Sandeep Chauhan | Jiwaji University Gwalior M.P. (original) (raw)

Papers by Sandeep Chauhan

Journal of Applied Polymer Science, 2006

To modify acrylamide (AAm) hydrogels for specialty applications, it was copolymerized with 2-Hydr... more To modify acrylamide (AAm) hydrogels for specialty applications, it was copolymerized with 2-Hydroxypropyl methacrylate (HPMA) in different molar ratio at 25°C in 1:1 water–acetone solvent system, using ammonium persulphate (APS) and N,N,N,N-tetramethyl ethylene diamine (TEMED) initiator–accelerator system. Two series of hydrogels were thus prepared using two different crosslinkers—ethylene glycol dimethacrylate (EGDMA) and N,N-methylene bisacrylamide (N,N-MBAAm). To affect property profile of the hydrogels, concentration of HPMA was varied over a range of five concentrations from 3.5 to 28 mM. Hydrogels were further functionalized by partial hydrolysis with NaOH and Hofmann amide degradation reaction. FTIR, Nitrogen analysis, and SEM were used to establish monomer reactivity and structure relationship of the hydrogels. Metal ion uptake was studied as a function of various structural aspects of the hydrogels. Water uptake behavior of the hydrogels was studied at constant time, temperature, and pH, both pre and post metal loading. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3040–3049, 2006

Desalination, 2005

Networks based on extracted cellulose and its derivatives such as hydroxypropyl cellulose (HPC), ... more Networks based on extracted cellulose and its derivatives such as hydroxypropyl cellulose (HPC), cyanoethyl cellulose, hydroxyethyl cellulose, hydrazinodeoxy cellulose, cellulose phosphate with acrylamide (AAm) and N, N-methylene bisacrylamide synthesized by simultaneous ...

Bioresource Technology, 2008

Novel supports for use as cation and anion adsorbents were prepared from lignocellulosics using p... more Novel supports for use as cation and anion adsorbents were prepared from lignocellulosics using pine needles and their carboxymethylated forms by network/hydrogel formation with acrylamide and N,N-methylene bisacrylamide. The hydrogels thus prepared were further functionalized by partial alkaline hydrolysis with 0.5 N NaOH and were characterized by FTIR, SEM and nitrogen analysis. Adsorption of Fe 2+ on these hydrogels was carried as a function of time, temperature, pH and ionic strength. The hydrogel having the maximum adsorption capacity was loaded with Fe 2+ at the conditions those afforded maximum uptake and was used as novel anionic adsorbent for NO À 3 . The water uptake capacities and biodegradability of the hydrogels before and after the ion loading was studied to evaluate the possible end-uses of these hydrogels as alternate materials in the removal of ionic species from water.

Journal of Applied Polymer Science, 2007

Microbial lipases (E.C. 3.1.1.3) are preferred biocatalysts for the synthesis of esters in organi... more Microbial lipases (E.C. 3.1.1.3) are preferred biocatalysts for the synthesis of esters in organic solvents. Various extracellular thermoalkaliphilic lipases have been reported from Pseudomonas sp. In the present study, a purified alkaline thermoalkalophilic extracellular lipase of Pseudomonas aeruginosa MTCC-4713 was efficiently immobilized onto a synthetic poly(AAc-co-HPMA-cl-EGDMA) hydrogel by adsorption and the bound lipase was evaluated for its hydrolytic potential towards various p-nitrophenyl acyl esters varying in their C-chain lengths. The bound lipase showed optimal hydrolytic activity towards p-nitrophenyl palmitate (p-NPP) at pH 8.5 and temperature 45°C. The hydrolytic activity of the hydrogel-bound lipase was markedly enhanced by the presence of Hg2+, Fe3+, and NH salt ions in that order. The hydrogel-immobilized lipase (25 mg) was used to perform esterification in various n-alkane(s) that resulted in ∼ 84.9 mM of methyl acrylate at 45°C in n-heptane under shaking (120 rpm) after 6 h, when methanol and acrylic acid were used in a ratio of 100 mM:100 mM, respectively. Addition of a molecular sieve (3Å × 1.5 mm) to the reaction system at a concentration of 100 mg/reaction vol (1 mL) resulted in a moderate enhancement in conversion of reactants into methyl acrylate (85.6 mM). During the repetitive esterification under optimum conditions, the hydrogel-bound lipase produced 71.3 mM of ester after 10th cycle of reuse. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 183–191, 2007

Journal of Applied Polymer Science, 2006

In continuation to our earlier work to use bioresource for developing alternate materials for use... more In continuation to our earlier work to use bioresource for developing alternate materials for use at the interface of biotechnology and polymer science, we have utilized pine needles as a renewable stock of cellulose to synthesize graft copolymers of vinyl imidazole. Kinetics of N-VIm by simultaneous γ-irradiation method has been investigated as a function of total dose, monomer concentration, and amount of water. Effect of water–methanol solvent composition on graft yields and polymerization kinetics has also been studied at the optimum grafting conditions of the total dose and monomer concentration. Effect of some additives such as ZnCl2, Mohr salt, tetramethylethylene diamine, potassium persulfate, ammonium persulfate as grafting accelerators and promoters has also been studied. Graft copolymers have been characterized by elemental analysis, FTIR, and swelling studies. The graft copolymers have been used as supports for metal ions sorption, enzyme immobilization, and as potential biomimicking catalysts. Sorption behavior of Fe2+ ions and Cu2+ ions and the immobilization of bovine serum albumin and protease as a function of graft yield has been reported. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1522–1530, 2006

Journal of Applied Polymer Science, 2006

An alkaline thermotolerant bacterial lipase of Bacillus coagulans MTCC-6375 was purified and immo... more An alkaline thermotolerant bacterial lipase of Bacillus coagulans MTCC-6375 was purified and immobilized on a methacrylic acid and dodecyl methacrylate (MAc-DMA) hydrogel. The lipase was optimally bound to the matrix after 20 min of incubation at 55°C and pH 9 under shaking conditions. The matrix-bound lipase retained approximately 50% of its initial activity at 70–80°C after 3 h of incubation. The immobilized lipase was highly active on medium chain length p-nitrophenyl acyl ester (C: 8, p-nitrophenyl caprylate) than other p-nitrophenyl acyl esters. The presence of Fe3+, NH4+, K+, and Zn2+ ions at 1 mM concentration in the reaction mixture resulted in a profound increase in the activity of immobilized lipase. Most of the detergents partially reduced the activity of the immobilized lipase. The immobilized lipase performed ∼62% conversion in 12 h at temperature 55°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1420–1426, 2006

Journal of Applied Polymer Science, 2008

In this article, we describe a novel pH-and temperature-sensitive and moderately salt tolerant hy... more In this article, we describe a novel pH-and temperature-sensitive and moderately salt tolerant hydrogels based on acrylic acid (AAc) and methacrylic acid (MAAc) by employing a novel research plan. AAc and MAAc have been converted to N-isopropylacrylamide (N-i-PAAm) and N-isopropyl methacrylamide (N-i-PMAAm), respectively, via amidation with isopropyl amine, followed by polymerization to respective polymers. These polymers were further converted into networks in the presence of AAc and MAAc and N,N-methylene bisacrylamide (N,N-MBAAm). The networks thus formed consist of both amides and carboxylic acid groups. Characterization of these networks has been carried out by nitrogen analysis, FTIR, NMR, and scanning electron microscopy for the investigation of different structural aspects of the synthesized polymers. Swelling studies of these networks have been carried out as a function of time, temperature, pH, and in the presence of additives, sodium dodecyl sulfate, cetyl trimethyl ammonium bromide, and 5% NaCl solution. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Journal of Applied Polymer Science, 2007

To design efficient polymeric supports for lipase immobilization, two series of hydrogels based o... more To design efficient polymeric supports for lipase immobilization, two series of hydrogels based on acrylamide and three methacrylates were prepared via crosslinking with ethylene glycol methacrylate and N,N-methylenebisacrylamide. The three methacrylates used to prepare these hydrogels had different alkyl chain lengths: C1 (methyl methacrylate), C12 (dodecyl methacrylate), and C18 (octadecyl methacrylate). In the reaction scheme, only the feed concentration of the hydrophobic component (methacrylate) was varied. The characterization of the hydrogels was carried out with Fourier transform infrared, scanning electron microscopy, and nitrogen analysis to establish their structural aspects and to obtain evidence for network formation; the swelling and water uptake of the hydrogels were studied as functions of the time, temperature, and pH. Lipase immobilization on selected hydrogels was studied as a function of the concentration of the methacrylate used in the feed and the nature of the crosslinker. The activity of the hydrogel series that showed the highest activity of the immobilized lipase was investigated further as a function of the methacrylate feed concentration, pH, and temperature. Some organic solvents were studied to investigate the effect of the nature of the solvent on the activity of the immobilized lipase. The activity of the immobilized lipase was more than that of the free lipase and was affected by the structural attributes of the polymeric supports and by the nature of the solvent. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Carbohydrate Polymers, 2007

Pine needles and their carboxymethyl forms were functionalized by network formation with 2-acryla... more Pine needles and their carboxymethyl forms were functionalized by network formation with 2-acrylamido-2-methylpropanesulphonic acid (AAmPSA) in the presence of N,N-methylene bisacrylamide. N-Tetramethylethylene diamine and ammonium persulfate were used as accelerator-initiator systems to prepare these hydrogels. The hydrogels were characterized by FTIR, SEM, and nitrogen analysis and for water uptake capacities before and after metal ion sorption with a view to evaluating their use in the removal of toxic ionic species from waste water. A detailed study of Cr 6+ adsorption was carried out as a function of time, temperature, pH, and ionic strength. The thermodynamic parameters of adsorption such as DH 0 , DS 0 , and DG 0 have been evaluated to understand the underlying mechanism of adsorption. In order to understand their reusability in possible technological applications, biodegradability of these hydrogels and their precursors was studied.

Annals of Cardiac Anaesthesia, 2007

Chest tube removal in the postcardiac surgical patients is a painful and distressful event. Fenta... more Chest tube removal in the postcardiac surgical patients is a painful and distressful event. Fentanyl and sufentanil have not been used for pain control during chest tube removal in the postoperative period. We compared efficacy offentanyl and sufentanil in controlling pain due to chest tube removal. One hundred and forty one adult patients undergoing cardiac surgery were recruited in a prospective, randomized, double blind, placebo controlled study. Patients were randomized to receive either 2 microg/Kg fentanyl IV or 0.2 microg/Kg sufentanil IV or 2 ml isotonic normal saline, 10 min before removing chest tubes. Pain intensity was assessed by measuring visual analog scale pain score 10 minutes before removing chest tubes and 5 min and 20 min after removing chest tubes. Level of sedation, heart rate, arterial pressure, oxygen saturation, and respiratory rate were recorded by a blinded observer at the same time intervals. Mean pain intensity scores 10 minutes before removal of chest tubes infentanyl, sufentanil and control groups were 23.88+/-5.2, 25.10+/-5.39 and 23.64+/-6.10 respectively. The pain scores 5 minutes after chest tube removal were reduced to 20.11+/-6.9 (p<0.05) in the fentanyl group and 13.60+/-6.60 (p<0.05) in the sufentanil group, whereas in control group pain scores increased to 27.97+/-8.39 (p<O.05). The pain scores in sufentanil group were significantly lower compared with fentanyl or control group. Sedation scores remained low in all groups and patients remained alert and none of the patients showed any adverse effects of opioids. Heart rate, arterial pressure and respiratory rate had least variations in sufentanil group than fentanyl or control group.

Journal of Cardiothoracic and Vascular Anesthesia, 2009

Hypothermia followed by rewarming during cardiopulmonary bypass can lead to cerebral hyperthermia... more Hypothermia followed by rewarming during cardiopulmonary bypass can lead to cerebral hyperthermia, which has been implicated as 1 of the causes for postoperative deterioration in neurocognitive function in patients undergoing coronary revascularization. Hence, the authors studied the effects of 2 different rewarming strategies on postoperative neurocognitive function in adult patients undergoing coronary artery bypass graft surgery with the aid of cardiopulmonary bypass. This was a randomized clinical trial. A cardiothoracic center of a tertiary level referral, teaching hospital. A total of 80 adult patients aged 45 to 70 years undergoing elective primary isolated coronary artery bypass graft surgery with cardiopulmonary bypass under moderate hypothermia at 30 degrees C were included in this study. The patients were randomly allocated into 2 groups of 40 each. In group A, patients were rewarmed to a nasopharyngeal temperature of 37 degrees C; whereas, in group B, patients were rewarmed to a nasopharyngeal temperature of 33 degrees C before weaning off bypass. The anesthetic and bypass management were standardized for both groups. All patients were assessed for neurocognitive function preoperatively and on the fifth postoperative day using the Post Graduate Institute Memory Scale. The amount of blood loss and need for blood and blood product transfusion postoperatively, the need for pacing, increased inotrope or vasodilator use, and time to extubation were also noted. Serum S100beta levels were measured after anesthetic induction and at 24 hours postoperatively. The jugular venous oxygen saturation and oxygen tension were noted at 30 degrees C and at the end of full rewarming (ie, at 37 degrees C or 33 degrees C, respectively, in the 2 groups). There was a significant deterioration in neurocognitive function postoperatively as compared with preoperative function in patients of group A (37 degrees C). This was associated with higher S100beta levels 24 hours postoperatively in group A (37 degrees C) compared with group B (33 degrees C) patients. Also, there was a significant decrease in jugular venous oxygen saturation in group A (37 degrees C) as compared with group B (33 degrees C) at the end of rewarming. The time to extubation was longer in group B (33 degrees C). No significant differences were noted in the amount of postoperative blood loss, blood and blood product use, inotrope or vasodilator use, and the need for pacing. Weaning from CPB at 33 degrees C may be a simple and useful strategy to lower the postoperative impairment of neurocognitive function and may be used as a tool to decrease morbidity after coronary revascularization.

Journal of Cardiothoracic and Vascular Anesthesia, 2001

1. J Cardiothorac Vasc Anesth. 2001 Jun;15(3):377-80. Case 6--2001: Exsanguinating endotracheal h... more 1. J Cardiothorac Vasc Anesth. 2001 Jun;15(3):377-80. Case 6--2001: Exsanguinating endotracheal hemorrhage during cardiopulmonary bypass. Chauhan S, Rao BH, Sahoo M, Raizada N, Saxena N, Slinger P, Barash P. ...

Annals of Thoracic Surgery, 2000

Background. Aprotinin and epsilon aminocaproic acid are antifibrinolytic agents used to reduce po... more Background. Aprotinin and epsilon aminocaproic acid are antifibrinolytic agents used to reduce postoperative blood loss after cardiopulmonary bypass. We compared low dose aprotinin with epsilon aminocaproic acid and a combination of the two agents to reduce postoperative blood loss in infants with congenital cyanotic heart disease undergoing corrective surgical procedures.

Journal of Cardiothoracic and Vascular Anesthesia, 2007

Cyanotic congenital heart diseases (CCHD) with secondary polycythemia and hyperviscosity state ar... more Cyanotic congenital heart diseases (CCHD) with secondary polycythemia and hyperviscosity state are associated with a reduction in blood flow, stagnation of blood, and thrombosis. Sufficient hemodilution in cyanotic children results in higher blood flow and significant reductions in perioperative blood loss. The aim of this study was to investigate similar beneficial effects of hemodilution in preventing shunt thrombosis and decreasing postoperative blood loss after modified Blalock-Taussig (BT) shunt operations in children with CCHD. Prospective, randomized, controlled study. Cardiac center of a tertiary care, referral hospital. Fifty children with CCHD undergoing modified BT shunt operations. Patients were randomized into 2 groups. The study group (n = 25) received a calculated amount of 6% hydroxyethyl starch (200/0.5) solution to bring down the hematocrit to 45%, whereas the control group (n = 25) received 5% dextrose solution intraoperatively as per the authors' normal protocol. Effects of hemodilution on shunt patency, postoperative blood loss at 24 hours, blood and blood component usage, and re-exploration rates were recorded. The shunt patency rate was significantly higher in the study group than the control group (100% and 84%, respectively, p < 0.05). Postoperative blood loss at 24 hours was significantly higher in the control group than in the study group (14.4 +/- 11.8 mL/kg and 9.9 +/- 8 mL/kg, respectively, p < 0.05). The number of recipients and the amount of blood and blood components administered were higher in the control group, but they were not statistically significant. The re-exploration rate (for excessive postoperative chest-tube drainage) was significantly higher in the control group than the study group (12% and 0%, respectively, p < 0.05). Hemodilution in CCHD patients undergoing modified BT shunt surgery has beneficial effects including improved shunt patency because of higher blood flow through the graft and less postoperative blood loss, which may be attributed to the lower viscosity produced by hemodilution.

Journal of Cardiothoracic and Vascular Anesthesia, 2000

Objective: To determine if quicker cardiac standstill obtained by adding adenosine to potassium c... more Objective: To determine if quicker cardiac standstill obtained by adding adenosine to potassium crystalloid cardioplegia translated into better myocardial preservation and cardiac function in the early postoperative period compared with the same cardioplegia without adenosine.

European Journal of Cardio-thoracic Surgery, 2009

Objective: Hypothermia conventionally used in cardiopulmonary bypass necessitates rewarming to no... more Objective: Hypothermia conventionally used in cardiopulmonary bypass necessitates rewarming to normothermic temperatures, which has been shown to be associated with neuropsychological injury. We studied the effects of two different rewarming strategies on postoperative neuropsychological function in cyanotic paediatric patients undergoing elective primary intracardiac repair of tetralogy of Fallot with the aid of cardiopulmonary bypass. Methods: This was a randomised clinical study undertaken in the cardiothoracic centre of a tertiary level referral and teaching hospital. Eighty children, aged 6-15 years undergoing elective primary intracardiac repair of tetralogy of Fallot using cardiopulmonary bypass under moderate hypothermia at 28 8C were included in this study. The patients were randomly allocated into two groups of 40 each. Group 1 patients were rewarmed to a nasopharyngeal temperature of 33 8C while group 2 patients were rewarmed to a nasopharyngeal temperature of 37 8C before weaning them off cardiopulmonary bypass. The anaesthetic and bypass management was standardised for both the groups. All patients were assessed for neuropsychological function preoperatively and on the fifth postoperative day using the MISIC tests. The amount of blood loss and need for blood and blood product transfusion postoperatively, need for pacing, increased inotropes or vasodilator use and time to extubation were also noted. Serum s-100b levels were measured post anaesthetic induction and at 24 h postoperatively. Results: There was a significant deterioration in neuropsychological function postoperatively in the patients in group 2 (37 8C) as compared to their preoperative function. This was associated with higher s-100b levels 24 h postoperatively in group 2 (37 8C) compared to group 1 (33 8C) patients. The time to extubation was longer in group 1 (33 8C). No significant differences were noted in the amount of postoperative blood loss, blood and blood product use, inotrope or vasodilator use and the need for pacing. Conclusion: Weaning off bypass at 33 8C is associated with lesser postoperative neuropsychological dysfunction compared to rewarming to 37 8C before weaning off bypass. This may be used as a tool to decrease neurologic morbidity following cardiac surgery in children with congenital cyanotic heart disease. #

European Journal of Cardio-thoracic Surgery, 2001

Objectives: While the role of adenosine pretreatment in animals has been well established, the ro... more Objectives: While the role of adenosine pretreatment in animals has been well established, the role in humans has been controversial. We performed this prospective, randomized study to ®nd out the usefulness of adenosine pretreatment in humans. Patients and methods: Twenty patients undergoing coronary artery bypass surgery for severe triple vessel disease and left ventricular dysfunction (ejection fraction , 35%) formed the study population. The adenosine group (n 10) received adenosine infusion (200 mg/kg) before aortic cross-clamp. The control group (n 10) received only normal saline injection. Cardiac function indices were assessed post-operatively. Results: In the adenosine group there was a signi®cant increase in cardiac output in the post-operative period from 3.46^1.06 to 4.46^0.92 l/min (P p 0:05). The cardiac index increased signi®cantly in the adenosine group from 1.97^0.43 to 2.54^0.5 l/min per m 2 (P p 0:05) and even when compared with the control group this increase was signi®cant (adenosine group vs. control group, P 0:03). Systemic vascular resistance fell from 1898.8^558.4 to 1134.9^530.7 dyne/s per cm 25 (P p 0:05) in the adenosine group. The pulmonary artery wedge pressure fell signi®cantly in the adenosine group from 11.1^5.0 to 7.2^2.6 mmHg (P p 0:05). Patients in the adenosine group maintained a lesser increase in resting heart rate post-operatively (96.1^13.4 to 114.1^18.7 beats/min) (P 0:7), as compared to the control group where the increase in the heart rate was signi®cant (77.1^8.3 to 109.7^14.9 beats/min) (P p 0:05). In the adenosine group only one patient (10%) had a raised creatine phosphokinase (MB) level at 12 h post-operatively as compared to three patients (30%) in the control group (P , 0:05). Conclusions: Adenosine pretreatment appears to protect against reperfusion injury in human hearts and thus results in improved post-operative haemodynamics. q

Journal of Cardiothoracic and Vascular Anesthesia, 2004

This study compared the efficacy of aminocaproic acid and tranexamic acid in reducing postoperati... more This study compared the efficacy of aminocaproic acid and tranexamic acid in reducing postoperative blood loss, as well as blood and blood product requirements in children with cyanotic congenital heart disease. A prospective randomized study. Cardiac center of a tertiary care, referral hospital. One hundred fifty children in the age group of 2 months to 14.5 years with cyanotic congenital heart disease undergoing corrective surgery on cardiopulmonary bypass (CPB). Patients were randomized into 3 groups. Group A was given aminocaproic acid in a dose of 100 mg/kg after anesthetic induction, 100 mg/kg on CPB and 100 mg/kg after protamine. Group T was given tranexamic acid, 10 mg/kg, after anesthetic induction, 10 mg/kg on CPB, and 10 mg/kg after protamine. Group C was the control group. Control group had the longest sternal closure time, maximum blood loss at 24 hours, and maximum requirements of blood and blood products. Among the 2 groups given antifibrinolytics, there was no significant difference in postoperative blood loss, blood and product requirement, and reexploration rates. Aminocaproic acid and tranexamic acid are equally effective in reducing postoperative blood loss, as well as blood and blood product requirements in children with cyanotic heart disease undergoing corrective surgery as compared with the control group.

Heart Lung and Circulation, 2006

We report two cases of mitral stenosis after Duran ring annuloplasty for myxomatous mitral regurg... more We report two cases of mitral stenosis after Duran ring annuloplasty for myxomatous mitral regurgitation. Simple explantation of the ring provided relief of mitral stenosis.

The Japanese Journal of Thoracic and Cardiovascular Surgery, 2007

Objective The aim of this study was to review short- and long-term outcomes following total corre... more Objective The aim of this study was to review short- and long-term outcomes following total correction in patients with tetralogy of Fallot that presented during adulthood. Methods It was a retrospective analysis of 284 patients (aged 14–50 years, mean 19.4 ± 2.5 years) with tetralogy of Fallot who underwent total correction at our institution between January 1991 and December 2001. Thirty patients were subjected to postoperative first-pass radionuclide angiocardiography scans. A Hindi version of the standard World Health Organization quality of life proforma was mailed to 120 patients operated on during the first half of the study period. Results Altogether, 45 (15.8%) patients had palliative shunts, and 32 (11%) had preoperative coil embolization. The transatrial/transpulmonary artery approach was used in 62 (22%) patients, the transventricular approach in 86 (30%) patients, and a combined approach in 136 (48%) patients. A transannular pericardial patch was used in 200 (70%) patients. A total of 61 (21%) patients had nonfatal complications. There were 28 hospital deaths. Follow-up ranged from 1 month to 10 years (mean 4.6 ± 2.3 years). There were 7 (2.5%) late deaths and 6 (2.1%) reoperations. Altogether, 94% of patients were in New Yk Heart Association (NYHA) class I. Radionuclide angiocardiography showed normal right ventricular and left ventricular function in 18 (60%) and 22 (73%) patients, respectively. All of the 66 respondents perceived an improved quality of life. The actuarial survival and freedom from reoperation at 10 years were 82.88% ± 3.80% and 92.82% ± 3.40%, respectively. Conclusion Total correction in this subset of patients offers the best option for long-term symptom-free survival.

Journal of Applied Polymer Science, 2006

To modify acrylamide (AAm) hydrogels for specialty applications, it was copolymerized with 2-Hydr... more To modify acrylamide (AAm) hydrogels for specialty applications, it was copolymerized with 2-Hydroxypropyl methacrylate (HPMA) in different molar ratio at 25°C in 1:1 water–acetone solvent system, using ammonium persulphate (APS) and N,N,N,N-tetramethyl ethylene diamine (TEMED) initiator–accelerator system. Two series of hydrogels were thus prepared using two different crosslinkers—ethylene glycol dimethacrylate (EGDMA) and N,N-methylene bisacrylamide (N,N-MBAAm). To affect property profile of the hydrogels, concentration of HPMA was varied over a range of five concentrations from 3.5 to 28 mM. Hydrogels were further functionalized by partial hydrolysis with NaOH and Hofmann amide degradation reaction. FTIR, Nitrogen analysis, and SEM were used to establish monomer reactivity and structure relationship of the hydrogels. Metal ion uptake was studied as a function of various structural aspects of the hydrogels. Water uptake behavior of the hydrogels was studied at constant time, temperature, and pH, both pre and post metal loading. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3040–3049, 2006

Desalination, 2005

Networks based on extracted cellulose and its derivatives such as hydroxypropyl cellulose (HPC), ... more Networks based on extracted cellulose and its derivatives such as hydroxypropyl cellulose (HPC), cyanoethyl cellulose, hydroxyethyl cellulose, hydrazinodeoxy cellulose, cellulose phosphate with acrylamide (AAm) and N, N-methylene bisacrylamide synthesized by simultaneous ...

Bioresource Technology, 2008

Novel supports for use as cation and anion adsorbents were prepared from lignocellulosics using p... more Novel supports for use as cation and anion adsorbents were prepared from lignocellulosics using pine needles and their carboxymethylated forms by network/hydrogel formation with acrylamide and N,N-methylene bisacrylamide. The hydrogels thus prepared were further functionalized by partial alkaline hydrolysis with 0.5 N NaOH and were characterized by FTIR, SEM and nitrogen analysis. Adsorption of Fe 2+ on these hydrogels was carried as a function of time, temperature, pH and ionic strength. The hydrogel having the maximum adsorption capacity was loaded with Fe 2+ at the conditions those afforded maximum uptake and was used as novel anionic adsorbent for NO À 3 . The water uptake capacities and biodegradability of the hydrogels before and after the ion loading was studied to evaluate the possible end-uses of these hydrogels as alternate materials in the removal of ionic species from water.

Journal of Applied Polymer Science, 2007

Microbial lipases (E.C. 3.1.1.3) are preferred biocatalysts for the synthesis of esters in organi... more Microbial lipases (E.C. 3.1.1.3) are preferred biocatalysts for the synthesis of esters in organic solvents. Various extracellular thermoalkaliphilic lipases have been reported from Pseudomonas sp. In the present study, a purified alkaline thermoalkalophilic extracellular lipase of Pseudomonas aeruginosa MTCC-4713 was efficiently immobilized onto a synthetic poly(AAc-co-HPMA-cl-EGDMA) hydrogel by adsorption and the bound lipase was evaluated for its hydrolytic potential towards various p-nitrophenyl acyl esters varying in their C-chain lengths. The bound lipase showed optimal hydrolytic activity towards p-nitrophenyl palmitate (p-NPP) at pH 8.5 and temperature 45°C. The hydrolytic activity of the hydrogel-bound lipase was markedly enhanced by the presence of Hg2+, Fe3+, and NH salt ions in that order. The hydrogel-immobilized lipase (25 mg) was used to perform esterification in various n-alkane(s) that resulted in ∼ 84.9 mM of methyl acrylate at 45°C in n-heptane under shaking (120 rpm) after 6 h, when methanol and acrylic acid were used in a ratio of 100 mM:100 mM, respectively. Addition of a molecular sieve (3Å × 1.5 mm) to the reaction system at a concentration of 100 mg/reaction vol (1 mL) resulted in a moderate enhancement in conversion of reactants into methyl acrylate (85.6 mM). During the repetitive esterification under optimum conditions, the hydrogel-bound lipase produced 71.3 mM of ester after 10th cycle of reuse. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 183–191, 2007

Journal of Applied Polymer Science, 2006

In continuation to our earlier work to use bioresource for developing alternate materials for use... more In continuation to our earlier work to use bioresource for developing alternate materials for use at the interface of biotechnology and polymer science, we have utilized pine needles as a renewable stock of cellulose to synthesize graft copolymers of vinyl imidazole. Kinetics of N-VIm by simultaneous γ-irradiation method has been investigated as a function of total dose, monomer concentration, and amount of water. Effect of water–methanol solvent composition on graft yields and polymerization kinetics has also been studied at the optimum grafting conditions of the total dose and monomer concentration. Effect of some additives such as ZnCl2, Mohr salt, tetramethylethylene diamine, potassium persulfate, ammonium persulfate as grafting accelerators and promoters has also been studied. Graft copolymers have been characterized by elemental analysis, FTIR, and swelling studies. The graft copolymers have been used as supports for metal ions sorption, enzyme immobilization, and as potential biomimicking catalysts. Sorption behavior of Fe2+ ions and Cu2+ ions and the immobilization of bovine serum albumin and protease as a function of graft yield has been reported. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1522–1530, 2006

Journal of Applied Polymer Science, 2006

An alkaline thermotolerant bacterial lipase of Bacillus coagulans MTCC-6375 was purified and immo... more An alkaline thermotolerant bacterial lipase of Bacillus coagulans MTCC-6375 was purified and immobilized on a methacrylic acid and dodecyl methacrylate (MAc-DMA) hydrogel. The lipase was optimally bound to the matrix after 20 min of incubation at 55°C and pH 9 under shaking conditions. The matrix-bound lipase retained approximately 50% of its initial activity at 70–80°C after 3 h of incubation. The immobilized lipase was highly active on medium chain length p-nitrophenyl acyl ester (C: 8, p-nitrophenyl caprylate) than other p-nitrophenyl acyl esters. The presence of Fe3+, NH4+, K+, and Zn2+ ions at 1 mM concentration in the reaction mixture resulted in a profound increase in the activity of immobilized lipase. Most of the detergents partially reduced the activity of the immobilized lipase. The immobilized lipase performed ∼62% conversion in 12 h at temperature 55°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1420–1426, 2006

Journal of Applied Polymer Science, 2008

In this article, we describe a novel pH-and temperature-sensitive and moderately salt tolerant hy... more In this article, we describe a novel pH-and temperature-sensitive and moderately salt tolerant hydrogels based on acrylic acid (AAc) and methacrylic acid (MAAc) by employing a novel research plan. AAc and MAAc have been converted to N-isopropylacrylamide (N-i-PAAm) and N-isopropyl methacrylamide (N-i-PMAAm), respectively, via amidation with isopropyl amine, followed by polymerization to respective polymers. These polymers were further converted into networks in the presence of AAc and MAAc and N,N-methylene bisacrylamide (N,N-MBAAm). The networks thus formed consist of both amides and carboxylic acid groups. Characterization of these networks has been carried out by nitrogen analysis, FTIR, NMR, and scanning electron microscopy for the investigation of different structural aspects of the synthesized polymers. Swelling studies of these networks have been carried out as a function of time, temperature, pH, and in the presence of additives, sodium dodecyl sulfate, cetyl trimethyl ammonium bromide, and 5% NaCl solution. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Journal of Applied Polymer Science, 2007

To design efficient polymeric supports for lipase immobilization, two series of hydrogels based o... more To design efficient polymeric supports for lipase immobilization, two series of hydrogels based on acrylamide and three methacrylates were prepared via crosslinking with ethylene glycol methacrylate and N,N-methylenebisacrylamide. The three methacrylates used to prepare these hydrogels had different alkyl chain lengths: C1 (methyl methacrylate), C12 (dodecyl methacrylate), and C18 (octadecyl methacrylate). In the reaction scheme, only the feed concentration of the hydrophobic component (methacrylate) was varied. The characterization of the hydrogels was carried out with Fourier transform infrared, scanning electron microscopy, and nitrogen analysis to establish their structural aspects and to obtain evidence for network formation; the swelling and water uptake of the hydrogels were studied as functions of the time, temperature, and pH. Lipase immobilization on selected hydrogels was studied as a function of the concentration of the methacrylate used in the feed and the nature of the crosslinker. The activity of the hydrogel series that showed the highest activity of the immobilized lipase was investigated further as a function of the methacrylate feed concentration, pH, and temperature. Some organic solvents were studied to investigate the effect of the nature of the solvent on the activity of the immobilized lipase. The activity of the immobilized lipase was more than that of the free lipase and was affected by the structural attributes of the polymeric supports and by the nature of the solvent. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Carbohydrate Polymers, 2007

Pine needles and their carboxymethyl forms were functionalized by network formation with 2-acryla... more Pine needles and their carboxymethyl forms were functionalized by network formation with 2-acrylamido-2-methylpropanesulphonic acid (AAmPSA) in the presence of N,N-methylene bisacrylamide. N-Tetramethylethylene diamine and ammonium persulfate were used as accelerator-initiator systems to prepare these hydrogels. The hydrogels were characterized by FTIR, SEM, and nitrogen analysis and for water uptake capacities before and after metal ion sorption with a view to evaluating their use in the removal of toxic ionic species from waste water. A detailed study of Cr 6+ adsorption was carried out as a function of time, temperature, pH, and ionic strength. The thermodynamic parameters of adsorption such as DH 0 , DS 0 , and DG 0 have been evaluated to understand the underlying mechanism of adsorption. In order to understand their reusability in possible technological applications, biodegradability of these hydrogels and their precursors was studied.

Annals of Cardiac Anaesthesia, 2007

Chest tube removal in the postcardiac surgical patients is a painful and distressful event. Fenta... more Chest tube removal in the postcardiac surgical patients is a painful and distressful event. Fentanyl and sufentanil have not been used for pain control during chest tube removal in the postoperative period. We compared efficacy offentanyl and sufentanil in controlling pain due to chest tube removal. One hundred and forty one adult patients undergoing cardiac surgery were recruited in a prospective, randomized, double blind, placebo controlled study. Patients were randomized to receive either 2 microg/Kg fentanyl IV or 0.2 microg/Kg sufentanil IV or 2 ml isotonic normal saline, 10 min before removing chest tubes. Pain intensity was assessed by measuring visual analog scale pain score 10 minutes before removing chest tubes and 5 min and 20 min after removing chest tubes. Level of sedation, heart rate, arterial pressure, oxygen saturation, and respiratory rate were recorded by a blinded observer at the same time intervals. Mean pain intensity scores 10 minutes before removal of chest tubes infentanyl, sufentanil and control groups were 23.88+/-5.2, 25.10+/-5.39 and 23.64+/-6.10 respectively. The pain scores 5 minutes after chest tube removal were reduced to 20.11+/-6.9 (p<0.05) in the fentanyl group and 13.60+/-6.60 (p<0.05) in the sufentanil group, whereas in control group pain scores increased to 27.97+/-8.39 (p<O.05). The pain scores in sufentanil group were significantly lower compared with fentanyl or control group. Sedation scores remained low in all groups and patients remained alert and none of the patients showed any adverse effects of opioids. Heart rate, arterial pressure and respiratory rate had least variations in sufentanil group than fentanyl or control group.

Journal of Cardiothoracic and Vascular Anesthesia, 2009

Hypothermia followed by rewarming during cardiopulmonary bypass can lead to cerebral hyperthermia... more Hypothermia followed by rewarming during cardiopulmonary bypass can lead to cerebral hyperthermia, which has been implicated as 1 of the causes for postoperative deterioration in neurocognitive function in patients undergoing coronary revascularization. Hence, the authors studied the effects of 2 different rewarming strategies on postoperative neurocognitive function in adult patients undergoing coronary artery bypass graft surgery with the aid of cardiopulmonary bypass. This was a randomized clinical trial. A cardiothoracic center of a tertiary level referral, teaching hospital. A total of 80 adult patients aged 45 to 70 years undergoing elective primary isolated coronary artery bypass graft surgery with cardiopulmonary bypass under moderate hypothermia at 30 degrees C were included in this study. The patients were randomly allocated into 2 groups of 40 each. In group A, patients were rewarmed to a nasopharyngeal temperature of 37 degrees C; whereas, in group B, patients were rewarmed to a nasopharyngeal temperature of 33 degrees C before weaning off bypass. The anesthetic and bypass management were standardized for both groups. All patients were assessed for neurocognitive function preoperatively and on the fifth postoperative day using the Post Graduate Institute Memory Scale. The amount of blood loss and need for blood and blood product transfusion postoperatively, the need for pacing, increased inotrope or vasodilator use, and time to extubation were also noted. Serum S100beta levels were measured after anesthetic induction and at 24 hours postoperatively. The jugular venous oxygen saturation and oxygen tension were noted at 30 degrees C and at the end of full rewarming (ie, at 37 degrees C or 33 degrees C, respectively, in the 2 groups). There was a significant deterioration in neurocognitive function postoperatively as compared with preoperative function in patients of group A (37 degrees C). This was associated with higher S100beta levels 24 hours postoperatively in group A (37 degrees C) compared with group B (33 degrees C) patients. Also, there was a significant decrease in jugular venous oxygen saturation in group A (37 degrees C) as compared with group B (33 degrees C) at the end of rewarming. The time to extubation was longer in group B (33 degrees C). No significant differences were noted in the amount of postoperative blood loss, blood and blood product use, inotrope or vasodilator use, and the need for pacing. Weaning from CPB at 33 degrees C may be a simple and useful strategy to lower the postoperative impairment of neurocognitive function and may be used as a tool to decrease morbidity after coronary revascularization.

Journal of Cardiothoracic and Vascular Anesthesia, 2001

1. J Cardiothorac Vasc Anesth. 2001 Jun;15(3):377-80. Case 6--2001: Exsanguinating endotracheal h... more 1. J Cardiothorac Vasc Anesth. 2001 Jun;15(3):377-80. Case 6--2001: Exsanguinating endotracheal hemorrhage during cardiopulmonary bypass. Chauhan S, Rao BH, Sahoo M, Raizada N, Saxena N, Slinger P, Barash P. ...

Annals of Thoracic Surgery, 2000

Background. Aprotinin and epsilon aminocaproic acid are antifibrinolytic agents used to reduce po... more Background. Aprotinin and epsilon aminocaproic acid are antifibrinolytic agents used to reduce postoperative blood loss after cardiopulmonary bypass. We compared low dose aprotinin with epsilon aminocaproic acid and a combination of the two agents to reduce postoperative blood loss in infants with congenital cyanotic heart disease undergoing corrective surgical procedures.

Journal of Cardiothoracic and Vascular Anesthesia, 2007

Cyanotic congenital heart diseases (CCHD) with secondary polycythemia and hyperviscosity state ar... more Cyanotic congenital heart diseases (CCHD) with secondary polycythemia and hyperviscosity state are associated with a reduction in blood flow, stagnation of blood, and thrombosis. Sufficient hemodilution in cyanotic children results in higher blood flow and significant reductions in perioperative blood loss. The aim of this study was to investigate similar beneficial effects of hemodilution in preventing shunt thrombosis and decreasing postoperative blood loss after modified Blalock-Taussig (BT) shunt operations in children with CCHD. Prospective, randomized, controlled study. Cardiac center of a tertiary care, referral hospital. Fifty children with CCHD undergoing modified BT shunt operations. Patients were randomized into 2 groups. The study group (n = 25) received a calculated amount of 6% hydroxyethyl starch (200/0.5) solution to bring down the hematocrit to 45%, whereas the control group (n = 25) received 5% dextrose solution intraoperatively as per the authors' normal protocol. Effects of hemodilution on shunt patency, postoperative blood loss at 24 hours, blood and blood component usage, and re-exploration rates were recorded. The shunt patency rate was significantly higher in the study group than the control group (100% and 84%, respectively, p < 0.05). Postoperative blood loss at 24 hours was significantly higher in the control group than in the study group (14.4 +/- 11.8 mL/kg and 9.9 +/- 8 mL/kg, respectively, p < 0.05). The number of recipients and the amount of blood and blood components administered were higher in the control group, but they were not statistically significant. The re-exploration rate (for excessive postoperative chest-tube drainage) was significantly higher in the control group than the study group (12% and 0%, respectively, p < 0.05). Hemodilution in CCHD patients undergoing modified BT shunt surgery has beneficial effects including improved shunt patency because of higher blood flow through the graft and less postoperative blood loss, which may be attributed to the lower viscosity produced by hemodilution.

Journal of Cardiothoracic and Vascular Anesthesia, 2000

Objective: To determine if quicker cardiac standstill obtained by adding adenosine to potassium c... more Objective: To determine if quicker cardiac standstill obtained by adding adenosine to potassium crystalloid cardioplegia translated into better myocardial preservation and cardiac function in the early postoperative period compared with the same cardioplegia without adenosine.

European Journal of Cardio-thoracic Surgery, 2009

Objective: Hypothermia conventionally used in cardiopulmonary bypass necessitates rewarming to no... more Objective: Hypothermia conventionally used in cardiopulmonary bypass necessitates rewarming to normothermic temperatures, which has been shown to be associated with neuropsychological injury. We studied the effects of two different rewarming strategies on postoperative neuropsychological function in cyanotic paediatric patients undergoing elective primary intracardiac repair of tetralogy of Fallot with the aid of cardiopulmonary bypass. Methods: This was a randomised clinical study undertaken in the cardiothoracic centre of a tertiary level referral and teaching hospital. Eighty children, aged 6-15 years undergoing elective primary intracardiac repair of tetralogy of Fallot using cardiopulmonary bypass under moderate hypothermia at 28 8C were included in this study. The patients were randomly allocated into two groups of 40 each. Group 1 patients were rewarmed to a nasopharyngeal temperature of 33 8C while group 2 patients were rewarmed to a nasopharyngeal temperature of 37 8C before weaning them off cardiopulmonary bypass. The anaesthetic and bypass management was standardised for both the groups. All patients were assessed for neuropsychological function preoperatively and on the fifth postoperative day using the MISIC tests. The amount of blood loss and need for blood and blood product transfusion postoperatively, need for pacing, increased inotropes or vasodilator use and time to extubation were also noted. Serum s-100b levels were measured post anaesthetic induction and at 24 h postoperatively. Results: There was a significant deterioration in neuropsychological function postoperatively in the patients in group 2 (37 8C) as compared to their preoperative function. This was associated with higher s-100b levels 24 h postoperatively in group 2 (37 8C) compared to group 1 (33 8C) patients. The time to extubation was longer in group 1 (33 8C). No significant differences were noted in the amount of postoperative blood loss, blood and blood product use, inotrope or vasodilator use and the need for pacing. Conclusion: Weaning off bypass at 33 8C is associated with lesser postoperative neuropsychological dysfunction compared to rewarming to 37 8C before weaning off bypass. This may be used as a tool to decrease neurologic morbidity following cardiac surgery in children with congenital cyanotic heart disease. #

European Journal of Cardio-thoracic Surgery, 2001

Objectives: While the role of adenosine pretreatment in animals has been well established, the ro... more Objectives: While the role of adenosine pretreatment in animals has been well established, the role in humans has been controversial. We performed this prospective, randomized study to ®nd out the usefulness of adenosine pretreatment in humans. Patients and methods: Twenty patients undergoing coronary artery bypass surgery for severe triple vessel disease and left ventricular dysfunction (ejection fraction , 35%) formed the study population. The adenosine group (n 10) received adenosine infusion (200 mg/kg) before aortic cross-clamp. The control group (n 10) received only normal saline injection. Cardiac function indices were assessed post-operatively. Results: In the adenosine group there was a signi®cant increase in cardiac output in the post-operative period from 3.46^1.06 to 4.46^0.92 l/min (P p 0:05). The cardiac index increased signi®cantly in the adenosine group from 1.97^0.43 to 2.54^0.5 l/min per m 2 (P p 0:05) and even when compared with the control group this increase was signi®cant (adenosine group vs. control group, P 0:03). Systemic vascular resistance fell from 1898.8^558.4 to 1134.9^530.7 dyne/s per cm 25 (P p 0:05) in the adenosine group. The pulmonary artery wedge pressure fell signi®cantly in the adenosine group from 11.1^5.0 to 7.2^2.6 mmHg (P p 0:05). Patients in the adenosine group maintained a lesser increase in resting heart rate post-operatively (96.1^13.4 to 114.1^18.7 beats/min) (P 0:7), as compared to the control group where the increase in the heart rate was signi®cant (77.1^8.3 to 109.7^14.9 beats/min) (P p 0:05). In the adenosine group only one patient (10%) had a raised creatine phosphokinase (MB) level at 12 h post-operatively as compared to three patients (30%) in the control group (P , 0:05). Conclusions: Adenosine pretreatment appears to protect against reperfusion injury in human hearts and thus results in improved post-operative haemodynamics. q

Journal of Cardiothoracic and Vascular Anesthesia, 2004

This study compared the efficacy of aminocaproic acid and tranexamic acid in reducing postoperati... more This study compared the efficacy of aminocaproic acid and tranexamic acid in reducing postoperative blood loss, as well as blood and blood product requirements in children with cyanotic congenital heart disease. A prospective randomized study. Cardiac center of a tertiary care, referral hospital. One hundred fifty children in the age group of 2 months to 14.5 years with cyanotic congenital heart disease undergoing corrective surgery on cardiopulmonary bypass (CPB). Patients were randomized into 3 groups. Group A was given aminocaproic acid in a dose of 100 mg/kg after anesthetic induction, 100 mg/kg on CPB and 100 mg/kg after protamine. Group T was given tranexamic acid, 10 mg/kg, after anesthetic induction, 10 mg/kg on CPB, and 10 mg/kg after protamine. Group C was the control group. Control group had the longest sternal closure time, maximum blood loss at 24 hours, and maximum requirements of blood and blood products. Among the 2 groups given antifibrinolytics, there was no significant difference in postoperative blood loss, blood and product requirement, and reexploration rates. Aminocaproic acid and tranexamic acid are equally effective in reducing postoperative blood loss, as well as blood and blood product requirements in children with cyanotic heart disease undergoing corrective surgery as compared with the control group.

Heart Lung and Circulation, 2006

We report two cases of mitral stenosis after Duran ring annuloplasty for myxomatous mitral regurg... more We report two cases of mitral stenosis after Duran ring annuloplasty for myxomatous mitral regurgitation. Simple explantation of the ring provided relief of mitral stenosis.

The Japanese Journal of Thoracic and Cardiovascular Surgery, 2007

Objective The aim of this study was to review short- and long-term outcomes following total corre... more Objective The aim of this study was to review short- and long-term outcomes following total correction in patients with tetralogy of Fallot that presented during adulthood. Methods It was a retrospective analysis of 284 patients (aged 14–50 years, mean 19.4 ± 2.5 years) with tetralogy of Fallot who underwent total correction at our institution between January 1991 and December 2001. Thirty patients were subjected to postoperative first-pass radionuclide angiocardiography scans. A Hindi version of the standard World Health Organization quality of life proforma was mailed to 120 patients operated on during the first half of the study period. Results Altogether, 45 (15.8%) patients had palliative shunts, and 32 (11%) had preoperative coil embolization. The transatrial/transpulmonary artery approach was used in 62 (22%) patients, the transventricular approach in 86 (30%) patients, and a combined approach in 136 (48%) patients. A transannular pericardial patch was used in 200 (70%) patients. A total of 61 (21%) patients had nonfatal complications. There were 28 hospital deaths. Follow-up ranged from 1 month to 10 years (mean 4.6 ± 2.3 years). There were 7 (2.5%) late deaths and 6 (2.1%) reoperations. Altogether, 94% of patients were in New Yk Heart Association (NYHA) class I. Radionuclide angiocardiography showed normal right ventricular and left ventricular function in 18 (60%) and 22 (73%) patients, respectively. All of the 66 respondents perceived an improved quality of life. The actuarial survival and freedom from reoperation at 10 years were 82.88% ± 3.80% and 92.82% ± 3.40%, respectively. Conclusion Total correction in this subset of patients offers the best option for long-term symptom-free survival.