Bipin Mehta - Academia.edu (original) (raw)

Papers by Bipin Mehta

Clinical positron imaging, Oct 1, 1999

The uptake of FDG was measured before, during, and after fractionated radiation in order to evalu... more The uptake of FDG was measured before, during, and after fractionated radiation in order to evaluate the potential of FDG-PET imaging as an indicator of tumor response. Methods: The study was performed with nude rats bearing the human neuroblastoma BE(2)C tumor xenografts. Tumors were irradiated with 10 fractions of 2 Gy using a 320 kV p X-ray unit. Following a baseline FDG-PET scan, repeat scans were performed weekly until animal sacrifice. The rodents were given up to 10 FDG-PET scans, over a period of up to 75 days posttreatment. Results and Conclusions: Neither, the average and maximum activity/cc of FDG tumor uptake, nor the respective standardized uptake values (SUV), correlated with tumor response. Instead, the total FDG uptake (defined as the product of the average FDG activity/cc with the tumor volume) correlated better with tumor response.

British Journal of Nutrition, Mar 1, 1974

I. The effects of the protein content of the diet on the vitamin Blz concentration of serum and o... more I. The effects of the protein content of the diet on the vitamin Blz concentration of serum and of various tissues were studied in rats by means of microbiological and radioisotopic techniques. 2. Protein starvation reduced tissue weights and nitrogen contents, serum protein concentrations and haemoglobin values. 3. The vitamin BIB contents of the serum and of several organs and tissues were greater in the protein-starved animals for reasons that remain unexplained. 4. The retention of radioactive cyanocobalamin per g fresh weight was significantly greater in liver, kidney, spleen and brain in the protein-depleted rats than in those given adequate protein. However, the total tissue retention was not significantly different between these groups, so that there was a greater capacity for tissue binding and for body conservation of vitamin B,, in the protein-starved animals. In an earlier investigation on undernourished Indian children serum concentrations of vitamin B,, were found to be significantly raised (Satoskar, Kulkarni, Mehta, Sanzgiri & Bamji, 1962). This observation contrasts with reports of reduced serum concentrations of other vitamins, e.g. A, E, C, riboflavin, nicotinic acid and pteroylmonoglutamic acid in such subjects (Moore & Sharman, I951 ; Trowell, Moore &

Canadian Journal of Microbiology, Oct 1, 1970

Proflavine binding of a sensitive strain of Bacillus subtilis and of a resistant strain derived f... more Proflavine binding of a sensitive strain of Bacillus subtilis and of a resistant strain derived from it was compared. Proflavine was bound very rapidly and more was bound at 0 °C than at 37 °C. Boiling increased the proflavine-binding capacity at 37 °C of sensitive but not of resistant cells. The binding capacity of sensitive and resistant cells suspended in buffer was the same; this was also true in various growth media. If cells were able to grow in the presence of proflavine their proflavine content decreased.Bound proflavine was released when cells were treated with growth media or with the salts of growth media. Sodium salts of organic acids also caused a release. This effect seemed due to their Na+ content, and was somewhat higher for resistant than for sensitive cells. The mechanism of proflavine resistance in B. subtilis is probably different from that of Escherichia coli, which is thought to depend on an energy-driven release of bound proflavine.

Canadian Journal of Microbiology, May 1, 1970

A correlation has been observed between the degree of DNA–DNA (deoxyribonucleic acid) hybridizati... more A correlation has been observed between the degree of DNA–DNA (deoxyribonucleic acid) hybridization and the frequency of interspecific genetic transformation between Streptococcus species of serological groups D and H and Diplococcus pneumoniae. The thermal denaturation (Tm) values and guanine plus cytosine (G + C) mole percent for all cultures were similar. Two mutants of the group D streptococcus, resistant to the potent antileukemic drug amethopterin, were found to be more alike than any other two organisms studied. The intraspecific genetic transfer of the thymine-requirement marker in either direction was not successfully demonstrated. The lack of transformation of amethopterin resistance to the wild type organism was partially due to the lack of homology between the mutants and the wild type.

Journal of Neuro-oncology, 1983

Osteosarcoma patients free of CNS metastases are at risk for acquiring leukoencephalopathy after ... more Osteosarcoma patients free of CNS metastases are at risk for acquiring leukoencephalopathy after receiving multiple courses of high dose intravenous methotrexate followed by oral leucovorin rescue (MTX-LV). A prospective study of the adequacy of CNS rescue of MTX biochemical toxicity by oral leucovorin was undertaken in newly diagnosed neurologically normal osteosarcoma patients. Prior to surgical resection of the primary tumor, ten patients received 4 weekly courses of MTX-LV. During the fourth weekly MTX-LV treatment, 0 and 72 hr serum and CSF determinations of MTX, 5-methyl-tetrahydrofolate (5-MTHF) and LV were made. No CSF MTX was detectable at 0 hr in any patient, but a significant elevation in CSF MTX occurred in 9/9 patients at 72 hr (mean 47.2 +/- 31.8 ng/ml or 1.04 +/- 0.7 X 10(-7) M). There was no significant change in mean CSF 5-MTHF over 72 hr despite a rise in serum 5-MTHF. MTX exceeded 5-MTHF in 6/9 patients in CSF, whereas only 3/8 patients had higher MTX in the serum at 72 hr. No acute systemic or neurotoxicity was seen. The failure of oral leucovorin to consistently elevate CSF 5-MTHF levels at 72 hr in the context of significant levels of CSF MTX may result in intermittent CNS folate deficiency. The clinical and pathological syndrome of leukoencephalopathy may be related to this phenomenon and may evolve after repeated MTX-LV treatments.

Archives of Disease in Childhood, Feb 1, 1962

The syndrome of kwashiorkor is seen predominantly in countries where children suffer from nutriti... more The syndrome of kwashiorkor is seen predominantly in countries where children suffer from nutritional deficiencies, particularly of protein. In countries like India, where the diet is often deficient in animal protein, an associated vitamin B12 deficiency also occurs, and vitamin B12 and folic copyright.

Neurology, Sep 1, 1979

Intracarotid (i.c.) hyperosmolar mannitol enhances central nervous system (CNS) penetration of in... more Intracarotid (i.c.) hyperosmolar mannitol enhances central nervous system (CNS) penetration of intravenous (i.v.) methotrexate (MTX) in normal adult rats. A fivefold augmentation in the CSF:serum and ipsilateral brain:serum MTX concentration ratios was observed 1 hour after drug administration. Intravenous mannitol had no such effect. Rats with meningeal carcinomatosis have a partial defect in blood-brain barrier function, and the CSF:serum MTX concentration ratio was 4.6 times higher in these animals than in normal rats prior to mannitol therapy. Intracarotid hyperosmolar mannitol further augmented the blood-brain barrier permeability to intravenous MTX. Intracarotid mannitol increased the therapeutic effect of MTX, since rats with meningeal carcinomatosis that received i.v. MTX and i.c. mannitol experienced a slight enhancement in survival.

Proceedings of the National Academy of Sciences of the United States of America, Jan 25, 2005

Each of Ϸ24 g of pMDR1-EGFP (a kind gift by S. Simon, The Rockefeller University, New York) and 6... more Each of Ϸ24 g of pMDR1-EGFP (a kind gift by S. Simon, The Rockefeller University, New York) and 60 l of Lipofectamine were diluted in 1.5 ml of DMEM, mixed, incubated for 20 min at room temperature, and added to the cells in a 10-cm culture dish. Media was changed 6 h after transfection and cells were harvested

The New England Journal of Medicine, Jul 24, 1975

The kinetics and distribution of methotrexate in intraventricular and intrathecal cerebrospinal-f... more The kinetics and distribution of methotrexate in intraventricular and intrathecal cerebrospinal-fluid spaces were studied in patients with meningeal leukemia and meningeal carcinomatosis after drug administration by intravenous infusion, indwelling intraventricular subcutaneous reservoir (Ommaya), or standard lumbar puncture. Negligible ventricular concentrations followed a single intravenous dose. During an intravenous infusion (500 mg per square meter for 24 hours) the ventricular cerebrospinal-fluid concentration rose to 6 times 10-minus 7 M. Methotrexate administered by Ommaya reservoir, at a dose of 6.25 mg per square meter, rapidly distributed in the subarachnoid space; the peak ventricular concentration of 2 times 10-minus 4 M declined exponentially over 48 hours. Lumbar cerebrospinal-fluid concentration reached a maximum of 5 times 10-minus 5 M four hours after injection and then fell exponentially. Administration by lumbar puncture occasionally produced epidural and subdural leakage; even with successful lumbar puncture, ventricular methotrexate concentration varied considerably from patient to patient despite similar doses. Administration by Ommaya reservoir more reliably produced adequate cerebrospinal fluid distribution than administration by lumbar puncture.

Annals of the New York Academy of Sciences, Aug 1, 1975

Cancer, 1987

The administration of an elemental, chemically defined liquid diet to rats significantly enhanced... more The administration of an elemental, chemically defined liquid diet to rats significantly enhanced gastrointestinal toxicity associated with methotrexate administration compared with rats fed a regular chow diet. Chemotherapy induced enteritis is potentially enhanced by the abrasive effect of bile acids on the susceptible cells of the small bowel mucosa. This study evaluated the interactions of methotrexate and cholestyramine in vitro. An additional goal was to evaluate the effects of cholestyramine on animal survival and drug pharmacokinetics in rats given an elemental, chemically defined liquid diet. In vitro binding of cholestyramine to methotrexate increased in a linear fashion at varying concentrations of both drugs in phosphate buffer solution (r greater than 0.84, P less than 0.001) and in bile which was not influenced by pH (range 5-8). The addition of cholestyramine to an elemental liquid diet significantly improved survival following methotrexate administration (20 mg/kg IP bolus) compared with rats fed an elemental liquid diet alone (P less than 0.02). Both elemental liquid diets, either with or without cholestyramine, delayed serum and biliary clearance of methotrexate up to 72 hours compared with rats fed a regular chow diet. However, rats fed an elemental liquid diet with added cholestyramine had significantly lower levels of methotrexate in serum from the systemic and portal venous circulation at 48 hours (P less than 0.03) and in bile at 48 (P less than 0.02) and 72 hours (P less than 0.05) following methotrexate administration. The addition of cholestyramine to an elemental liquid diet improves survival and reduces gastrointestinal toxicity following methotrexate administration, by binding methotrexate in bile and reducing the delay in systemic clearance of the drug. By binding to intraluminal bile acids, cholestyramine may also have a locally protective effect on the mucosal cells of the small intestine following methotrexate administration. Cholestyramine may be of clinical benefit in patients receiving high-dose methotrexate regimens as an adjunct to leucovorin rescue.

Journal of Parenteral and Enteral Nutrition, 1987

The toxic effects of methotrexate administration [20 mg/kg, bolus intraperitoneally (ip)] to rats... more The toxic effects of methotrexate administration [20 mg/kg, bolus intraperitoneally (ip)] to rats fed a regular chow diet (n = 10) was compared with results in animals fed an elemental, chemically defined, liquid diet (n = 10) for 7 days. All animals receiving an elemental diet became anorectic and lethargic within 60 hr of methotrexate injection. All animals in this group subsequently developed enteritis and died within 150 hr. There was no clinical evidence of enteritis in rats fed a regular chow diet and mortality as zero in this group (p less than 0.001). In a second study one group of rats (n = 9) was fed a regular chow diet for 7 days; four groups were fed an elemental, chemically defined, liquid diet (n = 9 per group) for 7 days. At 24 hr and 8 hr prior to, or 24 hr after methotrexate administration, one group was refed a regular chow diet; the fourth group was maintained on an elemental liquid diet throughout the study period. All rats fed a regular chow diet survived following methotrexate injection (20 mg/kg, ip). All rats fed an elemental diet throughout the study period died. Those rats refed a regular diet 24 or 8 hr prior to methotrexate injection demonstrated a significant improvement in survival (100% in the 24-hr group, 55% in the 8-hr group). However, those animals refed a regular diet 24 hr after methotrexate injection demonstrated a 100% mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

INDIAN JOURNAL OF ANIMAL HEALTH, 2021

Excessive consumption of sucrose adversely affects human health. Reduction in sugar consumption b... more Excessive consumption of sucrose adversely affects human health. Reduction in sugar consumption by the people has, therefore, become the need of the hour. The uses of sugar substitutes as sweeteners have their own significance in foods. Of late, tagatose has emerged as a highly potential low-calorie sweetener for food applications. Studies were conducted to find out the suitability of tagatose as a sweetener in flavoured milk. Results suggested that 8 g sucrose can be fully substituted by 8.25 g tagatose and 0.75 g fructose per 100 mL of flavoured milk.

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The Journal of Nuclear Medicine, 2000

Nuclear Medicine and Biology, 1999

P-glycoprotein (P-gp) has a role in multidrug resistance (MDR) encountered in human cancers. In t... more P-glycoprotein (P-gp) has a role in multidrug resistance (MDR) encountered in human cancers. In this study, we used the colchicine-resistant cell line BE(2)-C/CHCb(0.2), a strain of neuroblastoma cell line BE(2)-C, as a model to measure variations of P-gp expression in cells grown in vitro and in vivo. Cells were cultured in the medium supplemented with colchicine. At the beginning of the study the drug was withdrawn and, after 22 days, added back to the culture medium. Cells were harvested at various time points and xenografted in nude mice. P-gp content in cells was measured by self-competitive binding assay and in tumors, by quantitative autoradiography (QAR). Both assays were carried out using 125 I-labeled monoclonal antibody MRK16, reactive with P-gp. Concentration of P-gp in cells varied from a maximum of 1,361 pmol/g in the presence of colchicine to a minimum of 374 pmol/g in the absence of colchicine in the culture medium. P-gp concentration in the tumors ranged from 929 to 188 pmol/g, which correlated with P-gp content in the cells at the time of their injection in the mice. QAR is an accurate and reliable method to quantify P-gp expression in tumors. Changes in colchicine concentration in the ambient medium of BE(2)-C/CHCb(0.2) cells growing in vitro resulted in a change in phenotype of P-gp expression, which was stable under conditions of in vivo growth over approximately 9 cell divisions in nude mice xenografts. Therefore, P-gp content in xenografts depends only on the level of resistance of the cells at the time of their injection in the mice.

Bjog: An International Journal Of Obstetrics And Gynaecology, Dec 1, 1961

... AND MN PARIKH, MD, DA Assistant Professor of Obstetrics and Gynaecology Grant Medical College... more ... AND MN PARIKH, MD, DA Assistant Professor of Obstetrics and Gynaecology Grant Medical College, Bombay-8 ... Group Birth Globulins No. Weight Albumin - (Pounds) Alpha, Abha. Beta Gamma Infants, with weights above 40 6.12 5-69 3.66 0.16 0.33 0.44 1.20 5pounds .. .. . ...

Analytical Biochemistry, May 1, 1996

of the free antibody concentration in the reaction sys-To date, all reported measurements of mult... more of the free antibody concentration in the reaction sys-To date, all reported measurements of multidrug retem. The obtained data can be analyzed by fitting them sistance have been semiquantitative. The purpose of to a model equation, which results in estimation of both the present study is to establish and validate the selfthe number of binding sites B max and the dissociation competitive binding assay technique utilizing monoconstant K d. This can be carried out with precision clonal antibody for quantitative estimation of multidetermined by the highly specific character of antidrug resistance in tumor cells. This technique is used body-antigen interactions. Characterization of a cell for P-glycoprotein concentration measurement in line in terms of the number of antigen molecules ex-BE(2)-C human neuroblastoma cell line and its subpressed on a cell membrane may have important biolines with primary resistance to colchicine and actinological and clinical implications. Such characterization mycin D. Monoclonal antibody MRK-16 was used in is especially significant if the expression level of the this study. It was labeled with iodine-125 (125 I) to trace studied antigen is crucial for a vital cellular property, the concentration of antibody-antigen complexes. The such as multidrug resistance (MDR). 2 binding data were obtained by varying the concentra-MDR may be a major obstacle to chemotherapy of tion of the unlabeled antibody. The results were fitted various cancers (2, 3). If developed in cancerous cells, to a model equation to estimate the number of binding MDR may decrease efficacy of a variety of anticancer sites and antibody-antigen dissociation constant. The drugs, such as Adriamycin, vincristine, actinomycin D, P-glycoprotein concentration was significantly higher Taxol, and colchicine. Resistant cells can potentially in the resistant sublines than in the sensitive line. The survive otherwise cytotoxic levels of drugs in the ambihighest levels were achieved in actinomycin D-resisent medium depending (at least partially) on the level tant cells: 2.1 1 10 6 binding sites/cell versus 5.4 1 10 4 of P-glycoprotein (P-gp) expression (2-6). P-gp, a prodbinding sites/cell in the sensitive cells. The consistency of the results was verified by repeating the study three uct of mdr1 gene, is a 170-kDa transmembrane glycotimes for each cell line. The binding assay results were protein found in both normal and cancerous cells (4, confirmed by Western blot experiments performed on 6-9). As a member of ATP-binding cassette (ABC) the same cell lines.

P-glycoprotein (Pgp) is known to be associated with multidrug resistance (MDR). Quantitation of P... more P-glycoprotein (Pgp) is known to be associated with multidrug resistance (MDR). Quantitation of P-glycoprotein expression may permit appropriate therapy depending on Pgp expression in tumors. The present study was undertaken to evaluate the utility of quantitative autoradiography (QAR) in the quantification of MDR using MRK-16, a murine IgG mAb reactive against Pgp. Balb/c mice were xenografted with colchicine resistant BE(2)C/CHC

Journal of Organometallic Chemistry, 2010

Single crystal EPR studies of Mn(II) doped hexaaquazincdiaquabis(malonato) zincate [Zn(H 2 O) 6 ]... more Single crystal EPR studies of Mn(II) doped hexaaquazincdiaquabis(malonato) zincate [Zn(H 2 O) 6 ]-[Zn(mal) 2 (H 2 O) 2 ] have been carried out at room temperature using X-band spectrometer to identify the location of the dopant. Single crystal rotations along the three orthogonal axes show more than 30 line pattern EPR spectra indicating the presence of two types of dopant ions in the host lattice, with intensity ratio of 6:1. However, the latter could not be followed due to its low intensity during crystal rotations. The spin-Hamiltonian parameters, estimated from the three mutually orthogonal crystal rotations are: g xx = 1.972, g yy = 2.000, g zz = 2.023, A xx = 8.95, A yy = 9.48, A zz = 9.93 mT, D xx = À34.49, D yy = À3.26, D zz = 37.74 mT and E = 15.6 mT. The direction cosines of one of the principal values of g match with that of Zn-O bond in the host lattice, suggesting that the Mn(II) ion entered the lattice substitutionally. The large value of E is indicative of low symmetry of the substitutional site, in accordance with the crystal structure of the isomorphous [Zn(H 2 O) 6 ][Cu(mal) 2 (H 2 O) 2 ]. Covalency of Mn-O bond, estimated from Matamura's plot, is 9%. Various admixture coefficients, bonding and optical parameters have also been calculated.

Journal of Bacteriology, 1967

A number of species in the genus Streptococcus have been shown to undergo deoxyribonucleic acid (... more A number of species in the genus Streptococcus have been shown to undergo deoxyribonucleic acid (DNA)-mediated transformation. The first report of transformation in two strains of "viridans" streptococci was by R. M. Bracco et al.