Tanveer Ahmad | Bahauddin Zakariya University (original) (raw)

Papers by Tanveer Ahmad

Journal of Applied Physiology, 2009

Allergic airway inflammation (AI) is commonly associated with enhanced exhaled nitric oxide (ENO)... more Allergic airway inflammation (AI) is commonly associated with enhanced exhaled nitric oxide (ENO) in both humans and mice. Since mouse models are being used to understand various mechanisms of asthma, a noninvasive, simple, and reproducible method to determine ENO in mice is required for serial nonterminal assessment that can be used independent of environmental situations in which the ambient air contains substantial amounts of NO as a contaminant. The aim of this study was to noninvasively measure ENO in individual mice and to test its utility as a marker of AI in different models of allergic AI. We modified the existing ENO measuring methods by incorporating flushing and washout steps that allowed simple but reliable measurements under highly variable ambient NO conditions (1-100 ppb). This method was used to serially follow ENO in acute and chronic models of allergic AI in mice. ENO was reproducibly measured by this modified method and was positively correlated to AI in both acute and chronic models of asthma but was not independently related to airway remodeling. Resolution of AI and other related parameters in dexamethasone-treated mice resulted in reduction of ENO, further confirming this association. Restriction of allergen challenge to pulmonary but not nasal airways was associated with a smaller increase in ENO compared with allergen challenge to both. Hence, ENO can now be reliably measured in mice independent of ambient NO levels and is a valid biomarker for AI. However, nasal and pulmonary airways are likely to be independent sources of ENO, and any results must be interpreted as such.

American Journal of Respiratory Cell and Molecular Biology, 2010

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase (NOS), cause... more Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase (NOS), causes uncoupling of NOS leading to generation of reactive nitrogen species, such as peroxynitrite. The lung generates a significant amount of ADMA, potentially contributing to plasma ADMA levels that have been related to endothelial dysfunction. ADMA infusion causes increased collagen deposition in lungs, suggesting that it could influence the development of chronic lung diseases such as fibrosis, chronic obstructive pulmonary disease, and asthma. To explore the link between endogenous ADMA and asthma, we determined the levels of ADMA, enzymes implicated in its metabolism, and peroxynitrite in murine models of allergic airway inflammation (AAI) resembling asthma. ADMA levels and nitrosative stress were found to be positively correlated in cytosol and mitochondria during AAI. This was associated with increased expression of protein-arginine methyltransferase-2, an ADMA-synthesizing enzyme, and reduced expression of dimethylarginine dimethylaminohydrolase-2, an ADMA-degrading enzyme, in bronchial epithelia. Increased nitrotyrosine similarly localized to the bronchial epithelium, as well as in infiltrated inflammatory cells. Administration of L-arginine, which was expected to compete with ADMA and reverse the uncoupling/inhibition of NOS, restored normal ADMA metabolism, along with the expected reduction of nitrosative stress in lung. Because dimethylarginine dimethylaminohydrolase-2 function is known to be negatively related to oxidative stress, this may represent a feed-forward loop effect. We conclude that a delicate balance between ADMA-metabolizing enzymes is disturbed in bronchial epithelium during AAI, potentially causing increased nitrosative stress in a self-propagating cycle. This represents a potential therapeutic target in asthma.

American Journal of Respiratory Cell and Molecular Biology, 2010

There is growing epidemiological evidence that obesity increases the risk of developing asthma. I... more There is growing epidemiological evidence that obesity increases the risk of developing asthma. In some studies, insulin resistance or metabolic syndrome is a stronger risk factor than body mass. The obese-asthma subphenotype is marked by a paucity of inflammation but also by marked symptoms, poor response to glucocorticoids, and peripheral airway dysfunction. Although obesity may predispose to increased Th2 inflammation or atopic tendencies, other mechanisms that are independent of inflammatory cells need to be considered. There is growing evidence of the influence of hyperglycemia, hyperinsulinemia, and insulin-like growth factors on airway structure and function. Also, studies from mouse models of asthma have highlighted the importance of nitric oxide-arginine metabolism abnormalities and oxonitrosative stress in lungs. Such changes are well established features of the metabolic syndrome and may represent an interface between these diseases that can be therapeutically targeted. Such therapies, including administration of l-arginine or statins, increasing endothelial nitric oxide synthase, or the use of arginase inhibitors, have been successful in experimental models but have not yet translated to the clinical arena. We review the current understanding of the potential mechanistic links between obesity and asthma, emphasizing the potential influence of metabolic abnormalities on asthmatic processes, therapeutic implications, and expected challenges.

Physiological Genomics, 2009

Small maladaptations in cellular response to environmental stressors may underlie diseases like a... more Small maladaptations in cellular response to environmental stressors may underlie diseases like asthma. However, genomewide transcriptional profile comparisons between case and controls only highlight the quantitatively largest changes. Critical cellular homeostatic pathways may be upregulated modestly during normal adaptation to stress but insufficiently during disease. To discover such pathways in asthma, we utilized public information on differential response of primary bronchial epithelial cells from asthmatic or normal subjects to stressors like ozone and viral infections. Genes that were upregulated by stressor conditions in normal cells but were relatively downregulated in cells from asthmatic subjects were selected for further analysis. Either a stringent selection based on quantitative criterion or a nonstringent selection followed by network-based analysis was used. At the individual gene level, decay accelerating factor-1 (DAF-1, CD55) was identified and selected for validation. In a mouse model of allergic airway inflammation (AAI) resembling asthma, protein expression of CD55 was reduced compared with normal mice and returned to normal upon resolution of the allergic response. This was consistent with our finding of relative downregulation of CD55 in asthmatic compared with normal subjects. Interestingly, at a network level, the results pointed to possible abnormalities in the inositol signaling pathway, a critical cell signaling mechanism. In the mouse model of AAI, we found downregulation of inositol polyphosphate 4 phosphatase A (INPP4A), a critical member of the inositol signaling pathway. This and previous genetic evidence supports a role for inositol signaling abnormalities in asthma. In summary, logic-gated hypothesis-free exploration of published data sets may be valuable in discovery of novel disease-associated pathways.

International Immunopharmacology, 2010

Bronchial epithelial injury is the hall mark of asthma which is a chronic airway inflammatory dis... more Bronchial epithelial injury is the hall mark of asthma which is a chronic airway inflammatory disease. We have shown the mitochondrial ultrastructural changes and dysfunction in bronchial epithelia of OVA induced mice. Reduced L-arginine bioavailability in asthma leads to increased formation of peroxynitrite which could induce mitochondrial dysfunction. We have also shown that L-arginine administration attenuates experimental asthma and reduces peroxynitrite. In this study, we wanted to determine the effect of L-arginine on mitochondrial dysfunction and airway injury in allergic airway inflammation. To determine this, L-arginine was administered to ovalbumin sensitized and challenged mice during allergen challenges. Mitochondrial and cytosolic fractions were purified from the lung to determine key mitochondrial functions, and mitochondrial ultrastructural changes in bronchial epithelia of first generation bronchi were determined. It was found that L-arginine administration increased mitochondrial cytochrome c oxidase activity, reduced cytosolic cytochrome c, increased lung ATP levels, reduced DNA fragmentation in bronchial epithelia and restored the ultrastructural changes of mitochondria of bronchial epithelia. In addition, L-arginine administration reduced the widening of intercellular spaces between adjacent bronchial epithelia. These findings indicated that L-arginine administration reduced airway injury and restored mitochondrial dysfunction in murine allergic airway inflammation.

Journal of Allergy and Clinical Immunology, 2010

Background: Disturbance in the delicate balance between L-arginine-metabolizing enzymes such as n... more Background: Disturbance in the delicate balance between L-arginine-metabolizing enzymes such as nitric oxide synthase (NOS) and arginase may lead to decreased L-arginine availability to constitutive forms of NOS (endothelial NOS), thereby increasing the nitro-oxidative stress and airway hyperresponsiveness (AHR). Objective: In this study, we investigated the effects of high doses of L-arginine on L-arginine-metabolizing enzymes and subsequent biological effects such as cyclic guanosine monophosphate production, lipid peroxidation, peroxynitrite, AHR, and airway inflammation in a murine model of asthma. Methods: Different doses of L-arginine were administered to ovalbumin-sensitized and challenged mice. Exhaled nitric oxide, AHR, airway inflammation, T H 2 cytokines, goblet cell metaplasia, nitro-oxidative stress, and expressions of arginase 1, endothelial NOS, and inducible NOS in lung were determined. Results: L-arginine significantly reduced AHR and airway inflammation including bronchoalveolar lavage fluid eosinophilia, T H 2 cytokines, TGF-b1, goblet cell metaplasia, and subepithelial fibrosis. Further, L-arginine increased ENO levels and cyclic guanosine monophosphate in lung and reduced the markers of nitro-oxidative stress such as nitrotyrosine, 8isoprostane, and 8-hydroxy-29-deoxyguanosine. This was associated with reduced activity and expression of arginase 1, increased expression of endothelial NOS, and reduction of inducible NOS in bronchial epithelia. Conclusion: We conclude that L-arginine administration may improve disordered nitric oxide metabolism associated with allergic airway inflammation, and alleviates some features of asthma. (J Allergy Clin Immunol 2010;125:626-35.)

Journal of Allergy and Clinical Immunology, 2011

IL-13, a cytokine secreted by T(H)2 lymphocytes and other cells, critically modulates allergic in... more IL-13, a cytokine secreted by T(H)2 lymphocytes and other cells, critically modulates allergic inflammation and tissue remodeling in allergic asthma. Although much is known about transcriptional regulation of IL-13, posttranscriptional regulation is poorly understood. Because many inflammatory pathways are known to be regulated by microRNAs, permitting a rapid and fine-tuned response, the role of microRNA-mediated regulation of IL-13 was investigated using both in vitro and in vivo studies. A combination of in silico approaches and in vitro transfections in A549 cells and primary cultured T cells was used to demonstrate the involvement of let-7 in IL-13 regulation. Furthermore, intranasal delivery of let-7 microRNA mimic in mice was performed to study its effects in allergic airway inflammatory conditions. Using a combination of bioinformatics and molecular approaches, we demonstrate that the let-7 family of microRNAs regulates IL-13 expression. Induced levels of IL-13 in cultured T cells were inversely related to let-7 levels. In an IL-13-dependent murine model of allergic airway inflammation, we observed that inflammation was associated with a reduction in most of the members of the let-7 family. Exogenous administration of let-7 mimic to lungs of mice with allergic inflammation resulted in a decrease in IL-13 levels, resolution of airway inflammation, reduction in airway hyperresponsiveness, and attenuation of mucus metaplasia and subepithelial fibrosis. Let-7 microRNAs inhibit IL-13 expression and represent a major regulatory mechanism for modulating IL-13 secretion in IL-13-producing cell types and thereby T(H)2 inflammation.

Animal Feed Science and Technology, 2008

The experiment was conducted to evaluate the effect of varying dietary metabolizable energy (ME) ... more The experiment was conducted to evaluate the effect of varying dietary metabolizable energy (ME) and crude protein (CP) concentrations on broiler performance during hot summer conditions. One day old straight-run (0.50 male and 0.50 female) Starbro broiler chicks (n = 600) were randomly divided into 30 experimental units of 20 chicks each. Two levels of dietary ME (12.13 and 12.55 MJ/kg) and three levels of dietary CP (190, 210 and 230 g/kg) were used in a 2 × 3 factorial arrangement giving six dietary treatments. Level of essential amino acids were maintained in all the diets by supplementing low CP diets with crystalline amino acids. Each of the experimental diets was offered to five replicates from hatching to 28 d of age. At the end of the experiment, two birds from each replicate were randomly selected for data on dressing yield, breast meat yield, abdominal fat, and liver and gizzard weights. Increasing dietary ME significantly increased the BW gain, abdominal fat and liver weights, and protein and fat contents of the carcass whereas the dry matter of carcass was reduced by increasing dietary ME. Dietary CP had quadratic effects on BW gain, F:G, carcass weight, and dry matter and protein contents of the meat. Breast weight and fat contents of meat increased linearly with increasing CP of the diets. The low CP diets (i.e., 190 g/kg) at high ME (i.e., 12.55 MJ/kg) increased * Corresponding author at: et al. / Animal Feed Science and Technology 146 (2008) 302-312 303 the BW gain, feed intake, carcass weight and improved F:G. However, lowest F:G was observed in birds fed 210 g CP and 12.13 MJ ME/kg of diet. Protein and fat contents of the carcass were increased in birds fed on diets having high CP and ME whereas dry matter contents of meat improved with high CP and low ME diets. The results of the trial showed a correlation between dietary CP and ME and hence the optimal value for one cannot be predicted without considering the other. Briefly, low CP with high ME diets improved the overall performance when environmental temperature ranged from 32 to 39 • C.

Physica Medica, 2011

Wedge filters are commonly used in external beam radiotherapy to achieve a uniform dose distribut... more Wedge filters are commonly used in external beam radiotherapy to achieve a uniform dose distribution within the target volume. The main objective of this study was to investigate the accuracy of the beam modifier algorithm of Theraplan plus (TPP version 3.8) treatment planning system and to confirm that either the beam hardening, beam softening and attenuation coefficients along with wedge geometry and measured wedge factor at single depth and multiple fields sizes can be the replacement of wedged profile and wedged crosssectional data or not. In this regard the effect of beam hardening and beam softening was studied with physical wedges for 6 MV photons. The Normalized Wedge Factors (NWFs) were measured experimentally as well as calculated with the Theraplan plus, as a function of depth and field size in a water phantom for 15 , 30 , 45 , and 60 wedge filters. The beam hardening and softening was determined experimentally by deriving the required coefficients for all wedge angles. The TPP version 3.8 requires wedge transmission factor at single depth and multiple field sizes. Without incorporating the hardening and softening coefficients the percent difference between measured and calculated NFWs was as high as 7%. After the introduction of these parameters into the algorithm, the agreement between measured and TPP (V 3.8) calculated NWFs were improved to within 2 percent for various depths. Similar * Corresponding author. Tel.: þ82 (10) 3901 4141; fax: þ82 (53) 950 7355. improvement was observed in TPP version 3.8 while calculating NWFs for various field sizes when the required coefficients were adjusted. In conclusion, the dose calculation algorithm of TPP version 3.8 showed good accuracy for a 6 MV photon beam provided beam hardening and softening parameters are taken into account. From the results, it is also concluded that, the beam hardening, beam softening and attenuation coefficients along with wedge geometry and measured wedge factor at single depth and multiple fields sizes can be the replacement of wedged profile and wedged cross-sectional data in the TPS. The study also indicated that by ignoring the beam softening and beam hardening will result in an inaccurate dose to the target volume of the patient.

One-day-old Starbro male broiler chicks (n = 360) were used to determine the effect of increasing... more One-day-old Starbro male broiler chicks (n = 360) were used to determine the effect of increasing levels of Na + and Cl − above the NRC (1994) recommendations for growing broilers diets (hatching to 28 d) in extremely hot weather. The average maximum and minimum temperatures recorded were 39 and 32°C, respectively. An average relative humidity was 58.2% during the experimental period. Three levels of dietary Na + (0.20, 0.25, and 0.30%) and Cl − (0.30, 0.40, and 0.50%) were used in 3 × 3 factorial arrangement while maintaining a dietary electrolyte balance (DEB) of 250 mEq/kg. Higher weight gain (P < 0.002) and maximum water consumption (P < 0.05) were observed for birds fed diets containing 0.25 and 0.30% Na + , respectively. Litter moisture was significantly higher (P < 0.05) for birds fed diets containing 0.25% Na + (1716 and 0.40 and 0.50% Cl − . High dietary Na + (0.30%) tended to increase breast yield (P < 0.003) and decreased abdominal fat (P < 0.001). There was no effect of Na + on blood pH or serum HCO − 3 . Diets containing 0.40% Cl − increased the dressing percentage (P < 0.001) and leg yield (P < 0.001) and decreased serum HCO − 3 (P < 0.001). There was no effect of dietary Cl − on blood pH, feed intake, weight gain, feed:gain, water intake, water:feed intake, or mortality. Significant dietary effect of Na + × Cl − was noted only for litter moisture (P < 0.001), dressing percentage (P < 0.05), breast (P < 0.05) and leg (P < 0.001) yields, abdominal fat (P < 0.002), and serum HCO − 3 (P < 0.001). Birds fed diet containing 0.25% Na + and 0.30% Cl − performed as well as those fed other diets when the cyclic temperature ranged from 32 to 39°C. stress in birds have shown elevated blood pH . Birds attempt to correct blood pH by excreting HCO − 3 via urine. Bicarbonates are negatively charged ions that must be coupled with positively charged ions such as Na + or K + to be excreted in the urine. Thus, in heat stressed birds K + , Na + , and HCO − 3 become deficient in the body. Belay et al. (1990) reported that respiratory alkalosis induced by heat stress is related to a negative mineral balance of K + and Na + . Therefore, it is necessary to supply Na + and K + along with Cl − in adequate balance for optimum growth, bone development, and good litter quality .

Journal of Animal Physiology and Animal Nutrition, 2009

A 6-week feeding trial was conducted to determine the effects of varying dietary electrolyte bala... more A 6-week feeding trial was conducted to determine the effects of varying dietary electrolyte balance (DEB) on growth performance and physiological responses in broiler chicks reared during hot summer months (26.1–37.5 °C). The average minimum and maximum room temperatures recorded from 14 to 42 days of age were 26.1 and 37.5 °C, respectively, with relative humidity ranging from 51% to 55%. Five DEB treatments supplying 0, 50, 150, 250 and 350 (Na++K+–Cl−) mEq/kg of diet were prepared by adding NaHCO3 and/or NH4Cl to basal diet that contained 185 mEq/kg from 1 to 28 days and 172 mEq/kg from 29 to 42 days. These DEB diets were randomly offered to six experimental units of 20 chicks each. Improved 42-day body weight gain (BWG), feed:gain (F:G) and reduced mortality was noted with DEB 50, 150 and 250 mEq/kg compared to DEB 0 and 350 mEq/kg. A quadratic effect of increasing DEB level was observed on BWG and F:G, whereas the effect was linear for feed intake, water intake and litter moisture. The DEB 50, 150 and 250 maintained better blood pH, pCO2 and HCO3 concentrations during acute heat stress periods than that of 0 and 350. The blood heterophil and lymphocyte percent as well as heterophil:lymphocyte were remained unaffected. The lowest DEB (0 mEq/kg) diet reduced the feed intake and promoted metabolic acidosis. At 350 mEq/kg DEB, water intake and metabolic alkalosis were promoted probably due to high levels of dietary NaHCO3. The study concluded that overall better performance was recorded with DEB 50, 150 and 250 mEq/kg. These results indicated that single optimal DEB value could not be recommended to combat heat stress in broilers.

Animal Feed Science and Technology, 2009

Please cite this article in press as: Mushtaq, T., et al., Influence of sunflower meal based diet... more Please cite this article in press as: Mushtaq, T., et al., Influence of sunflower meal based diets supplemented with exogenous enzyme and digestible lysine on performance, digestibility. . Please cite this article in press as: Mushtaq, T., et al., Influence of sunflower meal based diets supplemented with exogenous enzyme and digestible lysine on performance, digestibility. . G Model ANIFEE-11995; No. of Pages 12 2

Animal Feed Science and Technology, 2000

Phytase was produced from a fungus Aspergillus niger through 10-day fermentation in a maize starc... more Phytase was produced from a fungus Aspergillus niger through 10-day fermentation in a maize starch-based medium. Activity of the enzyme was found to be 1.075 phytase units per minute per ml of the crude culture ®ltrate, at pH 5.5 and 408C. A 4-week feeding trial was conducted on 90-day-old broiler chickens, fed on diets based on maize and soyabean meal, to study the ef®cacy of phytase enzyme on growth performance, apparent availability of P and Ca, tibia-and-toe ash and mineral contents of tibia. Treatments involved a normal-P level (control, 4.5 g/kg non-phytate phosphorus, nP), a normal-P diet with phytase enzyme-treated maize and soyabean meal and a low-P diet plus phytase (1.075 PU/gm of substrate). Phytase supplementation increased (p < 0.05) BW in normal-P plus phytase diet by 2.65 percentage units as compared to control. Gain in weight was almost similar with both, low-P plus phytase, and control diets (645 vs. 653 g). Added phytase increased the feed intake in the same manner as weight gain, however, feed conversion ratio (FCR) was similar to that for all diets. Phytase treatment of low-P diet increased (p < 0.05) the relative retention of P and Ca by 20.1 and 5.0 percentage units, respectively, than with the control diet. The tibial-and-toe ash contents were increased (p < 0.05) by the normal-P plus phytase diet than with the control diet. Tibial-and-toe ash contents of low-P plus phytase diet were comparable (51.2 vs. 48.6 and 10.9 vs. 10.5) with that of the control diet. Phytase treatment had no effect on the concentration of any of the minerals measured in whole tibia ash, but did increase (p < 0.05) P and Ca in tibia DM of chicken by 4.5 and 9.8 percentage units, respectively, in normal-P plus phytase, and 1.2 and 2.2 percentage units, respectively, in low-P plus phytase diets. These results show that microbial phytase treatment of a low-P diet increased growth and relative retention of P and Ca, and improved bone mineralization in broiler chickens. #

Animal Feed Science and Technology, 2005

Experiment using 297 broiler chicks, kept from 1 to 42 days under cyclic heat stress (minimum 29.... more Experiment using 297 broiler chicks, kept from 1 to 42 days under cyclic heat stress (minimum 29.3 • C and maximum 38 • C), was conducted to investigate the relative efficacies of three sodium (NaHCO 3 , Na 2 CO 3 , Na 2 SO 4 ), and potassium (KHCO 3 , K 2 CO 3 , K 2 SO 4 ) supplements at an identical dietary electrolyte balance (DEB) 250 mEq/kg and two chloride supplements (CaCl 2 and NH 4 Cl) at DEB 50 mEq/kg. The desired levels of DEB were achieved by substitution of individual mineral supplement at the expense to builder's sand in the basal starter (DEB 185.6 mEq/kg) and finisher (DEB 174 mEq/kg) diet containing only salt as a source of Na and Cl. Each diet (one basal and eight experimental) was fed to three experimental units having 11 chicks each. The growth performances in K supplements, except KHCO 3 , were poorer than those of Na supplements. The NaHCO 3 , Na 2 CO 3 , Na 2 SO 4 and NH 4 Cl increased body weight gain, feed intake and improved feed to gain ratio than those of K 2 CO 3 and K 2 SO 4 after 42 days of age. These supplements also increased the water intake and resulted in lowered body temperature as well as reduced mortality. Very poor performance in CaCl 2 supplement was associated with disturbed calcium:phosphorus and very low blood pH (7.19). Better performance was noted with bicarbonate than that with carbonate and sulfate sources. The KHCO 3 accentuate the respiratory alkalosis by increasing blood HCO 3 contents (26.09 mmol/l) and gave poorer performance than NaHCO 3 . Blood lymphocytes, hemoglobin, hematocrit and electrolyte balance in heat stressed broilers were better improved by NH 4 Cl, NaHCO 3 , Na 2 CO 3 , Na 2 SO 4 and KHCO 3 than those of CaCl 2 , K 2 CO 3 and K 2 SO 4 supplements. Present findings emphasized the importance of considering metabolisable anions supplemented in association with cations while balancing the dietary electrolyte equations. That is why DEB equation cannot be used to predict the relative benefits of different mineral supplements.

Worlds Poultry Science Journal, 2006

Journal of Applied Physiology, 2009

Allergic airway inflammation (AI) is commonly associated with enhanced exhaled nitric oxide (ENO)... more Allergic airway inflammation (AI) is commonly associated with enhanced exhaled nitric oxide (ENO) in both humans and mice. Since mouse models are being used to understand various mechanisms of asthma, a noninvasive, simple, and reproducible method to determine ENO in mice is required for serial nonterminal assessment that can be used independent of environmental situations in which the ambient air contains substantial amounts of NO as a contaminant. The aim of this study was to noninvasively measure ENO in individual mice and to test its utility as a marker of AI in different models of allergic AI. We modified the existing ENO measuring methods by incorporating flushing and washout steps that allowed simple but reliable measurements under highly variable ambient NO conditions (1-100 ppb). This method was used to serially follow ENO in acute and chronic models of allergic AI in mice. ENO was reproducibly measured by this modified method and was positively correlated to AI in both acute and chronic models of asthma but was not independently related to airway remodeling. Resolution of AI and other related parameters in dexamethasone-treated mice resulted in reduction of ENO, further confirming this association. Restriction of allergen challenge to pulmonary but not nasal airways was associated with a smaller increase in ENO compared with allergen challenge to both. Hence, ENO can now be reliably measured in mice independent of ambient NO levels and is a valid biomarker for AI. However, nasal and pulmonary airways are likely to be independent sources of ENO, and any results must be interpreted as such.

American Journal of Respiratory Cell and Molecular Biology, 2010

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase (NOS), cause... more Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase (NOS), causes uncoupling of NOS leading to generation of reactive nitrogen species, such as peroxynitrite. The lung generates a significant amount of ADMA, potentially contributing to plasma ADMA levels that have been related to endothelial dysfunction. ADMA infusion causes increased collagen deposition in lungs, suggesting that it could influence the development of chronic lung diseases such as fibrosis, chronic obstructive pulmonary disease, and asthma. To explore the link between endogenous ADMA and asthma, we determined the levels of ADMA, enzymes implicated in its metabolism, and peroxynitrite in murine models of allergic airway inflammation (AAI) resembling asthma. ADMA levels and nitrosative stress were found to be positively correlated in cytosol and mitochondria during AAI. This was associated with increased expression of protein-arginine methyltransferase-2, an ADMA-synthesizing enzyme, and reduced expression of dimethylarginine dimethylaminohydrolase-2, an ADMA-degrading enzyme, in bronchial epithelia. Increased nitrotyrosine similarly localized to the bronchial epithelium, as well as in infiltrated inflammatory cells. Administration of L-arginine, which was expected to compete with ADMA and reverse the uncoupling/inhibition of NOS, restored normal ADMA metabolism, along with the expected reduction of nitrosative stress in lung. Because dimethylarginine dimethylaminohydrolase-2 function is known to be negatively related to oxidative stress, this may represent a feed-forward loop effect. We conclude that a delicate balance between ADMA-metabolizing enzymes is disturbed in bronchial epithelium during AAI, potentially causing increased nitrosative stress in a self-propagating cycle. This represents a potential therapeutic target in asthma.

American Journal of Respiratory Cell and Molecular Biology, 2010

There is growing epidemiological evidence that obesity increases the risk of developing asthma. I... more There is growing epidemiological evidence that obesity increases the risk of developing asthma. In some studies, insulin resistance or metabolic syndrome is a stronger risk factor than body mass. The obese-asthma subphenotype is marked by a paucity of inflammation but also by marked symptoms, poor response to glucocorticoids, and peripheral airway dysfunction. Although obesity may predispose to increased Th2 inflammation or atopic tendencies, other mechanisms that are independent of inflammatory cells need to be considered. There is growing evidence of the influence of hyperglycemia, hyperinsulinemia, and insulin-like growth factors on airway structure and function. Also, studies from mouse models of asthma have highlighted the importance of nitric oxide-arginine metabolism abnormalities and oxonitrosative stress in lungs. Such changes are well established features of the metabolic syndrome and may represent an interface between these diseases that can be therapeutically targeted. Such therapies, including administration of l-arginine or statins, increasing endothelial nitric oxide synthase, or the use of arginase inhibitors, have been successful in experimental models but have not yet translated to the clinical arena. We review the current understanding of the potential mechanistic links between obesity and asthma, emphasizing the potential influence of metabolic abnormalities on asthmatic processes, therapeutic implications, and expected challenges.

Physiological Genomics, 2009

Small maladaptations in cellular response to environmental stressors may underlie diseases like a... more Small maladaptations in cellular response to environmental stressors may underlie diseases like asthma. However, genomewide transcriptional profile comparisons between case and controls only highlight the quantitatively largest changes. Critical cellular homeostatic pathways may be upregulated modestly during normal adaptation to stress but insufficiently during disease. To discover such pathways in asthma, we utilized public information on differential response of primary bronchial epithelial cells from asthmatic or normal subjects to stressors like ozone and viral infections. Genes that were upregulated by stressor conditions in normal cells but were relatively downregulated in cells from asthmatic subjects were selected for further analysis. Either a stringent selection based on quantitative criterion or a nonstringent selection followed by network-based analysis was used. At the individual gene level, decay accelerating factor-1 (DAF-1, CD55) was identified and selected for validation. In a mouse model of allergic airway inflammation (AAI) resembling asthma, protein expression of CD55 was reduced compared with normal mice and returned to normal upon resolution of the allergic response. This was consistent with our finding of relative downregulation of CD55 in asthmatic compared with normal subjects. Interestingly, at a network level, the results pointed to possible abnormalities in the inositol signaling pathway, a critical cell signaling mechanism. In the mouse model of AAI, we found downregulation of inositol polyphosphate 4 phosphatase A (INPP4A), a critical member of the inositol signaling pathway. This and previous genetic evidence supports a role for inositol signaling abnormalities in asthma. In summary, logic-gated hypothesis-free exploration of published data sets may be valuable in discovery of novel disease-associated pathways.

International Immunopharmacology, 2010

Bronchial epithelial injury is the hall mark of asthma which is a chronic airway inflammatory dis... more Bronchial epithelial injury is the hall mark of asthma which is a chronic airway inflammatory disease. We have shown the mitochondrial ultrastructural changes and dysfunction in bronchial epithelia of OVA induced mice. Reduced L-arginine bioavailability in asthma leads to increased formation of peroxynitrite which could induce mitochondrial dysfunction. We have also shown that L-arginine administration attenuates experimental asthma and reduces peroxynitrite. In this study, we wanted to determine the effect of L-arginine on mitochondrial dysfunction and airway injury in allergic airway inflammation. To determine this, L-arginine was administered to ovalbumin sensitized and challenged mice during allergen challenges. Mitochondrial and cytosolic fractions were purified from the lung to determine key mitochondrial functions, and mitochondrial ultrastructural changes in bronchial epithelia of first generation bronchi were determined. It was found that L-arginine administration increased mitochondrial cytochrome c oxidase activity, reduced cytosolic cytochrome c, increased lung ATP levels, reduced DNA fragmentation in bronchial epithelia and restored the ultrastructural changes of mitochondria of bronchial epithelia. In addition, L-arginine administration reduced the widening of intercellular spaces between adjacent bronchial epithelia. These findings indicated that L-arginine administration reduced airway injury and restored mitochondrial dysfunction in murine allergic airway inflammation.

Journal of Allergy and Clinical Immunology, 2010

Background: Disturbance in the delicate balance between L-arginine-metabolizing enzymes such as n... more Background: Disturbance in the delicate balance between L-arginine-metabolizing enzymes such as nitric oxide synthase (NOS) and arginase may lead to decreased L-arginine availability to constitutive forms of NOS (endothelial NOS), thereby increasing the nitro-oxidative stress and airway hyperresponsiveness (AHR). Objective: In this study, we investigated the effects of high doses of L-arginine on L-arginine-metabolizing enzymes and subsequent biological effects such as cyclic guanosine monophosphate production, lipid peroxidation, peroxynitrite, AHR, and airway inflammation in a murine model of asthma. Methods: Different doses of L-arginine were administered to ovalbumin-sensitized and challenged mice. Exhaled nitric oxide, AHR, airway inflammation, T H 2 cytokines, goblet cell metaplasia, nitro-oxidative stress, and expressions of arginase 1, endothelial NOS, and inducible NOS in lung were determined. Results: L-arginine significantly reduced AHR and airway inflammation including bronchoalveolar lavage fluid eosinophilia, T H 2 cytokines, TGF-b1, goblet cell metaplasia, and subepithelial fibrosis. Further, L-arginine increased ENO levels and cyclic guanosine monophosphate in lung and reduced the markers of nitro-oxidative stress such as nitrotyrosine, 8isoprostane, and 8-hydroxy-29-deoxyguanosine. This was associated with reduced activity and expression of arginase 1, increased expression of endothelial NOS, and reduction of inducible NOS in bronchial epithelia. Conclusion: We conclude that L-arginine administration may improve disordered nitric oxide metabolism associated with allergic airway inflammation, and alleviates some features of asthma. (J Allergy Clin Immunol 2010;125:626-35.)

Journal of Allergy and Clinical Immunology, 2011

IL-13, a cytokine secreted by T(H)2 lymphocytes and other cells, critically modulates allergic in... more IL-13, a cytokine secreted by T(H)2 lymphocytes and other cells, critically modulates allergic inflammation and tissue remodeling in allergic asthma. Although much is known about transcriptional regulation of IL-13, posttranscriptional regulation is poorly understood. Because many inflammatory pathways are known to be regulated by microRNAs, permitting a rapid and fine-tuned response, the role of microRNA-mediated regulation of IL-13 was investigated using both in vitro and in vivo studies. A combination of in silico approaches and in vitro transfections in A549 cells and primary cultured T cells was used to demonstrate the involvement of let-7 in IL-13 regulation. Furthermore, intranasal delivery of let-7 microRNA mimic in mice was performed to study its effects in allergic airway inflammatory conditions. Using a combination of bioinformatics and molecular approaches, we demonstrate that the let-7 family of microRNAs regulates IL-13 expression. Induced levels of IL-13 in cultured T cells were inversely related to let-7 levels. In an IL-13-dependent murine model of allergic airway inflammation, we observed that inflammation was associated with a reduction in most of the members of the let-7 family. Exogenous administration of let-7 mimic to lungs of mice with allergic inflammation resulted in a decrease in IL-13 levels, resolution of airway inflammation, reduction in airway hyperresponsiveness, and attenuation of mucus metaplasia and subepithelial fibrosis. Let-7 microRNAs inhibit IL-13 expression and represent a major regulatory mechanism for modulating IL-13 secretion in IL-13-producing cell types and thereby T(H)2 inflammation.

Animal Feed Science and Technology, 2008

The experiment was conducted to evaluate the effect of varying dietary metabolizable energy (ME) ... more The experiment was conducted to evaluate the effect of varying dietary metabolizable energy (ME) and crude protein (CP) concentrations on broiler performance during hot summer conditions. One day old straight-run (0.50 male and 0.50 female) Starbro broiler chicks (n = 600) were randomly divided into 30 experimental units of 20 chicks each. Two levels of dietary ME (12.13 and 12.55 MJ/kg) and three levels of dietary CP (190, 210 and 230 g/kg) were used in a 2 × 3 factorial arrangement giving six dietary treatments. Level of essential amino acids were maintained in all the diets by supplementing low CP diets with crystalline amino acids. Each of the experimental diets was offered to five replicates from hatching to 28 d of age. At the end of the experiment, two birds from each replicate were randomly selected for data on dressing yield, breast meat yield, abdominal fat, and liver and gizzard weights. Increasing dietary ME significantly increased the BW gain, abdominal fat and liver weights, and protein and fat contents of the carcass whereas the dry matter of carcass was reduced by increasing dietary ME. Dietary CP had quadratic effects on BW gain, F:G, carcass weight, and dry matter and protein contents of the meat. Breast weight and fat contents of meat increased linearly with increasing CP of the diets. The low CP diets (i.e., 190 g/kg) at high ME (i.e., 12.55 MJ/kg) increased * Corresponding author at: et al. / Animal Feed Science and Technology 146 (2008) 302-312 303 the BW gain, feed intake, carcass weight and improved F:G. However, lowest F:G was observed in birds fed 210 g CP and 12.13 MJ ME/kg of diet. Protein and fat contents of the carcass were increased in birds fed on diets having high CP and ME whereas dry matter contents of meat improved with high CP and low ME diets. The results of the trial showed a correlation between dietary CP and ME and hence the optimal value for one cannot be predicted without considering the other. Briefly, low CP with high ME diets improved the overall performance when environmental temperature ranged from 32 to 39 • C.

Physica Medica, 2011

Wedge filters are commonly used in external beam radiotherapy to achieve a uniform dose distribut... more Wedge filters are commonly used in external beam radiotherapy to achieve a uniform dose distribution within the target volume. The main objective of this study was to investigate the accuracy of the beam modifier algorithm of Theraplan plus (TPP version 3.8) treatment planning system and to confirm that either the beam hardening, beam softening and attenuation coefficients along with wedge geometry and measured wedge factor at single depth and multiple fields sizes can be the replacement of wedged profile and wedged crosssectional data or not. In this regard the effect of beam hardening and beam softening was studied with physical wedges for 6 MV photons. The Normalized Wedge Factors (NWFs) were measured experimentally as well as calculated with the Theraplan plus, as a function of depth and field size in a water phantom for 15 , 30 , 45 , and 60 wedge filters. The beam hardening and softening was determined experimentally by deriving the required coefficients for all wedge angles. The TPP version 3.8 requires wedge transmission factor at single depth and multiple field sizes. Without incorporating the hardening and softening coefficients the percent difference between measured and calculated NFWs was as high as 7%. After the introduction of these parameters into the algorithm, the agreement between measured and TPP (V 3.8) calculated NWFs were improved to within 2 percent for various depths. Similar * Corresponding author. Tel.: þ82 (10) 3901 4141; fax: þ82 (53) 950 7355. improvement was observed in TPP version 3.8 while calculating NWFs for various field sizes when the required coefficients were adjusted. In conclusion, the dose calculation algorithm of TPP version 3.8 showed good accuracy for a 6 MV photon beam provided beam hardening and softening parameters are taken into account. From the results, it is also concluded that, the beam hardening, beam softening and attenuation coefficients along with wedge geometry and measured wedge factor at single depth and multiple fields sizes can be the replacement of wedged profile and wedged cross-sectional data in the TPS. The study also indicated that by ignoring the beam softening and beam hardening will result in an inaccurate dose to the target volume of the patient.

One-day-old Starbro male broiler chicks (n = 360) were used to determine the effect of increasing... more One-day-old Starbro male broiler chicks (n = 360) were used to determine the effect of increasing levels of Na + and Cl − above the NRC (1994) recommendations for growing broilers diets (hatching to 28 d) in extremely hot weather. The average maximum and minimum temperatures recorded were 39 and 32°C, respectively. An average relative humidity was 58.2% during the experimental period. Three levels of dietary Na + (0.20, 0.25, and 0.30%) and Cl − (0.30, 0.40, and 0.50%) were used in 3 × 3 factorial arrangement while maintaining a dietary electrolyte balance (DEB) of 250 mEq/kg. Higher weight gain (P < 0.002) and maximum water consumption (P < 0.05) were observed for birds fed diets containing 0.25 and 0.30% Na + , respectively. Litter moisture was significantly higher (P < 0.05) for birds fed diets containing 0.25% Na + (1716 and 0.40 and 0.50% Cl − . High dietary Na + (0.30%) tended to increase breast yield (P < 0.003) and decreased abdominal fat (P < 0.001). There was no effect of Na + on blood pH or serum HCO − 3 . Diets containing 0.40% Cl − increased the dressing percentage (P < 0.001) and leg yield (P < 0.001) and decreased serum HCO − 3 (P < 0.001). There was no effect of dietary Cl − on blood pH, feed intake, weight gain, feed:gain, water intake, water:feed intake, or mortality. Significant dietary effect of Na + × Cl − was noted only for litter moisture (P < 0.001), dressing percentage (P < 0.05), breast (P < 0.05) and leg (P < 0.001) yields, abdominal fat (P < 0.002), and serum HCO − 3 (P < 0.001). Birds fed diet containing 0.25% Na + and 0.30% Cl − performed as well as those fed other diets when the cyclic temperature ranged from 32 to 39°C. stress in birds have shown elevated blood pH . Birds attempt to correct blood pH by excreting HCO − 3 via urine. Bicarbonates are negatively charged ions that must be coupled with positively charged ions such as Na + or K + to be excreted in the urine. Thus, in heat stressed birds K + , Na + , and HCO − 3 become deficient in the body. Belay et al. (1990) reported that respiratory alkalosis induced by heat stress is related to a negative mineral balance of K + and Na + . Therefore, it is necessary to supply Na + and K + along with Cl − in adequate balance for optimum growth, bone development, and good litter quality .

Journal of Animal Physiology and Animal Nutrition, 2009

A 6-week feeding trial was conducted to determine the effects of varying dietary electrolyte bala... more A 6-week feeding trial was conducted to determine the effects of varying dietary electrolyte balance (DEB) on growth performance and physiological responses in broiler chicks reared during hot summer months (26.1–37.5 °C). The average minimum and maximum room temperatures recorded from 14 to 42 days of age were 26.1 and 37.5 °C, respectively, with relative humidity ranging from 51% to 55%. Five DEB treatments supplying 0, 50, 150, 250 and 350 (Na++K+–Cl−) mEq/kg of diet were prepared by adding NaHCO3 and/or NH4Cl to basal diet that contained 185 mEq/kg from 1 to 28 days and 172 mEq/kg from 29 to 42 days. These DEB diets were randomly offered to six experimental units of 20 chicks each. Improved 42-day body weight gain (BWG), feed:gain (F:G) and reduced mortality was noted with DEB 50, 150 and 250 mEq/kg compared to DEB 0 and 350 mEq/kg. A quadratic effect of increasing DEB level was observed on BWG and F:G, whereas the effect was linear for feed intake, water intake and litter moisture. The DEB 50, 150 and 250 maintained better blood pH, pCO2 and HCO3 concentrations during acute heat stress periods than that of 0 and 350. The blood heterophil and lymphocyte percent as well as heterophil:lymphocyte were remained unaffected. The lowest DEB (0 mEq/kg) diet reduced the feed intake and promoted metabolic acidosis. At 350 mEq/kg DEB, water intake and metabolic alkalosis were promoted probably due to high levels of dietary NaHCO3. The study concluded that overall better performance was recorded with DEB 50, 150 and 250 mEq/kg. These results indicated that single optimal DEB value could not be recommended to combat heat stress in broilers.

Animal Feed Science and Technology, 2009

Please cite this article in press as: Mushtaq, T., et al., Influence of sunflower meal based diet... more Please cite this article in press as: Mushtaq, T., et al., Influence of sunflower meal based diets supplemented with exogenous enzyme and digestible lysine on performance, digestibility. . Please cite this article in press as: Mushtaq, T., et al., Influence of sunflower meal based diets supplemented with exogenous enzyme and digestible lysine on performance, digestibility. . G Model ANIFEE-11995; No. of Pages 12 2

Animal Feed Science and Technology, 2000

Phytase was produced from a fungus Aspergillus niger through 10-day fermentation in a maize starc... more Phytase was produced from a fungus Aspergillus niger through 10-day fermentation in a maize starch-based medium. Activity of the enzyme was found to be 1.075 phytase units per minute per ml of the crude culture ®ltrate, at pH 5.5 and 408C. A 4-week feeding trial was conducted on 90-day-old broiler chickens, fed on diets based on maize and soyabean meal, to study the ef®cacy of phytase enzyme on growth performance, apparent availability of P and Ca, tibia-and-toe ash and mineral contents of tibia. Treatments involved a normal-P level (control, 4.5 g/kg non-phytate phosphorus, nP), a normal-P diet with phytase enzyme-treated maize and soyabean meal and a low-P diet plus phytase (1.075 PU/gm of substrate). Phytase supplementation increased (p < 0.05) BW in normal-P plus phytase diet by 2.65 percentage units as compared to control. Gain in weight was almost similar with both, low-P plus phytase, and control diets (645 vs. 653 g). Added phytase increased the feed intake in the same manner as weight gain, however, feed conversion ratio (FCR) was similar to that for all diets. Phytase treatment of low-P diet increased (p < 0.05) the relative retention of P and Ca by 20.1 and 5.0 percentage units, respectively, than with the control diet. The tibial-and-toe ash contents were increased (p < 0.05) by the normal-P plus phytase diet than with the control diet. Tibial-and-toe ash contents of low-P plus phytase diet were comparable (51.2 vs. 48.6 and 10.9 vs. 10.5) with that of the control diet. Phytase treatment had no effect on the concentration of any of the minerals measured in whole tibia ash, but did increase (p < 0.05) P and Ca in tibia DM of chicken by 4.5 and 9.8 percentage units, respectively, in normal-P plus phytase, and 1.2 and 2.2 percentage units, respectively, in low-P plus phytase diets. These results show that microbial phytase treatment of a low-P diet increased growth and relative retention of P and Ca, and improved bone mineralization in broiler chickens. #

Animal Feed Science and Technology, 2005

Experiment using 297 broiler chicks, kept from 1 to 42 days under cyclic heat stress (minimum 29.... more Experiment using 297 broiler chicks, kept from 1 to 42 days under cyclic heat stress (minimum 29.3 • C and maximum 38 • C), was conducted to investigate the relative efficacies of three sodium (NaHCO 3 , Na 2 CO 3 , Na 2 SO 4 ), and potassium (KHCO 3 , K 2 CO 3 , K 2 SO 4 ) supplements at an identical dietary electrolyte balance (DEB) 250 mEq/kg and two chloride supplements (CaCl 2 and NH 4 Cl) at DEB 50 mEq/kg. The desired levels of DEB were achieved by substitution of individual mineral supplement at the expense to builder's sand in the basal starter (DEB 185.6 mEq/kg) and finisher (DEB 174 mEq/kg) diet containing only salt as a source of Na and Cl. Each diet (one basal and eight experimental) was fed to three experimental units having 11 chicks each. The growth performances in K supplements, except KHCO 3 , were poorer than those of Na supplements. The NaHCO 3 , Na 2 CO 3 , Na 2 SO 4 and NH 4 Cl increased body weight gain, feed intake and improved feed to gain ratio than those of K 2 CO 3 and K 2 SO 4 after 42 days of age. These supplements also increased the water intake and resulted in lowered body temperature as well as reduced mortality. Very poor performance in CaCl 2 supplement was associated with disturbed calcium:phosphorus and very low blood pH (7.19). Better performance was noted with bicarbonate than that with carbonate and sulfate sources. The KHCO 3 accentuate the respiratory alkalosis by increasing blood HCO 3 contents (26.09 mmol/l) and gave poorer performance than NaHCO 3 . Blood lymphocytes, hemoglobin, hematocrit and electrolyte balance in heat stressed broilers were better improved by NH 4 Cl, NaHCO 3 , Na 2 CO 3 , Na 2 SO 4 and KHCO 3 than those of CaCl 2 , K 2 CO 3 and K 2 SO 4 supplements. Present findings emphasized the importance of considering metabolisable anions supplemented in association with cations while balancing the dietary electrolyte equations. That is why DEB equation cannot be used to predict the relative benefits of different mineral supplements.

Worlds Poultry Science Journal, 2006