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Biomedical subjects

G Sarwar

Publications and source records attributed to G Sarwar.

At least 19 recordsLinked to original sources
PubMed2002

Methicillin resistant Staphylococcus aureus: a multicentre study.

OBJECTIVE: To determine the frequency of Methicillin resistance Staphylococcus aureus infection in major cities of Pakistan. SETTING: Various laboratories of the country with one as the central Laboratory. MATERIALS AND METHODS: Seven hundred and ninety two consecutive clinical isolates of Staphylococcus aureus were collected from 8 laboratories all over Pakistan i.e. Karachi, Peshawar, Lahore, Sukkhur, Islamabad, Quetta, and Mirpur, Azad Kashmir. Antibiotic sensitivity was done by Kirby Bauer disc diffusion method and MIC of Vancomycin was determined by 'E' test. RESULTS: Forty two percent of the isolates were found to be Methicillin resistant staphylococcus aureus (MRSA) while no Vancomycin resistance was encountered. CONCLUSION: Methicillin resistant Staphylococcus aureus (MRSA) are seen in the local population with frequencies varying between 2-61% highest incidence is seen in the major cities of the country. Fortunately no Vancomycin resistant Staphylococcus has been isolated from any of the major cities.

Developing Countries↗
PubMed2001

Influence of tryptophan supplementation of soy-based infant formulas on protein quality and on blood and brain tryptophan and brain serotonin in the rat model.

A 2-wk feeding study with weanling rats was conducted to investigate the effects of tryptophan supplementation of soy-based infant formulas on protein quality and on the levels of blood and brain tryptophan and brain serotonin and 5-HIAA (5-hydroxyindole-3-acetic acid), a metabolite of serotonin. The powder and liquid concentrate forms of soy-based infant formulas obtained from four manufacturers were tested. The tryptophan contents of the test soy-based formulas (10.0-12.3 mg/g protein) were considerably lower compared to those of human milk (17-19 mg/g protein). The infant formulas were fed as the sole source of protein in diets containing 8% protein, 20% fat, 5% cellulose and adequate amounts of minerals and vitamins. In general, supplementation of the diets containing test formulas with graded levels of L-tryptophan (0.1 or 0.2%) had no effect on protein quality indices based on rat growth such as PER (protein efficiency ratio), NPR (net protein ratio) and relative NPR (RNPR), but resulted in significant (p < 0.05) increases in the concentrations of tryptophan in the plasma and brain, and serotonin and 5-HIAA in brain of rats. The increased concentrations of brain tryptophan and 5-hydroxyindoles (serotonin + 5-HIAA) in rats fed tryptophan-supplemented formulas compared to those fed unsupplemented formulas support the need for further research to investigate the influence of tryptophan supplementation of soy-based infant formulas on tryptophan metabolites and their potential related effects on sleep latency and neurobehavioral developments in infants.

Animals↗
PubMed2000

Influence of sources of dietary oils on the life span of stroke-prone spontaneously hypertensive rats.

In recent studies, the life span of stroke-prone spontaneously hypertensive (SHRSP) rats was altered by a variety of dietary fats. It was relatively shorter in rats fed canola oil as the sole source of fat. The present study was performed to find out whether the fatty acid profile and the high content of sulfur compounds in canola oil could modulate the life span of SHRSP rats. SHRSP rats (47 d old, n = 23/group) were matched by body weight and systolic blood pressure and fed semipurified diets containing 10% canola oil, high-palmitic canola oil, low-sulfur canola oil, soybean oil, high-oleic safflower oil, a fat blend that mimicked the fatty acid composition of canola oil, or a fat blend high in saturated fatty acids. A 1% sodium chloride solution was used as drinking water to induce hypertension. After consuming the diets for 37 d, five rats from each dietary group were killed for collection of blood and tissue samples for biochemical analysis. The 18 remaining animals from each group were used for determining their life span. The mean survival time of SHRSP rats fed canola oil (87.4+/-4.0 d) was not significantly different (P > 0.05) from those fed low-sulfur canola oil (89.7+/-8.5 d), suggesting that content of sulfur in canola oil has no effect on the life span of SHRSP rats. The SHRSP rats fed the noncanola oil-based diets lived longer (mean survival time difference was 6-13 d, P < 0.05) than those fed canola and low-sulfur canola oils. No marked differences in the survival times were observed among the noncanola oil-based groups. The fatty acid composition of the dietary oils and of red blood cells and liver of SHRSP rats killed after 37 d of treatment showed no relationship with the survival times. These results suggest that the fatty acid profile of vegetable oils plays no important role on the life span of SHRSP rat. However, phytosterols in the dietary oils and in liver and brain were inversely correlated with the mean survival times,indicating that the differential effects of vegetable oils might be ascribed, at least partly, to their different phytosterol contents.

Animals↗
PubMed1999

Influence of feeding alkaline/heat processed proteins on growth and protein and mineral status of rats.

Effects of feeding alkaline (0.1 N NaOH) and heat treated (75 degrees C for 3 h) proteins (lactalbumin and soybean protein isolate, SPI) on growth, and protein and mineral status of rats have been determined. The untreated and alkaline/heat treated lactalbumin contained 0.10 and 4.42 g lysinoalanine (LAL)/100 g protein, respectively. Similarly, the untreated and treated SPI contained 0.03 and 1.94 g LAL/100 g protein, respectively. The formation of LAL in the treated proteins was accompanied with a loss of cystine (73-77%), threonine (35-45%), serine (18-30%) and lysine (19-20%). The alkaline/heat treatments caused significant (P < 0.05) reductions in protein digestibility of lactalbumin (99 vs. 73%) and SPI (96 vs. 68%). The processing treatments also caused a drastic negative effect on protein quality, as measured by rat growth methods such as relative protein efficiency ratio (RPER) and relative net protein ratio (RNPR). The RPER and RNPR values of untreated lactalbumin and SPI were 89-91 and 56-64%, respectively. But the RPER and RNPR values of the treated lactalbumin and SPI were 0%. The mineral status of rats was also compromised by feeding alkaline/heat treated proteins. Liver iron levels in male rats (165-180 micrograms/g dry weight) and female rats (306-321 micrograms/g dry weight) fed the treated proteins were about half the levels in male rats (229-257 micrograms/g dry weight) and female rats (578-697 micrograms/g dry weight) fed the untreated proteins. The kidney iron contents of rats fed the treated proteins were also lower than that of rats fed the untreated proteins. Liver copper levels of male and female rats fed the treated proteins were up to three fold higher than those found in rats fed the untreated proteins. The data suggested that LAL, an unnatural amino acid derivative formed during processing of foods, may produce adverse effects on growth, protein digestibility, protein quality and mineral bioavailability and utilization. The antinutritional effects of LAL may be more pronounced in sole-source foods such as infant formulas and formulated liquid diets which have been reported to contain significant amounts (up to 2400 ppm of LAL in the protein) of LAL.

Amino Acids↗
PubMed1999

Threonine kinetics in preterm infants fed their mothers' milk or formula with various ratios of whey to casein.

BACKGROUND: Plasma threonine concentrations are elevated in infants fed formula containing a whey-to-casein protein ratio of 60:40 compared with concentrations in infants fed formula containing a ratio of 20:80 or human milk (60:40). OBJECTIVE: We studied whether degradation of excess threonine was lower in formula-fed infants than in infants fed their mothers' milk. DESIGN: Threonine kinetics were examined in 17 preterm infants (gestational age: 31+/-2 wk: birth weight: 1720+/-330 g) by using an 18-h oral infusion of [1-13C]threonine at a postnatal age of 21+/-11 d and weight of 1971+/-270 g. Five infants received breast milk. Formula-fed infants (n = 12) were randomly assigned to receive 1 of 3 formulas (5.3 g protein/MJ) that differed only in the whey-to-casein ratio (20:80, 40:60, and 60:40). RESULTS: Threonine intake increased significantly in formula-fed infants with increasing whey content of the formula (48.5, 56.4, and 63.2 micromol.kg(-1).h(-1), respectively; pooled SD: 2.2; P = 0.0001), as did plasma threonine concentrations (228, 344, and 419 micromol/L, respectively; pooled SD: 75; P = 0.03). Despite a generous threonine intake by infants fed breast milk (58.0+/-16.0 micromol.kg(-1).h(-1), plasma threonine concentrations remained low (208+/-41 micromol/L). Fecal threonine excretion and net threonine tissue gain, estimated by nitrogen balance, did not differ significantly among groups. Threonine oxidation did not differ significantly among formula-fed infants but was significantly lower in formula-fed infants fed than in infants fed breast milk (17.1% compared with 24.3% of threonine intake, respectively). CONCLUSION: Formula-fed infants have a lower capacity to oxidize threonine than do infants fed breast milk.

Administration, Oral↗
PubMed1999

Liquid concentrates are lower in bioavailable tryptophan than powdered infant formulas, and tryptophan supplementation of formulas increases brain tryptophan and serotonin in rats.

The bioavailability of tryptophan in powdered and/or liquid concentrate forms of milk-based infant formulas was determined by studying rat growth response by using a slope ratio method (food conversion efficiency: weight gain/food consumed vs. tryptophan consumed). A gelatin basal diet formulated to be adequate in all nutrients, except tryptophan (0.03%), for rat growth was supplemented with graded levels of crystalline L-tryptophan (0.02, 0. 04, 0.06, 0.08, 0.10, 0.12 and 0.14%, standard diets) or infant formulas providing 0.04 and 0.08% supplemental tryptophan (test diets). These diets were fed to weanling rats for 2 wk. Tryptophan bioavailabilities of various formulas varied from 83 to 95%, with some of the liquid concentrates having the lowest values. The levels of bioavailable tryptophan in the liquid concentrate forms (9.7-12.6 mg/g protein) and the powdered forms (11.1-13.1 mg/g protein) were considerably lower than those of human milk (17-19 mg/g protein). Supplementation of the liquid concentrates with graded levels of L-tryptophan (0.1, 0.5 and 1.0%) had no effect on protein quality indices, based on rat growth, but resulted in a dose-related increase in the concentrations of tryptophan in the plasma and brain and of serotonin and 5-hydroxyindole-3-acetic acid in the brains of rats. This study supports further research to investigate the influence of tryptophan supplementation of infant formulas, to more closely simulate tryptophan composition of human milk, on tryptophan metabolites and their potential related effects on sleep latency and neurobehavioral developments in infants.

Animals↗
PubMed1998

Free amino acids in milks of human subjects, other primates and non-primates.

Preterm and term transitional milks of human subjects and mature milks of human subjects, non-human primates and non-primates were analysed for free amino acids (AA) using precolumn phenylisothiocyanate derivatization and liquid chromatography. Differences in free AA between three types of human milk were small. Milks of pinnipeds (seals and sea lions) contained the highest levels of total free AA (8634-20,862 mumol/l), while the milks of cows and sheep had the lowest levels of total free AA (1061-1357 mumol/l). The milks of human subjects, chimpanzees (Pan troglodytes), gorillas (Gorilla gorilla), elephants (Elephas maximus), horses and pigs had intermediate levels of total free AA (3069-7381 mumol/l). Glutamic acid was the most abundant free AA in milks of human subjects (1339-2157 mumol/l), non-human primates (423-2528 mumol/l), elephants (1332 mumol/l), horses (1119 mumol/l), and cows (349 mumol/l). Taurine was the most abundant free AA in milks of pinnipeds (5776-13,643 mumol/l), pigs (1238 mumol/l), goats (1150 mumol/l) and sheep (341 mumol/l). Taurine was the second most abundant free AA in milks of human subjects and non-human primates, while histidine was the second most abundant free AA in milks of pinnipeds. Milks of each species had a distinctive free AA pattern which may reflect the relative importance of the free AA during early postnatal development.

Amino Acids↗
PubMed1997

Influence of dietary protein and fat on serum lipids and metabolism of essential fatty acids in rats.

A 120 d feeding study with adult rats was conducted to evaluate the influence of two protein sources (casein and gelatin), two protein levels (50 and 300 g/kg diet) and two fat levels (50 and 150 g/kg diet) on serum lipids (total cholesterol, HDL-cholesterol and triacylglycerols) and liver polyunsaturated fatty acid levels. In general, the concentrations of serum triacylglycerols and total cholesterol and liver phospholipid levels of arachidonic acid (AA) and docosahexaenoic acid (DHA) were higher in rats fed on casein diets compared with those fed on the gelatin diets. These effects were more pronounced in rats fed on the high-casein (300 g/kg)-high-fat (150 g/kg) diet. Gelatin was hypocholesterolaemic and also suppressed the liver phospholipid levels of AA and DHA (reported for the first time). The difference in the amino acid composition between casein and gelatin may be responsible for the observed effects. Casein contains higher levels of glutamic acid, methionine, phenylalanine and tyrosine, while gelatin contains higher levels of arginine, glycine and hydroxyproline. It is suggested that a protein source which increases serum cholesterol may also increase the concentrations of AA and DHA in rat tissues.

Analysis of Variance↗
PubMed1997

The protein digestibility-corrected amino acid score method overestimates quality of proteins containing antinutritional factors and of poorly digestible proteins supplemented with limiting amino acids in rats.

The validity of the protein digestibility-corrected amino acid score (PDCAAS) method in predicting the quality of fourteen protein products was compared with the commonly used protein quality methods, protein efficiency ratio (RER) and net protein ratio (NPR). A rat growth and balance study was conducted to determine protein digestibility and quality of the animal and vegetable protein products by the PER and NPR methods. Amino acid compositions of the products were also determined, and PDCAAS were calculated using a rat and a human pattern of amino acid requirements. Compared to the biological methods, the scoring method overestimated protein quality of mustard flour [PDCAAS of 84-92% vs. relative PER (RPER) or relative NPR (RNPR) of 0], raw black beans (PDCAAS of 45-72% vs. RPER or RNPR of 0), alkaline-treated lactalbumin and soybean protein isolate (PDCAAS of 44-67% vs. RPER or RNPR of 0) and heated skim milk (PDCAAS of 29-31% vs. RPER and RNPR of 0-5%). The scoring method also overestimated the protein quality of zein (true protein digestibility of 63%) supplemented with Lys, Met, Thr and Trp (PDCAAS of 63-71% vs. RPER and RNPR of 3-44%). These data demonstrate that the PDCAAS method is inappropriate for predicting protein quality of those protein sources which may contain naturally occurring growth-depressing factors or antinutritional factors formed during alkaline and/or heat processing.

Amino Acids↗
PubMed1995

A comparison of methods for determining total body protein.

The aim of the study was to find the optimal method (with respect to convenience and accuracy) for determining total protein in whole-body homogenates of rats. Three different protein extraction methods and five different protein concentration methods were assessed. The results were compared against a reference value measured by complete amino acid analysis after acid hydrolysis. The data demonstrated that extraction with 5% (w/v) sodium dodecylsulfate (SDS) in 0.5 N NaOH was far superior to that with water alone or to 6 N guanidine-HCl. A comparison of the Biuret, Bradford, and bicinchoninic acid methods on the SDS-NaOH-extracted samples showed that the Biuret method was optimal, giving a value that was 90% of the reference value with a small variation (2.4% of the mean). The Kjeldahl method gave the correct protein concentration only when a nitrogen factor of 5.51 +/- 0.03 (N = 5) was applied. The results suggest that extraction with SDS-NaOH followed by the Biuret procedure is a good method for measuring protein concentrations in whole body rat homogenates.

Amino Acids↗
PubMed1995

Effects of amylose and wheat bran on the levels of blood serum urea nitrogen (BUN), other blood parameters, growth and fecal characteristics in rats.

A basal diet (containing 20% soybean protein isolate) was supplemented with limiting amino acids (AA, methionine, threonine and tryptophan); wheat bran (WB, 24.3%); amylose (AM, 10%) or a combination of AA and WB or AM to investigate their effects on the levels of blood serum urea nitrogen (BUN), other blood parameters, growth and fecal characteristics in young rats. After 3 weeks feeding, supplementation of the basal diet with AA or WB resulted in improved growth (gain/food ratio) while the addition of AM had no effect on rat growth. Addition of WB to the basal diet had no effect on BUN while the addition of AA and AM caused about 20 and 12% reduction in BUN values, respectively. Rats fed the AA-AM diet had the lowest BUN values (42% lower than those fed the basal diet). Fresh volume, fresh weight, moisture and dry weight of feces in rats fed the WB diets were about four to five fold higher than in those fed the AM diets. The results suggested that BUN may not be a good predictor of growth and protein quality in diets containing AM or a source of dietary fiber (WB).

Amylose↗
PubMed1995

The effect of various bacteria and sera on functional activity of mouse macrophages.

The study has been performed to compare the ability of mouse peritoneal macrophages to ingest various types (catalase positive and negative) of bacteria and compared the influence of various sera on intracellular killing of Escherichia coli C (E. coli C). Among the tested microbes only E. coli C was ingested very luxuriantly and other organisms were taken up luxuriantly and moderately by mouse peritoneal resident macrophages (RMQs). Broad difference of ingestion was found even within the same genus (i.e., E. coli B and E. coli C). Intracellular killing of E. coli C by RMQs also varied depending on the type of serum. The maximum intracellular killing was found in the presence of normal mouse serum, although the difference was not much. The study has revealed that bacterial ingestion and intracellular killing ability of RMQs varies depending on bacterial strains and sera respectively.

Animals↗
PubMed1994

The protein quality of some enteral products is inferior to that of casein as assessed by rat growth methods and digestibility-corrected amino acid scores.

Protein digestibility and quality of six enteral nutrition products sold in Canada were studied by rat balance and growth methods. Casein+L-methionine, 0.2 g/100 g diet (control) and six enteral products (freeze-dried) were fed as the sole source of protein in diets containing 8.61-9.12 g/100 g protein (N x 6.25) to weanling and 18-mo-old rats for a period of 2 and 1 wk, respectively. A protein-free diet was also included in the feeding studies to permit calculations of true protein digestibility and net protein ratio values. Values for true digestibility of protein as determined in old rats for the control diet and the test products were 95 and 89-93%, respectively. Compared with old rats, protein digestibility values were 5-7 percentage units higher in young rats. The 2-wk relative protein efficiency ratio values (42-56%) or the relative net protein ratio values (61-74%) of the enteral products were considerably lower compared to those of the control (100). Supplementation of an enteral product with cysteine, cysteine + tryptophan, cysteine + threonine or cysteine + tryptophan + threonine caused significant improvement in protein quality; suggesting that the product was limiting in these three amino acids. The protein digestibility-corrected amino acid scores for the enteral products were 43-46, 69-75 and 86-93% by using whole egg, casein and the FAO-WHO (1991) pattern as reference proteins, respectively. The results indicate that these enteral products are inferior to casein in protein quality.

Amino Acids↗
PubMed1993

Evaluation of liquid chromatographic analysis of nutritionally important amino acids in food and physiological samples.

Significant advances have been made in standardizing methods for amino acid analysis of foods. The methods included standardized hydrolysis of the food proteins followed by separation and quantitation of the released amino acids by ion-exchange chromatography (IEC). IEC is still the main method in use. Its use is, however, being replaced by the faster higher-performance liquid chromatographic (HPLC) methods of derivatized amino acids. The HPLC separation of precolumn phenylisothiocyanate (PITC) derivatives has been adapted for rapid analysis of all amino acids in protein hydrolysates (12 min) and nutritionally important amino acids in deproteinized physiological samples (20 min). The inter-laboratory variability of the PITC derivatization method has not been determined although the intra-laboratory variation of the HPLC method was found to be similar to that of IEC. When similar hydrolytic conditions were used in preparing protein hydrolysates, amino acid results obtained with the PITC derivatization method were generally in close agreement with those obtained by IEC. There is, however, room for improvement in the HPLC analysis of amino acids in physiological samples.

Amino Acids↗
PubMed1993

A double-blind placebo-controlled glucose challenge in bulimia nervosa: psychological effects.

Nineteen bulimic women and 22 age-matched controls were randomly assigned to receive 25 g of glucose or a placebo injection under double-blind conditions. Blood samples of glucose, insulin, and glucagon, and psychometric assessments of mood and food cravings were obtained 10 min before, and 0, 5, 10, 20, 30, 45, and 60 min after injection. Blood levels of the large neutral amino acids (LNAAs) tryptophan, tyrosine, leucine, valine, phenylalanine, and leucine were determined at 10 min before and 60 min after the injection. Bulimic subjects were found to report more symptoms of distressed mood throughout the entire monitoring period than controls. Five minutes following glucose ingestion the self-reports of depression, fatigue, anxiety, and bewilderment rose to a level among the bulimic subjects that was above that at baseline, and was higher than that of bulimia nervosa (BN) subjects receiving placebo. No comparable change in mood was observed among controls. Blood glucose levels were correlated with mood in the bulimic group, but not in controls. In addition, the glucose injection induced a heightened urge to binge in the bulimic group (compared to placebo at 10 and 60 min), whereas reducing food cravings (for sweets) in the controls (at 5 min). When collapsed across time and injection condition, the blood glucose level of bulimics was lower than that of controls. There were no differences in insulin response between the groups. The bulimic group was found to have lower baseline levels of blood tryptophan, whereas no differences in the tryptophan/LNAA ratio were observed either at baseline or following glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗