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Biomedical subjects

S Mahmood

Publications and source records attributed to S Mahmood.

At least 55 records · Page 3Linked to original sources
PubMed1998

Effect of sodium on Saccharomyces cerevisiae invertase activity.

Effect of Na+ ions on yeast invertase activity has been studied as a function of pH. At acidic pH, Na+ (5-100 mM) had no effect but invertase activity was inhibited (38-44%) by Na+ ions (100 mM) with an increase in pH (6.8 and 8.0). Kinetic analysis revealed that invertase inhibition by Na+ ions was non-competitive and reversible in nature. Value of K(m) remained unaltered (33.3 mM) in presence of Na+ (20-100 mM) while Vmax decreased by 21-44% under these conditions. Value of Ki was of the order of 85 mM. Mechanism of observed inhibition of invertase activity as a consequence of Na+ ions interactions at the active site of the enzyme has been described.

Glycoside Hydrolases↗
PubMed1998

Harmaline interactions with yeast invertase.

The effect of harmaline, a plant alkaloid has been studied on yeast invertase activity in the absence and presence of 50mM Na+ as a function of pH. Harmaline (1-3 mM) inhibited the invertase activity at pH 5.2, 6.8 and 8 both in the absence (44-92%) and (22-85%) of Na+ ions. Kinetic analysis revealed that harmaline is a non-competitive inhibitor of invertase, at pH 5.2 and 6.8 but at pH 8, it produced a mixed type of inhibition, Km increased by 450% and 175% and Vmax decreased by 82% and 63% in the absence and presence of 50mM Na ions respectively. The observed inhibition of invertase by harmaline was reversible in nature. These findings suggest that the presence of Na+ site is not a prerequisite for the inhibition of enzyme by harmaline.

Glycoside Hydrolases↗
PubMed1997

GATA-6 DNA binding protein expressed in human gastric adenocarcinoma MKN45 cells.

A cDNA for the GATA-6 (GATA-GT1) DNA binding protein was cloned from a library of the human gastric adenocarcinoma cell line MKN45. The deduced amino acid sequence (449 residues) indicates that the primary structure of human GATA-6 is highly homologous to that of the rat protein. The potential phosphorylation site for protein kinases (A and C), and histidine and alanine clusters are conserved. Whereas the rat H+/K+-ATPase alpha and beta subunit genes have two and three GATA protein binding sites in their promoter regions, respectively, the human alpha subunit gene has only one binding site [Maeda, M., Kubo, K., Nishi, T. and Futai, M. (1996) J. Exp. Biol. 199, 513-520]. We cloned the 5'-upstream region of the human H+/K+-ATPase beta subunit gene by genome walking and found that it also has a single GATA protein binding site near the TATA box. The GATA sites of the human alpha and beta subunit genes are recognized by the zinc finger domain of human GATA-6. The conservation of the GATA protein binding sites suggests that they are important for the gene regulation of the human and rat H+/K+-ATPase.

Adenocarcinoma↗
PubMed1997

Rat intestinal alkaline phosphatase II messenger RNA is present in duodenal crypt and villus cells.

BACKGROUND & AIMS: Rats produce two messenger RNA (mRNA) isoforms encoding intestinal alkaline phosphatase that are regulated differentially by fat feeding but whose tissue distribution is not known. The aim of this study was to examine the distribution of these isoforms along the crypt/villus axis during fat feeding. METHODS: Nucleotide probes and polyclonal antibodies unique for each isoform were used for in situ hybridization and immunocytochemistry. RESULTS: mRNAs encoding isoforms I and II were distributed along the entire villus. The mRNA content of isoform II was more abundant. Quantitative grain counts showed that mRNA abundance of each isoform in the upper third of the villus was significantly (40%-65%) lower than in the remaining villus in the fasting duodenum. After fat feeding, the mRNA content of both isoforms increased over the villus. Five hours after feeding, the content of the mRNA encoding only isoform II was increased in the upper third of the villus relative to the rest of the villus. Only the mRNA encoding isoform II was found in the crypt cells. However, no immunoreactive enzyme was present in the crypt cells. CONCLUSIONS: The spatial expression of the two rat intestinal alkaline phosphatase isoforms is regulated differently in response to fat feeding.

Alkaline Phosphatase↗
PubMed1997

The role of hyperfractionated re-irradiation in metastatic brain disease: a single institutional trial.

Progression of brain metastases after brain irradiation has prompted several studies on retreatment of the brain. Increased durations of survival and improved quality of life have been reported. Fifteen patients with previously treated brain metastases were entered into this pilot study between May 1990 and January 1994. All patients had neurologic and/or radiologic evidence of progression of brain metastases. The lung was the primary site in 60% of cases. The remaining 40% had breast, ovarian, and skin primaries. The median interval between the first treatment and retreatment was 10 months. All patients received whole-brain irradiation with or without a boost for their initial treatment course. Doses ranged from 3,000 to 5,500 cGy for initial treatments (median, 3,000). Retreatment consisted of limited fields with a median side equivalent square of 8.8 cm. Patients were retreated with a median dose of 3,000 cGy (range, 600-3,000 cGy). A median cumulative dose of 6,000 cGy was achieved. Retreatment consisted of twice-daily fractions (150 cGy/fraction). Retreatment was tolerated without serious complications. Of the 15 patients treated, nine (60%) experienced improvement, and five (27%) had stabilization of neurologic function and/or radiographic parameters. Median survival was 3.2 months; two of the reirradiated patients survived > or = 9 months. In conclusion, reirradiation is a viable option in patients with recurrent metastatic lesions of the brain, and the use of a limited retreatment volume makes this a well-tolerated, low-morbidity treatment that leads to clinical benefits and, in some instances, enhanced survival. The influence of hyperfractionation on the outcome needs to be investigated further in large series.

Adult↗
PubMed1997

Assessment of nutritional beliefs and practices in pregnant and lactating mothers in an urban and rural area of Pakistan.

Nutritional beliefs and practices in 100 pregnant and 100 lactating women were assessed in an urban and rural area of Lahore. A structured questionnaire was used for the purpose. Seventy seven percent women and 54% of their husbands were illiterate, 50.5% belonged to a family with a per capita income of more than Rs.300.00 per month, 52.5% had 7 or more family members and 56% were living in nuclear families. The age of mothers, type of family, literacy, family income, parity and gravidity had not significantly influenced the nutritional beliefs and practices, only urban and rural differences were statistically significant. Eight-four percent of mothers had knowledge that diet should be changed by increasing, adding or avoiding some special food items in the diet during pregnancy and lactation, but only 65.5% practiced them. The reasons for this deficient knowledge and practice of dietary intake are lack of nutritional knowledge and poor economy. However, this can be overcome by improving nutritional knowledge and dietary practices of population in general and vulnerable groups in particular through media and MCH services on the use of locally available low cost nutritious foods and to avoid undue food restrictions. Improvement of applied nutritional knowledge of medical professionals is also necessary.

Adult↗
PubMed1996

Deficient nitric oxide responsible for reduced nerve blood flow in diabetic rats: effects of L-NAME, L-arginine, sodium nitroprusside and evening primrose oil.

1. This study examined the potential role of impaired nitric oxide production and response in the development of endoneurial ischaemia in experimental diabetes. Rats were anaesthetized (Na pentobarbitone 45 mg kg-1, diazepam 2 mg kg-1) for measurement of sciatic nerve laser Doppler flux and systemic arterial pressure. Drugs were administered into the sciatic endoneurium via a microinjector attached to a glass micropipette. 2. In two separate studies comparing diabetic rats (streptozotocin-induced; 8-10 wk duration) with controls, nerve Doppler flux in diabetic rats (Study 1, 116.6 +/- 40.4 and Study 2, 90.1 +/- 34.7 (s.d.) in arbitrary units) was about half that measured in controls (219.6 +/- 52.4 and 212.8 +/- 95.5 respectively; P < 0.005 for both). There were no significant differences between the two in systemic arterial pressure. 3. Inhibition of nitric oxide production by microinjection of 1 nmol L-NAME into the endoneurium halved flux in controls (to 126.3 +/- 41.3 in Study 1 and 102.1 +/- 38.9 in Study 2; both P < 0.001), with no significant effect in diabetic rats, indicating markedly diminished tonic nitric oxide production in the latter. D-NAME was without effect on nerve Doppler flux. 4. L-Arginine (100 nmol), injected after L-NAME, markedly increased flux in controls (by 65.8% (P < 0.03) and 97.8% (P < 0.01) in the two studies) and by proportionally similar amounts in diabetic rats [75.8% (P < 0.001) and 60.2% (P < 0.02)]. The nitro-donor, sodium nitroprusside (SNP; 10 nmol) had similar effects to L-arginine in both groups (increases of 66.0% in controls and 77.5% in diabetics; both P < 0.002). 5. A second diabetic group, treated with evening primrose oil performed exactly like control rats in respect of responses to L-NAME, L-arginine and SNP. 6. These findings implicate deficient nitric oxide in nerve ischaemia of diabetes and suggest correction thereof as a mechanism of action of evening primrose oil.

Animals↗
PubMed1995

High-resolution renal SPECT in eight minutes using a multi-detector gamma camera.

Planar renal scintigraphy with Tc-99m DMSA has become established as a standard diagnostic test to determine if a kidney has been scarred by infection. It has been suggested that high resolution SPECT may improve the sensitivity of detection of renal scars. To determine if it is possible to produce good quality renal SPECT with a short acquisition time, 10 adults were examined with a new multi-detector gamma camera using 8 minute, 16 minute, and 32 minute acquisitions. The number of defects seen (N = 16) with an 8 minute acquisition was not significantly different from the defects (N = 15) seen using a 16 minute and a 32 minute acquisition. In adults when imaging with a multi-detector gamma camera there was no clinical advantage in using an acquisition of longer than 8 minutes.

Adolescent↗
PubMed1995

Combined rest thallium-201/stress technetium-99m-tetrofosmin SPECT: feasibility and diagnostic accuracy of a 90-minute protocol.

UNLABELLED: Technetium-99m tetrofosmin is a recently developed compound that clears from background organs rapidly. Tetrofosmin has a good correlation with 201Tl. This study assesses the feasibility and diagnostic accuracy of a combined protocol involving rest 201Tl SPECT and stress imaging with 99mTc-tetrofosmin. METHODS: Twenty-five patients (23 men, 2 women; aged 36-73 yr) with known coronary artery disease underwent the combined protocol. Twenty minutes after the resting injection of 201Tl, resting SPECT data were acquired using low-energy, high-resolution collimators. A stress test using adenosine infusion combined with low-level dynamic exercise was performed. The stress data were collected 20 min later. The reconstructed vertical long-axis, horizontal long-axis and short-axis slices were analyzed qualitatively. Analysis was carried out using nine segments of the left ventricle. The segments were reported either as fixed or reversible. The results were compared to coronary angiography results. RESULTS: The sensitivity and specificity for the detection of diseased coronary vessels were 85% and 70% for the left anterior descending territory, respectively, 78% and 71% for the right coronary artery, and 69% and 70% for the left circumflex. Overall, the sensitivity was 80% and the specificity 70%. CONCLUSION: Combined rest 201Tl/stress 99mTc-tetrofosmin SPECT provides a protocol of short duration which displays similar diagnostic accuracy to a protocol using tetrofosmin as a single agent.

Adult↗
PubMed1994

Bradycardia progressing to cardiac arrest during adenosine thallium myocardial perfusion imaging in occult sino-atrial disease.

Adenosine is used increasingly as an alternative to dynamic exercise during myocardial perfusion imaging because it is a powerful coronary vasodilator with a short half-life. Minor side-effects are common but life-threatening events are rare. We report two cases of provocation by adenosine infusion of profound sinus bradycardia progressing to atrial and ventricular asystole. Despite discontinuation of the infusion, asystole persisted for up to 1 min in one case and was accompanied by a grand mal seizure. Normal sinus rhythm returned spontaneously in both cases without long-term sequelae. Sino-atrial disease was later suggested in both cases by 24-h electrocardiographic monitoring. We conclude that patients to whom adenosine is given may have occult sino-atrial disease and may be susceptible to life-threatening arrhythmias. Significant sinus bradycardia during the infusion may provide a warning of its presence.

Adenosine↗
PubMed1994

The diagnosis and assessment of an adult with anomalous origin of the left coronary artery from the pulmonary artery.

Anomalous origin of the left coronary artery from the pulmonary artery (the Bland-White-Garland syndrome) is a rare congenital cardiac defect which may present for the first time in adulthood. The recognition of this disorder, which produces widespread left ventricular ischaemia and the risk of sudden death, myocardial infarction and congestive heart failure, is important as the prognosis can be improved by surgical intervention. Thallium-201 scintigraphy has a useful role in demonstrating the widespread nature of the ischaemia of the left ventricle, whilst the diagnosis is confirmed at cardiac catheterisation.

Adult↗
PubMed1994

Rumen degradability of dry matter and crude fibre of irradiated and sodium hydroxide treated straws.

Wheat straw (WS) and triticale straw (TS) were treated with 2- and 4%-NaOH and/or 300- and 600-kGy radiation doses (accelerated electrons) for improvement of the nutritional value of these feeds. Beside the chemical composition of straws, the nylon bag rumen disappearance of dry matter and crude fibre was estimated. NaOH did not influence the chemical composition of straws, while irradiation significantly reduced the level of crude fibre (CF), neutral detergent fibre (NDF) and acid detergent fibre (ADF) proportionally to the dose. The level of nitrogen free extractives (NFE) and alpha-linked glucose polymers pronouncedly increased in the radiated straws. NaOH treatment raised potential rumen degradability of DM and irradiation did so in the case of potential as well as effective degradability. It was not able to prove the summarized influence of both treatments on DM and CF rumen degradability of the straws. The dynamics of the rumen disappearance of DM was different in the straws.

Animal Feed↗
PubMed1994

201Tl myocardial perfusion SPET: adenosine alone or combined with dynamic exercise.

201Tl myocardial perfusion single photon emission tomography (SPET) with pharmacological coronary vasodilatation using adenosine is now often used in the investigation of a patient with ischaemic heart disease (IHD). In this study, we present data from two groups of patients. Group A (n = 40) experienced 201Tl SPET with adenosine only as the pharmacological stress test, using an infusion rate of 140 micrograms kg-1 min-1. Group B patients (n = 50) had the same test combined with low-level dynamic exercise. The side effects were noted for both groups and 201Tl SPET studies were acquired for stress and redistribution images. There was a lesser degree of non-cardiac side effects in patients of group B. There was a significant difference in the haemodynamic parameters between the two groups. There was no significant difference in overall sensitivity (87% versus 90%) and specificity (84% versus 88%) in the detection of IHD between the two groups. In conclusion, addition of low-level dynamic exercise with adenosine is to be preferred to adenosine infusion alone, as this protocol is better tolerated and may enhance the detection of right coronary artery disease (sensitivity = 82% versus 90%, n.s.).

Adenosine↗
PubMed1994

Clinical experience with a multidetector SPET system (Toshiba GCA-9300A).

The clinical experience with the Toshiba GCA-9300A single photon emission tomography (SPET) system is discussed along with typical acquisition protocols for various SPET studies. The system was used to perform SPET studies in normals and in a variety of brain and body disorders. Its three Anger-type gamma cameras forming a triangular aperture offer a substantial increase in sensitivity compared to a single rotating gamma camera. This has allowed the routine use of lead fanbeam super high-resolution collimators (SHR FB) for 99Tcm-hexamethylpropyleneamine oxime (HMPAO) brain SPET studies and high-resolution parallel-hole collimators (HR PH) for cardiac and other body studies. The resulting improvement in spatial resolution coupled with the ease of patient positioning and the greater patient throughput compared to a conventional tomographic gamma camera, will enhance the role of brain and body SPET for both routine and research purposes.

Bone and Bones↗
PubMed1994

Longevity of dental restorations in selected patients from different practice environments.

The objective of the study was to evaluate the long-term survivals or longevity of dental restorations placed in selected patients from different practice environments in two countries. The case histories of 46 adult patients with 622 restorations placed in three private practices in Pakistan were followed for a minimum of 10 years, and compared with similar assessments of 50 adult patients with 966 restorations placed in a dental hospital in Australia. Amalgam and composite resin restorations showed similar survivals in both countries, but cast gold restorations had much lower survivals in the Pakistan group of patients. In both countries, restoration survivals were significantly better in females, and when patients attended less frequently for treatment. For the Australian group, changes in dental operators also gave significantly better survivals, and there were significant restoration survival differences present between the three practices in Pakistan.

Adult↗
PubMed1993

Characterization of proteins in rat and human intestinal surfactant-like particles.

Phospholipid-rich particles isolated from the apical surface of rat enterocytes have surfactant-like properties and are enriched for intestinal alkaline phosphatase. Purified intact rat particles were used to produce antibodies in rabbits. Antiserum against the rat particle identified major proteins of 48, 68, 98, and 118 kDa on Western blots of isolated rat surfactant-like particle and did not detect any protein in rat intestinal basolateral membranes, rat brush border membranes, or human particles, but did detect a single 180-kDa protein in a preparation of rat milk fat globules, and two proteins (66 and 103 kDa) in rat pulmonary surfactant. The proteins detected on Western blot corresponded with the major proteins identified by Coomassie blue staining. Similar particles were isolated from the apical surface of human intestine and had an enzyme composition, buoyant density, and lipid content similar to those of the rat particles. Antiserum raised against the human jejunal particle detected proteins in the human particle by Western blot that were similar in size with the rat particle proteins (33, 52, 75, 82, and 118 kDa), but did not cross-react with human brush border or rat particle proteins. These studies demonstrate that the surfactant-like particles are present in human as well as rat intestinal tissue, demonstrate similar enzyme and protein content, and confirm their unique identity, distinct from apical brush border or basolateral membranes.

Animals↗
PubMed1993

A comparison of effects of body weight and feed intake on digestion in broiler cockerels with effects of tannins.

The effects of body size and feed intake on N digestibility, pancreas and liver weight, and digestive enzyme activities in male broiler chicks were compared with those induced by dietary tannins. Four groups (SSM, ad lib., pair-fed and young) of sixteen birds each (2 weeks old) were used as experimental animals. They were fed on experimental diets for 4 weeks, except the young group which were fed from age 15 d to 24 d only. Two isonitrogenous and isoenergetic diets with (SSM) or without salseed (Shorea robusta) meal (CONTROL) were used. SSM diet was fed ad lib. to SSM group and control diet was fed ad lib. to ad lib. and young birds and to pair-fed birds at same intake level as SSM birds. Birds fed ad lib. utilized their diet more efficiently than the SSM and pair-fed birds. Digestibility of N, both apparent and ileal, was substantially lower with SSM diet than with the control diet. Each of the treatments induced enlargement of the pancreas (g pancreas/kg live weight) when compared with ad lib. birds. There was no difference between the relative liver weights of SSM and ad lib. birds; however, pair-fed and young birds had comparatively bigger livers. In pair-fed birds the trypsinogen activity of pancreatic tissue (U/g pancreatic tissue) was significantly depressed but there was a significant elevation in trypsinogen (U/kg live weight) activity in SSM birds; again pair-fed birds exhibited the lowest value for this variable.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗