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Biomedical subjects

M A Shah

Publications and source records attributed to M A Shah.

At least 37 records · Page 2Linked to original sources
PubMed1998

Prevalence of Helicobacter pylori antibodies in endoscopy personnel and non-medical volunteers of Karachi.

Prevalence of Helicobacter pylori (Hp) is high in developing countries. As endoscopy personnel are at greater risk of exposure to gastric secretions, they are apparently at higher risk of acquiring this infection. The aim of this study was to determine prevalence of Hp antibodies in endoscopy staff and compare it with non-medical volunteers and assess any additional risk of occupational exposure to Hp in the former group. Thirty-three subjects working in endoscopy suites of different hospitals of Karachi and 33 non-medical volunteers were investigated for the prevalence of Hp antibodies by using a commercially available rapid qualitative test (FlexPack HP; Abbott). The two groups were comparable in mean age, sex and social class. Twenty-six of 33 (79%) of the endoscopy personnel and 19/33 (58%) of the non-medical volunteers were positive for Hp serology (p = 0.06 R.R 1.37). Among the endoscopy personnel 13/14 (93%) of endoscopy assistants were positive and this subgroup had a significantly higher prevalence of Hp antibodies as compared to the control group (p = 0.019). No correlation could be found between the positive serology and symptoms of dyspepsia.

Adult↗
PubMed1998

Prevalence of pulmonary tuberculosis on the roof of the world.

SETTING: The Shimshal Valley, a remote village in Northern Pakistan, is one of the seven Pamirs of Central Asia, widely known as the roof of the world. OBJECTIVE: To investigate the prevalence of pulmonary tuberculosis (TB) in the Shimshal Valley. DESIGN: The Rapid Village Survey Method (RVS) was used to investigate the prevalence of pulmonary tuberculosis. The selection criteria were chronic cough, hemoptysis, past history of TB and close contact with a tuberculous patient. After clinical examination, a chest radiograph was done and a single spot sputum sample was obtained for smear examination. RESULTS: The total population of the village was 1077, of whom 231 cases were studied. Overcrowding affected 75% of the study population. The prevalence of smear positive pulmonary TB in the village studied was 554 per 100000 population, and the prevalence of active smear-negative TB was estimated at 1949/100 000. The prevalence of active pulmonary TB increased with age and the only risk factor for active TB was age over 45 years. Of the 21 cases with a past history of pulmonary TB, only 38% had completed a full course of chemotherapy. CONCLUSION: Pulmonary TB is a very serious health issue in the rural community (Shimshal Valley) of Pakistan. This study highlights the lack of efficacy of national tuberculosis control programs in the country.

Adolescent↗
PubMed1997

Antilymphocytic and immunosuppressive effects of Lantana camara leaves in rats.

Once daily administration of Lantana camara leaves juice at different dose levels (60, 300, 600 and 1500 mg/kg/day) for 14 days in rats resulted in alterations in various haemato- and biochemical parameters. Significant increase in blood urea nitrogen was observed with the doses of 600 and 1500 mg while significant increase in the relative weights of adrenals was observed at all the four dose levels. Total proteins, globulins, absolute lymphocyte count and per cent lymphocyte count were significantly decreased with 60, 600 and 1500 mg doses while a significant hypoglycemic effect was observed with 1500 mg only. Rats treated with 1500 mg dose did not exhibit any increase in alanine aminotransferase and aspartate aminotransferase activities or the alterations in relative kidney and liver weights. In another set of experiment, once daily oral administration of 1500 mg/kg/day for 14 days significantly inhibited the granulomatous tissue formation in rats and this effect was comparable to that of cyclophosphamide (10 mg/kg/day).

Animals↗
PubMed1996

Probing structure-activity relationship in diamine oxidase--reactivities of lysine and arginine residues.

Lysine and arginine residues of pig kidney diamine oxidase (DAO) were modified with 2,4,6-trinitrobenzenesulphonic acid (TNBS), 2,3-butanedione and phenylglyoxal, respectively, using different concentrations and time periods. Lysine residues are classified into 3 categories: completely exposed, highly reactive; sluggish, partly buried; and unreactive, completely buried. About 21 lysine residues whose modification did not lead to any significant conformational change as well as loss of catalytic activity are believed to be less important for the structural stability of the enzyme. On the other hand, the remaining 19 lysine residues are more important in maintaining the native structure of the enzyme as evidenced by the change in hydrodynamic parameters and loss of catalytic activity upon their modification. Arginine residues when probed with butanedione or phenylglyoxal treatment resulted in the significant loss of catalytic activity without any change in conformation implicating their involvement in the catalytic function of the enzyme. Significant change in conformation was noted when 10 arginine residues were modified, which suggests the structural role of these residues.

Amine Oxidase (Copper-Containing)↗
PubMed1996

Predictors of non-urgent utilization of hospital emergency services in Kuwait.

Utilization of the emergency rooms (ERs) in Kuwait has increased considerably during the last decade. Such an increase is a concern for health planners because of the burden on ER services, lack of continuous service provided by the ER and the higher cost of such services. Based on a study of 2011 patients attending the medical ERs in the six government hospitals in early 1993, the predictors of non-urgent utilization were analyzed. Patients were asked about their reasons for visiting the ER rather than the primary health care (PHC) centre. Both patients and doctors were asked to rate the urgency of the visit. According to the doctors' judgement, 61% of the visits were for non-urgent problems that did not require emergency care, while 23% of the patients viewed their visits to be non-urgent. Multiple logistic regression analysis indicated that perceived urgency of the visit was the most important predictor of a non-urgent visit to the ER, after controlling for several predisposing and enabling factors. Patients who perceived their visit to the ER to be non-urgent were about four times more likely to visit the ER for a non-urgent condition as judged by the doctor. The level of education had a significant, positive effect on non-urgent utilization among both Kuwaiti nationals and expatriates. Several factors may explain the above finding. Employment of educated persons in the hospital was one route through which education facilitated ER use. It is also likely that educated persons had more influential contacts or wasta in the hospital. Also, the less educated might have delayed seeking care while the educated consulted for non-urgent reasons as soon as they noticed the symptoms. Like education, the level of non-urgent utilization was higher among Kuwaiti nationals with higher incomes. Thus, a higher social class seems to facilitate ER use for non-urgent reasons. Among the non-Kuwaitis, lack of registration at the PHC centre was a significant reason for non-urgent use of the ER. It is recommended that hurdles in the utilization of PHC facilities should be removed. Registration of non-Kuwaitis at the PHC must be improved, and referrals to the PHC back from the ER should be instituted to ensure the necessary follow-up care.

Adult↗
PubMed1996

Ethnicity, nationality and health care accessibility in Kuwait: a study of hospital emergency room users.

In mid-1994, non-Kuwaiti expatriates constituted 61.7% of the total population of Kuwait (1.75 million). Despite this numerical majority, non-Kuwaitis exist as a social minority. Non-Kuwaitis may be grouped into three broad categories along ethnic/nationality lines into Bidoon (without nationality), Arabs, and Asians. The objective of this paper was to compare the relative accessibility of the various groups to health care services in Kuwait. The study is based on data collected as part of a survey of 2184 Emergency Room (ER) users in January-February 1993. All patients attending the hospital ERs between 7:30 am and 9:00 pm were interviewed about their reasons for coming to the ER instead of going to the primary health care (PHC) centres, as required. The major reason given was low accessibility of the PHCs. Compared to Kuwaiti nationals, 92% of whom were registered at the PHC centres, only 62% of the Arabs and 39% of the Asians were registered. Multiple logistic regression of the factors in registration indicated that nationality was the most important reason for lack of registration, with Asians only about one-quarter as likely to be registered as Kuwaitis. Also, people who had been in Kuwait for shorter durations (< 5 years) were less likely to be registered than the Kuwaiti nationals or expatriates who had been here for 10 years or longer. In the absence of registration at the PHC centre, the civil identification card (ID) may be used as a valid means to enter the health system. Among the Arabs and Asians, 22% and 29% did not have a civil ID card. Thus, for many expatriates, the hospital ER, which does not provide the necessary follow-up care is often the only source of health care available.

Arabs↗
PubMed1995

Histamine H2 receptor mediated relaxation of buffalo (Bubalus bubalus) ureter.

On the buffalo ureter, histamine did not elicit any direct effect. However, it caused concentration-dependent relaxation of the tissues precontracted by carbachol, phenylephrine, norepinephrine, KCI or BaCl2 and also inhibited the contractile effect of carbachol. Metiamide selectively antagonised the relaxation and inhibition of contractile response but mepyramine did not show this effect. Isoprenaline, dobutamine, salbutamol, verapamil and papaverine neither produced any direct effect nor relaxed the carbachol-contracted tissues; norepinephrine and epinephrine had contractile effects. Hence, the histamine-induced relaxation was mediated through the activation of H2 receptors and not through adrenergic mechanisms or blockade of Ca(2+)-channels or inhibition of cyclic nucleotide phosphodiesterase.

Animals↗
PubMed1994

Modification of pig kidney diamine oxidase with ethoxyformic anhydride and rose bengal: evidence for essential histidyl residue at the active site.

Purified diamine oxidase from pig kidney showed time dependent inactivation by ethoxyformic anhydride and photooxidation with Rose Bengal. Modification of histidine either by ethoxyformic anhydride or by Rose Bengal was the sole cause of enzyme inactivation. The inactivated enzyme showed no significant perturbation in structure. The protection against photooxidation of enzymatic activity and histidine residues by inhibitor (phenylenediamine hydrochloride) and substrate (putrescine) protected the photooxidation of two histidyl residues. However, kinetic analysis of photooxidation of histidyl residues and inactivation of the enzyme conclusively suggested the involvement of one histidyl residue, which seems to be located at the active site of diamine oxidase.

Amine Oxidase (Copper-Containing)↗
PubMed1993

Kinetics and stereospecificity of the lysyl oxidase reaction.

The structural specificity of amine oxidation by lysyl oxidase was investigated using kinetic and NMR spectroscopic analyses. Substrate efficiency increased with increasing molecular distance from the alpha-carbon of the aromatic moiety substituted on the aliphatic chains of a series of primary amines. The p-hydroxyl substituent of p-hydroxybenzylamine significantly increased kcat over that of benzylamine, whereas this was not the case when tyramine and phenethylamine were compared. Direct spectrophotometric measurement of p-hydroxybenzaldehyde formation yielded burst kinetics, the second, slower phase of which was eliminated under anaerobic conditions. Thus, enzyme reoxidation is the more rate-limiting of the two half-reactions catalyzed with this substrate by this ping-pong enzyme. 1H NMR spectroscopy of the alcohol reductively derived from the aldehyde product of the lysyl oxidase-catalyzed oxidation of deuterated tyramine indicated that the pro-S but not the pro-R alpha-deuteron was catalytically abstracted. Moreover, lysyl oxidase catalyzed solvent exchange of protons at the C-2 position. Such stereospecificity and proton exchange uniquely differentiates lysyl oxidase from all but an aortic semicarbazide-sensitive amine oxidase among the pro-S-specific copper-dependent amine oxidases analyzed thus far.

Amines↗
PubMed1993

Reaction of lysyl oxidase with trans-2-phenylcyclopropylamine.

trans-2-Phenylcyclopropylamine hydrochloride (tranylcypromine; TCP) was found to be both an inhibitor and a substrate of lysyl oxidase, the enzyme which oxidizes peptidyl lysine in elastin and collagen to initiate cross-linking in these proteins. The reaction of TCP with this enzyme was further characterized in view of the potential interference that chronic administration of this antidepressant compound may exert on the development and repair of connective tissues. In contrast to the irreversible and/or competitive inhibitors of lysyl oxidase previously described, TCP noncompetitively and reversibly inhibited the oxidation of both alkylamine and elastin substrates with Ki values of 386 and 375 microM, respectively. The noncompetitive mode of interaction affected the accessibility of the active site to productive amine substrates since the reductive trapping of n-hexylamine to lysyl oxidase was largely prevented by the presence of TCP. It was of additional interest that lysyl oxidase catalyzed a limited degree of conversion of TCP to cinnamaldehyde accompanied by the production of hydrogen peroxide. The lack of significant incorporation of protein-bound tritium accompanying reduction of the enzyme-TCP complex with [3H]NaBH4 argued against the formation of a Schiff base between the enzyme and the cinnamaldehyde product as the basis of the inhibitory effect. Spectral evidence was also obtained for an additional interaction between TCP and lysyl oxidase that was independent of the inhibitory effect of TCP. Cyclopropylamine, lacking the benzene moiety of TCP, inhibited lysyl oxidase irreversibly and competitively, and was not a substrate, pointing toward a defining role for the benzene moiety in the interaction of TCP with lysyl oxidase.

Animals↗
PubMed1992

Oxidation of peptidyl lysine by copper complexes of pyrroloquinoline quinone and other quinones. A model for oxidative pathochemistry.

Various o- and p-quinones were assessed as oxidants of peptidyl lysine in elastin and collagen substrates in the presence and absence of divalent copper as paradigms of protein-lysine 6-oxidase (lysyl oxidase) which contains both quinone and copper cofactors. Pyrroloquinoline quinone was among the most active in the absence and the most active of the o- and p-quinones tested in the presence of copper. The optimal rate of elastin oxidation occurred at a 2:1 PQQ/Cu(II) ratio while Cu(II) itself oxidized elastin relatively slightly. Elastin oxidation by 2:1 PQQ/Cu(II) required aerobic conditions consistent with oxygen-dependent turnover of this catalytic pair. Dimethylsulfoxide and catalase individually or in combination inhibited elastin oxidation by PQQ/Cu(II) by approx. 50%, suggesting that oxygen free radical species participate in the reaction. Amino-acid analysis of elastin and collagen substrates oxidized by 2:1 PQQ/Cu and then reduced with borohydride revealed that alpha-aminoadipic-delta-semialdehyde and lesser amounts of covalent cross-linkages were generated by this oxidant. In contrast, lysine oxidase produced aldehydes and significantly greater quantities of cross-linkage products, consistent with the known specificity of the enzyme. These data, thus, indicate the potential for free quinones, such as PQQ, particularly when stimulated by appropriate metal ions, to act as adventitious oxidants of lysine side-chains in proteins.

Anaerobiosis↗
PubMed1991

Asian women workers in Kuwait.

The author examines trends in the roles of immigrant Asian women workers in Kuwait, using data from published censuses and reports and from three national-level surveys conducted in 1977-1979, 1983, and 1986-1987. "The study deals separately with the two major types of migrants: the domestic servants and the clerical and professional (or semiprofessional) workers.... The policies of sending countries and of Kuwait are discussed to reach some conclusions about the likely future patterns of migration of Asian women workers to Kuwait."

Asia↗
PubMed1990

Structural and catalytic properties of copper in lysyl oxidase.

The spectral and catalytic properties of the copper cofactor in highly purified bovine aortic lysyl oxidase have been examined. As isolated, various preparations of purified lysyl oxidase are associated with 5-9 loosely bound copper atoms per molecule of enzyme which are removed by dialysis against EDTA. The enzyme also contains 0.99 +/- 0.10 g atom of tightly bound copper per 32-kDa monomer which is not removed by this treatment. The copper-free apoenzyme, prepared by dialysis of lysyl oxidase against alpha,alpha'-dipyridyl in 6 M urea, catalyzed neither the oxidative turnover of amine substrates nor the anaerobic production of aldehyde at levels stoichiometric with enzyme active site content, thus contrasting with the ping pong metalloenzyme. Moreover, the spectrum of the apoenzyme was not measurably perturbed upon anaerobic incubation with n-butylamine, while difference absorption bands were generated at 250 and 308 nm in the spectrum of the metalloenzyme incubated under the same conditions. A difference absorption band also developed at 300-310 nm upon anaerobic incubation of pyrroloquinoline quinone, the putative carbonyl cofactor of lysyl oxidase, with n-butylamine. Full restoration of catalytic activity occurred upon the reconstitution of the apoenzyme with 1 g atom of copper/32-kDa monomer, whereas identical treatment of the apoenzyme with divalent salts of zinc, cobalt, iron, mercury, magnesium, or cadmium failed to restore catalytic activity. The EPR spectrum of copper in lysyl oxidase is typical of the tetragonally distorted, octahedrally coordinated Cu(II) sites observed in other amine oxidases and indicates coordination by at least three nitrogen ligands. The single copper atom in the lysyl oxidase monomer is thus essential at least for the catalytic and possibly for the structural integrity of this protein.

2,2'-Dipyridyl↗