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A Sheikh

Publications and source records attributed to A Sheikh.

At least 55 records · Page 3Linked to original sources
PubMed1999

Mass spectrometric profiling of glucosamine, glucosamine polymers and their catecholamine adducts. Model reactions and cuticular hydrolysates of Toxorhynchites amboinensis (Culicidae) pupae.

Glucosamine (Gln), glucosamine polymers, and their catecholamine adducts were characterized using positive ion electrospray mass spectrometry (ESMS) and tandem mass spectrometry (ESMS-MS). N-acetyldopamine (NADA), a catecholamine found in many insect cuticles, was oxidized using mushroom tyrosinase, and the resulting quinone derivatives were reacted with Gln, (Gln)3, and polymeric glucosamine (chitosan). Adducts of glucosamine and its trisaccharide with NADA were readily identified as [M + H]+ ions in ESMS spectra, and ESMS-MS of selected ions confirmed the condensation of 1-3 NADA residues with Gln. In addition to Gln modification by the quinone derivatives of NADA, other spectra were consistent with the formation of adducts with N-acetylnoradrenaline and moieties formed by intramolecular cyclization following oxidation. The primary amine of glucosamine was involved in initial adduct formation, but the sites for subsequent additions of oxidized NADA to glucosamine, presumably via hydroxyl groups, could not be identified by ESMS alone. The ESMS spectra of chitosan films infused into the spectrometer following solubilization in acidic methanol/water produced spectra similar to that of (Gln)3 up to m/z 502. Ions of gradually decreasing intensity consistent with (Gln)x, where x = 4-8, were observed. Modification of chitosan films following incubation with NADA plus tyrosinase rendered the films insoluble in dilute acid, simulating the cross-linking process proposed to occur during insect cuticle sclerotization. Acid hydrolysates of the pupal stage of the mosquito Toxorhynchites amboinensis, using only two pupal exuviae for the hydrolyses, were infused into the mass spectrometer without preliminary chromatography. Eight amino acids, glucosamine, N-acetylglucosamine, catecholamines, and a variety of polymers incorporating these compound classes were identified.

Animals↗
PubMed1998

Phosphate poisoning by ingestion of clothes washing liquid and fabric conditioner.

A case of deliberate ingestion of clothes washing liquid and fabric conditioner is described. Tracheal intubation and controlled ventilation became necessary because of respiratory muscle dysfunction associated with hypocalcaemia. We suggest that the phosphate component of the clothes washing liquid was responsible for the dramatic metabolic upset and subsequent need for admission to the Intensive Care Unit.

Adult↗
PubMed1997

Cholera in a developing megacity; Karachi, Pakistan.

Despite rapid urbanization and increasing affluence in Karachi, cases of cholera are frequent. We analysed computerized isolation data from the AKUH Clinical Microbiology Laboratory, Karachi, from 1990-6 to examine microbiological, temporal and demographic trends in Vibrio cholerae infections. During this period 888 strains of V. cholerae (566 V. cholerae serogroup O1, and 204 V. cholerae serogroup O139) were isolated from specimens from 886 patients; 214/464 were adult inpatients, and 250/464 paediatric inpatients, the remaining 422 outpatients. Isolations peaked between June and August. Overlapping epidemics occurred in 1993 and 1994 of serogroup O1 (May to August), and serogroup O139 (August to October). All ages and social and economic strata were affected. Forty-four percent of all isolates were from children under the age of 5 years. The mean age of all patients with serogroup O1 infections was 19.6 years (+/-0.9) compared with 367 (+/-1.7) for serogroup O139 infections (P < 0.0001, t test). More than a quarter (27%) of all serogroup O1 isolates were from babies under 2 years of age. One patient had a serogroup O1 infection followed by a serogroup O139 infection 1 year later. Another patient was infected with serogroup O1 strains 5 years apart. Emergence of resistant strains was observed, but by 1996 serogroup O139 had disappeared. An aquatic organism, cholera nevertheless continues to take its toll in this city of 11 million situated in a desert.

Adolescent↗
PubMed1997

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Equipment Failure↗
PubMed1996

Epidemiology of adults hospitalized with burns in Karachi, Pakistan.

Burns are a leading cause of adult death in Karachi slums, therefore we reviewed 1 year's logged experience (November 1992 to October 1993) at Karachi's two adult burn units for patient age, sex, burn severity and outcome. Also 47 inpatients were interviewed regarding their circumstances of injury. We grouped these using Haddon's Matrix. The log identified 832 patients. Females (57 per cent) outnumbered males and were younger on average (25.1 vs 27.6 years, P = 0.002). Females had more severe burns than males (57 per cent vs 50 per cent total body surface area (TBSA) burn, P = 0.002). At the unit with outcome data (n = 556), the case fatality was 56 per cent. The estimated adult mortality due to burns in Karachi was 10.2/100 000, 6.8/100 000 and 14.1/100 000 for men and women, respectively. Burns of interviewed patients were most often associated with flames (33/47), but stove bursts caused the most severe injury (52 per cent TBSA). These patients were predominantly young uneducated female houseworkers, clothed in loose attire who were injured during daylight at home around a floor-level stove, unaware of fire safety, and who received no first aid. It was concluded that the high burn severity and case fatality rates demand: (1) preventive measures, such as kitchen sand buckets, safer stove design and placement and education on fire safety and first aid, and (2) risk factor analysis to refine interventions.

Accidents, Home↗
PubMed1996

A study of the incorrect use of ventilator disconnection alarms.

Pressure-sensitive ventilator disconnection alarms may fail to function correctly when used with discharging compliance ventilators such as the Manley Blease. The increase in gas flow on disconnection generates raised pressure owing to the resistance provided by components of the breathing system. Thirty-four anaesthetists, who were unaware of the nature of the survey, were observed to see if previous recommendations for the correct adjustment of the ventilator alarm were being followed. It was found that 77% of alarms were incorrectly adjusted and would not have alarmed in the event of a true disconnection occurring.

Anesthesia, General↗
PubMed1994

In vitro and in vivo response of hepatocytes from hepatic nodules to the mitoinhibitory effects of phenobarbital.

One of the proposed mechanisms by which phenobarbital (PB) promotes hepatocarcinogenesis in the rat is by differential mitoinhibition. However, our earlier studies indicated that PB inhibited DNA synthesis in vitro in hepatocytes isolated from both surrounding non-nodular liver and hepatic nodules promoted by orotic acid (OA). Since nodules generated by one promoter need not necessarily be resistant to another promoter, the present study was undertaken to determine whether foci/nodules promoted by PB itself are resistant to the mitoinhibitory effects of PB. Accordingly, rats were initiated with diethylnitrosamine (DENA, 200 mg/kg i.p) and promoted with PB (0.07% of PB as its sodium salt) in their drinking water for 16 or 33 weeks. In vitro studies indicated that PB (3-5 mM) inhibited DNA synthesis induced by epidermal growth factor (EGF) in hepatocytes from surrounding non-nodular liver as well as from nodules promoted by PB for 33 weeks. In another experiment, initiated rats exposed to PB for 33 weeks were subjected to either two-thirds partial hepatectomy (PH) or sham hepatectomy. Hepatocytes were labelled with tritiated thymidine in vivo for 48 h. Autoradiographic analysis indicated that in the presence of PB, the hepatocytes from both foci/nodules and the surrounding non-nodular liver responded to PH to the same extent. In addition, they both responded to PH less efficiently as compared to the corresponding controls. Further, initiated rats exposed to PB for 16 weeks when subjected to PH and killed 4 weeks thereafter, the percentage area occupied by gamma-glutamyltranspeptidase-positive foci/nodules in the PB group increased, but to the same extent as in initiated control rats not exposed to PB. The above results raised an interesting possibility that the lack of resistance of the PB-promoted nodules to the mitoinhibitory effects of PB may be because the PB-promoted nodule does not express a resistant phenotype. To examine this aspect, the response of hepatocytes from 33 week PB-promoted nodules to the mitoinhibitory effects of OA was examined. The results indicated that OA (60-120 microM) inhibited EGF-induced DNA synthesis in hepatocytes isolated from both nodules as well as from surrounding non-nodular liver. These results suggest that PB is a mitoinhibitor but may not provide a strong differential growth advantage to foci/nodules in response to a proliferative stimulus. Further, the nodules promoted by PB do not appear to express the resistant phenotype, defined as being resistant to the mitoinhibitory effects of OA and PB.

Animals↗