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Biomedical subjects

A Zaidi

Publications and source records attributed to A Zaidi.

At least 37 records · Page 2Linked to original sources
PubMed1999

Patients view of the anaesthetist in a developing country.

OBJECTIVE: The objective of this study was to assess patients regarding their knowledge and perception of the anaesthetists' role in patient care in a developing country. SETTING: The audit was conducted at the Aga Khan University Hospital, Karachi. METHODS: Two hundred surgical and 102 medical out-patients were included in the audit prospectively who filled a detailed questionnaire. RESULTS: Fifty-six percent of the patients knew that anaesthetists were medically qualified but only 20% and 27% had an idea about their role in the intraoperative and immediate postoperative period. 14.6% were aware of the anaesthetists role outside the operating room. No difference was observed between the two groups of patients except that a higher percentage of surgical patients were interested in having more information regarding anaesthesia and wanted to choose their anaesthetist if the need arose. Gender difference was observed in answer to two questions only. A higher percentage of males know the role of anaesthetist in the recovery room whereas a greater number of females who had surgery before remembered their anaesthetist postoperatively. CONCLUSION: The results of this audit show a poor perception of the anaesthetists role both inside and outside the operating room. Although public knowledge surveys have been carried out in developed countries there is a pressing need to repeat these in developing countries since the image as perceived by public may have a direct bearing on the recruitment of young doctors into an already shortage specialty in these less affluent countries.

Anesthesia↗
PubMed1998

Decrease in Ca-ATPase activity in aged synaptosomal membranes is not associated with changes in fatty acyl chain dynamics.

We have examined lipid peroxidation (LPO) and fatty acid acyl chain dynamics in synaptosomal membranes isolated from aged rat (Fischer 344 x Brown Norway F1 hybrids) brains, correlating these results with measurements of enzymatic activity of the synaptic plasma membrane Ca2(+)-ATPase (PMCA). Calcium-dependent ATPase activity in these membranes exhibits progressive decreases with a maximal loss of activity with age of approximately 35%. The sensitivity of this membrane-bound ion transporter to the lipid composition of the surrounding membrane, as well as the high abundance of oxidatively sensitive polyunsaturated fatty acyl chains in synaptosomal membranes, suggests that this age-related loss in catalytic turnover may result from LPO-mediated protein modification and/or changes in the physical structure of the bilayer. However, high-performance liquid chromatography analysis of 2,4-dinitrophenylhydrazone derivatives reveals no significant age-related increases in the content of reactive aldehydes (malondialdehyde, formaldehyde, acetaldehyde or acetone) which comprise breakdown products of lipid peroxidation. Electron paramagnetic resonance measurements employing 5- and 12-stearic acid spin labels with the nitroxide reporter groups at two depths in the bilayer were used to assess the fatty acyl chain dynamics (fluidity) of synaptosomal membranes. The resulting spectra demonstrate anisotropic lipid dynamics of two populations of lipids, i.e. lipids in direct association with membrane proteins (boundary lipids) and bulk lipids that do not directly associate with proteins. The nanosecond dynamics of both lipid populations is unaltered with age indicating that any compositional changes occurring with age are insufficient to result in alterations in bilayer fluidity relevant to PMCA activity. Thus, the observed age-related decline in PMCA activity may be explained by direct modification of membrane protein.

Aging↗
PubMed1998

Sensitivity of the synaptic membrane Na+/Ca2+ exchanger and the expressed NCX1 isoform to reactive oxygen species.

Two plasma membrane proteins, the Na+/Ca2+ exchanger (NCX) and the Ca2+-ATPase, are major regulators of free intraneuronal Ca2+ levels as they are responsible for extrusion of Ca2+ from the intracellular to the extracellular medium. Because disruption of cellular Ca2+ regulation plays a role in damage occurring under conditions of oxidative stress, studies were conducted to assess the sensitivity of the NCX to reactive oxygen species (ROS). Exchanger activity in brain synaptic plasma membranes and in transfected CHO-K1 cells was inhibited following brief exposure to the peroxyl radical generating azo initiator 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH) and to peroxynitrite. Incubation with hydrogen peroxide did not alter NCX activity, even at 800 microM concentration. In CHO-K1 cells transiently transfected with the NCX1 isoform of the exchanger, AAPH treatment decreased the maximal transport capacity (Vmax), whereas the K(act) remained unchanged. Peroxynitrite led to an increase in K(act) with no change in Vmax. Loss of activity following exposure to either AAPH or peroxynitrite was associated with the formation of high molecular weight aggregates of NCX, and AAPH also caused fragmentation of the exchanger protein. These findings suggest that the NCX is sensitive to biologically relevant ROS and could be involved in the loss of Ca2+ homeostasis observed under oxidative stress.

Amidines↗
PubMed1998

Orthotopic heart transplantation in a transgenic pig-to-primate model.

BACKGROUND: Previous studies demonstrated that hearts from transgenic pigs expressing human decay-accelerating factor (hDAF) were not hyperacutely rejected when transplanted heterotopically into the abdomen of cynomolgus monkeys. This study examines orthotopic transplantation of hDAF transgenic pig hearts into baboon recipients. METHODS: Orthotopic xenogeneic heart transplantation was performed using piglets, transgenic for hDAF, as donors. Ten baboons were used as recipients and were immunosuppressed with a combination of cyclophosphamide, cyclosporine, and steroids. RESULTS: Five grafts failed within 18 hr without any histological signs of hyperacute rejection. Pulmonary artery thrombosis induced by a size mismatch was observed in two of these animals. The other three recipients died because of failure to produce even a low cardiac output and/or dysrhythmia. The remaining five animals survived between four and nine days. One animal died of bronchopneumonia on day 4. Three xenografts stopped beating on day 5 due to acute vascular rejection. The longest survivor was killed on day 9 with a beating, histologically normal xenograft, because of pancytopenia. CONCLUSIONS: The results reported here demonstrate that hDAF transgenic pig hearts are not hyperacutely rejected when transplanted into baboon recipients. Orthotopically transplanted transgenic pig hearts are capable of maintaining cardiac output in baboons. An optimum immunosuppressive regimen is the subject of ongoing research.

Animals↗
PubMed1998

Life-supporting pig-to-primate renal xenotransplantation using genetically modified donors.

BACKGROUND: In order to circumvent the complement-mediated hyperacute rejection of discordant xenografts, a colony of pigs transgenic for the human regulator of complement activity, human decay-accelerating factor (hDAF), has been produced. METHODS: Seven kidneys from hDAF transgenic pigs and six kidneys from nontransgenic control pigs were transplanted into cynomolgus monkeys; both native kidneys were removed during the same operation. The recipient animals were immunosuppressed with cyclosporine, steroids, and cyclophosphamide. RESULTS: In the transgenic group, the median survival time was 13 days (range, 6-35 days); the median survival time in the control group was 6.5 days (range, 0.3-30 days). There were no cases of hyperacute rejection in the transgenic group, and the two longest-surviving kidneys in this group showed no evidence of rejection on histological examination. In contrast, all control kidneys underwent antibody-mediated rejection, one demonstrating hyperacute rejection and the others acute vascular rejection. CONCLUSION: This study demonstrates that (i) a kidney from an hDAF transgenic pig can support the life of a primate for up to 35 days (and also shows the basic physiological compatibility between the pig and nonhuman primate); (ii) nontransgenic kidneys are not routinely hyperacutely rejected; and (iii) the presence of hDAF on the kidney confers some protection against acute vascular rejection. Improved immunosuppression and immunological monitoring may enable extended survival.

Animals↗
PubMed1997

Eliminating access to anonymous HIV antibody testing in North Carolina: effects on HIV testing and partner notification.

Anonymous HIV testing may attract persons who might otherwise not be tested but may hinder partner notification. We evaluated the effects on North Carolina's HIV testing and partner notification programs of policy changes that eliminated and later restored anonymous testing in 82 counties. We used an interrupted time-series design to compare counties eliminating with counties retaining anonymous testing. We analyzed HIV testing and partner notification data from before, during, and after elimination of anonymous testing. After elimination of anonymous testing in 82 counties, the mean monthly level of testing (+/- SE) increased by 45%, or 548 (+/- 123) tests per month, while in 18 counties that retained anonymous testing, there was a 63% increase, or 802 (+/- 162) tests per month (p > .05). Among men of all races, testing increased by 16%, or 155 (+/- 35) tests per month, in counties that eliminated anonymous testing; and by 51%, or 305 (+/- 42) tests per month (p < .05), in counties that retained anonymous testing. After elimination of anonymous testing, both county types experienced similar increases in the rate of partners notified. However, partner notification was more successful if the index patient was tested confidentially; 2.7 times as many partners per index patient were notified and counseled. There was no effect on testing or on partner notification rates following restoration of anonymous testing. Substantial community opposition to eliminating anonymous testing was encountered. The policy change appeared to result in a slight decrease in testing among men and a slight increase in partners notified. Programs considering the elimination of anonymous testing should weigh these potential gains and losses, as well as the impact on relationships between the public health and advocacy communities

Confidentiality↗
PubMed1997

Comparison of nalbuphine and buprenorphine in total intravenous anaesthesia.

Nalbuphine (0.3 mg.kg-1) and buprenorphine (2.5 micrograms.kg-1) were compared as part of a total intravenous anaesthesia regimen using a propofol infusion in 60 patients undergoing laparoscopic cholecystectomy in a randomised double-blind study. Changes in haemodynamic variables greater than 20% from the baseline were noted. No difference was observed in blood pressure but the heart rate was significantly lower in the buprenorphine group. Intra-operative bradycardia (heart rate < 60 beat.min-1) occurred more often in the buprenorphine group. Recovery was fast and comparable with both drugs and no patient reported awareness. Quality of analgesia was similar in both groups. Both drugs provide suitable analgesic supplementation to total intravenous anaesthesia.

Adult↗
PubMed1997

Detection of autoantibodies to nuclear antigens by EIA and IF techniques.

The detection of antibodies to certain nuclear components has considerable importance in the diagnosis and management of patients with autoimmune diseases. In this study, antibodies to nuclear antigens in 250 positive and negative patient specimens were detected by immunofluorescence (IF) and enzyme immunoassay (EIA). Specimens were tested by three different EIA assays for autoantibodies to SS-A, SS-B, Scl-70 Sm, RNP, Jo-1, ENA, Histone, ss-DNA and ds-DNA and one IF assay for Antinuclear Antibodies (ANA). The majority of positive specimens were also confirmed positive by Western Blot. Ninety-seven percent of IF-ANA positive specimens assayed positive by EIA-ENA assay and only 6% of ENA negative specimens tested positive in IF-ANA assay indicating that EIA-ENA assay is as reliable as IF-ANA for screening patient specimens. Forty-five percent of EIA Jo-1 positive specimens showed negative IF-ANA results indicating that IF-ANA assay is not a reliable method for detection of antibodies to Jo-1. This may be due to the fact that specimens with low titer and sera which are positive for a limited number of specific nuclear antigen(s) cannot produce visible or clear fluorescence patterns and therefore are reported negative by IF-ANA. Our data shows that both methods are reliable for screening purposes, however EIA has greater specificity over IF because the presence or absence of antibody to a specific antigen can be better assessed. Overall, due to higher reproducibility, low cost, antigen specificity, and the nature of EIA, we recommend microtiter-based EIA assays for detection of antibodies to nuclear antigens.

Antibodies, Antinuclear↗
PubMed1996

A field trial of wheat-based oral rehydration solution among Afghan refugee children.

A total of 326 Afghan children aged between 6 months and 5 years with uncomplicated nondysenteric diarrhea for the previous 24 h to 5 days were treated at home by their mothers with either wheat-salt solution (WSS) or World Health Organization recommended glucose-oral rehydration salts (G-ORS). For 7 consecutive days the children were examined in the household and the mothers interviewed to assess the progress, feeding practices, and perception of treatment efficacy. Children treated with WSS recovered significantly earlier; the mean duration on treatment was 4.0 days (SD 1.7 days) on WSS compared to 6.4 days (SD 1.7 days) on G-ORS. By the second day of treatment, significantly more mothers using WSS (56%) reported that their children had formed stools versus 11% of their G-ORS counterparts; the mean stool frequency after 2 days was also significantly reduced; 3 stools day-1 (SD 2.1) on WSS versus 5 (SD 2.9) on G-ORS. The cereal-based solution was not confused with normal food and led to better feeding patterns. By day 2, 74% of the mothers using WSS had resumed their normal feeding frequencies as opposed to 33% of G-ORS mothers. On recovery the WSS group had gained significantly more weight; the WSS group gained 169 g (SD 142 g) while the G-ORS group lost 150 g (SD 174g). This study suggests by subjective and objective measures that WSS could be considered as an effective home fluid for the first-line treatment of diarrhea.

Acute Disease↗