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Biomedical subjects

A Khan

Publications and source records attributed to A Khan.

At least 379 records · Page 21Linked to original sources
PubMed1994

A view of HIV-I infection in Karachi.

A prospective study on the prevalence of HIV-I infection in Karachi, Pakistan was conducted over a period of six years (1986-1992). Over 15,000 individual samples and more than 32,000 donor units of individuals residing in Karachi at the time of sample collection were tested for HIV-I infection by our screening test EIA which revealed a positivity rate of 0.23% and 0.003% in individual and donor units respectively by Western Blot. We divided patients into four groups A, B, C and D based on the most plausible cause of transmission. The largest number of positive patients belonged to group B, who were of either foreign origin or expatriates or Pakistanis settled abroad. They comprised approximately 67% of the total positive cases and were subjected to testing on strong clinical grounds. In individuals of other groups like group A and D, there was history of travel abroad from time to time. The only positive donor unit (group C) belonged to a person who had been living in Middle East for the last 10-12 years. The last group D comprised of samples that were directly sent to us without complete history, except for the fact that they had been travelling back and forth. The large majority of patients fell in 20-50 years age group. Despite the limitations of this study, we conclude that the prevalence of HIV is steadily increasing in our population and so far, we have not been able to find an indigenous case of AIDS in our series.

Adolescent↗
PubMed1993

Investigation of retroviral involvement in chronic fatigue syndrome.

Within the last few years significant efforts have been made to identify objective reliable diagnostic markers from individuals with chronic fatigue syndrome (CFS). We report the absence of a previously described retroviral marker (HTLV-II gag) in a blinded study of CFS cases. Even with excellent reproducible sensitivities, this marker failed in repeated attempts to distinguish cases from controls. In addition, four other retroviruses (simian T cell leukaemia virus, human spumavirus, bovine leukaemia virus and simian retrovirus) were examined for their presence in these CFS cases and found to be absent. Our findings suggest that these agents, at least as markers, are non-distinguishing for CFS and that other factors may be confounding the resolution of an aetiology to this syndrome.

Biomarkers↗
PubMed1993

Temporary management of selected pharyngocutaneous fistulas with a silicone septal button.

Management of a pharyngocutaneous (PC) fistula following laryngopharyngectomy with or without neck dissection is a difficult problem, particularly in cases where repair cannot be accomplished in a reasonable period of time. Use of a silicone septal button is described in the temporary management of selected PC fistulas (i.e., fistula size not more than 1 cm). This technique has been used successfully to date in three patients whose salivary fistulas were located directly above their stomas. The silicone septal button worked as a useful temporary measure in preventing salivary spillage into the stoma und was well tolerated by the patients treated until definitive closure was possible.

Aged↗
PubMed1993

Abnormal insulin secretion and glucose metabolism in pancreatic islets from the spontaneously diabetic GK rat.

Insulin secretion and islet glucose metabolism were compared in pancreatic islets isolated from GK/Wistar (GK) rats with spontaneous Type 2 (non-insulin-dependent) diabetes mellitus and control Wistar rats. Islet insulin content was 24.5 +/- 3.1 microU/ng islet DNA in GK rats and 28.8 +/- 2.5 microU/ng islet DNA in control rats, with a mean (+/- SEM) islet DNA content of 17.3 +/- 1.7 and 26.5 +/- 3.4 ng (p < 0.05), respectively. Basal insulin secretion at 3.3 mmol/l glucose was 0.19 +/- 0.03 microU.ng islet DNA-1.h-1 in GK rat islets and 0.04 +/- 0.07 in control islets. Glucose (16.7 mmol/l) stimulated insulin release in GK rat islets only two-fold while in control islets five-fold. Glucose utilization at 16.7 mmol/l glucose, as measured by the formation of 3H2O from [5-3H]glucose, was 2.4 times higher in GK rat islets (3.1 +/- 0.7 pmol.ng islet DNA-1.h-1) than in control islets (1.3 +/- 0.1 pmol.ng islet DNA-1.h-1; p < 0.05). In contrast, glucose oxidation, estimated as the production of 14CO2 from [U-14C]glucose, was similar in both types of islets and corresponded to 15 +/- 2 and 30 +/- 3% (p < 0.001) of total glucose phosphorylated in GK and control islets, respectively. Glucose cycling, i.e. the rate of dephosphorylation of the total amount of glucose phosphorylated, (determined as production of labelled glucose from islets incubated with 3H2O) was 16.4 +/- 3.4% in GK rat and 6.4 +/- 1.0% in control islets, respectively (p < 0.01). We conclude that insulin secretion stimulated by glucose is markedly impaired in GK rat islets.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

The duration of placement as a predictor of peripheral and pulmonary arterial catheter infections.

To determine the appropriate time for removal or replacement of peripheral and pulmonary arterial catheters in critically ill cancer patients, we prospectively studied 71 peripheral arterial catheters and 71 pulmonary artery (Swan-Ganz) catheters from 110 consecutive cancer patients. All catheters were cultured semiquantitatively, by the roll-plate culture technique. Of the 71 peripheral arterial catheters, 11 (15%) produced local infections (> or = 15 colonies) and four (5.5%) produced catheter-related septicaemia. Ten of the 11 local infections and all four septicaemias occurred after 4 days of catheter placement (P < 0.05). Likewise, of the 71 Swan-Ganz catheters, 12 (17%) produced local infection and four (5.6%) led to septicaemia. Swan-Ganz catheter-related septicaemia occurred at rates of 2% and 16%, before and after 7 days of catheter placement, respectively (P = 0.056). Duration of placement was a risk factor for the development of catheter infections, independent of the patient's neutropenic status, administration of antibiotics such as vancomycin during catheterization, and the presence of concurrent central venous catheters. Life-table analysis showed that the cumulative risks of developing a catheter infection increased from 7% to 17% after 6 days of peripheral arterial catheter placement and from 9% to 18% after 4 days of placement of the Swan-Ganz catheter. We conclude that in the critically ill cancer patient in our unit, peripheral arterial catheters should be changed to a new site every 4-6 days and pulmonary artery catheters every 4-7 days.

Adolescent↗
PubMed1993

Can ECT-induced cognitive effects be altered pharmacologically?

1. A systematic review of the literature revealed twelve clinical trials that evaluated nine different drugs, and used three different conceptual models to prevent, restore or treat ECT-induced cognitive deficits. 2. This review indicated inconclusive results regarding clinical utility of any of the drugs. 3. Major factors discussed include the complexities involved in the evaluation of ECT-induced cognitive deficits, and the techniques of evaluating changes in cognitive functions. 4. Our conclusion is that future research should emphasize understanding the neural mechanisms related to ECT-induced cognitive deficits. We suggest several areas for future exploration.

Cognition Disorders↗
PubMed1993

Evidence for a rebound coagulation phenomenon after cessation of a 4-hour infusion of a specific thrombin inhibitor in patients with unstable angina pectoris.

OBJECTIVES: In a Phase I clinical trial, we studied the antithrombotic and clinical effects of the synthetic competitive thrombin inhibitor, argatroban, in 43 patients with unstable angina pectoris. BACKGROUND: Thrombin has a pivotal role in platelet-mediated thrombosis associated with atheromatous plaque rupture in patients with an acute ischemic coronary syndrome. However, the efficacy of conventional heparin therapy to prevent ischemic events is limited and has been surpassed by that of specific thrombin inhibitors in experimental models of arterial thrombosis. METHODS: Intravenous infusion of the drug (0.5 to 5.0 micrograms/kg per min) for 4 h was monitored by sequential measurements of coagulation times and of indexes of thrombin activity in vivo followed by a 24-h clinical observation period. RESULTS: Significant dose-related increases in plasma drug concentrations and activated partial thromboplastin times (aPTT), but no bleeding time prolongation or spontaneous bleeding, was observed. Myocardial ischemia did not occur during therapy but, surprisingly, 9 of the 43 patients experienced an episode of unstable angina 5.8 +/- 2.6 h (mean +/- SD) after infusion. This early recurrent angina was correlated significantly with a higher argatroban dose and with greater prolongation of aPTT but not with other demographic, clinical, laboratory and angiographic characteristics. Pretreatment plasma concentrations of thrombin-antithrombin III complex and fibrinopeptide A were elevated two to three times above normal values. During infusion, thrombin-antithrombin III complex levels remained unchanged, whereas a significant 2.3-fold decrease in fibrinopeptide A concentrations was observed. By contrast, 2 h after infusion, thrombin-antithrombin III complex concentrations increased 3.9-fold over baseline measurements together with return of fibrinopeptide A levels to values before treatment with argatroban. CONCLUSIONS: In patients with unstable angina, argatroban inhibits clotting (aPTT prolongation) and thrombin activity toward fibrinogen (fibrinopeptide A decrease), but in vivo thrombin (thrombin-antithrombin III complex) formation is not suppressed. However, cessation of infusion is associated with rebound thrombin (thrombin-antithrombin III complex) generation and with an early dose-related recurrence of unstable angina. Although the mechanism of this clinical and biochemical rebound phenomenon remains to be determined, its implication for the clinical use of specific thrombin inhibitors in the management of ischemic coronary syndromes may be significant.

Aged↗
PubMed1993

The tissue distribution of factor XIIIa positive cells.

Factor XIIIa has previously been used to identify a subgroup of dermal dendritic cells which co-express class II MHC antigens, intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function associated antigen-1 (LFA-1), leading to the suggestion that they play a central role in skin immune responses. To examine whether these cells may also be important constituents of other organs we have performed an immunohistochemical survey of normal tissue to identify the distribution of this factor XIIIa positive subgroup of dendritic cells in humans. Routine tissue sections from a range of organs were assayed for factor XIIIa expression using a standard peroxidase-antiperoxidase (PAP) immunolabelling technique. Dendritic, factor XIIIa positive cells were observed in all tissues studied, but were most numerous in skin and mucosal tissues (gastrointestinal tract, bladder). They were also observed associated with epithelial structures in lung and kidney, but were only rarely observed in liver, thyroid, testis and spleen. The distinctive distribution of these cells is consistent with an important role for them in immune responses at those sites.

Connective Tissue↗
PubMed1993

Low-dose thyrotropin-releasing hormone effects in cognitively impaired alcoholics.

The cognitive effects of a low dose of thyrotropin-releasing hormone (TRH) (2.0 mg, IV) were evaluated in 18 chronic alcoholic patients who exhibited memory dysfunction secondary to chronic alcohol abuse. The study used a double-blind crossover design that compared cognitive functions in patients with 2.0 mg of TRH IV as compared with a placebo. TRH was chosen because of its ability to enhance cholinergic transmission. Only minimal effects were seen with TRH. Patients with a shorter duration of alcohol use (mean of 16 years) performed significantly better with TRH as compared with placebo on a test involving verbal learning and memory. Those with a more chronic history of alcohol abuse (mean of 27 years) did not show such a response. All of the subjects showed cardiovascular response to TRH. Factors that may have contributed to the results of our study are discussed. It is our impression that future studies evaluating the cognitive effects of TRH in chronic alcoholics need to include an evaluation of the functional activity of TRH in the brain.

Adult↗
PubMed1993

Disseminated Pneumocystis carinii infection involving the neck and nasopharynx.

In summary, several points should be emphasized: 1. Adenoidal hypertrophy in a person who previously underwent adenoidectomy should lead to the suspicion of HIV infection. 2. P. carinii should be included in the differential diagnosis of adenoidal enlargement in HIV infections. 3. Extrapulmonary calcification should lead to the suspicion of P. carinii infection.

AIDS-Related Opportunistic Infections↗
PubMed1993

ECT and TRH: cholinergic involvement in a cognitive deficit state.

In this paper we describe the findings from two preliminary experiments, a human and an animal study, investigating whether thyrotropin-releasing hormone (TRH) can mitigate electroconvulsive therapy (ECT)-induced cognitive deficits. Our results suggest further explorations of TRH and its analogs as possible therapeutic agents for these deficits. We speculate that the major cause of the ECT-induced cognitive deficits is a decrease in cholinergic transmission in the central nervous system. Treatments such as TRH, which enhance cholinergic activity, can reverse the cognitive deficits.

Adult↗