PubMed Health⌕ Search

Biomedical subjects

R Rahman

Publications and source records attributed to R Rahman.

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

Successful medical management of orbital abscess in a patient with sickle cell anemia.

The authors describe a patient with sickle cell anemia who had an orbital abscess at the site of a bone infarct during hospitalization for a painful crisis. Because the patient was in close medical observation, the orbital abscess was diagnosed within 48 hours of the onset of symptoms. The patient was treated with a 2-week course of intravenous antibiotics. This resulted in complete resolution of the abscess, as evidenced by clinical improvement and findings on computerized axial tomography scanning. The authors conclude that a heightened suspicion of orbital abscess in sickle cell patients with ocular symptoms will allow the diagnosis of an orbital abscess that can then be cured with antibiotic treatment but without orbital surgery.

Abscess↗
PubMed1995

Monoclonal antibodies raised against covalently crosslinked complexes of human immunodeficiency virus type 1 gp120 and CD4 receptor identify a novel complex-dependent epitope on gp 120.

The binding of the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein, gp120, to its cell surface receptor, CD4, represents a molecular interaction involving distinct alterations in protein structure. Consequently, the pattern of epitopes presented on the gp120-CD4 complex should differ from those on free gp120. To investigate this concept, mice were immunized with covalently crosslinked complexes of viral HIV-1IIIBgp120 and soluble CD4. Two monoclonal antibodies (MoAbs) obtained from the immunized mice exhibited a novel epitope specificity. The MoAbs were marginally reactive with HIV-1IIIBgp120, highly reactive with gp120-CD4 complexes, and unreactive with soluble CD4. The same pattern of reactivity was seen in solid-phase assays using HIV-1(451)gp120. A similar specificity for complexes was evident in flow cytometry experiments, in which MoAb reactivity was dependent upon the attachment of gp120 to CD4-positive cells. In addition, MoAb reactivity was detected upon the interaction of CD4 receptors with purified HIV-1IIIB virions. Notably, seroantibodies from HIV-positive individuals competed for MoAb binding, indicating that the epitope is immunogenic in humans. The results demonstrated that crosslinked gp120-CD4 complexes elicit antibodies to cryptic gp120 epitopes that are exposed during infection in response to receptor binding. These findings may have important implications for the consideration of HIV envelope-receptor complexes as targets for virus neutralization.

Animals↗
PubMed1994

Mechanism of enzyme inhibition mediated by anti-reverse transcriptase antibodies from HIV type 1-infected individuals.

We have examined the mechanisms of reverse transcriptase (RT) inhibition mediated by anti-RT antibodies, isolated by affinity chromatography, from four HIV-1-positive individuals. In kinetics assays, anti-RT immunoglobulin (Ig) obtained from three of the sera mediated a noncompetitive type of inhibition against template primer; two of these three also mediated noncompetitive inhibition with respect to deoxyribonucleoside triphosphate. Such inhibition did not require that the Ig be preincubated with RT prior to the addition of reaction components. In contrast, a more complicated pattern of inhibition was exhibited by anti-RT Ig from the fourth serum. Preincubation of this Ig with enzyme markedly enhanced the inhibition. The results demonstrate that the specificities of RT-inhibiting antibodies vary among HIV-1-infected individuals, but that one prevalent mechanism of inhibition involves interactions with epitopes outside of the enzyme active site.

Antibody Specificity↗
PubMed1994

Thalassaemia. Part 3 of 3. Counselling and community education.

In two previous articles, Simon Dyson, Verna Davis, and Raheya Rahman described the basic facts about thalassaemia and also considered the outcome of a preliminary survey establishing levels of awareness among community groups in one area. In this, the concluding article in the series, they look at the particular issues raised in thalassaemia counselling work and consider one approach to community education on the issue.

Genetic Counseling↗
PubMed1993

Hypoglycaemic activity of Coccinia indica and Momordica charantia in diabetic rats: depression of the hepatic gluconeogenic enzymes glucose-6-phosphatase and fructose-1,6-bisphosphatase and elevation of both liver and red-cell shunt enzyme glucose-6-phosphate dehydrogenase.

Coccinia indica leaves were extracted with 60% ethanol, solvents were evaporated and the residue was suspended in water. This suspension was administered orally at a dose of 200 mg/kg body wt. after 18 h of fasting to normal fed and streptozotocin-induced male diabetic rats (180-250 g). After 90 min the rats were killed, and blood-glucose, hepatic glucose-6-phosphatase, fructose-1,6-bisphosphatase and glucose-6-phosphate dehydrogenase (G6PDH) and red-cell G6PDH were assayed. Blood sugar was depressed by 23% (P < 0.01) and 27% (P < 0.001) in the normal fed and streptozotocin-diabetic rats respectively compared with controls which were given distilled water. Hepatic glucose-6-phosphatase and fructose-1,6-bisphosphatase activities were depressed by 32% (P < 0.001) 30% (P < 0.05) respectively in the streptozotocin-diabetic rats, compared with 19% (P < 0.02) and 20% (P < 0.01) depression in the normal fed controls, whereas both the red-cell and hepatic G6PDH activities were found to be elevated by feeding the extract in the streptozotocin-diabetic and in the normal fed controls. Similar results were obtained with the 95%-ethanolic extract of Momordica charantia. Taken together, these results indicate that Coccinia indica and Momordica charantia extracts lowered blood glucose by depressing its synthesis, on the one hand through depression of the key gluconeogenic enzymes glucose-6-phosphatase and fructose-1,6-bisphosphatase and on the other by enhancing glucose oxidation by the shunt pathway through activation of its principal enzyme G6PDH.

Animals↗
PubMed1993

Thalassaemia: 1 of 3. Establishing basic awareness.

Thalassaemia has until recently received little attention and consequently is not widely understood by health professionals, write Simon Dyson, Verna Davis and Rafeya Rahman. In the first of three articles they describe the illness and its treatment and the potential role for health visitors in supporting children with the condition and their families. They conclude with a brief questionnaire to test thalassaemia-awareness levels.

Blood Transfusion↗
PubMed1993

Thalassaemia: 2 of 3. Current community knowledge.

In this second of three articles Simon Dyson, Verna Davis and Rafeya Rahman describe a study carried out in Manchester for the sickle-cell anaemia and thalassaemia centre to gauge the extent of community awareness about thalassaemia, the likely level of demand for further information and how that information might most usefully be given.

Health Knowledge, Attitudes, Practice↗
PubMed1992

Delineation of immunoreactive, conserved regions in the external glycoprotein of the human immunodeficiency virus type 1.

Immunization of mice and rats with purified external glycoprotein gp120 from two divergent human immunodeficiency virus type 1 (HIV-1) isolates resulted in the development of seven hybridomas secreting monoclonal antibodies able to recognize regions of gp120 which are common among divergent strains of HIV-1. These monoclonal antibodies cross-reacted with env glycoproteins from one African (Rutz), one Haitian (RF), and three North American viral isolates, namely IIIB, MN, and 451 by either immunoblot or radioimmunoprecipitation assays. All recognized denatured gp120 in immunoblots with the exception of one which required a conformationally intact glycoprotein for reactivity. The gp120 epitopes identified by these antibodies were mapped by screening of an env gene library in the lambda gt11 expression system. Three out of four epitopes were found to reside in the amino-terminal half of gp120 (Cys9 to Cys35, Thr44 to Glu72 and Val108 to Met130), the other was located in the middle region (Thr221 to Ser255). By virtue of their extent of cross-reactivity these reagents might provide a unique resource for the detection of new viral isolates related to HIV-1.

Amino Acid Sequence↗
PubMed1992

Renal cell carcinoma treated with continuous-infusion interleukin-2 with ex vivo-activated killer cells.

High-dose recombinant interleukin-2 (rIL-2) results in tumor responses in patients with metastatic renal cell carcinoma ranging from 9 to 31%. Continuous infusion regimens of rIL-2 may be less toxic and may result in greater in vivo lymphokine-activated killer (LAK) cell production. The current trial used a continuous infusion of rIL-2 with ex vivo LAK cells. These cells were pretreated with phenylalanine methyl ester to remove monocytes to allow cell culture at higher concentrations. Twenty-three patients were entered into the trial. Two patients had complete responses (9%) lasting 15+ and 20+ months. Four patients had partial responses (17%) of 9+, 6+, 3, and 3 months, respectively. One partial responder at 9+ months had only minimal residual retroperitoneal disease that may represent scar tissue. All responders had prior nephrectomies. All but one of the responding patients completed a full cycle of rIL-2 at the highest (starting) dose, 6 x 10(6) U/m2. This rIL-2/LAK regimen appears to be an effective therapy for metastatic renal cell carcinoma.

Adult↗
PubMed1992

Characterization of a neutralizing monoclonal antibody to the external glycoprotein of HIV-1.

The major neutralizing epitope on the external glycoprotein of HIV-1 was studied with an envelope-specific monoclonal antibody and with a human serum positive for antibodies to HIV-1 proteins, both of which were able to neutralize virus infectivity. The monoclonal antibody reacted specifically with gp120 from HIV-1IIIB, and was shown to neutralize infection of CEM cells by cell-free virions, and inhibited the formation of syncytia normally observed when uninfected cells are cocultured with HIV-1-infected cells. Similar neutralization of viral infection and inhibition of syncytia formation was also demonstrated by the HIV-1-antibody-positive human serum. By examining a number of overlapping peptides from a region of HIV-1 gp120 known to contain a neutralizing epitope, this epitope was localized between amino acids 307 and 320 (V3 loop) in the external glycoprotein molecule. The monoclonal antibody did not interfere with the binding of gp120 to CD4, or with the subsequent step of CD4-induced shedding of gp120 from the viral envelope. However, it blocked the proteolytic cleavage of the V3 loop by thrombin, suggesting that the antibody may be inhibiting the interaction of the loop with other membrane-bound proteins.

Amino Acid Sequence↗
PubMed1992

Hypoglycemic effects of Coccinia indica: inhibition of key gluconeogenic enzyme, glucose-6-phosphatase.

Coccinia indica (Family: Cucurbitaceae, locally known as telakucha) leaves were extracted with 95% ethanol. Following evaporation of the solvents, the residue was suspended in distilled water. When this suspension was fed orally to male normal-fed and 48-hr starved rats, the blood glucose was lowered 21% (P less than 0.01) in normal-fed and 24% (P less than 0.001) in 48-hr starved animals respectively. Starvation had induced a 3-fold increase in the activity of glucose-6-phosphatase and this activity was depressed 19% (P less than 0.05) by extract feeding while basal activity of the enzyme in normal-fed rats remained unaffected. Consistent with the depression of glucose-6-phosphatase, urea cycle enzyme arginase was also depressed 21% (P less than 0.001) and 12% (P less than 0.01) in the liver of 48 hr-starved and normal-fed animals respectively. Unlike glucose-6-phosphatase, starvation induced levels of gluconeogenic enzymes alanine aminotransferase and aspartate aminotransferase were not affected by Coccinia extract. These results suggest that the hypoglycemic effect of C. indica is partly due to the repression of the key gluconeogenic enzyme glucose-6-phosphatase.

Animals↗
PubMed1991

Interleukin-2 lymphokine-activated killer cell therapy of non-Hodgkin's lymphoma and Hodgkin's disease.

We conducted a phase II study utilizing interleukin-2 (IL-2) with lymphokine-activated killer (LAK) cells as therapy for non-Hodgkin's lymphoma (NHL) and Hodgkin's disease (HD). IL-2 was given at a fixed dose of 3 x 10(6) U/m2/day administered as a 24-h continuous intravenous infusion with LAK cells. Nineteen extensively treated patients were entered and 15 were evaluable. In general, this regimen was reasonably well tolerated with mild toxicities that were rapidly reversible. Patients who completed therapy did so without dose attenuations. However, discontinuation of therapy was necessary in four patients due to atypical toxicities that were not clearly dose related. Two patients (one NHL and one HD) had partial remissions of brief duration, four had disease stabilization, and seven had progressive disease. While there were not sufficient numbers to evaluate critically any NHL or HD subtype, this regimen does not appear to have significant activity for either disease.

Adult↗
PubMed1991

Unusual gastrointestinal complications of interleukin-2 therapy.

Minor and reversible gastrointestinal side effects are common when patients receive interleukin-2 (IL-2) with or without lymphokine-activated killer (LAK) cells. We treated 42 cancer patients with IL-2 therapy and 3 patients developed serious gastrointestinal problems during treatment. Complications included sigmoid colon perforation, ischemic necrosis of the small and large intestine, and diffuse bowel ulceration. These were not associated with tumor implants or hypotension. Two patients died as a direct result of these problems despite aggressive surgical and medical management. The incidence of major gastrointestinal complications with IL-2 therapy may be greater than previously reported and a heightened awareness of potential gastrointestinal problems may circumvent considerable morbidity and mortality.

Adenocarcinoma↗
PubMed1991

Interleukin-2 with ex vivo activated killer cells: therapy of advanced non-small-cell lung cancer.

A phase II study was conducted to examine the efficacy of interleukin-2 (IL-2) with lymphokine-activated killer (LAK) cells as therapy for advanced non-small-cell lung carcinoma (NSCLC). IL-2 was administered at a fixed dose of 6 x 10(6) U/M2 per day as a 24 h continuous intravenous infusion (CIV) with LAK cells. Eleven patients were entered onto this study and six were evaluable. One patient had a near complete response of 18 months duration. Only two patients were able to complete the regimen without dose reduction. This regimen was poorly tolerated with pulmonary toxicity being the major problem. The partial responder was the only patient to undergo more than one course of therapy. IL-2/LAK therapy may have activity in NSCLC and further studies are warranted in this uniformly fatal disease. However, future studies will have to incorporate less toxic IL-2 regimens.

Adult↗
PubMed1990

Characterization of the secreted, native gp120 and gp160 of the human immunodeficiency virus type 1.

We have previously shown that the cell line 6D5(451) chronically infected with the HIV-1 isolate HTLV-III(451), secretes the HIV-1 envelope glycoproteins gp120 and gp160 in the extracellular medium. The HTLV-III(451) gp120 and gp160 were purified by sequential affinity chromatographic steps using a monoclonal antibody to HIV-1 gp41 and an anti-HIV-1-positive human serum. Amino acid sequence analysis of gp120 and gp160 showed the loss of the signal peptide. Digestion of the purified gp120 and gp160 with endoglycosidases revealed that both proteins are heavily glycosylated and contain complex carbohydrates, in contrast to the intracellular form of gp160 which has been shown to contain mannose-rich immature sugars. Competitive binding analysis showed that while both gp120 and gp160 bind CD4, the affinity of gp160 was five times lower than that of gp120. Both gp120 and gp160 inhibited syncytia formation by HIV-1-infected cells when mixed with CD4+ cells. Furthermore, both gp120 and gp160 had strong mitogenic effects on the T cells from HIV-1-infected gibbons but not on cells from uninfected gibbons.

Amino Acid Sequence↗