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Biomedical subjects

R Ahmad

Publications and source records attributed to R Ahmad.

At least 109 records · Page 6Linked to original sources
PubMed1990

Haemodynamic effect of supraaortic ridge enhancement on the closure mechanism of the aortic valve and its implications in aortic valve repair.

The presence of the sinus of valsalva plays an essential part in the closing mechanism of the aortic valve. High-energy vortices are initiated at the upper limit of each sinus or supraaortic crest, and last during the whole valve closing time. An attempt was made to prove this hypothesis in vivo by intermittent augmentation of each supraaortic ridge. In a series of five dogs without cardiopulmonary bypass, pledgeted sutures were placed at the level of each crest and passed through tourniquets. In a series of three sheep, similar sutures were placed under direct vision with cardiopulmonary bypass. The supraaortic crests were augmented or maintained normal by tightening or loosening the tourniquets repeatedly. Simultaneous aortic and ventricular pressures and 2D- and M-mode echocardiography were recorded. In the dog series the results were unpredictable due to variability in the supraaortic crest enhancement because the sutures did not correspond to the anatomical crest. In the sheep series the sutures were correctly placed and M-mode echocardiography demonstrated a significant (p less than 0.01) shortening in systolic time. These results suggest the use of enhancement of the supraaortic crest as an adjunct technique in aortic valve repair.

Animals↗
PubMed1990

Hyperosmolar nonketotic hyperglycemia manifested as ascending polyneuropathy.

We have described a case of hyperosmolar nonketotic hyperglycemia atypically manifested as an ascending progressive predominantly motor neuropathy with sensory involvement. Although the patient noticed polydipsia, the lack of endogenous renal function prevented the expected polyuria and dehydration. Treatment with insulin produced such marked clinical improvement that 15 days after admission he was discharged home, fully mobile and self-sufficient. Because hyperosmolar nonketotic decompensation is uncommon and patients may initially have neurologic signs without a previous history of diabetes mellitus, the diagnosis may be overlooked.

Combined Modality Therapy↗
PubMed1990

Fractionated urinary cytology in the follow-up of bladder cancer.

Cytological examination of voided urine is an established investigation in urological practice. In a pilot study of 50 patients with histologically proven transitional cell carcinoma of the bladder, urine cytology was undertaken on samples from the initial, mid-stream and terminal parts of the void. Analysis showed that although the cell density varied between the samples in some cases, no part of the void was consistently richer in benign or malignant cells and similar cell types were seen in every sample from any given patient. It was concluded that fractionated cytology did not improve the diagnostic accuracy of urinary cytology and that any sample of urine was suitable for cytological purposes.

Adult↗
PubMed1990

Acute retention of urine: is trial without catheter justified?

Following an episode of acute retention of urine in men it is commonplace for urinary catheters to be removed to see if micturition is re-established. Many patients will require definitive treatment, however and, to assess which patients do benefit from a trial without catheter, the outcome of this practice was analysed against the relevant features of the history in 100 men. The majority of patients both with and without previous symptoms suggestive of outflow obstruction had further retentions. Trial without catheter was of value in three groups of patients: those with urinary tract infection without previous obstructive symptoms, those with gross constipation and those recently commenced on drugs with anticholinergic properties. With these exceptions, definitive treatment was necessary in 93% of the remainder. Most of those in whom micturition was re-established are still under active review and may yet come to surgery, in view of poor flow rates. With the exceptions detailed above it is concluded that trial without catheter is not justified in acute retention of urine and definitive treatment should be instituted at an early stage.

Acute Disease↗
PubMed1990

A study of urolithiasis in North West Frontier Province of Pakistan.

Of 188 (144 renal, 29 bladder, 15 ureteric) stones analysed, 109 (58%) were pure calcium oxalate stones and in 177 (94%) calcium oxalate was the main component. The remaining were of mixed composition containing calcium phosphate, uric acid and calcium hydrogen phosphate. Serum calcium levels in 50 patients with pure calcium oxalate stones were normal. Majority of the cases (76%) came from the hilly areas of N.W.F.P.

Adult↗
PubMed1990

Bovine genitourinary tuberculosis revisited.

Bovine tuberculosis is now rare in the western world. We report a case of bovine genitourinary tuberculosis causing obstructive renal failure. This combination does not appear to have been previously reported.

Acute Kidney Injury↗
PubMed1989

Interleukin-1 production in acute viral hepatitis.

The in vitro production of interleukin-1 in 15 children with acute hepatitis A and five children with acute hepatitis B was determined by measuring lymphocyte activating factor secreted by peripheral blood monocytes in a thymocyte proliferation assay. Aluminium hydroxide induced production of lymphocyte activating factor was significantly lower in patients with acute hepatitis A as well as patients with hepatitis B as compared with healthy control subjects. In both forms of acute viral hepatitis production of lymphocyte activating factor was severely depressed during the first week, increased gradually during the further course of the illness, but did not reach normal concentrations within the first three weeks after onset of the acute symptoms of the disease. No correlation could be found between in vitro production of lymphocyte activating factor and the severity of liver disease as estimated by the rise of serum concentrations of transaminases, bilirubin, or several parameters of acute phase reaction (alpha 1 antitrypsin, C reactive protein, erythrocyte sedimentation rate). The reduced production of interleukin-1, as assessed by determination of lymphocyte activating factor, could explain the only moderate acute phase reaction seen during acute viral hepatitis.

Acute Disease↗
PubMed1988

Phagocytosis of serum-opsonized zymosan down-regulates the expression of CR3 and FcRI in the membrane of human monocytes.

The effect of iC3b receptor (CR3)-mediated phagocytosis on the expression of CR (C3b receptor, CR3) and IgG FcR (FcRI, FcRII) has been investigated by using serum-opsonized zymosan as a multivalent ligand for CR3. Sixteen hours after a short (1-h) pretreatment of human monocyte monolayers with zymosan opsonized with human AB serum (250 micrograms/ml), CR3 expression (as assessed by flow cytometric analysis with mAb Mo1) was significantly reduced by 59 +/- 3% (mean +/- SEM, n = 15, p less than 0.001). Concomitant with CR3 down modulation, FcR binding activity (as assessed by binding of IgG-coated E) was also found to be decreased to 41 +/- 4% of control (n = 7, p less than 0.001). Reduced FcR function was paralleled by a decrease in the expression of FcRI (as assessed with mAb 32.2). This FcRI modulation was not caused by zymosan-bound IgG because zymosan opsonized with agammaglobulinemic serum equally down regulated CR3 and FcRI expression. Pretreatment with zymosan opsonized with human AB serum, however, did not change the expression of other IgG and C-binding sites such as FcRII (examined with mAb IV.3 and 2E1) and CR1 (assessed with mAb 57F) as well as of unrelated cell membrane structures (beta 2m, MHC class II). In contrast, co-modulation for FcR function and CR3 expression induced by polymeric IgG is accompanied by a decreased expression of FcRII. These data indicate that interaction of a specific receptor with its ligand not only changes the expression of the receptor triggered, but has also a modulating effect on other receptor systems on the same cell.

Antigens, Differentiation↗
PubMed1988

Effect of anticalmodulin drugs on testosterone synthesis in hCG stimulated mouse Leydig cells.

The effect of three anticalmodulin drugs, prepared in this laboratory and a commercially available drug Mastoparan, was tested on the secretion (or synthesis) of testosterone in hCG stimulated Leydig cells. The results of the use of drugs RN-IV A, RN-IV B and RN-IV C indicated that hCG (10 ng/ml), DbcAMP (0.1 mM) and cholera toxin (2 micrograms/ml)-stimulated testosterone production was inhibited in Leydig cells in a dose dependent manner. In hCG stimulated cells, the ID50 for drug RN-IV A was 2 microM, for drug RN-IV B was 25 microM and for drug RN-IV C was 130 microM. Based on ID50 the most effective drug was RN-IV A. Maximum inhibition of testosterone production was obtained at a concentration of 20 microM for drug RN-IV A, 150 microM for drug RN-IV B and 200 microM for drug RN-IV C. Further extensive experiments with drug RN-IV B showed that (a) at 100 microM concentration the drug does not impair the binding of receptor with 125I hCG, (b) the cAMP accumulation was prevented in a dose dependent manner reaching a minimal of 1.1 pM at 50 microM, compared with 3.5 pM in hCG (10 ng/ml) stimulated cells. The drug RN-IV B at a concentration of 100 microM, which failed to prevent conversion of exogenous pregnenolone or progesterone to testosterone, otherwise caused complete inhibition of testosterone production in hCG stimulated cells. Mastoparan also inhibited testosterone production in hCG stimulated cells in a dose dependent manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Grand mal fitting in a patient on regular haemodialysis treatment and receiving desferrioxamine therapy.

Fitting due to aluminium toxicity has been previously reported in chronic dialysis patients with prolonged exposure to aluminium, resulting in excessive aluminium accumulation. However, we report a case of a patient who fitted whilst receiving Desferrioxamine therapy, following a fall with the consequent sudden release of aluminium from fractured ribs. This suggests that sudden increases in serum aluminium levels may carry neurological sequelae.

Aluminum Hydroxide↗
PubMed1988

Comparable modulation of human monocyte functions by commercial factor VIII concentrates of varying purity.

Our previous observation on immune modulation induced by a given factor VIII (F VIII) concentrate preparation was extended by showing that the immune-modulating capacity is a more general feature of F VIII products and is independent of product purity. Interaction of human monocytes with therapeutic concentrations of various F VIII concentrates (0.2 to 2 IU F VIII/mL, six different F VIII concentrates from four manufacturers) led to a significant reduction in the expression of IgG Fc receptors in the membrane of these cells (F VIII concentrate-induced downmodulation of the receptor). This Fc receptor downmodulation was achieved by a short (1-hour) incubation of human monocytes with F VIII concentrates 16 hours prior to the Fc receptor assay and did not correlate with the respective product's IgG content. Although the IgG concentrations of the different products varied greatly (from 1.0 to 177.3 mg/1,000 IU F VIII), all products behaved comparably with respect to Fc receptor downmodulation (F VIII-treated monocytes: 34% +/- 7% to 44% +/- 4% rosette-forming cells; controls in the absence of F VIII: 83% +/- 5%). Furthermore, we also were able to demonstrate that heat treatment of F VIII, now used by virtually every manufacturer to eliminate contaminating viruses, had no effect on the respective products' Fc receptor-modulating capacity. The immune-modulating component was characterized as being a high-molecular-range compound containing IgG, IgM, F VIII, and blood group substances (most likely a combination of immune complexes and immunoglobulin aggregates). This compound is present in comparable amounts in both high-purity and intermediate-purity products and apparently copurifies with F VIII during the manufacturing process.

Antigen-Antibody Complex↗