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Biomedical subjects

M Zaki

Publications and source records attributed to M Zaki.

At least 55 records · Page 3Linked to original sources
PubMed1996

Somatostatin receptor subtype 2 mediates inhibition of gastrin and histamine secretion from human, dog, and rat antrum.

BACKGROUND & AIMS: In gastric antrum, somatostatin exerts a tonic inhibitory influence on gastrin and histamine secretion. Five different subtypes of somatostatin receptors, designated sst1-5, have been identified. sst2, sst3, and sst5 subtypes have been localized to the stomach by molecular biological techniques. The aim of this study was to identify the sst subtype regulating gastrin and histamine secretion in human, dog, and rat stomach. METHODS: Mucosal segments from human, dog, and rat antrum were superfused with various concentrations of somatostatin 14 and somatostatin analogues selective for sst2, sst3, and sst5. Gastrin and histamine were measured by radioimmunoassay. RESULTS: Somatostatin 14 and the sst2 agonist EC 5-20 inhibited gastrin and histamine secretion from all three species in a concentration-dependent manner, whereas the sst3 and sst5 agonists had no significant effect. Neutralization of endogenous somatostatin with the somatostatin antibody increased gastrin and histamine secretion. The increases were not affected by the gastrin antagonist but were abolished by the sst2 agonist, implying that the inhibitory influence of ambient somatostatin is exerted directly on the histamine cell rather than indirectly via changes in gastrin secretion. CONCLUSIONS: Somatostatin inhibits gastrin and histamine secretion in human, dog, and rat antrum by activating sst2 receptors on gastrin and histamine cells.

Animals↗
PubMed1996

CNN: a speaker recognition system using a cascaded neural network.

The main emphasis of this paper is to present an approach for combining supervised and unsupervised neural network models to the issue of speaker recognition. To enhance the overall operation and performance of recognition, the proposed strategy integrates the two techniques, forming one global model called the cascaded model. We first present a simple conventional technique based on the distance measured between a test vector and a reference vector for different speakers in the population. This particular distance metric has the property of weighting down the components in those directions along which the intraspeaker variance is large. The reason for presenting this method is to clarify the discrepancy in performance between the conventional and neural network approach. We then introduce the idea of using unsupervised learning technique, presented by the winner-take-all model, as a means of recognition. Due to several tests that have been conducted and in order to enhance the performance of this model, dealing with noisy patterns, we have preceded it with a supervised learning model--the pattern association model--which acts as a filtration stage. This work includes both the design and implementation of both conventional and neural network approaches to recognize the speakers templates--which are introduced to the system via a voice master card and preprocessed before extracting the features used in the recognition. The conclusion indicates that the system performance in case of neural network is better than that of the conventional one, achieving a smooth degradation in respect of noisy patterns, and higher performance in respect of noise-free patterns.

Algorithms↗
PubMed1996

Technical and safety aspects of blood and marrow transplantation using G-CSF mobilized family donors.

An allogeneic transplantation programme using immunoselected blood progenitor and bone marrow CD34+ cells has been established. Thirteen healthy HLA-matched, MLC negative sibling donors received two doses of 5 micrograms kg-1 G-CSF (s.c. daily) for 5 days. On days 4 and 5, large-volume mononuclear cell aphereses were performed (COBE Spectra) and on day 5 one unit of autologous blood was obtained. Mononuclear cells were pooled and cryopreserved after CD34+ cell-immunoselection on day 5. Bone marrow (BM) of the same donors was procured under routine conditions 10-45 days later (median: 27 days). The final graft consisted of blood CD34+ cells with either complete BM (n = 5) or immunoselected BM CD34+ cells (n = 8). The present paper describes the progenitor cell mobilization and apheresis protocol and analyzes the cell loss by BM and peripheral blood progenitor cell (PBPC) donation. Considerably larger amounts of mononuclear cells (CD45+), T-lymphocytes (CD3+) and platelets were lost by the apheresis as compared to bone marrow without apparent immediate clinical consequences for the donors. Owing to cross-cellular contamination of the apheresis concentrate, blood platelet count (PC) significantly decreased (mean PC after the second apheresis 116 x 10 microL-1); furthermore on average 3.04 x 10(10) CD3+ cells were removed by two apheresis sessions. This loss did not lead to long-term total lymphocyte count changes (2370 microL-1 versus 1889 microL-1) as observed during the long-term follow-up of 7/13 donors (mean 290 days). Subjectively, the PBPC collections were better accepted than BM donations in all but one family donor.

Adult↗
PubMed1996

Prevalence of Toxoplasma gondii and cytomegalovirus antibodies in patients with chronic renal failure.

This study aimed to determine the prevalence of Toxoplasma gondii and cytomegalovirus (CMV) antibodies in patients with chronic renal failure (CRF) with and without haemodialysis. To achieve this goal, 60 patients with CRF in addition to 20 healthy controls were investigated. Patients were classified into 3 groups, group 1 comprised 20 patients with CRF who haven't any haemodialysis sessions (under conservative treatment) group II comprised 20 patients with CRF due to primary renal diseases already on haemodialysis and group III comprised 20 patients with renal failure secondary to collagen disease or accompanied by liver disease undergoing haemodialysis. Out of 60 patients, Toxoplasma antibodies were detected in 38.3% and in 15% of the normal controls with a statistical significant difference. From the present results, it was noticed high percentages of positivity for Toxoplasma and CMV antibodies in patients with CRF undergoing haemodialysis which was also correlated to the number of the dialysis sessions. So, it can be concluded that CRF patients undergoing haemodialysis should be screened for Toxoplasma and cytomegalovirus before dialysis to prevent the dissemination of these infections through dialysis procedure.

Adult↗
PubMed1995

Evaluation of serum peptide banding patterns of patients on hemodialysis therapy by discriminant analysis.

The present study was directed towards determining serum protein abnormalities, with emphasis on protein deficits in patients on short- and long-term hemodialysis. Serum protein profiles of healthy controls and chronic and end-stage renal failure patients on hemodialysis were analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. A total of 104 distinct peptide bands in the molecular weight range of 23 kDa to 300 kDa were encountered for both healthy and patient populations. The SPSS/PC+ discriminant analysis employing group mean statistics revealed significant protein deficits in the patient population. As many as 72 (69.23%) of the 104 individual peptide bands had lower mean scores for the patients as compared to the healthy subjects. In all, 21 (29.2%) of these peptide bands belonged to the high molecular weight range of 185 kDa to 300 kDa while 13 (18.1%) were located in the low molecular weight range of 23 kDa to 36 kDa. To show that patients and healthy controls can be categorized into their respective groups on the basis of their serum protein profiles, a 100% correct classification was established by group membership prediction analysis. Furthermore, using minimization of Wilk's lambda as the criterion for variable selection, it was found that the 285 kDa, 265 kDa, 250 kDa, 155 kDa, 125 kDa, 110 kDa, 32 kDa, 27.5 kDa, 26 kDa and 23.5 kDa serum peptide bands were the most important in classifying an individual as healthy or diseased.

Adolescent↗
PubMed1995

Seroprevalence of Toxoplasma gondii in domestic animals in Pakistan.

The seroprevalence of Toxoplasma gondii infections among food animals in South-West Pakistan was measured by serological examination using a commercial latex agglutination test (LAT). In all 262 blood samples, from 100 cattle, 40 sheep, 58 goats and 64 chickens, were collected from the city abattoir. Titers considered diagnostically significant (> or = 1:64) were detected in 25% of cattle and 2.5% of sheep. None of the goats and chickens presented seropositivity for anti-toxoplasma antibodies. The study suggests the need for further investigations to determine the impact of these findings on the human population.

Animals↗
PubMed1994

HLA antigens in Arab children with steroid-responsive nephrotic syndrome.

Forty-eight Arab patients with steroid-responsive childhood nephrotic syndrome were studied for the frequency of HLA-A, -B, -C and -DR antigens. HLA-DR7 was significantly increased in the patient group (63% vs. 28%, P = 0.0002) confirming reports of a DR7 association in other ethnic groups and indicating a universal association with this antigen. HLA-CW6 was also significantly increased (44% vs. 21%, P corr. = 0.042). HLA-DQW1 was significantly reduced in the patients (29% vs. 57%, P corr. = 0.012) as was HLA-CW4 (6% vs. 24%, P corr. = 0.042).

Child, Preschool↗
PubMed1994

Acute protein loading in the assessment of renal reserve.

Functional renal reserve is a measure of the capacity of the kidney to increase the glomerular filtration in response to the stimulus of a protein meal or amino acid infusion. The aim of this study was to evaluate the usefulness of protein meal test to measure functional renal reserve in normal subjects and various groups of renal patients. One hundred and twenty five subjects from the Nephrology Clinic, Kuala Lumpur General Hospital were subjected to a protein loading test to measure their renal reserve. Each subject had to eat a 100 gram cooked chicken meat and timed 2 hours urine collections before and after the test meal were done to measure the creatinine clearances. The 62 healthy subjects showed a mean renal reserve (creatinine clearance after protein loading-baseline creatinine clearance) of 31.0 ml/min. The 31 subjects with various kidney diseases showed a mean renal reserve of 13.5 ml/min. The 19 renal transplant recipients showed renal reserve of 13.2 ml/min. The 12 nephrectomised donors showed renal reserve of 5.4ml/min. Renal reserve may be used to assess suitability of living related transplant donor for nephrectomy.

Adult↗
PubMed1993

Laron dwarfism in the Arabian Gulf: a report of a sibship.

Laron dwarfism is a rare inherited form of short stature. Most cases reported have been in people of Mediterranean origin, particularly Oriental Jews. We describe the first sibship in an Arab Muslim family from Kuwait in the Arabian Gulf. This type of growth hormone insensitivity is caused by defects in the growth hormone receptor gene. The recently available recombinant human insulin-like growth factor I has shown promise as a promoter of growth in children with Laron syndrome.

Age Determination by Skeleton↗