Biomedical subjects
M Ahmad
Publications and source records attributed to M Ahmad.
Palliation of malignant tracheobronchial obstruction by Nd-YAG laser: an update of experience at the Cleveland Clinic Foundation.
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Interaction of alpha-thalassemia with other hemoglobinopathies in the eastern province of Saudi Arabia.
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Yeast arginine permease: nucleotide sequence of the CAN1 gene.
The yeast CAN1 gene, thought to encode arginine permease, has found use in genetics as a selectable locus. We have sequenced the cloned CAN1 gene, which contains an open reading frame of 1770 nucleotides, encoding a polypeptide of calculated molecular weight 65,766. Disruption of this open reading frame largely abolishes CAN1 gene expression, while subcloned fragments of the open reading frame hybridize strand-specifically to a 2.3 kb yeast RNA message. The encoded protein has no leader signal sequence, and is highly hydrophobic, with a possible twelve membrane-spanning domains, several of which have the high hydrophobic moments seen in channel-forming or permease proteins. This protein structure is consistent with the CAN1 product being the plasma membrane arginine permease.
Severe congenital factor X deficiency with intracranial haemorrhage.
A Saudi Arabian infant with severe factor X deficiency who had had two intracranial haemorrhages is described. Attempts to raise his factor X level and improve his prothrombin time (PT) and partial thromboplastin time (PTT) by using vitamin K, oestradiol and danazol have failed. New therapeutic trials are necessary for patients with severe forms of this rare disorder.
Endogenous production of prothymocyte differentiating activity by phytohemagglutinin-stimulated T-cell-depleted human marrow.
The PHA responsiveness of marrow T-cell precursors remains a matter of controversy. We have investigated the capacity of human marrow to proliferate under phytohemagglutinin (PHA) stimulation following extensive removal of mature T cells by complement-dependent cytotoxicity with MBG6 and RFT8 monoclonal antibodies. PHA-induced thymidine uptake by marrow cells occurred with a peak on Days 6-8 of incubation instead of Day 3 for PBL. This peak was observed 48 hr earlier in the presence of PHA-stimulated T-depleted marrow cell supernatants. These supernatants can also promote the growth of mature T-cell colonies from MBG6-, RFT8-, T11-, T3- marrow. However, full colony development requires exogenous interleukin 2 (IL-2). IL-2 could be detected in marrow supernatants but only at very low levels and beyond Days 3 and 4. In contrast Days 1-6 marrow supernatants were equally effective in promoting MBG6-RFT8- marrow cell responsiveness to PHA. We conclude that marrow T-cell precursors are not PHA responsive and that PHA induces the production by marrow non-T cells of a prothymocyte-differentiating activity (PTDA); PTDA can differentiate marrow T-cell progenitors into PHA-responsive T cells; following activation by PHA, these cells undergo limited proliferation induced by IL-2 endogenously released from de novo differentiated T cells. It is suggested that this mechanism may account for extrathymic differentiation of the T-cell lineage in heavily irradiated marrow transplantation recipients.
Purification of bacterial luciferase by high-performance liquid chromatography.
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Pulmonary lymphoid neoplasms. Role of immunohistology in the study of cellular immunotypes and in differential diagnosis.
Seven cases of lymphoid neoplasms presenting in the lung were evaluated by immunohistology for T and B cell antigens and immunoglobulin light chains in frozen tissue sections. Although follow-up was short or inconclusive in some patients with lymphoma and pseudolymphoma, it was concluded that evaluation of T and B cell antigens and immunoglobulin light chains in frozen tissue is helpful in classifying lymphocytic neoplasms, especially in cases without definite cytologic evidence of malignancy. As demonstrated in two additional cases, lymphocyte/leukocyte markers in paraffin-embedded tissue are important in the differential diagnosis of lesions with cytologic features of malignancy.
The safety of outpatient transbronchial biopsy.
Fiberoptic bronchoscopy (FOB) is an accepted outpatient procedure, but transbronchial biopsy (TBB) is generally reserved for hospitalized patients. Over a three-year period, we performed fluoroscopically guided TBB in 148 of 688 outpatients undergoing FOB. Following the procedure, fluoroscopy was used to screen for possible pneumothorax in those patients who had had TBB. All patients were observed for one hour and then discharged if stable. Three patients (2.02 percent) were admitted and observed for acute hemoptysis following TBB. Bleeding ceased spontaneously in each. The remaining 145 patients were discharged after one hour of observation. One patient (0.68 percent) required Heimlich tube treatment for a delayed pneumothorax. Our experience indicates a low incidence of delayed complications in patients who are asymptomatic for one hour following TBB. We conclude that patients do not require hospitalization solely for TBB.
Aflatoxin in uncooked market commodities: spices.
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Urinary excretion of aflatoxin and liver cancer in Karachi.
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Studies on human prothymocytes by means of an agar T-cell colony assay.
The identity of bone marrow (BM) T colony-forming cells has led to controversy because of BM contamination with mature T cells having clonogenic potential. To circumvent this problem, extensive purging of BM cells was achieved, using E-rosetting and complement-dependent cytotoxicity, with a cocktail of monoclonal antibodies (Mabs): CD6 + CD8 + CD4 + CD2 and two successive rabbit Complement (C) treatments. This resulted in a 2-log elimination of mature T cells, as assessed by marker studies. T-cell-depleted marrow (TDBM) was plated in agar in the presence of PHA- and B+ null cell-derived prothymocyte differentiating activity (PTDA). Two peaks of colony formation were observed on days 7 and 10 of incubation. Both seven- and ten-day colonies contained mainly T4+ and only a few T8+ cells, which also expressed T3, T11, HLA-DR, and Tac antigens. These colony-forming cells were enriched (three- to fourfold) by discontinuous Percoll gradient centrifugation. These results point to the existence of marrow T-cell progenitors, which differ in their kinetics of colony generation and surface markers.
The effects of X-rays on the survival of Xenopus tadpoles.
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Serum lipoproteins in central retinal vein occlusion and other vascular lesion.
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Post mortem studies on infertile buffalo bulls: anatomical and microbiological findings.
Twenty-two buffalo bulls suffering from three different types of infertility were slaughtered and used for this study. Except for the reproductive system, no signs of localised or generalised disease were observed. Microbiological investigations were negative for brucellosis, vibriosis, mycoplasma and other non-specific microorganisms. Nine bulls with type 1 infertility had low bodyweights and underdevelopment of testes, accessory sex glands and endocrine glands. This picture suggests a total dysfunction of the pituitary-growth-gonadal axis. One bull of this type also showed bilateral epididymitis. Four out of 11 bulls with type 2 infertility had low bodyweights and most suffered from underdevelopment of testes, accessory sex glands and endocrine glands. Six bulls of this type had lesions of either epididymitis or orchitis or both. Two of these animals showed adhesions of periorchitis. One also showed seminal vesiculitis. In two bulls with type 3 infertility, bodyweights, reproductive organs and endocrine glands were normal. In later life, they yielded poor quality semen. Semen samples collected a few months before slaughter from nine bulls with type 2 and type 3 infertility were of poor quality and had higher percentages of abnormal spermatozoa in most cases.
Activation of fibrinolysis by apolipoproteins of high density lipoproteins in man.
The effects on fibrinolysis of purified normal human plasma lipoproteins and their apolipoproteins (apo) were assessed in an in vitro system containing urokinase, plasminogen, and fibrin. High and very low density lipoproteins (HDL and VLDL, respectively) but not low density lipoproteins (LDL) significantly increased lysis of radiolabeled fibrin or lysis area of plated fibrin compared to controls. Apo HDL, apo HDL2, apo HDL3, apo VLDL (buffer soluble apo), apo AI and AII activated fibrinolysis by 1.3-1.4 fold of control values, whereas apo B (as a narrow density cut of LDL) and non-lipoprotein control proteins (albumin and myoglobin) did not. Addition of HDL in the absence of urokinase failed to activate fibrin lysis. These data demonstrate that the major proteins of HDL - apo AI and apo AII - and possibly certain minor constituent(s) common to HDL and VLDL participate in the fibrinolytic process.
The pulmonary manifestations of systemic lupus erythematosus.
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Uterine involution and postpartum ovarian activity in Nili-Ravi buffaloes.
Uterine involution and postpartum ovarian activity were studied in 53 Nili-Ravi buffaloes. Mean intervals to uterine involution (26 days), regression of the corpus albicans of pregnancy (22 days), resumption of follicular activity (21 days) and first postpartum estrus (56 days) were not affected by the month of calving or age. Mean interval to formation of first corpus luteum (CL) after calving as indicated by progesterone in plasma (>/= 1.5 ng/ml) was 23.8 +/- 1.7 days, but only 52% of these CL were palpable. The number of CL formed before first postpartum estrus ranged from zero to five per buffalo; mean values based upon progesterone and palpation were 1.6 +/- 1.3 and 0.8 +/- 0.2, respectively. Based upon either progesterone or palpation, length of first postpartum luteal phase (7.9 or 6.6 days) was shorter than the luteal phase immediately preceeding the first estrus (12.1 or 8.9 days). Intervals from regular cyclic ovarian activity was not established until first estrus and intervals from the end of one luteal phase to the onset of the next were as long as three weeks. High concentrations of progesterone (>/= 1.5 ng/ml) on the day of behavioral estrus were seen in 23% of the buffaloes studied.