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Biomedical subjects

M Ashraf

Publications and source records attributed to M Ashraf.

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

[Orthopedic rehabilitation of children after combined treatment of malignant bone tumors].

The report is based on the data concerning 27 children who were given radiotherapy and chemotherapy for osteogenic sarcomas (14), Ewing's sarcomas and reticulosarcoma (10) and malignant giant cell tumours (2). The reconstructive conservative treatment (7 patients) were referred for prevention of contractures and fractures. The orthopaedic surgical correction of the appearing false joints, deformations and defects of the bones (20 patients) was performed 4 to 5 years after the termination of the primary treatment. During the reconstructive period 3 patients with malignant giant cell tumours and osteogenic sarcoma died because of metastases. The authors have made a conclusion about the advantage of extrafocal compression and distraction osteosynthesis over other methods of fixation and correction of deformations in children after the treatment of malignant bone tumours.

Adolescent↗
PubMed1989

Screening of steroids in horse urine and plasma by using electron impact and chemical ionization gas chromatography-mass spectrometry.

Gas chromatography with chemical ionization mass spectrometry and selected-ion monitoring provided a sensitive method for the screening and confirmation of steroids in horse urine and plasma. Chemical ionization mass spectrometry was more sensitive than the electron impact ionization mass spectrometry for most of the steroids except for testosterone, prednisone-metabolite-2 and prednisolone-metabolite-2. The chromatographic conditions used in this study provided clean separation of different natural and synthetic steroids. Approximately 75-85% of the steroids added to plasma and approximately 65-70% of the steroids added to urine were recovered by the extraction procedure used in this study.

Animals↗
PubMed1989

Screening and confirmation of drugs in horse urine by using a simple column extraction procedure.

A simple and reproducible column (Clean Screen-DAU, copolymeric bonded-phase silica column) extraction procedure has been described for the screening and confirmation of drugs in horse urine. The recovery of drugs by the column extraction was better than or comparable to the recovery by the liquid-liquid extraction, which is commonly used in the equine analytical laboratories. The column extraction provided broad coverage of drugs, separated extracts into three fractions (acidic/neutral, steroids, basic), produced a cleaner extract, and eliminated the need for special liquid-liquid extraction procedures for different drugs. The column extract was cleaner and did not contain impurities, whereas, the liquid-liquid extract was relatively impure and the extract required further thin-layer chromatographic cleanup. The column extraction procedure was used to confirm the presence of several potent drugs, such as fentanyl, etorphine, and mazindol.

Animals↗
PubMed1989

Simultaneous analysis of furosemide and bumetanide in horse plasma using high performance liquid chromatography.

A high performance liquid chromatographic method is described for the simultaneous determination of furosemide and bumetanide in horse plasma. The C8 (3 microns) reversed phase column (4.8 x 150 mm) provided clear separation of furosemide and bumetanide with other components present in the horse plasma. The detection limit for both the drugs was 10 ng/mL. Both drugs were stable in plasma (at natural or acidic pH) for up to 24 h. The method is sufficiently sensitive to detect furosemide levels in plasma obtained from horses receiving a therapeutic dose of furosemide.

Animals↗
PubMed1989

Treatment of coronary artery stenosis and coronary arteriovenous fistula by interventional cardiology techniques.

Complications associated with coronary arteriovenous fistulae (CAVF) include congestive heart failure, bacterial endocarditis, fistula rupture, and angina secondary to the "coronary steal" phenomenon. Traditional treatment of large CAVF is surgical ligation. In this report, we describe a modified microcoil embolization and guidewire technique for percutaneous closure of CAVF.

Angioplasty, Balloon, Coronary↗
PubMed1989

Effects of melittin on endothelium-dependent relaxation and cyclic GMP levels in rat aorta.

The present study investigates the mechanism of endothelium-dependent relaxation of vascular smooth muscle. Melittin, a polypeptide found in honeybee venom and a known activator of phospholipase A2, induced transient, endothelium-dependent relaxations of rat thoracic aortae contracted with norepinephrine. Higher concentrations of melittin induced relaxations followed by contractions. Prior incubation of melittin with trypsin abolished the changes in relaxation and contraction due to melittin. Melittin (10 micrograms/ml)-induced relaxations were associated with transiently elevated levels of cyclic GMP with a peak increase of 30-fold, which occurred 30 seconds after melittin exposure. Melittin (10 micrograms/ml) elevated cyclic AMP levels less than twofold and this effect was variable. A lower concentration of melittin (1 microgram/ml) elevated cyclic GMP levels approximately twofold, while exposure to 1 microgram/ml melittin in the presence of the cyclic GMP phosphodiesterase inhibitor, M&B 22948 (1 mM), increased cyclic GMP levels fivefold. Removal of the endothelium prevented the increased levels of cyclic GMP and cyclic AMP due to melittin. Exposure to the guanylate cyclase inhibitor, methylene blue, prevented the increased levels of cyclic GMP. Methylene blue, nordihydroguaiaretic acid, and the phospholipase A2 inhibitor, parabromophenacyl bromide, inhibited melittin-induced relaxations, while the cyclo-oxygenase inhibitor, indomethacin, was without effect. Arachidonic acid increased cyclic AMP levels but had no effect on cyclic GMP levels in the presence or absence of indomethacin. Relaxations to melittin, and to the endothelium-dependent vasodilators acetylcholine, trypsin, histamine, and the Ca2+ ionophore A23187, and/or the associated increased cyclic GMP levels, were reduced following exposure to melittin. Prior exposure to polyarginine (10 micrograms/ml), which induced endothelium-dependent relaxations that were prevented by methylene blue, also inhibited relaxations to the endothelium-dependent vasodilators. In contrast, relaxations to sodium nitroprusside were potentiated in tissues previously exposed to melittin. Removal of the endothelium by rubbing the intimal surface also potentiated relaxations to sodium nitroprusside. Scanning electron micrographs of the intimal surface demonstrated that melittin and polyarginine greatly damaged the endothelial cells. The present results suggest that polycation containing peptides induce endothelium-dependent relaxation through elevation of cyclic GMP levels within the smooth muscle.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Neurotoxicity in rats sub-chronically exposed to low levels of lead.

Pregnant rats (for prenatal exposure), 5-day-old rats, and 5-week-old rats were exposed orally to lead acetate daily for 10 weeks. Lead values in the brain of animals from all three lead-exposed groups were similar. Brain norepinephrine (NE) and GABA levels and glutamate decarboxylase (GAD) activity were decreased, and brain glutamate (glu), glutamine + asparagine (gln/asn), and tyrosine (tyr) levels, and monoamine oxidase (MAO) activities were increased in rats prenatally or 5 days postnatally exposed to lead. Brain ammonia, alanine (ala), aspartic acid (asp), and dopamine (DA) values were not affected by the prenatal or 5-day-postnatal lead treatment. Brain uptake index (BUI) values for glu were significantly elevated in rats exposed to lead prenatally or 5 days after birth. Exposure of 5-week-old rats to lead did not affect the brain catecholamine and amino acid levels. These results suggest that the brains of young rats were more sensitive to lead exposure than the brains of adult rats, although the accumulation of lead in brain was not affected by age.

Age Factors↗
PubMed1989

Morphological and biochemical evidence of protective effect by ONO-3144, a free radical scavenger, on the reoxygenation injury in the anoxic myocardium.

We have investigated the effect of ONO-3144 (2:aminomethyl-4-tert-butyl-propionylphenol), which accelerates the conversion of prostaglandin G2 to H2 and acts as a scavenger for free radicals, on the reoxygenation injury in the anoxic heart. Rat hearts were perfused retrogradely with Krebs-Henseleit (KH) medium for 30 minutes in Group I. In Group II, the hearts which were perfused with anoxic KH medium for 40 minutes were reoxygenated for 30 minutes. Group III was similar to Group II except that 4 mg ONO-3144/liter was added in anoxic medium. Group IV was similar to group III except ONO-3144 was present both during anoxia and reoxygenation. Coronary effluent was collected for the measurement of creatine phosphokinase (CPK). Tissue from each group was processed for electron microscopy, adenosine triphosphate (ATP), and tissue calcium. A six-fold increase in CPK leakage that was observed after reoxygenation of anoxic heart was prevented by ONO-3144. Tissue ATP was reduced from 21.65 +/- 1.1 mumol/gm dry weight (Group I) to 4.83 +/- 0.8 mumol/gm dry weight (Group II). A significant amount of ATP (9.05 +/- 1.22 mumol/gm dry weight) was preserved in the treated Group IV. The number of normal cells obtained by morphometrical analysis increased significantly from 24.2 +/- 8.4% (Group II) to 70.00 +/- 4.0% (Group IV), and severely injured cells were also reduced to 19.8 +/- 2.8% in the same group as compared to 54.8% in the untreated Group II. At the electron microscopic level, the cellular membranes, mitochondria, vascular endothelium, and glycogen deposits were well preserved in Group IV. The treatment during anoxia only did not minimize the reoxygenation damage (Group III). Thus, treatment with ONO-3144 provides a great protection against reoxygenation injury to the myocyte and vascular endothelium of the anoxic myocardium, perhaps by scavenging active oxygen species.

Adenosine Triphosphate↗
PubMed1988

Analysis of amino acids in brain and plasma samples by sensitive gas chromatography-mass spectrometry.

Gas chromatography-mass spectrometry-selected-ion monitoring provided a simple and sensitive method for analyzing amino acids in plasma and brain samples. Although the sensitivities of chemical ionization and electron-impact ionization were similar chemical ionization produced higher-mass ions, which might increase the selectivity of the assay. Both chemical and electron-impact ionization distinguished the natural amino acids from the 15N-labelled amino acids. The recovery of amino acids from plasma and brain samples was ca. 75%. The amino acid levels determined by gas chromatography-mass spectrometry were comparable with the amino acid levels determined by high-performance liquid chromatography or amino acid analyzer.

Amino Acids↗
PubMed1988

Prospective nerve conduction studies in cisplatin therapy.

We studied nerve conduction prospectively in 38 women receiving cisplatin for gynecological malignancies. Decreased sensory nerve action potential amplitudes and prolonged sensory latencies were the only significant changes identified. This prospective electrophysiological study validates the clinical observation of frequent sensory symptoms and occasional sensory neuropathies associated with cisplatin therapy.

Action Potentials↗
PubMed1988

Myocardial dysfunction and ultrastructural alterations mediated by oxygen metabolites.

The direct effect of oxygen metabolites was studied on isolated perfused rat hearts. Superoxide anion (O2-.) and hydrogen peroxide (H2O2) were generated by adding purine (2.3 mM) and purified xanthine oxidase (0.06 U/ml) to Krebs-Henseleit buffer (pH 7.4). Xanthine oxidase was added to the purine-containing perfusate either near the aorta (group A, which gave H2O2 less than 10 microM) or at a distant point from the aorta (group B, which gave 250 to 300 microM H2O2). The generation rate of O2-. was 31.7 +/- 1.0 nmol/ml/min in the experimental conditions. Contractile function, tissue adenosine triphosphate (ATP), and ultrastructure were not affected in group A. In contrast, hearts in group B showed marked decrease in contractility (+dP/dt) to 24.4 +/- 4.3% of control values. ATP levels were also markedly reduced from control values of 23.4 +/- 0.7 to 7.4 +/- 0.7 mumol/g dry tissue. Ultrastructure in group B hearts revealed "wavy" and disintegrated sarcolemma, depletion of glycogen deposits, and swelling and disruption of mitochondria. Release of the thiobarbituric acid reactive products including malondialdehyde was significant in the effluent (1.68 +/- 0.17 nmol/min/g wet tissue). These changes were almost completely prevented by catalase, but not by superoxide dismutase and deferoxamine. Moreover, exogenous H2O2 perfusion (300 microM) showed results similar to group B hearts. These observations suggest that H2O2 plays a major role in the injury. O2- does not appear to damage hearts directly, although it is important as a precursor of H2O2 and other radical species including hydroxyl radical.

Adenosine Triphosphate↗
PubMed1988

Characterization of isolated porcine intestinal mucosal mast cells following infection with Ascaris suum.

Porcine intestinal mucosal mast cells (IMMC) were isolated from intestinal tissues of swine by enzymatic digestion and density gradient separation. Helminth-free swine and swine exposed to the nematode parasite, Ascaris suum, were used as a source of intestinal tissue. Up to 40% of the isolated intestinal cells stained metachromatically with toluidine blue pH 3.0, indicating the presence of IMMC. The histamine content of this cell population ranged from 2.9-8.9 pg per toluidine blue-positive IMMC, regardless of the animal source. Enrichment procedures that increased the proportion of toluidine blue-positive IMMC from the isolated intestinal cell population correlated with an increase in the amount of histamine detected in the cell population, indicating that toluidine blue-positive IMMC were the major source of histamine in this heterogeneous cell population. However, only cells isolated from the intestines of parasite-exposed swine released histamine in vitro after mixing with antigens derived from A. suum. Cells from the intestines of both helminth-free and parasite-exposed swine did not release histamine after mixing with a non-parasite hapten-protein molecule DNP-human serum albumin, but did release greater than 90% of their total histamine after lysis with Triton X-100 or with the Ca2+ ionophore (A23187). The stimulus for acquired responsiveness of IMMC to A. suum antigens in vitro was parasitic infection in vivo because helminth-free swine maintained in confinement on concrete yielded IMMC that specifically released histamine in the presence of parasite antigens only after 3 weeks of daily experimental inoculations with A. suum eggs. IMMC isolated from the entire length of the small intestines of infected pigs were responsive to antigens in vitro, but the relative number of IMMC isolated and their level of histamine release decreased from the anterior to the posterior end. IMMC isolated from infected swine were also stimulated to release histamine in vitro by viable second stage larvae of A. suum and by treatment with anti-swine immunoglobulin. Responsiveness to both parasite antigens and anti-immunoglobulin were totally eliminated, however, by a brief treatment of the cells with acidic buffer, suggesting that an acid-dissociable cell-bound antibody molecule was responsible for specific antigen-induced histamine release by IMMC.

Animals↗
PubMed1988

Promoter strength comparisons of maize shrunken 1 and alcohol dehydrogenase 1 and 2 promoters in mono- and dicotyledonous species.

Promoter strengths of two maize alcohol dehydrogenase genes, Adh1 and Adh2, and the maize shrunken-1 gene, Sh1, were evaluated by transient expression in cultured protoplasts of Panicum maximum, Triticum monococcum, and Daucus carota. Promoter elements were ligated in correct and opposite orientations as transcriptional gene fusions to the chloramphenicol acetyl transferase gene containing the nopaline synthase 3' polyadenylation signal. The relative levels of gene expression were compared to the cauliflower mosaic virus 35S promoter. The full length Adh1 promoter (-1100 to +15) functioned in all species, but at a reduced level in D. carota. An Adh1 promoter deletion from -304 to -1100 did not express at detectable levels in any species nor did the Sh1 promoter construction. The Adh2 promoter (-860 to +90) only expressed in D. carota. The full length Adh1 promoter gave the highest level of CAT expression in the monocot cells but at levels which were approximately 30% compared to the CaMV 35S promoter. This was reduced further in D. carota to approximately 4%. These data suggest that at least some of the regulatory factors responsible for promoter function are somewhat species specific and that these differences should be considered in gene expression studies.

Journal Article↗
PubMed1988

Regulation of cholesterol metabolism in fetal rabbit aorta: role of amniotic fluid factors.

This study shows that amniotic fluid enhances cholesterol esterification in arterial wall, as measured by in vitro assay of acyl-CoA:cholesterol acyltransferase (ACAT) activity and by incorporation of oleic acid to cholesteryl esters in cultured fetal aortas and smooth muscle cells. This property is mostly evident in the fraction of molecular weight greater than 100,000, and it is abolished by delipidation, indicating that stimulating factor is probably lipoprotein in nature. Despite an increased cholesterol esterification by the presence of amniotic fluid in medium of cultured fetal aortas, the content of cholesterol and cholesteryl esters was much lower. The cellular structures are better preserved in explants cultured with amniotic fluid than in control animals. This study indicates that amniotic fluid contains factors that may have a pronounced effect on arterial wall during development.

Amniotic Fluid↗
PubMed1988

Localization of sodium-potassium adenosine triphosphatase in sheep myocardium by immunoelectron microscopy.

Immunohistochemical localization of sodium and potassium dependent adenosine triphosphatase (Na,K-ATPase) employing polyclonal antibodies was carried out on sheep myocardium. The tissue was fixed with glutaraldehyde or a paraformaldehyde/lysine/periodate combination fixative and embedded in different embedding media. Ultrathin sections were labeled with rabbit anti-sheep Na,K-ATPase antiserum followed by sheep anti-rabbit immunoglobulin complexed with colloidal gold. Glycol methacrylate embedded tissue provided good structural preservation and showed specific immunohistochemical labeling. Analysis of the gold particle distribution showed a significantly higher number of Na,K-ATPase immunoreactive sites associated with cell membrane and T-tubules.

Animals↗