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Biomedical subjects

M Anwar

Publications and source records attributed to M Anwar.

At least 91 records · Page 5Linked to original sources
PubMed1991

Effects of MK-801 on cerebral regional oxygen consumption in focal cerebral ischemia in rats.

This investigation tested in rats whether MK-801, an N-methyl-D-aspartate receptor antagonist, would improve the balance of oxygen supply and consumption in the focal ischemic area of the brain induced by occlusion of the middle cerebral artery. Fifteen minutes after middle cerebral artery occlusion, 5 mg/kg MK-801 was administered intravenously to the MK-801 group (n = 12), and normal saline was given to the control group (n = 12). One hour after the occlusion in each group, regional cerebral blood flow was determined in six rats using [14C]iodoantipyrine, and regional arterial and venous oxygen saturations were determined using a microspectrophotometric technique in the other six rats. In both groups of animals, the cerebral blood flow of the ischemic cortex was significantly lower than that of the contralateral cortex (36 +/- 16 [SD] and 67 +/- 14 ml/min/100 g for the control group; 33 +/- 10 and 58 +/- 11 ml/min/100 g for the MK-801 group, respectively). Oxygen extraction was significantly higher in the ischemic cortex (8.8 +/- 2.1 ml O2/100 ml blood) than in the contralateral cortex (5.6 +/- 0.3) for the control group. However, for the MK-801 group, there was no significant difference between the ischemic cortex (6.1 +/- 1.0) and the contralateral cortex (5.7 +/- 1.1). Oxygen extraction in the ischemic cortex of the MK-801 group was significantly lower than that of the control group. Calculated ischemic regional oxygen consumption was similar to the nonischemic values in the control group, whereas the ischemic value was reduced to 61% of the value of the contralateral cortex in the MK-801 group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Alpha-thalassaemia: prevalence and pattern in northern Pakistan.

The level of Hb Bart's is directly related to the inheritance of alpha-thalassaemia gene. Hb electrophoresis for Hb Bart's in the cord blood is a very simple method of finding out the prevalence of alpha-thalassaemia gene in a given population. A study was, therefore, carried out to find out the prevalence of alpha-thalassaemia gene in the population of northern Pakistan by estimating the concentration of Hb Bart's in 500 cord blood samples during the period 1986-87 at AFIP Rawalpindi. Hb Bart's was detected in 12 neonates, thus indicating a rate of 2.4% of general population as carrier of alpha-thalassaemia gene. Two distinct groups were recognized. The first group was composed of 9 (75%) neonates, in which Hb Bart's levels varied between 2.0% to 3.5%, while the second group of 3 neonates (25%) showed a level of 5.8% to 6.3%. The former group was considered to be carrying alpha-thalassaemia-2 gene and the latter group as carrier of alpha-thalassaemia-1 gene. Neither Hb H disease nor Hb Bart's hydrops foetalis syndrome was detected in this series.

Female↗
PubMed1990

Strain differences between albino and pigmented rats in monoamine-synthesizing enzyme activities of brain, retina and adrenal gland.

The present study compared the activities of some of the monoamine synthesizing enzymes in several brain regions, the retina as well as adrenal gland of albino Sprague-Dawley (SD) and Long-Evans hooded (LE) rats. Brainstem, hypothalamic and retinal tyrosine hydroxylase (TH) activity were significantly higher in LE than in SD. In addition to higher enzyme activity, a larger number of TH-immunoreactive perikarya as well as a higher concentration of TH-immunoreactive processes were observed in the retina of LE rats. There was no strain difference in TH activity of caudate nucleus (CN) and substantia nigra (SN). In contrast to brain regions and retina, adrenal TH activity was markedly higher in SD than in LE animals. Aromatic L-amino acid decarboxylase (AADC) activity of both the brainstem and adrenal gland in the LE strain was lower than in SD animals. No differences in the AADC activity of hypothalamus, SN and CN were found between LE and SD strains. Phenylethanolamine N-methyltransferase (PNMT) activity of the hypothalamus, retina and adrenal gland of LE strains was significantly lower than in SD rats. In spite of the difference in the enzyme activity, there were no marked morphological changes observed in PNMT-immunostaining patterns between the retina of LE and SD rats. Tryptophan hydroxylase activity of both the brainstem and hypothalamus did not exhibit strain differences.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Glands↗
PubMed1990

Anatomical substrates of cholinergic-autonomic regulation in the rat.

UNLABELLED: Acetylcholine (ACh) plays a major role in central autonomic regulation, including the control of arterial blood pressure (AP). Previously unknown neuroanatomic substrates of cholinergic-autonomic control were mapped in this study. Cholinergic perikarya and bouton-like varicosities were localized by an immunocytochemical method employing a monoclonal antiserum against choline acetyltransferase (ChAT), the enzyme synthesizing ACh. In the forebrain, bouton-like varicosities and/or perikarya were detected in the septum, bed nucleus of the stria terminalis, amygdala (in particular, autonomic projection areas AP1 and AP2 bordering the central subnucleus), hypothalamus (rostrolateral/innominata transitional area, perifornical, dorsal, incertal, caudolateral, posterior [PHN], subparafascicular, supramammillary and mammillary nuclei). Few or no punctate varicosities were labeled in the paraventricular (PVN) or supraoptic (SON) hypothalamic nuclei. In the mid- and hindbrain, immunoreactive cells and processes were present in the nucleus of Edinger-Westphal, periaqueductal gray, parabrachial complex (PBC), a periceruleal zone avoiding the locus ceruleus (LC), pontine micturition field, pontomedullary raphe, paramedian reticular formation and periventricular gray, A5 area, lateral tegmental field, nucleus tractus solitarii (NTS), nucleus commissuralis, nucleus reticularis rostroventrolateralis (RVL), and the ventral medullary surface (VMS). In the PBC, immunoreactive varicosities identified areas previously unexplored for cholinergic autonomic responsivity (superior, internal, dorsal, and central divisions of the lateral subnucleus, nucleus of Koelliker-Fuse and the medial subnucleus). In the NTS, previously undescribed ChAT-immunolabeled cells and processes were concentrated at intermediate and subpostremal levels and distributed viscerotopically in areas receiving primary cardiopulmonary afferents. In the nucleus RVL, cholinergic perikarya were in proximity to the VMS and medial to adrenergic cell bodies of the C1 area. Punctate varicosities of unknown origin and dendrites extending ventrally from the nucleus ambiguus overlapped the C1 area and immediate surround of RVL. IN CONCLUSION: 1) Cholinergic perikarya and putative terminal fields, overlap structures that are rich in cholinoreceptors and express autonomic, neuroendocrine, or behavioral responsivity to central cholinergic stimulation (PHN, NTS, RVL). The role of ACh in most immunolabeled areas, however, has yet to be determined. Overall, these data support the concept that cholinergic agents act at multiple sites in the CNS and with topographic specificity.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Changes in the circulating levels of hemoglobin, hematocrit, serum iron and total iron binding capacity after four methods of surgical tubal sterilization.

One-hundred women requesting voluntary surgical sterilization were included and enrolled into four groups (each n = 25). Four sterilization modalities were used namely: Falope ring, electrocoagulation, clip and Pomeroy ligation. The circulating levels of hemoglobin, hematocrit, serum iron and total iron binding capacity were studied before sterilization and at 3, 6 and 12 months thereafter. No significant changes were observed at 3 and 6 months post-sterilization. At 12 months a significant increase in the hemoglobin and serum iron was observed with a significant decrease in total iron binding capacity. Falope ring, clip and Pomeroy ligation were of a higher rank in this context versus electrocoagulation.

Adult↗
PubMed1990

Model surgery for orthognathic planning.

A modification of a popular North American model surgery technique is described, with a brief comparison with the key-spacer planning system of Lockwood. This technique enables bimaxillary movements to be planned with greater accuracy than with the Lockwood system.

Dental Articulators↗
PubMed1990

Effect of chemodenervation on the cerebral vascular and microvascular response to hypoxia.

This study evaluated the effect of bilateral carotid chemodenervation on the cerebrovascular response to hypoxia in conscious rats. Cerebral blood flow was measured using 4-iodo[N-methyl-14C]antipyrine, and the total and perfused microvasculature was studied by injection of fluorescein isothiocyanate dextran and alkaline phosphatase staining. To maintain constant PCO2, hypoxia was achieved in chemoreceptor-intact rats by the use of 4% CO2-8% O2-88% N2 and in chemodenervated rats by the administration of 8% O2-92% N2. Blood gas and hemodynamic parameters were similar in the two groups of rats. Chemodenervation had no significant effect on either resting blood flow or the perfused microvasculature during normoxia. A significant increase in cerebral blood flow (from 71 +/- 3 to 138 +/- 9 ml/min/100 g in control and from 91 +/- 5 to 127 +/- 7 ml/min/100 g in chemodenervated rats) and in the percent of cerebral arterioles and capillaries perfused occurred in both hypoxic control and chemodenervated rats. In chemoreceptor-intact rats, the greatest increase in blood flow and in perfused microvasculature occurred in caudal structures (medulla and pons) in comparison with rostral structures (cortex, thalamus, and hypothalamus). In chemodenervated rats, a similar increase in blood flow and perfused microvasculature occurred in all brain regions, with no regional differences. Thus, chemodenervation did not affect the overall cerebral blood flow or the microvascular response to hypoxia; however, rostral-to-caudal regional differences in the hypoxic response were lost after chemodenervation.

Animals↗
PubMed1990

HLA frequencies in Pakistani population.

HLA frequencies on 1231 subjects from within the country, using methods employed by National Institute of Health, USA is reported. Pakistani population appears to be a mixture of an indigenous population with others particularly Orientals and Negroids. Relationship with Caucasians is not convincing.

Gene Frequency↗
PubMed1989

Cervical prostaglandin injection: a novel method of administration for ripening the cervix and induction of labor.

Twenty pregnant women with greater than or equal to 36 weeks gestation and Bishop score of less than or equal to 4 were subjected to either intracervical injection of PGE2 (0.25 mg) every 4 h to ripen the cervix and induce labor (study group n = 10) or injection of only the diluent (control group n = 10). PGE2 cases showed significant increase in Bishop score and were successfully induced. The mean induction-establishment and induction-delivery intervals were 4.3 +/- 0.1 min and 6.07 +/- 1.7 h, respectively. The control group showed no response. PGE2 cervical injection is a safe and effective method for cervical ripening and labor induction.

Adult↗
PubMed1989

Serum from pregnant women carrying a fetus with neural tube defect is teratogenic for rat embryos in culture.

Sera from 13 pregnant women carrying a fetus with a neural tube defect, and from 13 control women with normal pregnancies at the same stage of gestation were used in the culture of postimplantation rat embryos. Serum from women with normal pregnancies had no adverse effect on rat embryo growth and development. Serum from 10 of the women with affected fetuses had a deleterious effect on the rat embryos as abnormalities of neural tube closure were observed in 28% of the conceptuses compared to only 1.3% of the embryos cultured in control serum.

Adolescent↗
PubMed1989

Adenosine and cerebral capillary perfusion and blood flow during middle cerebral artery occlusion.

The effects of adenosine on regional cerebral blood flow and indexes of the total and perfused microvascular bed were studied after 1 h of middle cerebral artery occlusion in the anesthetized rat. Iodo[14C]antipyrine was used to determine cerebral blood flow. Fluorescein isothiocyanate-dextran was used to study the perfused microvasculature, and an alkaline phosphatase stain was used to identify the total bed. Mean arterial blood pressure was significantly reduced by adenosine. Cerebral blood flow increased significantly by 75%, except in the flow-restricted cortex where flow averaged 28 +/- 15 (SD) ml.min-1.100 g-1 in control and 34 +/- 33 ml.min-1.100 g-1 in adenosine-treated animals. No significant regional structural differences were observed within the microvascular beds of the two groups. The percentage of the microvascular volume perfused increased significantly in all brain regions in the adenosine-treated rats, including the flow-restricted cortex. The percent perfused arteriolar volume in the flow-restricted cortex was 30 +/- 12% in control and 95 +/- 3% in adenosine-treated animals. Similar values for the capillary bed were 22 +/- 10% in control and 54 +/- 3% in adenosine-treated rats. These results indicate a maintenance of flow with a reduction in diffusion distances in the flow-restricted cortex after treatment with adenosine.

Adenosine↗
PubMed1988

Biochemical evidence for presence of dopamine beta-hydroxylase in rat retina.

Previously, we demonstrated immunocytochemically that certain phenylethanolamine N-methyltransferase neurons in the inner nuclear layer of rat retina contain other catecholamine synthesizing enzymes, including tyrosine hydroxylase and aromatic-L-amino acid decarboxylase but not dopamine beta-hydroxylase (DBH), the norepinephrine biosynthetic enzyme. In the present study by using a sensitive radioenzymatic assay for DBH we demonstrated the presence of DBH enzymatic activity in retinal extracts. Immunocytochemical studies, however, failed to demonstrate DBH-immunoreactive perikarya even in animals pretreated with colchicine, an inhibitor of axonal transport. Probably causes for these discrepant findings are discussed.

Animals↗
PubMed1988

Catecholaminergic neurons in the ventrolateral medulla and nucleus of the solitary tract in the human.

Catecholaminergic neurons in the ventrolateral medulla (VLM) and nucleus of the solitary tract (NTS) are important because of their presumed roles in autonomic regulation, including the tonic and reflex control of arterial pressure, neuroendocrine functions, and the chemosensitivity associated with the ventral medullary surface. However, little is known about the connections of these neurons in the human brain. As a first step in analyzing the functional biochemical anatomy of catecholamine neurons in the human, we used antisera against tyrosine hydroxylase (TH) and phenylethanolamine N-methyltransferase (PNMT) to localize medullary catecholamine-containing neurons and processes in the VLM and the NTS. Cells staining for TH were located throughout the VLM. Most cells staining for TH and PNMT, which are therefore adrenergic, occurred in an area of the VLM probably corresponding to the rostroventrolateral reticular nucleus. Axons of TH-immunoreactive neurons in the VLM projected (1) dorsally, in a series of parallel transtegmental trajectories, toward the dorsomedial reticular formation, the NTS, and vagal motor nucleus, (2) longitudinally, through the central tegmental field, as fascicles running parallel to the neuraxis, (3) ventrolaterally toward the ventral surface (VS) of the rostral VLM where they appeared to terminate, and (4) medially into the raphe, where they arborized. Similar systems of fibers were labeled for PNMT; the longitudinal bundles of PNMT-labeled axons were limited to the principal tegmental bundle and concentrated dorsally. Fibers containing PNMT were also identified in the medullary raphe, on the medullary ventral surface, and contacting intraparenchymal blood vessels. In the NTS, neurons exhibited immunoreactivity to both TH and PNMT: Four principal subgroups of TH-immunoreactive neurons were seen: a ventral, an intermediate, a medial, and a dorsal group. Perikarya containing PNMT were restricted to the dorsolateral aspect of the NTS. Processes containing TH and PNMT immunoreactivity were identified in the medial and dorsolateral NTS; others appeared to project between the NTS and the VLM and within the solitary tract. The presence of catecholaminergic fibers of the VLM interconnecting with the NTS, raphe, intraparenchymal microvessels, VS, and possibly the spinal cord suggests that the autonomic and chemoreceptor functions attributed to these neurons also may apply to the human.

Adult↗
PubMed1988

Possible mechanism of action of SKF 64139 in vivo on rat adrenal and brain phenylethanolamine N-methyltransferase activity.

SKF 64139, a specific inhibitor of the epinephrine-synthesizing enzyme, phenylethanolamine N-methyltransferase (PNMT), has been widely used as a pharmacological tool for studying the characteristics of epinephrine-containing neurons. However, the mechanism of action of this drug on PNMT in vivo has not been fully elucidated. In the present study, we traced changes of PNMT activity in rat adrenal glands and medulla oblongata between 1 and 48 hr after intraperitoneal injection of SKF 64139 (50 mg/kg body wt). Within 1 hr, enzyme activity in both tissues decreased to 10% of the respective control value. However, starting at 4 hr, activity gradually recovered from the inhibition and completely returned to the respective control level by 48 hr. Removal of the inhibitor by dialysis substantially restored the adrenal enzyme activity in 1, 2 and 4 hr groups and completely returned it to control levels in 18 and 48 hr groups. A similar pattern also seemed to hold with brain extracts. The profiles of immunotitration curves, using dialyzed tissue extracts and specific antibodies to bovine adrenal PNMT, clearly indicate that, even after dialysis, a substantial amount of inactive enzyme was present in tissue extracts from 1, 2 and 4 hr groups. In contrast, by 18 hr a very small amount of inactive enzyme was present. Throughout the experimental periods there was no noticeable differences among the control and the experimental groups in the number or intensity of immunocytochemical stained neurons with PNMT antibodies of the C1 area of ventrolateral medulla. Judging from the data obtained by dialysis, immunochemical titration and immunocytochemical staining, recovery of PNMT activity following its inhibition by SKF 64139 was not due to irreversible inhibition of the enzyme followed by new enzyme synthesis. Instead, reversible binding of inhibitor to PNMT and its release were responsible for recovery. PNMT from the 1, 2 and 4 hr groups resisted further in vitro inhibition by SKF 64139 because the residual inhibitor was probably still bound to the enzyme.

Adrenal Glands↗
PubMed1988

Evaluation of human serum as a culture medium for studies of rat embryonic development in vitro.

The normal growth of rat embryos cultured in human serum supplemented with glucose and 10% rat serum is of potential use in the assessment of teratogenic risk in man. Before this technique can be widely applied, it is necessary to know whether the stages of the menstrual cycle at which a serum sample is tested materially affect the results obtained. Moreover, in order to achieve reproducible conditions we have found it necessary to add a minimal amount of rat serum to the human serum used for culture, but unnecessarily high levels of rat serum supplementation could over-compensate for any growth factor deficiency in human serum. Here we report that culture of rat conceptuses gives similar results irrespective of whether human first, second, or third trimester pregnancy serum, postnatal serum, or serum at various stages of the menstrual cycle is used. We also report that addition of 2% rat serum supplement is sufficient to achieve reproducible rat embryonic growth and differentiation in human serum.

Animals↗
PubMed1988

Glucagon gene regulatory region directs oncoprotein expression to neurons and pancreatic alpha cells.

The regulatory region of the rat preproglucagon gene targets expression of the SV40 large T oncoprotein to two cell types in transgenic mice, the pancreatic alpha cells and a set of neurons localized in the hindbrain, both of which normally produce preproglucagon. Additional neurons in the forebrain and midbrain stain for T antigen but do not express the endogenous glucagon gene. Synthesis of T antigen in endocrine alpha cells results in the heritable development of pancreatic glucagonomas. In brains of transgenic mice from three independent lineages, expression of the hybrid gene begins at embryonic day 12 in neuroblasts of the hindbrain, where it continues throughout adult life, most notably in the medulla. Remarkably, oncoprotein expression in both proliferating neuroblasts and mature neurons has no apparent consequences, either phenotypic or tumorigenic. Expression of the hybrid glucagon gene in both neurons and islet cells supports a possible interrelationship between these cell types.

Animals↗
PubMed1988

Effect of prazosin on microvascular perfusion during middle cerebral artery ligation in the rat.

The purpose of this study was to evaluate the effects of prazosin, an alpha 1-adrenoceptor antagonist, on morphometric indexes of the total and perfused cerebral microvascular bed 1 hour after middle cerebral artery (MCA) ligation in pentobarbital-anesthetized rats. We hypothesized that this agent would prevent catecholamine-induced vasoconstriction in the ischemic brain. Cerebral blood flow (CBF) was determined with 14C-iodoantipyrine, and the perfused microvascular bed was visualized using fluorescein isothiocyanate-dextran. MCA occlusion did not alter systemic hemodynamic or blood gas parameters. CBF averaged 29 +/- 15 (mean +/- SD) ml/min/100 g in the MCA-ligated cortex and 49 +/- 18 in the other examined brain regions. Prazosin did not significantly alter these CBF values, averaging 26 +/- 14 and 48 +/- 10, respectively. There were no significant regional differences in total capillaries/mm2 in either group. The percent of the capillaries/mm2 perfused (51 +/- 6%) was similar in the two groups in all examined regions except the ischemic cortex. In the MCA-ligated cortex, 22 +/- 8% of the capillary volume was perfused in comparison with 49 +/- 8% in the prazosin-treated group. Prazosin-treated rats had an increased percentage of their microvasculature perfused despite a similarly reduced CBF. Prazosin appeared to reduce diffusion distances in the ischemic cortex. This might be due to its alpha 1-adrenoceptor blocking activity.

Animals↗