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Biomedical subjects

R L Zhang

Publications and source records attributed to R L Zhang.

47 records · Page 3Linked to original sources
PubMed1993

Postischemic (1 hour) hypothermia significantly reduces ischemic cell damage in rats subjected to 2 hours of middle cerebral artery occlusion.

BACKGROUND AND PURPOSE: We investigated the effect of hypothermia induced 1 hour after transient (2-hour) middle cerebral artery occlusion on the extent of ischemic cell damage in the rat. METHODS: Middle cerebral artery occlusion was induced extracranially by insertion of a nylon filament into the right internal carotid artery. Two groups of rats were investigated: (1) rats (n = 10) subjected to normothermic (37 degrees C) ischemia and normothermic reperfusion; and (2) rats (n = 10) subjected to normothermic ischemia and 1 hour of normothermic reperfusion followed by 3 hours of hypothermia (30 degrees C). All rats were killed 1 week after the experiment, and brain sections were stained with hematoxylin and eosin for evaluation of ischemic cell damage. RESULTS: Infarct volume in normothermic rats involved 20.9 +/- 4.6% of the hemisphere, whereas hypothermic rats exhibited a significantly smaller (P < .001) infarct volume of 11.1 +/- 2.7%. The numbers of surviving (or structurally intact) neurons within large sections of the cortex and striatum were significantly greater for hypothermic compared with normothermic rats (P < .01). CONCLUSIONS: Our data suggest that postischemic induction of hypothermia significantly reduces ischemic cell damage after 2 hours of middle cerebral artery occlusion in the rat, and that an interval of time of at least 1 hour after ischemia exists in which hypothermic intervention is effective in either salvaging or postponing irreversible neuronal injury.

Animals↗
PubMed1992

Cholecystokinin upregulation during intestinal repair.

To determine whether cholecystokinin (CCK), a small intestinal hormone, may have autocrine or paracrine functions, gene regulation in the rat stomach and duodenum has been evaluated following cytotoxic injury. We quantified total RNA, CCK messenger RNA (mRNA), total protein, small and large forms of CCK peptides and gastrin. The stomach and the intestine respond differently. Following cytotoxic injury duodenal total RNA falls (1.5 +/- 0.1 vs 0.18 +/- 0.04 mg/g P less than or equal to 0.0001), and CCK mRNA content is depleted (260 +/- 23 vs 41 +/- 8 pg CCK mRNA/duodenum P less than or equal to 0.0001), yet there is a paradoxical increase in CCK mRNA concentration (176 +/- 20 vs 303 +/- 38 pg CCK mRNA/mg total RNA P less than or equal to 0.01). Increases occurred in both molecular species of CCK peptides evaluated: CCK8 (8 +/- 7 vs 26 +/- 2 pmole/g P less than or equal to 0.0001), large forms of CCK (42 +/- 4 vs 250 +/- 27 pmole/g P less than or equal to 0.0001). By contrast, in the stomach, only decreases were observed. These data identify sites of anatomical and biosynthetic upregulation during gastrointestinal repair. Changes are dependent upon the length of the period of recovery, differ between stomach and duodenum, and may be age related. Intestinal CCK may have para- and or autocrine roles in addition to its hormone function.

Animals↗
PubMed1992

Effects of rifampicin on pharmacokinetics of isoniazid and its metabolite acetylhydrazine in rats.

After i.v. and i.p. injections of isoniazid (Iso) 40 mg.kg-1 to male Wistar rats, the plasma levels of Iso, acetylisoniazid (AcIso), and acetylhydrazine (AcHz) were determined by spectrophotometric method and gas chromatography. The results suggested that the pharmacokinetic behavior of Iso in rats belonged to a 2-compartment model. The plasma levels of AcHz in rifampicin (Rif 30 mg.kg-1)-pretreated rats were lowered vs the control (P < 0.05 or < 0.01). The T1/2 of AcHz was shortened by Rif (control group 3.3 h, Rif-pretreated group 1.4 h) after i.v. injection of AcHz 10 mg.kg-1 to rats and the results showed that AcHz was converted to its active metabolites quickly by increasing the oxidative elimination rate of AcHz, which is related to the higher incidence of liver necrosis caused by Iso and Rif in combination.

Animals↗
PubMed1992

Gastrointestinal transit after spinal cord injury: effect of cisapride.

Heartburn, bloating, and abdominal discomfort are common problems in patients with spinal cord injury but, despite its clinical significance, little is known about the gastrointestinal effects of spinal transections. To address the potential gastrointestinal pathophysiology of spinal cord injury, we measured mouth-to-cecum transit time (MCTT) in seven subjects with paraplegia and seven with quadriplegia. Gastric emptying was studied in six subjects with quadriplegia. MCTT was significantly prolonged in patients with quadriplegia, an abnormality corrected by the administration of cisapride. Patients with paraplegia, in contrast to those with quadriplegia, have normal mouth-to-cecum transit time. In addition, patients with quadriplegia had neither a prolonged gastric emptying time nor a change in gastric emptying time, with cisapride. Changes in gastrointestinal transit after spinal cord injury and the improvement of mouth-to-cecum transit time in subjects with quadriplegia, but not in those with paraplegia, may be explained by an imbalance between parasympathetic and sympathetic outflows to the gastrointestinal tract in this group of subjects.

Adult↗
PubMed1992

Coronary artery disease: metabolic risk factors and latent disease in individuals with paraplegia.

Individuals with spinal cord injury (SCI) currently have a longer life span as a result of recent improvements in medical care. As in the able-bodied population, cardiovascular disease is the leading cause of death in persons with SCI, but it appears to occur at younger ages in those with SCI than in the able-bodied population. The reduction in level of activity and adverse changes in body composition caused by SCI have profound metabolic consequences that may influence the progression and severity of coronary artery disease. Metabolic sequelae of SCI include disorders of carbohydrate and lipid metabolism. Almost half of the 45 active, healthy subjects with paraplegia we studied have a disorder of carbohydrate tolerance, 1 in 5 subjects having a diabetic oral glucose tolerance test. Hyperinsulinemia is found in those with abnormal glucose tolerance. Subjects with paraplegia having impaired glucose tolerance or diabetes mellitus are significantly older than those with normal glucose tolerance. High-density lipoprotein cholesterol is markedly depressed, and low density lipoprotein is relatively elevated. Radionuclide myocardial perfusion imaging after upper body ergometry exercise reveals latent coronary artery disease in 12 of 19 subjects with paraplegia.

Adult↗
PubMed1991

Is aging preprogrammed? Observations from the brain/gut axis.

Age related differential gene expression occurs in the neuro-enteral axis. Brain and gut organ weight, total RNA, total protein and three peptides were quantified in 4-, 10- and 37-week-old Sprague-Dawley rats. As animals aged, total RNA decreased in the brain (0.65 +/- 0.3-0.28 +/- 0.03 mg/g), but remained stable in the gut (2.6 +/- 0.3-2.9 +/- 0.4 mg/g). Total protein concentration rose in the duodenum (612 +/- 28-734 +/- 34 mg/g), while levels remained stable in the brain (641 +/- 54-666 +/- 34 mg/g). Three peptides were studied, cholecystokinin (CCK), VIP and secretin. With increasing age, significant changes were found only in CCK a true neural-enteral peptide. The concentration of smaller molecular forms of CCK decreased in the brain (248 +/- 18-188 +/- 21 pmol/g), while they remained stable in the duodenum (33 +/- 2-36 +/- 3 pmol/g). By contrast, the concentration of the larger forms of CCK were stable in the brain (36 +/- 3-40 +/- 4 pmol/g), but rose in the gut (89 +/- 14-134 +/- 17 pmol/g). These data indicate that as rats age there is preprogrammed differential control of gene expression between brain and intestine.

Aging↗
PubMed1991

[Effects of lobeline on slow action potential and force of contraction of guinea pig papillary muscle].

Intracellular microelectrode techniques were used to study the effects of N1-receptor agonist lobeline on the slow action potentials (SAP) and the force of contraction (FC), induced by histamine, BaCl2 and aminophylline, in catecholamine-depleted guinea pig papillary muscles in the presence of an M-cholinergic receptor antagonist atropine (3 mumol.L-1). In these preparations lobeline (1-64 mumol.L-1) suppressed, in a dose-dependent manner, the action potential amplitude (APA), the action potential duration (APD), the maximal upstroke velocity (Vmax) and FC. Elevation of calcium concentration outside the myocardiac cells to 3.6 mmol.L-1 antagonized the effects of lobeline in different degrees. These results suggest that the lobeline inhibits the slow inward current Isi of myocardiac cells.

Action Potentials↗
PubMed1991

Analysis of eye lens-specific genes in congenital hereditary cataracts and microphthalmia of the miniature schnauzer dog.

The congenital hereditary cataracts and microphthalmia in the miniature schnauzer dog are inherited by an autosomal recessive mode. To understand the genetic basis of these diseases, the authors purified and analyzed leukocyte deoxyribonucleic acid (DNA) from affected and normal animals using a candidate gene approach. Because the genes that encode the lens-specific proteins, specifically, alpha, beta, and gamma crystallins and the membrane protein (MP26), are known to maintain the structure and function of the lens, the authors used complimentary DNA (cDNA) fragments that corresponded to the above genes to search for the mutations at their loci in the affected animals. They found no evidence of the gene deletion and rearrangement in any of the five loci. In addition, the hybridizable sequences of the dog DNA to the specific probes for the human chromosome 4 and 18 loci, which are reported to be involved in the abnormality of the human eye, seem to be unaffected. These data support the notion that the hereditary cataracts and microphthalmia in the dog may be associated with genes other than those reported for several animal systems.

Animals↗
PubMed1990

Survey of 34 pregnant women with hepatitis A and their neonates.

Thirty-four pregnant women with hepatitis A and their neonates were investigated on serum anti-HAV IgM, ALT (GPT) and clinical manifestations (with 34 randomized controls) during the outbreak of viral hepatitis A in Shanghai. The result showed no evidence of maternal-infant transmission of hepatitis A, and no birth defect was found. Sufficient rest and proper diet for and close surveillance of the pregnant woman were suggested to ensure the well-being of mother and child. In addition, we found immune gamma-globulin given to the neonates born of mothers with hepatitis A may be beneficial to avoid horizontal transmission of hepatitis A.

Adult↗
PubMed1990

[Pleomorphic xanthoastrocytoma--a case report].

Pleomorphic xanthoastrocytoma (PXA) is a very rare and special kind of astrocytoma. Most of the patients have a relatively favorable prognosis despite its bizarre and pleomorphic cells. A 13 year old girl with PXA in the right occipitoparietal region is reported. Under light microscope, the tumor was markedly pleomorphic; mitosis was occasionally encountered and necrosis was absent. Immunohistochemically, cytoplasm of the tumor cells was positive for GFAP stain. Under electron microscope, many tumor cells contained glial filaments and large lipid vacuoles. Pericellular basal laminae could be found about some tumor cells, indicating a possible origin from subpial astrocyte. The clinicopathologic features, histogenesis, differential diagnosis and prognosis of PXA are discussed with review of literature.

Adolescent↗