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Biomedical subjects

Y H Shih

Publications and source records attributed to Y H Shih.

At least 55 records · Page 3Linked to original sources
PubMed1992

[Epidemiologic study of head injuries in Taipei City, Taiwan].

This study was designed to examine the descriptive epidemiology of head injuries in an urban population in the Taiwan area, Taipei City, during the period from July 1, 1987 to June 30, 1988. Clinical records reviewed included emergency room (ER) charts, inpatient charts of 19 major hospitals, death registration forms and medical examiners' reports in this city. A formulated definition was used to identify patients with head injuries. A total of 4,692 cases were collected, which included 4,319 hospital inpatients and 373 non-hospital deaths. The average incidence rate for head injury was 180/100,000 per year, 246/100,000 for males and 111/100,000 for females. The highest incidence rate was observed in the elderly group followed by the age group of 20-29 years. Sixty eight percent of the head injuries were caused by traffic accidents, 59.7 percent of which were involved in motorcycle rides. This rate was higher than those in any western reports. Among the 10-39 age group, the head injuries caused by traffic accidents were mainly due to motorcycle accidents. However, most of the children and the elderly who were injured were either pedestrians or bicycle riders. The average mortality rate was 23/100,000 per year, 34/100,000 for males and 12/100,000 for females. Initially the Glasgow Coma Scale was used in assessing the severity of head injuries. Seventy-two percent of the cases were considered mild, and 28 percent moderate to severe in degree, including 609 deaths.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Pharmacological characterization of PD 118717, a putative piperazinyl benzopyranone dopamine autoreceptor agonist.

PD 118717 (7-[3-[4-(2-pyrimidinyl)-1-piperazinyl]-propoxy]-2H-1- benzopyran-2-one sulfate) proved to be a dopamine (DA) D-2 autoreceptor agonist in biochemical and electrophysiological studies in rats and to exhibit an antipsychotic-like profile in behavioral tests in rodents and monkeys. In vitro binding studies indicated that PD 118717 bound selectively to DA D-2 vs. D-1 receptors and exhibited agonist binding properties (biphasic inhibitory curves and GTP shift) similar to DA. It also had significant affinity for serotonin-(5-HT)1A but not 5-HT1B and 5-HT2 receptors. PD 118717 was active in antagonizing the tau-butyrolactone-induced accumulation of dopa in rat striatum and mesolimbic regions. PD 118717 also depressed the firing of DA neurons in substantia nigra pars compacta of rats. In both of the latter tests the effects of PD 118717 were reversed by haloperidol. PD 118717 decreased brain DA metabolism, decreased DA utilization, decreased accumulation of dopa after inhibition of L-aromatic amino acid decarboxylase, stimulated serum corticosterone and inhibited stimulated serum prolactin levels. PD 118717 did not alter striatal acetylcholine levels; nor did it induce locomotor stimulation or stereotypy in normal animals, suggesting a lack of postsynaptic DA stimulation of normosensitive DA receptors. In tests designed to reveal even weak postsynaptic DA agonist effects, PD 118717 stimulated locomotor activity in 6-hydroxydopamine-lesioned animals and relatively higher doses induced a low degree of stereotyped behavior when combined with the DA D-1 agonist SKF 38393. PD 118717 decreased the accumulation of 5-hydroxytryptophan in brain, an effect probably due to an agonist action at 5-HT1A receptors. PD 118717 decreased spontaneous locomotor activity in rodents, antagonized amphetamine-stimulated hyperactivity in mice and inhibited Sidman avoidance in monkeys, effects seen with antipsychotic agents. Unlike DA antagonist antipsychotics, PD 118717 did not induce extrapyramidal dysfunction in monkeys. PD 118717 displayed behavioral activity after p.o. dosing and its effects did not show tolerance on repeated dosing. In conclusion, PD 118717 has the profile of a DA autoreceptor agonist in neurochemical and neurophysiological tests and produces effects suggestive of antipsychotic efficacy without neurological side effect liability in preclinical behavioral tests.

Animals↗
PubMed1991

Color pattern-reversal visual evoked potential in eyes with ocular hypertension and primary open-angle glaucoma.

Color pattern-reversal visual evoked potential testing was performed in 99 normal eyes, 27 eyes with ocular hypertension and 30 eyes with primary open-angle glaucoma with the use of black-white, black-red and black-blue color checkerboard stimuli. The P1 wave peak time and amplitude of the eyes with ocular hypertension and glaucoma were significantly different from those of age-similar normal eyes, especially on the black-red and black-blue checkerboards (p less than 0.001). The differences between the ocular hypertensive and glaucomatous eyes were of less significance. The P1 peak time difference between black-white and black-red checkerboards may serve as an important parameter in the early diagnosis of glaucoma.

Adolescent↗
PubMed1991

Calcium channel blocking and positive inotropic activities of ethyl 5-cyano-1,4-dihydro-6-methyl-2-[(phenylsulfonyl)methyl]-4-aryl-3- pyridine-carboxylate and analogues. Synthesis and structure-activity relationships.

The synthesis and pharmacological evaluation of a series of 2-[(arylsulfonyl)methyl]-4-aryl-5-cyano-1,4-dihydropyridine-3-carboxylic acid esters and analogues are described. These compounds possess a unique profile namely, calcium channel blocking and positive inotropic activities in vitro. Compound 54 was selected as the best compound in the series and was studied in detail. The synthesis and biological profiles of enantiomers of 54 are also reported. The data indicate that although the calcium channel blocking property of 54 is stereospecific the positive inotropic activity is not. Examples of 3- and 6-cyano and other closely related 1,4-dihydropyridine derivatives are described and evaluated for comparison and were found to be devoid of dual activities mentioned above.

Animals↗
PubMed1991

Tension pneumocephalus following ventriculoperitoneal shunt: a case report.

A case of tension pneumocephalus following suboccipital craniectomy and ventriculoperitoneal (VP) shunt surgery for obstructive hydrocephalus due to the presence of a cerebellopontine (CP) angle tumor is reported. The air entries were found on both sides of the frontal skull base. The formation of the fistula may have been either due to congenital bony defects or chronically elevated intracranial pressure. Iopamidol computed tomographic (CT) cisternogram was one of the diagnostic tools. Direct surgical repair of those bony-dural defects was mandatory in the prevention of the recurrence of the pneumocephalus.

Adult↗
PubMed1991

Intraoperative localization of sensorimotor cortex by cortical somatosensory evoked potentials.

Intraoperative cortical somatosensory potentials were evoked to localize the sensorimotor cortex under general anesthesia by contralateral median nerve stimulation in 12 patients. Eight patients underwent an excision of the epileptogenic focus for intractable complex partial seizures and the other 4 patients underwent tumor surgery following successful localization of the sensorimotor cortex. The relationships between the somatosensory evoked potentials and the anatomy of the sensorimotor cortex allowed rapid and accurate localization of the sensorimotor hand area: (1) the P2 recorded from the postcentral gyrus had a positivity of 49.0 microV on the average with a mean latency of 26.9 msec; (2) the N1 and P2 consistently showed phase-reversal across the Rolandic fissure; and (3) maximum SEP amplitudes were recorded from the hand representation area of the sensorimotor cortex. The neurophysiological and neurosurgical results demonstrate the feasibility of recording cortical SEP's under general anesthesia and the improvement of safety in surgical excisions near the sensorimotor cortex.

Adolescent↗
PubMed1990

Demarcation and localization of primary sensor and motor areas in human cortex by cortical somatosensory. Evoked potential (Co-SEP) during operation in surgery for epilepsy and intracranial tumor.

In neurosurgical operation, when the focus is close to the central fissure, precise delineation of the precentral motor and postcentral somatosensory areas is cardinal in defining the extent of the surgical resection. Eight ASA II-III patients scheduled for neurosurgery for intractable complex partial seizure (n = 5) and intracranial tumor (n = 3) were enrolled in the study. Subdural grids of electrodes were used for recording cortical evoked somatosensory potentials elicited by stimulating the median nerves to locate the primary somatosensory cortex and to delineate the central fissure through demonstration of phase-reversal pattern across the rolandic fissure. In all cases under general anesthesia, we were able to determine precisely the location of the central fissure. At the same time, we detected the evoked potential from SII (second sensory area) in one patient with intracerebral tumor. In conclusion, Co-SEP under general anesthesia is feasible and recommended to be performed as a routine intraoperatively for intractable epilepsy and tumor originating close to the primary motor or sensory strip in order to avoid iatrogenic damage to the vital cerebral cortex.

Brain Neoplasms↗
PubMed1989

Effects of CI-926 (3-[4-[4-(3-methylphenyl)-1-piperazinyl] butyl]-2,-4-imidazolidinedione), an antihypertensive agent, on rat brain catecholamine and serotonin turnover.

The effects of the antihypertensive drug CI-926 on rat brain norepinephrine (NE), dopamine (DA), and serotonin (5-HT) turnover and its in vitro affinity for several receptors were investigated. CI-926 (3-30 mg/kg intraperitoneally, i.p.) caused a dose-dependent increase in the rate of brain stem NE synthesis and increased the decline in NE after inhibition of its synthesis by alpha-methyl-p-tyrosine. These findings indicated that CI-926 increased brain NE turnover, probably as a compensatory response to central adrenoceptor blockade based on its nanomolar affinity for alpha 1-adrenoceptors and micromolar affinity for alpha 2-adrenoceptors. CI-926 also increased the rate of DA synthesis and DA metabolite levels; this indicates an increase in DA turnover. The latter effect of CI-926 is attributed to a compensatory response to DA-2 receptor blockade because no affinity for DA-1 relative to DA-2 receptors was found and the effect was antagonized by the DA agonist pergolide. CI-926 decreased brain 5-HT turnover, as indicated by reduced concentrations of the 5-HT metabolite 5-hydroxyindoleacetic acid and a reduced rate of 5-HT synthesis, effects characteristic of centrally acting 5-HT agonists. Based on its affinity for 5-HT-1A receptors versus 5-HT-1B and 5-HT-2, the decrease in 5-HT synthesis and release is interpreted as evidence of 5-HT-1A receptor activation. These findings indicate that besides peripheral alpha 1-adrenergic blockade, an interference of CI-926 with central adrenergic and serotoninergic neurotransmission may contribute in part to an explanation of its antihypertensive properties.

Animals↗
PubMed1989

CI-943, a potential antipsychotic agent. II. Neurochemical effects.

The effects of CI-943 (a novel 8-ethyl-7,8-dihydro-1,3,5-trimethyl-1H-imidazo[1,2-c]pyrazolo[3,4- e]pyrimidine compound exhibiting a favorable antipsychotic profile in animal tests) on neurochemical parameters related to biogenic amine neurons have been studied in rat brain. CI-943 (1-40 mg/kg p.o. and 20 mg/kg i.p.) accelerated the turnover of dopamine (DA) in rat brain as demonstrated by the enhancement of levels of the DA metabolites homovanillic acid, 3,4-dihydroxyphenylacetic acid or 3-methoxytyramine and by the enhancement rate of DA synthesis in either striatum or mesolimbic regions. These increases in DA turnover induced by CI-943 are not due to DA receptor blockade as CI-943, unlike known antipsychotics, did not exhibit affinity for DA receptors either in vitro or in vivo and did not affect rat serum basal prolactin levels. Amfonelic acid enhanced the action of haloperidol in increasing striatal homovanillic acid with no effect on that of CI-943 and clozapine, suggesting that CI-943, like clozapine, would be predicted to have a low risk of extrapyramidal side effects as compared to haloperidol. Chronic administration of CI-943 (40 mg/kg i.p.) to rats for 28 days did not affect the affinity or number of striatal DA receptors; in comparison haloperidol (0.5 mg/kg i.p.) caused an increase in number of DA receptors with no change in affinity. Measures of serotonergic function were increased; noradrenergic function was not affected by CI-943, nor did it exhibit affinity for a number of central nervous system receptors in vitro. The molecular mechanism by which CI-943 increases brain DA turnover is not known at this time but appears to be unique in comparison to known antipsychotic agents.

Animals↗
PubMed1988

Interaction between propranolol and calcium channel blockers in cardiac and vascular smooth muscle.

The ability of the beta-receptor antagonist propranolol to influence the response of isolated cardiac and vascular smooth muscle to several classes of calcium channel blockers was examined. For comparison, the interactions between propranolol and other classes of negative inotropic and vasorelaxant agents was also evaluated. The results of these studies demonstrate that propranolol pre-treatment significantly enhances the in vitro response to the dihydropyridine calcium channel blocker nifedipine, but not the thiazapine calcium channel blocker diltiazem. This enhancement was unrelated to the negative inotropic or vasorelaxant properties of these agents. In addition, propranolol pre-treatment of rat cortical membranes also enhanced the affinity of nifedipine for the 3H-nitrendipine binding site, but did not alter the effect of diltiazem on 3H-nitrendipine binding. These observations suggest that a direct interaction may exist between beta-receptor antagonists and dihydropyrine-type calcium channel blockers. This interaction may be an important factor in selecting drug therapy for conditions such as hypertension and angina.

Animals↗
PubMed1988

2-(2-Aryl-2-oxoethylidene)-1,2,3,4-tetrahydropyridines. Novel isomers of 1,4-dihydropyridine calcium channel blockers.

The title compounds are novel double bond isomers of 1,4-dihydropyridine-type calcium channel blockers (CCB). These derivatives were prepared by using the Hantzsch dihydropyridine synthesis. The assignment of structure was based on spectroscopic data and a regiochemically unambiguous synthesis. Several of the analogues inhibited [3H]nitrendipine binding with IC50 values as low as 25 nM. By comparison, nifedipine, a clinically useful 1,4-dihydropyridine CCB, inhibits [3H]nitrendipine binding with an IC50 of 1.6 nM. In the Langendorff rat heart preparation, treatment with the more potent derivatives produced marked dose-related increases in coronary flow with little or no effect on heart rate or contractility, except at the highest concentrations tested. The selectivity for vascular versus cardiac effects was similar to that of nifedipine, i.e., the concentration producing vasodilation was approximately 2 orders of magnitude lower than the concentration eliciting cardiodepression. These novel isomers extend the structure-activity relationships for calcium channel blockers into a series closely related to the 1,4-dihydropyridines.

Animals↗
PubMed1985

The effects of various cognition-enhancing drugs on in vitro rat hippocampal synaptosomal sodium dependent high affinity choline uptake.

The purpose of the present study was to compare the effect of seven drugs, that have been reported to enhance cognitive functions, on rat hippocampal cholinergic neuronal activity. The latter was assessed by measuring the effects of the drugs on in vitro sodium-dependent high affinity choline uptake (HACU) into rat hippocampal synaptosomes 30 minutes after their in vivo administration. 3,4-Diaminopyridine (0.1 mg/kg IP), like pramiracetam (44 and 88 mg/kg IP), increased HACU with higher or lower doses being ineffective. Centrophenoxine (100 mg/kg IP) decreased HACU. Piracetam (100 and 500 mg/kg IP), aniracetam (10-200 mg/kg PO), lysine vasopressin (0.005-0.05 mg/kg IM) and 4-aminopyridine (0.01-3.0 mg/kg IP) were ineffective. The results indicate that 3,4-diaminopyridine and centrophenoxine, like pramiracetam may be increasing cognitive function in part by affecting hippocampal cholinergic neuronal activity. In addition, the findings indicate the usefulness of using in vitro HACU as a biochemical measurement to assess the potential effect of cognitive-enhancing drugs on cholinergic neuronal activity in vivo.

Adrenocorticotropic Hormone↗
PubMed1984

Renal ultrasound in acquired immune deficiency syndrome.

Ten patients with clinical and laboratory features of acquired immune deficiency syndrome (AIDS) underwent renal ultrasonography prior to biopsy because of proteinuria, azotemia, or uremia. Four patients had a history of intravenous heroin abuse and were considered separately so as to exclude it as a cause of nephropathy. Histological examination revealed focal segmental glomerulosclerosis (FSGS), which in patients with AIDS is characterized by rapid progression to severe uremia (though FSGS can also occur in several other forms of renal disease). The authors recommend that AIDS-associated FSGS be considered as a cause of type I parenchymal disease and suggest that serial sonograms may be useful in monitoring progressive renal involvement.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Sonographic identification of collecting system duplications.

Sonography can replace urography in the search for a duplication anomaly of the collecting system. As a screening procedure, sonography is more cost effective and does not require ionizing radiation or an intravascular injection.

Diagnosis, Differential↗