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Biomedical subjects

S Pan

Publications and source records attributed to S Pan.

At least 109 records · Page 6Linked to original sources
PubMed1995

A permanent human cell line (EA.hy926) preserves the characteristics of endothelin converting enzyme from primary human umbilical vein endothelial cells.

Purification of endothelin converting enzyme (ECE) from endothelial cells has been hindered by the difficulty in obtaining primary endothelial cells in large quantity. We therefore tested transformed human umbilical vein endothelial cells (EA.hy926) for ECE activity. Our data clearly demonstrate that this transformed cell line preserves the ECE properties of the primary cell line. These include: (i) one sharp activity optimum at neutral pH; (ii) characteristics typical of a metalloprotease; (iii) IC50 value for phosphoramidon of 1.8 microM (2.7 microM for HUVEC); (iv) no inhibition by captopril and thiorphan, inhibitors of angiotensin converting enzyme and neutral endopeptidase 24.11. The enzyme showed a substrate specificity for big ET-1:big ET-2:big ET-3 in a ratio of 40:2.5:1. This report presents evidence that a permanent human endothelial cell line, EA.hy926, preserves the ECE activity of HUVEC and is useful for the study of ECE and its regulation of ET-1 production.

Animals↗
PubMed1995

A logit analysis of the likelihood of leaving rural settings for registered nurses.

This study examined the net effects of individual and community factors on the likelihood of registered nurses leaving current jobs using a logit analysis. Based on data from a survey of 2,509 rural nurses, four separate models were estimated and compared: one for nurses in rural settings as a whole and the other three for nurses in hospitals, skilled nursing facilities, and community/public health agencies. Results of the general model indicated that nurses' marital status, age, position, income, job satisfaction, and satisfaction with the community were significant determinants of the likelihood of leaving current jobs. Job satisfaction was the most significant factor, followed by satisfaction with the community. Findings from the models for three different employment settings were similar to those of the general model. However, the significance of factors and their strength of effect on nurses' decisions to leave or stay in their current jobs differed across the three types of facilities. Based on these findings rural nursing administrators and policy-makers should give priority to retention strategies that focus on improving the job environment. The development of different strategies for different groups of nurses (i.e., by age or marital status) and different types of facilities should increase the benefit/cost ratio. In addition, programs that involve rural health care agencies in community and economic development should be further explored as an avenue to increased nurse retention in rural areas.

Adult↗
PubMed1995

Molecular and biochemical characterization of a Coccidioides immitis-specific antigen.

Results of earlier investigations have indicated that the saprobic phase of Coccidioides immitis produces a heat-stable, 19-kDa antigen with serine proteinase activity which has been suggested to be specific for this pathogenic fungus. In the present study we have determined the N-terminal and partial internal amino acid sequences of the purified, 19-kDa antigen, cloned the gene which encodes this polypeptide, and confirmed that the secreted proteinase is a Coccidioides-specific antigen (CS-Ag). Both the genomic and cDNA sequences are reported and reveal that the csa gene which encodes this antigen has no introns. A 543-bp open reading frame encodes a 181-amino-acid-containing protein with a predicted molecular mass of 19.8 kDa and an isoelectric point of 8.3. The csa gene was localized on chromosome I of three representative C. immitis clinical isolates on the basis of Southern hybridizations. Expression of the csa gene in Escherichia coli using the pET21a plasmid vector yielded a recombinant protein that was recognized in immunoblot assays by antibody raised to the purified 19-kDa CS-Ag. Secretion of the native antigen is suggested to occur by cleavage of a putative 23-residue signal peptide. The native CS-Ag showed a low degree of glycosylation. Analysis of the carbohydrate composition of the CS-Ag revealed xylose, mannose, galactose, and glucose. However, the purified antigen showed no affinity for concanavalin A. A PCR method with specificity and high sensitivity for detection of C. immitis genomic DNA, using a pair of synthetic oligonucleotide primers whose sequences were based on that of the csa gene, was developed. A 520-bp product was amplified only when C. immitis genomic DNA was used as the template. The lower limits of DNA detection using this PCR method were 1 pg of C. immitis genomic DNA by ethidium bromide staining and 100 fg after Southern hybridization. The csa gene-based PCR method for detection of C. immitis DNA is useful for culture identification and may have clinical applications for the diagnosis of coccidioidal infections.

Amino Acid Sequence↗
PubMed1995

[Acoustic characteristics of external auditory meatus after tympanoplasty with open mastoid reconstruction].

This study investigated the effects of down-wall tympanoplasty (open technique included skeletonizing of mastoid) upon external auditory meatus resonance characteristics. The probe tube microphone measurement was performed twice pre and post operatively. The resonance frequency of external auditory meatus remained constant, but the peak amplitude was increased by 0.83dB SPL (P < 0.05). The results indicated that a tympanoplasty with standard open techniques did not affect the normal external auditory meatus resonance characteristics.

Acoustics↗
PubMed1995

[Study on human gamma-crystallins: V. Non-enzymatic glycation of fetal lens gamma 1- and gamma 3-crystallins in vitro].

PURPOSE: To compare the non-enzymatic glycation of different human fetal gamma-crystallins induced by glucose and fructose. METHODS: gamma 1- and gamma 2-crystallin were separated by the Sephadex gel chromatography from human fetal lenses. The non-enzymatic glycations of these gamma-crystallins were conducted by incubating with glucose or fructose at 37 degrees C for 20 days. The opacity and pellet formation as well as changes on SDS-polyacrymide gel electrophoresis (SDS-PAGE) pattern and blue fluorescence production were observed. RESULTS: Although the two gamma-crystallins displayed similar alterations, gamma 1-crystallin was easier to produce aggregation and insolublization in early stage (i.e. 3 days). SDS-PAGE showed that there were aggregates, formed through disulfide and non-disulfide cross-links, and degraded peptides produced. The blue fluorescence increased in glycated gamma 3-crystalline solution. Fructose had more significant effects (i.e. aggregation, degradation, producing blue fluorescence) on gamma-crystallins as compared with glucose. CONCLUSION: Human fetal gamma 1- and gamma 3-crystallins are sensitive, at different extent (gamma 1 > gamma 3), to response to non-enzymatic glycation, and fructose has stronger effect than glucose on the glycation.

Crystallins↗
PubMed1994

Focal traumatic brain injury causes widespread reductions in rat brain norepinephrine turnover from 6 to 24 h.

The effect of right sensorimotor traumatic brain injury (TBI) in male Sprague-Dawley rats on brain norepinephrine (NE) turnover was assessed by measuring the decline of endogenous NE levels following tyrosine hydroxylase inhibition produced with alpha-methyl-p-tyrosine. Right sensorimotor cortex contusions were produced by a pneumatically driven piston which depressed the dural surface by 2 mm at 3.2 m/s. TBI rats were compared to uninjured, anesthetized controls at 6 h and 24 h after surgery. While NE turnover was not affected at the lesion site at 6 h after TBI, it was either abolished or decreased by 33-75% bilaterally in the hypothalamus and in the cerebral cortex surrounding and rostral to the lesion site. In the cortex caudal to the lesion site, NE turnover was completely abolished. NE turnover in cerebral cortex opposite the lesion site and in the contralateral cerebellum was decreased by 51 and 43%, respectively, at 6 h. At 24 h, NE turnover was either abolished or decreased bilaterally by 45-92% in all cortical areas, in the hypothalamus, cerebellum, locus coeruleus and medulla. Thus, right sensorimotor cortex contusion causes a marked, early and widespread depression of brain NE turnover. Since amphetamine increases NE turnover, this may explain the dramatic improvement in behavioral deficits which occurs following amphetamine administration at 24 h after such lesions.

Animals↗
PubMed1994

Evidence for a phylogenetic connection between Coccidioides immitis and Uncinocarpus reesii (Onygenaceae).

Coccidioides immitis is an anomaly amongst the human systemic fungal pathogens. Its unique parasitic cycle has contributed to confusion over its taxonomy. Early investigators mistakenly suggested that the pathogen is a protist, while others agreed it to be a fungus but placed it in four different divisions of the Eumycota. The taxonomy of C. immitis is still unresolved. Ultrastructural examinations of its parasitic and saprobic phases have revealed features that are diagnostic of the ascomycetous fungi. Moreover, striking similarities between the kind of asexual reproduction (i.e. arthroconidium formation) of this pathogen and certain anamorphic and teleomorphic members of the genus Malbranchea have suggested a close relationship. Teleomorphs of these Malbranchea species are members of the Onygenaceae (Order, Onygenales). This family also includes teleomorphs of two human respiratory pathogens, Histoplasma capsulatum and Blastomyces dermatitidis. Although the 18S rRNA gene sequences (1713 bp) of these two pathogenic forms differ from that of C. immitis by only 35 and 33 substitutions, respectively, their mode of conidiogenesis is characterized by production of solitary aleurioconidia rather than alternate arthroconidia. In this study we have used characters derived from biochemical, immunological and molecular analyses to compare relatedness between C. immitis, H. capsulatum, B. dermatitidis, and six non-pathogenic species of Malbranchea (the Malbranchea states of Uncinocarpus reesii and Auxarthron zuffianum, as well as M. albolutea, M. dendritica, M. filamentosa and M. gypsea). Evidence is presented which supports inclusion of C. immitis in the Onygenaceae, and indicates that a close phylogenetic relationship exists between the Malbranchea state of U. reesii and this respiratory pathogen.

Amino Acid Sequence↗
PubMed1994

Histological maturity of healed duodenal ulcer and ulcer recurrence after treatment with omeprazole or cimetidine.

We investigated the relationship between histological maturity of healed duodenal ulcer and ulcer recurrence after treatment with omeprazole or cimetidine for 4 weeks. The healing rates, 92.5 and 72.4% in omeprazole-treated and cimetidine-treated groups, respectively, showed no significant difference between groups (P > 0.05). Histologically, the regenerating mucosa of healed ulcer was divided into three categories: good, fair and poor patterns. Of the healed cases, 22 (59.5%) of 37 omeprazole-treated and 12 omeprazole-treated and 12 (28.6%) of 42 cimetidine-treated ulcers achieved a good pattern, showing significant difference between groups (P = 0.01). The recurrence rate at 3 months showed statistically significant difference (P < 0.05) between two groups: 5.4% in omeprazole-treated and 23.8% in cimetidine-treated patients. During the period between 3 and 6 months after healing, the difference in recurrence rate between omeprazole-treated and cimetidine-treated groups was statistically not significant (12.5% and 25%, respectively, P > 0.05), though the cumulative recurrence rate at 6 months showed a significant difference between groups (17.6% vs 44.7%, P = 0.027). All the recurrent cases of both groups had a fair or poor pattern of regenerating mucosa. The difference in recurrence rate was statistically significant between the healed ulcers with a good pattern and that with a fair or poor patterns both at 3 months and between 3 and 6 months after healing (P < 0.001 in each). We concluded that better histological maturity of regenerating mucosa may contribute to the lower early recurrence in omeprazole-treated cases than in cimetidine-treated cases.

Adolescent↗
PubMed1994

[Study on soluble proteins in human fetal lens].

Soluble proteins from corter of human fetal clear lenses were separated by column chromatography with Sepharyl S-300 (superfine) and determined by disc-PAGE and SDS-PAGE. The results documented from 18W, 21W (2 cases) and 24W fetal lenses suggested that a negative correlation tended to be presented between the age of fetus and fraction of alpha, beta 1 crystallins (r = -0.9542; r = -0.9674) and a positive correlation between the age of fetus and fraction of beta 2, gamma crystallins (r = 0.9666; r = 0.9970). There was no change in the alpha, beta 1, beta 2 crystallins on disc-PAGE. Among the fetuses of different ages, the blurred band of gamma crystallin seen in 18W and 21W fetal lenses was thickened in the 24W fetal lens. The SDS-PAGE showed that there was no significant difference among the polypeptides in each of alpha, beta 1, beta 2, gamma crystallins in the studied fetal lenses of different age groups. It is presumed that the normal lens is proportionally composed of four fractions of crystallin. This is hypothetically contributed to the maintenance of normal structure of the lens, why the proper proportion of four fractions of crystallins is depended either on proteins synthesis or on protein molecular assembly is not yet clear.

Chromatography, Gel↗
PubMed1994

Assessment of sulfhydryl group in individual rat lens protein subunits during galactose cataract development.

A specific reagent DACM [N-(7-Dimethylamino-4-methyl-3-coumarinyl)maleimide] is used to study the -SH groups in lens proteins of normal and galactose cataractous rats. DACM when reacts readily with -SH groups form strong fluorescent adducts. The two -dimensional electrophoresis with DACM pre-labeled proteins is a simple and sensitive method for detecting -SH groups of protein subunit. In the present study, based on IEF/SDS-PAGE electrophoretically characterized soluble crystallins, describes specific changes in -SH groups of protein subunit during the development of galactose cataract. The contents of -SH groups of crystallins are progressively decreased in cataractous (5+) lens, the reduction of -SH content in alpha- and beta- crystallin protein subunits of the normal and cataractous lens proteins is also noticeable.

Animals↗
PubMed1994

Role of oxygen-derived free radicals in the mechanism of cysteamine-induced duodenal ulcer in rats.

In this study, the possible role of oxygen-derived free radicals in cysteamine-induced duodenal ulcers in rats was investigated. Separate groups of rats were treated with 350 mg/kg cysteamine subcutaneously. Superoxide dismutase (SOD) activity and thiobarbituric acid (TBA) reactants in the duodenal mucosa were analyzed one, three, six, 12 and 24 hours after treatment, respectively. Cu,Zn-SOD activity significantly decreased from 41.79 +/- 3.53 NU/mg protein to 29.56 +/- 3.62, 27.23 +/- 3.02 and 24.64 +/- 3.07 NU/mg protein at three, six and 12 hours, respectively. TBA reactants, indicators of tissue injury by oxygen-derived free radicals, significantly increased from 0.18 +/- 0.10 nmol/mg protein to 1.31 +/- 0.12 and 1.57 +/- 0.09 nmol/mg protein at six and 12 hours after cysteamine treatment, respectively. We conclude that an increase of oxygen-derived free radicals and a decrease of Cu,Zn-SOD activity in the duodenal mucosa may be involved in the pathogenesis of cysteamine-induced duodenal ulcers in rats.

Animals↗
PubMed1994

A study of use of low dose aspirin in prevention of pregnancy induced hypertension.

Forty-six nulliparous women in third trimester of pregnancy with a raised blood pressure of 30 mm Hg (systolic) or/and 15 mm Hg (diastolic) or both, over baseline values were treated with 75 mg of aspirin per day. The results are compared with another 48 age, height, weight, and gestational period matched nulliparaous women with similar condition for trial selection, who were treated as control. There is considerable more number of cases in the control group than in aspirin treated group showing subsequent rise of BP, appearance of proteinuria, and severe pre-eclamptic toxaemia. The aspirin treated group showed increased mean gestational age at termination 39.4 +/- 2.6 weeks as against 38.2 +/- 3.4, increased foetal weight 2860 +/- 552 g as against 2540 +/- 720 g. No case of neonatal haemorrhagic manifestations or congenital malformations were seen. However not much result is obtained with aspirin therapy in cases with established pregnancy induced hypertension or with proteinuria. Hence it is concluded that aspirin therapy should be given to prevent pregnancy induced hypertension. As predictability of other screening tests are not unequivocal, criterion used in this series for screening may be used.

Aspirin↗
PubMed1993

The effect and mechanism of the prokinetic action of cisapride on gastrointestinal smooth muscle.

Cisapride is a new prokinetic agent which can facilitate or restore motility throughout the entire gastrointestinal tract. Although facilitation of acetylcholine release has been suggested, the mechanism of action of cisapride is not clear. To investigate the effect and mechanism of action of cisapride, we used isolated muscle strips (with mucosa and submucosa removed) of guinea pig antrum, ileum and colon to study: (1) the dose response to cisapride, (2) the effect of antagonists (atropine and tetrodotoxin) on the stimulatory effect of cisapride. Besides these studies, we also used 3H-acetylcholine release method to investigate the acetylcholine release effect of cisapride. Cisapride elicited a dose-related enhancement of baseline activity (motility index) on the antrum and contraction on the ileum and colon at the dose of 4, 40 and 400 nM. At higher doses (4 microM) cisapride caused inhibition. This bell-shaped dose response curve suggested that cisapride might be autoinhibitory or that the receptors of cisapride might consist of high affinity stimulatory and low affinity inhibitory sites. The stimulatory responses elicited by cisapride (400 nM) were not significantly inhibited by atropine and tetrodotoxin in the antrum, ileum and colon. This suggested that cisapride might act directly on the smooth muscle. Cisapride (400 nM) evoked a rather small increase of 3H-acetylcholine release on the antrum, ileum and colon. Because the percentage of increase was small and we had demonstrated that the stimulatory effects of cisapride were not blocked by atropine and tetrodotoxin, the acetylcholine release effect of cisapride was considered unimportant.

Acetylcholine↗
PubMed1993

[Relations between opacification of lens protein and pH].

Some of the acidic reagents or medicines (i.e. HCl, GSH & GSSG, Vit. C, Vit. B6) and basic reagents (Tris) were used to regulate the pH of water soluble protein and urea soluble protein solution of human lenses. At a certain pH, the lens protein solution appears opalescence, the pH of opacity solution which is measured by pH meter is around 5.6-6.3. The opalescence of water soluble and urea soluble lens protein solution of human fetal, adult and cataractous lenses were also determined by gradient acidic and basic solution. The result show that the opacity is more obvious in soluble protein solution of cataractous lenses and clear lenses than in that of fetal lenses, and the lens urea soluble protein has a marked opalescence in comparison with the water soluble protein. So we assume that cataractogenesis might be associated with the change of pH within lens.

Adult↗
PubMed1993

[Malonaldehyde, superoxide dismutase and human cataract].

UV-spectrophotometry and fluorometry were used to study Malonaldehyde (MDA) and Superoxide Dismutase (SOD) in normal, cataractous human lenses and red blood cells of the patients with cataract. MDA content of senile and complicated cataractous lenses was significantly higher than that of normal human lenses, while that of complicated cataract was significantly higher than that of senile cataract. SOD activity of senile and complicated cataractous lenses was significantly lower than that of normal human lenses, while there was no marked difference between senile and complicated cataractous lenses. Significant correlation between cataractous lenses and red blood cells was not found in MDA content and SOD activity. There was a negative correlation between SOD and MDA in normal human lenses, but no correlation between SOD and MDA in cataractous lenses. The study shows that lipid peroxidation may be one of the possible mechanisms of cataractogenesis in human, and emphasizes the role of SOD in prevention of photoperoxidative damages to the tissues.

Adult↗
PubMed1993

[Amino acid analysis of retinal S-antigen and interphotoreceptor retinoid-binding protein].

Retinal S-antigen and interphotoreceptor retinoid-binding protein (IRBP) were purified by DEAE-Sephacel ionexchange chromatography and Con A Sepharose affinity chromatography. Amino acid analysis of the S-antigen and IRBP was carried out and compared with that presented by others. The possible reason for difference with regard to some amino acids and related problems were analyzed and discussed.

Amino Acids↗