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Biomedical subjects

J Yang

Publications and source records attributed to J Yang.

At least 667 records · Page 37Linked to original sources
PubMed1999

p53 induction as a genotoxic test for twenty-five chemicals undergoing in vivo carcinogenicity testing.

In vivo carcinogenicity testing is an expensive and time-consuming process, and as a result, only a relatively small fraction of new and existing chemicals has been tested in this manner. Therefore, the development and validation of alternative approaches is desirable. We previously developed a mammalian in vitro assay for genotoxicity based on the ability of cells to increase their level of the tumor-suppressor protein p53 in response to DNA damage. Cultured cells are treated with various amounts of the test substances, and at defined times following treatment, they are harvested and lysed. The lysates are analyzed for p53 by Western blot and/or enzyme-linked immunosorbent assay analysis. An increase in cellular p53 following treatment is interpreted as evidence for DNA damage. To determine the ability of this p53-induction assay to predict carcinogenicity in rodents and to compare such results with those obtained using alternate approaches, we subjected 25 chemicals from the predictive toxicology evaluation 2 list to analysis with this method. Five substances (citral, cobalt sulfate heptahydrate, D&C Yellow No. 11, oxymetholone, and t-butylhydroquinone) tested positive in this assay, and three substances (emodin, phenolphthalein, and sodium xylenesulfonate) tested as possibly positive. Comparisons between the results obtained with this assay and those obtained with the in vivo protocol, the Salmonella assay, and the Syrian hamster embryo (SHE) cell assay indicate that the p53-induction assay is an excellent predictor of the limited number of genotoxic carcinogens in this set, and that its accuracy is roughly equivalent to or better than the Salmonella and SHE assays for the complete set of chemicals.

Acyclic Monoterpenes↗
PubMed1999

Analysis of cyclin dependent kinase inhibitors in malignant astrocytomas.

The cyclin-dependent kinase inhibitors p16, p21, and p27 in human brain, and brain tumors were examined to explore clinicopathologic correlations. Western analysis and immunohistochemistry was performed and correlated retrospectively with the patients clinical characteristics. A trend was found between increased progression-free survival and p27 expression. There was no correlation between p27 expression and age or gender. The expression of p27 in malignant gliomas may have prognostic value. In addition, an investigation of the therapeutic benefit of overexpression of this cyclin-dependent kinase inhibitor is warranted given reports of diminished malignant potential of tumors expressing p27.

Adolescent↗
PubMed1999

Evaluation of scatter correction using a single isotope for simultaneous emission and transmission data. Phantom and clinical patient studies.

UNLABELLED: Photon scatter is one of the most important factors degrading the quantitative accuracy of SPECT images. Many scatter correction methods have been proposed. The single isotope method was proposed by us. AIM: We evaluate the scatter correction method of improving the quality of images by acquiring emission and transmission data simultaneously with single isotope scan. METHOD: To evaluate the proposed scatter correction method, a contrast and linearity phantom was studied. Four female patients with fibromyalgia (FM) syndrome and four with chronic back pain (BP) were imaged. Grey-to-cerebellum (G/C) and grey-to-white matter (G/W) ratios were determined by one skilled operator for 12 regions of interest (ROIs) in each subject. RESULTS: The linearity of activity response was improved after the scatter correction (r = 0.999). The y-intercept value of the regression line was 0.036 (p < 0.0001) after scatter correction and the slope was 0.954. Pairwise correlation indicated the agreement between nonscatter corrected and scatter corrected images. Reconstructed slices before and after scatter connection demonstrate a good correlation in the quantitative accuracy of radionuclide concentration. G/C values have significant correlation coefficients between original and corrected data. CONCLUSION: The transaxial images of human brain studies show that the scatter correction using single isotope in simultaneous transmission and emission tomography provides a good scatter compensation. The contrasts were increased on all 12 ROIs. The scatter compensation enhanced details of physiological lesions.

Back Pain↗
PubMed1999

The biology of P-selectin glycoprotein ligand-1: its role as a selectin counterreceptor in leukocyte-endothelial and leukocyte-platelet interaction.

Cell-cell interactions mediating leukocyte trafficking, thrombogenesis and inflammation are crucial for the host defense mechanism. The selectin family of integral membrane proteins includes E-selectin, L-selectin and P-selectin. Selectins mediate tethering and rolling of leukocytes to the vessel wall at the site of inflammation. The counter-receptor for P-selectin and possibly the other selectins is P-selectin glycoprotein ligand-1 (PSGL-1). This review focuses on the properties and biology of PSGL- 1.

Animals↗
PubMed1999

Using three-dimensional-computerized tomography as a diagnostic tool for temporo-mandibular joint ankylosis: a case report.

Roentgenographic examination has long been a useful diagnostic tool for temporo-mandibular joint (TMJ) disease. The methods include TMJ tomography, panoramic radiography and computerized tomography (CT) scan with or without injection of contrast media. Recently, three-dimensional CT (3D-CT), reconstructed from the two-dimensional image of a CT scan to simulate the soft tissue or bony structure of the real target, was proposed. In this report, a case of TMJ ankylosis due to traumatic injury is presented. 3D-CT was employed as one of the presurgical roentgenographic diagnostic tools. The conventional radiographic examination including panoramic radiography and tomography showed lesions in both sides of the mandible. CT scanning further suggested that the right-sided lesion was more severe than that on the left. With 3D-CT image reconstruction the size and extent of the lesions were clearly observable. The decision was made to proceed with an initial surgical approach on the right side. With condylectomy and condylar replacement using an autogenous costochondral graft on the right side, the range of mouth opening improved significantly. In this case report, 3D-CT demonstrates its advantages as a tool for the correct and precise diagnosis of TMJ ankylosis.

Ankylosis↗
PubMed1999

Characterization of human small intestinal cytochromes P-450.

Human small intestine epithelial cells (enterocytes) provide the first site for cytochrome P-450 (CYP)-catalyzed metabolism of orally ingested xenobiotics. The CYP composition of enterocytes could thus affect the potential toxicity or therapeutic efficacy of xenobiotics by modifying systemic uptake. We have characterized human enterocyte CYP composition to enable assessment of its functional roles. An isolation method for enterocytes from human small intestine was developed using EDTA buffer-mediated elution. Villous enterocytes were isolated in high yield, separated from crypt cells. Reverse transcriptase-polymerase chain reaction of total RNA from enterocytes revealed that CYP1A1, 1B1, 2C, 2D6, 2E1, 3A4, and 3A5 mRNA were expressed, but only CYP2C and 3A4 were detectable by Western immunoblotting in enterocyte microsomes from 10 human small intestines, whereas CYP1A1 was weakly detectable in two of eight intestines tested. Microsomal protein content decreased markedly along the small intestine from the duodenum to the ileum, whereas total CYP content and CYP3A4 erythromycin N-demethylase activity increased slightly in progressing from the duodenum to the jejunum and then decreased markedly toward the ileum. Levels of CYP3A4 and 2C protein did not decrease in concert as a function of length along the intestine distally. Maximal CYP content for the 10 intestines varied from 0.06 to 0.18 nmol/mg microsomal protein and maximal CYP3A4 erythromycin N-demethylase activity varied from 0.30 to 0.76 nmol/min/mg microsomal protein. In conclusion, CYP3A4 is the major form of CYP expressed in human small intestine enterocytes, CYP3A5 expression was not detected, CYP2C and, in some intestines, CYP1A1 were expressed. The highest metabolic activity occurred in the proximal intestine.

Adolescent↗
PubMed1999

Coronal approach for the replacement of the condylar head in bilateral temporomandibular joint ankylosis: report of three cases.

Limitation of mouth opening has long been the chief complaint for patients who suffer from temporomandibular joint (TMJ) ankylosis. For surgical treatment of this disease, several ways have been employed for access to the condylar fossa, including the preauricular, postauricular, perimeatal, endaural and Risdon approaches. In this article, we report three patients with bilateral TMJ ankylosis who underwent replacement of both condylar heads using the bicoronal approach. The advantages demonstrated with this surgical technique are ease of access to the condylar head, ideal surgical exposure field, utility of temporalis muscle and fascia and minimal risk of facial paralysis.

Adult↗
PubMed1999

Different responses of cerebral vessels to -30 degrees head-down tilt in humans.

This study explored changes of the cerebral circulation and evaluated the responses to weightlessness in 12 volunteers (18-22 yr of age). The velocities, diameters and blood flow volume of the common carotid artery (CCA), internal carotid artery (ICA), vertebral artery (VA) and internal jugular vein (IJV) were measured with color Doppler echogram before and during simulated weightlessness. -30 degrees head-down tilt (HDT) for 45 min was used as a weightlessness simulation model. When the subjects' positions were changed from the supine to -30 degrees HDT, blood flow velocities along the CCA, ICA and IJV decreased significantly (p< 0.05), and their diameters were increased. The subjects were divided into two groups according to measured changes in flow volume of the ICA and IJV: group I with a net in-flow of cerebral blood flow (CBF) and group II with a net out-flow of CBF during HDT. Symptoms were recorded in the two groups during HDT (nasal congestion, sensation of head fullness, headache, and others) and graded on a four-point scale, from absent to serious. Results showed that group I had a higher symptoms score while group II had a lower symptoms score. Although this difference did not reach statistical significance, it suggests that cerebral blood flow changes may be partly responsible for the symptoms observed in subjects during HDT.

Adolescent↗
PubMed1999

[Cloning of the idiopathic azoospermia related genes with mRNA differential display method].

OBJECTIVE: Defect of some genes related to spermatogenesis may result in male infertility with azoospermia. This study aimed to clone some of the genes. METHODS: Testis tissues from a patient with idiopathic azoospermia and from a normal fathered man were investigated with an improved mRNA differential display approach. RESULTS: Significant difference was observed between the two tissues in gene expression. Five differential expressed sequence-tags (ESTs) were cloned and sequenced. Homology analysis with software advanced BLAST 2.0 showed that one EST shared 100% homology with cosmid L27h9, which located in Huntington's disease region on 4p16.3; the other 4 showed very low homology with sequences in GenBank. CONCLUSION: Azoospermia has complex genetic heterogeneity. A gene located in Huntington's disease region on 4p16.3 is expressed in human testis during the spermatogenesis, and a loss of its function may associate with azoospermia.

Cloning, Organism↗
PubMed1999

Seed germination patterns in green dragon (Arisaema dracontium, Araceae).

Arisaema dracontium (green dragon) is a perennial herb that is widely distributed in eastern North America. However, in Canada, at the northern edge of its distribution, the species is designated as "vulnerable" with respect to conservation status. In natural populations, seedlings are uncommon; the present study was undertaken in order to characterize seed and seedling properties in green dragon. Seeds were sampled from five sites, ranging from Ontario at the northern limit of the distribution range, to Louisiana in the south. Seed germinability ranged from 25 to 55%, depending upon source. Experiments indicated that neither the hard seed coat nor a water-soluble exudate from the seed was responsible for inducing or maintaining dormancy. Patterns of seed germination appear to reflect general climatic conditions at the sites where seeds had originated. Cold stratification at 3°C produced significantly greater relative germinability in all seed collections except the most southerly one, from Baton Rouge. These seeds also had a slower overall speed of germination. In contrast, germination of seeds from the most northerly site was promoted by cold stratification and occurred over a relatively brief period. Germination in alternating light and dark conditions decreased the speed of germination compared to germination in the dark, however exposure to light changed the phenology of germination by promoting development of adventitious roots and primary leaves in these seedlings.

Journal Article↗
PubMed1999

Evidence of a central role for p38 map kinase induction of tumor necrosis factor alpha in pancreatitis-associated pulmonary injury.

BACKGROUND: Tumor necrosis factor alpha (TNF alpha) has been implicated as an important mediator in acute pancreatitis-associated adult respiratory distress syndrome, but the precise pathogenesis remains unclear. The purpose of this work was to clarify the role of TNF alpha that is produced within the lung parenchyma in the inducement of pancreatitis-related pulmonary injury and to examine 1 of the potential pathways leading to the production of pulmonary TNF alpha. METHODS: Bile salt pancreatitis was induced in rats (n = 40) that were randomized to receive a p38 mitogen-activated protein (MAP) kinase inhibitor or vehicle. A separate group (n = 16) underwent sham operation. Pulmonary capillary permeability was determined with fluorescein isothiocyanate-labeled albumin and Evans blue dye, and lung histologic analysis was performed. TNF alpha protein was measured in bronchoalveolar lavage fluid, and p38 MAP kinase was activity determined by Western blot analysis. RESULTS: The induction of pancreatitis resulted in increased pulmonary capillary leakage and worsened histologic condition (P < .01 vs sham). Effective inhibition of p38 MAP kinase-induced TNF alpha production completely prevented pancreatitis-associated pulmonary injury (P < .01 vs vehicle). CONCLUSIONS: p38 MAP kinase-induced TNF alpha production plays a central role in the development of pulmonary dysfunction, which accompanies severe acute pancreatitis in this rodent model.

Acute Disease↗
PubMed1999

Identification of a novel intron and 4 polymorphisms in the gene encoding the gamma subunit of the epithelial sodium channel.

The amiloride-sensitive epithelial sodium channel is a highly selective sodium channel that constitutes the rate-limiting step of sodium reabsorption in distal nephrons. It consists of at least 3 subunits (alpha, beta, and gamma) of similar structure and plays an important role in sodium and fluid homeostasis. Defects of this channel have been critically implicated in Liddle syndrome (pseudoaldosteronism) and pseudohypo-aldosteronism type 1. A sample of 48 individuals from 23 nuclear families was selected from Anhui, China. We sequenced 12 exons and flanking intronic sequences and discovered a new 207-bp intron located in the previously described exon X of Thomas et al. (1996). In addition, 4 novel single nucleotide polymorphisms were identified; 3 were in exon 3 and 1 was in exon 13. Furthermore, 2 base substitutions in exon 13 were present in all the Chinese subjects compared with the published European SCNN1G DNA sequence.

Base Sequence↗
PubMed1999

Mechanisms of photoreceptor cell apoptosis induced by N-methyl-N-nitrosourea in Sprague-Dawley rats.

A single intraperitoneal injection of 75 mg/kg N-methyl-N-nitrosourea (MNU) was given to 50-day-old female Sprague-Dawley rats and examined sequentially 12 and 24 hours, and 3 and 7 days after MNU treatment. Photoreceptor cell death was evoked in all treated rats. After MNU treatment, 7-methyldeoxyguanosine DNA adduct was detected selectively in photoreceptor cell nuclei at 12 hours, followed by photoreceptor cell apoptosis as confirmed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-digoxigenin nick-end labeling signals which peaked at 24 hours and continued until day 7 when several layers of photoreceptor cell nuclei were left. In apoptosis cascade, down-regulation of Bcl-2 was seen at 12 hours and up-regulation of Bax was seen at 24 hours, and caspase family (caspase 3/CPP32, caspase 6/Mch2, and caspase 8/FLICE protease) activities peaked 72 hours after MNU treatment. Therefore MNU-induced photoreceptor cell death was attributed to DNA adduct formation restricted to photoreceptor cell nuclei leading to photoreceptor cell apoptosis by up-regulation of Bax protein, down-modulation of Bcl-2 protein, and activation of caspases 3, 6, and 8.

Animals↗
PubMed1999

Streptozotocin-induced diabetes in human apolipoprotein B transgenic mice. Effects on lipoproteins and atherosclerosis.

The effects of diabetes and lipoprotein lipase (LpL) on plasma lipids were studied in mice expressing human apolipoprotein B (HuBTg). Our overall objective was to produce a diabetic mouse model in which the sole effects of blood glucose elevation on atherosclerosis could be assessed. Mice were made diabetic by intraperitoneal injection of streptozotocin, which led to a 2- to 2. 5-fold increase in plasma glucose. Lipids were assessed in mice on chow and on an atherogenic Western type diet (WTD), consisting of 21% (wt/wt) fat and 0.15% (wt/wt) cholesterol. Plasma triglyceride and cholesterol were the same in diabetic and non-diabetic mice on the chow diet. On the WTD, male diabetic HuBTg mice had a >50% increase in plasma cholesterol and more very low density lipoprotein (VLDL) cholesterol and triglyceride as assessed by FPLC analysis. A Triton study showed no increase in triglyceride or apolipoprotein B production, suggesting that the accumulation of VLDL was due to a decrease in lipoprotein clearance. Surprisingly, the VLDL increase in these mice was not due to a decrease in LpL activity in postheparin plasma. To test whether LpL overexpression would alter these diabetes-induced lipoprotein changes, HuBTg mice were crossed with mice expressing human LpL in muscle. LpL overexpression reduced plasma triglyceride, but not cholesterol, in male mice on WTD. Aortic root atherosclerosis assessed in 32-week-old mice on the WTD was not greater in diabetic mice. In summary, diabetes primarily increased plasma VLDL in HuBTg mice. LpL activity was not decreased in these animals. However, additional LpL expression eliminated the diabetic lipoprotein changes. These mice did not have more atherosclerosis with diabetes.

Animal Feed↗
PubMed1999

Treatment of epiphora due to insufficiency of lacrimal passage by acupuncture at Jingming.

Since 1995, the authors have employed acupuncture at Jingming (UB 1) with the warming needles to treat epiphora due to insufficiency of lacrimal passages. Of the 68 treated eyes in 42 patients, 28 eyes were cured, 35 improved, and 5 ineffective with a total effective rate of 92.65%; and 12 eyes were cured and 34 improved by only one course of treatment.

Acupuncture Points↗
PubMed1999

Twenty-three cases of atrophic rhinitis treated by deep puncture at three points in the nasal region.

Atrophic rhinitis is a disease which manifests itself mainly by anosmia due to dryness and atrophy of the nasal mucosa. There is no specific therapy for the disease at present. In the past few years, 23 cases of atrophic rhinitis were treated mainly by deep puncture at three points in the nasal region with satisfactory results. In order to find out the functional changes of the nasal mucosa, the mucociliary transport rate (MTR), surface temperature of the conchal mucosa, acid-base scale of nasal secretion, and volume of nasal secretion were determined before and after the treatment.

Acupuncture Points↗
PubMed1999

[Cost-benefit analysis for hepatitis A vaccine].

OBJECTIVE: To improve economic benefits of hepatitis A (HA) vaccination and to lay a foundation for formulating an immunization strategy for it. METHODS: Health economics methods were used for analyzing the cost-benefit ratio, balance point of cost-benefit and balance point of antibody level after HA vaccination. RESULTS: The benefit-cost ratio (BCR) for HA vaccine was 2.53 in Jiangxing City of Zhejiang Province with an HA-specific incidence rate of 41.15 per ten thousand. Incidence rate of HA was 16.26 per ten thousand at balance point of cost-benefit of HA vaccine. Cost would be reduced if serum HA antibody was screened before vaccination in the population with more than 50% of seropositive HA antibody. CONCLUSION: It indicated that more economic benefits would be gained if mass HA vaccination strategy was used. Vaccinee of choice was those at ages of 15 to 29 years. HA vaccination after antibody screening in the population aged over 25 years would be more economic than the direct use.

Adolescent↗