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Biomedical subjects

P Yang

Publications and source records attributed to P Yang.

At least 343 records · Page 19Linked to original sources
PubMed1990

[Effect of histamine on the action potential of the maxillary nerve in rabbits].

The significant enhancement of action potential as recorded from rabbit maxillary nerve with topically applied 1.0 mmol/L histamine on the nasal mucosa was completely blocked by pretreatment with diphenhydramine (H1 antagonist) but not with cimetidine (H2 antagonist). This fact gives new support to the concept that histamine exerts its pathological effect on nasal mucosa at least partly via an afferent nervous pathway of the trigeminal nerve.

Action Potentials↗
PubMed1990

[Serum antibodies to bovine retinal S antigen in the patients with uveitis and healthy subjects].

The antibodies to bovine S-Ag in sera were determined by ELISA in 43 patients with acute or chronic, anterior or panuveitis and in 32 healthy persons as controls. The results showed that the antibodies titers to bovine S-Ag in the patients with panuveitis were not different from those in the controls (P greater than 0.05). However the antibody titers to bovine S-Ag in the patients with anterior uveitis were significantly lower than those in the controls (0.01 less than P less than 0.05). It is suggested that there are naturally occurring antibodies to S-Ag in health persons. The relationship between antibodies to S-Ag and uveitis is discussed. It is indicated that natural antibodies to S-Ag may play a protective role in the healthy subjects.

Adolescent↗
PubMed1989

Predicting intrauterine growth retardation in sibships while considering maternal and infant covariates.

Data on 6,210 full-term sibships (gestational age greater than 36 weeks) reconstructed from birth certificates registered in Maryland between 1980 and 1984 were used to study sibship aggregation and recurrence risk of intrauterine growth retardation (IUGR) while considering maternal and infant covariates. In this study, IUGR was defined as being below the 10th percentile for race-, sex-, and gestational-age-specific birth weight based on all births registered in Maryland during 1984. Maternal factors (race, age at delivery, marital status, amount of prenatal care, concurrent illnesses, and complications during pregnancy) and infant factors (congenital malformations and first born child or not) were used as covariates in a modified logistic regression model which allowed correlation among sibs. First-time mothers who were under age 30 years, unmarried, received too little prenatal care, or had any reported pregnancy complications were at high risk of delivering an infant with IUGR. Even given the effects of these risk factors, however, there was a significant correlation in risk among full sibs (r = .237 +/- .028), which, combined with information on risk factors, can be used to estimate sibling recurrence risk for IUGR.

Adult↗
PubMed1989

Cytotoxic triterpenes from a Chinese medicine, Goreishi.

Bioactivity-guided fractionation of the methanol extract of Goreishi (the feces of Trogopterus xanthipes Milne-Edwards) afforded one new and three known cytotoxic triterpenes, namely, 3-O-cis-p-coumaroyltormentic acid, pomolic acid, 2 alpha-hydroxyursolic acid, and jacoumaric acid. In the course of this investigation, six additional compounds having no cytotoxic activity were isolated, namely, maslinic acid, 3-O-trans-p-coumaroylmaslinic acid, ursolic acid, tormentic acid, euscaphic acid, and a new triterpene, 3-O-trans-p-coumaroyltormentic acid. The structures of the new compounds were established on the basis of X-nucleus-proton correlation with fixed evolution time (XCORFE) and other spectroscopic evidence.

Animals↗
PubMed1989

[Effect of histamine on the capillary permeability of the nasal mucosa in normal rats].

The effect of histamine on the capillary permeability of the nasal mucosa was studied quantitatively in normal rats using the Evans blue technique. The content of Evans blue in terms of ng per mg of nasal mucosa was significantly (P less than 0.001) higher in histamine group than that in control group, and reached peak value five minutes after injection of histamine at the concentration of 10(-8) mol/L. It is thought that this preliminary result might be useful in selecting optimal concentration of the challenge agent and the optimal time to evaluate the reaction.

Animals↗
PubMed1989

[Ultrastructural localization of ferritin in glioma].

In this study, we localized ferritin in 30 cases of glioma under electron microscope by using immunogold staining technique, and detected serum ferritin concentration in 25 patients with gliomas by the ELISA method. The results were as follows: Ferritin positives were mainly diffused in the cell sap, and the strongest immunostain was in the secondary lysosomes, while the endothelial reticulum and Golgi apparatus were rarely found to contain ferritin. Mitochondria and nucleus never had ferritin. Elevated level of serum ferritin was seen in glioma of grade II, III and IV, but the serum ferritin level of grade I remained normal. After resection of the tumor, serum ferritin decreased. These results suggested that the neoplastic cells of glioma could synthesize ferritin and release it to the exterior of the cells resulting in elevated serum ferritin, which may be helpful for clinical diagnosis, treatment and prognosis of glioma.

Biomarkers, Tumor↗
PubMed1988

Effect of maternal and infant covariates on sibship correlation in birth weight.

Birth weight on 12,644 singleton infants from 6,196 sibships born in Maryland between 1980 and 1984 were used to estimate the effects of nine maternal and infant covariates on the sibship correlation in birth weight. Assuming a homogeneous correlation across all families, the estimated intraclass correlation was 0.4664 (+/- 0.0099). This high sibship correlation makes it possible to predict, with reasonable accuracy, the birth weight of a child given information on previous sibs, as well as covariates on the mother and/or infant pertinent to a given pregnancy. The reduction in variance associated with incorporating information on the nine covariates used here was approximately equal to that obtained by conditioning on a single previous sib. Testing for heterogeneity in correlation among different groups of families showed that a crude measure of parity (first live birth vs. other), time between births, mother's marital status, and maternal age at the birth of the last child significantly influenced the sibship correlation in birth weight.

Adult↗
PubMed1988

Distribution of polyamines and their biosynthetic enzymes in intestinal adaptation.

Ornithine decarboxylase (ODC) and the polyamines have been shown to be important for growth processes in the intestinal mucosa. The highest activity of ODC is found in the differentiated, nonproliferating villus-tip cells rather than in the rapidly proliferating undifferentiated crypt cells. During poststarvation refeeding and lactation, we now show that increases in ODC activity paralleled the time course of mucosal hyperplasia and thymidine incorporation. Increases in ODC (threefold) were similar in villus and crypt cells, and the villus-crypt gradient of decreasing ODC activity (40:1) was maintained. The activity of the other polyamine biosynthetic enzyme, S-adenosylmethionine decarboxylase (SDC), was highest in the crypt cells in the basal state and increased throughout the entire villus-crypt axis during refeeding and lactation, preserving a villus-crypt gradient opposite to that of ODC. During hyperplasia, all three polyamines increased. Putrescine was highest in the villus-tip cells, paralleling ODC activity, whereas spermidine and spermine were highest in the crypt cells and paralleled the distribution of SDC activity. Thus SDC activity and spermidine and spermine content may play a more important role than ODC and putrescine in regulation of intestinal mucosal proliferation. It is also possible that the threefold increases in the low levels of ODC in the crypt cells are adequate to trigger cell proliferation, whereas the higher ODC levels in villus cells may represent an association with the differentiation of the enterocytes.

Adaptation, Physiological↗
PubMed1988

Preoperative balloon occlusion of arteriovenous malformations.

Many materials have been utilized to embolize cerebral arteriovenous malformations (AVMs) preoperatively. Specific vascular anatomy with large feeding vessels deep to the nidus or aneurysms within feeding arteries favor the use of detachable balloons over other embolic agents. Detachable balloons allow test occlusion of a vascular pedicle before permanent occlusion and can obliterate aneurysms in feeding arteries. We describe 36 feeder arterial balloon occlusions performed in 31 patients. Twenty-nine patients subsequently had surgical resection. None of the patients developed normal perfusion pressure breakthrough or required blood transfusions. The preoperative balloon occlusion was judged by the neurosurgeon to decrease significantly the difficulty in surgical resection of the malformation. The remaining 2 patients underwent embolization before radiosurgery. One patient had aneurysms in the feeding artery, which was balloon-occluded to diminish the risk of hemorrhage. There were two neurological deficits and three asymptomatic arterial dissections related to the balloon procedure. Balloon occlusion of feeding arterial pedicles in selected cerebral AVMs may be a valuable surgical adjunct.

Adolescent↗
PubMed1988

Problems of genetic model testing in early onset periodontitis.

Familial aggregation of early onset or juvenile periodontitis (JP), a disorder that varies in expression and age of onset, has been recognized for some time. Autosomal recessive and X-linked inheritance patterns have been suggested, and one large pedigree has demonstrated autosomal dominant inheritance. The variability and age limitations in clinical phenotypic diagnosis present several problems to genetic analysis, because information on members of the youngest and older generations may be lost to the analysis. The purpose of the present study was to elucidate the genetic basis of JP by formal pedigree analysis and comparison of competing genetic models. Twenty-eight families were included, with general and specific autosomal models, and an X-linked model being compared. The autosomal recessive model provided the most parsimonious explanation of the data, and its likelihood was not significantly different from the more general model. Likelihoods for the sporadic (nongenetic) and X-linked models were considerably lower than the autosomal models. While comparison of genetic models suggests recessive inheritance of JP, the serious complications to pedigree analysis posed by limitations warns against acceptance of this conclusion, without more exhaustive evaluation of: (1) a more extensive collection of family data, (2) more complete investigation of the effects of age limitations on comparisons among competing models, and (3) elucidation of the importance of diagnosis and phenotype assignment of adults through past dental records.

Adult↗
PubMed1987

Differential protective effects of varying degrees of hypoxia on the cytotoxicities of etoposide and bleomycin.

Oxygen is thought to be involved both directly and indirectly in the mechanisms of action of several anti-cancer agents. We studied the effects of various oxygen concentrations on the cytotoxicities of the following drugs: bleomycin (BLM), etoposide (VP-16), doxorubicin (DOX), and mitomycin C (MMC). Human sarcoma cells, MESSA, were exposed to drug for 1 h at one of several oxygen concentrations: less than 1%, 2.5%, 5%, 21%, and 95%. Cytotoxicity was assessed by cellular incorporation of 3H-thymidine into DNA 5 days after drug exposure. Control experiments varying oxygen concentration without drugs demonstrated toxicity only at the highest concentration (95%). Three different responses of drug sensitivity to varying oxygen tensions were observed. BLM, which has been shown to utilize oxygen as a substrate in generating free radicals and producing DNA scission, demonstrated a progressive increase in cytotoxicity over the entire range of increasing oxygen concentrations. This is consistent with the model of a BLM-cation-oxygen complex and catalytic reduction of oxygen. VP-16, which also produces DNA strand breakage but by interaction with topoisomerase II, exhibited a threshold response. VP-16 toxicity was ameliorated by anoxic conditions (less than 1% O2), but not by oxygen concentrations of 2.5%-95%. The reason for this protective effect of anoxia with VP-16 is not clear. In contrast, acute anoxia had no effect on the cytotoxicities of DOX and MMC. We conclude that acute hypoxia protects cells from both BLM and VP-16 but that the nature of that protection is different. VP-16 toxicity is blunted only by severe anoxia, whereas BLM exhibits a dose response effect over the entire range of oxygen concentrations.

Bleomycin↗
PubMed1987

Polyamines in intestinal and pancreatic adaptation.

The intestinal mucosa is a rapidly proliferative tissue, with a highly dynamic cell population. Its total cellular mass is well controlled and can adapt, with hypo- or hyperplasia, to a wide variety of stimuli. Luminal nutrients, hormonal factors, and pancreatic and biliary secretions have all been implicated in the regulation of intestinal mucosal adaptation. Similarly, the same factors appear essential for the maintenance of exocrine pancreatic structure and function. The polyamines (putrescine, spermidine, and spermine) and the key enzyme controlling their synthesis (ornithine decarboxylase, ODC) are important for many cell growth processes, and may play important roles in intestinal and pancreatic adaptation. During intestinal adaptation in response to jejunectomy, lactation and pancreatico-biliary diversion (PBD), intestinal contents of ODC and polyamines are increased, paralleling increases in mucosal proliferative indices and DNA synthesis. With administration of the specific inhibitor of ODC (difluoromethylornithine, DFMO) the increases in ODC and polyamines are suppressed, and intestinal adaptation is abrogated. In pancreatic hyperplasia induced by caerulein, pancreatic polyamines are increased. With DFMO administration, caerulein-induced increases in pancreatic DNA synthesis were inhibited and pancreatic hypertrophy was partially suppressed. PBD-induced pancreatic hypertrophy, however, was not affected by DFMO. Thus, the role of polyamines in the adaptation of the pancreas, with a relatively quiescent proliferative status, is as yet undefined. It seems clear, however, that the induction of ODC and the resultant increase in polyamine biosynthesis are critical for the normal growth and especially for adaptive hyperplasia of the intestinal mucosa.

Adaptation, Physiological↗
PubMed1987

Genetic analysis of juvenile periodontitis in families ascertained through an affected proband.

Data from 28 families ascertained through a proband with juvenile periodontitis were used to test a series of Mendelian models of inheritance that included both autosomal and X-linked transmission. There was strong evidence of familial aggregation of this progressive dental disease, and the best-fitting model was an autosomal recessive model. Because of the rather limited age range for expression of the disease in this situation, simulations were done, in a model-choice analysis using samples of this size, to assess the chance of mistaking an autosomal dominant disease (with masking of the affected phenotype outside a specified age range) for an autosomal recessive disease. While the rate of Type II error was fairly high (40%) when competing models in these simulations were compared, these data suggest that it is reasonable to infer that juvenile periodontitis is an autosomal recessive disorder.

Adolescent↗
PubMed1986

Kinetic changes in mucosal ornithine decarboxylase activity during azoxymethane-induced colonic carcinogenesis in the rat.

In the azoxymethane (AOM)-treated rat model of colonic carcinogenesis, serial injections of the carcinogen lead to the eventual development of colonic tumors. However, the precise nature of carcinogenesis events in this commonly used model is not well defined, and the occurrence of classic initiation and promotion phases after serial injections is uncertain. Since increases in ornithine decarboxylase (ODC) activity have been associated with promotion in other tumor models, we measured mucosal ODC during AOM carcinogenesis in the rat. We gave male Fischer 344 rats ten weekly injections of AOM at a dose of 3 mg/kg (Wk 1-10) and measured colonic mucosal ODC activity during the entire 25-wk course. Colonic tumor incidence at Wk 25 was 0% in controls and 48% in AOM animals (15 of 31). Mucosal ODC in AOM animals was significantly increased over controls. The time course of changes in mucosal ODC was similar throughout the entire colon and differed generally in magnitude only. Distinct and prolonged increases in ODC activity occurred within 4 h of a single injection of carcinogen and persisted for at least 14 days. With a second AOM injection on Day 7, there was another distinct and prolonged increase in ODC over the persistently elevated activity. Over the entire 25 wk, the increase in ODC was distinctly biphasic, higher at Wk 2, 11, and 13 than at Wk 6, 17, 21, and 25. The findings indicate that AOM induces an increase in mucosal ODC during colonic carcinogenesis, and they suggest that this carcinogenesis model, with ten weekly injections of carcinogen, has the properties of a multistep process. The early peak in ODC might be associated with the early carcinogenesis (initiation) phase(s), and a subsequent second increase in ODC might be associated with late carcinogenesis (post-initiation or promotion) phase (s). These results strengthen the utility of the rat AOM colonic carcinogenesis model for further studies of the role of ODC and polyamine metabolism in neoplastic transformation.

Animals↗