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Biomedical subjects

H Yang

Publications and source records attributed to H Yang.

At least 1,045 records · Page 58Linked to original sources
PubMedDate not supplied

Intracisternal injection of CRF antagonist blocks surgical stress-induced inhibition of gastric secretion in the rat.

The effects of intracisternal injection of CRF antagonist, alpha-CRF 9-41, on the inhibition of gastric acid secretion elicited by intracisternal injection of corticotropin-releasing factor (CRF) and stress were investigated in conscious pylorus-ligated rats. Intracisternal injection of the alpha-helical CRF 9-41 (50 micrograms) did not influence basal gastric secretion, but injected concomitantly with intracisternal CRF (5 micrograms), completely blocked CRF (5 micrograms)-induced inhibition of gastric secretory volume, acid concentration and output. Intracisternal injection of alpha-helical CRF 9-41 (3, 10, 50 micrograms) produced a dose-related reversal (0, 52 and 100%) of brain surgery-induced inhibition of gastric acid output. By contrast intravenous injection of CRF antagonist (50 micrograms) did not inhibit gastric hyposecretory response to brain surgery. These data suggest that endogenous CRF in the brain may mediate stress-induced gastric hyposecretion in the rat.

Animals↗
PubMedDate not supplied

A monoclonal antibody to somatostatin with potent in vivo immunoneutralizing activity.

The spleen from a Robertsonian mouse with high titer and affinity antiserum after being immunized with somatostatin-14 conjugated to keyhole limpet hemocyanin was fused with FOX-NY cells. Hybridomas were cloned by limiting dilution, subcloned, and ascites was produced from the highest affinity close in pristine-primed Balb/c mice. Ascites fluid contained approximately 20 mg/ml IgG and bound 50% of 1 fmol 125I-[Tyr1]-somatostatin at a final dilution of 1:10,000,000. Binding of this IgG1 antibody, CURE.S6, was inhibited by 50% at 40 pM concentrations of either somatostatin-14 or somatostatin-28, but was not inhibited by [D-Trp8 -somatostatin at 1000-fold higher concentrations. The antibody produced very intense specific immunohistochemical staining of somatostatin endocrine cells in the stomach and pancreas and of intestinal somatostatin neurons with extremely low background staining. Intravenous injection of 2 mg purified antibody in urethane-anesthetized rats resulted in 300-fold increase in plasma GH within 15 min. CURE.S6 is a high affinity monoclonal antibody directed at the biologically active somatostatin ring structure. This antibody is useful for in vivo immunoneutralization of exogenous and endogenous somatostatin in the rat and also is an excellent reagent for immunohistochemical localization of somatostatin.

Animals↗
PubMedDate not supplied

Capsaicin-sensitive vagal afferents contribute to gastric acid and vascular responses to intracisternal TRH analog.

Central injection of TRH or its stable analog, RX77368, produces a vagal cholinergic stimulation of gastric acid secretion, mucosal blood flow and motor function. In the present study, we have investigated the contribution of capsaicin-sensitive vagal afferent fibers to the gastric responses to intracisternal injection of RX77368. Gastric acid secretion, measured in acute gastric fistula rats anesthetized with urethane, in response to intracisternal injection of RX77368 (3-30 ng) was reduced by 21-65% by perineural pretreatment of the vagus nerves with capsaicin 10-20 days before experiments. The increase in gastric mucosal blood flow measured by hydrogen gas clearance induced by intracisternal injection of RX77368 (30 ng) was also reduced by 65% in capsaicin-pretreated rats. In contrast, increases in gastric motor function measured manometrically or release of gastric luminal serotonin in response to intracisternal injection of RX77368 (3-30 ng) were unaltered by capsaicin pretreatment. The mechanism by which vagal afferent fibers contribute to the secretory and blood flow responses to the stable TRH analog is unclear at present, but it is possible that the decrease in gastric mucosal blood flow by lesion of capsaicin-sensitive vagal afferents limits the secretory response.

Afferent Pathways↗
PubMedDate not supplied

Raman spectroscopic study of microcosmic photodamage of the space structure of DNA sensitized by Yangzhou haematoporphyrin derivative and Photofrin II.

After calf thymus DNA has been photodamaged by Yangzhou haematoporphyrin derivative (YHPD) or Photofrin II, the Raman characteristic frequencies and the intensities of the bands assigned to various groups of the components of DNA change considerably. As a result of damage, homogeneous B-form calf thymus DNA becomes a mixture containing: (1) modified B-form DNA, which is shorter than the original because of double-helical DNA scission; (2) single-stranded DNA due to the breakage of some H-bonds and the lack of some bases, etc.

Animals↗
PubMedDate not supplied

Combinatorial synthesis of heterocycles: solid-phase synthesis of 2-amino-4(1H)-quinazolinone derivatives.

A new solid-phase synthesis of various substituted 2-amino-4(1H)-quinazolinones from a resin bound amine component is described. The amine was readily converted to the corresponding polymer bound S-methylthiopseudourea. Condensation with different substituted isatoic anhydrides afforded 2-amino-4(1H)-quinazolinone derivatives. The method is amenable for combinatorial library generation.

Amines↗
PubMedDate not supplied

Combinatorial synthesis of heterocycles: solid-phase synthesis of 6-amino-2,4-dioxo-3,4-dihydro-1,3,5-triazine derivatives.

A new solid-phase synthesis of trisubstituted 6-amino-2,4-dioxo-3,4-dihydro-1,3,5-triazines from a resin-bound amine component is described. The amine was readily converted to the corresponding polymer-bound S-methylthiopseudourea, which upon reaction with secondary amines gave the disubstituted guanidines. Cyclization of the polymer-bound guanidines with chlorocarbonylisocyanate afforded the triazinediones. The third point of diversity was introduced by the Mitsunobu reaction. The method is amenable for iterative combinatorial library generation.

Amines↗
PubMedDate not supplied

Variation among cell types in the signaling pathways by which IGF-I stimulates specific cellular responses.

This review compares the signaling pathways leading to cellular responses (primarily proliferation and differentiation) of cells to the insulin-like growth factors (IGFs). Although some systems (such as myoblasts and adipocytes) clearly employ the Ras-Raf-Mitogen Activated Protein (MAP) kinase pathway in signaling for cell proliferation, others (such as MCF-7 mammary tumors and brain capillary cells) proliferate in response to signals mediated by phosphatidylinositol-3 kinase and p70 S6 kinase. Similarly, most of the systems surveyed use a phosphatidylinositol-3 kinase pathway in differentiating in response to IGFs, but others (such as SH-SY5Y neuroblastoma cells) differentiate in response to the MAP kinase pathway. Thus, it seems that there are no simple generalizations that can be used to forecast the signaling pathway that will be involved in any response to the IGFs.

Adipocytes↗
PubMedDate not supplied

New hope for infertility therapy: fabricating gametes from stem cells.

The field of reproductive and developmental biology has been revolutionized by recent advanced studies. These studies indicate that stem cells are capable of forming gametes in vivo and in vitro in both mouse and human. This has provided powerful tools for undertaking new types of reproductive studies, and particularly might provide new technology and novel approaches in assisted reproductive medicine.

Animals↗
PubMedDate not supplied

Citation analysis of five journals in andrology.

AIM: To find out features in literature demand by researchers in the field of andrology and to offer advice on literature utilization and journal management. METHODS: Five andrology journals indexed by Science Citation Index Expanded (SCI-E) (Andrologia, Archives of Andrology, Asian Journal of Andrology, International Journal of Andrology, and Journal of Andrology) were included in the study. Original articles, editorials, reviews, corrections and letters from these journals were analyzed with bibliometric method for document loading, citations, information absorbing ability, and geographical coverage. RESULTS: The average number of references in each paper was 28.78. The main type of references was periodicals (94.32%), while books and other sources accounted for only 5.68%. Average Price index was 30.14%. The number of references in the first ranking 10 periodicals cited by the five journals made up 34.53% of the total references cited. Geographically, the five journals covered 6 continents with 42 countries or regions. CONCLUSION: Andrology journals have a wide coverage of literatures, which are related to reproductive medicine, urology, endocrinology and biochemistry. References in andrology journals are mainly periodicals and are relatively old. US, China and Japan lead the world in andrology researches for the number of papers published.

Andrology↗
PubMedDate not supplied

Long-acting delivery microspheres of levo-norgestrol-poly(3-hydroxybutyrate): their preparation, characterization and contraceptive tests on mice.

The preparative technology for sustained release drug delivery microspheres of levo-norgestrol-poly(3-hydroxybutyrate) was optimized based on the in-liquid-drying method. The formation of the drug microspheres was confirmed with differential thermal analysis. The appearance, particle size and distribution, residual CHCl3, drug content, drug release characteristics in vitro, stability and anticonceptive effect on mice of the microspheres were all examined. The average particle size was 64 microm with over 90% of the microspheres being in the range of 28.7-85.8 microm. The residual CHCl3 was lower than 0.001%. The drug release behaviour in vitro could be described by the Higuchi equation and the drug release t1/2 was prolonged by 1.8 times, compared with the original drug LNG. The microspheres were stable for 3 months and showed significant sustained release and anticonceptive effect in mice, and lower toxicity compared with the original drug.

Animals↗
PubMedDate not supplied

Asian and Pacific Islander mortality differences in Hawaii.

In the United States, national health status data pertaining to Asian and Pacific Islander (API) Americans are rarely disaggregated. By aggregating API data, however, the poor health status of some API groups is often masked by the favorable health status of others. The purpose of this paper is two-fold: (1) to compare mortality rates of the five major ethnic groups in Hawaii (Caucasians, Chinese, Filipinos, Japanese, and Hawaiians) and (2) to explore methodological issues related to comparative studies of API health indicators. Standardized and age-specific mortality rates and 95 per cent confidence intervals for major causes of death were estimated for 1990 based on Hawaii vital records and population data. In general, death rates were highest for Hawaiians and lowest for Japanese and Chinese, illustrating the importance of API data disaggregation and suggesting that special attention be paid to improving the health of Hawaiians. Methodologically, the study demonstrated that, while some compromises in analysis are required, legitimate comparisons across API groups can be made if data sets are available.

Adolescent↗
PubMedDate not supplied

Nonphospholipid vesicles of Carboplatin for lung targeting.

Carboplatin (CPt) was incorporated into nonphospholipid vesicles (NPLV) by the method of membrane dispersion and its content determined spectrophotometrically. The particle size was between 2.0-10.0 microm with a mean value of 3.26 microm and a span of 0.55; and the drug content was 3.965 mg/ml. Dynamic dialysis was used for in vitro release of CPt and the results indicated that the drug release t(1/2) was increased eight times, compared with the original drug. These parameters had little change after lyophilization. When tested with mice, the body distribution parameters showed obviously lung targeting characteristics. The S-180 lung neoplasm models were established by intravenous cancer cells in mice and the number of pulmonary nodules examined for evaluation of the therapeutic efficacy. Antitumor effect was increased and differed significantly (p <.05) compared with the original drug of the same dose.

Animals↗
PubMedDate not supplied

Evolutionary and physiological variation in cardiac troponin C in relation to thermal strategies of fish.

Striated muscle contraction is initiated when troponin C (TnC) binds Ca(2+), which activates actinomyosin ATPase. We investigated (i) the variation between cardiac TnC (cTnC) primary structure within teleost fish and (ii) the pattern of TnC expression in response to temperature acclimation. There were few differences between rainbow trout (Oncorhynchus mykiss), yellowfin tuna (Thunnus albacares), yellow perch (Perca flavescens), goldfish (Carassius auratus), white sucker (Catostomus commersoni), and icefish (Chaenocephalus aceratus) in cTnC amino acid sequence. No variation existed in the regulatory Ca(2+)-binding site (site 2). The site 3 and 4 substitutions were limited to residues not directly involved in Ca(2+) coordination. Fish cTnC primary structure was highly conserved between species (93%-98%) and collectively divergent from the highly conserved sequence seen in birds and mammals. Northern blots and polymerase chain reaction showed that thermal acclimation of trout (3 degrees, 18 degrees C) did not alter the TnC isoform pattern. While cardiac and white muscle had the expected isoforms-cTnC and fast troponin C (fTnC), respectively-red muscle unexpectedly expressed primarily ftnC. Cold acclimation did not alter myofibrillar ATPase Ca(2+) sensitivity, but maximal velocity increased by 60%. We found no evidence that TnC variants, arising between species or in response to thermal acclimation, play a major role in mitigating the effects of temperature on contractility of the adult fish heart.

Adaptation, Physiological↗
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Genetic diversity present within the near-complete mtDNA genome of 17 breeds of indigenous Chinese pigs.

The genetic diversity present within the near-complete mitochondrial genome (15,982 bp) was determined from 17 indigenous Chinese pig breeds and 3 European breeds. Animals were selected from 17 Chinese breeds that reflect the large phenotypic diversity of Chinese pigs and represent each of the six breed types, which are grouped based on morphological characteristics. Analysis of nucleotide diversity confirmed a high level of divergence between animals of European versus Asian origin; however, much more limited variation was observed between the 17 indigenous Chinese breeds. Each had a unique haplotype, but the lowest pairwise sequence divergence was only 0.01 +/- 0.01%, observed between the Tongcheng and Yushan Black. Comparison of control region sequence diversity revealed the 17 Chinese breeds contain a lower average pairwise distance (0.61 +/- 0.19%) than a group of European commercial breeds (0.91 +/- 0.21%). The dendrogram constructed from the near-complete mtDNA sequences showed the Chinese sequences loosely clustering into two groups. Although some correspondence with geographic origin was present, notable differences between the dendrogram and the traditional pig breed grouping system were observed.

Animals↗