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Biomedical subjects

W Q Huang

Publications and source records attributed to W Q Huang.

36 records · Page 2Linked to original sources
PubMed1997

Central ANG II receptor involved in carotid sinus reflex resetting in chronically stressed rats.

The performance of carotid sinus baroreceptor reflex (CSR) was characterized in chronically stressed rats by changing intracarotid sinus pressure (ISP) and constructing ISP-MAP (mean arterial pressure) relationship curve. The role of central angiotensin II (ANG II) receptors in the changes of CSR performance induced by chronic stress was determined. Rats were subjected to foot-shock stress for two weeks. The carotid sinus was isolated from the systemic circulation and the ISP changed in a stepwise manner. The results showed that in chronically stressed rats, ISP-MAP relationship curve shifted upward, the set point was significantly higher than that obtained from the unstressed group, and the reflex gain and the MAP range were significantly smaller than those in unstressed rats. After intracerebroventricular injection of saralasin (20 ng), MAP range was augmented and the set point decreased significantly. Injection of vehicle did not lead any significant differences between the parameters of the reflex measured before or after injection in either the stressed or the unstressed rats. Furthermore, administration of ANG II (10 microg) induced a significant increase in the set point and decrease in the reflex gain in the unstressed rats. The responses of CSR to ANG II were completely blocked by pretreatment of saralasin. These findings suggest that chronic stress could induce the decreased CSR function in the normotensives and central ANG II receptors involved in the resetting of CSR in the chronically stressed rats.

Angiotensin II↗
PubMed1997

[Effect of microinjection of CRH into rat central nucleus of amygdala on blood pressure and its central mechanism].

The effect of microinjection of corticotropin releasing hormone (CRH) into the central nucleus of amygdala (CeA) on blood pressure was examined in Wistar rats anaesthetized with pentobarbital sodium. The results were as follows: (1) Microinjection of CRH 100, 500 ng into the CeA produced a dose-dependent increase in blood pressure. The response occurred 5 min after injection and lasted for at least 1 h. (2) The response could be blocked by injection of CRH receptor antagonist alpha-helical CRH9-41 into CeA. (3) Lateral ventricle injection of naloxone could also attenuate the pressor response of CRH. (4) After injection of alpha-helical CRH9-41 into nucleus of solitary tract, the pressor response of CRH was diminished. The results suggest that the pressor effect induced by microinjection of CRH into the CeA might be partly mediated through opioid system via a descending pathway from CeA to NTS.

Amygdala↗
PubMed1994

Effects of histamine on electrophysiological properties and triggered activity in guinea pig papillary muscles.

The effects of histamine on action potentials (APs) and on early afterdepolarizations (EADs) were studied with standard microelectrode and computer in guinea pig papillary muscles. Experiments offer evidence that histamine (6.0 mumol/l) results in a significant diminution in action potential duration at 50% repolarization (APD50) and 90% repolarization (APD90) (data taken from no abnormal automaticity and oscillatory potential cells, 10 out of 19 preparations). Particularly, histamine can induce EADs (about 58%), oscillatory potentials and triggered activity. EADs frequently occur at low stimulation rates of 0.2-1.0 Hz and with prolongation of the action potential duration. EAD-induced triggered activity may exhibit fast spontaneous APs. Cimetidine (10 mumol/l, n = 6), an H2-receptor antagonist, antagonizes the effects of histamine. In the presence of cimetidine no EADs are observed by perfusing histamine. An H1-receptor antagonist, chlorpheniramine (10 mumol/l, n = 9), has no effect on the alterations of APs induced by histamine in ventricular myocardium. The results suggest that the mechanisms of histamine-induced shortness of AP duration, EADs and triggered activity may be related to the H2 receptor-mediated enhancement of the slow inward calcium current.

Action Potentials↗
PubMed1993

Oral immunization with influenza virus in biodegradable microspheres.

Polymeric microspheres were evaluated as an oral antigen delivery system for immunization with influenza virus. The immune responses obtained were compared after either oral or systemic immunization of BALB/c mice using purified, formalin-inactivated influenza virus type A/H3N2, either encapsulated in biodegradable and biocompatible microspheres or free in solution. The immunogenicity of formalin-treated influenza vaccine was preserved during the microencapsulation process, and the microencapsulated antigen induced protective immune responses after systemic immunization that were equal to or higher than those induced by conventional vaccine. When administered orally to primed animals, microencapsulated antigen induced levels of anti-influenza antibodies in saliva that were higher than and in serum that were comparable to those obtained by systemic immunization. Furthermore, oral booster immunization provided virtually complete protection of animals challenged with live virus.

Administration, Oral↗
PubMed1992

[Role of the central alpha-receptors in the modulation of carotid sinus reflex of rats].

To investigate the effects of the central alpha-receptors on the carotid sinus reflex, phenoxybenzamine (PBZ, 2 micrograms/20 microliters) or yohimbine (Y, 2 micrograms/20 microliters) was injected into the lateral cerebral ventricle (LCV) and intracarotid sinus pressure (ISP)-mean arterial pressure (MAP) relationship curve was constructed and fitted by a Logistic function. The results were as follows: (1) After injection of PBZ into LCV, the ISP-MAP relationship curve shifted upward at a higher ISP level with decreased peak slope and MAP range while the ISP-slope curve shifted downward. (2) After injection of Y into LCV, the ISP-MAP relationship curve shifted upward at a higher ISP level with decreased peak slope and MAP range and increased threshold. The ISP-slope curve shifted downward significantly at 10.64, 15.96 kPa. The peak slope and MAP range of Y group decreased significantly as compared with that of the PBZ group. These results indicated that after blockage of central alpha-receptors the sensitivity of the sinus reflex decreased significantly, and the blockage action of alpha 2-receptor is greater than that of alpha 1-receptor.

Animals↗
PubMed1992

[Effect of the central noradrenergic system on carotid sinus reflex in rats].

In order to study the effect of central noradrenergic system on the regulation of mean arterial pressure (MAP) by intracarotid sinus pressure (ISP), ISP-MAP relationship curves were constructed using isolated carotid sinus under the condition of injection of 6-OHDA (200 micrograms) into lateral ventricle or cauterization of locus coeruleus (LC) and compared with that obtained under the condition of control. All ISP-MAP curves can be fitted by a logistic functional plot whose characteristics can be defined by two parameters, i.e. coordinates of the inversion point of the slope of the curve and the MAP range related to the rate of change of slope factor with which carotid sinus pressure exerts its control. The results were as follows: After injection of 6-OHDA, the rate of change of the slope of the ISP-MAP curve is considerably slower than that of the normal control, thus showing a much compressed range of MAP by ISP, while the abscissa (i.e. position of ISP) of the slope inversion point of the curve shows practically no change. In comparison with the control, cauterization of LC causes a similar but less striking change of ISP-MAP curve than that of 6-OHDA injection experiment. All such differences were illustrated in Fig. 3. The above results indicated that the central noradrenergic system facilitates carotid sinus reflex and LC plays a dominant role.

Adrenergic Fibers↗
PubMed1991

Neuropeptides and neurotransmitters in human placental villi.

The human placenta contains many kinds of bioactive substances which are more or less similar to those from the hypothalamic-pituitary-gonadal axis. Most of the studies were carried out mainly with term placenta. The present study, therefore, was attempted to identify, quantify and characterize these substances in the human placenta at the early pregnancy. Using the RIA, immunohistochemistry, HPLC, tissue culture and intrauterine injection methods, we have found that: (1) many kinds of neuropeptides and neurotransmitters are present in the placental villi; (2) LH-RH, NT and SRIF positive immunoreactive granules are localized in the cytotrophoblast and those of beta-EP, 5-HT positive granules in the syncytiotrophoblast; (3) synthetic LH-RH and dynorphin (Dyn) stimulate the hCG secretion of the early placental villi in vitro, and (4) the antisera of LH-RH, NT, Dyn and NE antagonist-alpha-MPT significantly reduced the number of blastocyst implantations in the early pregnant rat. These results indicate that in the human placenta there possibly exists a self-regulation mechanism for the synthesis and secretion of placental hormones and neurotransmitters. Therefore, the human placenta can be regarded as a neuroendocrine organ.

Animals↗
PubMed1991

Evidence for atrial natriuretic peptide-(5-28) production by macrophages of the rat spleen: an immunochemical and nonradioactive in situ hybridization approach.

Atrial natriuretic peptide (ANP), a 28-amino acid peptide, is produced and secreted by cardiac atriocytes to modulate cardiovascular functions. Recently, biologically active receptors for ANP have been demonstrated in the spleen; we report here the production of ANP-(5-28) and its 15-kDa (K) mol wt (Mr) presumptive precursors by macrophages of rat splenic tissues. Splenic, hypothalamic, and heart tissues were collected from adult male Sprague-Dawley rats and acid extracted for ANP assay. The splenic content of immunoreactive (ir) ANP (mean +/- SEM, 428 +/- 68 pg/tissue; n = 7) was approximately a fifth of that found in the hypothalamus and about 4 orders of magnitude lower than that in the heart of the same animals. The Sephadex G-50 column profile of splenic extracts revealed two immunoreactive peaks; the major peak eluted in positions consistent with 15K Mr, while a minor peak coeluted with synthetic rat ANP-(1-28) of 3K Mr. HPLC analysis of the 3K Mr species showed a single peak of immunoreactivity, which eluted with a retention time similar to that of ANP-(5-28). In rat splenic sections, immunoperoxidase localization of ir-ANP revealed positive cells sparsely distributed in marginal sinuses and the red pulp of the tissue; employing a double staining technique, S22, a surface marker for macrophages, was colocalized on the same splenocytes. Furthermore, colorimetric in situ hybridization with antisense oligonucleotide probes labeled with digoxigenin, identified specific signals for pro-ANP mRNA in splenocytes of tissue sections. In monolayer cultures of vehicle-treated splenocytes, approximately 87% of the adherent cells stained positive for S22; this marker was colocalized with ir-ANP in approximately 15% of the cells. Twenty-four-hour treatment with lipopolysaccharide (50 micrograms/ml), a bacterial endotoxin, tripled the proportion of adherent cells (32 +/- 4%; P less than 0.01) staining positive for ir-ANP over that in control cultures (mean +/- SEM, 11 +/- 3%; 10(4) cells/sample; n = 5). Furthermore, an equivalent dose of lipopolysaccharide, but not Concanavalin-A (50 micrograms/ml), quadrupled ir-ANP content compared to that in vehicle-treated cultures (less than 5 pg/well). Thus, our findings suggest that ANP-(5-28) is produced by a small population of splenic macrophages and raise the possibility that the peptide may play a signalling role at the tissue level.

Animals↗
PubMed1990

Differential effects of galactose-induced cataractogenesis on the soluble crystallins of rat lens.

Soluble lens crystallins from 6-10-week-old, galactose-fed, male Sprague-Dawley rats were analyzed by two-dimensional polyacrylamide gel electrophoresis at each of the five Sippel stages of cataractogenesis. Electrophoretograms were compared with similarly analyzed crystallins from comparably aged, chow-fed controls. Polypeptides were assigned to crystallin families and subfamilies on the basis of chromatographic fractionations with Sephadex G-200, superfine. Staining intensities of polypeptides from control lenses remained essentially unchanged throughout the experimental period, while those of the polypeptides from cataractous lenses showed non-uniform changes. Staining of the genomic gamma-crystallins increases up to at least stage 3; by stage 4, staining of gamma-chains, with perhaps those of gamma 5 and gamma 6 excepted, diminishes and in the total cataract, staining of all chains is further reduced. With possibly the addition of one chain, the total number of postsynthetically modified gamma-crystallins in cataractous lenses does not exceed that in the comparably aged normal lens. The genomic alpha- and beta-crystallin polypeptides are sustained close to normal levels up to stages 3 or 2, respectively, after which their gradually falling levels are accompanied by the generation of new species or elevated levels of existing post-translational species. An exception to this behavior is the rapid and total loss of beta B1a, a genomic subunit implicated in the aggregation of beta H-crystallins. Charge heterogeneity and variable pI displayed by beta B1a and other highly cationic beta- and gamma-crystallin polypeptides can be induced during isoelectric focusing and may be due to thiol group oxidation.

Animals↗
PubMed1988

Mutagenicity and carcinogenicity studies of homemade "rust-proof cutting fluid".

A homemade rust-proof cutting fluid (RPCF) used in China was tested for carcinogenicity by an in vivo chronic experiment and for mutagenicity by the Ames Salmonella microsomal assay. Undiluted and threefold water-diluted fluid were given as drinking water to groups of young adult Wistar rats for 2 years. The treatment induced 11/40 malignant tumors with 9/40 acinar adenocarcinomas of the pancreas in the high-dose group. Simultaneous administration of ascorbic acid dissolved in the undiluted fluid at 2 g acid per 1 g sodium nitrite resulted in 1/40 pancreatic carcinoma. The results of the Ames test showed that the technical RPCF was mutagenic to TA100 with or without metabolic activation. It was concluded that the homemade RPCF, which is comprised of sodium nitrite, triethanolamine, and polyethylene glycol, may form direct-acting mutagen(s) upon storage and form, in vivo, e.g., nitrosamines that caused acinar pancreatic carcinoma in Wistar rats. Simultaneous administration of ascorbic acid is suggested for the protection of workers exposed to the rust-proof cutting fluid.

Animals↗
PubMed1988

[Electron microscopy of 300 tumors in the nervous system].

The results of 300 nervous system tumors observed by electron microscopy are reported. Of them, 12% depended on electron microscopy for diagnosis; 14% was further classified and typed by electron microscopy; 59% could be diagnosed by either electron or light microscopy but the former played an important role in confirming the diagnosis by light microscopy; 10% still could not be diagnosed even by electron microscopy; 5% failed in diagnosis due to faulty technique. The results indicate that the electron microscope is a useful tool in diagnosis of the nervous system tumor, particularly, in those whose diagnosis is difficult by light microscopy and in classification and typing of the tumor. In this paper, the pathognomonic ultrastructural features are described.

Diagnosis, Differential↗