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Biomedical subjects

N Wang

Publications and source records attributed to N Wang.

At least 415 records · Page 23Linked to original sources
PubMed1992

[Effects of dehydroepiandrosterone sulfate on the uterus and estrogen receptors in rats].

Dehydroepiandrosterone sulfate (DHA-S) at dosages of 50, 100 and 200 mg/kg s.c. for 3 days was shown to have obvious promotive effects on the growth of the uterus in immature rats. However, DHA-S given to ovariectomized rats at 40 and 100 mg/kg for 5 days was found to have no effect on the uterus. Incubation of granulosa cells for 3 h with DHA-S caused a significant increase in estradiol secretion. Even though DHA-S was found to increase uterine estrogen receptor concentration, this compound was shown to have no affinity for the estrogen receptor. It appears that the effects of DHA-S resulted mainly from the activity of its metabolite--estrogen.

Animals↗
PubMed1992

[A preliminary survey on Zhuang nationality medicinal crops at traditional herbs market of Jingxi County in Guangxi Zhuang Autonomous Region].

This paper reports an investigation and study on the Zhuang nationality medicinal crops available on the traditional herbs market in Jingxi county of Guangxi Zhuang Autonomous Region. There are 380 species belonging to 129 families and 322 genus, among which notably Embelia parviflora, Malus doumeri, Panax notoginseng, Polygala fallax, etc. This study may serve as a reference for exploitation and utilization of the Zhuang nationality medicinal herbs resources.

China↗
PubMed1992

Optimal delivery of cardioplegic solution for "redo" operations.

Increasing experience suggests that retrograde cardioplegia offers several benefits during cardiac reoperations. However, the need for dissection to allow caval snares for open coronary sinus intubation or to palpate the atrioventricular groove for transatrial coronary sinus intubation may disturb diseased vein grafts or require more dissection than necessary. Although antegrade-retrograde techniques can be used, antegrade cardioplegia risks atheromatous embolization from old vein grafts. To optimize delivery of cardioplegic solution, we designed and used "no touch" transatrial intubation of the coronary sinus for retrograde delivery of cardioplegic solution in 63 consecutive patients aged 20 to 87 years (mean 68 years) undergoing 36 redo coronary bypass operations, 7 combined redo coronary bypass/valve replacements, 6 redo aortic valve repairs/replacements, 6 redo mitral valve repairs/replacements, 4 redo double valve repairs/replacements, 2 redo triple valve repairs/replacements, and 2 redo composite aortic valve and arch replacements. "No touch" coronary sinus cannulation was achieved by minimally dissecting the aorta and high right atrium enough for two purse-string sutures. No attempt was made to dissect the junction of the inferior vena cava and atrioventricular groove if old vein grafts were present. The distal pressure line of the Gundry DLP RCSP retrograde cardioplegia cannula (DPL, Inc., Grand Rapids, Mich.) was connected to a transducer, flushed, and then introduced into the right atrium. The pressure tracing thus obtained was observed while the catheter was advanced, using its curved stylet, "blindly" without touching the heart, through the right atrium into the coronary sinus until a coronary sinus waveform was obtained (similar to floating a thermodilution catheter). The catheter's distal balloon was then inflated to occlude the coronary sinus momentarily. A rise in sinus pressure confirmed placement. If pressure did not rise, the cannula was usually in the right ventricle and was repositioned. All coronary sinuses were successfully intubated blindly. Bypass was then instituted, the aorta crossclamped, and the proximal aorta vented. Old vein grafts were cut at the aorta before retrograde cardioplegia was begun; atheromatous material was routinely flushed retrogradely from vein grafts. Only after arrest were hearts dissected as needed. Antegrade cardioplegia was not used. There were two (3%) deaths, both from hospital-acquired pneumonia, no perioperative myocardial infarctions, and no episodes of heart block. Inotropic agents were used in six of 63 patients (10%). We conclude that "no touch" transatrial retrograde cardioplegia offers optimal, simplified myocardial protection for cardiac reoperations, permits arrest of the heart before cardiac manipulations, and expands the use of retrograde cardioplegia by obviating cardiac dissection.

Aged↗
PubMed1991

Tubulin-G protein interactions involve microtubule polymerization domains.

It has been suggested that elements of the cytoskeleton contribute to the signal transduction process and that they do so in association with one or more members of the signal-transducing G protein family. Relatively high-affinity binding between dimeric tubulin and the alpha subunits of Gs and Gi1 has also been reported. Tubulin molecules, which exist in solution as alpha beta dimers, have binding domains for microtubule-associated proteins as well as for other tubulin dimers. This study represents an attempt to ascertain whether the association between G proteins and tubulin occurs at one of these sites. Removal of the binding site for MAP2 and tau from tubulin by subtilisin proteolysis did not influence the association of tubulin with G protein, as demonstrated in overlay studies with [125I]tubulin. A functional consequence of that association, the stable inhibition of synaptic membrane adenylyl cyclase, was also unaffected by subtilisin treatment of tubulin. However, ring structures formed from subtilisin-treated tubulin were incapable of effecting such inhibition. Stable G protein-tubulin complexes were formed, and these were separated from free tubulin by Octyl-Sepharose chromatography. Using this methodology, it was demonstrated that assembled microtubules bound G protein quite weakly compared with tubulin dimers. The alpha subunit of Gi1 and, to a lesser extent, that of Go were demonstrated to inhibit microtubule polymerization. In aggregate, these data suggest that dimeric tubulin binds to the alpha subunits of G protein at the sites where it binds to other tubulin dimers during microtubule polymerization. Interaction with signal-transducing G proteins, thus, might represent a role for tubulin dimers which is independent of microtubule formation.

Affinity Labels↗
PubMed1991

Differential evolution in chromosomal composition during multiple cycles of subcutaneous and intravenous metastasis.

It has been proven that multiple cycles of metastasis can improve the metastatic potential and homing specificity of a tumor cell population. In the present study, verification of genetic alterations during changes in metastatic behavior was done by analyzing the chromosome composition of a methylcholanthrene induced murine fibrosarcoma, 3AM during multiple cycles of subcutaneous (SC) and intravenous (IV) metastasis. After 10 cycles of SC metastasis, a cell type, 7B, with a small t(19;19)(A;A) metacentric marker chromosome was enriched from 4% in the original population to 90% in FIOR. However, when the tumor cells were injected IV rather than SC, no enrichment of the 7B cell type was observed. Instead, a cell type AX with a large t(14;19)(E5;A) acrocentric marker chromosome was enriched from 1% in the parental population to 76% in F1OIV after 10 cycles of IV metastasis. The polyploid dominant FIOIV was found to be extremely high in IV metastasis (411 foci/lung) but low in SC metastasis (48 foci/lung). The diploid dominant FIOR appears to be high in both SC (163 foci/lung) and IV (301 foci/lung) metastasis. The data obtained suggest that metastasis will lead to the selection of specific preexisting cell types, and the type of cell selected will depend on the route of metastasis. Furthermore, during metastasis, new cell types may also be produced de novo through chromosomal structural and numerical aberrations.

Animals↗
PubMed1991

Energy levels and probe placement in contact transscleral semiconductor diode laser cyclophotocoagulation in human cadaver eyes.

We investigated the effects of semiconductor diode laser contact transscleral cyclophotocoagulation in human cadaver eyes by gross examination, light microscopy, and scanning electron microscopy to determine optimum clinical treatment parameters. Irradiation was performed using a continuous-wave semiconductor diode laser with a fiber-optic probe. At 1.0 to 1.25 mm posterior to the limbus, spots were centered on the pars plicata by gross examination. Exposures of less than 2 J produced no visible damage. A 2- to 3-J exposure produced mild whitening of the ciliary processes, while 4- to 5-J exposures created more intense whitening of the pars plicata. Energies higher than 5 J frequently produced explosive tissue damage. Light microscopy of tissue treated with 1.8 to 6 J at 1.0 to 1.25 mm posterior to the limbus revealed coagulation necrosis of the nonpigmented and pigmented epithelium, with evidence of thermal coagulation of the ciliary stroma and stromal vasculature. Coagulation necrosis was more intense with longer exposure times. We found the optimum parameters for contact transscleral diode laser cyclophotocoagulation in cadaver eyes to be 3 to 4.5 J of energy delivered with the anterior edge of the probe 1.0 to 1.25 mm posterior to the limbus.

Ciliary Body↗
PubMed1991

An improved Hedley method for preparation of paraffin-embedded tissues for flow cytometric analysis of ploidy and S-phase.

A modification of the Hedley-method for flow cytometric DNA analysis of paraffin-embedded tissues is presented. Dewaxed and dehydrated tissue from paraffin blocks was incubated with subtilisin Carlsberg (pronase, Sigma protease XXIV) and then stained directly without washing and centrifugation. The loss of material was minimized, which was advantageous, for example, for the analysis of core-biopsies, and all measured samples showed extremely low frequencies of clumped cell nuclei. This made is easier to detect polyploid nuclei and even rare nuclei of high ploidy could be identified. S-phase analyses were more precise, since the background originating from clumped debris particles was very low. The improved method was applied to the estimation of frequencies of high-polyploid nuclei found in various diploid, tetraploid, and aneuploid human myosarcomas of the uterus.

Biopsy↗
PubMed1991

Pressure profiles show features essential to aerodynamic valving in geese.

Inspiratory airflow in the avian lung completely bypasses the most cranial secondary bronchi (the ventrobronchi), and instead enters bronchi arising more caudally (the dorsobronchi). Dotterweich (1936) proposed that 'aerodynamic valves' prevented entry into the ventrobronchi. We have recently provided evidence that inspiratory aerodynamic valving in avian lungs depends on convective inertia in the primary bronchus (Banzett et al., 1987). Theoretical and physical models (Butler et al., 1988; Wang et al., 1988) showed that convective inertia could effect valving, but the effectiveness of valving at resting flows was less than that observed in the bird. This leads us to hypothesize that a segment of the primary bronchus is constricted, accelerating the gas and enhancing the convective inertia. To test this hypothesis in the present work we measured pressures throughout the airways and air sacs in anesthetized, pump-ventilated geese at different flow rates and gas densities. Our data show: (1) there is a large pressure drop in the primary bronchus close to the ventrobronchial junction, indicating the presence of a constriction; (2) this pressure drop increases with gas density and flow; (3) the convective inertia at this site is more than 10 times downstream opposing pressures. We conclude that the primary bronchus just cranial to the first ventrobronchus forms a constriction which accelerates inspired air. Furthermore, we conclude that the convective inertia of gas leaving this segment is sufficient to achieve inspiratory valving.

Animals↗
PubMed1991

Prenatal diagnosis and subsequent management of a fetus with a 46XY r(4)(p15-q35) karyotype.

Fetal ultrasound examination at 29 weeks' gestation revealed a severely symmetrically growth-retarded fetus with microcephaly, hypertelorism, and hypoplastic genitalia with a two-vessel umbilical cord. G-banding analysis on amniotic cell cultures revealed a 46, XY,r(4)(p15-q35) karyotype in each of the colonies analyzed. This prenatal diagnosis, to our knowledge the first reported, assisted clinical management of this pregnancy.

Abnormalities, Multiple↗
PubMed1991

[First reported case of AIDS in China].

In this paper is reported the first case of acquired immunodeficiency syndrome (AIDS) in the Chinese continent. In the initial stage, the patient (male) experienced fever, malaise and headache in April, 1990, and then developed repeated pulmonary infection and insidious progressive subacute encephalitis. The diagnosis of AIDS was confirmed by serological test for positive HIV antibody by enzyme linked immunosorbent assays(ELISA), immunofluorescence assays (IFA) and Western blot test(WB), significant reducing of CD4 lymphocyte, reverse of CD4/CD8 ratio and isolation of HIV-1 from peripheral blood in August, 1990. The patient died on September 2nd, 1990. In autopsy, there were generalized atrophy of lymph tissues, lymphocytic depletion, diffusive inflammation and necroses of the cerebral and cerebella parenchyma caused by toxoplasma, multifocal Kaposi's sarcoma of the stomach, and small intestine and bronchopneumonia.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Positive inotropic effect of apomorphine on guinea pig myocardium is mediated by dopamine DA1 receptors.

Dopaminergic agonist apomorphine (Apo, 1-100 mumol.L-1) had a concentration-dependent positive inotropic effect on guinea pig left atria. This effect was not changed obviously when the influences of sympathetic and parasympathetic nerves were eliminated by reserpine and atropine, respectively. Apo had little inotropic action on guinea pig papillary muscles. The time course of positive inotropic effect of Apo was different from that of isoprenaline and phenylephrine. Apo influenced the isometric contraction curves in a different way from isoprenaline. Dopaminergic antagonist haloperidol antagonized the positive inotropic effect of Apo. This effect was also competitively antagonized by dopamine DA1 antagonist SCH 23390. While dopamine DA2 antagonist domperidone, beta-adrenergic antagonist propranolol and alpha-adrenergic antagonist phentolamine did not obviously influence the effect of Apo. We concluded that the positive inotropic effect of Apo was mediated by postsynaptic dopamine DA1 receptors in guinea pig left atria.

Animals↗
PubMed1991

[Genital mycoplasma colonization in the female genital tract].

Cervical or vaginal specimens obtained from 1,178 females at different physiologic periods of life were cultured for ureaplasma urealyticum and Mycoplasma hominis. Low recovery rates of U. urealyticum were obtained in the neonates (20/72, 27.8%) and puerperal (22/83, 26.5%) and postmenopausal (21/70, 30.0%) women. The highest incidence (114/157, 72.6%) was observed in pregnant women. It is suggested that the colonization of genital mycoplasma is associated with the hormonal status of the women.

Adult↗
PubMed1991

[Frequency of seroreactors to Legionella among the patients with pulmonary infections].

A prospective study was conducted with patients with pulmonary infections who were consecutively admitted to the three community hospitals in Benghu from July 1986 to May 1987, and to the children's hospital in Nanjing from September 1986 to January 1987. Antibodies to Lpi-8, Lm, Ld, and Lg were measured by the micro-agglutination test. During the study period, 150 adult patients (100 pairs sera) and 212 control healthy people and 110 pairs sera of childhood patients and 173 children without respiratory tract infections were investigated. The diagnosis of legionellosis was based on seroconversion (fourfold rise in titer to greater than 1:32 or static titer of greater than 1:32) and clinical and radiographic features of legionnaires' disease. About 11% legionella infection in hospitalized adult patients with pulmonary infections, and about 5.45% in children with atypical pneumonias.

Adolescent↗
PubMed1991

Localization of collagen types I and IV mRNAs in human optic nerve head by in situ hybridization.

Using in situ hybridization, individual cells expressing mRNAs for collagen types I and IV were localized in fixed-tissue sections of adult and fetal human optic nerve heads. Astroglial cells lining the cribriform plates and cells inside the cribriform plates of the lamina cribrosa had mRNA for collagen type IV. Cells in the glial columns, pial septa, and vascular wall also contained mRNA collagen type IV. Collagen type I mRNA was expressed by cells of the cribriform plates of the lamina cribrosa of adults. Few cells in the glial columns, pial septa, and blood vessels had mRNA for collagen type I. Scleral fibroblasts contained mRNA for collagen type I. These results indicated that the expression of mRNA for both collagen types I and IV paralleled the localization of these extracellular matrix proteins in the optic nerve head and suggested that both collagen types were synthesized in this tissue throughout life.

Adolescent↗