Search PubMed⌕ Search

Biomedical subjects

Y K Wu

Publications and source records attributed to Y K Wu.

At least 37 records · Page 2Linked to original sources
PubMed1994

Characterization of extractable species from poly(etherurethane urea) (PEUU) elastomers.

Methanol extracts of four poly(etherurethane urea) (PEUU) materials were analyzed using Gel Permeation Chromatography (GPC). The additives in the materials were Santowhite powder at 1 wt% and Methacrol 2138 F at 5 wt% loading levels. One-to-two wt% of the original PEUU films was extractable with methanol. The extractables consisted of a low molecular weight (Mw) PEUU polymer, an MDI-rich oligomer, the additives Santowhite (SW) powder and Methacrol 2138 F, and aniline. The low Mw PEUU polymer had a Mw of 12,000 relative to polystyrene, and the MDI-rich oligomer had a Mw of 1000 relative to polystyrene. Quantitation of all extracted species was achieved using GPC; the use of dual-detectors on the GPC made it possible to determine the soft-to-hard composition of the PEUU extracts as a function of molecular weight.

Amines↗
PubMed1994

[Traditional Chinese medicine and Western medicine treatment for severe intractable head injury].

38 cases of severe intractable head injuries were treated by TCM-WM treatment, the survival rate was 68.4%, which was difficult or ineffective for Western medicine treatment. The author lay emphasis on taking the following measures: (1) Place nasal feeding tube in the nose as early as possible; (2) Take Zenye Tang and Shengmai Yin as chief prescription for nourishing Yin and replenishing Qi; (3) Take large dose of citicoline, Angong Niuhuang Wan and Xuefu Zhuyu Tang to promote resuscitation; (4) When pulmonary infection was serious and antibiotic ineffective, Shashen Maidong Tang and Ditan Tang etc. could be used.

Adolescent↗
PubMed1994

Gastroduodenal intussusception due to Peutz-Jeghers syndrome. A case report.

An 18-year-old Chinese male was admitted to our hospital with recurrent abdominal pain, abdominal distension and intermittent non-bilious vomiting of about 2 months standing. A mildly tender mass measuring about 6 x 7 cm was present in the right upper quadrant area, and an abdominal computed tomography scan with enhancement showed a clearly encapsulated mass occupying the right side of the upper intra-abdominal area. Endoscopy revealed two huge cauliflower-like polyps and one small polyp in the stomach, and the biopsy specimens showed hyperplastic polyps. Moreover, multiple pigmentation of the buccal mucosa was also noted. The intra-abdominal mass was found to be a gastroduodenal intussusception following laparotomy. Gastroduodenal intussusception occurring secondarily to Peutz-Jegher syndrome, is a rarely documented condition. Only one case has been reported in Japan during the previous years. We report on another case, and review the literature.

Adolescent↗
PubMed1993

Metabolic fuel mixtures and diabetic embryopathy.

The incidence of congenital anomalies remains the major cause of morbidity and mortality among the offspring of diabetic women. Animal and human studies indicate that these malformations occur early in pregnancy and are influenced by the abnormal maternal metabolic milieu. This article reviews the recent advances in understanding the pathogenesis of diabetic embryopathy. A possible pathway to explain the various diabetic-related fuel aberration is presented.

Animals↗
PubMed1992

Synthesis of a potential bifunctional mimic of transaminases.

As a potential bifunctional mimic of transaminases 3,7-dimethyl-10-[3-(4- aminomethyl-5-hydroxy-6-methyl-3-pyridyl)propyl]-3,7,10- triazatricyclo[3.3.3.0(1,5)] undecane (I) has been synthesized by attaching 3,7-dimethyl-3,7,10-triazatricyclo [3.3.3.0(1,5)]undecane (II) to a pyridoxamine nucleus via an all-carbon chain. The chain length between the pyridine ring and II is restricted to three atom units so that the possibility for II to act bifunctionally during the transamination is maximized. In its protonated form, the nitrogen closest to the pyridine ring cannot deliver the proton intramolecularly to the alpha-carbon of the developing amino acid. To make the synthetic route generally applicable, introduction of the side-arm base is arranged at a later stage of the synthesis so that different di- or poly-amines can easily be used in place of II to prepare other target molecules that might possess bifunctional catalytic activity. This arrangement also greatly reduces the polarity and water-solubility of the intermediates and the purification of these compounds thus becomes much easier. The method of introducing the amino functionality at the C-4 methylene group described herein provides an alternative to that currently in use (reduction of oximes).

Aza Compounds↗
PubMed1990

A monokine stimulates prostaglandin-E2 production by human amnion.

The studies reported in this communication were designed to test the hypothesis that products of mononuclear cells are capable of stimulating prostaglandin E2 production by human amnion. Conditioned media obtained from peripheral blood mononuclear cells were incubated with amnion cells in primary culture. A dose dependent increase in PGE2 biosynthesis was observed in response to increasing amounts of the conditioned media. These observations suggest that mononuclear cells produce a factor(s) capable of stimulating prostaglandin production by amnion cells. The signal responsible for the increased biosynthesis of prostaglandins by human amnion associated with parturition in the setting of intraamniotic infection may be of host origin.

Amnion↗
PubMed1990

Cardiovascular community control programs in Beijing.

Cardiovascular community control program in Beijing started in 1969. In the past 20 years, eleven such programs had been established, covering a total population of 750,000. For those programs that have been operating for over 5-10 years, a marked drop in the mortality and morbidity rates of hypertension, stroke and acute myocardial infarction has been observed. It is proposed that this type of community control program should be further expanded in the next ten years so as to materialize the WHO goal of "Health for all by 2000".

Cerebrovascular Disorders↗
PubMed1990

Regulation of potassium and magnesium effluxes by external magnesium in barnacle muscle fibres.

Fluxes and flux rate constants for potassium and magnesium were measured as a function of ambient magnesium concentration in giant muscle fibres from the acorn barnacle. Experiments were carried out in the absence of both external Na and Ca (to prevent possible effects of these ions), and fibres were depleted of internal Na and Ca by soaking in Na- and Ca-free solution before each experiment. K efflux was biphasic with respect to increases in external Mg concentration [( Mg+2]0). K efflux approximately doubled (from about 63 to 130 pmol/cm2.s) when [Mg+2]0 was increased from 2 to 5 mM; K efflux remained elevated in Mg up to 60 mM. However, at [Mg+2]0 = 120 mM, the stimulatory effect of external Mg vanished, and at 357 mM it was replaced by an inhibitory effect. Mg efflux was also biphasic with respect to [Mg+2]0, and this efflux was matched at low to moderate [Mg+2]0 by Mg influx of comparable magnitude. This study suggests the possible existence of a Mg transport system that can serve variously as a Na/Mg or a Mg/Mg exchanger that may require the participation of K ions for its operation.

Animals↗
PubMed1990

Amniotic fluid interleukin-1 in spontaneous labor at term.

The regulatory signals responsible for the increased biosynthesis of prostaglandins during parturition have not been established. Interleukin-1 (IL-1) is capable of stimulating prostaglandin production by intrauterine tissues and is an inflammation mediator. It has been postulated as a signal for the onset of labor in the setting of intrauterine infection. A study was designed to determine if spontaneous labor at term was associated with changes in IL-1 activity in amniotic fluid. Such fluid was retrieved from 41 women in labor and from 39 women who were not in labor at term. Immunodetectable IL-1 beta was present in 22 of the 41 women in labor but in only 8 of the 39 women without labor. IL-1-like bioactivity was not different between the two groups at a dilution of 1:4, but at dilutions of 1:12, 1:36 and 1:108, amniotic fluid from women in labor had significantly higher bioactivity than that from women not in labor. A significant correlation was found between the bioassay and immunoassay results. Our data show that inhibitors of IL-1 bioactivity are present in amniotic fluid and suggest that in a subset of laboring women at term, an inflammatory reaction may play a role in triggering the onset of parturition.

Amniotic Fluid↗
PubMed1989

Infection and labor. III. Interleukin-1: a signal for the onset of parturition.

The regulatory signals responsible for the increased biosynthesis of prostaglandins during parturition have not been established. Because interleukin-1 is capable of stimulating prostaglandin production by intrauterine tissues and is an inflammatory mediator, we propose that interleukin-1 may act as a signal for the onset of human labor in the setting of intrauterine infection. The purpose of these studies was to determine interleukin-1 activity in amniotic fluid and to establish its relationship with the onset of term and preterm labor. Amniotic fluid from 182 patients was assayed for interleukin-1 activity. Cell-associated interleukin-1 activity was detected in fluid obtained in the third trimester but not in fluid obtained in the second trimester of pregnancy, suggesting a maturational event in interleukin-1 production. The factor responsible for interleukin-1 activity had biochemical characteristics of interleukin-1 alpha (estimated molecular weight of 14 kilodaltons, isoelectric point = 4.9), and its activity was blocked with an anti-interleukin-1 alpha antisera. Women in spontaneous labor at term were likely to have fluid phase interleukin-1 activity in amniotic fluid than women who were not in labor at term. Preterm labor in the setting of intraamniotic infections was associated with significant interleukin-1 activity in amniotic fluid. This bioactivity was predominantly attributable to interleukin-1 beta. A strong correlation between interleukin-1 and amniotic fluid concentrations of prostaglandin E2 and prostaglandin F2 alpha was found in women in preterm labor. These findings support the hypothesis that interleukin-1 may play a role in the initiation of preterm labor associated with intraamniotic infection.

Amniotic Fluid↗
PubMed1989

Infection and labor. IV. Cachectin-tumor necrosis factor in the amniotic fluid of women with intraamniotic infection and preterm labor.

A growing body of evidence supports a causal link between subclinical intrauterine infection and preterm labor. The mechanisms responsible for the onset of parturition in this setting have not been elucidated. The conventional view has been that bacterial products increase prostaglandin biosynthesis by intrauterine tissues and this, in turn, leads to the onset of labor. An alternative or complementary mechanism is that microbial products activate the host monocyte-macrophage system and that cytokines released during this process signal the initiation of parturition by stimulating prostaglandin biosynthesis by intrauterine tissues. This study was conducted to determine if cachectin-tumor necrosis factor is present in the amniotic fluid of women with intraamniotic infection and whether this cytokine can alter the rate of prostaglandin biosynthesis by intrauterine tissues. Amniotic fluid from 54 women was assayed for tumor necrosis factor. Tumor necrosis factor was not detectable in the amniotic fluid of women without intraamniotic infection regardless of the presence or absence of term or preterm labor. On the other hand, the amniotic fluid of 11 of 15 women with preterm labor and intraamniotic infection had measurable tumor necrosis factor. This cytokine stimulated prostaglandin E2 biosynthesis by amnion cells in monolayer culture in a dose-dependent fashion. These data support the concept that macrophage activation is involved in the onset of human parturition in the setting of infection. We propose that the host (fetus and/or mother) signals the onset of parturition through the secretion of inflammatory cytokines released in response to bacterial invasion.

Amnion↗
PubMed1989

A potential role for epidermal growth factor/alpha-transforming growth factor in human parturition.

Epidermal growth factor (EGF)/alpha-transforming growth factor (alpha-TGF) concentrations were measured in amniotic fluid by radioreceptor assay in non-laboring and laboring patients at term. The median concentrations of EGF/alpha-TGF were 1.28 ng/ml and 5.0 ng/ml in non-laboring and laboring patients respectively (p less than 0.05, Wilcoxon test). EGF was then incubated with amnion cells in monolayer culture to ascertain the effect of this hormone on the release of prostaglandin E2. Experiments were carried out in quadruplicate in 11 separate primary amnion-cell cultures (EGF was used at 1 ng/ml and 5 ng/ml, respectively). An increased release of prostaglandin E2 into the media was found. The response was concentration-dependent (p less than 0.01). We suggest that there may be a role for EGF in the mechanism of human parturition.

Amniocentesis↗
PubMed1989

Amniotic fluid concentrations of prostaglandin F2 alpha, 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) and 11-deoxy-13,14-dihydro-15-keto-11, 16-cyclo-prostaglandin E2 (PGEM-LL) in preterm labor.

Although prostaglandins (PGs) are considered the key mediators of human parturition at term, there is a paucity of data regarding their participation in the mechanisms responsible for preterm labor. The purpose of this study was to establish if preterm labor is associated with changes in the amniotic fluid concentrations of prostaglandins. PGF2 alpha, 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) and 11-deoxy-13,14-dihydro-15-keto-11,16-cyclo-prostaglandin E2 (PGEM-ll) were measured by using specific and sensitive radioimmunoassays. Amniotic fluid was retrieved by transabdominal amniocentesis from 55 women with preterm labor and intact membranes. Patients were divided into three groups according to the response to tocolysis and the presence or absence of an intra-amniotic infection. Amniotic fluid concentrations of PGFM and PGEM-ll were significantly greater in women with preterm labor and intra-amniotic infection than in women without infection. In addition, patients unresponsive to tocolysis without intra-amniotic infection also had a significantly greater concentration of PGFM and PGEM-ll in amniotic fluid than those responsive to tocolysis. Amniotic fluid concentrations of PGF2 alpha were greater in women with intra-amniotic infection than in women without intra-amniotic infection. In the absence of intra-amniotic infection, no difference in amniotic fluid PGF2 alpha concentrations could be found between women who responded to tocolytic treatment and those who did not.

Amnion↗
PubMed1989

Amniotic fluid arachidonate lipoxygenase metabolites in preterm labor.

This study was conducted to determine if preterm labor with intact membranes is associated with changes in the amniotic fluid concentrations of arachidonate lipoxygenase metabolites. Amniotic fluid was obtained by transabdominal amniocentesis from 68 women with preterm labor. The patients were classified into three groups according to their response to tocolysis and their amniotic fluid culture results: Group 1 - women with a negative amniotic fluid culture who responded to tocolysis (n = 32); Group 2 - women with a negative culture, but who failed to respond to tocolysis (n = 22); and Group 3 - women with intraamniotic infection (n = 14). The following arachidonate lipoxygenase products were measured by radioimmunoassay: leukotriene B4 (LTB4); leukotriene C4 (LTC4); 12-hydroxyeicosatetraenoic acid (12-HETE); and 15-hydroxyeicosatetraenoic acid (15-HETE). The median concentrations of LTB4 were significantly different among the three study groups (26 pg/ml, 67 pg/ml and 885 pg/ml, respectively, p greater than 0.05). Amniotic fluid concentrations of 12-HETE and LTC4 did not vary among the three study groups. On the other hand, a significant difference in the distribution of amniotic fluid concentrations of 15-HETE was noted only between women with intraamniotic infection (Group 3) and women responding to tocolysis (Group 1). These results indicate that the arachidonate lipoxygenase pathway is activated during the course of preterm labor. Selective changes in the concentrations of the assayed metabolites were noted. Amniotic fluid LTB4 concentrations may be a marker for the patient with preterm labor who is unresponsive to tocolysis.

Amniocentesis↗
PubMed1989

Bacterial endotoxin and tumor necrosis factor stimulate prostaglandin production by human decidua.

The purpose of these studies was to determine the effect of bacterial endotoxin and tumor necrosis factor (TNF) on prostaglandin (PG) secretion by human decidua. Decidual explants were established from women undergoing elective cesarean sections before the onset of labor. Escherichia Coli endotoxin and purified human recombinant TNF (rh TNF) were incubated with decidual explants. PGF2 alpha and PGE2 biosynthesis was measured by radioimmunoassay. A significant increase in the release of all PGs into the media occurred in response to LPS and TNF. In the setting of an extraamniotic infection, bacterial and host secretory products (TNF) could trigger the onset of labor, activating the decidua to produce PGs.

Decidua↗
PubMed1989

Amniotic fluid concentration of 5-hydroxyeicosatetraenoic acid is increased in human parturition at term.

5-hydroxyeicosatetraenoic acid (5-HETE) is an arachidonate lipoxygenase product capable of stimulating uterine contractility in a dose-dependent manner in vitro. The purpose of this study was to determine if spontaneous human labor at term is associated with changes in the concentration of this metabolite in amniotic fluid. Fluid was retrieved from 36 women not in labor and from 30 women in active labor at term. 5-HETE was determined by radioimmunoassay. The median amniotic fluid concentration of 5-HETE of women in labor was significantly greater than that of women not in labor (3538 pg/ml vs. 1977 pg/ml, respectively; p = 0.05). This observation is consistent with activation of the lipoxygenase pathway of arachidonic acid metabolism during spontaneous human parturition at term.

Amniotic Fluid↗
PubMed1989

Human decidua: a source of interleukin-1.

These studies were conducted to determine whether human decidua produces interleukin-1 in response to bacterial endotoxin. Explants of human decidua were incubated with and without Escherichia coli endotoxin for 20 hours. When tested for interleukin-1-like activity with the D10.G4.1 T-cell bioassay, supernatants from endotoxin-stimulated decidua contained significantly more interleukin-1 activity than did supernatants from unstimulated decidua. This activity could not be attributed to interleukin-2, as determined in the CTLL/2 assay for interleukin-2. Interleukin-1-like activity was due to interleukin-1, as demonstrated by the blockade of this bioactivity with antibodies against interleukin-1: interleukin-1 alpha and interleukin-1 beta. Antibodies against interleukin-1 alpha blocked the activity in five of six cases. In one instance, the bioactivity could be attributed to a mixture of interleukin-1 alpha and interleukin-1 beta. These data demonstrate that human decidua can produce interleukin-1 in response to bacterial endotoxin.

Antibodies↗