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Biomedical subjects

P Wan

Publications and source records attributed to P Wan.

15 recordsLinked to original sources
PubMed2002

Ethnic differences in ovulatory function in nulliparous women.

African-American women have a long-standing approximately 20% higher breast cancer incidence rate than USA White women under age 40 while rates among Latinas are lower than those of Whites. The reasons for this are not clear, however they may be due to ethnic differences in circulating oestradiol and progesterone levels. In a cross-sectional study, we investigated whether anovulation frequency and circulating serum oestradiol and/or progesterone levels vary among normally cycling nulliparous African-American (n=60), Latina (n=112) and non-Latina White (n=69) women. Blood and urine specimens were collected over two menstrual cycles among healthy 17- to 34-year-old women. Frequency of anovulation was greater among White women (nine out of 63, 14.3%) than African-American women (four out of 56, 7.1%) or Latina women (seven out of 102, 6.9%), although these differences were not statistically significant. African-American women had 9.9% (P=0.26) higher follicular phase oestradiol concentrations than Latina women and 17.4% (P=0.13) higher levels than White women. African-American women also had considerably higher levels of luteal phase oestradiol (vs Latinas, +9.4%, P=0.14; vs Whites, +25.3%, P=0.003) and progesterone (vs Latinas, +15.4%, P=0.07; vs Whites, +36.4%, P=0.002). Latina women were also observed to have higher follicular oestradiol, and luteal oestradiol and progesterone levels than White women (follicular oestradiol: +6.8%, P=0.48; luteal oestradiol: +14.6%, P=0.04; luteal progesterone: +18.2%, P=0.06). These results suggest that exposure to endogenous steroid hormones may be greater for young African-American and Latina women than for Whites.

Adult↗
PubMed2001

A multiethnic population-based study of smoking, alcohol and body size and risk of adenocarcinomas of the stomach and esophagus (United States).

OBJECTIVES: Since the 1970s incidence rates for esophageal and gastric cardia adenocarcinomas have risen substantially, particularly among white males in the United States. Reasons for the increase of these tumor types are not well understood. We sought to determine the role of smoking, alcohol use, and body size characteristics in the etiology of esophageal, gastric cardia, and distal gastric adenocarcinomas. MATERIALS AND METHODS: A population-based case-control study that included Whites, African-Americans, Latinos and Asian-Americans diagnosed with incident esophageal (n = 222), gastric cardia (n = 277), and distal gastric adenocarcinomas (n = 443), and 1356 control subjects was conducted in Los Angeles County. Unconditional logistic regression was used to calculate odds ratios (ORs), as an estimate of the relative risk, and corresponding 95% confidence intervals (CIs) for the three tumor types of interest. RESULTS: After adjustment for age, gender, race, birthplace, and education, current cigarette smoking was a significant risk factor for all tumor types; the association was strongest for esophageal adenocarcinomas (OR = 2.80, 95% CI = 1.8-4.3), intermediate for gastric cardia adenocarcinomas (OR = 2.12, 95% CI = 1.5-3.1), and weaker for distal gastric adenocarcinomas (OR= 1.50, 95% CI = 1.1-2.1). For esophageal adenocarcinomas only, cigarette smoking had a long-lasting deleterious effect, even 20 years after smoking cessation. Alcohol use was not associated with an increased risk of these tumor types. Risks of esophageal and gastric cardia adenocarcinomas also increased statistically significantly in a dose-dependent manner with increasing body mass index measured at ages 20 and 40 years and recently. The positive associations with smoking and body mass index were generally consistent when evaluated separately for Whites, non-Whites, males, and females. CONCLUSIONS: Cigarette smoking and high body mass index are significant, independent risk factors for esophageal and gastric cardia adenocarcinomas. Studies designed to understand the mechanisms whereby smoking and high body mass influence these tumor types are needed.

Adenocarcinoma↗
PubMed2001

Motivation for conflict among Chinese university students: effects of others' expertise and one's own confidence on engaging in conflict.

Researchers (A. C. Amason, 1996; D. H. Gruenfeld, 1995; K. A. Jehn, 1995, 1997; M. A. Rahim, 1989; M. A. Rahim & A. A. Blum, 1994; D. M. Schweiger, W. R. Sandberg, & P. L. Rechner, 1989; P. E. Tetlock, D. Armor, & R. S. Peterson, 1994) have documented the value of conflictual discussions for solving problems, but few have explored the conditions under which people are motivated to engage in controversy (K. A. Jehn, C. Chadwick, & S. M. B. Thatcher, 1997). Some (M. Van Berklom & D. Tjosvold, 1981) have hypothesized that high expertise and a competitive social context arouse concerns about defending one's position and challenging the opposing one. In the present study, Chinese university students in Hong Kong who expected to disagree with an expert, compared with those who did not expect to disagree with an expert, had less confidence, felt less knowledgeable about their position, and selected an agreeable discussant. Consistent with the idea of maintaining distance from those in power, the participants were reluctant to disagree directly with someone with greater expertise.

Conflict, Psychological↗
PubMed2001

[Molecular markers linked to dwarf gene Rht3 in wheat].

The dwarf gene Rht3 derived from Tom Thumb variety, a Tibetan wheat of China, is a dominant gene with the insensitivity to gibberellic acid. Rht3 shows to depress alpha-amylase activity and hence enchance the resistance to preharvest sprouting mainly through its effect on the expression of alpha-Amy1. Near isogenic lines with Rht3 and their segregating population were analyzed by PCR and RFLP techonology. In RAPD analysis, out of 310 random primers (10 bp) screened, only three primers of UBC389, OPV-06 and S1060 revealed polymorphisms in NIL from 310 random primers. Fragments S1060(1900) and S1060(2000) amplified by primer S1060 were shown to be linked to Rht3 with a genetic distance 7.1 cM and 9.2 cM. Fifty-three probes specific for short arms of homoeologous group 4 were screened in RFLP analysis. Xpsr584, XksuF8 and Xcdo38 showed polymorphisms between the NIL. The linkage analysis indicateded that Xpsr584 was linked to Rht3 with a genetic distance 8.0 cM.

Genes, Plant↗
PubMed2000

Effects of soy foods on ovarian function in premenopausal women.

It has been proposed that the high intake of soy foods among Asians may partly explain their lower rates of breast cancer, perhaps by lowering endogenous oestrogen levels, although this has been inadequately studied. Twenty healthy cycling premenopausal women (ten Asians and ten non-Asians) participated in a 7-month soy intervention study which was designed to investigate the effect of supplementation on ovarian function. Asian soy foods (tofu, soymilk, green soybean peas) in the amount of approximately 32 mg of isoflavones per day were added to the women's diets for three menstrual cycles. The women's baseline (two cycles) serum hormone levels were compared to levels during soy intervention (three cycles) and levels after intervention (two cycles). During the entire study period, subjects provided almost daily overnight urine samples and blood specimens during specified days of their menstrual cycles. The day of urinary luteinizing hormone (LH) peak was used as a marker for the day of ovulation. Knowledge of day of ovulation allowed comparison of hormone measurements at baseline to those obtained during intervention and recovery cycles with standardization of day of cycle. Soy intervention was associated with a statistically significant reduction in serum luteal oestradiol level (-9.3%, P < 0.05), but there were no significant changes in follicular phase oestradiol, follicular or luteal phase progesterone, sex hormone-binding globulin or menstrual cycle length. This significant reduction in luteal phase oestradiol was, however, observed only among Asian (-17.4%) but not among non-Asian (-1.2%) participants; urinary excretion of isoflavones was higher among Asians than non-Asians (29.2 vs 17.1 micromol day(-1), P= 0.16) during the intervention period. Thus, supplementation using traditional soy foods reduced serum oestradiol levels among Asian participants in this study. Differences in the type of soy products (i.e. traditional soy foods versus soy protein products), amount of isoflavones, and race/ethnicity of participants may have contributed to the divergent results. Larger soy intervention studies designed specifically to include participants of different race/ethnicities and using both traditional soy foods and soy protein products providing comparable doses of isoflavones are needed to definitively determine the effect of soy on ovarian function.

Adult↗
PubMed1999

[Pollen morphology identification of five species of medicinal sanguisorba with electron microscope].

OBJECTIVE: To approach a new evidence for identifying various species of Rosaceae Sanguisorba, especially for distinguishing S. applanata from S. sitchinese. METHOD: The pollens of five species S. officinalis, S. officinalis var. longifolia, S. applanata, S. applanata var. villosa and S. sitchinese were morphologically identified with electron microscope. RESULTS: The pollens are prolate or perprolate, having six colporates and featuring sculptures of small caverns and small granules combined. The species are closed to each other in pollen morphology, bur display differences in the diameter of pollens, clarity of pore membrane and presence or absence of irregular verrucous sculptures. CONCLUSION: This paper provides a new evidence for identifying the Sanguisorba.

Microscopy, Electron, Scanning↗
PubMed1995

[Hypocrellin B-ethanolamine (HB-E) sensitized photodamage on rat mitochondria].

The Hypocrellin B-Ethanolamine (HB-E) sensitized photodamage on lipid peroxidation, sulfhydryl oxidation and ATPase inactivation of rat liver mitochondria was studied under illumination of 640 nm, The HB-E sensitized photodamage of lipid peroxidation is less than sulfhydryl photooxidation, when HB-E concentration is 50 mumol/L. To elucidate the mechanism of photodamage of HB-E, antioxidant: BHT, Vit E, oxygen radical quencher: L-His, beta-Cart, were investigated. The results showed that HB photodamage of mitochondria is not only by oxygen radical, but also by HB-E radical as well. From compared tests among HB, HA, Hp, MB and HB-E, we found that HB-E had higher ability to photodamage lipid peroxidation, sulfhydryl oxidation and tryptophan than other photosensitizers. The experiments showed that the superoxide generated may be by HB-E radical.

Adenosine Triphosphatases↗
PubMed1994

[Case report of pulmonary histoplasmosis].

A case of pulmonary histoplasmosis in Beijing was reported Patient's CT scan showed naly patchy consolidation partly with small cavitations and hilar silhouette enlarged in both lungs. On pathologic examination, Histoplasma Capsutatums were found in the lung tissures by percutaneous lung biopsy. Skin rash had developed in the course. After treated by fluconaxole, most of the lung lesions and skin rash disappeared.

Adult↗
PubMed1990

[Cytological study on Eclipta prostrata L].

The authors report that the karyotype formula of Eclipta prostrata is K(2n) = 22 = 16m + 6sm, which belongs to "1A" of stebbins, the chromosome composition based on relative length is 2n = 22 = 10M2 + 12M1, and the total length of the chromosome is 29.3 microns. The chromosome volume of E. prostrata has also been calculated.

Chromosomes↗
PubMed1987

Cytotoxicity of compounds that interfere with the regulation of intracellular pH: a potential new class of anticancer drugs.

The extracellular pH (pHe) in many solid tumors is often lower than in normal tissues. Cells may survive conditions of acid pHe because antiports in their membrane exchange Na+ for H+, or HCO3- for Cl-, and thus regulate the intracellular pH (pHi). We have therefore assessed the effects of drugs which interfere with regulation of pHi on survival of Chinese hamster ovary and human bladder cancer MGH-U1 cells in tissue culture. Nigericin, an ionophore which acidifies the cytoplasm when cells are placed in medium at low pHe, was not toxic at pHe 6.5 or above but became very toxic as pHe was reduced below this value. Amiloride and 4,4'-diisothiocyanostilbene 2,2-disulfonic acid, inhibitors of the Na+/H+ and HCO3-/Cl- exchangers, respectively, decreased pHi in the presence of nigericin at low pHe. These drugs showed little or no toxicity in the pHe range of 6.0-7.0 but added greatly to the toxicity of nigericin. A combination of all three drugs led to toxicity in the pHe range of 6.5-6.8, well within the measured range of tumor pH, but not at pHe 7.0 or above. A combination of low pH and hypoxia, two conditions likely to be found in regions distant from tumor blood vessels, caused cell mortality in the absence of drugs, and this effect was increased by nigericin used alone or in combination with amiloride and 4,4'-diisothiocyanostilbene 2,2-disulfonic acid. These drugs may be regarded as prototypes for potential new anticancer agents that might achieve selective killing of tumor cells by interfering with the regulation of intracellular pH.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMedDate not supplied

Closed one-stage functional end-to-end jejunojejunostomy in horses with use of linear stapling equipment.

OBJECTIVE: To use gastrointestinal linear stapling instrumentation to perform a closed one-stage functional end-to-end jejunojejunostomy in adult horses as an alternative to a stapled side-to-side jejunojejunostomy. STUDY DESIGN: Clinical outcome, anatomic and histological architecture, and anastomotic dimensions were determined at 2, 4, 8, 16, and 24 weeks postoperatively. ANIMALS OR SAMPLE POPULATION: 18 adult horses. METHODS: The anastomosis and peritoneal cavity were inspected for adhesions. The diameter and circumference of the anastomosis and jejunum oral and aboral to the anastomosis were determined from digitized contrast radiographs and linear measurements. Healing of anastomotic sites was evaluated histologically. RESULTS: Three horses were euthantized in the immediate postoperative period. In the 15 surviving horses, there were no peritoneal adhesions or distortion of the anastomoses and stomas remodeled in an end-to-end fashion. The mean anastomotic staple line (7.48 cm) and mucosa (6.89 cm) diameters were significantly (P < .05) larger than the mean jejunal diameter oral (6.03 cm) and aboral (6.01 cm) to the anastomosis. The mean anastomotic luminal circumference (13.61 cm) was significantly (P < .01) larger than the mean oral (11.43 cm) and aboral (11.12 cm) jejunal circumference. Histologically, there was adequate mucosal and muscularis mucosae reapposition with a moderate degree of fibrosis and inflammation. CONCLUSIONS: Closed one-stage functional end-to-end jejunojejunostomy resulted in an acceptable functional anastomosis. CLINICAL RELEVANCE: This technique appears to be an acceptable alternative to linearly stapled, side-to-side jejunojejunostomies performed in horses.

Anastomosis, Surgical↗