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Biomedical subjects

G Xu

Publications and source records attributed to G Xu.

At least 325 records · Page 18Linked to original sources
PubMed1997

Comparisons between older and usual-aged medical school graduates on the factors influencing their choices of primary care specialties.

PURPOSE: To examine whether there are differences between older (30+ years) and usual-aged graduates in the factors that influence their decisions to enter primary care. METHOD: A national survey of primary care physicians was conducted by mail in early 1993. The survey population comprised physicians who had graduated from U.S. allopathic medical schools in 1983 and 1984. The questionnaire consisted of four parts: practice characteristics, 19 variables influencing the physicians' decisions to enter primary care (rated on a scale from 5 = very strong influence to 1 = no influence), the timing of the decision to enter primary care, and demographic and personal information. Data were analyzed through several statistical methods. RESULTS: In all, 355 (22%) older and 1,241 (78%) usual-aged graduates who were practicing in primary care specialties responded. Compared with the usual-aged graduates, the older graduates were more likely to have grown up in rural or inner-city areas, to have obtained a second academic degree, and to have made the decision to enter primary care earlier. The older graduates' decisions to enter primary care had been more influenced by children and familial responsibilities, whereas the usual-aged graduates had been more influenced by internship and residency experiences and by parents and role models before medical school. CONCLUSION: This study provides empirical evidence to support the notion that nontraditional students (i.e., older ones) are more likely to commit themselves earlier to a career decision and less likely to be influenced by the socialization process during medical school. In this regard, age-specific factors should receive more attention in the analysis of the physician workforce.

Adult↗
PubMed1997

Effect of aging on B-cell function and replication in rat pancreas after 90% pancreatectomy.

We studied the effect of aging on B-cell function and replication in depancreatized rats. Male Wistar rats, at the ages of 1, 5, and 15 months, underwent 90% pancreatectomy (Px) or a sham operation, and islet function and regeneration were examined 3 weeks later. Plasma glucose levels in 1-month-old rats reached a peak 2 weeks after Px and then declined, while those in 5- and 15-month-old rats reached significant levels as early as the day after Px or 2 days after surgery and continued to increase over the following 3 weeks. Consequently, in contrast to young Px rats, weight loss due to severe diabetes was observed in 5- and 15-month-old Px rats. Plasma glucose responses to intravenous glucose loading (0.5 g/kg body weight) were much greater in older Px rats than in younger rats. There was a marginal insulin response to glucose in 1-month-old Px rats, whereas no insulin response to glucose was observed in older Px animals. The insulin content of the residual pancreas was increased threefold in 1-month-old Px rats, but there was no increase in 5- and 15-month-old Px rats. These data demonstrate that the effect of reducing islet mass is much greater in aged rats than in young rats and that the replicatory capacity of B cells tends to diminish after adulthood has been reached.

Aging↗
PubMed1997

VP7: an attachment protein of bluetongue virus for cellular receptors in Culicoides variipennis.

The importance of VP7 of bluetongue virus (BTV) in the binding of BTV to membrane proteins of the BTV vector Culicoides variipennis was investigated. Core BTV particles, prepared from whole viruses, lacked outer proteins VP2 and VP5 and had VP7 exposed. More core particles and whole viruses bound to membrane preparations of adults of C. variipennis and KC cells, which were cultured from this vector insect, than to membrane preparations of Manduca sexta larvae. More core particles than whole viruses bound to membrane preparations of adults of C. variipennis and KC cells. Polyclonal anti-idiotypic antibodies (anti-Id), which were made against an antigen-combining region of an anti-BTV-10 VP7 antibody and functionally mimicked VP7, bound more to the membrane preparations of adults of C. variipennis and KC cells, and less to cytosol preparations. In Western overalay analysis, the Culicoides plasma membrane preparation reduced binding of an anti-VP7 monoclonal antibody to VP7. Whole and core BTV particles and the anti-Id bound to a membrane protein with a molecular mass of 23 kDa that was present predominantly in membrane preparations of adults of C. variipennis and KC cells. This protein was present in much lower concentrations in membrane preparations of C6/36 and DM-2 insect cells.

Animals↗
PubMed1997

Serum Calmodulin Activity in Male Lead-exposed Workers.

Serum calmodulin (CaM) activity was studied in 75 lead-exposed and 21 non-exposed male workers. The lead-exposed workers were divided into groups with low blood lead (BPb < 50 µg/dL) and high blood lead (BPb>/=50 µg/dL). The concentrations of lead, calcium, magnesium, copper, zinc, and free erythrocytic protoporphyrin (FEP) in blood were determined. Serum samples were heated in a water bath (100 degrees C) for 3 minutes and centrifuged for 15 minutes at 4 degrees C (18,000 x g). The supernatants obtained were used to measure CaM activity. The results showed that: 1) Average blood lead concentrations in workers with both low and high levels of exposure were significantly higher than those in controls (p < 0.05). 2) Serum CaM activity in the high-exposure group (31.09 +/- 7.84 µg/dL) was significantly lower than that in controls (78.11 +/- 15.13 µg/dL, p < 0.05). The biological threshold of BPb inhibition of CaM activity was less than 50 µg/dL. 3) Multiple correlation analysis showed a negative dose-response relationship between BPb and CaM activity. The stepwise regression procedure indicated that lead had negative, and calcium and magnesium positive, effects on serum CaM activity. The regression equation was Y = 66.1383 - 1.0857 X&inf1; + 2.9676 X&inf2; + 5.2222 X&inf3; (Y:CaM; X&inf1;:Pb; X&inf2;: Ca; X&inf3;:Mg). These results of the first such study carried out in male lead-exposed workers suggest that lead can inhibit CaM activity in humans.

Journal Article↗
PubMed1997

The relationship between the race/ethnicity of generalist physicians and their care for underserved populations.

OBJECTIVES: The purpose of this study was to examine empirically the relationship between physicians' race or ethnicity and their care for medically underserved populations. METHODS: Generalist physicians who received the MD degree in 1983 or 1984 (n = 1581) were surveyed. The personal and background characteristics of four racial/ethnic groups of physicians were compared with the characteristics of their patients. RESULTS: When the potentially confounding variables of gender, childhood family income, childhood residence, and National Health Services Corps financial aid obligations were controlled, generalist physicians from underrepresented minorities were more likely than their nonminority counterparts to care for medically underserved populations. CONCLUSIONS: Physicians from underrepresented minorities are more likely than others to care for medically underserved populations.

Adult↗
PubMed1997

[The experimental study on absorption and utilization of calcium from oyster shell powder mixed with fruit juice].

A new kind of calcium powder was prepared from the shell of oyster and the bones of other sea lives, in which fruit juice was mixed. This calcium powder and other four different forms of calcium (i.e., active calcium, gluconate, lactate, and phosphate) were fed to 4 groups of Wistar rats for 30 days. 3 days calcium metabolism test was done. The absorption and retention rates of calcium powder were 69.2% and 95.1% in the experimental group, which were higher than those in other calcium supplement groups (P < 0.05). The weight of femurs and the total calcium content of femurs had significantly increased in calcium powder group (P < 0.05). These findings indicated that calcium from calcium powder, which was prepared from sea lives and mixed fruit juice was more effective.

Animals↗
PubMed1997

[Experimental studies about effect of dexamethasone on diaphragm of normal rats].

The influence of dexamethasone on diaphragm function, its oxidative capacity, fiber cross-sectional areas, the content of glycogen and ultrastructural changes were determined in Wistar rats by receiving dexamethasone (2 mg/kg) muscle injection for two weeks. We noted dexamethasone treatment leads to significant atrophy of the mass of diaphragm, reduction of fiber cross-sectional areas (CSA) of type II a, II b fibers. Under high frequency (100 Hz) stimulation, the tention of the diaphragm muscle strips was decreased and diaphragm fatigue resistance (1/2 RT) was significantly improved. Histochemically, ATPase activity in type I and type II b fibers of the diaphragm was significantly reduced and a significant reduction of succinate dehydrogenase activity in the diaphragm was also observed, but increased glycogen was seen in the diaphragm. Ultrastructural changes including mitochondrial hyperplasia, swelling, myofibillae focus destructure were evident. It is concluded that steroid-induced myopathy may also involve the diaphragm.

Adenosine Triphosphatases↗
PubMed1997

[Effect of somatostatin on human sphincter of Oddi motility].

The effect of somatostatin on the sphincter of Oddi was investigated in 20 subjects referred for endoscopic sphincter of Oddi manometry. Six patients had common bile duct dilatation, three had common bile duct slight dilatation, three had hepatic hilar carcinoma and eight had normal findings on endoscopic retrograde cholangiopancreatography. A triple-lumen low compliance system was used to record the sphincter of Oddi basal pressure, phasic contraction frequency, amplitude, duration, and direction of wave propagation before and after intravenous administration of somatostatin in a dose of 250 micrograms. After a mean latency period of 1 min, there were significant changes including decreased basal pressure (P < 0.01) and decreased frequency of wave contraction (P < 0.01). The amplitude and duration of wave contraction and wave propagation sequence were not significantly influenced. Thus somatostatin has a significant inhibitory effect on the sphincter of Oddi activity, which may be helpful for biliary and pancreatic flow.

Adult↗
PubMed1997

[Meningo-cerebral arteriovenous malformations].

22 patients with meningo-cerebral arteriovenous malformations, we treated in our hospital between 1990 and 1995. Clinical manifestations included headache, nausea, seizure, intracranial hemorrhage, and progressive hemispheric neurologic deficits. The niduses were extensive and had dual feeding from internal and external carotid arteries. All patients underwent endovascular treatment and 4 surgical operations. The curative effect was satisfactory. The clinical and angiographic characteristics were discussed.

Adolescent↗
PubMed1997

[Atypical manigioma].

Most meningiomas have typical clinical and CT features. But some meningiomas which have an atypical clinical and CT findings can lead to a wrong diagnosis. The authors have reviewed 123 hospitalized patients with meningiomas which had been pathologically diagnosed. Nine of them had atypical meningiomas according to their histories, symptoms, signs and CT findings. All of these patients were mis diagnosed as having gliomas or metastatic tumors. The authors analyed these cases carefully and find the clues that may help to do an accurate preoperative diagnosis.

Adult↗
PubMed1997

[Long-term effect of voice rehabilitation in 125 patients following total laryngectomy].

One hundred and twenty-five patients received voice rehabilitation operations following total laryngectomy over the period from August 1977 to December 1994. Among them, 119 were male and 6 were female, the eldest was 70 years old and the youngest 30 years old, and the average age was 55.3 years. Clinical staging was as follows: stage II, 2 cases; stage III, 45 cases; stage IV, 66 cases; and recurrence, 12 cases. The voice rehabilitation operations included pharynx-trachea anastomosis 18 cases and trachea-esophagus fistulization 107 cases. One hundred and fourteen patients were followed-up for 13 months to 18 years. The 3, 5, and 10 year survival rates were 78.2%, 61.4%, and 40.5% respectively. The effective rates of voice rehabilitation according to hearing voice distance were 84.6%, 81.1%, and 67.5% 3 weeks, 1 year, and 5 years respectively after operation. The causes of failure were closure of fistula 15 cases; food aspiration 8 cases and unknown 3 cases. The clinical value, advantages and disadvantages of voice rehabilitation, and the time to evaluate the effect of voice rehabilitation were discussed.

Adult↗
PubMed1997

[Microscopic identification of the powder of roots of genus Adenophora: II. The roots of Sect. Remotiflorae and Sect. Adenophora].

This paper deals with the microscopic characteristics of the powder of the roots of 11 species and subspecies of Genus Adenophora. The results show that Sect. Basiphyllae, Sect. Pachydiscus, Sect. Remotiflorae and Sect. Adenophora can be identified based on the amount and thickness of the wall as well as the characteristics of the pit of sclerified cork cells, and 29 species, subspecies and varieties can be identified based on the amount, shape and thickness of the walls of the sclerified cork cells, the diameter and pit of the vessels, the number and shape of the secretion of the laticifers, and the number of inulin crystals.

Magnoliopsida↗
PubMed1997

[Immunohistochemical study on the expression of c-erbB2 oncoprotein in breast tumors].

OBJECTIVE: To examine the relationship between oncoprotein c-erbB2 over-expression and prognosis of primary breast tumor patients, and find if it can be used as a prognostic indicator. METHODS: Eighty-five cases of paraffin-embedded specimens were used for immunohistochemical study. RESULTS: Over-expression of c-erbB2 was observed in none of the 7 benign breast tumors. Twenty-three out of 78 cases of breast cancer showed over-expression with a positive rate of 29.4%. Over-expressed c-erbB2 oncoprotein was not detected in 80% of patients with negative lymph node. In clinical stage III patients, 71% of them over-expressed c-erbB2. The expression of c-erbB2 and estrogen receptor(ER) was inversely correlated in 67% of breast cancer patients. Oncoprotein c-erbB2 over-expression had no correlation with lymph node status(P > 0.05), but was closely correlated to clinical staging(P < 0.05). CONCLUSION: Patients with over-expression of c-erbB2 oncoprotein showed poor prognosis. The c-erbB2 may be used for predicting the prognosis of breast cancer patients.

Breast Neoplasms↗