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Biomedical subjects

G Xu

Publications and source records attributed to G Xu.

At least 469 records · Page 26Linked to original sources
PubMed1995

Lung cancer among workers exposed to silica dust in Chinese refractory plants.

A retrospective cohort mortality study was conducted for lung cancer among silica and clay brick workers at 11 refractory plants in China. The cohort included 6266 male workers employed before 1962 and followed between 1963 and 1985. The standardized rate ratios (SRR) were obtained by comparing the mortality rates of the silica-exposed cohort with those of a population of 11 470 male steel workers. As expected, significant excesses were observed for all deaths, all cancers, lung cancer, cardiorespiratory diseases, pulmonary heart diseases, and pulmonary tuberculosis. The lung cancer SRR was 1.49 (P < 0.01) for the total cohort. The increased lung cancer risk was attributed to the silicotics (SRR 2.10; P < 0.01) in the cohort. Higher lung cancer risk was found with increasing latency and severity of silicosis; this finding suggests that the excess was possibly related to occupational exposure to silica dust. Among the silicotics, there was a twofold excess of lung cancer risk among both the nonsmokers and the smokers.

China↗
PubMed1994

E2F-4, a new member of the E2F transcription factor family, interacts with p107.

The E2F family of transcription factors has been implicated in the regulation of cell proliferation, and E2F-binding sites are present in the promoters of several growth-regulating genes. E2F family members are functionally regulated, in part, by complex formation with one or more members of the nuclear pocket protein family, RB, p107, and p130. Pocket protein regulation of E2F likely contributes to normal cellular growth control. While the three cloned species of E2F, E2F-1, E2F-2, and E2F-3, are known to be targets of RB interaction, no E2F species has yet been shown to be a specific p107 or p130 target. Here, we describe the cloning of a new member of the E2F family, E2F-4, which forms heterodimers with a member(s) of the DP family and, unlike some family members, is present throughout the cell cycle and appears to be a differentially phosphorylated p107-binding partner. p107 binding not only can be linked to the regulation of E2F-4 transcriptional activity, but also to suppression of the ability of E2F-4 to transform an immortalized rodent cell line.

Adenovirus E2 Proteins↗
PubMed1994

Medical school and student characteristics that influence choosing a generalist career.

OBJECTIVE: To identify predictors in medical schools that can be manipulated to affect the proportion of graduates entering generalist practice. DESIGN AND PARTICIPANTS: Cross-sectional and retrospective studies of medical schools and practicing generalist physicians; surveys of MD-granting and DO-granting medical schools; site visits to nine schools with a high proportion of graduates becoming generalist physicians; surveys of national samples of MD and DO generalist physicians. INDEPENDENT VARIABLES: Characteristics of medical schools, including structural characteristics, financing, mission, admissions policies, student demographics, curriculum, faculty, and the production of generalist physicians; information on personal characteristics, background, perceptions, and attitudes of practicing generalist physicians. DEPENDENT VARIABLE: Estimated proportion of graduates of the classes of 1989, 1990, and 1991 in family practice, general internal medicine, and general pediatrics. RESULTS: Institutional mission, certain admissions policies, characteristics of entering students, and the presence of a primary care-oriented curriculum explained statistically significant variation in the number of physicians choosing generalist careers, even after the structural characteristics of public or private status, age of the school, and class size were controlled for statistically. CONCLUSIONS: Public and institutional policies, where implemented, have had a positive effect on students' choice of generalist careers. The most influential factors under the control of the medical school are the criteria used for admitting students and the design of the curriculum, with particular emphasis on faculty role models. Personal social values was the individual characteristic that most strongly influenced graduates' career choice.

Career Choice↗
PubMed1994

Immunotherapy with anti-CD3 monoclonal antibodies and recombinant interleukin 2: stimulation of molecular programs of cytotoxic killer cells and induction of tumor regression.

Adoptive cellular immunotherapy, infusions of interleukin 2 (IL-2) in conjunction with in vitro-activated killer cells, has brought new hope to patients with cancer. The broad application of this strategy, however, is constrained by the need for repeated leukapheresis and by the labor-intensive process of in vitro activation of cells. Also, current protocols generally use nonphysiological and toxic concentrations of IL-2. Identification of an in vivo stimulant that renders T cells responsive to physiologic concentrations of IL-2 represents a potential improvement over existing approaches. We have determined whether in vivo administration of monoclonal antibodies (mAbs) directed at the T-cell surface protein CD3 induces T-cell responsiveness to IL-2, stimulates cytolytic molecular programs of natural killer cells and cytotoxic T cells, and induces tumor regression. These hypotheses were explored in a murine hepatic MCA-102 fibrosarcoma model. We report that in vivo administration of anti-CD3 mAbs plus IL-2 results in intrahepatic expression of mRNA-encoding perforin, cytotoxic T-cell-specific serine esterase, and tumor necrosis factor alpha. Anti-CD3 mAbs alone or IL-2 alone failed to induce or induced minimal expression of these molecular mediators of cytotoxicity. The anti-CD3 mAbs plus IL-2 regimen also resulted in a significantly smaller number of hepatic metastases and a significantly longer survival time of tumor-bearing mice, compared to treatment with anti-CD3 mAbs alone or IL-2 alone. Our findings suggest that a regimen of anti-CD3 mAbs plus IL-2 is a more effective antitumor regimen compared with anti-CD3 mAbs alone or IL-2 alone and advance an alternative immunotherapy strategy of potential value for the treatment of cancer in humans.

Animals↗
PubMed1994

LRG1 is expressed during sporulation in Saccharomyces cerevisiae and contains motifs similar to LIM and rho/racGAP domains.

We here report the sequence of a yeast gene LRG1 whose deduced amino acid sequence contains sequence motifs similar to LIM domain proteins in the amino-terminal, and to rho/rac GTPase activating proteins (rho/racGAP's) in the carboxy-terminal part. LRG1 expression is differentially regulated showing a peak of expression in sporulating cells. Gene disruption experiments indicate that the gene is not essential and may play a role during mating.

Amino Acid Sequence↗
PubMed1994

Specificity of sialyl-sugar chain mediated recognition by the hemagglutinin of human influenza B virus isolates.

Recognition specificity for sialylsugar chains by the hemagglutinin of influenza B viruses isolated in different years from 1940 through 1990 (B/Lee/40, B/Setagaya/3/56, B/Tokyo/7/66, B/Kagoshima/1/68, B/Gifu/2/73, B/Kanagawa/3/76, B/Ibaraki/2/85, B/Yamagata/16/88, and B/Bangkok/163/90) was studied using 13 gangliosides. Reactivity of the viruses' hemagglutinin binding to gangliosides was determined by using thin-layer chromatography/virus-binding assay, and also by measuring virus binding to erythrocytes modified by incubation with gangliosides in terms of the absorbance of hemoglobin released from the infected cells. Eight strains preferentially recognized a novel ganglioside, carrying lacto-series type I and II sugar chains with the Neu5Ac alpha 2-6Gal linkage. It was found that B/Gifu/2/73 strain binds to lacto-series gangliosides containing Neu5Ac alpha 2-6Gal and Neu5Ac alpha 2-3Gal linkages. Other gangliosides studied, including GM4, GM3(alpha 2-3), GM3(alpha 2-6), GM2, GM1a, GD3, GD1a, GD1b, and GT1b, were poor receptors.

Animals↗
PubMed1994

Neurofibromin can inhibit Ras-dependent growth by a mechanism independent of its GTPase-accelerating function.

The NF1 gene, which is altered in patients with type 1 neurofibromatosis, has been postulated to function as a tumor suppressor gene. The NF1 protein product neurofibromin stimulates the intrinsic GTPase activity of active GTP-bound Ras, thereby inactivating it. Consistent with a tumor suppressor function, we have found that the introduction of NF1 in melanoma cell lines that are deficient in neurofibromin inhibited their growth and induced their differentiation. In addition, overexpression of neurofibromin in NIH 3T3 cells was growth inhibitory but did not alter the level of GTP.Ras in the cells. Transformation by v-ras, whose protein product is resistant to GTPase stimulation by neurofibromin, was inhibited in a cell line overexpressing neurofibromin, while transformation by v-raf was not altered. The results demonstrate that NF1 is a tumor suppressor gene that can inhibit Ras-dependent growth by a regulatory mechanism that is independent of neurofibromin's ability to stimulate Ras GTPase.

3T3 Cells↗
PubMed1994

Primary care and nonprimary care physicians' concerns in practice and perceptions of medical school curriculum.

The purpose of the present study is to address the issue of physicians' concerns in practice and their perception of a medical school's curriculum with an emphasis on comparisons between primary and nonprimary care physicians. The sample consisted of 663 physicians who graduated from Jefferson Medical College (JMC) between 1982 and 1986, and also responded to a mailed questionnaire. Comparisons were made between physicians in primary care (n=234) and in nonprimary care (n=429) specialties on their responses regarding concerns in medical practice and evaluation of the medical school curriculum. Primary care physicians were more concerned about the time for their professional development whereas nonprimary care physicians were more concerned about an oversupply of physicians in their specialties, prospective hospital payment, and malpractice litigation. Regardless of the specialties, the physicians overall seemed very concerned about their personal time. Interpersonal skills were regarded by all respondents as an important aspect of the medical school's curriculum. The importance of psychological, social, and cultural factors in the curriculum was strongly supported by these physicians' responses, particularly among primary care and women physicians.

Attitude of Health Personnel↗
PubMed1994

[Influence of stress on gastroenteric electric activity and modulated effect of acupuncture on it in rats].

Experiments were performed in SD rats. Three pairs of bipolar electrode were implanted surgically on the antrum, ascending and descending colon of rats. The stress model was induced by restraint cold immersion (4 degrees C Water, 30-40 min.). The modulating effect of Zusanli ST36 acupuncture on gastroenteric electric activity was investigated. The inhibitory effects of gastro-colon electric activity were obviously displayed in stress rats, such as the frequency and amplitude of slow wave were reduced, rhythmic disorder, degree of dispersion was enlarged, fast wave was decreased and the IDMEC phase III was prolonged or disturbed. Acupuncture of Zusanli could effectively reduce the inhibition effect of gastro-colon electric activity induced by stress in rats.

Animals↗
PubMed1994

[Surgical anatomy of the lateral wall of the sphenoid sinus].

Sixty-three sphenoid sinuses were examined in cadavers, with special attention to the neural and vascular structures on the lateral wall of the sinus. There are three structures producing prominences on the lateral wall of the sinus, 1) The carotid artery, including its presellar segment, infrasellar segment and retrosellar segment. The means of length, thickness and the distance to the middle line of the presellar one are 6.8 mm, 1.0 mm and 6.2 mm respectively. The means lf length, thickness and the distance to the middle line of the infrasellar one are 6.6 mm, 1.0 mm and 5.0 mm respectively. The means of length, thickness and the distance to the middle line of the retrosellar one are 6.6 mm, 1.8 mm and 7.1 mm respectively. 2) The bulge of optic canal, the means of its length, thickness and the distance to the middle line in sphenoid sinus are 4.8 mm, 1.0 mm and 5.5 mm respectively. 3) The maxillary branches of the trigeminal nerve, the mean of its length, thickness and the distance to the middle line in sphenoid sinus are 5.3 mm, 1.2 mm and 8.5 mm respectively.

Adult↗
PubMed1994

[Intranasal endoscopic management of cerebrospinal rhinorrhea].

The excellent visualization and atraumatic surgical techniques of endoscopic sinus surgery have been applied to the management of five cases of cerebrospinal rhinorrhea in the last 3 years. In all the cases, the exact sites of the lesion were identified on ethmoid roof (2 cases) or sphenoid sinus (3 cases). The procedures of the operation were as follows: to enlarge the leak and at the same time to block up it with the muscles, and then covering the muscles with fascia. All of the five cases were cured by one-step surgery. The techniques and indications for endoscopic management of cerebrospinal rhinorrhea are discussed.

Adolescent↗
PubMed1994

[Regulating effect of electro-acupuncture on dysrythmia of gastro-colonic electric activity induced by erythromycine in rabbits].

The myoelectric activity of gastro-colon was recorded in 20 rabbits. The model of gastro-colonic disorder was produced by vena injection of erythromycine (EM) (7 mg/kg). We investigated regulating effect of electro-acupuncture (EA) on the disorder of gastrocolonic electric activity (GEA). After the vagotomy the effect of EA was observed. In fasting and anaesthetic rabbits, the frequency and amplitude of GEA were 4.47 +/- 1.23 cmp, 1.90 +/- 0.27 mV at antrum, 8.33 +/- 2.61 cpm, 0.51 +/- 0.12 mV at ascending colon, 6.74 +/- 2.68 cpm, 0.35 +/- 0.10 mV at descending colon. After injection of EM, the frequency and amplitude of GEA were increased, the latency and duration of EM effect were 36.5 +/- 4.5 min and 3.8 +/- 1.4 min, the great contraction wave was showed. EA could shorten the duration and latency, decrease the frequency, amplitude and variation coefficient of GEA. After vagotomy the effect of EA disappeared. These results indicate that vagus nerve plays an important role in regulating effect of EA on gastro-colonic disorder.

Animals↗
PubMed1994

[Inhibition of protein kinase C by stilbenoids].

The effect of 15 stilbenoids on protein kinase C (PKC) was studied in order to search for naturally occurring PKC inhibitors. All these compounds were isolated from Chinese medicines. Three oligomeric stilbenes from Caragana sinica, alpha-viniferin, kobophenol A and miyabenol C, were shown to intensely inhibit the activity of partially purified rat brain PKC with IC50 values of 62.5, 52.0, and 27.5 mumol.L-1, respectively. Kinetic analyses revealed that that inhibition was noncompetitive. The other compounds also showed the effect. Monomer stilbenes exhibited PKC inhibitory activity at higher mumol.L-1 concentrations than oligomeric stilbenes. Whenever they are methylated or acetylated perfectly, the inhibition weakens or disappears.

Animals↗
PubMed1994

[Assay of R-plasmid and antibiotic resistance spectrum in 286 strains of gram-negative bacteria].

This paper reports the results of the sensitivity test to 10 antibiotics and the assay of R-plasmid on 286 strains of Gram-negative bacteria isolated from hospitals. It was found that the main prevalent resistant bacteria are Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae. Their major antibiotic resistance spectrum is: Ampicillin, Carbenicillin, Chloramphemicol, Gentamicin, Furbenicillin. The results showed that 272 of 283 strains resisted to 1-9 antibiotics (95.1%). One-hundred and seventy-eight of 286 strains resisted to more than 4 antibiotics (62.2%). One-hundred and fifty-one of 286 strains carried R-plasmid in resistant bacteria (53.3%). 13.3% resistance markers were transferred with the whole R-factor. But 86.7% resistance markers were transferred with only a part of R-factor.

Ampicillin Resistance↗
PubMed1994

[Nosocomial respiratory infection caused by Xanthomonas maltophilia in immunocompromised hosts].

Between January 1988 and December 1992, 68 patients admitted to our Department of Internal Medicine with hematological malignancies or solid tumors showed colonization of the respiratory tract with Xanthomonas maltophilia (X. maltophilia). To characterize the significance of respiratory tract colonization by X. maltophilia, we retrospectively reviewed the medical records of the 68 patients colonized with this organism. Twenty-seven of these 68 patients developed pneumonia, with X. maltophilia being implicated in 10 cases. The majority of the 10 patients showed lobular infiltration on chest X-ray. Pleural effusion was observed in 2 (20%) of the 10 patients. All 68 strains of X. maltophilia were resistant to imipenem/cilastatin. Most strains (98.5%) were sensitive to latamoxef, while all strains were sensitive to minocycline. This report describes the clinical features of nosocomial X. maltophilia pneumonia in immunocompromised patients.

Adolescent↗
PubMed1994

Characterization of antiphospholipid antibodies in women with recurrent spontaneous abortions.

Antiphospholipid antibodies are important in the etiology of recurrent pregnancy loss. To date, most studies have concentrated on antibodies to cardiolipin specifically. In this study, the serum of 352 women with recurrent pregnancy loss was studied by enzyme-linked immunosorbent assay for antibodies to six phospholipid epitopes: cardiolipin, phosphoserine, phosphoglycerol, phosphoethanolamine, phosphatidic acid and phosphoinositol. Of these women, 59.1% had either an IgG or IgM antibody to one of the six phospholipids. This compared to only 4.6% in the control group. Approximately 75% of the isotypes were IgM. The most common phospholipid epitope was phosphoserine. However, in patients with antibodies to only one phospholipid, phosphoethanolamine was the most common. These findings support recent evidence that antiphospholipid antibodies may interfere with the formation of syncytiotrophoblasts in the placenta. In addition, antiphospholipid antibodies occur more frequently in patients who suffer recurrent miscarriages than was previously thought.

Abortion, Habitual↗
PubMed1993

Evaluation of brain function in acute carbon monoxide poisoning with multimodality evoked potentials.

The median nerve somatosensory evoked potentials (SEP), pattern reversal visual evoked potentials (VEP), and brain stem auditory evoked potentials (BAEP) were studied in 109 healthy adults and in 88 patients with acute carbon monoxide (CO) poisoning. The upper limits for normal values of peak and interpeak latencies of multimodalities of evoked potentials in the reference group were established by a stepwise multiple regression analysis. SEP changes selectively affecting N32 and N60 were found in 78.8% of patients. There was prolonged P100 latency of VEP in 58.2% of the cases examined. The prevalence of BAEP abnormalities in comatose patients (36%) was significantly higher than that (8.6%) in conscious patients. BAEP abnormalities were most frequently seen in comatose patients who had diminished brain stem reflexes (77.8%). It has been found that a consistent abnormality involving N20 and subsequent peaks in SEP, a remarkable prolongation of P100 latency in VEP, or a prolongation of III-V interpeak latency in BAEP as well as the reoccurrence of evoked potential abnormalities after initial recovery all indicate unfavorable outcomes in patients with acute CO poisoning. The multimodality evoked potentials have proved to be sensitive indicators in the evaluation of brain dysfunction and in the prediction of prognosis of acute CO poisoning and the development of delayed encephalopathy.

Adult↗