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Biomedical subjects

A W Chen

Publications and source records attributed to A W Chen.

15 recordsLinked to original sources
PubMed2000

[Effect of propofol and midazolam on cerebral oxygen supply and demand imbalance during cardiopulmonary bypass].

Thirty patients undergoing heart valve replacement were divided randomly into three groups (n = 10): control group, propofol group and midazolam group. Jugular bulb blood oxygen saturation (SjO2), arterialvenous oxygen content difference (Da-vO2) and cerebral oxygen extraction rate(CEO2) were measured at various periods of cardiopulmonary bypass (CPB). The results showed: SjO2 decreased significantly, Da-vO2 and CEO2 increased markedly during rewarming period in control group; but in propofol group and midazolam group, SjO2, CEO2 and Da-vO2 did not decline significantly compared with baseline. It is suggested that administering propofol or midazolam is helpful in avoiding cerebral oxygen supply and demand imbalance during CPB.

Adolescent↗
PubMed1995

Functional consequences of directed mutations in human papillomavirus E6 proteins: abrogation of p53-mediated cell cycle arrest correlates with p53 binding and degradation in vitro.

Clinical and epidemiological studies have implicated the involvement of human papillomavirus (HPV) infection in cervical tumorigenesis. We have previously shown that expression of high-risk (HPV16) E6 can abrogate an important cell cycle checkpoint mediated by p53. Sublethal DNA damage causes p53 accumulation and G1 arrest in normal cells, but not in cells with mutant or absent p53, or in cells that express HPV16-E6. To investigate the functional consequences of low-risk (HPV11) E6 expression and to evaluate regions of E6 believed to mediate interaction with p53, we generated several E6 expression constructs, including HPV11-E6, and fourdifferent E6 mutants. HPV16E6 deltaD and HPV16E6 deltaB had short deletions of nucleotides encoding amino acids previously implicated in p53 degradation and binding, respectively. HPV16E6HL and HPV11E6LH had the putative p53 binding domain exchanged between the high- and the low-risk types. Unlike HPV16-E6, HPV11-E6 and the mutant E6 proteins were not able to bind or degrade p53 in in vitro assays. When expressed in RKO cells, HPV11-E6 or the mutant E6 proteins did not prevent p53 accumulation or interfere with p53-dependent WAF1/CIP1 mRNA expression, allowing p53-mediated G, cell cycle arrest after DNA damage. These findings demonstrate that low-risk and high-risk E6 proteins differ in their effects on p53-mediated cell cycle control and that rather subtle mutations of high-risk E6 can alter its ability to abrogate this important cellular response.

Cell Cycle↗
PubMed1993

Dermatophyte pseudomycetoma: a case report.

A 25-year-old man presented with several prominent subcutaneous masses in the occipital region of the scalp. He had a long history of tinea capitis and tinea corporis infection. Histopathology of the occipital lesions showed mycelial aggregates in the deep dermis and subcutis. Cultures of the excised material and superficial scales grew a fungus identified as Microsporum ferrugineum. We propose the term 'dermatophyte pseudomycetoma' to describe this distinctive mycosis.

Adult↗
PubMed1987

Mood across the menstrual cycle and number of menstrual symptoms reported: a cross-sectional study.

This study assessed mood among 110 women at three phases of the menstrual cycle and its relationship with the number of reported menstrual symptoms. Women who reported fewer menstrually-related symptoms tended to have generally higher mood scores, but specific depression of mood during menses was found among the subgroup of women who reported fewer menstrual symptoms. Contraceptive pill usage was not related to mood variation across the menstrual cycle. The findings raise questions about the validity of self-reports of menstrually-related symptoms.

Adolescent↗
PubMed1983

Stability, characterization, and kinetics of 111In-labeled monoclonal antitumor antibodies in normal animals and nude mouse-human tumor models.

Monoclonal antibodies (MoAbs) against carcinoembryonic antigen were successfully radiolabeled with 111In, and the radiopharmaceutical was characterized in vitro and in normal and tumor-bearing mice. The 111In-MoAb proved to be stable in vitro and in vivo under normal conditions, although instability could be induced in vitro with large quantities of iron-free transferrin. Animal distribution studies with 111In-MoAb demonstrated tumor localization superior to 67Ga and pharmacokinetics that were highly similar to those of endogenously labeled 75Se-MoAb. The 111In-MoAb followed first-order kinetics and fit a two-compartmental model when studied in nude mice bearing human colon tumors known to express carcinoembryonic antigen. Significant quantities of radiolabel appeared in tissues other than tumor, with liver and skin having the highest concentrations. Sufficient tumor/background ratios were formed for scanning purposes. The data indicate that 111In-MoAb may prove to be effective as a radiopharmaceutical for tumor imaging.

Animals↗
PubMed1976

Mechanism of protection from primary bovine viral diarrhea virus infection. I. The effects of dexamethasone.

A series of investigations was designed to study the role of cellular immunity and passive antibody in protecting neonatal calves from primary bovine viral diarrhea virus infection. Administration of corticosteroids (dexamethasone) in doses capable of suppressing cellular immunity markedly potentiated systemic bovine viral diarrhea virus infection in calves which lacked bovine viral diarrhea passive neutralizing antibody. Immunosuppressed calves did not form neutralizing antibody to bovine viral diarrhea virus and developed a fatal viremia. Calves with high levels of passive bovine viral diarrhea neutralizing antibodies were protected from the effect of corticosteroids. The results suggest an essential role for humoral passive antibody, but not for cellular immunity, in protection from primary systemic bovine viral diarrhea virus infection in calves.

Animals↗
PubMed1975

Development of specific in vitro lymphocyte responses in cattle infected with Mycobacterium bovis and with Mycobacterium avium.

Two calves infected with Mycobacterium avium and another 2 with Mycobacterium bovis were studied for development and specificity of lymphocyte activation responses and skin reactivity to purified protein derivatives (PPD). Lymphocytes cultured in vitro from infected calves manifested significant uptake of tritiated thymidine in response to the PPD prepared from the homologous organisms, whereas heterologous PPD produced little or no stimulation. The time of appearance of specifically sensitized lymphocytes was studied, as was the specificity of skin reactivity.

Animals↗
PubMed1975

Development of specific lymphocyte immunostimulation and tuberculin skin reactivity in swine infected with Mycobacterium bovis and Mycobacterium avium.

Swine infected with Mycobacterium bovis and Mycobacterium avium were studied for development and specificity of lymphocyte immunostimulation and tuberculin skin reactivity to purified protein derivatives (PPD) of tuberculins. Lymphocytes from infected animals had maximal blastogenic responses to PPD prepared from the homologous organisms. The time of appearance of specifically sensitized lymphocytes was studied, as was the specificity of skin reactivity. In vitro lymphocyte responses of M avium serotype 1-infected swine to M avium serotype 1 PPD were greater than were the responses of M avium serotype 2-infected swine to the same antigen. Results indicate that the specific stimulation of sensitized lymphocytes might prove useful in the diagnosis of tuberculosis in swine and in differentiating infections due to different serotypes of M avium.

Administration, Oral↗
PubMed1975

Effects of corticosteroids on responses of bovine peripheral blood lymphocytes cultured with phytohemagglutinin.

Corticosteroids given in vivo altered the response of lymphocytes in the peripheral blood of calves. Lymphocytes were cultured and stimulated in vitro with phytohemagglutinin (PHA). After an initial suppression of lymphocyte responses to PHA, there was a rapid return to normal. It is concluded that, in calves, short-term, high-dose immunosuppressive therapy with corticosteroids produces a population of lymphocytes resistant to corticosteroids, possibly by destruction of corticosteroid-sensitive lymphocytes.

Animals↗
PubMed1975

Comparison of lymphocyte stimulation and tuberculin skin reactivity in Mycobacterium bovis-infected Macaca mulatta.

Lymphocyte immunostimulation tests were conducted on Mycobacterium bovis-infected and tuberculin-negative rhesus macaques (Macaca mulatta), using purified protein derivative (PPD) tuberculins prepared from strains of Mycobacterium tuberculosis and Mycobacterium avium. The stimulation of lymphocytes with M tuberculosis PPD was significantly greater for the M bovis-infected macaques than for the noninfected controls (P smaller than 0.05). The response of lymphocytes from M bovis-infected macaques to stimulation with M tuberculosis PPD was greater than the responses to stimulation with M avium PPD (P smaller than 0.01). The results of in vitro lymphocyte stimulation and tuberculin skinreactivity were similar.

Animals↗
PubMed1974

Macrophage-dependent lymphocyte immunostimulation in cattle infected with Mycobacterium bovis and with Mycobacterium avium.

Cultures of bovine peripheral blood leukocytes were prepared from calves inoculated with Mycobacterium bovis and with M. avium. Suitable lymphocyte stimulation was obtained with specific and nonspecific mycobacterial mitogens. Leukocyte cultures depleted of adherent, macrophage-type cells did not respond to stimulation with purified protein derivative, although they were responsive to phytohemagglutinin.

Animals↗