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Biomedical subjects

M C Wang

Publications and source records attributed to M C Wang.

At least 73 records · Page 4Linked to original sources
PubMed1997

Protein tyrosine phosphatase-dependent activation of beta-globin and delta-aminolevulinic acid synthase genes in the camptothecin-induced IW32 erythroleukemia cell differentiation.

Camptothecin, an antitumor drug that specifically targets topoisomerase I, induced IW32 erythroleukemia cells to differentiate along the erythroid pathway, as demonstrated by the increased mRNA and protein expression of hemoglobin. Unlike other chemically induced erythroleukemia cell differentiation, no c-myc mRNA down-regulation was observed in the early phases of drug treatment. Among the heme-synthesizing enzyme mRNAs that were analyzed, only that of the erythroid-specific delta-aminolevulinic acid synthase (ALAS-E) was stimulated. Vanadate or benzylphosphonic acid, which inhibited protein tyrosine phosphatases (PTPase), blocked the camptothecin-induced differentiation. Maximal inhibition was attained if vanadate was added within the first 6 hr of camptothecin treatment, after which vanadate gradually lost its effectiveness. Camptothecin-induced expression of beta-globin or ALAS-E transcript levels was inhibited in the presence of cycloheximide or vanadate. It was also shown that vanadate blocked differentiation of IW32 cells induced by sodium butyrate, VM-26, and p53. Increased PTPase activity could be observed 48 hr after cells were treated with camptothecin, VM-26, or sodium butyrate. Analysis of PTPase activity in the course of camptothecin treatment showed elevated levels of PTPase in the cytosol and the nucleus, with a greater increase demonstrated in the cytosol than in the nucleus. Our results suggest that by stimulating the beta-globin and ALAS-E gene expression, PTPase plays a critical role in the induced differentiation of IW32 erythroleukemia cells.

5-Aminolevulinate Synthetase↗
PubMed1997

Bone mass and hip axis length in healthy Asian, black, Hispanic, and white American youths.

The primary objective of this study was to examine the associations of ethnicity, diet (calcium, protein, energy), and weight-bearing activity with dual-energy X-ray absorptiometry (DXA)-measured bone mass and hip axis length (HAL) in 423 Asians, blacks, Hispanics, and non-Hispanic Caucasians, aged 9-25 years. Bone mass was expressed as bone mineral content (BMC), bone mineral density (BMD), and bone mineral apparent density (BMAD). The data were analyzed using multiple linear regression, after stratifying for gender and pubertal stage and adjusting for height and weight. With few exceptions, Asians and Hispanics had comparable bone mass to whites at all pubertal stages. Greater femoral neck BMAD in black than white females was observed at all pubertal stages. Black males displayed greater BMD and BMAD than white males at all sites in early puberty and at the femoral neck in maturity. Calcium was positively and protein negatively related to BMAD at the femoral neck in early pubertal females. Among males, calcium was negatively associated with whole body BMC and BMD and spine BMD and BMAD in midpuberty. Weight-bearing activity was not associated with bone mass in females; in males, it was positively related only to femoral neck BMC in early puberty. There was an absence of evidence for ethnic differences in HAL among females. In males, we observed shorter HAL in mature Asians and blacks than whites. Neither diet nor activity was associated with HAL.

Absorptiometry, Photon↗
PubMed1997

Neighborhood risk factors for low birthweight in Baltimore: a multilevel analysis.

OBJECTIVES: Past research on low birthweight has focused on individual-level risk factors. We sought to assess the contribution of macrolevel social factors by using census tract-level data on social stratification, community empowerment, and environmental stressors. METHODS: Census tract-level information on social risk was linked to birth certificate records from Baltimore, Md, for the period 1985 through 1989. Individual level factors included maternal education, maternal age, medical assistance health insurance (Medicaid), and trimester of prenatal care initiation. Methods of multilevel modeling using two-stage regression analyses were employed. RESULTS: Macrolevel factors had both direct associations and interactions with low birthweight. All individual risk factors showed interaction with macrolevel variables; that is, individual-level risk factors for low birthweight behaved differently depending upon the characteristics of the neighborhood of residence. For example, women living in high-risk neighborhoods benefited less from prenatal care than did women living in lower-risk neighborhoods. CONCLUSIONS: Multilevel modeling is an important tool that allows simultaneous study of macro- and individual-level risk factors. Multilevel analyses should play a larger role in the formulation of public health policies.

Baltimore↗
PubMed1996

Ethnic differences in immune responses to hepatitis B vaccine.

A national vaccination program against hepatitis B virus (HBV) to immunize every newborn was initiated in Taiwan in 1986. A serologic survey of 1,812 fully vaccinated children residing in four aboriginal villages and four adjacent nonaboriginal Han Chinese rural villages was conducted in 1993. Children in three of the four aboriginal villages had significantly lower titers of antibody against hepatitis B surface antigen (anti-HBs) than did children in the nonaboriginal villages. Evaluation of cold chain operation for vaccine storage and transport suggested that cold chain failure was not responsible for the fact that children residing in the more remote aboriginal villages had lower mean titers of anti-HBs. However, children whose parents were both aborigines had lower anti-HBs mean titer than did children whose parents were both ethnic Han Chinese. Children of mixed parental origins had intermediate mean titer of anti-HBs. Serologic responses to Japanese encephalitis virus and diphtheria vaccines did not show such correlation with ethnic groups, indicating that the determinant for HBV hyporesponsiveness among the aboriginal children is distinct from that of other childhood vaccines. It was therefore concluded that host factors pertaining to ethnic origin might be responsible for the hyporesponsiveness to HBV vaccine in the aboriginal populations. This finding, if substantiated with further prospective studies, might provide possible means for more targeted trials to improve vaccine response and to reduce vaccine failure among these well-defined ethnic groups.

Child↗
PubMed1996

Differences in bone mineral in young Asian and Caucasian Americans may reflect differences in bone size.

Bone mineral content (BMC) and areal bone mineral density (BMD) have been reported to be lower in Asian than in Caucasian adults. To determine if racial differences in bone mass are present in younger subjects and whether they reflect differences in estimated volumetric bone density or in bone size, we compared measurements of bone mineral in healthy young Asian- and Caucasian-American males and females. Bone mineral was measured at the lumbar spine (L2-L4), femoral neck (FN), and whole body (WB) by dual-energy X-ray absorptiometry (DXA) in 99 Asians (49 females, 50 males) and 103 Caucasians (54 females, 49 males) ages 9-26 years. Results were expressed as BMC, BMD, and apparent density (BMAD), an estimate of volumetric bone density that reduces the effect of bone size. Subjects were compared on the basis of chronological age as well as by Tanner stage to correct for potential differences in the timing of puberty. Habitual dietary intake and physical activity were also assessed and correlated with bone mineral. The Asian and Caucasian cohorts differed in body size, diet, and physical activity. Asian females were shorter than the Caucasian females at all stages of puberty and weighed less at pre-/early puberty (p < 0.05). Asian males were older than Caucasians at midpuberty (p < 0.01) and weighed less than the Caucasian males at pubertal maturity (p = 0.001). Asian youths also consumed less calcium and reported less weight-bearing activity. Racial differences were most apparent when comparing BMC data. Asian males had greater spine BMC at midpuberty and lower WB BMC at maturity (p < 0.05). Asian females had lower FN BMC through midpuberty and lower WB BMC in pre-/early puberty (p < 0.05). WB BMD and WB BMC/height values were significantly lower in mature Asian versus Caucasian males. No significant racial differences in BMAD were observed. Multivariate regression analysis indicated that the differences in BMD and BMAD between Asian and Caucasian subjects were largely attributable to differences in weight and pubertal stage, and, at the FN, in weight-bearing activity. Further, the explanatory variables were less strongly associated with BMAD than with BMD. In summary, no significant differences in BMD were found between Asian and Caucasian youths through midpuberty; however, WB BMD and WB BMC/height values were lower in Asian males at sexual maturity. We conclude that observed differences in bone mineral between Asians and Caucasians may be partially attributed to the smaller bone size of Asians.

Absorptiometry, Photon↗
PubMed1996

Regulation of topoisomerase II expression during the VM-26 induced differentiation of IW32 murine erythroleukemia cells.

The effect of VM-26, a topoisomerase II targeting drug, on IW32 murine erythroleukemia cells was investigated. The VM-26 induced IW32 cells to differentiate at a non-toxic but cytostatic concentration (0.01 microgram/ml). More than 40% of the cells were induced to synthesize hemoglobin, and cells were arrested in G2/M phase of the cell cycle. Levels of beta-globin mRNA also increased significantly. Cells became committed to erythroid maturation after 16 h of continuous drug exposure. Replacement with fresh VM-26 after 48 h of drug treatment further increased the hemoglobin containing cells to greater than 80%. Unlike other drug induced erythroleukemia cell differentiation, c-myc mRNA expression was not affected by VM-26. Inhibition of topoisomerase II activity was observed during the first 12 h of VM-26 treatment; however, elevated enzyme activity was found thereafter. Northern blot analysis showed significant increase in the expression of topoisomerase IIalpha mRNA at 12 and 24 h after VM-26 addition. These findings indicate that VM-26 inhibited the activity of topoisomerase II and promoted the committed differentiation of IW32 cells along the erythroid pathway. In addition, a parallel increase in mRNA and activity levels of topoisomerase II in differentiated cells suggests that regulation of the enzyme expression occurred in the VM-26 induced erythroid maturation.

Animals↗
PubMed1996

A semiparametric extension of the Mann-Whitney test for randomly truncated data.

In many applications, statistical data are frequently observed subject to a retrospective sampling criterion resulting in pure right-truncated data. In classical testing problems, the Mann-Whitney test is used for testing the equality of two distributions. A semiparametric extension of this test is developed for the case when truncation is present. We consider a model in which the truncation distribution is parameterized, while the lifetime distribution is left as a nonparametric component. The method is seen to be applicable to many patterns of truncation including left truncation, right truncation, and doubly truncated data for which no other nonparametric or semiparametric test is currently available. Applications of the semiparametric method are given. Simulation results indicate that for pure right-truncated data the semiparametric test is more powerful than a recent nonparametric test.

Acquired Immunodeficiency Syndrome↗
PubMed1996

[Acute uremic pericarditis presented as cardiac tamponade with acute ischemic hepatitis: a case report].

Pericarditis is a frequent and serious complication of chronic uremia. The uremic pericarditis can get much improvement by aggressive heparin-free hemodialysis therapy. However, the presenting symptoms and signs are too nonspecific to identify at early stage. Cardiac tamponade is the late and fatal complication, and need the immediate & adequate management. A 35-year-old female patient suffered from nausea, vomiting and right upper quadrant dull pain in November 1993, and was admitted to a local hospital. Uremia (BUN: 210 mg/dl, serum Cr.: 13.2 mg/dl) and abnormal liver function (SGOT: 330 IU/L, SGPT: 449 IU/L) were found, then she received regular hemodialysis therapy. About 10 days later, acute exacerbation of liver function (SGOT: 2,488 IU/L, SGPT: 1,048 IU/L), consciousness disturbance and hypotension occurred during hemodialysis. She was referred to our ER immediately. At ER, she had been on comatous, shock state with pulseless electric activity. After resuscitation and serial evaluation, cardiac tamponade was diagnosed. Emergent pericardiocentesis and then bilateral partial pericardiectomy were done about 2 hours later. The pericardial effusion was bloody without evidence of malignancy, bacterial or TB infection. The pathology of pericardium revealed chronic inflammation only. HBsAg, Anti-HCV Ab, and anti-HAV IgM were undetectable. So the etiology of acute hepatitis was diagnosed as ischemic hepatitis. Her general condition and vital sign became stable thereafter. The liver function also improved rapidly. She was discharged one month later and received maintainance hemodialysis therapy and no evidence of recurrence till now.

Acute Disease↗
PubMed1995

Preparation of fibrin glue: a study of chemical and physical methods.

Concentrated fibrinogen was prepared from whole blood by cryoprecipitation or chemical precipitation and combined with thrombin to make fibrin glue (FG). Surgical applications of FG include control of bleeding, adhesion of tissues, and sealing of tissue defects. The purpose of this study was to compare cryoprecipitation (cryo) of fibrinogen to precipitation using ethanol, ammonium sulfate (AS), and poly(ethylene glycol) (PEG). Our results suggest that AS precipitation is as effective as cryo in yielding fibrin glues with high bond strengths and is more effective than ethanol and PEG precipitation. In addition, the volume of FG per milliliter of plasma is greater after AS precipitation than after a single freeze-thaw cycle. It is concluded that AS is an efficient means for preparing FG from autologous blood.

Fibrin Tissue Adhesive↗
PubMed1995

Preparation and use of fibrin glue in surgery.

Fibrin glue (FG) is used to control bleeding, to adhere tissues together, and to seal tissue defects. FG is prepared from platelet-rich plasma or by mixing concentrated fibrinogen solutions with thrombin. Concentrated fibrinogen solutions are produced by cryoprecipitation or by chemical precipitation of plasma. The literature on FG preparation is reviewed in order to compare the advantages and disadvantages of the different products reported and to summarize the clinical applications. It is concluded that additional studies are needed to fully evaluate the advantages and disadvantages of fibrinogen concentrated using cryoprecipitation and chemical precipitation and that specific advantages exist for use of both pooled homologous and autologous blood.

Ammonium Sulfate↗
PubMed1995

Violence by male partners against women during the childbearing year: a contextual analysis.

OBJECTIVES: Many contextual analyses that bridge the micro-level-macro-level gap in identifying risk factors for adverse outcomes have not used methods appropriate for multilevel data. The purpose of this paper is to illustrate the application of appropriate multi-level analytic methods and discuss their implications for public health. METHODS: A previously published individual-level model of physical violence perpetrated by male partners during the childbearing year was reanalyzed to include variables describing the neighborhoods where the women resided. Logistic regression with estimation methods of the generalized estimating equation was used for the contextual analysis. To assess the advantages of the generalized estimating equation over conventional logistic regression, both were used for the two-level model. RESULTS: The regression coefficients from the contextual model differed from the betas obtained in the individual-level model. Not only were neighborhood-level variables related to the risk of partner-perpetrated violence, but the presence of these macro-level variables in the models modified the relationships of the individual-level variables to the risk of violence. CONCLUSIONS: Two-level models that include individual- and community-level factors may be beneficial for purposes of explanation in public health research.

Adolescent↗
PubMed1995

Immunity to diphtheria in children three-to-six year of age in four counties of Taiwan.

An immunization program against diphtheria has been implemented in Taiwan since 1955, using combined diphtheria, pertussis and tetanus (DPT) vaccine. Diphtheria immunoglobulin (DIG) level was assessed in serum samples obtained from 1138 children, aged 3-6 years from north, south, east and central part of Taiwan by the VERO cell neutralization method. Specimens were collected by simple random sampling of residents from Hsinchu, Taichung, Pingtung and Hwalien counties, including both aborigines and non-aborigines. The former lived in one or two villages in each county, and the latter lived in a single village next to the former. Ninety-five percent (1086/1138) had a DIG titre > or = 0.01 IU/ml. There was no significant difference by sex, or by residential area. Seventy-nine percent (901/1138) of the children had completed the primary immunization schedule (at the age of 2, 4, 6 and 18 months), and the prevalence of DIG titre > or = 0.1 IU/ml considered to be long-term protective was as follows: 74.6% for 3-year group; 74.5% for 4-year group; 67.9% for 5-year group; 84.7% for 6-year group (including 52.2% who had had a booster shot at early primary school). These findings show that the diphtheria vaccination program provides good immunity in childhood.

Animals↗
PubMed1994

Collagen fibres with improved strength for the repair of soft tissue injuries.

Our laboratory has developed a process for self-assembly of high strength collagen fibres in vitro which exhibit the characteristic D period. These fibres can be cross-linked by severe dehydration (dehydrothermal cross-linking) at elevated temperature and formulated into devices used to repair soft tissues. This study was conducted to evaluate the effects of dehydrothermal cross-linking time and temperature on the tensile mechanical properties of collagen fibres. The results discussed indicate that the tensile strength of reconstituted collagen fibres is optimized by cross-linking for 5 d at 110 degrees C. Tensile strength and modulus values of 91.8 and 896 MPa are reported for fibres cross-linked in this manner. High tensile strength and modulus values are especially important in developing biodegradable materials that promote healing of orthopaedic structures.

Animals↗
PubMed1994

A long-term follow-up study of West syndrome.

BACKGROUND: Since the syndrome of infantile spasms, hypsarrhythmia and mental retardation was first delineated, there have been many publications about long-term prognosis of the West syndrome. This paper evaluates some of the early factors on which long-term prognosis may depend. METHODS: Patients with West syndrome were reviewed retrospectively according to the medical records as classification, response to initial medication regimen, prognosis and present neurological status. Seizure control, speech, psychomotor development, mentality, learning ability, behavior and motor handicap were followed over a mean period of 6.1 years. RESULTS: Thirty patients with complete hospital records were included in this study. Fourteen cases (46.7%) belonged to the symptomatic group, with a mean age of 3.4 months at onset. Four patients (13.3%) were cryptogenic type and a mean age of onset at 9.3 months. There were twelve cases (40%) in the doubtful group, whose mean onset age was 6.4 months. Of the symptomatic group, 92.8% patients had moderate to severe psychomotor retardation as compared to 25% in the cryptogenic group and 67% in the doubtful group; 35.7% of the symptomatic group patients suffered from motor handicap (spastic quadriplegia and hemiplegia as predominated), but only 8.3% of the doubtful group had motor handicap. CONCLUSIONS: The data collected showed that the following factors seemed to be related to better prognosis: later onset, normal to mild psychomotor delay upon diagnosis, and good seizure control.

Female↗
PubMed1993

Nickel chloride inhibits the DNA repair of UV-treated but not methyl methanesulfonate-treated Chinese hamster ovary cells.

Nickel, a human carcinogen, has been shown to enhance the cytotoxicity, mutagenicity, and sister-chromatid exchanges (SCE) induced by ultraviolet (UV) light but not by methyl methanesulfonate (MMS). To verify that the cocytotoxicity and cogenotoxicity of nickel are correlated with its inhibition on DNA repair, the effects of nickel on the DNA repair induced by UV and by MMS have been investigated. Our analyses of DNA repair of single-strand breaks by alkaline elution and alkaline sucrose sedimentation indicate that nickel inhibited the DNA repair in UV-treated, but not in MMS-treated cells. Therefore, the inhibition of DNA repair seems to play an important role in the cocytotoxicity and comutagenicity of nickel. However, the inhibition of DNA repair seems not to play a decisive role in enhancing SCE, because we have previously shown that arsenite inhibits the UV-induced DNA repair, but has no enhancing effect on the UV-induced SCE. Our results also show that nickel had obvious inhibitory effects on DNA ligation and postreplication repair, but had no apparent effect on nucleotide excision and DNA polymerization in the UV repair. The results of the DNA ligation inhibition by nickel in UV but not in MMS repair suggest that different ligases are used in the DNA repair of UV- and MMS-induced damages.

Animals↗
PubMed1993

Preoperative spinal artery localization and its relationship to postoperative neurologic complications.

PURPOSE: To evaluate the risk of spinal cord revascularization and ascertain the relationship between preoperative spinal arteriography and the frequency of postoperative neurologic injury and overall morbidity and mortality in patients who require surgical repair of thoracoabdominal aortic aneurysms. MATERIALS AND METHODS: Fifty patients scheduled for surgical repair of a thoracoabdominal aortic aneurysm underwent spinal arteriography. All patients were divided into a positive spinal artery group (in which the spinal artery was identified) or negative spinal artery group (in which the spinal artery was not identified) and further divided based on extent of disease. RESULTS: The complication rate of spinal arteriography was 4.6%; no patient had a permanent neurologic injury. No significant difference existed between the positive and negative spinal artery groups in occurrence of neurologic injury (P = .88) or combined morbidity and mortality (P = 51). CONCLUSION: Patients who require spinal cord revascularization do not have greater frequency of neurologic injury or overall morbidity and mortality than those without this requirement. Spinal arteriography enables definitive spinal cord revascularization and thereby reduces the risk of neurologic injury.

Adult↗