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Biomedical subjects

C J Chang

Publications and source records attributed to C J Chang.

At least 73 records · Page 4Linked to original sources
PubMed1999

Gender differences in HIV risk behaviors in an adult emergency department in New York City.

BACKGROUND: The human immunodeficiency virus (HIV) epidemic in the US increasingly involves urban heterosexual adults, particularly women, belonging to ethnic minority groups. An understanding of gender-based differences in HIV risk behaviors within these groups would be of value in the ongoing struggle to limit HIV transmission in metropolitan centers. METHODS: This was a prospective study of demographic and historical characteristics and HIV risk behaviors. The study utilized a structured interview format, which was administered to all patients treated by participating emergency department physicians. RESULTS: On univariate analysis of data obtained from 1,460 patients who had neither a known HIV infection nor a chief complaint or final emergency department diagnosis associated with HIV risk behaviors, men were more likely to be older, homeless, to have ever injected drugs, used crack, engaged in same-gender sex, paid for sex, been incarcerated, or had syphilis or gonorrhea. Women were more likely to report prior chlamydia infection or to report that their sole sex partners had other partners within the past year. On multivariate analysis, variables independently associated with male gender included homelessness, injection drug use, crack use, any prior sexually transmitted disease (in subjects 35 years of age or older), and sex with prostitutes. In a separate analysis of patients admitting to drug use, the male predominance of other risk behaviors was not observed; the only significant differences between genders were a higher rate of prostitution among women and a higher rate of sexual contact with a prostitute among men. CONCLUSIONS: In patients visiting an inner-city emergency department in the Bronx, HIV risk behaviors are generally more common in men, but rates of risk behaviors among male and female drug users are comparable.

Adult↗
PubMed1999

Microvascular vastus lateralis muscle flap for chronic empyema associated with a large cavity.

Thoracic empyema can be disabling and may need microvascular free flaps in some intractable cases. After repeated failure of conventional thoracic surgical procedures, 2 patients with empyema were treated with microvascular free vastus lateralis muscle flaps for obliteration of the large empyema cavity. The reconstruction was successful in wound closure and eradication of infection. The donor site morbidity was minimal, and the patients resumed normal daily activities. Microvascular vastus lateralis muscle flap is the best option if free flaps are required for reconstruction of empyema.

Aged↗
PubMed1999

Hepatitis C virus infection among short-term intravenous drug users in southern Taiwan.

The purpose of this study was to determine the correlation between the prevalence of hepatitis C virus (HCV) infection with duration of drug use and other risk factors among drug users. This survey covered 899 male drug users from Kaohsiung Narcotic Abstention Institute and Kaohsiung prison. The prevalence of positive anti-HCV was 67.2% among intravenous drug users (IVDU) and 14.7% among non-intravenous drug users (non-IVDU). Among intravenous (IV) drug users, age and duration of drug use were independently related to HCV seropositivity. Seroprevalence rate for HCV in the IVDU group increased with increasing duration of injection use within the first seven years of drug use. However, the steepest trajectory in seroprevalence of HCV infection occurred within the first four months. Due to the high rate of HCV infection among drug users, investigation of risk behaviors should be routine in such a group. A high frequency of HCV infection was also found among short-term injectors, which indicated that early risk reduction intervention was an important measure in moderating HCV infection.

Adolescent↗
PubMed1999

Cryogen spray cooling and higher fluence pulsed dye laser treatment improve port-wine stain clearance while minimizing epidermal damage.

BACKGROUND: When a cryogen spurt is applied to the skin surface for an appropriately short period of time (on the order of tens of milliseconds), the cooling remains localized in the epidermis, while leaving the temperature of the deeper port-wine stain (PWS) blood vessels unchanged. OBJECTIVE: The objective of this study was to compare the efficacy and safety of noncooled laser treatment (NC-LT), and cryogen spray cooled laser treatment (CSC-LT) of PWS birthmarks in a large series of patients. METHODS: A retrospective review was conducted of 196 patients with head or neck PWS birthmarks treated with the pulsed dye laser (lambda = 585 nm; taup = 450 microseconds) over a 7-year period. Subjects' ages ranged between 2 months and 62 years; there were 109 females and 87 males, all of whom were Asian. Ninety-eight patients received NC-LT using light dosages of 5-7 J/cm2. Subsequently, 98 patients received CSC-LT using light dosages of 8-10 J/cm2. The primary efficacy measure was the quantitative assessment of the blanching response scores of NC-LT PWSs as compared, on a blinded basis, to CSC-LT PWSs. RESULTS: Based on chi-squared analysis, there were clinical, and statistically significant, differences in the blanching response scores favoring PWS receiving CSC-LT as compared to the NC-LT group (P <.001). Permanent scarring was noted in 3.1% (n = 3) of the patients in the NC-LT group. Permanent scarring was not observed in the CSC-LT treatment group. Transient hyperpigmentation was noted in 57% (n = 56) and 48% (n = 47) of the patients in the NC-LT and CSC-LT groups, respectively. In both groups, the transient hyperpigmentation resolved in all patients within 1 year. Two patients in the NC-LT group developed delayed permanent hypopigmentation. Permanent hypopigmentation was not observed in the CSC-LT group. CONCLUSION: CSC permitted the use of higher incident light dosages leading to improved PWS clearance without producing complications such as permanent scarring or dyspigmentation.

Adolescent↗
PubMed1999

Intralesional photocoagulation of vascular anomalies of the tongue.

Vascular anomalies remain a challenge for patients and reconstructive surgeons. Recently, promising results have been reported using intralesional photocoagulation (ILP) to treat large, deep vascular lesions. We report our experience in treating 12 patients with vascular anomalies of the tongue (10 venous malformations and two haemangiomas) using intralesional photocoagulation. All patients were treated with a Nd:YAG (neodymium:yttrium-aluminium-garnet) (1064 nm) laser (Sharplan, Inc., NJ, USA) delivered with a 600 microns optical fibre. Laser power was set at 7 or 10 W, delivered with a pulse duration of 10 s. Laser energy was delivered to all areas of the vascular lesion. Heat, visible shrinkage and firmness of the lesion signalled the end-point of treatment. The mean follow-up period was 9.5 months (range 3-20 months). All patients demonstrated improvement as judged by a clinical assessment of the reduction in lesion size (mean reduction = 87%, range 60-100%). Three patients (25%) had complications attributed to photocoagulation. Energy delivered too superficially resulted in ulceration or scarring. These complications should be avoidable if this potential for harm is kept in mind.

Adult↗
PubMed1999

The effect of cotinine or cigarette smoke co-administration on the formation of O6-methylguanine adducts in the lung and liver of A/J mice treated with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)

4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a tobacco-specific nitrosamine, induces lung adenomas in A/J mice, following a single intraperitoneal (i.p.) injection. However, inhalation of tobacco smoke has not induced or promoted tumors in these mice. NNK-induced lung tumorigenesis is thought to involve O6-methylguanine (O6MeG) formation, leading to GC-->AT transitional mispairing and an activation of the K-ras proto-oncogene in the A/J mouse. NNK can be metabolized by several different cytochromes P450, resulting in a number of metabolites. Formation of the promutagenic DNA adduct O6MeG is believed to require metabolic activation of NNK by cytochrome P450-mediated alpha-hydroxylation of the methylene group adjacent to the N-nitroso nitrogen to yield the unstable intermediate, methanediazohydroxide. Nicotine, cotinine (the major metabolite of nicotine), and aqueous cigarette tar extract (ACTE) have all been shown to effectively inhibit metabolic activation of NNK to its mutagenic form, most likely due to competitive inhibition of the cytochrome P450 enzymes involved in alpha-hydroxylation of NNK. The objective of the current study was to monitor the effects of cotinine and cigarette smoke (CS) on the formation of O6MeG in target tissues of mice during the acute phase of NNK treatment. To test the effect of cotinine, mature female A/J mice received a single intraperitoneal injection of NNK (0, 2.5, 5, 7.5, or 10 mumole/mouse) with cotinine administered at a total dose of 50 mumole/mouse in 3 separate i.p. injections, administered 30 min before, immediately after, and 30 min after NNK treatment. To test the effect of whole smoke exposure on NNK-related O6MeG formation, mice were exposed to smoke generated from Kentucky 1R4F reference cigarettes at 0, 0.4, 0.6, or 0.8 mg wet total particulate matter/liter (WTPM/L) for 2 h, with a single i.p. injection of NNK (0, 3.75, or 7.5 mumole/mouse) midway through the exposure. Cigarette smoke alone failed to yield detectable levels of O6MeG. The number of O6MeG adducts following i.p. injection of NNK was significantly (p < 0.05) reduced in both lung and liver by cotinine and by cigarette smoke exposure. Our results demonstrate that NNK-induced O6MeG DNA adducts in A/J mice are significantly reduced when NNK is administered together with either cotinine, the major metabolite of nicotine, or the parental complex mixture, cigarette smoke.

Animals↗
PubMed1999

Intralesional photocoagulation of periorbital hemangiomas.

The purpose of this study was to examine the effects of intralesional bare fiber photocoagulation with the KTP and Nd:YAG lasers on periorbital hemangiomas of infancy. Initial reports by Apfelberg and Gregory suggest that intralesional laser therapy may have a role in the treatment of hemangiomas. Intralesional photocoagulation may be preferred to superficial laser treatment for several reasons. It may decrease cutaneous skin damage and more effectively reduce bulky, deep lesions. Twenty-three patients with periorbital hemangiomas were treated (KTP, n = 7; Nd:YAG, n = 16). An 18-g Angiocath was placed into the lesion to pass the fiber through. Laser energy was delivered by means of a 0.6-mm bare fiber at 10 to 15 J (KTP) or 7 J (Nd:YAG). Treatments were done under general anesthesia. Patients were followed closely for 1 month and then monthly to assess results and complications. Results are as follows: 61 percent demonstrated 50-percent or more reduction at 3 months; 22 percent demonstrated 50-percent or more reduction in 3 to 8 months, i.e., 83 percent of patients had 50-percent or more reduction within 8 months. To achieve these results, two patients required two treatments. The remaining 17 percent had 10- to 14-percent reduction at 1 to 3 months. Two of these patients had two treatments. A subgroup of patients had a very dramatic response. Thirty-five percent (8 of 23) had 50- to 90-percent reduction in 1 month. It is unclear why these patients responded so dramatically. We expected some ulceration during the healing phase. Seventeen percent developed ulceration. Complications were limited (4 percent) to one wound infection. Intralesional photocoagulation treatment with the KTP and Nd:YAG lasers is effective and safe for the treatment of periorbital hemangiomas in the majority of patients with minimal complications. Further study is necessary to identify factors that result in dramatic or limited responses.

Hemangioma↗
PubMed1999

Double-stranded linear duck hepatitis B virus (DHBV) stably integrates at a higher frequency than wild-type DHBV in LMH chicken hepatoma cells.

Integration of hepadnavirus DNAs into host chromosomes can have oncogenic consequences. Analysis of host-viral DNA junctions of DHBV identified the terminally duplicated r region of the viral genome as a hotspot for integration. Since the r region is present on the 5' and 3' ends of double-stranded linear (DSL) hepadnavirus DNAs, these molecules have been implicated as integration precursors. We have produced a LMH chicken hepatoma cell line (LMH 66-1 DSL) which replicates exclusively DSL duck hepatitis B virus (DHBV) DNA. To test whether linear DHBV DNAs integrate more frequently than the wild type open circular DHBV DNAs, we have characterized the integration frequency in LMH 66-1 DSL cells by using a subcloning approach. This approach revealed that 83% of the LMH 66-1 DSL subclones contained new integrations, compared to only 16% of subclones from LMH-D2 cells replicating wild-type open circular DHBV DNA. Also, a higher percentage of the LMH 66-1 DSL subclones contained two or more new integrations. Mathematical analysis suggests that the DSL DHBV DNAs integrated stably once every three generations during subcloning whereas wild-type DHBV integrated only once every four to five generations. Cloning and sequencing of new integrations confirmed the r region as a preferred integration site for linear DHBV DNA molecules. One DHBV integrant was associated with a small deletion of chromosomal DNA, and another DHBV integrant occurred in a telomeric repeat sequence.

Animals↗
PubMed1999

Gender differences in the presentation of adult obstructive hypertrophic cardiomyopathy with resting gradient: a study of 122 patients.

The present study investigated gender differences among adult patients with obstructive hypertrophic cardiomyopathy (OHCM) and resting gradient. Using outflow gradients >10 mmHg and the presence of asymmetrical septal hypertrophy of the left ventricle as inclusion criteria, 122 patients were identified among patients referred for echocardiographic examinations between May 1990 and October 1996. Clinical, echocardiographical and follow-up data were compared between male and female patients. The female patients were significantly older than male patients (mean age +/-SD 66.7+/-10.5 vs 54.8+/-12.5 years). The female patients had a smaller interventricular septal wall thickness, less frequent systolic anterior movement of the mitral valve, more frequent association with hypertension, and less frequent association with ischemic heart disease (IHD) and giant T wave inversion. In this study population, adult female patients presented with OHCM 12 years later than males. Whether this represents female patients' reluctance to seek medical attention early, a different disease process that affects predominantly elderly females, or a gender-specific end organ response to aging, hypertension, IHD and other processes, or the protective effects of estrogen remains to be determined.

Adolescent↗
PubMed1999

Discriminating glucose tolerance status by regions of interest of dual-energy X-ray absorptiometry. Clinical implications of body fat distribution.

OBJECTIVE: To determine whether measuring body fat distribution by dual-energy X-ray absorptiometry (DEXA) can be used to discriminate glucose tolerance status. RESEARCH DESIGN AND METHODS: Using a 75-g oral glucose tolerance test, a total of 1,015 Chinese subjects (559 men and 456 women) were categorized as having normal glucose tolerance (NGT), impaired glucose tolerance (IGT), or diabetes. Blood pressure and lipid profiles of these subjects were measured. Waist-to-hip ratio (WHR) and DEXA were used to evaluate the varying patterns of body fat distribution among the groups. RESULTS: Body fat distribution, as reflected by WHR and the centrality index, showed significant partial correlation coefficients with glycosylated hemoglobin, blood pressure, and lipid profiles in all subjects. After adjusting for age and BMI, there were significant differences among the three glycemic groups for all the cardiovascular risk factors except for total cholesterol level. The diabetic group had a significantly higher WHR and centrality index, but lower femoral fat percentage than the NGT and IGT groups. The diabetic group also showed higher abdominal fat percentage than the NGT group. Moreover, the IGT group had a higher centrality index than the NGT group. However, no significant differences were found in the percentage of lean tissue mass among the three groups. Using multiple stepwise logistic regression models, the centrality index remained a significant factor for discriminating different glucose tolerance status independent of the percentage total body fat. CONCLUSIONS: Central obesity has shown significant correlation with cardiovascular risk factors among the three different glycemic groups. Centrality index measured by DEXA appears to be the better predictor of glucose intolerance, compared with WHR, abdominal fat, and general obesity (reflected by percentage total body fat or BMI) in a large cohort of the Chinese population.

Absorptiometry, Photon↗
PubMed1999

In vitro and in vivo photosensitizing capabilities of 5-ALA in vascular endothelial cells.

BACKGROUND: The object of our study is to evaluate the feasibility of photodynamic therapy for complicated hemangiomas. We studied the effect of the photosensitizing agent 5-aminolevulinic acid (5-ALA) in both in vitro and in vivo models. METHODS: The in vitro photosensitizing activity of 5-ALA was examined in a microvascular endothelial cell (MEC) culture system. 5-ALA was added in various concentrations and the cells were illuminated at 630 nm. The percentage of MEC killed was measured by either a Live/Dead assay or an lactate dehydrogenase (LDH) assay. The effect of varying the light energy dose delivered at 630 nm after the administration of 5-ALA was studied by determining the amount of necrosis produced in chicken combs. RESULTS: The combination of 5-ALA at a concentration of 35 micrograms/ml, and illumination by 100 mW/cm2 of laser light at 630 nm wavelength, caused 50% cell kill in the MEC culture system. Chicken combs of animals that received 200 mg/kg of 5-ALA and illumination at a power density of 80 mW/cm2 had a depth of injury of 362.5 +/- 27.6 microns upon histological examination. Those combs that received 100 or 120 mW/cm2 showed a depth of injury of 732.5 +/- 29.1 and 792.5 +/- 36.0 microns respectively. CONCLUSION: 5-ALA is effective in sensitizing human MEC to laser illumination. However, the degree of absorption and tissue destruction in different anatomical structures should be considered in future clinical studies.

Aminolevulinic Acid↗
PubMed1999

Vulvovaginal reconstruction following radical tumor resection: report of 12 cases.

BACKGROUND: The absence of the vulva and vagina is a distressful problem, especially for the sexual life of a woman. The potential benefit associated with the use of various vaginal reconstructive methods was studied. METHODS: Between April 1987, and June 1997, 12 patients undergoing gynecologic carcinoma surgery were treated with simultaneous vulvovaginal reconstruction using local labia majora flaps (1), gracilis myocutaneous flaps (3), and innervated pudendal-thigh flaps (8). RESULTS: The mean follow-up period was 32 months. There were no major surgical complications, with the exception of one patient who had a ureteroileal fistula after bilateral gracilis myocutaneous flap reconstruction and radiotherapy. One patient received pelvic radiation after bilateral gracilis myocutaneous flap reconstruction, and the complication of perineal bleeding occurred 90 days after the vaginal reconstruction. Another patient had introital stenosis of the neovagina after reconstruction using bilateral labia majora flaps. Seven patients had regular and satisfactory sexual lives. These patients were all treated by innervated pudendal-thigh flap reconstruction. CONCLUSION: The innervated pudendal-thigh flap provides a sensitized flap for reconstruction of the vulva and vagina following vulvovaginal carcinoma surgery. For extended carcinoma with vulvovaginal involvement, the gracilis myocutaneous flap is would be better for reconstruction of a large defect.

Adult↗
PubMed1999

Obstructive hypertrophic cardiomyopathy in Taiwanese adults.

The purpose of this study was to analyze the clinical profiles, echocardiographic findings, and mortality among adult Taiwanese patients with obstructive hypertrophic cardiomyopathy (HCM) at Chang Gung Memorial Hospital, a university-affiliated tertiary referral center in suburban Taipei. We reviewed the medical records of all adult (> 15 years of age) patients referred to our laboratory for echocardiographic examinations of cardiac diseases from May 1990 through December 1996. The diagnosis of obstructive HCM required an outflow gradient of above 10 mm Hg and the presence of asymmetric septal hypertrophy of the left ventricle. Follow-up information on was obtained from hospital records, questionnaires, interviews, or the National Death Certificate Registry. Of the 6.798 adults who underwent echocardiographic examinations during the study period 122 (1.79%) had obstructive HCM. The mean +/- standard deviation age of the patients was 62.2 +/- 12.6 years, and females predominated (n = 76, 62.3%). During the mean follow-up period of 3.2 years, the annual all-cause mortality rate was 4.7%. Most deaths were due to concurrent medical conditions. The annual cardiac mortality rate was 0.99%. Logistic regression analysis identified medication with calcium channel blockers as the only negative predictor (relative risk = 0.26, 95% confidence interval = 0.07-0.96) of all-cause mortality, and left atrial size as the only positive predictor (relative risk = 1.18, 95% confidence interval = 1.02-1.37) of cardiac mortality. Cox regression analysis confirmed the former association, but not the latter. Thus, in our institution, obstructive HCM had a low prevalence among adult patients referred for echocardiographic examination. These patients were elderly and often had other associated medical conditions. The high all-cause mortality rate was largely due to non-cardiac causes. These findings suggest that obstructive HCM tends to have a benign clinical course. Large atrial size could be an independent predictor of cardiac mortality, but this possibility requires further confirmation.

Aged↗
PubMed1998

Sympathetic hyperactivity in Wistar rats with insulin-resistance.

In an attempt to know the effect of sustained hyperinsulinemia on sympathetic function, plasma norepinephrine (NE) and glucose levels were measured in Wistar rats with insulin resistance. Both the basal plasma glucose and the plasma NE levels in insulin-resistant rats were markedly higher than that obtained in normal or streptozotocin (STZ)-induced diabetic rats. Treatment with guanethidine and prazosin reversed these sympathetic hyperactive responses in insulin-resistant rats. Moreover, increase of plasma insulin in rats receiving an intraperitoneal glucose challenge test confirmed the mediation of endogenous insulin in this sympathetic hyperactivity. These results suggest an increase of sympathetic activity in insulin-resistant state that may be related to the hypertension-prone associated with diabetes mellitus in clinics.

Adrenergic alpha-Antagonists↗
PubMed1998

A prospective study of tuberculosis and HIV disease progression.

OBJECTIVE: To determine whether active tuberculosis alters the rate of progression of HIV infection in dually infected patients. METHODS: HIV-seropositive patients at two Bronx, New York hospitals with tuberculosis confirmed by culture from July 1992 to February 1995, who survived the initial hospitalization for tuberculosis, were matched on gender, age, CD4+ percentage, and calendar time with HIV-seropositive patients without tuberculosis participating in a study of the natural history of HIV infection. Patients received follow-up observation prospectively until May 23, 1995 to determine survival rates and development of AIDS-defining opportunistic infections (OIs). RESULTS: 70 patients had tuberculosis; 120 did not. Mean CD4+ percentages were 12.4% and 12.5%, respectively. At study entry, 27% of those with tuberculosis had prior AIDS-defining OIs other than tuberculosis, compared with 10% of those without tuberculosis (p = .004). In multivariate survival analysis, controlling for CD4+ level, tuberculosis was not an independent predictor of increased other causes of AIDS-related mortality. However, in a logistic regression model, independent predictors of subsequent OIs included tuberculosis (hazard ratio, 4.1; 95% confidence intervals [CI], 1.9, 8.7), CD4+ count <100/mm3 (hazard ratio, 2.4; 95% CI, 1.1, 5.0) and prior OIs (hazard ration, 3.3; 95% CI, 1.3, 8.3). CONCLUSIONS: Tuberculosis was not an independent predictor of increased non-tuberculosis-related mortality in HIV-seropositive patients but was associated with increased risk of development of OIs.

AIDS-Related Opportunistic Infections↗
PubMed1998

Novel protein kinase C inhibitors: alpha-terthiophene derivatives.

A series of alpha-terthiophene derivatives were prepared and their protein kinase C inhibitory activity were evaluated. The aldehyde derivatives were most potent inhibitors (IC50 < 1 microM). alpha-Terthiophene monoaldehyde was inactive in the inhibitions of protein kinase A, mitogen activated protein kinase and protein tyrosine kinase.

Enzyme Inhibitors↗
PubMed1998

Chimeric human-mouse IgG antibodies with shuffled constant region exons demonstrate that multiple domains contribute to in vivo half-life.

Structural features that determine the differing rates of immunoglobulin catabolism are of great relevance to the engineering of immunologically active reagents. Sequences in the CH2 and CH3 region of IgG have been shown to regulate the rate of clearance through their interaction with FcRn. In an attempt to probe additional structural features that regulate antibody half-life, we have investigated two families of chimeric antibodies, composed of identical murine heavy and light antidansyl variable regions joined to human kappa light-chains and wild-type or shuffled human IgG heavy-chain constant regions. These antibodies were iodinated, and their clearance was studied in severe combined immunodeficient mice hosts by whole-body radioactivity measurements. Clearances of the wild-type and recombinant antibodies were biphasic. In a panel of immunoglobulins derived from IgG2 and IgG3, as successive domains were varied from gamma2 to gamma3, beta-phase half-life gradually decreased from 337.0 h to 70.6 h. Statistical analysis suggested that the composition of each of the three domains affected half-life, and no single region of the molecule by itself determined the rate of clearance. In the second panel of immunoglobulins derived from IgG1 and IgG4, the construct with the amino terminus portion of the molecule derived from IgG4, joined within the CH2 domain to the COOH terminus portion of IgG1, had a half-life paradoxically greater than either IgG1, or IgG4 (P < 0.012). All four IgG1/IgG4 constructs demonstrated presence of the concentration catabolism phenomenon, which is a unique hallmark of immunoglobulin catabolism. The contribution of all three constant region domains to immunoglobulin half-life may be due to distant conformational effects in addition to direct binding to protective receptors, and emphasizes the importance of distant sequences on the rate of immunoglobulin catabolism. Interesting possibilities regarding mechanisms controlling immunoglobulin metabolism are raised by the hybrid gamma4/gamma1 molecule with a half-life greater than either parental immunoglobulin. Understanding the relationships between the structure of these molecules and their clearance rate will further our ability to produce immunoglobulins with improved pharmacokinetic properties.

Animals↗