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Biomedical subjects

J C Chang

Publications and source records attributed to J C Chang.

At least 55 records · Page 3Linked to original sources
PubMed1998

Guillain-Barré syndrome: MR imaging findings of the spine in eight patients.

PURPOSE: To evaluate magnetic resonance (MR) imaging findings of the spine in patients with Guillain-Barré syndrome. MATERIALS AND METHODS: MR imaging findings in eight patients (three male, five female; age range, 2-47 years) with Guillain-Barré syndrome were retrospectively reviewed. Guillain-Barré syndrome was diagnosed mainly on the basis of symptoms and also on the basis of supportive ancillary data, such as the results cerebrospinal fluid analysis and electrophysiologic evaluation. In addition, follow-up MR imaging was performed in three patients, who had slight clinical improvement. RESULTS: All patients had thickening of the intrathecal spinal nerve roots and cauda equina, with varying degrees of enhancement on gadolinium-enhanced axial T1-weighted images. Two enhancement patterns were noted. One was enhancement of both the anterior and posterior spinal nerve roots (n = 2); the other was enhancement of the anterior spinal nerve roots only (n = 6). Follow-up MR imaging in the three patients with slight improvement of symptoms revealed that the thickening and the degree of enhancement of the spinal nerve roots were diminished. CONCLUSION: Although the enhancement of the intrathecal spinal nerve roots is not specific to Guillain-Barré syndrome and can be seen in neoplasia and other inflammatory processes, the enhancement of only the anterior spinal nerve roots is strongly suggestive of Guillain-Barré syndrome.

Adolescent↗
PubMed1998

Hepatic cavernous hemangioma: sonographic patterns and speed of contrast enhancement on multiphase dynamic MR imaging.

OBJECTIVE: Our purpose was to investigate a correlation between the speed of contrast enhancement in patients with hepatic cavernous hemangioma revealed by dynamic MR imaging and the internal echo pattern revealed by sonography. MATERIALS AND METHODS: Forty-five patients underwent multiphase IV contrast-enhanced dynamic MR imaging that revealed 71 hepatic cavernous hemangiomas less than 4 cm in diameter; the MR findings were compared with the sonographic findings in these patients. On MR imaging, the hemangiomas were classified as rapid-, intermediate-, and slow-enhancing. We classified sonographic features as hypoechoic, iso- or mixed-echoic, and hyperechoic according to the relative echogenicity seen between lesions and the surrounding hepatic parenchyma. Sonographic patterns and MR imaging findings of individual lesions were then compared. RESULTS: Rapid-enhancing hemangiomas revealed on dynamic MR imaging tended to be hypoechoic on sonography (18/24, 75%; p = .0143), and lesions that were slow-enhancing on MR imaging tended to be hyperechoic (26/29, 90%; p < .0001). Hypoechoic lesions on sonography tended to be rapid-enhancing on dynamic MR imaging (18/18, 100%). Likewise, hyperechoic lesions on sonography tended to be slow-enhancing on MR imaging (26/33, 79%; p = .0009). CONCLUSION: In most patients with hepatic cavernous hemangiomas, we found that the speed of contrast enhancement on multiphase dynamic MR imaging enabled us to predict the echo pattern in sonography and vice versa.

Contrast Media↗
PubMed1998

Silicoating in resin-metal bonding: restorative implications for osseointegrated implant-bone unison.

Detailed background information leading to the development of a silicoating technique is presented with its advantages and disadvantages and its role in implant dentistry. The rationale is shown for coining a new acronym "osseointegrated Implant-Bone Unison" with an interest in biomechanical considerations for a prosthodontic restorative scenario. Several clinical cases are presented that involve silicoating and composite restorations.

Composite Resins↗
PubMed1998

Partial trisomy 13 [46,XY,dup(13)(q14-31)]: a case report.

We report a fetus with partial trisomy 13 [46,XY,dup(13)(q14-31)] which was found during an amniocentesis performed due to the age of the mother. This duplication segment (13q 14-31) has not been reported in literature. The clinical features of our patient included cleft lip/palate, low set ears, depressed nasal bridge, hypertelorism, and epicanthal fold. After termination of the pregnancy, the fetus was sent for an autopsy. The autopsy report was compatible with the gross findings and no other abnormalities, including central nervous, cardiac, and renal system, were found. The level of maternal alpha-fetoprotein, 2.67 MoM, was opposite with the common phenomenon in complete trisomy 13.

Adult↗
PubMed1998

Hybrid total knee arthroplasty: a 3- to 6-year outcome analysis.

We retrospectively analyzed the outcomes of hybrid total knee arthroplasty (TKA) with Miller Galante I (MG I) prostheses in 113 consecutive patients (140 knees). The mean follow-up period was 4.8 years (range 3.2-6.6). There were 135 cases of osteoarthritis and five of rheumatoid arthritis. The average age of patients at the time of surgery was 62.6 years. The Hospital for Special Surgery knee score along with radiographs were used to evaluate preoperative and postoperative knee status, and the Cybex isokinetic test was used to assess muscle strength at the final follow-up. The average knee score improved from 64 points preoperatively to 90 points postoperatively (p < 0.05). The mean motion are of the knee improved from 108 degrees preoperatively to 116 degrees at the final evaluation. A total of 122 knees were pain free on walking and 130 knees were completely pain free at rest. A total of 134 knees achieved good to excellent clinical results. The radiographic results showed that the mechanical axis of the lower extremity was realigned from a mean of 12 degrees varus preoperatively to a mean of 1 degree varus postoperatively. No obvious radiolucent zones were found on the lateral view of the femoral components in 60.7% of the knees, or on the anteroposterior or lateral views around the tibial components in 49.3% and 82.9% of knees, respectively. The Cybex isokinetic test at the final follow-up examination revealed that the hamstring/quadriceps peak torque ratio was 0.8 at a speed of 60 degrees per second and 0.96 at 180 degrees per second, indicating that quadriceps muscle strength did not recover to within the range of healthy subjects. There were 23 (16.4%) complications, including polyethylene wear of patellar components (14), patellofemoral maltracking (4), septic loosening (2), aseptic loosening (2), and superficial infection (1). Revision surgery improved the functional outcomes in all of these knees. Based on our experience, we do not recommend the use of the MG I prosthesis in total knee arthroplasty (TKA) because of the high rate of patellar complications. Strengthening of the quadriceps must be emphasized in postoperative rehabilitation. Hybrid fixation might be a useful alternative fixation mode in TKA procedures.

Adult↗
PubMed1998

Evaluation of sink effects on VOCs from a latex paint.

The sink strength of two common indoor materials, a carpet and a gypsum board, was evaluated by environmental chamber tests with four volatile organic compounds (VOCs): propylene glycol, ethylene glycol, 2-(2-butoxyethoxy)ethanol (BEE), and Texanol. These oxygenated compounds represent the major VOCs emitted from a latex paint. Each chamber test included two phases. Phase 1 was the dosing/sorption period during which sink materials (pieces of carpet and gypsum board samples) were exposed to the four VOCs. The sink strength of each material tested was characterized by the amount of the VOCs adsorbed or absorbed. Phase 2 was the purging/desorption period during which the chambers with the dosed sink materials were flushed with purified air. The reemission rates of the adsorbed VOCs from the sinks were reflected by the amount of the VOCs being flushed. Phase 1 results indicated that the sink strength for the four target compounds is more than 1 order of magnitude higher than that for other VOCs previously tested by the U.S. Environmental Protection Agency (EPA). The high sink strength reflected the unusually high sorption capacity of common indoor materials for the four VOCs. Phase 2 results showed that reemission was an extremely slow process. If all the VOCs adsorbed were reemittable, it would take more than a year to completely flush out the VOCs from the sink materials tested. The long reemission process can result in chronic and low-level exposure to the VOCs after painting interior walls and surfaces.

Air Pollution, Indoor↗
PubMed1998

Trends in cancer incidence and mortality in Missouri.

BACKGROUND: Cancer is the second leading cause of death in Missouri. Several factors influence public health planning and policy-making decisions, including assessment of the trends in disease and in related risk factors, of overall disease burden on the population, and of the effectiveness of intervention programs. To assess the influence of statewide cancer screening, education, and intervention programs on Missouri's cancer burden, recent trends in cancer incidence and mortality rates among Missourians were analyzed. METHODS: Age-standardized cancer incidence rates from 1985-1992 and cancer mortality rates from 1985-1994 and 1990-1996 were calculated by race, age group, and sex using data collected by the Missouri Cancer Registry and the Missouri Center for Health Statistics. Rates for each year examined were logged and regressed onto year. RESULTS: Between 1985 and 1992, the rate of cancer incidence increased by 16.1% (p < .05). From 1985-1994, cancer mortality rate increased by 3.5% (p < .05). Mortality among males, however, decreased between 1990 and 1996. This decrease was particularly pronounced among African-American males. Missouri males endured greater incidence of and mortality from cancer than Missouri females. Elderly males (both African American and white) exhibited the greatest increase in cancer incidence over the periods examined (+27.3% and +31.8% increase respectively, p < .05). Racial differences were nonexistent for cancer incidence rates, but the cancer mortality rate for African Americans was 45% greater than that for whites. CONCLUSIONS: Although Missouri cancer incidence and mortality rates are higher now compared to 16 years ago, data are presented that indicate a slight decline in mortality rates over the past six years. The recent decline (1990-96) in mortality was present only among men, particularly African-American men. The incidence increase was particularly important for women. Despite the implementation of some programs designed to target minorities and undeserved populations at greater risk, these data indicate that large demographic differences in cancer incidence and mortality still persist. A greater commitment to cancer screening, access to treatment, and cancer prevention programs are necessary to meet Missouri's year 2000 goals for cancer incidence and mortality.

Adolescent↗
PubMed1998

Effect of postprepared sperm parameters and insemination specimen volume on the outcome of intrauterine insemination.

BACKGROUND: The purpose of the present study was to identify the postprepared sperm parameters affecting the outcome of intrauterine insemination and to find out whether the volume of insemination specimen was a determinant factor in the rate of successful conception. MATERIALS AND METHODS: A retrospective study including 306 couples was designed. The patients were inseminated with either 1.0 or 0.5 ml of prepared specimens. The pregnancy rates were compared using the chi-square test. Logistic regression was chosen for multivariant analysis of the parameters. RESULTS: The only parameter significantly affecting the success rate was the postprepared sperm motility (p = 0.033). The pregnancy rate was 27.91% in cases with > or = 95% sperm motility. Only two patients with less than 75% sperm motility conceived. The pregnancy rates in cases with 0.5 ml and 1.0 ml inseminations were 12.12% and 16.13%, respectively. This difference was statistically insignificant (p = 0.427). CONCLUSION: The postprepared sperm motility was the only parameter predicting the successful rate of intrauterine insemination. Seventy-five percent sperm motility can be used as a cut-off value for selecting patients. The volume of insemination specimen did not influence the outcome. Insemination with 1 ml of fluid was just as effective as insemination with 0.5 ml.

Female↗
PubMed1997

Tissue-specific expression of herpes simplex virus thymidine kinase gene delivered by adeno-associated virus inhibits the growth of human hepatocellular carcinoma in athymic mice.

About 70% of hepatocellular carcinomas are known to express alpha-fetoprotein, which is normally expressed in fetal but not in adult livers. To induce herpes simplex virus-thymidine kinase expression in these cancer cells, we constructed an adeno-associated viral vector containing the HSV-TK gene under the control of the alpha-fetoprotein enhancer and albumin promoter. We previously demonstrated in vitro that although this vector can transduce a variety of human cells, only transduced AFP and albumin-expressing hepatocellular carcinoma cell lines were sensitive to killing by ganciclovir (GCV). In the present study, we explored the effect of this vector on hepatocellular carcinoma cells in vivo. Subcutaneous tumors generated in nude mice by implanting hepatocellular carcinoma cells previously transduced with this vector shrank dramatically after treatment with GCV. Bystander effect was also observed on the tumors generated by mixing transduced and untransduced cells. To test whether the tumor cells can be transduced by the virus in vivo, we injected the recombinant adeno-associated virus into tumors generated by untransduced hepatocarcinoma cell line. Tumor growth were retarded after treatment with GCV. These experiments demonstrate the feasibility of in vivo transduction of tumor cell with rAAV.

Animals↗
PubMed1997

A randomised trial of six versus twelve courses of chemotherapy in metastatic carcinoma of the breast.

Chemotherapy given to patients with metastatic carcinoma of the breast is palliative in intent. Longer regimens would be justified if there was a proven prolongation of symptom response or survival. We conducted a randomised trial to assess the survival of patients receiving up to six extra courses of chemotherapy compared with our conventional regimen of six courses. The patients received either VAC, VEC (vincristine, doxorubicin or epirubicin and cyclophosphamide) or MMM (mitozantrone, methotrexate and mitomycin C) therapy. Patients who had stable disease or were responding after six courses of chemotherapy were randomised to either stop or continue treatment for another six courses. Those patients receiving maintenance therapy had a significantly longer duration of response (P < 0.02) and a significantly longer progression-free survival (P < 0.01). However, there was no survival difference between the two groups. Furthermore, treatment toxicity, which was similar in the two groups, persisted for longer in the maintenance group. These results indicate no clinical advantage for giving maintenance chemotherapy in order to prolong survival of patients with metastatic breast cancer.

Adult↗
PubMed1997

Flavimonas oryzihabitans bacteremia: clinical features and microbiological characteristics of isolates.

Flavimonas oryzihabitans is rarely reported as a pathogen in humans. Twelve cases of F. oryzihabitans bacteremia were diagnosed at National Taiwan University Hospital over a 3-year period. The clinical features of these patients were analyzed, and antimicrobial susceptibilities and random amplified polymorphic DNA (RAPD) patterns of the 12 isolates were studied. Among these 12 patients, eight (67%) had underlying neoplastic diseases and all acquired F. oryzihabitans bacteremia while hospitalized. The clinical syndromes included primary bacteremia in 5 patients (42%), biliary tract infection in 3 (25%), and peritonitis, subdural empyema, infusion-related bacteremia, and pneumonia in 1 each. Polymicrobial bacteremia or concomitant fungemia was seen in three patients (25%). All the patients survived after antibiotic treatment. All isolates were susceptible to piperacillin, third-generation cephalosporins, aminoglycosides, and quinolones but resistant to cephalothin, cefuroxime, and trimethoprim. Susceptibility to aztreonam was variable (25%). The RAPD patterns differed among the isolates, indicating the epidemiological unrelatedness of these infections. F. oryzihabitans should be included as an etiology of severe nosocomial infection in patients with underlying debilitating diseases.

Adult↗
PubMed1997

Family history of cancer and risk of lung cancer in lifetime non-smokers and long-term ex-smokers.

BACKGROUND: Genetic factors appear to play a role in the aetiology of lung cancer. METHODS: To examine the association between family history of cancer (all types) and risk of lung cancer among non-smokers, we conducted a case-control study. Cases (n = 618) were identified through the Missouri Cancer Registry for the period 1986 through 1991, and included 432 lifetime non-smokers and 186 ex-smokers who had stopped at least 15 years prior to diagnosis or had smoked for less than one pack-year. Controls (n = 1402) were selected through drivers licence and Medicare files. RESULTS: The risk of lung cancer increased directly in relation to the number of family members affected with cancer. The odds ratio (OR) associated with five or more first-degree relatives with cancer was 2.7 (95% confidence interval [CI] 1.2-6.1), with a significant linear trend in risk according to the number of relatives affected (P = 0.03). Increased lung cancer risk was associated with two or more affected siblings (OR = 1.4; 95% CI: 1.0-1.9) and with two or more affected offspring (OR = 3.2: 95% CI: 1.3-8.1). Risk was slightly elevated for family history of lung cancer (OR = 1.3; 95% CI: 1.0-1.8). CONCLUSIONS: Our study identified a slight increase in risk of lung cancer in relation to five or more relatives with cancer. Preventive implications of this increased risk are unclear because the attributable fraction is low in comparison to a variety of other factors.

Adult↗