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Biomedical subjects

C H Chang

Publications and source records attributed to C H Chang.

At least 379 records · Page 21Linked to original sources
PubMed1993

Endothelium-derived relaxing factors.

The endothelium modulates vascular tone by liberating both dilator [endothelium-derived relaxing factors; EDRFs]and constrictor substances [endothelium-derived contracting factors; EDCFs]. This review focused on endothelium-derived relaxing factor, its discovery, characteristics, synthesis and interaction with vascular smooth muscle. The major endothelium-derived relaxing factor is nitric oxide formed from L-arginine, which activates guanylate cyclase in the smooth muscle, leading to accumulation of cyclic-GMP. Endothelial cells can also release endothelium-derived hyperpolarizing factor EDHF which also cause endothelium-dependent relaxation.

Animals↗
PubMed1993

Prediction of fetal macrosomia by single ultrasonic fetal biometry.

A total of 1,056 fetuses underwent single ultrasonographic measurement of fetal biparietal diameter (BPD), abdominal circumference (AC), femur length (FL), and estimated body weight within five days of delivery. The accuracy of these parameters and estimated body weight equations in the prediction of macrosomia (birth weight > or = 4,000 g) was evaluated. With the use of receiver operator characteristic curves, the optimal cutoff value for each parameter with the best sensitivity, specificity and accuracy was selected. BPDs > or = 9.4 cm had the best sensitivity (68.8%), specificity (74.3%), and accuracy (74.1%). ACs > or = 35 cm had the best sensitivity (81.3%), specificity (81.5%), and accuracy (81.5%). FLs > or = 7.0 cm had the best sensitivity (68.8%), specificity (74.5%), and accuracy (74.3%). The estimated body weight equations did not increase the prediction values whether or not FL was included. Both had the same prediction values at > or = 3,700 g, ie, sensitivity (71.9% vs 71.9%), specificity (92.1% vs 93.8%), and accuracy (91.5% vs 93.2%). The results showed AC to be the best single parameter for predicting macrosomia. Combinations of these parameters were better than a single parameter in the prediction of macrosomia.

Anthropometry↗
PubMed1993

Growth of human melanocytes from suction blister of localized vitiligo patient and from foreskins of newborns and adults by modified culture medium.

We report on the culturing of melanocytes from suction blisters from the uninvolved skin of localized (focal and segmental) vitiligo patients and from the foreskins of newborns and adults, over a long period of time using a modified culture medium composed of F-12 medium supplemented with insulin (5 mg/mL), cholera toxin (40 ng/mL), transferrin (5 mg/mL), hydrocortisone (1 mM), epithelial growth factor (20 ng/mL), endothelial cell growth supplement (ECGS) (15 mg/mL), retinol (1 x 10(-7) M), 12-o-tetradecanoyl-phorbol-13 acetates (TPA) (85 nM), and 1% fetal calf serum (FCS). This method may be used in in vitro studies on normal human melanocytes and for study of the difference between melanocytes of normal individuals and of those with vitiligo. The ability to culture melanocytes from localized vitiligo, and the inability to grow those of generalized vitiligo with this system reconfirms the difference in the pathogenesis of various types of vitiligo. Thus, culturing may be used for differentiating localized vitiligo from generalized vitiligo and may be used to guide the mode of treatment when vitiligo has just started to develop and only a few depigmented patches have appeared. The results of studies on seeding density effect and serial Dopa reaction on the melanocytes of normal individuals reveal that the use of tyrosinase activity as the assessment parameter requires the use of melanocytes cultured for less than five months at a seeding density of less than 4 x 10(4) cells/cm2. Enlarged and heavily pigmented cells, senescent cells, were observed after very long-term culture (one year and four months).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Primary chylopericardium: report of a case.

A 14-year-old girl was admitted due to exertional dyspnea of one month's duration. A grade 3/6 holosystolic murmur with distant heart sounds was heard at the left sternal border. Chest roentgenograms and echocardiograms showed a large amount of pericardial and left pleural effusion and a small perimembranous ventricular septal defect. Subxyphoid pericardial drainage and left pleural intubation were performed. The fluid from both sites was defined as chyle by the milky white appearance, presence of microscopic fat droplets and the lymphocyte predominance in the white cell count. Lymphangiograms and a chest computed tomographic scan demonstrated thoracic duct obstruction and leakage of contrast to pericardial and pleural spaces. The patient was treated with a medium chain triglyceride diet. Unfortunately, massive reaccumulation of the effusion was later noted. Therefore, a median sternotomy with ligation of the thoracic duct, creation of a posterior pericardio-pleural window and implantation of a left pleuro-peritoneal shunt with a Denver peritoneo-venous shunt were performed. Follow-up for one year with two-dimensional echocardiograms showed no more accumulation of the pericardial effusion.

Adolescent↗
PubMed1993

Acute renal failure after open heart surgery: clinical experience with continuous arteriovenous hemodialysis.

Continuous arteriovenous hemodialysis (CAVHD) was employed in five patients who suffered from acute renal failure (ARF) after open heart surgery during the period from July 1991 to February 1992. All patients had a urine output of less than 400 mL/24h and clinical evidence of fluid overload. Most of the patients needed respiratory support for respiratory insufficiency and required vasopressor infusions. They could not tolerate conventional hemodialysis due to severe hemodynamic instability, and the concurrent thoracic surgery precluded the application of peritoneal dialysis. All patients tolerated the CAVHD well, despite persistent hypotension. The mean age of the five patients was 53.6 +/- 15.3 years. The duration of CAVHD treatment ranged from 1.5 to 22 days. Whole blood clearances for urea, creatinine and phosphate were 13.27 +/- 1.86 mL/min, 13.05 +/- 3.12 mL/min, and 13.99 +/- 2.61 mL/min, respectively. According to the clinical condition, ultrafiltration averaged 100-200 mL/h; up to 1 L/h could be obtained without difficulty. In these situations, large concurrent amounts of vasopressors and nutritional fluids could be easily prescribed without fear of fluid overload. The introduction of CAVHD allowed a more stabilized environment for gradual recovery of the temporarily compromised ventricular function after open heart surgery. Later, the hemodynamic status was stabilized without or with only minimal infusions of vasopressors in all five patients. Renal function recovered in four patients and one was shifted to conventional hemodialysis. All five patients survived under CAVHD treatment. There were no significant complications related to the application of CAVHD.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1993

Study on blackfoot disease: with special reference to evaluating its cutaneous microcirculatory status.

We evaluated the microcirculatory status of blackfoot disease by skin temperature measurement, laser Doppler flowmetry and capillary microscopy. The results of these assessments revealed a good correlation between the disease stage and the microcirculatory status. No effective therapy other than surgical amputation was recommended before. In this study, we treated this endemic disease with prostaglandin E1 (PGE1) infusion therapy. PGE1 was most effective in the erythematous stage and some minor ulcer with an improvement of microcirculatory status. However, PGE1 had no effect in severe ulcerative (ulcer > 0.5 cm) and gangrenous stages. These microcirculatory improvements foreshadowed the improvement of clinical manifestations. The microcirculatory status after PGE1 treatment demonstrated the effectiveness of the therapy.

Aged↗
PubMed1993

Removal of renal cell carcinoma extending into the right atrium using cardiopulmonary bypass, profound hypothermia and circulatory arrest.

A 65-year-old man presented with renal cell carcinoma of the right kidney with a tumor thrombus extending up the vena cava to the right atrium. Cardiopulmonary bypass, profound hypothermia and total circulatory arrest were used to create a bloodless field for excision of the renal cell carcinoma and its tumor thrombus. Acute respiratory failure and deep jaundice developed after the operation and the patient was transferred to the intensive care unit for critical care. After respiratory therapy and nutritional support, the liver function was restored. The endotracheal tube was weaned one month later. The patient has had total resolution of all symptoms and there is no evidence of tumor recurrence of distant metastases after 6 months follow-up.

Aged↗
PubMed1993

Endothelium-derived contracting factors.

In the past decade, the importance of endothelium in modulating vascular tone has become apparent. Endothelium can produce different vasodilators, such as prostacyclin, endothelium-derived relaxing factor (most likely nitric oxide), and endothelium-derived hyperpolarizing factor. Endothelium can also produce endothelium-derived contracting factors (EDCF) which can induce constriction of the underlying vascular smooth muscle. Constriction may be mediated by a variety of products released by the endothelium. Thus, by responding to various stimuli and releasing either relaxing or contracting factors, the endothelium can set and modulate vascular tone.

Animals↗
PubMed1993

[The hemodynamic and ventilatory effects between Trendelenburg and reverse Trendelenburg position during laparoscopy with CO2-insufflation].

Thirty ASA class I female patients underwent gynecologic pelvioscopy and laparoscopic cholecystectomy were included in this study. All of them received general anesthesia and certain volume of CO2 pneumoperitoneum. We evaluated the effect of positioning (Trendelenburg as group I and reverse Trendelenburg as group II) on hemodynamic parameters and ventilation. The hemodynamic parameters, ventilation, and arterial blood gas were determined at the following stages: (1) after 10 minutes of normoventilation and before CO2 pneumoperitoneum (as control), (2) 5 minutes after CO2 pneumoperitoneum and positioning, (3) 25 minutes after positioning, (4) 50 minutes after positioning, (5) 10 minutes after resumption of supine position and decompression of abdomen. Arterial blood pressure, heart rate, minute volume, end-tidal CO2, oxygen saturation and blood gas analysis were taken during normoventilation. We found that there was no statistical difference between either group in respect to hemodynamic parameters. For the ventilation, both groups had appropriate SpO2 during the period of CO2 pneumoperitoneum, but PaCO2 was significantly increased in group I 25 min after CO2 pneumoperitoneum and Trendelenburg positioning. Nonetheless, end-tidal CO2 was not significantly increased. pH value and PaCO2 did respectively decrease and increase significantly in group I 50 min after Trendelenburg position. However, no change was found in end-tidal CO2. All data were not significantly different after resumption of supine position and decompression of abdomen. Conclusively, except that pH and PaCO2 had changed after a period of Trendelenburg positioning with CO2 pneumoperitoneum, the patients who underwent laparoscopic surgery with normoventilation have no hemodynamic and respiratory change.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Gastro-pleural fistula related with penetrating stab injuries of the chest and abdomen: laparotomy or thoracotomy.

A 30-year-old male presented with left side empyema due to gastro-pleural fistula following repair of penetrating stab injuries of left lower chest and abdomen. Exploratory thoracotomy was done due to persistent moderate amount of purulent discharge. However, fistula tract was not detected through this approach. The small fistula tract was repaired finally through laparotomy. We recommended the abdominal approach if the disease is not combined with diaphragmatic hernia. Transabdominal approach showed superiority in this rare entity.

Abdominal Injuries↗
PubMed1993

Breast biopsy for nonpalpable lesions: a worthwhile endeavor?

The purpose of this study was to determine our yield of carcinoma in patients with a nonpalpable mammographic abnormality and to identify which mammographic criteria will most likely yield a positive biopsy. We conducted a review of all patients with nonpalpable mammographic abnormality who underwent needle-localized breast biopsy at our institution from 1988 to 1991. Charts of 295 patients who underwent 332 needle-localized breast biopsy were reviewed for age, family history, cancer history, mammographic findings, operative time, volume of excised breast tissue, and histology. Mammographic abnormalities were categorized as suspicious (clustered) microcalcification, stellate mass, ill-defined mass, well-circumscribed mass, developing density, or asymmetric density. The overall yield of cancer positive biopsies was 48 of 332 (14.5%). The frequency of diagnosed cancers was DCIS (8), LCIS (1), Stage I (31) and Stage II (8). The frequency that each single mammographic criteria resulted in a cancer diagnosis was: suspicious calcification (12%), stellate mass (22%), ill-defined mass (14%), well-circumscribed mass (11%), developing density (9%) and asymmetric density (0%). However, patients with both a stellate mass and microcalcifications formed the highest risk subgroup, with cancer detected 66 per cent of the time (P = 0.03).

Adenofibroma↗
PubMed1992

Reactivation of a major histocompatibility complex class II gene in mouse plasmacytoma cells and mouse T cells.

Terminally differentiated plasma cells and mouse T cells do not express major histocompatibility complex (MHC) class II genes although class II gene expression is observed in pre-B and mature B cells as well as in activated human T cells. Transient heterokaryons were prepared and analyzed to investigate the mechanisms of inactivation of MHC class II gene in mouse plasmacytoma cells and mouse T cells. The endogenous MHC class II genes in both mouse plasmacytoma cells and mouse T cells can be reactivated by factors present in B cells. This reactivation of class II gene is also observed by fusion with a human T cell line which expresses MHC class II genes, but not with a class II negative human T cell line. It appears that the loss of MHC class II gene expression during the terminal differentiation of B cells or T cell lineage is due to absence of positive regulatory factor(s) necessary for class II transcription.

Animals↗
PubMed1992

Formycin triphosphate as a probe for the ATP binding site involved in the activation of guanylate cyclase.

Formycin A triphosphate (FTP), a fluorescent analog of ATP, slightly increased basal guanylate cyclase activity, but significantly potentiated guanylate cyclase activity stimulated by atrial natriuretic factor (ANF) in rat lung membranes. FTP potentiated ANF-stimulated guanylate cyclase activity with an EC50 at about 90 microM and inhibited ATP-stimulated guanylate cyclase activity with an IC50 at about 100 microM. These results indicate that FTP binds more tightly than ATP for the same binding site. Therefore, FTP would be an excellent tool for studying the ATP binding site.

Adenosine Triphosphate↗
PubMed1992

Usefulness of predischarge electrophysiologic study in predicting late outcome after surgical ablation of the accessory pathway in the Wolff-Parkinson-White syndrome.

A predischarge electrophysiologic study was performed in 113 patients with the Wolff-Parkinson-White (WPW) syndrome who had undergone surgical ablation of the accessory pathway. The study was performed 5 to 20 (mean 10 +/- 3) days after surgery. There were 82 male and 31 female patients (aged 4 to 58 years, mean 36 +/- 13). Sixty-one patients (54%) had manifest, 52 (46%) had concealed and 12 (11%) had multiple accessory pathways. All but 1 patient had atrioventricular reentrant tachycardia incorporating single or multiple accessory pathways during the control electrophysiologic study. The accessory pathways were located in the left ventricular free wall in 60% of cases, right ventricular free wall in 22%, posteroseptum in 13%, and anteroseptum in 5%. The predischarge electrophysiologic study showed that the accessory pathway was capable of anterograde and retrograde conductions in 4 patients (all with manifest WPW syndrome). Four patients showed induction of supraventricular tachycardia, including 2 with atrioventricular reentrant tachycardia, and 2 with atrioventricular nodal reentrant tachycardia. Recurrence of supraventricular tachycardia was noted in 5 patients during a follow-up of 28 +/- 26 months. Of these 5 patients, 2 had inducible and 3 had no inducible supraventricular tachycardia during the predischarge electrophysiologic study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Derivation of the SLEDAI. A disease activity index for lupus patients. The Committee on Prognosis Studies in SLE.

OBJECTIVE: To standardize outcome measures in systemic lupus erythematosus (SLE). Three indices were identified which could adequately describe outcome (disease activity, damage from disease, and health status); we describe here the development of the Disease Activity Index. METHODS: Twenty-four variables were identified as important factors in a disease activity index. These were used to generate 574 patient profiles, which were rated on a disease activity scale of 0-10 by 14 rheumatologists. A second rating of 10 of the profiles yielded scores that were not significantly different from the first, indicating that experienced clinicians can reliably make global estimates of disease activity. Multiple regression models were used to estimate the relative importance of the 24 clinical variables in the physicians' global rating of disease activity. These were estimated on a "training set" of 75% of physicians' ratings, and then validated on a "testing set," consisting of the remaining 25% of physicians' ratings. RESULTS: The explanatory power of the models in the training set was high (R2 = 0.93). The models' regression coefficients for the organ systems were simplified for easier use in clinical practice. This generated a "weighted" index of 9 organ systems for disease activity in SLE, the SLEDAI, as follows: 8 for central nervous system and vascular, 4 for renal and musculoskeletal, 2 for serosal, dermal, immunologic, and 1 for constitutional and hematologic. The maximum theoretical score is 105, but in practice, few patients have scores greater than 45. The SLEDAI predicted well the physicians' ratings in the testing set (Pearson's correlation coefficients = 0.64-0.79). CONCLUSION: The SLEDAI is a validated model of experienced clinicians' global assessments of disease activity in lupus. It represents the consensus of a group of experts in the field of lupus research.

Central Nervous System↗
PubMed1992

Dissection of the interferon gamma-MHC class II signal transduction pathway reveals that type I and type II interferon systems share common signalling component(s).

We have used a herpes virus thymidine kinase (HSV-TK) based metabolic selection system to isolate mutants defective in the interferon gamma mediated induction of the MHC class II promoter. All the mutations act in trans and result in no detectable induction of MHC and invariant chain (Ii) gene expression. Scatchard analysis indicates that the mutants have a normal number of surface IFN gamma receptors with the same affinity constant. The mutants fall into two broad categories. One class of mutants is still able to induce MHC class I, IRF-1, 9-27, 1-8 and GBP genes by IFN gamma. A second class of mutants is defective for the IFN gamma induction of all the genes tested; surprisingly, the IFN alpha/beta induction of MHC class I, 9-27, ISG54 and ISG15 genes is also defective in these mutants, although different members of this class can be discriminated by the response of the GBP and IRF-1 genes to type I interferons. These data demonstrate that the signalling pathways of both type I and type II interferon systems share common signal transduction component(s). These mutants will be useful for the study of IFN gamma regulation of class II genes and Ii chain, and to elucidate molecular components of type I and type II interferon signal transduction.

Base Sequence↗
PubMed1992

Does extent of surgery influence outcome for astrocytoma with atypical or anaplastic foci (AAF)? A report from three Radiation Therapy Oncology Group (RTOG) trials.

103 patients with the diagnosis of AAF were identified from the RT/BCNU arms of 3 RTOG malignant glioma trials. Pre-treatment tumor size was less than 5 cm for 48% and greater than or equal to 5 cm for 52%, and tumor sites were frontal lobe in 55%, temporal in 25%, and parietal in 16%. Surgery consisted of biopsy for 30%, partial resection for 56%, and total resection for 14%. Extent of surgery correlated with age, with 81% of patients less than 40 undergoing partial/total resection vs. 60% of those over 40 (P = 0.019). The median survival time (MST) of patients undergoing partial/total resection was 49 mo., vs. 18 mo. for those biopsied only (P = 0.002). Patients with frontal location had longer MST than those with non-frontal lesions (MST: 49 vs. 25 mo., P = 0.047), while no survival difference was apparent by univariate analysis of tumor size. Multivariate analysis demonstrated that only younger age, frontal location, and smaller tumor size correlated significantly with extended survival. Extent of surgery was not predictive. The close correlation between young age and extensive surgery obscures the survival advantage for greater surgery seen with univariate analysis. Smaller tumor size and frontal location favorably influence outcome even when adjusted by age.

Adult↗