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Biomedical subjects

D J Wang

Publications and source records attributed to D J Wang.

At least 37 records · Page 2Linked to original sources
PubMed1998

[Histopathological findings and clinical effects for acute rejections].

We reviewed 115 cases of acute rejection following renal transplantation. All cases were diagnosed after graft biopsy, and showed histopathological evidence of acute rejection. They were treated with administration of OKT3, 15-deoxyspergualin (DSG), anti-lymphocyte globulin (ALG) or methylprednisolone (MP). All rejections were histopathologically classified according to the Banff working classification. The clinical effects of each drug were evaluated both at 1 month and 1 year following the therapy for rejection, by measurement of serum creatinine level. The effective rate both at 1 month and 1 year was related with the Banff working classification ( p < 0.0001). At 1 month after treatment, there were no significant differences between the OKT3, DSG or ALG group and MP group in cases of borderline change and AR grade I. In cases of grade II and grade III, a significant difference was observed between the OKT3 or ALG group and MP group (p < 0.05). The DSG group showed a slightly better outcome than the MP group, although the difference was not significant. In conclusion, the Banff schema is shown to be valid for classification of acute renal allograft rejection, and it is necessary to determine the treatment for acute rejection according to histopathological classification.

Acute Disease↗
PubMed1998

Development of a web based electronic patient record extending accessibility to clinical information and integrating ancillary applications.

Web-technology offers a powerful mechanism for providing access to clinic information. Applications need no longer to be tied to a specific client operating system. The Johns Hopkins Hospital has designed a web based electronic patient record system which seamlessly incorporates multiple web sites. This paper will discuss the motivations for building the system, the architecture, and the challenges faced in designing the architecture.

Academic Medical Centers↗
PubMed1997

[Study of controlling acute hemorrhage from esophageal varices using adhesion technique of traditional Chinese medicine].

OBJECTIVE: The aim of this study was to find a method making the traditional Chinese medicine adhesion to the esophageal membrane for controlling bleeding esophageal varices. METHODS: The position and time that the medicine attached in the esophagus were observed in 30 healthy volunteers under the condition of erect and lying position. Thirty-seven cases with bleeding esophageal varices were treated by this technique. RESULTS: The medicine of adhesion was attached in the segment of esophagus more than 15 minutes under the condition of lying position. The effective rate of controlling bleeding esophageal varices was no statistical differences between the ballon temponade and our technique (P > 0.05). CONCLUSIONS: This technique is a new approach to control hemorrhage from esophageal varices.

Drugs, Chinese Herbal↗
PubMed1996

Relationship between smoking status and cardiovascular disease risk factors in young adult males in Taiwan.

BACKGROUND: To evaluate smoking status and cardiovascular risk factors in young male adults in Taiwan. METHODS: After cluster sampling, we performed a cross-sectional survey to assess smoking status, duration, and number of cigarettes smoked in 781 young adult males (mean age 20 years, range 18-24). Cardiovascular disease risk factors, including anthropometric factors, blood pressure, lipoproteins and apolipoprotein levels were also measured. RESULTS: In total 211 subjects (27.0%) had never smoked, 38 subjects (4.9%) were ex-smokers, and 532 (68.1%) still smoked cigarettes. The prevalence of smoking was higher than in 1989 and 1990 (54.8 and 59.4%, respectively). Current smokers had significantly higher serum triglyceride and lower high-density lipoprotein-cholesterol levels than subjects who had never smoked (56.2 versus 46.9 and 55.6 versus 59.0 mg/dl, respectively; P < 0.05 for both). No difference was found in other cardiovascular risk actors among subjects in the different smoking groups or among current smokers who had smoked for different periods of time or who smoked different numbers of cigarettes. CONCLUSION: These data suggest that the prevalence of smoking in young adult males in Taiwan has increased progressively. No differences were found in anthropometric factors or blood pressure among subjects of different smoking status. Abnormal lipoprotein levels (higher triglyceride and lower high-density lipoprotein cholesterol) were found in current smokers compared with non-smokers. A longer follow-up study will be needed to confirm whether the smoking status of these young adults can be correlated with the risk of cardiovascular disease.

Adolescent↗
PubMed1995

Homologous desensitization of ATP-stimulated mitogenesis: mechanism involves desensitization of arachidonic acid release and cAMP elevation but not the activation of protein kinase A.

Prolonged incubation of quiescent 3T3, 3T6, and A431 cells with the P2Y purinoceptor agonists ATP, ADP, or AMPPNP reduced the mitogenic responses of target cells to a further challenge by these agonists, as measured by [3H]thymidine incorporation. The mitogenic desensitization was agonist-specific, for no effect was seen on DNA synthesis stimulated by epidermal growth factor, insulin, bombesin, 12-O-tetradecanoyl-phorbol-12 acetate (TPA), or adenosine. The desensitization was completely reversible, since after a 24 hr incubation in the absence of ATP, the cells responded fully to the mitogenic action of ATP. The presence of a low level of cycloheximide blocked recovery, suggesting that down-regulation of the P2Y receptor may have occurred during desensitization. In Swiss 3T3 cells, stimulation of DNA synthesis occurs predominantly by activation of arachidonic acid release, followed by its oxidation to prostaglandin E2 and stimulation of adenylyl cyclase. Interestingly, prolonged preincubation with ATP produced a similar degree of desensitization of DNA synthesis and of ATP-dependent arachidonic acid release and cAMP accumulation. Furthermore, this was true for both wild type cells and mutants with a defective cAMP-dependent protein kinase (PKA). We conclude that homologous desensitization is likely due to uncoupling of the P2Y purinoceptor from phospholipase A2, and this process does not require activation of protein kinase A.

3T3 Cells↗
PubMed1995

RF electric field mapping in MR coils with a quartz crystal.

The electric field strength and distribution in MRI/MRS probes was assessed with a quartz crystal whose resonance frequency coincided with the probe frequency. A quartz crystal was used as the sensor because: (i) it was capable of producing a resonance signal when it was excited with a pulsed RF electric field; and (ii) the resonance signal was proportional to the square of the electric field strength (or RF excitation power). The sensor was placed in the vicinity of the MR coil under evaluation and was excited with a short RF pulse applied to the coil and, immediately after the pulse, the resonance signal induced was picked up by the same coil acting as a receiver coil. Intensities of the signals were used to assess the distribution of RF electric fields in the coil. This device is useful for probe design, particularly in the minimization of dielectric losses, which have been attributed to the presence of electric fields in MR coils.

Magnetic Resonance Imaging↗
PubMed1994

A novel synergistic stimulation of Swiss 3T3 cells by extracellular ATP and mitogens with opposite effects on cAMP levels.

In Swiss 3T3 mouse fibroblasts, the mitogenic effect of extracellular ATP depends on stimulation of adenylyl cyclase. Lysophosphatidic acid (LPA) and phosphatidic acid (PA) inhibited adenylyl cyclase but synergized with ATP in mitogenic stimulation. This unusual synergism of two mitogens with opposite effects on cAMP levels was further investigated. LPA and PA inhibited the elevation of cAMP caused by cholera toxin, prostaglandin E2, or forskolin, but not the rise induced by ATP. In fact, ATP overcame the inhibitory effects of LPA or PA on cAMP levels. Indeed, in the presence of ATP and either cholera toxin or prostaglandin E2, LPA became a stimulator of adenylyl cyclase. Stimulation of DNA synthesis and inhibition of cAMP accumulation by LPA were inhibited by pertussis toxin, but with different dose-response characteristics. In addition, a normal mitogenic response to LPA was obtained in transfected mutant cells with a defective regulatory subunit for protein kinase A and in cells whose regulation of cAMP levels was abnormal because of overproduction of cAMP phosphodiesterase. The data support the hypothesis that the mitogenic effect of LPA involves a PTX-sensitive Gi protein but not inhibition of adenylyl cyclase.

3T3 Cells↗
PubMed1994

Intracellular sodium in cardiomyocytes using 23Na nuclear magnetic resonance.

Intracellular sodium content in superfused isolated rat cardiomyocytes was measured using 23Na nuclear magnetic resonance. The shift reagent dysprosium tripolyphosphate was added to the buffer to distinguish between NMR signals from the intracellular region and the extracellular buffer. The NMR visibility of the intracellular sodium signal was experimentally determined by measuring the changes induced in the sodium NMR signals by application of ischemia as an intervention. Intracellular volume was accounted for by determining the change in the sodium signal upon adding cells (in beads) to the buffer solution at the beginning of each experiment and by killing the cells (in beads) with Triton X-100 at the end of each experiment. The visibility of intracellular sodium (relative to extracellular) was 0.47 +/- 0.12 (mean +/- S.D., n = 12). The average intracellular sodium concentration using this visibility is 29 +/- 4.5 mM (n = 12). This value is much higher than results obtained by some investigators using NMR techniques and by others using different standard methods, with the exception of those methods which evaluate the total intracellular sodium (atomic absorption spectroscopy and X-ray microanalysis). We conclude that total Nai is higher than generally reported, using other accepted techniques such as ion-specific electrodes, and that 23Na-NMR analysis can be used to accurately determine Nai in intact cells.

Animals↗
PubMed1994

Role of adenosine 3':5'-monophosphate-dependent protein kinase and cAMP levels in ATP-dependent mitogenesis in Swiss 3T3 cells.

To investigate the role of cAMP-dependent protein kinase (PKA) and cAMP levels in ATP-dependent mitogenesis, Swiss 3T3 cells were transfected with an expression vector coding for (i) a mutated regulatory subunit of PKA (PKA mutant) or (ii) a yeast low Km cAMP phosphodiesterase gene (PDE mutant). The PKA mutant showed 70% reduced PKA activity. Phosphodiesterase activity increased 2.5-fold in the PDE mutant, leading to a great reduction of cAMP levels stimulated by ATP and other cAMP-increasing agents. The mitogenic responses of PKA and PDE mutants to insulin, epidermal growth factor, or 12-O-tetradecanoylphorbol-13-acetate were not significantly changed. However, the further stimulation by ATP, ADP, and adenosine 5'-(beta,gamma-imido)triphosphate in the presence of these growth factors was reduced by > 80%. Mitogenic effect of prostaglandin E2, forskolin, cholera toxin, or adenosine was inhibited in both mutants. The mitogenic stimulation by dibutyryl cAMP, which is resistant to phosphodiesterase, was inhibited in the PKA mutant, but not in the PDE mutant. A partial reduction of platelet-derived growth factor- or bombesin-stimulated mitogenesis, which involves protein kinase C as well as the cAMP signal, was observed in the mutants. These genetic results confirm pharmacological data on the role of PKA and cAMP levels in mitogenesis due to ATP and other growth factors.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1994

Wireless precision piezoelectric thermometer using an RF excitation-detection technique with an NMR probe.

Based on an inductive RF excitation-detection scheme, a quartz-crystal temperature-measuring device is described for applications in MRI and MRS scanners where strong electric and magnetic fields are present. A quartz-crystal resonator with a high temperature sensitivity (88 ppm/degrees C) is employed as the temperature sensor. Changes in the quartz resonance frequency reflecting temperature variations are detected by a NMR coil multiply tuned to the resonance frequencies of the quartz crystal and the nuclei of interest. This wireless probe is simple to build and is capable of measuring temperature changes from -50 to +150 degrees C. The high frequency linearity of the device in this temperature region ensures a simple calibration procedure and a constant temperature resolution.

Electromagnetic Phenomena↗
PubMed1994

The interrelationship between impaired glucose tolerance and other risk factors for cardiovascular disease: is it a predictor for cardiovascular disease?

Glucose intolerance and cardiovascular risk factors were assessed among 215 subjects aged 27-86 years in Ho-long, Taiwan. An oral glucose tolerance test (OGTT) was normal in 107 subjects, impaired in 41 subjects, and abnormal in 67 subjects (as noninsulin dependent diabetes mellitus, NIDDM). Body fatness, blood pressure, carbohydrate and lipid metabolic factors were examined. One-way ANCOVA was used to compare age- and/or BMI-adjusted differences among these groups. Male subjects with NIDDM and impaired glucose tolerance (IGT) had higher systolic (SBP) and diastolic (DBP) blood pressures, plasma insulin (fasting and 1-hour after OGTT), serum triglycerides (TG), heavier body weight, and larger BMI than normal. IGT subjects were also found to have higher TG, insulin (2-hour) and larger insulin area under curve (IAUC) after OGTT than NIDDM. In females, subjects with NIDDM had higher TG, insulin (fasting and 1-hour after OGTT), and larger IAUC than normal. Moreover, female IGT subjects were also found to have significantly higher SBP, DBP, insulin (1-and 2-hour after OGTT), and larger IAUC than both normal and NIDDM subjects. These results suggest that adverse cardiovascular risk factors are present not only in NIDDM subjects, but also in IGT subjects.

Adult↗
PubMed1994

Reconstruction of esophagus with whole stomach through esophageal bed after resection of the upper esophageal carcinoma. A report of 160 cases.

From September 1985 to December 1992, 160 cases of reconstruction of the esophagus with the whole stomach through the esophageal bed after resection of the upper esophageal carcinoma were performed with neither operative mortality nor intrathoracic complications. The leakage rate of the cervical anastomosis with Gambee's single layer method was 1.2%. The main steps of the operative procedure consisted of: (1) making a right thoracotomy for dissecting and removing the entire thoracic esophagus; (2) laparotomy for mobilizing the whole stomach, constricting it to tube shape and doing a pyloroplasty; and (3) pulling up the mobilized tube-like stomach through the posterior mediastinal space (i.e. the esophageal bed) out of the left neck incision and then the esophagogastrostomy with Gambee's single layer anastomosis was performed.

Adult↗
PubMed1993

Stimulation of aged human lung fibroblasts by extracellular ATP via suppression of arachidonate metabolism.

The mitogenic effect of extracellular ATP on IMR-90 human fibroblasts subjected to in vitro aging was studied. ATP stimulated DNA synthesis and cell proliferation in young cells as much as epidermal growth factor (EGF) or insulin, while it stimulated aged cells to a much greater extent than seen for any other growth factor tested. When combined with EGF or insulin, ATP restored the greatly reduced mitogenic responsiveness of aged cells nearly to the level noted for young cells. Addition of prostaglandin E2 or other agents that elevate cAMP levels resulted in inhibition of DNA synthesis stimulated by EGF or insulin. Furthermore, the basal release of arachidonic acid and prostaglandin E2 and the endogenous levels of cAMP rose during aging and became much greater than in young cells. All three of these changes were suppressed by extracellular ATP. ATP-dependent suppression of cAMP accumulation was pertussis toxin-sensitive. Protein kinase C down-regulation inhibited arachidonate metabolism and enhanced DNA synthesis stimulated by ATP. These studies suggest that ATP exerts its mitogenic effect, especially on aged IMR-90 cells, at least partially by suppression of arachidonate metabolism.

Adenosine Triphosphate↗
PubMed1993

NMR visibility studies of N-delta proton of proximal histidine in deoxyhemoglobin in lysed and intact red cells.

Recent in vivo 1H MRS studies of muscle oxygen levels by means of myoglobin (Mb) oxygenation have necessitated an investigation of the possible contamination from deoxy-hemoglobin (Hb). To determine the contribution of Hb in these NMR measurements, we studied the NMR visibility of histidyl N-delta proton of Hb in lysed and intact RBC (red blood cell) suspensions. We found that the visibility of deoxy-Hb was significantly lower in intact RBCs (ca. 16%) than the solution form at an equivalent concentration of beta heme-iron, even though the visibility of deoxy-Hb from lysed RBC and deoxy-Mb was almost identical. Our study also shows that visibility increases with RBC swelling. Based on the difference in concentration and compartmentation, we conclude that less than 17% contribution from Hb is expected in Mb measurements in vivo. The possible mechanisms which cause the low visibility of Hb in RBCs are discussed.

Erythrocytes↗