Search PubMed⌕ Search

Biomedical subjects

D W Wang

Publications and source records attributed to D W Wang.

At least 55 records · Page 3Linked to original sources
PubMed1995

Voltage dependent inhibition of ATP sensitive potassium channels by flecainide in guinea pig ventricular cells.

OBJECTIVE: The aim was to examine the effects of flecainide, a class Ic antiarrhythmic drug, on the ATP sensitive potassium channel (KATP channel) current in guinea pig ventricular cells, using the inside-out patch clamp technique. METHODS: KATP channel activities were recorded from inside-out membrane patches with 140 mM KCl solution bathing both the external and internal surfaces of the membrane (20-22 degrees C). Flecainide was added to the intracellular medium (ATP-free, pH = 7.3). RESULTS: Flecainide (1-300 microM) inhibited the outward KATP channel current evoked at the holding potential of +40 mV, in a concentration dependent manner. The flecainide concentration for half maximum inhibition of the channel activity (IC50) and Hill coefficient of the flecainide inhibition were estimated to be 17.3 microM and 1.1, respectively. However, flecainide did not affect the inwardly directed KATP channel current measured at the potential of -40 mV. When the inhibitory effects of flecainide on the outward current were examined under conditions in which pH was decreased from 7.3 (control) to 6.8, the IC50 and Hill coefficient became 27.3 microM and 1.2, respectively. Furthermore, in the presence of 0.1 mM ADP on the cytosolic side of the membrane (pH = 7.3), flecainide blocked the outward currents with the IC50 of 47.0 microM and a Hill coefficient of 0.9. After 1 min exposure of the cytoplasmic side of the membrane to trypsin (1 mg.ml-1), glibenclamide (2 microM) did not inhibit the KATP channel currents, while flecainide (30 microM) reversibly inhibited this trypsin enhanced KATP channel activity. CONCLUSIONS: Flecainide at relatively high concentrations blocks the cardiac KATP channels only when the currents are directed outward, and in a concentration dependent manner. The potency of flecainide in blocking KATP channels decreased under conditions of increased H+ or ADP concentrations on the cytosolic side of the membrane, as may occur in myocardial ischaemia or hypoxia.

Adenosine Diphosphate↗
PubMed1995

Apoptosis in bone marrow cells of mice with different p53 genotypes after gamma-rays irradiation in vitro.

Apoptosis is a physiological phenomenon occurring during embryonic development, T and B cell maturation, and endocrine-induced atrophy. It can be initiated by various agents and has been considered to be related to the expression of the oncosuppressor p53 gene. In this review, p53 gene-targeting mice were used to study the effect of p53 gene status on the induction of apoptosis in bone marrow cells by gamma-ray irradiation. The results showed that homozygous null (p53 -/-) murine bone marrow cells were more resistant to the induction of apoptosis by radiation than other genotypes (heterozygous, p53 +/- and wild type, p53 +/+). The percentage of apoptotic cells in p53 +/+ mice was about three times that in p53 -/- mice at 4 hr after 6 Gy gamma-irradiation, and the analysis of the apoptosis-characteristic DNA ladder further supported these findings. We found that the homozygous null mice also can undergo apoptosis after irradiation. This suggested that there is another independent apoptotic p53 gene mechanism in irradiated murine bone marrow cells. Thus, in murine bone marrow cells, both p53 gene-dependent and -independent apoptosis occurred after irradiation. In our previous work, an increase in survival of hemopoietic progenitor cells after irradiation in vitro in p53 gene deletion mice was observed. This increase is closely related to the inhibition of apoptosis in bone marrow cells in p53 gene deletion mice.

Animals↗
PubMed1994

Phenotype analysis of mononuclear cells in endomyocardial biopsy specimens from patients with viral myocarditis and dilated cardiomyopathy.

This study investigated the distribution and phenotype of mononuclear cells in endomyocardial biopsy (EMB) specimens from patients with viral myocarditis (VMC, 25 cases) and dilated cardiomyopathy (DCM, 10 cases). T lymphocytes, including Th/i cells in VMC and Tc/s cells in DCM, predominated in the infiltrating mononuclear cells in these specimens. The morphological relationship between infiltration of T lymphocytes and pathological changes of myocardia was also observed and neither macrophages nor B lymphocytes were found.

Adult↗
PubMed1994

Collagen gene expression in radiation interstitial pneumonitis.

By using type I and type III collagen cDNA probe and cDNA-mRNA in situ hybridization, we observed the changes of rat lung alpha 1(I) and alpha 1(III) collagen gene expression in radiation interstitial pneumonitis. The results showed that the expressed cell of type I and type III collagen were scattered within the fibroblasts in the thickened interalveolar walls. The type I and type III collagen mRNA content in irradiated animals were higher than those in the controls at 0.5, 1, 2, 3, 6, and 12 months.

Animals↗
PubMed1994

The changes and significance of mast cells in irradiated rat liver.

There has been no report on changes in mast cells in hepatic radiation injury. Because of the interactions between mast cells and fibroblasts and mast cell changes in radiation interstitial pneumonitis, we examined the mast cells in experimental hepatic irradiation. We used 60Co gamma-ray in a single dose of 10, 30, 50, and 60 Gy given to the liver area of male Wistar rats. The liver tissue was examined 0.5, 1, 2, 3, 6, 9, and 12 months after irradiation. The mast cells were quantitatively and qualitatively assessed in liver sections by light and electronmicroscopy. Typical chronic liver fibrosis occurred after 30 Gy. As the lesions progressed in severity, the number of mast cells increased and they became larger 1 to 2 months after irradiation. After 3 to 6 months, this change was very marked and degranulation was noted. Both the number and size of mast cells were increased markedly. The peak intensity in mast cell changes paralleled that of connective tissue proliferation. At 12 months, when the fibrous tissue was rich in collagen, the mast cells decreased in number. Our findings suggest that mast cells participate in the development of radiation hepatic fibrosis.

Animals↗
PubMed1994

Prevention of atherosclerotic arterial stenosis and restenosis after angioplasty with Andrographis paniculata nees and fish oil. Experimental studies of effects and mechanisms.

Restenosis rate after coronary angioplasty has been up to 30%-40%. To solve this problem, we studied the effects of Andrographis Paniculata Nees (APN) and fish oil (FO, omega 3 polyunsaturated fatty acids over 70%) on atherosclerotic stenosis and restenosis after experimental angioplasty and the relevant mechanisms of APN and FO. Preliminary results showed that APN can significantly alleviate atherosclerotic iliac artery stenosis induced by both deendothelialization and high cholesterol diet (HCD) and restenosis following angioplasty in rabbits. FO showed the same but milder effects than APN did. Both APN and FO significantly inhibited blood monocytes to secrete growth factors in vivo. Ca(++)-ATPase activity of cell membrane of atherosclerotic rabbits was significantly decreased, while APN or FO, especially the former alleviated this reduction. Refined extract of APN significantly decreased in vitro resting platelet [Ca++]i and in vivo the resting and thrombin-stimulated platelet [Ca++]i after oral administration of APN for 2 weeks. APN significantly inhibited cell growth or DNA synthesis in dose-dependent manner. In conclusion because of the mechanisms described above, APN can alleviate atherosclerotic artery stenosis induced by both deendothelialization and HCD as well as lower restenosis rate after experimental angioplasty. The effects of APN are evidently superior to those of FO.

Angioplasty, Balloon↗
PubMed1993

Effects of captopril on platelet cytosolic free Ca2+ concentrations and on suppression of cell proliferation in culture.

In order to investigate the feasibility of angiotensin converting enzyme inhibitors (ACEIs) in preventing the development of atherosclerosis and restenosis after coronary angioplasty and to study their mechanisms, we measured the platelet cytosolic free Ca2+ concentration ([Ca2+]i) and observed the effects of captopril on platelet [Ca2+]i in rabbits and also observed the inhibitive action on fibroblast proliferation in culture. The results showed that resting platelet [Ca2+]i,ADP- or thrombin-stimulated platelet elevation amplitude after administration of captopril (12.5 mg, twice daily) for 15 days were significantly reduced in comparison with those before administration. And captopril also significantly inhibited fibroblast proliferation or reduced 3H-thymidine (3H-TdR) incorporation in culture in a dose-dependent manner. These findings suggest that ACEIs are promising drugs to reduce restenosis incidence after coronary angioplasty and to prevent atherosclerosis as well as provide a new explanation for their effects of suppressing cell proliferation.

Animals↗
PubMed1993

Experimental studies on prevention of atherosclerotic arterial stenosis and restenosis after angioplasty with Andrographis Paniculata Nees and fish oil.

In order to search for effective drugs to reduce restenosis incidence after coronary angioplasty, we studied the effects of a Chinese herb, extract of Andrographis Paniculata Nees (APN), and Fish Oil (FO) on atherosclerotic stenosis and restenosis after experimental angioplasty. Preliminary results showed that APN can significantly alleviate atherosclerotic iliac artery stenosis induced by both deendothelialization and high cholesterol diet (control group, stenosis incidence 100%, stenotic severe degree 60.53 +/- 31.03%, of which 30% arteries (6) are total occlusion; FO group: stenotic incidence and severe degree are 77% and 53.00 +/- 21.17%, respectively, and in APN group they are 70% and 25.39 +/- 10.52%, respectively, P < 0.01), and follow-up angiography 4 weeks after angioplasty showed that dilated iliac arteries in control group all had severe restenosis, but in APN group no or only mild restenosis occurs, and in FO group restenosis is as severe as stenotic degree prior to angioplasty. These preliminary results suggest that APN and FO can significantly alleviate stenosis induced by deendothelialization and high cholesterol diet and restenosis after angioplasty, while the former has a more marked effect. The above findings lead the authors to conclude that APN may play an important role in preventing restenosis after coronary angioplasty, but FO may be useful in reducing the extent of of restenosis after coronary angioplasty.

Angioplasty, Balloon↗
PubMed1992

Noma neonatorum: an unusual case of noma involving a full-term neonate.

Noma neonatorum is a gangrenous process that occurs in the oral, nasal or anal area and occasionally the eyelids and scrotum of the newborn. The disease is caused by Pseudomonas aeruginosa and usually affects premature ill babies during the first few weeks of life. A full-term neonate with nasal and scrotal noma is uncommon and is therefore reported.

Humans↗
PubMed1991

MOLPACK: molecular graphics for studying the packing of protein molecules in the crystallographic unit cell.

A graphics program, MOLPACK, has been developed on the Silicon Graphics IRIS-4D computer system for displaying the packing of proteins in the crystallographic unit cell. In addition to the normal viewing operations of rotation, translation and scaling, the program has the ability to translate molecules along the cell axes while maintaining their crystallographic equivalent positions within the unit cell. This allows the user to observe the packing of protein molecules generated by molecular replacement, to create a new packing model or to locate an unknown molecule. A special feature of the program is that up to four independent molecules can be manipulated in the asymmetric unit.

Computer Graphics↗
PubMed1991

O6-methylguanine-DNA methyltransferase and human cancer chemotherapy.

Two kinds of human tumor cell strains having different activity of O6-methylguanine-DNA methyltransferase (O6-MT) were transplanted into nude mice. Then the mice were injected intraperitoneally with bifunctional alkylating agent 1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU). The tumors with low O6-MT activity were quickly suppressed or cured. The result suggests that some tumors, if provisionally determined with low O6-MT activity, might be efficiently cured by treatment with ACNU. This probably opens a new way for human cancer chemotherapy.

Animals↗
PubMed1989

Choice of lasers for laser angioplasty.

Thrombi in test-tube, intraarterial thrombi and pig aorta wall were in vitro irradiated with continuous CO2 laser, short pulsal and ultrashort pulsal YAG laser (with pulse-width of 10 ns and 40 ps, respectively) and their double frequency laser and excimer laser with a wave-length of 308 nm and pulse-width of 20 ns. Their effect of vaporizing and ablating (photodecomposing) thrombi and their thermal injuring effect on adjacent tissues were compared and assessed in order to select optimal laser with little thermal injuring and more rapid vaporizing or ablating thrombi effect for laser angioplasty. The experimental results showed that excimer laser, ultrashort pulsal YAG laser and its double frequency laser, and double frequency laser of short pulsal YAG laser, with laser beam and blood vessel kept in a coaxial position, can effectively vaporize or ablate thrombi without thermal injury to vessel wall. So they may be used for laser angioplasty. Of them, especially, excimer laser and double frequency laser of ultrashort pulsal YAG laser have short wave-length and high peak power, and more effectively ablate thrombi than others, so they proved to be optimal lasers for laser angioplasty.

Angioplasty, Balloon↗
PubMed1989

Present status of cesarean section under acupuncture anesthesia in China.

(1) The present status of acupuncture anesthesia for cesarean section in China was presented. (2) Data were divided into two groups by the period, one group containing 24271 cases from 1975 to 1980 in 18 provinces and the other containing 16649 cases from 1981 to 1987 in 5 provinces. The successful rates were 92.1% and 98.9%, and the combined rates of excellent and good degrees were 74.5% and 87.1% in the former and the latter group, respectively. Thus, the effectiveness was significantly elevated in the latter group. (3) Physiological parameters under acupuncture anesthesia were compared with those under epidural anesthesia and local anesthesia. In acupuncture anesthesia, blood pressure, pulse rate and respiration were stable during operation, and blood loss was less than in epidural or local anesthesia. Neither complication nor anesthetic accident occurred during operation under acupuncture anesthesia. The use of acupuncture anesthesia for cesarean section was very safe not only for mother but also for her fetus. (4) Acupuncture anesthesia could be a good anesthetic method for cesarean section.

Acupuncture Analgesia↗
PubMed1989

[A survey of advanced schistosomiasis patients with upper gastrointestinal bleeding].

Among 4,950 advanced schistosomiasis patients examined, 709 (14.3%) had upper gastrointestinal bleeding, and in patients who had been treated with splenectomy, 532 presented history of bleeding. Of the 338 cases with a history of bleeding, 268 (79.3%) ceased bleeding after operation and 70 cases (20.7%) bled again. In 194 cases (7%) who had no history of bleeding before operation, bleeding occurred, suggesting that simple splenectomy has certain effect in preventing upper gastrointestinal bleeding, but the incidence of bleeding is higher in those who had a history of bleeding before operation. Gastrofibroscopic examinations in 50 cases who bled recently indicated that 74% of the patients had gastro-duodenal lesion as a concomitant disease. Prevention and treatment of upper gastrointestinal bleeding of advanced schistosomiasis patients are discussed.

Duodenum↗
PubMed1989

[An experimental study of excimer laser angioplasty in vitro].

Intratube thrombus and in vitro intraarterial thrombus and isolated normal pig aortic wall were radiated by excimer laser with wavelength of 308 nm and pulse width of 20 ns. The single pulse energy and the numbers of pulses were varied at the constant beam size and pulse frequency and the results were studied by micrometer measurement and histological examination. The results show: (1) excimer laser can effectively ablate thrombus. With constant total energy (at the range from 10 to 50 J), the depth of vaporized thrombus was nonlinearly proportional to the single pulse energy. But with constant single pulse energy (at the range from 10-100m J), the depth of vaporized thrombus was in linear proportion to the numbers of pulses; (2) if coaxial position of laser beam with blood vessel was maintained, thrombus can be effectively vaporized without arterial wall damage; (3) the incision produced by excimer laser has microscopically precise edges: there is no evidence of thermal injury and adjacent tissue is unaffected. Our conclusion is that excimer laser can be used safely and effectively in angioplasty. It may be mainly by photochemical effect that excimer laser ablates organic tissue.

Angioplasty, Balloon↗
PubMed1988

A comparison of endocrine pancreatic tissue in adults of four species of lampreys in British Columbia: a morphological and immunohistochemical study.

Histological techniques and immunohistochemistry with antisera against insulin and somatostatin were used in a study of the identification and the distribution of endocrine pancreatic tissue in adults of four species of lampreys in British Columbia. The fine structure of the pancreatic cells of one of the species was also examined. The four species (Lampetra ayresi, Lampetra tridentata, Lampetra macrostoma, and Lampetra richardsoni) all possess cranial and caudal pancreatic masses and an intervening intermediate cord, but there are variations in amount and deposition of the pancreatic tissue with respect to the alimentary canal and the liver which appear to be species specific. There is also some variation in the distribution of pancreatic tissue between L. richardsoni of different stream populations. A newly identified parasitic variety of L. richardsoni in Morrison Creek, called L. richardsoni var. marifuga, usually has no cranial pancreas but has an extensive intermediate cord. The distribution of pancreatic tissue in these lampreys is of relevance to taxonomy and to variations in development of the endocrine pancreas during lamprey metamorphosis. The pancreatic tissue of all species and var. marifuga is composed of cells which are immunoreactive to either insulin or somatostatin antisera. The fine structure of cells from the cranial and caudal pancreatic tissue from L. ayresi does not vary with saltwater and freshwater acclimation. Insulin-containing B cells and somatostatin-containing D cells are present in equal numbers in both pancreatic regions and the cells each have characteristic cytoplasmic granules. A third cell type is most abundant in the cranial pancreas but it is of unknown function.

Animals↗