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Biomedical subjects

D Cheng

Publications and source records attributed to D Cheng.

At least 127 records · Page 7Linked to original sources
PubMed1996

[An observation on calcium ion overloaded injury and the effect of calcium channel blocker in rabbit retina under acute ocular hypertension].

OBJECTIVE: In order to observe the retinal injury by Ca+2 overload under ocular hypertension and the effect of verapamil treatment. METHODS: Atomic absorption spectrophotometry and phosphate pyroantemonate (PPA) means were used to observe the changes of rabbit retinal Ca+2 content and the therapeutic effects of verapamil under this situation. RESULTS: In the ocular hypertensive group, Ca+2 increased from the moment of intraocular pressure elevation, and with prolongation of time, it tended to increase steadily. In comparison with the control group, there were significant differences (P < 0.01). PPA showed that the longer the time, the more obvious swollen the mitochondria and much more calcium deposition in the mitochondria. In the group of rabbits with ocular hypertension having taken verapamil treatment, the Ca+2 content was markedly lower, the changes of mitochondria milder and the Ca+2 deposition in mitochondria less than that of the ocular hypertension group without treatment. CONCLUSION: Calcium-overload may be one of the reasons of retinal injury under ocular hypertension, while calcium-blocker may alleviate this injury.

Animals↗
PubMed1995

Regulation and immunolocalization of acyl-coenzyme A: cholesterol acyltransferase in mammalian cells as studied with specific antibodies.

Acyl-coenzyme A:cholesterol acyltransferase (ACAT) catalyzes the formation of intracellular cholesterol esters in various tissues. We recently reported the cloning and expression of human macrophage ACAT cDNA. In the current study, we report the production of specific polyclonal antibodies against ACAT by immunizing rabbits with the recombinant fusion protein composed of glutathione S-transferase and the first 131 amino acids of ACAT protein. Immunoblot analysis showed that the antibodies cross-reacted with a 50-kDa protein band from a variety of human cell lines. These antibodies immunodepleted more than 90% of detergent-solubilized ACAT activities from six different human cell types, demonstrating that the 50-kDa protein is the major ACAT catalytic component in these cells. In multiple human tissues examined, the antibodies recognized protein bands with various molecular weights. These antibodies also cross-reacted with the ACAT protein in Chinese hamster ovary cells. Immunoblot analysis showed that the ACAT protein contents in human fibroblast cells, HepG2 cells, or Chinese hamster ovary cells were not affected by sterol in the medium, demonstrating that the main mechanism for sterol-dependent regulation of ACAT activity in these cells is not change in ACAT protein content. As revealed by indirect immunofluorescent microscopy, the ACAT protein in tissue culture cells was located in the endoplasmic reticulum. This finding, along with earlier studies, suggests that cholesterol concentration in the endoplasmic reticulum may be the major determinant for regulating ACAT activity in the intact cells.

Animals↗
PubMed1995

Activation of acyl-coenzyme A:cholesterol acyltransferase by cholesterol or by oxysterol in a cell-free system.

Acyl-coenzyme A:cholesterol acyltransferase (ACAT) is an intracellular enzyme that catalyzes the conjugation of long chain fatty acid and cholesterol to form cholesteryl esters. It is an integral membrane protein located in the endoplasmic reticulum. Experiments performed in intact mammalian cells have shown that the rate of cholesteryl ester synthesis in intact cells, as well as the ACAT activity from cell extracts, are greatly activated by the addition of low density lipoprotein (LDL) or oxygenated sterols such as 25-hydroxycholesterol to the growth medium. However, the molecular mechanism(s) by which sterol(s) stimulate the ACAT activity remains to be elucidated. Recently, our laboratory reported the expression cloning of human ACAT cDNA (Chang, C. C. Y., Huh, H. Y., Cadigan, K. M., and Chang, T. Y. 1993) J. Biol. Chem. 268, 20747-20755). In the current study, we report the expression of human ACAT cDNA in insect Sf9 cells. Uninfected Sf9 cells do not express detectable ACAT-like activity. Infecting these cells with recombinant virus containing ACAT cDNA caused these cells to express high levels of ACAT protein and high levels of ACAT activity when assayed in vitro. The catalytic properties of ACAT expressed in these cells were found to be similar to those found in human tissue culture cells. The combination of high level of ACAT protein expression and the low level of cellular cholesterol content in the infected cells have provided us a novel opportunity to establish a simple cell-free system, whereby stimulation of ACAT by sterols can be readily demonstrated. Using this system, we have shown that cholesterol itself can serve as an ACAT activator in vitro, in addition to its role as an ACAT substrate. The current work provides the experimental basis to hypothesize that, inside mammalian cells, cholesterol itself may serve as a physiological regulator of ACAT.

Amino Acid Sequence↗
PubMed1995

Coagulopathies in patients after transurethral resection of the prostate: spinal versus general anesthesia.

This prospective, randomized study evaluated the effects of spinal versus general anesthetic technique on perioperative blood loss and the development of postoperative coagulopathies in 50 patients undergoing transurethral resection of the prostate (TURP). Preoperative hematologic measurements included hemoglobin, platelet count, electrolytes, prothrombin time, partial thromboplastin time, fibrinogen, factor V, plasminogen, antithrombin III, and fibrinogen degradation product (FDP) levels. All hematologic blood samples wre repeated postoperatively at 1, 6, and 24 h. Intraoperative blood loss was not significantly different between the spinal and general anesthesia groups. The total blood loss after TURP was significantly correlated (r = 0.76; P < 0.0001) with the prostatic tissue weight. When the tissue weight resected exceeded 35 g, blood loss was in excess of the linear correlation shown with the weight of resected prostatic tissue. Platelet count decreased and prothrombin time increased in the spinal group at all postoperative time intervals compared to preoperative value (P < 0.05). There was no significant difference in measured coagulation variables (fibrinogen, factor V, plasminogen, antithrombin III, and FDP) between the spinal and general anesthesia groups, but there were significant decreases in postoperative fibrinogen and Factor V levels compared to preoperative values in both spinal and general anesthesia groups. Three patients (6%) had increased FDP levels 1 h postoperatively. The prostatic tissue weight and the surgical duration was significantly higher in these patients. We conclude that perioperative blood loss in TURP patients is not affected by the anesthetic technique. However, 6% of TURP patients developed subclinical intravascular coagulopathies which correlated with mass of resected prostate tissue.

Aged↗
PubMed1995

Radiology uses of the Internet.

The Internet promises to be an essential resource for radiology administrators. In addition to offering remarkable access to colleagues all over the world, the Internet offers specialized information resources for radiology, many of which are described in this article. The Internet is many networks that communicate with each other and whose general purpose is to share information. Although there are several consortium organizations that support and regulate it, no single body or organization "owns" the Internet. Many employees and students at large teaching centers already have access to the Internet through their institution's connection. Individuals and small institutions can contract with independent service providers for Internet access. Internet functions covered in this article include: e-mail, listservs, newsgroups, file transfer protocols, Gopher, and the World Wide Web. The rapid pace of information exchange is making the world of radiology smaller and more intimate. Communication and knowledge are becoming so accessible that individuals are privy to the most minute happenings in the industry. Sharing information on the Internet will benefit not only individual users and the industry, but also patients.

Commerce↗
PubMed1995

[Acute effect of milrinone on pulmonary hemodynamics in patients with hypoxic pulmonary hypertension].

Milrinone is a phosphodiesterase inhibitor that has vasorelaxant activity. The authors studied its effect on pulmonary haemodynamics in 12 patients with hypoxic pulmonary hypertension. After treatment with milrinone, mean pulmonary arterial pressure (from 4.61 +/- 1.41 kPa to 3.36 +/- 1.20 kPa, 1kPa = 7.5mmHg) and pulmonary vascular resistance (from 557.56 +/- 167.70 dyne.sec.cm-5 to 392.60 +/- 133. 81 dyne.sec.cm-5) decreased (P < 0.05), while cardiac output increased (from 5.11 +/- 1.62 L/min to 5.62 +/- 1.66 L/min) (P > 0.05). The systemic blood pressure (from 11.50 +/- 1.63 kPa to 10.71 +/- 1.83 kPa) and systemic vascular resistance (from 1476.64 +/- 531.52 dyne.sec.cm-5 to 1,236.49 +/- 410.18 dyne.sec.cm-5) also decreased (P > 0.05). but there was no change in arterial oxygen saturation (SaO2). The incidence of side effects were low, 4 patients developed tackycardia, and 2 patients developed ventricular premature beats. It is therefore, shown that milrinone is a potent pulmonary vasodilator.

Aged↗
PubMed1995

[Acute effects of platelet activating factor on the pulmonary circulation in rats].

To investigate the acute effects of platelet activating factor (PAF) on pulmonary circulation and cardiovascular function in rats, twenty anesthetized Wistar rats were given 100-800 ng/kg PAF by bolus intrapulmonary artery infusion. Mean pulmonary artery pressure (mPAP), mean systemic artery pressure (mSAP) and cardiac output (CO) were measured before and after administration. The results showed that PAF infusion caused: a rise in mPAP from 2.11 +/- 0.20 kPa to 2.65 +/- 0.11 kPa (100 ng/kg, P > 0.05), from 2.32 +/- 0.25 kPa to 2.85 +/- 0.24 kPa (200 ng/kg, P < 0.05) and from 2.11 +/- 0.33 kPa to 3.01 +/- 0.45 kPa (400 ng/kg, P < 0.05)p; a down in mSAP from 16.0 +/- 2.11 kPa to 9.1 +/- 2.39 kPa (100 ng/kg, P < 0.05); from 16.3 +/- 1.38 kPa to 7.0 +/- 0.57 kPa (200 ng/kg, P < 0.05) and from 16.4 +/- 2.56 kPa to 6.3 +/- 0.89 kPa (400 ng/kg, P < 0.05); and a down in CO from 48.1 +/- 2.16 ml/min to 30.8 +/- 3.27 ml/min (100 ng/kg, P < 0.05), from 47.8 +/- 2.12 ml/min to 25.6 +/- 2.86 ml/min (200 ng/kg, P < 0.05) and from 48.3 +/- 2.24 ml/min to 20.0 +/- 2.39 ml/min (400 ng/kg, P < 0.05). These findings suggested that PAF play an important role in the pathophysiologic course of pulmonary hypertension.

Animals↗
PubMed1995

[The delayed traumatic intracerebral haematomas].

The results of CT observation of 378 inpatients with head injury were reported. 46 delayed traumatic intracerebral haematomas (DTICH) patients were found to have 71 haematomas. The incidence of DTICH was 12.2%. 80.7% of DTICH patients were noted 48 hours after injury. Most of them were young and middle aged persons. The places of baematomas were at the injured zones. The intracranial pressure continous monitor is useful to judge the DTICH during the early stage. Surgical operation is proposed for the patients with many haematomas and displaced central tissue. The haematomas should be cleansed for the frequently occurring haematoma patients. The death rate of the example was 17.4%, which was lower than 44%-71% reported elsewhere.

Adolescent↗
PubMed1995

[Distribution of platelet activating factor in the pulmonary tissues of normal rats].

Platelet activating factor (PAF) is a biologically active phospholipid with a broad range of cellular targets and respective responses. Because lung homogenates obtained from normal rats contain measurable levels of PAF, it may be involved in both pathological and physiological processes of lung. In this study, we have searched for the distribution of PAF in the rat lungs by immunohistochemistry. We demonstrated that PAF immunoreactivity is present on pulmonary arterial and alveolar walls. The results showed that PAF are located in pulmonary arterial and alveolar wall under normal condition, and that PAF may play a role in maintaining pulmonary physiological process.

Animals↗
PubMed1995

[Effect of tetrandrine on pulmonary hypertension induced by monocrotaline in rats].

The effects of Tetrandrine (Tet) on intraacinous pulmonary arteries (IAPA) and bemodynamics were studied by means of a rat pulmonary hypertension model induced by monocrotaline. The results showed that Tet could reduce the contractive pressure of pulmonary artery, right ventricle and right atrium of heart by 28.0%, 28.3%, and 31.5% respectively. It could also decrease the vascular degeneration of endoepithelial cells of IAPA, the endoepithelial subcavity, the collagens of medial membrane and the numbers of smooth muscles of IAPA.

Alkaloids↗
PubMed1995

[Effects of ginkgolide B on isobaric hypoxic pulmonary hypertension in rats].

We examined the effects of ginkgolide B (BN52021), a specific platelet activating factor (PAF) antagonist, on hypoxia-induced pulmonary hypertension and pulmonary vascular remodeling. Chronic hypoxia can cause pulmonary hypertension and pulmonary vascular remodeling in rats. Treated with BN52021, the rat's pulmonary hypertension, pulmonary vascular remodeling and right ventricular hypertrophy at 3 weeks of hypoxic exposure (FiO2 = 0,10) could be reduced. The results suggest that PAF contributes to the development of chronic hypoxic pulmonary hypertension and pulmonary vascular remodeling, and PAF antagonist may be an useful agent for preventing hypoxic pulmonary hypertension.

Animals↗
PubMed1994

Hepatitis delta virus replication in vitro is not affected by interferon-alpha or -gamma despite intact cellular responses to interferon and dsRNA.

The hepatitis delta virus (HDV) genome consists of circular ssRNA which has extensive intramolecular complementarity and can form a dsRNA rod-like structure. If such RNA species were to exist in an unmasked form in cells, they would be expected to induce interferon (IFN) expression and activate two IFN-inducible dsRNA-dependent enzymes with anti-viral activity, namely the dsRNA-dependent protein kinase (PKR) and 2',5' oligoadenylate (2',5' A) synthetase. Since the virus replicates to high copy number for prolonged periods in infected cells it is apparently able to evade these antiviral mechanisms. The RNA genome may be masked and fail to induce or activate the antiviral response, or the virus may inhibit such a response. Treatment of a hepatoma cell line, Huh7, and a fibrosarcoma cell line, HT1080, stably transfected with a trimeric HDV cDNA construct, with IFN-alpha or IFN-gamma for up to seven days failed to influence the level of expression of genomic or antigenomic HDV RNA, or delta antigen (Ag). This is consistent with either failure of activation or inhibition of the IFN response. However the induction of several IFN-responsive genes, including PKR, 2',5' A synthetase and class I MHC is normal and cotransfection of a construct expressing delta Ag did not affect expression from an IFN-inducible chloramphenicol acetyltransferase construct. In addition, the activation of PKR is not inhibited in HDV-expressing cells and antiviral assays suggest that the ability of these cells to mount an antiviral response to at least two cytopathic viruses is unaffected. IFN-beta is inducible normally by dsRNA in cells transfected with the delta cDNA trimer. We conclude that HDV replication is not inhibited by IFN-alpha or IFN-gamma, even though the responses of cells expressing HDV RNA and antigen to IFN and dsRNA are intact.

2',5'-Oligoadenylate Synthetase↗
PubMed1994

High density cultivation of a recombinant CD-1 cell line producing prourokinase using a Biosilon microcarrier culture system.

CD-1, a genetically-engineered CHO cell line, was cultivated with a Biosilon microcarrier culture system. We successfully cultivated CD-1 cells to a very high density (over 1 x 10(7) cells/ml). Prourokinase was stably secreted at about 180 IU/10(6) cells/24 h. Experiments showed that CD-1 cells growing on Biosilon microcarriers were able to spontaneously release from the microcarriers, then reattach and proliferate on fresh microcarriers. This makes it very easy to scale up production. The microcarriers could be reused several times without affecting adhesion, proliferation and prourokinase secretion. With CM-PECC membrane radial flow chromatography and MPG chromatography, the prourokinase in conditioned medium could be purified to a specific activity of 1 x 10(5) IU/mg of protein. The purification factor was about 600 fold, and approximately 90% of the biological activity was recovered.

Animals↗
PubMed1994

[Clinical application of neurovascular island flap in the hand].

From 1962 to 1992, four kinds of neurovascular island flaps of the hand were used for the treatment of skin defects in the hand in 72 cases. Of these flaps, 38 were pulp flaps of the finger, 24 were based on the first dorsal metacarpal artery, 7 were from second dorsal metacarpal artery and 3 were from hypothenar area. All the flaps survived except 1. Postoperative follow-up showed excellent or good results in 94.4%. The indications of the operation, flap design and surgical procedure are described. The anatomical feature, the advantages and disadvantages of the flap are discussed.

Adolescent↗