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Biomedical subjects

D Cheng

Publications and source records attributed to D Cheng.

At least 109 records · Page 6Linked to original sources
PubMed1997

[TGF-beta 1 gene expression in the healing process of skin wound in rat].

For observation of the change of transforming growth factor-beta 1 (TGF-beta 1) gene expression in the process of skin wound healing, the following experiments were performed. Sixteen Wistar rats were chosen. At each side of the rat's back, a 1 cm x 1.5 cm middle-thick skin wound was made. After 3, 6, 9 and 12 days, the specimens were taken from the wounds. For each specimen, half of it was used for RNA extraction, and underwent dot blotting; and the other half was frozen immediately and underwent in situ hybridization. The probes were dig-labeled PDGF-BB cDNA probe and TGF-beta 1 probe. The results showed that TGF-beta 1 gene was expressed mainly in fibroblast, epithelial cell and capillary endothelial cell. The peak of TGF-beta 1 mRNA content was in the 6th day postoperatively. After that, the content of TGF-beta 1 decreased to normal. It was suggested that TGF-beta 1 gene expression was in close relation with healing process. TGF-beta 1 may play an important regulatory role in the skin wound healing.

Animals↗
PubMed1997

[The effect of different way of using FGF on wound healing].

To investigate the best way of using fibroblast growth factor (FGF) in wound healing, the following experiments were performed. Twelve Wistar rats were chosen. Four 1.5 cm x 1.5 cm middle-thick skin wounds were made in the back of each rat, 2 in each side, and labelled as number 1 to 4. Number 1 wound of each rat was used as control, only PBS was applied to the wound, 50 microliters per time, twice a day from the first day to 11th day. Number 2 wound was sustained medication group, 50 microliters 4 micrograms/ml FGF was applied twice a day from the first day to 11th day; Number 3 wound was early medication group, 50 microliters 8 micrograms/ml FGF was applied twice a day from the first day to 5th day; Number 4 wound was late medication group, 50 microliters 8 micrograms/ml FGF was added twice a day from the 5th day to 11th day. By day 4, 8, 12 and 16, the area of wounds were measured, and the healing time of each wound was recorded. The elastic fiber, collagen fiber and DNA content were measured by immunohistological method. The result showed that the elastic fiber, collagen fiber and DNA content in the groups of FGF used were more than those in the control group. The healing time of the control group was 14.4 days while that of the early meduation group was 13.4 days, late medation group was 13.5 days and sustained medication group was 12.2 days. It was suggested that FGF could accelerate the wound healing, and sustained use of FGF was the best way of giving the drug.

Animals↗
PubMed1997

[The problems in the use of superficial cervical artery skin flap and it's relevant solution].

Superficial cervical artery skin flap is widely used in clinical practice. In order to inprove the outcome of the flap in clinic, eleven cases of skin defect of scalp who were treated with the flap was discussed. After operation, the donor area healed but there was no hair growth on recipient area. Among them, six cases occurred partial necrosis of skin flaps. In order to avoid these problen, the relevant solution discussed as follows: 1. Handle well the pedicle of the skin flap to prevent the interference with venous returm. 2. Adhere strictly to indications. 3. Apply skin expander to obtain "extra" skin, then carryout the tranfer of skin flap and 4. Better use the skin flap with residual hair.

Adult↗
PubMed1996

Expression of recombinant alpha Ains-crystallin and not alpha A-crystallin inhibits bacterial growth.

alpha A-Crystallin and alpha Ains-crystallin are derived from the alpha A-crystallin gene via alternative splicing. They are identical except for the presence of a polypeptide, 23 amino acids long, encoded by the 'insert' exon. Evolutionary logic would suggest that the insertion of a 23 amino acid peptide in the middle of alpha A-crystallin, a protein evolving more slowly than either histone H1, cytochrome c or hemoglobin, would lead to appreciable structural and functional changes. However, based on physico-chemical studies, it is presently believed that alpha A-crystallin and alpha Ains-crystallin are functionally equivalent and that the presence of the 'insert' peptide in alpha Ains-crystallin is inconsequential. We report here that the independent expression of recombinant alpha Ains-crystallin, and not alpha A-crystallin, inhibits growth of the bacterial host. These observations were confirmed in coexpression experiments, wherein both the proteins were expressed in the same cell. Interestingly, growth inhibition is reversible. Importantly, the data demonstrate that it is catalytic amounts and not the gross accumulation of alpha Ains-crystallin which causes growth inhibition. Given the prior knowledge that alpha A-crystallin and alpha Ains-crystallin differ by a peptide of 23 amino acids, these data suggest that the "insert peptide' in alpha Ains-crystallin imparts properties on this protein that are different from alpha A-crystallin.

Animals↗
PubMed1996

Split fractures of the lateral tibial plateau: evaluation of three fixation methods.

A laboratory study was performed to compare the stability and ultimate strength of three standard fixation techniques for split-type lateral tibial plateau fractures. The three methods of fixation were (a) three 6.5-mm cancellous lag screws with washers; (b) two 6.5-mm cancellous lag screws with washers and an additional antiglide 4.5-mm cortical screw with washer; and (c) six-hole L-shaped buttress plate. Twelve pairs of embalmed mildly osteopenic lower extremities were used. Simulated split-type lateral tibial plateau fractures were created, reduced, and then instrumented in a matched pair design. The instrumented specimens were axially loaded to determine resistance to displacement, cyclically loaded to 10,000 cycles to determine dynamic stability, and then loaded to failure. There were no statistically significant differences found between resistance to displacement or failure strength as a function of either fragment size or sample bone density. On the basis of biomechanical stability, there appears to be no difference between the three fixation techniques tested. The results of this study suggest that use of an antiglide screw or buttress plate does not offer an advantage over lag screw fixation alone for the treatment of split type lateral tibial plateau fractures.

Biomechanical Phenomena↗
PubMed1996

Preconception health care for the primary care practitioner.

There will always be birth defects and pregnancy complications due to factors beyond our control. However, we are rapidly discovering many interventions women can use to optimize their chances of having a healthy pregnancy and baby. Most of these, such as immunization and normalization of a diabetic woman's glycosylated hemoglobin level, are most effective when begun before conception. Since the discovery of the congenital rubella syndrome in 1941, there has been a steady accumulation of information on the prevention of birth defects through preconception health. In just the last few years, we have learned that folic acid can decrease neural tube defects, angiotensin converting enzyme inhibitors are teratogenic, and zidovudine can decrease the vertical transmission rate of human immunodeficiency virus. The Varivax vaccine released last year is expected to decrease the perinatal morbidity from varicella. By using the time before conception, we may be able to fully maximize the benefits of good nutrition, exercise, medical screening, and avoidance of environmental toxins.

Female↗
PubMed1996

[Protective and treated effects of L-arginine on hypoxia-induced pulmonary hypertension in rats].

The protective and treated effects of L-Arginine on isobaric hypoxia-induced pulmonary hypertension were studied in rats. It was found that L-Arginine significantly inhibits hypoxic pulmonary hypertension and right ventricular hypertrophy. The mean pulmonary arterial pressure (mPAP) was 3.58 +/- 0.06 kPa and right ventricle/(left ventricle plus septum) ratio [RV/(LV+S)] was 0.34 +/- 0.01 in rats exposed to hypoxia (FiO2 = 0.10 +/- 0.05) for 3 weeks. The mPAP was 2.61 +/- 0.09 kPa and RV/(LV+S) was 0.26 +/- 0.01 in rats pretreated with L-Arginine [200mg/(kg.d)]i there is significant difference between the two groups. We also found that L-Arginine (300mg/kg) can decrease mPAP in rats with hypoxic pulmonary hypertension. The results suggest that L-Arginine might have significant protential for protection and treatment of hypoxic pulmonary hypertension.

Animals↗
PubMed1996

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

OBJECTIVE: To evaluate the effects of Ginkgolide B, a specific platelet activating factor (PAF) antagonist, on hypoxia-induced pulmonary hypertension and pulmonary vascular remodeling. MATERIALS AND METHODS: Forty male Wistar rats were divided into 4 groups, receiving normal saline, Ginkgolide B, isobaric hypoxia and isobaric hypoxia plus Ginkgolide B respectively. Pulmonary hemodynamics were assessed via right heart catheterization. Pulmonary vascular remodeling were examined by a computerized image analyser. RESULTS: Chronic hypoxia (FiO2 = 0.10, 3 weeks) caused pulmonary hypertension, pulmonary vascular remodeling and right ventricular hypertrophy in rats. Treatment with Ginkgolide B reduced the extent of pulmonary hypertension, pulmonary vascular remodeling and right ventricular hypertrophy induced by hypoxic exposure. CONCLUSIONS: The results suggest that PAF participates in the process of chronic hypoxic pulmonary hypertension and pulmonary vascular remodeling, and PAF antagonist could be a potentially useful agent for preventing hypoxic pulmonary hypertension.

Animals↗
PubMed1996

[Effects of ginkgo plus on hypoxic pulmonary hypertension in rats].

We examined the effects of Ginkgo Plus on the pulmonary hemodynamics and right ventricular hypertrophy in rats exposed to isobaric chronic hypoxia. The rats treated with chronic hypoxia developed pulmonary hypertension and right ventricular hypertrophy. Ginkgo Plus reduced significantly the hypoxia-induced increase of mean pulmonary arterial pressure and pulmonary vascular resistance as well as the ratio of right ventricular weight vs left ventricular plus septal weights. The results suggested that Ginkgo Plus could relieve the hypoxic pulmonary hypertension.

Animals↗
PubMed1996

[The level of platelet activating factor in blood of rats with hypoxic pulmonary hypertension].

Because hypoxia is a known predisposing factor for pulmonary hypertension, we investigated the effects of hypoxia and platelet activating factor (PAF) on the development of pulmonary hypertension in rats. Male Wistar rats were made hypoxic by placing them in a isobaric hypoxic chambar (O2 = 10%) for 3 weeks; the rats developed pulmonary hypertension and right ventricular hypertrophy. We found that PAF level in blood of rats were significantly elevated at 2-3 weeks of hypoxia (280.8 +/- 119.7 ng/ml and 324.2 +/- 67.6 ng/ml vs 148.3 +/- 60.2 ng/ml). Therefore, we conclude that PAF plays a central role in mediating hypoxia-induced pulmonary hypertension.

Animals↗
PubMed1996

[The role of platelet activating factor in chronic pulmonary hypertension].

To investigate the chronic effects of platelet activating factor (PAF) on pulmonary circulation, we administered PAF to 15 male Wistar rats in low doses by intraperitoneal injection for 28 days. The results showed that after PAF treatment the mean pulmonary arterial pressure increased by 1.17 kPa, the pulmonary vascular resistance increased by 2409.3 kPa.s/L, the cardiac output decreased by 9.1 ml/min and the ratio of right ventricular weight to left ventricular plus septal weights increased by 0.1, compared with control. Histologic sections of the lungs were examined under light microscope equipped with a computerized image analyser. The wall of pulmonary arterioles was thickened; the percent of vascular wall thickness/vascular external diameter and percent of vascular wall area/total vascular area were increased in the PAF group (P < 0.05). These suggest that PAF may play an important role in the pathogenesis of chronic pulmonary hypertension.

Animals↗
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↗