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Biomedical subjects

D Cheng

Publications and source records attributed to D Cheng.

At least 73 records · Page 4Linked to original sources
PubMed1999

[Endarterectomy for carotid stenosis].

OBJECTIVE: To discuss the indications, anesthesia and surgical techniques of carotid endarterectomy (CEA). METHODS: Twenty-two sides of carotid stenosis were revealed in 20 patients. CEA was performed under general anesthesia in 21 sides and local anesthesia in one. The time of carotid occlusion ranged from 27 to 52 minutes (average 35.5 min) in 20 operations, and intraoperative shunt was used in the other two. Fifteen operations were monitored with EEG. RESULTS: The postoperative course was uneventful in 17 patients after 18 operations, while transient muscle strength decrease on contralateral side and ipsilateral lower facial paresis occurred after three operations in the other three patients. Nineteen patients were followed-up for 38 months on the average. Among nine patients with TIA, ischemic attacks ceased in eight and decreased in one. Improvement was achieved in six patients with cerebral infarction. One patient without symptoms of carotid ischemia was still normal after operation. CONCLUSION: Carotid endarterectomy is a safe and effective way for treating carotid stenosis.

Adult↗
PubMed1999

[The change of plasma level of endothelin-1 in patients with cor pulmonale and the effects of Captopril].

The purpose of this study was to investigate the role of endothelin(ET) in the development of cor pulmonale and the mechanism of captopril in treatment. The plasma ET-1 levels of 36 patients with cor pulmonale and 20 normal subjects were measured by radioimmunoassay. Twenty patients were treated with antibiotics and oxygen, and the other 16 patients were treated with antibiotics, oxygen and captopril for 14 days. The results showed that the ET-1 level of patients with cor pulmonale (88.9 +/- 8.9 ng/L) was significantly higher than that of normal control (53.5 +/- 5.1 ng/L). After treatment, the ET-1 level declined significantly in both groups of patients (P < 0.01); the ET-1 level in patients treated with captopril was lower than that in patients not treated with captopril (P < 0.05), but the level of ET-1 in patients was still higher than that of normal control (P < 0.05). These suggest that ET-1 may play an important role in the onset of cor pulmonale and captopril can reduce the ET-1 level.

Adult↗
PubMed1999

[The diagnostic and therapeutic value of flexible bronchoscopy in foreign-body aspiration misdiagnosed as other respiratory diseases].

To explore the causes of missed diagnosis of foreign-body aspiration and summarize the experiences on the diagnostic and therapeutic use of flexible bronchoscopy (FB) in these patients. Twelve cases of foreign-body aspiration misdiagnosed as other respiratory diseases, confirmed by FB examination were analyzed. All of these patients had no histories of foreign-body aspiration, and no foreign-body shadows were found on their chest films. But there were atelectasis, hilar enlargement and obstructive pneumonia found on the films. Among the patients in this group, 7 cases were misdiagnosed as lung cancer, 2 cases of pneumonia and asthma each, and 1 case as tuberculosis. The diagnoses of all the 12 cases were confirmed by FB examinations. The foreign-bodies of the 11 cases were successfully grasped and taken out through the FB. This suggests that FB should be of great diagnostic and therapeutic value in patients with foreign-body aspiration misdiagnosed as other respiratory diseases.

Adolescent↗
PubMed1998

Isolation of cholesterol-requiring mutant Chinese hamster ovary cells with defects in cleavage of sterol regulatory element-binding proteins at site 1.

The synthesis and uptake of cholesterol requires transcription factors designated sterol regulatory element-binding proteins (SREBPs). SREBPs are bound to membranes in a hairpin orientation with their transcriptionally active NH2-terminal segments facing the cytosol. The NH2-terminal segments are released from membranes by two-step proteolysis initiated by site 1 protease (S1P), which cleaves in the luminal loop between two membrane-spanning segments. Next, site 2 protease (S2P) releases the NH2-terminal fragment of SREBP. The S2P gene was recently isolated by complementation cloning using Chinese hamster ovary cells that require cholesterol for growth, due to a mutation in the S2P gene. A similar approach cannot be used for S1P because all previous cholesterol auxotrophs manifest defects in S2P, which is encoded by a single copy gene. To circumvent this problem, in the current studies we transfected Chinese hamster ovary cells with the S2P cDNA, assuring multiple copies. We mutagenized the cells, selected for cholesterol auxotrophy, and identified two mutant cell lines (SRD-12A and -12B) that fail to cleave SREBPs at site 1. Complementation analysis demonstrated that the defects in both cell lines are recessive and noncomplementing, indicating a mutation in the same gene. These cells should now be useful for expression cloning of the sterol-regulated S1P gene.

Acetates↗
PubMed1998

Pharmacokinetics of doxacurium during normothermic and hypothermic cardiopulmonary bypass surgery.

PURPOSE: To compare the pharmacokinetic behaviour of doxacurium in patients undergoing normothermic or hypothermic cardiopulmonary bypass (CPB) for coronary artery bypass graft surgery. METHODS: Twenty patients in two equal groups were studied. Anaesthesia was induced with sufentanil and midazolam after a standard premedication. Doxacurium was administered at 3 x ED95 (80 micrograms.kg-1), and anaesthesia was maintained with 0.5 microgram.kg-1 hr-1 sufentanil, 0.05 mg.kg-1 midazolam and isoflurane 0.5-1%. Systemic temperature for patients in the normothermic and hypothermic groups was maintained at 33-36 C and 26-30 C respectively. Timed blood and urine samples were collected and pharmacokinetic parameters were estimated using a non-compartmental approach. RESULTS: For the normothermic and hypothermic groups, terminal elimination half-life (t1/2 beta) was 100.1 +/- 28 and 183.8 +/- 60 min (P < 0.05) respectively, elimination half-life during the CPB phase (T1/2 CPB) 114.5 +/- 10 and 183.8 +/- 60 min (P < 0.05), mean residence time 108.8 +/- 25 and 164.8 +/- 34 min (P < 0.05) and apparent volume of distribution at steady state 0.20 +/- 0.03 and 0.26 +/- 0.04 L.kg-1 (P < 0.05). Compared with the hypothermic group, the normothermic group had a higher rate of renal clearance (1.40 +/- 0.4 vs 0.93 +/- 0.3 ml.min-1.kg-1; P < 0.05) and a higher value for renal clearance as a percentage of the total clearance (76.2 +/- 10 vs 58.3 +/- 20%). CONCLUSION: The elimination rate of doxacurium during normothermic CPB is faster than that in hypothermic CPB.

Aged↗
PubMed1998

MR imaging of the prostate and bladder.

Magnetic resonance imaging has become an important imaging modality for the male pelvis. Its unparalleled ability to depict soft tissue structures and highlight pathology have made it the best method for determining the extent of many disease processes. This article reviews the use of MR to evaluate diseases of the prostate gland and bladder. In both, the major indication for imaging is the local staging of cancer, and MR is currently the best imaging modality. This article will discuss the critical clinical issues concerning prostate cancer and neoplasms of the bladder, and the contribution of MR imaging.

Humans↗
PubMed1998

Molecular identification of the sterol-regulated luminal protease that cleaves SREBPs and controls lipid composition of animal cells.

The lipid composition of animal cells is controlled by SREBPs, transcription factors released from membranes by sterol-regulated proteolysis. Release is initiated by Site-1 protease (S1P), which cleaves SREBPs in the ER luminal loop between two membrane-spanning regions. To clone S1P, we prepared pCMV-PLAP-BP2, which encodes a fusion protein that contains placental alkaline phosphatase (PLAP) in the ER lumen flanked by cleavage sites for signal peptidase and S1P. In sterol-deprived cells, cleavage by both proteases leads to PLAP secretion. PLAP is not secreted by SRD-12B cells, cholesterol auxotrophs that lack S1P. We transfected SRD-12B cells with pCMV-PLAP-BP2 plus pools of CHO cDNAs and identified a cDNA that restores Site-1 cleavage and PLAP secretion. The cDNA encodes S1P, an intraluminal 1052-amino-acid membrane-bound subtilisin-like protease. We propose that S1P is the sterol-regulated protease that controls lipid metabolism in animal cells.

Alkaline Phosphatase↗
PubMed1998

Localization of hepatitis delta virus RNA in the nucleus of human cells.

Hepatitis delta virus (HDV) is a human pathogen that can greatly increase the severity of liver damage caused by an hepatitis B infection. HDV contains a circular, single-stranded RNA genome that encodes a unique protein, the delta antigen. Two forms of the delta antigen, deltaAg-S and deltaAg-L, are derived from a single open reading frame by RNA editing. Here we analyze the subcellular distribution of HDV RNA and its spatial relationship to known intranuclear structures. The human hepatoma cell line Huh7 was stably transfected with wild-type HDV cDNA and the viral RNAs were localized by in situ hybridization and fluorescence confocal microscopy. HDV RNA is detected throughout the nucleoplasm, with additional concentration in focal structures closely associated with nuclear speckles or clusters of interchromatin granules. Both the smaller form of the delta antigen (deltaAg-S), which is required for HDV genomic replication, and the larger form of the delta antigen (deltaAg-L), which represses replication, co-localize with delta RNA throughout the nucleoplasm and in the foci. However, the foci do not incorporate bromo-UTP and do not concentrate either RNA polymerase II or cleavage and polyadenylation factors required for viral RNA synthesis and 3' end processing, respectively. Thus, it is unlikely that the delta foci represent major sites of viral transcription or replication. In conclusion, the data show that viral RNA-protein complexes accumulate in structures closely associated with interchromatin granules, a subnuclear domain highly enriched in small nuclear ribonucleoproteins, poly(A+) RNA, and RNA splicing protein factors. This implies a specific compartmentalization of ribonucleoproteins in the nucleus.

Carcinoma, Hepatocellular↗
PubMed1998

In vitro resistance to thrombin-induced platelet microbicidal protein among clinical bacteremic isolates of Staphylococcus aureus correlates with an endovascular infectious source.

Platelet microbicidal proteins (PMPs), small cationic peptides released at sites of endovascular damage, kill common bloodstream pathogens in vitro. Our group previously showed that in vitro resistance of clinical staphylococcal and viridans group streptococcal bacteremic strains to PMPs correlated with the diagnosis of infective endocarditis (IE) (Wu et al., Antimicrob. Agents Chemother. 38:729-732, 1994). However, that study was limited by (i) the small number of Staphylococcus aureus isolates from IE patients, (ii) the retrospective nature of the case definitions, and (iii) the diverse geographic sources of strains. The present study evaluated the in vitro PMP susceptibility phenotype of a large number of staphylococcemic isolates (n = 60), collected at a single medical center and categorized by defined and validated clinical criteria. A significantly higher proportion of staphylococcemic strains from patients with IE was PMP resistant in vitro than the proportion of strains from patients with soft tissue sepsis (83% and 33%, respectively; P < 0.01). Moreover, the levels of PMP resistance (mean percent survival of strains after 2-h exposure to PMP in vitro) were significantly higher for isolates from patients with IE and with vascular catheter sepsis than for strains from patients with abscess sepsis (P < 0.005 and P < 0.01, respectively). These data further support the concept that bloodstream pathogens that exhibit innate or acquired PMP resistance have a survival advantage with respect to either the induction or progression of endovascular infections.

Anti-Bacterial Agents↗
PubMed1998

Scattering properties of Bagolini lenses and their effects on spatial vision.

The effect of a Bagolini lens on spatial vision was investigated by studying its far-field diffraction pattern as produced by a coherent beam of laser light, and its effect on the contrast sensitivity function (CSF) in human subjects. For lenses of the main type studied, which were crossed by a series of slightly-irregular striated bands, each consisting of fine, parallel, etched lines of various widths and separations, the diffraction pattern consisted of undiffracted light giving a bright central spot and wide-angle, diffracted light giving a dim streak. The latter was due to the sum of the diffraction patterns associated by the irregular fine etched lines. The streak produced by a single striated band was modulated by a series of regular maxima and minima related to the width of the band. Analysis of this pattern gave the width of the band as 0.6 mm, in close agreement with direct microscopical measurements. When four bands were illuminated by a beam of about 3 mm diameter, similar to the diameter of the photopic pupil, the diffraction pattern showed no obvious maxima and minima, due to irregularity in the width and separation of the bands. The central spot contained more than 90% of the total light in the diffraction pattern. Thus the Bagolini lens, with its relatively weak far-field diffraction pattern lacking regular maxima and minima when areas > or = 3 mm in diameter were used, was expected to have only a small effect on the apparent contrast of the targets in CSF experiments. This was confirmed by the measurements: Bagolini lenses showed no significant effect on either the monocular or binocular CSF. Further similar measurements with lenses of slightly different design from another manufacturer confirmed these findings. Therefore Bagolini lenses do not disrupt vision when they are used to determine the presence of suppression and anomalous retinal correspondence.

Contrast Sensitivity↗
PubMed1998

[Therapeutic effects of ultrashort wave and He-Ne laser on experimental infection in skin flaps of rabbits].

In order to investigate the therapeutic effects of ultrashort wave and He-Ne laser on experimentally infected skin flaps, 24 lower abdominal skin flaps on 24 rabbits were established, under each flap 1 ml of S. aureus (9 x 10(8) bacterials/ml) was injected respectively. Then, ultrashort wave and He-Ne laser were utilized respectively in 2 groups once a day for 6 days, with on treatment in two another two groups as control groups. After the period of treatment, the 4 groups were evaluated in the bacterial amounts, thickness of skin flaps and degree of infection. The results showed that the skin flaps in the treatment groups were much better than those in the control groups. It suggested that both the ultrashort wave and He-Ne laser are helpful in the treatment of infection of S. aureus in skin flaps.

Animals↗
PubMed1998

[Cromakalim inhibits endothelin-1 induced pulmonary hypertension in rats].

There is evidence that endothelin-1 (ET-1) and potassium channel may play an important role in the development of pulmonary hypertension. To evaluate the effect of ATP-sensitive K+ channel opener on pulmonary hypertension induced by ET-1, catheter was inserted into the pulmonary artery in ten male Wistar rats which had had pulmonary hypertension established by infusion of ET-1 (1.5 micrograms/kg), and then cromakalim were injected with a dose of 150 micrograms/kg. The mean pulmonary arterial pressure (mPAP), cardiac output (CO) monitored before and after infusion of ET-1, and 1 min, 5 min, 10 min after cromakalim injection, and pulmonary vascular resistance (PVR) were calculated. It was found that the mPAP was significantly increased, from 2.36 +/- 0.24 kPa to 3.32 +/- 0.49 kPa(P < 0.01), and PVR also increased, by infusion of ET-1. After cromakalim injection, mPAP were decreased to 2.50 +/- 0.62 kPa in 1 min, 1.14 +/- 0.18 kPa in 5 min and 2.33 +/- 0.52 kPa in 10 min, PVR decreased significantly. It is suggested that there is interaction between ET-1 and potassium Channel, and Cromakalim decreases mPAP in part by inhibiting the response of pulmonary artery to ET-1.

Animals↗
PubMed1998

[Changes of the gene expression of vascular endothelial growth factor in the lung of rats with chronic hypoxic pulmonary hypertension].

To observe the effect of chronic hypoxia on the gene expression of vascular endothelial growth factor (VEGF) in rat's lung, and the role of VEGF in the pathogenesis of hypoxic pulmonary hypertension, thirteen male Wistar rats were exposed to isobaric hypoxia for 3 weeks. The pulmonary artery pressure was measured by right cardiac catheterization. The serum level of VEGF was measured by Elisa. The VEGF cRNA was labeled with digoxigenin-UTP by in vitro transcription. The expression of VEGF mRNA in the lung was examined by hybridization in situ. The pulmonary artery pressure was significantly increased after hypoxic exposure. The serum level of VEGF in rats treated with hypoxia (420.3 +/- 73.1 pg/ml) was significantly increased in comparison with that of normal rats (322.2 +/- 58.1 pg/ml). The VEGF hybridization signals on the wall of pulmonary arteriole were significantly increased in rats with pulmonary hypertension. Chronic hypoxia can markedly increase expression of VEGF mRNA in the pulmonary arteriole and hence stimulate VEGF synthesis and secretion. The increase of VEGF may play a role in the developing process of hypoxic pulmonary hypertension.

Animals↗
PubMed1998

[Changes of level and distribution of vascular endothelial growth factor in the lungs of rats with hypoxic pulmonary hypertension].

This study was designed to elucidate whether the level and distribution of vascular endothelial growth factor (VEGF) are changed in the lungs of rats with hypoxic pulmonary hypertension. 13 male Wistar rats were exposed to isobaric hypoxia for 3 weeks. The pulmonary artery pressure was measured by right cardiac catheterization. The level of VEGF in pulmonary homogenate was measured by Elisa method. The distribution of VEGF in the rat lung was examined by immunohistochemistry. The results showed that the pulmonary artery pressure was significantly increased after hypoxic exposure. The level of VEGF in pulmonary homogenate of rats treated with hypoxia (466.9 +/- 75.5 pg/g) were significantly increased as compared with taht of normal rats (376.2 +/- 47.1 pg/g). The contents of VEGF in the wall of pulmonary arteriole were significantly increased in rats with pulmonary hypertension. So we suggest that chronic hypoxia can strongly stimulate VEGF secretion, and VEGF may mediate the process of hypoxic pulmonary vascular remodeling and pulmonary hypertension.

Animals↗
PubMed1998

[Isolation and identification of smooth muscle cells from pulmonary artery in rats].

To explore the method of isolating acutely the smooth muscle cells from pulmonary artery in rats, small pulmonary arteries (700-200 microns, ID) were dissected free of connective tissue and were allowed to digest in a N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid(HEPES)-buffered physiological saline solution (HPSS) containing collagenase, papain and bovine serum albumin. The tissue was then triturated to disperse smooth muscle cells. The isolated cells in suspension were identified and photographed with film on electron microscope (EM). We succeeded in isolating the single smooth muscle cell, which appeared compressed typically. 90% cells in suspension were identified smooth muscle cells on EM. We conclude that the method for isolation of pulmonary arterial smooth muscle cells is simple, stable and effective and is recommanded for use.

Animals↗
PubMed1998

[The change of plasma level of endothelin in patients with acute attack of asthma].

In order to assess the interaction of endothelin (ET) and acute attack of asthma, the plasma levels of ET in 23 patients with acute attack of asthma and 12 normal controls were measured by radioimmunoassay. The partial pressure of oxygen in arterial blood (PaO2) and peak flow (PEF) were measured synchronously. The results showed that the plasma ET level in asthmatic patients (89.2 +/- 8.4 ng/L) was much higher than that in normal controls (52.2 +/- 6.5 ng/L), P < 0.001. There was a significant negative correlation between the plasma level of ET and the PaO2 (r = -0.7893, P < 0.01) or PEF (r = -0.7124, P < 0.01). The results suggest that ET may play a role in acute attack of asthma, and its level may stand for the degree of the disease.

Adolescent↗
PubMed1998

[The inhibition effect of acute hypoxia on K+Ca-ATP channels of pulmonary artery smooth muscle cells of rats].

OBJECTIVE: To explore the possible mechanism underlying hypoxic pulmonary vasoconstriction, we evaluated the effect of acute hypoxia on potassium channels in pulmonary artery smooth muscle cells. METHOD: The single smooth muscle cell was freshly isolated from pulmonary artery (phi 700-200 microns) of Wistar rats with acute enzymatic digestion method. In symmetrical high K+ solution, we separated one outward K+ current from the patch of smooth muscle cells with inside-out configuration using patch-clamp technique. According to the electrophysiological response to the patch channel, this current was identified as the Ca2+, ATP activated potassium channel (K+Ca-ATP). The hypoxic solution was obtained by aeration with 5% CO2-balance N2 mixture. RESULT: The currents of K+Ca-ATP in the patch of smooth muscle cells was much inhibited while the oxygen tension of solution was reduced from normoxic (PO2 > or = 13.33 kPa) to hypoxic (PO2 < or = 2.67 kPa) levels (P < 0.01). Cromakalim (10 nmol/L), an opener of potassium channel, could activate the currents of K+Ca-ATP decreased by acute hypoxia (P < 0.01). CONCLUSION: Acute hypoxia has an inhibition role on K+Ca-ATP currents in pulmonary artery smooth muscle cells, causes the membrane potentional depolarization, leads to pulmonary vasoconstriction, increases pulmonary vascular resistance and artery pressure. The decrease of K+Ca-ATP contributes to development of hypoxic pulmonary vasoconstriction. Cromakalim is one of effective antagonists for hypoxic pulmonary vasoconstriction.

Animals↗