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Biomedical subjects

L Chen

Publications and source records attributed to L Chen.

At least 1,135 records · Page 63Linked to original sources
PubMed1995

[Detecting human papillomavirus DNA of condylomata and pseudo-condylomata by in situ hybridization and polymerase chain reaction in paraffin-embedded specimens].

One hundred and thirty seven cases of paraffin-embedded tissue specimens biopsied each from condylomata and pseudo-condylomata of vulva and vagina were examined. Type 6b 11 human papillomavirus (HPV) DNA was detected in condylomata by in situ hybridization using digoxigeninlabelled probes and polymerase chain reaction (PCR). The positive rate was 82.5%, 83.9% respectively. It was negative in the 137 cases of pseudo-condylomata by in situ hybridization, but positive in 3 cases by PCR. For a correct diagnosis, the necessity of combining the data of clinical finding, microscopic examination and in situ hybridization or PCR is emphasized. Our results showed that pseudo-condylomata represent dysplastic appearances of vulval and vaginal mucosa, which become more marked during pregnancy and fungal or trichomonal infections, and could rather easily be misdiagnosed as condylomata.

Condylomata Acuminata↗
PubMed1995

[The diagnostic significance of rheumatoid factors in patients with early rheumatoid arthritis].

The early phase of rheumatoid arthritis has attracted increasing attention due to the concern with prognosis of the disease. In this study IgM rheumatoid factor (RF) and IgA immunoglobulin were measured twice a year in 96 patients. Their joint damage was assessed yearly with radiographic examination. Radiological abnormalities detected included osteoporosis, bone erosion and joint space narrowing. The patients were followed up for three years. The changes of joint damage might be of three types: worsening, nonchange and improvement. A significant correlation between the levels of IgM RF and IgA immunoglobulin and disease activity was observed. A high level of IgM RF was prognostic for a more severe disease. One patient with 7 g/L IgA immunoglobulin exhibited considerable joint damage progression in a year, while 2 cases with minor IgA immunoglobulin showed remarkable improvement. These two parameters can be considered the important laboratory indicators for the early disease. The results may also be applied to guide second line antirheumatic drug therapy.

Adult↗
PubMed1995

[Plasma endothelin 1 and its clinical evaluation in asthma].

Plasma endothelin 1 (ET1) was determined by radioimmunoassay in 28 cases of acute attack of asthma (attack group), 23 subjects of non-symptomatic asthma (remission group) and 20 normal volunteers (control group). The results showed that the plasma ET1 in attack group (13.4 +/- 5.2 fmol/ml) was much higher than that in both remission group (8.4 +/- 3.9 fmol/ml, P < 0.01) and control group (6.6 +/- 2.6 fmol/ml, P < 0.01). However, there was no significant difference between remission group and control group. The plasma ET1 level revealed notably negative correlation to PaO2 and FEV1% (r = -0.8257, r = -0.8157, P < 0.01). The results suggested that ET1 probably involved in pathophysiologic process of acute attack of bronchial asthma.

Adult↗
PubMed1995

Biomedical material for sutureless esophagogastrostomy. Analysis of 31 cases.

The results of 31 cases of sutureless esophagogastrostomy by intraluminal elastic circular ligation (IECL) with the biodegradable supporting tube were reported. The fate of the supporting tube could be tracked satisfactorily by X-ray. The tube-dislodge time was 15.03 +/- 2.23 days and unaffected by the size of supporting tube or the site of anastomosis. The supporting tube could be safely absorbed or partially discharged through the alimentary tract. IECL, with the merits of saving time, anastomosing tightly and leaving no suture materials in the anastomotic site, can be expected to further reduce the incidence of anastomotic leakage and provide references for other gastrointestinal anastomosis.

Adult↗
PubMed1995

[Effect of puerarin on cerebral blood flow in dogs].

The hemodynamics of left intra- and extracranial arteries was determined by a pulsatile Doppler flowmeter and a transcranial Doppler system simultaneously in anesthetized dogs. Low doses of puerarin (50mg/kg, iv) did not alter the cerebral perfusion pressure, but reduced the flow velocities of both middle cerebral artery and anterior cerebral artery. The globle cerebral blood flow was enhanced due to dilatation of the intracranial arteries.

Adrenergic beta-Antagonists↗
PubMed1995

[A new technique of esophagogastrostomy above the aortic arch--covering and suspending of the anastomotic area with mediastinal pleura flap].

The postoperative anastomotic leakage is the most severe complication and the principal cause of death after resection of esophageal carcinoma. Especially, anastomosis above the aortic arch is accompanied by high incidence of anastomotic leakage usually with fatal prognosis. The authors improved the conventional method of anastomosis by using a mediastinal pleura flap to cover and suspend the anastomotic area with excellent result. From January of 1990 to April of 1995, 210 patients with esophageal carcinoma were so treated. No anastomotic leakage or stricture developed. Only one patient died of extensive myocardial infarction with an overall mortality of 0.47%. The major merit of this procedure was that the mediastinal pleura flap could cover the area of anastomosis and sustain the dragging force acting on this area, providing a better condition for the anastomosis to heal and thus reducing the possibility of anastomotic leakage.

Adult↗
PubMed1995

[The variable number of tandem repeats in the renin gene of rats and possible significance in hypertension].

The variable number of tandem repeats (VNTR) in the first intron of renin gene for the spontaneously hypertensive rat (SHR), its controls Wistar-Kyoto (WKY), renal hypertensive rat, and Sprague-Dawley rat (SD) were compared by polymerase chain reaction (PCR) method. An analysis of VNTR from WKY, Wistar and SD showed that there are two different renin gene alleles and three genetypes 2.0kb/2.0kb, 2.0kb/1.8kb, 1.8kb/1.8kb. The genetype from renal hypertensive rats is same as those seen in the normal controls. However, compared with the WKY, Wistar and SD genes, a "deletion" of approximately 1.0kb was found in the first intron of the SHR renin gene. Our results strongly suggest that the cause and mechanism of elevated blood pressure is complex, and the molecular basis of the genetic-prone hypertension is existed.

Animals↗
PubMed1995

Ultrastructure of parietal cells before and after extended parietal cell vagotomy in patients with duodenal ulcer and their complications.

Since 1979 we have treated 149 patients with duodenal ulcer by extended parietal cell vagotomy (EPCV). Electron microscopy of parietal cells from gastric body mucosa and gastric acid secretory test were carried out in 22 randomly selected patients before and after EPCV. It was shown that before EPCV the ultrastructure of parietal cells presented the feature of vigorous section identical to the hyperfunctional secretion of gastric acid. The ultrastructure of parietal cells presented the feature of acute depression of secretory function, which was identical to a significant reduction of secretory function of gastric acid 0.5-6 months after EPCV. Two to 10 years after operation, however, especially over 10 years after EPCV, the ultrastructural changes of parietal cells gradually returned to normal, but gastric acid secretion remained at a low level, without preoperative secretory capacities. The results of this study provide a histological basis for the application of extended parietal cell vagotomy in the treatment of duodenal ulcer and its complications.

Adult↗
PubMed1995

[Experience in management of capsular contraction through areolar incision after implantation of prosthesis for augmentation mammaplasty].

Since 1990, 19 cases of capsular contraction of Baker's III, IV have been treated with partial excision of the capsule and replacement of implants through areolar incision. The result was satisfactory. After six months to eighteen months follow-up observation, no capsular contraction was again found. All patients were graded Baker's I. Prevention of capsular contraction was also discussed.

Adult↗
PubMed1995

[The morphologic changes of outer hair cells induced by hypotonic, hypertonic medium and electromotility].

For further understanding of biological features of cochlear outer hair cells, outer hair cells were isolated from guinea pig cochlea with micromechanical method and observed when the microosmotic concentration of their culture medium were changed. Outer hair cells shortened 3.14 +/- 0.76% (P < 0.01) within one minute after the osmotic concentration of the medium decreased to 280 mmol/L, accompanied with increase of cell diameter. Elongation of 3.34 +/- 1.09% (P < 0.05) of outer hair cells were observed after osmotic concentration of the medium was increased to 320 Os mmol/L, accompanied with decrease of cell diameter. Oscillatory elongation and shortening of outer hair cells and oscillatory displacements of intracellular organelles could be observed when square wave electrical potentials were applied across isolated outer hair cells. Hypertonic high potassium medium (K+ 100 mmol/L, 320 Osmmol/L) decreased the oscillatory movement of the cells by about 43.14% (negative potential) and 46.17% (positive potential) (P < 0.05). The shape of outer hair cells restored when the medium was isotonic. The mechanism and biological bases of outer hair cell movement were discussed.

Animals↗
PubMed1995

[Excitation of hypothalamic nucleus arcuatus neuron induced decrease of plasma sialic acid level in rats].

The effect of sodium glutamate (Glu) on plasma sialic acid (SA) level was studied by means of microinjection into the nucleus arcuatus (ARC) and ultraviolet spectrophotometry. The results indicate: (1) The plasma SA level was significantly decreased after microinjection of Glu into the ARC (P < 0.01). With increasing Glu concentration, the onset of the decrease occurred earlier. (2) When Glu was microinjected into ARC after intraventricular injection of apomorphine, the plasma SA level was significantly decreased (P < 0.01) and the time required to cause the decrease was shortened. (3) When Glu was microinjected into ARC after intraventricular injection of spiperone, no change was found in the plasma SA level (P > 0.05). The above results suggest that the mechanism underlying the decrease of plasma SA level is probably related to modulated dopamine (DA) release of hypothalamic dopaminergic neurons by DA-D2 receptor.

Animals↗
PubMed1995

Oxidative changes in the liver, brain and lens of lipopolysaccharide-treated rats.

Oxidative damage in various tissues of LPS-treated rats was studied using the following parameters: changes in reduced (GSH) and oxidized glutathione (GSSG) levels in liver, brain and lens; the activity of glutathione peroxidase (GSH-PX) in both liver and brain; the content of cytochrome P450 reductase in liver. Bacterial LPS was injected i.p. (at a dose of 4 mg/kg BW) 6 h before the animals were killed. One group of rats received N omega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase (NOS) (given for 4 days in the drinking water at a concentration of 50 mM); another group received both L-NAME and LPS. In brain and lens no changes in GSH were observed after either LPS, L-NAME or both. In contrast, GSSG and the GSSG/GSH ratio was significantly higher after LPS. This effect was abolished in the brain by L-NAME treatment. The level of the activity of the antioxidative enzyme GSH-PX in brain was significantly higher after L-NAME in LPS-treated animals. Hepatic GSH-PX activity was enhanced after either LPS, L-NAME or treatment with both substances. Additionally, LPS diminished the level of cytochrome P450 reductase with this effect being largely prevented by L-NAME. The results suggest that GSH, as an endogenous antioxidant, may play a major role in combating toxicity of LPS.

Animals↗
PubMed1994

Relationship between cytochrome P450 2E1 and acetone catabolism in rats as studied with diallyl sulfide as an inhibitor.

Previous studies have demonstrated that cytochrome P450 2E1 (P450 2E1) catalyzes the oxidation of acetone in vitro. The present study was designed to determine the importance of P450 2E1 in the catabolism of acetone in rats using diallyl sulfide (DAS) as an inhibitor of this enzyme. After a single intragastric dose of DAS, blood samples were collected from rats at different time points, and blood acetone concentrations were measured by gas chromatography. In a low DAS dose (50 mg/kg body weight) group, the maximum acetone level of 6-fold higher than the normal level was reached at 6 hr; the acetone level returned to normal at 48 hr. In a high dose (200 mg/kg) group, the maximum acetone level of 9-fold higher than the normal level was reached at 12 hr; the acetone level returned to normal at 60 hr. The turnover time and fractional turnover rate of elevated acetone were 15.8 +/- 0.5 hr and 0.054 +/- 0.001 hr-1, respectively, for the low dose, and 19.2 +/- 0.6 hr and 0.046 +/- 0.005 hr-1, respectively, for the high dose. In a chronic experiment, DAS (50 and 200 mg/kg, i.g.) was given to rats daily for 29 days, and elevated blood acetone levels were observed during the entire experimental period: 2.0 to 2.8 micrograms/mL for the low dose and 3.4 to 3.9 micrograms/mL for the high dose at 24 hr after the 1st, 7th, 14th and 28th doses versus 0.8 to 0.9 micrograms/mL for the control. The increase of blood acetone level was closely related to the decreases of N-nitrosodimethylamine (NDMA) demethylase activity and P450 2E1 content in liver microsomes. Consistent with the lack of cumulative effect from the multiple doses of DAS on acetone level, rather stable levels of the DAS metabolites, diallyl sulfoxide (45.0 micrograms/mL, range: 33.8 to 58.6 micrograms/mL) and diallyl sulfone (11.7 micrograms/mL, range: 6.9 to 15.6 micrograms/mL), were observed at 24 hr after the 1st, 7th, 21st and 28th doses with DAS (200 mg/kg) in the chronic experiment. It is likely that the inactivation and inhibition of P450 2E1 by DAS and its metabolites block the oxidation of acetone and cause its elevation in blood. The results strongly suggest an important role of P450 2E1 in acetone catabolism under physiological conditions.

Acetone↗
PubMed1994

A blue non-heme iron protein from Desulfovibrio gigas.

A novel iron-containing blue protein, named neelaredoxin, was isolated from the sulfate-reducing bacterium Desulfovibrio gigas. It is a monomeric protein with a molecular mass of 15 kDa containing two iron atoms/molecule. The N-terminal sequence of neelaredoxin has similarity to the second domain of desulfoferrodoxin, a protein purified from Desulfovibrio vulgaris Hildenborough. This finding supports the hypothesis that the gene coding for desulfoferrodoxin (rbo) might have arisen from a gene fusion [Brumlik, M. J., Leroy, G., Bruschi, M. & Voordouw, G. (1990) J. Bacteriol. 172, 7289-7292]. The visible spectrum exhibits a single band at 666 nm, responsible for the blue color of the protein, which is completely bleached upon reduction with sodium ascorbate. In the oxidized state the EPR spectrum is complex, exhibiting well-resolved features at g = 7.6, 7.0, 5.9, and 5.8 which are assigned to two high-spin (S = 5/2) mononuclear-iron (III) centers with different rhombic distortions (E/D approximately 0.05 and approximately 0.08). The two iron atoms contribute identically to the visible spectrum as judged from visible redox titrations, from which a reduction potential of +190 mV was determined for both iron sites at pH 7.5. At high pH the visible and the EPR spectra become pH-dependent with a pKa above 9: the 666-nm band shifts to 590 nm and the EPR signals are converted into a signal with gmax approximately 4.7. Neelaredoxin is readily reduced both by H2/hydrogenase/cytochrome c3 and by NADH/NADH-rubredoxin oxidoreductase.

Amino Acid Sequence↗
PubMed1994

Crystal structure of a four-stranded intercalated DNA: d(C4).

The crystal structure of d(C4) solved at 2.3-A resolution reveals a four-stranded molecule composed of two interdigitated or intercalated duplexes. The duplexes are held together by hemiprotonated cytosine-cytosine base pairs and are parallel stranded, but the two duplexes point in opposite directions. The molecule has a slow right-handed twist of 12.4 degrees between covalently linked cytosine base pairs, and the base stacking distance is 3.1 A. This is in general agreement with the NMR studies. A biological role for DNA in this conformation is suggested.

Computer Graphics↗
PubMed1994

Proteins of the inter-alpha-trypsin inhibitor family stabilize the cumulus extracellular matrix through their direct binding with hyaluronic acid.

We have previously identified a glycoprotein of the inter-alpha-trypsin inhibitor family of proteins as a serum factor responsible for the stabilization of the expanding cumulus mass. In this study, the mechanism of interaction of this cumulus extracellular matrix stabilizing factor (cESF) with hyaluronic acid (HA) has been explored. It was found that the pH optimum for binding of cESF and HA is 7 and that binding is sensitive to ionic strength. The dissociation constant is about 1.9 x 10(-8) M in 10 mM sodium phosphate buffer (pH 7.2). Circular dichroism studies show that cESF contains about 24% alpha-helical and 42% beta-sheet structure. Gross conformational changes in cESF, however, are not detected in the presence of HA. We also found that modification of lysine residues of cESF with citraconic anhydride greatly reduced its binding with HA and completely abolished its cumulus stabilizing activity, and deblocking lysine residues restored its capacity to bind with HA and its cumulus matrix stabilizing activity. This evidence supports the hypotheses that cESF stabilizes the expanding cumulus extracellular matrix by directly binding with HA and that cESF may serve as a structural protein to organize the formation of the cumulus extracellular matrix. Our evidence also supports the view that binding of cESF and HA is through a stereo-specific charge interaction. Putative binding sites of cESF that interact with HA are postulated.

Alpha-Globulins↗
PubMed1994

Interdigitation-fusion: a new method for producing lipid vesicles of high internal volume.

Previously we demonstrated that fused phospholipid sheets can be formed from small unilamellar vesicles (SUVs) comprised of saturated symmetric chain lipids by exposing them to concentrations of ethanol sufficient to cause bilayer interdigitation (Boni et al. (1993) Biochim. Biophys. Acta 1146, 247-257). Here we report that these sheets spontaneously form large, predominately unilamellar vesicles, when exposed to temperatures above their main phase transition temperature (Tm). These vesicles, termed interdigitation-fusion vesicles (IFVs), have mean diameters between 1 and 6 microns, and, once produced, are stable both above and below the Tm of the lipid. The average captured volume of IFVs is dependent upon lipid chain length, the concentration of ethanol used to induce interdigitation-fusion, and size of the precursor liposomes. IFVs comprised of DPPC and DSPC had averaged captured volumes of 20-25 microliters/mumol lipid. IFVs produced from SUVs containing only DPPG or DPPC/DPPG mixtures had captured volumes equivalent to those made from pure DPPC SUVs indicating that charge can be introduced without consequence to the IFV process. Inclusion of cholesterol in precursor vesicles reduced IFV captured volume in a concentration dependent fashion by interfering with interdigitation. Cholesterol could be incorporated, however, into IFVs through admixture with the already formed phospholipid sheets producing far less comprise to captured volume. IFVs are useful as model systems or drug carriers, since their large internal volume allows for efficient encapsulation particularly with regard to compounds such as iodinated radiocontrast agents which otherwise interfere with vesicularization.

1,2-Dipalmitoylphosphatidylcholine↗