Search PubMed⌕ Search

Biomedical subjects

M Chen

Publications and source records attributed to M Chen.

At least 631 records · Page 35Linked to original sources
PubMed1995

[Comparative study of HCG receptors in rat ovary and testis].

It has been documented that there are specific human chorionic gonadotropin (HCG) receptors in cell membrane of rat ovary and testicle. In order to make a further study on the characteristics of the HCG receptors on rat ovary and testicle, we focused on comparing those two kinds of receptors. Furthermore, we contrasted the testicular cell membrane with its homogenates. Rat ovarian and testicles were homogenized and soniced under ice cold conditions. The homogenates were centrifuged at 12,100 x g for 20 min following filtration. After sucrose density gradient ultracentrifugation (78,000 x g, 2.5h) for the pellets, the interface layers between 37% and 41% were collected. The pellets were subsequently suspended in cold 1mmol/L NaHCO3 solution and recentrifuged at 27,000 x g for 25 min. The results show that the cell membrane of both the rat ovary and testicle can bind to HCG specifically. A small amount of HCG has more evident inhibitory effect on the binding in testis than ovary. Scatchard plot analysis for the binding assay yielded a bound capacity of testicle cell membrane of 4.5 x 10(-5) mol/micrograms protein, Kd of 1.6 x 10(-7) mol/L, whereas it was 0.51 x 10(-9) mol/micrograms protein, a Kd of 1.69 x 10(-6) mol/L in ovarian cell membrane. In comparison with homogenates and cell membrane, the HCG binding activity of later is more sensitive.

Animals↗
PubMed1995

Efficacy of human leucocyte alpha-interferon treatment for chronic hepatitis C virus infection.

A total of 42 Swedish patients with biopsy-proven chronic hepatitis C virus (HCV) infection were treated with a natural human leucocyte alpha-interferon (HuIFN-alpha-Le), Alfanative (BioNative AB, Umeå, Sweden) in an open uncontrolled study. Two patients were withdrawn from treatment within 2 weeks due to non-compliance and were omitted from further analysis, and 40 patients (17 females), mean age 39 years (range 24-71) completed the study. All patients were HCV RNA-positive in serum prior to treatment, with raised alanine aminotransferase (ALT) levels > 1.5 times the upper normal limit known for more than 6 months. Interferon was given at a dose of 3 MU t.i.w. for an intended 24 weeks and follow-up was a further 24 weeks after treatment. Biochemical non-responders were withdrawn from treatment within 12-16 weeks but continued follow-up. Overall 21/40 (52.5%) patients had a complete biochemical response with normal ALT levels at the end of treatment. Sustained response during follow-up was seen in 8 (20%) whereas 13 (32.5%) had a non-sustained response. At the end of treatment 23 (58%) patients had undetectable serum HCV RNA and 9 (23%) at follow-up. Patients with sustained, non-sustained and non-response had a mean pretreatment HCV RNA level of 3.2 x 10(5), 2.5 x 10(6) and 3.2 x 10(6) genomes/ml, respectively, differences that did not reach statistical significance. Of the patients 3, 9, 10 and 14 had genotype 1b, 3a, 1a, and 2b, respectively, and 4 had mixed genotypes. Of the 23 patients with genotype 2b or 3a, 7 had a sustained response vs. none of the 13 patients with genotype 1a or 1b (p = 0.03). No patients with cirrhosis had a sustained response whereas 4/18 with chronic persistent and 4/18 with chronic active hepatitis had such a response. It is concluded that some 50% of patients treated with HuIFN-alpha-Le responded with normalisation of ALT levels but that only 20% had a durable response 24 weeks post-treatment, and that patients with genotypes 3a or 2b seem to respond better than patients with other genotypes.

Adult↗
PubMed1995

Efficacy of human leucocyte alpha-interferon treatment for chronic hepatitis C virus infection.

A total of 42 Swedish patients with biopsy-proven chronic hepatitis C virus (HCV) infection were treated with a natural human leucocyte alpha-interferon (HuIFN-alpha-Le), Alfanative (BioNative AB, Umeå, Sweden) in an open uncontrolled study. Two patients were withdrawn from treatment within 2 weeks due to non-compliance and were omitted from further analysis, and 40 patients (17 females), mean age 39 years (range 24-71) completed the study. All patients were HCV RNA-positive in serum prior to treatment, with raised alanine aminotransferase (ALT) levels > 1.5 times the upper normal limit known for more than 6 months. Interferon was given at a dose of 3 MU t.i.w. for an intended 24 weeks and follow-up was a further 24 weeks after treatment. Biochemical non-responders were withdrawn from treatment within 12-16 weeks but continued follow-up. Overall 21/40 (52.5%) patients had a complete biochemical response with normal ALT levels at the end of treatment. Sustained response during follow-up was seen in 8 (20%) whereas 13 (32.5%) had a non-sustained response. At the end of treatment 23 (58%) patients had undetectable serum HCV RNA and 9 (23%) at follow-up. Patients with sustained, non-sustained and non-response had a mean pretreatment HCV RNA level of 3.2 x 10(5), 2.5 x 10(6) and 3.2 x 10(6) genomes/ml, respectively, differences that did not reach statistical significance. Of the patients 3, 9, 10 and 14 had genotype 1b, 3a, 1a, and 2b, respectively, and 4 had mixed genotypes. Of the 23 patients with genotype 2b or 3a, 7 had a sustained response vs. none of the 13 patients with genotype 1a or 1b (p = 0.03). No patients with cirrhosis had a sustained response whereas 4/18 with chronic persistent and 4/18 with chronic active hepatitis had such a response.

Adult↗
PubMed1995

[Molecular diagnosis of Huntington's disease: an analysis of two large families].

At present molecular techniques comprise a main resource in the early accurate diagnosis for Huntington's disease. We describe the molecular diagnosis for 8 HD patients and 39 risky family members in two large HD pedigrees by using G8 RFLP linkage analysis as well as direct detection of the expanded (CAG) repeat in IT15 gene with the nested PCR denaturing polyacrylamide gel electrophoretic autoradiography and direct DNA sequencing. The results showed that the normal IT15 alleles contained 13 to 26 CAG repeat but major in 16, while all the HD alleles had over 40 copies of (CAG)n. There was no overlap between the normal and affected alleles. The presymptomatic diagnosis of 39 family members at risk for HD disclosed that 11 subjects carried the affected alleles. All these results indicated that the unstable mutations in IT15 gene were responsible for HD in the Chinese. They also provide valuable data for HD molecular diagnosis, genetic counselling and genetic health.

Adolescent↗
PubMed1995

[The effect of moxibustion on gastric mucosa in rats and its relation to copper, zinc contents in serum].

18 rats were randomly deivided into 3 groups: control grup, the group merely with experimental gastric ulcer and the group with experimental gastric ulcer after 3-week moxibustion. The results showed: (1) moxibustion could significantly reduce the ulcer area of the rats (P < 0.05); (2) compared with control group, the experimental gastric ulcer model rats had an increase in copper content and Cu/Zu ratio, the differences were statistically significant (P < 0.05, P < 0.01); (3) in contrast to the rats merely with experimental gastric ulcer, moxibustion-pretreated rats had a significant increase in Zinc content in serum (P < 0.01), but its copper content and Cu/Zn ratio in serum were significantly decreased (P < 0.05, P < 0.01). The results confirmed that moxibustion pretreatment at "Shen-Jue" could protect the gastric mucosa from strass-induced ulcer, having protective effect on gastric mucosa. The results also suggested that there was a disbalance in trace elements metabolism, but moxibustion could improve it. This was most likely to be one of the mechanisms of moxibustion protection on gastric mucosa.

Animals↗
PubMed1995

[8%-9% and 12%-13% hypoxic gas induced free radicals generation in rat's left and right myocardium].

Alpha-phenyl-tert-butylnitrone (PBN) was administered intravenously to capture free radicals of rat's myocardium. Rats were exposed to hypoxic gas (8%-9% O2 in N2) for 15 min. The ESR (electron spin resonance) signal intensity of PBN-spin adduct in the left myocardium increased significantly as compared with the normoxia group (n = 5, P < 0.05), but in the right myocardium there was no significant changes between hypoxia and normoxia. Rats exposed to hypoxic gas (12%-13% O2 in N2) were divided into four groups: I (hypoxia for 15 min), II (hypoxia for 60 min), III (hypoxia for 30 min/normoxia for 15 min/hypoxia for 30 min) and IV (injected MPEG- SOD intravenously before hypoxia for 60 min). The ESR signal intensity of PBN-spin adduct of left and right myocardium in group II increased significantly as compared with normoxia group (n = 5, P < 0.01), but the ESR signal intensity of group I didn't show obvious change as compared with normoxia group (n = 5, P > 0.05). In the right myocardium of group III the ESR signal intensity of PBN-spin adduct decreased significantly as compared with group II (n = 5, P < 0.05) and in the left myocardium did not decrease evidently. In the left myocardium of group IV the ESR signal intensity of PBN-spin adduct decreased evidently as compared with group II (n = 5, P < 0.05) and that in the right myocardium did not decrease evidently. When the rats were exposed to 8%-9% hypoxic gas for 15 min and 12%-13% hypoxic gas for 60 min, the SOD (superoxide dismutase, EC 1.11.1.9) activity of myocardium decreased and the content of MDA (malondialdehyde) increased significantly (n = 8, P < 0.05 or P < 0.01). The above results suggested that one way of myocardium free radical gereration may be relevant to decrease of SOD activity. The generation of free radicals pertained chiefly to superoxide free radical in the left myocardium and the membrane structure of myocardium cells might have been damaged largely during hypoxia.

Animals↗
PubMed1995

[Acute hypoxia induce free radicals generation in rat's cortex and hippocampus].

Anesthetized rats were ventilated artificially to 10.5%-11.0% O2 in N2 (equivalent to altitude about 5 000 m). PBN (alpha-phenyl-ter-butylnitrone) was injected intravenously 5 min before hypoxia. The experiment results showed that the ESR (electron spin resonance) signal intensity of PBN-spin adduct in cortex and hippocampus both increased significantly during hypoxia (15 min) as compared with normoxia group (n = 5, P < 0.01). In the third group of rats injected with MPEG-SOD (monomethoxy-polyethylene glycol-superoxide dismutase) intravenously 20 min before hypoxia, the ESR signal intensity of PBN-spin adduct in cortex and hippocampus did not decrease significantly under hypoxia for 15 min (compared with hypoxia group, n = 5, P > 0.05). This may be due to the fact that MPEG-SOD could not pass the blood-brain barrier owing to its large molecular weight. The enzyme activity of SOD (superoxide dismutase. EC 1.15.1.1), GSH-Px (Glutathione peroxidase, EC 1.11.1.9) and content of MDA (malondialdehyde) was also determined. The results showed that the hypoxia had no effect on the SOD, GSH-Px activity and MDA content (n = 7 or n = 8, P > 0.05). The above results suggested that ventilation to 10.5%-11.0% O2 in N2 15 min induced free radical generation in rat's cortex and hippocampus, but this generation was not due to decrease of SOD, GSH-Px activity in cortex and hippocampus.

Animals↗
PubMed1995

[Application of serology and 14C-urea breath test to monitoring of the effect of anti-Helicobacter pylori chemotheraphy].

In order to evaluate the value of serology and 14C-urea breath test in monitoring the effect of anti-Helicobacter pylori chemotherapy, at the first stage of this study, endoscopy, 14C-urea breath test and serology (H. pylori IgG antibody measured by ELISA) were performed in 42 of patients before the onset of anti-H pylori chemotherapy and at 1, 3, 6 and 12 months after termination of the treatment. On analyzing the change of the results of breath test and serology during the one year follow-up period in these patients, "above the cutoff value" in breath test and "reduction of A value less than 15% when comparing with pretreatment" in serology were made as the H. pylori positive criteria for monitoring therapeutic effectiveness on H. pylori. At the second stage of this study, total of another 63 of patients were studied to test the accuracy of the monitoring criteria. The results showed that the sensitivity of breath test was all 100.0% and specificity 95.5% and 100.0% respectively at 6 and 12 month after termination of treatment, the sensitivity of serology was all 100.0% and specificity was 50.0% and 83.3% respectively. A scheme for monitoring the effect of anti-H. pylori chemotherapy by combination of 14C-urea breath test and serology is proposed based on this study.

Antibodies, Bacterial↗
PubMed1995

[Cervico-scapulo-dorsal reverse axial flap with pedicle including the transverse cervical artery].

The anatomy of the transverse cervical artery and its branches were studied on 52 arteries in 26 cadavers. It was confirmed that blood in the transverse cervical artery might flow reversely into the suprascapular artery and the posterior intercostal perforators through anastomic branches. An axial skin flap in the cervico-scapulo-dorsal area could be adequately supplied by this artery. We have used this flap in reconstruction for burn scar contractures of the neck in 20 cases, and in one patient bilateral flaps were used. There was partial necrosis of the tip in 4 flaps, while all others survived completely.

Adolescent↗
PubMed1995

[Clinical study of the venous flaps].

Seven venous flaps were used clinically. Of them six flaps survived completely, one saphenous venous flap had partial necrosis of the derma. The size of the largest survived flap was 5 cm x 15 cm. Three principles regarding the flap application were emphasized: 1) The tissue surrounding the recipient site should be normal. High venous pressure and oxygen tension in the recipient veins are needed. 2) Rich venous network and an axial vein are required in the recipient site. 3) Reliable fixation of the flap is necessary to avoid any damage to new blood vessels.

Adolescent↗
PubMed1995

[Malignant melanoma of nasal cavity: report of 24 cases].

The malignant melanoma of nasal cavity is one of the refractory diseases. The malignant degree and the recurrent rate of this disease are high. And it is very easy to make misdiagnosis. This article reviewed the clinical and pathological data of malignant melanoma of nasal cavity for 20 years from 1971 to 1991. All the patients were followed up. We found that there were altogether 24 cases of this disease which covered 0.02% of all the inpatients during that period of time. The pathological characteristics of this tumor showed that there was a typical fore-melanin body in different tumor cells. If we pay attention to the minor and grained melanin, misdiagnosis can be avoided. Surgery is the first choice for this disease. And the post-operative radiotherapy, laser therapy gives a better result.

Adult↗
PubMed1995

[Hypoxia induced increase of MDA and echinocytes from erythrocytes in rabbit's blood with special reference to inhibition of the increase by MPEG-SOD].

When rabbits acutely exposed to hypobaric hypoxia (at imitative altitude 5,000 m, PaO2 = 6.7 kPa), the percentage of the activity of superoxide dismutase (SOD in erythrocyte; EC 1.15.1.1) decreased respectively to 86%, 76%, 81%, 84%, 55%, 81%, 84% and 95% for a period of 0.25, 0.5, 1, 2, 3, 4, 5 and 24 h hypoxia while MDA (malondialdehyde) in erythrocyte and plasma increased significantly during hypoxia periods of 1, 2, 3, 5 and 24 h (n = 5, P < 0.05, P < 0.01 vs. normoxia group). The increase of MDA in plasma could be prevented by vitamin E (V. E, i.p, 1 mg daily for 3 consecative days before hypoxia), but that in erythrocyte did not show significant change probably because the injected V.E. without vehicle cannot penetrate through the erythrocyte membrane effectively. The echinocytes from erythrocytes increased significantly after hypoxia for 24 h (n = 5, P < 0.05 vs. normoxia group). However, by injecting MPEG-SOD (monomethoxypolythlene glycol-SOD) intravenously 30 min before hypoxia, the increase of MDA (both of erythrocyte and plasma) and echinocytes (from erythrocytes) were both inhibited obviously during hypoxia for 24 h (n = 5, P < 0.05, P < 0.01 vs. hypoxia group). It is inferred that the increase of MDA and echinocytes from erythrocytes may be due to lipid peroxidation by superoxide free radicals (O2-.) generated in erythrocytes through Fenton pattern Haber-Weiss reaction during hypobaric hypoxia.

Altitude↗
PubMed1994

Regulation of hepatitis B virus ENI enhancer activity by hepatocyte-enriched transcription factor HNF3.

Hepatitis B virus (HBV) ENI enhancer can activate the expression of HBV and non-HBV genes in a liver-specific manner. By performing the electrophoretic mobility-shift assays, we demonstrated that the three related, liver-enriched, transcription factors, HNF3 alpha, HNF3 beta, and HNF3 gamma could all bind to the 2c site of HBV ENI enhancer. Mutations introduced in the 2c site to abolish the binding by HNF3 reduced the enhancer activity approximately 15-fold. Moreover, expression of HNF3 antisense sequences to suppress the expression of HNF3 in Huh-7 hepatoma cells led to reduction of the ENI enhancer activity. These results indicate that HNF3 positively regulates the ENI enhancer activity and this regulation is most likely mediated through the 2c site. The requirement of HNF3 for the ENI enhancer activity could explain the liver specificity of this enhancer element.

Base Sequence↗
PubMed1994

Constitutive expression of B-myb can bypass p53-induced Waf1/Cip1-mediated G1 arrest.

Overexpression of wild-type p53 protein has been shown to induce arrest in the G1 stage of the cell cycle and to transactivate expression of the gene that encodes the 21-kDa Waf1/Cip1 protein, a potent inhibitor of cyclin-dependent kinase activity. p53-dependent G1 arrest is accompanied by decreased expression of the B-myb gene, a relative of the c-myb cellular oncogene. In this study we show that B-myb expression is required for cells to progress from G1 into S phase and that high levels of ectopic B-myb expression uncoupled from cell cycle regulation rescues cells from p53-induced G1 arrest even in the presence of Waf1/Cip1 transactivation and inhibition of cyclin E/Cdk2 kinase activity. Cotransfection experiments with p53 expression plasmids and expression plasmids encoding in-frame deletion mutations in B-myb coding sequences indicate that the DNA-binding domain of the B-Myb protein is required for this activity. These results provide evidence of a bypass of p53-induced Waf1/Cip1-mediated cell cycle regulatory pathways by a member of the myb oncogene family.

Base Sequence↗
PubMed1994

Infrared studies on the interaction of carbon monoxide with divalent nickel in hydrogenase from Chromatium vinosum.

Infrared spectra of a carbon monoxy-bound form of the EPR silent Ni(II) species of hydrogenase isolated from Chromatium vinosum are presented. These spectra show a band at 2060 cm-1 due to v(CO) for a metal-CO complex. This absorbance shifts to 2017 cm-1 upon exposure of the enzyme to 13CO. This band is attributed to v(CO) from a Ni(II)-CO species. It is shown that the CO on this species is photolabile at cryogenic temperatures but rebinds to form the original carbon monoxy species at temperatures above 200 K. In addition to the v(CO) band, infrared lines are detected at 2082, 2069, and 1929 cm-1, which shift slightly higher in frequency upon photolysis of the CO from the Ni. These infrared bands do not arise from CO itself on the basis of the fact that the frequency of these bands is unaffected by exposure of the enzyme to 13CO. Experiments in D2O show that these bands do not arise from an exchangeable hydrogen species. It is concluded that these non-CO bands arise from species near or coordinated to the Ni active site. The possible nature of these bands is discussed.

Carbon Monoxide↗