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Biomedical subjects

M Chen

Publications and source records attributed to M Chen.

At least 559 records · Page 31Linked to original sources
PubMed1996

Field studies on the preventive effect of oral artemether against schistosomal infection.

OBJECTIVE: To study the preventive effect of oral artemether (Art) against schistosomal infection in the field. METHODS: In Minglang District of Yiyang City, Hunan Province, there is an islet with embankment type endemic area in the southern Dongting Lake region. From August to October 1994 the residents who frequently contacted the infested water were selected for study and allocated to the Art group and the control group. About one month before the preventive Art administration, all the residents understudied were examined by stool hatching technique, and then treated orally with praziquantel at a single dose of 40 mg/kg in stool egg-negative residents and 50 mg/kg in stool egg-positive ones. In the Art group, the first dose of 6 mg/kg was given at the end of August, followed by 3 repeated doses every 15 days. Placebo (starch) was given to the control group at the same time as in the Art group. The preventive efficacy was evaluated by stool examination 25-32 days after the last medication. RESULTS: In the Art group, 20 out of 365 studied residents became stool positive with an infection rate of 5.5%, while in the control group, 51 out of 376 studied residents were stool positive with an infection rate of 13.6%. The egg count per gram of feces (EPG) determined by the Kato-Katz method was 122 +/- 79 in the Art group and 681 +/- 909 in the control group. Meanwhile, two cases of acute schistosomiasis were found in the control group, but none was observed in the Art group. No apparent adverse side effect was seen during the treatment with Art. CONCLUSION: Oral Art exhibited apparent preventive effect on the residents who contacted the infested water in schistosomiasis endemic area.

Administration, Oral↗
PubMed1996

[Capsaicin-sensitive afferent neurons and endogenous nitric oxide (NO) mediate the gastric acid secretion and hyperemic responses to intragastric peptone].

Using hydrogen gas clearance technique to measure gastric mucosal blood flow (GMBF) and a high dose of capsaicin to ablate the capsaicin-sensitive afferent neurons, the role of capsaicin-sensitive neurons in the gastric acid secretion and hyperemic response to intragastric peptone was investigated. The results were as follows: (1) there was an increase in acid secretion associated with the hyperemic response to intragastric peptone; (2) pretreatment with a high dose of capsaicin to ablate afferent neurons completely abolished the gastric hyperemic response to intragastric peptone and partially inhibited the acid secretion; (3) the gastric hyperemic response to intragastric peptone was completely blocked by pretreatment with L-nitro-arginine methyl ester (L-NAME), whereas the acid secretion was significantly attenuated; (4) inhibited effects of L-NAME on acid secretion and GMBF could be reversed by pretreatment with L-arginine (L-ARG); (5) pretreatment with atropine inhibited gastric acid output (GAO) and partially attenuated GMBF. These results suggested that capsaicin-sensitive afferent neurons and endogenous NO were involved in the gastric acid secretion and hyperemic response to intragastric peptone and the hyperemic response was mediated by both cholinergic and noncholinergic neurons.

Animals↗
PubMed1996

The Hybaid Lecture. Microcollinearity and segmental duplication in the evolution of grass nuclear genomes.

Recent studies have shown that grass genomes have very similar gene compositions and regions of conserved gene order, as exemplified by collinear genetic maps of DNA markers. We have begun the detailed study of sequence organization in large (100-500 kb) segments of the nuclear genomes of maize, sorghum and rice. Our results indicate collinearity of genes in the regions homoeologous to the maize adh1 and sh2-a1 genes. Comparable genes were found to be physically closer to each other in grasses with small genomes (rice and sorghum) than they are in maize. In several instances, we have found evidence of tandem and 'distantly tandem' duplications of segments containing maize and sorghum genes. These duplications complicate characterizations of microcollinearity and could also interfere with some map-based approaches to gene isolation.

Biological Evolution↗
PubMed1996

[A study of the variation of the (AT)xTy motif-530bp 5' to the beta-globin gene in the Chinese population].

The repeated purine-pyrimidine motif (AT)xTy at the region -530bp 5' to the beta-globin gene is regarded as the binding site for BP1, a transcriptionally repressive nuclear protein. In present study, the rearrangement patterns of the -530 motif in the Chinese population, including 43 patients with various hemoglobinopathies and part of their relatives (34), as well as 20 hematologically normal individuals, were investigated with the method of ds-DNA cycle sequencing. The results showed that the -530 motif in Chinese people had three major variation types-(AT)8T5, (AT)7T7 and (AT)9T5. Besides, a novel rearrangement type, (AT)10T3, was found in a hematologically normal family. Furthermore, the analysis of haplotype between the beta-globin structural loci and the -530 motif rearrangement indicated that linkage disequilibrium existed between three mutant beta-globin genes (i.e., IVS-II-654(C-->T), CD41-42(-4bp) and HbE), and three -530 motif rearrangement types (i.e., (AT)8T5, (AT)7T7 and (AT)9T5)7 respectively.

Asian People↗
PubMed1996

Treatment of cutaneous T cell lymphoma with low doses of interferon alpha-2b.

OBJECTIVE: To evaluate the optimal dose and route of interferon-alpha-2b (INF-alpha-2b) given to the Chinese patients with cutaneous T-cell lymphomas (CTCL). PATIENTS AND METHODS: Sixteen Chinese patients with CTCL treated with INF-alpha-2b were evaluated. They were divided into groups according to the TNM Classification: I B (8 patients), II A (2), II B (5) and IV B (1). During induction INF-alpha-2b was given intramuscularly every other day or two times a week, beginning with a dose of 1-3 x 10(6) IU. Depending on tolerance, the dosage could be increased weekly to a maximum tolerated dose of 18 x 10(6) IU (mean, 6 x 10(6) IU/week) with administration two or three times a week. Patients with clinical response were given maintenance dosage from the start. Thereafter the dosage was gradually decreased after disappearance of skin lesions. Three patients were treated by combining intramuscular and intralesional injection of INF. RESULTS: Six patients (I B, 2 patients: II A, 2, II B, 2) achieved complete response (CR). Seven patients (I B, 5 patients) showed partial response. The overall response rate in this group was 81.25%. The prominent initial clinical response in three patients was manifested early at one week after intramuscular treatment with INF and then the skin lesions were resistant to the therapy but disappeared rapidly by combining intralesional injection of INF. The conditions of those patients obtaining CR within 3 to 6 weeks were stable for 1-36 weeks. CONCLUSIONS: This study had demonstrated that the overall response rate in treatment of patients with CTCL was 81.25% and higher (85.7%-87.5%) in the subgroups at early stages I and II of the disease. The dosage (mean dose of 6 x 10(6) IU/week) adopted by us is optimal for the Chinese patients with CTCL. Intralesional injection of INF could be recommended.

Adult↗
PubMed1996

[Curative effect of Interfon-Alpha in children with infectious mononucleosis].

Thirty-one cases of infectious mononucleosis treated with Interfon-Alpha were reported. The dose of intramuscular injection was one million units per day for 5-7 days. The recovery course of fever, angina, lymphadenopathy and hepatosplenomegaly was much shorter in the study group than in the control group (27 cases). The results suggested that interfon-Alpha should be efficacious against EBV activity and might shorten the course of this disease.

Antiviral Agents↗
PubMed1996

[The inhibition of yohimbine injected intrathecally on electroacupuncture-induced analgesia and release of beta-endorphin from rat brain].

Yohimbine (30 micrograms/8 microliters, ith), an antagonist of alpha 2-adrenergic receptor, can inhibit electroacupuncture-induced analgesia (EAA) for 15 min, with its biggest effect reducing the pain threshold of electroacupuncture (EA) to the level of sham electroacupuncture (SEA). Yohmbine also completely inhibit the increase of beta-endorphin in the push-pull liquids from ventriculus lateralis cerebri caused by EA. But yohimbine itself produce no effect on pain threshold and the concentration of beta-endorphin. These results suggest that EAA and the increased release of beta-endorphin caused by EA are related to the activation of alpha 2-adrenergic receptor in the spinal cord.

Acupuncture Analgesia↗
PubMed1996

[Repair of skin defects on the anterior portion of the foot with reversed dorsalis pedis flap].

Based on anatomical observations of the course of skin arteries and venous drainage of the reversed dorsalis pedis flap in 30 adult cadaversmretrograde dorsalis pedis flaps have been performed on six patients to repair their skin defects on the anterior portion of the foot. All the flaps survived without severe swelling or any necrosis. Clinical applications indicated that the blood supply and venous drainage of the flap were satisfactory. The advantages and key points of the operation were discussed in this paper.

Adolescent↗
PubMed1996

[Lobectomy by video-assisted thoracoscopic surgery].

Lobectomy by video-assisted thoracoscopic surgery (VATS) has been marked by decrease in pain, morbility, hospital stay, bleeding, and transfusion. This new way approach was performed on 10 dogs and 21 patients. In this paper we discuss how to deal with pulmonary vessels, bronchus and fissure. We suggested that Stage I lung cancer and lung disease were indicated of lobectomy by VATS.

Adolescent↗
PubMed1996

[The principle of nasal defects repair based on the frontal and temporal vessels anatomy].

After dissection of 9 corpes' (18 sides) vessels of the forehead, nose and temporal, we have discovered that the superatrochlear arteries run upward bilaterally, the branches of the supertrochelear arteries, the superficial branches of the supraorbital arteries and the front branches of the superficial temporal form a network--the frontal artery anastomotic net. The main trank and the parital branches of the superficial temporal arteries give off 2-3 ear branches. Based on these findings, we have made a series of explor atire researches, designed several new kinds of skin flaps for repairing the nasal defects, and improved a number traditional skin flaps. Guided by the above mentioned principles, we have successfully reconstructed 32 different kinds of nasal defects and achieved good results.

Adolescent↗
PubMed1996

[Mechanism of vascular desensitization to agonists].

The patterns and mechanism of vascular desensitization to agonists were studied in isolated arteries of Wistar and SHR rats. The results showed that: (1) Arteries were much easier to desensitize peptidergic agonists (A II, AVP) than catecholaminer gic agonists (NE, PE); (2) the desensitization induced by peptidergic agonists and catecholaminer gic agonists were homologous within 30 minutes; (3) the endothelium-EDRF-cGMP pathway was not involved in agonist-induced desensitization; (4) inhibition of surface receptor internalization by phenylarsine oxide (PAO, 10(-5)mol/L) could transiently reverse the desensitization and the blocking of intracellular receptor re-insertion into the membrane by chloroauine (10(-5)mol/L) could accelerate the desensitization in varying degrees with different arteries, which demonstrated the involvement of receptor cycling in homologous desensitization, but was not the unique mechanism; (5) there was no change in the function of voltage-dependent Ca2+ channel during homologous desensitization; (6) the concentration-contraction curve of GTP gamma S shifted down-ward during homologous desensitization, suggesting the functional change of G protein (s); (7) the desensitization to agonists didn't decrease in arteries of SHR compared with the arteries of Wistar rats.

Angiotensin II↗
PubMed1996

[Heterogeneity of adrenoceptors in rat basilar and renal arteries].

A comparative study was made on the distribution of alpha- and beta-adrenoceptors between rat basilar (BA) and renal arteries (RA). The results showed that (1) the endothelium-independent relaxation due to beta-agonism was more significant in BA than that in RA; (2) there was no alpha 1-adrenoceptor-mediated vasoconstriction in most of the BA, only a small part of BA showed constriction in response to alpha 1-agonism, but with low affinity and efficacy and a desensitization tendency; (3) no response to alpha 2-agonist BHT 920 (10(-3) mol/L) in BA was shown, either in the presence or absence of endothelium. But in RA there was relaxation in the presence of endothelium and constriction in its absence. The above results suggest that there is a scarce distribution of alpha 1- and alpha 2-adrenoceptors, but an abundant distribution of beta-adrenoceptor in basilar artery compared with that in renal artery. The alpha 1-subtype in BA is different from the alpha 1-subtype in RA, and the alpha 2-receptor which mediates direct smooth muscle constriction and endothelium-dependent relaxation is highly heterogeneous between basilar and renal arteries.

Adrenergic alpha-Agonists↗
PubMed1996

[Heterogeneities in intracellular Ca2+ pools among different arterial smooth muscle cells and its possible role in vascular reactivities in rat].

The differences in intracellular Ca2+ pool capacities, the mutual relations between different agonist-sensitive Ca2+ pools (ASCaP) and between ASCaP and caffeine-sensitive Ca2+ pool (CSCaP), and the possible role of Ca2+ pool capacity in vascular reactivities in different isolated artery rings of rat in Ca(2+)-free media were studied by using the tension of vascular smooth muscle as an indicator of Ca2+ release. The study showed the following findings: (1) the Ca2+ pools were significantly different in capacities in different arteries (renal artery > mesenteric artery > caudal artery > aorta > pulmonary artery); (2) different ASCaPs were partially "overlapped", i.e., when one ASCaP was depleted, other kind of agonist could still induce a small but significant Ca2+ release; (3) the CSCaP was present in all the arteries tested, but it was not the same pool with the ASCaP; (4) there were no high-K+ depolarization-induced Ca2+ release in all the arteries tested and (5) there was a positive correlation between the maximal contraction (Emax expressed as mg force/mg muscle wet weight) and the Ca2+ pool capacities, suggesting that there is a role of Ca2+ pool capacities in the vascular contractilities.

Animals↗
PubMed1996

[The relationship between human chorionic gonadotrophin and lipoprotein metabolism].

We compared human chorionic gonadotrophin (hCG-beta) with lipids, lipoproteins and apolipoproteins in serum between pre- and postmenopausal women, and observed the changes of levels of hCG-beta in animals suffering from hypertriglyceridemia. The results have shown that the concentration of hCG-beta in postmenopausal women is much higher than that in premenopausal women (P < 0.001). Correspondingly, triglyceride (TG) is elevated (P < 0.05). High density lipoprotein cholesterol (HDL-C) and HDL-C/LDL-C ratio are decreased (P < 0.001, P < 0.01). On the other hand, the tendency of highing hCG-beta level has been found in animal study. The concentration of hCG-beta in male rats suffering form hypertriglyceridemia is higher than that in normal animals (P < 0.05).

Adult↗
PubMed1996

[Mitral valve replacement under beating heart in 137 cases].

To avoid damage of myocardial ischemia, myocardial hypoxia and reperfusion injury, we designed mitral valve replacement in beating heart under extracorporeal circulation with low dose temperature of 31 degrees C to 35 degrees C in 137 cases of rheumatic heart disease, congenital heart disease mitral stenosis and mitral insufficiency, or concurrent aortic insufficiency. The patients were rept in unblocking aorta, unfilling cardiac arrest perfusion, idle pulse and dradycardia of 40-50 times/min, nose temperature of 32 +/- 1 degrees C. Patients with concurrent aortic insufficiency should first undergo replacement of aorta under cold cardiac arrest and then replacement mitral valve under beating heart to reduce the time of cold heart ischemia. Plastic surgery for tricuspid valve was done under beating heart. Good postoperative prognosis was nated: an average arterial pressure of 9.5-10.5 kPa (70 to 80 mmHg), dose of dopamine was obviously reduced. No low cardiac output syndrome, acute renal failure and severe arrythmia were observed in 137 cases, except 4 deaths due to infection and blood coagulation (2.9%). A left cardiac chamber no-level air removal device and aorta perfusioner leading flow device were designed for exsufflation of left pneumatocardia.

Adolescent↗
PubMed1996

[Long-term effects of CPAP in obstructive apnea syndrome].

OBJECTIVE: To study the long term effects with CPAP in OSAS. METHODS: Eighteen patients with OSAS were treated by CPAP at home for 3 to 27 months from 1987 to 1995, comparing the parameters of polysomnography (PSG) before and after treatment. RESULTS: (1) all the symptoms of OSAS were improved; (2) The parameters of PSG showed that the longest apnea duration from 66 +/- 21s to 43 +/- 24s (P < 0.05); AHI from 66 +/- 16 to 28 +/- 20 n/hour (P < 0.001); The lowest SaO2 from 53% +/- 19% to 75% +/- 11% (P < 0.001); (3) Comparing the body weight and blood pressure, no significant difference was shown before and after treatment with CPAP, but the blood pressure of 6 (50%) OSAS patients with hypertension had decreased to normal range. CONCLUSION: Long term treatment with CPAP in OSAS were effective, after which, the AHI, lowest level of hopoxemia, the longest apnea duration and the sympoms of OSAS were improved. The mechanism could be that the patents' breathing control were restored.

Adult↗