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Biomedical subjects

D Chen

Publications and source records attributed to D Chen.

At least 775 records · Page 43Linked to original sources
PubMed1993

[Role of musculocutaneous nerve in the relationship between "chutse" acupoint and heart].

Ligating fourty eight rabbits left ventricular branch of coronary artery made model of acute myocardial infarction (AMI) with indices of ECG and size of AMI. They were divided at random into four groups: "Chutse" acupoint group, cutting musculocutaneous nerve of "Chutse" acupoint group, cutting musculoutaneous nerve group, control group. Results showed that there is no role in laser acupuncture at "Chutse" acupoint for reducing myocardial injury and size of AMI after cutting musculocutaneous nerve of "Chutse" acupoint. It is illustrated that the musculocutaneous nerve might play an important role in the relationship between "Chutse" acupoint and heart.

Acupuncture Points↗
PubMed1993

The prognostic characteristics of hypertensive left ventricular hypertrophy in a population with low prevalence of hypertension and low plasma cholesterol.

One hundred and twenty-six hypertensive patients with ECG left ventricular hypertrophy (HT-LVH) were followed for 10 years to investigate the prognostic characteristics in a population with low prevalence of hypertension (2.93%) and low plasma cholesterol (4.26 +/- 0.91 mmol/L). A cohort of age-, sex-, region- and occupation-matched, randomized hypertensives without ECG-LVH (n = 163) and normotensives (n = 275) served as controls. HT-LVH was found to be associated with an increased risk of overall death, stroke mortality and cardiovascular mortality. The major cause of death in rural hypertensives with ECG-LVH was stroke (56.8%). After adjusting BP and BP stratification, no significant difference of stroke risk was found between patients with and without LVH, while cardiovascular risk persisted in patients with LVH plus ST segment depression. LVH per se did not appear to be an independent factor for stroke death. Higher stroke mortality in patients with LVH may be ascribed to the coexisting higher level of BP. Furthermore, after adjusting for the coexisting hypertension, ECG-LVH in terms of voltage only was not related to the prognosis of stroke and cardiovascular death. The mortality rate of stroke was not affected by plasma cholesterol levels, as the levels seen were in a low range.

Adult↗
PubMed1993

[Preliminary observations on junctional intercellular communication in the epidermis of the adult mammal skins].

1. Shown by the sagittal cryostat-microsections, the epidermis of the adult mouse and rabbit skins consisted of 3-4 layers of cells, occupying about 40 mu in thickness. When advancing a penetrating microelectrode from the surface of the epidermis vertically downward into its depth, the cell membrane potentials of these layers in series, being -4---8mv, -6---20mv, -12---20mv, -12---20mv, respectively, could be got. These potentials, in turn, could be used to mark the proper insertion of the electrode in cell of a desired layer. Beyond the depth of 40 mu usually no membrane potential was met. 2. Microinjection of carboxyfluorescein (CoF) into cell in the first (shallowest) epidermal layer, no matter how long the injection time was, produced restricted dye transfer-only to 1 or 2 neighbor cells. Transfer to 3-5 neighbor cells would be seen in 15 min. after 7 min. of CoF injection into cell in the 2nd layer, and this number would slowly increased if the injection time was further prolonged. Similar CoF injection into cell in the 3rd or 4th (Malpighi) layer resulted in dye transfer to 20-40 neighbor cells. Most testing injections in this work have been done to cells in the 3rd epidermal layer.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[The relations between acupuncture manipulations and responsive discharges of deep receptors].

Twenty-nine rabbits were used. The spindle, tendon organ, light and heavy pressure receptors in medial gastrocnemius muscle were identified by recording discharges of single afferent fiber in medial gastrocnemius nerve from fine filaments by dissection. The discharge patterns of the receptors responding to the manipulations, i.c. lift and thrust, twist and twirl, rotate, scrape flick the needle and finger-pressure were observed. Data at 85 units were collected totally. Every type of deep receptor can react to any manipulation. The discharge patterns of different receptors were alike when stimulated with same manipulation, but there were different patterns while varying manipulations acting on the same receptor. These are due to the movement forms, the force amount, the time duration of the manipulations. All these facts are nearly the same as in cutaneous receptors. Acupuncture effect on deep receptors was not limited to one point but within a certain area, namely distant effect existed. The area size varied from receptor to receptor and from manipulation to manipulation. Because of the distant effect on receptors by acupuncture, and the lose of responsibility in units when receptor destroyed, we suggest that effective acupuncture stimulation is induced mainly due to the receptor deformation, which is caused by the stress from pressure, stretch and vibration of acupuncture. In view of the needling sensation is closely related to the curative effects, the receptors dealing with needling sensation are analysed according to this series works and other facts, we further advance the opinion that the receptors of deep pain are the chief material foundation to induce the sensation of hand needling.

Acupuncture Therapy↗
PubMed1993

Clinical study of 381 postmenopausal bleeding patients.

In order to evaluate the etiology, incidence of malignancy, clinical risk factors and the interval between menopause and the onset of abnormal vaginal bleeding in postmenopausal women, 381 cases with a complete medical history and available histologic findings were enrolled in this study at the National Taiwan University Hospital from 1989 to 1991. The results showed that 212 (55.6%) of these women had normal histologic findings and 83 (21.9%) had benign pathologic findings, whereas 14 (3.6%) had cervical intraepithelial neoplasia (CIN), 42 (11%) had endometrial hyperplasia, 19 (5%) had cervical cancer and 11 (2.9%) had endometrial cancer. Twenty-nine (7.6%) of the cases suffered from either CIN III or cervical cancer; this number was twice as high as those with endometrial atypical hyperplasia and endometrial cancer (n = 13, 3.4%). In addition, various risk factors, especially obesity, were found to be significantly correlated with malignancy. Fractional curettage should be performed for postmenopausal bleeding patients to ensure accurate diagnosis and correct management.

Endometrial Hyperplasia↗
PubMed1993

[The applicability of a new stable fluorescence reagent CGE (N) for TLC measurements and spectrofluorimetry].

A new stable fluorescent reagent, CGE (N), was designed and synthesized in our laboratory. This paper presents the results of using it to detect a compound having aminogroup. Glycine as an example was derived by using CGE (N), the best condition of derivatisation reaction was pH8, T 50 +/- 1 degree C, and time 3-5 h. Spread agent was CHCl3: CH3OH:CH3COOC2H5: iceHAc (1:3:5:1). Rf of glycine-CGE (N) was 0.45, of which fluorescent spectrum Em was 356nm (at Ex = 277nm). The correlation coefficient between the fluorescent scanning area and quantity was over 0.99, the linear relation retained for 24 h, the detection limit 0.24 microgram, and the linear range 0.24-19.2 micrograms. The data revealed that stability, sensitivity and reproducibility were good. These indicate that CGE(N) is a fine fluorescent reagent for compounds having primary amino-group and this method is reliable.

Chromatography, Thin Layer↗
PubMed1993

[Helicobacter pylori associated gastritis: a primary study of ammonia and urea in gastric juice and mucus in gastric mucosa].

The mucosa of 46 patients with histological chronic gastritis were cultured for helicobacter pylori (HP) and the ammonia and urea in their gastric juice were also determined. The results showed the average ammonia concentration (1.22 +/- 0.23 mmol/L) in HP positive patients was higher than that of HP negative patients (0.72 +/- 0.25 mmol/L), (P < 0.05). But the average urea concentration (0.45 +/- 0.29 mmol/L) in HP positive patients was lower than that of HP negative patients (2.71 +/- 1.20 mmol/L), (P < 0.05). The higher the level of ammonia stands, the more severe the gastritis is. (rs = 0.556). On the other hand, the quantity of mucus was elevated in 18 patients among 28 patients with HP eradicated by drug treatment, which was significantly different from the patients with HP not eradicated. It is suggested that the epithelium of gastric mucosa and the mucus are the chief components of the gastric mucosa barrier; the presence of HP increases ammonia, and thus damages the gastric epithelium and reduces the quantity of mucus. Consequently, the protective gastric mucosa barrier is damaged, and then comes the liability to HP-associated gastritis.

Ammonia↗
PubMed1993

[Laparoscopic cholecystectomy with the ultrasound dissector].

Due to tissue selectivity the ultrasonic dissector facilitates anatomical clearance even in difficult situations. Although of no advantage in routine laparoscopic cholecystectomies and even more time consuming, it seems to be of considerable value in difficult laparoscopic cholecystectomies and offers more safety for the patient.

Cholecystectomy, Laparoscopic↗
PubMed1993

[Prevention of reserpine induced experimental gastric ulcer in rat with amoxicillin a report of preliminary controlled study].

In recent years, amoxicillin (A) has been proved very effective in clearing helicobacter pylor (HP) and promoting ulcer healing. Is the cure due solely to the clearance of HP? Forty three Wistar rats were randomized into four groups to investigate the efficacy of A in preventing the experimental ulcer induced by reserpine and compare it with that of ranitidine (R) and antacid weishuping (W). A normal saline (NS) group was used as control. The total numbers of ulcer induced per rat for the NS, W, R and A groups were 7.8 +/- 5.1, 2.2 +/- 3.2, 1.0 +/- 1.2 and 2.1 +/- 1.9, respectively. The ulcer indices were 20.8 +/- 13.2, 4.5 +/- 7.7, 2.0 +/- 3.7 and 4.5 +/- 3.9, respectively. No HP was identified. The results indicated that A, R and W were all effective in preventing reserping induced ulcer with no significant difference (P > 0.05); they were significantly more effective than NS (P < 0.05). Since A is not an antacid and no HP existed in the experimental rats, there must be a mechanism of A involved in the prevention of experimental ulcer.

Amoxicillin↗
PubMed1993

New advances in vaccine delivery systems.

Successful application of the next generation of vaccines will require that protection be induced with a minimal number of administrations, and that a practical approach to inducing immunity at mucosal surfaces be developed. For these reasons, vaccine-containing microspheres were formulated from the biodegradable and biocompatible copolymer poly(DL-lactide-co-glycolide) [DL-PLG]. Subcutaneous immunization of mice with 1- to 10-microns microspheres containing a toxoid vaccine of staphylococcal enterotoxin B (SEB) induced a 500-fold potentiation of the circulating antitoxin response. Strong adjuvant activity was dependent on the microspheres being no more than 10 microns in diameter and required that the antigen was within the particles. The rate of DL-PLG biodegradation is a function of the ratio of lactide to glycolide, and the co-injection of SEB toxoid microspheres formulated with two different DL-PLG ratios stimulated both a primary and an anamnestic secondary antitoxin response. When it was administered by the oral or intratracheal (IT) route, microencapsulated SEB toxoid was found to be effective in the induction of concurrent circulating and disseminated mucosal antibody responses. Female rhesus macaques immunized with a microencapsulated simian immunodeficiency virus (SIV) vaccine produced high levels of circulating anti-SIV antibodies, and following oral or IT boosting, specific antibodies were found in vaginal wash fluids. Vaginal challenge with viable homologous SIV resulted in the infection of three out of four nonimmunized but only one out of seven microsphere-immunized macaques. Thus, DL-PLG microspheres are a promising approach to the delivery of vaccines, combining adjuvant activity with controlled release and effective presentation to mucosally associated lymphoid tissues (MALT).

Adjuvants, Immunologic↗
PubMed1993

[Studies on longevity tea].

This paper reports the preparation, physical and chemical identification and content determination of Longevity Tea. The preparation process is advanced, the content determination is simple and accurate and thus can be taken as standards for the quality control of Longevity Tea.

Drugs, Chinese Herbal↗
PubMed1992

Regulation of integrin gene expression by substrate adherence.

Under substrate adherent conditions, integrin gene expression can be regulated by transforming growth factor-beta, interleukin-1 beta, and prostaglandins. This report demonstrates a new mechanism that can differentially control the expression of several integrins. When MG-63 osteosarcoma cells are maintained in suspension, up-regulation of several integrin alpha-subunits takes place. Within as little as 4 h, the mRNA levels for both the alpha 2- and alpha 4-subunits are increased 4- and 6-fold, respectively. It was found that mRNA levels for the alpha 2-, alpha 4-, and alpha v-subunits were markedly increased in several differentiated cell lines under nonadherent conditions; however, cells that did not express a given integrin under substrate adherent conditions also did not express this integrin when maintained in suspension. The alpha 5-subunit did not upregulate during suspension growth. By immunocytochemistry, changes in integrin mRNA levels were confirmed at the protein level. Both cytochalasin B and a phorbol ester were found to induce the expression of the alpha 2-subunit, but not the alpha 4- and alpha 5-subunits, in a dose-dependent fashion. Many investigators have documented changes in gene expression that result from changes in "cell shape." These phenomena may result from up-regulation of integrin gene expression induced by the lack of substrate adherence.

Base Sequence↗
PubMed1992

Alpha 5 integrin subunit expression changes during myogenesis.

Fibronectin and its cellular receptor, the alpha 5 beta 1 integrin, are involved in the transmembrane signalling events that control muscle cell differentiation. In this study, the expression of the alpha 5 integrin subunit was followed by reverse transcription-polymerase chain reaction (RT-PCR) to determine alterations during myogenesis. In studies of murine muscle, we found a 90% reduction in the level of the alpha 5 integrin subunit mRNA during early postnatal development. Concurrently, the fibronectin alternative splicing pattern changed markedly in the EIIIB and V exons. In-vitro analyses of these molecules during myoblast differentiation revealed changes that followed trends similar to those observed in vivo, although of lesser magnitude. These observations imply an important role of fibronectin and the alpha 5 integrin subunit in muscle development.

Alternative Splicing↗
PubMed1992

Two-label peak-height encoded DNA sequencing by capillary gel electrophoresis: three examples.

We report a modification to the peak-height encoded DNA sequencing technique of Tabor and Richardson. As in the original protocol, the sequencing reaction uses modified T7 polymerase with manganese rather than magnesium to produce very uniform incorporation of each dideoxynucleoside. To improve sequencing accuracy, two fluorescently labeled primers are employed in separate sequencing reactions. As an example, one sequencing reaction uses a FAM-labeled primer with dideoxyadenosine triphosphate and dideoxycytosine triphosphate; the concentrations of ddATP and ddCTP are adjusted to produce a 2:1 variation in the relative intensity of fragments. The second sequencing reaction uses a TAMRA labeled primer with dideoxythymidine triphosphate and dideoxyguanidine triphosphate; the concentrations of ddTTP and ddGTP are adjusted to produce a 2:1 variation in relative intensity of fragments. The pooled reaction products are separated by capillary gel electrophoresis and identified by one of three different detector systems. Use of a 2:1 peak height ratio typically produces a sequencing accuracy of 97.5% for the first 350 bases; a 3:1 peak height ratio improves accuracy to 99.5% for the first 400 bases. For these experiments, capillary electrophoresis is performed at an electric field of 200 V/cm; two to three hours are required to separate sequencing fragments up to 400 nucleotides in length.

Bacteriophage T7↗
PubMed1992

Activity of a plasmid-borne leu-500 promoter depends on the transcription and translation of an adjacent gene.

leu-500 is a chromosomal promoter mutation in Salmonella typhimurium that normally causes the promoter to be inactive in the initiation of RNA synthesis. But in a strain that has mutations in topA, the gene encoding DNA topoisomerase I, the mutant promoter becomes active. We show that the leu-500 promoter can function on a plasmid when it is adjacent to the tetracycline-resistance gene tetA. Activation of the leu-500 promoter requires that the tetA gene is transcribed and translated and that the host cell is topA. We propose that the A----G mutation in the -10 region of the leu-500 promoter is compensated by local negative supercoiling arising from transcription of the tetA gene, which may reach elevated levels in a topA background, provided that diffusional dissipation is reduced due to anchoring of the TetA peptide in the membrane. This is a clear example of the modulation of the activity of a promoter by the activity of another promoter in cis, when they can be coupled through the topology of the template.

DNA Topoisomerases, Type I↗