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Biomedical subjects

D Chen

Publications and source records attributed to D Chen.

At least 667 records · Page 37Linked to original sources
PubMed1995

Trophic effects in the acid-producing part of the rat stomach after pyloric stenosis.

BACKGROUND: Pyloric stenosis produces gastric hypersecretion and is thought to stimulate the growth of the gastric mucosa in the rat, the dog, and man. However, the mechanisms behind the hypersecretion and the trophic effect of pyloric stenosis are little known. The purpose of the present study was to examine whether the postulated trophic effects described include growth of the histamine-producing enterochromaffin-like (ECL) cells and whether circulating gastrin can be held responsible. METHODS: Pyloric stenosis was produced in rats by tying a ligature around the pylorus, thereby narrowing the passage through the sphincter. The animals were left for 4 to 12 weeks. RESULTS: The operation dilated the stomach, increased the serum gastrin concentration approximately twofold, and increased the oxyntic mucosal weight, volume, and surface area but not the mucosal thickness and total DNA content. The interglandular space was increased, and the DNA concentration was reduced. The density of the ECL cells (that is, the number of ECL cells per visual field) was reduced at 4 weeks and back to control values at 8 and 12 weeks. The calculated total volume of the ECL cell population was unchanged at first but showed a less than twofold increase 12 weeks after the operation. The volume density of the ECL cells (that is, the proportion of the mucosa made up of ECL cells) was reduced at 4 and 8 weeks and was back to normal at 12 weeks. The ECL cells are rich in histidine decarboxylase (HDC); whenever the cells are stimulated, the enzyme activity increases. The HDC activity in the oxyntic mucosa was reduced at first and returned to control values 12 weeks later. CONCLUSIONS: Pyloric stenosis per se does not affect the total number of oxyntic mucosal cells, but causes the ECL cell population to grow somewhat, probably because of the moderate hypergastrinemia. Interestingly, however, there was no increase in the HDC activity, suggesting that the ECL cells are not much activated by the operation.

Animals↗
PubMed1995

[Captopril in improving vascular structure and lowering blood pressure].

SHRs were given captopril 20 mg/kg/day (group A, n = 13) and 100 mg/kg/day (group B, n = 17) from intrauterus period to 16 weeks of age, then the treatment was removed. Experiments were carried out at 40 weeks. SBP, left ventricular mass/body weight ratio, wall/lumen ratio of branch III mesenteric and renal artery were determined. The perfusion pressure response to alpha 1 adrenergic agonist (phenylephrine) of resistance blood vessels in a hindquarter model in the presence of Nw-nitro-1-arginine-methyl ester (LNAME) or L-arginine were examined. Untreated SHR (n = 16) and untreated WKY (n = 17) served as controls. Both doses of captopril treatment completely prevented hypertrophy of vascular vessels to some extent comparable to that of the untreated WKY. But their SBP was still significantly higher than that of the untreated WKY. The curves of perfusion pressure responding to incremental doses of phenylephrine shifted rightward in the captopril treatment groups in a dose dependent manner. The curves of high dose group were almost identical to those of WKY, markedly different from that of the untreated SHR. Captopril decreased the over enhanced vasoconstrictor effect of LNAME in SHR. The attenuated vasoconstrictor effect by L-arginine was greatly augmented by captopril, suggesting that captopril improves the function of resistance of vessels by mediating endothelial cells. Captopril-induced alteration in vascular structure and function may be separated from its hypotensive effect. Clinically, continuing administration of captopril may be beneficial to the improvement of the vascular system in those blood pressure unresponsive patients.

Animals↗
PubMed1995

Dorsal scapular nerve compression. Atypical thoracic outlet syndrome.

The dorsal scapular nerve and long thoracic nerve of 10 cadavers (20 sides) and 36 patients with dorsal scapular nerve compression were studied anatomically. The origin of the dorsal scapular nerve of a section frequently shared a common trunk with the long thoracic nerve, and went through the scalenus medius anterointernally and posterolaterally with the presence of some tendinous tissues. Leaving the long thoracic nerve, it might give branches to the shoulder and the subaxillary region and finally have the branches join the long thoracic nerve again. The compression of the section near the origin caused discomfort and sourness of the neck, shoulder and back region. Clinically, the severance of the scalenus anterior and medius ameliorated or relieved the compression of the dorsal scapular nerve. Complete decompression required cutting of the scalenus medius and its tendinous tissue superficial to the dorsal scapular nerve. Among 24 sides of 22 patients undergoing surgery, the symptoms of 20 sides of 19 patients were completely or partially relieved.

Adult↗
PubMed1995

Effects of urine on the functional quality of human spermatozoa.

OBJECTIVE: To determine the effect of urine on sperm function and to elucidate the reason by which it may be deleterious. DESIGN: Prospective controlled in vitro study. INTERACTIONS: Sperm were exposed to various concentrations of pooled urine in Ham's F-10 Medium supplemented with 3.5 g% bovine serum albumin (GIBCO, Grand Island, NY) and sperm exposed to Ham's F-10 Medium with pH and osmolality adjusted to mimic that of the urine (pH 5.4; 520 mOsm). MAIN OUTCOME MEASURE: Sperm motility and the ability of sperm to penetrate and migrate into mucus and to penetrate hamster oocytes were determined. RESULTS: All sperm variables studied were significantly decreased when the sperm were exposed to > or = 40% urine. Potential of hydrogen- and osmolality-adjusted Ham's F-10 did not significantly affect the sperm function. CONCLUSION: Urine is deleterious to sperm function and may involve other biochemical factors that are unrelated to pH and osmolality of urine.

Animals↗
PubMed1995

A study of biological function of retinoblastoma gene (Rb gene).

The human wild-type Rb gene cDNA has been cis- or trans inserted into the retrovirus vector DOL, resulting in a sense-expression vector DOLRB and an antisense-expression vector DOLRBAS of Rb gene. By eletroporation transfection techniques, the vector DOLRB has been introduced into the human breast carcinoma cell line MDAMB468 and human hepatocellular carcinoma cell line SMMC7721 both of which have an inactivated Rb gene and the vector DOLBAS, into normal human embryonic lung fibroblasts HEL cells. With the expression of Rb protein, the growth rate of the MDAMB468 cells is decreased by about 50%, their colony formation ability in soft agar is repressed completely, and their tumorigenicity in nude mice is repressed partially. Meanwhile, the cell population of G1 phase of Rb+ MDAMB468 cells is increased markedly. About 75% of transfected SMMC7721 cells have been killed by Rb gene product. For HEL cells, with the transient expression of antisense Rb gene, the Rb protein synthesis is reduced and the growth rate of those cells increased, but no colonies of HEL cells are formed in soft agar.

Animals↗
PubMed1995

Quadrilateral space syndrome.

We studied 4 cases of quadrilateral space syndrome. Though the syndrome is quite uncommon, it might be discovered by examination of the patient complaining of pain of neck and shoulder especially when the tenderness in the quadrilateral space. Early surgical decompression is indicated as soon as diagnosis is made.

Adult↗
PubMed1995

Value of polymerase chain reaction assay in diagnosis of intestinal tuberculosis and differentiation from Crohn's disease.

It is difficult to make a precise diagnosis of intestinal tuberculosis and to differentiate it from Crohn's disease. For evaluating Polymerase Chain Reaction (PCR) assay in these two aspects, 36 specimens of intestinal tuberculosis from surgical resections and endoscopic biopsies and 26 Crohn's disease samples were subjected to PCR assay. 21 specimens of normal colon tissue surrounding cancer were used as the control. Oligonucleotides derived from the IS 6110 sequence, which is repeated in M. tuberculosis chromosome and highly specific for the M. tuberculosis complex, were used as a primer. The amplified PCR products were detected by examination of ethidium-bromide-stained polyacrylamide gels. The specificity of PCR products was confirmed by digestion with Sal I restrictive endonuclease and southern blot hybridization using digoxigenin-labeled probe. The results showed that the M. tuberculosis DNA was identified in 27/36 intestinal tuberculosis, but none of 26 Crohn's disease. Acid fast bacilli were only found in 16/36 intestinal tuberculosis. In conclusion, as a rapid, sensitive, and specific pathogenic method in diagnosis of intestinal tuberculosis, PCR assay has been developed in this study, and is considered valuable in the differentiation between intestinal tuberculosis and Crohn's disease.

Base Sequence↗
PubMed1995

In patients with hypertensive left ventricular hypertrophy and coronary heart disease, coronary flow reserve is similarly impaired.

Coronary blood flow reserve (CFR) was assessed by transesophageal Doppler echocardiography in normal subjects (group A, n = 20), hypertensive non-left ventricular hypertrophy (non-LVH) patients (group B, n = 22), hypertensive patients with LVH (group C, n = 32) and coronary heart disease patients (group D, n = 33) with the volume sample placed at the bifurcation of the left main and left descending coronary artery. Coronary blood flow velocity (CBFV) was evaluated at rest, 2 minutes after dipyridamole (0.56 mg/kg, i.v.), and 2 minutes after aminophylline i.v. The ratio of dipyridamole to rest maximal diastolic velocity (D/R PDV) was considered the index of coronary blood flow reserve. It was found that D/R PDV was significantly less in groups C and D compared with that in groups A and B(D/R PDV, 1.84 +/- 0.57, 1.57 +/- 0.41 versus 2.59 +/- 0.70 and 2.22 +/- 0.58, respectively), with no difference in D/R PDV between groups C and D. Twenty-four out of 32 patients in group C with D/R PDV were less than 2.0 compared to 29 out of 33 patients in group D (P > 0.05). Significant negative correlation was found between D/R PDV, D/R PSV and interseptal thickness, left ventricular mass index in hypertensive patients. These data show that impaired CFR in hypertensive patients with LVH is comparable to that in patients with coronary heart disease.

Adult↗
PubMed1995

[Analytical study on drug-processing of the root of Glycyrrhiza uralensis Fisch. by HPLC].

This paper presents a study on the drug-processing of the root of Glycyrrhiza uralensis. A HPLC method for the determination of glycyrrhizic acid in Glycyrrhiza uralensis and its processed products has been established. The method is simple, specific and accurate. The recovery is 99.97% and the relative standard deviation is 0.9%.

Chromatography, High Pressure Liquid↗
PubMed1995

[Investigation of damage of the gastric mucosal barrier by Helicobacter pylori].

Damage of the gastric mucosal barrier by Helicobacter pylori (Hp) has been investigated with estimation of antral mucosal hexosamine and phospholipid, and the degree of pathologic changes to be also evoluted in 100 cases of chronic superficial gastritis. There are 42% of 50 cases of Hp positive patients with active gastric lesions, and significantly high than 50 cases of Hp negative patients (8%). The mean value of antral mucosal hexosamine is 30.33 mg/g in Hp positive group, while in Hp negative group, the mean value is 36.98 mg/g (P < 0.005). The mean value of antral mucosal phospholipid is 31.96 mg/g in Hp positive. While in Hp negative is 36.49 mg/g (P < 0.05). So, estimation of mucosal hexosamine and phospholipid can be represent the degree of damage of gastric mucosal barrier. Hp should be considered as causative agent to break down the gastric mucosal barrier.

Gastric Mucosa↗
PubMed1995

[Clinical and pathologic analysis of 33 cases of brachial plexus neurinoma].

Clinical and pathological findings in 33 cases of brachial plexus neurinoma are reported. In 30 cases (90.91%) the diagnosis was proved to be correct by postoperative histological sections, and in other 3 cases (9.09%) the diagnosis couldn't be made preoperatively. The 33 cases were subjected to surgical resections and 18 (54.55%) of them still felt numbness and pain within two weeks after surgery. Sixteen cases were followed up for three months and 14 (87.5%) of them felt numbness by percussion over the incision. All the 33 cases had no brachial plexus traumatic complication postoperatively.

Adolescent↗
PubMed1995

Guyin decoction in the treatment of immuno-sterility and its effect on humoral immunity.

60 cases of immuno-sterility (treated group) were treated with Guyin Decoction, and were compared with 25 control cases treated by Western medicine. The results showed that in the treated group 19 cases were cured, 32 improved and 9 failed respond, while in the control group 6 were cured, 8 improved and 11 failed. The decoction had significant effect on serum IgA and IgG.

Adult↗
PubMed1995

[A prospective study on relationship between abnormal nasopharyngeal mucosa and nasopharyngeal carcinoma].

Abnormal nasopharyngeal mucosa was defined as abnormal finding under the examination of nasopharyngoscope. 43541 healthy persons aged 30-64 were observed for 6 years in the high risk area of NPC, by mean of EBV serological and nasopharyngeal cavity examination. The results are as follows. 1. In the high risk area of NPC, abnormal nasopharyngeal mucosa such as follicle hyperplasia and bulge are common in the younger people, especially in the post-roof of the nasopharyngeal cavity. 2. There was no significant difference on statistics between the abnormal and normal groups on the positive rate and GMT of EBV VCA/IgA. Abnormal nasopharyngeal mucosa did not change with the change of VCA/IgA titer. 3. There was significant difference on the prevalence rate of NPC between the abnormal nasopharyngeal mucosa and normal groups except the age, sex factors. There was no confirmation of the abnormal nasopharyngeal mucosa as precancerous lesion.

Adult↗
PubMed1995

An unique model for the analysis of neuronal nitric oxide signaling: the leech CNS.

An hypothesis for the presence of nitric oxide synthase (NOS) and the involvement of nitric oxide (NO) in neuronal signaling in the leach (Hirudo medicinalis) CNS is based on (i) the presence of fixative resistant NADPH-diaphorase (NADPH-d) in a specific neuronal population in the segmental ganglion; (ii) direct measurements with NO-sensitive electrodes giving an estimated NO concentration of 400-600 nM; (iii) biochemical assay for NOS using L-arginine/L-citrulline conversion in the CNS which gave a comparable value to that of the rat cerebellum and (iv) specific pharmacological effects of the NO precursor L-arginine and a NOS inhibitor (NG-Nitro-L-arginine) in modulation of chemical connections between NADPH-d-positive and NADPH-d-negative neurones. The very high value of estimated NO concentration and NOS activity and the relatively small number of putative NOS-containing (NADPH-d-positive) cells, including identified sensory (N, P, T cells), motor (AE) and interneurones (151) with known monosynaptic connections, make these neurones an ideal preparation on which to study the possible effects of NO on synaptic interactions.

Animals↗
PubMed1994

Inverse relationship of cotranslational translocation with the hydrophobic moment of the bovine preproparathyroid hormone signal sequence.

To investigate the dependence of transmembrane translocation on the hydrophobic moment of the hydrophobic core of the preproparathyroid hormone signal sequence, amino acids were switched to maximize or minimize the hydrophobic moment without changing the length or overall hydrophobicity of the core. As assayed in an in vitro translation system with microsomal membranes, the efficiency of translocation of these mutants was inversely related to the hydrophobic moment, indicating the hydrophobic moment or a related property may contribute to translocational activity.

Amino Acid Sequence↗