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Biomedical subjects

J Cheng

Publications and source records attributed to J Cheng.

At least 451 records · Page 25Linked to original sources
PubMed1992

Differential effects of intracellular calcium elevating agents on adrenergic-stimulated cyclic nucleotide and melatonin synthesis in rat pinealocytes.

In this study, the role of elevation of intracellular Ca2+ and activation of protein kinase C on adrenergic-stimulated cyclic nucleotide accumulation and melatonin synthesis in rat pinealocytes was investigated. It was found that whereas KCl, ionomycin, and ouabain, three Ca(2+)-elevating agents, had a potentiating effect on adrenergic-stimulated cyclic AMP response, their effects on melatonin synthesis were inhibitory. Similar inhibition was also observed when dibutyryl cyclic AMP was used to stimulate melatonin synthesis. By determining intracellular Ca2+ directly, it was found that the enhancing effects of these agents on the cyclic AMP response but not their inhibitory effects on melatonin synthesis paralleled their abilities to elevate intracellular Ca2+. In comparison, activation of protein kinase C significantly enhanced the adrenergic-stimulated cyclic AMP response and, to a lesser degree, the adrenergic-stimulated N-acetyltransferase and melatonin levels. These results indicate that (i) Ca(2+)-elevating agents have opposite effects on adrenergic-stimulated cyclic AMP and melatonin production; (ii) a post cyclic AMP event of importance to melatonin synthesis is inhibited by these agents; and (iii) the mechanism of inhibition may not be directly related to their effect on intracellular Ca2+.

Animals↗
PubMed1992

Closure mechanisms of laryngeal vestibule during swallow.

This study examined the temporal effects of bolus volume on closure of the laryngeal vestibule at the arytenoid to epiglottic base and the mobile portion of the epiglottis, the temporal relationships between these levels of airway closure and cricopharyngeal opening for various bolus volumes, and the mechanisms responsible for these two levels of airway protection during deglutition. Closure of the laryngeal vestibule progressed inferiorly to superiorly at all bolus volumes. Duration of closure of the airway at the arytenoid to epiglottic base increased systematically with bolus volume, as did the duration of descent of the epiglottis below horizontal. Closure at the arytenoid to epiglottic base occurred earlier in relation to maximal laryngeal elevation as bolus volume increased. In contrast, descent of the epiglottis to horizontal and the temporal relationship between closure of the airway at the arytenoid to epiglottic base and cricopharyngeal opening were independent of bolus volume. These findings indicate a tightly organized neural program for some pharyngeal swallow events with systematic variability with volume in other pharyngeal events, possibly modulated by afferent input from the periphery. The neuromuscular mechanisms responsible for closure of the airway at the arytenoid to epiglottic base and at the mobile epiglottis appear to be quite different. Closure at the arytenoid to epiglottic base is apparently under direct neural control by active anterior tilting of the arytenoid cartilage and posterior projection of the epiglottic base as the larynx elevates, whereas epiglottic downward movement to closure is the biomechanical effect of hyolaryngeal movement, downward bolus movement, and tongue base retraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Studies on the luminescence of channels in rats and its law of changes with "syndromes" and treatment of acupuncture and moxibustion.

We previously reported the discovery of 14 channels in the human body, which possessed the biophysical property of high emission of light. In this study we found the same property on the Ren and Du channels in healthy rats. Additionally, we discovered that the luminance of the related channels in rat models with different "syndromes" varied greatly. For instance, a markedly low luminance appeared on the Du channel in animals with experimental syndrome of Yang deficiency induced by hydrocortisone; while in animals with experimental syndrome of blood deficiency caused by bleeding, an apparently low luminance occurred on the Ren channel. The intensity of the emitted light on Du and Ren channels increased after acupuncture treatment, but not significantly. This phenomenon conforms to the theory in traditional Chinese medicine that the Du channel is the "sea of Yang channels", while the Ren channel is the "sea of Yin channels".

Acupuncture Therapy↗
PubMed1992

[Effect of bradykinin, ionophore A23187 and trypsin on prostacyclin release from calf and pig aorta endothelial cells].

This paper details the methods of establishing stock culture and subculture of calf and pig aorta endothelial cells and the effects of bradykinin, ionophore A23187, trypsin and arachidonic acid (AA) on the release of prostacyclin (PGI2) from the cells. The release was measured by 6-keto PGF1 alpha radioimmunoassay. The results showed that the stimuli significantly increased the release of PGI2 in the two endothelial cell types (P < 0.01, n = 8), and the release was much stronger in pig than in calf endothelial cells under the experimental conditions. We therefore suggest that the reactivities of the two endothelial cells to the stimuli differ. The results offer useful information for further research of the mechanism of their pharmacologic actions on endothelial cells and their relationship with PGI2.

Animals↗
PubMed1992

[Studies on sedative and anticonvulsion effects of differently processed rhizoma Typhon].

Mice were employed to study sedative and anticonvulsion effects of Rhizoma Typhon processed by different methods. The results showed that processed and raw Rhizoma Typhon had marked sedative effect and delayed convulsion time, caused by cardiazole and strychnine. Processed and raw Rhizoma Typhon had similar action. With the new processing method, similar sedative and anticonvulsion effects were obtained compared with the old processing method.

Animals↗
PubMed1992

Role of the p53 tumor suppressor gene in the pathogenesis and in the suppression of acute lymphoblastic T-cell leukemia.

The tumor suppressor gene p53 has been shown to be mutated in 50% of acute lymphoblastic T-cell-leukemia (T-ALL) cell lines, all of which were established from T-ALL cases in relapse. In these lines both alleles of the p53 gene were independently affected by point mutation. In contrast, in human solid tumors possessing a mutated p53 allele, the second wild-type p53 suppressor allele is often lost by deletion rather than altered by mutation. This suggests that in T-ALL cell lines, the product encoded by the second mutated allele provides the cells with an additional oncogenic stimulus, beyond the loss of suppressive activity. While different p53 mutations have been shown to possess differential oncogenic potential in the p53 plus ras cotransformation assay, in T-ALL cells different mutations may in addition possess distinct functions, further contributing to the tumorigenic phenotype.

Animals↗
PubMed1991

Genetic influences in opioid analgesic sensitivity in mice.

Studies of various strains of mice revealed marked differences in their analgesic sensitivity towards morphine (mu), U50,488H (kappa 1) and naloxone benzoylhydrazone (NalBzoH; kappa 3). Sensitivity to mu and kappa analgesia varied independently of the other. Analgesic sensitivity to morphine remained relatively consistent among 3 different nociceptive assays for each strain. However, the sensitivity of an individual strain to NalBzoH remained highly dependent upon the assay used. CD-1 mice were sensitive to NalBzoH in all 3 assays, but in BALB/c mice NalBzoH produced analgesia only in the hot plate and cold water tail-flick assays. In Swiss-Webster mice, NalBzoH was active in the radiant heat and cold water tail-flicks but inactive in the hot plate. Although the levels of mu, kappa 1 and kappa 3 binding in whole brain homogenates did vary somewhat, they did not correlate with analgesic sensitivity. These results suggests that the genetic controls over mu and kappa analgesia operate independently and further illustrate the many difficulties in evaluating potential analgesics.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1991

Observation of the activity of factor VIII in the endometrium of women pre- and post-insertion of three types of IUDs.

The endometrial materials were obtained from 90 women who had been randomly inserted with three types of IUDs (Stainless steel ring, SS; copper T 220, TCu 220, and levonorgestrel-releasing device, LNG). An immunoperoxidase reaction, PAP method, with the antiserum of Factor VIII as the primary antibody, was carried out to detect the Factor VIII activity in the endometrial endothelium pre- (control) and post-insertion of the IUDs. The results revealed that: 1. There was a generalized lower Factor VIII activity in the endometrium of women post-insertion of IUDs (except LNG). 2. Comparison of the Factor VIII activity in the endometrium of women using different types of IUDs showed that the TCu type and the SS type decreased the activity significantly whereas the activity remained unchanged after 3-6 months' use of the LNG-IUD. The different types of IUDs seemed to influence the coagulation regulatory system in different ways; the lower Factor VIII activity, the more tendency to bleeding. 3. The Factor VIII activity in the endometrium of women using IUDs was lower in all phases of the menstrual cycle including the proliferative phase when the Factor VIII activity is normally high. It cannot be excluded that this could be a contributing factor to IUD-induced bleedings.

Adult↗
PubMed1991

Opioids regulate the release of human chorionic gonadotropin hormone from trophoblast tissue.

Opioid ligands were investigated for their effect on hCG release from trophoblast tissue obtained from term human placenta. Data obtained indicate that opiate agonists stimulate in vitro basal hCG release from trophoblast tissue. The potency of these opioid agonists correspond to their kappa receptor selectivity, i.e., the greater the selectivity the lower is the effective concentration causing maximum stimulation. Opioid antagonists inhibit the release of hCG due to their reversal of the stimulation caused by endogenous opioid peptides. Potency of the antagonists correspond also to their kappa receptor selectivity. Antagonists reverse the stimulation of hCG release caused by agonists indicating that the ligand's action is mediated by the placental kappa opioid receptors. The bell shaped response curves for agonists and antagonists suggest that opioids play a role in the regulation of hCG release from trophoblast tissue, but other mechanism(s) may also exist.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1991

Lectin histochemistry of cystic jaw lesions: an aid for differential diagnosis between cystic ameloblastoma and odontogenic cysts.

The binding sites for Ulex europaeus agglutinin I (UEA-I), Bandeirea simplicifolia agglutinin I (BSA-I), and peanut agglutinin (PNA) were comparatively examined in the surgical materials from 41 cases of cystic and solid ameloblastomas and 42 cases of non-neoplastic odontogenic cysts including dentigerous cyst, odontogenic keratocyst, and radicular cyst. In non-neoplastic cysts, most of epithelial lining layers gave positive binding with UEA-I and BSA-I. However, no positive reactions were obtained for these two lectins in the epithelial components of ameloblastoma, except for limited UEA-I binding to markedly keratinized tumor cells in four cases. PNA binding was irregular and did not make any clear distinction between ameloblastomas and cysts. The results suggest that the lectin staining for UEA-I and BSA-I is a useful histologic aid for differential diagnosis between cystic ameloblastoma and non-neoplastic jaw cysts.

Ameloblastoma↗
PubMed1991

Effects of spatial dispersion of acetylcholine release on AV conduction responses to vagal stimulation in dogs.

We determined the effects on atrioventricular (AV) conduction of changing the spatial dispersion of acetylcholine (ACh) release from vagal nerve fibers in anesthetized dogs. We paced the atria at a constant rate and stimulated the vagus nerves with one stimulus burst per cardiac cycle. We varied the spatial heterogeneity of ACh release in the cardiac tissues by changing the stimulus voltage, and we varied the quantity of ACh release from each excited nerve fiber by changing the number of pulses per stimulus burst. We slightly changed the stimulus timing with each heartbeat to scan the entire cardiac cycle. We constructed phase-response curves (PRCs) by plotting the changes in AV conduction time as a function of the timing of vagal stimulation. We found that the amplitude of the PRC varied directly with average AV conduction time (AV), whereas the minimum-to-maximum phase difference of the PRC varied inversely with AV. However, for any given change in AV, the specific characteristics of the PRCs did not depend on whether we varied the number of pulses per burst or the stimulus voltage. Therefore, the phase-dependent characteristics of the dromotropic responses appear to be unaffected by the spatial dispersion of ACh release from the vagal nerve endings. The effects of vagal activity on the AV conduction time are determined by those conducting fibers that are the least restrained by neurally released ACh.

Acetylcholine↗
PubMed1991

Plasma superoxide dismutase measurement in children with viral hepatitis.

Seventy-seven blood samples from normal controls aged 0-8 years and 93 blood samples from children of similar ages with various viral hepatitis were investigated by measuring plasma superoxide dismutase (EC 1.15.1.1) using chemiluminescence immunoassay (CLIA). Total and Cu,Zn-SOD activities of normal controls of group 2 (1-8 years old) were significantly higher than that of normal controls of group 1 (0-1 year old) (P less than 0.01, P less than 0.01), while there were no differences of Mn-SOD activities between the two groups. Total, Cu,Zn- and Mn-SOD activities significantly increased in the acute phase (0-4 weeks after onset) and dropped to the normal levels in the restoration phase (4th week later) for 29 children with cytomegalovirus hepatitis (CMVH), in comparison with group 1. Only Mn-SOD activities were significantly increased in the acute phase (with increased ALT levels) and restoration phase (with normal ALT levels) for 18 children with hepatitis A (HA). Total and Cu,Zn-SOD activities significantly decreased and Mn-SOD activities significantly increased in both the active (with increased ALT levels) and the inactive phases (with normal ALT levels) for 36 children with chronic persistent hepatitis (CPH). Only Cu,Zn-SOD activities fell significantly in both active and inactive phases for 10 children with chronic active hepatitis (CAH).

Child↗
PubMed1991

[Research and application of SUPER-1 intellectural instrument used in physiology laboratory].

Research work for making a biomedical signal processing instrument based on the APPLE-II computer is reported in this paper. According to the theory of the computer, two interface boards were designed as the hardware of the instrument. The memorizing waveform program was designed as the main program in the software system. Through a functional extended program, also called software inter face, more than ten programs especially for physiology can be easily linked to the main program. with the combination of both the software and hard ware several parameters of the instrument, such as sampling speed, gain of the amplifier, etc. can be controlled by a closed loop. This instrument is available in the physiology laboratory to replace oscilloscope, recorder, stimulator simultaneously. The functions of the instrument are stronger than those of the conventional instruments.

Microcomputers↗
PubMed1991

Endosonographic TNM staging of extrahepatic bile duct cancer: comparison with pathological staging.

Endosonography was performed preoperatively in 33 patients with common bile duct carcinoma and in 43 patients with carcinoma of the common hepatic duct and its bifurcation. The results were correlated with the histology of resected specimens according to the new (1987) TNM (tumor, node, metastasis) classification. Endosonography was accurate in the evaluation of the depth of tumor infiltration. Overall accuracy for common bile duct carcinoma and common hepatic duct carcinoma was 82.8% and 85%, respectively. Endosonography was helpful in diagnosing regional lymph node metastases but not accurate in diagnosing nonmetastatic lymph nodes. With common bile duct carcinoma, the incidence of lymph node metastasis increased with progressive depth of tumor infiltration. No such correlation was found in common hepatic duct carcinomas. In the staging of distant metastasis, this technique was limited by the low-penetration depth of ultrasonography. Thus, additional transcutaneous ultrasonography or computed tomography was necessary for complete staging. The routine use of the biopsy channel for endosonographically guided aspiration puncture will further enhance the diagnostic value of endosonography in the future.

Bile Duct Neoplasms↗