Biomedical subjects

W P Jiang

Publications and source records attributed to W P Jiang.

At least 19 recordsLinked to original sources

PubMed1994

[Studies on electrophysiology of lysophosphatidylcholine and evaluation of its clinical significance].

The cellular electrophysiological effects of lysosphatidylcholine (LPC) were investigated by using patch-clamp whole cell recording and conventional microelectrode technique, LPC(10 microns) suppressed the sodium, background potassium and calcium current and the effect of LPC on activity of ionic channels was nonselective. Resting potential, action potential amplitude and maximal rate of rise of phase of action potential were decreased with LPC (50 microns) perfusing. The incidence of abnormal automaticity, early after depolarization (EAD) and delayed after depolarization (DAD) was higher. It is clearly shown that LPC accumulates at early time of myocardial ischemia and thus may induce ischemic arrhythmias.

Action Potentials↗

PubMed1992

[Insight into the mechanism of torsade de pointes (TDP) induced by cesium chloride].

Standard intracellular potential recording technique was used in isolated guinea pig ventricular muscle and monophasic action potential (MAP) recording technique was performed on both the epicardium and endocardium of dog hearts in vivo. The results showed that CsCl lengthened action potential durations of ventricular muscle as well as QT intervals of dog hearts. The incidence of early after depolarization (EAD) induction was 71.4%. Ventricular tachycardia induced by CsCl manifested as typical TdP in 44.4% with EAD shown on epicardial MAP recording. This suggested that EAD and triggered activity might be an important mechanism of TdP. As verapamil could depress the induction of EAD, we believe that Ca++ inward currents was responsible for the induction of EAD and TdP by CsCl.

Action Potentials↗

PubMed1991

The astacin family of metalloendopeptidases.

Molecular cloning of a human intestinal brush border metalloendopeptidase (N-benzoyl-L-tyrosyl-p-aminobenzoic acid hydrolase, PPH) and a mouse kidney brush border metalloendopeptidase (meprin A) has revealed 82% identity in the NH2-terminal amino acid sequences (198 residues) of the mature enzymes. Furthermore, searching of protein sequence data bases with the inferred peptide sequences as probes revealed strong similarities to astacin, a crayfish digestive protease, and an NH2-terminal domain of a human bone morphogenetic protein (BMP-1). Meprin A and PPH both have approximately 30% identity with astacin and BMP-1. Multiple alignment analysis indicated that 37 residues, including 3 cysteine residues, are strictly conserved for the four proteins in a sequence frame equivalent to the complete 200-amino acid astacin sequence. The four proteins contain a zinc-binding motif (HEXXH), found at the active site of most metalloendopeptidases, within an extended sequence of HEXXHXXGFXHE which is unique to this subgroup of metalloendopeptidases. In addition, the four proteins have 54% identity in a 24-amino acid sequence that includes the putative active site. A fifth protein, Xenopus laevis developmentally regulated protein UVS.2, also shares sequence identity with the metalloendopeptidases. These data provide strong evidence for an evolutionary relationship of these proteins. It is suggested that this new family of metalloendopeptidases be called the "astacin family."

Amino Acid Sequence↗

PubMed1991

pH regulation of an egg cortex tyrosine kinase.

Fertilization of the echinoderm egg is known to result in the phosphorylation, on tyrosine, of a high-molecular-weight cortical protein (HMWCP) localized in the egg cortex. Studies using various parthenogenic agents indicate that this phosphorylation event occurs in response to the alkaline shift in cytoplasmic pHi which normally occurs 1 to 2 min after fertilization. In the present study, the purified egg cell surface complex was used as in vitro system to determine whether a small alkaline shift in pH, such as occurs upon fertilization, could stimulate the activity of the egg cortex-associated tyrosine kinase toward endogenous protein substrates. The results demonstrated that the cell surface complex is highly enriched in a tyrosine kinase activity which accounts for the majority of the protein kinase activity in this preparation. The activity of this tyrosine kinase toward the HMWCP and other cortical proteins was highly dependent on pH over the range pH 6.8 to 7.3. This indicates that the fertilization-associated change in cytoplasmic pH would be sufficient to trigger increased tyrosine phosphorylation of the high-molecular-weight cortical protein in vivo. The regulation of tyrosine phosphorylation by small changes in pH represents a novel control mechanism in which a tyrosine protein kinase may act as a pH-sensitive transducer.

Animals↗

PubMed1991

[A study on diarrhoea disease caused by Vibrionaceae along coast the east of Zhejiang Province].

A study of the etiology of 1028 cases of acute diarrhoea due to vibrionaceae was carried out between August 1988 to July 1990 along the coast of east Zhejiang Province. From 417 clinical cases (40.56%) were found. 590 strains (57.39%) of pathogenic vibrios Among them, the detection rates of vibrio, aeromonas and plesionmonas were 48.14%, 44.74%, 7.12% respectively. There were 8 Species of vibrio detected: V. parahemolyticus (63.73%), V. fluvialis (11.97%), V. alginolyticus (10.215), non-01 vibrio cholera (9.86%), V. furnissii (2.47%), V. mimicus (1.06%), V. metchnikovii (0.35%), V. vulnificus (0.35%). The detection rate of aeromonas species of A. sorbia, A. caviae, A. hydrophila and A. indefinite sp. were 30.68%, 27.27%, 22.73%, and 19.32% respectively. Plesionmonas shigellides was also found in this study. The age, sex, clinical features, detection rates of pathogenic vibrios of diarrhoea cases and sea food contact history were analyzed.

Adult↗

PubMed1990

Phorbol ester treatment stimulates tyrosine phosphorylation of a sea urchin egg cortex protein.

Fertilization of the sea urchin egg results in the phosphorylation, on tyrosine, of a high molecular weight protein localized in the egg cortex. In the present study, treatment of unfertilized eggs with the phorbol ester 12-O-tetradecanoylphorbol 13-acetate stimulated tyrosine phosphorylation of the high molecular weight cortical protein to levels three- to fivefold higher than that occurring in response to fertilization. Experiments using agents that inhibit the egg Na+/H+ exchange system or mimic the fertilization-induced shift in cytoplasmic pHi, suggest a signal transduction pathway in which protein kinase C activates the egg Na+/H+ exchange system and the resultant cytoplasmic pHi shift promotes tyrosine phosphorylation of the high molecular weight cortical protein.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1990

[Use of signal averaging system in the study of ventricular late potentials].

Signal-averaged electrocardiograms (SAECGs) were performed in 93 patients with various heart diseases and 20 dogs with experimental acute myocardial infarction. SA-ECGs were recorded with a high-pass bidirectional digital filter Mode FDS which was made by Shanghai Fudan University and Suzhou Medical College. All the patients and dogs were also examined with ART 1200 EPX recorder. Ventricular late potentials (VLPs) were directly recorded from the epicardium with experimental infarction by using composite electrodes and signal averaging system in late stage of coronary ligation. The results showed: VLPs were detected by body surface SA-ECG only in half of the dogs with VLPs detected by the real time mapping on infarction region, but the abnormal SAECGs did reveal the delayed ventricular activity; the data obtained with FDS or ART SA-ECG were similar.

Adult↗

PubMed1989

Nitrate induces enzymes of the mannitol cycle and suppresses versicolorin synthesis in Aspergillus parasiticus.

Addition of sodium nitrate to growing cultures of Aspergillus parasiticus (ATCC 36537) induces the synthesis of enzymes involved in nitrate assimilation (NO3- reductase), of enzymes in the pentose pathway (glucose-6-phosphate dehydrogenase), and of enzymes in the mannitol cycle (mannitol- and mannitol-1-phosphate dehydrogenases). Addition of NO3- also causes a dose-dependent suppression of synthesis of the polyketide secondary metabolite, versicolorin A. We suggest that in the presence of NO3- plus peptone, the cytoplasmic NADPH/NADP ratio may be elevated, resulting in increased conversion of malonyl coenzyme A to fatty acid rather than to polyketide.

Anthraquinones↗

PubMed1989

Intestinal crypt stem cells possess high levels of cytoskeletal-associated phosphotyrosine-containing proteins and tyrosine kinase activity relative to differentiated enterocytes.

Growth and differentiation of stem cells is thought to be regulated by growth factors and responding protein tyrosine kinase activities. Comparing mitotic stem cells from the adult intestinal epithelium, isolated from the crypts of Lieberkuhn, with isolated differentiated absorbtive cells we find major differences in the levels of phosphotyrosine-containing proteins. Crypt stem cells possess two major phosphotyrosine-containing polypeptides of 36 and 17 kD which have greater than 15 times more phosphotyrosine than that present in the polypeptides of differentiated enterocytes. Tyrosine kinase activity and similar phosphotyrosine-containing proteins are associated with the Triton cytoskeleton. Moreover, crypt tyrosine kinase(s) is active in vitro in phosphorylating similar cytoskeleton-associated substrates. These results suggest that cytoskeleton-associated phosphotyrosine kinase(s) and their substrates may play a role in growth and differentiation of adult intestinal epithelial cells.

Animals↗

PubMed1989

[Electrophysiologic studies on reentrant ventricular arrhythmia in the late myocardial infarction period].

The mechanisms of reentrant ventricular tachycardia were studied in canine post-infarction model. In 15 dogs that weighed 10-20 kg, the anterior descending coronary artery was ligated. 3 to 7 days after coronary artery occlusion, the dogs were reoperated to set up a composite electrode or a patch electrode with 32 bipolar electrodes. The composite electrode was utilized to record ventricular late potentials (VLPs) from the epicardial surface of the infarction zone (IZ) and adjacent normal zone (NZ). The bipolar electrodes were used to record the epicardial isochronal maps. 16 bipolar electrodes were placed over the area of infarction and its bordering zone and the other 16 bipolar electrodes were distributed over the remaining surface of the ventricle. Reentrant ventricular tachycardias were induced by programmed electrical stimulation. The VLPs and epicardial isochronal activation were recorded by SC-16 oscillograph and computerized mapping system during sinus rhythm and programmed stimulation. The experiments showed; 1) VLPs were demonstrated in 11 of the 15 dogs (73.3%) during programmed stimulation. 2) The reentrant circuit has a characteristic figure-8 configuration in the form of two circulating wave-fronts around arcs of functional conduction block that coalesce into a slow commun reentrant wave-front. One of the two synchronous circuits traveled clockwise and the other counter-clockwise. 3) VLPs represent a delayed depolarization at the ischemic myocardium, where the impulse conducts slowly in the reentrant circuit. It is clear that the present study may increase the understanding of the mechanism of ventricular arrhythmias in the late myocardial infarction period.

Animals↗

PubMed1989