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W Tang

Publications and source records attributed to W Tang.

At least 271 records · Page 15Linked to original sources
PubMed1995

Cloning, localization, and functional expression of a human brain inward rectifier potassium channel (hIRK1).

We have cloned a novel human brain inward rectifier K+ channel (hIRK1), which shares approximately 60% amino acid identity with another human inward rectifier (hIRK2) but 98% identity with the mouse IRK1. The hIRK1 mRNA is expressed in several human tissues: skeletal muscle > placenta > heart > brain > lung > kidney. In human brain, the hIRK1 mRNA is uniformly distributed (except for a higher level in the corpus callosum, which contains white matter and glial cells), whereas the hIRK2 mRNA is expressed in major regions of the basal ganglia and limbic system. Xenopus oocytes injected with hIRK1 cRNA expressed an inwardly rectifying K+ current that was blocked by extracellular Ba2+. The hIRK1 channel carried a significant outward current when membrane potential was more positive than the K+ equilibrium potential (EK) and therefore had an "N-shape" current-voltage relation, resembling that of the native cardiac IRK channel. The resting membrane potential was near EK in oocytes expressing hIRK1, but was approximately -40 mV in H2O-injected or non-injected oocytes. The ability of hIRK1 to set the resting membrane potential depended on the outward current. Single-channel conductance of hIRK1 was 32 pS measured with 150 mM KCl in the patch pipette, significantly higher than 23 pS measured for mouse IRK1 and approximately 10 pS for hIRK2.

Amino Acid Sequence↗
PubMed1994

Cloning a novel human brain inward rectifier potassium channel and its functional expression in Xenopus oocytes.

We have cloned a novel inward rectifier K+ channel (hIRK2) from a human frontal cortex cDNA library. The amino acid sequence of hIRK2 shares 60% and 40% identity with the mouse IRK1 and the rat ROMK1 channels, respectively. Xenopus oocytes injected with hIRK2 cRNA showed an inwardly rectifying K+ current that had a prominent 'N-shape' I-V curve and was blocked by extracellular Ba2+. The hIRK2 channel has two unique features: (a) an 18 amino acid insertion between the first transmembrane region and the pore, and (b) restricted mRNA distribution found only in human brain and heart.

Amino Acid Sequence↗
PubMed1994

Peptide receptors in astroglia: focus on angiotensin II and atrial natriuretic peptide.

Astroglial cells derived from the mammalian central nervous system contain a wide variety of peptide receptors, including specific sites for angiotensin II (AII) and atrial natriuretic peptide (ANP). The AII receptors present in these cells are primarily of the AT1 subtype. The ANP receptors present in these cells consist of a mix of ANP-A and ANP-B sites ("biological receptors") and also ANP-C sites ("clearance receptors"). Available evidence indicates that activation of AII receptors results in a stimulation of astroglial proliferation, whereas ANP has an antiproliferative effect in these cells. Intracellular pathways which may mediate these effects of AII and ANP on cell proliferation are discussed, including the presentation of novel data on the activation of protein kinase C and of glucose uptake by AII. We also consider the possibility that the opposing actions of AII and ANP on astroglial proliferation may represent another facet of the mutual antagonism between these two peptides, which has been observed throughout mammalian systems.

Angiotensin II↗
PubMed1994

Prevalence of fluoroscopic coronary calcific deposits in high-risk asymptomatic persons.

Coronary calcific deposits are always associated with coronary atherosclerosis. Sensitive radiographic technology can detect coronary calcium before atherosclerosis becomes symptomatic. A total of 1461 asymptomatic high-risk adult subjects were studied with digital subtraction fluoroscopy to detect coronary calcium. Risk factor data were recorded including age, sex, family history, smoking history, diabetes history, body mass index, systolic blood pressure, left ventricular hypertrophy on ECG, total serum cholesterol level, high-density lipoprotein (HDL) cholesterol, and total cholesterol/HDL ratio. Digital subtraction fluoroscopy in the left anterior oblique projection was performed in all subjects. The prevalence of calcific deposits in at least one major coronary artery was high (58.3%). Eleven percent had coronary calcium in all three major arteries. Multivariate logistic regression analysis showed significant correlations (p < 0.05) between the prevalence of coronary calcium and age, smoking history (relative risk = 1.30), diabetes history (relative risk = 1.24), and family history (relative risk = 1.26). In older subjects (at least 65 years of age), smoking and serum lipoproteins assumed greater importance as contributors to coronary calcium, whereas in younger subjects a history of diabetes was more significant. Coronary calcific deposits are prevalent in high-risk asymptomatic subjects. Their occurrence is closely related to most known risk factors.

Age Distribution↗
PubMed1994

Prognostic significance of cardiac cinefluoroscopy for coronary calcific deposits in asymptomatic high risk subjects.

OBJECTIVES: This research investigated the prognostic significance of radiographically detectable coronary calcific deposits. BACKGROUND: Coronary calcific deposits are almost always associated with coronary atherosclerosis. We investigated the association between fluoroscopically determined coronary calcium and coronary heart disease end points at 1 year of follow-up. METHODS: This prospective population-based cohort study was conducted in the suburbs of Los Angeles. Fourteen hundred sixty-one asymptomatic adults with an estimated > or = 10% risk of having a coronary heart disease event within 8 years underwent cardiac cinefluoroscopy for assessment of coronary calcium at initiation of the study. Clinical status including angina, documented myocardial infarction, myocardial revascularization and death from coronary heart disease were determined after 1 year. RESULTS: The prevalence of calcific deposits was high (47%). A follow-up examination at 1 year was successfully completed in 99.9% of subjects. Six subjects (0.4%) had died from coronary heart disease and 9 (0.6%) had had a nonfatal myocardial infarction. Thirty-seven subjects (2.5%) reported angina pectoris, and 13 (0.9%) had undergone myocardial revascularization. Fifty-three subjects had at least one event during the 1-year period. Radiographically detectable calcium was associated with the presence of at least one of these end points, with a risk ratio of 2.7 (confidence limits 1.4, 4.6). The presence of coronary calcium was an independent predictor of at least one end point when controlling for age, gender and risk factors. However, three deaths due to coronary heart disease and two nonfatal myocardial infarctions occurred in subjects without detectable coronary calcium. CONCLUSIONS: The presence of coronary calcific deposits incurs an increased risk of coronary heart disease events in asymptomatic high risk subjects at 1 year. This increased risk is independent of that incurred by standard risk factors.

Aged↗
PubMed1994

Spontaneous gasping increases the ability to resuscitate during experimental cardiopulmonary resuscitation.

OBJECTIVE: To evaluate the effect of spontaneous gasping on cardiorespiratory functions and the ability to resuscitate during experimental cardiac arrest. DATA SOURCES: Studies in rat and pig models during cardiac arrest and cardiopulmonary resuscitation (CPR). STUDY SELECTION: We retrospectively examined the role of spontaneous gasping during the course of experimental studies on cardiopulmonary resuscitation. DATA EXTRACTION: The data were extracted to illustrate the mechanisms of spontaneous gasping and its effects on pulmonary gas exchange and blood circulation during CPR. DATA SYNTHESIS: Spontaneous gasping increased PaO2 and decreased PaCO2 values during precordial compression in the absence of mechanical ventilation. The frequency of gasping during precordial compression was greater in successfully resuscitated animals. A significant linear correlation was established between coronary artery perfusion pressure and both the frequency (r2 = .90, p < .01) and the duration (r2 = 0.69, p < .01) of gasping during untreated ventricular fibrillation and before resuscitation was attempted. Like coronary perfusion pressure, the frequency and duration of gasping predicted the success of cardiac resuscitation attempts. CONCLUSIONS: Spontaneous gasping is associated with both pulmonary and hemodynamic effects during cardiac arrest in experimental animals. Spontaneous gasping is biologically useful and is predictive of a more favorable outcome of resuscitative efforts.

Animals↗
PubMed1994

Reproducibility of digital subtraction fluoroscopic readings for coronary artery calcification.

RATIONALE AND OBJECTIVES: Digital subtraction fluoroscopy, an inexpensive screening test for coronary atherosclerosis, is highly sensitive in detecting coronary calcifications. However, no previous study has reported interobserver agreement for this test. METHODS: Six hundred and thirty-one subjects underwent digital subtraction fluoroscopy in the 60 degrees left anterior oblique projection. Images were acquired with pulsed fluoroscopy at 15 frames per second. An averaged mask was subtracted from successive images. These fluoroscopic images were stored on a digital disk and replayed in cine loop format. An observer, blinded to clinical information, read the fluoroscopic studies for the presence of calcium in the left main-left anterior descending artery, circumflex artery, and right coronary artery. The images were then stored on digital tape and reread by a second blinded observer. RESULTS: The percentages of interobserver agreement regarding the presence and absence of calcium in left main-left anterior descending, circumflex, and right coronary arteries, were 91.9%, 92.9%, and 92.2%, respectively. The overall kappa values, which are 0.85, 0.77, and 0.82 in left main-left anterior descending, circumflex, and right coronary arteries, respectively, show a highly significant level of agreement (P < .0001). CONCLUSION: Digital subtraction fluoroscopy is a reliable screening test for coronary calcifications.

Calcinosis↗
PubMed1994

Accuracy of quantifying coronary hydroxyapatite with electron beam tomography.

RATIONALE AND OBJECTIVES: The electron beam tomography coronary calcium score continues to be used without experimental validation. To determine its accuracy, a series of experiments was performed. METHODS: A chest phantom model was constructed with coronary arteries represented by cylindrical holes containing hydroxyapatite granules embedded in a gelatin matrix to simulate coronary arteries. Experiments were performed to determine the relationship between the mass of hydroxyapatite in each of these arteries, the coronary calcium score currently used in coronary screening, and an alternative method of estimating mass from the images. The model was scanned with equal amounts of hydroxyapatite in each artery: 1) when the cylindrical heart was rotated 36 degrees 10 times between scans, and 2) when the particle diameters varied from 0.1 mm to 4 mm. The scores were calculated, and a subtraction algorithm was applied to estimate the exact mass of hydroxyapatite in each artery. RESULTS: The hydroxyapatite scores varied by 42% with position and by 1.54 x 10(6)% with particle diameter. The estimated masses from the subtraction algorithm were more stable with position and particle size, with maximum percent errors of 10% and 14% for position and particle size, respectively. CONCLUSIONS: These results suggest that the coronary calcium score is invalid, and that more precise and clinically relevant methods, such as the arterial summation method, should be rigorously tested in clinical studies.

Algorithms↗
PubMed1994

Human rsk isoforms: cloning and characterization of tissue-specific expression.

Serine-threonine protein kinases in the ribosomal S6 kinase (rsk or p90rsk) family have been implicated as signaling intermediates in the cellular response to several growth factors. To investigate the molecular diversity of human p90rsk isoforms, mixed degenerate oligonucleotide polymerase chain reaction was used to isolate partial rsk cDNAs (1.1 kb). Three closely related human rsk cDNAs were obtained (HU-1, HU-2, HU-3). These cDNAs are encoded by separate genes based on DNA sequence diversity and distinct patterns seen with genomic Southern blots. Northern analysis revealed different sized mRNA transcripts for each isoform. A full-length HU-1 cDNA (3.1 kb) was subsequently isolated from a HeLa cell library. 5'-cDNA clones for HU-2 and HU-3 were isolated using the "rapid amplification of cDNA ends" strategy. Experiments using human x hamster somatic cell hybrids localized the HU-1 gene to human chromosome 3; HU-2 is on chromosome 6; and HU-3 is on the X chromosome. The tissue distribution of human rsk mRNAs was determined using ribonuclease protection assays. HU-3 mRNA was present in multiple RNA samples. HU-2 was expressed in fibroblast > muscle > lymphocyte = placenta > liver. HU-1 was expressed in Epstein-Barr virus lymphocyte > > muscle = liver > fat = placenta. These results indicate that the multiplicity of p90rsk isoforms is increased to at least three for humans and that marked tissue-/cell-specific differences in p90rsk isoform expression are present.

Amino Acid Sequence↗
PubMed1994

Gastric intramural PCO2 as monitor of perfusion failure during hemorrhagic and anaphylactic shock.

Indirect measurement of gastric intramural pH (pHG) utilizing a luminal tonometer in the stomach has been proposed for monitoring the severity and progression of perfusion failure. In the present study, we investigated gastric PCO2 and pHG as indicators and quantitators of the severity of perfusion failure in the experimental rodent model of both hemorrhagic and anaphylactic shock. Gastric intramural PCO2 (PGCO2) and pHG were directly measured with miniaturized sensors inserted into the anterior wall of the stomach. In hemorrhagic shock, animals were bled into a reservoir maintained at a pressure of 35 mmHg. pHG decreased from 7.39 +/- 0.08 to 6.67 +/- 0.11 (P < 0.01), and PGCO2 increased from 53 +/- 4 to 136 +/- 3 Torr (P < 0.01). Anaphylactic shock was induced in animals that had been sensitized 21 days before with crystallized ovalbumin. Antigen challenge produced an immediate reduction in mean aortic pressure from 144 to 60 mmHg. pHG decreased from 7.40 +/- 0.05 to 6.99 +/- 0.07 (P < 0.01), and PGCO2 increased from 48 +/- 5 to 133 +/- 9 Torr (P < 0.01). The increases in PGCO2 were highly correlated with decreases in gastric blood flow in both hemorrhagic (r = 0.96) and anaphylactic shock (r = 0.92). The correlations with pHG were more moderate. These experiments demonstrated prominent increases in PGCO2 and H+ during both hemorrhagic and anaphylactic shock. We further noted that the estimation of pHG based on the assumption that HCO3-concentrations of the stomach wall and arterial blood are the same was not fully sustained.

Anaphylaxis↗
PubMed1994

Spontaneous gasping during cardiopulmonary resuscitation without mechanical ventilation.

Spontaneous gasping is frequently observed during cardiac arrest, especially when mechanical ventilation is withheld during precordial compression. We related spontaneous gasping to pulmonary gas exchange and cardiac resuscitability in a rodent model of cardiac arrest. Ventricular fibrillation was electrically induced in 15 Sprague-Dawley rats. After 4 min untreated ventricular fibrillation, precordial compression was initiated. Coronary perfusion pressure was maintained between 25 and 30 mm Hg. Oxygen was supplied at the tracheal tube port coincident with start of precordial compression in 10 animals. Five additional control animals were identically treated except they were mechanically ventilated coincident with start of precordial compression. After 6 min precordial compression, defibrillation was attempted and five of 10 nonventilated animals, and all control animals, were resuscitated by direct current countershock. In the successfully resuscitated, nonventilated animals, the frequency of spontaneous gasping during precordial compression progressively increased to an average of 19 gasps/min but it was < 6 gasps/min in nonresuscitated animals. More frequent gasping was associated with correspondingly greater arterial PO2 (110 versus 51 mm Hg, p < 0.01) and lesser PCO2 (55 versus 91 mm Hg, p < 0.01). In control animals, no spontaneous gasping was observed during precordial compression. Arterial PO2 and PCO2 of mechanically ventilated animals was more like that of spontaneously gasping rats. According, the frequency of spontaneous gasping in absence of mechanical ventilation is predictive of cardiac resuscitation success and associated with improved arterial oxygenation and CO2 removal.

Analysis of Variance↗
PubMed1994

Cardiopulmonary resuscitation by precordial compression but without mechanical ventilation.

It is widely held that mechanical ventilation is essential for cardiopulmonary resuscitation (CPR). However, cardiac output and therefore pulmonary blood flow is reduced to less than one-third of normal during CPR. We therefore reasoned that ventilatory requirements are correspondingly reduced and postulated that gas exchange may be maintained during precordial compression with oxygen passively delivered to the airway in the absence of mechanical ventilation. After tracheal intubation, Sprague-Dawley rats were randomized. Fifteen animals were maintained on positive-pressure ventilation with room air and an additional 15 animals breathed spontaneously. Cardiac arrest was induced by electrical fibrillation. The inspired gas concentration of oxygen was then increased to 100% in both groups. Precordial compression was begun after 4 min of untreated ventricular fibrillation. After an additional 6 min of precordial compression, resuscitation was attempted by DC countershock. During cardiac resuscitation, there were no significant differences in coronary perfusion pressure between mechanically ventilated and spontaneously breathing animals, but arterial PO2 was significantly lower and arterial PCO2 was significantly higher in the absence of positive-pressure ventilation. However, neither resuscitability nor 24-h survival were affected. Postresuscitation myocardial contractility, reflected in the maximally generated dP/dt40, was also not adversely affected. In the unventilated group, only resuscitated animals developed spontaneous gaspings at an average frequency of 17 +/- 2/min-1. The current emphasis on mechanical ventilation as the highest priority for cardiopulmonary resuscitation is therefore not fully supported under the experimental conditions of this study.

Animals↗
PubMed1994

[Fine needle aspiration cytology and influencing factors in breast cancer].

The results of 200 women with primary breast cancer who had fine needle aspiration cytology prior to definitive surgery at the Peking Union Medical College Hospital were presented. Among them, aspiration cytology was positive and suspicious in 87% (174/200) and pseudonegative in 13% (26/200). Clinical factors relating to the success of these aspiration were evaluated. The most significant factor was which physician performed the aspiration. Size of the lesion and type of the cancer were also important influences on the aspiration. Experiences in aspiration cytology were introduced by author.

Adenocarcinoma↗
PubMed1994

Rehabilitative effect of music therapy for residual schizophrenia. A one-month randomised controlled trial in Shanghai.

Seventy-six in-patients who had the residual subtype of schizophrenia were randomly assigned to a treatment group or a control group. Both groups received standard medication as prescribed by their treating physicians, but the treatment group also received a one-month course of music therapy that included both passive listening to music and active participation in the singing of popular songs with other patients. Outcome was evaluated by four nurses using Chinese versions of the Scale for Assessment of Negative Symptoms and the in-patient version of the World Health Organization's Disability Assessment Scale. Music therapy significantly diminished patients' negative symptoms, increased their ability to converse with others, reduced their social isolation, and increased their level of interest in external events. As music therapy has no side-effects and is relatively inexpensive, it merits further evaluation and wider application.

Adolescent↗
PubMed1994

The application of traditional Chinese medicine to the management of hepatic cancerous pain.

The authors summarized the application of traditional Chinese medicine to the management of hepatic cancerous pain in Beijing and Shanghai, and in Jiangsu and Zhejiang Provinces. The therapeutic principle was to invigorate blood circulation and reduce stasis and to soothe the liver and regulate qi, so as to dredge the channels and collaterals. The results were satisfactory.

Amphibian Venoms↗
PubMed1994

Ventricular fibrillation voltage as a monitor of the effectiveness of cardiopulmonary resuscitation.

Ventricular fibrillation (VF) voltage was previously identified as a predictor of the success of cardiopulmonary resuscitation. In the present study we investigated the mechanism by which VF voltage predicts the success of cardiac resuscitation in a well-established rodent model of cardiac arrest. After 4 minutes of untreated VF, precordial compression was initiated and maintained for 6 minutes. Increases in coronary perfusion pressure during precordial compression were associated with concomitant increases in VF voltage (r = 0.61, p = 0.013). Significantly greater coronary perfusion pressure (24 vs 17 mm Hg) and VF voltage (0.17 vs 0.12 mV) were observed in resuscitated animals. To obviate electrical artifacts produced by precordial compression, boluses of oxygenated blood were injected into the ascending aorta in another 5 animals as an alternative method of cardiac resuscitation. This restored myocardial perfusion before defibrillation. Increases in VF voltage from 0.04 mV to 0.47 mV during aortic infusions were again correlated with coronary perfusion pressure (r = 0.62, p < 0.01) and predicted the success of cardiac resuscitation. Greater VF voltages after initiation of cardiac resuscitation were associated with increases in myocardial creatine phosphate, from 0.23 to 0.70 mmol/kg wet weight, and significant decreases in lactate content, from 22.8 to 13.9 mmol/kg wet weight. Increases in creatine phosphate were highly correlated with increases in VF voltage (r = 0.99, p < 0.01). Accordingly, increases in VF voltage during cardiac resuscitation reflect increases in myocardial perfusion and favorable changes in myocardial energy metabolism. As such, VF voltage, like coronary perfusion pressure, serves as a quantitative predictor of the success of cardiopulmonary resuscitation.

Action Potentials↗
PubMed1994

Cardiac resuscitation by retroaortic infusion of blood.

Current methods of closed-chest cardiac resuscitation generate coronary perfusion pressures that rarely exceed one fourth of normal, and this decreases with prolongation of cardiac arrest. The resuscitation effort is therefore almost uniformly unsuccessful when precordial compression is initiated after 8 minutes of untreated cardiac arrest. This report introduces a new option for cardiac resuscitation by infusion of oxygenated blood into the ascending aorta such as to transiently increase the pressure gradient for coronary perfusion. Thirty-six anesthetized, mechanically ventilated normovolemic rats were investigated. Cardiac arrest was induced with an alternating current delivered through an electrode catheter advanced into the right ventricle. Ventricular fibrillation was untreated for 4, 6, or 8 minutes, after which resuscitation was attempted without blood infusion, with infusion of oxygenated blood, or with infusion of oxygenated blood containing 30 mg/kg epinephrine. The boluses of blood were delivered through a catheter advanced from the right carotid artery into the ascending aorta. Except for mechanical ventilation and direct current precordial countershock for electrical defibrillation, no other mechanical resuscitation intervention, and specifically no precordial compression, was administered. None of six control animals that received either no retroaortic infusion or right atrial infusion was resuscitated after 4 minutes of untreated ventricular fibrillation. Each of five animals was successfully resuscitated by retroaortic infusion after 4 minutes of untreated cardiac arrest; one was resuscitated after 6 minutes, and none was resuscitated after 8 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗