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Biomedical subjects

P Liu

Publications and source records attributed to P Liu.

At least 307 records · Page 17Linked to original sources
PubMed1994

Conductance catheter measurements of left ventricular volume in the intact dog: parallel conductance is independent of left ventricular size.

OBJECTIVE: It has recently been suggested that conductance catheter parallel conductance (alpha Vc) is a function of left ventricular volume. To confirm this, alpha Vc was measured in this study over a wide range of steady state volumes. In addition, conductance derived volumes were compared to those obtained by radionuclide angiography to determine if the conductance catheter can be used to measure absolute left ventricular volume accurately in the intact dog heart. METHODS: Seven dogs were anaesthetised and instrumented with left ventricular conductance and pressure tip catheters, a flow through rho cuvette to continually measure blood resistance, a thermodilution catheter, and a venous catheter for volume infusion/withdrawal. Conductance and angiographic data were acquired at 8(SD 1) variably loaded states. Parallel conductance was measured twice at each state using a saline dilution technique and a new non-linear algorithm that allows variability in the observations of both maximum and minimum conductance volumes. RESULTS: The mean value of alpha Vc was 89.1(18.0) ml (71.8 to 111.3 ml) with a mean within-animal coefficient of variation of 7.3(3.4)%. Multiple linear regression using dummy variables to account for the large interanimal variability did not reveal any relationship between alpha Vc and either maximum or minimum left ventricular volume. Furthermore, no difference was found when alpha Vc values measured at the lowest and highest loading levels in each dog were compared. Linear regression showed good agreement between conductance and radionuclide derived end diastolic volumes (slope = 0.94, R = 0.9, p < 0.001). CONCLUSIONS: While alpha Vc varies between animals, it remains constant within any given animal over a broad range of left ventricular volumes. Thus the conductance catheter can provide reliable absolute left ventricular volume measurements under steady state conditions.

Animals↗
PubMed1994

Indoor factors and IgE levels in children.

The objective of the study was to determine indoor characteristics of households in relation to total serum IgE. In a population-based cross-sectional study, 1096 6-12-year-old children were examined in three East German towns (Eisleben, Hettstedt, and Zerbst). Of the questionnaires, 772 (70.4%) were returned by the parents. Serum IgE of 703 children and urinary cotinine in a random subsample of 224 children were analyzed. Linear regression on log(IgE) adjusted for the main covariates was used to assess indoor risk factors such as room size, and the presence of curtains, carpet, and plants in the child's room. Open-heating facilities indoors, passive smoking, and furniture made of chipboard had the most important effect. A higher urinary cotinine/creatinine ratio was associated with higher total IgE level. Total IGE increased also with the number of persons living in the household, independently of indoor smoking. We conclude that indoor air pollution from smoking and open-heating facilities may increase the IgE levels of children. The role of other factors such as chipboard, which could reflect the emission of formaldehyde, or the number of persons per household, which could reflect viral or helminthic infection, remains to be analyzed.

Air Pollution, Indoor↗
PubMed1994

Photoacoustic ultrasound: pulse production and detection of 0.5% Liposyn.

Theoretical predictions and experimental measurements of photoacoustic pulse production within a 0.5% solution of Liposyn, a highly scattering, optical propagation medium, are reported. A simple model for photoacoustic energetics is developed that predicts photoacoustic signal pressure as a function of depth within a turbid medium following surface irradiation from an infrared source. The model is valid for very short irradiation duration. The model predicts that the acoustic pressure produced at a distance r from the center of a small, highly absorbing sphere of radius R consists of two, opposite polarity pulses, one originating from the near and one from the far side of the sphere. The magnitude of these biphasic pulses is expected to be proportional to the energy fluence (E) incident on the surface of the sphere and to the ratio, R/r. Furthermore, the energy fluence (E) that reaches the sphere is roughly proportional to e-mu effZ, where mu eff is the effective attenuation coefficient of the turbid medium and Z is the depth of the embedded sphere below the irradiated surface. The variation of E with depth within the absorber and biphasic acoustic pulse production have been verified experimentally. Further experiments demonstrate that a small (3-mm diameter), highly absorbing sphere can be detected and localized at a depth of 37.5 mm within a 0.5% solution of Liposyn with a spatial resolution of 1 x 6 mm2, using a biologically safe level of infrared irradiation (lambda = 1064 nm) and a conventional ultrasound transducer (frequency = 2.25 MHz). These results suggest that photoacoustic ultrasound imaging may have application to biologic systems such as the human breast.

Acoustics↗
PubMed1994

Viral infection and the pathogenesis of dilated cardiomyopathy.

Long-term follow-up studies of patients with suspected viral myocarditis reveal progression to dilated cardiomyopathy (DCM) in a significant number of cases. Thus, an underlying viral etiology has been hypothesized in the pathogenesis of ongoing heart disease that leads to DCM. Recent application of molecular biology in clinical diagnosis has strengthened this hypothesis. By use of probe hybridization and polymerase chain reaction, enteroviral RNA has been detected in the myocardium of patients at all stages of the disease process: myocarditis, chronic heart disease, and DCM. Experimental murine models of enterovirus-induced heart disease provide a framework for examining the pathogenic mechanisms. Viral cytotoxicity, immunological responses, viral RNA persistence, and spasm of the coronary microvasculature are all implicated in the ongoing disease process. Abnormal cardiac function and heart failure are attributed to the pathological changes that occur.

Animals↗
PubMed1994

[Seroepidemiologic study on the feasibility of screening for the antibody to HCV by pooling the serum specimens].

The feasibility of screening for the antibody to HCV by pooling 10 serum specimens was studied by utilizing the epidemiologic method of single blind random allocation. We changed only the ratio between the pooled serum specimen volume and the serum specimen diluent volume, with their total volume and single serum specimen volume being as much as the volume required by EIA. Other steps were the same as those of EIA. The result showed that taking single serum specimen as the control group, the sensitivity and specificity of pooled serum specimen were 100% and 97.6%, respectively. The false positive rate was 2.4%, Kappa value was 0.95 (P < 0.05). The analysis of profit found that remarkable social and economic benefit will be obtained when serum pooling method is used. These results demonstrate that pooling 10 serum specimens is feasible to screening the antibody to HCV in blood donors by EIA.

Adolescent↗
PubMed1994

[Successful clinical pregnancy after transfer of frozen-thawed embryos].

A case of successful clinical pregnancy after transfer of frozen-thawed embryos was reported in this paper. The woman is a 45,XO karyotype Turner's syndrome patient with primary amenorrhea, and her husband has azospermia. She was given hormone replacement therapy to achieve adequate endometrial development. The donated embryos from two sources were frozen on April 27 and April 30, 1994 respectively. The transfer was done on May 25, 1994. Urinary beta-hCG became positive 14 days later. On July 8th, an intra-uterine embryonic sac containing an embryonic bud with good primitive heart beats was seen under vaginal B-ultrasound. Blood hCG reached 232,900 IU/L on July 25. The pregnancy is going on smoothly. The methods of freezing and thawing embryos were described.

Adult↗
PubMed1994

[Alterations of oxygen free radicals in rabbit models and its relation to formation of pigment gallstones].

The experimental rabbits were divided into three groups. In the first group the common bile ducts were loosely ligated and contaminated by E. coli (BOI); in the second group the common bile ducts were only loosely ligated (BO); and the third group was the control group (Con). Alterations of oxygen free radicals were studied in all these models. The result showed that alterations of the partial hepatic oxygen free radicals (OFR), the hepatic prostaglandin E2 (PGE2) and the pigment gallstones were similar. There was a positive correlation among them (P < 0.05). In group BOI, these indexes were higher than in group BO. It is suggested that oxygen free radicals are possibly responsible for the formation of pigment gallstones through the pathway from oxygen free radicals to promote the production of prostaglandin E2, glycoprotein and pigment gallstones at last E. coli may aggravate the formation of pigment gallstones by increasing hepatic oxygen free radicals.

Animals↗
PubMed1994

[Surgical treatment of middle lobe carcinoma of the lung].

From February 1965 to April 1993, 88 patients with middle lobe carcinoma of the lung were treated surgically. It constituted 7.7% of the total patients of operated lung cancer in our hospital. Clinical symptoms were mainly fever, cough, bloody-sputum and chest pain. 84 of 88 patients were treated by wedge resection, lobectomy and pneumonectomy. Exploration was preformed in 4 patients. The 1, 3, 5 and 10-year survival rates of the 78 patients followed up were 87.18%, 43.08%, 38.18% and 24.13% respectively. It related to four clinical features of middle lobe cancer of the lung were treated surgically is discussed.

Adenocarcinoma↗
PubMed1994

Beneficial effects of extracellular glutathione against endotoxin-induced liver injury during ischemia and reperfusion.

The potential beneficial effect of hepatocellular glutathione against inflammatory liver damage was investigated in a model of endotoxin-enhanced ischemia-reperfusion injury. Animals were subjected to 20 min of hepatic ischemia, followed by 4 hr of reperfusion. The injection of 0.5 mg/kg Salmonella enteritidis endotoxin potentiated liver injury and the postischemic oxidant stress, as indicated by increased plasma levels of glutathione disulfide. Depletion of hepatic glutathione levels by > 90% with phorone and inhibition of glutathione synthesis with buthionine sulfoximine further increased liver injury in this model, as indicated by enhancement of plasma alanine aminotransferase activities from 2,234 +/- 122 U/L to 4,024 +/- 282 U/L. Continuous infusion of a glutathione (GSH) solution in GSH-depleted animals (22 mumol/kg/hr) attenuated reperfusion injury by 55%. In vitro experiments demonstrated the capability of GSH to react rapidly with reactive oxygen species, such as hydrogen peroxide (H2O2) and hypochlorous acid (HOCl). Only H2O2 oxidized GSH quantitatively to its disulfide; HOCl oxidized GSH to higher oxidation states. These data support the hypothesis that the enhanced release of hepatocellular GSH functions as a defense mechanism against reactive oxygen species generated by inflammatory cells during endotoxemia and reperfusion. This internal defense system of the liver may be of general importance in preventing, or at least limiting, liver damage by reactive oxygen generated in particular by Kupffer cells during their physiological function to remove gut-derived endotoxin and bacteria.

Animals↗
PubMed1994

Lipopolysaccharide-induced cytotoxicity against cultured mouse hepatocytes and the role of nonparenchymal liver cells.

Lipopolysaccharide (LPS) was found to induce significant hepatocytotoxicity against cultured mouse hepatocytes. Degeneration and necrosis of cultured hepatocytes and decrease of hepatocyte viability were prominent. The aspartate transferase level and 3H-TdR release in the medium were significantly increased after treatment, and the degree of these changes paralleled with LPS concentration. Various other parameters showed no significant difference between the hepatocytes cultured alone and those cocultured with nonparenchymal liver cells. However, if the nonparenchymal liver cells were isolated from mice which had been pretreated with D-galactosamine (GalN) not only was the hepatocytotoxicity induced by LPS enhanced, but the cells also showed certain cytotoxicity against cultured hepatocytes even without LPS. These results suggest that nonparenchymal liver cells might promote LPS-induced hepatocyte injury.

Animals↗
PubMed1994

The changes and significance of mast cells in irradiated rat liver.

There has been no report on changes in mast cells in hepatic radiation injury. Because of the interactions between mast cells and fibroblasts and mast cell changes in radiation interstitial pneumonitis, we examined the mast cells in experimental hepatic irradiation. We used 60Co gamma-ray in a single dose of 10, 30, 50, and 60 Gy given to the liver area of male Wistar rats. The liver tissue was examined 0.5, 1, 2, 3, 6, 9, and 12 months after irradiation. The mast cells were quantitatively and qualitatively assessed in liver sections by light and electronmicroscopy. Typical chronic liver fibrosis occurred after 30 Gy. As the lesions progressed in severity, the number of mast cells increased and they became larger 1 to 2 months after irradiation. After 3 to 6 months, this change was very marked and degranulation was noted. Both the number and size of mast cells were increased markedly. The peak intensity in mast cell changes paralleled that of connective tissue proliferation. At 12 months, when the fibrous tissue was rich in collagen, the mast cells decreased in number. Our findings suggest that mast cells participate in the development of radiation hepatic fibrosis.

Animals↗
PubMed1994

[Epidemiological study on risk factors of cervical cancer].

The relationship between cervical cancer and risk factors including virus infection of cervix was studied with methods of molecular and serological epidemiology. DNA extracted from cervical biopsies taken from 57 cases and 51 controls were tested for HPV6/11, HPV16/18 by Dot-blot hybridization and for HSV-2 by PCR. Sera were detected for HCMV-IgM by ELISA. The results and risk factors were analyzed by logistic regression model. The multiple logistic regression model results showed that HPV16/18 infection was an important risk factor, the infection rate was significantly higher in the group of cervical cancer, the OR was 31.96. Other risk factors were the educational level and the number of birth, the OR were 0.57 and 1.85, respectively. The difference of HSV-2 infection of cervix and HCMV-IgM in serum was not significant between the two groups.

Case-Control Studies↗
PubMed1994

[Study on risk factors of 292 pregnant women infected with HCMV].

This paper is to determine the risk factors of reactivation by HCMV during pregnancy for improving child birth and bringing-up. A total of 292 paired sera were collected from mothers and their infants in Shanghai and were tested for IgG and IgM by ELISA. The positive rates of HCMV IgG and IgM were 98.97%, 96.97% and 3.77%, 1.71%, respectively in mothers and infants. The rate of IgM was 1.49% in infants whose mothers' education were above the high school level, whereas it was 4.17% whose mothers' educational degree was lower than that grade, and the relative ratio (RR) was 2.8. The number of previous pregnancies were closely associated with the positive rate of IgM. In infants born to mothers at first pregnancy, the positive rate was 1.96%, whereas in infants born to mothers at third pregnancy it increased to 3.70%, RR was 1.89. In pregnant women who were known to have postmortem or premature deliveries before the positive rate was 9.09%, whereas it was 2.53% in pregnant women at first pregnancy, the RR was 3.59. The rates of their infants were 3.03% and 1.90%, respectively, the RR was 1.59. The frequency of IgM antibody in 292 sera of mothers was correlated with that in their infants. It showed that HCMV might be transmitted from mother to fetus.

Adult↗
PubMed1994

[The effect of Tripterygium wilfordii monomers T4,T7,T15 and Triptolide on rat nuclear protein].

Rat epididymal sperms were collected after 7 weeks of treatment with Tripterygium wilfordii monomers T4,T7,T15 and triptolide. Total nuclear basic protein (TNBP) were extracted from sperm nuclei isolated by sonication. The relative proportions of histones and protamine were determined by scanning microdensitometry following electrophoresis of TNBP in polyacrylamide gels. It was found that the content of TNBP was reduced while the total histone/protamine ratios were increased following treatment, indicating a marked decrease of protamine levels as compared with the control group. These results suggest that the interruption of nuclear protein transition of spermatids induced by T4,T7,T15 and triptolide might lead to infertility.

Animals↗
PubMed1994

[The protective effect of prostaglandin E1 in experimental model of massive live cell necrosis].

The protective effect of PGE1 in mice injected with propionibacterium acnes (P.acnes) and subsequently with a small dose of lipopoly-saccharide-endotoxin (LPS) 7 days later was studied. The results of this study were as follows: (1) When PGE1 was administered one hour before the injection of LPS, the survival rate of mice was significantly higher (90%), than that of a control group (17%). No necrosis was found in the liver. (2) PGE1 suppressed the release of tumor necrosis factor (TNF) and secreted-interleukin-1 (SIL-1) in culture supernatants of P.acnes-elicited kupffer cells and membrane IL-1 (mIL-1) in kupffer cells in a dose-dependent manner in vitro. These results strongly suggest that PGE1 can prevent liver cell necrosis in the animal model and the mechanism of curative effect of PGE1 in massive liver cell necrosis may result from inhibition of the activity of TNF, sIL-1 and mIL-1 in the kupffer cells.

Alprostadil↗
PubMed1994

The 21-aminosteroid tirilazad mesylate protects against endotoxin shock and acute liver failure in rats.

The protective effect of the 21-aminosteroid tirilazad mesylate (U-74006F) was investigated in an experimental model of endotoxin shock and acute liver failure. In male Fischer rats subjected to 20 min of hepatic no-flow ischemia followed by reperfusion and injection of 0.5 mg/kg of Salmonella enteritidis endotoxin, severe hepatic injury developed, as indicated by a histological evaluation and liver enzyme release. Treatment with U-74006F (two bolus doses of 3 mg/kg each; the first dose was injected i.v. 30 min before ischemia and the second dose, at the time of reflow) reduced the hepatic injury by 60% at 4 hr of reperfusion, improved the survival rate from 18% to 55% and decreased the degree of hepatic injury at 48 hr of reperfusion. U-74006F treatment did not affect the extent of complement activation during reperfusion, the Kupffer cell-induced oxidant stress, or tumor necrosis factor-alpha formation in this model. U-74006F did not significantly reduce superoxide formation of Kupffer cells and neutrophils in vitro or in vivo. The substantial neutrophil infiltration in the liver during the pathogenesis was not affected at 4 hr of reperfusion but was attenuated by 70% at 48 hr. It was therefore concluded that, in the sequence of pathophysiological events, U74006F acted at a site distal to inflammatory cell activation and the generation of cytotoxic mediators. The protection against the initial endotoxin-enhanced reperfusion injury in the liver strongly inhibited the progression of the inflammatory response and subsequent liver failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[Observation on the action of extractum semen Persicae on anti-fibrosis of liver].

It was observed that Extractum Semen Persicae acted obviously on hepatic fibrosis induced by CCl4. Through promoting the degradation of collagens type I, II, IV, VI and fibronectin, ESP has proved helpful in markedly reducing the fibrous septa composed of both collagenous and reticular fibers as well as in repairing the structure of hepatic tissues.

Amygdalin↗