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Biomedical subjects

S Gu

Publications and source records attributed to S Gu.

At least 91 records · Page 5Linked to original sources
PubMed1995

An increase in low aortic pressure increases coronary artery flow and coronary thrombolysis induced by intravenous administration of recombinant tissue plasminogen activator.

PURPOSE: Our study investigated the effects of an increase in aortic pressure, induced by norepinephrine (NE) administration on coronary artery flow in a clotted artery, and rate of coronary thrombolysis induced by intravenous (i.v.) administration of recombinant tissue plasminogen activator (rtPA). METHODS: A canine model of coronary thrombosis, induced by intracoronary injection of radioactive autologous blood clots, was used to test the hypothesis that an increase in aortic blood pressure will increase coronary artery flow and the rate of clot lysis induced by i.v. administration of rtPA. RESULTS: After clot injection, 11 dogs were phlebotomized to decrease systolic aortic pressure to 75 mm Hg. Subsequently, .25 mg/kg of rtPA was administered intravenously over two 15-minute intervals, one during hypotension, and the other after NE infusion had increased systolic blood pressure to 130 mm Hg. In six dogs the hypotensive condition was studied first, and in five dogs the NE-induced normotensive condition was studied first. In all dogs, coronary artery flow and the rate of clot lysis were significantly increased in the normotensive condition. CONCLUSIONS: These results indicate that an increase in a low coronary artery perfusion pressure may enhance coronary artery flow and the rate of thrombolysis.

Animals↗
PubMed1995

Effectiveness of Norplant implants through seven years: a large-scale study in China.

The effectiveness of Norplant implants over a seven year period of continuous use was studied in a multicenter trial. Pregnancy rates were 0.4 per 100 in both year six and year seven. More than 3,600 women completed 6 years and more than 2,400 women completed 7 years. Pregnancy rates increased with weight (p < .05) and decreased with age, but in years 6 and 7 combined, the pregnancy rate neither reached nor exceeded 1 per 100 woman years in any 5 year age group or in any 10 kg weight group.

Adult↗
PubMed1995

Effects of progressive vascular occlusion on slope and intercept of the pulmonary artery pressure-flow relationship.

Pulmonary hemodynamics may be described by mean pulmonary arterial pressure (PAP)-cardiac output (CO) plots. The slope of the PAP-CO relationship may define the incremental resistance (IR), and the extrapolated pressure intercept (P(I)), the effective outflow pressure. The authors investigated the effects of progressive pulmonary vascular occlusion on the IR and P(I) of the PAP-CO plot. Nine experimental and nine time control dogs were studied. In the former group, PAP-CO plots were obtained in three conditions: (1) Baseline, (2) following occlusion of the right pulmonary artery, and (3) following occlusion of the right pulmonary artery and blood flow to the left upper lobe. Following progressive occlusion, there was a corresponding increase in the IR of the PAP-CO plot, from 1.95 to 3.62 to 5.16 mmHg.1-1.min (all P < 0.05). In contrast to the increase in IR, P(I) remained constant. Over the same interval, there were no changes in IR or P(I) in the time control group. These findings indicate that changes in the slope of the PAP-CO plot correspond to changes in the number of parallel vascular units.

Animals↗
PubMed1995

Intravenous administration of recombinant tissue plasminogen activator. Optimizing the rate of coronary thrombolysis.

Although many studies have confirmed the efficacy of thrombolytic therapy in treatment of acute myocardial infarction, few studies have been designed to determine which dose regimen optimizes the rate of coronary thrombolysis. This study was designed to compare the efficacy of coronary thrombolysis obtained with intravenous administration of three dose regimens of recombinant tissue plasminogen activator (rtPA). The same total dose was administered as a bolus, over 30 min, or over 90 min. A canine model was employed. Coronary thrombosis was induced by injection of radioactive blood clot through a catheter placed in the left anterior descending coronary artery. Subsequently, 18 dogs were randomized into 3 groups of 6 dogs each. In group 1 dogs, 0.5 mg/kg of rtPA was administered intravenously as a bolus; in the group 2 dogs, rtPA was administered intravenously over 30 min (rtPA30); in the group 3 dogs, the drug was administered over 90 min (rtPA90). Coronary thrombolysis was assessed with a gamma camera. While at 100 min, the extent of clot lysis was similar between groups, 15 and 30 min after the start of rtPA administration, coronary thrombolysis was significantly less in the rtPA90 group. These results indicate that for a given total dose of rtPA, the rate of intravenous administration may significantly affect the rate of coronary thrombolysis.

Animals↗
PubMed1995

Old-age support system and policy reform in China.

"With the on-going economic transition from the central planned system to a market-oriented system, the population aging process in China is also accelerating, and the support system for the elderly becomes an important issue demanding attention. With data from Chinese national statistics and a regional probability sampling survey in Wuhan Area, two supporting systems for the aged in China are examined in this paper. After a briefing of the population aging process in China, a detailed discussion of the two supporting systems, i.e. the formal and the informal support systems for the aged, including arrangement, operation and funding mechanisms of the systems, is made in terms of policy reform. Then follows an international comparison to highlight features and problems of the Chinese systems. Finally, solutions are proposed for the restructuring of China's pension systems."

Age Distribution↗
PubMed1995

[Study on the optimums for Pseudomonas maltophilia HCG receptor expression].

According to the design of orthogonal experiment, the optimums for expression of Pseudomonas maltophilia with HCG receptor were studied by radioassay. The results showed that the optimums influencing the specific binding percentage of Pseudomonas maltophilia were the cultures of No. 3 solid medium added with 0.5% galactose and incubated at a temperature of 37 C for 72 hours. Under these conditions, the binding percentage of Pseudomonas maltophilia to HCG was higher than those under other conditions.

Pseudomonas↗
PubMed1995

[Chemical compositions of Podocarpus imbricatus].

Twelve components were isolated from Podocar pus imbricatus, of which ten were identified as imbricatafiavone A (1), imbricataflavone B (2), robustaflavone (3), robustaflavone-7"-methyl ether (4), podocarpusflavone A (5), sandaracopimaric acid (6), beta-sitosterol (7), p-hydroxybenzoic acid (8), n-C34H69OH (9) and 10-nonacosanone (10). 4, 5, 8, 9 and 10 are obtained from the species for the first time.

Biflavonoids↗
PubMed1994

Intraaortic balloon counterpulsation enhances coronary thrombolysis induced by intravenous administration of a thrombolytic agent.

OBJECTIVES: This study was designed to test the hypothesis that in the presence of moderate hypotension, intraaortic balloon counterpulsation would enhance coronary thrombolysis induced by intravenous administration of recombinant tissue-type plasminogen activator (rt-PA). BACKGROUND: Although many studies have confirmed the efficacy of thrombolytic therapy in acute myocardial infarction, few have systematically investigated the effects of alterations in aortic pressure on coronary thrombolysis, and none have previously investigated the effects of intraaortic balloon counterpulsation on thrombolysis. METHODS: The effects of intraaortic balloon counterpulsation on aortic pressure, coronary blood flow and coronary thrombolysis were studied in a canine model. Coronary thrombosis was induced in eight dogs by injection of radioactive blood clot through a catheter placed in the left anterior descending coronary artery. Subsequently, dogs underwent phlebotomy to decrease systolic aortic pressure to approximately 90 mm Hg. After phlebotomy, during a 15-min interval of intravenous administration of rt-PA, coronary thrombolysis and coronary flow were determined during and in the absence of counterpulsation. RESULTS: Intraaortic balloon counterpulsation significantly increased aortic diastolic pressure. Corresponding to the increase in pressure, intraaortic balloon counterpulsation significantly increased the rate of rt-PA-induced coronary thrombolysis. Although not statistically significant, peak diastolic coronary flow tended to increase with counterpulsation. CONCLUSIONS: These results indicate that in the presence of moderate systemic hypotension, intraaortic balloon counterpulsation enhances the rate of rt-PA-induced coronary thrombolysis.

Animals↗
PubMed1994

A five-year evaluation of NORPLANT II implants in China.

A five-year study of NORPLANT II rod implants was undertaken in four large cities and metropolitan areas in eastern China. Designed to test the safety, efficacy and acceptability of these implants, the study involved 1,208 women and was conducted concurrently with a similar study of NORPLANT capsule implants. At the end of five years, the gross pregnancy rate was 0.65 per 100, and the continuation rate was 65.3 per 100. Both these values were similar to and not statistically different from the rates of the capsule implant users. In 4,828 woman-years of use, there were few severe adverse events reported. Users and providers found the method to be an acceptable long-term contraceptive method of great reliability.

Adult↗
PubMed1994

Effect of rate of administration of recombinant tissue plasminogen activator on efficacy of coronary thrombolysis.

The authors employed a canine model of coronary thrombosis, induced by injection of radioactive blood clot, via a catheter placed in the left anterior descending (LAD) coronary artery, to compare effects of different rates of administration of recombinant tissue plasminogen activator (rtPA) on efficacy of coronary thrombolysis. In one group of dogs 0.75 mg/kg of rtPA was administered via the catheter placed in the LAD coronary artery over fifteen minutes. In a second group of dogs the same dose of rtPA was administered over forty-five minutes. Compared with the group in which the drug was administered over forty-five minutes, by thirty and forty-five minutes after onset of treatment, the extent of coronary thrombolysis was significantly greater (P < 0.05) in the group who received the drug over fifteen minutes. These results demonstrate that the rate of intracoronary administration of rtPA may significantly affect thrombolytic efficacy.

Animals↗
PubMed1993

Mesonephric contribution to testis differentiation in the fetal mouse.

Testes from 11.5-day-old mouse embryos, with and without attached mesonephroi, were cultured for 7 days. Isolated testes failed to develop well-differentiated testis cords: however, when cultured attached to a mesonephros from either a male or a female donor embryo, testes developed cords that were normal in appearance. Testes cultured next to a mesonephric region but separated from it by a permeable filter, did not develop normal cords, nor did testes grafted to fragments of embryonic limb or heart. When testes were grafted to mesonephric regions from mice carrying a transgenic marker, the marker was found in some of the peritubular myoid cells and other interstitial cells of the testis, but not in the Sertoli cells or the germ cells. We conclude that after 11.5 days post coitum, cells can migrate from the mesonephric region into the differentiating testis and can contribute to the interstitial cell population, and that this contribution is necessary for the establishment of normal cord structure. The germ cells in all cultured testes, whether or not differentiated cords were present, were T1 prospermatogonia: no meiotic germ cells were seen.

Animals↗
PubMed1993

p53 gene mutations in Chinese human testicular seminoma.

Genomic deoxyribonucleic acid from 17 primary human testicular seminomas was screened for the presence of mutations in exons 5 to 8 of gene p53, using the single strand conformation polymorphism assay, followed by direct deoxyribonucleic acid sequencing. The p53 mutations in 1 allele leading to an amino acid change but a normal (wild-type) sequence in the remaining allele were identified in 4 of 17 seminomas (23.5%). Sites of mutations were in exon 5 (codon 141), exon 7 (codon 238, codon 258) and exon 8 (codon 270). The present study suggested that mutation of the p53 gene is involved in the development of human testicular seminoma as in the case of several other types of human cancers.

Base Sequence↗
PubMed1992

Marked systemic hypotension depresses coronary thrombolysis induced by intracoronary administration of recombinant tissue-type plasminogen activator.

OBJECTIVES: This study was designed to test the hypothesis that the level of aortic blood pressure affects the rate and extent of coronary thrombolysis induced by intracoronary administration of recombinant tissue-type plasminogen activator (rt-PA). BACKGROUND: Although many studies have confirmed the efficacy of thrombolytic therapy in the treatment of acute myocardial infarction, the effects of altered blood pressure on coronary thrombolysis have not been studied. Because the aortic pressure represents the coronary artery inflow pressure, first principles predict that changes in blood pressure will affect the delivery of the thrombolytic agent and thus affect thrombolysis. METHODS: The effects of large changes in blood pressure on coronary thrombolysis were studied in a canine model. Coronary thrombosis was induced by injection of radioactive blood clot through a catheter placed in the left anterior descending coronary artery. Subsequently, 24 dogs were classified into three groups of 8 dogs each: Group 1 dogs underwent phlebotomy to adjust systolic blood pressure to 130 mm Hg; Group 2 dogs underwent phlebotomy to decrease systolic blood pressure to 75 mm Hg. Dogs in Group 3 also underwent phlebotomy to achieve a systolic blood pressure of 75 mm Hg and then received norepinephrine to increase this pressure to 130 mm Hg. After adjustment in blood pressure, all dogs received an infusion of rt-PA (0.25 mg/kg body weight) over 30 min through the left anterior descending artery catheter. In a fourth group of six dogs, the effect of altered blood pressure on the rate of coronary thrombolysis was assessed. RESULTS: In dogs in Groups 1 and 3, the rate and extent of coronary thrombolysis were significantly increased compared with values in Group 2. In each of the six Group 4 dogs the rate of coronary thrombolysis increased when norepinephrine increased systolic blood pressure from 75 to 130 mm Hg. CONCLUSIONS: These results indicate that a moderate increase in coronary inflow pressure increases the rate and extent of coronary thrombolysis compared with values during marked systemic hypotension.

Animals↗
PubMed1992

Pulmonary vascular pressure-flow characteristics. Effects of dopamine before and after pulmonary embolism.

We compared the general hemodynamic effects of dopamine and dobutamine in dogs with acute pulmonary hypertension complicated by a decrease in cardiac output (CO). The pulmonary hypertension was induced by injection of autologous blood clot. Emboli markedly increased mean pulmonary artery pressure (Ppa) and decreased CO (both p < 0.001). Both dopamine and dobutamine increased CO 50% (p < 0.05) and decreased pulmonary vascular resistance (PVR) (p < 0.05), calculated as (PAP - left ventricular end diastolic pressure)/CO. Mean PVR (mm Hg/L/min) decreased from 16.1 to 12.4 with dopamine and from 16. to 11.9 with dobutamine, both p < 0.05. Ventricular filling pressures were not affected. In another 12 dogs we investigated the effects of both drugs on pulmonary pressure-flow (P-Q) characteristics. P-Q characteristics were determined in dogs with normal Ppa values and in those with embolic pulmonary hypertension. The slope of the P-Q relationship defines the incremental vascular resistance and the extrapolated pressure intercept, the effective vascular outflow pressure. All P-Q relationships were described well by a linear equation. Despite significant systemic effects in both groups and despite a decrease in PVR with both drugs in embolized dogs, neither drug significantly affected pulmonary P-Q characteristics. The discrepancy between PVR and incremental resistance is explained by an incorrect assumption in PVR that the left ventricular filling pressure is the effective vascular outflow pressure. We conclude that both before and after the induction of pulmonary hypertension, both dopamine and dobutamine improve CO without affecting pulmonary vascular tone.

Animals↗
PubMed1992

Coronary thrombolysis. Comparative effects of intracoronary administration of recombinant tissue plasminogen activator and urokinase.

We employed a canine model of coronary thrombosis, induced by injection of radioactive blood clot, via a catheter placed in the left anterior descending coronary artery, to compare effects of intracoronary administration of recombinant tissue plasminogen activator (rtPA) and urokinase (UK) on rate and extent of coronary thrombolysis. Two doses of UK, 15,000 U/kg (UK15) and 30,000 U/kg (UK30) and two doses of rtPA, 0.25 mg/kg (rtPA.25) and 0.75 mg/kg (rtPA.75) were given. Drugs were infused over 45 min. Compared with the other regimens, rate and extent of coronary thrombolysis were significantly increased with rtPA.75. Also, despite a much higher dose of UK, coronary thrombolysis was similar with UK30 and rtPA.25. Compared with UK15, rate and extent of coronary thrombolysis were increased with rtPA.25. These results indicate that intracoronary administration of rtPA is superior to intracoronary UK in inducing thrombolysis.

Animals↗
PubMed1992

Social support among the aged in Wuhan, China.

"This study provides information on supportive social relations in a sample of 2,762 elderly people in Wuhan, China. The elderly concerned were found to be actively engaged in exchanges of social support with their families and kin. They not only receive assistance but also provide a substantial amount of help to others. These supportive ties were highly positive and satisfactory to the great majority of the respondents. Only moderate correlations were found among various dimensions of social support. These results underscore the multi-dimensional nature of social support and suggest that caution needs to be exercised in extrapolating interpersonal exchanges from social embeddedness."

Adult↗