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Biomedical subjects

H Y Ni

Publications and source records attributed to H Y Ni.

13 recordsLinked to original sources
PubMed2001

[Heat stress-induced HSP70 expression in heart and vessels of simulated weightless rats].

To examine the effect of simulated weightlessness on inducible HSP70 expression in the heart and vessel tissues of rats, a tail-suspension rat model was used to simulate weightlessness. HSP72 mRNA and HSP70 expression in heart and vessel tissues of both simulated weightless and control rats exposed to heat stress (ambient temperature, Ta = 43 degrees C) and recovered at Ta of 25 degrees C for 1 h (CON-H1, SUS-H1) or 2 h (CON-H2, SUS-H2) were analyzed using Northern blot and Western blot. The expression of HSP72 mRNA in the myocardium significantly decreased in SUS-H2, as compared with that of CON-H2 rats. The amount of HSP72 in the myocardium tended to decrease in both SUS-H1 and SUS-H2 groups, as compared with the corresponding control groups, but the differences were not statistically significant. The levels of inducible HSP70 expression in the vessels were related with their anatomical locations, for that the expression of both HSP72 mRNA and HSP72 significantly increased in basilar arteries, whereas it showed a slight decline in femoral arteries. The blunted HSP70 expression in myocardium suggests that simulated weightlessness may induce myocardial changes similar to those in aging. However, the HSP70 expression changes in arteries are in accord with the trend of differential adaptation changes in vessels to simulated weightlessness.

Animals↗
PubMed2001

[Counteraction effect of intermittent -Gx on changes of responsiveness of basilar artery in tail-suspended rats].

OBJECTIVE: To investigate counteracting effects of intermittent -Gx exposure on changes of responsiveness of basilar artery in tall-suspended rats. METHOD: Rats tail-suspended for 3 wk were daily subjected to 1 h 1.5 G or 2.6 G centrifugation, simulating -Gx exposure of various G values. Responses of perfused isolated basilar arterial rings to KCl was examined. RESULT: Maximal isometric contractile response to KCl were significantly enhanced in arterial rings isolated from 3 wk tail-suspended rats as compared with that from simultaneous control rats (P < 0. 05). However, maximal isometric contractile responses to KCl of arterial rings isolated from 3 wk tail-suspended plus daily -Gx exposure rats were no difference as compared with that from simultaneous control rats, and were significantly decreased (P < 0.05) as compared with that from 3 wk tail-suspended rats. CONCLUSION: Daily intermittent -Gx exposure as a countermeasure to prevent the effects of simulated weightless on changes in responsiveness of basilar artery from tail-suspended rats was valid.

Animals↗
PubMed2001

[Locating the impairment of human cognitive function during hypoxia].

Objective. To find the location where the human brain cognitive function impairs under hypoxia. Method. 14 healthy males, aged 18-20 years, performed auditory Oddball test of two different intensities (55 dB, 80 dB) during exposure to 5000 m by breathing low oxygen mixture. EEG and Reaction Time (RT) were recorded. P3, the component of ERP, was extracted from EEG. P3 latency and RT were used as indices of the experiment. Additive Factors Method was used to analyse the result of the experiment. Result. Interaction between hypoxia and stimulus intensity was found for P3 latency and RT. Conclusion. Acute hypoxia influences the preprocessing stage of information processing.

Acoustic Stimulation↗
PubMed2000

[Counteracting effects of intermittent head-up tilt on simulated-weightlessness induced atrophy of anti-gravity muscles].

Objective. To study the efficacy of intermittent + Gz (45 degrees head-up tilt, HUT) exposures in preventing or alleviating atrophic changes in hind limb muscles induced by simulated weightlessness. Method. Male Sprague-Dawley (SD) rats were assigned randomly to one of three groups: simultaneous control (CON), simulated weightlessness (SUS), and SUS plus 6 h/d HUT (SUS + HUT). Muscles examined included soleus (SOL), medial gastrocnemius (correction from grastrocnemius) (MG), lateral gastrocnemius (LG) and extensor digitorum longus (EDL). Sections were treated with an adenosinetriphosphatase (ATPase) stain or alkaline phosphatase stain. The cross-sectional areas (CSA) of fibers, the relative proportion of type I fiber and the ratio of capillaries/fibers (C/F) were measured using Leica image analysis system. Result. Compared with CON, the wet weight of hind limb muscles in SUS were significantly reduced. The changes of wet weight in different groups were various. The C/F ratios of all muscles were significantly reduced. SUS + HUT rats showed significant increases in SOL and MG wet weight, and the relative counter-effects of intermittent HUT were 93.4% and 34.8%, respectively. In SUS + HUT group, the CSA of both type I and II fibers and relative proportion of type I fibers were completely recovered in SOL, and partially recovered in MG, while the counter-effects were much less obvious in the fibers of LG and EDL. However, HUT resulted in a significant recovery of the C/F ratios in all muscles. Conclusion. The present study demonstrated that intermittent HUT is effective in counteracting the atrophy induced by simulated weightlessness. The result that reactivity to HUT varied among different muscles suggests that the intermittent artificial gravity should be complemented with other countermeasures.

Animals↗
PubMed2000

Heat shock protein 70 expression in myocardium is blunted with simulated weightlessness.

Exposure of cardiac cells to a mild thermal or ischaemic stress, sufficient to induce HSP expression, protects them against a subsequent exposure to a more severe ischaemic stress. Over expression of HSPs by transfection of herpes simplex virus vectors in vitro or in transgenic animal in vivo can protect primary cardiac cells from subsequent exposure to severe thermal or hypoxic stress. The increases in myocardial and liver HSP70 accumulation in response to nonexertional heat stress are attenuated with senescence, and hearts from aged animals exhibit an impaired ability to produce the protective HSP. In our previous work, peculiar changes associated with aging, like lipofuscin accumulation and collagen deposition were shown in the myocardial tissue of long-term simulated weightless rats. We therefore designed the present study to examine whether the heat-stress induced HSP70 accumulation in myocardial tissue may decline with simulated weightlessness.

Animals↗
PubMed1999

[Effects of mild and moderate hypoxia on event-related potentials and the comparison of different stimulus paradigms].

OBJECTIVE: To investigate the effects of mild and moderate hypoxia on event-related potentials (ERP), and to compare the sensitivity of different stimulus paradigms to hypoxia. METHODS: Twelve subjects performed visual Oddball and memory set size (MSET) 1 and MSET 3 of Sternberg tasks on the ground and at the simulated altitudes of 2500 m and 4300 m by breathing low oxygen mixtures. P3 latency and amplitude of ERP, reaction time (RT) and response error rate (ER) were recorded. RESULTS: During hypoxia at the altitude of 4300 m, P3 latency significantly delayed, and ER was high when the difficulty of task increased (Sternberg paradigm with MSET 3). In contrast, at the altitude of 2500 m no changes were observed. Sternberg paradigm with MSET 1, in comparison with others, could elicit clearer ERP waves, and P3 latency was slower during hypoxia. CONCLUSION: Hypoxia at the altitude of 4300 m has strong influence on ERP. P3 latency can be used as a sensitive index in evaluating the decrement of brain cognitive capacity during hypoxia. ERP elicited by Sternberg paradigm with MSET 1 was more sensitive to hypoxia.

Adolescent↗
PubMed1994

Trinucleotide repeat polymorphism within the human antithrombin gene (AT3): allele frequency data for three population groups.

The fifth intron of the human antithrombin gene (AT3) of chromosome 1q23 contains a highly polymorphic short tandem repeat based on the trinucleotide repeat [ATT]. Alleles range in size from [ATT]5 to [ATT]18, and can be typed using the polymerase chain reaction. Here we report allele frequency population data for Caucasians, Blacks and Southeast Asians. Statistical analyses demonstrate consistency with Hardy-Weinberg equilibrium for all three databases, and that the allele frequencies of all three population groups are significantly different from each other. This locus reveals 76% to 87% heterozygosity and therefore may be useful for forensic identity testing and paternity determination.

Alleles↗
PubMed1990

Secular change in birthweight among southeast Asian immigrants to the United States.

We analyzed the Washington State births in 1980-1986 to Southeast Asian parents whose birth place was coded as being outside of the US. The mean birthweight increased from 3188 grams in 1980-81 to 3283 grams in 1986, an annual increment of about 18 grams (95% CI = 11, 25 grams). The prevalence of low birthweight (less than 2500 grams) decreased from 7.2 percent in 1980-81 to 5.4 percent in 1986, an annual reduction of 6.4 percent (95% CI = 1.3, 11.2 percent). In an analysis of information ascertained from the birth certificate, the change of paternal occupational status (from student to employed) was associated with 27 percent of the reduction in the prevalence of low birthweight, independent of maternal age, infant sex, and prior gravidity. A similar temporal change of birthweight during the same period of time was not observed among infants of US-born Asian mothers. Among the women who had two consecutive births from 1984 to 1986, the improvement of birthweight for the second birth compared to the first birth was much greater in infants born to the Southeast Asian mothers than that to White mothers. Our study suggests that living in the United States after immigration from their native countries has had a positive impact on the birthweight of infants born to Southeast Asian immigrants.

Adult↗
PubMed1990

Previous abdominal surgery and tubal pregnancy.

To determine the role of previous abdominal surgery in tubal pregnancy risk, we compared 337 women diagnosed with tubal pregnancy during 1981-1986 with 893 population-based controls concerning their medical, reproductive, and sexual histories. After excluding types of abdominal surgery that involve the fallopian tubes directly and after adjusting for age, gravidity, and reference year, we found no increased risk for tubal pregnancy related to previous cesarean delivery (relative risk 0.6, 95% confidence interval 0.3-1.2), ovarian surgery (relative risk 1.2, 95% confidence interval 0.6-2.5), or removal of an unruptured appendix (relative risk 1.2, 95% confidence interval 0.7-2.2). An increased risk was noted for tubal pregnancy associated with previous ruptured appendix (relative risk 1.8, 95% confidence interval 0.6-5.5), but the increase was well within the limits of chance. With the possible exception of ruptured appendix, our study indicates that abdominal surgery that does not directly involve the fallopian tubes has little or no influence on the occurrence of tubal pregnancy.

Abdomen↗
PubMed1988

The endothelial cell and the factor VIII bypassing activity of prothrombin complex concentrate.

Some classical hemophiliacs have a paradoxical hemostatic response to prothrombin complex concentrate (PCC). We hypothesized that vascular endothelial cells (EC) may contribute to this "factor VIII bypassing activity". When PCC were incubated with suspensions or monolayer cultures of EC, they acquired the ability to partially bypass the defect of factor VIII deficient plasma. This factor VIII bypassing activity distributed with EC and not with the supernatant PCC, and was not a general property of intravascular cells. The effect of PCC was even more dramatic on fixed EC monolayers, which became procoagulant after incubation with PCC. The time courses of association and dissociation of the PCC-derived factor VIII bypassing activity of fixed and viable EC monolayers were both rapid. We conclude that EC may provide a privileged site for sequestration of constituents of PCC which express coagulant activity and which bypass the abnormality of factor VIII deficient plasma.

Blood Coagulation Factors↗
PubMed1984

Epstein-Barr virus activation in Raji cells with ether extracts of soil from different areas in China.

Epstein-Barr virus (EBV) inducers were found in soil samples collected from the ground under tung oil trees and other plant species of Euphorbiaceae family growing in southern provinces of China where incidence of an EBV-associated malignancy, nasopharyngeal carcinoma (NPC) is prevalent. In such NPC high risk areas, the positive rate of EBV inducers in soil samples was up to 59.5%. Since many tung oil trees are planted along the roads and rivers of the high risk area, the possible significance of EBV inducers in soil under the trees in the development of malignancy among inhabitants of the area is discussed.

Burkitt Lymphoma↗