Search PubMed⌕ Search

Biomedical subjects

X Xu

Publications and source records attributed to X Xu.

At least 685 records · Page 38Linked to original sources
PubMed1997

Short-term exercise training enhances reflex cholinergic nitric oxide-dependent coronary vasodilation in conscious dogs.

The effects of exercise training on the coronary vasodilation following activation of the Bezold-Jarisch reflex were examined in conscious dogs. Mongrel dogs were chronically instrumented using sterile techniques for measurements of systemic hemodynamics and left circumflex coronary blood flow (CBF). With the heart rate controlled (150 bpm), veratrine (0.5 to 20 micrograms/kg) caused dose-dependent increases in CBF; eg, 5 micrograms/kg of veratrine increased CBF by 61 +/- 6% from 31 +/- 1.3 mL/min (P < .05). After exercise training, the dose-response curve of CBF in response to veratrine was shifted to the left; eg, 5 micrograms/kg of veratrine increased CBF by 101 +/- 12% (P < .05 compared with control) from 34 +/- 2.3 mL/min. The enhanced coronary vasodilation was blunted by nitro-L-arginine (NLA, 35 mg/kg). In anesthetized dogs after exercise training, electrical stimulation of the left vagus nerve caused greater increases in CBF, and NLA inhibited increases in CBF. Acetylcholine, norepinephrine, angiotensin II, and bradykinin caused greater increases in NO2- production in coronary microvessels from exercise-trained dogs compared with those from normal dogs. Our results indicate that the coronary vasodilation following activation of the Bezold-Jarisch reflex is enhanced in conscious dogs after exercise training. Since electrical stimulation of the vagus nerve caused greater coronary vasodilation and since the agonists resulted in greater increases in NO production in coronary microvessels from exercise-trained dogs, the mechanism responsible for the enhanced coronary vasodilation following activation of the Bezold-Jarisch reflex is most likely due to the increased release of NO from the endothelial cells.

Acetylcholine↗
PubMed1997

Association between air pollution and low birth weight: a community-based study.

The relationship between maternal exposure to air pollution during periods of pregnancy (entire and specific periods) and birth weight was investigated in a well-defined cohort. Between 1988 and 1991, all pregnant women living in four residential areas of Beijing were registered and followed from early pregnancy until delivery. Information on individual mothers and infants was collected. Daily air pollution data were obtained independently. The sample for analysis included 74,671 first-parity live births were gestational age 37-44 weeks. Multiple linear regression and logistic regression were used to estimate the effects of air pollution on birth weight and low birth weight (< 2,500 g), adjusting for gestational age, residence, year of birth, maternal age, and infant gender. There was a significant exposure-response relationship between maternal exposures to sulfur dioxide (SO2) and total suspended particles (TSP) during the third trimester of pregnancy and infant birth weight. The adjusted odds ratio for low birth weight was 1.11 (95% CI, 1.06-1.16) for each 100 micrograms/m3 increase in SO2 and 1.10 (95% CI, 1.05-1.14) for each 100 micrograms/m3 increase in TSP. The estimated reduction in birth weight was 7.3 g and 6.9 g for each 100 micrograms/m3 increase in SO2 and in TSP, respectively. The birth weight distribution of the high-exposure group was more skewed toward the left tail (i.e., with higher proportion of births < 2,500 g) than that of the low-exposure group. Although the effects of other unmeasured risk factors cannot be excluded with certainty, our data suggests that TSP and SO2, or a more complex pollution mixture associated with these pollutants, contribute to an excess risk of low birth weight in the Beijing population.

Adult↗
PubMed1997

Impact of different patterns of feed intake during lactation in the primiparous sow on follicular development and oocyte maturation.

The potential contribution of nutritionally induced differences in follicular and oocyte maturity to embryo survival was addressed in pigs. When primiparous, lactating sows are fed to appetite from farrowing to day 21 of lactation and then with feed intake restricted to 50% from day 22 to 28 (restricted), embryo survival is 64% at day 28 of gestation, compared with 85% in sows fed to 50% from farrowing to day 21 and then fed to appetite from day 22 to 28 (refed). In the present study, 32 sows were equally assigned to these two treatments (restricted or refed) but they were slaughtered 38 h before the estimated time of oestrus. The largest 15 follicles per sow were aspirated and follicular fluid recovered for analysis in vitro. Although plasma oestradiol concentration before slaughter and follicular fluid oestradiol concentration at slaughter were not different (P > 0.05), refed sows had more (P < 0.02) large follicles than did restricted sows. Cumulus expansion scores in vitro were not different between treatments, although more (P < 0.03) oocytes from refed sows had matured to metaphase II than those from restricted sows. Similarly, although cumulus expansion of oocyte-cumulus complexes from prepubertal gilts oocytes incubated with follicular fluid obtained from restricted (n = 1227) or refed (n = 1147) sows was not different (P > 0.05), the rate of oocyte nuclear maturation was greater (P < 0.012) after incubation with follicular fluid from refed than with that from restricted sows. Differences in the maturation of the follicle and oocyte in the period before the LH surge may therefore contribute to the treatment effects on embryo survival.

Animals↗
PubMed1997

A dynamic model of the human/clothing/environment-system.

In this paper a dynamic model of the human/ clothing/environment-system is developed. The human body (controlled system) is subdivided into six segments consisting of the head, trunk, arms, hands, legs and feet. Each segment is further divided into the core, muscle, fat, and skin layer. The afferent signal of the controlling system is composed of the weighted temperatures measured by thermal receptors at sites distributed in the body. The difference between this signal and its threshold activates the thermoregulatory actions: vasomotor changes, metabolic heat production and sweat production. The model considers the competition between skin and muscle blood flow during exercise in hot environments because of limited cardiac capacity, as well as cold induced vasodilatation. Additionally a combined model of heat and mass transfer from the skin through clothing to the environment is developed and incorporated into the thermoregulatory model. The human/clothing model can be used to investigate the interaction between the human body, clothing and environment. The model is validated by comparing the simulation with experimental results under different conditions: heat, cold, exercise, clothing and transient phases. It turns out that the simulation is compatible with the experimental results. We conclude that the model can be applied in a broad range of environmental conditions. Application of the model is easy via a user-friendly interface i.e. a WINDOWS-shell.

Afferent Pathways↗
PubMed1997

[Clinical study of bioactive glass ceramics as orbital implants].

One hundred and two patients received a bioactive glass ceramics as an orbital implant of 98 cases 96.1% were successful after operation. Of 4 cases that underwent operation, conjunctiva was torn partly when stitches were taken out of the wound. One out of four had to remove the orbital implant. After a follow-up of 6 months to 2 years, there were no complications. All patients were satisfied with their cosmetic appearance and motility although drilling of the motility hole as a secondary procedure was not peformed.

Adolescent↗
PubMed1997

[Effect of superoxide dismutase on membrane fluidity and functions of lymphocytes in traumatized mice].

Effect of superoxide dismutase (SOD) on membrane fluidity and functions of lymphocytes in traumatized mice was studied. The results showed that in vivo administration of SOD (10,000 U/kg.d, from 0 to 3 days posttrauma) could significantly decrease malondialdehyde (MDA) contents in serum, lymphatic tissues from spleen, thymus, mesenteric lymph nodes and T cells plasmalemma, mitochondria, microsome, restore decreased T lymphocytes and T cells in traumatized mice, elevate membrane fluidity of lymphocytes transformation (TLT), reduce interleukin 2 (IL-2) production, supprssed IL-2 receptor (IL-2R) expression and depress IL-2 mediated lymphocyte proliferation response (IL 2MLPR) after trauma in various degress. It is suggested that SOD may protect lymphocytes post trauma from damage of oxygen free radical, and elevate lymphocytes functions.

Animals↗
PubMed1997

[A study of multimedia computer assistant instruction of forensic autopsy].

A study of software system for forensic autopsy teaching was carried on with multimedia computer and authour tool. This software system can meet the need of morphological instruction by combining the theory of forensic medicine with its practice. It also indicates that the multimedia computer is playing an impotant role in forensic medicine.

Computer-Assisted Instruction↗
PubMed1997

[Matching study of lung function and respiratory symptoms in ex-dust exposure miners].

The lung function tests and respiratory symptom investigations were carried out on 156 pairs of ex-dust exposure miners and control workers according to match designing method. The matching was based on age, height, weight and smoking habit. The result showed that ex-dust exposure miners had higher frequency of abnormal lung function than that of control workers. Compared with control workers, the prevalence of respiratory symptoms and the incidence of chronic bronchitis were higher in ex-dust exposure miners.

Bronchitis↗
PubMed1997

[Systemic manifestations of myasthenia gravis and its putative pathogenesis].

We studied the systemic manifestations of myasthenia gravis and its putative pathogenesis. 644 clinically, pharmacologically and electrophysiologically diagnosed patients with myasthenia gravis (MG) were studied. 33 patients had Graves disease, 5 periodic paralysis, 4 Hashimoto disease, and 4 epilepsy, polymyositis, rheumatoid arthritis and Guillain-Barre syndrome each. 45 patients had positive anti-skeletal-muscle antibodies, 9 positive anti-thyroid antibody, and 3 positive SSA and SSB. 11 MG patients with positive pyramidal signs (MG+PS) had no evidence of multiple sclerosis (MS) or other neurologic diseases. Compared with 12 MG patients without pyramidal signs (MG-PS) and 23 normal controls (NCs), they had not only high levels of IgGcsf and IgG syn, but also increased ratio of AChRAbcsf/AChRAbs (P < 0.05). Four MG patients had epilepsy. Four MG patients had severe memory disorders. Three MG patients had diseases of the peripheral nerves without diabetes mellitus and toxin. SGPT was significantly increased in 22 MG patients than in 9 normal controls (P < 0.05). These systemic manifestations were improved while MG was improved by immunological therapy. MG is a systemic autoimmune disease predominantly involving AChR on the postsynaptic membrane of N-M conjunction.

Adolescent↗
PubMed1997

[Renal subcapsular effusion cured by using greater omentum packed].

The fistula of proximal convoluted tubule which causes the persistent leakage of the glomerular filtrate and brings about renal subcapsular effusion is very seldom seen. There has been no similar report about it. Up to now, there has been no definite diagnosis and treatment for this disease. We made the advantage of the great absorption power of the greater omentum blood vessels networks to make internal drainage. In this way, the glomerular filtrate was reabsorbed and thus the disease was cured.

Drainage↗
PubMed1997

[Combined resection of the pancreas and portal vein replaced by blood vessel prosthesis for pancreatic head carcinoma: report of two cases].

The resectability and prognosis of carcinoma of the pancreatic head are still poor. The higher resectability rate was achieved by combined resection of the pancreas and portal vein. Two patients in whom the portal vein, surrounded but not penetrated by pancreatic carcinoma, was resected and replaced by an expanded Teflon (Gore-Tex) tube (diameter 8 mm). One patient, who survived 32 months without recurrence of disease, had a ultrasonography and CT proved patent graft 6 and 32 months after operation. A second survivor had a patent graft at 20 month. Excision of involved portal vein during pancreatoduodenectomy for carcinoma of the head of the pancreas is a feasible and valid procedure in the absence of metastases. Vein grafting is the best means for portal vein reconstruction. Gore-Tex appears to be suitable prosthesis when the portal vein must be sacrificed.

Adult↗
PubMed1997

[IL-2, IFN-gamma, and TNF-alpha mRNA expression in peripheral blood mononuclear cells in patients with multiple sclerosis].

We determined the cytokine messenger RNA (mRNA) expression patterns of peripheral blood mononuclear cells from 17 patients with multiple sclerosis (MS) and 11 normal controls, by using a quantitative reverse transcription in combination with polymerase reaction (RT/PCR) and Southern blot hybridization method. A significantly higher levels of IL-2, IFN-gamma mRNA in patient with MS compared to normal controls and significantly higher level of expressions of IFN-gamma, TNF-alpha mRNA were detected in active MS patients compared to those with stable desease (P < 0.05). These data further support the central role of some cytokines in the pathophysiology of this autoimmune disease.

Adult↗
PubMed1997

[Cytological study of subretinal fluid].

OBJECTIVES: To determine the cellular components of subretinal fluid and the origin of cells participating in the proliferation in the membranous tissue of proliferative vitreoretinopathy (PVR). METHODS: 35 subretinal fluid samples were studied by cytology using autofluorescent and immunohistochemical assays. RESULTS: There were a large quantity of retinal pigment epithelium (RPE) and small quantity of pigment epithelial cells originated from epithelial cells of ciliary body and iris, there were also various quantities of neuroretinal cells and macrophages. Neither T-lymphocytes nor B-lymphocytes were found in this group of samples. CONCLUSIONS: RPE, pigment epithelial cells, neuroretinal cells and macrophages are in subretinal fluid and may participate in the formation and development of PVR in various degrees.

Humans↗
PubMed1997

[Experimental study of anti-tumour effect of rhTNF alpha on the laryngeal squamous cell carcinoma].

The anti-tumor effect of rhTNF alpha (recombination human tumor necrosis factor) with three different doses on laryngeal squamous cancer was investigated in nude mice. The results indicated that the higher and the middle doses of rhTNF alpha had significant antitumour effect against laryngeal cancer in BALB/C nude mice. The inhibitory rate of tumor growth was 54.4%(P < 0.05). The lower dose of rhTNF alpha also had antitumour effect but the cancer grew again when rhTNF alpha was stopped. Ultrastructural changes showed that the plasma membrane and the nucleus envelope of the tumor cell were destroyed and the number of lysosomes increased, fibroid material could be seen in the cancer capillary.

Animals↗