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Biomedical subjects

W Gao

Publications and source records attributed to W Gao.

At least 91 records · Page 5Linked to original sources
PubMed2000

Development of an affordable diaphragmatic pump for cardiopulmonary bypass: an in vivo evaluation.

A new diaphragmatic pump (L-Y pump) and its drive unit were developed in our institute. The pump has a priming volume of 80 ml. The pump housing is 72 mm in diameter and 42 mm in height. Its total weight is 139 g. To assess and confirm the function and controllability of this pump, comparative studies of cardiopulmonary bypass (CPB) with L-Y pump (group A) and conventional roller pump (Group B) were performed using dogs. Both pumps provided pump flow of 90 to 100 ml/kg/min. The hemodynamics of both groups were stable and within the normal range. No leakage or thrombus formation was observed in the L-Y pump. All biochemistry data showed no significant differences between the 2 groups. This data demonstrated low plasma-free hemoglobin levels in the L-Y pump group; after 120 min of CPB, mean plasma free hemoglobin levels were 48.7 +/- 8.6 mg/dl in the roller pump group and 21.4 +/- 7.1 mg/dl in the L-Y pump group, and minimal hemolysis was indicated. In conclusion, this L-Y pump and its controller system might be useful for CPB in terms of its low hemolysis and good pump quality. This pump demonstrated easy manipulation, good controllability, and provided a sufficient pulsatile flow. This pump is suitable not only for CPB, but also as a long-term circulatory support system.

Animals↗
PubMed2000

Fluoride release/uptake from newer glass-ionomer cements used with the ART approach.

PURPOSE: To determine the fluoride ion release/uptake of two conventional glass-ionomer cements (GICs) manufactured for use with the ART approach (Fuji IX GP, Ketac-Molar), as compared with that of a resin-modified GIC (Fuji II LC). MATERIALS AND METHODS: 15 specimens of each material were prepared and placed in vials with artificial saliva and stored at 37 degrees C. The solution was replaced weekly for 6 wks, and the fluoride ions released were measured in ppm each week. After 6 wks, the 15 specimens of each material were divided into three equal groups and placed into three fluoride recharging agents (1.23% APF gel, 1.1% neutral NaF and 0.001% CaF2) for 4 min at 23 degrees C. Fluoride ion measurements of the recharged specimens were carried out at 1 day, 2 days, then weekly for another 6 wks. RESULTS: All freshly-mixed specimens showed the highest fluoride ion release after 1 week, then the release rates dropped quickly to become largely stabilized after 3 wks. After one 4-min exposure to APF gel the initial fluoride ion release increased significantly for all materials. The highest rates were during the first day, but then dropped very quickly to again become largely stabilized after usually 3 wks. Exposure to NaF and CaF2 did not usually result in significantly sustained fluoride ion release by any material. The order of release/uptake for all three agents was Fuji II LC > Fuji IX GP > Ketac-Molar. The mechanism of fluoride ion release after the application of different fluoride recharging agents is not clear. It may occur partly by washout of recharge agents that are retained in the pores and cracks of the restorative materials, for APF gel is viscous and difficult to wash off completely with deionized water; by erosion of surfaces by low pH agents, or by the subsequent release of fluoride ions from within the cement matrix.

Acidulated Phosphate Fluoride↗
PubMed2000

[Non-cirrhotic portal hypertension associated with autoimmune disease].

OBJECTIVE: To summarize the cases of non-cirrhotic portal hypertension associated with autoimmune disease, review the literature and introduce the clinical and pathological features of the syndrome. METHODS: Six female patients treated, between 1983 and 1998 had no history of hepatitis. Variceal bleeding occurred in 5 patients. One patient received sclerotherapy and operation was performed in 3 patients for variceal bleeding. Four patients were subjected to liver biopsy. RESULTS: Liver dysfunction of these patients remained normal and variceal bleeding didn't reccur after therapy. Liver biopsy showed nodular regenerative hyperplasia without fibrous septa. CONCLUSIONS: Non-cirrhotic portal hypertension associated with autoimmune disease is a rare syndrome, characterized by significant portal hypertension as well as histological evidence that cirrhosis is absent. Prevention and treatment of variceal bleeding is very important.

Adult↗
PubMed2000

[Modified sternal turnover with pedicle of abdominal rectus muscle for pectus excavatum].

OBJECTIVE: To assess surgical correction for children with pectus excavatum. METHOD: Modified sternal turnover operation with rectus abdominalis pedicle was performed on 20 children with pectus excavatum since 1987. RESULTS: The patients were successfully corrected and no recurrence was seen during 6 to 36 months after operation. Human bone density examination showed same results in some patients before and six months after operation. CONCLUSION: Modified sternal turnover operation has the following advantages: easy to operate; less bleeding; better blood supply to the turned sternum; rapid postoperative recovery; satisfied correction of deformity and no recurrence. It should be widely used clinically.

Child↗
PubMed2000

[Staple in pericardial devascularization of upper GI bleeding due to portal hypertension: application and therapeutic effect].

OBJECTIVE: To investigate the therapeutic effect of staple in pericardial devascularization on upper GI bleeding due to portal hypertension. METHODS: From July, 1997 to July, 2000, 30 portal hypertensive patients were treated by using pericardial devascularization plus partial resection of lower part of the esophagus with staple (CDH25). The eliminating rate of varicose veins of the lower part of the esophagus and the stenosis rate of anastomosis were evaluated. The therapeutic effect of pericardial devascularization without lower part esophageal resection in 28 patient with upper GI bleeding due to portal hypertension was taken as control. RESULTS: All the patients were followed up for 23 months. There was no death due to the operation. All patients in the study group had no upper GI rebleeding during the 23-month follow-up. The rebleeding rate in the control group was 18% (5/28) (P < 0.05 vs. Study group). The varicose veins eliminating rate was 100% in the study group and 53.6% (15/28) in the control group (P < 0.01); the stenosis rate of anastomosis was 6.7% (2/30) in the study group. CONCLUSION: The therapeutic effect of pericardial devascularization could be improved by the use of staple with shorter operative time.

Adult↗
PubMed2000

[Amelioration of nerve growth factor against noise-induced threshold shift: a transmission electron microscope observation].

OBJECTIVE: To study the protective effects of nerve growth factor(NGF) on noise-induced hearing damage in guinea pigs. METHODS: NGF injected Guinea pigs were consecutively exposed to white noise of 115 dB(A) for 6 days continually (45 min.d-1). Auditory thresholds were measured using auditory cortex evoked response to tone bursts in different post-exposure intervals (1 h, 1 d, 2 d, 3 d and 6 d). The ultrastructural changes within hair cells were also observed by a transmission electron microscope(TEM). RESULTS: The auditory threshold shifts in test group A(NGF:1,000 U.kg-1.d-1, i.m.), B(NGF:2,000 U.kg-1.d-1, i.m.) and C(NGF:3,000 U.kg-1.d-1, i.m.) were significantly fewer than that in the control group(Saline: 1 ml.kg-1.d-1, i.m.). Threshold shifts almost recovered in test group B and C 3 days after the exposure; while a threshold shift of (16.43 +/- 6.91) dB was present 6 days after the exposure in the control group. TEM showed that all three rows of the outer hair cells(OHCs) of the basal turn in the control group displayed significant pathological changes. Depolymerization of actin filiaments within stereocilia, swelling of submembraneous cistern and the efferent nerve-ending and slight edema of hair cells were evident. In test group A, the hair cells display slight pathological changes, which are confined in the third row of OHCs in a local position of the basal turn. In group B and C hair cells have nearly normal appearance. CONCLUSION: NGF is able to reduce threshold shift, and promote the recovery of auditory threshold in acoustic trauma. This factor can, to some extent, protect against noise-induced hearing damage.

Animals↗
PubMed2000

[A novel apoptotic related gene--homocysteine-induced gene HCY-2].

OBJECTIVE: To investigate the mechanisms resulting in cardiovascular diseases and birth defect. METHODS: Induced screening and differential display, Northern blot, and immunohistochemistry assay were applied to clone the homocysteine-induced gene HCY-2 and detect the expression of HCY-2 gene respectively. RESULTS: A novel HCY-induced full length cDNA--HCY-2 which encodes 142 amino acids was obtained from vascular smooth muscle cells of rats. Results of the Northern blot and immunohistochemistry assays suggest that it widely expresses in many kinds of tissues such as heart, kidney, brain, liver, and lung. In vitro, we transferred recombinant HCY-2 gene into endothelial cells and found that it could induce apoptosis and DNA injury. In vivo, HCY-2 gene could induce chicken embryo cells apoptosis and embryo malformation. CONCLUSIONS: The results indicated that HCY-2 gene might be a novel apoptosis-inducing gene and might be involved in the pathogenesis of cardiovascular diseases and birth defects induced by hyperhomocysteinemia.

Amino Acid Sequence↗
PubMed2000

[Detection of DNA variation after space flight in Datura innoxia by random amplified polymorphic DNA markers].

OBJECTIVE: To substantiate the effect of space environment on medicinal plants, the seeds of Datura innoxia were set up in retrievable satellites. METHODS: After returning to earth, the DNA variation of different groups was detected by random amplified polymorphic DNA (RAPD) markers. RESULTS: From a pre-screening of 65 primers with 20 oligonucleotide lengths, 15 primers that produced distinct profiles for each DNA sample were selected. In contrast with the earth controlled group, 39 polymorphic bands were produced in weightless group, and its degree of gene polymorphism was 23.1%; 45 polymophic bands were produced in hit group, and its degree of gene polymorphism was 24.4%. The polymorphic bands ranged approximately from 200 to 1990 bp. CONCLUSIONS: These results indicate that weightlessness induce DNA variation to some extents in Datura innoxia, while the compound effect of weightlessness and high energy heavy ions is more notable than the effect of single weightlessness.

Cosmic Radiation↗
PubMed1999

The Trypanosoma cruzi trans-sialidase, through its COOH-terminal tandem repeat, upregulates interleukin 6 secretion in normal human intestinal microvascular endothelial cells and peripheral blood mononuclear cells.

The Trypanosoma cruzi trans-sialidase can sensitize mice to become highly susceptible to T. cruzi invasion, through mechanisms that remain unknown. In pursuing this observation, we found that purified trans-sialidase induces the selective release of biologically active interleukin (IL)-6 in naive human intestinal microvascular endothelial cells (HIMECs), peripheral blood mononuclear cells (PBMCs), and bladder carcinoma cells. The trans-sialidase action was independent of its catalytic activity, as demonstrated with a genetically engineered trans-sialidase mutant, an enzymatically active polypeptide, and cocultures of PBMCs with epimastigotes and trypomastigotes. Instead, the trans-sialidase action was reproduced with a recombinant COOH-terminal tandem repeat and with synthetic peptides modeled on the tandem repeat. Most interesting, HIMECs infected with a trypomastigote population expressing trans-sialidase effectively released IL-6, but did not upon infection with the counterpart trypomastigote population expressing low trans-sialidase levels. IL-6 is a key factor in the regulation and symptom formation of infection caused by several types of viruses, such as HIV and influenza A virus. However, the function of IL-6 in protozoan and other parasitic diseases remains unclear. The unique findings presented here suggest that trans-sialidase is a major inducer of IL-6 secretion in T. cruzi infection, independently of immune cell activation. Such IL-6 secretion might underlie some features of Chagas's disease, such as pyrexia, neuroprotection, and fibrosis, and might result in the undermining of normal acquired immunity against T. cruzi.

Amino Acid Sequence↗
PubMed1999

Superhumps in a Peculiar SU Ursae Majoris-Type Dwarf Nova, ER Ursae Majoris.

We report the photometry of a peculiar SU Ursae Majoris-type dwarf nova, ER Ursae Majoris, for 10 nights during 1998 December and 1999 March, covering a complete rise to the supermaximum and a normal outburst cycle. Superhumps have been found during the rise to the superoutburst. A negative superhump appeared in the December 22 light curve, while the superhump on the next night became positive and had a large-amplitude waveform distinct from that of the previous night. In the normal outbursts we captured, superhumps with larger or smaller amplitudes seem to always exist, although it is not necessarily true for every normal outburst. These results show great resemblance to V1159 Ori. It is more likely that superhumps occasionally exist at essentially all phases of the eruption cycles of ER UMa stars, which should be considered in modeling.

Journal Article↗
PubMed1999

Regulation of learning by EphA receptors: a protein targeting study.

EphA family receptor tyrosine kinases and their ephrin-A ligands are involved in patterning axonal connections during brain development, but until now a role for these molecules in the mature brain had not been elucidated. Here, we show that both the EphA5 receptor and its ephrin-A ligands (2 and 5) are expressed in the adult mouse hippocampus, and the EphA5 protein is present in a phosphorylated form. Because there are no pharmacological agents available for EphA receptors, we designed recombinant immunoadhesins that specifically bind to the receptor binding site of the ephrin-A ligand (antagonist) or the ligand binding site of the EphA receptor (agonist) and thus target EphA function. We demonstrate that intrahippocampal infusion of an EphA antagonist immunoadhesin leads to impaired performance in two behavioral paradigms, T-maze spontaneous alternation and context-dependent fear conditioning, sensitive to hippocampal function, whereas activation of EphA by infusion of an agonist immunoadhesin results in enhanced performance on these tasks. Because the two behavioral tasks have different motivational, perceptual, and motor requirements, we infer the changes were not caused by these performance factors but rather to cognitive alterations. We also find bidirectional changes in gene expression and in electrophysiological measures of synaptic efficacy that correlate with the behavioral results. Thus, EphA receptors and their ligands are implicated as mediators of plasticity in the adult mammalian brain.

Animals↗
PubMed1999

[Lower lead exposure and mental development].

Children were divided into two groups based on their blood lead levels(< 10 or > or = 10 mg/dl). The mental development indexes(PDI, VIQ, PIQ and FIO) were significantly decreased in the high lead group. Simple correlation analysis indicated that there was a negative association between blood lead levels and PDI, VIQ, PIQ and FIO(r = -0.1458, -0.3330, -0.2316 and -0.3133 respectively). But multiple regression analysis showed that the indexes of mental development were not associated with blood lead levels. It is concluded that lead is probably one of the risk factors hindering mental development. But the effect is weak while the blood lead level is not high enough.

Child↗
PubMed1999

Retrograde embolization during saphenous vein graft angioplasty.

Angioplasty of degenerated saphenous vein grafts is not infrequently complicated by distal embolization of atheromatous debris. We describe an uncommon case in which balloon angioplasty of an old vein graft to a second diagonal branch of the left anterior descending coronary artery was followed by distal embolization. However, the embolization occurred in a retrograde fashion distal to the anastomotic site, resulting in occlusion of the upstream first diagonal branch. The reasons for its occurrence are discussed, together with suggestions for its recognition.

Angina Pectoris↗
PubMed1999

Ischemia-reperfusion in the adult mouse heart influence of age.

Age-related changes in the mouse heart after ischemia-reperfusion have not been well characterized. To test the hypothesis that advanced age was associated with increased susceptibility to myocardial injury after ischemia/reperfusion, we studied the hearts of young adult and old mice. In young adult (6-8 months) and aged (22-24 months) C57 BL/6 mice, we performed left anterior descending coronary artery ligation and subjected the hearts to 45 min of ischemia followed by varying periods of reperfusion of 15 min, 1 h, 4 h, and 24 h. We found that there was a significant age difference in the size of the infarct between the young adult and old hearts. There was also greater damage in the old hearts in terms of contraction band necrosis, myofiber tears, DNA fragmentation, and mitochondrial disruption. Thus, the old heart is more susceptible to injury after ischemia-reperfusion. This may be partly due to an age-associated decrease in coronary circulation and collateral flow, as well as other factors.

Aging↗
PubMed1999

Detection of bone marrow micrometastasis.

The detection of metastasizing single tumor cells has so far been difficult. Using a monoclonal antibody (MAb A45-B/B3) recognizing human cytokeratin, we identified immunocytochemically single tumor cells and micrometastases in patients (n = 24) with nonsmall cell lung cancer at the time of surgery of the primary tumor. The cytokeratin-positive cells (1-14/5 x 10(5) cells) in the bone marrow samples of 9 (9/24) patients were found. We also found a garland-like cluster, which consists of seven cancer cells and two closely connected tumor cells from one bone marrow sample. These results indicate that this technique can be used as a early diagnostic technique of bone marrow micrometastasis in the patient with the nonsmall cell lung cancer.

Animals↗
PubMed1999

[Effect of space environment on physiological state in Carthamus tinctorius L].

OBJECTIVE: To substantiate te effect of weightlessness and heavy ion radiation in space environment on medicinal plants. METHODS: The seeds of medicinal plant Carthamus tinctorius were carried aboard a retrievable satellite during 3-18 July, 1994. After returning to earth, the changes of peroxidase and protein were studied by means of electrophoresis. RESULTS: The result showed that the peroxidase activity of each group of seeds which were hit and penetrated by heavy ions rays was higher than that of the ground controlled seeds, but slightly lower than that of the weightless seeds. The protein contents of the weightless seeds and the seeds which is penetrated once and less than once by heavy ions rays were higher than those of the seeds which were kept on earth, but the seeds which were penetrated 2-3 times by heavy ion rays were lower than those of the ground controlled seeds. The peroxidase isozyme and protein patterns of the weightless seeds were similar to those of the ground controlled seeds, but very different between the heavy ion ray penetrated seeds and the earth kept seeds. CONCLUSION: It follows that the weightlessness in space environment has an effect mainly on the physiological condition of plants, but the heavy ion radiation has a stronger effect on the hereditary basis of plants.

China↗