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H Yao

Publications and source records attributed to H Yao.

At least 163 records · Page 9Linked to original sources
PubMed1993

Failure of MK-801 to reduce infarct volume in thrombotic middle cerebral artery occlusion in rats.

BACKGROUND AND PURPOSE: We examined the effects of the noncompetitive N-methyl-D-aspartate receptor antagonist MK-801 using a newly developed stroke model of thrombotic distal middle cerebral artery occlusion under conditions of carefully controlled head temperature. METHODS: Male Sprague-Dawley rats were treated with 1 mg/kg of MK-801 or saline before the induction of ischemia. An argon laser-activated dye laser (562 nm) was used to cause thrombotic distal middle cerebral artery occlusion. In experiments 1 and 2, the single laser beam (20 mW) was separated into three beams. Each beam was positioned onto the distal middle cerebral artery at three sites along the vessel. The photosensitizing dye rose bengal (20 mg/kg) was administered intravenously over 2 minutes; the three points were then irradiated for 3 minutes. In experiment 3, higher power of the laser (three separate irradiations using a single beam of 20 mW) was used. The ipsilateral common carotid artery was occluded permanently, and the contralateral carotid artery was occluded for 60 minutes. Head temperature was controlled at 36 degrees C in experiment 1 and not controlled in experiments 2 and 3. Three days after the ischemic insult, brains were perfusion-fixed and infarct volumes were determined. RESULTS: Head temperature was mildly hypothermic (34-35 degrees C before ischemia, with a further decrease of 1-2 degrees C during the initial 60 minutes of ischemia) in experiment 2. However, no differences were observed in head temperature between the MK-801-treated and control groups. Cortical infarct volume in experiment 1 was 89 +/- 29 mm3 (mean +/- SD) in the treated group, which was not different from the control value of 84 +/- 40 mm3. Infarct volumes were smaller (58 +/- 35 mm3 and 54 +/- 14 mm3) in the control groups of experiments 2 and 3, respectively. However, MK-801 also failed to reduce infarct volumes in experiments 2 and 3. CONCLUSIONS: MK-801 is not effective in this stroke model of focal thrombotic infarction under conditions of either controlled (normothermic) or uncontrolled (mildly hypothermic) head temperature.

Animals↗
PubMed1993

Idiopathic cerebral hemorrhage during delivery in normotensive women--case reports.

Two normotensive pregnant women who developed cerebral hemorrhage during delivery are reported. The hematoma was small and subcortical in one and large and putaminal in the other. They had no history of hypertension, cerebrovascular disorders, or eclampsia. Cerebral angiography studied in one case revealed no abnormalities. Idiopathic cerebral hemorrhage during delivery without any evidence of vascular risk factors is discussed.

Adult↗
PubMed1993

The cloning and sequencing of coat protein gene from beet necrotic yellow vein virus.

The beet necrotic yellow vein virus (BNYVV) isolate NM was isolated from sugarbeet infected with rhizomania in Inner Mongolia of China. The cDNA of BNYVV coat protein (CP) gene was amplified from the extracted RNA of BNYVV isolate NM by using the polymerase chain reaction (PCR) and cloned into pGEM-7zf(+). Its complete nucleotide sequence was determined by means of Sanger's dideoxy-mediated chain-termination method. The result shows that CP gene of BNYVV isolate has 567 nucleotides. It shares 98.8% and 96.7% identity with the CP gene of isolate F13 (report in reference [1]) in terms of amino acid and nucleotide sequence, respectively.

Amino Acid Sequence↗
PubMed1993

Electrochemical homogeneous enzyme immunoassay of theophylline in hemolyzed, icteric, and lipemic samples.

We demonstrate here an electrochemical homogeneous enzyme immunoassay for theophylline, which can be performed in hemolyzed, lipemic, and icteric samples. The assay used an unmodified Syva EMIT theophylline kit. One of the enzymatic reaction products, NADH, reacted with 2,6-dichloroindophenol (DCIP) to reduce DCIP to DCIPH2, which was detected electrochemically with flow-injection analysis. The inter- and intraassay coefficients of variation of this manual technique were < 9% at theophylline concentrations of 14 to 34 mg/L. The CVs were 9-15% at low concentrations (6.3 mg/L), which is below the therapeutic range. Analytical recoveries were 91-97% for normal serum and 92-111% for hemolyzed, icteric, or lipemic sera. The measured concentrations (y) were compared with those obtained by the fluorescence polarization immunoassay (x); a scatter plot of the results showed a linear relationship of y = 1.00 x - 0.57 mg/L (r = 0.966, Sy/x = 1.51). This alternative way to measure the serum concentration of theophylline overcomes the shortcomings of spectrophotometric methods, by which it is difficult to measure theophylline in severely hemolyzed, icteric, or lipemic sera.

Bilirubin↗
PubMed1993

[Long-term results of isolated mitral valve replacement using bioprosthesis].

We evaluated late clinical results of 134 hospital survivors, of whom 152 patients underwent isolated mitral valve replacement with bioprosthesis from September, 1976 to July, 1989 for acquired valvular heart diseases. One hundred fifty-two bioprosthesis consisted of Hancock porcine aortic, 44, Carpentier-Edwards porcine aortic, 28 Ionescu-Shiley pericardial 46 and Carpentier-Edwards pericardial 34. The cumulative follow-up period was 1151.0 patient.year (pt.yr). The actuarial survival rate with Kaplan-Meier method was 82.4%, 79.9%, 76.0% at 5, 7 and 10 years respectively. The actuarial event free rate of primary tissue failure was 96.7%, 82.8% and 56.7% at 5, 7 and 10 years respectively. The linealized rate of bioprosthetic valve endocarditis was 0.3%/Pt.yr. Although 104 patients (77.6%) of 134 received postoperative anticoagulant therapy with Warfarin sodium about for one year. Thromboembolic complications occurred at rate of 1.3%/Pt.yr. The bioprosthesis in the mitral position is now used only in the selected patients because of the limited long term durability and necessity of permanent anticoagulant therapy.

Adult↗
PubMed1993

[Surgical treatment of the primary cardiac rhabdomyoma in the neonate--a case report].

A successful surgical treatment of intracardiac rhabdomyoma in a 12-day-old female is reported. The neonate was first noted to have a cardiac murmur and she was diagnosed cardiac tumor by two dimensional echocardiography. It showed multiple cardiac tumors which occupied the right ventricular outflow tract and interventricular septum. Under the routine cardiopulmonary bypass the tumor of the right ventricular outflow tract was removed. Histological examination revealed a rhabdomyoma. Follow-up evaluation 7 years after operation showed normal growth and development of the patient. A repeated two dimensional echocardiogram revealed no sign of recurrence and the left ventricular cavity was not obstructed by the residual tumor in the interventricular septum. We reviewed 10 cases treated surgically in infancy including three neonate in Japan.

Echocardiography↗
PubMed1993

[Clinical use of an expanded polytetrafluoroethylene sheets (GORE-TEX SHEETS) as a pericardial substitute after aorto coronary bypass grafting].

Reoperation after cardiovascular surgical procedures are often accompanied by the possibility of injuring the heart the great vessels, and extracardiac grafts during resternotomy. To reduce the risk associated with resternotomy and to facilitate dissection of intrapericardial adhesion, we have used GORE-TEX SHEET as pericardial substitute since January, 1989. In case GORE-TEX SHEET are implanted in the mediastinum, prolongation of the foreign body reaction, mediastinitis, increasing postoperative hemorrhage should be in mind. In this study, the biocompatibility of GORE-TEX SHEET was examined clinically. The following postoperative indices such as duration of fever, change of the WBC counts, WBC fraction, CRP, mediastinal hemorrhage are evaluated. These results showed no statistical significance between GORE-TEX SHEET group and autologous pericardial group by the randomized study. We recommend use of GORE-TEX SHEET as a pericardial substitute in cases of major cardiovascular operation using median sternotomy.

Aged↗
PubMed1992

Inhibition of ischemia-induced dopamine release by omega-conotoxin, a calcium channel blocker, in the striatum of spontaneously hypertensive rats: in vivo brain dialysis study.

The effect of omega-conotoxin GVIA (CgTX), an N-and L-type voltage-sensitive calcium channel (VSCC) blocker, on the release of dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) in the striatum before and during transient cerebral ischemia in spontaneously hypertensive rats was studied using an in vivo brain dialysis technique. Continuous perfusion of CgTX in the striatum was started 20 min before ischemia and concentrations of dopamine and DOPAC in the dialysate were measured using HPLC with an electro-chemical detector. Before ischemia, both 10 and 100 microM CgTX significantly lowered the concentration of dopamine, to 49% of the basal values. DOPAC concentrations also decreased significantly, by 28 and 17%, respectively. Forebrain ischemia, produced by bilateral carotid artery occlusion, reduced striatal blood flow to less than 6% of the resting value in each group. During 20 min of ischemia, the vehicle group showed a marked increase in dopamine (175 times the basal concentration). In the 10 or 100 microM CgTX perfusion group, in contrast, dopamine release was significantly attenuated, to 38 or 29% of the vehicle group, respectively. DOPAC concentrations decreased during ischemia to 58% of the basal value in the vehicle group and 49% in both CgTX groups. These results indicate that the massive release of striatal dopamine during ischemia depends largely on the influx of extracellular calcium via CgTX-sensitive VSCCs.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1992

CBF and oxygen metabolism in hemodialysis patients: effects of anemia correction with recombinant human EPO.

To investigate the effects of anemia correction with recombinant human erythropoietin (rhEPO) on both cerebral blood flow and oxygen metabolism in hemodialysis (HD) patients, the regional cerebral blood flow (rCBF), oxygen extraction (rOEF), and metabolic rate for oxygen (rCMRO2) were measured by positron emission tomography in five HD patients, and the data were compared with eight nondemented controls who had neither anemia nor uremia. In the HD patients, 1,500 U of rhEPO were administered intravenously three times a week to achieve a 10% increase in hematocrit (Hct) as an absolute value. Before rhEPO administration, the hemispheric rCMRO2 in HD patients was 1.48 +/- 0.09 (SE) ml.min-1.100 ml-1, which was significantly lower than that of 2.18 +/- 0.10 in the controls (P less than 0.01). In contrast, both rCBF and rOEF were significantly greater in the HD patients than the control, being 40 +/- 3 vs. 32 +/- 3 ml.min-1.100 ml-1 for rCBF (P less than 0.02) and 49 +/- 1 vs. 38 +/- 1% for rOEF (P less than 0.001). After treatment with rhEPO, Hct rose significantly from 21 +/- 1 to 31 +/- 1% in HD patients (P less than 0.001). There were significant reductions in both the hemispheric rCBF to 32 +/- 1 ml.min-1.100 ml-1 (P less than 0.01) and rOEF to 42 +/- 1% (P less than 0.01). However, the hemispheric rCMRO2 remained low at 1.58 +/- 0.06 ml.min-1.100 ml-1 even after rhEPO treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Leukoaraiosis and dementia in hypertensive patients.

BACKGROUND AND PURPOSE: Although our previous study demonstrated that dementia of the Binswanger type may be a disconnection dementia caused by leukoaraiosis, some hypertensive patients with marked leukoaraiosis do not develop dementia. The goal of the present study is to elucidate the pathophysiology of nondemented hypertensive patients with leukoaraiosis. METHODS: We performed clinical and neuroradiological studies, including positron emission tomography, in eight hypertensive patients with leukoaraiosis. RESULTS: Four patients were demented, and two among the other four who were not demented at the first examination developed dementia during the follow-up period. Digital subtraction angiography of the cervical and intracranial arteries demonstrated stenotic lesions in only one patient. Cerebral blood flow and oxygen metabolism in patients with dementia were markedly reduced in the white matter (59-67% of control values). In contrast, cerebral blood flow in the white matter of patients without dementia was reduced less markedly (74% of control), oxygen extraction fraction in the white matter was significantly increased (130% of control), and oxygen metabolism remained at almost-normal levels not only in the white matter but also in the cortical area. CONCLUSIONS: Hypertension-caused arteriosclerotic changes of the long penetrating medullary arteries may cause misery perfusion and later ischemic damage in the periventricular white matter. Preserved oxygen metabolism in hypertensive patients with leukoaraiosis may represent the early stage of vascular dementia of the Binswanger type.

Adult↗
PubMed1992

[A case of true aneurysm of the mitral valve associated with torn chordae].

The patient was a 62 year old woman complaining of severe exertional dyspnea. Preoperative echocardiogram demonstrated the abnormal uniform echo of the anterior leaflet of the mitral valve which protruded toward the left atrium in systole as well as in diastole. Severe mitral regurgitation was also detected. The aneurysm of the anterior leaflet of the mitral valve was confirmed during the operation and mitral valve replacement was performed. The postoperative course was uneventful. Pathological examination of the resected aneurysm showed myxomatous degeneration. There were no signs of the inflammatory processes. The aneurysm formation in this case was considered to be due to the myxomatous degenerative changes of the anterior leaflet of the mitral valve. Fifteen cases of true aneurysm of the mitral valve reported in Japan were reviewed.

Chordae Tendineae↗
PubMed1992

[Reconstructive surgery in 59-year-old patient with coarctation of aorta under the monitoring of somatosensory evoked potential and spinal cord perfusion pressure].

Postoperative paraplegia is a relatively rare complication in reconstructive surgery for coarctation of the aorta and the operative treatment is usually performed without any adjuncts. A 59-year-old male patient underwent replacement of descending thoracic aorta with vascular prosthesis under the monitoring of SEP and spinal cord perfusion pressure (SCPP) [pressure difference between mean distal aortic pressure (MDAP) and the cerebrospinal fluid pressure (CSFP)]. During cross-clamping of the aorta, MDAP decreased from 61 to 40 mmHg and CSFP increased from 6 to 15 mmHg, SCPP was 25 mmHg, and the amplitude of the SEP waves rapidly decreased. As the ischemic changes of spinal cord were suspected, the aortic cross-clamping was released. The amplitude of SEP recovered to the preoperative level immediately after de-clamping. In order to prevent spinal cord ischemia, the partial cardio-pulmonary bypass was employed, and SCPP was maintained above 60 mmHg, so that SEP did not show any ischemic changes during cross-clamping of the aorta. The patient did not develop any neurological deficit postoperatively. The monitoring of SEP and SCPP appears to be useful for prevention of postoperative paraplegia in the surgical treatment for coarctation of the aorta.

Aortic Coarctation↗
PubMed1991

Excitatory and inhibitory amino acid changes in ischemic brain regions in spontaneously hypertensive rats.

Excitatory (glutamate, aspartate) or inhibitory amino acids (gamma-aminobutyric acid: GABA, taurine) and glutamine contents were examined in acutely induced cerebral ischemia in spontaneously hypertensive rats. At 20 min ischemia most of these amino acids remained unchanged, but glutamine significantly decreased by 14% in the CA3 hippocampal subfield. At 60 min ischemia glutamate significantly decreased by 14% in the CA3, aspartate by 17-26% in the CA3, cingulate cortex, septum and striatum. In contrast, GABA significantly increased by 48-106% in the cortices (frontal, parietal and cingulate), striatum and nucleus accumbens, but insignificantly in hippocampal subfields. Likewise, taurine increased in the parietal cortex and nucleus accumbens. Glutamine showed heterogeneous changes (increase in the nucleus accumbens and decrease in the CA3). Amino acid levels change during ischemia, but their changes are varied in each area, implying that different reaction of amino acids may explain the selective vulnerability to cerebral ischemia.

Amino Acids↗
PubMed1991

Prevention of postanesthetic shivering with intravenous administration of aspirin.

There have been many reports of postanesthetic shivering (PAS); however, the causes have not been defined clearly, and the reported methods of inhibiting PAS are not always available clinically. In the present study, we assessed the effect of the intravenous administration of aspirin on the prevention of PAS in 62 patients undergoing oral or maxillofacial surgery, anesthetized with enflurane-nitrous oxide. Thirty of the patients were randomly selected, and received intravenous aspirin DL-lysine 900 mg (equivalent to aspirin 495 mg) before the end of surgery. No significant differences were noted in the rectal temperatures between the group given aspirin and the control group. Shivering was observed in 17 of the 32 patients of control group. In contrast, shivering was observed in 5 of the 30 patients who received aspirin. This was a statistically significant difference ( P < 0.01). These data indicate that intravenous administration of aspirin significantly inhibited PAS. The finding suggests that PAS is related to prostaglandin synthesis or to the formation of derivatives of arachidonic acid, since aspirin inhibits both the synthesis of prostaglandins and the formation of derivatives of arachidonic acid.

Clinical Trial↗
PubMed1991

Age-related vulnerability to cerebral ischemia in spontaneously hypertensive rats.

BACKGROUND AND PURPOSE: We sought to determine the effects of aging on regional cerebral blood flow and ischemic brain damage in transient cerebral ischemia in rats. METHODS: Five adult (5-6 months) and five aged (18-22 months) female spontaneously hypertensive rats were subjected to 20 minutes of bilateral carotid occlusion and 60 minutes of recirculation under amobarbital anesthesia (100 mg/kg i.p.). Regional cerebral blood flow in the hippocampus and striatum was measured using the hydrogen clearance method. Nine adult and 14 aged rats were subjected to 20 minutes of bilateral carotid occlusion or were sham-operated under ether anesthesia. Seven days after 20 minutes of cerebral ischemia, the rats' brains were perfusion fixed. Ischemic damage in the hippocampus and striatum was graded (0 [normal] to 3 [majority of neurons damaged]). RESULTS: After 20 minutes of bilateral carotid occlusion, striatal cerebral blood flow decreased to 9.1 +/- 1.5 and 3.9 +/- 2.0 ml/100 g/min in aged and adult rats, respectively, and hippocampal cerebral blood flow decreased to 8.6 +/- 2.4 and 5.7 +/- 2.4 in aged and adult rats, respectively. Although these ischemic cerebral blood flow values were not significantly different between the two age groups, scores for ischemic damage in the hippocampus CA-1 subfield and striatum were significantly higher in aged than in adult rats (p less than 0.05, Kruskal-Wallis' h test with Bonferroni correction). CONCLUSIONS: We conclude that aging may be a primary factor in the development of greater ischemic neuronal damage observed in aged hypertensive rats.

Aging↗