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Biomedical subjects

Y J Yang

Publications and source records attributed to Y J Yang.

At least 73 records · Page 4Linked to original sources
PubMed1996

The value of Tc-99m MIBI SPECT during isosorbide dinitrate infusion in assessment of viable myocardium in patients with myocardial infarction.

Tc-99m MIBI myocardial SPECT has shown promise for evaluation of coronary artery disease. But its role in predicting myocardial viability is still under investigation. The purpose of this study was to evaluate the value of Tc-99m MIBI myocardial SPECT during isosorbide dinitrate (ISDN) infusion in the assessment of myocardial viability. Thirty-seven patients with previous myocardial infarction (the infarct age ranged from < or = 30 days to 900 days) were studied, of them 13 patients had Tc-99m MIBI studies before and after coronary artery bypass grafting (CABG). The results showed that out of 134 segments with hypoperfusion at resting SPECT, 56 segments (41.8%) had an increase in Tc-99m MIBI uptake during ISDN infusion. Among them, 17 segments (30.4%) were normalized, 6 segments (10.7%) were significantly improved and 33 segments (58.9%) were improved. The degree of improvement in perfusion was related to the age of the myocardial infarction. In 13 patients with CABG, of 31 segments with improvement in perfusion post CABG, 25 segments (80.6%) showed perfusion improvement during ISDN infusion, and of 28 segments with improved wall motion post CABG, 23 segments (82.1%) showed improvement in perfusion during ISDN infusion. Tc-99m MIBI SPECT during ISDN infusion may therefore be a useful approach for assessing myocardial viability.

Adult↗
PubMed1996

Chronic elemental mercury intoxication: neuropsychological follow-up case study.

In initial and follow-up investigations of neuropsychological function in a patient with elemental mercury intoxication, his scores were compared with those of a group of normal control subjects matched for sex, age and education. Each subject received a comprehensive neuropsychological examination including a personality inventory. On the initial examination the results indicated that the patient had a significant depression of performance intellectual functioning, impairments of attention, non-verbal short-term memory and visual judgement of angles and directions, psychomotor retardation and personality changes including depression, anxiety, desire to be alone, lack of interest and sensitivity to physical problems. Such an impairment picture is compatible with the previous observations of individuals with chronic exposure to elemental, organic or inorganic mercury. The follow-up study was undertaken about 1.5 years later. The results show that the patient's cognitive and personality functions were fully recovered. Our findings thus suggest a reversibility of impaired neuropsychological function in persons with elemental mercury poisoning if a prompt removal from the toxic environment is accomplished, together with proper medical treatment.

Adult↗
PubMed1996

Incidence of post-transfusion hepatitis in Taiwan before and after introduction of anti-HCV testing.

The effectiveness of second-generation anti-hepatitis C virus antibody (anti-HCV) screening of blood donations for the prevention of non-A, non-B post-transfusion hepatitis (NANB PTH) was assessed. A prospective study of 192 transfusion recipients was performed to compare the incidence of NANB PTH after the introduction of the second-generation anti-HCV test with the incidence before its introduction. We used a polymerase chain reaction to detect HCV-RNA and HBV-DNA in the sera of patients with NANB PTH. The incidence of acute post-transfusion hepatitis C was 11% (8 of 71) before the screening for anti-HCV as compared with 2.5% (3 of 121) after the screening (p < 0.05). Viremia was detected within the first five weeks of infection in 10 patients with acute post-transfusion hepatitis C. However, there was no significant difference in the incidence of non-A, non-B, non-C (NANBNC) PTH before screening (3 of 71, 4.2%) compared with after screening (3 of 121, 2.5%). Usually, NANBNC PTH was not clinically important. Anti-HCV screening of blood donors significantly reduces the incidence of post-transfusion hepatitis C, but not the incidence of NANBNC PTH.

Adolescent↗
PubMed1996

Papillary cystic tumor of the pancreas in children.

Papillary cystic tumor of the pancreas, so-called Frantz tumor, is a very rare tumor in children. Only 157 cases had been reported since 1959. The clinical manifestations of this disease are usually a slowly growing abdominal mass with or without abdominal pain. It occurs predominantly in young females, and its pathogenesis is still unknown. Surgical resection is usually curative, and its prognosis is excellent. Four adolescent girls with acute or chronic abdominal pain were found to have papillary cystic tumor of the pancreas at our hospital in the past 4 years. They all have a variable clinical presentation. Papillary cystic tumor of the pancreas should therefore be considered one of the differential diagnoses of abdominal pain or abdominal mass in adolescent girls.

Abdominal Pain↗
PubMed1996

Role of endothelial cell mitosis in transendothelial transport of low density lipoprotein in hypercholesterolemic and normal rabbits.

BACKGROUND: Atherosclerosis is characterized by focal areas of lipid accumulation and intimal smooth muscle cell proliferation in large arteries. It has been suggested that the permeability of arterial endothelium to lipid is an important factor in the initiation and progression of atherosclerosis. The mechanism by which macromolecules such as low density lipoprotein (LDL) enter the arterial wall, however, is still not completely understood. Our previous studies have demonstrated that there is close association of endothelial cell turnover with transendothelial macromolecular transport in normal rat aorta. Because hypercholesterolemia has been well documented as one of the major risk factors for atherosclerosis, we explore the relationship between endothelial cell mitosis and transendothelial transport of LDL in hypercholesterolemic rabbits. METHODS: The present study is designed to perform on thoracic aortae from 30 male New Zealand white rabbits fed with either 1% cholesterol-enriched diet (HC group; n = 15) or normal diet (NC group; n = 15). The concentrations of serum cholesterol and triglycerides from two groups were measured by enzymatic procedures using commercial kits. The aortae of hypercholesterolemic and normocholesterolemic rabbits underwent perfusion-fixation 10 min following the intravenous injection of low density lipoprotein conjugated with Lucifer yellow (LY-LDL) for fluorescence microscopy. En face preparations of the thoracic aortae stained with hematoxylin allowed the identification of ECs in mitosis. The relationship between LY-LDL leakage and endothelial cell mitosis was determined. RESULTS: Although endothelial cell mitosis is infrequent (NC: 0.0022 +/- 0.0007%; HC: 0.0004 +/- 0.0001%) in the thoracic aorta of New Zealand white rabbits, 68.2 +/- 8.4% (NC) or 74.3 +/- 9.0% (HC) of dividing cells in the M phase were associated with LYLDL leakage. These dividing cells accounted for 65.0 +/- 9.2% (NC) or 64.4 +/- 11.3% (HC) of all LY-LDL leaky spots. CONCLUSIONS: Thus, this study not only confirmed the close association of EC mitosis with macromolecular permeability in normal group, but also demonstrated that the same relationship existed in hypercholesterolemic rabbits. These observations lend support to the theory that transiently open junctions surrounding the endothelial cells undergoing cell turnover provide pathways through which LDL enters the subendothelial space, resulting in lipid accumulation and atherosclerosis.

Animals↗
PubMed1995

Effect of injury on the bi-affinity alpha 1-adrenoreceptor binding in rat brain in vivo.

Focal freezing lesions in rats cause a widespread decrease of cortical glucose utilization in the lesioned hemisphere, probably as a reflection of depressed cortical activity. The noradrenergic neurotransmitter system was implicated in these alterations when it was demonstrated that prazosin, a specific norepinephrine (NE) antagonist at alpha 1-adrenergic receptors, prevented their development. In normal rat brain, specific binding of [125I]HEAT [(+/-)2-(3-[125I]iodo-4-hydroxyphenyl)-ethyl-aminomethyl-tetralone], another selective alpha 1-adrenoreceptor ligand, was demonstrated in vivo at sites consistent with the alpha 1A- and alpha 1B-adrenoreceptor subtypes. In the present study, the effect of a freezing lesion on specific binding of [125I]HEAT in rat brain in vivo was determined three days after traumatization when cortical glucose use suggested the greatest degree of functional depression. The steady-state volumes of distribution of [125I]HEAT three days after injury were significantly increased in all the cortical areas of the lesioned hemisphere, but not in the subcortical structures. Injury did not modify the binding affinities for HEAT. However, a statistically significant increase in the number of low-affinity binding sites for this ligand was demonstrated in all cortical areas of the lesioned hemisphere, but not in subcortical structures. The traumatization did not modify Bmax estimates for the high-affinity binding of HEAT. The results support the hypothesis that changes in the noradrenergic system are of functional importance in brain injury and that at least some effects of injury are mediated by alpha 1B-adrenergic receptors.

Animals↗
PubMed1995

Tetralogy of Fallot with an additional muscular inlet type ventricular septal defect--repair with split patch technique.

An 8-year-old girl with tetralogy of Fallot (TF) and double ventricular septal defects (VSDs) was reported. The additional VSD was a muscular inlet type. A split patch technique was used to cover both VSDs during the total correction. Follow-up echocardiogram demonstrated no residual shunt nor significant tricuspid valve regurgitation. The patient is doing well 2 years after operation.

Child↗
PubMed1995

Schwann cell properties: 3. C-fos expression, bFGF production, phagocytosis and proliferation during Wallerian degeneration.

The role of Schwann cells (SC) during Wallerian degeneration has been controversial. The consensus opinion is that monocytes/macrophages are mainly responsible for myelin removal although SC were shown to phagocytose myelin in vitro and in vivo. In the present study, we correlate proto-oncogene expression with phenotypic changes in SC during Wallerian degeneration using immunohistochemistry and electron microscopy. The proliferative cells are labeled with proliferative cell nuclear antigen (PCNA), and macrophages are labeled with ED1 macrophage marker. We demonstrate c-fos expression in SC at the onset of axon disintegration 12 hours post-axotomy followed by expression of ED1, basic fibroblast growth factor (bFGF) and PCNA after 1 day. The myelin sheath fragments at the nodal region and forms ellipsoids. Schwann cells move to internodes and undergo nuclear and cytoplasmic hypertrophy; they phagocytose myelin ellipsoids with thick vimentin-rich processes and undergo mitosis. Resident macrophages express c-fos and phagocytose myelin debris sequestered into endoneurium by SC after 3 days, but they do not enter the tube until the fifth day. We believe that SC are induced by signals from injured axons to express c-fos which activates downstream genes that lead to the acquisition of phagocytic and proliferative activities. Myelin debris processed by SC may act as an inducer and a chemoattractant for resident macrophages. Cytokines produced by macrophages may stimulate SC proliferation and production of neurotrophic factors.

Animals↗
PubMed1995

Modified Senning procedures for simple transposition of the great arteries.

From December 1990 to July 1994, 10 infants with simple transposition of the great arteries (TGA) underwent the Senning procedure at National Cheng Kung University Medical College. Their ages ranged from 1 to 8 months (mean, 4.8 +/- 2 months), and their body weight ranged from 3.5 to 7.5 kg (mean, 5.7 +/- 1.2 kg). Four infants were treated with the conventional method by covering the sinoatrial (SA) node with the anterior right atrial flap (group 1). The other six patients had modified procedures, having the suture line across the caval vein, caudal to the SA node (group 2). Three of the group 1 patients experienced junctional rhythm temporarily, another had SA node dysfunction for 1 week postoperatively. In group 2, all patients were in sinus rhythm except one, who returned to sinus rhythm on the second postoperative day. There was one (10%) surgical mortality, a patient in group 1, and one (10%) late mortality, in group 2. The clinical follow-up interval was 6 to 46 months (mean, 28.8 mo). All survivors were in sinus rhythm, and echocardiographic studies demonstrated no difference between the two groups as to conduit obstruction or degree of tricuspid valve regurgitation. In conclusion, in situations that require atrial switch for the correction of TGA, a suture line across the caval vein, caudal to the SA node, may be a useful modification to prevent arrhythmias.

Cardiac Surgical Procedures↗
PubMed1994

Variation in mitochondrial DNA and population structure of the Taipei treefrog Rhacophorus taipeianus in Taiwan.

Mitochondrial DNA (mtDNA) from 40 samples of the Taipei treefrog Rhacophorus taipeianus collected from seven populations in Taiwan were sequenced to document the DNA sequence variation in anuran mtDNA and to elucidate the phylogeographic population structure in the Taipei treefrog. Sequences of 722-764 bases in length, including a 108-bp segment of the cytochrome b gene and a 614-656-bp D-loop segment, were obtained by direct sequencing using polymerase chain reaction (PCR). The variation in length was due to a 40-bp region that tandemly repeated four to five times in the D-loop region. The first repeat is the most conserved one among the five repeats because there are no variable sites in this repeat. Besides the 40-bp length variation, 28 positions in the 764-bp sequences are variable and distributed evenly in the cytochrome b gene fragment and D-loop region. Variation in the D-loop of the Taipei treefrog is comparable to those of other vertebrates. Two well-differentiated lineages (northern and central) differing by mean sequence divergence of 1.7% are identified and concordant with their geographic distributions. The two lineages are inferred to have split from a common ancestral population in the early Pleistocene. However, the interpopulation divergence of the northern lineage (< 0.33%) is apparently lower than that of the central lineage (1.11%), implying that the two lineages evolved independently and had different demographic histories after divergence. This study reveals that anuran D-loop has potential as a genetic marker in phylogenetic and population genetic analyses of anurans.

Animals↗
PubMed1994

Chronic elemental mercury intoxication: clinical and field studies in lampsocket manufacturers.

Four workers chronically exposed to elemental mental mercury in a lampsocket manufacturing factory were studied. The clinical manifestations were severe in one, mild in another, and suspicious in the remaining two. Correlation between severity of clinical features and increased urinary mercury concentrations was found. The time weighted average mercury concentrations were 0.945 mg/m3 and 0.709 mg/m3 for two workers in one room and 0.225 mg/m3 in the other. After stopping exposure, the workers recovered spontaneously or with D-penicillamine treatment within six months. It is concluded that recovery from chronic elemental mercury intoxication may be complete when patients are removed early from the exposure environment. The hazard of mercury intoxication in recycling of waste substances is emphasised.

Adult↗
PubMed1994

Importance of transcapillary insulin transport to dynamics of insulin action after intravenous glucose.

Insulin action in vivo is determined by both transendothelial insulin transport (TET) across the capillary and subsequent insulin binding and postreceptor events. To examine TET under non-steady-state conditions, we performed intravenous glucose tolerance tests (IVGTT; 0.3 g/kg; n = 7) on conscious dogs. At basal, insulin in lymph was only 53 +/- 7% of plasma insulin (P < 0.001), whereas lymph glucose exceeded plasma levels (109 +/- 4 vs. 104 +/- 4 mg/dl, respectively; P < 0.02). On injection, dynamics of glucose in plasma and lymph were similar, suggesting rapid equilibration of glucose between compartments. In contrast, insulin appearance in lymph was delayed relative to plasma (5.1 +/- 1.3 vs. 2 +/- 0 min), peaked later (21 +/- 2 vs. 8 +/- 2 min), attained peak value of only 52 +/- 6% of plasma insulin (range, 35-76%), and remained lower than plasma insulin throughout the IVGTT (P < 0.05 or better). Minimal model-derived insulin sensitivity (SI) averaged 3.55 +/- 0.75 x 10(-4) min-1/(microU/ml). There was a strong linear relationship between lymph insulin and its effect on glucose disappearance [X(t), r = 0.95 +/- 0.01]. Determination of the relative contributions of TET and post-TET insulin-sensitive processes to overall SI revealed that cellular sensitivity to interstitial insulin dominated (r2 = 0.55), but was not the exclusive determinant of, overall SI, as insulin transport was also important (r2 = 0.21). TET is a previously unrecognized contributor to SI in vivo.

Animals↗
PubMed1994

Left vocal cord palsy: an unusual presentation of a mycotic aneurysm of the aorta caused by Salmonella cholerasuis.

A 67-year-old man was admitted to hospital because of fever, productive cough and a concomitant hoarseness. A para-aortic lesion was found on chest X-ray, and bronchoscopy revealed a left vocal cord palsy. Due to rapid enlargement of the lesion, angiography was performed, which revealed a pseudoaneurysm at the descending aorta. Operation disclosed an infected aneurysm with rupture, and tissue culture yielded Salmonella cholerasuis. The findings of a mycotic aneurysm and hoarseness due to compression of the left recurrent laryngeal nerve is a rare and serious combination caused by salmonella, previously unreported in the medical literature.

Aged↗
PubMed1994

Cardiac responses activated by nicotine in canine ganglial plexus between aorta and pulmonary artery.

In order to study the location and function of nicotine-sensitive neurons of cardiac ganglial plexuses, microdissections of collections of fat pads were carried out, and nicotine (100 micrograms) was injected into the ganglial plexus between aorta and pulmonary artery (A-PGP) in 30 anesthetized open-chest dogs. There were numerous ganglia or neurons in A-PGP. Either positive or negative inotropic and chronotropic responses were elicited following injections of nicotine into A-PGP. Control injections of 0.1 ml saline into A-PGP and injections of nicotine (100 or 200 micrograms) into right marginal ganglial plexus did not elicit any cardiac responses. After acute decentralization, nicotine (100 micrograms) was again injected into the same locus of A-PGP. Some positive and negative responses could still be induced, but their frequencies were reduced. These suggest that nicotine can directly activate the efferent parasympathetic and sympathetic neurons and indirectly activate them by stimulating the afferent neurons existing on the surface of dog heart.

Animals↗
PubMed1994

Systemic atrioventricular valve replacement in an infant with corrected transposition of the great arteries.

An eight-month-old male infant with corrected transposition of the great arteries and severe systemic atrioventricular valve regurgitation due to "Ebstein-like anomaly" is reported. Through a midline sternotomy and transeptal approach, a 20 mm Medtronic Hall aortic mechanical valve was reversely implanted into the systemic atrioventricular valve. Anti-platelet drugs (acetylsalicylic acid and dipyridamole) were prescribed for prevention of thromboembolism. The patient is doing well three years after operation.

Heart Valve Prosthesis↗