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Biomedical subjects

C H Yang

Publications and source records attributed to C H Yang.

At least 217 records · Page 12Linked to original sources
PubMed1993

Indocyanine green videoangiography of choroidal neovascular membrane in age-related macular degeneration.

Fluorescein angiography is the traditional tool for the detection of choroidal neovascularization of age-related macular degeneration. However, some limitations exist which impede its efficacy in the detection of subretinal neovascularization. Indocyanine green videoangiography is a recently developed technique which differs from fluorescein angiography in many ways. We performed indocyanine green videoangiography in 18 eyes with occult choroidal neovascularization, demonstrated by fluorescein angiography. Sixteen of the 18 eyes showed an abnormal vessel loop in the early phase of indocyanine green videoangiography. In the late phase, all 18 eyes had abnormal dye retention around the suspected neovascular area; however, only 12 eyes revealed a distinct border of neovascularization. No side effects, such as nausea, vomiting, or allergic reactions, were noted in our patients. Advantages and drawbacks of indocyanine green videoangiography in comparison with fluorescein angiography are discussed.

Choroid↗
PubMed1993

Effect of intravenous clonidine on prevention of postepidural shivering.

The effects of intravenous clonidine, a central adrenergic alpha-2 agonist, on the incidence of shivering and hemodynamic changes after epidural anesthesia were assessed in patients undergoing extracorporeal shock wave lithotripsy (ESWL). Forty ASA class I or II patients were randomly assigned in a double-blind manner to one of two groups. Twenty patients received intravenous clonidine 150 micrograms/10 ml (clonidine group) and twenty patients received normal saline (control group) at 20 min before epidural administration of 1.5% lidocaine. Shivering was determined objectively by observing involuntary muscle activity. Arterial blood pressure, heart rate, respiratory rate and oxygen saturation were measured at 5-min intervals during the first 50 minutes following IV pretreatment. There was significant difference between clonidine and control groups in the incidence of shivering (5% vs. 55%, p = 0.002). Shivering began at an average of 16.8 +/- 9 min (range: 5-30 min) in control group and only one patient shivered at 18 min in clonidine group. The mean sensory level was T7 in both groups. There were no differences between the two groups in mean arterial pressure and respiratory rate, though there was a trend in reduction of MAP in clonidine group. Heart rate and oxygen saturation decreased slightly in clonidine group. The main adverse effect of clonidine pretreatment was drowsiness. In conclusion, intravenous clonidine 150 micrograms was effective in preventing shivering with minor hemodynamic changes in patients receiving epidural anesthesia.

Adult↗
PubMed1993

Serodiagnosis of tuberculosis using the A60 IgG ELISA.

The serodiagnosis of tuberculosis (TB) by using an enzyme-linked immunosorbent assay (ELISA) to detect IgG against mycobacterial antigen 60 (A60) was evaluated. Forty-three controls (10 healthy adults, 19 patients with non-tuberculous pulmonary diseases and 14 patients with non-pulmonary infectious diseases) and 63 patients with TB in different disease activity (50 patients with active TB and 13 patients with old pulmonary TB) were studied. When a cut-off value of 200 units was selected, the results obtained with controls were: 100% negative in IgG titers in healthy adults and patients with non-pulmonary infectious diseases, 89% negative in IgG titers in patients with non-tuberculous pulmonary diseases. The overall "false positive" rate was 5% in the control groups. The percentage of serologically positive cases of active TB was: 82% in smear-positive, 67% in smear-negative/culture-positive and 38% in culture-negative. Of the 13 patients with calcified pulmonary TB, four had a positive serological response (31%). Four out of eight patients with active TB showed an elevation in IgG titer 1 to 3 months after diagnosis and anti-TB chemotherapy. The positive and negative predictive values of the test may provide valuable information according to the prevalence of TB in different populations. When the TB prevalence is high, a positive IgG ELISA test may support the diagnosis of active TB.

Antibodies, Bacterial↗
PubMed1993

Prognostic significance of human papillomavirus detected with polymerase chain reaction in cervical cancer.

In order to investigate the prognostic factors of cervical cancer and its association with human papillomavirus (HPV), we analyzed 50 specimens of cervical cancer with a DNA polymerase chain reaction (PCR) mainly to detect HPV types 16 (HPV 16) and 18 (HPV 18). The result showed that at least 74% (37/50) of the specimens had HPV DNA. Among them, 54% (20/37) of the cases were HPV 16 and 32% (12/37) were HPV 18. These HPV DNA positive patients had poorer differentiation in histology than the HPV DNA negative patients. We draw no conclusion about the prognostic significance of HPV DNA in cervical cancer. Perhaps more cases should be analyzed.

Adult↗
PubMed1993

Prenatal cytogenetic diagnosis by amniocentesis before 15 weeks' gestation.

Three hundred and ten early amniocenteses before 15 weeks' gestation, including one set of triplets and four twins, were performed for prenatal cytogenetic diagnosis. There was a 100% success rate in obtaining amniotic fluid and 99.4% success rate in achieving amniotic cell cultures. The mean time from amniocentesis to cell harvest by the in situ culture method was 11.3 days. A total 13 abnormal fetal karyotypes were diagnosed. The total fetal loss rate (spontaneous abortion, elective termination and late loss) was 4.5%, while miscarriage within two weeks after amniocentesis occurred in three cases (1%). Early amniocentesis combined with in situ cell culture is a safe, rapid and effective technique for early prenatal cytogenetic diagnosis.

Abortion, Spontaneous↗
PubMed1993

Reduced haloperidol/haloperidol ratios after oral haloperidol and decanoate administration in schizophrenics.

1. Haloperidol and reduced haloperidol plasma concentrations were measured in thirteen stable schizophrenic patients that received both oral haloperidol and haloperidol decanoate. 2. Significant correlations between reduced haloperidol/haloperidol ratios from oral haloperidol and haloperidol decanoate occurred at week two and week 16, respectively. 3. The formation of RH was consistent during haloperidol decanoate treatment.

Administration, Oral↗
PubMed1992

Crystallization and preliminary X-ray crystallographic analysis of lipase from Pseudomonas cepacia.

Large crystals of lipase from Pseudomonas cepacia have been grown at room temperature from solutions containing 2-methyl-2,4-pentanediol and sodium citrate. They grow within two weeks to typical dimensions of 1.0 mm x 0.5 mm x 0.3 mm. The crystals belong to the monoclinic space group P2(1), with unit cell parameters a = 84.91 A, b = 47.33 A, c = 86.00 A, and beta = 116.09 degrees. And they diffract to about 1.6 A upon exposure to synchroton X-rays. X-ray data have been collected to 2.2 A Bragg spacing from a native crystal.

Burkholderia cepacia↗
PubMed1992

Alteration of folate analogue transport inward after induced maturation of HL-60 leukemia cells. Molecular properties of the transporter in an overproducing variant and evidence for down-regulation of its synthesis in maturating cells.

Studies are described examining further the decline in folate analogue influx mediated by the one-carbon reduced-folate transport system in HL-60 cells following induction of maturation by cytodifferentiation agents. To facilitate the investigation of the underlying basis of this phenomenon, we derived a variant (HL-60/LCV) with 4-5-fold elevated influx capacity (Vmax) for folate analogues. A commensurate increase in the putative transporter for this system was documented by affinity labeling of these cells with N-hydroxysuccinimide-[3H]aminopterin. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the affinity labeled plasma membrane in HL-60/LCV cells delineated a protein peak at Mr = 75,000-80,000. This was substantially greater than the analogous transporter (Mr = 45,000-47,000) we had delineated (Yang, C.-H., Sirotnak, F.M., and Mines, L.S. (1988) J. Biol. Chem. 263, 9703-9709) with the same methodology in the L1210 cell plasma membrane. In addition, the rate of translocation of the Mr = 75,000-80,000 transporter in HL-60 and HL-60/LCV cells was 2-fold lower than the rate of translocation determined for the Mr = 45,000-47,000 transporter in L1210 cells. During induced maturation of HL-60/LCV cells toward the granulocyte pathway, [3H]methotrexate (MTX) influx capacity and the amount of the affinity labeled transporter decreased rapidly in a parallel fashion. The decrease in [3H]MTX influx and in affinity labeling and in the amount of the Mr = 75,000-80,000 transporter was 5-fold following exposure to 210 mM dimethyl sulfoxide (Me2SO) for 5 days during growth in culture. Moreover, during cycloheximide treatment, the decay in [3H]MTX influx at 37 degrees C and in amount of affinity labeled transporter was the same (t1/2 = 144-155 min) for both control and Me2SO-treated HL-60/LCV cells. These results, which reveal no difference in metabolic turnover for control and Me2SO-treated cells, suggest that the decline in folate analogue influx in HL-60/LCV influx cells is a very early event in the program of differentiation and probably occurs by down-regulation of synthesis of the transporter for the one-carbon reduced-folate transport system.

Affinity Labels↗
PubMed1992

Sociological and economic theories of suicide: a comparison of the U.S.A. and Taiwan.

Time-series analyses were carried out to explore the importance of sociological and economic variables in accounting for the suicide rate in the U.S.A. and in Taiwan for 1952-1984. Sociological variables (divorce and female labor force participation) played similar roles in the multiple regressions for both nations while economic variables (GNP per capita/growth and unemployment) played a role only in the U.S.A.

Cross-Cultural Comparison↗
PubMed1992

Correlation of contractile function and passive properties of rabbit urinary bladder subjected to outlet obstruction--an in vitro whole bladder study.

The present study investigated the correlation between contractile function and passive properties of rabbit urinary bladder subjected to outlet obstruction. Mild bladder outlet obstruction was induced by placing silicone rings (7 mm. diameter) around the bladder necks of male New Zealand rabbits. The animals were sacrificed after 2 weeks of obstruction. Contractile function was evaluated by measuring the response of the in vitro whole bladder to 500 microM bethanechol administration. Passive properties was assessed by performing in vitro cystometry and stress-relaxation techniques utilizing six different infusion rates. When the intravesical pressure reached 30 cm. H2O the infusion was stopped, allowing the bladder to relax and intravesical pressure to drop to a steady state level. The results can be summarized as follows: 1) Although the intravesical pressure response to bethanechol was about the same in control (13.3 cm. H2O) and obstructed (12.4 cm. H2O) bladder, the obstructed bladder emptied significantly less than control (20.4 vs 89.3%); 2) the results of the passive properties study showed that bladder stiffness was significantly higher at all infusion rates in the obstructed bladder, 3) the obstructed bladder showed significantly less relaxation after rapid stretching of the whole bladder by high speed fluid infusion; 4) histological examination of obstructed bladders revealed marked fibrous thickening of the serosal layer, interstitial fibrosis of the muscle layers, and hypertrophic and/or degenerative changes of the muscle fibers. In summary, 2 weeks after mild outlet obstruction of the urinary bladder the emptying ability, but not pressure generation, was reduced along with increased bladder stiffness and diminished capacity for stress-relaxation. Interstitial fibrosis and changing the properties of the smooth muscle cells might be involved in the functional impairment and deranged viscoelasticity of the urinary bladder after outlet obstruction.

Animals↗
PubMed1992

NuMA: an unusually long coiled-coil related protein in the mammalian nucleus.

A bank of 892 autoimmune sera was screened by indirect immunofluorescence on mammalian cells. Six sera were identified that recognize an antigen(s) with a cell cycle-dependent localization pattern. In interphase cells, the antibodies stained the nucleus and in mitotic cells the spindle apparatus was recognized. Immunological criteria indicate that the antigen recognized by at least one of these sera corresponds to a previously identified protein called the nuclear mitotic apparatus protein (NuMA). A cDNA which partially encodes NuMA was cloned from a lambda gt11 human placental cDNA expression library, and overlapping cDNA clones that encode the entire gene were isolated. DNA sequence analysis of the clones has identified a long open reading frame capable of encoding a protein of 238 kD. Analysis of the predicted protein sequence suggests that NuMA contains an unusually large central alpha-helical domain of 1,485 amino acids flanked by nonhelical terminal domains. The central domain is similar to coiled-coil regions in structural proteins such as myosin heavy chains, cytokeratins, and nuclear lamins which are capable of forming filaments. Double immunofluorescence experiments performed with anti-NuMA and antilamin antibodies indicate that NuMA dissociates from condensing chromosomes during early prophase, before the complete disintegration of the nuclear lamina. As mitosis progresses, NuMA reassociates with telophase chromosomes very early during nuclear reformation, before substantial accumulation of lamins on chromosomal surfaces is evident. These results indicate that the NuMA proteins may be a structural component of the nucleus and may be involved in the early steps of nuclear reformation during telophase.

Amino Acid Sequence↗
PubMed1992

The nuclear-mitotic apparatus protein is important in the establishment and maintenance of the bipolar mitotic spindle apparatus.

The formation and maintenance of the bipolar mitotic spindle apparatus require a complex and balanced interplay of several mechanisms, including the stabilization and separation of polar microtubules and the action of various microtubule motors. Nonmicrotubule elements are also present throughout the spindle apparatus and have been proposed to provide a structural support for the spindle. The Nuclear-Mitotic Apparatus protein (NuMA) is an abundant 240 kD protein that is present in the nucleus of interphase cells and concentrates in the polar regions of the spindle apparatus during mitosis. Sequence analysis indicates that NuMA possesses an unusually long alpha-helical central region characteristic of many filament forming proteins. In this report we demonstrate that microinjection of anti-NuMA antibodies into interphase and prophase cells results in a failure to form a mitotic spindle apparatus. Furthermore, injection of metaphase cells results in the collapse of the spindle apparatus into a monopolar microtubule array. These results identify for the first time a nontubulin component important for both the establishment and stabilization of the mitotic spindle apparatus in multicellular organisms. We suggest that nonmicrotubule structural components may be important for these processes.

Anaphase↗
PubMed1992

Bilateral macular coloboma and pigmented paravenous retinochoroidal atrophy.

A patient had bilateral macular coloboma with aggregations of pigment clumps located perivascularly, predominantly paravenously, and in other parts of the retina. The Toxoplasma IgG antibody was negative. The diagnosis of bilateral macular coloboma with pigmented paravenous retinochoroidal atrophy was made and seemed to be a developmental abnormality in origin.

Adult↗
PubMed1992

Glucose-6-phosphate dehydrogenase deficiency--report of 4 cases.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common hereditary enzyme disorder and more than 200 million people have a deficiency in this enzyme. It is a globally important cause of neonatal jaundice and causes life-threatening hemolytic crisis in childhood. At later ages, certain drugs such as antimalarials, and fava beans cause hemolysis among G6PD deficiency patients. The frequency and severity is influenced by genetic and cultural factors. It is common in Mediterranean, African, and some East Asian populations but rare in Korea. Four cases of G6PD deficiency which were first noticed in Korea are investigated with their clinical features.

Child↗
PubMed1992

[Transcervical resection of endometrium and submucous myomas].

Transcervical resection of the endometrium and submucous myomas using an unmodified urologic resectoscope has recently been developed as a treatment for menorrhagia and/or infertility when conservative management proves unsatisfactory but the patient desires to preserve the fertility or wishes to avoid hysterectomy. Through June 1990, 7 patients were treated with this procedure including one for endometrial ablation and six for transcervical myomectomy alone. No significant complication was seen and the results were relatively satisfactory in an average 7 1/2 months follow up. This approach seems a safe, effective surgical procedure and represents an attractive alternative to hysterectomy or abdominal myomectomy.

Adult↗
PubMed1991

Ocular pulse amplitude in myopia.

We studied the ocular pulse amplitude of myopic patients by using Alcon Pneumotonography. One hundred and eighty-eight cases (376 eyes) were enrolled in this study. The results revealed that the higher the myopia the lower the ocular pulse amplitude. The pulse amplitude has high correlation with refractive error and axial length, but poor correlation with scleral rigidity, intraocular pressure and corneal curvature. As the ocular pulse amplitude is generated by the choroidal blood flow, these results may reflect circulatory disturbance in the development of myopia.

Adolescent↗