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Biomedical subjects

C F Yang

Publications and source records attributed to C F Yang.

126 records · Page 7Linked to original sources
PubMed1982

Long-segment arterial occlusion: percutaneous transluminal angioplasty.

In cases of occlusion of the superficial femoral artery exceeding a length of 10 cm, accompanied by involvement of the popliteal artery and poor runoff, percutaneous transluminal angioplasty is unfavorable. However, when such advanced occlusive disease is present in patients for whom vascular surgery is not feasible, this technique can be of value by averting or at least postponing amputation. Percutaneous transluminal angioplasty was used to recanalize long segments (10-36 cm) of occluded or stenotic femoropopliteal arteries in 21 patients. Results were evaluated by means of pre- and postangioplasty arteriograms and measurements of pressure indices. The initial success rate was 76%; the success rate on 5-24 month follow-up was 67%. The long-term benefit can be improved by other measures, such as stopping cigarette smoking, exercise, long-term anticoagulation therapy, and early detection and treatment of restenosis.

Aged↗
PubMed1977

Partition distribution of insecticides as a critical factor affecting their rates of absorption from water and relative toxicities to fish.

Loaches, Misgurnus anguillicaudatus (Cantor), a common fish in Taiwan, were treated with DDT, dieldrin, and monocrotophos by continuous exposure in aqueous solutions (or suspensions) and by injection. DDT and dieldrin were 150 and 220 times more toxic, respectively, than monocrotophos, to the fish exposed in aqueous solutions (24-hr LC50), but only 1/9 and 1/4 as toxic as monocrotophos by injection (24-hr LD50). Results of GLC analyses indicate that, at the end of 24-hr exposure, 96.5% of DDT, 92.7% of dieldrin, and 14.3% of monocrotophos were absorbed by loaches from aqueous solutions. The initial rates of absorption for DDT and dieldrin were about 10 to 20 times faster than that for monocrotophos. The large differences in relative toxicity may be due to partition distribution which in turn caused differences in absorption, as DDT and dieldrin are lipophilic and monocrotophos is hydrophilic. Statistical analysis of the relationship between fish toxicities and partition coefficients supports the present finding. The coefficient of correlation is 0.70 between parition coefficients (benzene/water) and toxicities to fish (rainbow trout) of 12 organophosphorus insecticides, 0.74 between coefficients and corrected fish toxicities, and 0.96 between partition coefficients and corrected fish toxicities for organophosphates only. Results of analyses are significant at less than 1% probability level. Similar correlation was also obtained between partition coefficients for hexane/water and toxicities of 8 organophosphorus and 5 organochlorine insecticides to rainbow trout.

Absorption↗
PubMedDate not supplied

Phosphorylation of the carotenoid droplet protein p57 by the catalytic subunit of cyclic adenosine monophosphate-dependent protein kinase and the effect of fluoride.

We have previously shown that the dispersion and aggregation of carotenoid droplets in goldfish xanthophores are regulated, respectively, by phosphorylation and dephosphorylation of a carotenoid droplet protein p57. There is a basal level of p57 phosphorylation of p57 in unstimulated cells, which is greatly stimulated by adrenocorticotropic hormone (ACTH) or cyclic adenosine monophosphate (cAMP) acting via cAMP-dependent protein kinase. We have also observed that, in permeabilized xanthophores, pigment dispersion can be induced when cAMP is replaced by fluoride. Since p57 has multiple phosphorylation sites, there is the question of whether all p57 phosphorylation is by cAMP-dependent protein kinase or whether phosphorylation by cAMP-independent protein kinase coupled with inhibition of phosphatase activity by fluoride can replace cAMP-dependent protein kinase and that the ability of fluoride to replace cAMP for pigment dispersion in permeabilized cells is probably due to activation of adenylcyclase. We also show that ACTH causes an approximately threefold increase in the level of cAMP in these cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMedDate not supplied

Experimental corneal neovascularization by basic fibroblast growth factor incorporated into gelatin hydrogel.

The study was designed to investigate the feasibility of using an acidic gelatin hydrogel as a biodegradable vehicle for basic fibroblast growth factor (bFGF). bFGF was incorporated by polyion complexation into a biodegradable hydrogel prepared by cross-linking acidic gelatin with the isoelectric point of 4.9. The dried hydrogel (sized to 2x1 mm) was hydrated with bFGF aqueous solution including different doses of bFGF (20, 50, 125, 250 and 500 ng) and implanted into a rabbit corneal pocket (2.5x2 mm). As a control group, the gelatin hydrogel without bFGF or bFGF alone (500 ng) was used. Corneal angiogenesis was evaluated by biomicroscopy, corneal fluorescein angiography and histology for 21 days. Photographs were taken and corneal angiogenesis was evaluated by image analysis. The hydrogel degraded with time after its implantation into the corneal pocket. Experimental eyes receiving the hydrogel containing more than 50 ng of bFGF demonstrated significant corneal angiogenesis. Control eyes and eyes receiving the hydrogel containing 20 ng of bFGF showed no corneal angiogenesis. Corneal angiogenesis, which occurred on the 3rd or 4th day after implantation, reached maximal growth on about day 7 and regressed from day 10 after implantation. The area of angiogenesis showed a dose-dependency on bFGF. The gelatin hydrogel itself induced neither angiogenesis nor inflammation. These results suggested that acidic gelatin hydrogel releases bioactive bFGF with its biodegradation, resulting in corneal neovascularization.

Absorbable Implants↗
PubMedDate not supplied

Vessel, plaque, and lumen morphology after transluminal balloon angioplasty. Quantitative study in distended human arteries.

We performed transluminal balloon angioplasty in 24 cadaver and nine amputated limb superficial femoral arteries under controlled experimental conditions. The cadaver arteries were excised, restored to in situ length, redistended, and maintained at 100 mm Hg intraluminal pressure at 37 degrees C throughout the angiographic and dilation procedure and during fixation. The amputated limb arteries were dilated and pressure perfusion-fixed after dilation. Quantitative analysis of cadaver vessels revealed that arteries with prominent atherosclerotic lesions had the same internal elastic lamina (IEL) circumference (15.6 +/- 1.0 mm) as those with little or no stenosis (16.8 +/- 0.5 mm) but lumen area (8.8 +/- 1.7 mm2) was markedly reduced compared to nonstenotic sites (20.0 +/- 1.9 mm2, p less than 0.01). Lesions occupied 49 +/- 6% of the area circumscribed by the IEL in cadaver arteries with prominent plaques. After dilatation, lumen areas at stenotic sites were enlarged 43% on histologic sections (12.6 +/- 1.8 mm2 vs 8.8 +/- 1.7 mm2, p less than 0.01) and 31% as determined by angiography (p less than 0.05) when compared to immediately adjacent nondilated regions. The increased lumen area was associated with splitting of the intima near the edges of the plaque, separation of the edges of the plaque from the media, and stretching of the media and adventitia, often with accompanying rupture of the media. There was no evidence of plaque compression, fragmentation, deformation, modeling, or herniation into the media. The detached wedge-shaped edges of the lesions formed flaps projecting into the lumen, resulting in a marked increase in lumen irregularity on cross-section.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Pathologic studies of fatal cases in outbreak of hand, foot, and mouth disease, Taiwan.

In 1998, an outbreak of enterovirus 71-associated hand, foot, and mouth disease occurred in Taiwan. Pathologic studies of two fatal cases with similar clinical features revealed two different causative agents, emphasizing the need for postmortem examinations and modern pathologic techniques in an outbreak investigation.

Disease Outbreaks↗
PubMedDate not supplied

Rapid diagnosis of common aneuploidies by quantitative fluorescent polymerase chain reaction.

The most frequent autosomal aneuploidies in newborns involve chromosomes 21, 18, and 13. The pre- and postnatal detection of chromosome abnormalities has been almost exclusively performed by cytogenetic analysis. In this paper, we assess the diagnostic value of fluorescent polymerase chain reaction (PCR) using polymorphic small tandem repeats (STR). PCR products are distinguished via both size and fluorescence intensity to confirm the trisomy by either triallelic signals with similar fluorescence intensities or diallelic pattern with double-dose response. Compared with the relatively time-consuming and laborious classic cytogenetic analysis, this technique is rapid, inexpensive, and sensitive for the detection of trisomies 21, 18 and 13, particularly when the numbers of cells obtained from the prenatal diagnosis is limited or where cell culture fails. With greater samples tested and more STR markers available, this method will become more reliable. This study investigates the detection of aneuploides involving chromosomes 21, 18, and 13 by comparing quantitative fluorescent PCR with karyotyping performed by conventional cytogenetics. The results obtained by the two techniques were concordant in all trisomy cases of this study.

Aneuploidy↗
PubMedDate not supplied

Chorea-ballismus with nonketotic hyperglycemia in primary diabetes mellitus.

PURPOSE: To describe the neuroimaging (Ct, MR, and single-photon emission CT [SPECT]) findings in a series of patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus and to correlate the imaging findings with the clinical presentation. METHODS: The neuroimaging and clinical data from 10 patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus were evaluated. Family and drug histories, as well as other causes of chorea, were excluded. All 10 patients had CT, 5 also had MR imaging, and 3 had SPECT examinations. Three had follow-up CT and MR imaging studies, and MR findings were correlated with CT findings in 5 cases. Two experienced neuroradiologists, aware of the diagnosis but blinded to the clinical status of the patients, evaluated all images and reached a consensus as to the final interpretation. RESULTS: CT studies in 9 of 10 patients showed a hyperdense putamen and/or caudate nucleus; in 1, the CT findings were normal. T1-weighted MR images in all 5 patients who had MR imaging (including the patient with a normal CT study) showed hyperintense lesions without significant T2 signal alternation at the basal ganglia. In all 3 of the patients who had SPECT studies of the brain, the scans revealed hypoperfusion at corresponding areas. All 3 follow-up studies depicted resolution of the lesions in the abnormal basal ganglia. Increased hypointensity on T2-weighted and gradient-echo T2*-weighted images was also observed in the sequential MR images. In all patients, the initial side of involvement correlated well with the neuroimaging findings. The chorea resolved within 2 days after treatment of the hyperglycemia in 9 patients. CONCLUSION: In patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus, CT and T1-weighted MR images show unilateral or bilateral lesions of the putamen and/or caudate. SPECT scans show hypoperfusion. These findings may be related to petechial hemorrhage and/or myelin destruction. Early recognition of these imaging characteristics may facilitate diagnosis of primary diabetes mellitus with hyperglycemia and prompt appropriate therapy.

Aged↗