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Biomedical subjects

C J Chiu

Publications and source records attributed to C J Chiu.

At least 19 recordsLinked to original sources
PubMed2001

Myopia and contrast sensitivity function.

PURPOSE: to measure the contrast sensitivity function of varying degrees of myopia with two types of optical correction (spectacle lens and contact lens). METHODS: One hundred and five myopic eyes and twenty-eight emmetropic eyes were collected. The myopic group included 105 eyes corrected with spectacle lenses and 71 eyes of them corrected with contact lenses, too; all had corrected vision acuity of 20/20 or better. The myopic eyes were divided into four groups: group 1 (-1D to -3D), low myopia; group 2 (-3.25D to -6D), medium myopia; group 3 (-6.25D to -12D), high myopia; and group 4 (> -12D), severe myopia. Spatial contrast sensitivity was measured using the OPTEC 2000 Contrast Sensitivity System. RESULTS: In groups 1 and 2, no statistically significant difference was found between myopes and emmetropes. In group 3, statistically significant loss of contrast sensitivity at higher spatial frequencies was found for myopic subjects corrected with spectacle lens, but not for myopes corrected with contact lens. In group 4, myopic subjects corrected with spectacle lenses showed significantly reduced contrast sensitivity function at all spatial frequencies; subjects corrected with contact lenses showed statistical sensitivity losses at 6, 12, 18 cycle/degree spatial frequencies. CONCLUSIONS: 1. We may suppose that low and medium myopes (groups 1 and 2), who showed normal contrast sensitivity functions, had no retinal dysfunction. 2. For high myopes, contact lens correction could reduce optical defocus and improve contrast sensitivity function in high spatial frequencies. 3. As retinal function disturbances occurred in severe myopes, the diminished contrast sensitivity was not fully compensated by contact lens correction. 4. Loss of contrast sensitivity might be interpreted as evidence for early retinal function disruption before retinal pathological events occur in severe myopes.

Adult↗
PubMed2001

Effect of a lacto-ovo vegetarian diet on fasting small intestinal motility.

BACKGROUND: Changes in diet can alter gastric and small intestinal (SI) motility. The effects of a vegetarian diet on fasting SI motility are unknown. METHODS: Manometric studies were performed in 9 lacto-ovo vegetarians (7 women) and 9 omnivores (7 women) of similar age and body mass index. On each study day, manometry was used to assess SI motility for 5 h, or 3 complete cycles of the interdigestive motor complex (IDMC). Lacto-ovo vegetarians were studied once: omnivores were studied twice, on their usual diet, and after consuming a 14-day lacto-ovo vegetarian diet. Diet diaries were kept for 5 days prior to each manometric study. Data were analysed for dietary composition and for cycle length and duration of each phase (I, II and III) of the IDMC. RESULTS: Dietary intake did not differ between chronic vegetarians and chronic omnivores apart from a trend to higher fibre intake (29 +/- 3 versus 20 +/- 3 g/day; P = 0.058). Omnivores eating a vegetarian diet showed a trend to decreased alcohol consumption (P = 0.068), but did not increase their fibre intake (20 +/- 3 versus 21 +/- 3 g/day). Neither cycle length nor duration of each IDMC phase differed between chronic vegetarians and chronic omnivores. After 14 days of a vegetarian diet, omnivores had a reduction in cycle length (128 +/- 19 versus 86 +/- 12 min; P = 0.02), with a non-significant reduction of Phase II (99 +/- 20 versus 50 +/- 8 min: P = 0.066). CONCLUSIONS: A chronic vegetarian diet has no major effect on fasting SI motility; but acute dietary change may alter the cycle length and component phases of the IDMC.

Adolescent↗
PubMed2001

Association between genetic polymorphism of tumor necrosis factor-alpha and risk of oral submucous fibrosis, a pre-cancerous condition of oral cancer.

Many cytokines have been thought to play important roles in the pathogenesis of oral submucous fibrosis (OSF), an areca nut chewing-specific pre-cancerous condition characterized by the deposition of collagen in oral submucosa. Tumor necrosis factor-alpha (TNF-alpha), situated in the class III region of human leukocyte antigen (HLA), is a mediator with multiple functions, including the regulation of inflammatory reaction and transcriptions of collagen and collagenase. In total, 809 male subjects were recruited for assessment of the association of OSF with a bi-allelic promoter-region (-308) polymorphism on the TNFA gene. The high production allele, TNF2, was significantly lower among OSF subjects (n = 166) than in areca-chewing controls (n = 284). This association was independent of oral cancer status. The multivariate-adjusted odds ratio for the TNFA 11 genotype was 2.6 (95% confidence interval = 1.4-4.9; p = 0.004). The finding may imply a multifunctional etiological factor of TNF-alpha in OSF pathogenesis.

Adult↗
PubMed1997

Cloning and nucleotide sequencing of the S4 genome segment of avian reovirus S1133.

The sequence of RNA genome segment S4 of the avian reovirus (ARV) strain S1133 was determined. S4 RNA is 1185 base pairs long and contains one open reading frame encoding a protein of 367 amino acid residues (40.6 kDa), the similar size as the known S4 gene product (sigma NS), with a net charge of -1 at neutral pH. The S4 RNA sequence possesses a pentanucleotide sequence UCAUC at the 3'-terminus of its plus strand like in ARV S1 and S3 segments and ten segments of mammalian reovirus (MRV). The predicted amino acid sequence comparison revealed that the homology is 44.02%, 45.71%, and 42.33% for ARV sigma NS and three serotypes of MRV sigma NS, respectively. The relatively high content of alpha-helix structure in the C-terminal portion of ARV sigma NS suggests that this protein may functionally relate to MRV sigma NS. Northern blot hybridization showed that a 32P-labeled cDNA insert S4-49 from ARV S4 RNA cross-hybridized with the corresponding RNA segments of all seven strains of ARV tested.

Amino Acid Sequence↗
PubMed1977

Spontaneous aortocaval fistula secondary to ruptured abdominal aortic aneurysm.

Two patients with the rare condition of spontaneous aortocaval fistula secondary to ruptured abdominal aortic aneurysm were treated successfully by surgical closure of the fistula. In view of the existing controversies on certain aspects of the pathophysiology involved, canine experiments were performed to elucidate the pathogenesis of regional venous hypertension and hematuria observed in these patients. The experiments demonstrated that regional venous hypertension is a purely rheologic phenomenon and that hematuria originates from a congested lower urinary tract.

Animals↗
PubMed1977

The roles of ventilation and perfusion in lung metabolism.

The lung, like other viable organs, requires the adequate supply of oxygen and metabolic substrates for its functional and structural integrity. Therefore, we studied the metabolic and ultrastructural consequences in the canine lung following bronchial and/or pulmonary arterial occlusions. The results indicate that the lung can maintain its bioenergetic levels for 5 hours with either the ventilation or perfusion alone. Ultrastructural changes appear to precede metabolic alterations measured. When both the ventilation and perfusion were interrupted, rapid biochemical and structural deteriorations occurred, whereas the combinations of alveolar obliteration and hypoxemia, induced with low F102, produced intermediate damage. The implications of these findings on the pathogenesis and evolution of acute respiratory distress syndrome, on the lung preservation for transplantation, and on the rationale for membrane oxygenator support are discussed.

Adenosine Diphosphate↗
PubMed1976

Why do radial artery grafts for aortocoronary bypass fail? A reappraisal.

The reasons for the high failure rate of radial artery grafts for aortocoronary bypass (ACB) are appraised. Each of 11 dogs received four types of grafts: femoral arteries were grafted to carotid arteries, and jugular veins were grafted to femoral arteries bilaterally. One of each pair of grafts was wrapped in a plastic sheet in order to interfere with the regeneration of vasa vasorum. The grafts were examined 2 months later. The results suggest that although operative trauma and intraluminal pressure change play important roles, the thick-walled artery appears to depend more on vasa vasorum for its integrity than does the thin-walled vein. A free radical artery graft, with vasa vasorum disrupted at both ends, cannot regenerate readily from the adjacent tissue, as is the case at the ACB position, and is therefore more vulnerable to subintimal hyperplasia and occlusion than either the vein graft or the internal mammary artery graft; both of these grafts are thinner, and the internal mammary artery graft remains undisrupted at one end.

Animals↗
PubMed1975

Cyclic AMP response to epinephrine and shock.

Hormonal regulation is fundamental to homeostasis, and the response in tissues is mediated by adenosine 3':5' equals cyclic phosphate (cyclic AMP). Since circulating levels of catecholamines are elevated during hemorrhagic shock, experiments were carried out to study the effects of epinephrine and of shock on cyclic AMP levels of plasma and of the intestine, a particularly vulnerable organ in canine hemorrhagic shock. Epinephrine was given to normotensive dogs as a constant infusion (group 1) or as a single pulse (group 2). Sequential blood samples showed a marked increase in circulating cyclic AMP, especially in portal and hepatic venous blood. Little change was noted in the tissues. Hemorrhagic shock (group 3) induced a marked increase in plasma cyclic AMP, with a depletion of mucosal cyclic AMP and adenosine triphosphate (ATP). Pretreatment before shock with alpha-blockade (group 4) abolished the decrease in mucosal cyclic AMP and ATP, and reduced the increase in plasma cyclic AMP.

Acepromazine↗
PubMed1975

Selective arterialization of coronary veins for diffuse coronary occlusion. An experimental evaluation.

The selective arterialization of coronary veins as a surgical therapy for diffuse coronary arteriosclerosis was studied in canine and sheep experiments. The arterialized blood can be delivered promptly to the selected region of the myocardium and an adequate runoff exists for this mode of revascularization, so that myocardial edema and hemorrhage do not occur. The retrograde blood flow through an anastomosis between the internal mammary artery (IMA) and great cardiac vein (GCV) is excellent, with a predominantly diastolic flow pattern. Follow-up studies indicate significant but partial protection of the myocardium against diffuse LAD occlusion. The size of infarcts is decreased. However, the focal or small transmural infarcts observed are usually located near the apex of the heart. The studies with radioactive microspheres (15 plus or minus 5 mu diameter) revealed that the degree of capillary trapping of microspheres is very much less when the microspheres are injected retrograde into the vein than when injected into the artery. This may indicate that significant "shunt" blood flow exists when the coronary vein is arterialized. Thus this study demonstrates both the potential and the limitation of the selective arterialization of coronary veins in revascularizing patients suffering from diffuse coronary arteriosclerosis.

Animals↗
PubMed1975

Effects of exogenous cyclic adenosine monophosphate in hemorrhagic shock.

Hemorrhageic shock produces potentially damaging alterations in the metabolism of cyclic adenosine 3',5'-monophosphate (cAMP), which is an intracellular second messenger for many hormones. The hypothesis that the administration of exogenous cAMP might have salutary effects on cardiovascular hemodynamics in shock was tested in canine experimetns. Intravenous bolus injection of dibutyryl cAMP (2 mg. per kilogram) produced hyperglycemia, but no changes occurred in heart rate, arerial pressure cardiac output, or in the first derivative of left ventricualr pressure (dp/dt). The findings were similar in conscious and anesthetized (Nembutal) normotensive dogs, in dogs after 3 hours of shock (at blood pressure of 40 mm. Hg) and after the reinfusion of shed blood. The only hemodynamic change noted was a transient hypotensionupon injection of massive doses of dibutyryl-(db-) cAMP or cAMP (greater than 10 mg. per kilogram). The implication of these findings in light of earlier reported hemodynamic effects of cAMP is discussed.

Anesthesia↗