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Biomedical subjects

T H Lin

Publications and source records attributed to T H Lin.

At least 163 records · Page 9Linked to original sources
PubMed1975

Relationship of chemical structure and solvent to in vivo scintigraphic distribution patterns of 11C compounds. II. 11C aminonitriles.

The preparation and scintigraphic evaluation of the distribution patterns in dogs of a series of structurally related aminonitriles labeled with 11C is described. Carbon-11-HCN was collected in water containing carrier NaCN following 22 MeV proton bombardment of 99% N2 and 1% H2 gas mixture for 1 hr. Ten 11C alphaN-alkylaminophenylacetonitrile hydrochlorides and 12 11C alpha-N-arylaminoarylacetonitriles were prepared from 11C-NaCN and the corresponding Schiff base, Ar-CH=N-R(Ar). Those 11C aminonitriles that were administered intravenously in aqueous solution showed some initial accumulation of activity in the liver followed by diffuse whole-body distribution and some small accumulation in urine. Aqueous insoluble 11C aminonitriles, which were administered intravenously in ethanol, ether, or DMSO, showed variable initial partial retention of activity in the lungs with prominent accumulation of activity in liver and excretion in bile. Several of these compounds showed pronounced and rapid accumulation of activity in the brain. Such activity in the brain was largely cleared within 15 min. Concentration of activity in the cerebrospinal fluid following clearance from the brain was 30 times greater than blood and equivalent in concentration to that noted in bile 18 min after intravenous administration of 11C alpha-anilinophenylacetonitrile in ethanol. These results suggest the possible correlation of regional brain uptake of activity of certain 11C aminonitriles with regional brain perfusion. Use of these or similar materials could permit assessment of brain tissue morphology followed by scintigraphic imaging of the bulk flow characteristics of cerebrospinal fluid.

Acetonitriles↗
PubMed1969

Fatigue crack nucleation in metals.

One of the unanswered questions in the study of fatigue is how cracks nucleate at stresses far below the static fracture strength. Previous theories show possible qualitative mechanisms that may operate in a crystal at room and low temperatures but none provides a quantitiative theory of this phenomenon. We show here a quantitative mechanism of fatigue crack initiation.With a small initial stress field, two closely located thin slices slide in opposite directions under cyclic loading. The increase of the local plastic strain with cycles of loading is calculated. The local plastic shear strain, positive in one slice and negative in the other, reaches 100 per cent at the free surface in a few hundred cycles. These large strains clearly cause the start of an extrusion or intrusion and fatigue crack nucleation.

Journal Article↗
PubMedDate not supplied

The impact of a brief coping skills intervention on adherence to breast self-examination among first-degree relatives of newly diagnosed breast cancer patients.

The present investigation sought to determine (1) the impact of a single session stress management/coping intervention (problem-solving training; PST) versus a general health counseling (GHC) control condition on breast self-examination (BSE) adherence among relatives of newly diagnosed breast cancer patients, and (2) whether women with heightened perceived risk of breast cancer and/or cancer specific distress at baseline were more likely to improve their BSE adherence following PST. The participants were 510 women age 20-75 who had at least one first-degree relative with breast cancer. All of the participants completed a baseline telephone interview, an intervention (PST versus GHC), and a 3-month follow-up telephone interview. The results revealed a 36% overall improvement in BSE adherence, with no significant between-group difference in improvement (chi 2 = 0.03, p = 0.87). The logistic regression analysis of improvement in BSE adherence revealed a statistically significant cancer-specific distress by treatment interaction (p = 0.04). Among women who received PST, those with high levels of cancer-specific distress were two times more likely to improve in BSE adherence than women low in cancer-specific distress. There was no effect of cancer-specific distress in the control condition. These results suggest that women with a family history of breast cancer who have high levels of distress may be most likely to benefit from behavioral coping skills intervention to promote adherence to breast cancer screening.

Adaptation, Psychological↗
PubMedDate not supplied

Half-scan cone-beam x-ray microtomography formula.

An x-ray shadow projection microtomographic system using a scannable point source is under development at AMIL-ARTS, SUNY at Buffalo. To overcome the limitations of the commonly used Feldkamp's cone-beam reconstruction formula, we have developed a generalized Feldkamp-type cone-beam reconstruction formula. In the generalized Feldkamp-type cone-beam reconstruction, a scanning locus can be either planar or helix-like, and a transaxial slice is reconstructed using projection data collected from a 360 degrees angular range (full scan). In this paper, the full-scan cone-beam formula is modified to require only projection data of approximate 180 degrees plus two fan-angles (half scan). First, a half-scan derivative-free noncircular fan-beam reconstruction formula is formulated. Then, a half-scan cone-beam reconstruction formula is derived as an extension of the half-scan fan-beam reconstruction formula using Feldkamp's procedure. Typical numerical simulation results are given for both half-scan formulae. Compared with the full-scan cone-beam formula, the half-scan cone-beam formula reduces the involved angular range of projection data and allows better longitudinal/temporal resolution.

Image Processing, Computer-Assisted↗
PubMedDate not supplied

Trace elements in hair of Blackfoot disease.

Blackfoot disease is a peripheral vascular disease resulting in gangrene of the lower extremities. Though extensive epidemiological study has implicated that high arsenic content in artesian well water of the endemic area bears some important connection with the disease, the etiology of the disease is still unknown. In this study, attention is paid to multielement determination in order to find out whether the trace elements in hair of Blackfoot disease patients are different from those of the controls. Experimental results indicate that the concentrations of As and Se in hair of patients are significantly higher than those of the controls, but Ca and Zn are significantly lower than those of the controls. The possible connection of these elements with the etiology of the disease is discussed.

Arsenic↗
PubMedDate not supplied

Longitudinal changes in Ca, Mg, Fe, Cu, and Zn in breast milk of women in Taiwan over a lactation period of one year.

The study of the composition of human milk has attracted worldwide interest, since it represents the pattern of nutrients most suitable for the younger infant. In the present study, the concentration of Ca, Mg, Fe, Cu, and Zn was measured in a total of 211 samples of human milk. The analytical technique of inductively coupled plasma atomic emission spectrometry (ICP-AES) was used for the analysis. From the results, it indicates that the mean concentration of Zn is highest in the colostrum with decreasing concentrations as the lactation progressed. The effects of age, parity, and lactation history on the results are also analyzed. It shows that the Zn concentration in the colostrum in the older mothers (>30 yr) was higher than that of the younger ones (20-30 yr).

Adult↗
PubMedDate not supplied

Antioxidant enzymes and trace elements in hemodialyzed patients.

Antioxidant enzymes together with trace elements in 26 patients with chronic renal failure treated with hemodialysis and 25 healthy subjects were investigated. Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSHPx) in plasma and erythrocytes were examined immediately before and after hemodialysis. The results are summarized as follows: 1. A significant decrease in plasma SOD, CAT, and GSHPx and erythrocyte GSHPx were found in patients before hemodialysis. 2. Erythrocyte CAT and GSHPx were significantly lower in the patients after hemodialysis than in the controls. 3. Plasma GSHPx was significantly higher after a single hemodialysis than before hemodialysis. 4. A good correlation between erythrocyte SOD and copper (Cu) in patients before hemodialysis was found. 5. A good correlation of GSHPx in erythrocytes and plasma was found before hemodialysis, whereas an even better correlation was found after hemodialysis. 6. Abnormalities of trace elements were found in hemodialyzed patients. 7. There is indirect evidence for increased oxidizing stress in uremic patients with hemodialysis. Dialysis treatment may improve some abnormalities (e.g., Hb, P), but may also induce some deleterious effects of free radicals or lipid peroxidation.

Adult↗
PubMedDate not supplied

Effect of acute administration of mercuric chloride on the disposition of copper, zinc, and iron in the rat.

The present study was designed to investigate the effect of mercuric chloride administration on copper, zinc, and iron concentrations in the liver, kidney, lung, heart, spleen, and muscle of rats. The results showed that after dose and time exposure to mercuric chloride, the concentration of mercury in the six tissues was significantly elevated. Data showed that there were no interaction between mercury and tissue iron. There was a considerable elevation of the content of copper in the kidney and liver. The most significant changes in the copper concentration took place in the kidneys. About a twofold increase in the copper content of the kidney was noted after exposure to mercuric chloride (3 mg and 5 mg/kg). Only slight elevations in the copper content occurred in the liver especially in high dose and longer exposure time. In the remaining organs, the copper content was not changed significantly (p > 0.05). The most significant changes in the zinc concentration took place in liver, kidney, lung and heart (5 mg/kg). Marked changes in kidney zinc concentrations were observed at any of the specified doses. Zinc concentrations were significantly increased in kidney of rats sacrificed 9-48 h after s.c. injection of HgCl2 (5 mg/kg); in liver obtained from rats at 18, 24 or 48 h after injection; and in lung after 24 or 48 h of treatment. The heart and spleen zinc concentrations were elevated at 24 and 48 h after injection of HgCl2 (5 mg/kg), respectively. The results of this study implicate that effects on copper and zinc concentrations of the target tissues of mercury may play an important role in the pathogenesis of acute mercuric chloride intoxication.

Animals↗
PubMedDate not supplied

Clinical features and management of overdosage with thyroid drugs.

Accidental ingestion and overdose of medications used in thyroidal illnesses may occur because of the frequency of these diagnoses. This review discusses acute overdosage of 4 groups of medicines. Acute ingestion of thyroid replacement medications occurs very frequently. Overdosage in children is usually asymptomatic and a benign condition; after evacuation of the stomach, propranolol may be used to treat symptomatic children. Other therapeutic regimens are rarely indicated in this age group. Ingestions of large amounts of antithyroid medications occur very rarely and limited information regarding treatment is available in the medical literature. Acute ingestion of iodine often results in corrosive injury of the gastrointestinal tract and renal damage. Cardiopulmonary collapse secondary to circulatory failure, oedema of the epiglottis and aspiration pneumonias may cause death. Administration of starch and sodium thiosulphate, maintenance of airway and stabilisation of circulation are the major components of therapy. Acute overdosage of beta-blockers is uncommon but can be lethal. Patients may appear well initially but they can suddenly develop convulsions and profound cardiovascular collapse requiring instant aggressive therapy. Potassium and glucose concentrations should be monitored. The usage of atropine, isoprenaline (isoproterenol), glucagon and prenalteral is discussed.

Adult↗
PubMedDate not supplied

On the viscoelastic properties of the anteromedial bundle of the anterior cruciate ligament.

The nonlinear viscoelastic properties of the anteromedial (AM) bundle of porcine anterior cruciate ligament (ACL) were characterized by using a new analytical approach based on the quasi-linear viscoelastic theory. Stress relaxation and cyclic tensile tests were performed. Using the solution derived from this approach, we curve-fitted data from the stress relaxation test to determine the viscoelastic coefficients for the ligament bundles. The coefficients were verified by comparison of the predicted and the experimental results from the cyclic tensile test. The ACL AM bundle exhibited significant stress relaxation with time; a reduction of more than 50% of the peak value occurred during the 2-h experiment. Also, the reduced relaxation function for the ACL AM bundle was not a linear function of logarithmic time, as is commonly assumed for many soft tissues. The new approach, which takes into account the finite strain rate of the ramp function used in the stress relaxation test, provides an accurate description of this nonlinear stress relaxation behavior.

Animals↗