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Biomedical subjects

T V Nguyen

Publications and source records attributed to T V Nguyen.

122 records · Page 7Linked to original sources
PubMed1986

Computing the skeleton of coronary arteries in cineangiograms.

In this paper we describe techniques to determine the skeleton of coronary arteries and to measure their medically significant geometric properties (such as boundaries and orientations) in cineangiograms. We use these geometric properties for segmentation, i.e., for separating the image of the arteries from the background. The purpose of this segmentation is to produce a structural description of the arterial tree for high-level processing. Our technique is completely automatic, efficient, and reliable. Our technique starts with the detection of skeleton points from a local ridge detector using density profiles of the arteries. Local orientations of skeleton points are obtained directly from the ridge detection or from local edge directions. Boundaries of the arteries are computed from the density profile along a straight line perpendicular to the skeleton. From this, a sequential and raster-scan tracking procedure is applied to obtain segments of the arteries from two scanning directions. The final segments are generated by merging all the segments.

Algorithms↗
PubMed1986

Depletion of striatal beta-phenylethylamine following dopamine but not 5-HT denervation.

The effects of lesions of the substantia nigra (electrolytic 2 mA 10 sec, or 6-OHDA 2 or 8 micrograms) and of the midbrain raphé nuclei (electrolytic 2 X 1.0 mA 10 sec) at 7 days postlesion on striatal levels of beta-phenylethylamine, DA, DOPAC, HVA, 5-HT and 5-HIAA and on hypothalamic levels of beta-phenylethylamine, DA, NA, 5-HT and 5-HIAA were investigated. In the presence of deprenyl (2 mg kg-1 2 hr SC), both electrolytic and 6-OHDA-induced dopamine-depleting lesions of the nigra but not 5-HT-depleting lesions of the raphé nuclei resulted in a marked decrease in the accumulation of beta-phenylethylamine. The marked reduction in accumulation of striatal beta-phenylethylamine in response to lesions of the substantia nigra indicates that the intraneuronal compartment is a major site of striatal beta-phenylethylamine synthesis. An equivalent decrease (approximately 40%) in the accumulation of 5-HT was observed following electrolytic lesions of the substantia nigra or raphé nuclei after administration of L-5-HTP (200 mg kg-1 hr IP). As L-5-HTP at the dose employed in this study is taken up non-selectively by both DA- and 5-HT-containing neurones the loss of L-AAD following nigral and raphé lesions was apparently equivalent. These results indicate that depletion of beta-phenylethylamine may not be simply attributable to a general loss of L-AAD following lesions of monoamine-containing neurones and suggest either co-localisation of beta-phenylethylamine and DA or the existence of distinct beta-phenylethylamine-containing neurones.

Animals↗
PubMed1985

Deuterium isotope effect in the transamination of p-tyrosine by rat liver tyrosine transaminase.

The rate of transamination of p-tyrosine catalyzed by rat liver soluble tyrosine aminotransferase (E.C. 2.6.1.5.) was significantly reduced when the hydrogen at the alpha-carbon position is replaced by deuterium or when the reactions were conducted in 2H2O. The cleavage of carbon-hydrogen bond at alpha-carbon position is at least partly involved in the rate-limiting step of tyrosine transamination. In 2H2O solvent the reduction of the overall rates of transamination of both p-tyrosine and alpha-2H1-p-tyrosine occurred uncompetitively which suggests that the deuterium solvent effect is involved in the tautomerization of the external Schiff's base.

Animals↗
PubMed1985

Genotoxic classification of anticancer drugs.

The effects of bacterial DNA excision repair on the mutagenic and lethal actions of 17 injectable anticancer drugs have been used to classify them into three levels of potential risk to medical personnel who are involved in their preparation and administration.

Antineoplastic Agents↗
PubMed1985

Linking family hardship to children's lives.

The impact of drastic income loss on children is mediated by a number of family adaptations, including the shift toward more labor-intensive households and altered relationships. Using newly developed codes on parenting behavior during the Great Depression, this study investigates the role of parental behavior (rejecting, nonsupportive) in linking economic hardship to children's lives in the Oakland Growth Study. The results extend beyond those reported in Children of the Great Depression by showing that economic hardship adversely influenced the psychosocial well-being of girls, but not boys, by increasing the rejecting behavior of fathers. The parenting behavior of mothers did not vary significantly by income loss. In addition, the rejecting influence of hard-pressed fathers was more pronounced in relation to less attractive daughters, as judged by physical features. Attractive daughters were not likely to be maltreated by their fathers, no matter how severe the economic pressure. These outcomes on family mediation and conditional effects underscore the importance of viewing economic decline in relation to both the child's characteristics and parenting behavior. An understanding of the effects of economic decline in children's lives requires knowledge of parent and child behavior within the family and life course.

Adolescent↗
PubMed1985

Effect of Yoshida ascites tumour on the circulation in rats.

The circulation in anaesthetized rats with Yoshida ascites tumour was studied. Cardiac output was determined according to the reference flow method, while the distribution of cardiac output by labelled microspheres 15 mu in diameter. Arterial blood pressure decreased by 39 mm Hg and TPR by 23% at unaltered cardiac output. Blood flow of the brain and the coronaries increased by 39-43% while that of the kidney and the intestines decreased by 43 and 28%, respectively. The cardiac output fractions of the brain, the coronaries and the hepatic artery increased considerably, while that of the kidney decreased. The haematocrit decreased from 43 to 23%. It is assumed that part of the circulatory alterations (redistribution of cardiac output) were due to the anaemia and its consequences, while the others (arterial hypotension, lack of increase in cardiac output) should be regarded as an effect of a factor reaching the circulation from the cells of the ascites tumour.

Anemia↗
PubMed1984

Immunogenic proteins of Leishmania major during mouse infection.

Mice of different strains (C3H/He, A/Jax, DBA/2, BALB/c and CBA/Ca) were infected intracutaneously with Leishmania major. Antibody production was analysed on the antigens of the promastigote form of the parasite which had previously been separated by SDS-polyacrylamide gel electrophoresis and transferred to nitrocellulose sheets. The kinetics of IgG antibody production were determined and the major immunogenic proteins of the parasite were identified for each strain of mouse. It was found that: 1 Antibody directed against parasite proteins appeared in the blood in all mouse strains tested soon after the first week of infection and rose steadily for 5 to 12 weeks. 2 Qualitative individual variation within a given strain was commonly observed in the response to the various antigens. Each mouse strain synthesized IgG directed against a somewhat different spectrum of parasite proteins. Homologies in antigen recognition by pooled sera of five mice ranged from 54% to 79% from one mouse strain to another. Hybrid mice from a BALB/c X CBA cross (F1 generation) recognized essentially all antigens recognized by the two parents. Proteins of L. major with apparent molecular weights of 19 kD, 60 kD, 65 kD, 70 kD and greater than 100 kD were immunogenic in all strains of mice tested.

Animals↗
PubMed1982

Exposure of pharmacy personnel to mutagenic antineoplastic drugs.

The Salmonella reversion test was used to measure the mutagenic activities of urine concentrates from individuals preparing cancer chemotherapy agents for i.v. administration. Longitudinal studies were performed in which the total urine produced in 24-hr periods was collected, starting on a Sunday at 7 p.m. after a duty-free weekend and extending over an 8-day period. There was no detectable increase in mutagenic activity in the urine concentrates of three pharmacy administrators who had no contact with these drugs. All six individuals admixing drugs in open-faced, horizontal laminar flow hoods displayed a 2-fold increase in mutagenesis by the fourth day with peak values of 2.7- to 24-fold occurring on Days 5 and 6, reduced values by Day 7, and a return to the spontaneous level by Day 8. When four of the six positive individuals in the preceding experiment admixed comparable amounts of chemotherapeutic drugs in a closed-face, vertical laminar flow hood, no increase in mutagenic activity was detected in their urine concentrates over the 8-day period.

Allied Health Personnel↗
PubMed1982

Risk of handling injectable antineoplastic agents.

Uptake of mutagenic substances by persons handling injectable antineoplastic agents was studied, and various methods of preventing such exposure were evaluated. Six persons who prepared i.v. admixtures individually collected their urine in 24-hour batches during several eight-day study periods; each prepared from 12 to 90 admixtures per working day during each period. I.V. personnel prepared admixtures in both horizontal laminar-flow hoods and vertical-flow biological-safety cabinets, and using gloves and masks. Three pharmacy personnel who did not handle any drugs served as controls. Urine was concentrated (each 24-hour sample was concentrated to about 1 ml), and the Salmonella/mammalian microsome mutagenicity test (Ames test) was used to detect mutagenic activity in the urine concentrates. Mutagenicity was observed in the urine of all personnel during periods when they prepared antineoplastic admixtures in horizontal laminar-flow hoods, both when using no protection and while wearing gloves or masks. When admixtures were prepared in the vertical-flow biological safety cabinet by personnel wearing gloves, no urine mutagenicity was detected. The control group showed no urine mutagenicity. Protective intervention methods should be used by all persons handling antineoplastic agents. Guidelines for handling these drugs are presented.

Animals↗
PubMed1977

Effects of prostaglandin endoperoxide analogs on contractile elements in lung and gastrointestinal tract.

Prostaglandin endoperoxides are formed in the lung as intermediate compounds in the biosynthesis of prostaglandins and thromboxanes. The effects of different doses of two analogs of prostaglandin endoperoxide PGH2 were compared with those of PGF2alpha and PGE2 on superfused preparations of isolated trachea, bronchiole, peripheral lung, pulmonary artery and gastrointestinal smooth-muscle tissues. Endoperoxide analogs induced contraction of all smooth-muscle structures in the lung and airway. Compared to PGF2alpha, analog I was approximately 71 times as potent on guinea-pig trachea, 214 times as potent on guinea-pig lung, and 57 times as potent on guinea-pig pulmonary artery. Analog II was moderately less potent on all tissues than analog I. On gastrointestinal smooth-muscle organs, the PGH2 analogs were generally closer in activity to PGF2alpha and PGE2, or even weaker. The findings show that PG endoperoxide analogs are potent constrictors of airways, lung and pulmonary vessels, and suggest that the naturally occurring compounds may participate in the mediation of bronchoconstriction and pulmonary vasoconstriction in disease states.

Animals↗
PubMedDate not supplied

Pharmacogenomics of osteoporosis: opportunities and challenges.

The genetics of osteoporosis can be considered in two broad areas: disease susceptibility and drug activity. While the former has been studied, the latter is still largely untouched. Pharmacogenomics is the utilization of genetic information to predict outcome of drug treatment, with respect to both beneficial and adverse effects. The pharmacotherapy of osteoporosis is characterized by variability in therapeutic response with limited prediction of response on a patient-by-patient basis. This is particularly problematic in a clinical situation where therapy is typically required for several years before outcomes can be evaluated for an individual. Thus, the emerging field of pharmacogenomics holds great potential for refining and optimising pharmacological treatment of osteoporosis. Key components for future development of the pharmacogenomics of osteoporosis should include improved understanding of mechanisms of drug action, identification of candidate genes and their variants and expansion of clinical trials to include genetic profiling. This approach could provide clinicians and scientists with powerful tools to dissect novel molecular pathways involved in osteoporosis and to identify new drug targets. The iterative combination of innovative genomics with classical endocrinological approaches in osteoporosis research can be examined as a model of biological research and innovate therapeutical approaches in a continuing interaction between clinical science and basic research.

Animals↗
PubMedDate not supplied

[Evaluation of malaria vector control measures in central Vietnam (1976-1991)].

Activities used to control malaria transmission in the pilot station of Vanh Canh in the Binh Dinh Province of central Vietnam from 1976 to 1991 have been evaluated. These activities were: spraying DDT in and around the houses in the villages and the settlements in the fields; spraying lambdacyalothrin in the houses; and use of bed-nets impregnated with permethrin. Their efficacy was measured by the number of fever episodes due to malaria infections among the population. The spraying of DDT in the houses was followed by a reduction of malaria infection by more than 90%. However, spraying of the settlements was not advantageous. The termination of DDT spraying was not followed by an increase of malaria infections. Spraying with lambdacyalothrin was slightly more effective than with pyrimiphos and DDT. The use of pesticide-impregnated bed-nets was efficient, especially in the villages far away from the forest. Thus, these activities can contribute to the control of the malaria endemic in central Vietnam.

Adolescent↗