Biomedical subjects

T T Le

Publications and source records attributed to T T Le.

29 records · Page 2Linked to original sources

PubMed1995

Endovascular stent placement and magnetic resonance angiography for management of hypertension and renal artery occlusion during pregnancy.

BACKGROUND: Severe renovascular hypertension carries serious maternal and fetal risk. In patients failing medical therapy, therapeutic options include surgical revascularization, nephrectomy, and percutaneous angioplasty. CASE: A pregnant woman with long-standing hypertension developed accelerated hypertension despite multiple drug therapy. Magnetic resonance angiography diagnosed an atrophic kidney with a critical proximal right renal artery lesion. At 17 weeks' gestation, this renal artery occlusion was treated with percutaneous angioplasty and endovascular stent placement; hypertension has improved markedly, allowing discontinuation and tapering of her antihypertensive medications. Total fetal radiation dose was 0.002 Gy. CONCLUSION: Magnetic resonance angiography is a promising, noninvasive diagnostic method of evaluating renovascular hypertension during pregnancy. Transluminal angioplasty and endovascular stent placement can be performed safely and effectively with nominal fetal radiation exposure.

Adult↗

PubMed1995

Changes in various plasma lipid components, glucose, and insulin in Spermophilus lateralis during hibernation.

This study evaluated fat mobilization as related to gluconeogenesis in two age groups of hibernating golden-mantled ground squirrels (Spermophilus lateralis). Our experimental group consisted of a total of 16 male and 15 female squirrels. Plasma samples were collected from selected animals being killed weekly from January to March, and the concentration of triglycerides, glycerol (GY), free fatty acids (FFA), total cholesterol, lipase activity, glucose, and insulin, were determined by biochemical assays and radioimmunoassay. Our results showed a mean FFA/GY ratio of five, which was higher than the predicted value of three, suggesting a significant depletion of GY and an enhanced rate of gluconeogenesis via GY to maintain glucose homeostasis in the hibernating animals. The factor of age did not significantly affect plasma lipid components. However, in the male group, plasma glucose levels were significantly higher for adults than for juveniles. Overall, females had significantly higher plasma glucose levels than males (150 +/- 11 vs. 110 +/- 8 mg%, P < 0.05). In the adult group, a gender influence was also seen on plasma insulin levels, with females' being higher than males' (66 +/- 13 vs. 25 +/- 3 microIU/ml, P < 0.01). We suggest that during hibernation, female squirrels may have a higher rate of lipolysis and gluconeogenesis along with a lower glucose utilization than their male counterparts. Additionally, adult females may exhibit a higher peripheral insulin resistance during hibernation than adult males, a possibility which merits further study.

Age Factors↗

PubMed1995

Variants of olfactory memory and their dependencies on the hippocampal formation.

Olfactory memory in control rats and in animals with entorhinal cortex lesions was tested in four paradigms: (1) a known correct odor was present in a group of familiar but nonrewarded odors, (2) six known correct odors were simultaneously present in a maze, (3) correct responses required the learning of associations between odors and objects, and (4) six odors, each associated with a choice between two objects, were presented simultaneously. Control rats had no difficulty with the first problem and avoided repeating selections in the second; this latter behavior resembles that reported for spatial mazes but, in the present experiments, was not dependent upon memory for the configuration of pertinent cues. Control animals varied considerably in their acquisition of odor-object associations with only a subgroup learning every set of pairings. These latter animals also performed well in the fourth task and, as indicated by post hoc analyses, developed complex strategies in dealing with the problem of serial odor-object pairs. Lesioned animals had no difficulty in selecting correct odors learned prior to surgery (problem one) but repeated their choices in problem two. This latter result suggests that hippocampus contributes to the transient memory of prior choices for odors as it does for prior choices in spatial mazes. Entorhinal rats were able to form odor-object associations (problem three), and a subgroup of the animals periodically succeeded in doing a long series of such choices (problem four), though with less frequency than controls. These results indicate that rats use both long-term memory and transient memory in dealing with olfactory problems and suggest that the second of these is dependent upon a hippocampal process that encodes a type of information other than the relationship between cues.

Animals↗

PubMed1994

Effects of cyclothiazide on synaptic responses in slices of adult and neonatal rat hippocampus.

The effects of cyclothiazide, a drug that blocks AMPA receptor desensitization, on synaptic responses were studied in field CA1 of hippocampal slices from adult and neonatal rats. Cyclothiazide (100 microM) reliably increased AMPA receptor-mediated field EPSP decay times in adult slices but only after prolonged (60-120 min) applications. In neonatal slices, 30 min applications of cyclothiazide were sufficient to produce large and long-lasting increases in response decay times. Since the effects of cyclothiazide on AMPA receptor binding properties were similar in adult and neonatal forebrain membranes, the data indicate that the slow action of the drug in adult slices is probably due to diffusion barriers. The prolongation of EPSP decay by cyclothiazide suggests that AMPA receptor-mediated synaptic responses in hippocampus are terminated by receptor desensitization.

Animals↗

PubMed1993

Monoclonal antibodies against the muscle-specific N-terminus of dystrophin: characterization of dystrophin in a muscular dystrophy patient with a frameshift deletion of exons 3-7.

The first three exons of the human muscle dystrophin gene were expressed as a beta-galactosidase fusion protein. This protein was then used to prepare two monoclonal antibodies (mAbs) which react with native dystrophin on frozen muscle sections and with denatured dystrophin on western blots but which do not cross-react with the dystrophin-related protein, utrophin. Both mAbs recognized dystrophin in muscular dystrophy (MD) patients with deletions of exon 3, and further mapping with 11 overlapping synthetic peptides showed that they both recognize an epitope encoded by the muscle-specific exon 1. Neither mAb recognizes the brain dystrophin isoform, confirming the prediction from mRNA data that this has a different N-terminus. One Becker MD patient with a frameshift deletion of exons 3-7 is shown to produce dystrophin which reacts with the N-terminal mAbs, as well as with mAbs which bind on the C-terminal side of the deletion. The data suggest that transcription begins at the normal muscle dystrophin promoter and that the normal reading frame is restored after the deletion. A number of mechanisms have been proposed for restoration of the reading frame after deletion of exons 3-7, but those which predict dystrophin with an abnormal N-terminus do not appear to be major mechanisms in this patient.

Amino Acid Sequence↗

PubMed1992

Utrophin, the autosomal homologue of dystrophin, is widely-expressed and membrane-associated in cultured cell lines.

Utrophin, the autosomal dystrophin-related protein (DRP), is expressed in HeLa cells, smooth muscle-like BC3H1 cells from mouse brain, COS monkey kidney cells, the P388D1 monocyte-macrophage cell line and untransformed human skin fibroblasts, as well as in rat C6 glioma and Schwannoma cells. It was undetectable, however, in the Sp2/O mouse myeloma cell line and in hybridoma lines derived from it. Dystrophin was not detected in any of these cell lines. Although all utrophin-containing cells were capable of forming monolayers in culture, no major effects of either attachment to substratum or length of time in culture (2-17 days) on utrophin levels were observed. After subcellular fractionation of BC3H1 or glioma cells, nearly all of the utrophin was found in the Triton-soluble fraction, suggesting an association with cell membranes.

Animals↗

PubMed1990

Beta-thalassemia/haemoglobin E disease in Vietnam.

A clinical and haematological study of 75 patients with beta-thalassemia/haemoglobin E (HbE) in Vietnam is described. The clinical picture is similar to thalassemia major. Anemia is often severe, haemoglobin was 5.0 +/- 1.6 g/dl. Splenomegaly was almost consistently detected. Haemochromatosis was clear. Both red cell indices and morphology showed hypochromicity and microcytosis, the MCH was 23.3 +/- 2.9 pg, the MCV was 81.5 +/- 11 fl; anisocytosis, poiklocytosis, tear drop cells, leptocytosis, target cells, and polychromasia were always observed. The osmotic fragility of erythrocytes was increased. The erythrocytic lifespan was shortened, about 7-15 days and the erythrocytes were destroyed in the spleen in 63 per cent of cases. Depending on whether it was beta(+)-thalassemia/HbE or beta(0)-thalassemia/HbE, HbF ranged from 22.8 +/- 7.2 to 57 +/- 12.7 per cent; HbE from 30.1 +/- 12.2 to 42.7 +/- 13 per cent; and HbA1 was decreased down to from only 46.8 +/- 13.5 to 0 per cent.

Adolescent↗

PubMed1989

Extractive ultrafiltration.

Extractive ultrafiltration is a separation process by which liquid extraction in series with ultrafiltration removes contaminants from water. The toxin is extracted into an organic-in-water emulsion which is then separated by an ultrafilter. The ultrafilter thus replaces the settler in a conventional mixer-settler process; the extraction and emulsification allow ultrafiltration to remove much smaller molecules than is indicated by the nominal molecular weight cut-off of the membrane. In the present study, the toxins, toluene and monochlorobenzene, were individually extracted from water into heptane and hexane, respectively, reducing their concentration in the permeate water five to ten fold, at fluxes in excess of 60% of the pure water flux for the membrane. The operating temperature, organic to water ratio, and amount of surfactant used to stabilize the emulsion, were independently varied to determine the optimum values of each quantity, consistent with highest possible permeate flux through the membrane and maximum removal of the contaminant. General conclusions drawn were that the optimum permeate was obtained 1. at ambient temperature 2. when surfactant concentration was a minimum 3. when a minimum amount of extraction solvent was used.

Chemical Phenomena↗

PubMedDate not supplied

Comparison of the treadmill exercise score and single-photon emission computed tomographic thallium imaging in risk assessment.

BACKGROUND: This study compared the prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging with that of treadmill exercise score in medically treated patients with coronary artery disease (CAD). METHODS AND RESULTS: The treadmill exercise score was derived from exercise duration, degree of ST segment depression, and the treadmill anginal index. There were 121 patients with no CAD and 316 patients with angiographically defined CAD (> or = 50% diameter stenosis of one or more vessels). During a mean follow-up of 29 months, there were 35 cardiac deaths or nonfatal myocardial infarctions. Multivariate Cox survival analysis showed the extent of thallium imaging abnormality and CAD to be independent predictors of prognosis. On the other hand, the treadmill exercise score was not a significant predictor even on univariate analysis. The results of thallium uptake were the strongest independent predictors of prognosis and in addition provided incremental prognostic power to coronary angiography (chi 2 = 29 for SPECT, 27 for coronary angiography, and 37 for both). CONCLUSIONS: Thus exercise SPECT thallium imaging is significantly better than the treadmill exercise score in risk assessment. The size of the perfusion abnormality is an important predicator of prognosis.

Adult↗

PubMedDate not supplied

Screening donor blood for malaria by polymerase chain reaction.

In countries where malaria is endemic, its transmission is a hazard of blood transfusion. The microscopical and immunological methods in current use for malaria diagnosis are unsatisfactory for low levels of parasitaemia in blood donations. The polymerase chain reaction (PCR) can be 100-fold more sensitive than thick blood film examination when appropriate primers are used and can detect and distinguish Plasmodium falciparum and P. vivax in a single tube. A study of 1506 blood donations in Ho Chi Minh City (3 of which were positive) suggests that PCR can provide an effective screen for P. falciparum under local conditions. Studies in a region of Viet Nam where malaria is common showed that PCR detects many more cases of low-level parasitaemia (19/30) than thick blood films (4/30).

Animals↗

PubMedDate not supplied

[The results of serological studies in different foci of tropical and tertiary malaria].

Attempt was made to determine the value of serologic indices of malaria surveys. Following uniformed methodological and technical approaches 3 foci of P. vivax and 6 foci of P. falciparum malaria were surveyed in different endemic zones of Vietnam and the USSR. It was shown that the most objective criteria for a foci classification is its serologic mean geometric titre. The latter in its turn directly depends of transmission longevity in a foci.

Animals↗