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Biomedical subjects

M Truong

Publications and source records attributed to M Truong.

11 recordsLinked to original sources
PubMed2002

Analysis of radiation-induced apoptosis in human lymphocytes: flow cytometry using Annexin V and propidium iodide versus the neutral comet assay.

BACKGROUND: The neutral comet assay was devised to measure double-stranded DNA breaks, but it has also been used to measure apoptosis based on its characteristic DNA fragmentation patterns. There is still uncertainty about the reliability of this method. By comparing the comet assay with a flow cytometry method that uses Annexin V binding to apoptotic cells, we have provided further evidence for evaluating the usefulness of the comet assay for detecting apoptosis. METHODS: Apoptosis was induced in human peripheral blood mononuclear cells (PBMC) by ionizing radiation and measured using the comet assay and a flow cytometry method that measures Annexin V and propidium iodide (PI) staining. RESULTS: The Annexin V flow cytometry assay distinguished among early apoptosis, late apoptosis, and an apoptotic or necrotic phase in which the cells were labeled with both Annexin V and PI. The comet assay detected only the latter two phases of apoptosis. CONCLUSIONS: The comet assay is a useful tool for measuring the late stages of apoptosis whereas the Annexin V assay measures higher amounts of apoptosis because it can detect cells in an earlier stage of the apoptotic pathway.

Annexin A5↗
PubMed2002

The effect of the ratio of CD4+ to CD8+ T-cells on radiation-induced apoptosis in human lymphocyte subpopulations.

PURPOSE: Apoptosis occurs spontaneously in cultured human peripheral blood lymphocytes but is enhanced by exposure to ionizing radiation. Subpopulations of lymphocytes are known to have varying radiosensitivities to radiation-induced apoptosis. The purpose of this study was to examine the radiation-induced apoptotic response of CD4(+) and CD8(+) T-cells incubated as a complete lymphocyte population. MATERIALS AND METHODS: Using a four-colour flow-cytometry method, which measures annexin-V binding to phosphatidyl serine and propidium iodide, spontaneous and radiation-induced apoptosis was measured in the total lymphocyte fraction and in CD4(+) and CD8(+) T-cell subpopulations. RESULTS: It was found that CD8(+) T-cells were more sensitive to radiation-induced apoptosis than CD4(+) T-cells at doses up to 2 Gy. The yield of radiation-induced apoptosis in the total lymphocyte fraction decreased with increasing ratios of CD4(+) to CD8(+) T-cells (CD4/CD8 ratio). By manipulating the CD4/CD8 ratio within lymphocyte cultures, it was found that the CD4/CD8 ratio had a dramatic effect on the yield of spontaneous apoptosis of total lymphocytes fraction and CD4(+) T-cells but not CD8(+) T-cells. CONCLUSION: The CD4/CD8 ratio affects the apoptotic response of human lymphocytes and CD4(+) T-cells.

Adult↗
PubMed2000

Phase II study of intravenous Doxil in malignant pleural mesothelioma.

Twenty-four patients with pleural mesothelioma received 50 mg/m2 of Doxil every four weeks. At follow-up, the disease had stabilized in 43% percent of patients and had progressed in 57%. No objective responses were observed. Estimated median survival of all patients was 37 weeks. Major toxicities were erythrodysesthesia of hands and feet and myelosuppression. No cardiac toxicity was observed. We concluded that Doxil at this dosage and schedule is inactive against pleural mesothelioma.

Aged↗
PubMed1998

Sonographic appearance of benign and malignant conditions of the colon.

OBJECTIVE: The objective of this study was to compare the sonographic appearance of different abnormalities of the colon to evaluate the role of sonography in their differential diagnosis. MATERIALS AND METHODS: We retrospectively reviewed videotaped sonographic examinations of 99 patients with proven diagnoses that included diverticulitis (n = 35), malignancy (n = 20), Crohn's disease (n = 16), pseudomembranous colitis (n = 14), ischemic colitis (n = 9), and ulcerative colitis (n = 5). Data were collected with regard to gut features, including the site of colonic involvement, associated small-bowel involvement, length of diseased segment, stratification, luminal contents, pneumatosis, and diverticula. Perigut features evaluated included abnormal fat, abscess, fistula, and ascites. RESULTS: On sonography, the following features were statistically significant (p < .05). Involvement of the small bowel was more common in patients with Crohn's disease than in the remainder of the study population (44% versus 1%). Left-sided colonic disease (91% versus 38%), diverticula (91% versus 3%), and perigut findings (91% versus 57%), including abnormal fat (83% versus 39%) and abscess (34% versus 8%), were features that indicated diverticulitis. Malignant conditions were more common in patients with a greater wall thickness (mean, 26.2 mm versus 10.2 mm), asymmetric involvement (85% versus 39%), loss of stratification (85% versus 20%), absence of perigut findings (65% versus 22%), and involvement of a short diseased segment (70% versus 16%). Involvement of the entire colon (50% versus 2%), luminal contents (64% versus 28%), and ascites (64% versus 26%) were features suggesting pseudomembranous colitis. CONCLUSION: Although the sonographic appearances of abnormalities of the colon overlap, some sonographic features are helpful in the differential diagnosis of colonic abnormalities.

Adult↗
PubMed1998

Mediastinal lymphadenopathy and hazy mediastinal fat: new CT findings of congestive heart failure.

OBJECTIVE: We describe two new CT findings of congestive heart failure (CHF): enlarged mediastinal lymph nodes and hazy heterogeneous mediastinal fat. MATERIALS AND METHODS: Forty-six patients were retrospectively identified who had major and minor clinical signs of congestive heart failure and had undergone chest CT during their symptomatic period. Two radiologists reviewed the CT studies and by consensus documented the presence or absence of imaging findings of CHF, including interstitial abnormalities, vascular redistribution, axial thickening, pleural effusions, cardiac enlargement, and mediastinal abnormalities. RESULTS: Smooth septal thickening, bilateral pleural effusions, vascular redistribution, and cardiac enlargement were the most common CT findings in patients with CHF. Enlarged mediastinal lymph nodes and hazy mediastinal fat were seen in 55% and 33% of cases, respectively. In a cohort of 17 patients with elevated pressures in the pulmonary capillary wedge documented within 24 hr of CT, CT scans revealed lymphadenopathy in 14 patients (82%) and inhomogeneous fat in 10 patients (59%). CONCLUSION: Enlarged mediastinal lymph nodes and hazy mediastinal fat occur in patients with CHF and are revealed by CT. Lymphadenopathy in patients with CHF does not necessarily indicate malignancy or an infectious process.

Adipose Tissue↗
PubMed1996

[Community-acquired pneumonia in children: importance of Mycoplasma pneumoniae infections and efficacy of antibiotics].

OBJECTIVES: Define a therapeutic management schema adapted to children with community-acquired pneumonia. METHODS: A prospective survey was conducted in 104 children over 18 months of age with community-acquired pneumonia. The pathogen was isolated in 85% of the cases. RESULTS: Viral infection alone was proven in 30 children (respiratory syncytial virus in 10). Pneumococci pneumonia was found in 12 patients; the isolated strains were sensitive to penicillin. Apyrexia was obtained in 11/12 cases with amoxicillin. Mycoplasma infections occurred in 42% of the cases (41 alone and in association with pneumococci in 2 cases). Pneumococci and mycoplasma infections could not be differentiated with standard radiography and laboratory tests. Initial treatment with beta lactamines was always unsuccessful in children with mycoplasma infections. Apyrexia was achieved when antibiotics were changed to macrolides. CONCLUSION: Since lower respiratory tract infections due to pneumococci are much more severe than those due to mycoplasma, beta lactamines should be given as first intention treatment for children over 18 months with pneumonia. Macrolides should be given in case of failure because mycoplasma would then be the most probable infectious agent.

Adolescent↗
PubMed1996

Arabidopsis carotenoid mutants demonstrate that lutein is not essential for photosynthesis in higher plants.

Lutein, a dihydroxy beta, epsilon-carotenoid, is the predominant carotenoid in photosynthetic plant tissue and plays a critical role in light-harvesting complex assembly and function. To further understand lutein synthesis and function, we isolated four lutein-deficient mutants of Arabidopsis that define two loci, lut1 and lut2 (for lutein deficient). These loci are required for lutein biosynthesis but not for the biosynthesis of beta, beta-carotenoids. The lut1 mutations are recessive, accumulate high levels of zeinoxanthin, which is the immediate precursor of lutein, and define lut1 as a disruption in epsilon ring hydroxylation. The lut2 mutations are semidominant, and their biochemical phenotype is consistent with a disruption of epsilon ring cyclization. The lut2 locus cosegregates with the recently isolated epsilon cyclase gene, thus, providing additional evidence that the lut2 alleles are mutations in the epsilon cyclase gene. It appears likely that the epsilon cyclase is a key step in regulating lutein levels and the ratio of lutein to beta,beta-carotenoids. Surprisingly, despite the absence of lutein, neither the lut1 nor lut2 mutation causes a visible deleterious phenotype or altered chlorophyll content, but both mutants have significantly higher levels of beta, beta-carotenoids. In particular, there is a stable increase in the xanthophyll cycle pigments (violaxanthin, antheraxanthin, and zeaxanthin) in both lut1 and lut2 mutants as well as an increase in zeinoxanthin in lut1 and beta-carotene in lut2. The accumulation of specific carotenoids is discussed as it pertains to the regulation of carotenoid biosynthesis and incorporation into the photosynthetic apparatus. Presumably, particular beta, beta-carotenoids are able to compensate functionally and structurally for lutein in the photosystems of Arabidopsis.

Arabidopsis↗
PubMed1995

[Measurement of peak expiratory flow in young children: comparison of four portable equipments].

BACKGROUND: Peak expiratory flow (PEF) monitoring is seldom used in young children because peak flow meter normal values are needed for children less than 7 years old. POPULATION AND METHODS: PEF was measured in 152 non asthmatic school children, aged 2.9 to 14.5 years with four peak flow meters (Assess, DHS, Vitalograph, MiniWright). Calibration of these peak flow meters were performed with flows ranging from 100 to 700 l/min with a calibration syringe. RESULTS: Calibration demonstrated the excellent linearity of each device but there was a slight overestimation by DHS and MiniWright, and a slight underestimation by Vitalograph and Assess. PEF measured with the four devices was better linearly correlated with height (r = 0.72 to 0.77) than with age. Differences similar to calibration have been found between the four linear regressions. CONCLUSION: These results indicate that PEF can be used in young children less than 7 years old. It is necessary to always use the same peak flow meter for a child.

Adolescent↗
PubMed1995

[Peanut sensitization and oily solution vitamin preparations].

BACKGROUND AND METHODS: Early sensitization to peanut can occur through milk formulas which contain peanut oil. Thus, the groundnut allergens in relation to the early feeding have been systematically tested in all children referred to the paediatric allergy unit for symptoms not related to peanut allergy. RESULTS: Out of 102 children, 4 to 35 months old, 19 had a positive test (weal > 3 mm). Neither breast feeding nor milk formulas changed the frequency of sensitization. On the contrary, vitamin D preparations in groundnut oil significantly increased the risk (p < 0.008). Odds ratios were 5.47 in the case of neonatal prescription, 4.82 in case of delayed prescription. Odds ratio increased to 8.25 (p < 0.04) in allergic children under two years who had received oily vitamin D preparation during their neonatal period. CONCLUSIONS: The result suggest to leave groundnut oil out of all foods and drugs given to infants and young children, as required for infantile milk formulas.

Animals↗