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Biomedical subjects

E Martin

Publications and source records attributed to E Martin.

At least 523 records · Page 29Linked to original sources
PubMed1989

Larynx: MR imaging at 2.35 T.

To study the consequences of an improvement in spatial resolution, the authors compared magnetic resonance (MR) images of nine laryngeal specimens with whole-organ histologic slides of the same specimens. Five of the specimens were obtained during laryngectomies performed on patients with high-stage tumors of the larynx. Four specimens were from patients with no known disease. The MR images were obtained on a 2.35-T system with a closely fitting probe head. A conventional spin-echo sequence was used, with T1- and T2-weighted settings. The in-plane resolution obtained was about 0.3 mm. The T2-weighted images generally showed better contrast and allowed identification of the perichondrium. The resolutions used were not much greater than those clinically available. The findings suggest that there will be important advances in clinical MR imaging of the larynx in the near future.

Aged↗
PubMed1989

Variations in the in vivo P-31 MR spectra of the developing human brain during postnatal life. Work in progress.

With use of a modified surface coil technique, the authors recorded phosphorus-31 magnetic resonance (MR) spectra of the brains of 40 neonates and infants (48 examinations) ranging from 33 weeks postconceptional age to 6 years of age. Signals of phosphorus metabolites were collected in the frontotemporal region of the brain, and various P-31 MR spectral variables were compared at different times during postnatal life. The ratio of the phosphomonoester signal to the phosphodiester signal, which is related to phospholipid synthesis, decreases within the first 6 months of life; during the same time period, the ratio of the phosphocreatine (PCr) signal to the beta-adenosine triphosphate (ATP) signal increases. In addition, a difference was observed between the areas under the alpha- and beta-ATP peaks. This difference increases with age and correlates with the PCr/beta-ATP signal ratio. The variation of the alpha-ATP peak with age might be explained by overlap of the signals of nicotinamide adenine dinucleotide (NAD) and alpha-ATP.

Adenosine Triphosphate↗
PubMed1989

Quantitative estimation of the collagen content in normal and pathologic pancreas tissue.

The aims of the study were to measure the collagen content in pancreas using a colorimetric method and to compare the amount of collagen in normal pancreas (11 cases), diffuse fibrosing pancreatitis (17 cases), and chronic calcifying pancreatitis (11 cases). The procedure of fibrosis measurement was based on the selective capacity of two dyes, Sirius red and fast green, to set on collagen and noncollagenous proteins, respectively. After staining of sections, colors were eluted from the sections and the specific absorbance of each eluted dye was read on a spectrophotometer. The collagen content in normal pancreata was 26.5 +/- 7.2 micrograms collagen/mg protein. The amount of collagen increased with the age of patients: the mean value of the patients under the age of 50 was 18.2 +/- 4 micrograms collagen/mg protein whereas the mean value in older patients was 31.9 +/- 8 micrograms collagen/mg protein (p less than 0.01). The value of collagen in pancreas with a diffuse fibrosing pancreatitis was 44.7 +/- 7.5 micrograms collagen/mg protein. This value was significantly different from the collagen content in normal pancreas (p less than 0.001) and in pancreas with a chronic calcifying pancreatitis (77.9 +/- 8 micrograms collagen/mg protein, p less than 0.001). This method permits discrimination between different chronic diseases that can also be differentiated on a histopathologic basis.

Adult↗
PubMed1989

Human immunodeficiency virus (HIV) infection in haemophiliacs: long-term prognostic significance of the HIV serologic pattern.

To identify markers of prognostic value in the course of HIV disease, immunologic parameters and profiles of HIV antibodies and antigen were studied in 60 haemophiliacs. The 43 HIV-seropositive subjects were followed prospectively over a 4 year period with a retrospective analysis as well of their frozen plasma for HIV markers. This group had a significant decrease in number of helper/inducer T lymphocytes as compared with 17 HIV seronegative subjects. The degree of changes correlated with the stage of disease, with the most severe depletion of CD4 cells in those who developed AIDS. Counts of B cells and platelets were also lower in HIV-infected haemophiliacs. Ten out of 12 AIDS patients had undetectable antibodies to HIV p24 antigen; low levels of p24 antibody were also seen in six out of 15 subjects with lymphadenopathy (CDC stage III), but in only two out of 16 asymptomatic subjects (CDC stage II). Sustained HIV p24 antigenaemia (greater than 30 pg/ml) was seen in 10 AIDS patients, in five subjects with lymphadenopathy and in two asymptomatic haemophiliacs. Initial HIV serologic profiles, obtained when all patients were asymptomatic, were highly predictive for progression of the HIV infection: the initial pattern of low anti-p24 antibody and positive p24 antigenaemia conferred the worst prognosis, with all patients in this group developing ARC or AIDS within 36 months, whereas an initial high level of anti-p24 without p24 antigenaemia was associated with relatively the best prognosis. Of such subjects, 58% have remained clinically asymptomatic after 48 months of the study (P less than 0.00001). The serologic profile of HIV antibody pattern and HIV antigen in haemophilic patients thus already provides important prognostic information at an early stage of HIV infection.

AIDS Serodiagnosis↗
PubMed1989

Localization of apolipoprotein A-I and apolipoprotein A-II in human atherosclerotic arteries.

Apolipoprotein A-I and apolipoprotein A-II, the two major protein components of the high-density lipoproteins, were visualized in human arteries using an immunofluorescence technique. Apolipoprotein A-I and apolipoprotein A-II were codeposited into the intima and upper media of normal arteries of atherosclerotic patients. The amount of deposits increased in fatty streaks. In atherosclerotic plaques, apolipoproteins accumulated around the necrotic material. These two apoproteins were present in the extracellular matrix as well as in the foam cells surrounding the atherosclerotic lesions. The concomitant intracellular localization of apolipoprotein A-I and of apolipoprotein A-II in the cytoplasm of foam cells supports the hypothesis that extracellular high-density lipoprotein particles are internalized in the macrophages during the atheromatous process.

Aged↗
PubMed1989

Diffuse fibrosis of the pancreas: a peculiar pattern of pancreatitis in alcoholic cirrhosis.

In order to evaluate the effects of chronic alcohol consumption on pancreas morphology we reviewed the autopsy data of 530 patients: 148 with liver alcoholic cirrhosis (group I), 39 with non alcoholic cirrhosis (group II), 47 autopsies of chronic alcohol drinkers without liver cirrhosis (group III) and 296 non alcoholic patients with normal liver, age and sex-matched with group I (group IV). In the control group (group IV) lipomatosis and intralobular fibrosis were common (57 percent and 40 percent) and increased with age. The prevalence of five elementary lesions (protein plug, dilatation of duct, epithelial atrophy, canalicular regression and perilobular fibrosis) and of one pathologic diagnosis (diffuse fibrosing pancreatitis) were higher in group I than in group IV. Duct lesions (protein plugs, canalicular regression and epithelial atrophy) were also significantly higher in drinkers without cirrhosis (group III) than in group IV. Chronic calcifying pancreatitis was rare (2 cases in group I). Thirty-six cases were classified as diffuse fibrosing pancreatitis. This constituted an homogeneous histopathologic group, significantly more frequent in the group of alcoholic cirrhosis, and was always discovered incidentally at autopsy. Because diffuse fibrosing pancreatitis might easily be confused with the morphological changes of chronic calcifying pancreatitis, we suggest to include this histopathologic entity into the Marseille's classification of pancreatitis.

Acute Disease↗
PubMed1988

Distribution of phospholipids around gramicidin and D-beta-hydroxybutyrate dehydrogenase as measured by resonance energy transfer.

A resonance energy transfer method was developed to study the distribution of phospholipids around integral membrane proteins. The method involved measuring the extent of energy transfer from tryptophan residues of the proteins to different phospholipids labeled with a dansyl moiety in the fatty acid chain. No specific interactions were observed between gramicidin and dansyl-labeled phosphatidylcholine, phosphatidylethanolamine, or phosphatidic acid. The results were consistent with a random distribution of each phospholipid in the bilayer in the presence of gramicidin. However, a redistribution of both gramicidin and dansyl-labeled phospholipids was easily observed when a phase separation was induced by adding Ca2+ to vesicles made up of phosphatidylcholine and phosphatidic acid. Polarization measurements showed that in the presence of Ca2+ a rigid phosphatidic acid rich region and a more fluid phosphatidylcholine-rich region were formed. Energy-transfer measurements from gramicidin to either dansylphosphatidylcholine or dansylphosphatidic acid showed gramicidin preferentially partitioned into the phosphatidylcholine-rich regions. Energy-transfer measurements were also carried out with D-beta-hydroxybutyrate dehydrogenase reconstituted in a vesicle composed of phosphatidylcholine, phosphatidylethanolamine, and phosphatidic acid. Although the enzyme has a specific requirement for phosphatidylcholine for activity, the extent of energy transfer decreased in the order dansylphosphatidic acid, dansylphosphatidylcholine, dansylphosphatidylethanolamine. Thus, the enzyme reorganized the phospholipids in the vesicle into a nonrandom distribution.

Dansyl Compounds↗