Biomedical subjects
P Germain
Publications and source records attributed to P Germain.
Neurohormonal profile before and after beta-blockade in patients with neurocardiogenic syncope.
Our objective was to evaluate the effects of beta-blockers on the neurohormonal profile, particularly vasopressin (VP) release, in vasovagal syncope and to gain further insight on the pathophysiology of this syndrome. Patients (< or =75 years) with no cardiovascular, neurological disorders, or contraindications to the use of isoproterenol or beta-blockers and being explored for unexplained syncope were included. An 80 degrees HUT was performed under identical conditions. After a 25-min period of passive tilt, isoproterenol was infused at a rate of 1-5 microg/mn if required. Two groups matched for age and sex were considered: a HUT-positive and a HUT-negative group. The HUT-positive group was then given beta-blockers, subsequently reassessed, and divided into two subgroups: alpha beta-blocker nonresponder group and a beta-blocker responder group. Blood samples for assays of norepinephrine (NE), epinephrine (E), and VP were taken at baseline and the end of the procedure. In all, 44 subjects entered the study, 22 in each group. The HUT-positive group exhibited an obvious lesser increase in plasma NE and a clear-cut rise in plasma E and VP compared to the HUT-negative group (P < 0.05). Even though no patient in the HUT-positive group reported recurrent symptoms under treatment, the second HUT could distinguish two subgroups: a beta-blocker nonresponder group (n = 12) whose HUT remained positive and a beta-blocker responder group (n = 10) whose HUT was normalized. The time course of plasma E and VP during the second HUT was similar to that for the HUT-positive and HUT-negative groups. In conclusion, the efficacy of beta-blockers is associated not only with a reduction of the sympathoadrenal stimulation seen in vasovagal syncope but also with a lower release of VP suggesting that low-pressure baroreceptors might be involved in VP release.
Modulation of lipid metabolism and spiramycin biosynthesis in Streptomyces ambofaciens unstable mutants.
Streptomyces ambofaciens is prone to genetic instability involving genomic rearrangements at the extremities of the chromosomal DNA. An amplified DNA sequence (ADS205), including an open reading frame (orfPS), is responsible for the reversible loss of spiramycin production in the mutant strain NSA205 (ADS205(+) Spi-). The product of orfPS is homologous to polyketide synthase systems (PKSs) involved in the biosynthesis of erythromycin and rapamycin and is overexpressed in strain NSA205 compared with the parental strain RP181110. As PKSs and fatty acid synthase systems have the same precursors, we tested the possibility that overexpression of orfPS also affects lipid metabolism in strain NSA205. This report focuses on comparative analysis of lipids in strain RP181110, the mutant strain NSA205, and a derivative, NSA228 (ADS205(-) Spi+). NSA205 showed a dramatically depressed lipid content consisting predominantly of phospholipids and triacylglycerols. This lipid content was globally restored in strain NSA228, which had lost ADS205. Furthermore, strains RP181110 and NSA205 presented similar phospholipid and triacylglycerol compositions. No abnormal fatty acids were detected in NSA205.
Myocardial bridging as a cause of acute transient left heart dysfunction.
The significance of myocardial bridging is still a matter of debate, and although several reports have underlined its pathologic potential, myocardial bridging is often considered to be a benign phenomenon. We present here the case of a 63-year-old woman with a history of acute left heart failure and ECG evidence of ischemia, and whose primary abnormality on extensive workup was myocardial bridging. This case further underlines that myocardial bridging can lead to significant cardiac events.
[Interdigital periarterial sympathectomy: treatment of severe and refractory Raynaud's phenomenon].
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Physiological investigations by image analysis.
Modern quantitative image analysis has been extensively used to characterize the morphology of microorganisms, especially those of the filamentous type. More recently physiological features have been quantified, making use of classical stains as well as fluorescent dyes. The potential of the technique is illustrated by a detailed analysis of the differentiation of Streptomyces ambofaciens. Three different staining procedures have been used to monitor the thinning and septation of hyphae (with propidium iodide staining), the leakage of cellular components through the membrane (with carbol gentian violet staining) and the respiration (with INT staining) in a batch submerged culture.
Effect of physical training on bone mineral density in prepubertal girls: a comparative study between impact-loading and non-impact-loading sports.
Physical activity is known to have an anabolic effect on bone tissue. It has been shown to increase the bone mineral density (BMD) in young adults, as well as in teenagers. But there is little information about the effect of intensive physical activity in childhood, particularly at the prepubertal stage. To examine the influence of an early intensive physical training on BMD, we have studied a group of elite prepubertal girls, at the starting phase of their peak bone mass acquisition. Subjects were engaged either in sport requiring significant impact loading on the skeleton, or in sport without impact loading. Forty-one healthy prepubertal girls took part in this study. The sport group consisted of 10 swimmers (10.5 +/- 1.4 years old) and 18 gymnasts (10.4 +/- 1.3 years old), who had performed 3 years of high-level sport training (8-12 h per week for swimmers, 10-15 h per week for gymnasts). Thirteen girls (10.7 +/- 1 years old) doing less than 3 h per week of physical activity served as a control group. BMD measurements were done using dual-energy X-ray absorptiometry. There was no statistical significant difference between groups as regards age, body height and weight, and body composition. There was no statistical significant difference between swimmers and controls for all the BMD measurements. Mean BMD in gymnasts was statistically higher than in the control group for mid-radius (+15.5%, p < 0.001), distal radius (+33%, p < 0.001), L2-4 vertebrae (+11%, p < 0.05), femoral neck (+15%, p < 0.001) and Ward's triangle (+15%, p < 0.01). Moreover, in gymnasts, BMD at radius, trochanter and femoral neck was above normative values. We conclude that physical activity in childhood could be an important factor in bone mineral acquisition in prepubertal girls, but only if the sport can induce bone strains during a long-term program: gymnastics has such characteristics, unlike swimming. Such acquisition could provide protection against risks of osteoporosis in later life, but this remains debatable.
Influence of temperature and pH on production of two bacteriocins by Leuconostoc mesenteroides subsp. mesenteroides FR52 during batch fermentation.
The influence of temperature and pH on growth of Leuconostoc mesenteroides subsp. mesenteroides FR52 and production of its two bacteriocins, mesenterocin 52A and mesenterocin 52B, was studied during batch fermentation. Temperature and pH had a strong influence on the production of the two bacteriocins which was stimulated by slow growth rates. The optimal temperature was 20 degrees C for production of mesenterocin 52A and 25 degrees C for mesenterocin 52B. Optimal pH values were 5.5 and 5.0 for production of mesenterocin 52A and mesenterocin 52B respectively. Thus, by changing the culture conditions, production of one bacteriocin can be favoured in relation to the other. The relationship between growth and specific production rates of the two bacteriocins, as a function of the culture conditions, showed different kinetics of production and the presence of several peaks in the specific production rates during growth.
Does the 6-minute walk test predict the prognosis in patients with NYHA class II or III chronic heart failure?
BACKGROUND: We prospectively evaluated the potential of the 6-minute walk test compared with peak VO2 in predicting outcome of patients with New York Heart Association (NYHA) class II or III heart failure. METHODS AND RESULTS: Patients with a history of heart failure caused by systolic dysfunction were included. The combined final outcome (death or hospitalization for heart failure) was used as the judgment criterion. One hundred twenty-one patients (age 59+/-11 years; left ventricular ejection fraction 29.6%+/-13%) were included and followed for 1.53+/-0.98 years. Patients were separated into two groups according to outcome: group 1 (G1, 74 patients), without events, and group 2 (G2, 47 patients), who reached the combined end point. Peak VO2 was clearly different between G1 and G2 (18.5+/-4 vs. 13.9+/-4 ml/kg/min, p=0.0001) but not the distance walked (448+/-92 vs 410+/-126 m; p=0.084, not significant). Survival analysis showed that unlike peak VO2, the distance covered was barely distinguishable between the groups (p < 0.08). However, receiver operating characteristic curves revealed that the best performances for the 6-minute walk test were obtained for subjects walking < or =300 m. These patients had a worse prognosis than those walking farther (p=0.013). In this subset of patients, there was a significant correlation between distance covered and peak VO2 (r=0.65, p=0.011). Thus it appears that the more severely affected patients have a daily activity level relatively close to their maximal exercise capacity. Nevertheless, the 300 m threshold suggested by this study needs to be validated in an independent population. CONCLUSIONS: A distance walked in 6 minutes < or =300 m can predict outcome. Moreover, in these cases there is a significant correlation between the 6-minute walk test and peak VO2 demonstrating the potential of this simple procedure as a first-line screening test for this subset of patients.
[The uterus does not explain everything].
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[MRI semeiology of segmental contraction abnormalities in arrhythmogenic dysplasia of the right ventricle].
The diagnosis of localized arrhythmogenic right ventricular dysplasia may be difficult to ascertain. Aside from electrophysiological arguments, visualization of an abnormal right ventricular contraction pattern is of crucial importance for diagnosis. Cine-MR is almost the only examination method which offers detailed informations on the right ventricular contraction pattern. Nine observations of segmental right ventricular contraction abnormalities assessed by cine-MR are described here: dyskinesia of the distal part of the anterior wall (2), of the inferior wall (2), of the right ventricular outflow tract (2); akinesia of the outflow tract (2) and of the inferior wall (1). Morphological abnormalities of the right ventricle are always associated with contraction abnormalities but seem to be less disease specific. Patients should be more readily referred for a cine-MR examination when the diagnosis of localized right ventricular dysplasia is suspected. Cine-MR sequences related to these observations may be reached via Internet at:http:@alsace.u-strasbg.fr/cardio/coeur.htm.
Engineered cell lines as a tool for monitoring biological activity of hormone analogs.
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Diltiazem slow-release and left-ventricular hypertrophy: a volumetric approach of left ventricular mass using magnetic resonance imaging.
AIMS: This study was designed to assess the changes in left ventricular mass (LVM) in hypertensive patients with left ventricular hypertrophy under drug therapy with once-daily slow-release diltiazem. Magnetic resonance imaging (MRI) was used for this purpose because of its higher reproducibility than M-mode or two-dimensional echocardiography. METHODS: Patients suffering from essential hypertension were included if their baseline LVM index (LVMI) was > or = 105 g/m2 in male or > or = 85 g/m2 in female patients, ie, equal or higher to the median values observed in hypertensive patients in our institution. MRI consisted in a true short-axis, electrocardiogram (ECG) gated spin-echo slice acquisition at baseline, after 3 and 6 months of therapy (M0, M3, and M6). Data were stored on magnetic tapes and read subsequently under blind conditions and the control of an external auditor. RESULTS: Thirty-five patients were included. Of these, 14 patients (40%) were not previously treated. Inter- and intra-observer variability for LVMI measurement were 5.6 +/- 4.3% and 2.1 +/- 3.0%, respectively. Mean baseline LVMI was 110 +/- 16 g/m2 in male and 96 +/- 16 g/m2 in female patients. It decreased by 3.6% at M3 (P = 0.05) and by 6.0% at M6 (P = 0.02). A trend towards a greater LVMI reduction was observed in previously untreated patients. CONCLUSION: This study confirms that MRI is a reproducible technique for the measurement of LVM. It demonstrates a significant reduction in LVMI as early as the 3rd month of therapy in hypertensive patients treated with once-daily sustained release (SR) diltiazem, although baseline LVMI in the majority of participating patients was only moderately increased.
Use of confocal microscopy to localize the SHBG interaction with human breast cancer cell lines--a comparison with serum albumin interaction.
This work has allowed a comparison between the interaction of two principal plasma estradiol-binding proteins, serum albumin and Sex Hormone Binding Globulin (SHBG), with human breast cancer cells in culture (MCF-7 and MDA-MB 231), using a protocol which protects the integrity of cell structure. We showed that serum albumin was highly internalized by cells whereas SHBG interacted essentially at the plasma membrane level, and this whatever the contents of the receptor estrogen cells. If, by its high plasma concentration, serum albumin is internalized in a non-specific way and can thus fit into intracellular traffic, SHBG, by its membrane binding, seems to have a specific action toward target cells.
Regulation of spiramycin synthesis in Streptomyces ambofaciens: effects of glucose and inorganic phosphate.
The production of the 16-membered macrolide antibiotic, spiramycin, in Streptomyces ambofaciens is inhibited by glucose, 2-deoxyglucose and inorganic phosphate. The role of intracellular ATP content and phosphorylated metabolites as common regulating signals of both glucose and phosphate inhibitory effects is discussed. Two enzymatic targets of the effect of phosphate on spiramycin biosynthesis were studied. Valine dehydrogenase, the first enzyme of valine catabolism (supplier of aglycone spiramycin precursors), and alkaline phosphatase, which cleaves phosphorylated intermediates, were repressed in the presence of excess phosphate.
Identification of 137Cs-and 241Am-binding sites in the oyster Crassostrea gigas.
The subcellular distribution and binding of 241Am and 137Cs in the visceral mass of the oyster Crassostrea gigas were investigated following exposure to sea water contaminated with these radionuclides. 241Am was predominantly sequestered by the lysosomal system. Approximately, 10% of 241Am was associated with soluble macromolecules. 241Am was bound to lipofuscin, ferritin and to unidentified ligands of 60 to 15 kdaltons mol. wt. No evidence was found for binding of 241Am to metallothionein synthesized de novo. In contrast, only small amounts of 137Cs were present in lysosomes and 137Cs was not associated with soluble cellular proteins. These results indicate that they enter complete separate metabolic pathways.
Comparison between abnormalities in segmental endocardial motion and abnormalities in segmental wall thickening after anterior myocardial infarction. A cine-magnetic resonance study.
In this study, two patterns of regional contract on of the left ventricle have been studied: endocardial motion and wall thickening, in order to check which of these was the most affected after myocardial infarction. The clinical relevance of this comparison was to assess which parameter of the regional contraction abnormality would best depict the severity of the infarction. Long axis cine-magnetic resonance slices were used to assess segmental systolic left ventricular endocardial motion and segmental systolic wall thickening in 39 normal subjects and in 30 patients at the chronic stage of an anterior myocardial infarction. In the group of normal subjects, endocardial motion and wall thickening showed significant regional heterogeneity. Overall endocardial motion was greater than overall wall thickening: 9.5 +/- 2.0 mm vs 7.1 +/- 1.8 mm. P = 4 x 10(-12) (3.1 +/- 1.2 mm vs 2.0 +/- 0.7 mm, P = 9 x 10(-5) after infarction). A significant linear correlation was found between these two parameters. In the infarction group, abnormality scores for endocardial motion and for wall thickening were calculated. These scores were defined as the average values exceeding the mean minus two standard deviations of the normal range for segments corresponding to the antero-septal-apical walls. The abnormality score for endocardial motion greater than the abnormality score for wall thickening: 0.31 +/- 0.12 vs 0.20 +/- 0.07, P = 9 x 10(-4). We conclude that, in clinical practice, endocardial motion is affected to a greater degree by myocardial infarction than is wall thickening and therefore constitutes a more discriminant index in the assessment of post-infarction patients.
[Multifocal choroiditis associated with herpes zoster ophthalmicus. Apropos of a case].
We describe a patient with multifocal choroidal lesions affecting the midperipheral fundus, with an atrophic and scattered punched-out pale aspect. Lesions were discovered seven months after an ipsilateral herpes zoster ophthalmicus. Fluorescein angiography findings exhibited a delay of choroidal injection and late moderate staining during the venous phase. The etiological arguments refer to a previous herpes zoster infection. The pathogeny would involve an occlusion of posterior ciliary arteries, lesions of posterior ciliary nerves and/or direct cytopathogenic involvement of chorioretina by neurotropic virus from ciliary ganglion.