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Biomedical subjects

M Vincent

Publications and source records attributed to M Vincent.

At least 199 records · Page 11Linked to original sources
PubMed1991

[Cervicogenic headache: report of a case].

It has been known for many years that headaches can originate from abnormalities in the neck. However, their clinical pictures were never sufficiently systematized, at least not in order to permit the research on their pathogenesis. Sjaastad et al. described in 1983 a group of patients with a very uniform and stereotyped headache. Attacks of mild, longlasting, unilateral head pain without sideshift, occurred every few weeks. The headache could be provoked by neck movements, such as extension, rotation or lateral flexion, as well as by external pressure towards trigger points in the neck. It usually started back in the neck, eventually spreading to the ipsilateral orbito-frontal-temporal or facial areas. The denomination "cervicogenic headache" (CH) was proposed. Its pathophysiology is presently unknown. The C2 and occipital nerve blockages eliminate the pain. We present a CH case and make some comments on its clinical picture, pathophysiology, and treatment.

Adult↗
PubMed1991

[Renal function during stress in hypertensive patients].

In this study, the measurement of blood pressure values, glomerular filtration rate (GFR, inulin clearance), renal plasma flow (RPF, PAH clearance), the filtration fraction (GFR/RPF), natiuresis and proximal sodium resorption (measured by lithium clearance), was performed at rest and during a computerised psychological stress test (Stroop word color conflict test) in 12 normotensive and 10 hypertensive subjects. The stress induced in the normotensives induced a significant increase of the filtration fraction and proximal tubule sodium resorption. The hypertensive kidney, submitted to a basal vasoconstriction greater than that of the normotensive kidney, does not react to stress. In the hypertensives, proximal sodium resorption occurs but is not significantly greater than at rest. In the long-term, the increased sodium resorption during stress could contribute to the development and the persistence of essential hypertension.

Adult↗
PubMed1991

[Role of sympathetic nervous system on blood pressure and heart rate variabilities in the rat: spectral analysis].

The role of the sympathetic nervous system (SNS) in the genesis of the beat-to-beat variability of blood pressure (BP) and heart rate (HR) was studied using spectral analysis. The SNS activity of genetically normotensive rats of the Lyon strain (LN) was abolished in 2 ways: 1) adrenergic blockade with administrations of phentolamine (PHE, 5 mg/kg i.v.) or propranolol (PRO, 5 mg/kg i.v.) or both drugs (PHEPRO) or 2) destruction of the sympathetic fibers with an early chronic treatment with guanethidine (LNSx). HR and systolic (SBP) and diastolic (DBP) BP spectra were computed using 50 to 100 stationary sequences from 1 h beat-to-beat recordings and covered the 0.015-3.85 Hz frequency band. In LN rats, spectra obtained in baseline conditions exhibited a high-frequency peak (HF, 1.04-1.13 Hz) related to the respiratory frequency and a mid-frequency peak (MF, 0.38-0.45 Hz). Concerning BP, the alterations of the SNS induced significant decreases of the total modulus (mmHg/Hz1/2) of the MF band (0.27-0.74 Hz): [formula: see text] In addition, the MF peak of SBP and DBP spectra was abolished in LNSx and PHEPRO rats. Concerning HR spectra, the moduli of all the frequency components were decreased in PHEPRO rats only. In conclusion, the similarity of the results observed in LNSx and PHEPRO rats shows that the MF oscillations of BP depend in a large extent (65%) on the action of the sympathetic fibers and involve the activation of both alpha- and beta-adrenoceptors. Concerning DBP, this effect is especially mediated by the activation of alpha-adrenoceptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[Renin secreting tumor and severe hypertension. Apropos of a new case].

A renin-secreting tumour has been observed in a 32-year-old female with severe hypertension known for 17 years. The excision of the tumour lead to the complete normalisation of the blood pressure. Histological examination showed that the tumour was benign, contained secretion granules at different stages of maturation, and derived from the juxta-glomerular apparatus. After reviewing the 40 cases previously reported in the literature we discuss the clinical presentation of this type of tumour and the approach to their diagnosis.

Adult↗
PubMed1990

Time-resolved fluorescence of the single tryptophan residue in rat alpha-fetoprotein and rat serum albumin: analysis by the maximum-entropy method.

The time-resolved fluorescence emissions of the lone tryptophan residues in rat alpha-fetoprotein (RFP) and rat serum albumin (RSA) were studied. The total fluorescence intensity decays in both proteins were multiexponential. Analysis of the data by nonlinear least squares as a sum of discrete exponentials showed that four exponentials were needed for a satisfactory fit for both proteins. Analysis by the maximum entropy method using 150 logarithmically equally spaced exponentials yielded four well-resolved excited-state lifetime classes with barycenters and relative amplitudes values (ci) that corresponded to those obtained from the nonlinear least-squares method. Changing the temperature affected the relative amplitudes of the lifetime classes but had little effect on the lifetime values themselves. This suggests that the four classes reflect local conformational substates that exchange slowly with respect to the time window of observation defined by the longest lifetime. The internal rotational dynamics of the tryptophan in each protein was monitored by fluorescence anisotropy decay measurements. The mobility of the tryptophan appeared to be larger and faster in RFP than in RSA. The nonlinear least-squares analysis suggests the existence of three rotational correlation times of 0.1, 3, and 55 ns for this protein. As a function of temperature, the long correlation time did not follow the Perrin's law expected for a rigid rotating body. This suggests that this correlation time may reflect not only the Brownian rotation of the whole protein but also the flexibilities of domains in the protein. For RSA a two-component model with correlation times of 0.4 and 31 ns was sufficient to describe the data.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Diagnosis of perceptive deafness in adults].

The finding of perception deafness in an adult patient should set off full clinical and paraclinical evaluation, as this symptom may hide two problems requiring urgent attention. The first problem concerns the diagnosis: any unilateral and progressive perceptive deafness suggests a possible acoustic neurinoma. The second problem is one of therapeutic decision, since in all patients with sudden onset deafness the prognosis depends on an early treatment. General practitioners can use simple tests that will give them some indications on the severity of the loss of hearing, but to establish the side and cause of the deficit, additional and highly specialized examinations are always needed. Medical and hearing aids are sufficient in most patients. Surgery should be reserved to very special cases and will be contemplated or not, depending on the cause of the deafness.

Adult↗
PubMed1990

Transient expression of an intermediate filament-associated protein (IFAPa-400) during in vivo and in vitro differentiation of chick embryonic cells derived from neuroectoderm.

The expression of an intermediate filament (IF) associated protein (IFAPa-400) and IF proteins was investigated during chick neurogenesis. Using immunoblots and indirect immunofluorescence we have found that IFAPa-400 was strongly expressed during the early events of nervous tissue ontogenesis and disappeared thereafter. IFAPa-400 was elevated in the brain and retina until ED 10 and until hatching in the cerebellum. This protein was shown to be transiently expressed in the Müller glia of the developing retina. In the brain, IFAPa-400 decreased as development proceeded in a way similar to vimentin but the latter remained elevated in the retina and the cerebellum radial glia (Müller and Bergmann cells). In all tissues examined, GFAP was detected long after the disappearance of IFAPa-400. In dorsal root ganglion cell cultures, IFAPa-400 and vimentin were absent from mature neurons but were coexpressed into supportive cells. In trunk neural crest cell cultures, IFAPa-400 and vimentin were present in all cells after one day but IFAPa-400 became undetectable after a few days of culture in differentiated melanocytes and catecholaminergic neurons. The transient expression of this giant cytoskeletal protein in non-differentiated cells deriving from the neuroectoderm could reflect a structural change which precedes overt cytodifferentiation.

Animals↗
PubMed1990

Maintenance treatment of patients with myelodysplastic syndromes using recombinant human granulocyte colony-stimulating factor.

Myelodysplastic syndromes (MDS) are characterized by chronic refractory cytopenias resulting in increased risk of infection, bleeding, and conversion to acute leukemia. In an effort to improve these cytopenias we have treated 18 patients over a 6- to 8-week period with increasing daily subcutaneous doses of recombinant human granulocyte colony-stimulating factor (G-CSF). Sixteen patients responded with improvement in neutrophil counts. On cessation of treatment these counts returned to baseline values over a 2- to 4-week period. To maintain these improved blood counts 11 patients were treated with G-CSF for more prolonged periods. Ten patients again responded with an increase in total leukocyte counts (1.6- to 6.4-fold) and absolute neutrophil counts (ANC) (3.6- to 16.3-fold), with responses persisting for 3 to 16 months. A significantly decreased risk of developing bacterial infections was noted during periods with ANC greater than 1,500/mm3 as compared with periods of time with ANC less than 1,500/mm3. Two anemic patients had a greater than 20% rise in hematocrit over the study period, and 2 additional patients had a decrease in red blood cell transfusion requirements during G-CSF treatment. Bone marrow myeloid maturation improved in 7 of 9 maintenance phase patients. Three patients progressed to acute myeloid leukemia during treatment. The drug was generally well-tolerated and no severe toxicities were noted. These data demonstrated that G-CSF administered to MDS patients by daily subcutaneous administration was well-tolerated and effective in causing persistent improvement of the neutrophil levels and marrow myeloid maturation. These effects were associated with a decreased risk of infection and, in some patients, with decreased red blood cell transfusion requirements.

Colony-Stimulating Factors↗
PubMed1990

Relation between membrane phospholipid composition, fluidity and function in mitochondria of rat brown adipose tissue. Effect of thermal adaptation and essential fatty acid deficiency.

Male weanling rats were maintained either at 28 degrees C (thermoneutrality) or at 5 degrees C (cold adaptation). During 9 weeks they were fed either a 2% hydrogenated coconut oil diet deficient in essential fatty acids or a diet containing 2% sunflower oil. The respective incidences of cold adaptation and of EFA deficiency on lipid composition of mitochondrial membranes from brown adipose tissue (BAT) were investigated. Using 1,6 diphenylhexatriene (DPH) as a probe, the parameters of membrane fluidity were estimated by steady-state fluorescence polarization measurements (rs) and by time-resolved fluorescence anisotropy decay (order parameter S). Cold acclimation induced a decrease of phosphatidylcholine to phosphatidylethanolamine (PC/PE ratio), an increase of the total fatty acid unsaturation index (T.U.). EFA deficiency had the same effect as cold on the PC/PE ratio, but decreased T.U. Cold adaptation induced a larger decrease of S than of rs, whereas EFA deficiency only increased rs and did not modify S. In liposomes prepared from mitochondrial lipids, rs values were smaller than in whole mitochondria. Both in cold-adapted and in EFA-deficient rats the variations of rs were correlated with lipid unsaturation. Comparison between BAT thermogenic activity, assessed by GDP binding and proportions of PE and PC showed a high correlation suggesting a change in the membrane occurring with the increase of mitochondrial activity that could be related to phospholipid composition rather than to membrane fluidity.

Adaptation, Physiological↗
PubMed1990

Effects of prolonged treatment of myelodysplastic syndromes with recombinant human granulocyte colony-stimulating factor.

In vitro marrow hemopoietic cultures were utilized to determine the possible efficacy of recombinant human granulocyte colony-stimulating factor (G-CSF) for treating the refractory cytopenias present in the myelodysplastic syndromes (MDS). Our studies showed responsiveness of enriched hemopoietic precursors in vitro to the proliferative and granulocytic differentiative stimuli of G-CSF, generally without increased clonal self-generation. These in vitro parameters correlated with in vivo hematologic responses in our Phase I and II clinical trials. In this study 18 patients were treated for two months with s.c. administration (0.1-3 micrograms/kg/day) of G-CSF, escalating doses every two weeks. This study indicated normalization of neutrophil courses in 16 patients and reticulocyte responses with decreased red blood cell (RBC) transfusion requirements in three of 12 transfusion-dependent patients. Marrow myeloid maturation improved in the responding patients. Extended treatment for additional six- to 16-month periods has indicated persisting neutrophil responses. The relative risk of developing bacterial infections was significantly decreased in patients whose neutrophil level normalized (absolute neutrophil count greater than 1,500/mm3) during G-CSF therapy, compared to such episodes in their pretreatment neutropenic period. This therapy was well-tolerated, without serious toxicity being noted. In vitro neutrophil function (chemotaxis and phagocytosis) remained normal or improved in six of the eight tested patients. Transformation to acute myelogenous leukemia occurred in two patients with refractory anemia with excess blasts in transformation (RAEB-T) during or within a month of the treatment period. Marrow cytogenetic studies indicate persistence of the initial normal and/or abnormal clones.(ABSTRACT TRUNCATED AT 250 WORDS)

Colony-Stimulating Factors↗
PubMed1990

The value of computed tomographic (CT) scan surveillance in the detection and management of brain metastases in patients with small cell lung cancer.

One hundred and twenty-seven consecutive patients presenting with small cell lung cancer were entered into a whole-brain CT scan surveillance study, starting at presentation and repeating at 3-monthly intervals for 2 years as an alternative to prophylactic cranial irradiation (PCI). The aim of the study was to detect CNS metastases at an early asymptomatic stage in the hope that prompt CNS radiotherapy could achieve long-term control; at the same time unnecessary PCI with its potential long-term morbidity could be avoided. CNS metastases were found in 56 patients (44%) including 16 (13%) at diagnosis and 40 at a median of 4 months (range 1-27 months) after completing chemotherapy. No patient developed CNS disease while on chemotherapy. Thirty-six patients were asymptomatic at diagnosis (group A) but 20 developed clinical CNS relapse between scans (group B) (interval relapse). Despite prompt radiotherapy 56% of patients in group A and 60% of patients in group B died with active CNS disease. Likewise, there was no survival difference between patients in group A, group B or those who never developed CNS disease. Regular 3-month CT scan surveillance is therefore not an effective substitute for PCI.

Brain Neoplasms↗
PubMed1990

Dietary calcium, vascular reactivity, and genetic hypertension in the Lyon rat strain.

In order to examine the relationship existing between dietary calcium and the development of hypertension, we developed a long-term study in the Lyon hypertensive rat strain (LH) and two control strains, the Lyon normotensive (LN) and low blood pressure rats (LL) given enriched (HCa, 2.5%), deprived (LCa, 0.03%) and normal (NCa, 0.6%) calcium diets. Evolution of body weight, systolic blood pressure (BP), plasma calcium and magnesium was monitored from 4 to 23 weeks of age. Total cardiovascular reactivity and contractile response of isolated aorta to norepinephrine were measured at 23 weeks of age. LH rats on HCa diet failed to develop hypertension (BP less than 150 mm Hg) whereas LH rats on LCa diet exhibited higher blood pressure levels than their controls fed the NCa diet. Moreover, in LN rats HCa diet slightly decreased BP whereas LCa had no effect. In the LL rats, on the contrary, only LCa diet slightly increased BP. In vivo responsiveness to NE was significantly higher in LH compared to LL and LN rats fed a NCa diet. HCa and LCa diets both induced a significant decrease in this response in LH rats. HCa diet increased the response in LN rats but decreased it in LL. In contrast, at the same age, the in vitro contractile response of isolated aorta to NE was significantly decreased in LH compared to LN and LL rats receiving NCa diet. Moreover in LH and LN rats on HCa diet the contractile response was markedly increased but no significant difference was observed with LCa diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Analysis of the renin gene intron A tandem repeat region of Milan and Lyon hypertensive rat strains.

The region of intron A of the rat renin gene containing a unique tandemly repeated sequence was analysed in the Milan and Lyon hypertensive rat strains and their controls, and in several Sprague-Dawley rats, using an oligonucleotide probe complementary to the tandemly repeated sequence and a renin complementary DNA probe. In the Milan rats, the size of the Bgl II DNA fragment encompassing the tandem repeat region was the same in the hypertensive (MHS) and normotensive (MNS) strains. In the Lyon model, a difference of 1.1 kilobase (equivalent to about 28 copies of the 38 basepair tandem repeat sequence) was observed in the size of the Bgl II fragment of the hypertensive (LH) and normotensive (LN) strains. However, the finding that the size of the fragment in the Lyon low-blood-pressure (LL) strain was the same as that in the LH strain rather than the LN strain suggests that the difference between the two latter strains is not by itself a major cause of the blood pressure difference between them in the intron A tandem region. An analysis of Sprague-Dawley rats, from which the Lyon strains are derived, showed that at least three different renin gene alleles, two with Bgl II fragments of the same size as those seen in the Lyon strains, are randomly segregating in this population.

Alleles↗
PubMed1990

Parathyroidectomy in the Lyon hypertensive rat: cardiovascular reactivity and aortic responsiveness.

We have studied the effect of parathyroidectomy on the systolic blood pressure, cardiovascular reactivity and the contractile response of isolated aorta to norepinephrine in the genetically hypertensive Lyon rat strain (LH), parathyroidectomized hypertensive Lyon rats (LH-PTX) and parathyroidectomized hypertensive Lyon rats given a Ca-enriched diet to re-establish normocalcemia (LH-PTX + Ca). Parathyroidectomy significantly lessened (-20%) the development of elevated blood pressure. In the LH-PTX + Ca, the blood pressure was lower than that of LH controls but was higher than that of LH-PTX. At 23 weeks, in vivo responsiveness to norepinephrine and angiotensin II was significantly lower in the LH-PTX and only slightly decreased in the LH-PTX + Ca. In contrast, at the same age, the in vitro contractile response of isolated aortas to norepinephrine was significantly higher in the LH-PTX compared with other groups. Interestingly, without endothelium, this difference disappeared. In conclusion, parathyroidectomy lessened the blood pressure elevation in the Lyon model of hypertensive rats via mechanisms that are partly independent of serum calcium levels.

Animals↗
PubMed1990

Effects of swim training alone and in combination with clonidine and rilmenidine on blood pressure, plasma electrolytes, vasopressin, and renin activity in spontaneously hypertensive rats.

Adaptations to the effects of clonidine (CL) and rilmenidine (R) were studied during a 12-week training program (swimming) in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. Systolic blood pressure (SBP) was regularly measured during this period. Body weight (BW) was determined at the beginning and at the 12th week. Plasma parameters, cardiac determinations, vasopressin (pAVP), and plasma renin activity (PRA) were measured only at the end of the experiment. Both SBP and ponderal benefit were reduced by CL, R, and training. Contrary to beta-adrenoceptor blocking agents, we found no inhibition of the beneficial effect on SBP of training in combination with CL or R. Plasma and hypothalamic vasopressin were reduced by both drugs but only CL increased plasma renin activity (PRA) although its mechanisms of action are still not clearly understood. Our results suggest that CL and R as well as swim training can be considered as an effective countermeasure in SHR. Moreover, the heterogeneity of action of CL and R on some of the parameters tested is in favor of different pharmacological properties for these drugs.

Adrenergic alpha-Agonists↗