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Biomedical subjects

F Masson

Publications and source records attributed to F Masson.

At least 37 records · Page 2Linked to original sources
PubMed1997

Effects of physico-chemical factors influencing tyramine production by Carnobacterium divergens.

Tyramine production by a strain of Carnobacterium divergens was tested in relation to different conditions of pH, temperature, glucose, oxygen availability, potassium nitrate and sodium chloride content, using a combination of a Doehlert and Plackett-Burman experimental design. A second degree polynomial model was chosen to describe tyramine production which was quantified by high performance liquid chromatography. Maximal tyramine production occurred during the stationary phase in acidic conditions obtained by low initial pH (< 5) or addition of glucose (0.6%) to the medium. Production was slower at 5 degrees C than at 23 degrees C and 10% sodium chloride inhibited this production. However, the formation of tyramine was not affected by the presence of potassium nitrate or oxygen availability.

Bacteriological Techniques↗
PubMed1997

Injuries in a problematic socioeconomic context: a population-based study in Réunion, Indian Ocean, 1993-1994. GEAR. Groupement d'Etude sur les Accidents à la Réunion.

BACKGROUND: This study was designed to estimate the incidence and describe the characteristics of injuries during a one-year period in the French island of Réunion, Indian Ocean, a defined geographic population with socioeconomic problems. METHODS: Cases were injuries from accidents (unintentional injuries), self-inflicted injuries (suicides and attempted suicides), or injuries purposely inflicted by other people, that resulted in hospital admission or death. Patients and injury characteristics were recorded prospectively, alternately every other week, in all emergency rooms on the island; all death certificates were studied. RESULTS: The overall annual incidence of injuries was 1578 per 100,000 residents. The three main causes of injury were (i) falls on the same level (23.6%), (ii) poisoning (23.0%) and (iii) traffic accidents (21.5%). Of the traffic accident cases, 44% were motorcyclists (mostly mopeds) and more than half of the cases were 15-25 years old. Suicides and attempted suicides accounted for 80.9% of poisonings, 35.5% of immediately fatal injuries, and 19.6% of non-fatal injuries. Homicides and assaults accounted for 8.3% of all injuries. The employment rate was lower for injured patients than in the total Réunion population (standardized ratio for males: 74; P < 0.001). Half of the injured hospitalized patients had an Injury Severity Score < 5 and 8 days after hospitalization, 83.5% of patients had returned home. CONCLUSION: Injury epidemiology may be affected by different demographic, socioeconomic, cultural and geographical factors. Targeted studies are therefore necessary to guide injury prevention measures.

Adolescent↗
PubMed1997

Angiotensin II-induced phosphoinositide production and atrial natriuretic peptide release in rat atrial tissue.

The effect of angiotensin II (Ang II) on inositol phosphate (IP) production and atrial natriuretic peptide (ANP) release was studied in sliced rat atrial tissue. The ability of Ang II (10(-7) M) to stimulate IP accumulation was detected after 1 min of incubation, and the maximal increase was observed at 5 min. In (2-3H) inositol-labeled atrial tissue, Ang II induced the formation of (2-3H) inositol monophosphate (IP1) in a dose-dependent manner. The effect of Ang II (10(-7) M) on IP1 was prevented by losartan (10(-7) M) but was not affected by PD123319 (10(-7) M). Similar effects were observed on Ang II-induced ANP release in the presence of these antagonists. The mechanism of ANP liberation induced by this peptide was independent of cyclic adenosine monophosphate (cAMP) and regulated by nitric oxide (NO). The role of Ca2+ in the effect of Ang II was tested by 1,2-bis (o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid tetra (acetoxymethyl) ester (BAPTA-AM; 10(-5) M), a chelator of intracellular Ca2+ that prevented the release of ANP by Ang II stimulation. We concluded that Ang II induced IP production and ANP release through AT1 receptors. Stimulation of ANP release by Ang II was dependent on intracellular Ca2+.

Angiotensin II↗
PubMed1996

Cellular mechanism of angiotensin II-induced atrial natriuretic peptide release in rat right atrial tissue.

This study presents an investigation of the mechanism of angiotensin II (Ang II)-induced atrial natriuretic peptide (ANP) release in superfused sliced right atria of rats. Ang II (0.1 microM) enhanced ANP release by 49%. This phenomenon was significantly blocked by (Sara1-Ileu 8) Ang II (1 microM) and losartan (0.1 microM). The use of neomycin (100 microM), a phospholipase-C inhibitor completely suppressed the effect of Ang II on ANP increase. To elucidate the intracellular mechanism of ANP released by Ang II, the role of protein kinase C (PKC) was determined by 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7) and phorbol ester : 4-beta-phorbol 12-myristate-13-acetate (PMA). We observed that PMA (0.1 microM) stimulated ANP release whereas H-7 (10 microM), an inhibitor of PKC in the presence of Ang II, prevented ANP increase. The role of calcium was also evaluated with 8-(N-N-diethylamino)-ocytyl-3,4,5, trimethoxy-benzoate (TMB-8) (10 microM) and N-(6-aminohexyl)-5-chloro-1-naphtalene sulfonamide (W-7) (10 microM), which completely inhibited ANP release by Ang II. Pre-treatment with diltiazem (10 microM), an antagonist of the Ca++ channel, did not prevent ANP increase due to Ang II, but A23187 (5 microM) enhanced ANP release by Ang II. These results suggest that PKC and intracellular calcium play an important role in ANP release under the influence of Ang II in rat atrial tissue.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1996

Histamine and tyramine production by bacteria from meat products.

A series of 94 strains of lactic acid bacteria and Micrococcaceae were tested for their ability to decarboxylate histidine and tyrosine in a laboratory medium. Histamine and tyramine were quantified by using a fluorimetric and a HPLC method. There was no significant difference between the results obtained with either method. Among the strains tested, only three released histamine. On the other hand, all the strains of Carnobacterium produced high concentrations of tyramine (2193 micrograms/ml). Some strains of Lactobacillus curvatus and also Lactobacillus plantarum showed tyramine production. Micrococcaceae and Lactobacillus sake did not produce tyramine.

Chromatography, High Pressure Liquid↗
PubMed1996

[Characteristics of head trauma in children: epidemiology and a 5-year follow-up].

BACKGROUND: Accidents are the major cause of morbidity and mortality in children. The aim of this population-based study was to describe characteristics of head injuries leading to hospitalization in children less than 15 years old, in a defined geographic population (Aquitaine: 2.7 millions inhabitants) and the longterm outcome (5-year follow up) of a sample of these patients. PATIENTS AND METHODS: Hospitalized patients, residents of the region, were included in a prospective study during 13 weeks spread over the whole year in 1986 in all emergency services of the region. The follow-up study concerned patients hospitalized in 3 hospitals (a trauma I level center, a pediatric hospital and a general hospital), with a sampling frame taking into account the overall injury severity. Impairments, disabilities and handicaps were assessed with a structured questionnaire five years later and results in children compared with those of adults. RESULT: Annual incidence of hospitalized head injuries in children was 294/100,000 inhabitants. The lethality was 0.3% in hospitalized patients. Ninety-two percent of head injuries were minor. In the youngest patients, the most frequent circumstances were a fall at home. The traffic accidents rate increased with age from 14% to 53% in the 10-14 years old children. Five years later, 104 children were reviewed (83 minor and 21 moderate or severe head injuries). Children complained less often of somatic symptoms than adults. Two children had disabilities in daily life activities, including one whose minor head injury eventually worsened and one after a very severe brain injury. According to the Glasgow Outcome Scale three patients had a poor recovery (2 severe and 1 moderate disability). CONCLUSIONS: Origin and mechanisms of head injuries in childhood were similar than in previous studies. Incidence was higher because of a higher proportion of minor head injuries. Disabilities and poor recovery happened in children with brain lesions or in one children with a minor head injury complicated by a severe anoxia. Anxiety and depression should be better studied in these children.

Adolescent↗
PubMed1996

Prevalence of impairments 5 years after a head injury, and their relationship with disabilities and outcome.

To determine what consequences cognitive, behavioural or somatic impairments had on disabilities and recovery after a head injury (HI), a population-based sample of 231 adult patients was studied 5 years after an HI. Eighty lower-limb-injured (LLI) patients were considered as controls. Sixty-four LLI and 176 HI patients were reviewed (114 minor, 35 moderate, and 27 severe HI). Prevalence values of headaches (44-54%), dizziness (26-37%), and anxiety (47-63%) were not significantly different in the three HI severity groups, but were significantly lower in patients with an isolated limb injury (12-15%). Memory problems and depressive mood increased with injury severity. Mental impairments were frequent in severe HI patients (18-40% of patients). In minor and moderate HI patients, most disabilities were related to associated injuries. According to the Glasgow Outcome Scale (GOS), recovery was not considered as good because of somatic, behavioural or cognitive complaints in 2.5%, 5.7% and 59.2% of surviving patients in each of the above HI groups. Somatic or behavioural complaints may have considerable consequences in some minor HI patients, and the long-term management of certain patients needs improvement because these impairments are misunderstood.

Adolescent↗
PubMed1996

Cloning of a cDNA encoding a developmentally regulated 22 kDa polypeptide from tobacco leaf plasma membrane.

A polypeptide doublet (P18-P19, ca 22 kDa, pI 4.5) has been shown to accumulate in tobacco leaf plasma membrane in a development-dependent way, under constant environmental conditions. P18 and P19 were purified by 2D-PAGE and microsequenced. Microsequences revealed only small differences between the two polypeptides. A PCR-based cloning strategy identified a cDNA displaying a 591 bp ORF. The encoded polypeptide contained P19 specific microsequences. It was expressed in E. coli and a specific rabbit antiserum was raised. Western-blots confirmed its identification as P19. The accumulation pattern of hybridizable mRNA around the floral induction period was similar to that of P18 and P19. Searching of databases revealed no significant hits except unidentified plant ESTs. P18 and P19 are proposed as the first example of plant-specific and developmentally regulated plasma membrane proteins.

Amino Acid Sequence↗
PubMed1996

Plasma levels and molecular forms of proatrial natriuretic peptides in healthy subjects and in patients with congestive heart failure.

A specific and sensitive radioimmunoassay (RIA) for the N-terminal fragment of proatrial natriuretic peptide (NproANP) was developed. Antiserum raised in rabbits against a mixture enriched with prohormone was 100% cross-reactive with human proANP(1-30). Plasma concentrations of proANP(1-30) and ANP immunoreactivities (ir-) were simultaneously measured in healthy subjects and patients with congestive heart failure (CHF; 26 dilated cardiomyopathy and 5 ischemic heart disease). High plasma levels of both ir-proANP(1-30) and ir-ANP were detected in CHF patients. Circulating ir-ANP levels were elevated in New York Heart Association functional Classes II and III patients but not in Class I patients. However, plasma levels of ir-proANP(1-30) were higher in asymptomatic patients than in healthy subjects, and markedly increased in patients of Classes II and III. Analysis of ir-proANP(1-30) by gel filtration chromatography or reverse-phase high pressure liquid chromatography revealed a 10 kDa peptide circulating as a distinct entity. These findings indicate that: (i) the most probable form of NproANP in human plasma is a 10 kDa peptide and (ii) in CHF patients the rise in plasma ir-proANP(1-30) levels is more pronounced than the variation in plasma ir-ANP. Thus, NproANP plasma levels may prove to be a more sensitive marker of left ventricular dysfunction than ANP.

Adult↗
PubMed1995

Myocardial production of prostaglandins: its role in atrial natriuretic peptide release.

In recent years, considerable evidence has been accumulated on prostaglandins (PG) in modulating atrial natriuretic peptide (ANP) release. In the current study we investigated whether eicosanoids promote isoproterenol-induced ANP secretion from superfused rabbit sliced atria. Inclusion of the cyclooxygenase inhibitor indomethacin (10 mumol) to the superfusing medium abolished isoproterenol-induced ANP release. Next, PGE2, but not PGF2 alpha or PGI2 (10 mumol), increased ANP release. Furthermore, isoproterenol-induced PGE2 formation was fully attenuated by indomethacin. Dibutyl-cAMP (0.5 mmol) had no effect on PGE2 formation, and the protein kinase A (PKA) inhibitor H89 (20 mumol) did not alter isoproterenol-induced PGE2 formation. On the other hand, indomethacin led to a significant decrease in isoproterenol-induced cAMP production. In addition, PGE2 enhanced basal cAMP concentration in superfusates. Superfusion of sliced atria by forskolin (10 mumol) or by dibutyl-cAMP (0.5 mmol) produced a significant rise in ANP release. Finally, H89 was ineffective on basal ANP release but abolished the increase of ANP release in response to isoproterenol or to PGE2. We conclude that: the effect of isoproterenol on ANP release is sensitive to indomethacin and H89; PGE2, but not PGE2 alpha or PGI2, increases ANP release; isoproterenol promotes myocardial PGE2 formation independently of adenylate cyclase and PKA activation pathways; and PGE2-induced ANP release is mediated by cAMP production and subsequent PKA activation. These results suggest that isoproterenol-induced ANP release appears to be mediated at least partly by PGE2 with underlying cAMP formation and PKA activation.

Animals↗
PubMed1995

[Rupture of an aneurysm of the internal iliac artery into the primary iliac vein].

Authors present a case of spontaneous rupture of internal iliac artery in common iliac venous, and propose a review of cases reported in literature. Abreast of modern imagery and especially computed tomography is able to give a precise diagnosis, but angiography is the Most accurate procedure for detecting arteriovenous fistula and cannot be excluded out of diagnostic approach.

Aged↗
PubMed1994

[Diagnostic and therapeutic strategies in acute pneumopathies in urban practice].

The consensus conference of the French Language Society of Infectious Disease convened at Lille in 1991 stressed the fact that "in the management of pneumonia, neither the clinical features nor the bacteriological information would enable a prediction of the responsible and effective agent with sufficient accuracy" and that antibiotic therapy should be empirical, based on the probabilities linked to the epidemiology and locality. The object of this study was to ascertain the diagnosis and therapeutic attitude of the general practitioner (GP) dealing with an acute infectious pneumonia in a 40 year old adult, previously well without any critical signs, which was the model taken for the consensus conference. One hundred GPs were selected at random from the general medical list in the city of Bordeaux and registered with the local medical council in Gironde. They were invited to answer a questionnaire containing 69 questions. The results were analysed for the two phases of the enquiry. The strategy of first intention and the method of re-evaluating for treatment instituted. Secondly the strategy used when faced with a patient who did not improve with the initial treatment. Eighty eight GPs answered the questionnaire and thus we are able to give the following information: the differential diagnosis was not clearly made between bronchial and pulmonary pathology when faced with a lower respiratory tract infection; two thirds of the GPs had a diagnostic and therapeutic approach which was in agreement with the recommendations of the consensus.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1993

The endocrine pancreas in brain-dead donors. A prospective study in 25 patients.

To determine whether hyperglycemia in brain-dead donors is a sign of endocrine pancreas insufficiency, we studied pancreatic function in 25 consecutive brain dead patients. Blood samples were drawn at 2-hr intervals from donor referral until organ procurement to analyze glucose, insulin, and C-peptide levels. After donor retrieval, two specimens were taken from the pancreas for a subsequent immunohistochemical examination. At referral mean glycemia was 13.60 +/- 1.49 mmol/L, and there was a large range of plasma glucose levels (4.6-31.6). Of 25 patients, 16 had glycemia above 10 mmol/L. At organ procurement a mean of 20 hr later, mean glycemia as 8.61 +/- 0.58 mmol/L (P < 0.005 with paired t test), and only 5 patients had glycemia above 10 mmol/L. Hyperglycemia was associated with elevated insulin and C-peptide levels during donor management. An elevated C-peptide/glucose molar ratio might be considered a sign of peripheral insulin resistance. Hyperglycemia above 25 mmol/L could not be related to the amount of glucose administered during donor maintenance. Severe hyperglycemia had a natural tendency to be partly corrected. Histologic and immunohistochemical examinations were available in 17 cases and can be considered normal. It is concluded that endocrine pancreatic function can be considered effective after brain death. The mechanism of the relative insulin resistance of these patients requires further study. Blood glucose levels, in the range observed in this study, are not a good donor criterion of endocrine pancreatic function before pancreas transplantation.

Adolescent↗
PubMed1993

Mechanisms of isoproterenol-induced atrial natriuretic peptide release from superfused rabbit atria.

The mechanisms for isoproterenol-induced atrial natriuretic peptide (ANP) release were studied in superfused rabbit sliced right atria. Addition of 1 microM norepinephrine to this preparation induced a significant monophasic twofold rise in ANP release. This effect was abolished by 1 microM propranolol and mimicked by 1 microM isoproterenol. Furthermore, addition of 200 microM 3-isobutyl-1-methylxanthine (IBMX) to the superfusing medium potentiated isoproterenol effect 31%. In addition, superfusion of slices with 0.5 mM N6,2-O-dibutyryladenosine 3',5'-cyclic monophosphate [(Bu)-2cAMP] enhanced ANP release in the same manner as the beta-agonist. After isoproterenol stimulation, adenosine 3',5'-cyclic monophosphate (cAMP) concentration in effluents increased significantly. ANP secretory response to isoproterenol was unaffected by extracellular calcium concentration or 1 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). Finally, 10 microM indomethacin significantly reduced isoproterenol-stimulated ANP release. It is concluded that 1) norepinephrine-induced ANP release is mediated by its beta-agonist activity, 2) isoproterenol-stimulated release appears to be mediated by cAMP, 3) isoproterenol effect does not require extracellular calcium, and 4) prostaglandins may be involved in this beta-adrenergic effect.

Animals↗
PubMed1992

Atrial natriuretic peptide during water deprivation or hemorrhage in rats. Relationship with arginine vasopressin and osmolarity.

The concentrations of atrial natriuretic peptide (ANP) in atria, hypothalami and plasma were investigated in relation to the variations of the plasma endogenous immunoreactive arginine vasopressin (Ir-AVP) during water deprivation or hemorrhage in normal conscious Wistar rats. Furthermore, the in vitro and in vivo effect of extracellular hyperosmolarity on ANP release from right atrium and hypothalamus was examined. Water deprivation elevated circulating immunoreactive ANP (Ir-ANP: pg/ml) to 153 +/- 7 (24 h); 174 +/- 1 (48 h) from the control level (109.6 +/- 7.8). This increase in Ir-ANP concentration which correlated with atrial (r = -0.93) or hypothalamic (r = -0.87) Ir-ANP content decrease, was associated with significantly enhanced levels of plasma Ir-AVP, plasma sodium, osmolarity and hematocrit. An acute volume depletion by hemorrhage significantly reduced plasma Ir-ANP (67 +/- 8.4 pg/ml) from the sham operated level (140 +/- 18 pg/ml). Plasma Ir-AVP was elevated dramatically (207.4 +/- 53.4 pg/ml) compared with the sham operated level (8.8 +/- 2.6 pg/ml). These results, indicating the lack of correlation between plasma Ir-ANP and Ir-AVP in vivo, suggest that the ANP secretion, which is regulated mainly by plasma volume, may be modulated by a change in plasma osmolarity. Extracellular hyperosmolarity stimulated the ANP release from superfused sliced normal rat atria and hypothalami.

Animals↗