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Biomedical subjects

M Legrand

Publications and source records attributed to M Legrand.

At least 91 records · Page 5Linked to original sources
PubMed1990

Tobacco Mesophyll Protoplasts Synthesize 1,3-beta-Glucanase, Chitinases, and "Osmotins" during in Vitro Culture.

Tobacco (Nicotiana tabacum) mesophyll protoplasts synthesize six basic proteins (a, a', a(1), b, b', and c) which are undetectable in the leaf and whose synthesis is reduced by auxin (Y Meyer, L Aspart, Y Chartier [1984] Plant Physiol 75: 1027-1033). Polypeptides a, a', and a(1) were shown to have similar mobilities on two-dimensional electrophoresis as one 1,3-beta-glucanase and two chitinases from tobacco mosaic virus-infected leaves. In immunoblotting experiments, polypeptide a was recognized by specific antibodies raised against the 1,3-beta-glucanase and a' and a(1) reacted with anti-chitinase antibodies. Similarly, b and b' comigrated with osmotin and its neutral counterpart, two proteins characteristic of salt-adapted tobacco cells, and reacted with anti-osmotin antibodies. In addition it has been shown that 1,3-beta-glucanase and chitinase activities increased at the same time as a, a', and a(1) accumulated in cultivated protoplasts. Finally, polypeptide c was also detected in tobacco mosaic virus-infected leaves but could not be identified as any of the pathogenesis-related proteins characterized so far in tobacco. Thus, cultivated tobacco protoplasts synthesize and accumulate typical stress proteins.

Journal Article↗
PubMed1990

Clinical significance of serum pro-collagen III in chronic myeloproliferative disorders.

Pro-collagen III (PC III) has been proposed as a useful value for diagnosis and follow-up of myeloproliferative disorders. A significant difference is observed between polycythaemia vera (PV) and essential thrombocythaemias (ET) on one hand, and the pure erythrocytoses (PE) on the other hand, but a large overlap makes this test of low diagnostic value. High values are observed in primary and post-PV myelofibrosis, but excessive PC III levels in active PV are not predictive of evolution toward myelofibrosis. PC III level is lower in myelo-suppressed patients (32P, or hydroxy-urea) than in active cases or in patients treated by phlebotomies. We conclude that PC III measurement is of low diagnostic value for discriminating PV and PE, does not appear to allow short-term prediction of evolution to myelofibrosis, but may be useful to evaluate the role of treatment in delaying progression of PV toward myelofibrosis.

Aged↗
PubMed1990

[Coronary vasospasm: a cause of sudden death. Case report of reversible heart arrest with spontaneous coronary spasm documented by angiography].

The authors report a case of cardiac arrest occurring in a patient who had just entered the catheter laboratory for coronary angioplasty. Opacification of the left coronary artery revealed a proximal occluding double spasm unrelated to the distal stenoses for which angioplasty had been requested. Resuscitation and antispastic therapy with intracoronary injection of a nitrate derivative resulted in a complete recovery without any sequellae. The role of coronary spasm in sudden death and the value of the ergometrine test in patients with coronary stenosis are discussed.

Coronary Angiography↗
PubMed1990

[Management of meningeal hemorrhage for angiographic evaluation].

Perfect immobilization of the patient is mandatory when performing cerebral angiography. It allows good analysis and diagnosis of arterial or arterio-venous malformations. Neuroleptanalgesia or general anesthesia are currently used. Most common complications are due, either to induced arterial hypertension or to arterial catheterism (vasospasm or embolism). Early diagnosis and adequate treatment are necessary.

Anesthesia↗
PubMed1989

[Critical analysis of 1000 systematic assays of serum levels of vitamin B12 and folates].

Between January 15 and April 30, 1988, one thousand assays of serum vitamin B12 and folates were performed, and the reasons why they were requested as well as their clinical usefulness are discussed. In 50 cases these assays were requested for a suspected myeloproliferative syndrome; in some of the patients with polycythaemia vera an excess of B12 was observed without hyperleukocytosis, an argument for keeping the B12 assay as an element of initial evaluation. In numerous cases the assays were performed for aetiological evaluation of a macrocytosis of suspected alcoholic origin in most patients; more than 50 per cent of the patient had folate deficiency and only a few had low B12 values. Folate levels were frequently low and B12 levels generally normal in patients with gastrointestinal disease, but many of them had been supplemented with folate and/or B12 prior to the assay. More than 20 per cent of the 1,000 assays were performed in patients aged 80 years or more, and more than 50 per cent of them had a low folate level; this has no consequences for individual subjects, but it may be of epidemiological or sociological interest. It must be mentioned that too many blood samples (more than 40 per cent) were sent to the laboratory without adequate information and after supplementation in 20 per cent of the cases. Very few patients with very low B12 levels were subjected to Schilling's test, so that the clinical usefulness of this assay, as currently utilized, is questionable in a large number of cases.

Adolescent↗
PubMed1989

Immunogold localization of beta-1,3-glucanases in two plants infected by vascular wilt fungi.

An antiserum raised against a purified tobacco beta-1,3-glucanase (PR-N) was used to study the subcellular localization of enzyme in fungus-infected plant tissues by means of post-embedding immunogold labeling. In susceptible tomato plants, the enzyme accumulation was found to occur as a result of successful tissue colonization, whereas it appeared to be an early event associated with limited spread of the fungus in resistant tissues. Although marked differences between susceptible and resistant tomato cultivars were observed in the rate of production of beta-1,3-glucanase, the pattern of enzyme distribution was similar. The enzyme was found to accumulate predominantly in host cell walls and secondary thickenings of xylem vessels. By contrast, a very low amount of enzyme was associated with compound middle lamellae. The occurrence of beta-1,3-glucanase at the cell surface of invading fungi was an indication of their possible antifungal activity. A low enzyme concentration was detected in vacuoles of both healthy and infected tissues. In infected eggplant tissue, the pattern of beta-1,3-glucanase distribution was similar to that observed with tomato. Whether these hydrolases accumulate first in vacuoles and are subsequently conveyed toward the outside to participate in fungal wall lysis remains to be determined.

Antibody Specificity↗
PubMed1989

Central cardiovascular effects of dihydropyridines in spontaneously hypertensive rats.

Intracerebroventricular (i.c.v.) injections of dihydropyridine derivatives calcium channel agonist (BAY K8644) and antagonist (nifedipine, nicardipine, PN 200-110) induced opposite long-lasting changes in blood pressure (BP) in pentobarbital anesthetized spontaneously hypertensive rats (SMR). I.c.v. nifedipine (NIF), nicardipine (NIC), and PN 200-110 decreased mean blood pressure dose-dependently and stereoselectively, (+) NIC and (+) PN being 8 and 3 times more potent than their (-) isomers, respectively. The decrease in BP was due to a withdrawal of the sympathetic tone, since NIF- and NIC-induced falls in BP were suppressed after either hexamethonium (HXM), 6 OHDA or bilateral adrenalectomy. I.c.v. BAY K8644 increased BP dose-dependently. The i.c.v. BAY K8644-induced hypertensive effect was inhibited: a), by NIF and (+) PN but not by (-) PN, therefore probably occurring at central DHP sites; b), by HXM and reserpine, thus probably mediated by an increase in sympathetic tone; c) by i.c.v. methylatropine (MA) while i.v. MA and i.c.v. HXM had no inhibitory effect, thus probably involving central muscarinic sites. In SHR, NIC did not after the K(+)-evoked ACh release but suppressed the BAY K8644-induced increase in ACh release. In anesthetized normotensive control rats (WKY), neither i.c.v. NIF, NIC or BAY increased BP and HR while, in conscious SHR it decreased BP without any change in HR. These data increased BP and HR while, in conscious SHR it decreased BP without any change in HR. These data suggest that central DHP sites may be involved in the cholinergic transmission and may participate in genetic hypertension via sympathetic tone.

Animals↗
PubMed1989

Comparative clinical results of ileal-pouch anal anastomosis and ileorectal anastomosis in ulcerative colitis.

The aim of the study was to compare the results of ileal-pouch anal anastomosis (IAA) and total abdominal colectomy with ileorectal anastomosis (IRA) in the treatment of ulcerative colitis. The number of patients included in the comparative trial was 104 (IAA) and 197 (IRA), respectively. No clear advantage of IRA over IAA was seen: postoperative mortality and morbidity were about the same; functional results as shown by the frequency of stools and daytime continence were virtually equal. A factor favoring IAA was, among others, recurrence of proctitis after IRA which is more difficult to treat than the pouchitis occurring after IAA and is associated with a higher rate of secondary permanent end ileostomy; besides, IRA entails the risk of cancer developing in the rectal stump, while at the same time it is difficult to follow up these patients closely enough. IRA is indicated only if the diagnosis of ulcerative colitis is in doubt; if the patient is more than 60 years of age; and if IAA proves technically too difficult, IAA is usually preferable, however, if there is any doubt as to whether the patient is suffering from ulcerative colitis or Crohn's disease, ileorectostomy is preferred which does not preclude IAA at a later date in case of need.

Anal Canal↗
PubMed1988

Central and peripheral cardiovascular effects of the enantiomers of the calcium antagonist PN 200-110.

The negative inotropic effects and the central and peripheral hypotensive effects of (+) and (-) PN 200-110 were investigated in cultured chick heart cells and in spontaneously hypertensive rats, respectively. There was a large difference in negative inotropic potency between the two enantiomers in cultured chick embryo ventricular cells: the (+) enantiomer was 140 fold more potent (IC50 = 1.1 +/- 0.2 nM) than the (-) enantiomer (IC50 = 160 +/- 20 nM). (+) PN 200-110 was 10 fold more potent than (-) PN 200-110 in lowering blood pressure after intravenous injection and only three fold more potent after intra-cerebroventricular injection (i.c.v.) into pentobarbital-anaesthetized spontaneously hypertensive rats. I.c.v. administered (+) PN 200-110 (1 microgram/kg) partially antagonized the hypertensive response to i.c.v. administered BAY K 8644 (30 micrograms/kg), a calcium channel agonist, while the same dose of the (-) enantiomer did not change the i.c.v. BAY-induced increase in blood pressure. These results suggest that the dihydropyridine calcium channel antagonist, PN 200-110, may act centrally and stereoselectively at the level of the dihydropyridine receptor sites involved in the control of blood pressure in spontaneously hypertensive rats.

Anesthesia↗
PubMed1988

Central modulation of baroreceptor reflex response to phenylephrine by dihydropyridines in rats.

The effects of two dihydropyridine derivatives, the calcium channel agonist BAY k 8644 or the antagonist PN 200-110, on the central nervous components of the baroreceptor reflex control of heart rate during activation of baroreceptors by phenylephrine (2 micrograms i.v.) were studied in pentobarbital-anesthetized normotensive (Wistar) rats and spontaneously hypertensive rats (SHR). To rule out an effect on peripheral vessels or on the sinoauricular node (or on both), BAY k 8644 and PN 200-110 were administered intracerebroventricularly (i.c.v.) at doses that did not change blood pressure. Baroreceptor reflex sensitivity was calculated as the slope of the relationship between systolic arterial pressure and heart period. Baroreceptor reflex sensitivity increased with time following the onset of anesthesia. In SHR, injection of BAY k 8644 (3 micrograms/kg i.c.v.) suppressed the time-dependent increase in baroreceptor reflex sensitivity. The inhibitory effect of BAY k 8644 (3 micrograms/kg i.c.v.) on the time-dependent increase in baroreceptor reflex sensitivity was suppressed by pretreatment with PN 200-110 (0.6 microgram/kg i.c.v.) but not with the solvent, indicating that the central effect of BAY k 8644 occurred at the level of specific dihydropyridine binding sites. In addition, the inhibitory effect of BAY k 8644 (3 micrograms/kg i.c.v.) on the time-dependent increase in baroreceptor reflex sensitivity was suppressed by pretreatment with the muscarinic antagonist atropine methylnitrate (80 micrograms/kg i.c.v.) but not with the solvent. In normotensive rats, the time-dependent increase in baroreceptor reflex sensitivity was not significantly altered by BAY k 8644 (3 micrograms/kg i.c.v.).(ABSTRACT TRUNCATED AT 250 WORDS)

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1988

[Central control of the baroreflex response to phenylephrine by dihydropyridines in the anesthetized rat].

We have previously shown that a calcium channel activator (BAY K 8644) and a calcium channel inhibitor (CCI) (nifedipine), both dihydropyridine derivatives (DHP), can modulate in opposite fashion calcium dependent mechanisms involved in the central control of blood pressure and heart rate in SHR but not in Wistar rats. These results suggested that central DHP receptor sites might modulate baroreflex function. Therefore, we studied in pentobarbital anaesthetized SHR, the effects of BAY K 8644 and PN (200-110) (CCI) on central integration of baroreflex function (ramp method: phenylephrine 2 microgram i.v.). In order to rule out peripheral vascular effects, BAY and PN were administered intracerebroventricularly (i.c.v.) at doses which did not change BP. Baroreflex sensitivity (BRS) increased with time following the onset of anesthesia. In SHR, i.c.v. injection of BAY (3 microgram/kg) but not PN (0.6 micrograms/kg) suppressed the time dependent increase in BRS. The inhibitory effect of BAY on the time-dependent increase in BRS was suppressed by a pretreatment with PN (0.6 micrograms/kg i.c.v.) and by a pretreatment with the muscarinic antagonist atropine methylnitrate (80 micrograms/kg i.c.v.). BAY i.c.v. dit not change BRS in Wistar rats. These results indicate that DHP may centrally modulate BRS in SHR and suggest a central sympatho-excitatory effect for BAY mediated by an enhanced release of acetylcholine.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1987

Biological function of ;pathogenesis-related' proteins: four PR proteins of tobacco have 1,3-beta-glucanase activity.

Three of the ten acidic ;pathogenesis-related' (PR) proteins known to accumulate in Nicotiana tabacum cv Samsun NN reacting hypersensitively to tobacco mosaic virus, namely -O, -N and -2, have been shown to have 1,3-beta-glucanase (EC 3.2.1.39) activity. By using sera raised against each protein purified to homogeneity close serological relationships have been demonstrated between the three proteins. The same specific sera cross-reacted with a basic protein which is also a 1,3-beta-glucanase induced by virus infection and which can be considered as a new basic pathogenesis-related protein of tobacco. Protein PR-O and the basic 1,3-beta-glucanase display about the same specific enzymatic activity, i.e. 50-fold and 250-fold higher than specific activities of proteins PR-N and -2 respectively.

Journal Article↗
PubMed1987

Enzymatic synthesis of lignin: purification to homogeneity of the three O-methyltransferases of tobacco and production of specific antibodies.

Three o-diphenol-O-methyltransferases (OMTs; EC 2.1.1.6) involved in the biosynthesis of lignin have been purified to homogeneity from tobacco leaves. Seven different fractionation steps which included (NH4)2 SO4 precipitation, conventional low-pressure chromatography on Ultrogel AcA34 and DEAE-cellulose columns, high-performance liquid chromatography (HPLC) on three different supports (Mono Q, Mono P, and TSK G-3000 SW columns), and finally preparative electrophoresis were necessary. At each step of purification, the protein content of the enzymatic fractions was analyzed by electrophoresis on polyacrylamide gels under denaturing conditions. Purified OMT I appeared on sodium dodecyl sulfate-polyacrylamide gel as a doublet with electrophoretic mobilities corresponding to molecular weights of 38,500 +/- 2000 and 39,500 +/- 2000. The other two enzymes migrated as single but rather broad bands with molecular weights of 42,000 (OMT II) and 43,000 (OMT III). Polyclonal antibodies were raised in rabbits. The titers of antibodies were measured by an indirect enzyme-linked immunosorbent assay method, and their specificity was demonstrated by immunoblotting enzyme preparations at different stages of purification. Immunodetection of the three enzymes with a specific antiserum suggested serological relationships between the three OMTs of tobacco.

Animals↗
PubMed1987

Biological function of pathogenesis-related proteins: Four tobacco pathogenesis-related proteins are chitinases.

Four endochitinases (poly[1,4-(N-acetyl-beta-D-glucosaminide)] glycanohydrolase, EC 3.2.1.14) have been purified from leaves of Nicotiana tabacum cv. Samsun NN reacting hypersensitively to tobacco mosaic virus. Two of them are acidic proteins of molecular weights 27,500 and 28,500 and have been identified as 2 of the 10 pathogenesis-related proteins that are known to accumulate in tobacco in response to stress or pathogen attack. These two pathogenesis-related proteins, named "P" and "Q" when their biological function was unknown, account for one-third of tobacco mosaic virus-induced chitinase activity of tobacco leaves. They are serologically closely related to the two other chitinases, which can be considered as new basic pathogenesis-related proteins. These two basic chitinases exhibit higher molecular weights (32,000 and 34,000) and higher specific enzyme activity than the two acidic isoforms.

Journal Article↗