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Biomedical subjects

R Dumas

Publications and source records attributed to R Dumas.

At least 19 recordsLinked to original sources
PubMed1992

Isolation and kinetic properties of acetohydroxy acid isomeroreductase from spinach (Spinacia oleracea) chloroplasts overexpressed in Escherichia coli.

Acetohydroxy acid isomeroreductase catalyses a two-step reaction, an alkyl migration and a NADPH-dependent reduction, in the assembly of the carbon skeletons of branched-chain amino acids. Detailed investigations of acetohydroxy acid isomeroreductase aimed at elucidating the biosynthetic pathway of branched-chain amino acids and at designing new inhibitors of the enzyme having herbicidal potency have so far been conducted with the enzymes isolated from bacteria. To gain more information on a plant system, the gene encoding the mature acetohydroxy acid isomeroreductase from spinach (Spinacia oleracea) leaf chloroplasts has been used to transform Escherichia coli cells and to overexpress the enzyme. A rapid protocol is described that allows the preparation of large quantities of pure spinach chloroplast acetohydroxy acid isomeroreductase. Kinetic and structural properties of the plant enzyme expressed in Escherichia coli are compared with those reported in our previous studies on the native enzymes purified from spinach chloroplasts and with those reported for the corresponding enzymes isolated from Escherichia coli and Salmonella typhimurium. Both the plant and the bacterial enzymes obey an ordered mechanism in which NADPH binds first, followed by substrate (either 2-acetolactate or 2-aceto-2-hydroxybutyrate). Inhibition studies employing an inactive substrate analogue, 2-hydroxy-2-methyl-3-oxopentanoate, showed, however, that the binding of 2-hydroxy-2-methyl-3-oxopentanoate and NADPH occurs randomly, suggestive of some flexibility of the plant enzyme active site. The observed preference of the enzyme for 2-aceto-2-hydroxybutyrate over 2-acetolactate is discussed with regard to the contribution of acetohydroxy acid isomeroreductase activity in the partitioning between isoleucine and valine biosyntheses. Moreover, the kinetic properties of the chloroplast enzyme support the notion that biosynthesis of branched-chain amino acids in plants is controlled by light. As judged by analytical-ultracentrifugation and gel-filtration analyses the overexpressed plant enzyme is a dimer of identical subunits.

2-Acetolactate Mutase↗
PubMed1992

Sphenoidal electrode insertion under local analgesia in children.

The indications for method and the results of sphenoidal electrode insertion under local analgesia are evaluated in children. This technique makes it possible to study the hippocampal area, which cannot be studied by other extracranial electrodes. It also localizes in a temporal lobe some complex seizures without electrical events on surface recordings, complex seizures with bilateral temporal spikes or a frontotemporal focus of spikes, as well as those with a temporal focus with bilateral synchronous spikes in standard EEG. Therefore, sphenoidal electrodes inserted without heavy general analgesia enable temporal seizures to be identified and localized, leading to more specific neuroradiological and neurophysiological explorations and helping in this way to select possible patients for epileptic surgery.

Adolescent↗
PubMed1992

Effect of somatostatin analog octreotide on human sphincter of Oddi.

The effect of the long-acting somatostatin analog octreotide on the sphincter of Oddi was investigated in seven subjects referred for endoscopic sphincter of Oddi manometry. Six patients had unexplained right upper quadrant pain and one had bile duct dilatation without evidence of fixed obstruction on endoscopic retrograde cholangiopancreatography. A triple-lumen low-compliance system was used to record the sphincter of Oddi basal pressure, phasic contraction frequency, amplitude, duration, and direction of wave propagation before and after intravenous administration of octreotide in a dose of 50 micrograms. After a mean latency period of 1 min, significant changes included increased basal pressure in all seven patients, increased frequency of wave contractions in six patients, and decreased wave amplitude in six patients. The median duration of wave contraction and wave propagation sequence were not significantly influenced. Thus, octreotide has a significant stimulatory affect on the sphincter of Oddi activity, which may impair biliary and pancreatic flow.

Adult↗
PubMed1992

Vascular manifestations in homocystinuria.

Homocystinuria was discovered in a 21-year-old woman when she presented with lower limb ischemia and pulmonary embolism. This patient had a partial deficit in cystathionine-synthetase and took strongly dosed oral contraceptive medication. This report underscores: (1) the value of searching for this type of pathology even in the adult; (2) the possibility of disclosure by another condition, and particularly, drug-induced; (3) the importance of searching for other involved members of the same family; and (4) the possibility of treatment in vitamin sensitive patients.

Adult↗
PubMed1992

[Investigation via electroencephalogram with sphenoidal electrodes of a case of reading epilepsy: role of the temporal lobe in the emotional evocation of seizures].

Reading epilepsy in a 20-year-old male. Electroencephalographic study with sphenoidal electrodes localized the onset of critical spikes in the temporal areas (especially the left). The frequency and diffusion of critical spikes were increased when material read had an emotional content. This case report supports the "communication" hypothesis as opposed to hypotheses that emphasize proprioceptive and other "lower order" stimuli in evoking seizures while reading. The authors discuss the role of the temporal lobe in reading: lexical function, treatment of visual information and emotional integration of stimuli.

Adult↗
PubMed1992

Plasma lipoproteins in cortical versus lacunar infarction with or without cardiac arrhythmia, and in transient ischaemic attacks: a case control study.

We investigated the relation of plasma lipids to the risk for cortical infarction with (22 cases) or without (38 cases) cardiac arrhythmias, for lacunar infarction (28 cases) and transient ischaemic attacks (TAI) (15 cases). In the group of cortical infarction with or without cardiac arrhythmias, we observed a maximum increase of total cholesterol, of very low density lipoprotein (VLDL) and low density lipoprotein (LDL), triglycerides, total Apolipoprotein (Apo) B, LDL-Apo B and Apo-A1. On the contrary, we observed a decrease of total ApoE, HDL-ApoE, a distribution of LDL in a single layer and the presence of LDL of small weight. TAI is different from the former group by a low level of HDL and the lack of abnormalities of Apo-A1, and on the distribution and the weight of LDL. Finally, lacunar infarction presents a normal plasma lipoprotein profile. These data suggest that previously demonstrated differences in LDL-cholesterol levels between patients with ischaemic stroke and control subjects may apply to patients with cortical but not lacunar infarction. The presence or not of a cardiac arrhythmia doesn't give a special lipoprotein profile, and TAI has no changes on the distribution and the weight of LDL. Therefore, separation of ischaemic strokes into types based on mechanism as large vessel atherosclerosis versus small vessel atherosclerosis may help clarify lipid-related risk factors in cerebrovascular disease.

Arrhythmias, Cardiac↗
PubMed1992

Frequency of transient ischaemic attacks in strokes: place for a preventive treatment.

Transient ischaemic attack (TIA) represents a neurological deficit during less than 24 hours, without any abnormality on CT scan. This symptom may have 2 risks: it may give place to a severe stroke, and it is not always linked to an ischaemic mechanism. This work rests on a population-based registry existing in Dijon since 1985 with a specific and exhaustive registration. CT scan allows the mechanisms of stroke to be identified: cortical infarct, lacunar infarct, cerebral haemorrhage, and TIA. TIA represent 15% of stroke. Survival rate of 80% is better than other strokes. A TIA may appear before a cerebral infarct in 48% of the cases, a lacunar infarct in 18% of the cases, another TIA in 28% of the cases, and a haematoma in 8% of the cases. Therefore TIA is an important symptom appearing before severe stroke, that may let place to a preventative action.

Aged↗
PubMed1992

Does the somatostatin analogue octreotide protect against ERCP induced pancreatitis?

This study evaluates the effect of the long acting somatostatin analogue octreotide on biochemical and clinical parameters of endoscopic retrograde cholangiopancreatography (ERCP) induced pancreatitis. Altogether 245 patients were randomised to receive either octreotide or isotonic saline. Octreotide (100 micrograms) was administered intravenously five minutes before ERCP and subcutaneously 45 minutes after ERCP. There were no significant differences in the median serum amylase and lipase activities at baseline, eight, and 24 hours after ERCP. Five patients (2%) developed clinical pancreatitis--three in the octreotide and two in the placebo groups. Excluding patients who developed pancreatitis, 43 (18%) developed abdominal pain after ERCP--21 in the octreotide and 23 in the placebo groups. There were no significant differences in the median serum amylase and lipase values between the treatment groups. None of the 52 patients who had therapeutic interventions developed pancreatitis. This study suggests that octreotide may not protect against ERCP induced pancreatitis.

Amylases↗
PubMed1992

Molecular analysis of the sex-determining region from the Y chromosome in two patients with Frasier syndrome.

In the Frasier syndrome there is an association between XY gonadal dysgenesis and chronic renal failure. Owing to an observed sex reversal, the Y chromosomes of two girls with this syndrome have been analyzed. Using molecular-biology techniques, no major alterations of the known sex-determining area of the Y chromosome were found. Furthermore, the sequence did not reveal impairment of the recently described testis-determining factor SRY. These data suggest that in the Frasier syndrome, XY sex reversal and renal failure could be the result of either faulty gene(s) located downstream in the sex differentiation pathway during embryogenesis, or impaired SRY regulation. Preliminary results on the Wilms' tumor suppressor gene WT1, a candidate for acting downstream to SRY, are also provided.

Adolescent↗
PubMed1992

Screening for Y-derived sex determining gene SRY in 40 patients with Turner syndrome.

In Turner patients, the presence of a Y chromosome or derivative Y is correlated with the risk of gonadoblastoma induction. "Marker" chromosomes originating from Y, may not show characteristic fluorescence and then be very difficult to identify by conventional cytogenetic techniques, although they still predispose the patients to gonadal tumors. Using polymerase chain reaction of the gene from the sex-determining region of the Y chromosome, we screened 40 Turner patients (thirty seven 45X and three 45X,46XX) for the presence of Y chromosomal DNA. We were able to identify karyotypically unrecognized Y chromosome material in 1 patient out of the 40 studied. In this patient mild clinical and biological hyperandrogenism was observed. Reliability of our technique was ascertained by the detection of the expected 648 base pairs amplified DNA fragment in all normal male controls as well as in 3 Turner patients with confirmed 45X,46XY mosaicism. Despite the low frequency of unrecognized Y chromosome material (1 case over 40 in our experience), our data suggest that polymerase chain reaction of the gene from the sex-determining region of the Y chromosome is worthy of being performed in Turner patients considering the potential risk of the presence of a Y chromosome.

Adolescent↗
PubMed1992

Endolaparoscopic palliation of pancreatic cancer.

Two patients with advanced pancreatic cancer were palliated for both duodenal and biliary obstruction without laparotomy. The techniques of endoscopic biliary stent and laparoscopic gastrojejunostomy are described. This combination achieved rapid palliation with minimum morbidity. Patients with advanced pancreatic cancer and a limited life expectancy benefit greatly from the shortened hospital stay and convalescence this manner of treatment offers.

Adult↗
PubMed1992

[Piezoelectric extracorporeal lithotripsy in children: first results and reflections after 18 sessions].

From 1988 to 1990, we treated 13 children between the ages of 2 and 15 years with stones of the upper urinary tract. These stones were treated by means of 18 sessions of piezoelectric extracorporeal lithotripsy: 14 under general anaesthesia and 4 without even any analgesia. We obtained an 84.5% success rate with no particular adverse effects. These results are similar to those reported for hydroelectric or electromagnetic shock wave lithotripsy, which are associated with a higher morbidity. The efficacy of extracorporeal lithotripsy in paediatrics is remarkable, but clinical studies in adults as well as animal experimentations have demonstrated severe renal contusion and do not formally exclude the possibility of delayed complications. At the present time, this technique should therefore be used very cautiously and must be accompanied by systematic prevention of recurrent stones.

Adolescent↗
PubMed1992

[Acute anterior bi-opercular syndrome of critical origin in epilepsy with rolandic spikes].

We report the fifth case of a palsy of the lips, the tongue and the pharynx corresponding to an acute pseudo-bulbar syndrome causing speech arrest, and hyper-sialorrhea. The clinical examination and the electroencephalograms showed a partial motor status with spikes discharges in the two central regions, in a 10-year old boy known to have epilepsy with rolandic spikes. The status epilepticus ceased with phenytoin therapy. Although epilepsy with rolandic spikes is a benign one without any cerebral lesion, a partial motor status epilepticus is possible and does not change prognosis.

Brain Diseases↗
PubMed1992

[Difficulties in diagnosis of frontal syndrome in epileptic children: clinical, diagnostic, physiopathological aspects. Apropos of 6 cases].

The authors report 6 cases of acute frontal syndrome following severe seizures of frontal origin. The study of the 6 cases shows the place of disorders in affectivity, behavior, judgement and motor activity; such features changing over time. The relationship between the frontal syndrome and epilepsy is suggested by the fact that the frontal syndrome appears after an increased frequency of frontal seizures, with prolonged discharges of generalized or frontal spikes. The frontal syndrome disappears slowly with the epileptic discharges, and no frontal lesion is found on CT-Scan. Such cases suggest that the frontal syndrome is functional, linked to the localization of the epileptic discharges; it may be regarded as a post-critic deficit, and must be differentiated from a post-critic delirium or a psychotic state.

Adolescent↗
PubMed1992

[Prognosis of transient ischemic accidents disclosing infarction].

In a prospective study, thirty six out of 175 consecutive patients (21%) with transient ischemic attack (TIA), had cerebral infarction on CT-scan. This group of patients differed from the group without cerebral infarction by a higher age, a longer duration of neurological deficit, a greater frequency of neurological history, vertebro-basilar TIAs, cephalagia and, cardiac arrhythmia, and by a higher 2-year mortality rate. Due to their difference in etiological factors and prognosis, TIAs with cerebral infarction on CT-scan should be differentiated from those without cerebral infarction.

Cerebral Infarction↗