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Biomedical subjects

P Guyon

Publications and source records attributed to P Guyon.

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

A T-DNA gene required for agropine biosynthesis by transformed plants is functionally and evolutionarily related to a Ti plasmid gene required for catabolism of agropine by Agrobacterium strains.

The mechanisms that ensure that Ti plasmid T-DNA genes encoding proteins involved in the biosynthesis of opines in crown gall tumors are always matched by Ti plasmid genes conferring the ability to catabolize that set of opines on the inducing Agrobacterium strains are unknown. The pathway for the biosynthesis of the opine agropine is thought to require an enzyme, mannopine cyclase, coded for by the ags gene located in the T(R) region of octopine-type Ti plasmids. Extracts prepared from agropine-type tumors contained an activity that cyclized mannopine to agropine. Tumor cells containing a T region in which ags was mutated lacked this activity and did not contain agropine. Expression of ags from the lac promoter conferred mannopine-lactonizing activity on Escherichia coli. Agrobacterium tumefaciens strains harboring an octopine-type Ti plasmid exhibit a similar activity which is not coded for by ags. Analysis of the DNA sequence of the gene encoding this activity, called agcA, showed it to be about 60% identical to T-DNA ags genes. Relatedness decreased abruptly in the 5' and 3' untranslated regions of the genes. ags is preceded by a promoter that functions only in the plant. Expression analysis showed that agcA also is preceded by its own promoter, which is active in the bacterium. Translation of agcA yielded a protein of about 45 kDa, consistent with the size predicted from the DNA sequence. Antibodies raised against the agcA product cross-reacted with the anabolic enzyme. These results indicate that the agropine system arose by a duplication of a progenitor gene, one copy of which became associated with the T-DNA and the other copy of which remained associated with the bacterium.

Agrobacterium tumefaciens↗
PubMed1997

Is dobutamine stress echocardiography useful for noninvasive differentiation of ischemic from idiopathic dilated cardiomyopathy?

Dobutamine stress echocardiography was performed in 56 consecutive patients, mean age: sixty-two +/- twelve years. Twenty-two patients had an idiopathic dilated cardiomyopathy (group 1) and 34 had angiographically proven ischemic dilated cardiomyopathy (group 2). Wall motion score index and left ventricular ejection fraction were determined at baseline, 5 micrograms/kg/min, peak, and ten minutes after stepwise dobutamine infusion. Worsening or no change in global wall motion score was observed in 9 group 2 patients (26%) and 1 group 1 patient (5%, P = .07). No significant difference was observed with regard to wall motion score index decrease between baseline and peak dose. Left ventricular ejection fraction increase during dobutamine infusion was comparable in both groups. Thus, an ischemic response was observed more often in the coronary artery disease group, yielding a good specificity and positive predictive value although sensitivity was low. However, left ventricular function improvement did not help to discriminate patients with or without significant CAD.

Aged↗
PubMed1997

[Clinical, echocardiographic and Doppler outcome in ischemic right ventricular dysfunction associated with inferior wall infarction].

Right ventricular involvement during inferior wall myocardial infarction does not seem to alter long-term clinical prognosis but its specific outcome has not been clearly studied. We have previously demonstrated that pulmonary regurgitant (PR) flow tracings doppler analysis allows the accurate diagnosis of RV involvement, especially when the pressure half-time of PR was < or = 150 ms and the ratio of the minimal velocity to the maximal velocity was < or = 0.5. We studied 40 patients with acute inferior wall myocardial infarction and with PR flow. Doppler echocardiography was obtained during the first day, before discharge (early control) and between 12 and 24 months follow-up (late control). Among 22 patients with RV involvement defined with PR-derived doppler parameters (RVIPR). 8 had right ventricular enlargement and/or wall motion abnormalities, observed in 6 cases at early control and in 4 at late control. Doppler analysis showed remnant RVIPR parameters in 9 patients at early control and 8 among these at late contorl, with no relation with pulmonary artery pressure or other echocardiographic parameters. No clinical, angiographic or therapeutic data predicted these distinct echocardiographic and doppler patterns and the long-term prognosis was not different. At late control, among 12 RVIPR patients which PR-derived doppler parameters were normal at early control, two patients had still RVIPR pattern at late control and described ischemic recurrence. PR flow doppler analysis is a useful tool for diagnosis and outcome evaluation of RV involvement and shows a remnant diastolic dysfunction in half of the patients with acute RV involvement.

Aged↗
PubMed1997

[Value of fasciocutaneous tensor fasciae latae island flap in the treatment of large abdominal hernias. Apropos of a case].

One case of repeated incisional hernia is reported. This hernia was initially repaired but repeated infection occurred. This hernia was then successfully treated with a fasciocutaneous tensor fasciae latae island flap. The patient was reexamined two years after surgery and presented a functional abdominal wall. Other different reconstructive possibilities of regional myocutaneous flaps are described.

Abdominal Muscles↗
PubMed1997

[Myocardial infarction in a pregnant woman during salbutamol therapy].

The authors report the case of a 31 year old woman at 30 weeks' gestation who developed a non-Q wave postero-lateral myocardial infarction during treatment with salbutamol. There were no complications and delivery took place at term normally. Coronary angiography was performed 3 months post-partum and was normal: the Methergin test was negative. Myocardial ischaemia occurring during treatment with a beta-2 mimetic in pregnancy is rare and hardly ever progresses to myocardial infarction. The usual mechanism of ischaemia is an imbalance of myocardial oxygen demand and supply. Myocardial oxygen consumption is naturally increased during pregnancy and excess intracellular calcium secondary to the beta-1 stimulation occurring with the use of beta-2 mimetic drugs further aggravates matters. This hypothesis raises the question of the value of calcium inhibitors in these forms of myocardial ischaemia.

Abortion, Threatened↗
PubMed1996

[Neurocysticercosis: pediatric aspects].

Neurocysticercosis is the most frequent parasitosis of the central nervous system in the world. Due to the extension of the pandemy, and the importance of the migrations from endemic countries, this parasitosis is being diagnosed with increasing frequency in France. Epilepsy is the main revealing symptom. However, in endemic countries, neurocysticercosis should be suspected in patients with any neurological sign. Diagnosis is based upon imaging procedures (computed tomography and magnetic resonance imaging) and serology (Elisa and Western blot). The evolution is highly variable, from complete latency to severe encephalopathy with psychomotor regression. Praziquantel and albendazole are the main therapeutic agents. Although corticosteroids are usually very effective on symptoms of the acute phase of the disease, their place in the treatment remains to be clarified. Racemic and ventricular forms of the disease usually need neurosurgery. In endemic regions, the diminution of the frequency of the disease relies upon prevention through health education compaigns, pending the achievement of an efficient vaccine.

Central Nervous System Diseases↗
PubMed1996

High prevalence of serological markers of cysticercosis among epileptic Malagasy children.

Neurocysticercosis (i.e. cerebral localization of the metacestode larvae of Taenia solium) is believed to be a major cause of late onset epilepsy in non-Muslim developing countries. To define its role in childhood epilepsy in Madagascar, analysis of serological markers of cysticercosis was performed in 256 children with unexplained epilepsy and in 113 controls. Sera were considered positive when high titres in ELISA were present together with at least one of the bands 13, 14, 18, 21, 24 or 32 kD on Western blot. Altogether, 17.6% of the patients versus none of the controls were seropositive using these criteria. When analysing the bands of the Western blot, those of 13, 14 and 18 were significantly more frequently detected in sera of epileptic children than in sera of controls. Neurocysticercosis can be considered the main cause of secondary childhood epilepsy in our country, Madagascar being one of the most important foci in the world.

Adolescent↗
PubMed1996

[Particularities of the immune response in neurocysticercosis].

Unique physiological and immunological features of the brain, as previously presented, explain the limitation of local inflammatory reactions and the existence of intrathecal specific IgG production. In addition, some parasitic factors of recent knowledge are induced during neurocysticercosis, which could be involved in vivo in a modulation of the immune response by larval products (a soluble RNA-peptide, some metacestode surface sphingoglycolipids). These recent findings lead us to make a critical review of the antigenic profiles obtained by enzyme-linked immunoelectrotransfer blot (EITB) on samples collected from patients suffering from simple or multiple neurocysticercosis.

Adolescent↗
PubMed1996

[Isolated anomalous origin of a septal artery from a third coronary ostium. Apropos of a case].

The authors report the case of a patient undergoing coronary angiography for angina who had an anomalous origin of the septal perforator artery from a separate ostium. Anomalies of the coronary arteries may consist not only of anomalous trajectories and coronary fistulae but also of anomalous origins of the main coronary arteries. The anomalous origin of a septal artery from a separate ostium is very rare accounting for 0.5% of cases in the medical literature. In some cases, this artery provides a collateral circulation for occluded main coronary vessels, thereby preserving left ventricular contractility.

Angina Pectoris↗
PubMed1996

[Laparoscopic resection of ileo-cecal tuberculosis].

Rarely seen in industrialised countries, ileo-caecal tuberculosis does not require surgery unless complications or diagnosis uncertainly occur. When laparotomy is contre indicated in presence of chronical respiratory disease, laparo-assisted ileo-caecal resection is an interesting alternative to classical surgery as it has less effect on ventilation. This laparo-assisted ileo-caecal resection appears to the first reported in presence of intestinal tuberculosis.

Aged↗
PubMed1995

[Indications for percutaneous angioplasty and coronary surgery in stable angina pectoris].

Coronary by-pass surgery and percutaneous transluminal angioplasty (PTCA) have changed the prognosis and life quality of patients with stable angina. Medical treatment and myocardial revascularisation are both useful and most often complementary. Coronary by-pass surgery is indicated in the treatment of coronary left main disease and three-vessel disease with poor left ventricular function. PTCA is the best choice in patient with one-vessel disease resulting in myocardial ischaemia. Discussion remains open in other cases mainly in stenosis of proximal left anterior descending artery. Often the ultimate choice results from the limits of each technique: sapheneous by-pass occlusion or coronary artery restenosis after PTCA. New techniques and devices in revascularization are expected to improve prognosis:use of arterial by-pass grafts, gene transfer, local drug delivery.

Angina Pectoris↗
PubMed1995

Hemodynamic criteria for diagnosis of right ventricular ischemia associated with inferior wall left ventricular acute myocardial infarction.

To test the diagnostic value of different hemodynamic indexes for the diagnosis of acute right ventricular (RV) ischemic dysfunction, we studied 2 groups of consecutive patients admitted for an acute left ventricular inferior wall myocardial infarction: 51 patients with (group 1) and 32 patients without (group 2) RV ischemia as determined by coronary angiography. In both groups, we analyzed by right-sided cardiac catheterization right-sided heart pressures, pulmonary capillary wedge pressure, and cardiac index. We also calculated pressure ratios (mean right atrial pressure or RV end-diastolic over pulmonary capillary wedge pressures), pulmonary vascular resistance, and RV stroke work index. We found significant differences (p < 0.01) between the 2 groups when comparing mean right atrial pressure, RV end-diastolic pressure, ratio of these 2 pressures over pulmonary capillary wedge pressure, RV stroke work index, and right atrial and RV pressure waveforms. The best combined sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were found for the right atrial M or W waveform pattern, isolated or combined with a disproportionate elevation of RV end-diastolic over pulmonary capillary wedge pressures (respectively, 92%, 94%, 90%, 87%, and 89%). Volume loading was performed in 27 patients (18 with and 9 without RV ischemia). Right heart pressures and RV stroke work index increased significantly and similarly in both groups. Cardiac index increased significantly only in patients without RV ischemia (p = 0.02). However, volume loading did not significantly modify the diagnostic value of the different hemodynamic criteria studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Relations between Doppler tracings of pulmonary regurgitation and invasive hemodynamics in acute right ventricular infarction complicating inferior wall left ventricular infarction.

To test the hypothesis that flow characteristics from pulmonary regurgitation (PR) can predict right ventricular (RV) involvement in patients with inferior wall acute myocardial infarction, we prospectively recorded continuous-wave Doppler tracings and right-sided cardiac hemodynamics in 48 consecutive patients with inferior wall acute myocardial infarction and PR. Right heart hemodynamics enabled the identification of 29 patients with (group 1) and 19 without (group 2) RV involvement. In patients with RV involvement, the pulmonary regurgitant flow pattern was characterized by a rapid rise in flow velocity to a peak level followed by an abrupt deceleration in mid-diastole, whereas in patients without RV involvement, the deceleration in mid-diastole was gradual. The pressure half-time of PR (PHTPR) and the lowest mid-diastolic to peak early diastolic velocity ratio were significantly lower in group 1 than in group 2 (91 +/- 31 vs 214 +/- 57 ms [p < 0.001], 0.35 +/- 0.08 vs 0.59 +/- 0.13 [p < 0.001], respectively). The best diagnostic accuracy (95%) was obtained with cut-off values of PHTPR < or = 150 ms and the lowest mid-diastolic to peak early diastolic velocity ratio < or = 0.5: sensitivity 100%, specificity 89%, positive predictive value 94%, and negative predictive value 100%. Using multiple logistic regression analysis, we found that PHTPR was the strongest predictor of RV involvement. Thus, these parameters, derived from pulmonary regurgitant tracings, are useful in the noninvasive bedside diagnosis of RV infarction.

Aged↗
PubMed1995

[Tuberculosis in children in Madagascar. 122 cases observed at the Soavinandriana-Antananarivo Hospital Center].

A group of 122 observations of pediatric tuberculosis has been studied. Nurslings represented 34% of the group, children under 8 years old 75% and only 10% were above 12. The sex ratio was 1,1. In a statistically significant way, tuberculous children were less often immunized by BCG than reference children not infected by tuberculosis. Contact has been traced back to close family in 42% of cases. Weight loss was significant at diagnosis time and after treatment the difference with the reference group disappeared. Extrapulmonary localizations were less frequent with children under 2, pulmonary and extrapulmonary localizations associations could be observed with 14% of children under 2 and with 31% of the whole children developing a proved tuberculosis. The importance of bronchial fibroscopy has been pointed out, for it allowed to detect 30% of abnormalities and to prove the diagnosis of tuberculous in 25% of cases. It is regrettable that the National Tuberculosis Control Programme did not prescribe chemoprophylaxis of contact children in its routine instructions, yet it is well known that child tuberculosis is rarely contagious and is not considered a priority by a programme. Finally, the authors reported that the number of pediatric tuberculosis managed in the country showed an obvious underestimation of the problem and they hope this work would lead to think more frequently of that diagnosis in the future.

Adolescent↗
PubMed1995

[Syncopal ventricular tachycardia complicating paroxysmal atrial fibrillation in severe myocardial ischemia].

The authors report two cases of spontaneous paroxysmal atrial fibrillation closely followed by syncopal ventricular tachycardia resulting in cardiac arrest requiring defibrillation. Both patients, men aged 62 and 64 years, had a past history of myocardial infarction without arrhythmias; atrial fibrillation occurred during severe myocardial ischaemia; coronary arteriography showed tight stenoses of the left main coronary artery with normal left ventricular function. Ventricular tachycardia (or fibrillation) during spontaneous paroxysmal atrial fibrillation is a rare occurrence. This sequence of events has been described in patients with accessory conduction pathways or in hypertrophic cardiomyopathy. It is an exceptionally rare complication of ischemic heart disease with only a very few previously reported cases. Myocardial ischaemia is probably the cause of the arrhythmia in together with irregularity of the ventricular contractions responsible for long cycle-short cycle sequences which are particularly arrhythmogenic and changes in sympathetic tone.

Atrial Fibrillation↗
PubMed1994

"Pseudo-narrowing" during right coronary angioplasty: how to diagnose correctly without withdrawing the guidewire.

The straightening of a sinuous proximal segment of a coronary artery using the stiffness of the guidewire has recently been recognized as likely to cause false coronary lesions. The accurate diagnosis between a true dissection and a pseudo-lesion is usually only done once all intra-coronary material has been removed into the guiding catheter. Such a manoeuvre may prove dangerous in case of dissection. We propose to demonstrate that it is possible to diagnose this phenomenon while leaving the guidewire within the coronary artery, and withdrawing it progressively until its floppy segment rests equally on either side of the suspect lesion.

Angioplasty, Balloon, Coronary↗