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H Gras

Publications and source records attributed to H Gras.

At least 19 recordsLinked to original sources
PubMed1992

RTIME: a program for time-series measurements and evaluation in electrophysiology with the AT-PC.

This work describes a program which uses a standard RS232-serial interface of an IBM-AT-compatible microcomputer to receive via four data lines input from any laboratory equipment (spike discriminators, stimulus equipment, etc.) generating pulses between 0 to -15 V (low) and +5 to +15 V (high). Therefore, program operation is independent from any hardware extensions of the computer. The time of occurrence of input pulses is recorded with a resolution of 10 microseconds. Depending on processor speed and optional on-line display of interval histograms, a maximum sampling rate of 1.3-6 kHz is attained. Designed primarily for electrophysiological applications, the program comprises an extensive set of functions for off-line analysis of data either in the time- or in the phase-domain. The program is controlled by menu-selectable commands with detailed on-line explanation and is therefore suited for use even by operators without computer experience, e.g., students on courses in experimental physiology. Elaborate schemes of evaluation can be defined as macro commands to speed up and simplify complex data analysis in actual research.

Action Potentials↗
PubMed1988

The neurotrophic factor neuroleukin is 90% homologous with phosphohexose isomerase.

Neuroleukin (NLK) is a protein of relative molecular mass (Mr) 56,000 (56K) secreted by denervated rat muscle and found in large amounts in muscle, brain, heart and kidneys. The protein is a neurotrophic factor for spinal and sensory neurons and a lymphokine product of lectin-stimulated T-cells. It also induces immunoglobulin secretion by human mononuclear cells. Molecular clones of NLK have been expressed in monkey COS cells and the product was shown to have the same biological and biochemical properties as the extracted protein. NLK is abundant in muscle, brain and kidney, but is active at concentrations of 10(-9) to 10(-11) M, similar to those for other polypeptide factors. We have cloned the gene for pig muscle phosphohexose isomerase (PHI) (EC 5.3.1.9) which catalyses the conversion of glucose-6-phosphate to fructose-6-phosphate, an obligatory step in glycolysis, and determined its amino-acid sequence. Surprisingly, it is 90% homologous to the sequence of mouse neuroleukin.

Amino Acid Sequence↗
PubMed1988

[Electrophysiological study of pro-arrhythmogenic effects of erythromycin].

Three cases of torsades de pointe induced by erythromycin have recently been reported. After observing a new case, the authors tried to demonstrate the possible mechanism of the arrhythmogenic action of this molecule. Twenty-two patients undergoing electrophysiological studies in the catheter laboratory to determine the cause of syncope were given an intravenous injection of 10 mg/Kg of erythromycin lactobionate. The drug was injected in 1 minute (bolus) in 11 patients (Group A). The other 11 patients (Group B) received the drug by slow intravenous infusion (20 minutes). Electrophysiological parameters were measured before and after erythromycin. A significant prolongation of the atrial refractory periods (+39 ms), ventricular refractory periods (+20 ms), QT (+20 ms) and QTC intervals (+42 ms) was observed in Group A. These electrophysiological effects could explain an arrhythmogenic action similar to that of antiarrhythmic drugs in Group I of Vaughan-Williams' classification. The slow intravenous infusion of erythromycin in Group B considerably reduced these undesirable secondary effects. This difference was directly related to serum concentrations of the molecule.

Adult↗
PubMed1987

[Study of electrophysiological effects of betaxolol].

Betaxolol is a new cardioselective beta-blocker without any intrinsic sympathomimetic activity. A study of the cardiac electrophysiological effects of this molecule used intravenously was carried out in 20 patients. Betaxolol prolongs the sinus cycle (+ 25%, p 0.001), prolongs the sino-atrial conduction time (+ 20.1%) and atrio-hissian conduction time (+ 10.8%, p 0.001), and prolongs the refractory periods at all levels: atrial (+ 8%), nodal (+ 20.8%), right ventricular (+ 4.3%). These findings confirm the electrophysiological characteristic effects of the beta-blockers series; however, the moderate but significant increase of the refractory ventricular period, seems to provide this molecule with a certain degree of originality in this therapeutic class.

Adrenergic beta-Antagonists↗
PubMed1986

[Acute myocarditis in Lyme's syndrome. Value of myocardial scintigraphy with gallium 67].

The authors report the case of a 35 year old man with no known previous cardiac disease. One month after a tic bite causing diffuse abdominal erythema, he was admitted to hospital with fever, breathlessness and bradycardia. The electrocardiogramme showed first degree atrioventricular block with a sinoatrial block (SA = 200 ms, AH = 240 ms). Echocardiography eliminated the diagnosis of pericardial effusion. Thallium 201 myocardial scintigraphy was pathological and showed irregular global uptake suggesting cardiomyopathy. Gallium 67 scintigraphy showed increased uptake in the left ventricle. The evolution was uncomplicated with normalisation of clinical, ECG and radiological changes. Cardiac catheterisation and angiography eliminated ischaemic and primary cardiomyopathy. Control radionuclide investigations were normal at one month: there was no persistent abnormal Gallium uptake. The diagnosis of Lyme's syndrome was confirmed by positive serology with successive titres of 1/1024 and 1/2048 (significant at titres over 1/256). This unusual case illustrates: the risk of myocardial disease in Lyme's syndrome; the diagnostic value of Gallium 67 scintigraphy in acute myocarditis: Gallium seems to fix specifically on inflamed tissues, so distinguishing myocarditis from primary cardiomyopathies.

Acute Disease↗
PubMed1984

The tail flattening reflex in Lumbricus: reconstitution after tail amputation and modifications in segmental nerve roots.

On stimulation of the head, the caudal 20-30 segments of intact earthworms exhibit a marked dorso-ventral flattening reflex which is an element of the escape response. When the tail is removed this reflex is reconstituted gradually in segments anterior to the amputation level without regeneration of new tail segments. It takes longer to reestablish the flattening if larger parts of the body are cut off, but after 60 days p.o. all animals regained the full response independent of the number of segments amputated. Extirpation of three consecutive ganglia from the ventral nerve cord also suffices to develop flattening anterior to the operated segments, but the reaction is less pronounced and appears later than after tail amputation. Moreover, it vanishes at the same time the normal tail flattening is observed again, presumably after regeneration across the gap in the cord. In different regions of the body, area and perimeter distributions of transversely sectioned axons in the three pairs of segmental nerves (SN I-III) of the cord were measured. Characteristic changes along the length of the animal were found for SN I and SN III. In tail segments the axonal size distributions are more variable than "typical" segments. The flattening reflex is mediated by axons in SN III (Pallas and Drewes, 1981). In body segments having reconstituted behavioral characteristics of the lost tail segments, the area of the largest axons and the general size distribution in SN III approximate those found in normal tail segments.

Animals↗
PubMed1984

A 'hidden line' algorithm for 3D-reconstruction from serial sections--an extension of the NEUREC program package for a microcomputer.

An algorithm is described to generate pictures in arbitrary perspective from serially sectioned biological material. Only those parts of the object which lie on a direct line of sight to the observer are included into the computed paper-plot, while hidden lines are omitted. The program was written for an inexpensive Apple II+ microcomputer as an extension of an earlier program library (NEUREC) for three-dimensional reconstruction. Application examples of neuronal and cardiac tissues are presented.

Animals↗
PubMed1984

[Early diagnosis of postinfarction ventricular aneurysm. Value of contrast scintigraphy].

Early diagnosis of a ventricular aneurysm after myocardial infarction may provide a valuable means of preventing certain complications. We studied 55 patients with acute myocardial infarction on the 8th day by Technetium 99 angioscintigraphy with study of wall motion and ejection fraction at equilibrium. The results were compared with left ventriculography performed three months after infarction. Angioscintigraphy demonstrated 17 cases of dyskinesia, 16 cases of hypokinesia, and 22 cases of akinesia, divided into two subgroups depending on whether the ejection fraction was lower (n = 11) or higher than 40% (n = 11). Contrast angiography at 3 months confirmed the presence of 27 aneurysms, 17 akinetic plaques and 11 cases of hypokinesia. Comparison between the two series of investigations showed excellent correlations: in the group of dyskinesia (17 cases) an aneurysm was confirmed in 15 cases; in the group of hypokinesia (16 cases) only one aneurysm was demonstrated by the reference angiography. The results were less uniform in the group with akinesia. In the subgroup with a low ejection fraction, 9 out of 11 cases progressed to aneurysm and, in retrospect, should be considered as likely aneurysms. There were only 2 aneurysms (2/11) in the subgroup with localised akinesia and a high ejection fraction. The overall results suggest that angioscintigraphy at the 8th day of myocardial infarction is a reliable means of detecting left ventricular aneurysm; in cases of dyskinesia or widespread akinesia with an ejection fraction of less than 40% the presence of an aneurysm was confirmed in 24 out of 28 patients (86%).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1982

[The electrophysiologic effects of intravenously administered bepridil].

The electrophysiological effects of intravenous bepridil were studied at doses of 2 mg/kg and 3 mg/kg. The drug was tested on 25 patients of both sexes who were undergoing electrophysiological investigation for other reasons (11 normal ECGs, 11 pathological ECGs, 3 WPW syndromes). Electrophysiological parameters before and after bepridil were compared. The following changes were noted: - the refractory period was significantly prolonged at all conducting levels; - the sinus cycle was significantly lengthened in a practically constant fashion (+9,2 p. 100); - conduction in the sinoatrial and atrioventricular nodes was significantly prolonged (+15 p. 100 and + 11 p. 100); - the Luciani-Wenckebach point was significantly decreased in the anterograde, and even more so in the retrograde, directions (-20 and -23 p. 100 respectively); - however, infrahisian conduction was not affected either in patients with normal or pathological ECGs. The drug was effective in blocking the accessory pathway in two of the three patients with the WPW syndrome. A study of drug plasma levels did not show a dose-effect relationship. The plasma levels were extremely variable from one subject to another, suggesting tissue fixation of the active part of the molecule. These results demonstrate the valuable electrophysiological effects of bepridil which, by its mode of action, is very similar to amiodarone.

Adult↗
PubMed1981

Local light stimulation of isolated chromatophores of the sea urchin Centrostephanus longispinus.

The dark-reaction (pigment aggregation) of isolated, light-sensitive pigment cells of the sea urchin Centrostephanus longispinus was monitored using IR-microscopy. It differs in time course and mode of pigment displacement from the inverse process of pigment dispersion in white light. Partial illumination of darkness respectively causes locally different and appropriate pigment movements in the individual cell regions. Spot-illumination of a cell process of an otherwise darkened chromatophore leads to local pigment dispersion (from thd dark-adapted state) or aggregation (from the light-adapted state) exactly to the point of stimulation, while the pigment cell shows normal dark-reaction in all other regions. The results indicate that the pigment granules do not bear the receptor pigment, rather it may be expected in the whole cell membrane. The observation of contrary translocations in different regions of the cell support the concept of a local mechanism of granule movement regulated in a very precise manner.

Animals↗
PubMed1980

Ultrastructural observations on changes in cell shape in chromatophores of the sea urchin Centrostephanus longispinus.

Alterations in cell shape of the light-sensitive chromatophores of the sea urchin Centrostephanus longispinus were studied by scanning- and transmission electron microscopy. Transition of the aggregated to the dispersed state is accompanied by incorporation of vesicles into the membrane of the pigment cell. During disperson a system of microtubules originating from centriole-like structures is established throughout the stellate cell. Within restricted areas of the cell, cytoplasmic differentiation and condensation is found. The possible functional significance of the findings is briefly discussed.

Animals↗
PubMed1979

[Hemodynamic effects of hydralazine in the cardiac insufficiency of non-obstructive myocardiopathy].

The haemodynamic effects of a single dose of between 0.15 and 0.25 mg/kg hydralazine were studied during cardiac catheterisation of 9 patients with primary congestive cardiomyopathy and heart failure. The systemic arterial resistances decreased (--1 370 +/- 400 dynes/s.cm-5/m2, p less than 0.05); the reduction of pulmonary arterial resistances was less marked (--420 +/- 400 dynes/s.cm-5/m2, p less than 0.05). Intraaortic pressure was reduced (--16 +/- 12 mmHg, p less than 0.02) as was average pulmonary arterial (--4.2 +/- 4,2 mmHg, p less than 0.05) and left ventricular end diastolic pressures (--4.2 +/- 3.0 mmHg, p less than 0,02). Systolic index increased in all cases (+13 +/- 5 ml/syst/m2, p less than 0.001). Heart rate was unchanged. This was due to the improvement of left ventricular function by the reduced impedence. These results confirm the place of hydralazine in the treatment of certain forms of heart failure.

Adult↗
PubMed1978

[Clinicopathological study of the causes of mortality during the acute phase of myocardial infarction (author's transl)].

Clinical and autopsy study of 100 cases of patients dying during the first 3 weeks of hospitalisation for myocardial infarction revealed the following causes of death: cardiac failure in 59 cases (including 40 of cardiogenic shock), rupture of the heart in 29 cases (24 of rupture of the ventricular wall, 4 of the septum and 1 of a mitral papillary muscle). 4 ventricular arrhythmias and 6 haemorrhagic or embolic complications. In 2 cases, the cause of death could not be accurately determined. In cardiogenic shock, death usually occurred early. It was later in cases of refractory left ventricular failure. Conduction disturbances were much commoner in cases of myocardial infarction complicated by fatal cardiac failure (57.6%) than in the presence of any other complication (17.1%) (p less than 0.001). The responsible infarction was often extensive and recurrent. Rupture of the heart invariably occurred during the first three days of an infarction often initial (p less than 0.001), anterior (apart from septal rupture) and small in size (p less than 0.01). Other complications play only a secondary role in mortality at the present time, in particular arrhythmias, the gravity of which has greatly decreased since the reduction of delays before hospitalisation and improvements in anti-arrhythmic therapy.

Acute Disease↗
PubMed1977

[Rupture of an infective aneurysm of the sub-renal abdominal aorta into the inferior vena cava. One case (author's transl)].

An aorto-caval fistula developed in a 62-year-old woman secondary to the rupture of an infective aneurysm of the aortic bifurcation. Treatment in relation to local and, above all, general infection is discussed, emphasising the value of epiplooplasty and prolonged appropriate antibiotic therapy. However, adequate follow-up is essential in order to be able to affirm cure, recurrence of the infectious process always being possible, even late.

Anti-Bacterial Agents↗