Biomedical subjects

D Garnier

Publications and source records attributed to D Garnier.

At least 37 records · Page 2Linked to original sources

PubMed1993

A simple method for calibrating collagenase/pronase E ratio to optimize heart cell isolation.

A mixture of crude collagenase and non-specific proteases has been used to isolate guinea pig ventricular heart cells. Measurements of collagenase activity with Wünsch's substrate and protein content with sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) suggest that collagenase enzymes do not play a major role in heart cell isolation. On the other hand, an important factor in heart digestion seems to consist of some fractions of the proteases present in crude collagenase. It is also noted that crude collagenases do not present any sensitivity to added calcium but because this ion is important to obtain isolated cells its role is discussed. According to our results, the SDS-PAGE method can be used to determine the appropriate enzyme concentrations to obtain calcium-tolerant myocytes. These myocytes have electrophysiological properties as reported in the literature.

Amino Acid Sequence↗

PubMed1993

The effects of increasing cell length on auxotonic contractions; membrane potential and intracellular calcium transients in single guinea-pig ventricular myocytes.

Until recently the investigation of length-dependent effects in cardiac muscle was restricted to multicellular preparations. We describe our experimental set-up which for the first time, in single cardiac myocytes, permits the effects of changes in cell length on auxotonic contractions (measured by carbon fibre transducers) to be simultaneously recorded with the effects on membrane potential and/or changes in intracellular calcium concentration (using indo-1 AM, acetoxylmethyl form). Consistent with previous findings (in experiments at 20-25 degrees C and 0.25 Hz) we report that following a stretch there was an increase in passive tension and contraction. A stretch which increased sarcomere length by approximately 3% had no significant effect on resting membrane potential or action potential amplitude. There was, however, a significant decrease in the action potential duration (P < 0.01, n = 8). No significant change in the amplitude of the intracellular calcium transient was seen following a stretch but a reduction in its duration was observed (P < 0.025, n = 11). Our observations on intracellular calcium transients are consistent with the hypothesis that, in mechanically loaded preparations, their time course is more dependent on changes in tension than changes in length.

Animals↗

PubMed1993

[Forum on tissue expansion. Fast continuous expansion. A 3-years evaluation of its use from a retrospective study of 78 cases].

The authors report their experience of cutaneous expansion in a retrospective study of 78 cases. They compare the two methods usually applied: discontinuous slow expansion in two thirds of cases versus rapid continuous expansion in one third of cases. Both methods, as they are defined in the department, are described. Statistical analysis revealed two important facts: the complication rate was considerably lower in continuous expansion. Length of hospital stay was similar for both techniques. The results, not yet studied in a strictly scientific way, do not appear to argue against continuous expansion. Rapid cutaneous expansion may be considered to be a valuable technique in the future, but it must be chosen for certain people only and must be adapted to each patient.

Adolescent↗

PubMed1993

[Congenital coronary-cardiac fistula. Diagnosis by color Doppler echocardiography in an infant].

The authors report the case of a 2 month old child in whom a coronary artery fistulae was diagnosed by colour Doppler echocardiography. Routine two-dimensional echocardiography showed a very dilated right coronary artery. Turbulent flow was detected in this vessel by pulsed Doppler echocardiography. Colour Doppler showed the fistulous connection to the inferior wall of the right ventricle. Until recently, this condition could only be diagnosed by selective angiography and coronary arteriography. Although there have been few reports in the literature, colour Doppler echocardiography would seem to be a significant advance in non-invasive diagnosis of abnormal connections of the coronary arteries. It allows the differential diagnosis of coronary aneurysm, ectopic coronary arteries and sinus of Valsalva aneurysms to be excluded. The patients can be followed up by colour Doppler echocardiography and anatomic information can be obtained to guide surgery, notably the site of drainage of the fistula. Coronary artery fistulae presenting clinically with a continuous murmer atypically situated for a patent ductus arteriosus are difficult to detect by conventional echocardiography and usually required cardiac catheterisation and angiography. Color Doppler echocardiography is a valuable non invasive diagnostic tool for this condition. The others report the case of a coronary artery cardiac fistula in a neonate diagnosed by color Doppler echocardiography.

Age Factors↗

PubMed1992

Alteration of the L-type calcium current in guinea-pig single ventricular myocytes by heptaminol hydrochloride.

1. The effects of heptaminol on calcium current amplitude and characteristics were studied in single ventricular myocytes of guinea-pig by use of the whole cell configuration of the patch clamp technique. 2. A concentration-dependent decrease in ICa amplitude was observed. At heptaminol concentration as low as 10(-6) M, this effect was observed in only two cells (n = 6). At 10(-5) M the reduction of ICa was of 30 +/- 15% (n = 11). 3. The current recovery from inactivation at -40 mV holding potential (HP) seemed less sensitive to perfusion with heptaminol (greater than 10(-6) M). However, at -80 mV HP the overshoot of the recovery curve was decreased by heptaminol. 4. Both at -40 mV and -80 mV HP, heptaminol (10(-5) M) significantly increased the steady state inactivation of ICa. 5. As previously proposed by others to explain the effects of membrane active substances, the effects of heptaminol may result from alterations in cell membrane properties and possibly from an increase in intracellular free calcium ion concentration.

Animals↗

PubMed1992

Rate dependence of action potential duration and calcium current in isolated guinea-pig cardiocytes.

The duration of the action potential at 50% of its amplitude (APD50) and peak calcium currents (ICa) was measured in single cardiac guinea-pig ventricular cells, using the whole-cell patch-clamp technique in current-clamp and voltage-clamp modes respectively. In the absence of intracellular calcium buffer, pacing at 0.28 Hz from a rest period of 1-2 min induced a transient increase (15.5 +/- 3.5%) in APD50, followed by a gradual shortening. Switching from 0.28 to 0.75 Hz again induced a transient increase of APD50 (6.8 +/- 2.9%). In the presence of EGTA or BAPTA on the cytosolic side of the membrane, this transient phase was prolonged and its amplitude slightly increased (10.6% when switching from 0.28 to 0.75 Hz in 5 mM-BAPA). The same increase in rate induced either a negative or a positive staircase of ICa, depending on the holding potential. At a holding potential of -80 mV, ICa peak was enhanced and the inactivation kinetics was slowed down. This facilitation of ICa seems to be dependent on calcium ions entering the cell via the calcium channels and could partly explain the observed transient increase in APD50.

Action Potentials↗

PubMed1991

Differences in the hypoxic contraction of small isolated pulmonary arteries of cat and rabbit.

In small (less than 300 microns diameter) pulmonary arterial (PA) rings isolated from the cat, hypoxia induced a transient contraction (250 +/- 120 mg, n = 7), whereas in rings of rabbit PA of the same size, hypoxia had no significant effect (n = 19). Precontraction by 40 mmol KCl.1(-1), noradrenaline (NA) 10(-6) mol.1(-1), or histamine (His 10(-5) mol.1(-1)) did not modify this difference between the two species and did not potentiate the hypoxic contraction of small rings of the cat PA. Large rabbit pulmonary arterial segments (300-2000 microns) exhibited no response to hypoxia before precontraction (n = 15). In the presence of procaine (2%) rabbit PA rings (n = 6, small) exhibited no hypoxic contraction. These results in vitro reflect previous in vivo observations.

Animals↗

PubMed1991

Stretch-induced increase of resting intracellular calcium concentration in single guinea-pig ventricular myocytes.

Single guinea-pig ventricular myocytes were loaded with the fluorescent Ca2+ indicator Indo-1 AM and stretched by carbon fibres. Stretching increased resting tension. Sarcomere lengths were increased by 2-18%. It was observed that a stretch increased resting [Ca2+]i in seven out of eight cells. The change in [Ca2+]i increased with the size of the stretch and returned to pre-stretch levels on return to resting cell length. These observations suggest a means by which changes in resting muscle length can modify the contractile state of cardiac muscle.

Animals↗

PubMed1991

[Rapid tissue expansion: value of the measurement of the transcutaneous oxygen pressure and intraprosthetic pressure].

Tissue expansion is often unpleasant for the patient because of its long duration. The authors present a series of 16 rapid expansion prostheses implanted in 10 patients. The expansion was monitored by measuring the percutaneous oxygen partial pressure and intraprosthetic pressure. The expansions were performed without any complications. Monitoring of the expansion by measuring the pcPO2 appears to ensure good results.

Adolescent↗

PubMed1991

[The inframammary fold: myth or reality?].

Is the inframammary fold an anatomical entity? In order to answer this question, the authors conducted an anatomical, histological and radiological study. The results of these studies were concordant and were able to anatomically define the inframammary fold. The inframammary fold corresponds to a division of the fascia superficialis. It contains numerous fibres stretched between the fascia superficialis and the fascia prepectoralis. In contrast, there are no fibres connecting the fascia superficialis to the deep dermis.

Adult↗

PubMed1991

[Orbital neurofibrosarcoma. Clinical and etiological study; apropos of a case].

This case report is about a relapsing conjunctive sarcoma affecting a 67 year old woman, involved with Von Recklinghausen's neurofibromatosis. Surgical orbital exenteration was necessary for curative treatment and reconstruction used a temporal muscle flap. Through this report, emphasis is placed on diagnosis difficulties and possibility of serious development concerning these malignant tumors in the scope of neurofibromatosis.

Aged↗

PubMed1990

A new method of attachment of isolated mammalian ventricular myocytes for tension recording: length dependence of passive and active tension.

The study of the Frank-Starling's law in mammalian single cells has been hindered by a lack of an easily performed method of stretching cells. Some authors have succeeded in this but their methods required a great deal of technical expertise and in most cases they have not had much success. We have developed an easy method of stretching mammalian ventricular cells from slack sarcomere length (S.L.) (Lo, 1.77 +/- 0.05 microns) to about 117% of this length. Thin carbon fibers (12 microns in diameter) which can be bound electrochemically to the cell membrane surface have been used. A flexible long fiber of known compliance (80 microns/microN) was attached to one end of the cell and a stiff double fiber (4 microns/microN) to the other end. The cell attachment was relatively easy to perform and successful results were obtained in 80% of the attempts. The displacement of the flexible fiber allows the quantitative measurements of the resting tension in a group of non-stimulated cells and of auxotonic contractions developed upon stimulation in another group of cells. Increasing S.L. from Lo to 105-106% of Lo, an increase in active tension from 0.21 +/- 0.03 mN/mm to 0.26 +/- 0.01 mN/mm (n = 4) could be noticed with a stimulation frequency of 0.5 Hz. An increase in active tension was also observed at 1 Hz. Staircase kinetics were accelerated with stretching; this confirms at the single cell level the hypothesis of an effect of length-dependent activation on the staircase. Eulerian differential stiffness constant was calculated and found to be 13.5 +/- 1.2, a value which is comparable to that described in intact heart. Thus the important stiffness found in the whole heart may be due to intracellular component(s) such as myofilament and/or connectin.

Animals↗

PubMed1990

[Tangential injuries and hematoma. Application of liposuction combined with biological glue].

The authors report an unconventional method of management in hematomas complicating tangentiel trauma. They use the application of liposuction within the first days, this procedure allow complete removal of the clots. It is associated with a biological glue sprayed all over the skin detachment. This simple operative technique is carried out under local anaesthesia and minimizes the recurrence of hematoma. The long term morphological result is satisfactory, avoiding the sequelae of conventional procedures.

Hematoma↗

PubMed1990

[Repetitive inhalation anesthesia in rats].

Inhalational anesthesia in the rat seems a good process, by a rapid induction and awakening if a steady state ventilation-perfusion ratio and no pollution are obtained. Animals are cooped up in an "induction-box" which is joined to a scavenger system. Anesthesia maintenance is assumed with a Bain circuit and allows short and frequent anesthesia. Isoflurane does not markedly decrease circulatory and respiratory factors at low concentration (2%). So any anaesthetist can do himself such a practical system.

Anesthesia, Inhalation↗

PubMed1989

Contractile responses to hypoxia of isolated rings from the left branch of rabbit pulmonary artery.

Contractile responses of left extrapulmonary artery segments with either intact or damaged endothelium were examined with changes in PO2 at constant pH. Hypoxia consistently reduced noradrenaline-induced contractions. This hypoxia-induced relaxation was sometimes followed by a contraction and a second relaxation. Hypoxia-induced relaxations were also obtained if precontraction was elicited with KCl (40 mM), but no triphasic response was observed. Relaxations faded away with time and only contractions were then observed. Relaxations were more considerable in rings from young animals and, although always present, decreased with the age of the animal. Endothelium damage reduced hypoxia-induced relaxations. Indomethacin, a potent blocker of cyclooxygenase, increased hypoxia-induced contraction and reduced relaxation in segments with intact endothelium. Without endothelium the indomethacin effect was less significant. It is concluded that the response to hypoxia of the pulmonary artery is similar to that of systemic vessels. Endothelium seems to play a modulatory role in the hypoxia-induced response in extrapulmonary artery. Prostaglandin metabolism seems to play a minor role in this modulation.

Acetylcholine↗

PubMed1989

Decrease in internal H+ and positive inotropic effect of heptaminol hydrochloride: a 31P n.m.r. spectroscopy study in rat isolated heart.

1. The cardiotonic effect of heptaminol hydrochloride (Hept-a-myl, Delalande) was studied using 31P-nuclear magnetic resonance (n.m.r.) spectroscopy and left ventricular pressure (LVP) measurements in rat isolated hearts. The possibility of this effect being mediated by an intracellular realkalinisation was tested. 2. Isolated hearts were perfused at 10 ml min-1 by the Langendorff method with Krebs-Henseleit solution at 37 degrees C and stimulated at 5 Hz. Mechanical activity was measured as variations of left ventricular pressure (LVP). 31P-n.m.r. spectra were recorded every 2 min. Changes in cardiac adenosine triphosphate (ATP), phosphocreatine (PCr) and inorganic phosphate (Pi) were followed and intracellular pH (pHi) was estimated from the chemical shift of Pi. 3. The effects of heptaminol were tested in different conditions: normoxia, moderate ischaemia, severe ischaemia, and moderate ischaemia in the presence of amiloride or guanidinium chloride as inhibitors of the Na-H exchange. 4. In normoxia, heptaminol induced a cyclic increase of systolic LVP, associated with an increase in Pi. No significant effect on pHi was observed. In changing from normoxia to moderate ischaemia, PCr and systolic LVP decreased; a mild intracellular acidification (pHi 6.96) was obtained. Heptaminol induced a restoration of pHi and increased LVP. In severe ischaemia, the realkalinization effect and the restoration of LVP induced by heptaminol were no longer observed. During moderate ischaemia, Na-H exchange inhibitors decreased pHi and LVP. Heptaminol applied in the presence of these inhibitors was unable to restore pHi and LVP. In severe ischaemia, the realkalinization effect and the restoration of LVP induced by heptaminol were no longer observed. During moderate ischaemia, Na-H exchange inhibitors decreased pHi and LVP. Heptaminol applied in the presence of these inhibitors was unable to restore pHi and LVP. 5. These results suggest that the positive inotropic effect of heptaminol during moderate ischaemia could be related to a restoration of internal pH, possibly mediated by a stimulation of the Na-H exchange.

Alkalosis↗

PubMed1989

Gossypol-induced modifications in the microenvironment of rat epididymal spermatozoa.

Gossypol acetic acid (20, 25 or 30 mg/kg/day orally for 5 weeks) decreased epididymal weight in adult Sprague-Dawley rats but the epididymal concentrations of proteins, lactate dehydrogenase and acid phosphatase were unchanged. The concentrations of carnitine, inositol and potassium in epididymal fluid were decreased in a dose-related manner. These modifications were not due to disturbances of Leydig and Sertoli cell functions which were normal. We suggest that the reduction in epididymal secretion results from a decrease in the number of spermatozoa rather than from a direct action of gossypol on the epididymal epithelium.

Animals↗

PubMed1989

[Spinocellular epithelioma of the hand. Apropos of a diffuse and extensive commissural form].

The authors report a case of squamous cell carcinoma of the hand unusual because of its very rapid extension: A 64 year old man was referred to us for treatment of a keratoacanthoma located in the thumb web (histological diagnosis on two occasions). In fact, the histological frozen-section examination at the time of surgery revealed a well differentiated squamous cell carcinoma. A wide excision of the tumor was carried out together with amputation of the index finger according to Chase's technique. Axillary lymphadenectomy was performed due to clinical evidence of regional lymphatic spread (large node) twenty one days following surgery. Four months later, a recurrence in the thumb web required radiocarpal disarticulation. Three months later, a new recurrence at the stump, spreading to the forearm, necessitated an above-elbow amputation. In relation to this unusual case, the authors emphasize the importance of initial diagnosis and the difficulties of surgical management of this tumor, especially in palmar and web or deep locations.

Amputation, Surgical↗