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Biomedical subjects

M Franck

Publications and source records attributed to M Franck.

At least 19 recordsLinked to original sources
PubMed2006

Could the pale, soft, and exudative condition be explained by distinctive histological characteristics?

Pork quality depends on various genetic and environmental factors. Despite the improvement of slaughter conditions, the PSE type is still one of the main concerns in this field. This study was conducted on nonstressed animals to evaluate the tissue characteristics of some muscles usually involved during stress compared with a reference muscle, the M. triceps brachii, which is actually not subject to stress-caused damages. Samples of M. triceps brachii, M. longissimus dorsi, M. biceps femoris, and M. semimembranosus were taken from pigs exhibiting 1 of the 3 HAL genotypes (NN, Nn, or nn) and 2 of the 3 RN genotypes (rn+rn+ or rn+RN-). Histoenzymology and immunohistochemistry were used to compare the fiber typing and capillary network in these muscles within these different stress susceptibility genotypes. In comparison with the reference muscle, M. triceps brachii, the combination of a high value of the number of type IIb fibers and a low vascular network showed a primary effect on muscles usually involved during stress. This led to the definition of a PSE index. A dramatic increase (P < 0.001) in this PSE index was systematically found in muscles usually involved in the PSE-type condition. These results show that distinctive histological characteristics were associated with the vulnerability of some muscles independently of the genotypes. Moreover, this study highlights the distinctive histological features of each genotype and is likely to suggest some interactions between them.

Animals↗
PubMed2006

[Ovarian tissue vitrification: Cortex and whole ovary in sheep].

OBJECTIVE: The aim of this study was to evaluate a cryopreservation technique by vitrification of cortex or whole ovaries in sheep, using two cryoprotectant solutions: VS1 and VS4 and to study their physical properties to avoid ice crystallisation by vitrification of whole sheep ovaries permeated with a cryoprotectant solution. ANIMALS AND METHODS: From 6-month-old ewes, whole sheep ovaries with their vascular pedicles were collected at the slaughterhouse or at the veterinary school and prepared for cryoprotectant toxicity tests and freezing procedure. Follicle viability was measured by trypan blue test and histological examination of ovary. The hemi-ovarian cortex was stored in liquid nitrogen. Four to six weeks after the first laparotomy, the controlateral ovary was removed and the vitrified-warmed hemi-ovary was sutured. Thermal properties of a cryoprotectant solution called VS4 (critical cooling rates [Vccr], vitreous transition temperature [Tg], end of melting temperature [Tm]) were measured by differential scanning calorimetry. RESULTS: No significant difference in follicle viability or normal follicle rates was observed between ovarian cortex exposed or non-exposed to cryoprotectant solutions. Nor was any significant difference observed before and after vitrification. Three pregnancies occurred, from which four lambs were born after autografts of vitrified ovarian cortex. With whole ovary, the decrease in the number of normal follicles was lower when frozen-thawed ovaries were treated with VS4 (P = 0.04). There were less nuclear anomalies (P = 0.02). The Vccr of VS4 has been estimated to be 14.3+/-1.1 degrees C/min and Tg was -125.0+/-0.2 degrees C. Because the penetration of cryoprotectants was very low, Vccr was very high and the cooling speed did not allow cortex to vitrify. DISCUSSION AND CONCLUSIONS: Cryopreservation of cortex or whole ovary by vitrification seems a promising technique in reproductive medicine. The best histologic results were obtained with the VS4 cryoprotectant when whole ovary was vitrified.

Animals↗
PubMed2001

Follicular viability and morphology of sheep ovaries after exposure to cryoprotectant and cryopreservation with different freezing protocols.

OBJECTIVE: To test the toxicity of cryoprotectant in sheep ovarian tissue and to determine optimal conditions for freezing hemiovary cortex. DESIGN: Small follicles (<60 microm in diameter) were isolated enzymatically for viability testing. Dead and live follicles were identified by using trypan blue staining, and follicle morphology was examined histologically. SETTING: Centre hospitalo-universitaire de Biologie de la Reproduction, Hôpital Edouard Herriot, Lyon, France. ANIMAL(S): Lambs 5 to 6 months of age. INTERVENTION(S): Two-millimeter slices of hemiovarian cortex were prepared for cryoprotectant toxicity tests and freezing procedures. MAIN OUTCOME MEASURE(S): Follicular mortality and histologic structure. RESULT(S): For freezing procedures, the concentration of cryoprotectant was increased to 2 M on the basis of results of cryoprotectant toxicity tests in fresh tissues. Follicular mortality rates were 4.6% with of 2 M dimethyl sulfoxide (DMSO) and 3.8% with 2 M of propylene glycol (PROH). After freezing with semiautomatic seeding, follicular mortality rates were 8.4% (2 M of DMSO) and 12.4% (2 M of PROH). Tissue morphology was well preserved with 1.5 M of DMSO or PROH. With 1.5 M DMSO, results of the slow cooling protocol (2 degrees C/min) without seeding and the standard very slow cooling protocol (0.3 degrees C/min) were similar. CONCLUSION(S): Optimal survival of primordial follicles in the sheep was obtained by using a slow cooling protocol with semiautomatic seeding at 2 M of DMSO.

Animals↗
PubMed2000

Better preservation of endothelial function and decreased activation of the fetal renin-angiotensin pathway with the use of pulsatile flow during experimental fetal bypass.

OBJECTIVE: Pulsatile flow was shown to overcome the progressive rise in peripheral and placental vascular resistances observed during steady-flow bypass, this rise being counteracted by inhibition of nitric oxide synthase. This study quantifies the release of endothelial vasoactive substances during a 60-minute in utero model of fetal bypass. METHODS: Fetuses were randomly allocated into 1 of 2 groups (steady flow, n = 8, or pulsatile flow, n = 13) and subjected to bypass through central cannulation and perfusion with either a centrifugal or pulsatile (125 beats x min(-1)) blood pump. RESULTS: Lactate concentration was high, starting at fetal exteriorization and increasing during fetal preparation in the 2 groups. Once bypass was established, the rise was significant only in the steady-flow group. Plasma nitric oxide metabolites, similar before bypass, reached higher levels during pulsatile flow at the end of bypass (99+/-9 vs. 82+/-23 micromol x L(-1); P =.037). Levels of urinary nitric oxide metabolites were significantly higher in the pulsatile-flow than in the steady-flow group (764+/-143 vs. 508+/-240 micromol x L(-1); P =.005). Plasma cyclic guanosine monophosphate levels increased after 30 minutes of bypass in the pulsatile-flow group (25+/-18 vs. 12+/-8 pmol x mL(-1); P =.004), and urinary cyclic guanosine monophosphate excretion was higher in the pulsatile-flow group (517+/-450 vs. 118+/-78 pmol x mL(-1); P =.024). Plasma endothelin-1 levels increased in the 2 groups and were higher in the steady-flow group at 30 minutes (27+/-5 vs. 23+/-2 pg x mL(-1); P =.04) and 60 minutes of bypass (39+/-7 vs 32 +/- 6 pg x mL(-1); P =.04). Plasma renin concentration increased significantly during bypass only in the steady-flow group (26+/-10 vs. 57+/-42 in ng A1 x mL(-1) x h(-1); P =.04). CONCLUSIONS: Improved placental and peripheral perfusion during fetal pulsatile-flow bypass may be mediated by preservation of fetal/maternal endothelial nitric oxide biosynthetic mechanisms and/or decreased activation of the fetal renin-angiotensin pathway.

Analysis of Variance↗
PubMed1999

Restoration of ovarian steroid secretion and histologic assessment after freezing, thawing, and autograft of a hemi-ovary in sheep.

OBJECTIVE: To evaluate the effects of freezing, thawing, and autograft of a hemi-ovary on steroid secretion, endometrial maturation, and ovarian histology in ewes. DESIGN: Experimental animal study. SETTING: Laboratoire de Zootechnie, Ecole Nationale Vétérinaire, Marcy l'Etoile, France. ANIMAL(S): Six lambs aged 6 months to 1 year old. INTERVENTION(S): Hemi-ovaries were prepared and frozen from the right ovary of six lambs and autografted 4 weeks later to the contralateral ovarian hilus. The autografts and the uterus were recovered 1 year later. Blood tests were performed each week to measure P concentration. MAIN OUTCOME MEASURE(S): Number of primordial follicles; levels of plasma P. RESULT(S): Histologic examination of ovarian slices after freezing showed no destruction of primordial, primary, secondary, or cavitary follicles. The frozen ovarian autograft showed good recovery of the macroscopic and microscopic ovarian structure. After autografting, histologic examination revealed primordial to cavitary follicles. Secretion of P started to rise 4 weeks after the autograft. Histologic analysis of the endometrium showed numerous glands, vessels, and mucous secretion. CONCLUSION(S): Frozen ovarian autografts achieved P secretion and endometrial maturity.

Animals↗
PubMed1999

Pulmonary embolism and cor pulmonale in a cat.

A 14-year-old male neutered cat experienced pulmonary embolism 15 days following surgical debridement of a recurrent dorsolumbar abscess. Clinical signs were dominated by respiratory distress. Pulmonary embolism was suggested from the lateral thoracic radiograph by the presence of an abruptly attenuated lobar artery and a contiguous oligaemic area in the caudal lung lobe. Pulmonary hypertension was demonstrated on Doppler echocardiography by right pulmonary artery dilation and tricuspid regurgitation raising the pulmonary arterial pressure to 56 mmHg. Chronic pulmonary hypertension, assumed from right ventricular wall hypertrophy, and hypokinesia, indicating chronic cor pulmonale, was suggestive of chronic rather than acute pulmonary embolism. Postmortem histological evidence of pulmonary arteriolar occlusion confirmed the diagnosis of pulmonary embolism.

Abscess↗
PubMed1999

Neonatal Soave endorectal pull-through for Hirschsprung's disease.

In October 1994 we changed our management of neonatal Hirschsprung's disease from a staged procedure after initial colostomy to a neonatal single-stage Soave endorectal pull-through (SERPT) without a colostomy. We report on our experience with the first 12 neonatal SERPTs, comparing them retrospectively with a consecutive series of 12 patients managed with initial colostomy, followed by a SERPT months later. A neonatal SERPT proved to be an easier and quicker procedure than the same procedure in the older child. Patients could be discharged earlier and fewer complications were encountered; in addition a colostomy was avoided. The cosmetic result and parental acceptance were excellent. At the same time the cost was less than half compared with the staged group. At this stage of follow-up functional results are comparable with previous staged pull-through procedures.

Anastomosis, Surgical↗
PubMed1998

Freezing, thawing, and autograft of ovarian fragments in sheep: preliminary experiments and histologic assessment.

OBJECTIVE: To evaluate the effects of freezing and thawing on the histologic changes in ovarian fragments from sheep and to determine the feasibility of ovarian autografts. DESIGN: Histologic evaluation of follicles that survived after freezing at -196 degrees C for 2 weeks. Histologic evaluation of ovarian fragments 6 months after the autografts. SETTING: Laboratoire de Zootechnie, Ecole National Véterinaire, Marcy l'Etoile, France. ANIMAL(S): Six ewes aged 6 months to 1 year. INTERVENTION(S): Cortical fragments were prepared from the right ovary of 6 lambs and were grafted immediately to the contralateral ovarian hilus or were cooled slowly to -196 degrees C in medium containing dimethyl sulfoxide for 2 weeks. The autografts were recovered 6 months later. RESULT(S): Histologic examination of ovarian slices after freezing showed no destruction of primordial, primary, secondary, or cavitary follicles. The ovarian autograft showed good recovery of the macroscopic and microscopic ovarian structure. After autografting, histologic examination revealed primordial to cavitary follicles. CONCLUSION(S): Freezing of ovarian fragments is possible without damaging the follicles. Ovarian autografts showed good recovery of ovarian structure.

Animals↗
PubMed1998

Effects of various flow types on maternal hemodynamics during fetal bypass: is there nitric oxide release during pulsatile perfusion?

OBJECTIVE: This study investigates the role of various flow conditions on maternal hemodynamics during fetal cardiopulmonary bypass. METHODS: Normothermic fetal bypass was conducted under pulsatile, or steady flow, for a 60-minute period. Fetal lamb preparations were randomly assigned to 1 of the 3 groups: steady flow (n=7), pulsatile flow (n=7), or pulsatile blocked flow bypass (n=7), where fetuses were perfused with Nomega-nitro-L-arginine after the first 30 minutes of pulsatile flow to assess the potential role of endothelial autacoids. RESULTS: Maternal oximetry and pressures remained unchanged throughout the procedure. Under fetal pulsatile flow, maternal cardiac output increased after 20 minutes of bypass and remained significantly higher than under steady flow at minute 30 (8.8+/-0.7 L x min(-1) vs 5.9+/-0.5 L x min(-1), P=.02). Maternal cardiac output in the pulsatile group also remained higher than in both steady and pulsatile blocked flow groups, reaching respectively 8.7+/-0.9 L x min(-1) vs 5.8+/-0.4 L x min(-1) (P=.02) and 5.9+/-0.3 L min(-1) (P=.01) at minute 60. Maternal systemic vascular resistances were significantly lower under pulsatile than under steady flow after 30 minutes and until the end of bypass (respectively, 9.1+/-0.6 IU vs 12.7+/-1.1 IU, P=.02 and 8.9+/-0.5 IU vs 12.9+/-1.2 IU, P=.01). Infusion of Nomega-nitro-L-arginine was followed by an increase in systemic vascular resistances from 9.3+/-0.7 IU, similar to that of the pulsatile group, to 13.5+/-1 IU at 60 minutes, similar to that of the steady flow group. CONCLUSIONS: Maternal hemodynamic changes observed under fetal pulsatile flow are counteracted after infusion of Nomega-nitro-L-arginine, suggesting nitric oxide release from the fetoplacental unit under pulsatile fetal flow conditions.

Animals↗
PubMed1998

Experimental right ventricle to pulmonary artery discontinuity: outcome of polyurethane valved conduits.

OBJECTIVE: The ideal substitute for the treatment of ventricle-pulmonary artery discontinuity remains a topic of controversy, because of calcifications and degeneration of biologic substitutes leading to subsequent reoperations. Because polyurethane valves used in ventricular assist devices show a satisfactory biocompatibility, the aim of this study was to evaluate a valved conduit composed of a Dacron graft incorporating a trileaflet 25 mm polyurethane valve. METHODS: The conduit was implanted between the right ventricle and the main pulmonary artery in adult sheep, with ligation of the proximal pulmonary artery. The animals received no medications. Serial hemodynamic data were collected at the time of implantation and at postoperative intervals of 6 and 12 months. RESULTS: The peak pressure gradient across the valve increased significantly between implantation (0.17 +/- 5.6 mm Hg) and 6 months after operation (7.3 +/- 3 mm Hg, p = 0.0007) and remained stable thereafter (6.7 +/- 3 mm Hg at 12 months), whereas the cardiac output remained unchanged (4.6 +/- 0.6 L/min at implantation, 4 +/- 0.6 L/min at 6 months, and 3.9 +/- 1.1 L/min at 12 months). At the completion of the study, valve samples were processed and vapor coated with carbon for microscopic examination. There was one instance of nonadherent thrombus formation inside a cusp but no structural failures. The other valves were free of calcium deposits and no significant amounts of phosphorus could be detected by scanning electron microscopy and energy dispersive spectrometry. CONCLUSIONS: These data demonstrate the good hemodynamic performance, low thrombogenicity, and acceptable durability of the polyurethane valves implanted in the right side of the heart in a chronic sheep model.

Animals↗
PubMed1998

The hemodynamic effects of hypoxemia in anesthetized pigs: a comparison between right heart catheter and echocardiography.

UNLABELLED: During hypoxemia, hypoxic pulmonary vasoconstriction and tachycardia are often observed in association with increases in pulmonary artery pressure and cardiac output. Nevertheless, the hemodynamic consequences of hypoxemia have never been evaluated by echocardiography and simultaneously compared with invasive hemodynamic variables. Fourteen open-chest, anesthetized piglets (weight 29-36 kg) were submitted to progressive hypoxemia and reoxygenation. Usual invasive hemodynamic variables were obtained from peripheral and central heart catheters. Direct epicardial echocardiography was used to measure right and left ventricular areas on a short-axis view at mid-papillary level. The mean pulmonary artery pressure (MPAP) increased with pulmonary vascular resistance in a dose-related manner as the fraction of inspired oxygen (FIO2) declined from 0.5 to 0.12. The MPAP correlated with right ventricular end-diastolic area (RVEDA) only at FIO2 0.08. There was a 49% reduction in left ventricular end systolic wall stress (LVESWS) between FIO2 0.5 and 0.08. Left ventricular ejection fraction area (LVEFA) increased by 33% above baseline and correlated with the decrease in LVESWS. No correlation was observed between left ventricular end-diastolic area and pulmonary artery occlusion pressure or left atrial pressure and between cardiac output and LVEFA. Systemic vascular resistance underestimates the magnitude of changes in LVESWS but overestimates the afterload compared with LVESWS. This study demonstrates that, for the lowest FIO2 (0.08), changes in MPAP correlated with changes in RVEDA but not in pulmonary vascular resistance. Moreover, LVESWS decreases significantly in a dose-related manner under progressive hypoxemia and normalizes immediately after reoxygenation. This study also shows that, under hypoxemic conditions, echocardiography enhances understanding of hemodynamic changes compared with right heart catheterization alone. IMPLICATIONS: Acute hypoxemia in pigs is responsible for pulmonary vasoconstriction-induced pulmonary hypertension (which is restricted by the right ventricular failure), as well as a PaO2-dependent decrease in left ventricular afterload. These changes are better displayed by echocardiography than by right heart catheter.

Anesthesia↗
PubMed1998

Cranial vena caval thrombosis secondary to invasive mediastinal lymphosarcoma in a cat.

A 12-year-old female cat was diagnosed with a cranial vena caval thrombosis in association with a mediastinal lymphosarcoma. The cause of the cranial vena caval thrombosis was thought to be invasion of the venous wall by neoplastic lymphoid cells. Clinical signs of cranial vena caval thrombosis, such as swelling and oedema of the submandibular area, the ventral part of the neck and the forelimbs, were related to a space-occupying mediastinal lymphosarcoma, which also induced respiratory distress and cyanosis. Non-selective angiocardiography demonstrated the occlusion of the cranial vena cava and abnormal venous collateral vessels feeding the heart which are accepted as the venographic hallmark of clinically overt cranial vena caval syndrome. At postmortem examination, an intracaval thrombus, 5 cm in length, was seen extending from the costocervical vein to the sulcus terminalis of the right atrium.

Animals↗
PubMed1997

Flow-induced release of endothelium-derived relaxing factor during pulsatile bypass: experimental study in the fetal lamb.

OBJECTIVE: This study was initiated to test the hypothesis that fetal hemodynamic changes observed under pulsatile flow bypass might be related to the release of endothelium-derived relaxing factor through oscillating shear stress. METHODS: Normothermic bypass was instituted in utero in 21 preterm fetal lambs for a 1-hour period through the right atrium and main pulmonary artery. Ultrasonic flowmeters were positioned around the descending aorta and the umbilical artery. The circuit consisted of an oxygenator and a pump set to either continuous flow (n = 7) or pulsatile flow (n = 7) and adjusted to maintain a fetal main arterial pressure of 50 mm Hg. In seven other animals, endothelium-derived relaxing factor was blocked by a continuous infusion of N omega-nitro-L-arginine after 30 minutes of pulsatile flow. RESULTS: During the first 30 minutes of bypass, pump flows were significantly lower in the continuous-flow group than in the pulsatile-flow or blocked-flow groups (respectively, 612 +/- 144, 907 +/- 153 and 987 +/- 228 ml/min), with similar changes in aortic and umbilical flows. Systemic vascular resistances were significantly lower in the pulsatile-flow and blocked-flow groups than in the continuous-flow group (550 +/- 106 vs 821 +/- 212 dynes/sec/cm-5). However, after blockade of endothelium-derived relaxing factor, resistances increased gradually in the blocked-flow group to reach the level of that of the continuous-flow group at the end of bypass (943 +/- 77 vs 556 +/- 143 dynes/sec/cm-5 in the pulsatile-flow group). CONCLUSIONS: Blockade of endothelium-derived relaxing factor after 30 minutes of pulsatile flow returns fetal hemodynamics to continuous flow conditions. The specific inhibitor of endothelium-derived relaxing factor used in this experiment suggests that nitric oxide may be released by fetal endothelium during pulsatile bypass.

Animals↗
PubMed1997

[Effects of active synchronized prolonged coronary perfusion in the animal].

The efficacy of a system of active diastolic synchronised coronary perfusion was studied during prolonged balloon angioplasty in 8 sheep. In the first part of the study (group 1) including 5 animals, the aim was to study the effects of high and constant flow (48 ml/min) for 90 minutes perfusion on haemolysis, the arterial wall and the perfused myocardium. The second part of the study (group 2), including 3 animals, assessed whether flow adapted to the extent of the vascular bed perfused (24 to 40 ml/min) could protect the myocardium for an interval of 60 minutes. In group 1, after 90 minutes of perfusion (48 ml/min), there was no haemolysis, or jet lesion of the arterial wall distal to the catheter tip. On the other hand, the creatinine phosphokinase levels increased at the 60th minute (188 vs 119 i.u./l for controls) and at the 90th minute (238 vs 119 i.u./l; p < 0.05). Moreover, the perfused myocardium was the site of histological lesions. These observations showed myocardial changes due to the "overflow phenomenon". In group 2, the flow rate was adapted to each animal, increasing progressively until disappearance of electrocardiographic signs of ischaemia (ST elevation) and maintained for 60 minutes. No signs of haemolysis, jet lesions or myocardial changes were observed, with absence of creatinine phosphokinase elevation and histological abnormalities. These preliminary results show that the system investigated allowed myocardial protection after arterial occlusion for an interval of 60 minutes.

Angioplasty, Balloon, Coronary↗
PubMed1996

[Hemodynamics of right circulation in ewes: normal values].

The right cardiac pressure was measured on 24 anesthetized adult ewes (Halothane) with a Swan Ganz catheter. After a review of the catheterization technique, the results (mean +/- standard deviation) in mmHg were: right auricle 17 +/- 5, right ventricle 30 +/- 6 (systolic) and 12 +/- 6 (telediastolic), pulmonary artery 29 +/- 6 (systolic), 13 +/- 6 (diastolic) and 20 +/- 6 (mean), capillary pressure 17 +/- 7. We observed slight variations in the pressure curve morphology compared to those found for man and the pressures were 5-10 mmHg higher than what is observed in man and slightly higher than those observed in dogs. These results also demonstrate a great variation between animals.

Anesthesia, General↗
PubMed1995

Awareness of blood pressure: interoception or contextual judgement?

Most patients with mild to moderate hypertension are asymptomatic but some patients report symptoms and seem to be aware of their blood pressure. The research question is whether the estimation of blood pressure is primarily derived from interoception or is inferred by contextual judgement. A psychophysiological ambulatory assessment was conducted with 51 male hypertensive patients and 30 either normotensive or hypotensive student subjects employing (1) a multichannel recording system for blood pressure, heart rate and physical activity; and (2) a pocket computer for assessing estimated BP, setting variables and self-ratings of subjective state. Within-subject correlations revealed that there was no significant relationship between estimated BP and concurrently recorded systolic BP. Estimated BP is, however, related to self-ratings of feeling physically tense and self-ratings of physical activity. Blood pressure awareness appears to be a rather inconsistent and subjective phenomenon, based on contextual judgements and inferences instead of "perception", but it is a relevant methodological issue (and possible bias) in hypertension research.

Adult↗