Biomedical subjects

J Petit

Publications and source records attributed to J Petit.

At least 73 records · Page 4Linked to original sources

PubMed1999

[Right postero-lateral thoracotomy for open heart surgery in infants and children. Indications and results].

In order to avoid the aesthetic prejudice of median sternotomy in young children undergoing open heart surgery for isolated congenital heart disease, a right posterolateral thoracotomy was performed in 146 children aged 5 months to 14 years. The large majority (140/146, 96%) were atrial septal defects: 130 ostium secundum, 5 sinus venosus, 1 low septal defect and 4 ostium primum (partial endocardial cushion defect). Six children had isolated perimembranous ventricular septal defects. One patient died of a probable lesional pulmonary oedema. Minor complications were observed in 15 cases and one had to be reoperated for a residual shunt. With an average follow-up of 2.6 years, all survivors are asymptomatic. The scar is normal, without cheloid or thoracic deformation, invisible to the patient when he looks in a mirror. The use of this approach requires a very accurate anatomical diagnosis, especially with regards to systemic and pulmonary drainage. The presence of a left superior vena cava draining into the coronary sinus is a contra-indication. The right posterolateral thoracotomy is now the approach of choice in its standard indication, the repair of ostium secundum atrial septal defects with large shunts, in young girls under 10 years of age.

Adolescent↗

PubMed1999

Non-convulsive status in the ring chromosome 20 syndrome: a video illustration of 3 cases.

We report the clinical history and the video-EEG recordings of three young adults with r(20), who exhibited repeated episodes of non-convulsive status epilepticus, often triggered by emotional events. This recognizable clinical entity associates a slight mental deficiency, behavioural disorder and epilepsy, often resistant to treatment and with a particular clinical presentation. We demonstrate with video EEG recording, atypical absence status triggered by emotional behaviour with ictal EEG characterized by bifrontal slow waves, often rhythmic, or sharp waves. Our report highlights the characteristic features of non-convulsive status in this electro-clinical syndrome.

Adult↗

PubMed1998

Simple and sensitive method for determination of metronidazole in human serum by high-performance liquid chromatography.

A simple and sensitive HPLC method for determination of metronidazole in human plasma has been developed. A step of freezing the protein precipitate allowed an efficient separation of aqueous and organic phases minimizing the noise level and improved therefore the limit of quantitation (10 ng ml(-1) using 1 ml of plasma sample). The separation of compounds was performed on a RP 18 column with acetonitrile-aqueous 0.01 M phosphate solution (15:85, v/v) as mobile phase. Detection was performed by UV absorbance at 318 nm. Metronidazole was well resolved from the plasma constituents and internal standard. An excellent linearity was observed between peak-height ratios plasma concentrations over a concentration range of 0.01 to 10 microg ml(-1). Within-day and between-day precision (expressed by relative standard deviation) and accuracy (mean error in per cent) did not exceed 4% between 1 and 10 microg ml(-1) and 8.3 and 7.2% respectively for the limit of quantitation. The method is suitable for bioavailability and pharmacokinetic studies in humans.

Antitrichomonal Agents↗

PubMed1998

An anatomical substrate for the spatiotemporal transformation.

The purpose of the present experiments was to test the hypothesis that the metrics of saccades caused by the activation of distinct collicular sites depend on the strength of their projections onto the burst generators. This study of morphofunctional correlations was limited to the horizontal components of saccades. We evoked saccades by stimulation of the deeper layers of the superior colliculus (SC) in alert, head-fixed cats. We used standard stimulus trains of 350 msec duration, 200 Hz pulse rate, and intensity set at two times saccade threshold in all experiments. Evoked saccades were analyzed quantitatively to determine the amplitude of the horizontal component of their "characteristic vectors". This parameter is independent of eye position and was used as the physiological, saccade-related metric of the stimulation sites. Anatomical connections arising from these sites were visualized after anterograde transport of biocytin injected through a micropipette adjoining the stimulation electrode. The stimulation and injection sites were, therefore, practically identical. We counted boutons deployed in regions of the paramedian pontine reticular formation reported to contain long-lead and medium-lead burst neurons of the horizontal burst generator. Regression analysis of the normalized bouton counts revealed a significant positive correlation with the size of the horizontal component of the characteristic vectors. This data supports a frequent modelling assumption that the spatiotemporal transformation in the saccadic system relies on the graded strength of anatomical projections of distinct SC sites onto the burst generators.

Animals↗

PubMed1998

Biventricular repair for double-outlet right ventricle. Results and long-term follow-up.

BACKGROUND: The purpose of the present study was to define the optimal management and to identify the risk factors for death and repeat operation in patients with double-outlet right ventricle. METHODS AND RESULTS: From 1985 through 1996, 154 consecutive patients underwent biventricular repair for double-outlet right ventricle. The presence of bilateral infundibular structures was the major inclusion criteria (142 patients). According to the relationship of the ventricular septal defect (VSD) to the great arteries, there were 86 patients with a subaortic VSD (56%), 45 patients with a subpulmonary VSD (29%), 18 patients with a noncommitted VSD (12%), and 5 patients with a doubly committed VSD (3%). Sixty-five patients (42%) had undergone previous palliative procedures. At repair, the median age was 10 months, and the median weight was 6.5 kg. Two main types of repair were used: intraventricular baffle repair (n = 115) and arterial switch operation with VSD-to-pulmonary artery baffle (n = 39). There were 14 hospital deaths (9%; 70% confidence limit [CL], 7% to 12%). The only significant risk factor for early death was the presence of congenital mitral valve anomalies (P = 0.02). Twenty-eight patients (18%) required 39 repeat operations. The repeat operation rate was higher in patients with associated VSD enlargement at baffle construction (n = 29; 19%) (P = 0.01). There were 6 late deaths (4%; 70% CL, 2% to 7%). Patients presenting with pulmonary stenosis constituted a low-risk group for global death (P = 0.008). The median follow-up was 52 months. Ten-year actuarial survival and survival with freedom from repeat operation rates were 86% and 62% (70% CL, 83% to 89% and 54% to 70%), respectively. CONCLUSIONS: Long-term survival with good quality of life can be achieved after either 1- or 2-stage repair of this complex anomaly.

Adolescent↗

PubMed1998

[Long-term stability of bone mineral density in patients with renal transplant treated with cyclosporine and low doses of corticoids. Protective role of cyclosporine?].

OBJECTIVES: Cyclosporine has been thought to have a deleterious effect on bone in transplant recipients because of high turnover osteopenia observed in humans after transplantation. However, varying confounding factors such as renal and parathyroid function, cumulative steroid doses and previous exposure to aluminium, also play a role and hinder interpretation of the cyclosporine effect on bone mineral density (BMD). PATIENTS AND METHODS: A 2-year prospective study was conducted to measure BMD starting 3 months after transplantation and bone remodeling markers from the first post-transplantation day in 52 kidney recipients with no prior exposure to aluminum. None of the patients experienced rejection and at 3 months all had good stable renal function (serum creatinine 137 mumol/l) and mildly elevated parathyroid hormone levels (1.5 times the upper limit of normal). All patients were given the same low dose steroid treatment (10 mg/day) and at 6 months cyclosporine was decreased from 7 to 4.8 mg/kg/day. RESULTS: BMD measured by double energy X-ray absorptiometry, (DEXA) and expressed in Z score, was moderately decreased at 3 months for the vertebrae (-1.40), the femoral neck (-1.34) and the ultradistal radius (-0.95) which have predominantly cancellous bone and was significantly less decreased (p < 0.05) for the lower third of the radius (-0.6) which is mainly cortical bone. BMD measurements were comparable at 6, 12 and 24 months. When measured by axial computerized tomography (ACT) BMD of the vertebrae showed a non-significant increase of Z score from -1.37 to -1.19 at 2 years. Bone remodeling markers was observed up to month 6 (from month 3 for osteocalcine and from month 1 for total and bone alkaline phosphatase and urinary pyridinoline), then returned to baseline levels at 2 years in parallel with decreased cyclosporine dosage. The increase of vertebral BMD measured by ACT at 1 year was correlated both to cyclosporine dose at 1 year and to bone alkaline phosphatase at 6 months. CONCLUSION: Our data confirm the presence of moderate osteopenia 3 months after transplantation, predominantly in trabecular bone, logically linked to the initial high doses of corticosteroids. The long-term stability of BMD measured by DEXA and the correlation of vertebral BMD increase measured by ACT with cyclosporine dose and bone alkaline phosphate suggest that cyclosporine had a beneficial immunosuppressor effect by stimulating bone remodeling and thus counterbalancing the suppressive effect of corticosteroids.

Adrenal Cortex Hormones↗

PubMed1998

[Kidney procurement from a heart-arrest donor].

Brain death occurred in a 47-year-old head trauma patient following 5 days of intensive care. The procedure for multiple organ procurement was initiated. Irreversible cardiac arrest had occurred during the period in the surgical intensive therapy unit. External cardiac massage and mechanical ventilation were maintained until in situ cooling of the kidneys was achieved. The patient was taken to the operating room for nephrectomy. Both kidneys were transplanted with a favorable outcome. Procurement of kidneys from non-heart-beating donors could increase the number of available grafts for transplantation.

Craniocerebral Trauma↗

PubMed1998

Induction and modulation of acute-phase response by protein malnutrition in rats: comparative effect of systemic and localized inflammation on interleukin-6 and acute-phase protein synthesis.

The acute-phase protein (APP) response is regulated by cytokines such as interleukin-6 (IL-6), interleukin-1 (IL-1) and tumor necrosis factor (TNF), but may also be influenced by malnutrition. The aims of this study were as follows: 1) to determine in rats the effect of a protein-deficient diet on IL-6 mRNA expression in intestine, liver and peripheral blood mononuclear cells (PBMC), and on alpha-1 acid glycoprotein (AGP) and alpha-2 macroglobulin (A2M) serum levels and hepatic mRNA expression; 2) to compare, in protein-deficient rats, the IL-6 and APP responses after a turpentine (TO)- or a lipopolysaccharide (LPS)-induced inflammation; and 3) to determine the effect of a protein malnutrition on IL-6 mRNA expression in rat PBMC treated ex vivo with LPS. Interleukin-6 mRNA was present in intestine and PBMC but not in the liver of malnourished rats, and was absent in any tissue or cells of controls. A2M was present in the serum from malnourished rats but not after refeeding. AGP mRNA expression was not influenced by protein malnutrition. In malnourished rats, IL-6 serum level peaked later than in controls after TO and LPS treatment. In malnourished TO-treated rats, A2M mRNA increased earlier than in controls and remained detectable later than in controls. AGP mRNA expression after TO was not influenced by protein malnutrition. In PBMC of malnourished rats, LPS-induced IL-6 mRNA expression occurred earlier and lasted longer than in controls. Our results indicate that protein malnutrition by itself induces IL-6 and A2M expression, and that it modulates the APP response to inflammation.

Acute-Phase Proteins↗

PubMed1998

Comparison of static fusimotor innervation in cat peroneus tertius and longus muscles.

Static fusimotor innervation was compared in cat peroneus longus and tertius muscles because the gamma to spindle ratio is considerably higher in the longus (approximately 60 gamma axons for 17 spindles) than in the tertius (approximately 24 gamma axons for 14 spindles). Single gamma axons were identified as static (gamma(s)) by their typical effects on the response of primary ending to ramp stretch. The intrafusal muscle fibers that single gamma(s) axons activated in the spindles they supplied were identified by the features of cross-correlograms between Ia impulses and stimuli, at 100 Hz, and by those of primary ending responses during stimulation at 30 Hz. In each experiment, a large proportion of the gamma population was tested on about nine spindles. A statistical analysis was used to estimate the number of spindles supplied by single gamma(s) axons and the proportion of gamma(s) axons that supply only one spindle among those the stimulation of which had activated either bag2 or chain fibers alone in a single spindle. In peroneus longus, nearly all gamma(s) axons supply one or two spindles, whereas in peroneus tertius, the majority of gamma(s) axons supply from three to six spindles. The proportion of nonspecifically distributed gamma(s) axons, i.e., of axons that supply both bag2 fibers and chain fibers either in the same or in different spindles, is much lower (56%) in the longus than in the tertius (83%) as previously observed on a population of gammas axons that supplied from three to six spindles. Correspondingly, the proportion of specific axons is much higher in the longus (44%) than in the tertius (17%). In none of the two muscles was a strict relationship observed between the conduction velocity of gamma(s) axons and their intrafusal distribution (specific bag2, specific chain fibers, nonspecific). However, gamma(s) supplying bag2 fibers either specifically or in combination with chain fibers tended to have faster conduction velocities, which suggests that, in various motor acts, the proportion of activated bag2 and chain fibers may be related to the proportions of activated fast and slow gamma(s) axons.

Animals↗

PubMed1998

New mechanism that accounts for position sensitivity of saccades evoked in response to stimulation of superior colliculus.

New mechanism that accounts for position sensitivity of saccades evoked in response to stimulation of superior colliculus. J. Neurophysiol. 80: 3373-3379, 1998. Electrical stimulation of the feline superior colliculus (SC) is known to evoke saccades whose size depends on the site stimulated (the "characteristic vector" of evoked saccades) and the initial position of the eyes. Similar stimuli were recently shown to produce slow drifts that are presumably caused by relatively direct projections of the SC onto extraocular motoneurons. Both slow and fast evoked eye movements are similarly affected by the initial position of the eyes, despite their dissimilar metrics, kinematics, and anatomic substrates. We tested the hypothesis that the position sensitivity of evoked saccades is due to the superposition of largely position-invariant saccades and position-dependent slow drifts. We show that such a mechanism can account for the fact that the position sensitivity of evoked saccades increases together with the size of their characteristic vector. Consistent with it, the position sensitivity of saccades drops considerably when the contribution of slow drifts is minimal as, for example, when there is no overlap between evoked saccades and short-duration trains of high-frequency stimuli.

Algorithms↗

PubMed1998

[Primary renal chondrosarcoma: apropos of a case].

The authors report a case of primary renal chondrosarcoma associated with subcapsular renal haematoma. The authors reviewed the four largest series of renal sarcomas reported in the literature and propose an analysis of the various clinical characteristics, complementary investigations and treatment modalities of this exceptional form of renal sarcoma.

Aged↗

PubMed1997

Biventricular repair of conotruncal anomalies associated with aortic arch obstruction: 103 patients.

BACKGROUND: Biventricular repair of conotruncal anomalies associated with aortic arch obstruction is a complex surgical procedure that combines a cardiac repair and a aortic arch reconstruction. METHODS AND RESULTS: From January 1984 to April 1996, such a repair was performed in 103 patients. The conotruncal anomalies included: 15 transpositions of the great arteries (TGAs) with intact ventricular septum, 44 TGAs with ventricular septal defect, 32 double outlet right ventricle with subpulmonary ventricular septal defect, 10 truncus arteriosus, one double outlet left ventricle, and one tetralogy of Fallot. The arch obstruction included 88 coarctation and 15 interrupted aortic arch. One-stage repair has been the favored technique since 1990 and was performed in 58 neonates, including 38 TGAs or double outlet right ventricle and ventricular septal defect, 10 TGAs with intact ventricular septum, and all of the 10 truncus arteriosus. The cardiac repair included 89 arterial switch operations, 2 Kawashima rerouting, 10 truncus arteriosus repairs, and one double-outlet left ventricle repair and one tetralogy of Fallot repair. The aortic arch was reconstructed by direct anastomosis in 85 patients, with a Gore-Tex conduit in three patients and more recently by an ascending aortic patch augmentation in 15 patients. The hospital mortality was 12% (7 of 58) for the one-stage repair and 20% (9 of 45) for the two-stage repair. There were six late deaths. Reoperations or angioplasties were mandatory for 12 right ventricle outflow tract obstructions after arterial switch, involving 10 patients with double outlet right ventricle (P=.02), 10 recurrent arch obstruction, and six miscellaneous lesions. CONCLUSIONS: One-stage biventricular repair of conotruncal anomalies associated with aortic arch obstruction can be achieved in selected patients with an 83% survival rate at 7 years.

Aortic Arch Syndromes↗

PubMed1997

Tendon organ sensitivity to steady-state isotonic contraction of in-series motor units in feline peroneus tertius muscle.

1. Measurements have been made of the sensitivity of tendon organs to steady-state, isotonic contractions of single and groups of in-series motor units in the peroneus tertius muscle of the cat hindlimb. 2. Linear relationships were found between the Ib afferent discharge and the contractile tension generated by tetanic stimulation of single motor units. These relationships held for the fast, fatiguable (FF) units and for all but the lowest tensions generated by the slow (S) and some fast, fatigue resistant (FR) units. The sensitivity of the organs was independent of the contractile properties of the units. 3. Groups of three motor units were stimulated isotonically at low rates (around 30 Hz), but asynchronously to produce a smooth tension profile. Again, linear relationships pertained between the discharge rate and the tension, and the sensitivity was the same for different motor unit types. 4. Under isotonic conditions, therefore, the tendon organs showed linear responses to the tension with similar sensitivities, indicating that tendon organs may have the capacity to signal faithfully steady-state contractile tensions.

Afferent Pathways↗

PubMed1997

Tension distribution of single motor units in multitendoned muscles: comparison of a homologous digit muscle in cats and monkeys.

To determine whether single motor units (MUs) in multitendoned muscles distribute tension to multiple tendons or instead focus tension selectively on a single tendon, we examined the distribution of tension generated by single MUs in the cat extensor digitorum lateralis (EDLat), and in its macaque homolog, the extensor digiti quarti et quinti (ED45). General properties of MUs (maximal tetanic tension, axonal conduction velocity, and twitch rise time) were similar in these muscles to those reported for other limb muscles in cats and monkeys. Most cat EDLat MUs were found to exert tension rather selectively on one of the three tendons of the muscle. Fast fatigable MUs were slightly but significantly more selective than fast fatigue-resistant and slow MUs. In contrast, and contrary to expectation, the macaque ED45 contained a lower proportion of MUs that exerted tension selectively on one of the two tendons of the muscle, and a higher proportion of relatively nonselective MUs. These findings suggest that the cat EDLat may consist of three functional subdivisions, each acting preferentially on a different tendon, whereas the macaque ED45 is more likely to function as a single multitendoned muscle.

Animals↗

PubMed1997

Technique to repair tetralogy of Fallot with absent pulmonary valve.

The syndrome of tetralogy of Fallot with absent pulmonary valve is characterized by aneurysmal dilatation of the pulmonary arteries causing tracheobronchial obstruction of varying degree. Relief of this obstruction is the main goal of the surgical repair and can best be achieved by appropriate pulmonary arterioplasty. We describe our current technique to repair this syndrome in infants and older children including pulmonary arterioplasty, ventricular septal defect closure, and right ventricular outflow tract reconstruction without valve insertion.

Aneurysm↗

PubMed1997

Prevention of unbalanced lung perfusion and atrial arrhythmias after the lateral tunnel operation.

BACKGROUND: The lateral tunnel operation has become increasingly popular with pediatric cardiac surgeons, as it is technically reproducible, is relatively easy to perform, and can be used in a variety of patients with single-ventricle physiology. The main drawbacks of the original operation are uneven blood flow distribution to the lungs and increasing incidence of supraventricular arrhythmias over time. METHODS: In 1988, we modified this technique by avoiding narrowing of the tunnel at the superior vena cava-atrial junction, avoiding incorporation of the crista terminalis in the baffle suture line, and minimizing damage to the sinoatrial node. Between 1988 and 1995, 19 patients underwent this operation at Marie-Lannelongue Hospital in Paris. RESULTS: There was one early death and no late deaths. At a mean follow-up of 5.2 years, all survivors are in New York Heart Association class I. Early atrial flutter, related to atrial scarring secondary to multiple previous surgical procedures, developed in 1 patient, and late atrial flutter developed in 1 patient who had a previous Blalock-Hanlon atrial septectomy. All patients are currently in sinus rhythm. Atrial flutter did not occur in 17 patients who had had no previous atrial wall surgical procedure. CONCLUSIONS: We believe that the good long-term clinical results are directly attributable to our modifications, which ensure optimal hemodynamics and absence of rhythm disturbances. All patients who had not previously undergone operation on the atrial wall were free from supraventricular tachyarrhythmias at a mean follow-up of 5.2 years. This is a consequence of protecting the sinus node, crista terminalis, and Bachmann's bundle.

Atrial Flutter↗

PubMed1997

Primary central nervous system lymphoma of T-cell origin: description of two cases and review of the literature.

Primary lymphomas of the central nervous system (PLCNS) of T-cell lineage are unusual. It has been suggested that T-cell PLCNS, compared to those of B-cell origin, present some differences in relation to age of presentation, gender, location of the tumor and survival. We describe two cases with T-cell PLCNS and review 22 parenchymatous T-cell PLCNS reported in the English literature. Age, gender and survival of the whole series of 24 T-cell PLCNS did not differ from that reported in large series of PLCNS where the great majority were of B-cell origin. In contrast, a location in the posterior fossa was found in 54% of T-cell PLCNS, whereas this location ranged from 12 go 29% in series of, mostly B-cell, PLCNS. T-cell PLCNS had a higher frequency (33%) of the histologic low grade small lymphocytic lymphoma than B-cell PLCNS (5%). Analysis of six T-cell PLCNS long-term survivors showed that half of them had low grade lymphomas. We conclude that T-cell PLCNS do not differ from those of B-cell origin in age of presentation or gender, but they have a preference to develop in the posterior fossa and a higher frequency of low grade histology which would probably explain the longer survival in some patients.

Adult↗

PubMed1997

Functional consequences of bag2 and chain fiber coactivation by static gamma-axons in cat spindles.

A study of the distribution in cat peroneus tertius spindles of 42 single static gamma-axons was recently carried out with a physiological method for identifying the intrafusal muscle fibers supplied by single gamma-axons. It was found that 35 axons (83%) supplied both slow-contracting bag2 fibers and fast-contracting chain fibers. The distribution of these axons generally varied from one spindle to another among all the spindles that each of them supplied (bag2 and chain fibers together, bag2 alone, chains alone). To find some functional consequences of this coactivation, responses of primary endings to sinusoidal stretch of the muscle (amplitude 0.5-1 mm, frequency linearly increasing from 0.6 to 8-9 Hz in 12 s) were recorded at different average muscle lengths (0.5, 1.0, and 1.5 mm shorter than maximal physiological length) in nembutalized cats during repetitive stimulation at 10, 20, and 30 Hz of single gamma-axons previously shown to supply bag2 and chain fibers in the spindles bearing the primary endings. These responses were compared with responses elicited in passive spindles and during activation of either bag2 fibers or chain fibers alone. Several records of discharge frequency were averaged. During stimulation at 30 Hz of gamma-axons coactivating bag2 and chain fibers, the averaged discharge of primary endings became continuous (that is, without interruption during each shortening phase as occurs in passive spindles) over the whole range of stretch frequencies. The modulation of the discharge was roughly sinusoidal, with an amplitude that increased with the stretch frequency. Stimulation at 30 Hz of gamma-axons activating bag2 fibers alone elicited a modulation of comparable shape and amplitude but only in the range of sinusoidal stretch from 0.6 to 3-4 Hz. Stimulation at 30 Hz of gamma-axons activating chain fibers alone elicited for each cycle in the range of 0.6 to 5-6 Hz a distorted modulation of large amplitude with a minimal frequency close to that of the stimulation. The average muscle length did not significantly influence these various responses. In summary, the coactivation of bag2 and chain fibers, at presumed physiological frequencies, enables primary endings to continuously signal changes of length over a large range of stretch velocities independently of the average muscle length.

Animals↗