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Biomedical subjects

J Petit

Publications and source records attributed to J Petit.

At least 163 records · Page 9Linked to original sources
PubMed1991

Anatomic repair of Taussig-Bing hearts.

From 1978 through 1990, 27 consecutive patients underwent anatomic repair of Taussig-Bing heart (TBH) malformation. Group 1 (seven patients) underwent intraventricular repair by rerouting of the left ventricular blood stream through a tunnel patch from the ventricular septal defect (VSD) to the aorta. Group 2 (20 patients) underwent an arterial switch with VSD closure. Indications for each type of repair were based on the following criteria: when the great vessel relation is more or less anteroposterior, repair is performed at the arterial level; when side by side, the minimal tricuspid pulmonary valve distance is evaluated; if less than aortic valve diameter or if there are abnormal tricuspid chordae, repair is performed at the arterial level; if greater, pulmonary artery banding is performed in order to wait until suitable weight for intraventricular repair. The mean age at operation was 13.2 months. Coarctation of the aorta was present in 12 patients, abnormal tricuspid chords in eight, and subaortic stenosis in seven. The great vessels were in D-transposition in 12 patients, and they were side by side in 15. Seventeen patients underwent previous palliative surgery. Early (two patients, 7.4%) and late (two patients, 8%) mortality rates were related in group 1 to subaortic stenosis and in group 2 to myocardial infarction. Mean follow-up of 40 +/- 24 months was achieved in 22 survivors. They were all in New York Heart Association (NYHA) class I, without medication. Actuarial survival and freedom from reoperation rates were, respectively, at 5 years 73 +/- 14.6% and 58 +/- 13% (70% confidence limits [CL]).(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1991

[Retroperitoneal rhabdomyosarcoma revealed by acute kidney failure in children. Report of a case].

Retroperitoneal sarcomas are rare tumors representing 0.1% to 0.2% of all malignant tumors. They are usually revealed by an abdominal mass (33%), possibly associated with pain (41%). Edema of the lower limbs is reported in 10% of cases. Acute renal failure with anuria by bilateral ureteral compression, associated with invasion of the inferior vena cava has not been previously reported.

Acute Kidney Injury↗
PubMed1991

[Gallstone duodenal obstruction or Bouveret's syndrome. Apropos of two cases].

Bouveret's syndrome is a rare form of Gallstone Ileus, characterized by its duodenal site after migration through a cholecysto-duodenal fistula in almost all cases. The two cases reported emphasize the interest of endoscopy in its early diagnosis. A therapeutic schema is proposed, based upon a systematic initial endoscopic extraction trial. The surgical treatment when needed is discussed in its modalities, and adapted to a reasonable evaluation of general and local conditions.

Aged↗
PubMed1991

[Adenocarcinoma of the rete testis. Review of the literature apropos of a new case].

The authors report the case of a 66 year old man with a Boden stage I adenocarcinoma of the rete testis treated by orchiectomy and adjuvant chemotherapy. Lung metastases developed 46 months later and were responsible for death despite further chemotherapy. Adenocarcinoma of the rete testis is an exceptional tumour, as only 23 cases satisfying the criteria defined by Feek and Hunter have been reported in the literature. The prognosis is poor even in the apparently localized forms (5 year survival less than 25%) and local recurrences and lung and/or hepatic metastases are frequent. Radiotherapy and chemotherapy appear to have little value.

Aged↗
PubMed1990

Plasma and blood assay of xanthine and hypoxanthine by gas chromatography-mass spectrometry: physiological variations in humans.

Plasma and blood xanthine and hypoxanthine levels were assayed using a sensitive and specific method involving gas chromatography-mass spectrometry, associated with an optimized sample preparation procedure. Physiological variation was studied in 224 subjects with no purine metabolism disorders. An age dependency for both compounds was found, comparable with that known for uric acid. The mean plasma levels for the 224 subjects were 0.65 +/- 0.24 microM for xanthine and 1.65 +/- 0.78 microM for hypoxanthine. Corresponding mean blood levels were 0.59 +/- 0.21 microM for xanthine and 1.72 +/- 0.74 microM for hypoxanthine. Plasma and blood levels were significantly different, by ca. 10%. Rapid in vitro release of hypoxanthine from erythrocytes and continuation of intraerythrocytal metabolism lead to overestimation exceeding 10% within half an hour after sample blood collection. Hence samples must be deproteinized promptly. Blood can therefore be conveniently used for oxypurine assay instead of plasma when prompt spinning of samples is difficult to manage, as is usually encountered in clinical practice.

Adolescent↗
PubMed1990

Intermittent stimulation of fusimotor fibres during slow stretch of muscle spindles in the cat.

Responses of muscle spindles of the peroneus tertius muscle of the cat were recorded during intermittent fusimotor stimulation, applied during slow stretch, after muscle conditioning by stimulation of the nerve at the test length or at a length 2.5 mm longer. Some static and all dynamic axons evoked afferent bursts whose amplitude was relatively independent of the level of stretch response. Other static axons produced bursts that grew in size with the stretch.

Action Potentials↗
PubMed1990

Slowing of the discharge of secondary endings of cat muscle spindles during fusimotor stimulation.

Responses of secondary endings of muscle spindles of the peroneus tertius muscle of the anaesthetized cat have been recorded during repetitive stimulation of functionally single fusimotor fibres that produced slowing of the discharge. In a sample of 125 pairs of single fusimotor fibres and secondary spindle afferents 5 examples of slowing were seen. The amount of slowing became less at longer muscle lengths. Conditioning the spindle by stimulating the muscle nerve at fusimotor strength, at a length 2.5 mm longer than the test length, and then returning to the test length 3 seconds later led to a greater degree of slowing of the discharge than after conditioning stimulation at the test length. With one exception, responses to muscle stretch were reduced during stimulation of a fusimotor fibre that produced slowing. On two occasions stimulating a fusimotor fibre that produced slowing of the response of one secondary ending, led to excitation of two other endings. Two possible explanations for the generation of slowing responses have been considered. The first is that the slowing is the result of contraction of the region of intrafusal fibre directly underlying the secondary sensory ending. The second, which we favour since it accounts for the facts more adequately, is that slowing is the result of shortening of the region of nuclear chain fibres on which the sensory ending lies, produced by movement in an adjacent nuclear bag fibre.

Animals↗
PubMed1990

Lack of useful clinical predictors of response to splenectomy in patients with chronic idiopathic thrombocytopenic purpura.

We set out to identify clinical or analytical variables that might predict the response to splenectomy in patients with chronic idiopathic thrombocytopenic purpura (ITP). We retrospectively examined 138 mostly adult patients with chronic ITP, treated with splenectomy. Information was compiled from five Public Health Hospitals from a questionnaire and chart review. Sixty-one potentially prognostic variables were analysed by univariate and multivariate statistical methods. After multivariate analysis, age (relative risk = 1.02; CI 1-1.03) and a severity of the bleeding diathesis (relative risk = 1.6; CI 1.13-2.22) were independent prognostic factors for a sustained response to splenectomy. An independent analysis of the postsplenectomy counts showed that an early (days 1-3) thrombocyte count exceeding 156 x 10(9)/l cells increases the likelihood of a permanent unmaintained response. Our data indicate that the response to splenectomy in patients with chronic ITP cannot be adequately predicted on the basis of pre-splenectomy clinical or analytical variables.

Adult↗
PubMed1990

Urease-negative Nocardia asteroides causing cutaneous nocardiosis.

We report a case of cutaneous nocardiosis, caused by a urease-negative strain of Nocardia asteroides, in a patient who had undergone long-term corticosteroid therapy. The microbiological characteristics of the isolate were typical of N. asteroides except for the failure of the isolate to hydrolyze urea. During the course of routine identification, laboratory specialists should be aware of the occasional occurrence of atypical strains of N. asteroides.

Aged↗
PubMed1990

Changes in muscle stiffness produced by motor units of different types in peroneus longus muscle of cat.

1. The effects of maximal tetanic contractions of varying numbers of motor units of the same type [slow (S), fast fatigue-resistant (FR), or fast fatigable (FF)] on the mechanical responses to muscle stretch were studied in the peroneus longus muscle of anesthetized cats. 2. Two types of stiffness measurements were made: 1) an average stiffness, defined as the tension change from the beginning to end of a 0.5-mm ramp stretch; and 2) a dynamic stiffness, defined as the ratio of peak-to-peak tension to amplitude of a maintained 85-microns sinusoidal stretch at frequencies of 10-80 Hz. 3. Contractions of slow and fast units elicited different increases in average stiffness. Type S units, although developing much smaller tetanic tensions than fast ones, produced a resistance to stretch comparable with or greater than that of fast units developing much higher tensions. 4. For comparable tetanic tensions, slow units also elicited a greater dynamic stiffness than fast units. During sinusoidal stretch, changes in muscle tension led changes in muscle length during contraction of S units, but the reverse was observed for frequencies 30-50 Hz during contraction of FF units. This suggests that the latter perform oscillatory work on the driving apparatus. 5. Type S units, whose low-threshold motoneurons are the first to be recruited, appear well adapted to play a role in posture and in slow movements because of the resistance they offer to forces tending to change joint position or to oppose the progression of slow movements.

Animals↗
PubMed1990

Ensemble discharge from Golgi tendon organs of cat peroneus tertius muscle.

1. The responses of individual tendon organs of the cat peroneus tertius muscle to motor-unit contractions were recorded in anesthetized cats during experiments in which all the Ib-afferent fibers from the muscle had been prepared for recording in dorsal root filaments. This was possible because the cat peroneus tertius only contains a relatively small complement of approximately 10 tendon organs. 2. Motor units of different physiological types were tested for their effects on the whole population of tendon organs in the muscle. Effects of unfused tetanic contractions were tested under both isometric and anisometric conditions. Each motor unit activated at least one tendon organ, and each tendon organ was activated by at least one motor unit. Individual slow-type units were found to act on a single or two receptors, whereas a fast-type unit could activate up to six tendon organs. 3. In one experiment, the effects of 8 motor units on 10 tendon organs were examined. One fast-twitch, fatigue resistant (FR)-type unit acted on six tendon organs, of which four were also activated by another FR unit. The contraction of each unit, on its own, elicited a range of individual responses, from weak to strong. The discharge frequencies of individual responses displayed no clear relation with the strength of contraction, nor did they accurately represent the shape of force profiles. But when all the discharges were pooled, a fairly good correspondence appeared between variations of contractile force and variations of averaged discharge frequencies.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Effects of tetanic contraction of motor units of similar type on the initial stiffness to ramp stretch of the cat peroneus longus muscle.

1. The stiffness during the initial portion of a ramp stretch was measured in cat peroneus longus muscle at rest and during maximal tetanic contractions produced by increasing numbers of motor units of the same type [slow (S), fast fatigue resistant (FR), or fast fatigable (FF)]. 2. This initial ramp stiffness was defined as the ratio between tension and length change over the limited range of constant velocity extension during which tension rose linearly with length change. This stiffness was reduced by tetanic contraction of a number of motor units while other units remained inactive. The reduction had different characteristics in contractions produced by S, FR, or FF units. 3. Two brief ramp (triangular) stretches were applied at short intervals to evaluate the contribution of stable cross bridges to the changes in ramp stiffness. When the amplitude of the first stretch exceeded the presumed elastic limits of the stable cross bridges, the second ramp stretch showed a reduction of 20-60% in initial stiffness. This was seen both in passive muscles and in muscles in which several motor units were contracting. 4. When increasing numbers of motor units of the same type were activated, the initial ramp stiffness to the second of a pair of triangular stretches delivered during contraction increased almost linearly with the developed tension. The slope of this increase was 2.5 times steeper for S units than for FR units. This reflects the fact that contraction produced by S units causes a proportionally greater resistance to stretch than that of fast units.

Animals↗
PubMed1990

Severe self-poisoning with oxetorone: report of one case.

The authors report a case of severe self-poisoning with oxetorone. Plasma concentration of the drug assessed by HPLC was a thousand times higher than therapeutic levels. Coma, convulsions, and cardiac conduction defects were observed, similar to those noted with tricyclic and tetracyclic antidepressant poisoning. Similar cardiac disorders consisting of conduction defects had not been previously described during oxetorone intoxication.

Adult↗