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Biomedical subjects

P Williot

Publications and source records attributed to P Williot.

11 recordsLinked to original sources
PubMed1995

Circulatory and respiratory effects of an hypoxic stress in the Siberian sturgeon.

Changes in circulatory, ventilatory and acid-base variables were studied in Siberian sturgeon (Acipenser baeri) exposed to acute and severe hypoxia (PWO2 = 10 torr), followed by a rapid return to normoxia. This treatment caused a significant stress, revealed by the high levels of plasma catecholamines and cortisol. The moderate circulatory changes firstly observed would represent the effects of increased plasma catecholamine levels together with an increased adrenergic nervous tone on the cardiovascular system. Then, these effects were masked by a possible vagal reflex resulting in bradycardia. Deep hypoxia induced a ventilatory alkalosis combined with a moderate metabolic acidosis. The latter amplified concomitantly with a massive flush of lactate into the blood stream. The initial hyperventilation was followed by a deep ventilatory depression. During return to normoxia, hyperventilation resumed consistent with the repayment of an oxygen debt. Thus, the sturgeon, although considered as an archaic fish, developed the same adaptative responses as teleosts submitted to comparable hypoxic conditions.

Animals↗
PubMed1995

[Lich-Gregoir ureteroneocystostomy: experience of a North-American pediatric center].

Between August 1990 and December 1993, 140 children underwent Lich-Gregoir antireflux plasty. Twenty-eight boys and 112 girls were included with an age range of 4 months to 15 years (average 5.8 years). Twenty-seven of 220 ureters reimplanted were duplicated. At 6 months follow-up, 10 of 140 children had persistent reflux and 5 had controlateral reflux. Two patients had obstruction and 1 needed reintervention. At 1 year follow-up, only 3 children had persistent reflux and none controlateral. The Lich-Gregoir antireflux procedure is a simple surgery with minimal morbidity and excellent success rate.

Adolescent↗
PubMed1993

Comparative distribution of mammalian GnRH (gonadotrophin-releasing hormone) and chicken GnRH-II in the brain of the immature Siberian sturgeon (Acipenser baeri).

The brain of the sturgeon has recently been shown to contain at least two forms of GnRH (gonadotropin-releasing hormone), mammalian GnRH (mGnRH) and chicken GnRH-II (cGnRH-II). In this study, we compared the distribution of immunoreactive (ir) mGnRH and cGnRH-II in the brain of immature Siberian sturgeons (Acipenser baeri). The overall distribution of mGnRH was very similar to the distribution of sGnRH in teleosts such as salmonids or cyprinids. mGnRH-ir perikarya were observed in the olfactory nerves and bulbs the telencephalon, the preoptic region, and the mediobasal hypothalamus. All these cell bodies are located along a continuum of ir-fibers that could be traced from the olfactory nerve to the hypothalamopituitary interface. No ir-fibers were observed in the anterior lobe of the pituitary, but a few were seen to enter the neurointermediate lobe. mGnRH-ir fibers were detected in many parts of the brain, particularly in the forebrain. mGnRH-ir cerebrospinal fluid-contacting cells were observed in the telencephalon, the preoptic region, and the mediobasal hypothalamus. In contrast, cGnRH-II was present mainly in the posterior brain, although a few ir axons were seen in the above-mentioned territories. In particular, cGnRH-II-ir cells bodies, negative for mGnRH, were consistently observed in the nucleus of the medial longitudinal fasciculus of the midbrain tegmentum. The cGnRH-II innervation in the optic tectum, cerebellum, vagal lobe, and medulla oblongata was more abundant than the mGnRH innervation in the same areas. This study provides evidence that the organization of the GnRH systems in a primitive bony fish is highly similar to that reported in teleosts and further documents the differential distribution of two forms of GnRH in the brain of vertebrates.

Amino Acid Sequence↗
PubMed1993

Respiratory responses to progressive ambient hypoxia in the sturgeon, Acipenser baeri.

Changes in respiratory and acid-base variables were studied in siberian sturgeon, Acipenser baeri, during progressive deep hypoxia followed by recovery under normoxic conditions. During hypoxia, both ventilatory frequency and amplitude increased and this sturgeon was able to maintain standard oxygen consumption down to a low critical level of ambient PO2 (PWO2 < 40 mmHg). During the posthypoxic period, an O2 debt was repaid by an elevated oxygen consumption (nearly double control value at 1 h), indicating that a shift to anaerobic metabolism had occurred during exposure to severe hypoxia. Gradually increasing ambient hypoxia initially induced a respiratory alkalosis. Below the critical PWO2 level and during normoxic recovery, a sudden flush of lactate into the blood was associated with a typical metabolic acidosis which was almost totally compensated 3.5 h after return to normoxia. Thus, as for most other fish, respiratory responses of the sturgeon to progressive hypoxia reveal a typical O2 regulatory behavior.

Acid-Base Equilibrium↗
PubMed1993

Maturation of the external urinary sphincter: a comparative histotopographic study in humans.

The developmental anatomy of the striated urinary sphincter remains controversial and is scantly documented in children. We compared its structure and configuration in the fetus, infant and adult to determine anatomical differences among these groups. We removed 25 postmortem specimens from fetuses, infants and children, which were fixed and stained for histological study. Ages ranged from 14 weeks of gestation to 12 years postpartum. Transverse and mid sagittal sections were obtained from the bladder neck to the membranous urethra in male and the whole urethra in female subjects. At the level of the membranous urethra in male and mid urethra in female subjects the striated muscle fibers completely encircle the urethra and join behind it to form a tail-like structure that runs posteriorly towards the perineal body. This structure is mid sagittal in male and mediolateral in female subjects. At 3 to 4 months of life, at the level of the bulbourethral glands the tail disappears; the striated sphincter becomes horseshoe-shaped and its 2 branches bifurcate posteriorly to envelop these glands. The urethral striated sphincter consists of scantly dispersed muscle fibers in the fetus. In young infants it becomes well defined in both sexes with the presence of a tail-like structure that characterizes this age group. In older subjects this tail disappears and the sphincter assumes a horseshoe or omega-shaped configuration as splitting of the sphincter progresses caudo-cranially with development. We attempt to determine whether the ring configuration of the voluntary sphincter contributes to high voiding pressures that are reported to occur in some newborns and infants.

Child↗
PubMed1990

Transitional hydronephrosis of the newborn and infant.

Between 1986 and 1988, 187 hydronephrotic renal units were discovered antenatally in 134 subjects and confirmed in the neonatal period. Of these cases 119 (64%) were due to anomalies of the ureteropelvic junction. The remainder (36%) were due to various congenital uropathic conditions. Investigation consisted of renal ultrasonography, voiding cystourethrography and diuretic renography with 99mtechnetium-diethylenetriaminepentaacetic acid augmented with furosemide. Of the 119 renal units 36 (30%) underwent pyeloplasty, while 42 (35.7%) were considered normal without obstruction or dilatation. In 41 units (34.3%) diuretic renography showed partial obstruction or dilatation without obstruction that washed out readily with furosemide. Serial renal ultrasonography and renography were performed in these patients. A 12-month followup showed improvement or stabilization in 80% of the renal units and deterioration to significant obstruction in 20%. In attempting to identify the renal units that were most at risk for deterioration, it was realized that the initial ultrasound had a predictive role. None of the mildly hydronephrotic units deteriorated, whereas 14% of the moderately hydronephrotic and 32% of the markedly hydronephrotic units showed further deterioration. However, whether diuretic renography initially demonstrated partial obstruction or dilatation without obstruction, the ultimate outcome could not be predicted. Based on this experience an algorithm is proposed for the evaluation and management of antenatally detected hydronephrosis with currently available imaging techniques.

Female↗
PubMed1990

Influence of early function on long-term pediatric cadaveric renal allograft survival.

The significance of early renal graft function on long-term transplant survival is controversial. From our pediatric renal transplant population we studied 151 children who had an initial cadaveric renal transplant, were dependent on dialysis before transplantation and were 5 to 19 years old at transplantation. We used dependence upon dialysis as the parameter for early graft function. There was a statistically significant difference in long-term graft survival between patients who were independent of and dependent on dialysis at 1 week and 1 month postoperatively. Our results show that early renal graft function is important for long-term graft survival. All efforts should be directed to obtaining early renal graft function by proper organ procurement, storage, operative technique and aggressive postoperative management.

Actuarial Analysis↗
PubMed1987

Urodynamics.

Urologic problems constitute a very significant percentage of all clinical problems in pediatrics. Incorporation of urodynamic evaluation and followup is important in achieving optimal results in a significant number of these entities. In terms of cost effectiveness, it is particularly efficient in this age of extremely high-priced technology.

Adolescent↗
PubMed1986

Transitional neonatal hydronephrosis: fact or fantasy?

Hydronephrosis secondary to an anomalous ureteropelvic junction was detected antenatally in more than 60 neonatal renal units Those 21 units that exhibited partial obstruction or dilatation without obstruction were selected for this study. They were assessed and followed by serial diuretic isotope renography (99mtechnetium-diethylenetriaminepentaacetic acid augmented with furosemide) and ultrasonography. Excretory urography was used selectively. Of the 17 renal units that could be assessed 88 per cent demonstrated labile ureteropelvic junctions. Indeed, in 3 to 6 months, when the definitive status seemed to be attained, 41 per cent (7 units) had deteriorated, 12 per cent (2 units) remained stable and 47 per cent (8 units) underwent spontaneous improvement. We recommend a 3 to 6-month observation period for patients with hydronephrosis secondary to ureteropelvic junction anomalies when definite obstruction cannot be confirmed by isotope renography.

Dilatation, Pathologic↗