Acute exposure of Siberian sturgeon (Acipenser baeri, Brandt) yearlings to nitrite: median-lethal concentration (LC(50)) determination, haematological changes and nitrite accumulation in selected tissues

Exposure of Siberian sturgeon (Acipenser baeri) yearlings (172.0+/-18 g; mean+/-S.D.) to several NO(2)(-)-N concentrations (0, 25, 130, 180 and 275 mg/l) was studied for 72 h in static tests. At 72 h, the median-lethal concentration of NO(2)(-)-N was 130 mg/l in water with high chloride content (130.5 mg/l). Nitrite exposure produced high levels of methaemoglobin (MetHb) but did not seem to cause mortality, as surviving fish showed higher levels (82.7+/-5.6%) than torpid specimens (60.8+/-4.5%). Levels of MetHb were unrelated to environmental and plasmatic nitrite concentrations, as both torpid and surviving fish exposed to the highest nitrite levels (275 mg/l of NO(2)(-)-N) presented similar concentrations of MetHb to those exposed to 25 mg/l of NO(2)(-)-N, thus indicating the ability of Siberian sturgeon yearlings to regulate plasmatic nitrite levels and maintain them lower than the environmental concentration of the toxicant. Nitrite exposure caused changes in the plasmatic electrolyte balance, which is characterised by extracellular hyperkalemia, high plasmatic chloride levels and low plasmatic sodium concentration. Differences between the nitrite concentration in the liver of torpid (46.3+/-9.0 mg/l) and surviving specimens (19.1+/-13.1 mg/l) exposed to several concentrations of NO(2)(-)-N suggest a significant contribution of the liver in nitrite detoxification pathways, and would thus explain a possible nitrite tolerance of Siberian sturgeon yearlings.

Are postoperative studies justified after extravescial ureteral reimplantation?

PURPOSE

We evaluated the usefulness of postoperative imaging studies after extravesical ureteroneocystostomy and identified patient subsets in which these studies are necessary.

MATERIALS AND METHODS

Records of 438 patients who had undergone extravesical ureteroneocystostomy from 1991 to 1997 were reviewed retrospectively. Study inclusion criterion was primary reflux with at least 1 year of postoperative followup. Grades I to III reflux were defined as low, and grades IV and V were defined as high. All patients were on prophylactic antibiotics. Evaluation included ultrasound and a voiding cystourethrogram 3 months postoperatively, and if reflux persisted the studies were repeated at 12 months.

RESULTS

A total of 438 patients (723 renal units) underwent extravesical ureteral reimplantation. At 3 months the procedure was successful in 93.2% of ureters (91.3% patients), and at 12 months the success rate increased to 97.9% of ureters (95.4% patients). There were 49 renal units in 38 cases that were refluxing at 3 months, 11 of which were contralateral. At 12 months reflux resolved spontaneously in 20 of 38 ipsilateral and 8 of 11 contralateral ureters. Of the remaining 18 ipsilateral units reflux was high grade preoperatively in 12 and persisted postoperatively in 4. There was a statistically significant difference in the success rate at 1 year between high (94%) versus low (99%) grade reflux (p = 0.007). Age and preoperative bladder function did not significantly affect the success rates but males had a lower success rate. Hydronephrosis was noted in 7.2% of ureters at 6 weeks and in only 0.005% at 12 months.

CONCLUSIONS

Extravesical reimplantation is successful in treating vesicoureteral reflux. Postoperative voiding cystourethrogram should be reserved for high grade reflux. Limiting these studies will help reduce patient discomfort and the cost of treatment.

Molecular cytogenetic analysis of the karyotype of the European Atlantic sturgeon, Acipenser sturio

A karyotype analysis was carried out on the European Atlantic sturgeon, Acipenser sturio (2n=121 +/- 3). The telomeric sequence repeat (TTAGGG)n detected by fluorescent in situ hybridization (FISH) was mostly localized at the telomeres of all chromosomes. Ribosomal DNA (rDNA) genes were detected by silver staining techniques and by FISH with digoxigenin-labelled probe for 28S rDNA. Silver staining detected active NORs in the telomeric regions of six chromosomes, and by FISH one or two additional minor sites were detected. The 5S rDNA was found in the interstitial region of a small metacentric pair. The 5S rRNA gene was completely sequenced for the first time in a sturgeon species. The A. sturio karyotype organization is discussed in relation to phylogenesis of the species within the Acipenseridae and to polyploidization events characterizing sturgeon evolution.

Urinary retention after bilateral extravesical ureteral reimplantation: does dissection distal to the ureteral orifice have a role?

PURPOSE

We evaluated the outcome and incidence of urinary retention after bilateral detrusorrhaphy using 2 modifications of the original Lich-Gregoir procedure.

MATERIALS AND METHODS

We evaluated the charts of 220 patients who underwent correction of bilateral vesicoureteral reflux using the extravesical approach from January 1991 to December 1997. Inverted Y detrusorrhaphy was performed in 154 patients and the advancing suture modification was done in 66.

RESULTS

The success rate using the advancing suture technique was 92.4 and 95.4% at 3 and 12 months, respectively. The Y detrusorrhaphy technique was successful in 91.6 and 97.4% of cases at 3 and 12 months, respectively. The difference in the techniques was not statistically significant. Urinary retention developed in 8.4% of the patients who underwent Y detrusorrhaphy compared to 15.2% of those who underwent the advancing suture technique (not statistically significant). However, patients with grades IV and V reflux, children younger than 3 years and boys had significantly (p <0.05) higher postoperative retention rates of 24.6, 35.6 and 20.3%, respectively, when all 220 patients were considered.

CONCLUSIONS

Each modification of the original Lich-Gregoir technique is highly effective for treating bilateral vesicoureteral reflux and each is associated with a low rate of temporary urinary retention. Although there seems to be a lower incidence of retention with the Y detrusorrhaphy technique, this was not statistically significant. Because of the higher incidence of urinary retention in young children, boys and/or patients with high grade reflux, we recommend that physicians consider a longer period of catheterization regardless of the technique chosen.

Urinary retention after bilateral extravesical ureteral reimplantation: does dissection distal to the ureteral orifice have a role?

PURPOSE

We evaluated the outcome and incidence of urinary retention after bilateral detrusorrhaphy using 2 modifications of the original Lich-Gregoir procedure.

MATERIALS AND METHODS

We evaluated the charts of 220 patients who underwent correction of bilateral vesicoureteral reflux using the extravesical approach from January 1991 to December 1997. Inverted Y detrusorrhaphy was performed in 154 patients and the advancing suture modification was done in 66.

RESULTS

The success rate using the advancing suture technique was 92.4 and 95.4% at 3 and 12 months, respectively. The Y detrusorrhaphy technique was successful in 91.6 and 97.4% of cases at 3 and 12 months, respectively. The difference in the techniques was not statistically significant. Urinary retention developed in 8.4% of the patients who underwent Y detrusorrhaphy compared to 15.2% of those who underwent the advancing suture technique (not statistically significant). However, patients with grades IV and V reflux, children younger than 3 years and boys had significantly (p <0.05) higher postoperative retention rates of 24.6, 35.6 and 20.3%, respectively, when all 220 patients were considered.

CONCLUSIONS

Each modification of the original Lich-Gregoir technique is highly effective for treating bilateral vesicoureteral reflux and each is associated with a low rate of temporary urinary retention. Although there seems to be a lower incidence of retention with the Y detrusorrhaphy technique, this was not statistically significant. Because of the higher incidence of urinary retention in young children, boys and/or patients with high grade reflux, we recommend that physicians consider a longer period of catheterization regardless of the technique chosen.

Modified Lich-Gregoir ureteral reimplantation: experience of a Canadian center

PURPOSE

Various techniques of ureteral reimplantation have been described for correction of vesicoureteral reflux. We report our experience regarding the safety and efficacy of a modified Lich-Gregoir extravesical approach.

MATERIAL AND METHODS

From January 1991 to January 1996 we evaluated prospectively 256 patients who underwent a modified Lich-Gregoir procedure for correction of vesicoureteral reflux. A total of 385 vesicoureteral units were reimplanted, including 41 duplex systems. The modification to the Lich-Gregoir technique we used consists of ending the paraureteral myotomy with an inverted Y, which permits easier detrusor muscle reapproximation.

RESULTS

This procedure was successful initially in 214 of 237 patients, as confirmed by a normal voiding cystourethrogram 4 to 6 months postoperatively. Of the 237 cases persistent vesicoureteral reflux developed in 13 patients, which resolved spontaneously in 9 after 1 year, contralateral reflux developed in 8, which was treated conservatively, and ureteral obstruction developed in 2. Thus, the 1-year overall success rate was 96%. Urinary retention developed in 12 children with bilateral reimplantation (8.3%) with successful recovery in all after conservative management with urethral catheter drainage of 1 week or less. The duration of hospitalization after surgery ranged from 1 to 3 days.

CONCLUSIONS

The modified Lich-Gregoir technique of extravesical ureteral reimplantation is successful, simple to perform, reproducible and associated with low morbidity. It also requires minimal hospital stay. These results should encourage the use of this technique when indicated to correct vesicoureteral reflux in children.

Occurrence and in vitro biosynthesis of 11-ketotestosterone in Siberian sturgeon, Acipenser baeri Brandt maturing females

High levels of 11-ketotestosterone (11KT) were found (49 to 160 ng ml(-1)) in plasma of Siberian sturgeon females during the end of their reproductive cycle. These levels were measured either by specific radioimmunoassay, or both by specific radioimmunoassay and by UV absorption after HPLC (isocratic conditions, 33% methanol, 26% acetonitrile, 41% water). In order to find the origin of 11KT synthesis, ovaries were incubated (30 min and 2h at 20°C) with tritiated 17-hydroxyprogesterone (17OHP) or with tritiated androstenedione (A4). Testosterone (conversion rate from tritiated 17OHP: 4%) and 11-ketotestosterone (conversion rate from tritiated A4: 1.6%) were identified as metabolites of respectively 17OHP and A4 (TLC, HPLC and crystallization). 11β-hydroxyandrostenedione (11βOHA4) and 11β-hydroxytestosterone (11βOHT) were suggested to be intermediate metabolites. Besides interrenal and blood cells were incubated respectively with tritiated cortisol and tritiated A4. 11βOHA4 was identified in interrenal incubation (yield from tritiated cortisol: 1.2%). 11KT in interrenal (yield from tritiated cortisol: 0.14%), and 11βOHA4 and 11KT in blood cells (yield from tritiated A4: 1.6%), were suspected to be synthesized (TLC, HPLC, acetylation). No significant metabolization of tritiated cortisol could be found in liver. The possible contribution of each of these tissues to high 11KT levels found in plasma is discussed.

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.

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.

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.

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.

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.

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.

Accuracy of bladder volume determinations in children using a suprapubic ultrasonic bi-planar technique

Accurate residual urine determination is an important measurement in children. We developed a suprapubic ultrasonic method using a bi-planar volume estimation technique to obtain this information in a noninvasive manner. Our data confirm that this method accurately detects an empty bladder in children and can provide reliable estimates of bladder volume.

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.

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.