Distal Shunt Obstruction in Children With Myelomeningocele After Bladder Perforation

PURPOSE

We studied short-term complications and particularly the signs of shunt dysfunction after augmented bladder perforation in patients with myelomeningocele and ventriculoperitoneal shunts.

MATERIALS AND METHODS

In our series of bladder augmentations in 27 patients with myelomeningocele and a ventriculoperitoneal shunt in the last 10 years (1994 to 2004) we noted 4 who were 8 to 16 years old at our institute with bladder perforation 2 to 5 years after augmentation. Three patients received a colonic augmentation and 1 received an ileal augmentation. One patient underwent surgery for small bowel obstruction 2 years after the primary operation, when a hole in the augmented bladder was identified and oversewn. The other 3 bladder perforations occurred spontaneously or after failure to catheterize. An additional patient with spontaneous perforation underwent auto-augmentation elsewhere.

RESULTS

After primary open abdominal surgery and enterocystoplasty there was no sign of shunt dysfunction in any patient. Bladder perforation and leakage of free urine into the abdominal cavity occurred in 4 of the 5 patients. In those patients severe symptoms of shunt dysfunction, including headache and high intracranial pressure, were noted 2 to 7 days after perforation. In patient 1 there was only urine leakage into a small cavity close to the bladder and no acute signs of post-perforation shunt dysfunction. In all cases the shunt was externalized for 1 to 6 weeks without further complications.

CONCLUSIONS

In patients with myelodysplasia who have bladder perforation and free urine in the abdominal cavity the peritoneum is chemically inflamed by urine. Resorption of cerebral liquor may be disturbed, leading to shunt dysfunction and high intracranial pressure. Therefore, it is important for the urologist to recognize and evaluate postoperative signs and symptoms of increased intracerebral pressure in patients with bladder perforation. If found, early computerized tomography of the brain is recommended.

Endoscopic treatment with dextranomer-hyaluronic acid for vesicoureteral reflux: histological findings

PURPOSE

Dextranomer-hyaluronic acid co-polymer is the first endoscopic bulking agent approved for vesicoureteral reflux in the United States. We evaluated the histopathological changes associated with this treatment in children with vesicoureteral reflux.

MATERIALS AND METHODS

Children 1 to 11 years old in whom treatment with dextranomer-hyaluronic acid co-polymer for grades III or greater vesicoureteral reflux had failed were eligible for the study. Failure was defined as persistent vesicoureteral reflux on voiding cystourethrography done approximately 3 months after implantation. At ureteral reimplantation the implant and surrounding ureteral tissue were resected and fixed for histopathological analysis. Tissue sections (4 to 5 microm.) were stained for routine histology and examined under a light microscope. Patients with a similar grade of vesicoureteral reflux who had not undergone endoscopic treatment served as the control group.

RESULTS

The study population comprised 23 patients with vesicoureteral reflux, of whom 13 with a mean age of 2 years 8 months at diagnosis underwent 1 to 3 treatments with dextranomer-hyaluronic acid co-polymer. The remaining 10 patients with a mean age of 1 year 10 months at diagnosis did not receive the bulking agent before ureteral reimplantation. The implant remained in situ 13 to 39 months (mean 22). On ureteral reimplantation the implant was located at the site of injection in 12 of the 13 patients. Histologically a granulomatous inflammatory reaction indicated by giant cell infiltration was observed at the implantation site. At ureteral reimplantation 9 implants were pseudo-encapsulated. Calcification was present in 9 ureters, while the eosinophil count was greater than 5 cells per 0.125 mm2 in 7 ureters treated with dextranomer-hyaluronic acid co-polymer. Mast cell infiltration was similar in the treatment and control groups.

CONCLUSIONS

Endoscopic treatment with dextranomer-hyaluronic acid co-polymer for vesicoureteral reflux is associated with a granulomatous reaction of the giant cell type, inflammatory cell infiltration and implant pseudo-encapsulation. They are typical histological findings associated with implantation of a foreign material. Dextranomer-hyaluronic acid co-polymer remains safe and effective for vesicoureteral reflux in children.

Vasopressin and hypercalciuria in enuresis: a reappraisal

OBJECTIVE

To test the hypotheses that vasopressin deficiency or hypercalciuria are important in polyuric and non-polyuric bedwetting, as nocturnal polyuria is a pathogenetic factor in enuresis responsive to antidiuretic therapy with desmopressin.

SUBJECTS AND METHODS

Vasopressin deficiency has been implicated as a cause of nocturnal polyuria, but measurements of vasopressin in plasma have given contradictory results, because the hormone is released in pulses. Urinary levels reflect the secretion over longer periods. Hypercalciuria has also been proposed as a pathogenetic factor. Twenty-eight enuretic children who responded to desmopressin therapy with or without added anticholinergic agents (diuresis-dependent enuresis, DE), 15 children with therapy-resistant enuresis (not diuresis-dependent, NDE) and 51 continent controls were assessed. Urinary vasopressin, calcium and osmolality were measured in the morning after a 12-h thirst provocation. Urine production was recorded for 2 days.

RESULTS

Because most data were not normally distributed, the values are expressed as the median (range). There were no differences in urine osmolality; i.e. con-trols 919 (636-1232), DE 849 (462-1149), NDE 968 (664-1191) mOsml/kg); vasopressin, controls 34 (8-983), DE 26 (9-295), NDE 50 (9-116) pmol/L; or calcium excretion (expressed as the calcium/creatinine ratio), controls 0.16 (0.01-0.71), DE 0.14 (0.04-0.67), and NDE 0.23 (0.03-0.69). The DE group produced more urine, at 18.4 (9.2-52.5) mL/kg/day, than the other groups, i.e. control 12.7 (8.3-42.8) and NDE 12.1 (6.3-36.8) mL/kg/day (P = 0.008).

CONCLUSION

All enuretic children with nocturnal polyuria do not have vasopressin deficiency. The urinary calcium excretion does not differ between enuretic and dry children.

The effect of endoscopic injections of dextranomer based implants on continence and bladder capacity: a prospective study of 31 patients

PURPOSE

A prospective study was conducted to assess the efficacy of dextranomer based implants as a new bulking agent for endoscopic treatment of pediatric structural incontinence.

MATERIALS AND METHODS

A total of 33 children and adolescents 5 to 18 years old with severe incontinence due to sphincteric incompetence (exstrophy-epispadias in 13, neuropathic bladder in 16, bilateral ectopic ureters in 4) were enrolled in the study. All but 1 patient wore diapers. Preoperative evaluation consisted of medical history, pad test, urine culture, urinary tract ultrasound and videourodynamics. This evaluation was repeated 6 months and 1 year after treatment and then on a yearly basis. Of the patients 14 had 2 and 1 had 3 treatment sessions to achieve a definitive result. At each evaluation the patient was considered cured-dryness interval of 4 hours confirmed by pad test, significantly improved-minimal incontinence requiring no more than 1 pad a day with less than 10 gm. leakage during pad test; and no further treatment required, and treatment failure-no significant improvement. Videourodynamics were mainly useful to study the evolution of the bladder capacity, activity and compliance. Followup after the last injection ranged from 6 to 36 months (mean 18).

RESULTS

The mean injected volume was 3.9 ml. (range 1.6 to 12) and the procedure lasted a mean of 30 minutes (10 to 60). In the postoperative period 2 patients had temporary dysuria and 10 had a nonfebrile urinary tract infection. At 1 month 24 of the 33 patients (73%) were dry or improved. Two patients were subsequently excluded from study for noncompliance with followup. At 6 months 17 of 31 patients (55%), at 1 year 13 of 28 (46%), at 2 years 10 of 23 (43%) and at 3 years 10 of 20 (50%) were dry or improved. Similar success occurred in cases of neuropathic bladder (57%) and exstrophy-epispadias complex (46%). Success rate of re-treated patients was 35%. Of 13 patients with a normal initial bladder capacity 3 had a bladder decompensation requiring augmentation after 6 months. Also an increase of at least 50% in capacity was observed in 12 of 18 patients with an initial small bladder. No side effect related to the substance was observed.

CONCLUSIONS

Endoscopic treatment of pediatric structural urinary incontinence with dextranomer implant, a nontoxic, nonimmunogenic, nonmigrant synthétic substance, was effective after 3 years in half of our patients. It may also be beneficial for patients with small bladder functional capacity. As the success rate decreased during the first year of followup, the result observed at 1 year seems to remain stable subsequently.

Suicide mortality among electricians in the Swedish construction industry

OBJECTIVES

To investigate the risk of suicide in Swedish electricians employed in the construction industry. A few studies have indicated an increased risk of suicide for electricians in the construction industry and electricians exposed to electromagnetic fields.

METHODS

This is a cohort study. Electricians were identified through a computerised register of construction workers who had participated in health examinations in 1971-92. In this register, 33,719 male electricians were identified together with a reference group consisting of 72,653 male glass or woodworkers. Through a linkage with the Swedish Death Register, the cause of death was identified to the end of 1997. Mortality as a result of suicide was also compared with the general population with adjustments for sex, age, and period.

RESULTS

The risk of mortality from suicide was decreased for electricians (standardised mortality ratio (SMR) 0.58, 95% confidence interval (95% CI) 0.47 to 0.71) and for the reference group of construction workers (SMR 0.81, 95% CI 0.72 to 0.91) compared with the general population.

CONCLUSION

Contrary to some other studies, risk of suicide was not increased among electricians in the construction industry.

Pressure flow measurement of hydronephrosis in children: a new approach to definition and quantification of obstruction

PURPOSE

Hydronephrosis due to obstruction of the ureteropelvic junction is not uncommon in children. The critical level of outflow resistance characterizing obstruction remains to be established. It was previously found in our laboratory that the outflow resistance could be calculated in an animal model by servoregulating the infused flow to preset pressure levels. We determine whether this procedure is also feasible in patients with hydronephrosis.

MATERIALS AND METHODS

A total of 46 patients with 48 hydronephrotic kidneys were examined. There were 32 boys and 14 girls with a diagnosis of hydronephrosis and suspected ureteropelvic junction obstruction who underwent a pressure flow study under general anesthesia for evaluation before possible surgery. The kidney was punctured percutaneously under ultrasonic guidance, and the study was performed under fluoroscopy. Flow levels were measured when steady state flow was achieved at pressures 5, 10, 15, 20, 25 and 30 mm. Hg greater than the intra-abdominal pressure. A conventional Whitaker test at an infusion rate of 10 ml. per minute was performed for comparison. The patient then underwent pyeloplasty if the kidney was considered obstructed.

RESULTS

There were 2 patients excluded from evaluation because of significant leakage of contrast medium. Stable and repeatable recordings were obtained in all pressure flow studies but only in 7 of 46 Whitaker tests. A total of 41 kidneys were considered obstructed at pressure flow studies and operated on. The resistance was pressure dependent. Thus, mean resistance in the previous range 5 to 15 mm. Hg was considered a good overall measure of outflow resistance. Mean resistance less than 0.75 was normal and greater than 1.25 obstruction. There were 7 patients who had crossing vessels and a high mean resistance (3 or greater).

CONCLUSIONS

The Whitaker test proved to be of no value for calculating the outflow resistance in ureteropelvic junction obstruction. The pressure flow study is superior to the Whitaker test for determining the outflow resistance and also allowing categorization of ureteropelvic junction obstruction.

Long-term followup of children treated with dextranomer/hyaluronic acid copolymer for vesicoureteral reflux

PURPOSE

Dextranomer/hyaluronic acid copolymer is a novel substance that has favorable properties for endoscopic treatment of vesicoureteral reflux. We assess the long-term efficacy and safety of this treatment of children.

MATERIALS AND METHODS

Children 1 to 15 years old with grade III or greater vesicoureteral reflux were eligible for enrollment in our study. All patients received endoscopic treatment with dextranomer/hyaluronic acid copolymer and were scheduled to have a voiding cystourethrogram 3 and 12 months after implantation. Children with reflux grade III or greater after treatment received up to 2 more implantations, and those with persistent reflux were referred for open surgery. In some cases long-term clinical followup was accompanied by a late voiding cystourethrogram.

RESULTS

A total of 228 patients received endoscopic treatment. The efficacy population was comprised of 221 children, including 67 who received 2 and 8 who received 3 implantations. Endoscopic treatment was performed without complications in all cases. Patients were followed clinically for 2 to 7.5 years (mean 5). On the last voiding cystourethrogram 68% of patients had a positive response (grade I or less) and 81% had no dilating reflux. The corresponding results for treated ureters were 75% and 85%, respectively. Only 27 (12%) patients were referred for open surgery. A late voiding cystourethrogram was performed in 49 patients 2 to 5 years after treatment. Of the ureters free of reflux (grade 0) 3 to 12 months after treatment 96% remained free of dilating reflux. Adverse events occurred in association with implantation in only 2% of patients, although urinary tract infection subsequently developed in 8%.

CONCLUSIONS

Endoscopic treatment with dextranomer/hyaluronic acid copolymer was effective and well tolerated in children with vesicoureteral reflux. Long-term followup indicated that there was no deterioration in patients responding positively to treatment.

Bladder capacity and renal concentrating ability in enuresis: pathogenic implications

PURPOSE

We compared bladder volume and renal concentrating capacity in dry children and 2 distinct groups of children with enuresis to hypothesize about the pathogenesis of various types of enuresis.

MATERIALS AND METHODS

A total of 55 dry children and 100 with enuresis underwent an overnight thirst provocation test to assess renal concentrating capacity and completed a 2-day voiding chart to assess functional bladder capacity. The enuretic children were subdivided into 27 desmopressin responders and 73 desmopressin nonresponders before study inclusion.

RESULTS

The desmopressin responder group had lower average renal concentrating capacity +/-1 standard deviation than dry children and desmopressin responders (856 +/- 158 mOsm./kg. versus 939 +/- 147 and 962 +/- 151, respectively, p <0.05). Analogously average daytime urine production in the desmopressin responder group was greater than in dry children and desmopressin responders (22.2 +/- 10.2 ml./kg. body weight versus 15.4 +/- 7.3 and 15.3 +/- 7.2, respectively, p <0.01). Average functional bladder capacity expected for age was less in desmopressin nonresponders than in dry children and responders (52.2% +/- 19.9% versus 79.2% +/- 30.4% and 69.5% +/- 25.7%, respectively, p <0.001).

CONCLUSIONS

Desmopressin responders produced larger amounts of less concentrated urine than the other children, while desmopressin nonresponders had smaller bladder capacity than the other groups. These results support the idea that enuretic children who respond favorably to desmopressin treatment have polyuria, whereas children with therapy resistant enuresis have detrusor hyperactivity.

Renal blood flow increase during volume expansion in hydronephrotic rats

PURPOSE

We assessed the renal blood flow pattern in experimental hydronephrosis during normal hydration and extracellular volume expansion.

MATERIALS AND METHODS

Partial obstruction of the left ureter was created in 3-week-old Sprague-Dawley rats by embedding the ureter in a psoas muscle groove. Moderate hydronephrosis without kidney weight reduction developed in all cases. The effects on renal hemodynamics were studied with real-time ultrasound flowmetry 3 weeks later during normal hydration and then during volume expansion. The degree of hydronephrosis was classified as mild, moderate or severe.

RESULTS

Under baseline conditions renal blood flow was normal in mild and moderate hydronephrosis but low in severe hydronephrosis. During volume expansion renal blood flow increased significantly in all experimental animals (mean 14%) compared to that in controls, which remained unaffected or decreased (mean -3%). The flow increase was related to the degree of dilatation, which was 2% in mild, 13% in moderate and 44% in severe hydronephrosis when the groups were considered separately.

CONCLUSIONS

A significant increase in renal blood flow proportional to the degree of hydronephrosis occurred as a result of volume expansion. This finding may be explained by a state of vasodilatation combined with a reduction in the filtration coefficient.

The overactive bladder in children: a potential future indication for tolterodine

OBJECTIVE

To determine the safety, efficacy and pharmacokinetics of tolterodine in children with an overactive bladder.

PATIENTS AND METHODS

Thirty-three children (20 boys and 13 girls, aged 5-10 years) with an overactive bladder and symptoms of urgency, frequency and/or urge incontinence were enrolled in an open, dose-escalation study. Patients were treated with oral tolterodine 0.5 mg (n = 11), 1 mg (n = 10) or 2 mg (n = 12) twice daily for 14 days. The primary safety endpoint was the change in residual urinary volume, as determined by ultrasonography. In addition, voiding diary variables (frequency and incontinence episodes) and pharmacokinetics were evaluated. Other safety endpoints included laboratory variables, electrocardiogram recordings and reported adverse events.

RESULTS

There were no safety concerns in terms of the change in residual urinary volume for any of the three dosage groups; values were comparable with baseline after 2 weeks of treatment for all three dosages. Adverse events were reported by 20 patients (six on 0.5 mg, five on 1 mg, and nine on 2 mg). Most adverse events were not considered to be drug-related; of the 13 possibly related events, 10 occurred in those taking 2 mg. Headache was the most commonly reported adverse event. No serious adverse events were reported and there were no general safety concerns. There was an improvement in voiding diary variables in all treatment groups after 2 weeks of treatment, although the efficacy was greatest in those taking 1 mg and 2 mg. Pharmacokinetic findings were consistent with dose linearity over the range 0.5-2 mg.

CONCLUSION

The results support the use of 1 mg twice daily as the optimal dose of tolterodine for treating children aged 5-10 years with an overactive bladder.

Effect of thromboxane and nitric oxide blockade on renal blood flow increase during volume expansion in hydronephrotic rats

OBJECTIVE

It has recently been found that hydronephrotic rats, despite low diuresis, show a significant increase in renal blood flow (RBF) during volume expansion. The present experiments were designed to evaluate the mechanisms underlying this phenomenon.

MATERIAL AND METHODS

Three-week-old Sprague-Dawley rats underwent partial obstruction of the left ureter using the Ulm-Miller psoas groove technique. The effects on RBF were studied 3 weeks later under general anesthesia using real-time ultrasound flowmetry, first during normohydration and then during extracellular volume expansion, in both untreated animals, and after prior blockade of either thromboxane or nitric oxide.

RESULTS

Significant hydronephrosis developed in all cases. RBF was normal under control conditions. During volume expansion RBF increased significantly in untreated experimental animals (mean 7.5%). In contrast to this finding, RBF remained unchanged during volume expansion in both the thromboxane and nitric oxide blockade groups.

CONCLUSION

It is concluded that a thromboxane- and/or nitric oxide-dependent RBF redistribution takes place in hydronephrotic kidneys during volume expansion.

Enuresis--background and treatment

Nocturnal urinary continence is dependent on 3 factors: 1) nocturnal urine production, 2) nocturnal bladder function and 3) sleep and arousal mechanisms. Any child will suffer from nocturnal enuresis if more urine is produced than can be contained in the bladder or if the detrusor is hyperactive, provided that he or she is not awakened by the imminent bladder contraction. Urine production is regulated by fluid intake and several interrelated renal, hormonal and neural factors, foremost of which are vasopressin, renin, angiotensin and the sympathetic nervous system. Detrusor function is governed by the autonomic nervous system which under ideal conditions is under central nervous control. Arousal from sleep is dependent on the reticular activating system, a diffuse neural network that translates sensory input into arousal stimuli via brain stem noradrenergic neurons. Disturbances in nocturnal urine production, bladder function and arousal mechanisms have all been firmly implicated as pathogenetic factors in nocturnal enuresis. The group of enuretic children are, however, pathogenetically heterogeneous, and two main types can be discerned: 1) Diuresis-dependent enuresis - these children void because of excessive nocturnal urine production and impaired arousal mechanisms. 2) Detrusor-dependent enuresis - these children void because of nocturnal detrusor hyperactivity and impaired arousal mechanisms. The main clinical difference between the two groups is that desmopressin is usually effective in the former but not in the latter. There are two first-line therapies in nocturnal enuresis: the enuresis alarm and desmopressin medication. Promising second-line treatments include anticholinergic drugs, urotherapy and treatment of occult constipation.

Prevalence of postmenopausal symptoms in two age groups of elderly women in relation to oestrogen replacement therapy

A cross-sectional study of the whole female population of ages 71 and 81 years in a defined part of Sweden was undertaken to investigate the prevalence of oestrogen treatment and postmenopausal symptoms. A questionnaire was mailed to 2245 women, of whom 1084 (87%) aged 71 years and 611 (62%) aged 81 years left evaluable responses. Of the responding 71- and 81-year-old women 25 and 16%, respectively were receiving oestrogen, and 4 and 2% of all women of the respective age groups were on systemic treatment. Nearly half of all the women reported urinary incontinence, which was considerate for approximately half of these women. Five and 11% of the respective age groups had experienced more than two urinary tract infections (RUTI) in the last year. RUTI had occurred both in the oestrogen-treated group and in the non-treated group. Vegetative symptoms were still encountered among these elderly women. Previous fractures were frequent, being experienced after menopause by 29 and 39% of the 71- and 81-year-old women respectively. Thirty-five and 39% of the women in respective age group had sought medical help for postmenopausal symptoms. Of the women with moderate, severe or unbearable urinary incontinence, 60 and 66% of the respective age groups had sought medical help. In only few of the totals of women on oestrogen had the treatment a complete effect. Only 2 and 1% of all women in respective age group had been offered and undergone surgery for their urinary incontinence.

Injectable dextranomer-based implant: histopathology, volume changes and DNA-analysis

OBJECTIVE

To study the tissue reaction in and around the implant, the changes in implant volume and the DNA profile of the invading cells when a new substance, dextranomers in sodium hyaluronan solution (DiHA), was injected into experimental animals.

MATERIALS AND METHODS

Nine pigs were followed up from 2 weeks to 3.5 months and 34 rats were followed up from 3 weeks to 16 months after injection of DiHA into the bladder in pigs and into the subcutaneous tissue in rats. Histopathological analysis was performed in 16 pig and 63 rat implants. In 31 of the rat implants the DNA profile was analysed. Changes in implant volume over time were estimated in 51 rat implants during the period up to 12 months after implantation.

RESULTS

Histologically, in the early phases the area within and around the implant was fairly rich in cells, predominantly fibroblasts, inflammatory cells and giant cells of the foreign body type. Later in the process an increase in extracellular matrix around the microspheres and ingrowth of blood vessels was seen. No tissue necrosis or significant eosinophilia was observed around the implants. DNA measurements by flow cytometry revealed no aneuploid cells. There was a decrease in implant volume by 23% over a period of 12 months.

CONCLUSIONS

DiHA does not induce any major tissue changes in and around the implants. No DNA changes were observed during the study period of 16 months. DiHA seem to be a safe and suitable injectable substance with good tissue-augmenting properties.

Desmopressin resistant enuresis: pathogenetic and therapeutic considerations

PURPOSE

We tested the role of the bladder in the pathogenesis of desmopressin resistant enuresis by evaluating the influence of urine production on the timing of the enuretic event and the response to anticholinergic medication.

MATERIALS AND METHODS

We gave 33 children with monosymptomatic nocturnal enuresis resistant to the standard 0.4 mg. oral dose of desmopressin 0.4 and 0.8 mg. desmopressin and placebo tablets for 5 nights each in a double-blind crossover fashion. The time of enuresis or nocturia was documented. All 9 children who had at least 1 dry treatment period during the randomized portion of the study then received open label treatment with 0.8 mg. desmopressin. Nonresponders to this regimen and the remainder of the children were offered anticholinergic treatment.

RESULTS

Average time between bedtime and voiding was 5.0, 5.6 and 5.0 hours during the nights with placebo, and 0.4 and 0.8 mg. desmopressin, respectively (p = 0.12). Of the 9 children subsequently treated with 0.8 mg. desmopressin 5 became completely dry. Of the remaining 28 children given anticholinergic treatment 20 responded.

CONCLUSIONS

Antidiuresis does not delay the enuretic event in children with desmopressin resistant enuresis. This finding and the favorable response to anticholinergic medication favor the hypothesis that these children have nocturnal bladder instability. A subgroup of enuretic children responds to high but not normal doses of desmopressin.

Endoscopic treatment of children with vesico-ureteric reflux

Endoscopic subureteric injection of tissue-augmenting substances has become an alternative to long-term antibiotic prophylaxis and open surgery in the treatment of children with vesico-ureteric reflux. Successful elimination of reflux in about 80% of patients after a single injection (and in 90% after a repeat) has been achieved using the foreign-body non-degradable substances Teflon and silicone. Few patients have required open surgery and recurrence of reflux after initial successful treatment has occurred in only 5-10%. Concern has arisen, however, about possible distant migration and granuloma formation after injection of particulate plastic materials. Cross-linked bovine collagen is a biodegradable alternative substance, but with a lower response rate of 60% after the first treatment and a recurrence rate of 10-20%. Dextranomer in sodium hyaluronan is a new biological substance with microparticles with a response rate of 69% after the first injection. Biological substances have caused few complications. Present literature on injection treatment unfortunately focuses on elimination of reflux, with little attention to subsequent frequency of pyelonephritis or to the long-term development of the kidneys. Furthermore, there are no controlled, randomized studies with subureteric injection as one of the treatment alternatives. Thus, although having the advantage of being a minimally invasive procedure that can be performed on an outpatient basis, this technique needs to be tested in a large prospective study with the long-term renal outcome as the main end-point.

Depth of sleep and sleep habits among enuretic and incontinent children

In order to evaluate differences in sleep factors between children with wetting problems and dry children, questionnaire data were obtained from 1,413 schoolchildren between the ages of 6 and 10 y. The analyses were performed using logistic regression, and adjusted odds ratios (ORs) were calculated to approximate the relative risk. Current enuresis was associated with a subjectively high arousal threshold, pavor nocturnus, nocturia and confusion when awoken from sleep (ORs 2.7, 2.4, 2.1 and 3.4, respectively), whereas children with current incontinence often experienced bedtime fears, onset insomnia or nocturia (ORs 2.4, 2.3 and 2.7, respectively). Children exhibiting urinary urgency were overrepresented among both children with current enuresis (OR 2.5) and those with current incontinence (OR 17.2). It is concluded that impaired arousal mechanisms and bladder instability are aetiological factors underlying nocturnal enuresis.

Sleep of children with enuresis: a polysomnographic study

OBJECTIVE

To evaluate relationships between bladder voiding and sleep in children with enuresis.

METHODS

Polysomnographic recordings were obtained from 25 children, aged 7 to 17 years, with monosymptomatic nocturnal enuresis. During 52 recorded nights, 37 enuretic events were detected. Responders (n = 7) and nonresponders (n = 16) to desmopressin treatment were compared.

RESULTS

The mean latency between sleep onset and the first bladder voiding was 3 hours 20 minutes (SD = 2 hours 5 minutes). The number of voidings were 19, 7, 10, and 1 occurring during stages 2, 3, and 4, and rapid-eye movement sleep, respectively. Desmopressin responders were found to void during the early or late part of the night, whereas the voidings of the nonresponders were dispersed evenly throughout the night (chi2 = 8.09).

CONCLUSIONS

The enuretic event is a predominantly non-rapid eye movement sleep phenomenon. Responders and nonresponders to desmopressin treatment void during different parts of the night.

DiHA Dextran Copolymer, a new biocompatible material for endoscopic treatment of stress incontinent women. Short term results

BACKGROUND

This study was undertaken to investigate the safety and effect of DiHA, dextranomers in hyaluronan, a new biocompatible material for endoscopic treatment of stress incontinence, and to further develop the injection technique.

METHODS

Twenty women aged 38 to 90 years with genuine stress incontinence participated. Seventeen were followed for a minimum of 6 months after treatment and three for a minimum of 3 months. The DiHA implants were administrered by transurethral endoscopically controlled submucosal injections under local anesthesia. Safety was assessed mainly in terms of infection, need for catheterization, residual urine and dysuria. The treatment efficacy was estimated objectively by a short-term pad test with standardized physical exercise and a 48 h pad-test, 7 days, and 1, 3 and 6 months after treatment. The patient's subjective experience of the effect was also studied.

RESULTS

The implantation procedure was well accepted by the patients. Four patients required catheterization due to voiding problems during the first 24 postoperative hours. One patient had urinary retention 14 days postoperatively. No UTI or local infection was detected. Some patients had transient urgency. In 17 or 20 patients the treatment resulted in objective cure or improvement.

CONCLUSIONS

This substance shows promising qualities for endoscopic treatment of stress incontinence.

Osmoregulation and desmopressin pharmacokinetics in enuretic children

OBJECTIVE

The aim was to compare responders and nonresponders to antienuretic treatment with desmopressin with respect to pharmacokinetics and renal effects of the drug.

METHODS

Twelve children, aged 7.6 to 16.2 years, with nocturnal enuresis were examined. Six patients were nonresponders and 6 were responders to desmopressin treatment. The children were given 2 mg of desmopressin intravenously and plasma concentrations of the drug were monitored overnight. Urine parameters were followed for 24 hours after desmopressin administration. Ten patients also underwent a thirst provocation test.

RESULTS

Desmopressin pharmacokinetics did not differ between the groups. Neither nocturnal urine production nor morning urine osmolality after desmopressin injection differed between responders and nonresponders, whereas the responders produced significantly larger amounts of significantly less concentrated urine during the day after the injection compared with the nonresponders (urine production, 2.02 +/- 0.84 and 0.77 +/- 0.20 mL/kg/h; urine osmolality, 558 +/- 271 and 883 +/- 134 mOsm/kg). Nonresponders voided with smaller bladder volumes (2.43 +/- 0.68 mL/kg body weight) than responders (4.70 +/- 1.21 mL/kg). The responders produced significantly less concentrated urine than the nonresponders during the thirst provocation test (607 +/- 185 and 922 +/- 217 mOsm/kg, respectively).

CONCLUSION

Intravenous desmopressin pharmacokinetics and desmopressin renal effects did not differ between responders and nonresponders to desmopressin treatment. Nonresponders had a smaller spontaneous bladder capacity and responders produced less concentrated urine.

Desmopressin in the treatment of severe nocturnal enuresis in adolescents--a 7-year follow-up study

OBJECTIVES

To evaluate the role of long-term oral desmopressin (over a 7-year follow-up) in refractory enuretics, particularly in assessing the potential curative effect, and to analyse the results for specific types of patient to obtain clues about possible mechanisms of cure.

PATIENTS AND METHODS

The effect of oral desmopressin was investigated in 25 adolescents (aged 11-21 years) with severe monosymptomatic nocturnal enuresis. The long-term study consisted of two 12-week treatment periods, with the efficacy of the drug assessed as the reduction in the number of wet nights per week. Subsequently, the patients were followed-up for up to 7 years. Close contact was maintained with the families over this period ('good doctoring' approach). At 3-, 5- and 7-year intervals after completing the study, patients were assessed for dryness, frequency, treatment and sleeping habits, using postal questionnaires and telephone follow-up.

RESULTS

At the end of the long-term study, 35% of the patients remained dry without therapy. Within 2 years of ending treatment, 15 patients were dry, compared with an expected estimate of six by spontaneous resolution, and after 7 years, 19 patients were cured. Nocturia occurred in 75% of the enuretic patients but in only 5% of the healthy controls.

CONCLUSIONS

Active treatment of primary nocturnal enuresis with oral desmopressin has a clinically significant effect on the cure rate, which is maintained after ceasing therapy. The cure rate was higher than would be expected from spontaneous recovery alone during the first 2 years of the study and there was a significant further increase in the cure rate 7 years after ending therapy, again greater than the expected spontaneous cure rate. There also seemed to be a better response to treatment when it was prolonged. Furthermore, this therapy is safe when administered in the long-term.

Sleep and night-time behaviour of enuretics and non-enuretics

OBJECTIVE

To investigate connections between nocturnal enuresis and sleep factors such as the subjective depth of sleep and classical parasomnias.

PATIENTS, SUBJECTS AND METHODS

One hundred school children aged 6-10 years answered a questionnaire, with their parents, and the same questions were asked of a group of 29 children of the same age suffering from severe nocturnal enuresis.

RESULTS

There were significant differences in arousability, with the enuretic group being 'deep sleepers', and in the prevalence of onset insomnia, nightmares, interrupted sleep and bedtime struggles, which were all less common among the enuretics. The prevalence of classical parasomnias did not differ between the groups.

CONCLUSION

A high arousal threshold is one of the pathogenetic factors underlying nocturnal enuresis and we propose that this group of therapy-resistant enuretic children might not only sleep more deeply than their nonenuretic peers, but perhaps have 'better' sleep.

Lack of distant migration after injection of a 125iodine labeled dextranomer based implant into the rabbit bladder

PURPOSE

In recent years endoscopic treatment of stress incontinence and vesicoureteral reflux has been introduced. Reports of possible particle migration of the injected material to distant organs in humans and experimental animals have led to a search for biological nonmigration products. An implant found to have a good clinical effect in these conditions is dextranomer in hyaluronan. We performed this study in rabbits to investigate the possible migration of dextranomer particles.

MATERIALS AND METHODS

125Iodine labeled dextranomer particles were injected into the submucosal space of rabbit bladders, and samples of blood and various tissues were examined for radioactivity at scheduled intervals during a 28-day period. Furthermore, whole body autoradiography was performed 1 day, and 1 and 4 weeks after injection.

RESULTS

Radioactivity was found in blood samples and in all tissues but it remained at the background activity level except in the thyroid, where uptake representing free 125iodine was detected. In the bladder 41 and 45% of the injected dose remained within the bladder wall 1 day and 4 weeks, respectively, after injection. The remainder of the dose probably disappeared from the bladder wall by leakage into the urine shortly after deposition, as indicated by the finding of 10-fold higher urine radioactivity levels at day 1 than at day 28 after injection.

CONCLUSIONS

No distant migration of dextranomer particles occurs after submucosal injection of such an implant in the rabbit bladder wall.

The genetics of primary nocturnal enuresis: inheritance and suggestion of a second major gene on chromosome 12q

Primary nocturnal enuresis (PNE), or bedwetting at night, affects approximately 10% of 6 year old children. Genetic components contribute to the pathogenesis and recently one locus was assigned to chromosome 13q. We evaluated the genetic factors and the pattern of inheritance for PNE in 392 families. Dominant transmission was observed in 43% and an apparent recessive mode of inheritance was observed in 9% of the families. Among the 392 probands the ratio of males to females was 3:1 indicating sex linked or sex influenced factors. Linkage to candidate regions was tested in 16 larger families segregating for autosomal dominant PNE. A gene for PNE was excluded from chromosome 13q in 11 families, whereas linkage to the interval D13S263-D13S291 was suggested (Zmax = 2.1) in three families. Further linkage analyses excluded about 1/3 of the genome at a 10 cM resolution except the region around D12S80 on chromosome 12q that showed a positive two point lod score in six of the families (Zmax = 4.2). This locus remains suggestive because the material was not sufficiently large to give evidence for heterogeneity. Our pedigree analysis indicates that major genes are involved in a large proportion of PNE families and the linkage results suggest that such a gene is located on chromosome 12q.

Diurnal plasma vasopressin and urinary output in adolescents with monosymptomatic nocturnal enuresis

Plasma arginine vasopressin (AVP) levels, urinary flow and urine osmolality were investigated in a group of adolescents (20 boys and 5 girls), aged 11-21 y, with severe monosymptomatic nocturnal enuresis and a control group of healthy adolescents (16M and 4F) with similar age- and sex-distribution. Half of the control group was investigated twice, with an interval of 6 months. AVP samples were taken every fourth hour in all adolescents and half of the control group were also investigated every second hour to achieve more samples during controlled sleep. After the study the enuretic group were put on long-term oral desmopressin (DDAVP). The difference between day and night values of AVP was significant for both groups, but there was no difference in the day/night ratios of plasma-AVP. All the adolescents produced less urine while asleep, but the controls produced significantly more urine than the enuretics during day. The controls also had a significantly larger nocturnal elevation of urine osmolality than the enuretics, thus a tendency towards polyuria was found. We could not find any significant difference between responders to DDAVP treatment and non-responders in any of the parameters studied. AVP is secreted in a pulsatile fashion and with point hormone samples taken every fourth or second hour we were unable to find any difference in the diurnal AVP secretion between enuretics and normal controls.

Bladder exstrophy in Sweden--a long-term follow-up study

A retrospective review of all new cases of bladder exstrophy in Sweden in 1970 through 1989 is presented. The aim was to evaluate management of the malformation in Sweden and possibly identify factors that might improve the outlook. The incidence was 1:33,500 births. Records were reviewed of the 61 children (37 males and 24 females) treated at Sweden's four specialist centers of pediatric surgery. There was one perinatal death. Primary management was mainly early bladder closure (within 72 hours), late closure or perinatal urinary diversion. Subsequent measures included augmentation cystoplasty, bladder neck reconstruction, provision of continent urinary reservoir and penile reconstruction. The follow-up time was 4-19 years. In 15 cases renal scarring developed, though with impairment of total function in only three. Ten patients achieved continence, defined as 3-hour dry intervals, of whom four had urinary reservoirs with continent stoma. Urinary tract infections were recorded during follow-up in 43% of the surviving patients, though the true incidence of infection presumably was higher. To improve management of bladder exstrophy in sparsely populated Sweden, a nation-wide strategy of ongoing interhospital collaboration has been adopted. Results will be continuously presented.

Prevalence of genitourinary and other climacteric symptoms in 61-year-old women

In a population-based cohort study, 1280 women, aged 61, were interviewed regarding their genitourinary and other postmenopausal symptoms by means of an anonymous questionnaire. The group selected was to constitute all women of 61 years of age living in Uppsala county, Sweden. The response rate was 84%. All were postmenopausal women. Seventy-three percent of the women answering admitted some degree of urinary incontinence and 33% more severe degree. Forty-nine percent reported some degree of stress incontinence, 25% a more severe degree. Thirty-one percent experienced urge incontinence, 14% severely. A minority (4%), had had more than two urinary infections during the last year. The majority (67%) had changed urinating habits, going to the toilet at night and a minority complained of increased frequency of micturation (8%). Of the participating women, 59% were still sexually active, 43% had trouble with vaginal dryness and 10% with vaginal burning. Vasomotor problems such as hot flushes (30%), daily (33%) and nightly sweating (36%) were all common troubles. Forty-seven percent of the women had asked for medical help for estrogen deficiency problems, 82% were satisfied with the help they had received. Thirty-four percent were on estrogen therapy, 16% had systemic therapy 18% low dose estrogen treatment.

A national center for sexually abused women in Sweden

Sexual violence is a significant global problem. The unequal power between men and women is considered to be the main reason for violence against women. Women who are exposed to sexual assault are great consumers of medical and social care. The Swedish government has reacted to the problem by establishing an expert center for battered and raped women. The center has three main tasks: treatment in a professional and empathic way; research into and development of medical and psychosocial treatment of patients and the underlying causes of sexual violence; education and information of the general public.

The prevalence of urogenital symptoms in postmenopausal women

Lower urogenital tract disorders, such as vaginal athropy, urethritis, dyspareunia, recurrent urinary tract infections and urinary incontinence symptoms, are more prevalent in postmenopausal women. While these disorders are attributed to the ageing process as well as estrogen deficiency, knowledge of the relationship between estrogen status and symptomatology is scarce and hard to investigate due to the complexity of the problem. Little is known about the epidemiology of urogenital symptoms and their relationship to estrogen status and treatment. Studies of the prevalence of urogenital symptoms in postmenopausal women have been rare and results divergent. Through reviewing existing literature and relating findings to our own prevalence studies of 61-, 71- and 81-year-old women, we can conclude that many of the symptoms accounted for in our study are those known to be due to the loss of estrogen and easily dealt with by estrogen therapy. However, there is a need for more adequate information about postmenopausal symptoms and the effect of estrogens, as only a minority of postmenopausal women are currently treated.

A new bioimplant for the endoscopic treatment of vesicoureteral reflux: experimental and short-term clinical results

We investigated the safety and clinical effects of a new biocompatible, biodegradable treatment, the Deflux system (dextranomer microspheres in sodium hyaluronan solution), for the endoscopic treatment of grades III and IV vesicoureteral reflux. In preclinical safety studies in pigs histopathological examination demonstrated excellent tolerance. Two weeks after submucous implantation in the pig bladder early ingrowth of fibroblasts and recently generated collagen were noted at the implantation sites. At 14 weeks of followup this ingrowth had slightly increased. Long-term followup in rats showed that the volume of subcutaneous implants was slightly reduced (23%) 1 year after implantation. In a clinical study we investigated the implantation technique and the short (3 months) and long-term (1 year) effects of Deflux implantation in 75 children (101 ureters) with grades III and IV vesicoureteral reflux. We report data from up to 3 months of followup. Implant volumes of 0.4 to 1.0 ml. were sufficient to create distinct boluses and crescent-like ureteral orifices. Although viscous, due to its viscoelastic properties the substance was easy to inject in a well controlled manner. At cystography 3 months later reflux had resolved in 68% of implants, was reduced to grades I and II in 13% of implants and was unchanged in 19% of treated ureters (grades III and IV reflux). No signs of ureteral obstruction or adverse reactions were noted. Results from 1 year of followup will be reported later. Our results indicate that the dextranomer microspheres act as micro-carriers that promote ingrowth of fibroblasts and generate new collagen. We conclude that the Deflux system may represent a new, safe, simple alternative to endoscopic treatment of vesicoureteral reflux in children.

Tubuloglomerular feedback in rats with chronic partial bilateral ureteral obstruction

Rats with chronic partial unilateral ureteral obstruction (UUO) have a paradoxical resetting of the tubuloglomerular feedback (TGF) mechanism. During extracellular fluid volume expansion (VE) in control animals, a decrease in TGF sensitivity is normally noted. In rats with partial UUO, however, TGF sensitivity in the obstructed kidney was increased, associated with a relative reduction in single nephron glomerular filtration rate. In the present study, we examined the tubular and interstitial pressures, whole kidney function and the TGF system in rats with chronic partial bilateral ureteral obstruction. The rats were divided into preferentially ipsilaterally and preferentially contralaterally obstructed, as judged by pelvic volume. Measurements were performed both during hydropenia and during VE. During hydropenia TGF characteristics were the same in the 2 groups. During VE, however, TGF sensitivity was unchanged in the most obstructed kidneys (ipsilateral), while if the obstruction was preferentially contralateral, TGF-sensitivity decreased. This opposite change in TGF sensitivity resulted in higher electrolyte and water excretion from the least obstructed kidney. The change in TGF sensitivity was not correlated to renal interstitial pressure.

IN CONCLUSION

rats with moderate chronic partial bilateral ureteral obstruction have an almost preserved function with regard to renal hemodynamics and excretion during hydropenia. During volume expansion, however, different responses were found in the least and most obstructed kidneys, with a decreased sensitivity of TGF in the least obstructed kidney, while TGF sensitivity was unchanged in the most obstructed kidney.

Desmopressin tablets in the treatment of severe nocturnal enuresis in adolescents

BACKGROUND

In recent years the treatment of primary nocturnal enuresis (PNE) with desmopressin (DDAVP) has been promising. The route of administration until now had been intranasal, but because the tablets were introduced for the treatment of diabetes insipidus they have also become available for the treatment of PNE.

OBJECTIVES

To find the optimal dosage of desmopressin tablets and to compare desmopressin's efficacy with placebo in a group of adolescents with severe monosymptomatic enuresis. The long-term safety of desmopressin was also studied in the same group of patients.

METHODS

The effect of oral desmopressin (1-deamino-8-D-arginine-vasopressin) (DDAVP tablets, Minirin) was investigated in 25 adolescents (ages 11 to 21 years) with severe monosymptomatic nocturnal enuresis. The first part of the dose-ranging study comprised a single-blind dose titration period, followed by a double-blind, crossover efficacy period comparing desmopressin with placebo. The final part was an open long-term study consisting of two 12-week treatment periods. The efficacy of the drug was measured in reductions of the number of wet nights per week.

RESULTS

During the first dose-titration period, the majority of the patients were given desmopressin 400 micrograms, and the number of wet nights decreased from a mean of 4.9 to 2.8. During the double-blind period, a significant reduction of wet nights was observed (1.8 vs 4.1 for placebo). During the two long-term periods, 48% and 53% of the patients could be classified as responders (0 to 1 wet night per week) and 22% and 23.5% as intermediate responders (2 to 3 wet nights per week). No weight gain was observed due to water retention. After cessation of the drug, 44% of the patients had a significant decrease in the number of wet nights.

CONCLUSIONS

Oral desmopressin has a clinically significant effect on patients with PNE, and therapy is safe when administered as long-term treatment.

Renal tubular apoptosis after partial ureteral obstruction

Partial ureteral obstruction in the weanling rat leads to hydronephrosis of the ipsilateral kidney and renal cell deletion through the process of programmed cell death known as apoptosis. The apoptotic response following partial ureteral obstruction in weanling Sprague-Dawley rats was studied using the traditional markers of apoptosis, including deoxyribonucleic acid (DNA) laddering pattern on agarose gel electrophoresis, in situ gap labeling of fragmented DNA for quantitative apoptotic body determination, polyadenylated messenger ribonucleic acid (mRNA) expression of sulfated glycoprotein-2, and polyadenylated mRNA expression of epidermal growth factor and transforming growth factor-beta. Partial ureteral obstruction resulted in a progressive increase in the intensity of DNA fragmentation associated with apoptosis during the initial 3 weeks. Quantitative apoptotic body counting revealed a 3-fold increase by week 3 of partial obstruction. This increase represented a level of apoptosis, which is 65% of that observed in complete ureteral obstruction. By week 2 of partial obstruction there was a 13-fold increase in the expression of sulfated glycoprotein-2 mRNA, as well as changes in the growth factor environment characterized by a decline in the constitutive expression of epidermal growth factor mRNA and an increase in the expression of transforming growth factor-beta mRNA. These altered levels represent changes in expression comparable to those observed during the apoptotic response following complete ureteral obstruction, although the time course is delayed by 2 to 3 weeks.

Treatment with oral desmopressin in adolescents with primary nocturnal enuresis. Efficacy and long-term effect

Twenty-four adolescents, mean age 13.5 years, with primary nocturnal enuresis (PNE), were studied to evaluate the efficacy of long-term oral desmopressin use. Reduction in mean number of wet nights per week was the criterion for response. Results showed that during 12-week treatment Period I, 48% were full responders (< or = 1 wet night/wk); 22% were intermediate responders (2 to 3 wet nights/wk); and 30% were nonresponders (> 3 wet nights/wk). During 12-week treatment Period II, 53% were full responders, 23.5% were intermediate responders, and 23.5% were nonresponders. Despite a high relapse rate (50% after Period I, 56% after Period II), 17 patients (71%) were completely dry 2 years posttreatment, suggesting a possible curative effect of oral desmopressin. It was concluded that oral desmopressin is comparable to the intranasal formulation, with a good, long-term therapeutic effect in adolescents with PNE.

Renal interstitial pressure and tubuloglomerular feedback control in rats during infusion of atrial natriuretic peptide (ANP)

Atrial natriuretic peptide (ANP), injected at physiological concentrations, is known to induce both natriuresis and diuresis. It has been suggested by some investigators that these changes result from an increasing glomerular filtration rate (GFR), but others have been unable to demonstrate an increased GFR. The tubuloglomerular feedback (TGF) mechanism is an important regulator of GFR, and the sensitivity of TGF is decreased during ANP administration. Furthermore, resetting of TGF is, in most instances, related to changes in renal interstitial hydrostatic and oncotic pressures. It is also known that ANP may increase capillary permeability which may change renal interstitial pressure. The present study was performed to examine renal interstitial pressures and the TGF mechanism during ANP infusion. In accordance with previous studies, TGF sensitivity was found to be decreased. The tubular flow rate which elicited half the maximal drop in stop-flow pressure (Psf) was increased from 18.5 to 25.7 nl min-1. In contrast, ANP infusion resulted in a decreased interstitial hydrostatic pressure and an increased interstitial oncotic pressure. From previous experiments, such changes in interstitial pressures would be expected to increase TGF sensitivity. The changes in interstitial pressure cannot, therefore, directly explain the resetting of the feedback mechanism. In conclusion, the present paper shows a decreased renal net interstitial pressure after intravenous administration of ANP.

Long-term partial ureteral obstruction and its effects on kidney function

Previously it has been shown that partial ureteral obstruction present in young rats for 12 weeks results in small morphological changes in the kidney as well as slightly decreased kidney function. In the present study the aim was to examine whether rats obstructed for one year had more advanced changes in morphology and kidney function. The first group of animals examined after three weeks of obstruction showed only modest changes in kidney function with a reduced potassium concentration in the urine but no reduction in the glomerular filtration rate. After one year there was a reduction in urine flow as well as in the excretion of both potassium and sodium. Urine osmolality was also reduced. Glomerular filtration rate measured in this group of animals was reduced in the obstructed kidney by about 60% compared to the contralateral one. There were only small changes in the morphology with no loss in parenchymal weight or compensatory hypertrophy, but there was a significant deformation of the papilla and an increase in inflammatory cells in the parenchyma. In conclusion hydronephrosis during a shorter period is not harmful to kidney function but if sustained for an extended time period kidney function will deteriorate.

Effect of thromboxane inhibition on tubuloglomerular feedback in hydronephrotic kidneys

The tubuloglomerular feedback (TGF) system is less sensitive after extracellular volume expansion (VE). In rats with partial ureteral obstruction, however, we have previously found increased TGF sensitivity during such expansion. Thromboxane A2 (TXA2) has been reported to be increased in the hydronephrotic kidney, and the present study was undertaken to investigate whether TXA2 might be responsible for these findings. The TGF characteristics were studied, by means of the stop-flow technique, in control and hydronephrotic rats before and after intravenous injection of either a thromboxane synthetase inhibitor or a thromboxane receptor antagonist during hydropenia. After VE, TGF was studied again. Proximal tubular stop-flow pressure (Psf) was measured during perfusion of the loop of Henle with a modified Ringer's solution, the maximal response (delta Psf) to an increased tubular flow rate was determined and the tubular perfusion rate which elicited a half-maximal decrease in Psf, designated the turning point, was recorded. In hydropenic control or hydronephrotic animals, TXA2 did not permanently change the TGF characteristics. During VE of the TXA2-blocked hydronephrotic animals, blocked both with synthetase inhibitor or receptor-antagonist, TGF was reset to a lower sensitivity like VE controls, as indicated by a high turning point and a low delta Psf. It was therefore concluded that thromboxane A2 inhibition does not influence the TGF system in hydropenia, but that the production of thromboxane A2 is responsible for the resetting of the TGF system during VE in hydronephrotic animals.

Back-leak of pelvic urine to the bloodstream

The aim of the present investigation was to measure the back-leak of pelvic urine to the blood circulation. In normopenic hydronephrotic, dehydrated hydronephrotic and dehydrated control kidneys the back-leak was estimated from a servocontrolled machine which regulated infused saline to keep a present pelvic pressure constant. The disappearance of fluid from the renal pelvis could be measured at different pressure levels, and a pressure-dependent outflow of fluid was found. From these measurements a back-leak conductance could be calculated which proved to be independent of pressure. In the lower pressure range (15-20 mmHg) there was a significantly lower conductance in the dehydrated controls compared with the dyhydrated hydronephrotic kidneys, while in the higher pressure range (25-30 mmHg) no difference was found. From electron microscopical studies the pyelorenal back-leak of fluid in both hydronephrotic and control animals seemed to be most pronounced in the fornix region, as documented by a heavy presence of horseradish peroxidase in the intracellular spaces there. Other experiments with radioactively labelled inulin, which was injected into the pelvic cavity, indicated that most of the back-leak occurred via the renal blood vessels and not through the lymphatic system. The importance of this back-leak was evident from the measurements of the total kidney glomerular filtration rate (GFR) at a slightly increased pelvic pressure, where some of the urine with radioactive tracer flows back to circulation. The back-leak of pelvic urine could also affect the concentration mechanism by removing diluted urine which had flowed over the renal papilla, and through water and urea diffusion increased papillary interstitial osmolarity.

Pressure and flow measurements in the partially obstructed ureter of the rat

Hydronephrosis in man or experimental animals can be caused by an increased ureteral flow resistance. This condition can in the long run prove harmful to renal function. We compared two ways of measuring ureteral flow resistance in animals with and without a ureteral hindrance, the hindrance being induced by embedding the ureter in the psoas muscle. One needle connected via catheters to a pressure recording system and another connected to a pump system were introduced through the parenchyma into the renal pelvis. Experiments were carried out with two procedures: 1) infusion of 0.5 ml x min-1 of saline into the renal pelvis was performed while recording the pressure response; 2) a servocontrolled pump system was used which regulated the flow introduced into the renal pelvis to keep a preset pressure at a constant level. In the first group of experiments we did not establish a steady-state pressure despite 20-30 min of infusion. The result from the second series of experiments indicated that steady-state flow measurements could be achieved at the different pressure levels between zero and 30 mmHg. A good linear relationship between pressure and flow was found, even though a considerable hysteresis was observed. Furthermore, a reduced flow resistance down to a certain level at increased pressure was also recorded. As expected, the resistance to flow was significantly lower in the control than in the hydronephrotic animals. In order to investigate the diagnostic ability of the linear relationship between pressure and flow, prediction regions for one future animal were calculated. It seemed possible that determination of the whole pressure-flow relationship in the pressure range between zero and 30 mmHg will prove useful to determine the flow hindrance in hydronephrotic animals.