Search PubMed⌕ Search

Biomedical subjects

J M Nijman

Publications and source records attributed to J M Nijman.

At least 19 recordsLinked to original sources
PubMed2002

Unilateral multicystic dysplastic kidney: a combined pre- and postnatal assessment.

OBJECTIVE: To review the prenatal assessment of associated renal pathology, non-renal pathology and renal biometry, fetal outcome and postnatal urological management in the presence of unilateral fetal multicystic dysplastic kidney. METHODS: A total of 38 singleton pregnancies with fetal unilateral multicystic dysplastic kidney was studied over a 13-year period. Prenatally, fetal biometry, including head and abdominal circumferences and largest longitudinal diameter of the affected and contralateral kidneys, was performed. The amount of amniotic fluid was assessed. Fetal karyotyping was offered in cases of contralateral renal or non-renal pathology. A MAG 3 scan and voiding cystogram was performed approximately 4 weeks after delivery to establish renal function and to exclude urinary reflux. RESULTS: Unilateral fetal multicystic dysplastic kidney was left-sided in 53% and right-sided in 47% of cases. The fetus was male in 63% and female in 37% of cases. Associated renal and non-renal pathology existed in 21% and 5% of cases, respectively. The fetal karyotype in these subsets was always normal. The longitudinal diameter of the multicystic dysplastic kidney was above the 95th centile in 87%. There was polyhydramnios in three cases and oligohydramnios in two cases. The prematurity rate was 16%. Postnatal examination revealed a non-functional multicystic kidney in 87% (33/38) of cases. Following surgical removal of the affected kidney, these infants progressed normally. Of the remaining five infants, four died because of associated anomalies and one infant developed normally without surgery. CONCLUSIONS: Fetal outcome is determined by associated renal and/or non-renal structural pathology and not by the size/location of the unilateral multicystic dysplastic kidney or amniotic fluid volume.

Amniotic Fluid↗
PubMed2002

Identification of bladder wall layers by Raman spectroscopy.

PURPOSE: We explored the applicability of Raman spectroscopy to in situ investigation of bladder wall tissue. MATERIALS AND METHODS: Bladder wall tissue was obtained from a guinea pig model and frozen sections were used for Raman spectroscopic investigations. From each section 500 to 700 spectra were obtained in a 2-dimensional grid spanning the urothelium, lamina propria and muscle layer. The data set of spectra was subdivided into groups of similar spectra by a cluster analysis algorithm. With each group assigned a different color Raman maps of frozen sections were constructed based on group membership of measured spectra. These maps were then compared with histological and histochemical data obtained from hematoxylin and eosin and immunohistochemical staining for collagen I and III and for smooth muscle actin to correlate Raman spectral features with bladder wall structure and molecular composition. RESULTS: Urothelium, lamina propria and muscle layers could be clearly distinguished based on Raman spectra. Lamina propria spectra were dominated by signal contributions of collagen and the smooth muscle layer showed strong signal contributions of actin. The urothelium had a relatively strong lipid signal contribution. CONCLUSIONS: These results and the fact that Raman spectroscopy is rapidly evolving into a technology that can be applied in vivo by thin, flexible fiberoptic catheters indicate that prospects are good for in vivo analysis of the molecular composition of the normal and pathological bladder without biopsies.

Actins↗
PubMed2001

[Differential diagnosis and treatment of girls with 46XY-karyotype and androgen insensitivity syndrome].

The importance of the secretion and action of androgens during the critical period of male sexual development is exemplified in patients with androgen insensitivity syndrome. Their karyotype is always 46XY. In 2 sisters, aged 11 and 13 years, the androgen insensitivity syndrome was diagnosed based on an androgen receptor gene mutation. Ambiguous genital development of a new-born was shown to be due to a lack of testosterone production, based on a luteinizing hormone receptor gene mutation. Finally, in a phenotypically female new-born a gene mutation of 17-beta hydroxysteroid dehydrogenase type 3 was found to be responsible for insufficient testosterone synthesis during embryonic development. The presentation of a patient, and specifically a neonate, with abnormal genital development represents a difficult diagnostic and therapeutic challenge. Referral to a centre with experience in the diagnosis and management of disorders of sexual development is advised where the emphasis should be on psychological and genetic counselling.

17-Hydroxysteroid Dehydrogenases↗
PubMed2001

Urodynamic follow-up of experimental urethral obstruction in individual guinea pigs.

It is unknown whether changes in bladder function due to urethral obstruction follow a specific sequence. To answer this, we adapted a small animal model to allow repeated complete pressure-flow studies, enabling individual follow-up of changes in bladder function on urethral obstruction. Obstruction was induced in guinea pigs by placing a silver ring around the urethra. Urodynamic studies were repeated under anesthesia with ketamine/xylazine. Bladders were filled and bladder pressure measured through a single suprapubic catheter. Urine flow rate was measured using an ultrasound probe around the penis. Accurate measurements of bladder pressure and urine flow rates were obtained at 1-week intervals for 11 weeks in individual guinea pigs. In the control animals, the urodynamic parameters did not show significant changes. In the obstructed group, urethral resistance (P(low,ave)) increased from 20 to 35 cm H(2)O after 4 weeks and remained at that level. The maximum flow rate (Q(max)) increased from 0.17 to 0.24 mL/s after 2 to 3 weeks. After this peak, it gradually decreased to lower than the starting value after 10 to 11 weeks. The pressure at maximum flow rate (p(Qmax)) increased from 24 to 47 cm H(2)O after 6 to 7 weeks and thereafter declined. During weeks 1 through 4 of obstruction, unstable contractions were seen. All animals followed a similar sequence of patterns but at variable rates. Our animal model allows complete urodynamic follow-up of individual animals with urethral obstruction. We observed a specific sequence of changes in urodynamic patterns and parameters of bladder function.

Animals↗
PubMed2000

[Prenatal ultrasonic detection of asymptomatic urogenital abnormalities: advantages and disadvantages].

Prenatal ultrasound studies have significantly contributed to the understanding of congenital abnormalities of the urinary tract and the development of pediatric urology over the past decade. Besides providing more insight into pathophysiology of the developing urinary tract, it has promoted the possibilities of early postnatal intervention and of studying the natural history of developmental abnormalities such as pelviureteral junction obstruction and vesico-ureteric reflux. The downside of this development has been and probably still is a considerable amount of diagnostic and therapeutic interventions for so-called abnormalities which, left alone, will disappear with time and without significant sequelae. On the other hand, many children with severe obstructive uropathy are alive today because of early intervention. Longterm follow-up studies are needed to prove the efficacy of prenatal screening and to ascertain the contribution of these technical possibilities to quality of life.

Contraindications↗
PubMed2000

Changes in bladder contractility and compliance due to urethral obstruction: a longitudinal followup of guinea pigs.

PURPOSE: We established the longitudinal changes in bladder contractility and compliance as a result of urethral obstruction using a guinea pig model. MATERIALS AND METHODS: Obstruction was induced in guinea pigs by a silver ring around the urethra. Urodynamic studies were performed longitudinally in individual animals. Bladder contractility and compliance were calculated from the measured bladder pressure and urine flow rate. RESULTS: Bladder contractility developed in distinct phases. It reached a maximum 200% increase after an average of 3.25 weeks concomitant with an almost 2-fold increase in urethral resistance, remained 150% to 200% increased during weeks 4 to 7 and then decreased to starting levels again, while urethral resistance remained almost 2-fold increased. Bladder compliance decreased by 80% during the first 3 weeks and continued to decrease to 5% of its original value after 10 to 11 weeks. CONCLUSIONS: Our data indicate that as a result of obstruction bladder function passes through a specific sequence of stages, including first a compensatory increase in contractility, then a stabilization phase and finally a decompensation state. In contrast bladder compliance shows a continuous decrease. The data suggest that for assessing how far a bladder has deteriorated due to obstruction a combination of functional and structural data may be warranted.

Animals↗
PubMed1998

Diagnosis and grading of detrusor instability using a computerized algorithm.

PURPOSE: Detrusor instability and hyperreflexia are characterized by involuntary detrusor contractions in the filling phase of the voiding cycle. The diagnosis is made when urodynamic evaluation reveals such contractions. To compare patients and evaluate treatment a method is needed to quantify the degree of instability. We developed an instability parameter based on the area under the curve of involuntary detrusor contractions on conventional filling cystometry. MATERIALS AND METHODS: We developed an automatic method to calculate the area under the curve of involuntary detrusor contractions in conventional filling cystometry. Logistic regression was used to construct decision rules to differentiate stable from unstable bladders. These rules, derived from a group of 100 children, were applied to a second group of 77 who were independently assessed by 3 urodynamics experts. RESULTS: Typically 88% of the second group were correctly classified as stable or unstable by the automatic procedure. In the unstable subgroup there was poor correlation between the calculated instability parameter and the instability score assigned by the experts. Most likely this difference occurred because the experts based their opinion mainly on the amplitude of the highest unstable contraction and the percentage of filling time that instability was found. CONCLUSIONS: The proposed method of automatically grading detrusor instability based on the area under detrusor contractions differs from the intuitive method used by experts. Since no standard is available, it cannot be concluded which method is better. Our proposed method is objective and it results in a single physical value.

Algorithms↗
PubMed1995

Developmental pattern and regulation by androgens of androgen receptor expression in the urogenital tract of the rat.

Distribution and regulation of androgen receptor expression during fetal and neonatal virilization of the rat fetus was assessed by immunohistochemistry. In mesonephric duct derivatives the androgen receptor expression became evident first in the efferent ductules and epididymis (on fetal day 14), subsequently in the vas deferens and finally in the seminal vesicle. Mesenchymal cells of the urogenital tubercle were positive for androgen receptors from fetal day 14 onwards. In the mesenchymal cells of the prostate anlagen, androgen receptor positive cells were found first on fetal day 16. Administration of 5alpha-dihydrotestosterone to pregnant rats from day 11 to day 20 of gestation caused a stabilization of the wolffian duct in female fetuses. The androgen receptor expression pattern became similar as found in mail fetuses, and showed an increase in density and in frequency of androgen receptor positive cells. Administration of the androgen antagonist flutamide during the same interval caused a reduction in density and frequency of androgen receptor positive cells in male fetuses. These findings indicate that androgens enhance the expression of androgen receptors in the developing rat genital tract by induction of androgen receptor positive cells, and by increasing the frequency. The developmental pattern of androgen receptor expression in the rat mesonephric duct system reflects the androgen-responsiveness of the ducts, and is consistent with induction of the androgen receptor along the ducts by testosterone reaching these structures in an exocrine fashion.

Androgen Antagonists↗
PubMed1995

Decreased immunoreactive androgen receptor levels are not the cause of isolated hypospadias.

OBJECTIVE: To elucidate whether diminished levels of androgen receptor (AR) are the underlying cause for the development of hypospadias by determining AR levels in the foreskins of boys with hypospadias. PATIENTS AND METHODS: The content of AR was determined by a sensitive immunoblotting technique in extracts from preputial tissue obtained from 15 patients (mean age 2.5, SD +/- 1.5 years) with hypospadias and from seven controls (mean age 2.5, SD +/- 1.5 years). Immunoreactivity of the protein was measured by densitometry. RESULTS: No significant difference in mean AR content was found between those boys with hypospadias (2.1 +/- 0.9 fmol/mg protein, +/- SD) and the age-matched control group (2.2 +/- 0.3 fmol/mg protein). Stratification by the severity of hypospadias (distal and proximal on the shaft, and penoscrotal hypospadias) showed that the severity was not related to tissue AR levels. CONCLUSION: It is unlikely that hypospadias is caused by a decreased expression of AR.

Child, Preschool↗
PubMed1995

Intrapelvic Wilms' tumor simulating xanthogranulomatous pyelonephritis.

A 2-year-old boy presented with an atypical renal mass with extension into the pyelocalyceal system and distal ureter which was diagnosed initially as xanthogranulomatous pyelonephritis (XGP). The final diagnosis was intrapelvic Wilms tumor extending into the ureter. In the literature, only three patients have been described with Wilms tumor extending into the ureter, none of whom had a continuous extension into the distal ureter.

Child, Preschool↗
PubMed1993

[Routine urodynamic studies is not indicated in children with enuresis].

From January 1980 to January 1992, urodynamic examinations were performed in 339 enuretic children without constipation or anatomical or neurogenic causes of incontinence. Nocturnal enuresis was seen in 178 patients, 130 children suffered from nocturnal and diurnal enuresis, and 31 had only diurnal enuresis. M. detrusor instability was found in 44% of the children and 73% showed more than 15% reduction in functional bladder capacity. In 5% an infravesical obstruction was suspected on pressure-flowmetry and in 12% dysfunctional voiding was seen. Routine urodynamic studies are not indicated in children with enuresis.

Child↗
PubMed1991

[Always wet].

Explore the source record for details and available documents.

Child↗
PubMed1991

Prenatal diagnosis, management and outcome of fetal uretero-pelvic junction obstruction.

Prenatal diagnosis, management and outcome were studied retrospectively in 24 cases of unilateral and bilateral uretero-pelvic junction obstruction (UPJO). Moderate-to-marked pelvic dilatation was documented in 19 out of 24 cases. The low morbidity and mortality observed in this study are probably determined by the late (third trimester) detection of UPJO, resulting in an underestimation of the prevalence of more severe renal pathology. Amniotic fluid was increased in 4 out of 14 cases of unilateral UPJO and in 5 out of 10 cases of bilateral UPJO, the underlying mechanism of which is still unclear. There was no oligohydramnios. The incidence of extrarenal structural pathology was low, i.e., 3 out of 24 cases. A close agreement could be demonstrated between pre- and postnatal sonographic grading of pelvic dilatation. However, postnatal ultrasonic grading of pelvic dilatation correlated poorly with the degree of functional obstruction as determined by IVP and lasix renography. Despite the severity of pelvic dilatation in the majority of cases, enlarged kidneys were revealed by postnatal clinical examination in only three instances, underlining the importance of prenatal sonographic detection of UPJO.

Birth Weight↗
PubMed1991

Forced hydration prior to renography in children with hydronephrosis. An evaluation.

We have developed a method of diuretic renography for the assessment of upper urinary tract obstruction in children. A maximal diuresis under standardised conditions is obtained by forced intravenous hydration over a 2-h period prior to renography. We evaluated the predictive value of this method for the clinical and functional outcome in 73 children with apparent unilateral pelviureteric junction obstruction. The predictive value of a non-obstructive pattern was 94%, while the predictive value of an obstructive pattern could not be assessed accurately because the patients concerned subsequently underwent operation. The method is safe and reliable and offers advantages over conventional diuretic renography.

Adolescent↗