Jan C. Molenaar

Renal Function up to 50 Years After Unilateral Nephrectomy in Childhood

Removal of one kidney during childhood differs from removal of a kidney from an adult as the childs future depends on an adequate function of the remaining kidney during a longer period of time. We assessed the long-term effect of unilateral nephrectomy in childhood on renal function, protein excretion, and blood pressure. Data were obtained from 111 subjects undergoing uninephrectomy for unilateral renal disease before the age of 16 years who had no evidence of renal abnormalities in the contralateral kidney at the time of surgery. At investigation the patients were 18 to 56 years of age with an interval of up to 52 years after uninephrectomy. On average, renal function was well maintained at approximately 75% of the reported normal two-kidney value. Blood pressure in men was higher than in women. Stratification for age showed no statistically significant differences between those undergoing uninephrectomy before or after the age of 4.5 years. Stratification for post-uninephrectomy interval revealed renal function to be lower and blood pressure, urinary albumin excretion, and protein excretion to be higher in those with an interval of more than 25 years. In men over 30 years of age, linear regression analysis indicated a decrease in glomerular filtration rate, effective renal plasma flow, and creatinine clearance, and an increase in blood pressure and albumin excretion with time. Controlled longitudinal studies are needed to detect true changes and to ascertain whether such changes are different from the age-related changes seen in individuals with two kidneys.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrasonography is accurate enough for the diagnosis of intussusception

For more than 10 years the authors have been using ultrasonography to confirm clinically suspected intussusception without performing a contrast enema. The aim of this study is to review this diagnostic policy. Between 1980 and 1989, 163 children who, on clinical examination and plain abdominal radiographs were suspected of having intussusception, underwent ultrasonography to confirm the diagnosis. In 33 children, ultrasonography did not show intussusception; of the remaining 130 children, intussusception was diagnosed in 128. In two children in whom intussusception was noted subsequently, the diagnosis was not established on ultrasound. Thus, ultrasonography had a sensitivity of 98.5% and a specificity of 100% in the diagnosis of intussusception. It is a quick, simple, noninvasive method to diagnose intussusception, with high accuracy. The role of contrast enema is limited to therapeutic application.

The effect of fetal urine on the development of thebowel in gastroschisis

A gastroschisis model was successfully developed in the chicken embryo. The embryologic anatomy of this laboratory animal enabled the inducement of an abdominal wall defect, whereby the eviscerated abdominal contents were not exposed to fetal urine. A total of 999 embryos underwent a surgical intervention at an early developmental stage, from the 5th-8th day of the incubation period. Twenty-four hour mortality was 7%. Surgery carried out on the 5th day resulted in the largest number of survivors, 25% of the induced lesions had healed and gastroschisis did not occur. The characteristic picture of gastroschisis only evolved when the herniated bowel was exposed to urine components. Histologic studies were carried out with the aid of various staining techniques to determine the development and distribution of the enteric ganglia in experimental gastroschisis. Contrary to similar studies that would point to damage of enteric ganglion cells as being responsible for the delay in intestinal motility, no ganglionic injury was noted in our bowel studies.

Urogenital tract abnormalities associated with congenital anorectal anomalies

Of 150 children with congenital anorectal malformations 50 per cent had urogenital abnormalities. Vesicoureteral reflux was noted in 47 per cent of the children with a supralevator and in 35 per cent with an infralevator lesion. A urinary tract evaluation is recommended in all children with congenital anorectal anomalies.

Development of Renal Function in the Rat

Clearance methods, allowing for repeated use in the same animals, were applied in a cross-sectional study to establish the normal increase in renal function in rats. It was shown that the glomerular f

Diagnosis of congenital neurogenic abnormalities of the bowel with monoclonal anti-neurofilament antibodies

The diagnostic properties of two monoclonal, antineurofilament antibodies were tested in a retrospective investigation of bowel specimens of 24 cases of Hirschsprungs disease, eight cases of long-segment aganglionosis, eight cases of pseudo-obstruction, and six cases of chronic constipation. Immunohistochemical staining with the antibodies in combination with hematoxylin counterstaining revealed six distinctive and divergent pictures, demonstrating innervation disturbances in all cases. Apart from Hirschsprungs disease and long-segment aganglionosis, characteristic pictures also appeared for pseudo-obstruction and, diversely, for chronic constipation. In addition, anomalies were revealed in the ganglionic, proximal bowel of five patients with Hirschsprungs and two with long-segment aganglionosis, who had all suffered from chronic constipation postoperatively.

Changes in the glomerular filtration rate after unilateral nephrectomy in rats

Changes in the glomerular filtration rate (GFR) were studied in rats, 4 h to 4 weeks after unilateral nephrectomy (NX). The GFR was determined with a technique using51Cr-EDTA and a single timed blood sample. The GFR determined in this way corresponded with the GFR calculated by two compartment analysis and with the plasma levels of creatinine and urea.Increases in the GFR, compared with half the GFR of sham operated rats, were observed as early as 4 h after NX. This increase was entirely due to an increase in the GFR per gram of kidney, since no increase in kidney weight was observed at that time. After the initial increase, the GFR remained at that level during the first 48 h after NX. At 48 h a significant increase in kidney weight per 100 g body weight had taken place. The longterm changes in the GFR amounted to an increase of about 80% of that of sham operated rats after 3–4 weeks. After 4 weeks, the increase in the GFR of the remaining kidney was due to an increase in kidney weight of 35% as well as an increase in the GFR per gram of kidney of 20%.These data indicate that the increase in the GFR of the remaining kidney after unilateral NX occurs rapidly and is independent of an increase in kidney weight. Compensatory hypertrophy develops at a later stage and helps to maintain the increased function of the single remaining kidney.

Long-term follow-up of renal function in rats with unilateral hydronephrosis.

In order to obtain more information on the long-term changes in renal function of hydronephrotic kidneys, we have measured the glomerular filtration rate (GFR) in rats with a congenital or an experimental unilateral hydronephrotic kidney (HK). In Brown Norway rats, with congenital hydronephrosis, the presence of an HK affected neither the total GFR nor the contribution of that kidney to the total GFR, during a follow-up of 70 weeks. In Wistar rats with experimental unilateral hydronephrosis two groups could be distinguished on the basis of the contribution of the HK to the total GFR. In the first, the contribution of the HK to the total GFR was not different from that of controls. This contribution as well as the total GFR remained similar to that of controls during the follow-up. In the second group, the contribution of the HK to the total GFR was reduced to 25%. In these rats the total GFR was slightly less than that of controls. The contribution of the HK to the total GFR remained unchanged for the next 56 weeks. It is concluded that the long lasting presence of unilateral hydronephrosis in rats does not necessarily result in a progressive loss of renal function with time.

Glomerular Hyperfiltration in Hypertensive Fawn-Hooded Rats

The glomerular filtration rate (GFR), effective renal plasma flow (ERPF), systolic blood pressure (SBP) and urinary protein excretion (UpV) were determined in 12-week-old male rats of the spontaneously hypertensive Fawn-Hooded (FH) strain. These data were compared with those of either age-matched or weight-matched male, normotensive Wistar Albino Glaxo (WAG) rats. The GFR was significantly higher in FH rats than in both WAG control groups. In contrast, the ERPF did not differ between the FH and WAG rats. Thus, a higher filtration fraction was present in the FH rats. As no differences were found in the total number of glomeruli per kidney comparing FH and WAG rats, the high GFR was not due to an increase in the number of glomeruli. The SBP and the UpV were significantly higher in FH rats than in WAG rats. To our opinion, the arterial hypertension associated with glomerular hyperfiltration proteinuria suggests the presence of glomerular hypertension in FH rats.

Cell division in migratory and aggregated neural crest cells in the developing gut: An experimental approach to innervation-related motility disorders of the gut

Extensive studies in the chicken embryo have recently supplied more insights into the development of the enteric nervous system, which mainly derives from the vagal neural crest (i.e., the neural crest opposite somites 1 to 7). Crest cells migrate from this region to and via the developing gut. By means of a double labeling technique of both neural crest cells and cells in the S-phase of the cell cycle, we found that these migrating crest cells still proliferate in the gut. Some cells even go through cell division after the formation of a nerve plexus. Some implications for the pathogenesis of congenital innervation abnormalities such as hyperganglionosis and the aganglionosis of Hirschsprungs disease are discussed.