John W. Duckett

Postnatal Testicular Maldevelopment in Unilateral Cryptorchidism

Histomorphometric analysis of semi-thin sections was performed on testicular biopsies of 232 unilaterally cryptorchid testes and 195 of their contralateral descended partners. The results demonstrated a decreased number of germ cells detectable from the first year of life. There was delayed and defective transformation of gonocytes to Ad spermatogonia, which normally is complete at age 6 months, delayed or failed transformation of Ad spermatogonia to primary spermatocytes, which normally commences at age 3 years and decreased numbers of Leydig cells. These abnormalities were present in the unilaterally cryptorchid testes and their contralateral descended partners but they were more severe, of earlier onset and more progressive in the cryptorchid testes. These findings are compatible with the hypothesis that hypogonadotropic hypogonadism is the cause of the increased incidence of infertility seen in unilateral cryptorchidism.

Ureteroceles in Children: Followup of Management with Upper Tract Approach

Ureteroceles can be associated with obstruction and/or reflux to any of the involved renal units. Their management is controversial and the possible options are numerous. From a population of 58 children with ureteroceles we analyzed those patients who underwent upper pole heminephrectomy alone as to the secondary operative rate. Followup examination of those patients whose management was initiated with upper pole partial nephrectomy and partial ureterectomy revealed a higher than expected incidence of persistent reflux.

THE MODERN ENDOSCOPIC APPROACH TO URETEROCELE

PURPOSEnDuring the last 20 years the surgical approach to ureterocele has evolved from major open surgery to minimally invasive endoscopic puncture. We believe that the endoscopic approach decreases the need for open surgical procedures. We identified specific factors that predict the need for repeat surgery.nnnMATERIALS AND METHODSnWe reviewed the charts of 60 new patients with ureterocele treated with primary endoscopic incision between 1991 and 1995. Followup ranged from 4 to 62 months (mean 20). Mode of presentation, ureterocele location, associated vesicoureteral reflux and association of the ureterocele with a duplex system were evaluated. Ureterocele wall thickness was assessed subjectively via radiographic and cystoscopic methods, and categorized as thin, intermediate and thick.nnnRESULTSnAll 9 patients with a single system ureterocele had an intravesical ureterocele. No patient had associated reflux nor did any require a secondary open procedure. In 3 cases new onset ipsilateral reflux into the ureterocele spontaneously resolved. Of the 51 patients with a duplex system and associated ureterocele 19 (37%) required a secondary open procedure. The ureterocele was intravesical and ectopic in 22 (43%) and 29 (57%) cases, respectively. Reflux was associated with the ureterocele in 27 patients (53%), and 12 (44%) required a secondary open procedure. A total of 11 patients underwent ureteral reimplantation of 15 refluxing renal units and only 2 renal units required ureteral tapering. Reflux is no longer present in 14 of the 15 renal units (93%). Patients with a thick walled ureterocele required repeat puncture more frequently than those with a nonthick ureterocele.nnnCONCLUSIONSnWith the use of modern endoscopic techniques children with intravesical and single system ureteroceles require secondary open surgery less frequently than those with ectopic and duplex system ureteroceles. The mode of presentation does not predict the need for a repeat open procedure. Thick walled ureteroceles require repeat endoscopic puncture more frequently than thin and intermediate walled ureteroceles.

Evaluation of Fetal Renal Function: Unreliability of Fetal Urinary Electrolytes

In the fetus with bilateral hydronephrosis it has been reported that a normal volume of amniotic fluid, absence of renal cortical cysts, urinary sodium less than 100 mEq./l., chloride less than 90 mEq./l. and osmolarity less than 210 mOsm. are prognostic factors indicative of good renal function, whereas oligohydramnios, cortical cysts and higher urinary levels of sodium, chloride or osmolarity suggest irreversible renal dysplasia. We report 5 cases in which the fetal urinary electrolytes were not predictive of ultimate renal function. In 3 instances fetal urinary electrolytes and osmolarity were abnormally elevated but the infants survived without ventilatory support. In 2 of these 3 patients the volume of amniotic fluid was normal. Diagnoses included posterior urethral valves, prune belly variant and bilateral ureteropelvic junction obstruction. In 2 cases with oligohydramnios fetal urinary electrolytes were suggestive of satisfactory renal function but the infants died of pulmonary hypoplasia and had bilateral renal dysplasia, prune belly syndrome and urethral atresia. Presently, the volume of amniotic fluid remains the most important prognostic sign in the fetus with bilateral hydronephrosis. Further work is necessary to identify other factors that may be more reliable as prognostic indexes of fetal renal function.

The Decompensated Detrusor II: Evidence for Loss of Sarcoplasmic Reticulum Function After Bladder Outlet Obstruction in the Rabbit

PURPOSEnWhile it may lack the classic morphological pattern in striated muscle systems, there is ample evidence that smooth muscle also contains sarcoplasmic reticulum. These intracellular storage sites release calcium into the cytosol to generate contractile force in response to various stimuli. A major component of the sarcoplasmic reticulum is an adenosine triphosphate dependent ion pump, which serves to drive free calcium out of the cytosol back into this intracellular reservoir. This ion pump serves to maintain the intracellular calcium storage sites, and also as a marker of the sarcoplasmic reticulum.nnnMATERIALS AND METHODSnMuscle strip studies were performed to stratify the data into 3 major groups (controls, and compensated and decompensated obstructions) based on physiological performance. These were correlated with biochemical and molecular determinations of sarcoplasmic endoplasmic reticulum calcium, magnesium-adenosinetriphosphatase expression.nnnRESULTSnOur results demonstrate a remarkable loss of sarcoplasmic endoplasmic reticulum calcium-adenosinetriphosphatase activity in the decompensated group and a moderate loss in the compensated group.nnnCONCLUSIONSnThese data provide molecular support for our previous physiological studies in which we demonstrated an important role for intracellular calcium storage and release with normal bladder smooth muscle function. These data strongly support our contention that contractile dysfunction in bladder smooth muscle following outlet obstruction is partially mediated by changes in the mechanisms of intracellular calcium homeostasis.

An Absent Testis is Associated with Contralateral Testicular Hypertrophy

Surgical exploration was done in 109 boys ages birth through 9 years with unilateral impalpable testes by physical examination under anesthesia. Of the patients 51 (47%) had an absent testis and 58 had intra-abdominal testes. At open biopsy of the contralateral descended testis the 3 dimensions of the exposed testis were recorded and testicular volume was calculated. The mean volume of the contralateral descended testes of boys with an absent testis was greater than that of boys with intra-abdominal testes at all ages. The differences were significant (p = 0.0019 to 0.0117) from birth through year 4 but not from years 5 through 9. However, the standard deviations ranged from 27 to 74% of the means, and there was broad overlap of the volumes of the 2 groups. These findings indicate that, although the volume of the contralateral descended testis of boys with an absent testis is significantly greater than that of boys with intra-abdominal testes, the volume of the contralateral descended testis is not a reliable criterion for differentiating an absent testis from an intra-abdominal testis in a boy with a unilateral impalpable testis. Surgical exploration continues to be the method of choice for making the diagnosis of an absent testis.

Developmental Aspects of Excitation Contraction Coupling of Rabbit Bladder Smooth Muscle

There is growing evidence that smooth muscle function changes with normal development. In this study a Scatchard analysis revealed that the binding of 3H-ryanodine changed from 6.6 fmol./mg. protein in 3-day-old rabbits to 44 fmol./mg. protein in 8-week-old rabbits (p < 0.05) with no associated developmental changes in the dissociation constants. The physiological findings using muscle strip techniques correlate well with these findings in that the neonatal bladders are far less sensitive to ryanodine than their mature counterparts. In contrast, nifedipine inhibited contractility in the neonatal group to a much greater degree than the mature group. These biochemical and physiological findings support our contention that the mechanism for excitation contraction coupling changes with normal development. Contraction in neonatal rabbit bladder smooth muscle is more dependent upon the influx of extracellular calcium and with normal maturation mechanisms for intracellular calcium storage and release begin to predominate.

Developmental Factors in the Contractile Response of the Rabbit Bladder to Both Autonomic and Non-Autonomic Agents

Previous work in this laboratory has demonstrated that the bladders of 1-day-old and 1-week-old rabbits generate higher pressures in whole-bladder preparations than bladders from mature 8-week-old rabbits. In addition, the density of cholinergic receptors does not change during this maturation period. The present study was designed to determine if the increased responsiveness of the neonatal bladder was specific for cholinergic stimulation. Using bladder strips, we have demonstrated that the newborn bladders generated much greater tension in response to ATP, serotonin, histamine, and substance P. The response of the 1-day-old bladder smooth muscle to these contractile agents was at least double the response of the 8-week-old bladders. However, the response of all age groups to bethanechol was approximately the same, and the response to KCl was only 40% greater in the 1-day-old bladders as compared to the adult. These current studies indicate that the newborn bladder responds to a variety of nonadrenergic, noncholinergic agonists to a significantly higher degree than the adult bladder, and that maturation is accompanied by substantial changes in the pharmacology of the bladder.

Developmental Aspects of Bladder Contractile Function: Evidence for an Intracellular Calcium Pool

Recent studies indicate that specific functional changes in smooth muscle accompany development and that these functional differences may relate to developmental alterations in intracellular calcium content. The possibility that neonatal bladder smooth muscle might be more permeable to calcium ions was tested using the radioligand H3 PN-200 and subsequent Scatchard analyses. No differences in either receptor density or the dissociation constants were noted in comparisons between neonatal and mature rabbit bladder smooth muscle. The sensitivity to calcium in isolated bladder smooth muscle strips exposed to high potassium was tested following calcium depletion. Calcium repletion was performed and dose response curves were generated, which showed that the neonatal strips had a significantly lower effective dose producing 50% of maximal response than their mature counterparts (1.5 versus 7.5 mM., p < 0.05). These findings are consistent with the hypothesis that intracellular binding and secondary calcium release are low in neonatal bladder smooth muscle, and that they increase with maturation. These studies are also consistent with the studies showing maturational increases in the intracellular binding and storage of calcium (sarcoplasmic reticulum), which have been reported in the developing rabbit and sheep myocardium.

Developmental Aspects of Bladder Contractile Function: Sensitivity to Extracellular Calcium

The urinary bladders of 1-day and 1-week-old rabbits generate higher intravesical pressures in response to bethanechol and field stimulation than bladders isolated from mature 8-week-old rabbits. Yet the density of cholinergic receptors in the rabbit bladder does not change with maturation (1 day to 8 weeks). In an effort to better understand the molecular mechanisms by which newborn rabbit bladders generate greater pressures than the bladders of adult rabbits, we studied the effect of maturation on the relationship between extracellular calcium and contraction. Our results showed quite clearly that (1) at physiologic concentrations of calcium (2.5 mumol/l), isolated bladder strips of 1-day- and 1-week-old rabbits contracted in response to bethanechol to 98% of their maximal tension as opposed to 68% for their 8-week-old counterparts, (2) the ED50 (for calcium) for the 1-day and 1-week bladders was 0.4 mmol/l whereas the ED50 for the adult bladder strips was 2.2 mmol/l, and (3) the neonatal bladders demonstrated a much greater sensitivity to diltiazem than the adult bladders. The contractile response to calcium of the neonatal bladders was significantly inhibited by 1 mumol/l diltiazem whereas the 8-week-old bladders showed no inhibition at this concentration. In a second series of experiments, the effect of extracellular calcium on concentration was correlated with the intracellular concentration of free calcium using the calcium fluoride FURA-2 and surface spectrofluorometry. These studies confirmed that the increased contractile response of the neonatal bladder strips to calcium or cholinergic agonists was associated with an increase in the maximal intracellular free calcium concentration.