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Biomedical subjects

H M Snyder

Publications and source records attributed to H M Snyder.

At least 73 records · Page 4Linked to original sources
PubMed1993

Bilateral undescended testes.

The management of boys with undescended testes appears to be an increasingly common problem. While Scorer (1964) [11] reported an incidence of 0.8% of undescended testes in boys of one year of age, a recent survey (Radcliffe Hospital, Oxford, 1986) [18] suggests the incidence has risen to as high as 1.6%. While the etiology may be varied, it is quite clear that many cases represent disturbances of the hypothalamic-pituitary-gonadal axis and may represent a forme fruste of hypogonadotropic hypogonadism [3]. Bilateral undescended testes might logically appear to represent the worst end of such an endocrinopathy. Indeed, a review of the experience at The Children's Hospital of Philadelphia [12] of boys with bilateral undescended testes indicated a greater number of CNS abnormalities (P = 0.0000) than in boys with unilateral undescended testes (Table 1). Also consistent with bilateral cryptorchid testes representing the most severe end of the spectrum was the reported findings from that study that bilateral undescended testes also exhibit a significantly greater number of associated G-U anomalies (P = 0.0004).

Biopsy↗
PubMed1993

Nonoperative management of blunt pediatric major renal trauma.

Although algorithms exist for the management of renal trauma in adults, guidelines have not been established in children. Of 1,175 patients entered into our Trauma Registry between 1987 and 1991, 61 (5.2%) presented with gross or microscopic hematuria. Eight of the 58 patients (13.8%) who had blunt abdominal trauma had major renal injuries. Gross hematuria (n = 10) was a significant predictor of major renal injury (n = 5) (p < 0.001). All 3 patients with microscopic hematuria and a major renal injury also had evidence of multisystem trauma. Admission blood pressure, hemoglobin, and trauma score were not predictors of major renal trauma. All cases were managed nonoperatively except for 1 patient who required a partial nephrectomy for continued hemorrhage. These data suggest that hematuria of any degree should be evaluated in the pediatric population, since major injuries can occur with even microscopic hematuria or in the absence of shock. Nonoperative management in this series resulted in no morbidity or delayed complications and suggests that surgical exploration be reserved for ongoing bleeding.

Adolescent↗
PubMed1993

Congenital penile curvature (chordee without hypospadias).

We treated 30 patients aged six months to nine years with congenital penile curvature from 1988 to 1993. Twenty-four patients appeared to have a primary curvature with normal corpus spongiosum. In 12 of these 24 patients dissecting skin and dartos fascia were adequate to straighten the penis. In the other 12 patients, artificial erection demonstrated a varied degree of convexity of the penis after the skin and dartos fascia release, implying a disproportion of the corpora cavernosa bodies. We corrected this deformity using dorsal tumica albuginea plications (TAP). The remaining 6 patients presented with a primary curvature and hypoplastic urethra. In 5 of these patients we divided the hypoplastic midportion of the urethra leaving the meatus naturally on the glans and replaced the midurethral segment using a tubularized island flap. Of these 5 patients 2 required TAP for penile straightening. The final patient with a hypoplastic urethra was managed by preserving the urethral plate and applying an only island flap urethroplasty. Complications were one fistula and two mild ventral penile curvatures, presently not severe enough for reoperation (mean follow-up 2.6 years). We present a systematic approach for the repair of congenital penile curvature using intraoperative artificial erection, TAP, and the island flap urethroplasty when needed.

Algorithms↗
PubMed1993

Biochemical characterization and quantitation of the collagenous components of urethral stricture tissue.

The collagenous composition of normal and strictured human urethral tissue was analyzed qualitatively by immunohistochemistry and quantitatively by 2-dimensional gel electrophoresis of cyanogen bromide digested tissue. Histological comparison of the normal and strictured urethral tissue showed that the normal urethral spongiosum was replaced by densely packed connective tissue fibers interspersed with fibroblasts in the strictured tissue. The immunohistochemical analysis of urethral tissue identified the presence of types I and III collagen fibers in normal spongiosum and in the connective tissue scar of strictured tissue. Estimation of the collagen type III:I ratio using scanning densitometry revealed a CB5:CB8 peptide ratio of 0.357 +/- 0.058 in the normal tissue, while the urethral stricture tissue had a CB5:CB8 ratio of 0.203 +/- 0.079 (p = 0.010). Total collagen content, as determined by hydroxyproline analysis, revealed no statistically significant differences between control and strictured tissue. Therefore, the normal urethral spongiosum was comprised of 75.1% type I collagen and 24.9% type III collagen. In contrast, the type I collagen in urethral stricture tissue was increased (83.9%), with a corresponding decrease in type III collagen (16.1%). This alteration in the ratio of collagen type III:I may explain the fibrotic noncompliant nature of urethral stricture scar tissue.

Adolescent↗
PubMed1993

Culture of urethral fibroblasts: cell morphology, proliferation and extracellular matrix synthesis.

The in vitro morphology and proliferative activity of urethral fibroblasts were characterized from primary isolates of fetal bovine urethral spongiosum. Cells were identified as fibroblastic based on their spindle-shaped morphology and lack of expression of phenotypic markers characteristic of either urethral smooth muscle or epithelial cells. Urethral fibroblasts proliferated at a steady rate and did not exhibit contact-inhibition of growth in a culture medium of Medium 199 supplemented with 10% newborn calf serum. Both immunohistochemistry and metabolic labeling analyses of extracellular matrix synthesis demonstrated the presence of collagen types I and III, and fibronectin. Quantitation of the collagenous components of the cell medium revealed that urethral fibroblasts synthesize 85% type I collagen, 14% type III collagen and < 1% type V collagen. In contrast, the urethral fibroblast cell layer matrix consisted of 98% type I collagen, < 1% type III and < 1% type V collagen.

Animals↗
PubMed1993

Bladder smooth muscle cells in culture: I. Identification and characterization.

This report documents the growth and culture characteristics of human and fetal bovine bladder smooth muscle cells in vitro. Bladder smooth muscle cell strains have been identified by their spindle shaped morphology, noncontact inhibited growth characteristics and the expression of smooth muscle cell specific alpha-actin. Extracellular matrix protein biosynthesis by these cells in vitro has been characterized by metabolic labeling of proteins with [14C] radiolabeled proline and analysis by SDS gel electrophoresis. These studies demonstrate that bladder smooth muscle cells synthesize predominantly types I and III collagen, and fibronectin. In addition type III collagen exists in both a partially processed (pN alpha 1[III]) form and processed form. Complementary immunohistochemical studies show localization of type I, III, and IV collagens, and fibronectin to bladder smooth muscle cell extracellular matrix. We conclude that both fetal bovine and human smooth muscle bladder cells are capable of secreting the classic components of the surrounding connective tissue.

Animals↗
PubMed1993

Endoscopic incision of ureteroceles: intravesical versus ectopic.

A total of 51 children, mostly less than 2 years old, underwent endoscopic incision of ureteroceles as a primary form of treatment. In 73% no further surgery was required. Of the patients 19 were diagnosed by prenatal ultrasound, with a urinary tract infection the usual presenting symptom in the remainder. Of 27 intravesical cases endoscopic incision resulted in decompression of the ureterocele in 93%, with preservation of upper pole function in 96%, and secondary surgical procedures were required in 7%. Reflux was created in 18% and it persisted in 2 of 4 patients. Of 24 cases of ectopic (extravesical) ureteroceles incision resulted in decompression in 75%, with upper pole function preserved in 50%. Reflux was created in 47% and a secondary surgical procedure was performed in 50%. Preservation of upper pole function was significantly better for intravesical versus ectopic ureteroceles (p < 0.01), and the requirement for secondary surgical procedure was greater with ectopic ureteroceles (p < 0.01). Three patients had intermittent bladder outlet obstruction following the incision and required further surgery. The 2 different techniques for incision of intravesical and ectopic ureteroceles are described. The role of endoscopic incision in the overall management of ureteroceles is confirmed by this review, and the need for partial nephroureterectomy may diminish.

Adolescent↗
PubMed1993

Anatomical, morphological and volumetric analysis: a review of 759 cases of testicular maldescent.

Undescended testis is the most frequent disorder of male sexual differentiation affecting 0.8% of all boys by age 1 year. Anatomical and descriptive features of undescended testis lack standardization, and often do not reflect intraoperative findings. We review a large cohort of patients treated for undescended testis and analyze anatomical, morphological and volumetric findings at orchiopexy. Of 759 patients 1 month to 9 years old entered into the study between 1985 and 1990 at our hospital 55% underwent surgery between ages 8 months and 4 years, 15.5% had bilateral undescended testis and 27.6% had a nonpalpable gonad. Preoperative physical findings correlated poorly with intraoperative observation with respect to testicular position. An ectopic gonad was diagnosed in 15% of the patients, most of whom had a patent processus vaginalis. Gubernacular attachment was in the scrotum in only a third of all cases studied. Undescended testes were softer and smaller than the contralateral gonad in the majority of cases. To our knowledge ours is the first study to correlate preoperative and intraoperative findings in cases of undescended testis. New anatomical as well as morphological and volumetric data are provided.

Age Factors↗
PubMed1993

A surgical approach to reoperative orchiopexy.

While techniques for initial orchiopexy are well known, descriptions of a surgical approach to the more difficult reoperative case are scarce. We describe 25 patients undergoing reoperative orchiopexy following prior herniorrhaphy, hydrocelectomy or attempted orchiopexy. A technique of en bloc spermatic cord mobilization from an inferior approach is detailed. This approach is designed to minimize the potential for spermatic cord injury during reoperation, and has proved to be safe and reliable.

Child↗
PubMed1993

Vesicoureteral reflux and reflux nephropathy in children.

Vesicoureteral reflux is seen in up to one half of all children with urinary tract infections and reflux nephropathy is potentially the leading reversible cause of end-stage renal disease in children and adults. Recent studies still leave some doubt to the pathogenesis of reflux nephropathy. In 1992, the International Reflux Study in Children published data on the 5-year follow-up of children with high-grade reflux showing no clear advantage toward either surgical or medical management (although new surgical techniques may prove beneficial). A need to identify children with dysfunctional voiding exists. Appropriate, preferably noninvasive, studies should be employed to identify children at risk including those with antenatally diagnosed hydronephrosis and siblings of children with documented reflux.

Child↗
PubMed1993

Histologic maldevelopment of unilaterally cryptorchid testes and their descended partners.

The pathogenesis of the increased incidence of subfertility in cryptorchidism remains controversial, and the concept that the prepubertal testis is a quiescent organ continues to be held by some. Histomorphometric analyses including total and differential germ cell counts and Leydig counts were performed on semithin sections of biopsies from 459 unilateral undescended testes and 356 of their contralateral descended partners in order to further investigate these two issues. The results demonstrate reduced numbers of Leydig cells, delayed disappearance of gonocytes, delayed appearance of adult dark spermatogonia, failure of primary spermatocytes to appear, and reduced total germ cell counts in the undescended testis. These findings support the hypothesis that understimulation of the testis leads to reduced numbers of Leydig cells which leads to delayed and defective maturation of germ cells and reduced total germ cell counts which underlie the increased risk of subfertility in cryptorchidism. The appearance of adult dark spermatogonia in the first year of life and the onset of meiosis at three years of life in the contralateral descended testes contradicts the view that the prepubertal testis is quiescent. Complete evaluation of prepubertal testicular biopsies should include total and differential germ cell counts and Leydig cell counts.

Biopsy↗
PubMed1992

Evolution in the management of infant pyeloplasty.

Improving diagnostic modalities, evolving concepts regarding perinatal renal physiology, and advances in surgical technique have contributed to an evolution in the management of infant pyeloplasties. Currently, the majority of patients present with a prenatal diagnosis of ureteropelvic junction obstruction and do not require surgical intervention prior to 4 weeks of age. Postnatal ultrasound, voiding cystourethrography, and nuclear renography complete the diagnostic evaluation, with intravenous urography and retrograde pyelography being unnecessary in the majority of infants. A decreasing incidence of complications and a shortening of hospital stay has been documented. We presently prefer a dismembered, nonintubated technique performed through a dorsal lumbotomy approach.

Clinical Protocols↗
PubMed1992

The predictive value of ultrasonography in evaluation of infants with posterior urethral valves.

Between 1981 and 1989, 28 infants less than 6 months old with posterior urethral valves underwent ultrasound evaluation as part of the initial evaluation at our hospital. The single ultrasound feature that correlated with subsequent renal function was the status of corticomedullary differentiation. The presence of corticomedullary junctions in at least 1 kidney in 17 infants was always associated with a serum creatinine level of 0.8 mg./dl. or less in long-term followup. Of 11 patients with absent corticomedullary differentiation 7 had eventual creatinine levels of greater than 0.8 mg./dl. with 5 of them suffering clinically significant renal insufficiency. An association between vesicoureteral reflux and absent corticomedullary junctions was also found.

Follow-Up Studies↗
PubMed1992

Is lamina propria matrix responsible for normal bladder compliance?

Immunohistochemistry using monoclonal and polyclonal antibodies to extracellular matrix proteins is a highly sensitive tool for the characterization of matrix components. For the first time in the normal and noncompliant human bladder we have used antibodies to collagen types I, III and IV, and elastin to provide morphological correlation with mechanical properties noted clinically. In the normal bladder elastin and collagen types I and III showed intense localization in the lamina propria with modest localization in the detrusor layer. In contrast, lamina propria staining in the noncompliant bladder was essentially unchanged, while there was intense localization within the detrusor layer. Significantly, this intense localization consisted of collagen type III and elastin with little increase in type I. Type IV collagen is associated with basement membranes and individual smooth muscle cells, and shows commensurate increase in specimens with muscle hypertrophy and/or hyperplasia. These observations suggest that in the normal bladder the lamina propria may be a major structural capacitance layer with the smooth muscle covering it. The collagen fibers of the lamina propria may gradually unfold during filling, thus, accounting for normal compliance while in the noncompliant bladder the capacitance layer shifts outward to the infiltrated smooth muscle, thus, preventing the normal expansion of the lamina propria. The smooth muscle infiltration consists of a deposition of collagen type III and elastin with little increase of collagen type I, and it results in a loss of compliance. The pattern of localization would suggest that the smooth muscle is responsible for this accumulation.

Adolescent↗
PubMed1992

Lithogenic properties of enterocystoplasty.

Calculi formed in 26 of 87 patients (30%) following augmentation enterocystoplasty, of which 23 formed within the reservoir, at a mean interval of 25 months postoperatively. The calculi were composed principally of triple phosphates suggesting an important etiological role of bacteriuria and the urease reaction. Open cystolithotomy was the most successful means of removing the calculi.

Humans↗
PubMed1992

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.

Adaptation, Physiological↗