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Biomedical subjects

R I Silver

Publications and source records attributed to R I Silver.

At least 19 recordsLinked to original sources
PubMed2001

A fishnet gantry for pediatric extracorporeal shock wave lithotripsy on the Sonolith 3000.

A new type of lithotripsy gantry composed of fishnet and bungee cords has been developed to allow proper patient positioning of infants and small children who undergo extracorporeal shock wave lithotripsy on the Sonolith 3000 lithotriptor. The materials are safe, inexpensive, easy to use, and do not interfere with shock wave delivery during a lithotripsy session. The gantry can be used for other lithotripsy machines that have a similar construction with a self-contained waterbath and a large lithotripsy table window.

Child↗
PubMed2000

The undescended testicle: diagnosis and management.

Early diagnosis and management of the undescended testicle are needed to preserve fertility and improve early detection of testicular malignancy. Physical examination of the testicle can be difficult; consultation should be considered if a normal testis cannot be definitely identified. Observation is not recommended beyond one year of age because it delays treatment, lowers the rate of surgical success and probably impairs spermatogenesis. By six months of age, patients with undescended testicles should be evaluated by a pediatric urologist or other qualified subspecialist who can assist with diagnosis and treatment. Earlier referral may be warranted for bilateral nonpalpable testes in the newborn or for any child with both hypospadias and an undescended testis. Therapy for an undescended testicle should begin between six months and two years of age and may consist of hormone or surgical treatment. The success of either form of treatment depends on the position of the testicle at diagnosis. Recent improvements in surgical technique, including laparoscopic approaches to diagnosis and treatment, hold the promise of improved outcomes. While orchiopexy may not protect patients from developing testicular malignancy, the procedure allows for earlier detection through self-examination of the testicles.

Age Factors↗
PubMed2000

A ventriculoperitoneal shunt masquerading as a paratesticular tumor.

A 3-year-old boy with hydrocephalus was observed to have a painless 2.0-cm right scrotal mass. Abdominal radiograph showed ventriculoperitoneal shunt tubing in the right scrotal sac. Removal of a detached shunt catheter and inguinal hernia repair resolved the problem.

Child, Preschool↗
PubMed2000

Decreased linear growth associated with intestinal bladder augmentation in children with bladder exstrophy.

PURPOSE: We determine if enterocystoplasty results in delayed linear growth using a case controlled study to observe the effects of intestinal bladder augmentation on growth in patients with bladder exstrophy. MATERIALS AND METHODS: A total of 50 patients who had undergone bladder augmentation for incontinence due to classic bladder exstrophy were selected from our patient database and matched for gender, age and type of exstrophy with 50 patients who had nonaugmented bladder exstrophy. Patients were then contacted and asked to permit the pediatricians to release growth charts. Once consent was obtained the charts were requested from the pediatricians, and evaluable data, defined as at least 1 height before and after augmentation, were obtained for 17 of 50 (34%) augmented and 15 of 50 (30%) nonaugmented cases. RESULTS: Mean age at surgery was 7.7 years. Delayed growth as defined by a postoperative decrease in percentile height occurred in 14 of 17 (82%) augmented cases (mean loss 15.6 percentile points). Delayed growth after age 7.7 years occurred in 5 of 15 (33%) controls but average growth for the entire group was 6.7 percentile points (p = 0. 014). Mean followup was 5.7 years (median 4.9) for the augmented group and 7.3 years (median 8.2) for the control group. CONCLUSIONS: Intestinal bladder augmentation is associated with a nearly universal decrease in percentile height. Close long-term followup of these patients and analysis of subtle metabolic alterations may provide information to help minimize or prevent growth impediment in the future.

Adolescent↗
PubMed2000

What is the etiology of hypospadias? A review of recent research.

The multi-factorial etiology of hypospadias is becoming more defined with ongoing investigation. Implicated factors include testosterone biosynthesis defects, 5 alpha-reductase type 2 mutations, androgen receptor mutations (rare), IVF (progesterone administration or endocrine abnormalities associated with infertility), and environmental agents that can disrupt the male sex hormone axis. It also seems that the incidence of hypospadias is on the rise, both in the United States and in Europe. Hypospadias is a physical manifestation that may be a consequence of numerous physiological aberrations, and our ability to understand and to potentially prevent this problem will require a significant amount of additional work. Our challenge for the future remains to identify the various etiologies, provide prenatal counseling for affected families with a history of hypospadias, and minimize or eliminate exposure to environmental agents that may contribute to this problem. It is even possible that some day we may be able to offer prenatal therapy to prevent hypospadias when the risk for this birth defect seems high. Does this sound far-fetched? Consider the modern management of a family with a child born with the adrenogenital syndrome, another endocrine derangement that can cause abnormal genital development. In this situation, dexamethasone can be administered to the mother in subsequent pregnancies to prevent fetal virilization until the sex of the fetus can be determined or adrenal enzyme mutations can be excluded. Perhaps in the future a similar approach will be taken for those families with strong risk factors for hypospadias.

Humans↗
PubMed1999

Measurement of urinary N-acetyl-beta-D-glucosaminidase to assess renal ischemia during laparoscopic operations.

BACKGROUND: Oliguria during laparoscopy is a well-documented phenomenon of unknown etiology. Experimental evidence suggests that renal perfusion is reduced during pneumoperitoneum. N-acetyl-beta-D-glucosaminidase (NAG), which is present in renal tubular cells, is released into the urine in response to tubular insults. In this study, urinary NAG was measured before and after procedures to assess for ischemic renal injury. METHODS: A total of 31 patients underwent laparoscopic procedures while 28 patients had conventional surgery. Urine was obtained first at the time of preoperative Foley catheter placement and later during the recovery room stay. NAG levels were measured and indexed to urinary creatinine. RESULTS: Operative time for the laparoscopy group was 105 min (range, 15-255); for the conventional group, it was 179 min (range, 75-385) (P < 0.05). No differences were noted between pre- and postoperative NAG levels or between the groups. There was no correlation between urinary NAG levels and operative time. CONCLUSION: Pneumoperitoneum is not associated with a change in the urinary concentration of NAG. This finding suggests that there is no significant renal tubular injury associated with laparoscopic surgery.

Acetylglucosaminidase↗
PubMed1999

5alpha-reductase type 2 mutations are present in some boys with isolated hypospadias.

PURPOSE: We determined whether 5a-reductase type 2 mutations are present in boys with isolated hypospadias. MATERIALS AND METHODS: Penile skin tissues obtained at surgery during hypospadias repair were examined for 5alpha-reductase type 2 mutations by single strand conformational polymorphism and deoxyribonucleic acid sequence analysis. Clinical data, including family history of hypospadias and preoperative position of the urethral meatus, were correlated with the genetic findings. RESULTS: Of the 81 specimens examined 7 (8.6%) involved a mutation in at least 1, 5alpha-reductase type 2 gene, while 2 patients had mutations in both alleles. The mutations identified were A49T, L113V and H231R. The A49T mutation in 5 patients was the most common (71%) and it was generally present in less severe forms of hypospadias. To our knowledge neither the A49T nor the L113V mutation has been previously reported in association with 5alpha-reductase type 2 deficiency and to date they have only been identified in cases of isolated hypospadias. Family history was negative in the 7 patients with 5a-reductase type 2 mutations but positive in 5 without mutations. CONCLUSIONS: Some boys with isolated hypospadias have a mutation in at least 1 gene for 5alpha-reductase type 2. This finding suggests that a partial deficiency of 5alpha-reductase activity and inadequate levels of dihydrotestosterone in the fetal urethra may be sufficient to cause the phenotype of hypospadias without other clinical features of 5alpha-reductase deficiency. Family history may not be reliable for determining which boys with hypospadias are likely to have such mutations.

Child↗
PubMed1999

Detection of adenocarcinoma by urinary microsatellite analysis after augmentation cystoplasty.

Augmentation cystoplasty is associated with an increased risk of bladder cancer development between 10 and 20 years after augmentation. Using microsatellite analysis, we analyzed urine obtained before surgical resection of the malignant lesion from a patient who developed invasive adenocarcinoma after augmentation cystoplasty. Loss of heterozygosity was identified in both urine and tumor samples from this patient. This observation suggests that microsatellite urine analysis may be useful as a monitoring tool for patients after augmentation cystoplasty.

Adenocarcinoma↗
PubMed1999

Staged closure of the pelvis in cloacal exstrophy: first description of a new approach.

PURPOSE: We describe a staged approach for pelvic closure in patients with cloacal exstrophy, and evaluate the technique for functional and cosmetic results. MATERIALS AND METHODS: Staged closure of the pelvis was performed in 5 patients 12 months to 14 years old with cloacal exstrophy at our institution, including some referred with a history of failed closure. The technique involves initial pelvic osteotomy followed by soft tissue and pelvic ring closure 2 to 3 weeks later. Clinical information is reviewed to assess the effectiveness of the technique. RESULTS: At a mean followup of 3.2 years (range 1 to 9) closure was successful in all 5 patients without technical problems or surgical complications, and with excellent functional and cosmetic results. CONCLUSIONS: This technique of staged pelvic closure may provide reliable initial or secondary repair in patients with cloacal exstrophy in whom 1-stage pelvic closure is unfeasible even with pelvic osteotomy.

Adolescent↗
PubMed1999

In vitro fertilization is associated with an increased risk of hypospadias.

PURPOSE: The purpose of this study was to determine if there is an increased incidence of hypospadias in male offspring conceived by in vitro fertilization (IVF). MATERIALS AND METHODS: A retrospective institutional chart review from 1988 to 1992 and data from the Maryland Birth Defects Registry were statistically analyzed to assess the risk of hypospadias with IVF. RESULTS: The data for the 5-year period indicated a 5-fold increased risk of hypospadias after IVF, with an incidence of approximately 1.5% in the IVF group and 0.3% in the control group. The only recognized difference between the groups was maternal progesterone administration in the IVF group but the cause of the increased risk of hypospadias was unknown. The distribution of hypospadias severity was similar in both groups. CONCLUSIONS: Male newborns conceived by IVF have a 5-fold increased risk of hypospadias, which may be related to maternal progesterone administration, or other maternal or fetal endocrine abnormalities that may or may not be related to infertility. Health care providers should be aware of this risk so that they can properly counsel infertile couples seeking assisted reproduction by IVF technology.

Female↗
PubMed1998

Idiopathic anterior urethritis in prepubertal and pubertal boys: pathology and clues to etiology.

OBJECTIVES: Records were reviewed to examine the common features of boys with noninfectious anterior urethritis, and to describe the underlying pathology. METHODS: Five cases of anterior urethritis with features typical of this syndrome are reviewed. RESULTS: These cases demonstrate the typical appearance and in 1 case the pathologic diagnosis of squamous metaplasia of the bulbar urethra. CONCLUSIONS: Prepubertal urethrorrhagia is associated with squamous metaplasia of the urethra. The tendency to stricture formation may precede instrumentation of the urinary tract.

Adolescent↗
PubMed1998

A quantitative histologic analysis of collagen subtypes: the primary obstructed and refluxing megaureter of childhood.

OBJECTIVES: To analyze and identify collagen subtypes in the primary obstructed and refluxing megaureter of childhood. METHODS: Anticollagen monoclonal antibodies to collagen types I, III, and IV were used in control ureters (n = 4), obstructed (n = 7), and refluxing (n = 13) megaureters. Additionally, all were stained with Masson's trichrome to further define the extracellular matrix. After staining and serial sectioning, representative ureteral sections, focusing on the muscularis and lamina propria regions, were digitized and analyzed with a color image analysis system. RESULTS: Immunohistochemical studies demonstrated increases in collagen types I and III for both obstructed and refluxing megaureters compared with controls (P <0.05). Collagen type IV was not detected in statistically significant amounts in any ureter. In control ureters most was type I (83% +/- 9%) collagen. Obstructed megaureters produced similar results with virtually all collagen being type I (84% +/- 26%) with very little type III collagen present, 5.3% +/- 3%. Refluxing megaureters contained only 55% +/- 15% type I collagen. However, there was an increase in type III collagen (16% +/- 4%) versus (4.5% +/- 2%) in controls (P <0.05). CONCLUSIONS: These data suggest that the greater contribution of type III collagen may play a role in the pathophysiology of refluxing megaureters. Because type III collagen is a less distensible fiber, it may cause an intrinsically stiffer ureter and play a role in the lower surgical success in the reimplantation of refluxing megaureters.

Antibodies, Monoclonal↗
PubMed1998

Multi-institutional study of testicular microlithiasis in childhood: a benign or premalignant condition?

PURPOSE: Testicular microlithiasis, a rare ultrasonographic diagnosis in children, has been shown to coexist in benign and malignant conditions. The natural history of incidentally discovered testicular microlithiasis has not been well defined in the pediatric population. The concern that testicular microlithiasis may be a premalignant condition has been raised. Reports indicate as much as a 45% association of germ cell tumors with testicular microlithiasis at the time of tumor diagnosis and there have been 4 cases of interval testicular tumor development associated with preexisting testicular microlithiasis. To address this issue we performed a multi-institutional study to evaluate children with incidentally diagnosed testicular microlithiasis. MATERIALS AND METHODS: Data on 26 patients with a mean age of 12.3 years at presentation with incidentally discovered testicular microlithiasis were collected from 7 institutions. Presenting scrotal conditions were reviewed. Two children with a previous testicular malignancy were excluded from study. RESULTS: Followup ranged from 1 month to 7 years (mean 27.6 months). Testicular biopsy and tumor marker (alpha-fetoprotein and beta-human chorionic gonadotropin) determinations were performed in 9 and 15 patients, respectively. To date no testicular tumor has developed during clinical followup. CONCLUSIONS: Our multi-institutional study has not yet shown a trend toward the malignant degeneration of incidentally diagnosed testicular microlithiasis in children. However, we still advocate close surveillance of patients with testicular microlithiasis, such as yearly testicular ultrasound, physical examination, and judicious tumor marker determinations. We propose that a registry be started to follow prospectively patients with testicular microlithiasis to define its significance better.

Adolescent↗
PubMed1997

Prostate-specific antigen in men born with bladder exstrophy.

OBJECTIVES: To determine serum levels of prostate-specific antigen (PSA) in men born with bladder exstrophy and to investigate the clinical utility of this test in the bladder exstrophy population. METHODS: Ten men aged 19 to 45 years with a history of bladder exstrophy underwent digital rectal examination and free and total serum PSA determinations. Immunohistochemistry for PSA and prostate-specific acid phosphatase (PSAP) was performed on archival prostate tissue from 1 man with bladder exstrophy. RESULTS: Free and total serum PSA levels for all patients were measurable and below the upper limit for established age-specific reference ranges for normal men. Both PSA and PSAP were detectable by immunohistochemistry in prostate epithelial cells of a man with bladder exstrophy. CONCLUSIONS: Men born with bladder exstrophy have detectable serum PSA levels. However, because prostate cancer in men with bladder exstrophy has not been reported, whether PSA will have a clinical role as a serum tumor marker for prostate cancer in this population remains to be determined. If so, the PSA reference range for men with the exstrophy condition will need to be defined. Because prostate histology in men with exstrophy resembles that of normal men, careful clinical monitoring for benign and malignant tumors should not be overlooked in this particular population.

Adult↗
PubMed1997

Spinal abnormalities in classic bladder exstrophy.

OBJECTIVE: To determine the frequency and clinical sequelae of significant spinal malformations in children born with classic bladder exstrophy. PATIENTS AND METHODS: All patients evaluated or treated for classic bladder exstrophy at this institution were reviewed retrospectively. Radiographs or reports pertinent to the spine were retrieved and reviewed with a paediatric radiologist and all vertebral abnormalities categorized. Clinical charts of those with spinal anomalies were reviewed to determine any clinical neurological disorders associated with the radiographic findings. RESULTS: Of 423 patients with classic bladder exstrophy who were identified, 299 had radiographs or reports available for adequate review. Of these, 34 (11%) normal variants, e.g. spina bifida occulta and lumbarization or sacralization of vertebrae, were identified. Abnormalities of spinal curvature were identified in eight patients (2.7%), all with uncomplicated scoliosis. Spinal dysraphism was diagnosed in 12 patients (4%) and included myelomeningocele, lipomeningocele, scimitar sacrum, posterior laminal defects in two or more vertebrae, vertebral fusion and hemivertebrae. The one patient with myelomeningocele had clinical neurological dysfunction, giving an overall incidence of 0.3%. CONCLUSIONS: Spinal anomalies, excluding normal variants, occur in children born with classic bladder exstrophy at a rate of about 6.7%. The incidence of this association is much less than that for cloacal exstrophy. Although rare, neurological dysfunction can occur in the case of spinal dysraphism. Paediatric urologists and neurologists should be aware of this significant difference between patients with classic bladder and cloacal exstrophy to properly diagnose, evaluate and treat the attendant neurological problems.

Adolescent↗
PubMed1997

Immunohistochemical description of nitric oxide synthase isoforms in human clitoris.

PURPOSE: Our aim was to identify and localize nitric oxide synthase isoforms in the human clitoris in support of the hypothesis that nitric oxide mediates erectile function in this organ. MATERIALS AND METHODS: Nitric oxide synthase immunohistochemistry studies specific for neuronal, inducible and endothelial isoforms of the enzyme were performed on human clitoral tissue obtained from 4 patients (3 with female pseudohermaphroditism and 1 with true hermaphroditism) at feminizing genitoplasty and from 1 phenotypically normal woman at autopsy. RESULTS: Neuronal nitric oxide synthase immunoreactivity was detected in nerve bundles and fibers coursing within the glans clitoris and corpora cavernosa of the clitoris, predominating in the latter tissue. Specific inducible nitric oxide synthase immunoreactivity was not identified. Endothelial nitric oxide synthase immunoreactivity was detected in vascular and sinusoidal endothelium of these tissues with a predominance in the glans clitoris. CONCLUSIONS: The presence and anatomical localizations of nitric oxide synthase isoforms in the human clitoris indicate that nitric oxide is generated in this organ. These data suggest that nitric oxide may be involved in the erectile physiology of the clitoris as a modulator of clitoral smooth muscle activity. Functional studies are required to support this hypothesis.

Child↗