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Biomedical subjects

H M Snyder

Publications and source records attributed to H M Snyder.

At least 55 records · Page 3Linked to original sources
PubMed1996

The long-term outcome of posterior urethral valves treated with primary valve ablation and observation.

PURPOSE: We believe that primary valve ablation with observation is the preferred management for posterior urethral valves. However, debate continues as to the role of high diversion. We examined the long-term outcome of a large series of patients treated with primary valve ablation, and compared it to the outcome of high diversion and vesicostomy. MATERIALS AND METHODS: We reviewed the records of 100 patients treated with primary valve ablation (74%), vesicostomy (13%) or high diversion (9%) before 1985. Median followup was 11.2 years. RESULTS: Overall 13% of our patients had end stage renal disease by age 15 years. Three patients initially treated with valve ablation and 3 initially treated with vesicostomy later underwent high diversion but none benefited from the secondary procedure. Four patients initially treated with valve ablation subsequently underwent vesicostomy but only 1 benefited. Bladder storage capacity was well preserved. Diurnal urinary continence developed in 46% of patients at age 10 years and only 1 remained incontinent after age 20 years. One patient with diversion who awaits transplantation had a small contracted bladder. Recent urodynamic studies in 10 cases of delayed urinary continence have not shown decreased bladder compliance or capacity. Kaplan-Meier analysis of outcomes of the different treatments indicated no statistical difference in patient age at end stage renal disease development. However, comparing the number of surgical procedures in the different treatment groups revealed a significant increase in the amount of surgery in infants with diversion. Our results were equivalent to those of the best published series, many of which strongly advocate high diversion. CONCLUSIONS: By avoiding diversion in most cases bladder function is preserved and the need for bladder augmentation is decreased.

Child↗
PubMed1996

The decompensated detrusor II: evidence for loss of sarcoplasmic reticulum function after bladder outlet obstruction in the rabbit.

PURPOSE: While 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. MATERIALS AND METHODS: Muscle 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. RESULTS: Our results demonstrate a remarkable loss of sarcoplasmic endoplasmic reticulum calcium-adenosinetriphosphatase activity in the decompensated group and a moderate loss in the compensated group. CONCLUSIONS: These 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.

Animals↗
PubMed1996

10-year experience with prenatal intervention for hydronephrosis.

PURPOSE: We evaluated clinical outcomes after attempted prenatal intervention in fetuses with hydronephrosis. MATERIALS AND METHODS: We retrospectively reviewed the histories of 10 fetuses considered for prenatal intervention between 1984 and 1993. One female and 8 male fetuses had bilateral hydroureteronephrosis and profound or progressive oligohydramnios, and 1 male fetus had massive progressive unilateral hydronephrosis. RESULTS: Shunt placement was not recommended and it was refused by the parents in 1 case each. Amniotic shunting was attempted in 8 fetuses between 22 and 28 weeks of gestation. Shunts were successfully placed with decreased hydronephrosis and increased amniotic fluid volume in 4 cases, while shunt placement was not technically possible in the remainder. Two shunts that retracted intra-abdominally at birth required laparotomy for retrieval. Postnatally all patients with shunts had compromised renal function. Of the 4 patients in whom attempts were unsuccessful 3 had mildly diminished renal function and 1 died of nonrenal causes (intraabdominal sepsis) on day 16 of life. No patient with a functioning shunt had postnatal pulmonary problems, whereas 3 without successful intervention had mild respiratory compromise. CONCLUSIONS: No definite advantage was noted in the small number of fetuses that underwent successful shunting. Successful shunt placement did not prevent renal insufficiency. The relief of oligohydraminos may benefit pulmonary function in some patients. The high technical failure and complication rates of in utero intervention should be considered before proceeding.

Female↗
PubMed1995

Use of injectable fat to obstruct the urethra in rabbits.

Bulking agents have been injected to correct urinary incontinence for at least 15 years. The injection seeks to increase bladder outlet resistance by partially obstructing the urethra and thereby reduce urinary leakage in patients with stress urinary incontinence. Although the implant is effective and requires a shorter in-hospital stay than more traditional procedures, no ideal implant substance has been discovered. To assess the effectiveness of injected fat as a bulking agent, we injected small volumes of perivesical fat into the bladder neck in New Zealand White (NZW) rabbits and tested the effect on the bladder. In eight rabbits, we harvested perivesical fat and partially closed the urethral lumen with an initial injection. A second injection 1 month later completely closed the urethral lumen. We injected six other rabbits with similar volumes of saline as controls. Two weeks after the second injection, we measured micturition frequency, bladder weight, response to electrical field stimulation, and response to bethanecol in each group. Fat implants were present at the injection site in each case 4 weeks after the first injection. Rabbits receiving fat implants had increased micturition frequency, increased bladder weight, and increased response to bethanecol and field stimulation. Previous studies have demonstrated that these changes are characteristic of mild outlet obstruction in rabbits. Injected fat can be made to close the urethra and create bladder outlet obstruction in rabbits. The short-term success of fat as a bulking agent in this experiment is encouraging and suggests the need for longer term studies.

Adipose Tissue↗
PubMed1995

Comparison of three measures of injury severity in children with traumatic brain injury.

Eighty-six traumatically brain-injured children aged 6 to 15 years who were consecutively admitted to a pediatric Level I trauma center were recruited for participation in the study. A comprehensive battery of behavioral, cognitive, communicative, social, motoric, and neurological tests was administered to the children from 12 to 36 months postinjury. The performance of three severity indices, the Glasgow Coma Scale (GCS), the ASCOT probability of survival, and the head injury component of the Anatomic Profile, was compared with respect to their association with long-term outcomes in five neurological domains, as assessed by linear regression models. The ASCOT probability of survival was correlated to test scores in all five domains. The GCS and the head injury component of the Anatomic Profile were each correlated to outcome in only one domain. The ASCOT probability of survival, which includes coded variables for the GCS, systolic blood pressure, and respiratory rates on admission, as well as a measure of multisystem anatomic injury, was the most sensitive indicator of head injury severity and was associated with outcomes beyond survival and death in this population. Probability of survival is a promising brain injury severity index that may be useful in efforts to assess new medical and rehabilitative therapies for children with traumatic brain injury.

Adolescent↗
PubMed1995

Developmental factors in the contractile response of rabbit urinary bladder: effect of anoxia and extracellular acidosis.

Previous studies have demonstrated that the mechanism of excitation contraction coupling changes with normal development in rabbit urinary bladder smooth muscle. The present study was designed to determine whether there were any differences in the effects of anoxia and extracellular acidosis in response to field stimulation, bethanechol and KCl between mature (8 weeks) and neonatal (3 days) rabbit bladder smooth muscle. Bladder smooth muscle strips from mature and neonatal New Zealand White rabbits were mounted in organ baths and bathed in oxygenated Tyrode's solution. Anoxia was produced by changing the gas mixture to 95% nitrogen/5% CO2 and the effects on contractility were determined at different times after initiation of anoxia. The extracellular acidosis was produced by decreasing the buffer's NaHCO3 concentration. We conclude that bladder smooth muscle does not exhibit an age-specific ability to counteract the effects of anoxia or acidosis as is seen in the developing rabbit myocardium. Instead it appears that the purinergic mechanisms of contraction are much more sensitive to the effects of anoxia or acidosis. Neonatal bladder smooth muscle exhibits a greater drop in contractility with anoxia or acidosis at low frequency (2 Hz) field stimulation; we attribute this to the fact that neonatal bladder smooth muscle has a greater purinergic component in its response to field stimulation. These differences in the responses to anoxia and pH reflect alternate mechanisms of pharmacologic activation, and not inherent differences in the biochemistry of the maturing smooth muscle.

Acidosis↗
PubMed1994

Ultrasound diagnosis of bladder outlet obstruction in rabbits.

One of the primary characteristics of partial outlet obstruction secondary to BPH is an increase in bladder mass commonly referred to as bladder hypertrophy. This condition has been simulated in rabbits by the partial ligation of the catheterized urethra. Ultrasonography has been utilized in both adult and pediatric urology to visualize the bladder and diagnose specific bladder disorders. The aim of the present study is to determine if ultrasonography can visualize bladder wall hypertrophy induced by obstruction. Partial outlet obstructions were created in NZW rabbits using standard methodologies, and then 5 to 7 days later, sonography was performed. The films were read by both the principal investigator and blinded investigators instructed to determine bladder wall thickness and from this predict the bladder weight. Then results were correlated with cystometrograms (CMGs) and whole bladder weights. Both the principal investigator and the blinded investigators were consistently able to distinguish obstructed from control bladders based solely on sonographic depictions of relative bladder wall thickness. In addition, the investigators were able to distinguish between low (control), medium, and high bladder weights based on sonography. The accuracy of predicting the bladder weights increased when cystosonograms were correlated with CMG studies. Thus, the degree of bladder hypertrophy can be accurately estimated by the combination of cmg and ultrasonography.

Animals↗
PubMed1994

Characterization of a fibroblast cell from the urinary bladder wall.

For the first time we report on the growth, culture, and matrix production characteristics of a cell type isolated from the lamina propria of the urinary bladder wall. A fibroblastlike cell was identified as distinct from bladder detrusor smooth muscle cells and urothelium based on morphology, growth characteristics, and immunohistochemical staining. Characterization of extracellular matrix synthesis by this cell type using 35S-methionine metabolic labeling demonstrated that these cells are capable of secreting components of the surrounding connective tissue, including several fibrillar collagens, a basement membrane collagen, and fibronectin.

Actins↗
PubMed1994

Primary dilated megaureter: long-term followup.

Previously, we reported on the changing concepts in the management of 35 neonates with primary obstructive megaureters, 25 of whom were observed without surgery for a mean of 28 months while 10 were surgically treated. We report the long-term outcome of the 25 patients who were managed without surgery. This group consists of 19 male and 6 female neonates with 19 unilateral and 6 bilateral dilated ureters. Of the patients 17 presented with an antenatal diagnosis of hydronephrosis, 2 with infection and 6 with incidental findings. None of the patients had vesicoureteral reflux. Followup serial imaging (2 or more studies per case) consisted of excretory urography in 18 of the 25 cases, diethylenetriaminepentaacetic acid renal scan in 16 and/or sonogram in 10. Mean followup was 7.3 years (range 4.8 to 12.4) for 24 patients and 1 was lost to followup after 1.5 years. Excretory urography showed improvement in urinary tract dilatation in 12 cases and stable dilatation in 6. Renal scans demonstrated expected interval increases in the glomerular filtration rate with age without any deterioration in per cent of renal function in all 16 cases. None of the patients had stones, pain or pyelonephritis. We conclude that it is safe to follow a select group of patients with primary dilated megaureters in the absence of vesicoureteral reflux. We recommend antibiotic prophylaxis and serial urinary tract imaging to confirm renal growth and preservation of renal function.

Dilatation, Pathologic↗
PubMed1994

Type III collagen decreases in normal fetal bovine bladder development.

In normal fetal bovine bladder development we have shown that compliance increases at approximately the same time that urine production first occurs. The late first trimester fetal bladders are relatively stiff with a progressive increase in bladder compliance peaking in the newborn period. From the newborn period through adulthood, we documented a relatively modest decrease in bladder compliance, which may result from the normal aging process. To account for these changes, we have used the bovine model to perform biochemical analyses of the major structural collagens that are found in the bladder (types I and III). These results show that the per cent of type III collagen decreases in the developing bladder from the end of the first trimester until the newborn period. Comparing the newborn bladder to that of a mature adult, we documented a relatively modest increase in the amount of type III collagen. We demonstrated that the ratio of type III-to-type I collagen parallels the normal compliance changes in the developing fetal and mature bovine bladder.

Aging↗
PubMed1994

Changing concepts of hypospadias curvature lead to more onlay island flap procedures.

From 1987 through 1992, 1,109 primary hypospadias operations were performed at our hospital, of which 374 (33%) were onlay island flap procedures. In contrast, from 1982 to 1987 only 66 of 657 primary hypospadias repairs (10%) were onlay island flaps. The increase in this type of repair stems from the observation that in most cases of hypospadias the urethral plate is not the cause of penile curvature. Intraoperative artificial erection after skin take down revealed that only 50 of the 374 patients (13%) still had a significant bend. After experience demonstrated that the residual bend was not due to a fibrous urethral plate, but rather to a generally mild (20 to 30 degree) corporeal disproportion, correction was achieved by dorsal tunica albuginea plications. We conclude that better healing of the onlay flap to spongiosum supported urethral plate may account for the lower fistula rate (6%) observed with the onlay island flap hypospadias repair, and even in severe cases of hypospadias the urethral plate is usually healthy and it does not require division to produce a straight penis.

Child↗
PubMed1994

The absent cryptorchid testis: surgical findings and their implications for diagnosis and etiology.

On surgical exploration for impalpable testes, there is often found nothing or a nubbin of tissue at the end of the spermatic vessels. This situation is commonly referred to as an absent testis. Controversy exists on how to establish correctly this diagnosis and the degree of investigation required. In addition, there is disagreement concerning whether an absent testis results from early torsion or endocrinopathic event. What is accepted is that the spermatic vessels are singularly important in establishing testis location. In this study, the pathological findings of 117 cases of absent testis diagnosed by surgical exploration at our hospital were reviewed. This diagnosis represented 10% of 1,225 patients explored for cryptorchidism from 1985 to 1991. Average patient age at operation was 26.8 months (range 5 months to 14 years). Of these children 78 (67%) presented with an impalpable left testis. At operation 3 patients (3%) underwent laparoscopy only, while all others had groin exploration with or without transperitoneal exposure to ensure identification of spermatic vessels. In 110 cases surgical specimens or nubbins were excised. Pathological study of these remnants revealed vas deferens in 89 cases (81%), epididymal tissue in 40 (36%) and small amounts of seminiferous tubules with germinal elements in 7 (6.4%). Only 26 specimens (24%) had sufficient vascular tissue present to be suggestive of spermatic vessels. A significant number showed the presence of calcification (35.5%) and hemosiderin (30%) deposits within the remnant. A subset of patients with absent testis possesses testicular tissue of presumed increased malignant potential. Therefore, surgical exploration with spermatic vessel identification and remnant removal is the gold standard for the diagnosis and treatment of the absent testis. The surgeon continues to be responsible for spermatic vessel identification, since the vessels may be recognized at pathological examination in less than 25% of the cases. Also, the common finding of calcification and hemosiderin lends weight to the torsion etiology over endocrinopathy for an absent testis.

Adolescent↗
PubMed1994

Normal epididymal anatomy in boys.

It is accepted that a range of epididymal anomalies exists in boys with cryptorchidism, varying from ductal patency aberrations to abnormal attachments of the epididymis to the testes or even complete absence. Despite several series characterizing these variations, there are few studies of normal controls for comparison. We document normal epididymal anatomy in boys. During an 18-month period ending in 1991, 94 boys (mean age 4.8 years, range 1 month to 18 years) underwent inguinal or scrotal exploration unrelated to cryptorchidism. Epididymal anatomy was recorded for all exposed testes. Indications for surgery included hydrocele or hernia in 85 boys, torsion in 8 and varicocele in 1. A total of 112 epididymides was examined and the configurations were recorded as type 1-head and tail attachment with a "looped" body in 94 of 112 cases (83.9%), type 2-complete attachment to the testis in 14 (12.5%), type 3-head attachment only in 3 (2.7%), type 4-tail attachment only in 0 (0%), type 5-nonfusion in 1 (0.9%) and type 6-anomalies of ductal patency in 0 (0%). These data reveal that the most common epididymal configuration in normal boys is a looped epididymis with the head and tail attached (84%) followed by complete fusion with the testes (12.5%). Other variations are rare. Absence of the epididymis was not observed.

Adolescent↗
PubMed1994

Benign cystitis in children mimicking rhabdomyosarcoma.

Seventeen (13 male, 4 female) patients, aged 13 months to 13 years, with benign cystitis had imaging findings that mimicked those of rhabdomyosarcoma. Our experience indicates that in the child with hematuria, dysuria, and frequency plus cystographic or sonographic demonstration of a bladder with reduced capacity and circumferential wall thickening or sonographic findings of isoechoic bladder wall thickening (focal, multifocal or circumferential distribution), intact mucosa, and bullous lesions should strongly suggest inflammation and not malignancy. When an inflammatory lesion is suspected, follow-up imaging should be performed in 2 weeks, which if normal will preclude biopsy.

Adolescent↗