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Biomedical subjects

B A Kogan

Publications and source records attributed to B A Kogan.

At least 19 recordsLinked to original sources
PubMed2001

Placement of artificial urinary sphincter in children and simultaneous gastrocystoplasty.

PURPOSE: Previous studies have described placement of an artificial urinary sphincter and simultaneous augmentation cystoplasty with a segment of bowel. Conclusions from these studies indicated that infection rates were higher and a staged approach should be undertaken. Others have suggested that concurrent urinary reconstruction with stomach and sphincter placement can be performed safely. Results comparing infection rates of simultaneous sphincter placement and gastrocystoplasty versus staged sphincter placement and augmentation cystoplasty using a segment of ileum or stomach versus sphincter placement alone in a pediatric population have not been previously described to our knowledge. We reviewed these various groups of patients to determine if the difference in infectious complications were clinically and statistically significant. MATERIALS AND METHODS: A retrospective review of medical records from 1986 to 1999 identified 28 pediatric patients (age 18 years or less) who had undergone placement of an AS800dagger artificial urinary sphincter. Data points were collected focusing on etiology of the neurogenic bladder, age at time of surgery, types of surgery performed, length of followup and complication rates. RESULTS: Complete data were available for 27 of the 28 patients. Neurogenic bladder was secondary to myelomeningocele in 25 cases, transverse myelitis in 1 and spinal cord injury in 2. Mean patient age at surgery was 12.7 years (range 6.1 to 18.2) and mean followup was 4.3 years (range 1 month to 13 years). Simultaneous gastrocystoplasty was performed in 7 cases (group 1), staged sphincter placement followed by augmentation cystoplasty with a segment of ileum or stomach was done in 8 (group 2) and 12 did not require bladder augmentation (group 3). Urethral device erosion requiring explantation was the most common complication, occurring in 3 patients in group 1 and 2 in group 3 (p = 0.101). Mean time to erosion was 22.1 months (range 2 to 46.4). Previous surgery (bladder neck or hernia repair) was a common factor in each group with complications. Urine cultures and culture of the explanted device were positive in 2 patients in group 1. CONCLUSIONS: Simultaneous placement of artificial urinary sphincter at the time of gastrocystoplasty can be performed in carefully selected patients, although those undergoing staged procedures did well without complications. Prior bladder neck surgery seems to be a significant risk for infection. A staged approach to lower urinary tract reconstruction would be more advantageous due to the absence of infection and erosion in those undergoing staged sphincter placement and augmentation cystoplasty.

Adolescent↗
PubMed2001

Increased blood flow after catheterization and drainage in the chronically obstructed rabbit urinary bladder.

OBJECTIVES: To determine the effect of drainage on rabbit bladder blood flow after 4 weeks of partial outlet obstruction. Previous studies have shown that catheterization and drainage of the urinary bladder in control rabbits resulted in a significant nitric oxide-induced increase of blood flow to the bladder. It was also shown that 4 weeks' partial outlet obstruction caused a significant decrease in blood flow to the bladder. METHODS: Male New Zealand White rabbits underwent partial outlet obstruction by standard methods. After 4 weeks, the blood flow to the bladder muscle and mucosa was determined by a microsphere technique. Within 1 to 2 minutes after transurethral catheterization and complete drainage of the bladder, the blood flow was again determined. Unobstructed animals served as controls. Four other control animals underwent a repetitive blood flow study during 10 minutes to determine the time frame of blood flow changes after drainage. Blood flow was also measured in 2 control rabbits after transurethral catheterization without drainage and in 2 control rabbits after drainage by suprapubic puncture. To exclude the possibility that increased intravesical pressure alters the blood flow measurements, the relationship between the intravesical volume and the bladder pressure was examined in the obstructed rabbits. RESULTS: After drainage of the bladder, the blood flow to the bladder muscle increased 4.5-fold in the decompensated obstructed group (bladder weights greater than 15 g) and 2.5-fold in the compensated animals (bladder weights less than 5 g) and control animals. Blood flow to the mucosa followed the same pattern but without reaching significance. Blood flow returned to near baseline values within 5 minutes. Catheterization without drainage did not alter the blood flow. In contrast, drainage by puncture increased the blood flow significantly. Higher intravesical volumes increased the intravesical pressure slightly, but after opening the abdominal fascia, the intravesical pressure did not change with increasing volumes. CONCLUSIONS: Although the previously shown decreased blood flow to the bladder smooth muscle may be an etiologic factor in bladder contractile dysfunction secondary to partial outlet obstruction, the bladder does have the ability to increase the blood flow after drainage. This ability could be a compensatory and possibly protective mechanism after outlet obstruction.

Animals↗
PubMed2001

Magnetic resonance imaging in the evaluation of congenital anomalies of the external genitalia.

OBJECTIVES: To assess the value of magnetic resonance imaging (MRI) in the anatomic evaluation and management planning of complex congenital genitourinary anomalies. METHODS: Multiplanar T(1) and T(2)-weighted MR images were obtained in 6 pediatric patients with congenital genitourinary anomalies, including aphallia, diphallia, ectopic scrotum, and epispadias. The imaging studies were read by experienced radiologists and discussed with the urologic surgeons in a multidisciplinary conference. RESULTS: Each congenital anomaly was demonstrated in detail by MRI. The MR images of penile agenesis showed hypoplastic corpora cavernosa and a vestigial bulb. In patients with penile duplication, MRI was able to delineate the course of each corporal body and the varying degree of thickness of the tunica albuginea. For the patient with scrotal ectopia, detailed MR images excluded both the possibility of urethral and corporal duplications and the presence of viable testes in the ectopic scrotum. In the case of epispadias, MRI illustrated the precise spatial relationship between the erectile bodies and urethra. Additionally, MRI identified related aberrant pelvic organs and provided images of the external genital structures. CONCLUSIONS: MRI, by rendering excellent anatomic interpretation of complex genital anomalies and associated abnormal pelvic tissues, assists surgeons in conceptualizing the anomalous structures and contributes to their formulation of management approaches.

Adult↗
PubMed2001

Aspirin treatment improves bladder function after outlet obstruction in rabbits.

OBJECTIVES: To examine whether bladder smooth muscle dysfunction after outlet obstruction could be altered by treatment with aspirin. Long-term outlet obstruction causes contractile and metabolic dysfunction of the bladder in vivo and in vitro. The evidence is growing that a decrease in bladder perfusion is an important cause of this phenomenon. The platelet aggregation inhibitor, acetylsalicylic acid (aspirin), has been used to improve perfusion of the heart for decades. METHODS: Ten male New Zealand white rabbits were obstructed for 4 weeks. Five rabbits received no further treatment (Obs), and 5 rabbits received 2 mg/kg/day aspirin (Obs+aspirin), administered by an osmotic pump implanted subcutaneously 1 week before the surgical obstruction. The bleeding time was measured to confirm the effectiveness of the aspirin treatment. Three different control groups were created: sham-operated rabbits, unobstructed rabbits with pumps containing DMSO (vehicle), and unobstructed rabbits with pumps containing aspirin. The contractile responses of bladder strips to field stimulation, adenosine triphosphate, carbachol, and KCl were determined. A section of each detrusor tissue was fixed in formalin and used to determine the smooth muscle and collagen (connective tissue) volume fraction. RESULTS: No differences were found in the bladder weights or responses to stimuli in the different control groups, which were therefore combined. Partial bladder outlet obstruction caused significant increases in the bladder weight of the obstructed animals (Obs+aspirin, 10.15 +/- 0.87 g; Obs, 10.17 +/- 0.88 g; and controls, 2.87 +/- 0.21 g). The aspirin treatment increased the bleeding time from 1.7 +/- 0.3 minutes to 3.3 +/- 0.1 minutes. The responses to field stimulation were significantly reduced in all of the obstructed rabbits. However, the responses of the bladder strips from the Obs rabbits to field stimulation were impaired to a significantly greater degree than were those from the Obs+aspirin rabbits. The response to 32-Hz stimulation was reduced by 86% in the Obs group but by only 64% in the Obs+aspirin group. The responses to carbachol were significantly reduced by 62% in the strips from the Obs rabbits, but the responses of the strips from the Obs+aspirin rabbits were similar to the responses of the strips from the controls. The responses to KCl and adenosine triphosphate were reduced, although they just failed to achieve statistical significance using Bonferroni's analysis. The ratio of smooth muscle and connective tissue shifted slightly toward smooth muscle after 4 weeks of obstruction, but no difference was found with or without aspirin treatment. CONCLUSIONS: Low-dose aspirin has a small but significant protective effect on the contractile dysfunction induced by bladder outlet obstruction in rabbits, although the increase in bladder mass was not altered. Bladders of the same weight showed improved responses to all forms of stimulation after pretreatment with aspirin. Already used by millions of patients with heart diseases, aspirin could be a useful protection against contractile dysfunction of the obstructed bladder.

Animals↗
PubMed2001

Effect of chronic bladder outlet obstruction on blood flow of the rabbit bladder.

PURPOSE: Previous studies have shown that the initial reaction of the rabbit bladder to partial bladder outlet obstruction is increased blood flow at day 1 and a return to baseline blood flow at 1 week. Mucosal and muscle blood flow followed this pattern but mucosal blood flow was always 4 to 5-fold greater. In this study we examined the effect of 4 weeks of outlet obstruction on bladder blood flow and correlated it with the severity of bladder contractile dysfunction. MATERIALS AND METHODS: A total of 14 male New Zealand White rabbits underwent partial outlet obstruction creation by standard methods. After 4 weeks the rabbits were anesthetized, and blood flow to the muscle and mucosa was determined by standard fluorescent microsphere technique. A section of each detrusor was used for in vitro contractility studies. Contractile responses to field stimulation, carbachol and potassium chloride were determined. A section of each detrusor tissue was fixed in formalin and used to determine the smooth muscle volume fraction. RESULTS: Four weeks of partial bladder outlet obstruction caused a significant and variable increase in bladder weight and a decrease in blood flow to bladder muscle without changes in the blood flow to mucosa. There was a clear correlation between the severity of contractile dysfunction, bladder weight and the magnitude of the decrease in blood flow in muscle. The smooth muscle volume fraction remained stable at approximately 40%. CONCLUSIONS: Bladder decompensation was associated with decreased blood flow to bladder smooth muscle. Because compensated obstructed bladders with relatively normal contractile function are also hypertrophied but have normal blood flow, decreased blood flow in decompensated bladders is not simply a response to bladder hypertrophy. From this study we hypothesize that decreased blood flow to bladder smooth muscle is an etiological factor in bladder contractile dysfunction (bladder decompensation) secondary to partial outlet obstruction.

Animals↗
PubMed2001

The response of fetal sheep bladder tissue to partial outlet obstruction.

PURPOSE: We characterized the response of fetal ovine bladder strips to stimulated contraction and relaxation, and compared this response to that of strips from the pregnant mother and those obtained after a short duration of fetal bladder outlet obstruction. MATERIALS AND METHODS: Sham surgery or bladder obstruction was performed in fetal sheep at 90 days of gestation (term 147 days). Bladder tissue was obtained 3 and 5 days later. Isolated strips of full-thickness bladders from fetuses and pregnant females were mounted individually in Tyrode's solution containing glucose. The strips were subjected to electrical field stimulation. Alternate strips were stimulated by adding carbachol, adenosine triphosphate and KCl. Each strip stimulated by carbachol also underwent field stimulation in the presence of carbachol. Relaxation was also tested using isoproterenol and nitroprusside. RESULTS: The response of isolated strips to field stimulation showed phasic contraction or biphasic response, consisting of initial phasic contraction followed by phasic relaxation and a return to control tension after the end of stimulation. In fetal bladder strips field stimulation at all frequencies after carbachol stimulation produced phasic relaxation or a biphasic response with an initial relaxation phase followed by phasic contraction. This field stimulated relaxant response was not present in adult female bladder strips. In addition, field stimulation stimulated relaxation was completely eliminated by pretreatment with N-nitro-L-arginine-methyl ester, indicating that relaxation was nitric oxide mediated. The fetal responses to all forms of stimulation and relaxation were significantly greater than those of pregnant females. After 5 days or greater of obstruction the responses to field stimulation were reduced significantly. In contrast, there were no significant differences in contractile responses to adenosine triphosphate, carbachol or KCl, or the relaxant response to field stimulation after obstruction. However, there was a significant reduction in relaxant responses to isoproterenol and nitroprusside. CONCLUSIONS: In mid gestation sheep fetus contractile responses to field stimulation, adenosine triphosphate, carbachol and isoproterenol are well developed. The fetal ovine bladder shows a strong neuronal nitric oxide response that is not present in the pregnant mother and is maintained after short-term obstruction.

Animals↗
PubMed2000

Absorption of oxybutynin from vaginal inserts: drug blood levels and the response of the rabbit bladder.

OBJECTIVES: Oxybutynin has been used for treatment of urge urinary incontinence for more than 20 years. However, one of the major problems with its use is uncomfortable anticholinergic side effects that can lead to discontinuation of treatment. Alternative forms of drug administration may reduce side effects and thus improve patient compliance. METHODS: A cylinder-shaped, curved silicone elastomer insert containing oxybutynin was anchored in the vagina of female rabbits. The inserts were designed to release oxybutynin at rates of 0.5, 1.0, and 5.0 mg/day, respectively. Blood drug and metabolite levels were monitored for 1 to 7 days and cystometry was carried out after 7 days of treatment. RESULTS: There was a consistent dose-dependent absorption of the oxybutynin resulting in stable plasma concentrations by 3 days. Levels of N-desethyloxybutynin, the active metabolite that is thought to be responsible for side effects, were less than 1.0 ng/mL in all groups. The cystometrograms showed a decrease in the detrusor pressures for the higher oxybutynin groups and a dose-dependent decrease in micturition pressure. The vaginal wall in contact with the insert showed no irritation. CONCLUSIONS: The inserts produced stable blood levels and released sufficient amounts of oxybutynin to have measurable effects on the bladder. There was no irritating effect of the insert on the vaginal wall after a 1-week treatment. Vaginal inserts containing oxybutynin may be an interesting alternative method for the chronic delivery of oxybutynin.

Absorption↗
PubMed2000

High urinary flow accelerates renal injury in young rats with partial unilateral ureteral obstruction.

PURPOSE: We studied the effect of dietary manipulation and high urine flow on neonatal partial ureteral obstruction in a weanling rat preparation. MATERIALS AND METHODS: A total of 40, 3-week old Sprague-Dawley rats underwent unilateral ureteral obstruction by burial of the right ureter in the psoas muscle and 13 underwent sham operation. Low, high and normal salt, and high sucrose diets were administered for 2 months. The glomerular filtration rate of each kidney was measured by iothalamate clearance. Intrapelvic pressure and renal blood flow were measured before and after acute volume loading. RESULTS: Fluid intake and urine output were 8 to 10-fold greater in animals on high salt and high sucrose diets compared to those in rats on normal and low salt diets. Hydronephrosis was observed only in rats with partial obstruction and high urine flow. No difference in renal weight was noted. Relative glomerular filtration rate of the partially obstructed kidney was maintained when urine flow was normal but decreased significantly with high urine flow. Total glomerular filtration rate also decreased with high urine flow. Intrapelvic pressure was elevated significantly at baseline in partially obstructed kidneys with high urine flow. All kidneys with partial obstruction had significantly increased intrapelvic pressure with volume loading. Renal blood flow was not significantly decreased in rats with high urine flow. CONCLUSIONS: Chronic high urine flow causes loss of renal function in partially obstructed weanling rat kidneys. Research should be done to determine whether human infants with hydronephrosis and partial ureteral obstruction would benefit from the prevention of increased fluid and salt intake.

Animals↗
PubMed2000

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Delivery of Health Care↗
PubMed2000

Intraoperative pharmacological erection as an aid to pediatric hypospadias repair.

PURPOSE: The intraoperative evaluation of erection is a major advance in hypospadias surgery. We determined the advantages of erections induced pharmacologically over those induced by intracorporeal saline injection for evaluating chordee during hypospadias surgery. MATERIALS AND METHODS: During the repair of hypospadias or chordee without hypospadias 56 boys 6 months to 13 years old underwent pharmacological erection induced by 14 microg. alprostadil administered intracavernously. Phenylephrine (40 microg. ) was given for detumescence. We monitored the adequacy of erection and detumescence, changes in blood pressure and pulse, and in 3 cases intracorporeal pressure. Intraoperative artificial erection was also induced in 30 patients. RESULTS: Erection occurred within 1 minute of injection. It was judged to be excellent in 47 cases and adequate in 6, while it failed in 3 probably due to injection outside of the corpora. Erection involved the whole penis, in contrast to artificial erection when tourniquet placement altered the erection and left the penile base flaccid. The degree of chordee remained stable during evaluation compared to artificial erection when curvature varied with the force of the saline injection. Erection persisted during chordee repair as long as the corpora were not opened. Detumescence occurred within seconds in all cases in which phenylephrine was given. There were no cases of priapism, and systemic blood pressure and pulse did not change. Intracorporeal pressure during pharmacological erection was 47 to 70 mm. Hg, whereas during artificial erection pressure was 50 to 250 mm. Hg depending on how much saline was injected and how rapidly fluid drained through the tourniquet. Chordee was induced by over injection. CONCLUSIONS: Pharmacological erection in hypospadias repair is effective and reliable with no significant complications. It is especially valuable in severe hypospadias and in patients with a large suprapubic fat pad. Artificial erection with saline injection should be performed with only moderate force since over filling is unphysiological and may falsely induce chordee.

Adolescent↗
PubMed1999

Upper ureteral reconstructive surgery.

Upper ureteral reconstructive surgery encompasses a wide variety of procedures directed at the correction of abnormal processes and structural defects in the proximal ureter. Although some of these techniques have strict indications for specific causes, technical innovations have led to development of numerous alternatives in upper ureteral reconstructive surgery. These innovations provide the practicing urologist with various options from which to choose for the management of upper ureteral disease.

Adult↗
PubMed1999

Growth factor expression in the obstructed developing and mature rat kidney.

The purpose of this study is to evaluate the role of keratinocyte growth factor (KGF), transforming growth factor-alpha (TGF-alpha), and their receptors in altered renal growth caused by complete ureteral obstruction in the developing kidney. Neonatal and adult rats underwent complete unilateral ureteral ligation or sham operation. The kidneys were harvested at 1, 5, 10, 20, and 30 days after obstruction. Renal growth and development was assessed by histology and immunohistocytochemical localization of vimentin, cytokeratin and smooth muscle-alpha actin. Cellular proliferation was measured by [3H]thymidine labeling index of all cells. RNase protection assays were used to quantify mRNA encoding for KGF, KGF receptor, TGF-alpha, and epidermal growth factor (EGF) receptor. Ureteral obstruction in the developing kidneys resulted in decreased DNA synthesis, rapid parenchymal loss, myofibroblast proliferation in the interstitium, decreased tubular epithelial cells formation, and development of cystic dysplasia. In comparison, obstruction in the mature kidneys resulted in transient growth in the medullary ductal cells, parenchymal loss, and myofibroblast proliferation at a later time, lymphocytic infiltration in the interstitium but not cystic dysplasia. KGF and KGF receptor mRNA levels were increased in obstructed neonatal kidneys. Similarly, TGF-alpha and EGF receptor mRNA levels were increased. Delayed and more moderate increases in KGF, KGF receptor, and TGF-alpha expression were also seen in the obstructed mature kidneys. Of importance, the amount of EGF receptor mRNA was not increased in the obstructed compared with the contralateral or sham-operated adult kidneys. This study suggests that obstruction alters the normal expression pattern of KGF, TGF-alpha, and their receptors in renal development. These changes may be responsible for the impaired renal growth and altered development seen in ureteral obstruction of the kidneys. Although some changes are similar to those seen in the adult kidney, the increased expression of TGF-alpha and cystic dysplasia are unique to neonatal obstruction.

Aging↗
PubMed1999

Expression of the Wnt gene family during late nephrogenesis and complete ureteral obstruction.

Because the Wnt-4, -7b, and -11 genes are expressed in metanephric kidneys and code for secreted glycoproteins that may serve as mediators of the transformation of renal mesenchyme to epithelium, we investigated the pattern of Wnt gene expression in late metanephrogenesis and after ureteral obstruction. Newborn and 10-, 20-, and 60-day-old rats underwent complete unilateral ureteral ligation or sham operation. The kidneys were collected bilaterally 1, 5, 10, 20, or 30 days later. RNase protection assays were used to quantify the amounts of mRNA encoding Wnt-4, -7b, and -11, E-cadherin, and cytokeratin-19. Renal development was assessed by histologic characterization of vimentin, cytokeratin, E-cadherin, and beta-catenin distribution. During normal development, the amounts of mRNA encoding Wnt-4 and Wnt-11 increased during gestation and then abruptly decreased after the completion of metanephrogenesis, 15 days after birth. In contrast, the amounts of mRNA encoding Wnt-7b, E-cadherin, and cytokeratin-19 increased during development and into adulthood. In neonatally obstructed kidneys, the expression of Wnt-4 was abnormally maintained when obstruction was induced before the completion of renal development and was reactivated when obstruction was induced after the completion of metanephrogenesis. Wnt-7b expression was minimally affected and Wnt-11 expression was only transiently affected by obstruction. In neonatally obstructed kidneys, the differentiation of mesenchyme to epithelium failed to proceed normally, with the majority of cells maintaining vimentin expression and some differentiated epithelial cells reverting to vimentin expression. In addition, the expression of E-cadherin and cytokeratin was increased in epithelial cells. Changes in the expression of Wnt genes were correlated with histologic changes. This study suggests that Wnt-4 and -11 are likely to be important mediators of the transformation of mesenchyme to epithelium in the kidney. Obstruction induced during metanephrogenesis disrupts the normal pattern of Wnt-4, -7b, and -11 expression and interferes with the normal transformation process in developing kidneys, by maintaining the mesenchymal component and inducing the transformation of epithelium to mesenchyme.

Aging↗
PubMed1998

Length of stay for specialized pediatric urologic care.

BACKGROUND: Pediatric urologic specialists have been excluded from many recent managed care contracts because they are believed to be more expensive and of no better quality than general urologists in managing common urologic problems in children. We believed this to be inaccurate. OBJECTIVES: To compare the length of stay at the University of California, San Francisco Medical Center for 2 common pediatric urologic operative procedures with data from other northern California hospitals and to document our results and patient satisfaction. DESIGN: Retrospective analysis of HCIA statewide database (HCIA Inc, Orange, Conn). SETTING: Northern California, 1995. SUBJECTS: Children younger than 12 years undergoing surgery for repair of an obstruction of the ureteropelvic junction or vesicoureteral reflux. MAIN OUTCOME MEASURE: Length of stay. RESULTS: The length of stay in our hospital was similar to that observed in other hospitals in which other full-time pediatric urologic specialists practiced and was significantly less than that observed in other northern California hospitals, even when adjusted for risk. In fact, a savings of 279 hospital days would have been realized if all patients had the same length of stay as that achieved at University of California, San Francisco Medical Center. In the 38 patients operated on at our center, there was uniform surgical success. Of the parents, 92% (11/ 12) were satisfied with their child's care and 92% (11/ 12) believed they received enough information to know what to expect and how to care for their child at home. There were no data available evaluating quality from other northern California hospitals for comparison. CONCLUSIONS: Our finding that actual and risk-adjusted length of stay were shorter when patients were treated by full-time pediatric urologists, while excellent quality was maintained, suggests that these specialists achieve their results with more efficiency and lower resource utilization than do general urologists. The implication of these results is that exclusive contracting that prevents patients from receiving care from full-time specialists results in overuse of valuable resources and possibly reduced quality. If our results are generalizable, they have important implications for health care reform in the United States.

Academic Medical Centers↗