PubMed Health⌕ Search

Biomedical subjects

B Kogan

Publications and source records attributed to B Kogan.

11 recordsLinked to original sources
PubMed2001

The effect of urine volume and nitric oxide on basal bladder blood flow: response to catheterization and drainage.

Preliminary studies demonstrated that catheterization and drainage of the urinary bladder resulted in a significant increase in blood flow to the bladder. The objectives of this study were to determine 1) the relationship between urine volume and basal blood flow to the bladder smooth muscle and mucosa, 2) the effect of acute catheterization and drainage on bladder mucosal and smooth muscle blood flow, and 3) whether nitric oxide was involved in regulation of basal blood flow or the increase in blood flow observed after catheterization and bladder drainage. Twenty-four rabbits were separated into two groups: group 1 (14 rabbits) and group 2 (10 rabbits) treated with L-NAME (NOS inhibitor) 30 minutes before blood flow measurement. Blood flow was measured in all animals using a fluorescent microsphere technique before and immediately after catheterization and drainage of the bladder. The results demonstrated that 1) blood flow to the muscle and mucosa were independent of urine volume at the time of catheterization and drainage; 2) catheterization and drainage significantly increased blood flow to both the bladder smooth muscle and bladder mucosa, but not to the kidney; 3) L-NAME significantly reduced basal blood flow to the kidney, but not to the bladder smooth muscle or mucosa; and 4) L-NAME completely prevented the catheterization- and drainage-induced increases in blood flow to the bladder body mucosa and muscle. This study demonstrates that basal blood flow to the bladder smooth muscle and mucosa during filling is independent of NO control; although bladder blood flow may be increased significantly by NO synthesis and release during bladder emptying, and thus may be an important regulator of blood flow during and immediately following micturition.

Animals↗
PubMed2001

Granulomatous lymphangitis of the scrotum and penis. Report of a case and review of the literature of genital swelling with sarcoidal granulomatous inflammation.

BACKGROUND: Acquired lymphedema of the genitalia is a rare childhood presentation and is more common in elderly individuals secondary to pelvic/abdomenal malignancy or its therapy or worldwide due to filariasis. OBJECTIVE: Herein, we report a case of a healthy 11-year-old boy who presented with a 1-year history of chronic, asymptomatic scrotal and penile swelling. Biopsy revealed edema, lymphangiectases and peri- and intralymphatic sarcoidal type granulomas. This histologic pattern of granulomatous lymphangitis is most commonly associated with orofacial granulomatosis (granulomatous cheilitis and Melkersson-Rosenthal syndrome) and Crohn's disease. Treatment with topical steroids and physical support has resulted in marked improvement. No systemic disease (Crohn's disease) is evident 1 year later. Literature review revealed 44 cases of genital lymphedema with non-infectious granulomas. The majority of these young patients had Crohn's disease, frequently with anal involvement and a minority, both with and without Crohn's disease, had orofacial granulomatosis. CONCLUSIONS: Granulomatous lymphangitis should be considered in the differential diagnosis of chronic idiopathic swelling of the genitalia, particularly in younger individuals. Further clinical examination, additional laboratory studies and close follow-up for co-existing or subsequent development of Crohn's disease should be performed. The overlap between granulomatous lymphangitis of the genitalia, Crohn's disease and orofacial granulomatosis suggest that granulomatous lymphangitis of the genitalia may represent a forme fruste of Crohn's disease.

Administration, Topical↗
PubMed2001

Urethra is more sensitive to ischemia than bladder: evidence from an in vitro rat study.

PURPOSE: Experimental studies have demonstrated that ischemia may induce significant bladder dysfunction. Because multiple causes leading to bladder ischemia also decrease urethral perfusion, we assessed the effect of in vitro ischemia on the contractile responses of the rat bladder and urethra. We evaluated the hypothesis that neurogenic dysfunction in urethral ischemic injury occurs before myogenic dysfunction is present. We also compared contractile responses of the rat bladder and urethra to in vitro ischemia followed by reoxygenation. MATERIALS AND METHODS: Isolated strips of rat bladder detrusor muscle and prostatic urethra were incubated in normal physiological medium and stimulated electrically and chemically. In vitro ischemia was produced by incubating tissue in ischemic medium for 30 or 60 minutes. The maximal tension and maximal rate of tension generated were analyzed digitally before ischemia and after ischemia followed by reoxygenation. RESULTS: We demonstrated that after 30 minutes of ischemia followed by reperfusion the maximal rate of tension generated decreased significantly only in the urethra and only in response to field stimulation. After 60 minutes of ischemia the decrease in urethral contractile responses was greater than the decrease in bladder contractile responses. Ischemia 60 minutes in duration caused a significant decrease in the maximal rate of tension generated as well as maximal tension in the urethra and bladder but only in response to field stimulation. CONCLUSIONS: This experiment demonstrates that the urethra is more sensitive to ischemic injury than the bladder. Our finding may explain the development and symptoms of urinary incontinence secondary to sphincteric damage before bladder dysfunction is present. We also demonstrated that in the bladder and urethra the response to field (neurogenic) stimulation is the most sensitive form of stimulation to ischemia.

Animals↗
PubMed2000

Rabbit urinary bladder blood flow changes during the initial stage of partial outlet obstruction.

PURPOSE: The rabbit urinary bladder's early response to partial outlet obstruction includes bladder wall remodeling with marked urothelial and fibroblast hyperplasia (1 day) and smooth muscle hypertrophy (3-5 days) resulting in a 4-5 fold increase in bladder mass within 7 days. In this study, we examined the effect of partial outlet obstruction on bladder blood flow during the initial period of rapid growth (1-7 days). MATERIALS AND METHODS: Each New Zealand White rabbit was partially obstructed by tying a 2-0 silk ligature loosely around the vesical outlet. After 0 (unoperated), 4 hours, 1, 3, or 7 days of obstruction, 5 rabbits per group were anesthetized and the carotid and femoral arteries cannulated with polyethylene tubing. Additional rabbits receiving sham surgeries were treated like obstructed animals at 4 hours and 1 day post-obstruction (5/group). Using standard methods, fluorescent microspheres were infused through the right carotid artery. Bladder and right kidney were rapidly removed upon completion of sphere infusion; bladder mucosa and muscle were separated. Sphere densities in detrusor, mucosa, and kidney were measured by Interactive Medical Technologies, Ltd. A section of each detrusor tissue was fixed in formalin and immunostained for smooth muscle alpha-actin. RESULTS: Mucosal blood flow (0.20 +/- 0.03 ml./min./gm.) was approximately 4-fold greater than that of detrusor (0.05 +/- 0.01 ml./min./gm.). Sham surgery caused a significant increase in bladder blood flow at 4 hours post-obstruction that returned to control levels by 1 day. Both mucosal and muscle blood flows were slightly higher in rabbit bladders obstructed for 4 hours than in sham-operated rabbits, and substantially greater in those obstructed for 1 day: 0.68 +/- 0.13 ml./min./gm. (mucosa) and 0.26 +/- 0.04 ml./min./gm. (muscle). Blood flows returned to control values by 3 days post-obstruction and remained constant through 7 days. Kidney blood flow was unchanged. Although bladder weight increased 4-fold after 7 days of obstruction, the volume fraction of smooth muscle (transverse section) remained constant at approximately 40%. CONCLUSIONS: Blood flow was approximately 4-fold greater in bladder mucosa than in muscle, which may relate to the significantly higher metabolic rate and lower high energy phosphate concentration of mucosa than muscle. Partial outlet obstruction resulted in a significant increase in blood flow at 1 day post-obstruction, which coincides temporally with the early cellular hyperplasia and hypertrophy of obstructed rabbit bladder. This increase in blood flow may be an essential factor for the initial increase in bladder mass. By three days, the blood flow per gram of tissue returned to control levels. The mechanisms relating to the changes in blood flow induced by partial outlet obstruction are currently under investigation.

Animals↗
PubMed1999

Intracellular Ca(2+) dynamics and the stability of ventricular tachycardia.

Ventricular fibrillation (VF), the major cause of sudden cardiac death, is typically preceded by ventricular tachycardia (VT), but the mechanisms underlying the transition from VT to VF are poorly understood. Intracellular Ca(2+) overload occurs during rapid heart rates typical of VT and is also known to promote arrhythmias. We therefore studied the role of intracellular Ca(2+) dynamics in the transition from VT to VF, using a combined experimental and mathematical modeling approach. Our results show that 1) rapid pacing of rabbit ventricular myocytes at 35 degrees C led to increased intracellular Ca(2+) levels and complex patterns of action potential (AP) configuration and the intracellular Ca(2+) transients; 2) the complex patterns of the Ca(2+) transient arose directly from the dynamics of intracellular Ca(2+) cycling, and were not merely passive responses to beat-to-beat alterations in AP; 3) the complex Ca(2+) dynamics were simulated in a modified version of the Luo-Rudy (LR) ventricular action potential with improved intracellular Ca(2+) dynamics, and showed good agreement with the experimental findings in isolated myocytes; and 4) when incorporated into simulated two-dimensional cardiac tissue, this action potential model produced a form of spiral wave breakup from VT to a VF-like state in which intracellular Ca(2+) dynamics played a key role through its influence on Ca(2+)-sensitive membrane currents such as I(Ca), I(NaCa), and I(ns(Ca)). To the extent that spiral wave breakup is useful as a model for the transition from VT to VF, these findings suggest that intracellular Ca(2+) dynamics may play an important role in the destabilization of VT and its degeneration into VF.

Action Potentials↗
PubMed1998

Wave propagation in cardiac tissue and effects of intracellular calcium dynamics (computer simulation study).

Computer simulation using Luo-Rudy I1 model of ventricular myocyte showed that intracellular calcium dynamics become irregular in case of high rate stimulation. This causes the transition from stationary to nonstationary spiral wave and its breakup in 2D model of cardiac tissue. Obtained results suggest how ventricular fibrillation may occur due to the abnormalities of intracellular calcium dynamics. The short review of existing cardiac cell models with calcium dynamics is presented.

Animals↗
PubMed1997

Quasiperiodicity and chaos in cardiac fibrillation.

In cardiac fibrillation, disorganized waves of electrical activity meander through the heart, and coherent contractile function is lost. We studied fibrillation in three stationary forms: in human chronic atrial fibrillation, in a stabilized form of canine ventricular fibrillation, and in fibrillation-like activity in thin sheets of canine and human ventricular tissue in vitro. We also created a computer model of fibrillation. In all four studies, evidence indicated that fibrillation arose through a quasiperiodic stage of period and amplitude modulation, thus exemplifying the "quasiperiodic transition to chaos" first suggested by Ruelle and Takens. This suggests that fibrillation is a form of spatio-temporal chaos, a finding that implies new therapeutic approaches.

Action Potentials↗
PubMed1986

Bilateral nephrectomy for Wilms tumor.

Bilateral nephrectomy was performed in 4 patients with bilateral Wilms tumor. The current philosophy regarding the need to preserve maximum renal parenchyma is discussed. New guidelines suggested by the National Wilms Tumor Study group discourage unilateral nephrectomy and partial nephrectomy at initial exploration for bilateral Wilms tumor. Alternatively, it is recommended that continued treatment with chemotherapy and/or radiation therapy followed by second and third-look operations to maximize preservation of renal parenchyma be done with bilateral nephrectomy as a last resort option.

Child, Preschool↗
PubMed1981

Early postoperative assessment of the functional patency of ureterovesical junction following ureteroneocystostomy.

We studied 37 children soon after ureteroneocystostomy using diuretic radionuclide urography to assess the patency of the ureterovesical junction. Postoperative obstruction was excluded correctly in 90 per cent of the patients. Transient ureterovesical obstruction occurred in 5 patients, identification of which was useful in assigning risk and in guiding followup studies. Because it is a safe, noninvasive and relatively low radiation test the diuretic radionuclide urogram proves to be an attractive alternative to the excretory urogram in the early and late followup of patients undergoing a ureterovesical junction operation.

Adolescent↗