Computer assisted laparoscopic pneumovesical ureter reimplantation a.m. Cohen: initial experience in a pig model

To assess the feasibility of a new variant of laparoscopic Cohen cross-trigonal ureter reimplantation in vesico-ureteral reflux (VUR) using telesurgical equipment. VUR was induced in 8 female pigs by transurethral unroofing of the ureteric orifices. Three months later the reflux was verified by a cystography. A cross-trigonal ureter reimplantation a.m. Cohen was performed by laparoscopic access to the bladder using the da Vinci telesurgical system. The 12 mm camera port was placed below the umbilicus, two 8 mm working ports for the robotic system were placed lateral to the rectus muscles and an additional port for assistance between camera and right working port. The outcome was assessed 3 months later by a new cystography. The operative time for a single reimplantation varied from 45 to 90 minutes. In all pigs the reflux disappeared after the procedure, which was complicated by a postoperative port hernia in two animals. Laparoscopic transvesical ureter reimplantation using telesurgical equipment is a feasible method in the few cases this procedure is indicated. The advantage of the robotic equipment is the better access to submucosal tunneling of the ureter and the intravesical suturing of the anastomosis indicated by shorter operative time and success rates similar to the open procedure.     

Incontinence in a child with a duplex kidney: case report

Persistent incontinence after toilet training in young girls and urinary tract infections or epididymitis in prepubertal boys should raise suspicion of an ectopic ureter. This often occurs in the context of duplication of kidney structures or other parenchymal abnormalities. The presence or absence of reflux affects surgical treatment, which may consist of ureteral reimplantation, ureteroureterostomy, and/or upper pole nephrectomy.     

Correction of experimentally produced vesicoureteric reflux in the piglet by intravesical injection of Teflon.

Vesicoureteric reflux was produced in eight piglets by opening their bladders and slitting the anterior intravesical wall of the ureter. Cystography confirmed the presence of bilateral reflux in six piglets and unilateral reflux in two. Six to eight weeks later the bladder was again opened and Teflon paste injected in the space behind the intravesical ureter, thereby creating a support for the submucosal ureter. Cystography four to six weeks after injection of Teflon paste showed absence of reflux in all animals. Intravenous pyelography showed obstruction at the vesicoureteric junction in only one of the 14 treated ureters and this was later confirmed at necropsy. Animals were followed up from one to six months and then were killed. Gross examination of the vesicoureteric region showed a well circumscribed subureteric Teflon mass of firm consistency, retaining its shape and position at the site of the injection. Histological examination showed encapsulation of the implant by a thin layer of fibrous tissue and a foreign body granulomatous reaction with histiocytes and giant cells within the implant. Hence it is technically feasible to correct experimentally produced vesicoureteric reflux in the piglet by intravesical injection of Teflon paste--a relatively inert material. It may now be possible to treat vesicoureteric reflux in man by endoscopic injection of Teflon behind the intravesical ureter.     

Treatment of vesicoureteric reflux by endoscopic injection of Teflon.

Thirteen girls with grade III-V vesicoureteric reflux were treated by endoscopic injection of Teflon paste behind the intravesical ureter. Fourteen of the 18 treated ureters showed complete absence of reflux after one injection of Teflon. Three ureters required a second injection of Teflon for successful treatment of the reflux. One ureter with grade IV reflux was converted to grade II reflux. Properly carried out, this procedure corrects reflux. It takes less than 15 minutes, may be done as a day procedure, and avoids open surgery. There have been no complications.     

The effect of ureteric stents on urine flow: Reflux

If the ureter becomes blocked, the resultant increased pressure may be relieved by inserting a double-J stent (a polymer tube, usually punctuated with holes). A major clinical problem associated with stent use is reflux (retrograde flow of urine from the bladder to the kidney), which may result in infections, scarring, and even renal failure. We develop a mathematical model, treating the ureter as an elastic tube and the stent as a permeable rigid tube within it. We investigate how the number of holes in the stent wall affects the total amount of reflux that occurs when bladder pressure rises, by considering the limits of a highly-permeable stent, and an impermeable stent. We find that, in the scenarios we consider, the highly-permeable stent gives rise to less total reflux than the impermeable one.Revised version: 8 August 2003     

A two way fully coupled fluid structure simulation of human ureter peristalsis

Abstract

Numerical simulations of ureter peristalsis have been carried out in the past to understand both the flow field and ureter wall mechanics. The main objective of the current investigations is to have a better understanding of the urine transport due to the peristalsis in the ureter, thus making the information helpful for a better treatment and diagnosis of ureteral complications like urine reflux. In the current study, a numerical simulation is performed using a finite-element-based solver with a two-way fully coupled fluid structure interaction approach between the ureter wall and urine. For the first time, the ureter wall is modeled as an anisotropic hyper-elastic material based on experiments performed in previous literature on the human ureter. Peristalsis in the ureter is modeled as a series of isolated boluses. By observing the flow field it is clear that the peristalsis mechanism has a natural tendency to create a backflow as the isolated bolus moves forward. As a result, the urine can flow back from the bladder to the ureter at the ureterovesical (ureter-bladder) junctions, if the one-way valve starts to malfunction.     

Vesico-ureteric Reflux after Renal Transplantation

The uretero-vesical junction has been examined by micturating cystography in 20 patients after renal transplantation. Intravenous pyelograms were used to investigate the upper urinary tract in 13 of the patients. Persistent urinary infection did not occur in patients without vesico-ureteric reflux. However, both those with reflux of their own and the transplant ureters had persistent infection. When reflux affected the tunnelled transplanted ureter there was no infection, but two patients without a tunnel implant had a persistent urinary infection.     

α-Fetoprotein-Producing Non-Germ Cell Tumors of the Urological System

Elevated serum levels of α-fetoprotein (AFP), a fetal serum protein, occur mainly in the development of hepatocellular carcinoma (HCC) or germ cell tumors, mainly yolk sac tumor. Rarely, other tumors of the urological system produce AFP. This article reviews the AFP-producing non-germ cell tumors of the urological tract reported to date. These include different types of tumors of the adrenal glands, kidney, ureter, urinary bladder, and testis. It is important for pathologists, urologists, and oncologists to be aware of such cases as the diagnosis affects the management plan for the patient.     

Chronic epididymitis: a practical approach to understanding and managing a difficult urologic enigma

Many patients with unilateral or bilateral testicular, epididymal, or scrotal pain as their sole presenting symptom receive a diagnosis of "chronic epididymitis." This common clinical entity is diagnosed and treated by practicing urologists but essentially ignored by academic urologists. This article defines chronic epididymitis, reviews current knowledge regarding its etiology, and describes appropriate physical examination and clinical testing for patients with the condition. The recently developed Chronic Epididymitis Symptom Index is presented, which can be used for baseline evaluation and follow-up of patients with chronic epididymitis, both in clinical practice and in research treatment trials. Treatment options, from watchful waiting to medical therapy to epididymectomy, are reviewed.     

Perplexing problem of persistently painful prostatitis

Chronic prostatitis has been a perplexing problem for urologists for decades. This review explores the perils and pitfalls urologists encounter with epidemiology, etiology, classification, diagnosis, and treatment of this syndrome. The major question involves the problem of developing rational treatment plans for patients with a medical condition associated with genitourinary pain, variable voiding, and sexual dysfunction but no obvious and accepted etiology. Exciting, innovative, ongoing research does offer some solutions and management strategies that urologists can even now incorporate into their practice while waiting for the fundamental questions to be answered.     

Effectiveness of bulking procedures in measuring population-pairwise similarity with dominant and co-dominant genetic markers

Two bulking procedures (bulking individuals before and after genotyping) are commonly applied in similarity based studies of genetic distance at the population or higher level, but their effectiveness is largely unknown. In this study, expected population-pairwise similarity for both bulking procedures is derived with dominant and co-dominant diallelic markers. Numerical examples for the derived formulae are given with up to ten individuals randomly selected from each population. The procedure of bulking individuals after genotyping with either marker system is generally more informative than the procedure of bulking individuals before genotyping, because the former incorporates the information from marker alleles of intermediate frequency. Both procedures are effective with 5–10 individuals selected randomly from either population, but the procedure of bulking before genotyping requires a genotyping effort several-fold less than the procedure of bulking after genotyping. For either bulking procedure, a co-dominant marker system is generally more informative than a dominant marker system. Received: 20 October 1999 / Accepted: 11 November 1999     

Microbial Ecological Model of Filamentous Bulking and Mechanisms

The paper proposes a prototype mathematical model for the interactions among filamentous bacteria, floc-forming bacteria and protozoa within completely mixed activated sludge systems, which is capable of describing the practical coexistence of three microorganisms in a generic way. The systems with substrate fluctuation and without substrate fluctuation are investigated, respectively. The results show that filamentous bulking will occur within an interested range of substrate concentrations under unsuitable dilution rates, particularly at low substrate concentrations. When substrate concentration fluctuates, the same-frequency synchronous control parameters are beneficial to prevent filamentous bulking. Thus, the present investigations not only reveal the cause of the problem of filamentous bulking theoretically, but also may provide a crucial theoretical foundation for overcoming it.     

Injectable polymeric microspheres with X-ray visibility. Preparation,properties, and potential utility as new traceable bulking agents

The copolymer of methyl methacrylate (MMA) and 2-[2',3',5'-triiodobenzoyl]oxoethyl methacrylate (1), ratio 3:1 (mass:mass), was prepared via a free-radical polymerization in bulk. The copolymer (M(w) = 97.8 kD and M(n) = 41.5 kD) was dissolved in chloroform and subsequently transformed into beads with a diameter in the micrometer range, using a solvent evaporation technique. The resulting microbeads were characterized by different techniques, including NMR spectroscopy, differential scanning calorimetry, gel permeation chromatography, and scanning electron microscopy. The latter technique was used as the basis for statistical analysis of the bead size. Typically, an average diameter of 96 microm and a standard deviation of 21 microm were obtained. The beads were also subjected to some preliminary tests regarding cytotoxicity. The copolymer of MMA and 1 contains covalently bound iodine. Therefore, the material is intrinsically radiopaque, i.e., capable of absorbing X-radiation while no contrast additive is needed. Our interest in these microspheres stems primarily from their possible utility as injectable and afterward traceable (radiopaque) bulking agents, e.g., for use in urology for the treatment of female stress incontinence due to sphincter deficiency. As a first test into this direction, a sample of the microbeads was mixed with ethylene glycol, and the resulting suspension was studied with respect to injectability and radiopacity. The results suggest that the radiopaque microbeads may provide access to improved bulking agents. Further modification of the surface may be necessary in order to suppress the migratory aptitude of the radiopaque polymeric microspheres in vivo.     

Predicting the onset of filamentous bulking in biological wastewater treatment systems by exploiting image analysis information

The performance of the activated sludge process is limited by the ability of the sedimentation tank (1) to separate the activated sludge from the treated effluent and (2) to concentrate it. Apart from bad operating strategies or poorly designed clarifiers, settling failures can mainly be attributed to filamentous bulking. Image analysis is a promising technique that can be used for early detection of filamentous bulking. The aim of this paper is therefore twofold. Foremost, correlations are sought between image analysis information (i.e., the total filament length per image, the mean form factor, the mean equivalent floc diameter, the mean floc roundness and the mean floc reduced radius of gyration) and classical measurements (i.e., the Sludge Volume Index (SVI)). Secondly, this information is both explored and exploited in order to identify dynamic ARX and state space-type models. Their performance is compared based on two criteria.     

Cat-eye syndrome. Clinical and cytogenetical differentialdiagnosis (author's transl)]

We report a 5 1/2-year-old girl whose clinical symptoms are consistent with diagnosis of the cat-eye syndrome. The prominent symptoms are: anal stenosis, preauricular tags and pits, coloboma of the iris, doubling of the pelvis and ureter on both sides, vesicourethral reflux on the right side and normal mental development. Leucocyte alkaline phosphatase is normal. Chromosomal analysis shows a supernumerary submetacentric chromosome. This extra chromosome is smaller than the G-group chromosomes and has satellites on the short and long arms. Autoradiography after 3H-thymidine incorporation shows a late-labeling marker chromosome. After using the Giemsa-banding technique, the chromatides demonstrate dark bandings with only soft, unstained satellites. With the fluorescence method, one can see spotlike fluorescence of the satellites on both arms and diffuse fluorescence of the hetero-chromatic segments. In addition, the C-bandings demonstrate a homogeneous dark staining of the chromatids, but we did not find stained satellites. Using the Giemsa-11 technique one can see the 47th chromosome with predominantly heterochromatic parts, but small euchromatic segments are visible between them. Satellites are unstained. Using currently accepted cytogenetical methods, it is not possible to identify the origin of this supernumerary marker chromosome.     

Laparoscopic fundoplication: the alternative to long-term medical therapy for severe gastroesophageal reflux disease.

Gastroesophageal reflux disease is common. Fundoplication is very effective for those patients who fail medical therapy, particularly those with an incompetent lower esophageal sphincter. Open surgery is reported to achieve cure rates in excess of 90 percent. Laparoscopic fundoplication has been performed since 1991. The early experience with this procedure is reviewed. RESULTS: 1992 cases were reported in the literature. The mortality rate was 0.1 percent. Operative complications occurred as follows: 0.9 percent esophagogastric perforation rate; 0.6 percent bleeding rate (requiring transfusion); and 0.6 percent pneumothorax rate. No splenectomies were reported. 4.8 percent of patients required conversion to the open procedure. As experience with the procedure is gained this conversion rate decreases. Recurrent reflux postoperatively is 3.4 percent, but follow-up is short (range: 0 to 36 months; mean: two years). Dysphagia requiring dilatation occurs in 3.5 percent of patients. Gas bloat occurs in 0 to 24 percent of patients. These results compare favorably with the published results of medical therapy and the open fundoplication. CONCLUSIONS: The early experience with laparoscopic fundoplication appears promising and provides an attractive alternative to long-term medical therapy and to open surgery in appropriate patients. Long-term follow-up is awaited.     

Use of laparoscopy in pediatric urology

The goal of laparoscopy is to minimize patient morbidity while maintaining successful outcomes. The use of laparoscopy in urology has grown significantly over the past 30 years. Its use has been slower to gain acceptance in pediatrics than in the adult population. Laparoscopic orchidopexies and nephrectomies are commonly performed and have become widely accepted as alternatives to open surgery, if not the gold standard. The more technically demanding procedures, such as laparoscopic pyeloplasty, laparoscopic-assisted bladder reconstruction, and laparoscopic ureteral reimplantation, tend to be performed at selected centers and have yet to achieve widespread acceptance. As laparoscopy is applied more widely in pediatric urology, its potential benefits and drawbacks will be clarified.     

Ureteral motility in sheep

Ureteral motility was studied in twenty-five sodium pentobarbital-anaesthetized sheep. Mean frequency of the peristaltic waves was 15 per min and the range was 11-19. Frequency was the same throughout the length of the ureter. Mean contraction pressure (cm H2O) was 40 in the upper ureter, 35 in the middle ureter and 31 in the lower ureter. Mean concentration time was 1 sec and range was 0.6-1.5. Mean relaxation time was 1.1 sec and range was 0.7-1.5. Diuresis induced by rapid intravenous administration of physiologic sodium chloride solution abolished the peristaltic activity.     

Active contractions of ureteral segments

The first step in the analysis of the biomechanics of any organ is to obtain its constitutive equation. In pursuit of a constitutive equation describing the peristalsis of the ureter, we measured the relationship between the length of the muscle, the velocity of contraction, and the active tension development of isolated ureter segments. The results of length-tension measurements (giving the maximum tension developed in isometric contraction of a ureter segment of specific length) were similar to those obtained by previous investigators and reflected the behavior of length-tension relationship for other smooth muscles. Two aspects of the force-velocity relationship of the ureter were examined: the effect of releasing the ureter at different times after stimulation, and that at different levels of afterload. Measurements were analyzed using the hyperbolic Hill's equation in the form T/T0 = (1-v/v0) (l + cv/v0)-1 where v is the velocity of contraction, v0 is the velocity of contraction when T = 0, T is the tension in the muscle after release, T0 is the tension in the muscle immediately prior to release, and c is the dimensionless constant. The results of force-velocity measurements showed that the so-called "maximum" velocity v0, is the largest if the tension is released at a time of contraction, early in the rise portion of the contraction cycle. Further, if tension is released from an isometric contraction at a fixed time in the rise portion of the contraction cycle, the largest value of v0 is obtained when the muscle length is in the range of 0.85-0.90 Lmax. Interestingly, the in vivo length of the ureter lies also in this range, 0.85-0.90 Lmax.     

Advanced glomerulosclerosis is reversible in nephrotic mice

Advanced glomerulosclerosis, a common hallmark of chronic renal diseases (CRD) is believed to be irreversible, and it is thought that glomerular hyperfiltration and hypertrophy may participate in its pathogenesis. We demonstrate here that glomerulosclerosis is "reversible" in an animal model. We used nephrotic ICGN (nep/nep) mice which showed a rapid progression of glomerulosclerosis, accompanied by histological findings for glomerular hyperfiltration. It is known that ureter ligation reduces glomerular filtration in ligated kidneys. When ureter ligation was applied to our model, glomerulosclerosis (characterized by myofibroblast hyperplasia and over-accumulated matrix protein) weakened in conjunction with suppressed glomerular hypertrophy. During this process, glomerular myofibroblasts showed apoptotic cell death after unilateral ureter ligation (UUO) treatment. Our results suggest that inhibition of glomerular filtration in sclerotic tufts may cause glomerular remodeling through the modulation of molecular and cellular sclerogenesis.