Characterization of spontaneous electrical activity of the urinary tract: Ureter,bladder, urethra

The study aimed to characterize spontaneous electrical activity of the ureter, urinary bladder and urethra as well as their interrelationship. The basic parameters of pacemaker activity (amplitude, frequency, peak rise rate, peak rise time, peak half-width) were comparatively analyzed in each of the active areas. Out of the three areas compared, the ureteral rhythmogenic zone displayed the maximum amplitude and apex formation rate. Under conditions of urine influx from the ureter into the bladder and isolation of these organs from the urethra, the amplitude and peak rise rate in the latter decreased by almost 20%. At the same time, all the parameters of the ureter and bladder remained intact. Complete block of urine influx into the bladder by transecting the ureter at the appropriate area led to a slight decrease in the amplitude of action potentials, peak rise rate and rhythmogenicity frequency in the bladder, respectively, by 14.2, 12.5 and 16% at the constancy of other parameters of its activity. Subsequent isolation of the bladder from the urethra had no appreciable effect on the altered parameters of the former. The similar tendency towards a reduction of the parameters was observed under the same conditions in the urethra. Thus, a relationship was revealed between autonomous activities of the ureter, bladder and urethra. The regulatory role in this process is provided by the urine flow through these organs.     

Mathematical model of the male urinary tract

The paper presents a simplified (but not trivial) mathematical model of the interaction between the urine flow and the male urethra and bladder, respectively. Urine is assumed to be a Newtonian fluid. The flow is considered to be non-stationary, isothermal and turbulent. The urethra and bladder wall, featuring elastic properties, experience large displacements and strains. The dynamic forces are included in the urethra wall motion. When fully extended the urethra attains the shape of an axisymetric tube. An iterative method based on the uncoupled approach is developed.     

A new method to correlate histology with biomechanical properties in urethral tissue. An in-vitro study using light microscopy and scanning acoustic microscopy

When surveying the classical biomechanical theory of flow and resistance, the passive elastic properties of the urethra seems to be important for the transport of urine though the urethra. The aim of this study was to show that scanning acoustic microscopy (SAM) is a suitable methodology for investigating elastic properties of the urethra, and that it can be used to correlate elastic properties to histological areas. One 40 kg female pig and one 2 kg male rabbit comprised the material. A SAM2000 was used at a working frequency of 1000 MHz. Sections of nominal 3 micrometer thickness fixed urethral tissue were prepared for SAM and stained for light microscopy. The histological layers of the urethra were evident in the SAM image, and showed highly variable values of elastic properties. The layers seen with SAM correlated well with those seen with light microscopy. In conclusion, we have provided the first images of the microelastic properties of the urethra and correlated them to histology.     

Structural and ultrastructural features of the inlet and outlet regions of the urinary bladders of the leech,Hirudo medicinalis L.

Each of the 34 nephridia in the leech, Hirudo medicinalis, has its own separate bladder. Urine flows from the last portion of the nephridium, the final canal, into the bladder through a special inlet which prevents backflow of urine. This inlet consists of a vestibule formed by two serially arranged septa, each with a small pore. As no muscles or cilia are associated with either the nephridia or the bladder inlet, urine flow into the bladder is passive. Urine leaves the bladder through an outlet that consists of a urethra with sphincters at both ends and an opening, the nephridiopore, in the ventral skin. The sphincter muscles are distinct from the body wall muscles and receive double innervation: urine retention and release is therefore active.     

The Shape of the Urine Stream — From Biophysics to Diagnostics

We develop a new computational model of capillary-waves in free-jet flows, and apply this to the problem of urological diagnosis in this first ever study of the biophysics behind the characteristic shape of the urine stream as it exits the urethral meatus. The computational fluid dynamics model is used to determine the shape of a liquid jet issuing from a non-axisymmetric orifice as it deforms under the action of surface tension. The computational results are verified with experimental modelling of the urine stream. We find that the shape of the stream can be used as an indicator of both the flow rate and orifice geometry. We performed volunteer trials which showed these fundamental correlations are also observed in vivo for male healthy volunteers and patients undergoing treatment for low flow rate. For healthy volunteers, self estimation of the flow shape provided an accurate estimation of peak flow rate (). However for the patients, the relationship between shape and flow rate suggested poor meatal opening during voiding. The results show that self measurement of the shape of the urine stream can be a useful diagnostic tool for medical practitioners since it provides a non-invasive method of measuring urine flow rate and urethral dilation.     

The biomechanical properties of E. coli pili for urinary tract attachment reflect the host environment

Uropathogenic Escherichia coli express pili that mediate binding to host tissue cells. We demonstrate with in situ force measuring optical tweezers that the ability of P and type 1 pili to elongate by unfolding under exposure to stress is a shared property with some differences. The unfolding force of the quaternary structures under equilibrium conditions is similar, 28 +/- 2 and 30 +/- 2 pN for P pili and type 1 pili, respectively. However, type 1 pili are found to be more rigid than P pili through their stronger layer-to-layer bonds. It was found that type 1 pili enter a dynamic regime at elongation speeds of 6 nm/s, compared to 400 nm/s for P pili; i.e., it responds faster to an external force. This possibly helps type 1 to withstand the irregular urine flow in the urethra as compared to the more constant urine flow in the upper urinary tract. Also, it was found that type 1 pili refold during retraction at two different levels that possibly could be related to several possible configurations. Our findings highlight functions that are believed to be of importance for the bacterial ability to sustain a basic antimicrobial mechanism of the host and for bacterial colonization.     

The microbial communities in male first catch urine are highly similar to those in paired urethral swab specimens

Urine is the CDC-recommended specimen for STI testing. It was unknown if the bacterial communities (microbiomes) in urine reflected those in the distal male urethra. We compared microbiomes of 32 paired urine and urethral swab specimens obtained from adult men attending an STD clinic, by 16S rRNA PCR and deep pyrosequencing. Microbiomes of urine and swabs were remarkably similar, regardless of STI status of the subjects. Thus, urine can be used to characterize urethral microbiomes when swabs are undesirable, such as in population-based studies of the urethral microbiome or where multiple sampling of participants is required.     

Flow of urine through the ureter: a collapsible, muscular tube undergoing peristalsis

In steady flow through nonuniform collapsible tubes a key concept is the compressive zone, at which flow limitation can occur at both high and low Reynolds numbers. Ureteral peristalsis can be considered as a series of compressive zones, corresponding to waves of active muscular contraction, that move at near-constant speed along the ureter towards the bladder. One-dimensional, lubrication-theory analysis shows that peristalsis can pump urine from kidney into the bladder only at relatively low mean rates of urine flow. Under these circumstances isolated boluses of urine are propelled steadily through the ureter (assumed uniform) by the contraction waves. At higher mean rates of flow the behavior depends on whether the frequency of peristalsis is higher or lower than a critical value. For frequencies above the critical value steady propagation of boluses that are in contact with contraction waves at both ends is possible. As the flow rate rises the urine begins to leak through the contraction waves and steady peristaltic flow breaks down. There is an upper limit to the mean flow rate that can be carried by steady peristalsis, which depends on the mechanical properties of the ureter. At high flow rates the peristaltic contractions do not pump but hinder the flow of urine through the ureter.     

COMMON LESIONS OF THE URETHRA IN WOMEN

Urethral disease in women and girls often is overlooked. As the urine may seem to be normal as determined by repeated urinalysis, the symptoms—urinary frequency and burning—may be attributed entirely to other pelvic disease or to functional disorder. Since erroneous diagnosis may lead to unnecessary procedures or to neglect of treatment with consequent development of severe disease in the kidneys or ureters, it is important to consider urethral lesions as a possible cause in any case of abdominal discomfort in women.The most common lesions of the urethra in women are urethritis, stricture, caruncle, inflammatory polyps and cysts, prolapse of the urethra, and diverticulum. In some cases diagnosis can be made simply on the basis of inspection and palpation. In others more extensive diagnostic procedures must be carried out in order that treatment may be definitive.The methods of treatment, varying with the nature of the lesion, are outlined herein.     

Single-cell RNA-Seq analysis identified kidney progenitor cells from human urine

Dear Editor, Urine passes through the entire kidney and urinary tract system starting from the glomerulus and ending to the urethra.Cells in the kidney and urinary tract could be exfoliated from the epithelium into the urine, while leukocyte could infiltrate from the local tissue into the urine, which makes the urine a useful subject for clinical evaluation of relevant diseases.Among them, renal tubular cells and podocytes have been identified and 2D or 3D cultured from human urine specimens (Oliveira Arcolino et al., 2015;Schutgens et al.,2019).Particularly, kidney stem cell/progenitor cells were successfully recovered from pediatric patient urine and then cultured for kidney regenerative purpose by the Romagnani group.However, they also showed that such cells cannot be recovered from healthy individuals (Lazzeri et al., 2015).It remains unknown whether similar types of progenitor cells can be found in different individuals, either healthy or diseased.     

Numerical simulation of the urine flow in a stented ureter

When a stent is implanted in a blocked ureter, the urine passing from the kidney to the bladder must traverse a very complicated flow path. That path consists of two parallel passages, one of which is the bore of the stent and the other is the annular space between the external surface of the stent and the inner wall of the ureter. The flow path is further complicated by the presence of numerous pass-through holes that are deployed along the length of the stent. These holes allow urine to pass between the annulus and the bore. Further complexity in the pattern of the urine flow occurs because the coiled "pig tails," which hold the stent in place, contain multiple ports for fluid ingress and egress. The fluid flow in a stented ureter has been quantitatively analyzed here for the first time using numerical simulation. The numerical solutions obtained here fully reveal the details of the urine flow throughout the entire stented ureter. It was found that in the absence of blockages, most of the pass-through holes are inactive. Furthermore, only the port in each coiled pig tail that is nearest the stent proper is actively involved in the urine flow. Only in the presence of blockages, which may occur due to encrustation or biofouling, are the numerous pass-through holes activated. The numerical simulations are able to track the urine flow through the pass-through holes as well as adjacent to the blockages. The simulations are also able to provide highly accurate results for the kidney-to-bladder urine flow rate. The simulation method presented here constitutes a powerful new tool for rational design of ureteral stents in the future.     

An analogue computer simulation of cloacal resorption of salt and water from ureteral urine in birds

The transmural flow of NaCl and water occurring during the retrograde flow of ureteral urine into the coprodeum and large intestine of birds has been simulated by analogue computation. The purpose was to estimate whether a fraction of the urine (water) which in the dehydrated state is hyperosmotic to plasma can, in spite of this, be absorbed from the narrow space between the epithelium and the central faeces core. The values of urine flow, urine osmolality, osmotic permeability, net NaCl absorption rate, and solute-linked water flow determined by in vivo perfusion studies in the domestic fowl were used in the calculation. The cloacal sojourn of ureteral urine was found to result in a net water gain but at the expense of a hyperosmotic NaCl absorption. The model was further used to evaluate the quantitative influence of the system's parameters upon the fractional water absorption. This was found very sensitive to the urine osmolality, moderately sensitive to the urine flow and NaCl absorption rate and almost unaffected by the osmotic permeability of the coprodeum and large intestine within a reasonable physiological range. The change of the epithelial transport parameters from the normally hydrated to the dehydrated state resulted in a marked increase in water absorption.     

Ultrasound and X-ray urethrography and urethroscopy during endoscopic operations on the urethra

In 41 patients are made x-ray ascending and descending and transrectal US (TRUS) of an urethrography and endoscopy before and after transurethral (TUR) of operations on a urethra. For 35 patients there were posttraumatic strictures and obliterations of a urethra, for 3--postinflammatory strictures, for 2--iatrogenic false courses of a urethra and for 1--congenital diverticulum of a urethra. The comparative estimation ultrasonic and x-ray urethrography and urethroscopy has shown, that they are not competitive, but complementary techniques. Thus TRUS of a urethra, as the technique irrelevant with radial load on the patient, can and should more widely be used born for primary diagnostic, and for monitoring outcomes TUR on a urethra.     

The effects of antidiuretic hormone on urine flow and composition in the chronically-cannulated ovine fetus.

The fetuses of nine pregnant ewes were chronically cannulated between 86 and 130 days with cannulae in one carotid artery, one jugular vein, the fetal bladder and the amniotic cavity. The effects of infused AVP on fetal urine flow rate and composition were studied. A dose of 35 pmol. h-1 always caused an increase in urine osmolality and a decrease in flow rate and free water clearance without change in blood pressure. Higher doses (140 pmol.h-1) were significantly pressor and caused increased excretion of sodium, chloride, urea and creatinine. Although this dose always caused an increase in urine osmolality, in five experiments the flow rate also rose. It is concluded that the ovine fetus has the ability to control its own urine flow and composition, and possibly also amniotic fluid volume and composition.     

Characteristic male urine microbiomes associate with asymptomatic sexually transmitted infection

Background

The microbiome of the male urogenital tract is poorly described but it has been suggested that bacterial colonization of the male urethra might impact risk of sexually transmitted infection (STI). Previous cultivation-dependent studies showed that a variety of non-pathogenic bacteria colonize the urethra but did not thoroughly characterize these microbiomes or establish links between the compositions of urethral microbiomes and STI.

Methodology/Findings

Here, we used 16S rRNA PCR and sequencing to identify bacteria in urine specimens collected from men who lacked symptoms of urethral inflammation but who differed in status for STI. All of the urine samples contained multiple bacterial genera and many contained taxa that colonize the human vagina. Uncultivated bacteria associated with female genital tract pathology were abundant in specimens from men who had STI.

Conclusions

Urine microbiomes from men with STI were dominated by fastidious, anaerobic and uncultivated bacteria. The same taxa were rare in STI negative individuals. Our findings suggest that the composition of male urine microbiomes is related to STI.     

Effect of norepinephrine and vasopressin on renal kallikrein excretion in rats

The purpose of this study was to investigate the effect of norepinephrine and vasopressin on urinary kallikrein excretion in the rat. Two studies were undertaken: (a) acute experiments in which the rats were infused with 30% dextrose in water with the addition of norepinephrine or vasopressin, (b) chronic experiments in which the drugs were infused during seven days through an osmotic minipump. In acute experiments, urinary kallikrein excretion increased without modification in urinary flow and glomerular filtration rate. In chronic experiments, urinary kallikrein excretion was not modified in norepinephrine-treated rats and decreased in vasopressin-infused animals. This decrease followed the modifications of the urine flow. In chronic experiments the dextrose infusion increased urinary kallikrein excretion. In all the groups studied a positive correlation between urine flow and urinary kallikrein excretion was observed. It is concluded that norepinephrine and vasopressin are important stimulators of the urinary kallikrein excretion only in those circumstances where it is necessary to eliminate an excess of water.     

Female urethral dilatation (bougierung): a case report

Background

Primary bladder neck obstruction is a rare clinical entity, reported to be responsible for 2.7–8% of lower urinary tract symptoms. It can lead to various urinary storage and voiding symptoms. The mainstay of treatment of female urethral strictures is urethral dilatation. Despite the long history of this method, it is unclear how far the female urethra should be dilated in correlation with residual urine volume.

Case presentation

A 79-year-old Caucasian woman presented to our institute with urgency (12–15 times/day), nocturia (3 times/night), and reoccurring urinary tract infections. A physical examination revealed no anatomical malformation in her genital organs, 150 mL post-void urine retention, and a significant narrowing in the mid-segment of the urethra (4 mm). After informed consent, our patient underwent urethral dilatation ranging from Ch9 (3 mm) to Ch39 (13 mm), and reported no symptoms at the 4-week follow-up, with no post-void residual urine.

Conclusions

The relatively low (around 50%) success rate of urethral dilatation might be improved by the utilization of wider dilatators, and the relaxation of the pubourethral ligament, achieved by a gentle downward saggital push during the intervention, although long-term studies with a large number of participants are necessary to prove our hypothesis.

     

Renal haemodynamics and natriuretic responses to intravenous administration of diadenosine tetraphosphate (Ap4A) and nicotinamide adenine dinucleotide (NAD) in rat.

Effects of Ap4A and NAD--precursor of adenosine, on renal plasma flow (RPF), glomerular filtration rate (GFR) and urine excretion were determined in the anaesthetised rats. Infusion of Ap4A or NAD (i.v., bolus--1 micromol/kg followed by 10 nmol/min/kg) decreased RPF and GFR (by 30 and 40%, respectively). In spite of GFR reduction during Ap4A infusion, the significant increase in sodium excretion and urine flow was noticed: fractional sodium (FENa) and urine excretion (FEurine) rose 15-fold and 2.5-fold in comparison with the control value, respectively. In contrast to Ap4A, NAD-induced decrease in GFR was associated with parallel decrease in sodium and urine excretion, thus the FENa and FEurine did not significantly change. Pretreatment with adenosine deaminase (adenosine degrading enzyme, 2 U/min/kg) or theophylline (P1-receptors antagonist, 0.2 mmol/min/kg) ceased responses to NAD, whereas Ap4A-induced changes were not affected. Pre-treatment with suramin (P2-receptors antagonist, (i.v., bolus--12 mg/kg followed by 1.2 mg/min/kg) completely abolished the renal effects of Ap4A. We conclude that Ap4A may exert specific action on renal function. It acts different from NAD that modified renal function through its hydrolysis product--adenosine. Ap4A might reduce glomerular filtration rate and evoke natriuresis and diuresis, and its effects are probably mediated through stimulation of P2-receptors.     

High urine flow rate increases prostaglandin E excretion in the conscious dog

Although previous studies from this and other laboratories have shown that urinary prostaglandin E excretion (U_PGEV) can vary independent of urine flow rate, recent studies during water diuresis in the conscious dog have suggested that high urine flow rate per se may increase U_PGEV. To examine the effect of urine flow rate on U_PGEV we administered either mannitol, chlorothiazide or Ringer's solution to mongrel dogs and measured U_PGEV. During anesthesia neither mannitol or chlorothiazide increased U_PGEV. There was, however, a consistent increase with all three agents in awake animals. This increase in U_PGEV was independent of alterations in glomerular filtration rate. There was a consistent increase in urinary sodium excretion and decrease in urinary osmolality with all three agents. The changes in PGE, however, were similar to those found during water diuresis when no increase in sodium excretion was found. It is not presently clear whether these findings reflect a true increase in renal PGE synthesis due to some change in flow or pressure within the renal medulla or rather represent unchanged PGE synthesis by renal tubular cells, the high tubule fluid flow rate causing increased entry into the tubular lumen in contrast to the renal interstitium.     

Detection of latent bacteriuria in patients with chronic pyelonephritis

Diagnostic possibilities of selective examination of renal urine particularly collected under medicamentous polyuria conditioned by the administration of Lazix were studied in latent bacteriuria. By means of separate collection of renal urine against the background of polyuria it was possible additionally to detect bacteriuria in 1/3 of the patients, to record increase in the intensity of the index in almost half of the patients with renal bacteriuria and, in 1/4 of them to detect, in renal urine, the aetiological agent absent from bladder urine. The latter circumstance not only has a diagnostic significance but also plays a certain role in the selection of medicamentous therapy in chronic pyelonephritis. In addition to traditional bacteriological methods, filtration through membrane filters was used to isolate and identify microflora in the urine. By means of this method it is possible to detect extremely low bacteriuria which cannot be established by any other method.