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Query: UMLS:C0403608 (ureter)
 9,655 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The construction of renal lobules in Triturus (Cynops) pyrrhogaster was studied by reconstruction from serial semithin sections, and the structure of nephrons, collecting ducts and ureters was investigated by means of light and electron microscopy. In T. pyrrhogaster the kidney was mesonephros in construction; renal lobules were arranged segmentally and each of them sent one ureter. Male ureters ran caudally and met together before joining the Wolffian duct. In renal lobules, long collecting ducts ran medio-laterally in the dorsal aspect of the kidney and sent several branches ventrally. Each branch duct or short collecting duct received one nephron. Each nephron had five segments; 1) renal corpuscle, 2) ciliated neck segment with or without a naphrostome, 3) proximal tubule, 4) ciliated intermediate segment and 5) distal tubule. Proximal and distal tubules were segregated spacially in renal lobules and occupied the peripheral and central zone respectively. The filtration barrier of the glomerulus consisted of both the basal lamina of podocytes and the subendothelial connective tissue, and was much thicker than the mammalian filtration barrier. Proximal tubule cells had a brush border, apical specialization for reabsorption of organic materials and well-developed smooth endoplasmic reticulum, but few baso-lateral interdigitations. In distal tubule cells, baso-lateral interdigitations and infoldings were well-developed. Collecting duct cells had a sparse cytoplasm. Ureter cells in males contained many secretory granules. On the basis of structural organization of the newt kidney as well as physiological data in literature, we suggest that in land vertebrates proximal tubules were primarily adapted to reabsorption of organic materials and distal tubules to reabsorption of electrolytes and water.
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PMID:The structure of the kidney of Japanese newts, Triturus (Cynops) pyrrhogaster. 683 32

Only the neodymium-YAG laser is suitable for destroying tumors endoscopically, because it shows a very high transmission through water and a slight absorption in the tissue. It means scattering becomes important and leads to a homogeneous and uniform distribution of the radiation in the tissue producing a deep thermal effect. An examination of a section through a bladder wall under light microscope after neodymium-YAG laser irradiation shows a layered, sharply delimited coagulation necrosis that extends to all of the bladder wall layers and reaches the outermost zones. In this way it is possible to destroy not only the exophytic part of a tumor but also the tumor base in the tissue. Since 1976 we destroyed more than 4000 bladder tumors by laser application. For tumors on the ureter or kidney pelvis a special endoscope, described by Perez-Castro Ellendt and modified by us, can be used, if it is not possible to perform a conventional operation. It is reported about four cases of distal ureter tumors (GI-II) in patients who had refused an operation for removing the tumor bearing ureter segments. Now, for more than one and half a year all patients are free of tumors and the irradiated ureters show a good function. This novel procedure is not for routine, but for high risk patients or patients, who refuse an open operation.
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PMID:[Destruction of ureteral tumors with the neodymium-YAG laser. A new, organ-preserving surgical procedure]. 685 29

Rehydrating rats injected with diazepam (8 mg/kg, SC) increased their intake of 2.0% NaCl solution. Neither bilateral nephrectomy nor bilateral ureter ligation interfered with the increased NaCl solution ingestion produced by diazepam. It is concluded that the increased intake of the NaCl solution is not secondary to renal water-electrolyte losses nor dependent upon intact renal benzodiazepine receptors.
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PMID:Diazepam-induced NaCl solution intake: independence from renal factors. 688 22

Urine was observed to flow intermittently in the collecting ducts of the extrarenal papilla of antidiuretic rats. The purpose of this investigation was to test Reinking and Schmidt-Nielsen's hypothesis that intermittent flow plays an important role in the production of maximally concentrated urine. Samples of collecting duct fluid were obtained from the base and tip of the papilla by micropuncture through the intact ureter. Fluid osmolality rose sharply from base, 894+/-120 mosmol/kg H(2)O(-1) (mean+/-SE), to tip, 1,667+/-114 (P<0.001), a distance of only 2 mm, and was due exclusively to reabsorption of water. After excision of the ureter, which abolished intermittent flow, osmolality fell modestly at the base to 723+/-82 mosmol/kg H(2)O(-1) (P < 0.02), but strikingly at the tip to 1,012+/-103 (P < 0.001). The pelvic ureter was paralyzed by topical verapamil and dimethylsulfoxide, which abolished intermittent flow. Osmolality of urine at the tip was not changed (1,959+/-184 mosmol/kg H(2)O(-1) before, vs. 1,957+/-126 after paralysis). The ureter was severed just beyond the papillary tip, a maneuver which preserved intermittent flow but abolished urinary reflux over the papilla. Urinary osmolality fell from 1,876+/-134 mosmol/kg H(2)O(-1) to 1,284+/-115 (P < 0.005). These findings demonstrate that when the ureter is intact, over half of the increase in urinary osmolality above isotonicity occurs in the terminal one-fourth of the medullary collecting duct and is due exclusively to water reabsorption (no net solute addition). It is the continuity of the ureter, rather than intermittent flow due to ureteral peristalsis, which is essential for the formation of a maximally concentrated urine.
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PMID:Urinary concentration in the papillary collecting duct of the rat. Role of the ureter. 705 36

In previous reports from this laboratory we have suggested that a reduction in medullary tonicity decreases the thin ascending loop of Henle sodium reabsorption and is in part responsible for the magnitude for the natriuresis accompanying 10% body weight Ringer loading. According to this postulate, one would expect that the medullary washout associated with water diuresis would also result in a natriuresis, but this does not occur. It is possible, however, that increased delivery from the proximal tubule is necessary to demonstrate an effect of medullary tonicity on urinary sodium excretion. Micropuncture studies were designed to test that possibility by increasing distal delivery by 2% Ringer loading in animals with and without reduced medullary tonicity. In an initial series of experiments the alpha-adrenergic agonist clonidine was used to induce a water diuresis. When given alone, this agent caused a marked decrease in urine osmolality and an increase in urine flow rate but had no effect on proximal reabsorption in either superficial or juxtamedullary nephrons, and did not alter urinary sodium excretion. Volume expansion with 2% body weight Ringer solution resulted in a significant fall in proximal reabsorption and a trivial increment in sodium excretion. When this same degree of volume expansion was conferred on animals undergoing a water diuresis, a marked increase in absolute and fractional sodium excretion occurred. In a second group of studies medullary tonicity was reduced in the left kidney only by removal of the left ureter 1 h before micropuncture. When these animals were infused with 2% body weight Ringer solution, proximal reabsorption was decreased in juxtamedullary nephrons, and a marked increase in sodium excretion was observed only from the left kidney. Finally, the effect of water diuresis on fractional sodium delivery to the early and late distal tubule of superficial nephrons during 2% Ringer loading was evaluated. Delivery to both of these sites was comparable after 2% Ringer loading alone and during 2% Ringer loading plus water diuresis. From these data, we conclude that medullary tonicity does influence renal sodium handling but that this effect is manifest in the final urine only under conditions in which proximal reabsorption is decreased. The data also suggest that this effect is limited to juxtamedullary nephrons and is probably localized to the thin ascending limb of the loop of Henle.
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PMID:Effect of medullary tonicity on urinary sodium excretion in the rat. 707 54

The aim of this study, involving 25 female mongrel dogs, was to develop a technique of ureteroileal anastomosis that would 1) avoid the danger of ureteric obstruction and urinary extravasation and 2) prevent reflux, even when exposed to extreme pressures. The combined principle, developed ny Leadbetter and Clarke, offers 3 theoretically possible modifications that were successively applied to the ileal conduit. The technically simplest one as described by Kelalis and the long-tunnel-modification of the Leadbetter-Clarke technique, resulted in ureteric obstruction and high-pressure reflux, respectively, in a high percentage. The last modification of the combined principle, not described before, allows the ureter to develop free peristalsis, covered by ileal mucosa only and unimpeded by any muscular tension. Twelve renal units implanted according to this last technique were fully protected from reflux when subjected to a pressure of 25 cm. of water. High-pressure reflux was observed in 2 renal units only. When these 12 renal units were compared with 12 renal units implanted into the same ileal conduit accordingly to Cordonnier, a statistically significant difference as to the pyelonephritic involvement of the corresponding kidneys could be established with preponderance to the inflammatory changes on the refluxing side (p less than 0.05).
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PMID:A long-tunnel modification of the combined principle after Leadbetter and Clarke as true antireflux uretero-ileal anastomosis. 712 May 82

Retrograde movements of urine into the renal pelvic space (pelvic refluxes) were studied in anesthetized Munich Wistar rats and hamsters. The urine was made green by a continuous i.v. infusion of lissamine green in saline, and the experimental kidney was either placed on a shallow trough or left in situ. The renal pelvis was exposed and illuminated with a fiber optic light, and urine movements were observed through the transparent but intact pelvic wall. Urine was collected from both kidneys in the rats. In both rats and hamsters, the inner medulla of the kidney was analyzed for solutes at the end of the experiment. The experimental procedures did not interfere with the normal function of the experimental kidney, and the results were the same in rats and hamsters. During constant urine flow, full refluxes did not occur. Urine either moved straight down the ureter after it exited from the ducts of Bellini or it briefly bathed the papillary tip. In rats, full pelvic refluxes started approximately 0.8 min after a bolus injection (0.5 ml of isosmotic saline, i.v.), at a time corresponding to a steep rise in urine flow (2 microliter.min-2.100 g body wt-1). Following increased infusion rate, full refluxes were associated with an increase in urine flow of 0.05 g microliter.min-2.100 g body wt-1. Full refluxes were also seen in the hamsters following a bolus injection or increased infusion rate. Increasing intrapelvic pressure by 1 cm H2O also caused full pelvic refluxes. When full refluxes occurred, urine came into contact with all areas of the renal pelvis. Because full pelvic refluxes occur only during rising urine flow, this mechanism would bring urine with decreasing osmolality into contact with the outer medullary areas facing the pelvic space.
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PMID:Occurrence of renal pelvic refluxes during rising urine flow rate in rats and hamsters. 723 Jun 8

The main problem with urinary diversion via cutaneous ureterostomy is stomal stenosis. Results with experimental and clinical implants of carbon polymer stoma prostheses (max. clinical observation period: 31 months) for vesicostomies have encouraged us to find out whether implants of this material would be suitable for cutaneous ureterostomies as well. The first step was dilation of the ureters in 16 mongrel dogs, 4 mini pigs and 4 sheep. This was done by knotting a thread over a splint which had been introduced into the ureter. After 7 days the ureter was ligated prevesically and a carbon polymer stoma was implanted into the ureter. 37 of the 48 stoma implants were well tolerated and provided water tight urinary drainage; slight encrustation occurred, but, radiologically, a smooth flow of contrast medium was seen. Ten of these 37 cases had transient urinary leakage. Eleven of the 48 stoma implants were unsuccessful because of insufficient healing, urinary extravasation, parastomal inflammation or severe encrustations. The results of these experiments on animals would seem to justify initial clinical use. It is conceiveable that this way stomal stenosis of the cutaneous ureterostomy can be avoided.
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PMID:Experimental data on the application of a stoma prosthesis in cutaneous ureterostomy. 726 5

Cohen's ureteroneocystostomy is largely employed by many pediatric urologists, the only substantial criticism being the impossibility of endoscopic ureteral catheterization after this procedure. A method is described, based on the use of a catheter needle introduced on the filled bladder suprapubically, in a lateral position, opposite to the side of the ureter concerned. Adequate ureteral catheter is introduced on the venous catheter, using a common endoscopic rubber tip to maintain water tightness. Under endoscopic vision the ureteral catheter is easily inserted in the ureteral meatus and introduced in the ureter.
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PMID:[Catheterization of the ureter after anti-reflux reimplantation using the Cohen technic]. 730 21

The nephron segments involved in the renal tubular transport of digoxin and the direction of transport in each segment were evaluated using renal micropuncture techniques in 11 rats made diuretic by i.v. infusion of .85% saline. Tubular fluid was collected from 4 different sites along the nephron: late proximal, early distal, late distal, and ureter. The concentrations of 3H-digoxin and 14C-inulin were measured in each sample and the reabsorption of water and efflux of digoxin were calculated. Water was removed from the lumen along the entire length of the nephron and only 2.53 +/- 0.3% of the filtrate was excreted in the urine. Digoxin was also absorbed in the proximal convoluted tubule and in the loop of Henle. About 1/3 of the filtered drug exited in these early nephron segments probably by passive diffusion. In the distal convoluted tubule, digoxin was added to the tubular fluid. The fraction of digoxin present in the lumen increased form 64 +/- 3.8% of the filtered load at early distal site to 78.7% +/- 4.8% at late distal site indicating that an amount equal to 15% of filtered digoxin entered the tubule. This influx occurred against a concentration of 3-5, suggesting the existence of a carrier mediated or active transport mechanism in this nephron segment. Transport of digoxin beyond the late distal puncture site was negligible. The collecting duct appeared to be relatively impermeable to the drug since a concentration gradient of 30 or greater failed to cause its diffusion out of the tubule. The data indicate bidirectional transport of digoxin in the rat nephron. Efflux occurs primarily in the early nephron segments while net influx is limited to the distal convoluted tubule.
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PMID:Digoxin transport in the distal nephron of rats during saline diuresis. 732 67


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