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Biomedical subjects

D Rohrmann

Publications and source records attributed to D Rohrmann.

At least 19 recordsLinked to original sources
PubMed2001

Magnetic resonance urography in children: evaluation of suspected ureteral ectopia in duplex systems.

PURPOSE: We evaluate the diagnostic accuracy of magnetic resonance urography in children with suspected ectopic ureters and ureteroceles in duplex systems. MATERIALS AND METHODS: A total of 14 children 4 weeks to 8 years old with a total of 18 duplex systems underwent magnetic resonance urography using a 1.5 tesla scanner. After injection of low dose furosemide, half-Fourier rapid acquisition with relaxation enhancement images were obtained for T2-weighted static fluid magnetic resonance urography. Respiratory gated 3-dimensional gradient echo images were acquired for T1-weighted excretory magnetic resonance urography 5 to 30 minutes after intravenously administered gadolinium. RESULTS: All magnetic resonance examinations were successfully performed without sedation. The diagnostic accuracy of T1-weighted excretory magnetic resonance urography depended on the renal function. Twelve duplex systems with a normal excretory function, including 6 bifid ureters and 6 upper moieties with inferomedial ectopic ureters, were analyzed correctly with the exception of a 6 mm. ureterocele in 1 case. In 6 duplex systems with poor or nonfunctioning upper moieties ectopic ureters were only demonstrated on T2-weighted magnetic resonance urograms. CONCLUSIONS: Respiratory gated excretory and static fluid magnetic resonance urography complement each other in the evaluation of duplex systems in children and provide high accuracy in the evaluation of suspected ectopic ureters and ureteroceles.

Child↗
PubMed2001

[Gadolinium-enhanced T(1)-weighted MR urography versus T(2)-weighted (HASTE) MR urography in children].

PURPOSE: To evaluate gadolinium-enhanced T(1)-weighted excretory MR urography (EMRU) versus T(2)-weighted (HASTE) MR urography in children with upper urinary tract abnormalities. PATIENTS AND METHODS: In a prospective study 63 children, aged from 3 weeks to 15 years, underwent MR urography in a 1.5-T scanner. Before and after an intravenous injection of 0.05 mg/kg body weight of furosemide, respiratory-triggered HASTE images were obtained for T(2)-weighted MR urography. EMRU was performed subsequent to i. v. gadolinium injection with respiratory-gated, coronal 3 D-gradient-echo sequences. RESULTS: Compared to T(2)-weighted (HASTE) MR urography, gadolinium-enhanced MR urography revealed a superior diagnostic accuracy in non-dilated collecting systems (horseshoe kidneys, ectopic kidneys, duplex systems, single ectopic ureters, ureteroceles). EMRU and T(2)-weighted (HASTE) MRU turned out to be equivalent in the assessment of obstructed but normal functioning upper urinary tracts (UPJ obstructions, megaureters). Non-functioning dilated collecting systems and multicystic dysplastic kidneys were best visualized with use of T(2)-weighted (HASTE) MR urography. CONCLUSION: Respiratory-gated gadolinium-enhanced T(1)-weighted MRU allows accurate evaluation of most upper urinary tract abnormalities. T(2)-weighted (HASTE) MRU complements GMRU in the evaluation of non-functioning renal units and cystic disease of the kidneys.

Adolescent↗
PubMed2001

Buttock placement of the implantable pulse generator: a new implantation technique for sacral neuromodulation--a multicenter study.

OBJECTIVE: In the standard operation procedure for sacral neuromodulation, the implantable pulse generator (IPG) is implanted in a subcutaneous pocket at the lower part of the anterior abdominal wall. This procedure requires a long operation time and three incisions. With the IPG in the abdominal wall, some patients complain of displacement or pain at the IPG site postoperatively. By modifying the technique of placement of the IPG, these disadvantages are overcome. METHODS: Between August 1999 and July 2000, 39 patients underwent a buttock implant of the IPG. In 2 of these patients the position of the IPG was changed from abdominal region to the buttock. During follow-up, complications concerning the operation and location of the IPG were compared to the published literature. RESULTS: Operation time is reduced in all patients by approximately 1 h. No repositioning of the patient is required during surgery. Only a short subcutaneous tunnel is required to connect the lead to the IPG. Pain at the level of the IPG was noted in 10% of the patients, which needed no further treatment. No infections were seen and the IPG did not displace postoperatively. CONCLUSION: Buttock placement of the IPG in sacral nerve stimulation leads to shorter operation time; only two incisions are needed instead of three and a shorter subcutaneous tunnel is needed. Using this technique there are less complications and a lower re-operation rate.

Adult↗
PubMed2000

[In vitro analysis and animal experiment study of surface modified biodegradable polylactide ureteral stents].

With the objective of developing a biodegradable ureteric stent, various polylactides were analyzed and grafted with a clinically adapted surface. Stent moulding was performed by CESP technology (Controlled Expansion of Saturated Polymers), which is not based on high temperature but gas-loading under high pressure which induces a foamy bulk structure. The hydrolytically biodegradable, synthetic homo- and copolymers poly(D,L-lactide) (PDLLA), poly(D,L-lactide-co-trimethylene-carbonate) (PDLLA-co-TMC), poly(D,L-lactide-co-glycolide) (PDLLA-co-Gly) as derivatives of lactic acid or glycolic acid and surface modifications with hydroxyethylene-methacrylate (HEMA) and oligoethyleneoxidemonomethacrylate (OEOMA) were analyzed with regard to cytotoxicity and cell adhesion. Methacrylates have minimized protein and cell adhesion and degradation of non-toxic products. All polymers exhibited a high degree of biocompatibility and cell adhesion was markedly reduced following HEMA grafting. A 3 cm and 7 Charrière prototype of the stent was moulded from PDLLA-co-TMC by CESP-technology, and grafted with HEMA by means of plasma-induced polymerization. Finally, the stents were implanted into female sheep, following unilateral ureterotomy. Regular blood and urine analysis as well as ultrasound and the final autopsy revealed no pathological findings. Histopathological analysis exhibited a regular epithelium without any changes being determined by contact to the stent, and a good regeneration of all layers in the area of anastomosis.

Anastomosis, Surgical↗
PubMed2000

Feasibility and utility of respiratory-gated, gadolinium-enhanced T1-weighted magnetic resonance urography in children.

RATIONALE AND OBJECTIVES: To evaluate the feasibility and utility of respiratory-gated, gadolinium-enhanced T1-weighted magnetic resonance (MR) urography in children. METHODS: In a prospective study, 30 consecutive children, aged 3 weeks to 13.8 years, underwent MR urography. After intravenous injection of low-dose furosemide and gadopentetate dimeglumine, respiratory-gated, coronal, T1-weighted 3D-gradient-echo sequences were obtained at 1.5 T 5 to 30 minutes after contrast administration. Postprocessing of the data was performed using a maximum-intensity projection algorithm. In addition, precontrast half-Fourier rapid acquisition with relaxation enhancement MR urograms were obtained in 29 children. RESULTS: Respiratory-gated, T1-weighted MR urography was successfully performed in all children without the need for sedation. Compared with the final diagnosis, prospective analysis of MR urography images revealed the correct diagnosis in 56 of 58 pelvicaliceal systems (96%). The ureteral morphology was correctly evaluated in 59 of 64 ureters (92%). The method showed limited efficiency for evaluating nonfunctioning renal units. CONCLUSIONS: Respiratory-gated, gadolinium-enhanced T1-weighted MR urography is a feasible and effective diagnostic tool in the assessment of upper urinary tract morphology in children. It is especially useful in depicting nondilated collecting systems and ureters.

Adolescent↗
PubMed1999

Mitochondrial and mitochondrial-related nuclear genetic function in rabbit urinary bladder following reversal of outlet obstruction.

Partial outlet obstruction of the rabbit urinary bladder causes increased tissue hypertrophy and decreased contractility of that organ; we showed that, in an experimental rabbit model, both correlate closely with alterations in the status and expression of mitochondrial (mt), and mt-related nuclear, genetic parameters in bladder smooth muscle. Here we investigate the rate and overall level of recovery of mt and nuclear genetic function following reversal of outlet obstruction in the same animal model. Release from outlet obstruction at 28 days resulted in improvement in both level of hypertrophy and contractile function in all bladders studied. However, bladders fell into two groups based on whether relative copy mt genome number per cell was above or below that of unobstructed controls. Bladders with high mt DNA content adjusted organellar genome copy number toward normal post-reversal but did not properly adjust mt transcript levels; mt-related nuclear transcripts in these samples showed recovery. Bladders with low mt DNA content showed no adjustment of those levels toward normal post-reversal but did show some adjustment in other mt and nuclear genetic parameters. Thus, a limiting factor for return of normal bladder function following reversal of outlet obstruction may be recovery of normal mt genetic performance.

Animals↗
PubMed1997

Compliance of the obstructed fetal rabbit bladder.

We evaluated compliance in the developing bladder using a newly developed animal model of posterior urethral valves: partial infravesical obstruction in the fetal rabbit bladder. Partial bladder outlet obstruction was created in fetal rabbits at day 23 of a 31 to 32-day gestation period. An in vitro whole bladder preparation provided data on compliance and an isolated bladder strip preparation provided data on the mechanical properties of the bladder wall. In addition, the influence of calcium on both preparations was evaluated. Partial bladder outlet obstruction in the fetal rabbit resulted in a markedly larger bladder weight (246.4 +/- 22.3 mg, n = 14) than control bladders (90.2 +/- 5.7 mg, n = 13). Isolated smooth muscle strips from obstructed and normal bladders revealed identical stretch-stress patterns. In contrast, obstructed bladders had significantly increased compliance in the whole bladder preparation. Since the increase in compliance was not correlated to mechanical properties of the isolated bladder strips, it must therefore result from the pattern of mass increase of the whole bladder wall. During filling, both the control and obstructed bladders had the same slow, large amplitude spontaneous contractions. In addition, both had rapid contractions: those in the obstructed bladders had significantly lower frequency and higher amplitude than the ones in the control bladders. Removing the calcium from the organ bath eliminated the spontaneous contractions but did not change the baseline pressure or force values, indicating that the compliance of these fetal rabbit bladders is a function of the passive properties of the bladder wall. Three main patterns occur in cystometrograms of patients with posterior urethral valves: myogenic failure, hyperreflexic bladders, and low compliance bladders. Using our model of partial outlet obstruction in the fetal rabbit bladder, we could not imitate the group with low compliance. We therefore hypothesize that the different patterns of bladder dysfunction associated with posterior urethral valves are due to infravesical obstruction occurring with different severities or at different ages of gestation.

Animals↗
PubMed1997

Partial bladder outlet obstruction in the fetal rabbit.

PURPOSE: We developed and tested an animal model of bladder dysfunction due to posterior urethral valves using partial outlet obstruction of the fetal rabbit bladder. MATERIALS AND METHODS: Partial bladder outlet obstruction of fetal rabbit bladders was created on day 23 of gestation. Of the litter of 8 to 10 fetuses half was obstructed and the remainder served as controls. The doe and fetuses were sacrificed on day 30 of gestation (full term 31 to 32 days) and the fetal bladders were removed. Bladders that had doubled in weight from the average bladder weight of the control littermates were deemed sufficiently obstructed. Hematoxylin and eosin staining was performed and bladder strip response to 32 Hz. field stimulation, 200 microM. bethanechol and 200 mM. potassium chloride was measured. RESULTS: Average body weight did not differ between the control and obstructed fetuses, indicating that surgery did not hinder fetal development. Hematoxylin and eosin staining confirmed smooth muscle cell hypertrophy and increased connective tissue in the obstructed bladders. Obstructed bladder strips responded significantly less to field stimulation, and significantly more to bethanechol and potassium chloride (mean plus or minus standard deviation 5.18 +/- 1.52, 6.29 +/- 1.3 and 10.15 +/- 2.18 x force per/100 mg. tissue, respectively)than control bladder strips (9.0 +/- 1.19, 3.5 +/- 0.46 and 6.16 +/- 1.33 x force per/100 mg. tissue, respectively) suggesting that denervation supersensitivity may have resulted from obstruction. CONCLUSIONS: Partial outlet obstruction of the fetal rabbit bladder results in bladder hypertrophy and dysfunction but these changes are markedly different from those in the adult rabbit. Since rabbit fetal development is delayed compared to human fetal development, this model can be used to assess the consequences of posterior urethral valves.

Animals↗
PubMed1997

The operative management of recurrent ureteropelvic junction obstruction.

PURPOSE: Surgical repair of ureteropelvic junction obstruction is successful in 98% of cases. We evaluated children undergoing repeat pyeloplasty and discuss the etiology of recurrent ureteropelvic junction obstruction, surgical approach and outcome. MATERIALS AND METHODS: Between 1982 and 1996, 366 children with ureteropelvic junction obstruction were surgically treated at our institution, including 16 who presented with recurrent ureteropelvic junction obstruction and required surgery. RESULTS: Repeat repair was successful in all 16 patients, including ureterocalicostomy in 3 and dismembered pyeloplasty in the remainder. No nephrectomy was necessary. Anteriorly elongated flank incisions were made in all cases. Dense scar tissue around and obstructing the ureteropelvic junction was noted in the majority of cases. In 7 patients a redundant pelvis resulted in a kink at the ureteropelvic junction. A nephrostomy tube was placed in all cases and an additional transanastomotic stent was used in all but 2. Obstruction was relieved with 1 operation. CONCLUSIONS: A redundant pelvis resulting in a kink at the ureteropelvic junction may contribute to a higher change of urinary leakage and subsequent obstructive scar formation in cases of failed pyeloplasty. Before repeat surgery anatomy should be precisely identified by antegrade and retrograde studies. The surgical approach usually involves identifying the ureter below the area of the previous surgery and then ensuring a tension-free anastomosis. If inadequate ureteral length or an intrarenal pelvis precludes direct anastomosis, ureterocalicostomy is an alternative. A nephrostomy tube and transanastomotic stent are advisable. Nephrectomy is rarely necessary and a good functional result can be anticipated.

Child↗
PubMed1996

Effect of thapsigargin on the contractile response of the normal and obstructed rabbit urinary bladder.

Excitation-contraction coupling is achieved by translocation of calcium from the extracellular space as well as by the release of calcium from intracellular stores. Thapsigargin has been shown to selectively block the sarcoplasmic Ca-ATPase, thereby preventing the reuptake of calcium into intracellular stores and the participation of these calcium storage sites in the contractile response to stimulation. The current study determined the effect of thapsigargin on the contractile response to field stimulation, bethanechol, and KCl in control rabbit bladders and bladders obtained from rabbits subjected to partial outlet obstruction. Partial bladder outlet obstruction resulted in a marked increase in bladder mass and in significant decreases in the contractile response to field stimulation, bethanechol, and KCl. Thapsigargin (5-40 microM) had no effect on the contractile responses of bladder strips isolated from control rabbits to field stimulation, bethanechol, or KCl. However, bladder strips isolated from obstructed rabbits showed a significant concentration-dependent decrease in the contractile response to field stimulation in the presence of thapsigargin. Thapsigargin had no effect on the contractile responses of bladder strips isolated from obstructed rabbits to either bethanechol or KCl. In general, the data described in this study support our current hypothesis: as smooth muscle cells enlarge (hypertrophy) and the cell volume increases, there is an increased dependence on the release of intracellular calcium from the sarcoplasmic reticulum to mediate the contractile response to field stimulation.

Animals↗
PubMed1996

Diagnostic and therapeutic laparoscopy of the nonpalpable testis.

We report about laparoscopic examination and treatment of 19 patients with 25 non-palpable testes. Thirteen patients presented with unilateral and six patients with bilateral absent testes, respectively. In all cases of non-palpable testes laparoscopy was able to determine the exact localization and supported the surgical approach. Six testicles were treated by open orchiectomy after diagnostic laparoscopy; three testes were fixed by laparoscopically assisted orchiopexy. Three patients (three testicles) were treated by standard orchiopexy after laparoscopy and in three cases microvascular autotransplantation was performed. Laparoscopically, five aplastic testicles without vas and vessels were diagnosed. Three testes were considered as vanishing and in two patients (two testes) due to previous surgical exploration elsewhere testicular remnants were totally atrophic and were resected with the adjacent vas. All laparoscopic findings except the vanishing testis syndrome were proven either by open surgery or by laparoscopic preparation of the internal inguinal ring.

Child↗
PubMed1996

Protective effect of Tadenan on bladder function secondary to partial outlet obstruction.

PURPOSE: Tadenan (DEBAT, Paris, France) is a pharmaceutical agent used in the treatment of benign prostatic hyperplasia (BPH). The specific aim of this study was to determine if pretreatment of rabbits with Tadenan reduced either the hypertrophic response of the bladder to partial outlet obstruction or the accompanying contractile dysfunction. MATERIALS AND METHODS: Twenty-five male New Zealand rabbits (3 to 5 kg.) were separated into 5 groups of 5 rabbits each. Each rabbit in groups 1,2, and 3 received Tadenan orally at 1, 10 and 100 mg./kg./day for 3 weeks. Group 4 received vehicle only (peanut oil); Group 5 were controls. The bladders were evaluated (in vitro studies) after 2 weeks of obstruction. RESULTS: 1) Tadenan did not reduce the effect of partial outlet obstruction on bladder mass. 2) Tadenan pretreatment resulted in a significant protective effect on the contractile responses to field stimulation, bethanechol and KCl. CONCLUSIONS: These results clearly demonstrate that Tadenan pretreatment protected the bladder from the contractile dysfunctions induced by partial outlet obstruction.

Adenosine Triphosphate↗
PubMed1996

The decompensated detrusor I: the effects of bladder outlet obstruction on the use of intracellular calcium stores.

PURPOSE: As in other smooth muscle groups, extracellular calcium influx as well as the release of calcium from intracellular storage sites or sarcoplasmic reticulum occur in response to receptor stimulation. The relative participation of extracellular influx versus intracellular release has recently been shown to be influenced by developmental stage and obstruction. Partial bladder outlet obstruction results in marked hypertrophy of the bladder and produces alterations in contractile function. To understand better how this contractile dysfunction after outlet obstruction is influenced by intracellular calcium handling we tested the effects of 2 drugs with known effects on the sarcoplasmic reticulum. MATERIALS AND METHODS: We evaluated ryanodine, which blocks the release of calcium from the sarcoplasmic reticulum, and thapsigargin, which blocks the ability of the sarcoplasmic reticulum to pump cytosolic calcium back into the storage sites. Rabbit bladders were obstructed for different periods, after which detrusor muscle strips were harvested and contractile performance was evaluated in the absence and presence of ryanodine and thapsigargin. RESULTS: In the early phases of outlet obstruction the release of intracellular calcium increased significantly. With prolonged obstruction and detrusor decompensation the intracellular storage sites lost the ability to contribute to the generation of contractile force. CONCLUSIONS: Alterations in the calcium handling ability of the smooth muscle cell appear to have an important role in the process of decompensation of bladder function in infravesical obstruction.

Animals↗
PubMed1996

The decompensated detrusor II: evidence for loss of sarcoplasmic reticulum function after bladder outlet obstruction in the rabbit.

PURPOSE: While it may lack the classic morphological pattern in striated muscle systems, there is ample evidence that smooth muscle also contains sarcoplasmic reticulum. These intracellular storage sites release calcium into the cytosol to generate contractile force in response to various stimuli. A major component of the sarcoplasmic reticulum is an adenosine triphosphate dependent ion pump, which serves to drive free calcium out of the cytosol back into this intracellular reservoir. This ion pump serves to maintain the intracellular calcium storage sites, and also as a marker of the sarcoplasmic reticulum. MATERIALS AND METHODS: Muscle strip studies were performed to stratify the data into 3 major groups (controls, and compensated and decompensated obstructions) based on physiological performance. These were correlated with biochemical and molecular determinations of sarcoplasmic endoplasmic reticulum calcium, magnesium-adenosinetriphosphatase expression. RESULTS: Our results demonstrate a remarkable loss of sarcoplasmic endoplasmic reticulum calcium-adenosinetriphosphatase activity in the decompensated group and a moderate loss in the compensated group. CONCLUSIONS: These data provide molecular support for our previous physiological studies in which we demonstrated an important role for intracellular calcium storage and release with normal bladder smooth muscle function. These data strongly support our contention that contractile dysfunction in bladder smooth muscle following outlet obstruction is partially mediated by changes in the mechanisms of intracellular calcium homeostasis.

Animals↗
PubMed1996

Effects of tadenan pretreatment on bladder physiology and biochemistry following partial outlet obstruction.

PURPOSE: Tadenan is a pharmaceutical agent used in the treatment of BPH. Prior studies demonstrated that pretreatment of rabbits with Tadenan significantly reduced the contractile dysfunction following two weeks of partial outlet obstruction. The specific aim of the present study was to determine the effect of Tadenan pretreatment on the time course of the response to partial outlet obstruction and correlate the effect of Tadenan on the contractile responses to field stimulation, bethanechol, and KCl with both mitochondrial enzyme activity (citrate synthase) and sarcoplasmic reticular function (calcium-ATP'ase activity). MATERIALS AND METHODS: Sixty male New Zealands white rabbit (3 to 5 kg.) were separated into 12 groups of 5 rabbits each. Each rabbit in groups 1-6 received Tadenan orally at 100 mg./kg./day for three weeks; each rabbit in groups 7-12 received vehicle (peanut oil). Each rabbit in groups 2-6 and 8-12 received a partial outlet obstruction as described below. One group of Tadenan treated and one group of vehicle-treated rabbits were euthanized at 1, 3, 5, 7, and 14 days following partial outlet obstruction. The non-obstructed groups were studied after 4 weeks of drug or vehicle treatment. Each bladder was rapidly removed and weighed, and 3 longitudinal strips prepared and mounted in individual baths for contractile studies. The remainder of the bladder was frozen for biochemical analysis. The contractile responses to field stimulation, bethanechol, and KCl were determined; and the enzyme activities of citrate synthase (marker for mitochondrial function) and calcium-ATP'ase (marker for sarcoplasmic reticulum) were determined. RESULTS: 1) Tadenan did not reduce the effect of partial outlet obstruction on bladder mass. 2) Although the contractile responses to forms of stimulation were reduced at 1 day following partial outlet obstruction, Tadenan pretreatment resulted in a significant protective effect on the contractile responses to field stimulation, bethanechol, and KCl at 3, 5, 7, and 14 days of obstruction. 3) The activities of both citrate synthase and calcium ATP'ase were reduced significantly at 1 day following obstruction for both Tadenan treated and vehicle treated groups. The activities of both enzymes returned to near normal levels at 7 and 14 days for the Tadenan groups whereas the activities of both enzymes remained significantly reduced in the vehicle treated groups. CONCLUSIONS: These results clearly demonstrate that Tadenan pretreatment protected the bladder from both the contractile and metabolic dysfunctions induced by partial outlet obstruction.

Adenosine Triphosphate↗
PubMed1996

Alloplastic replacement of the urinary bladder.

PURPOSE: The loss of a functioning bladder is nowadays mostly managed by replacement with gastrointestinal segments. Management of these urinary diversions is difficult and the long-term effects are unknown. We developed a silicone rubber prosthesis for alloplastic replacement of the urinary bladder and tested it in an animal experiment. MATERIAL AND METHODS: Two artificial bladders were implanted into subcutaneous pockets on each side of the anterior abdominal wall. Cystectomy was performed and each prosthesis was connected to one kidney. Distally, a Y-shaped tube sutured to the urethral stump joined the two bladder outlets. The whole system was successfully implanted in 5 sheep with a mean follow-up of 11.5 months (5-19 months). RESULTS: Adequate capacity, effective and reliable mechanical function and patent anastomoses to the renal pelvis and the urethra could be achieved. Blood chemistry and renal ultrasound were performed at regular intervals demonstrating neither morphological nor functional deterioration of the renal parenchyma. Histopathological examination in the end of the experiment confirmed the excellent clinical results. CONCLUSIONS: The positive outcome of these animal experiments suggests this system would be useful for human bladder substitution. Standardized industrial production of the prostheses will be needed prior to implantation in humans.

Animals↗
PubMed1995

Biofeedback in the treatment of voiding disorders in childhood.

Voiding disorders are a common problem in pediatric urology. Biofeedback is a non-invasive method in the treatment of voiding disorders in childhood. Biofeedback takes aim at the learning or relearning of influencing involuntary functions. We report about our preliminary results of biofeedback training in the treatment of the enuretic syndrome in children. Out of 26 children with pseudo-detrusor-sphincter-dyssynergy 17 could be completely cured and 5 improved considerably. Out of 21 children with motor urgency 9 could be completely cured and 7 children improved. Biofeedback is a successful method to treat children with the enuretic syndrome.

Biofeedback, Psychology↗