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Biomedical subjects

R Hofmann

Publications and source records attributed to R Hofmann.

At least 19 recordsLinked to original sources
PubMed1995

Aortic valve replacement: is the stentless xenograft an alternative to the homograft? Early results of a randomized study.

From November 1992 to October 1993 we randomized 101 patients over 60 years of age undergoing elective aortic valve replacement, with or without concomitant coronary artery bypass grafting, to receive either a cryopreserved aortic or pulmonary homograft (n = 38) or a stentless porcine aortic valve xenograft (Edwards Prima 2500) (n = 63). The majority of all valves (92%) were inserted freehand in the subcoronary position. Six homografts (16%) were implanted as a free-root replacement and two xenografts (3%) were used as a mini root. There were four in-hospital deaths (4%), three in the homograft group and one in the xenograft group (homograft, 7.9% versus xenograft, 1.6%; p = not significant). Forty-one patients were followed at 3- to 6-month intervals for 9 +/- 2 months (3 to 14 months) and valve pathology was assessed routinely by means of color flow Doppler echocardiography. Two patients in the homograft group developed new aortic insufficiency grade II; all others remained with trivial or no valve incompetence. The mean gradient remained unchanged to immediate postoperative measurements (homograft, 5 +/- 1 mm Hg versus xenograft, 11 +/- 4 mm Hg; p < 0.001). Despite a slightly higher transvalvular gradient, xenografts achieved excellent initial results when compared to homografts. Ease of implantation and freedom from thromboembolism indicate that xenografts can be an acceptable alternative to homografts, particularly in older patients with small aortic annuli. Long-term studies assessing the durability of the xenograft are necessary for final evaluation.

Aged↗
PubMed1995

Negotiating ureteral stenoses and kinks with a hydrophilic wire.

Negotiating a tortuous or obstructed ureter with a wire can be time-consuming and sometimes tiring. The principle of using a slippery floppy wire and then replacing it with a stiff wire through a 5-french open-ended ureteral catheter yields a high success rate. The ureteral catheter can be used for a radiocontrast study and allows access for a 0.035 'coaxial wire', which can be used as a guide wire for a single or double J stent.

Humans↗
PubMed1995

Internally concealed cocaine: analytical and diagnostic aspects.

Thirty persons arrested at Frankfurt airport for smuggling internally concealed cocaine in 1993/1994 were investigated. An X-ray examination (in all 30 cases), immunochemical examination of urine (in 27 cases) and of saliva (in 20 cases) was performed in parallel. An X-ray examination gave positive results in all examined persons. EMIT cocaine metabolite assay (cut off 300 ng benzoylecgonine (BE)/mL) was positive in eight urine samples. After reducing the cut off to 150 ng BE/mL urine, eleven samples were classified as positive. The results were confirmed by means of chromatographic determinations. These findings showed limited role of immunological examination of urine as a screening test in suspected smuggling of internally concealed drugs. All saliva samples showed negative immunochemical results. The number of concealed containers ranged from 44 to 135 per person. The amount of cocaine hydrochloride found in particular cases ranged from 242 to 1050 g net weight, divided into containers weighing from 5.7 to 13.8 g. Drug packages were obviously machine-made. The packages smuggled by a particular person were uniform. However, a distinct interpersonal variability in drug packages was observed, in regard to the number of protective layers (4-7), size, weight, and cocaine purity. This may be helpful for the identification of production site. The leaching of cocaine from selected containers was investigated in a stirring bath and was independent of the conditions applied.

Adult↗
PubMed1994

Detection of aneuploid cells in acute lymphoblastic leukemia with flow cytometry before and after therapy.

We have evaluated the proliferative activity and DNA content of immunophenotyped hematopoietic cells applying flow cytometry. After indirect immunofluorescence the cell membrane was permeabilized for propidium iodide staining of DNA. Compared with single parameter detection of DNA content this method has more certainty in the determination of aneuploidies in lymphatic leukemia cells. Immunophenotyped residual normal hematopoietic cells were used as an internal standard. If this method was tested for evaluation of therapeutic effects after chemotherapy greater sensitivity in detection of minimal residual disease was observed than when using microscopic evaluation or single parameter DNA analysis in cases of aneuploid lymphoblastic leukemias.

Aneuploidy↗
PubMed1994

[Nerve preserving retroperitoneal lymph node excision in non-seminomatous testicular cancer].

Thirty-nine patients with a non-seminomatous testicular tumor underwent retroperitoneal lymphadenectomy (RPLND) between 12/90 and 7/93. Twenty-four patients with stage I disease were operated on with a modified nerve-sparing RPLND, while 7 patients with stage IIA and 8 patients with stage IIB had bilateral RPLND. Twelve of fifteen patients with stage IIA and IIB had preservation of their sympathetic postsynaptic fibers. Intraoperative electric stimulation of the fibers resulted in ejaculation in 25/26 patients. Semen analysis revealed 21 patients with necrospermia and maturation arrest, while 3 had aspermia. Antegrade ejaculation was restored after 1.1 months following nerve-sparing RPLND and 7 months following radical RPLND. Ejaculation did not return in one patient. No patient showed relapse. Our results show that the sympathetic postsynaptic fibers can be preserved during RPLND. Nerve-sparing RPLND is superior to radical and modified RPLND with regard to preservation of ejaculation without compromising the radicalness of the tumor surgery.

Adult↗
PubMed1994

[Microsurgical techniques in urology].

Microsurgery is an established operative technique for refertilization by vasovasostomy, tubulovasostomy and microsurgical epididymal sperm aspiration. Other andrological indications for the use of a microscope are penile revascularization, resection of varicocele and surgical treatment of Peyronie's disease. Autotransplantation of intra-abdominal testicles and hypospadia correction are indications for microsurgical techniques in pediatric urological surgery. Renal transplant, sex-change surgery and replants of penis and scrotum are further indications for use of microsurgery. Microsurgery will move into new fields of urological surgery, especially neurourology.

Adult↗
PubMed1994

[Microsurgical therapy of occlusive azoospermia].

From 5/88 to 8/93 148 patients were operated on for obstructive azoospermia using a microsurgical technique. In 68 patients we performed a vasectomy reversal by vasovasostomy (VT), 42 patients underwent a tubulovasostomy (TT), and 8 patients had a VT with contralateral TT. Two patients had implantation of an alloplastic spermatocele, 9 patients had microsurgical epididymal sperm aspiration (MESA), and 19 patients microsurgical exploration. Patency was achieved in 89% of patients after VT and in 32% after TT. A pregnancy occurred in 34% after VT and in 13% after TT. No pregnancy was achieved after MESA or alloplastic spermatocele. A microsurgical procedure is necessary for the treatment of congenital or acquired obstructive azoospermia.

Adult↗
PubMed1993

Motility and intraluminal pressure of the ileocolonic junctional zone and adjacent bowel in a canine model.

The exact role of the ileocecal valve (ICV) at the junction of small and large bowel is not well understood. Bowel segments used for the construction of urinary reservoirs incorporate the ICV. In the Indiana pouch its natural continence is used as one principle for achieving continence of the efferent limb. Motor activity and pressure in the ICV, the ileum and colon were registered in eight dogs. Myogenic activity of the bowel consisted of slow waves, irregular spontaneous contractions and superimposed spikes. Pressures of 7.2 +/- 0.3 cmH2O were recorded in the ileum and of 5.6 +/- 0.4 cmH2O in the colon. The pressure in the ICV was 12.7 +/- 0.4 cmH2O rising to 26.4 +/- 2.2 cmH2O during spontaneous depolarization. Balloon dilatation of the ileum resulted in relaxation of the ICV in 76% of experiments, whereas colonic distension was followed by a pressure increase in the ICV region in 80% of experiments. In 16% of cases a relaxation of the ICV area and a weaker response after repeated dilatation was noted. These findings make the ICV an unreliable continence mechanism as its long-term continence can not be predicted despite intraoperative evaluation. Additional measures to ensure consistent continence at the ICV (e.g. electric stimulation) need to be studied.

Animals↗
PubMed1993

Stimulated pressure response of the ileocolonic junctional zone and its use as a continence mechanism in a canine model.

Mechanisms for maintaining passive continence in the efferent limb of urinary diversions include compression of tissue, peristalsis, equilibration of pressure and use of valves. Motor activity and pressure in the ileum, ileocecal valve (ICV) and the colon were evaluated in dogs. Spontaneous activity and pressure were compared with stimulated pressure response and activity. Stimulation was performed at the pelvic nerve and the small nerves in the mesenterium, as well as direct neurostimulation of the bowel. Resting pressure at the ICV was 12.7 +/- 0.4 cmH2O rising to 26.4 +/- 2.2 cmH2O during spontaneous depolarization. Stimulation of the pelvic nerve resulted in increased colonic motor activity with unchanged pressure. Electric stimulation of small mesenterical nerves to the ICV increased pressure in the ICV to 35.0 +/- 4.1 cmH2O, while direct myoelectric stimulation of the ICV zone increased the intraluminal pressure to 75.0 +/- 3.2 cmH2O. Termination of the electric stimulation was followed by a slow decrease of pressure to the resting level over a period of 30-45 s. Maintaining continence at the ICV with long-term constant or intermittent stimulation seems feasible.

Animals↗
PubMed1993

Effects of nerve stimulation on blood flow in the urinary bladder, urethra and pelvic floor in the dog.

Pelvic organs have triple innervation from the pelvic, sympathetic and pudendal nerves. Peripheral effects can be studied by neurostimulation of the nerves, whereas the topography of the spinal cord neurons can be determined by horseradish peroxidase tracing. We have evaluated the neurophysiologic effects of the nerves at their target organs by intraoperative electric stimulation and compared the effects to the anatomical innervation areas. These zonal areas were determined by blood flow alterations, measured with nine different microspheres. Pelvic nerve stimulation showed bladder contraction with no significant blood flow changes during stimulation. Sympathetic nerve stimulation caused moderate detrusor contraction and pressure increase in the bladder neck and intraprostatic area. Regional blood flow showed a four-fold increase in the bladder neck area during neurostimulation. Pudendal nerve stimulation revealed an intraurethral pressure increase with a 3.5-fold increase of blood flow in the sphincteric area and in the pelvic floor musculature.

Animals↗
PubMed1992

Scatter factor is a glycoprotein but glycosylation is not required for its activity.

Scatter factor (SF) is a protein produced by fibroblasts, smooth muscle cells, and human placenta which scatter cohesive epithelial cell colonies and increases cellular motility. SF bound to concanavalin A and other lectins with high affinity. SF could also be stained with a glycoprotein specific stain. Incubation of producer cells (N-ras-transformed 3T3), with tunicamycin homolog A1 did not have any significant effect on the secretory activity of SF. The treatment of SF with N- and O-glycanases as well as endoglycosidase H had no effect on its activity. However, treatment of target (Madin Darby canine kidney) cells with tunicamycin A1, abolished the scattering response. These studies suggest that scatter factor is a glycoprotein, but glycosylation is not required for its secretion or activity by the producer cells; however, glycosylation of proteins in the target cells is required for SF action.

3T3 Cells↗
PubMed1992

Endoscopic and open stone surgery in morbidly obese patients.

Management of urinary stone disease in the morbidly obese patient can be troublesome and problematic. We present 4 recent female patients with an average weight of 442 pounds and an average height of 5 feet 2 inches. The patients underwent a total of 8 open surgical or endoscopic procedures for partial or complete staghorn calculi. Complications encountered included inability to reach the stones with rigid or flexible ureteroscopes, inadvertent incision above the 10th rib for pyelolithotomy, intraoperative rhabdomyolysis during a flank incision, consecutive temporary renal failure and wound infection. We discuss the limitations of extracorporeal shock wave lithotripsy, retrograde endoscopic manipulation, percutaneous antegrade surgery and open surgical approaches. Such patients continue to represent diagnostic challenges and high risk therapeutic options.

Adult↗
PubMed1992

Renal artery embolism: clinical features and therapeutic options.

Renal artery embolism is an infrequent but important cause of renal loss. However, due to its rarity and nonspecific presentation diagnosis is often delayed and occasionally missed. Furthermore, proper therapeutic intervention is not well established and aggressive surgical management is often ill-advised. We review the literature and present 3 cases seen recently at our institution. Selective intra-arterial infusion of thrombolytic agents appears to be the most favorable treatment. The duration of occlusion does not necessarily correlate with the return of renal function, and the degree of collateral renal blood flow can be important.

Adult↗
PubMed1992

Ureteroscopy without routine balloon dilation: an outcome assessment.

A retrospective analysis of 156 rigid ureteroscopic stone procedures in 145 patients revealed successful manipulation in 90%. The stone-free rate after adjunctive procedures was 95%. Access was achieved without balloon dilation in all but 18 patients. There were 24 perforations, occurring in 31% of proximal, 8% of mid ureteral and 8% of distal stone manipulations. Of the evaluable patients 63% underwent radiographic assessment for stricture disease, 75% at 6 months or more after the procedure. The stricture rate was 3.5% in all patients and 5.9% in patients with perforations. Of 37 patients evaluated for vesicoureteral reflux only 1 had reflux. Questionnaire followup was obtained for 74% of the patients (mean followup 2.6 years) and 32% felt normal within 3 days. Postoperative symptoms included flank pain (13%), renal colic (12%), pelvic discomfort (30%) and Double-J stent related complaints (49%). Of the patients 15% have reported recurrent stones. Ureteroscopy is effective and well tolerated, and it has minimal long-term complications.

Catheterization↗
PubMed1992

Pyonephrosis: diagnosis and treatment.

A series of 23 confirmed cases of pyonephrosis initially treated by percutaneous nephrostomy drainage were reviewed. Presentation was extremely variable, ranging from sepsis to asymptomatic bacteriuria. Fever, flank pain and leukocytosis were often absent. Ultrasonography was diagnostic in only 3 of 12 patients. In all, 17 patients had associated nephrolithiasis, and 5 patients ultimately required nephrectomy. Renal urine cultures were positive in 16 of 21 instances, with multiple organisms found in 8 of 21, and added bacteriological data not provided by bladder urine cultures in 11 cases. A pre-existing history of urinary tract infection, hypertension and malignancy was common. Percutaneous drainage was a safe, quick and effective diagnostic and therapeutic method.

Adult↗