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Biomedical subjects

M K Willscher

Publications and source records attributed to M K Willscher.

At least 19 recordsLinked to original sources
PubMed1997

Development of a smart holmium:YAG laser lithotriptor.

BACKGROUND AND OBJECTIVE: The purpose of this study was to develop a feedback control system for the pulsed holmium:YAG medical laser that enhances tissue selectivity and safety by discriminating between soft and hard biological tissue such as urinary and biliary calculi and bone. STUDY DESIGN/MATERIALS AND METHODS: The ability to discriminate is achieved by monitoring prompt laser-induced visible/NIR photoemissions via retrograde transmission over the laser delivery fiber in conjunction with a developed detection algorithm. RESULTS: Experimental data are presented for a system that employs this discrimination scheme with an electro-optic shutter for rapid intrapulse feedback control of holmium laser-based lithotripsy procedures. The results demonstrate the feasibility of a lithotriptor that can deliver 1 J per pulse to calculi yet limit errant discharges to surrounding urinary tract tissue to < or = 0.1 J. CONCLUSION: Based on animal tissue safety data, the laser margin of safety is improved by an order of magnitude.

Algorithms↗
PubMed1988

Safety and efficacy of electrohydraulic lithotripsy by ureteroscopy.

Electrohydraulic lithotripsy, when performed blindly for ureteral calculi in the past, resulted in frequent ureteral perforation and, therefore, it was considered to be unsafe. A total of 33 patients from 5 institutions underwent electrohydraulic lithotripsy for ureteral calculi under direct vision. There were only 3 minor ureteral perforations treated by ureteral catheter drainage. All patients were free of stones after treatment and there were no long-term complications. Electrohydraulic lithotripsy by ureteroscopy is considered to be a safe and effective method for fragmentation and removal of large ureteral calculi.

Adult↗
PubMed1988

The effect of a low dose of intrathecal morphine on impaired micturition reflexes in human subjects with spinal cord lesions.

The potential therapeutic value of a low dose (200-250 micrograms) of intrathecal (i.t.) morphine on bladder capacity was tested in six subjects with chronic suprasacral spinal cord lesions. Micturition reflexes were examined by saline fill cystometry accompanied by EMG recordings from the external anal and urethral sphincters and selected lower limb muscles. Hyperactive detrusor reflexes were associated with a low capacity bladder in five of the six subjects. All subjects revealed vesicoexternal sphincter dyssynergia, and vesical-induced and spontaneous contractions of the abdominal and lower limb musculature. The results was incontinence and frequent catheterizations. Within 5-15 min of the bolus morphine injection into the L1-2 i.t. space, bladder capacity increased to near-maximal values in all subjects. Soon thereafter, uninhibited detrusor contractions, spontaneous motor discharges, and vesicosomatic (limb) reactions were abolished. A peak effect was observed within 2-4 h. Alterations of bladder capacity persisted for 18-22 h. Side effects included pruritus and nausea. Intrathecal morphine acts at sacral spinal cord sites, e.g., primary afferents and/or dorsal horn neurons, mediating vesicovesical and vesicosomatic (sphincter, limb) reflexes, and spontaneous motor discharges. Clinically, i.t. morphine may be an effective therapy for individuals with suprasacral spinal cord lesions when a low capacity bladder interferes with their quality of life.

Dose-Response Relationship, Drug↗
PubMed1984

Penile horns: report of 2 cases.

We report 2 cases of penile horns, including 1 in which verruca carcinoma developed in the base. Treatment of this disease and its potential malignant degeneration are discussed.

Aged↗
PubMed1983

Scrotal ultrasonography.

Scrotal ultrasonography was performed on 43 patients with a diagnostic accuracy rate of 88 per cent. With a small parts 7.5 MHz. real-time ultrasound scanner a clear distinction between gonadal and epididymal pathologic conditions can be achieved in the majority of cases.

Genital Diseases, Male↗
PubMed1980

Development of a carbon dioxide laser cystoscope.

CO2 laser lesions were created at varying power densities on the exteriorized canine bladders. A 50-watt carbon dioxide continuous laser coupled to a Zeiss surgical microscope was used. A schematic power curve was developed indexing depth of bladder penetration by the laser against laser energy output. Once the optimal power settings for the carbon dioxide laser were established, vertical heat transmission, hemostasis, and healing were studied. A prototype carbon dioxide laser cystoscope was then constructed that allowed endoscopic delivery of the CO2 laser beam into the intact canine bladder. The beam was focussed by a germanium lens and directed out the end of the endoscope, using a movable mirror. Eight dogs were then endoscopically studied in vivo.

Animals↗
PubMed1980

Dilemma of small pyelonephritic kidney associated with vesicoureteral reflux.

Nineteen children with severe unilateral pyelonephritic scarring secondary to reflux and infection were followed up for at least five years after ureteral reimplantation. The small kidneys in these children grew at a rate which paralleled expected normal, and this growth was independent of the degree of hypertrophy in the contralateral kidney or the size difference between each pair of renal units. The authors differentiate between obligate and compensatory renal growth and conclude that children with a small pyelonephritic kidney should undergo reimplantation rather than nephrectomy because of the recuperative powers of the growing kidney and its ability to become a potentially life-sustaining organ in the future.

Adaptation, Physiological↗
PubMed1980

Simplified technique for microscopic vasovasostomy.

A one-layer technique for microscopic vasovasostomy is described. There was an 83-per cent return of sperm and 50-per cent pregnancy rate using this technique. With attention to detail, both vasa can be reanastomosed within two hours.

Humans↗
PubMed1979

The association of histocompatibility antigens of the B7 cross-reacting group with Peyronie's disease.

A significant relationship between Peyronie's disease and histocompatibility antigens of the B7 cross-reacting group is described. The association of Peyronie's disease with a group of immunologically cross-reacting antigens, rather than with a single antigen, suggests that a yet undetermined agent of specific molecular configuration involves in some way its pathogenesis. This finding has diagnostic application and adds a new dimension to the etiologic investigation of Peyronie's disease.

Cross Reactions↗
PubMed1979

Evaluation of perihilar and central renal masses using the Chiba needle.

The Chiba needle was used to puncture 14 central renal masses believed to be cysts. Of these masses 13 were cysts and 1 was a peripelvic liposarcoma. Arteriography was not done before puncture. No complications occurred when these central masses surrounded by parenchyma or adjacent to hilar structures were punctured. Renal cyst puncture and cystography using the Chiba needle are safe methods for optimal diagnosis of central and peripelvic systs.

Animals↗
PubMed1978

Retroperitoneal fibrosis with ureteral obstruction secondary to Actinomyces israeli.

A case of Actinomycosis israeli causing retroperitoneal fibrosis and ureteral obstruction is presented. This rare occurrence followed direct extension of the infectious process from intra-abdominal abscesses to the retroperitoneum, resulting in dense fibrosis. Diagnosis is most commonly established by histologic identification of sulfur granules obtained at abdominal exploration. The pathogenesis and treatment of genitourinary as well as retroperitoneal actinomycosis is discussed.

Actinomycosis↗
PubMed1978

Association of HLA-B27 antigen with retroperitoneal fibrosis.

This is the second known case of retroperitoneal fibrosis in a middle-aged black man whose tissue type was HLA-B27 positive. The HLA-B27 antigen is present in only 4 per cent of black American male subjects and may be important in the diagnosis and management of patients with primary retroperitoneal fibrosis. A genetic predisposition is suggested for the development of idiopathic primary retroperitoneal fibrosis in patients who are HLA-B27 antigen positive.

Adult↗
PubMed1978

Development of a carbon dioxide laser cystoscope.

A 50-watt carbon dioxide continuous laser coupled to a Zeiss surgical microscope was used to study the characteristics of laser-induced lesions on the exteriorized canine bladder. The relationship of energy to the depth of the lesion created by the laser was evaluated. Healing, vertical temperature transmission and hemostasis were studied. A prototype carbon dioxide laser cystoscope then was constructed and used endoscopically to create surgical lesions in the intact canine bladder.

Animals↗