Search PubMed⌕ Search

Biomedical subjects

D M Barrett

Publications and source records attributed to D M Barrett.

At least 37 records · Page 2Linked to original sources
PubMed1998

An implantable mechanical urinary sphincter: a new nonhydraulic design concept.

OBJECTIVES: We present data concerning an artificial implantable mechanical urinary sphincter that was designed to eliminate the inherent problems of the current hydraulic artificial urinary sphincter (American Medical System [AMS] 800). Our goal was to design a sphincter that creates urethral compression similar to the AMS 800 but creates the force without the use of fluid, thereby eliminating as much as 50% of the reoperations seen with the AMS 800, which occur because of fluid-related malfunctions. METHODS: An implantable artificial mechanical sphincter consisting of a compressive coil encompassed in a polytetrafluoroethylene sheath was devised and tested in 6 live mongrel dogs to establish compressive force versus bladder pressure data, so as to provide data to create a mechanical sphincter for use in humans. RESULTS: A direct relationship between bladder leakage pressure and cable tension force was demonstrated in all 6 experimental animals, thereby creating a mathematical equation that can be used by mechanical engineers to design a mechanical sphincter for use in humans. CONCLUSIONS: This study demonstrated that a mechanical urinary sphincter can be created that will provide continence and eliminate the problems associated with the hydraulic aspect of the AMS 800. In doing so, nearly 50% of the reoperations seen with the current AMS 800 can be eliminated, thereby improving the quality of life of patients for whom an artificial urinary sphincter is indicated.

Animals↗
PubMed1998

Total alloplastic replacement of the urinary bladder.

Bladder cancer is the second most common malignancy of the genitourinary tract. In 1992, the estimated incidence of bladder cancer in the United States was 50,000 cases. Cystectomy and urinary diversion were the preferred methods of treatment. Currently, these patients undergo various types of intestinal urinary diversion. These procedures represent a significant advancement over bilateral ureterostomies; however, many problems are associated with their use and they are among the topics discussed in this article.

Humans↗
PubMed1998

Textural modification of processing tomatoes.

Knowledge of the textural properties of processing tomatoes is crucial to ensuing product acceptability; measurement, control, and optimization of these properties through judicious selection of varieties and control of unit operations results in products that the consumer prefers. It is important to first define the terms texture, rheology, consistency, and viscosity prior to discussing principles of their measurement. The textural properties of processing tomatoes may be measured using both sensory and objective tests, and the latter may be either destructive or nondestructive in nature. The unique anatomy of tomato fruit (peel, pericarp, columella, and locules) in part dictates the method of texture measurement. Numerous factors, including variety, maturity, genetic modification, cultural particles, and environmental conditions, processing conditions, and calcium addition affect the textural integrity of tomatoes. Textural properties of raw tomatoes and most processed tomato products are reviewed in this article.

Food Handling↗
PubMed1998

High-power potassium titanyl phosphate laser vaporization prostatectomy.

In a search for potential therapeutic strategies for benign prostatic hyperplasia (BPH) that would be associated with less morbidity than transurethral resection of the prostate, various types of laser prostatectomy have been used. Although the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser allows performance of prostatectomy in an almost bloodless field and without absorption of irrigant, the remaining necrotic tissue causes bladder outlet obstruction and related symptoms for 5 to 7 days after treatment. In contrast, the potassium titanyl phosphate (KTP) laser has been found to vaporize tissue with minimal coagulation of the underlying structures. With use of the KTP laser, heat is concentrated into a small volume, the tissue is ablated by rapid vaporization of cellular water, and a 2-mm rim of coagulated tissue is left. After favorable results were obtained in studies of canine prostates and human cadavers, we implemented clinical use of 60-W KTP laser prostatectomy in selected patients. In 10 patients with symptomatic BPH who ranged in age from 52 to 80 years, outpatient KTP laser prostatectomy yielded significantly increased mean peak urinary flow rates (from 8.0 mL/s preoperatively to 19.4 mL/s within 24 hours after the procedure). No patient had hematuria, dysuria, or incontinence after removal of the catheter, and no patient required recatheterization. One patient, however, had urgency, and two other patients became febrile during the 24-hour observation period. Overall, KTP laser vaporization prostatectomy can provide immediate relief from obstructive symptoms of BPH and is not associated with dysuria.

Animals↗
PubMed1998

Transurethral enzyme injection--future management of benign prostatic hyperplasia.

Although benign prostatic hyperplasia, a common condition among elderly men, has been effectively treated with transurethral resection of the prostate, this surgical procedure is associated with many well-recognized risks and complications. Because of this potential morbidity and mortality, various alternative treatment strategies for benign prostatic hyperplasia have been proposed. The use of enzyme solubilization and ablation of prostatic tissue to alleviate urinary outlet obstruction has proved effective in dogs and warrants investigation in human trials. Transurethral enzyme injection of the prostate has the potential for being a treatment modality with minimal invasiveness, limited requirements for anesthesia, and minimal associated toxicity for the management of benign prostatic hyperplasia.

Anti-Bacterial Agents↗
PubMed1998

Mayo Clinic long-term analysis of the functional durability of the AMS 800 artificial urinary sphincter: a review of 323 cases.

PURPOSE: We determine the long-term durability of the AMS 800* artificial urinary sphincter in the correction of severe urinary incontinence, and evaluate mechanical versus nonmechanical failure and reoperation rates before (1983 to 1987) and after (1988 to present) the introduction of the narrow backing occlusive cuff design. MATERIALS AND METHODS: From January 1983 to October 1994 more than 400 patients received an AMS 800 artificial urinary sphincter placed by 1 surgeon and 323, mean age 60.4 years, met study requirements for review. Mean followup was 68.8 months (range 18 to 153). Only patients with a minimum of 18 months of followup were included in the study. Of the 313 men and 10 women in the study group sphincters were placed at the urethra in 272 and at the bladder neck in 51. All patients were followed from surgery to the date of sphincter failure. Etiology of the failures was recorded and divided into mechanical versus nonmechanical sphincters placed before and after the introduction of the narrow backing cuff. RESULTS: Overall, 58 of the 139 patients (42%) in the pre-narrow backing cuff group versus 31 of the 184 (17%) in the narrow backing cuff group required a first reoperation. Mechanical failure occurred in 29 cases (21%) with the pre-narrow backing and 14 (7.6%) with the narrow backing cuff. Nonmechanical failure developed in 24 cases (17%) with the pre-narrow backing and 17 (9%) with the narrow backing cuff. Ultimately 437 operations were required in the 323 patients, of whom 234 (72%) required no further surgical intervention at a mean followup of 68.8 months. CONCLUSIONS: Technological advances in the design and construction of the AMS 800 have dramatically decreased the reoperation and failure rates. These advances and improved surgical techniques provide an excellent long-term solution and increased continence in correctly selected patients with urinary incontinence.

Female↗
PubMed1997

Use of the artificial urinary sphincter in men and women.

There are numerous therapeutic options for treating incontinence. Implantation of an artificial genitourinary sphincter is an excellent choice in cases of incontinence due to sphincteric dysfunction. In this article we report the Mayo Clinic data from several large series and compare these data to other recent reviews. In addition, we review current recommendations regarding patient selection and evaluation. There were 458 patients who underwent implantation of an artificial sphincter, including 417 men and 41 women. The overall continence rate was 88.2%, the reoperation rate was 23.1%, and the mechanical reliability was 88%. Satisfaction rates were greater than 90%. We conclude that artificial sphincter implantation is safe, reliable and very effective in treating incontinence due to sphincteric dysfunction in properly selected patients.

Female↗
PubMed1997

High-power (60-watt) potassium-titanyl-phosphate laser vaporization prostatectomy in living canines and in human and canine cadavers.

OBJECTIVES: We studied the safety and efficacy of 60-W potassium-titanyl-phosphate (KTP) laser prostatectomy in living dogs and compared the efficacy with that in fresh human and dog cadavers. METHODS: Ten dogs underwent 60-W KTP laser prostatectomy and were sacrificed 3 hours (n = 5) or 7 weeks (n = 5) after operation. Two thawed fresh-frozen human cadaver prostates and two thawed fresh-frozen canine prostates were also vaporized with the 60-W KTP laser. All prostates were weighed, measured, serially sectioned, and whole mounted for histologic analysis. RESULTS: In dogs, the in vivo procedure was hemostatic, and no irrigant absorption was detected. Prostatic defects with a mean diameter of 3.0 and 2.5 cm at 3 hours and 7 weeks postoperatively, respectively, were produced. With experience, resection time was reduced to 14 minutes. Of the 5 dogs that were studied for 7 weeks, 4 voided immediately after removal of the urethral catheter on the morning after operation, and 1 dog required recatheterization but voided with a strong stream when the urethral catheter was removed 4 days later. All 5 dogs were continent and had normal erectile function postoperatively. Defects of 2.0 and 2.5 cm were produced in the two human cadaver prostates (weight, 29.5 and 55 g) with resection times of 26 and 54 minutes, respectively. Human and canine cadaver prostates required similar energies for tissue vaporization (15.2 and 13.7 kJ/cm3 cavity created, respectively, P > 0.6), whereas living canine prostates required only 7.0 kJ/cm3 cavity created (P < 0.01 compared with cadaver tissue). CONCLUSIONS: The 60-W KTP laser allows technically easy, safe, rapid, and hemostatic removal of canine prostatic tissue in vivo. Furthermore, there is no difference in the efficacy of KTP laser vaporization between human and canine cadaver prostates. These findings suggest that KTP laser vaporization may be as effective in living human prostates as it is in living dogs, and thus it may be a useful technique in the surgical treatment of human benign prostatic hyperplasia.

Animals↗
PubMed1997

Long-term followup and evaluation of primary realignment of posterior urethral disruptions.

PURPOSE: We analyzed the long-term results of treatment of posterior urethral disruptions with immediate primary realignment. MATERIALS AND METHODS: A total of 57 patients with posterior urethral disruptions (56 complete and 1 partial) underwent primary urethral realignment within 6 hours after injury. Pelvic fractures were present in 52 patients. In all cases the actual operating time for realignment was 1.25 hours or less. All patients were evaluated postoperatively for incontinence, impotence and strictures. Mean followup was 10.5 years (range up to 40 years) after injury and 53 patients were available for long-term followup. RESULTS: Erections-42 of 53 patients (79%) reported no erectile dysfunction, 7 (13%) reported decreased quality of erection but required no treatment and 4 (7.5%) had erectile dysfunction requiring treatment. Incontinence-2 of 53 patients (3.7%) reported mild post-realignment stress incontinence. Both patients did not need treatment for incontinence or protective padding. Strictures-18 of 53 patients (34%) had evidence of post-realignment strictures and required no further urethral dilation or surgical intervention. Mean followup for these 18 patients was 12 years 2 months. A total of 36 patients (68%) had post-realignment strictures; however, 23 (43.4%) were considered to have mild strictures that were observed or easily managed with in-office dilation. Mean followup for these patients was 8.5 years. Of the 53 patients 13 (24.5%) had more significant strictures that required a repeat procedure using general anesthesia. A total of 20 procedures was required to treat the 13 patients. Of the 20 procedures done using general anesthesia 16 (80%) were completed on an outpatient basis. The remaining 4 patients required urethroplasty. Mean followup of the 13 patients was 11 years 9 months. CONCLUSIONS: Immediate primary realignment resulted in negligible intraoperative morbidity, and acceptably low incidences of impotence, incontinence and symptomatic strictures.

Adolescent↗
PubMed1997

In situ hybridization for Helicobacter pylori in gastric mucosal biopsy specimens: quantitative evaluation of test performance in comparison with the CLOtest and thiazine stain.

Numerous detection methods for Helicobacter Pylori (H. pylori) have been developed with varying degrees of purported diagnostic utility. We have developed a rapid nonradioactive in situ hybridization (ISH) method for H. pylori detection in paraffin-embedded tissue and assessed its relative diagnostic performance by receiver operator characteristics (ROC) in comparison to the thiazine stain and CLOtest. Forty-five patients undergoing endoscopy had antral biopsies and concomitant CLOtest performed. ISH for H. pylori was done using a 22-base, biotin-labeled oligonucleotide probe complementary to a portion of H. pylori 16s rRNA with the following sequence: 5'-GGACATAGGCTGATCTTAGC-3'. ISH using this probe was specific for H. pylori with no crossreactivity with other bacterial or fungal organisms. Receiver operator characteristic analysis was used to assess the diagnostic performance of ISH and thiazine techniques. ISH and thiazine stains were done on serial sections, reviewed independently, and scored on a graded scale from 1-5 based upon the degree of assurance of H. pylori presence. Diagnostic performance was assessed in "expert" and "nonexpert" pathologist groups with the CLOtest serving as the invariant test for relative test comparison. The ISH test performed slightly better (ROC area 0.9) than the thiazine (ROC area 0.8) in the nonexpert population, but equally well in the "expert" group (ROC area 0.95, 0.95). ISH followed by routine hematoxylin and eosin staining showed detailed mucosal histology with a dramatic visualization of H. pylori along the surface of the foveolar cells with no evidence of lamina propria invasion. In summary, ISH for H. pylori is an excellent test that is specific, easily read, and allows concomitant detailed histologic mucosal examination.

Biopsy↗
PubMed1996

Transurethral enzymatic ablation of the prostate: canine model.

OBJECTIVES: The purpose of this study was to investigate the toxicity and potential usefulness of transurethral prostatic injection of a collagenase-based solution in treating benign prostatic hyperplasia in dogs. METHODS: The injected solution contained collagenase, hyaluronidase, Triton X-100, and gentamicin. Twenty-one dogs were randomly divided into three groups for transurethral prostatic needle injection: two treatment groups were observed for 6 and 12 weeks and a control group was observed for 12 weeks. Laboratory studies, clinical monitoring, and complete postmortem examination were performed in all animals. RESULTS: Gross hematuria was noted in all dogs for a mean of 4 days after injection. No significant postoperative morbidity was noted. There were no significant differences in the values of laboratory tests among the three groups except for a mean increase in serum level of aspartate transaminase for treatment groups on postoperative day 1; this resolved by postoperative day 7. Histologically, all treated prostates had stromal atrophy and cystic acinar dilation involving about 30% of the gland without extraprostatic extension of these changes. The urethra, bladder, rectum, testicles, kidney, liver, and lungs were normal and intact in all animals. CONCLUSIONS: Transurethral injection of this enzyme solution creates a predictable, favorable histologic response in the canine prostate. The procedure appears safe and warrants further investigation for treatment of human benign prostatic hyperplasia.

Animals↗
PubMed1996

Optimized microvessel density analysis improves prediction of cancer stage from prostate needle biopsies.

OBJECTIVES: Clinical staging of prostate cancer is inaccurate, often with significant upstaging on final pathologic review. We previously demonstrated the ability to predict extraprostatic extension of cancer by use of the Gleason score and serum prostate-specific antigen (PSA) measurements. Herein we present an interim analysis of data from an ongoing multi-institutional study to determine the predictive power of an enhancement of microvessel density analysis in combination with Gleason score and serum PSA to predict extraprostatic extension. METHODS: We evaluated a total of 186 randomly selected biopsy samples and matched totally embedded radical prostatectomy samples with preoperative PSA concentrations and patient demographics. Gleason score and optimized microvessel density (OMVD) were determined from the needle biopsy samples; pathologic stage was verified by independent review of the radical prostatectomy samples. An automated digital image analysis system measured microvessel morphology and calculated the OMVD in the biopsy samples (Biostage; Bard Diagnostic Sciences, Seattle, Wash). RESULTS: Prediction of extraprostatic extension was increased significantly when OMVD analysis was added to Gleason score and serum PSA concentration (P = 0.003). CONCLUSIONS: Optimized microvessel density analysis significantly increases the ability to predict extraprostatic extension of cancer preoperatively when combined with Gleason score and serum PSA concentration. This method appears to be a useful tool that can assist with treatment decisions in selected patients.

Aged↗
PubMed1996

Laser prostatectomy: two and a half years' experience with aggressive multifocal therapy.

OBJECTIVES: The aim of this study was to evaluate patient outcome 1 to 2 1/2 years after aggressive neodymium: yttrium-aluminum-garnet (Nd:YAG) laser prostatectomy alone or combined with potassium titanyl phosphate (KTP/532) laser therapy. METHODS: In 32 men with symptomatic bladder outlet obstruction caused by benign prostatic hyperplasia, Nd:YAG laser energy (40 W) was delivered to six or more locations on the prostatic lateral lobes and one or more on the median lobe. In a subgroup of 15 of these patients, the prostate was also incised and sculpted with KTP/532 laser to create a better channel. RESULTS: In the 32 men, voiding parameters improved: mean peak flow rate increased from 10 to 21 mL/s (110%), residual volume decreased from 167 to 64 mL (62%), and American Urological Association (AUA) symptom score decreased from 24 to 9 (63%). Catheters were removed after 3 days. Of the 17 patients treated with the Nd:YAG laser alone, 12 (70.5%) required recatheterization, whereas only 5 of the 15 (33%) who received KTP/532 laser therapy after Nd:YAG treatment required recatheterization (P < 0.001). In the entire group of 32 patients, complications included predictably prolonged retention (14 to 60 days) in 4 patients (12.5%) with hypotonic bladders, prolonged dysuria in 4 (12.5%), vesical neck contracture in 2 (6%), and significant hematuria in 1; none had incontinence. All 25 sexually active men remained potent (100%), but among these patients retrograde ejaculation developed in 5 (20%). CONCLUSIONS: Aggressive Nd:YAG laser prostatectomy is safe and effective for obstructive prostates up to 70 mL in volume and produces good results that are sustained for up to 2 1/2 years. Adjunctive KTP/532 laser therapy apparently creates an unobstructed channel more quickly and reduces the rate of postoperative retention, but it does not alter other voiding parameters.

Adult↗
PubMed1996

Potassium-titanyl-phosphate laser vaporization of the prostate: a comparative functional and pathologic study in canines.

OBJECTIVE: We compared the functional and pathologic results of potassium-titanyl-phosphate (KTP) laser vaporization prostatectomy with those of neodymium:yttrium-aluminum-garnet (Nd:YAG) laser vaporization and coagulation prostatectomy in dogs. METHODS: The prostates of 41 dogs were treated with KTP laser vaporization (n = 21), Nd:YAG laser vaporization (n = 10), or Nd:YAG laser coagulation (n = 10). Dogs were sacrificed 2 days or 8 weeks after treatment. Prostates were weighed, measured, serially sectioned, and whole-mounted for histologic analysis. RESULTS: All techniques were hemostatic, and no irrigant absorption was detected. KTP laser vaporization produced a prostatic defect with a mean diameter of 3.0 and 2.4 cm at 2 days and 8 weeks postoperatively, respectively. Smaller defects (P < 0.0005 at 2 days and P < 0.02 at 8 weeks) were produced by Nd:YAG laser vaporization (2.0 and 1.4 cm, respectively) and coagulation (0.5 and 0.9 cm, respectively). No dog treated with KTP laser vaporization was incontinent or developed urinary retention, including 5 dogs whose urethral catheters were removed within 24 hours of surgery. CONCLUSIONS: KTP laser vaporization prostatectomy not only provides hemostasis similar to that obtained with Nd:YAG laser coagulation, but also removes tissue at the time of operation, allowing dogs to void without straining within 24 hours of treatment. In addition, the procedure is technically simple, and the operator has excellent control over exactly which tissue is removed and which is left intact. These findings suggest that KTP laser vaporization may be useful in the treatment of human benign prostatic hyperplasia.

Animals↗
PubMed1996

Periurethral injection of the genitourinary spheroidal membrane.

Periurethral injection of bulking agents to cause coaptation of the urethral walls has long been used in the treatment of urinary incontinence. A new form of this treatment is the silicone Genitourinary Spheroidal Membrane (Genisphere), which is placed in the periurethral tissues with a special delivery tool. Among 39 women who received two or three Genispheres, 29 (77%) became dry or markedly improved with a significant increase in leak-point and proximal urethral closure pressures. Early sexual activity, a short urethra, atrophic tissue, bladder instability, incorrect positioning, and device rupture were the causes of failure. The device has several advantages over traditional bulking agents, including the absence of silicone particles that can migrate, and has proved to be a safe method of treating stress urinary incontinence.

Cystoscopy↗
PubMed1995

Visual laser ablation of the prostate: a preliminary report.

OBJECTIVE: To report our preliminary experience with visual laser ablation of the prostate (VLAP) for treating bladder outlet obstruction caused by benign prostatic hyperplasia (BPH) and to evaluate its short-term outcome. DESIGN: We reviewed our laser technique in 47 men with symptomatic obstruction caused by BPH who underwent VLAP between July 1992 and April 1993 at our institution, and we compared our results with those reported in the literature. MATERIAL AND METHODS: Our 47 patients were from 43 to 87 years old (mean, 69.6). The mean pretreatment American Urological Association symptom score was 22, mean peak flow rate was 9.5 mL/s, and mean postvoid residual urinary volume was 136 mL. Neodymium:yttrium-aluminum-garnet laser energy was delivered at the 2-, 4-, 8-, and 10-o'clock positions and, when necessary, to the median lobe by one of two lateral-firing laser probes. All but the first four patients were treated on an outpatient basis, and all patients were catheterized (Foley catheter) for 2 to 10 days after VLAP. RESULTS: Of the 47 patients, 32 had data pertaining to a mean follow-up of 5 months; they had a mean symptom score of 10, mean peak flow rate of 15.7 mL/s, and mean postvoid residual volume of 63 mL. In 12 patients, data from a mean follow-up of 11 months were available; they had a mean symptom score of 6, mean peak flow rate of 18.8 mL/s, and mean postvoid residual volume of 10 mL. Perioperative complications (myocardial infarction, thrombophlebitis, and epididymitis) in three patients responded to conservative therapy. Urinary retention occurred for 2 to 60 days after initial removal of the Foley catheter in 12 patients, who then had resumption of spontaneous voiding. In three patients who stated their condition was worse postoperatively, conventional transurethral resection of the prostate was done 6 months after VLAP, and a fourth patient had a persistently obstructive bladder neck incised 8 months after VLAP. CONCLUSION: Our early experience and that reported in the literature indicate that VLAP is a safe and efficacious alternative treatment of obstructive BPH. Although the early results of VLAP rival those of transurethral resection of the prostate, the success rate in treating large prostates should be improved, and long-term results should be assessed to determine the durability of the beneficial effects.

Adult↗
PubMed1995

Diversion.

Explore the source record for details and available documents.

Humans↗