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Biomedical subjects

J Hulbert

Publications and source records attributed to J Hulbert.

At least 19 recordsLinked to original sources
PubMed1997

Cryosurgery of dunning AT-1 rat prostate tumor: thermal, biophysical, and viability response at the cellular and tissue level.

This study investigates cryodestruction of the Dunning AT-1 rat prostate tumor at the single cell, tissue slice, and in vivo levels. The thermal history around a 3-mm-diameter cylindrical cryosurgical probe was predicted by solving the bioheat equation in a one-dimensional cylindrical geometry. At various radial positions in the iceball this thermal history was approximated by a constant cooling rate and a final, steady-state temperature (or end-temperature). The predicted cooling rates and end temperatures ranged from > or = 1000 degrees C/min to 5 degrees C/min and -196 degrees C to -20 degrees C, respectively. These cooling rates and end-temperatures were then imposed on single AT-1 cells, AT-1 tissue slices in vitro and AT-1 tumors in vivo. The single cells and tissue slices were frozen by LN2 immersion, copper block slam-freezing, or controlled cooling on a cryomicroscope or a directional solidification stage. LN2 immersion is lethal to AT-1 cells (presumably due to intracellular ice formation), while cooling at 5-100 degrees C/min leaves some viable cells (at end-temperatures ranging between -20 and -40 degrees C). AT-1 tumor slices show extensive intracellular ice formation due to slam cooling, extensive dehydration at 100 degrees C/min, and total dehydration at rates < or = 10 degrees C/min to end temperatures below -10 degrees C. Postfreeze culture and histology of the AT-1 tissue show that extensive intracellular ice formation is lethal, while cellular dehydration and vascular engorgement leave viable cells (at end-temperatures between -20 and -40 degrees C). Based solely on the single cell and in vitro tissue damage achieved by cooling rates and end-temperatures, a sizable portion of a cryosurgically frozen tumor would be expected to survive. However, in vivo cryosurgery performed on AT-1 tumors demonstrated that the tissue was damaged throughout the cryolesion, even at the periphery where the thermal history would be expected to allow single cells and tissue slices to survive in vitro. Taken together, these results suggest that damage mechanisms other than those due to cooling rate and end-temperature may be responsible for the increased cellular destruction at the periphery of the iceball in vivo and that cooling rate is less important than end-temperature in determining cryosurgical damage in AT-1 tumors. Experiments are ongoing to determine if the time held at an end temperature, thawing rate, vascular response, or other mechanisms are primarily responsible for the enhanced destructive capability in vivo.

Animals↗
PubMed1997

Rectal protection during prostate cryosurgery: design and characterization of an insulating probe.

This study presents the design and characterization of an insulating probe made of silicone that could be used for enhancing the safety and efficacy of prostate cryosurgery. The probe would be placed in Denonvilliers' fascia between the prostate and the rectum prior to freezing. During freezing, the iceball would be monitored by ultrasound through the silicone, and direct temperature monitoring of the rectal and prostatic tissue via thermocouples mounted on opposing sides of the device. Both theoretical and experimental studies were performed to verify the insulating and acoustic properties of the probe. The insulating effect of the silicone will enhance cell death within the prostate while minimizing tissue freezing injury and therefore fistula formation postfreeze in the rectum. Experiments were also performed with the insulator placed in gelatine which showed that the silicone material is transparent to ultrasound. In addition the silicone was itself visible under ultrasound imaging, a characteristic which may assist in the delivery of the device to the surgical site. One possible scenario for reconfiguration and delivery of the device is suggested prior to a cryosurgery. The success of this device in insulating and monitoring temperature during freezing suggests that it can also be useful in protecting sensitive tissues adjacent to a surgical site when extreme heat is applied (i.e., electron or hyperthermic surgery).

Cryosurgery↗
PubMed1996

Laparoscopic complications in markedly obese urologic patients (a multi-institutional review)

OBJECTIVES: Significant obesity is considered to be a relative contraindication to laparoscopic surgery. This study reviews the complications encountered in massively obese patients undergoing urologic laparoscopic surgery. METHODS: Body mass index (BMI) was used as an objective index to indicate massive obesity. Eleven institutions compiled retrospective data on 125 patients having a BMI greater than 30. Procedures performed included 76 pelvic lymph node dissections, 14 nephrectomies, 7 bladder neck suspensions, and 28 miscellaneous procedures. RESULTS: For the group as a whole, the mean BMI was 35.1 (range 30.1 to 57.2). Mean operative time was 202 minutes (range 60 to 480). Conversion to open surgery occurred in 15 of the 125 patients (12%). Complication rates (minor and major) were 22% (27 occurrences in 125 patients) intraoperatively and 26% (33 occurrences in 125 patients) postoperatively. The major complications included 2 trocar injuries to abdominal wall vessels, 1 bladder injury, 3 peripheral nerve injuries, 1 dysrhythmia, 1 deep vein thrombosis, 1 wound seroma, 1 nephrocutaneous fistula, 1 incisional hernia, and 1 death. CONCLUSIONS: In this review, complication rates for urologic laparoscopic surgery on massively obese patients were higher than in the general population undergoing laparoscopic surgery (0.3% to 21%).

Adolescent↗
PubMed1994

Intraureteral metallic self-expanding endoprosthesis (Wallstent) in the treatment of difficult ureteral strictures.

Intractable and recurrent ureteral stricture presents a continuous challenge to the urologist. We report on 5 patients with severe ureteral stricture who were successfully treated with self-expanding metallic stents. Ureteral stricture occurred at ureteroileal anastomotic sites after neoplasm resection in 2 cases, multiple upper ureteral strictures were related to multiple surgical procedures for correction of bladder exstrophy in 1 and a ureteral kink developed in 1. Treatment with transluminal balloon dilation provided poor results but self-expanding metallic stents were used successfully with no major complications. In the last patient the stent and the overlying ureter were removed due to recurrent reflux; the gross and histological ureteral changes are discussed in detail. The technical approach is described, alternative therapeutic options are considered and pertinent literature is reviewed.

Adult↗
PubMed1992

Hemicorporectomy for acute aortic occlusion: a case study.

Hemicorporectomy has been done for potentially curable pelvic malignancy and for intractable pelvic sepsis with bone involvement. In this report, the authors describe the first use of hemicorporectomy to treat ischemic gangrene of the limbs and pelvic soft tissues secondary to acute aortic occlusion.

Acute Disease↗
PubMed1990

Physician perceptions of and management practices for significant fetal drug exposure.

A random sample by questionnaire in 1989 of U.S. physicians' perceptions of and management practices for significant fetal drug exposure in the specialty/sub-specialty areas of genetics, neonatology, pediatrics, family practice, neurology, and obstetrics and gynecology was analyzed. Neonatologists reported the greatest number of cases of significant fetal drug exposure, with 45% seeing at least one case per week. Of all physicians, 88% felt that fetal drug exposure is underreported in medical histories, with no statistically significant differences noted in responses for scope of practice or physician age and gender. Review of management styles showed that most physicians recognize the potential problems of fetal drug exposure and the desired intervention. There was, however, a small group of physicians (less than 10%) who did not follow this pattern. Fetal drug exposure continues to be an area in which continuing professional and public education is desirable.

Attitude of Health Personnel↗
PubMed1988

Complicated mania. Comorbidity and immediate outcome in the treatment of mania.

In a case-control study, 57 manics with antecedent or coexisting nonaffective psychiatric disorders (n = 38) or serious medical illnesses (n = 19) ("complicated mania") were compared with 114 age-, sex-, and year-of-admission-matched controls with no other disorder ("uncomplicated mania"). Significant differences emerged between the three groups in age, marital status, age at onset, number of prior hospitalizations and prior suicide attempts, organic features, and outcome measures (recovery and death rates). Patients were divided into four treatment groups based on primary mode of therapy during index admission; the groups included electroconvulsive therapy, adequate lithium carbonate, inadequate lithium carbonate, and neither treatment. Uncomplicated manics were significantly more likely to receive adequate lithium carbonate and less likely to receive inadequate lithium carbonate than were complicated manics. The latter patients had a significantly poorer immediate response to treatment overall, and to adequate lithium carbonate specifically. Seventy-eight (68.4%) uncomplicated manics had recovered ad discharge, compared with 26 (45.6%) complicated manics. Logistic regression suggested that the influence of comorbidity on outcome was more important for women than men. We conclude that complicated mania is a useful clinical construct.

Adult↗
PubMed1988

Predictors of immediate response in the treatment of mania: the importance of comorbidity.

Four hundred thirty-eight bipolar manics were admitted to an acute care psychiatric inpatient ward over a 12-year period. Eighty percent had good and 20% poor immediate outcome. Good outcome patients were characterized by short episode duration, older age of onset, a longer hospitalization, fewer suicide thoughts, and less psychiatric and medical comorbidity than the poor outcome group. Patients were divided into four treatment groups based on primary mode of therapy during index hospitalization: electroconvulsive therapy (ECT), adequate lithium, inadequate lithium, and neither treatment. Patients experiencing good outcome were more likely to be in the adequate lithium group and less likely to receive neither treatment. Regression analysis identified the absence of comorbidity, duration of lithium treatment more than 2 weeks, and duration of episode of less than 1 month as predictors of good outcome at hospital discharge.

Adult↗
PubMed1987

Alternative treatment of prostatic urethral obstruction secondary to benign prostatic hypertrophy. Non-surgical balloon catheter prostatic dilatation.

Benign prostatic hypertrophy (BPH) produces symptoms that currently can only be treated surgically either by open or endoscopic prostatectomy. We have undertaken animal (1) and human studies to determine if invasive radiologic techniques utilizing balloon catheters could be applied to the treatment of this common ailment. We report a series of twelve patients treated by retrograde transurethral balloon catheter prostatic dilatation. The procedure is performed using topical anesthesia with a specially designed balloon catheter (Medi-Tech, Inc.). The procedure is done on an outpatient basis and is completed within approximately 15 minutes. Relatively long-term results have resulted in persistent relief of symptoms. No complications have been encountered. We anticipate that balloon dilatation of the prostatic urethra will have a major impact on the treatment of BPH based on the promising preliminary results. Transurethral resection of the prostate (TURP) is associated with moderate morbidity and significant cost which can be reduced by the proposed procedure.

Catheterization↗
PubMed1987

Prostatic urethra: experimental dilation in dogs.

An animal study was undertaken to develop a balloon dilation technique that could be used in humans to treat the common ailment of benign prostatic hypertrophy. Dogs were used as a model because of the similarities in the prostate between the two species and the ready availability of the canines. A retrograde transurethral approach was used for dilation. Balloon catheters, 8-20 mm in diameter, were used. Significant, long-lasting dilatation of the prostatic urethra was not accomplished until 20-mm balloons (or two 10-mm ones) inflated for 10 minutes were used. The animals were followed for up to 14 months. No deleterious histologic effects of dilation were identified within the urethra or prostate that could lead to stenosis of the prostatic urethra in later stages.

Animals↗
PubMed1987

Benign prostatic hypertrophy: retrograde transurethral dilation of the prostatic urethra in humans. Work in progress.

Retrograde transurethral balloon dilation of the prostatic urethra was performed in five human volunteers with benign prostatic hypertrophy. Each patient underwent cystoscopy, uroflow studies, voiding cystourethrography, retrograde urethrography, and magnetic resonance imaging before dilation and at defined intervals afterward. The longest follow-up to date is 8 months. Patients were given topical anesthetics and mild sedatives, and dilation was performed with a 25-mm urethroplasty balloon catheter inflated at 3-6 atm for 10 minutes. All catheter manipulations were done with a guide wire and under fluoroscopic control. Significant resolution of symptoms of prostatism was seen in four patients. The unsatisfactory results in the last patient were believed to be caused by ineffectual dilation of predominantly middle lobe hypertrophy--a condition that is now regarded as a contraindication to dilation. This technique has promise to replace transurethral resection of the prostate as the treatment of choice for this common male ailment.

Aged↗
PubMed1985

Electrolysis for recanalization of urinary collecting system obstructions: a percutaneous approach.

Nine recent endourologic cases are presented that evidence percutaneous electrolysis and electrocautery as new and safe techniques for incising the urothelium. Electrolysis with balloon dilation was employed to remove stones sequestered behind infundibular and/or diverticular neck stenoses, to correct uretero-pelvic junction (UPJ) stenoses and strictures, and to recanalize a totally obstructed fibrotic UPJ.

Adult↗
PubMed1985

Percutaneous removal of ureteral calculi: clinical and experimental results.

Between May 1983 and October 1984, 51 patients who had 68 ureteral stones underwent treatment at the University of Minnesota. All 68 stones were removed successfully using percutaneous techniques. The 100% success rate is a great improvement over previous results at our institution. The primary factors appear to be the development of the retrograde-flush technique, familiarity with and access to a wider range of methods, and the increasing use of the retrograde ureterorenoscope to see stones in the lower ureter. The average patient was a 45-year-old man who had no other medical problems. The average hospital stay was 6.8 days. Experimental studies with dogs indicate that injection rates of up to 30 ml/sec of contrast material through a retrograde catheter in the ureter are safe if a vent is present in the upper collecting system.

Adult↗
PubMed1979

Orthopaedic problems of renal transplantation.

One in six patients receiving renal transplants has orthopaedic problems. Osteoporosis with accompanying fractures is common, as is avascular necrosis of the hips, knees, and other bones. Immunosuppressive therapy with steroids is implicated and its mode of action discussed. No means of prophylasix is known. If treated conservatively, aseptic necrosis of bone is much more disabling than is commonly believed as judged by the critical assessment technique of Charnley. The authors therefore recommend that a surgical approach should be adopted whenever possible.

Adult↗