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Biomedical subjects

M M Warren

Publications and source records attributed to M M Warren.

At least 19 recordsLinked to original sources
PubMed1997

Increased incidence of non-transitional cell carcinoma of the bladder in women of the Texas Gulf Coast region.

The objective of our study was to verify a suspected increased incidence of non-transitional cell carcinoma (TCC) of the bladder in female patients treated at our institution. The study included 169 patients, 83% of whom resided in the Texas Gulf Coast region. Tumors were considered TCC or non-TCC on the basis of their predominant histologic pattern. The incidence of non-TCC among men (8.1%) was comparable with data from American tumor registries and European studies. In contrast, our female patients exhibited a marked increased incidence of non-TCC (42.3%), which is approximately five times higher than that in other series. All male and female patients with non-TCC had invasive disease. History of urinary tract infections was strongly associated with non-TCC. Our results suggest that our sample of the female population in the Texas Gulf Coast region has a significantly high incidence of non-TCC. This unusual trend merits further investigation.

Adenocarcinoma↗
PubMed1997

Value of prostatic cancer screening in patients treated for benign prostatic hyperplasia with medical or minimally invasive modalities.

OBJECTIVE: To assess the likelihood of overlooking the diagnosis of prostate cancer (PCA), using current screening methods, in patients treated for benign prostatic hyperplasia (BPH) with medical or minimally invasive treatment modalities, which do not produce tissue specimens for histologic review. To appraise this, we examined the impact of the preoperative use of prostatic specific antigen (PSA) in combination with transrectal ultrasound (TRUS) and systematic sextant prostate needle biopsy (PNbx) on the subsequent incidence of stage A PCA in patients undergoing transurethral resection of the prostate (TURP). METHODS/RESULTS: After excluding all patients found to have PCA during pretreatment screening, 485 patients who underwent TURP for presumed BPH from 1976 to 1994, were reviewed. From 1976 to 1989, PSA was not used for pretreatment screening, and stage A PCA was diagnosed in 11.4% of 317 patients. In 1990 and 1991, pretreatment screening included PNbx obtained under ultrasound guidance for PSA > or = 15.0 ng/ml. Stage A PCA was diagnosed in 14.2% of 63 patients. From 1992 to 1994, pretreatment screening included systematic sextant PNbx performed for PSA > 4.0 ng/ml, and stage A PCA was diagnosed in 2.8% of 105 patients. The difference in incidence of stage A PCA between the first two groups and group three was significant (p = 0.021); so is the difference in incidence of stage A2 (p = 0.037). For stage A1, the difference did not reach statistical significance (p = 0.089). CONCLUSION: Our findings suggest that systematic sextant PNbx for PSA > 4.0 ng/ml significantly reduces the risk of overlooking prostate cancer in patients undergoing treatment of BPH with modalities that do not provide tissue specimens.

Aged↗
PubMed1996

Healing response of the canine prostate to Nd:YAG laser radiation.

The objective of the study was to characterize the healing response of the canine prostate to laser thermal injury. The study included 20 canine prostates that underwent transurethral laser radiation. The prostates were retrieved 1 hr after laser radiation in 7 dogs (acute group), and from 3 days to 9 weeks in 13 dogs (chronic group). Two distinct features were observed. First, reepithelialization of the prostate urethra resulted from mobilization of proliferating epithelial cells from acinar and ductal prostatic epithelium into the cavity surface, and not from the edges of the wound at the bladder neck. Squamous cell metaplasia was a prominent feature of reepithelialization. Second, the healing process in the canine prostate was relatively unimpeded. The large glandular component provided abundant germinal epithelial growth, and the absence of stromal elements allowed for complete sloughing of necrotic tissue without residual eschars. Further, the lesions in the chronic group had a tendency to be larger than those in the acute group, suggesting that extended delayed necrosis may occur at deep prostatic tissue layers.

Animals↗
PubMed1996

Mechanism of healing of the human prostatic urethra following thermal injury.

OBJECTIVES: To characterize histopathologically the healing response of the prostatic urethra after laser thermal coagulation and standard transurethral resection of the prostate (TURP). METHODS: The study included 31 patients who underwent radical prostatectomy because of malignancy. Twenty-two (first group) had laser radiation either at the time of surgery (18 patients) or from 1 to 12 weeks prior to prostatectomy (4 patients). Nine patients (second group) had TURP from 6 to 96 weeks prior to prostatectomy. RESULTS: Coagulation necrosis followed by sloughing was observed during the first 10 weeks after laser radiation. After the first 10 weeks, the healing response was otherwise stereotypical and comparable for both groups of patients. Re-epithelialization was prominent and resulted from migration of proliferating epithelial cells from the remaining acinar and ductal epithelium. Squamous metaplasia was conspicuous and present indefinitely. Development of inflammatory reaction followed by granulation tissue and well-organized fibroblastic stroma were sequentially recognized, but less prominent. Complete re-epithelialization and wound sealing was not observed before the first 12 weeks of healing. CONCLUSIONS: Our study suggests that laser thermal coagulation and TURP are partial-thickness injuries. Because of the abundant germinal epithelium in the remaining prostatic glands and ducts, the healing response of the prostatic urethra is relatively unimpeded and free of contractures, analogous to second-degree skin burns.

Aged↗
PubMed1995

Laser photocoagulation of prostate: influence of dosimetry.

BACKGROUND AND OBJECTIVE: Recently, increasing enthusiasm has been shown for application of lasers for the treatment of benign prostate hyperplasia (BPH). However, little is known about the thermodynamics of prostatic tissue response during laser irradiation and how the treatment outcome can be optimized. Our objective was to conduct a systematic study of the influence of exposure parameters on the extent of tissue coagulation and to determine the effects of rate of tissue heating on lesion size by comparing the tissue response to high laser power rapid heating vs. low laser power slow heating. STUDY DESIGN/MATERIALS AND METHODS: Nd:YAG laser irradiation of prostate was performed in 15 mongrel canines, using an incident power of 15, 30, or 50 Watts (at the fiber tip) and an exposure time varying from 30 to 300 seconds. The laser beam was delivered via a Urolase side-emitting catheter. The tissue response was compared based on gross as well as histological evaluations of thermal lesions. RESULTS: The depth of coagulation necrosis increased as the laser power was reduced from 50 W to 30 W and further to 15 W while the total delivered energy was kept constant at 2,700 J by adjusting the exposure time. The difference between the three heating rates was more dramatic when the estimated volume of coagulated tissue was considered. Increasing the irradiation time for the low power (15 W) from 180 to 300 seconds resulted in enlarging the coagulated volume by a factor of 1.6. However, for high power (50 W), increasing the exposure time from 54 to 90 seconds resulted in increasing the coagulated volume by a factor of 1.2. CONCLUSION: This study suggests that a slow heating regimen yields larger volumes of coagulation necrosis than the currently used rapid heating approach.

Aluminum Silicates↗
PubMed1995

Randomized clinical trial comparing low power-slow heating versus high power-rapid heating noncontact neodymium:yttrium-aluminum-garnet laser regimens for the treatment of benign prostatic hyperplasia.

OBJECTIVES: To evaluate and compare the safety and effectiveness of two noncontact laser regimens for the treatment of human benign prostatic hyperplasia (BPH), and to assess the impact of the spatial distribution of the laser-induced lesions on treatment outcome. METHODS: This was a prospective, double-blind, randomized study that included 29 patients with BPH (both the patients and the study physician assistant in charge of the follow-up evaluation were blinded to the treatment rendered). The patients were randomized to receive either a 15 W for 180 s (15 patients) or 50 W for 60 s (14 patients) laser regimen (powers measured at the fiber tip). There were two study phases for each treatment group: the irradiated sites were not overlapping during the first phase (lesions 1.5 cm apart), and were overlapping during the second phase (lesion less than 1.0 cm apart). RESULTS: Morbidity was minimal in both groups. At 1 year of follow-up, there was significant improvement of the American Urological Association-7 symptom score, the peak urinary flow rate, and the postvoid residual in both treatment groups. These improvements were not statistically significantly different regardless of time or the phase of the study for the two treatment groups. There were 3 treatment failures, 2 of whom were later successfully re-treated with larger amounts of laser energy. Furthermore, the peak flows in the second phase of the study were statistically significantly higher than those in the first phase of the study, regardless of the treatment group. CONCLUSIONS: Our results suggest that both the 15 W for 180 s and the 50 W for 60 s are equally safe and effective treatments for BPH. Perhaps more importantly, they also suggest that the spatial distribution of lesions and overlapping of treated (irradiated) sites has significant impact on treatment outcome.

Aged↗
PubMed1995

Thermocoagulation effect of diode laser radiation in the human prostate: acute and chronic study.

OBJECTIVES: To evaluate the safety and efficacy of low-power slow-heating diode laser-induced photocoagulation of prostatic tissue for treatment of benign prostatic hyperplasia, we conducted a series of acute and chronic studies using a diode laser (810 nm) to irradiate human prostate. METHODS: The study included 6 patients undergoing radical prostatectomy because of malignancy. Laser radiation to the prostate was given transurethrally, in a noncontact mode, at the time of the procedure in 2 patients (acute group): 10 W for 300 seconds on the right side of the prostate and 15 W for 180 seconds on the left. In the remaining 4 patients (chronic group), laser radiation was given at 1, 7, 10, and 12 weeks prior to the prostatectomy. RESULTS: In the acute group the average depth of coagulation was 8.5 and 9.0 mm for the laser regimens of 15 W for 180 seconds and the 10 W for 300 seconds, respectively. In the chronic group, the average depth of coagulation was 8.9 mm for both laser regimens studied. In the acute group, there was an ill-defined hemorrhagic ring at the periphery of the lesion. At 1 week, an intact necrotic coagulum was present. At 7 weeks, some of the coagulated tissue had already sloughed off. Longer follow-up at 10 and 12 weeks demonstrated formation of a well-defined cavity with mostly re-epithelialized surface. CONCLUSIONS: Our findings suggest that noncontact diode laser (810 nm) irradiation can induce in the human prostate significant coagulation necrosis followed by sloughing of tissue and cavitation of the prostatic urethra.

Aged↗
PubMed1995

Comparison of thermocoagulation effects of low power, slow heating versus high power, rapid heating Nd: YAG laser regimens in a canine prostate model.

We compared the thermocoagulation effects of low power, slow heating (15 W x 180 seconds) versus high power, rapid heating (50 W x 60 seconds) laser regimens in the canine prostate. The study was performed in 20 mongrel canines. On each prostate, the low power regimen was delivered at the 2 and 4 o'clock positions, and the high power at the 8 and 10 o'clock positions. The laser power was measured at the fiber tip. Seven dogs (acute group) were sacrificed 1 hour after the procedure. The other 13 dogs (chronic group) were sacrificed at different time intervals from 3 days to 9 weeks after the procedure. The average depth of coagulation was significantly greater in lesions treated at low power (acute: 10.7 mm., chronic: 13.3 mm.) than in those treated at high power (acute: 8.5 mm., chronic: 11.6 mm.). Another potential benefit of the low power regimen observed in the study was preservation of the integrity and efficiency of the laser probe.

Animals↗
PubMed1995

Histopathological evaluation of laser thermocoagulation in the human prostate: optimization of laser irradiation for benign prostatic hyperplasia.

We have previously shown in a canine prostate model that a noncontact low power neodymium:YAG laser regimen of 15 watts for 180 seconds yields a larger volume of coagulation necrosis than the currently recommended high power regimen of 50 watts for 60 seconds. These 2 regimens have not yet been compared in humans. The objective of this study was to evaluate histopathologically the thermocoagulation effect of these 2 laser regimens in the human prostate and the effect of the spatial distribution of the laser lesions on the extent of coagulation necrosis. The study was conducted in 10 patients undergoing radical prostatectomy or cystoprostatectomy. The laser treatment was given transurethrally 1 hour before removal of the specimen. There were no fractures of the prostate. The coagulation necrosis did not reach the peripheral zone and it was minimal in areas rich in fibromuscular tissue, such as the bladder neck. At times, nodular benign prostatic hyperplasia was unaffected. A 4-quadrant treatment in the same plane often yielded small nonconfluent lesions. Confluent lesions in the same plane yielded approximately 30% greater depth of coagulation necrosis, which was achieved when 3 or 4 lesions were created on each side of the prostate (per single transverse plane). Likewise, coagulation necrosis observed with 15 watts for 180 seconds was approximately 40% greater than that noted with the 50 watts for 60 seconds regimen. Our findings suggest that noncontact laser prostatectomy is a safe procedure that can be improved by modifying the laser regimen and the spatial distribution of lesions.

Aged↗
PubMed1995

In vivo reduction of bacterial populations in the urinary tract of catheterized sheep by iontophoresis.

PURPOSE: Iontophoresis kills microbes in vitro and, therefore, may be a useful method for eliminating microbial populations associated with catheter-induced urinary tract infections in vivo. MATERIALS AND METHODS: Catheters were modified to deliver current to platinum electrodes in the catheter tip. Female sheep were catheterized with this iontophoretic catheter and left ambulatory. In 5 sheep (experimental group) 400 microA was applied to the catheter and withheld in 4 sheep (control group) for 20 to 21 days. The animals were then sacrificed. During the study, types and concentrations of bacteria, and physical and chemical characteristics of the urine samples were determined. RESULTS: Throughout the study, bacteria levels were reduced in urinary tracts of the experimental group (10(3) to 10(4) microbes per ml.) compared with the control group (10(7) microbes per ml.), without extensive alterations to urine chemistry or the sheep urinary tract. CONCLUSIONS: Since iontophoresis safely reduced bacterial populations in catheterized sheep, this technology may reduce or eliminate nosocomial, catheter-induced urinary tract infections in humans.

Animals↗
PubMed1995

Prostate cancer screening: a decision analysis.

BACKGROUND: The issue of whether to screen men for prostate cancer is controversial. No randomized clinical trials have been completed to confirm the efficacy of screening for prostate cancer. We created a mathematical model of the clinical risks and benefits of screening for prostate cancer. METHODS: A Markov decision-analytic model evaluated the outcomes of annually screening asymptomatic men for prostate cancer beginning at age 50 years. The screening and testing algorithm included the digital rectal examination, transrectal ultrasound, and prostate-specific antigen test. A sample of 10 male patients with no history of prostate disease were interviewed to assess their utilities (preferences) regarding the various adverse outcomes of prostate cancer treatment. RESULTS: The model indicated that no screening was preferred to screening when patients' utilities were considered (24.14 vs 23.47 quality-adjusted life years expected). The optimal decision was sensitive to the utilities of impotence and urethral stricture, the most common adverse outcomes for patients under the age of 65 years. When adverse outcomes of treatment were ignored, screening was favored (24.86 vs 24.22 years of life expectancy. CONCLUSIONS: When quality-of-life preferences of men are considered, the annual screening of asymptomatic patients for prostate cancer is not recommended.

Aged↗
PubMed1994

Quantification, qualification, and microbial killing efficiencies of antimicrobial chlorine-based substances produced by iontophoresis.

The dependence of microbial killing on chloride ions present in solutions undergoing iontophoresis is addressed. A 400-microA current was applied to vials containing synthetic urine or saline, and the production of chlorine-based substances (CBSs) was detected by the N,N-diethyl-p-phenylene diamine colorimetric method. It was found that as the time of current application increased, the total concentration of CBSs also increased. The iontophoretic current converted (through oxidation) chloride ions present in the solutions into CBSs such as free chlorine, chlorine dioxide, chlorite, monochloramine, and dichloramine (the last two were produced by iontophoresis only when nitrogenous substances were present in the solution). Two of the CBSs (free Cl and ClO2), when they were separately added back to microbial suspensions (approximately 3 x 10(5) CFU/ml) at the same concentrations at which they were detected in either 0.46% (wt/vol) NaCl solution or synthetic urine iontophoresed for 4 h at 400 microA, reduced or eliminated bacterial genera and a fungus. However, when free Cl and ClO2 were jointly added back to microbial suspensions, bacterial and fungal killing was synergistic and more rapid and complete than when these chlorine-based biocides were added separately. Therefore, iontophoresis of solutions containing chloride ions produces chlorine-based biocides that are responsible for the antimicrobial effect of iontophoresis.

Bacteria↗
PubMed1993

Iontophoresis and chloride-containing compounds: parameters required for killing.

Fungi, and gram-positive and gram-negative organisms were susceptible to iontophoretic killing in simple media. Iontophoresis did not depend on electrode type but did require chloride-containing compounds in the medium. All organisms could be killed efficiently if chloride-containing compounds (for example sodium chloride and calcium chloride) were present in physiological concentrations. Effectiveness of iontophoretic killing could be reduced by nonphysiologically elevated concentrations of other substances (for example creatinine and albumin). The data suggest that iontophoresis should function well in urine, since chloride-containing compounds are present in adequate concentrations even if some naturally occurring compounds, such as creatinine or albumin, are elevated.

Calcium Chloride↗
PubMed1993

Recent advances in the diagnosis and treatment of renal arteriovenous malformations and fistulas.

Arteriovenous malformations remain relatively rare clinical lesions. However, with an increasing number of percutaneous renal procedures being performed, their overall incidence can be expected to increase. Congenital arteriovenous malformations usually present with hematuria, while acquired fistulas are more likely to present with hemodynamic changes, such as hypertension, cardiomegaly and congestive heart failure. Arteriography remains the principal method of diagnosis. However, newer imaging modalities such as CT, MRI and color duplex ultrasound may make significant contributions in the evaluation of these abnormalities (fig. 1). Surgery, whether nephrectomy or ligation of feeding vessels, has long been the standard treatment for symptomatic arteriovenous malformations or fistulas. The loss of normal renal parenchyma, migration of occluding agents or recanalization of abnormal vessels has limited the use of embolization as a method of treatment in the past. Recently, newer techniques and agents, such as pharmacoangiography and alcohol, have increased the efficacy of embolization therapy, either as an adjuvant to surgery, definitive therapy or palliation. Although to our knowledge there have been no controlled studies comparing surgical treatment versus embolization, certain recommendations can be made. Because of the decreasing morbidity and increasing efficacy, embolization should be attempted at the time of arteriography as a means of treatment for most arteriovenous malformations and fistulas. However, the choice of surgery, embolization or a combination must be individualized for each patient with regard to overall health, symptoms and manifestations of the fistula or malformation (fig. 2).

Algorithms↗
PubMed1992

Electrode and bacterial survival with iontophoresis in synthetic urine.

Urinary catheters, especially in patients with long-term catheter requirements, frequently are a source of infection. Iontophoresis has been proposed as a method to decrease or eliminate such infections. Several types of material were examined for their potential use as electrodes in an iontophoretic catheter system. Silver, copper and nickel electrodes did kill microorganisms but did not show longevity. Carbon and gold electrodes showed longevity and killing of microorganisms. Gold proved to be somewhat better than carbon in killing Klebsiella pneumoniae in a broth. Few organisms survived iontophoresis. Those few that survived (mainly Klebsiella in broth), when rechallenged by iontophoresis, did not show any striking resistance to iontophoresis. Our data support the proposition that inclusion of electrodes, depending on the electrode type, in a catheter probably will decrease or eliminate a bacterial population in urine and, thus, may help prevent catheter-related infections and their sequelae.

Bacteria↗
PubMed1992

Iontophoresis generates an antimicrobial effect that remains after iontophoresis ceases.

Iontophoresis required chlorine-containing compounds in the medium for effective microbial population reduction and killing. After iontophoresis ceased, the antimicrobial effect generated by iontophoresis remained but slowly decreased. Antimicrobial effects of iontophoresis may be related to the generation of short-lived chlorine-containing compounds.

Candida albicans↗
PubMed1991

Serum and urinary immunoglobulin in the rat model of acute urinary tract infection.

Total levels of urine and serum immunoglobulin IgM, IgG and IgA, and the E. coli-specific bacterial immunoglobulin response were determined by enzyme-linked immunosorbent assay (ELISA) in a rat model of acute urinary tract infection. High levels of urinary IgM were detected as early as day 3 post infection and then decreased to statistically insignificant levels. Peak levels of IgG occurred in the serum and urine on day 14. Urine and serum IgA levels remained low throughout the study period. The results demonstrate that in the rat model of acute urinary tract infection, IgM appears first in the urine and serum, and rapidly decreases. IgG then appears in the serum and urine followed by a late E. coli-specific immunoglobulin serum and urine response. Also, a non-specific component of the immunoglobulin response was noted in both the serum and urine. In the rat, IgA appears to play little or no role in the urine or in the serum response to the infection.

Acute Disease↗