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L Klotz

Publications and source records attributed to L Klotz.

At least 37 records · Page 2Linked to original sources
PubMed2000

Hyperproliferative hepatocellular alterations after intraportal transplantation of thyroid follicles.

The thyroid hormone 3,5,3'-triiodo-L-thyronine (T3) is a strong direct hepatocyte mitogen in vivo. The effects of T3 resemble those of peroxisome proliferators, which are known to induce hepatocellular tumors in rats. With the aim of studying long-term local effects of thyroid hormones on liver parenchyma, small pieces of thyroid tissue were transplanted via the portal veins into the livers of thyroidectomized male Lewis rats. At 1 week, 3 weeks, 3 months, and 18 months after transplantation, the transplants were found to proliferate, to synthesize thyroglobulin, and to release thyroxine and T3. At 3 and 18 months after transplantation, the hepatocytes of the liver acini downstream of the transplanted follicles showed an increase in cytoplasmic basophilia, a loss of glycogen, an enlargement and hyperchromasia of their nuclei, and a strong increase in cell turnover compared with unaltered liver acini. The altered hepatocytes exhibited an increase in the activities of glucose-6-phosphate dehydrogenase, glucose-6-phosphatase, malic enzyme, mitochondrial glycerol-3-phosphate dehydrogenase, cytochrome-c-oxidase, and acid phosphatase; the activities of glycogen synthase and glycogen phosphorylase were strongly decreased. The hepatocytic alterations downstream of the transplanted follicles could be explained by effects of T3. On the other hand, they resembled alterations characteristic of amphophilic preneoplastic liver foci observed in different models of hepatocarcinogenesis.

Animals↗
PubMed2000

Hepatocellular alterations after intraportal transplantation of ovarian tissue in ovariectomized rats.

The mechanisms of hepatocarcinogenesis by certain synthetic estrogens seem to involve both nongenotoxic and indirect genotoxic effects. However, the natural estrogen estradiol did not exert any carcinogenic effects in established experimental protocols. To elucidate specific long-term effects of natural estrogens on hepatocytes, small pieces of ovarian tissue were transplanted via the portal vein into the livers of ovariectomized female rats. One week, 3 weeks, and 3 months after transplantation the transplants were found to proliferate and to secrete estradiol. Three weeks after transplantation the hepatocytes of the liver acini downstream of the stimulated transplants already showed a remarkable loss of glycogen, distinct cytoplasmic amphophilia, enlargement of their nuclei, a strong increase in the number and size of peroxisomes, an increase in proliferative activity and apoptotic elimination, and changes in the activity of certain key enzymes of energy metabolism. All hepatocellular alterations could be inhibited by the estrogen receptor antagonist toremifene and are, therefore, attributed to specific effects of estradiol produced by the transplants. The observed alterations resemble in some respects amphophilic preneoplastic liver foci, which particularly occur after long-term administration of nongenotoxic hepatocarcinogens, including the adrenal steroid hormone dehydroepiandrosterone. In a preliminary experiment three of six animals exhibited a hepatocellular carcinoma, and another animal developed a hepatocellular adenoma 18 months after intrahepatic ovarian tissue transplantation.

Adenoma↗
PubMed2000

Placebo-associated remissions in a multicentre, randomized, double-blind trial of interferon gamma-1b for the treatment of metastatic renal cell carcinoma. The Canadian Urologic Oncology Group.

OBJECTIVE: To determine the validity of using an historical maximum spontaneous regression rate (reportedly 0-1.1% in those with lung metastases after nephrectomy) in clinical trials of treatments for patients with metastatic renal cell carcinoma (RCC), as the eligibility criteria for most studies will select patients with better performance status (and thus excluding those who are unlikely to respond) and more modern staging methods would potentially reduce the number of false-positives. PATIENTS AND METHODS: A multicentre randomized,placebo-controlled, double-blind trial was recently completed in which 197 patients with metastatic RCC from 17 study centres across Canada were randomized to receive placebo or recombinant interferon gamma-1b (60 microg/m2) subcutaneously once every 7 days until disease progression. All tumour responses were validated by an independent response committee unaware of the treatment. RESULTS: The median (95% confidence interval) overall response rate (complete, CR, and partial, PR) for those on interferon-gamma was 4 (1.4-11.5)% and for those on placebo was 6 (2. 5-13.2)% (P = 0.75). In the six patients who were receiving placebo the CR and PR (three each) was considered to represent spontaneous remission. Of these six patients (aged 44-64 years) five had undergone nephrectomy, one a tumour embolization, four had clear cell carcinoma and one an adenocarcinoma, and all had regression of lung and/or lymph node metastases. CONCLUSION: The lack of efficacy of interferon-gamma in this trial underlines the importance of continued research to identify alternative therapeutic agents or combinations of agents in phase II studies. However, the threshold response rate for initiating phase III trials should be increased to 18% in the phase II trials, i.e. three times the response rate on placebo.

Adult↗
PubMed2000

Intraoperative cavernous nerve stimulation during nerve sparing radical prostatectomy: how and when?

Although nerve-sparing prostatectomy is widely practiced, the results with respect to potency preservation often do not meet expectations. The concept of intraoperative cavernous nerve stimulation is rational. Recent data that link the response to sildenafil after prostatectomy to bilateral nerve sparing has increased the importance of optimizing nerve sparing. The cavernous nerves are often difficult to visualize and may have a variable course. A tumescent response to nerve stimulation can be consistently demonstrated. The response may be subtle, and characterized by a minimal increase in penile circumference and blood flow. Immediately after prostectomy, proximal nerve stimulation identifies whether neural continuity has been maintained, and is predictive of recovery of erectile function. A new device, the Cavermap, has been developed to permit intraoperative nerve stimulation with tumescence monitoring. An initial phase 2 and subsequent phase 3 single blinded, randomized, multicenter study that compared Cavermap-assisted prostatectomy with conventional nerve sparing demonstrated a significant benefit in terms of the duration of nocturnal tumescence by Rigiscan (Timm Medical Technologies, Eden Prairie, Minnesota) at 1 year. Other approaches are being explored, including sural nerve grafting, use of nerve stimulation during cystectomy or abdominal-perineal resection, and direct corpus cavernosum pressure monitoring during nerve stimulation. These approaches warrant further evaluation.

Clinical Trials as Topic↗
PubMed2000

Neurostimulation during radical prostatectomy: improving nerve-sparing techniques.

Considerable variation exists in the reported results of nerve-sparing prostatectomy with respect to potency preservation. This may reflect differences in surgical technique. The Cavermap is a device that uses intraoperative nerve stimulation with real time tumescence monitoring to permit identification of the course of the cavernous nerve fibers during radical prostatectomy. Results of a single center phase 2 and a blinded multicenter phase 3 study have demonstrated an improved outcome compared with conventional nerve sparing with respect to Rigiscan-measured nocturnal erection at 1 year after prostatectomy. The device permits evaluation of the success of nerve-sparing during surgery. Further studies of the effectiveness of the Cavermap device are warranted.

Clinical Trials as Topic↗
PubMed2000

Differences between urologists in the United States and Canada in the approach to prostate cancer.

PURPOSE: We examine differences in screening, detection, staging and treatment of prostate cancer between urologists in the United States and Canada. MATERIALS AND METHODS: An anonymous questionnaire was developed and mailed to 700 randomly selected American and 350 Canadian urologists. The 7 domains of prostate cancer management comprised screening/case identification, radical prostatectomy indications, staging evaluations, neoadjuvant therapy, nerve sparing techniques, postoperative management and treatment of biochemical recurrence. The Dillman method of questionnaire administration was used. All data were stratified by country and analyzed using the generalized chi-square test. RESULTS: Surveys were adequately completed by 45% and 79% of American and Canadian urologists, respectively. Practice experience and clinical volumes were not significantly different between the 2 cohorts. Overall, there were few differences in prostate cancer screening, staging, postoperative management, biochemical failure and use of neoadjuvant therapy. However, practicing American urologists tended to pursue more aggressive case finding practices, such as a higher age cutoff for prostate specific antigen testing (p = 0.0001) and more frequent use of transition zone biopsies (p = 0.0001). American urologists also displayed a tendency toward more liberal indication for extirpative surgery. They were more likely to perform radical prostatectomy in men older than 70 years, those with higher prostate specific antigen and those with node positive disease. Among both national cohorts there was considerable variation in management patterns for all domains of prostate cancer. Variation was most common among treatment of patients with adverse pathological conditions (positive margins, seminal vesicle involvement) and postoperative biochemical failure. Even when credible evidence exists (biopsy technique, preoperative staging) significant proportions of urologists in both countries continued to practice contrary to existing data. CONCLUSIONS: American and Canadian practice patterns for prostate cancer differ significantly only in the domains of case identification and surgical indications. In addition, considerable intra-national variation in practice patterns exists. These data highlight the necessity to support randomized clinical trials in prostate cancer.

Canada↗
PubMed2000

p53 nuclear accumulation is not associated with decreased disease-free survival in patients with node positive transitional cell carcinoma of the bladder.

PURPOSE: Although the majority of patients with node positive transitional cell carcinoma of the bladder have disease progression, a definitive subset is cured by surgery only. Nuclear accumulation of p53 has been associated with disease progression in patients with superficial transitional cell carcinoma and decreased survival in those with muscle invasive disease. We determined whether p53 status would predict survival in a cohort with nodal metastasis. MATERIALS AND METHODS: We explored the comprehensive database of all 199 radical cystectomies performed at our institution between July 1988 and September 1999. The 59 patients in this database with node positive pathology comprise our study. We performed immunohistochemical analysis of specimens using the MAB1801 antibody with greater than 20% lymph node and primary tumor nucleus staining deemed positive. Additional covariates measured included patient age, sex, pathological disease stage, adjuvant chemotherapy and nodal stage. Disease-free survival curves were generated for the various covariates and compared using the log rank test. The Cox proportional hazards technique was used to determine covariate adjusted p53 survival. RESULTS: In the cohort overall median disease-free survival was only 21 months, although 18% of patients were disease-free at 5 years. There was evidence of p53 nuclear accumulation in 54% of cases and complete agreement of nodal with bladder p53 nuclear accumulation. No significant baseline differences were noted in the covariates with respect to p53 nuclear accumulation. For stratum specific disease-free survival univariate and multivariate analyses revealed that only pathological stages p0-p2b versus p3-p4 (hazards ratio 2.86, p = 0.03), and nodal stages N2 versus N1 and N3 versus N1 (hazards ratio 3.84, p = 0.01 and hazards ratio 13.3, p = 0.0002, respectively) were significantly associated with prolonged disease-free survival, while p53 nuclear accumulation was not. CONCLUSIONS: Despite credible evidence for p53 nuclear accumulation prognostication in patients with in situ and invasive transitional cell carcinoma, this marker is not predictive of disease-free survival in node positive disease.

Aged↗
PubMed2000

A randomized phase 3 study of intraoperative cavernous nerve stimulation with penile tumescence monitoring to improve nerve sparing during radical prostatectomy.

PURPOSE: We determine if mapping of the cavernous nerve during radical prostatectomy using intraoperative cavernous nerve stimulation with tumescence monitoring results in improved erectile potency compared to conventional nerve sparing. MATERIALS AND METHODS: A prospective, randomized, single blinded study was performed on 61 patients at 6 centers. Patients had elected to undergo nerve sparing prostatectomy and had normal preoperative erectile function documented by the Sexual Function Inventory Questionnaire (SFIQ) and RigiScan parallel testing. Patients were randomized between conventional nerve sparing and nerve sparing assisted by the CaverMap Surgical Aid. paragraph sign In all patients neural continuity was assessed immediately after prostate removal by proximal cavernous nerve stimulation. All patients were blinded according to their allocation cohort. RESULTS: At 1 year there was substantial improvement in erectile function in the CaverMap group as measured by RigiScan. This group had a mean of 15. 9 minutes of greater than 60% nocturnal tumescence compared to 2.1 minutes in the conventional nerve sparing group (p <0.024). By SFIQ there was a nonsignificant trend to improved potency in the CaverMap group (71% versus 62%, p = 0.17). Of patients who had bilateral, unilateral and no response to stimulation after resection erectile function assessed by SFIQ recovered in 68%, 27% and 0%, respectively (p = 0.016). CONCLUSIONS: CaverMap assisted prostatectomy led to improved erectile function as assessed by RigiScan testing with no associated adverse events. A response to stimulation immediately after removal of the prostate accurately predicted return of erectile function.

Adult↗
PubMed2000

Neoadjuvant hormone therapy: the Canadian trials.

The Canadian Urologic Oncology Group has carried out three studies of neoadjuvant hormonal therapy (NHT) in prostate cancer. The first, a study of 3 months of cyproterone acetate (CPA) 100 mg TID in patients undergoing external-beam radiation therapy, showed a benefit with respect to time to biochemical progression. There are no survival or clinical progression data available from this study. The second study involved 3 months of CPA prior to radical prostatectomy compared with radical prostatectomy alone and enrolled 200 patients. The probability of biochemical progression at 36 months was similar in the two groups (CPA 40%; surgery alone 30%; P = 0.3233). More recently, we have carried out a randomized trial of 3 v 8 months of leuprolide plus flutamide prior to radical prostatectomy in 547 patients. Patients were stratified by clinical stage, Gleason grade, and serum prostate specific antigen (PSA) concentration. In the 3- and 8-month groups, presurgery PSA concentrations were <0.1 ng/mL in 35% v 73%, and >0.3 ng/mL in 37% v 10%, respectively. In the 3- and 8-month groups, the positive margin rates were 17% and 5% and the organ-confined rates 71% and 91% (P < 0.01). One-year follow-up is now available on the entire cohort. Data regarding time to biochemical and clinical progression and overall and disease-specific survival will be required to determine whether this change in the pathologic findings translates into a patient benefit.

Androgen Antagonists↗
PubMed2000

Precancerous lesions in the kidney.

Renal cell carcinoma (RCC), although occurring less frequently than prostate and bladder cancer, is actually the most malignant urologic disease, killing >35% of affected patients. Therefore, investigation of the nature of premalignant lesions of the kidney is a relevant issue. Following the most recent histological classification RCC can be subdivided into four categories: conventional RCC; papillary RCC; chromophobe RCC; and collecting duct carcinoma. In contrast to many genitourinary malignancies, premalignant alterations in the kidney are scarcely described. Intratubular epithelial dysplasia has been recognized as the most common precursor of RCC. In analogy to prostatic intraepithelial neoplasia (PIN), the premalignant lesions of the kidney are described as high or low-grade renal intratubular neoplasia. In contrast, precancerous lesions have been described as part of the von Hippel-Lindau syndrome (VHL) where the evolution from a simple cyst to an atypical cyst with epithelial hyperplasia to cystic or solid conventional-type RCC is well documented. Finally, in the genesis of papillary RCC an adenoma-carcinoma sequence has been recognized with specific genetic changes. There are no data on the epidemiology of premalignant lesions of the kidney, but research into the etiology of RCC has been extended substantially. Familial and genetic factors are well documented in VHL disease, in hereditary papillary RCC, in the tuberous sclerosis complex and in familial RCC. Cigarette smoking and obesity are established risk factors for RCC. Hypertension or its medication has also been associated with an increased risk. Among dietary factors an inverse relation between risk and consumption of vegetables and fruit has been found. Occupational exposure to substances such as asbestos and solvents has been linked to an increased risk of RCC. Specific RCC variants have distinctive chromosome alterations and several genes have been implicated in the development of RCC. Loss of material from the 3p chromosome characterizes conventional RCC and the deletion of the VHL suppressor gene plays an important role in the genesis of this RCC variant. In contrast, numerical changes with trisomy of chromosomes 7 and 17 and loss of the sex chromosome are typical changes in papillary tumors, whereas papillary RCC have additional trisomies. Chromophobe RCC is characterized by loss of chromosomes with a combination of monosomies. Less consistent genetic alterations are associated with collecting duct carcinoma. The traditional treatment of RCC is surgery by radical or partial nephrectomy. The latter approach carries a risk of tumor recurrence as a result of unrecognized satellite lesions or premalignant lesions that might have been present at the time of surgery. However, the reported recurrence rates after partial nephrectomy are <1% and therefore the possible presence of premalignant disease does not alter the actual treatment strategy advocated. Although multifocality and bilateral occurrence of RCC are much more likely in cases of papillary RCC, biopsy of the renal remnant or contralateral kidney is not justified even in patients with this tumor type. Conversely, patients with RIN in a partial or radical nephrectomy specimen or in a renal biopsy taken for whatever reason should be subjected to closer follow-up with regularly repeated ultrasound. When an effective chemopreventive regimen becomes available it might be useful for patients with an inherited risk of RCC as well as in those who are at risk of tumor recurrence after intervention. Mass screening with the purpose of detecting RCC at its earliest stage is not recommended at the present time, but screening focused on certain risk groups can be advocated. Further research is needed to identify avoidable risks, develop effective chemoprevention and recognize patients at risk.

Carcinoma, Renal Cell↗
PubMed1999

A phase 1-2 trial of diethylstilbestrol plus low dose warfarin in advanced prostate carcinoma.

PURPOSE: This prospective study was designed to determine the safety and efficacy of low dose warfarin in the prophylaxis of thromboembolic disease in patients receiving diethylstilbestrol therapy for advanced prostatic carcinoma. MATERIALS AND METHODS: Patients were stratified to receive 1 mg. warfarin and 3 mg. diethyl-stilbestrol daily (younger than 65 years) or 1 mg. warfarin and 2 mg. diethylstilbestrol daily (older than 65 years). Efficacy of therapy was determined by measuring serum prostate specific antigen (PSA), testosterone and international normalized ratio. Patients were monitored for signs and symptoms of hypercoagulability, bleeding and fluid retention. RESULTS: Of the 32 patients enrolled in the study 6 were lost to followup and 4 died of advanced prostatic disease (2), pneumonia (1) and myocardial infarction (1). Patients were followed for a total of 272 months. Median patient age was 73.5 years. Median pretreatment serum PSA was 95.4 microg./l. with a median pretreatment serum testosterone value of 12.9 nmol./l. After 3 months of therapy the median serum PSA was 1.5 microg./l. with a median serum testosterone value of 0.1 nmol./l. Adverse events were common. In 10 patients (31%) clinically significant proximal deep venous thrombosis developed, 2 (7%) had a myocardial infarction, 2 (7%) had transient ischemic attacks, 1 had new prolonged chest pain and 1 had marked dyspnea due to congestive heart failure. Clotting factor assays performed in a subset of 7 patients demonstrated that factor VII failed to normalize. CONCLUSIONS: The significant thromboembolic toxicity associated with the hypercoagulable state induced by diethylstilbestrol is not reduced by fixed low dose warfarin therapy.

Adult↗
PubMed1999

Prevalence and patterns of the use of complementary therapies among prostate cancer patients: an epidemiological analysis.

PURPOSE: We determine the prevalence and patterns of the use of complementary therapies among patients with and those at high risk for prostate cancer. MATERIALS AND METHODS: A cross-sectional survey was performed of men presenting to 2 urban tertiary urology clinics for prostate cancer evaluation or followup, and those attending a prostate cancer support group. All men diagnosed with and those at high risk (positive family history or abnormal prostate specific antigen) for prostate cancer were eligible for study. A 9-item self-administered, anonymous questionnaire about complementary therapies was administered. RESULTS: Of 357 patients who received the survey 155 from the urology clinics and 113 from the support group responded, for a total response rate of 75%. Of the patients presenting to urology clinics and the support group 27.4 and 38.9% with and 25.8 and 80% at high risk for prostate cancer, respectively, used some form of complementary therapy. The use significantly differed according to disease status (p = 0.001), and was highest among men who were clinically disease-free after radical therapy. Of the patients 24% did not inform the urologist of using alternative therapy. CONCLUSIONS: The prevalence of the use of complementary therapy among patients with or at increased risk for prostate cancer was high and dependent on the disease state. Urologists should be aware of this pattern of use, and consider the potential effects when assessing patients for and with prostate cancer.

Aged↗
PubMed1998

Early experience with intraoperative cavernous nerve stimulation with penile tumescence monitoring to improve nerve sparing during radical prostatectomy.

OBJECTIVES: To determine if intraoperative stimulation of the cavernous nerves while monitoring changes in penile tumescence to map the course of these nerves would result in an improvement in nerve sparing and erectile function after radical prostatectomy. METHODS: Patients were eligible for this pilot study if they were undergoing a radical prostatectomy and were candidates for a nerve-sparing approach. Erectile function was assessed by patient self-reporting and questionnaire before surgery and by patient self-reporting periodically 12 months after surgery. A cavernous nerve stimulator and tumescence-monitoring device was used during radical prostatectomy to identify the course of the cavernous nerves and guide the surgeon in avoiding nerve damage. Patients were monitored for any evidence of complications and/or adverse events for 1 year from time of surgery. RESULTS: Twenty-six patients were recruited to the trial. Nerve stimulation and tumescence monitoring was performed in 23 patients. Twenty-one of 23 patients demonstrated a tumescence response to intraoperative nerve stimulation. Nineteen of 21 patients reported erectile function preoperatively. Seventeen (89%) of 19 patients demonstrated a tumescence response during surgery. Sixteen (94%) of the 17 patients who demonstrated a response to nerve stimulation and for whom the surgery was guided by the tumescence response reported the ability to have erections after surgery. No side effects due to the use of the device were reported. Only 3 (12%) of 25 patients had positive margins confined to the lateral margin and/or apex whose modifications associated with nerve sparing could conceivably have altered margin status. CONCLUSIONS: These clinical data suggest that an intraoperative tumescence response to cavernous nerve stimulation may guide the surgeon in preserving cavernous nerves and improving erectile function after radical prostatectomy.

Aged↗
PubMed1995

Orchidectomy and hormonal therapy of prostate cancer.

The objective of this study is to document the use of hormonal therapies in treating prostate cancer in Ontario in the last decade. Drug utilization data were extracted from the Ontario Drug Benefit Program, while surgical orchidectomy rates were calculated from Hospital Medical Records Institute data. The provincial rate of orchidectomy showed a 55% relative increase from 1981 to 1991. There was a 6.4-fold variation in orchidectomy rates among counties in Ontario. As well, the expenditures on new hormonal therapies rose 38-fold between 1985 and 1990, and doubled between 1990 and 1992. There was no consistent relationship between use of orchidectomy and hormonal drug therapy at the county level. We conclude that both forms of hormonal therapy have increased in Ontario. The wide variation in surgical orchidectomy rates observed in Ontario suggests differences in practice styles and possible medical uncertainty. Guidelines for the hormonal therapy of prostate cancer may be a helpful step forward for practitioners and patients.

Journal Article↗