Ochratoxin A, ubiquitous mycotoxin contaminating human food

Ochratoxin A (OTA) a mycotoxin produced by molds of the Aspergillus and Penicillium genera, contaminates animal feeds and human foods. It has been shown to induce renal adenomas and hepatocellular carcinomas in rodents. OTA is implicated in Balkan endemic nephropathy, a disease followed by a high incidence of urinary tract tumours. Concerning the genotoxicity of OTA, we have recently shown, using the [32P]-phosphate postlabelling method, that several DNA-adducts are formed in four mice organs treated with OTA. Some of the adducts were specific of every analyzed tissue. These results, allow us to state that OTA metabolism in different from organ to organ. The influence of OTA metabolism on its genotoxic effect was studied. Preliminary results have shown the possibilities of oxidative pathways in OTA metabolism leading to genotoxic compounds. Effects of some vitamins such as retinol (A), ascorbic acid (C) and tocopherol (E), which are known to act as superoxide anion scavengers, were tested on genotoxicity of OTA. Pretreatment of mice by vit E induced a decrease of the DNA-adducts by 80% in kidney, and by 55% in liver. Vit A and vit C decreased DNA-adduct levels by 70% in kidney. In liver, DNA adduct level was essentially decreased by vit C (90%). Vit A decreased only the level by 25% in this organ. The involvement of oxidative metabolism in the genotoxicity of OTA led us to investigate the effect of prostaglandin H synthase (PHS) which is known to cooxidase xenobiotics. Aspirin and indomethacin which inhibit this enzyme were given prior to OTA administration to mice in order to test this metabolic pathway. The decrease observed with aspirin was of about 90% and 30% in kidney and liver respectively, and of 90% and 80% with indomethacin in kidney and liver. These results confirmed that OTA is activated to genotoxic metabolites by cooxydation by the prostaglandin synthase route. Human bronchial epithelial cells (BEAS-2B) expressing or not human cytochrome P450s (CYP) (1A2, 2A6, 2D6, 2E1 and 3A4) were incubated with 0.5 microM OTA for 24 h. DNA-adducts were detected in all cells. Total DNA-adduct levels ranged from 4 to 85 adducts per 10(9) nucleotides. Some adducts were common to all cell types including cells expressing only normal phase II enzymes, but no cytochromes P450. Some other DNA-adducts were only induced by specific CYPs. The highest DNA-adduct level was found in cells where CYP 1A2 was expressed. Nevertheless, more different types of DNA-adducts were formed in cells expressing CYP 2D6.(ABSTRACT TRUNCATED AT 400 WORDS)     

Comparison of DNA-adduct and tissue-available dose levels of MeIQx in human and rodent colon following administration of a very low dose

[2-14C]2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) was administered orally (304 ng/kg body-weight dose based upon an average 70-kg-body-weight subject) to 5 human colon-cancer patients (58 to 84 years old), as well as to F344 rats and B6C3F1 mice. Colon tissue was collected from the human subjects at surgery and from the rodents 3.5 to 6 hr after administration. Colon DNA-adduct levels and tissue available doses were measured by accelerator mass spectrometry (AMS). The mean levels of MeIQx in the histologically normal colon tissue were not different among the human (97 +/- 26 pg MeIQx/g), rat (133 +/- 15 pg/g) or mouse (78 +/- 10 pg/g) tissues; and no difference existed between the levels detected in human normal and tumor tissue (101 +/- 15 pg/g). Mean DNA-adduct levels in normal human colon (26 +/- 4 adducts/10(12) nucleotides) were significantly greater (p < 0.01) than in rats (17.1 +/- 1 adduct/10(12) nucleotides) or mice (20.6 +/- 0.9 adduct/10(12) nucleotides). No difference existed in adduct levels between normal and tumor tissue in humans. These results show that MeIQx forms DNA adducts in human colon at low dose, and that the human colon may be more sensitive to the effects of MeIQx than that of mice or rats.     

Sensitization to doxorubicin resistance in breast cancer cell lines by tamoxifen and megestrol acetate

Acquired drug resistance is a major factor in the failure of doxorubicin-based chemotherapy in breast cancer. We determined the ability of megestrol acetate and/or tamoxifen to reverse doxorubicin drug resistance in a doxorubicin-resistant breast cancer line (the human MCF-7/ADR). The cytotoxicity of doxorubicin, megestrol acetate, and/or tamoxifen was determined in the sensitive and resistant cell lines utilizing the sulphorhodamine B assay. Tamoxifen alone produced an IC50 (concentration resulting in 50% inhibition of control growth) of 10.6 microM, whereas megestrol acetate alone resulted in an IC50 of 48.7 microM in the MCF-7/ADR cell line. The IC50 of doxorubicin in MCF-7/ADR was 1.9 microM. Neither megestrol acetate alone nor tamoxifen alone at 1 or 5 microM altered the IC50 of doxorubicin. However, the combination of tamoxifen (1 or 5 microM) and megestrol acetate (1 or 5 microM) synergistically sensitized MCF-7/ADR cells. Additionally, megestrol acetate and tamoxifen inhibited iodoarylazidoprazosin binding to P-glycoprotein, and, in their presence, there was an increased doxorubicin accumulation in the MCF-7/ADR cells. Furthermore, the combination of tamoxifen and megestrol acetate had much less effect on the cytotoxicity of doxorubicin in MCF-7 wild-type cells. Clinically achievable concentrations of tamoxifen and megestrol acetate can largely sensitize MCF-7/ADR to doxorubicin. The combination of these three drugs in a clinical trial may be informative.     

Ciprofloxacin pharmacokinetics in burn patients

Cyproterone acetate (CPA), a synthetic progestin recently found to induce genotoxic effects in hepatocytes from female rats and from humans of both genders, and two structural analogues, chlormadinone acetate (CMA) and megestrol acetate (MGA), have been compared for their capacity to induce DNA repair synthesis as measured by quantitative autoradiography. Exposure of primary human hepatocytes for 20 h to concentrations of CPA, CMA and MGA ranging from 2 to 50 microM induced positive responses in cultures from donors of both genders and the amounts of DNA repair elicited by the three progestins were similar. Under the same experimental conditions substantial differences were observed in the amounts of DNA repair elicited by the three progestins in primary hepatocytes from female rats, their potency decreasing in the following order CPA > CMA > MGA, and the three compounds failed to induce DNA repair in hepatocytes from male rats. These results, which agree with previous findings, suggest that for these sex steroids extrapolation to humans of results obtained in rats might be questionable.     

Antiandrogen withdrawal syndrome

The antiandrogen withdrawal syndrome was first reported in patients with prostate cancer who manifested disease progression after total androgen blockage therapy with medical or surgical castration and pure antiandrogen, flutamide; discontinuation of flutamide resulted in a decline in prostate specific antigen and, in some cases, with clinical response. Same phenomena have been reported after the withdrawal of casodex, chlormadinone acetate, megestrol acetate, diethylstilbestrol, and estramustine phosphate. Mutations in the androgen receptor(AR) gene were discovered in clinical specimens of human prostate cancer patients who showed this syndrome and some of these being identical to the mutation found in LNCaP prostate cancer cell line. Another mechanism otherwise the point mutation of AR would be also speculated.     

Antiandrogen withdrawal syndrome with cyproterone acetate

OBJECTIVES: To determine whether the antiandrogen withdrawal syndrome occurs with the steroidal antiandrogen cyproterone acetate. METHODS: Cyproterone acetate was withheld in 12 patients with progressing androgen-independent metastatic prostate cancer. Eight patients had been receiving cyproterone acetate concomitant with androgen ablation, and in 4 patients it was prescribed after failure of androgen suppression. Time to response and to disease progression were defined by serum prostate-specific antigen (PSA) levels and imaging studies. RESULTS: PSA levels decreased in 5 of the 1 2 patients; in 4 of them (33%), the decrease exceeded 50%. The decline lasted a median of 24 weeks (range 9 to 37.8). All 5 patients had received initial concomitant exposure to androgen ablation and cyproterone acetate. CONCLUSIONS: We recommend that the steroidal antiandrogen cyproterone acetate be added to the list of agents capable of inducing antiandrogen withdrawal syndrome.     

Covalent binding of acidic drugs via reactive intermediates: detection of benoxaprofen and flunoxaprofen protein adducts in biological material

The purpose of the study was the direct detection of intact protein adducts-resulting from in-vitro incubations of flunoxaprofen- and benoxaprofen glucuronides in biological materials or originating from in vivo studies-by polyacrylamide gel electrophoresis (SDS-PAGE) followed by blotting and fluorescent scan, presumably yielding better specificity for the macromolecular binding partner and avoiding alkaline cleavage to release the aglycone. Glucuronides were isolated from urine samples or generated by incubation of aglycone with cofactors and rat liver microsomes. Following dialysis against BSA solution, SDS-PAGE and subsequent electrotransblotting were performed. Apparently, albumin represents the major binding protein for the covalent binding of these acyl glucuronides in plasma following incubation with blank plasma. In microsomal proteins two fluorescent peaks (appr. 39 and 62 KD) were identified for flunoxaprofen and benoxaprofen incubations. In vivo covalent binding was detected for both flunoxaprofen and benoxaprofen in plasma samples. For the racemically administered benoxaprofen a slight preponderance in adduct concentrations was found for the S-enantiomer. The pharmacokinetic analysis of in vivo data obtained for R/S-benoxaprofen (dose: 600 mg racemate) and S-flunoxaprofen (dose: 100 mg racemate), both of which have been withdrawn from the market, (employing a stereospecific HPLC method when analyzing volunteers' and patients' samples collected in the last 14 years, yet not stored longer than 3-4 years) demonstrated that significant amounts of glucuronides occur for both drugs (n = 2 for each compound; average Cmax values of the glucuronides: S-flunoxaprofen: 395 ng/ml; S-benoxaprofen: 775 ng/ml; R-benoxaprofen: 563 ng/ml). Presumably because of stereoinversion in humans, aglycone and glucuronide concentrations were higher for S- than for R-benoxaprofen. In vivo aglycone/glucuronide ratios were smaller for S- than for R-benoxaprofen, although in vitro incubation with human liver microsomes resulted in preferential glucuronidation of the R-enantiomer of benoxaprofen. Plasma concentration-time curves of the glucuronides paralleled those of the respective aglycones in their terminal phase. S-Benoxaprofen adduct concentrations were higher than R-benoxaprofen adduct concentrations (S: 28 ng/ml; R: 18 ng/ml covalently bound) and S-flunoxaprofen adduct concentrations with 29 ng/ml in the same range as S-beoxaprofen adducts, although for the latter the dose range as well as the respective glucuronide concentrations were higher. This indicates a higher reactivity of S-flunoxaprofen as opposed to S-benoxaprofen glucuronides.     

Bone marrow relapse in high-risk pediatric patients with acute lymphoblastic leukemia: a comparison of relapse times and initial clinical features of patients on different protocols. Children''s Cancer and Leukemia Study group (CCLSG)

Alpha adrenergic blocker has become the first choice in the medical treatment of benign prostatic hyperplasia (BPH). The efficacy of alpha adrenergic blocker has been suggested to be related to the prostatic tissue components, and to be ineffective in treating the clinical symptoms caused by BPH in some cases. The efficacy and prostate reduction of an anti-androgenic agent, chlormadinone acetate, combined with alpha adrenergic blocker, tamsulosin hydrochloride, were evaluated using 40-BPH patients insufficiently treated with tamsulosin hydrochloride alone. Fifty mg of chlormadinone acetate and 0.2 mg of tamsulosin hydrochloride were administered orally once a day for 16 weeks to patients with a prostate subjective symptoms score, I-PSS, of greater than 13 or a peak flow rate of less than 12 ml/s, even after the treatment with 0.2 mg of tamsulosin hydrochloride alone for more than four weeks. Total I-PSS decreased significantly after four weeks. The total irritative symptom score did not change for 16 weeks, but the total obstructive symptom score decreased significantly, as did the total I-PSS. In objective data, the estimated volume of both total prostate and the transition zone on transrectal ultrasonogram decreased significantly at the end of the treatment, and the peak flow rate decreased significantly after 12 weeks. These findings suggest that the addition of chlormadinone acetate may be a reasonable alternative in the treatment of BPH patients responding insufficiently to tamsulosin hydrochloride alone, and that combination therapy using chlormadinone acetate and tamsulosin hydrochloride may be useful for BPH patients with serious obstructive symptoms.     

Interactions between pacemakers and security systems

BACKGROUND: Hot flashes are often a troublesome symptom in breast carcinoma survivors and men with prostate carcinoma who have undergone androgen deprivation therapy. A previous clinical study demonstrated that, on a short term basis, low dose megestrol acetate markedly reduced hot flashes and was well tolerated. Little information has been available regarding the long term use of low dose megestrol acetate for hot flashes. METHODS: Patients previously enrolled on a randomized placebo-controlled trial that evaluated the short term use of megestrol acetate for hot flashes were contacted and interviewed by telephone. RESULTS: A total of 132 persons were contacted. Nine percent of the patients discontinued megestrol acetate after resolution of their hot flashes. Forty-five percent of the patients contacted were continuing to utilize megestrol acetate approximately 3 years beyond the conclusion of the 1992 study. Three-quarters of these patients were utilizing < or =20 mg of megestrol acetate per day. Potential toxicities attributed to megestrol acetate included episodes of chills, appetite stimulation/weight gain, vaginal bleeding, and carpal tunnel syndrome symptoms. CONCLUSIONS: A substantial proportion of patients continue to use megestrol acetate for periods of up to 3 years or longer with continued control of hot flashes. This treatment appears to be relatively well tolerated.     

Anastrozole versus megestrol acetate in the treatment of postmenopausal women with advanced breast carcinoma: results of a survival update based on a combined analysis of data from two mature phase III trials. Arimidex Study Group

BACKGROUND: This report presents the results of a survival update based on the combined data from two studies that compared the efficacy and tolerability of anastrozole (1 or 10 mg once daily), a selective, nonsteroidal aromatase inhibitor administered orally, and megestrol acetate (40 mg 4 times daily) in the treatment of postmenopausal women with advanced breast carcinoma whose disease had progressed after treatment with tamoxifen. METHODS: Two randomized, parallel-group, multicenter trials were conducted, involving a total of 764 patients. The two trials were identical in design; both were double blind for anastrozole and open label for megestrol acetate. Overview analyses were conducted with the intent of strengthening the interpretation of results from each trial. The median follow-up duration for this survival update was 31 months. RESULTS: At the clinical dose of 1 mg daily, anastrozole demonstrated a statistically significant survival advantage over megestrol acetate, with a hazard ratio of 0.78 (P < 0.025)(0.60 < 97.5% confidence interval [CI] <1.0). The 1 mg anastrozole group also had a longer median time to death (26.7 months) compared with 22.5 months for the megestrol acetate group. The 10 mg anastrozole group also had a survival benefit over the megestrol acetate group, with a hazard ratio of 0.83 (P=0.09, not significant)(0.64 < 97.5% CI < 1.1). Higher 2-year survival rates were observed for both anastrozole treatment groups than for the megestrol acetate group (56.1%, 54.6%, and 46.3% for the groups given 1 mg anastrozole, 10 mg anastrozole, and megestrol acetate, respectively). CONCLUSIONS: This combined analysis of two trials of postmenopausal patients with advanced breast carcinoma has clearly demonstrated that, after disease progression with tamoxifen, treatment with anastrozole 1 mg once daily results in a statistically and clinically significant advantage over a standard treatment, megestrol acetate. This important benefit, in addition to the good tolerability profile of anastrozole, supports the use of this drug as a valuable new treatment option for this patient population.     

Pharmacokinetic interaction of megestrol acetate with zidovudine in human immunodeficiency virus-infected patients

This nonrandomized, two-period crossover study was performed to assess whether concomitant administration of megestrol acetate influences the steady-state pharmacokinetics of zidovudine and its inactive 5'-O-glucuronide metabolite. Twelve HIV-positive, asymptomatic male volunteers received a 100-mg oral capsule dose of zidovudine at least 30 min before meals five times a day at 0700, 1100, 1500, 1900, and 2300 h on study days 1 to 3 and a single 100-mg dose at 0700 h on day 4. On days 5 to 17, 800 mg of megestrol acetate, as a 40-mg/ml aqueous suspension, was administered orally immediately before the 0700 h dose of zidovudine. On days 5 to 16, zidovudine was also administered at 1100, 1500, 1900, and 2300 h. Serial blood samples were collected for 12 h after the single 100-mg dose of zidovudine on days 4 and 17; trough samples were also obtained just before the 0700 h dose on days 2 to 4 and 15 to 17. Levels of zidovudine and its glucuronide in plasma were assayed by a validated radioimmunoassay. Statistical analysis of trough plasma level data indicated that steady-state levels of zidovudine and its glucuronide in plasma had been attained when pharmacokinetic assessments were made on days 4 and 17. When megestrol acetate and zidovudine were coadministered for 13 days, differences of -14, -6.5, and -4.6% in mean zidovudine peak concentration and areas under the curve at 0 to 4 and 0 to 12 h, respectively, +22.5% in mean trough concentration, +2.6% in mean plasma half-life, and no change in median time to peak were observed compared to conditions when zidovudine was administered alone; for zidovudine 5'-O-glucuronide the respective differences were -9, -7.3, -4.4, +2.3, and +10% and no change. None of the differences were statistically significant (P > 0.05). Concomitant therapy with megestrol acetate, at the dose employed to treat anorexia, cachexia, or an unexplained, significant weight loss in AIDS patients, did not alter the steady-state pharmacokinetics of zidovudine or its 5'-O-glucuronide metabolite.     

Clearance of N-nitrosodimethylamine and N-nitrosodiethylamine by the perfused rat liver. Relationship to the Km and Vmax for nitrosamine metabolism

The first-pass clearance of dietary N-nitrosodimethylamine (NDMA) by the liver is the most important factor in the pharmacokinetics of this carcinogen in the rat, but is less important in the pharmacokinetics of N-nitrosodiethylamine (NDEA). The reason for the difference in clearance of these two nitrosamines is not known. These experiments were carried out to see whether the general characteristics of the clearance of these two carcinogens in vivo could be reproduced in the perfused liver, and whether the clearance could be correlated with the Michaelis-Menten parameters Km and Vmax for their metabolism. If this could be done one would be able to predict the possible extent of first-pass clearance of nitrosamines in man from measurement of Km and Vmax for nitrosamine metabolism by the human liver. The Km (22 microM) and Vmax (10.2 and 13.4 nmol/g liver/min) for the metabolism of NDMA by slices from two human livers, the inhibition of that metabolism by ethanol (Ki 0.5 microM), and the rate of N-7 methylation of DNA when slices are incubated with NDMA, were measured. These results are similar to those reported previously with rat liver. The Km (27 microM) for the metabolism of NDEA by rat liver slices and the inhibition of that metabolism by ethanol (Ki 1 microM) were estimated from the rate of ethylation of the DNA of the slices. The clearance of both these nitrosamines by the perfused rat liver was measured, and the results appeared to parallel those in vivo with a striking difference between the clearance of NDMA and NDEA. The maximal rate of clearance of NDMA was 11.2 nmol/g liver/min and of NDEA 8.9 nmol/g liver/min, similar to the Vmax for metabolism of NDMA by liver slices and to the estimated maximal rate of liver metabolism of both nitrosamines in the living rat. However, although the Km for metabolism of these two nitrosamines by liver slices is similar (about 25 microM), the logarithmic mean sinusoidal concentration [see Bass and Keiding, Biochem Pharmacol 37: 1425-1431, 1988] giving half maximal clearance during perfusion (the equivalent to Km) was 2.3 microM for NDMA and 10.6 microM for NDEA. The almost 5-fold difference between these two values is the basis for the difference between the clearance of the two nitrosamines.(ABSTRACT TRUNCATED AT 400 WORDS)     

Intrauterine growth restriction: a genetic perspective

BACKGROUND: Anastrozole is a new oral aromatase inhibitor with highly potent and selective activity for the aromatase enzyme. In a Phase III trial, the efficacy and tolerability of anastrozole, given in doses of 1 and 10 mg orally once daily, and megestrol acetate, given in doses of 40 mg orally 4 times daily, were compared in 386 postmenopausal women with advanced breast carcinoma who progressed after tamoxifen therapy. METHODS: The trial was randomized, double blind for anastrozole, open label for megestrol acetate, parallel group, and multicenter. Patients were randomly assigned to receive anastrozole, 1 mg (n = 128); anastrozole, 10 mg (n = 130); or megestrol acetate (n = 128). The primary efficacy measures were time to progression and tumor response; secondary measures were time to treatment failure, duration of response, quality of life, and time to death. RESULTS: With a median duration of follow-up of 6 months, there was no statistical evidence of a difference between either 1 or 10 mg doses of anastrozole and megestrol acetate for any efficacy endpoint. According to rigid response criteria, 10%, 6%, and 6% of patients in the anastrozole 1 mg, anastrozole 10 mg, and megestrol acetate groups, respectively, had an objective response (complete response or partial response) and 27%, 24%, and 30% of patients in the respective groups had stable disease for a duration of 24 weeks or longer. Quality-of-life assessments revealed that anastrozole in a 1-mg dose was associated with better physical scores and anastrozole in a 10-mg dose with better psychologic scores than megestrol acetate. Both anastrozole and megestrol acetate were generally well tolerated. Among anticipated adverse events, gastrointestinal disturbance was more common among patients in the anastrozole groups, whereas weight gain occurred more frequently among patients in the megestrol acetate groups. Weight increases of 5% or more and 10% or more were more common among megestrol acetate-treated patients; moreover, patients in this group continued to gain weight over time. CONCLUSIONS: Anastrozole, given in doses of 1 and 10 mg once daily, represents a well tolerated and effective therapeutic option for the treatment of postmenopausal women with advanced breast carcinoma who progress after tamoxifen treatment.     

Evidence for negative charge in the conduction pathway of the cardiac ryanodine receptor channel provided by the interaction of K+ channel N-type inactivation peptides

1. Precision-cut liver slices represent a suitable and convenient in vitro preparation for studying metabolism and toxicity mechanisms of drugs and toxic chemicals. Particularly in the case of human liver slices, cryopreservation would enable more efficient utilization of this scarce and irregularly available tissue. 2. Liver slices from consecutive human livers were cryopreserved using a method previously developed for rat and monkey liver slices. This procedure involves incubation in 12% dimethyl sulphoxide for 30 min on ice and direct immersion into liquid nitrogen. 3. Functional integrity of cryopreserved human liver slices, as compared with that of fresh liver slices, was maintained at 66 +/- 8% (alanine aminotransferase activity retained in the slices), 78 +/- 7% (urea synthesis), 88 +/- 14% (testosterone hydroxylation), 84 +/- 7% (N-deethylation of lidocaine) and 88 +/- 10% (total O-deethylation of 7-ethoxycoumarin). The ratios of testosterone metabolites did not change on cryopreservation. 4. These results show that the cryopreserved human liver slices retained the measured drug metabolism activities. Therefore, this cryopreservation method is suitable for storing liver slices to be used for comparing drug metabolism patterns, at least qualitatively, between species.     

Use of precision-cut rat liver slices for studies of xenobiotic metabolism and toxicity: comparison of the Krumdieck and Brendel tissue slicers

1. In this study we have compared freshly cut and cultured precision-cut rat liver slices produced by the Krumdieck and Brendel-Vitron tissue slicers. 2. No significant differences were observed in levels of protein, potassium, total glutathione (i.e. GSH and GSSG), reduced glutathione (GSH) and cytochrome P450 and activities of 7-ethoxyresorufin O-deethylase and 7-benzoxyresorufin O-debenzylase in freshly cut rat liver slices produced by the two tissue slicers. However, levels of oxidized glutathione (GSSG) were significantly greater in liver slices produced with the Brendel-Vitron tissue slicer. 3. Precision-cut rat liver slices produced with both tissue slicers were cultured for 0 (i.e. a 1-h preincubation), 24 and 72 h in a dynamic organ culture system in an atmosphere of either 95% 02/5% CO2 or 95% air/5% CO2. 4. Apart from small differences in glutathione levels in 0 and 24 h cultured liver slices, no significant differences were observed in the parameters measured between liver slices prepared with both tissue slicers and cultured in both gas phases. 5. With liver slices produced by both tissue slicers 50 microM sodium arsenite produced a greater induction of heat shock protein 70 levels in slices cultured for 24 h in a high oxygen than in an air atmosphere. 6. These results suggest that both tissue slicers can readily produce precision-cut liver slices for studies of xenobiotic metabolism and toxicity. However, the data suggest that for any given application of precision-cut tissue slices it is desirable to establish optimal culture conditions     

On the mechanism of hypocholesterolemic action of amphotericin B in rat

The transient hypocholesterolemia phenomenon observed in rats, injected i.v. with amphotericin B (1.5 mg/kg/day) for three weeks, was investigated by in vitro [14C] acetate incorporation into the liver cholesterol. The incorporation of acetate in liver slices of treated animals increased more than two-fold (p less than 0.02) when compared with controls.When amphotericin B was added in vitro to liver slices of control rats, the incorporation of acetate into cholesterol decreased to about 65% of that observed with the corresponding controls (p less than 0.01). The results are consistent with the hypothesis that initially amphotericin B causes inhibition of de novo cholesterol synthesis resulting in hypocholesterolemia which disappears on continued treatment possibly due to compensatory increased rate of cholesterol biosynthesis.     

Evaluation of mycobacteria growth indicator tube for recovery and drug susceptibility testing of Mycobacterium tuberculosis isolates from respiratory specimens

The new BBL mycobacteria growth indicator tube (MGIT) was evaluated for its ability to detect mycobacteria directly from patient specimens and to determine the drug susceptibility of Mycobacterium tuberculosis isolates. A total of 85 respiratory specimens were tested. Specimens were digested, concentrated, examined microscopically for acid-fast bacilli, and inoculated into MGITs and onto Lowenstein-Jensen slants by standard procedures. The tubes were incubated at 37 degrees C and were examined daily for fluorescence to 365-nm UV light. All 25 specimens smear positive for acid-fast bacilli were tested for drug susceptibility in MGITs containing 1.0 mu g of rifampin per ml, 0.1 mu g of isoniazid per ml, 2.0 mu g of streptomycin per ml, and 2.0 mu g of ofloxacin per ml. These results were compared with those obtained by testing the same M. tuberculosis isolates by the indirect proportion method at drug concentrations of 4.0 mu g of rifampin per ml, 0.2 mu g of isoniazid per ml, 2.0 mu g of ethambutol per ml. 4.0 mu g of streptomycin per ml, and 2.0 mu g of ofloxacin per ml. No significant difference in the sensitivity of detection of M. tuberculosis isolates was found between the two methods. However, the time to detection was significantly shorter in MGITs. Drug susceptibility test results for M. tuberculosis isolates by the two methods demonstrated an excellent correlation. The mean time to reporting of drug susceptibility results was 5 days for MGITs versus 16 days for Lowenstein-Jensen slants. The results of this preliminary study indicate that the MGIT system appears to have potential for routine use in mycobacteriology for both the detection and the drug susceptibility testing of M. tuberculosis isolates. However, it is important to emphasize that simple nonautomated equipment should be developed to improve the accuracy of fluorescence detection.     

Coincidence of balloon cell melanoma with balloon cells in a dermal nevus]

OBJECTIVE: To determine the effects of megestrol acetate on testosterone, dehydroepiandrosterone and PSA levels in patients with disseminated prostatic carcinoma. METHODS: 26 patients with disseminated prostatic carcinoma treated with megestrol acetate were followed for 21 months to determine its effects on testosterone, dehydroepiandrosterone and PSA levels. RESULTS/CONCLUSIONS: We observed a testicular and adrenal antiandrogenic effect. Patient clinical course improved when PSA levels dropped, although this improvement was not related with changes in androgen levels.     

Basic principles and initial results of adjuvant hormone therapy and irradiation of prostatic carcinoma

Radiotherapy is an effective treatment for localized prostate cancer. A dose response relationship has been demonstrated for both local tumor control and complications. Reducing the volume of normal tissue treated may allow dose escalation without an increase in RT induced side effects. Androgen blockade before RT could, by reducing tumor volume, increase local control, disease-free (DFS) and overall survival in patients (pts) with prostatic adenocarcinoma. A total of 79 patients with T2-T4 prostate cancer have been treated initially with LHRH agonists and cyproterone acetate followed by radical irradiation between 1988 and 1993. The first cohort of 22 patients were monitored intensively by transrectal ultrasound and computed tomography. For each patient conformal photon beam radiotherapy and conventional treatment plans were produced and dose volume histograms compared for total volume, rectal volume, and bladder volume. Overall mean reduction of prostate volume was about 50%, and radiotherapy target volume was reduced by 37%. 53 further patients without clinical evidence of regional or distant metastases were given 3 months preradiotherapeutic hormonal cytoreduction with a short course of cyproterone acetate and LHRH. PSA level fell rapidly in most patients and after 3 months treatment the median PSA level was 1 ng/ml and 83% had PSA level 10 ng/ml. At 18 months PSA levels continued to be < 2 ng/ml in 70% of the patients. Combined modality treatment with the neoadjuvant or adjuvant androgen deprivation and conformal therapy show considerable promise as novel methods to improve the therapeutic ratio. This treatment approach may be used to explore the possibility of dose escalation in prostate cancer to enhance local control, and therapeutic randomised studies are underway to test these approaches.