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ABSTRACTThe pharmacokinetic profiles, safety, and efficacies of different dosing schedules of posaconazole oral suspension in patients with possible, probable, and proven refractory invasive fungal infection (rIFI) or febrile neutropenia (FN) were evaluated in a multicenter, open-label, parallel-group study. Sixty-six patients with FN and 32 patients with rIFI were randomly assigned to one of three posaconazole regimens: 200 mg four times a day (q.i.d.) for nine doses, followed by 400 mg twice a day (b.i.d.); 400 mg q.i.d. for nine doses, followed by 600 mg b.i.d.; or 800 mg b.i.d. for five doses, followed by 800 mg once a day (q.d.). Therapy was continued for up to 6 months in patients with rIFI or until neutrophil recovery occurred in patients with FN. The 400-mg-b.i.d. dose provided the highest overall mean exposure, with 135% (P= 0.0004) and 182% (P< 0.0001) greater exposure than the 600-mg-b.i.d. and 800-mg-q.d. doses, respectively. However, exposure in allogeneic bone marrow transplant (BMT) recipients (n= 12) was 52% lower than in non-BMT patients. Treatment-related adverse events (occurring in 24% of patients) were mostly gastrointestinal in nature. Twenty-four percent of patients had adverse events leading to premature discontinuation (none were treatment related). In efficacy-evaluable patients, successful clinical response was observed in 43% with rIFI (56% of patients receiving 400 mg b.i.d., 17% receiving 600 mg b.i.d., and 50% receiving 800 mg q.d.) and 77% with FN (74% receiving 400 mg b.i.d., 78% receiving 600 mg b.i.d., and 81% receiving 800 mg q.d.). Posaconazole is well tolerated and absorbed. Divided doses of 800 mg (400 mg b.i.d.) provide the greatest posaconazole exposure.

ABSTRACTZygomycosis, an infection that is associated with significant morbidity and mortality, is becoming common in immunocompromised patients. Posaconazole is a new extended-spectrum azole antifungal that has demonstrated in vitro and in vivo activity against zygomycetes. This report provides the results from the first 24 patients with active zygomycosis who were enrolled in two open-label, nonrandomized, multicentered compassionate trials that evaluated oral posaconazole as salvage therapy for invasive fungal infections. Posaconazole was usually given as an oral suspension of 200 mg four times a day or 400 mg twice a day. Eleven (46%) of the infections were rhinocerebral. Duration of posaconazole therapy ranged from 8 to 1,004 days (mean, 292 days; median, 182 days). Rates of successful treatment (complete cure and partial response) were 79% in 19 subjects with zygomycosis refractory to standard therapy and 80% in 5 subjects with intolerance to standard therapy. Overall, 19 of 24 subjects (79%) survived infection. Survival was also associated with surgical resection of affected tissue and stabilization or improvement of the subjects' underlying illnesses. Failures either had worsening of underlying illnesses or requested all therapy withdrawn; none of the failures received more than 31 days of posaconazole. Posaconazole oral solution was well tolerated and was discontinued in only one subject due to a drug rash. Posaconazole appears promising as an oral therapy for zygomycosis in patients who receive required surgery and control their underlying illness.

We retrospectively compared 81 temporal artery biopsy specimens demonstrating perivascular inflammation without evidence of temporal arteritis and 76 specimens demonstrating no inflammation. Patients with perivascular inflammation included 43 women (mean age, 71.2 years). Nineteen patients met the 1990 American College of Rheumatology (ACR) criteria for the diagnosis of temporal arteritis. All patients demonstrated chronic perivascular inflammation consisting primarily of lymphocytes. Granulomas were noted in 4 specimens. Internal elastic lamina disruption, intimal fibroplasia, and dystrophic calcification were noted in 86 arteries examined. Fibrosis or scarring of the vessel walls was observed in 10 specimens. Corticosteroid therapy was beneficial to 33 of 56 patients. In patients with no evidence of inflammation (50 women; mean age, 66.6 years), 21 met ACR criteria for temporal arteritis. Histologically, disruption of the elastic lamina was noted in 75 of 81 arteries biopsied, intimal fibroplasia in 66, microcalcifications in 5, and fibrosis or scarring in 5. In this group, 47 patients received corticosteroid therapy; clinical improvement was noted in 28. Patients with chronic perivascular inflammation but no arteritis seem no more likely to have temporal arteritis on clinical grounds than similar patients without inflammation on biopsy.

Our working hypothesis states that DNA damage is a critical step in toxic cell death. The DNA hypothesis was tested in cultured mouse hepatocytes by examining whether inhibitors of DNA repair would increase dimethylnitrosamine toxicity and DNA damage in parallel. Inhibitors were chosen for selectivity toward DNA polymerase alpha (aphidicolin, myricetin), DNA ligase (ethidium bromide), or multiple repair enzymes (ara-C, doxorubicin). Dimethylnitrosamine caused concentration-dependent DNA damage at 6 hr and cell death at 24 hr (35% ALT release vs. 8.8% in control cultured hepatocytes). Each repair inhibitor increased dimethylnitrosamine-induced DNA damage and toxic cell death in parallel. Doxorubicin maximally elevated DNA fragmentation and toxicity (57% ALT release). Repair inhibitors alone failed to damage DNA or cause cell death in this model system. These data support the hypothesis that DNA damage is an early causal event in toxic cell death caused by alkylating hepatotoxicants.

Two areas of the Weddell Sea, one in the south and one in the west, were chosen for a preliminary investigation of sea-ice motion tracking from ERSt Synthetic Aperture Radar (SAR) images during the Austral summer. Only a small number of images were processed, so a manual tracking method was used. In the 3-day period between SAR images the atmosphere warmed near the surface, which led to significant changes in radar backscatter from, and thus in contrast between, ice floes and the areas between them. It was therefore not always possible to track features from one image to the next. The tracked features were clearly identified in images which were sub-sampled at onesixteenth of the full resolution available. In the southern Weddell Sea images, many large floes were present which allowed a quite detailed pattern of the surface water circulation to be mapped as the ice motion was predominantly forced by the ocean currents during a period of low surface wind speeds. The observed circulation pattern agreed well with previous observations from hydrographic surveys in this area north of the Filchner Ice Shelf. In the western Weddell Sea images good tracers were hard to find, but it was still possible to detect the edge of the western boundary current of the Weddell Gyre. Continuous monitoring of sea-ice motion in these two areas using SAR imagery could be a useful means of detecting changes in surface water flow which may be linked to the rate of formation of Antarctic bottom water.

Obese humans suffer from excessive organ dysfunction, altered drug pharmacokinetics and may be at increased risk of various drug toxicities. A recent report shows that gentamicin nephrotoxicity in critically ill patients is more frequent and more severe than usual in individuals who are substantially overweight. The present study utilizes an overfed rat model to examine the influence of obesity on the nephrotoxic potential of gentamicin. After 52 weeks on an energy-dense diet, obese animals outweighed pellet controls by more than 80% (913 +/- 86 vs. 507 +/- 52 g; X +/- S.D., n = 7). When animals were treated twice daily for 6 days with 30 mg/kg of gentamicin i.p. based on total body mass, obese rats sustained more cortical necrosis than control (median score 3+ vs. 0), higher serum creatinine (4.36 +/- 2.72 vs. 0.71 +/- 0.17) and greater creatinine adjusted N-acetyl hexosaminidase excretion. The impact of obesity on intrinsic susceptibility to gentamicin nephrotoxicity was assessed by dosing animals for 5 days to ideal body mass plus 40% of excess body mass, the current clinical practice for achieving normal gentamicin concentrations in obese patients. Obese rats again sustained more frequent and severe cortical necrosis (2+ vs. 0) and excreted more N-acetyl hexosaminidase than control animals. Urine pH averaged 1.7 U below normal in obese animals, but restoration to normal values by 2 weeks on the pellet diet did not diminish the toxicity increase. Results from the overfed rat closely resemble the recent clinical observation that obese patients sustain more frequent and severe kidney damage from aminoglycoside antibiotics.(ABSTRACT TRUNCATED AT 250 WORDS)

Several hepatotoxic agents damage Ca++ regulation and produce toxic cell death in a manner consistent with a cause-and-effect relationship; however, vital targets of Ca++ remain unidentified. Recent results show that DNA may be the chief Ca++ target during apoptosis, a form of cell death considered distinct from toxic cell death or necrosis. The present studies explored whether nuclear Ca++ regulation is lost before dimethylnitrosamine-induced necrosis, whether DNA is attacked by Ca(++)-dependent endonucleases and whether inhibitors of Ca(++)-endonuclease activity and the DNA repair enzyme poly(ADP-ribose)polymerase affect necrosis. Adult male ICR mice received 100 mg/kg of dimethylnitrosamine i.p. By 2 to 4 hr, total nuclear Ca++ reached 150 to 180% of control and DNA fragmentation was 140 to 170% of control. Electrophoresis of DNA revealed a sharp decline in genomic DNA with the appearance of DNA fragments in a ladder-like pattern. Ca++ elevation and DNA fragmentation preceded toxic cell death by 4 hr or more and reached peak values at 18 to 24 hr, coincident with maximal alanine aminotransferase leakage. Aurintricarboxylic acid, a Ca(++)-endonuclease inhibitor, reduced toxicity 67%. 3-Aminobenzamide, nicotinamide adenine dinucleotide and theophylline, inhibitors of poly(ADP-ribose)polymerase-mediated DNA repair, potentiated liver damage 2-fold. These results support the hypothesis that DNA fragmentation plays a contributing role in toxic cell death induced by dimethylnitrosamine. Furthermore, the findings suggest that new opportunities may exist to moderate the toxicity of alkylating hepatotoxins by altering DNA regulation.

In Britain, the specialty of palliative medicine continues to develop, encouraging the referral of patients early in the palliative phase of their illness. This had led to an increased number of patients receiving palliative chemotherapy and hospice care concurrently, posing special problems to the professionals involved. In this retrospective study, 52 patients were identified who received chemotherapy and hospice care simultaneously. Case notes were reviewed to reveal problems arising from sharing the duty of care. The poor quality of communication between professionals, perhaps reflecting a limited understanding of the various roles in patient care, we found to cause significant difficulties. The duration and discontinuation of cytotoxic therapy seems to be a particularly difficult matter. Hospice admission often signalled the end of this treatment. In a third of the patients, no decision was taken to stop chemotherapy despite the last dose being an average of just 1 week before death. The value of chemotherapy for patients who are too ill to return home is questioned. Seven patients were diagnosed as suffering from chemotherapy-induced sepsis and neutropenia either by hospice inpatient or home care teams, and were admitted to their acute centres accordingly. Most patients who died during the study period received terminal care in the hospice. Suggestions are made on improving professional education and communication, including the use of a 'chemotherapy card'.

The revelation that many covalent binding estimates are falsely low due to flawed normalization discloses that protection by N-acetyl-L-cysteine against acetaminophen hepatotoxicity is accompanied routinely by a 50 to 80% decline in arylation. Elevated glutathione may be responsible for inhibiting covalent binding but above-normal concentrations have never been demonstrated in vivo after N-acetyl-L-cysteine treatment or separated adequately from other possible hepatoprotective actions including direct reduction of the toxic acetaminophen metabolite by the antidote. This led us to compare the conventional L-isomer of the antidote to its nonphysiologic stereoisomer, N-acetyl-D-cysteine, because the latter should be capable of reducing the toxic metabolite but not of stimulating glutathione biosynthesis. Oral coadministration of N-acetyl-D-cysteine (1200 mg/kg), however, failed in preventing the elevation of serum alanine aminotransferase activity, in decreasing hepatocellular necrosis, in interdicting covalent binding of the toxic metabolite to hepatocellular proteins and in preventing the depletion of liver glutathione caused by 500 mg/kg of acetaminophen. N-acetyl-L-cysteine succeeded in decreasing these measures of acetaminophen hepatotoxicity while driving liver glutathione concentrations 2-3 fold above control values. The L-isomer also increased urinary excretion of glutathione-derived acetaminophen metabolites whereas the D-isomer increased only acetaminophen sulfate excretion and reversed the customary predominance of acetaminophen cysteine over the mercapturic acid conjugate. Liver uptake of N-acetyl-D-cysteine was reflected in organ concentrations 7-fold higher than noted for the L-isomer.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytochrome P450IIE1 (IIE1) is a microsomal xenobiotic-activating enzyme that is inducible not only by various chemical agents but also by fasting and diabetes. Using a rat model that mimics human obesity, we have found that hepatic IIE1 levels are also increased by this common clinical disorder. Liver microsomes from rats made obese by feeding with an energy-dense diet displayed elevated aggregate P450 content (+28%) and enhanced catalytic activities associated with IIE1, including low-Km N-nitrosodimethylamine demethylation (+66%), aniline hydroxylation (+52%), p-nitrophenol hydroxylation (+170%), and acetaminophen-cysteine conjugate formation (+28%). In contrast, obesity had no significant effect on cytochrome b5 content, P450 reductase activity, benzphetamine demethylation, or erythromycin demethylation, with the latter two reactions being linked with rat IIC11 and IIIA1, respectively. The enhancement of IIE1-dependent drug-metabolizing activities noted in liver microsomes from obese rats was paralleled by a similar increase (111%) in hepatic IIE1 protein content in these animals, as assessed on immunoblots developed with anti-hamster IIE1 IgG. Anti-IIE1-inhibitable rates of microsomal p-nitrophenol metabolism, a reaction highly correlated with IIE1 content (r = 0.88, p less than 0.01), were over 3-fold higher in obese rats than in nonobese controls, providing additional evidence for the obesity-related increase of hepatic IIE1. The induction of IIE1 by the pathophysiological condition of obesity may provide a biochemical basis for the increased incidence of occult liver disease and certain cancers noted in obese individuals.

The overfed rat served as the animal model for examining the influence of obesity on the hepatotoxic and nephrotoxic potential of metabolically activated drugs, and acetaminophen served as the prototype drug. Weanling Sprague-Dawley rats were given a standard pellet diet or semisynthetic, energy-dense diet designed to produce obesity. After 24 weeks, when overfed rats outweighed controls by more than 50%, animals received 710 mg/kg of acetaminophen i.p., based on total body weight. Toxicity evaluation included biochemical signs of organ injury over the first 24 hr and histopathologic changes in tissue morphology at 48 hr. Both enzyme release (alanine aminotransferase into plasma, alkaline phosphatase into urine) and frank cellular necrosis in liver and kidney of obese rats greatly exceeded that in pellet-fed controls. Contributing to the potentiation of injury were higher peak plasma concentrations of acetaminophen in obese animals resulting from total body weight dosing. However, liver and kidney injury and mortality remained elevated when peak plasma concentrations were matched by fat-free mass dosing, indicating that increased toxicity also was related to obesity. Incomplete recovery of acetaminophen and metabolites from obese animals (45 vs. 71% in control rats) caused by a functional renal impairment made it impossible to determine the metabolic fate of acetaminophen in overfed animals from the analysis of urine collections. Drug products measured in urine were summed with amounts remaining in carcass at sacrifice, computed as terminal plasma concentrations times respective distribution volumes. These results showed obese rats to form more glucuronide and less sulfate conjugate than did pellet-fed controls, coinciding with clinical evidence for enhanced glucuronidation in obese humans.(ABSTRACT TRUNCATED AT 250 WORDS)

N-acetylcysteine is the drug of choice for the treatment of acetaminophen poisoning, yet the mechanism of protection in vivo is unknown. Prevention of liver injury could result from decreased production of the toxic intermediate(s), from increased capacity to detoxify the toxic intermediate(s) or from increased ability of the tissue to withstand or even repair the molecular damage caused by the toxic species. Treatment of mice with N-acetylcysteine (1200 mg/kg p.o.) was found to prevent the hepatic damage caused by 1000 mg/kg p.o. of acetaminophen. Possible mechanisms for this hepatoprotective effect were examined by measurement at different time points of acetaminophen and its metabolites in plasma, urine, bile and whole-body homogenates and by evaluation of the changes in these parameters caused by treatment with N-acetylcysteine. A high-pressure liquid chromatographic method was developed to measure the majority urinary metabolites of acetaminophen and was validated by desorption chemical ionization mass spectral analysis of individual metabolites. Minimal differences in the concentration of unchanged acetaminophen and metabolites in whole-body homogenates at 4, 6 and 24 hr postdose were noted for N-acetylcysteine-treated vs. vehicle-treated mice. These results are incompatible with a decreased formation of the toxic species secondary to delayed acetaminophen absorption from the gastrointestinal tract or with an increased clearance of acetaminophen via nontoxic pathways such as sulfation as plausible mechanisms for the observed hepatoprotection.(ABSTRACT TRUNCATED AT 250 WORDS)

Experiments were designed to test whether the protective effect of N-acetylcysteine against acetaminophen hepatotoxicity precedes arylation of tissue or whether protection occurs after arylation of tissue. Investigation of potential postarylation actions showed that N-acetylcysteine was unable to attenuate the liver necrosis caused by acetaminophen or several other hepatotoxins that act through chemically reactive metabolites. Furthermore, varying the time and route of N-acetylcysteine treatment indicated that the late protection against acetaminophen mortality probably was a consequence of pharmacokinetic factors rather than postarylation intervention in the process of cell death. The antidote was found to inhibit covalent binding of acetaminophen by about 70% when N-acetylcysteine protected against liver necrosis. Treatment regimens that had no effect upon covalent binding also had no effect on acetaminophen hepatotoxicity. Previous failures to detect this relationship apparently occurred because of a failure to consider biological events important in the pathophysiology of acetaminophen-induced necrosis, particularly the marked intrahepatic hemorrhage and vascular congestion with liver engorgement by protein and fluid. These results support the hypothesis that sulfhydryl nucleophiles such as N-acetylcysteine act primarily through prearylation mechanisms to decrease the amount of reactive metabolite available for initiation of hepatic injury.