Aliskiren reduces vascular pathology in diabetic retinopathy and oxygen-induced retinopathy in the transgenic (mRen-2)27 rat.

AIM/HYPOTHESIS: We examined whether the renin inhibitor, aliskiren, provides similar or greater protection than ACE inhibition from non-proliferative diabetic retinopathy and from the proliferative neoangiogenesis of oxygen-induced retinopathy. METHODS: Transgenic (mRen-2)27 rats, which overexpress mouse renin and angiotensin in extra-renal tissues, were studied. For diabetic studies, non-diabetic, diabetic (streptozotocin, 55 mg/kg), diabetic + aliskiren (10 mg kg(-1) day(-1), pump), or diabetic + lisinopril (10 mg kg(-1) day(-1), drinking water) rats were evaluated over 16 weeks. For oxygen-induced retinopathy studies, rats were exposed to 80% oxygen (22 h/day) from postnatal days 0 to 11, and then room air from postnatal days 12 to 18. Aliskiren (10 or 30 mg kg(-1) day(-1), pump) or lisinopril (10 mg kg(-1) day(-1), drinking water) was administered during retinopathy development between postnatal days 12 and 18. RESULTS: Systolic BP in diabetic (mRen-2)27 rats was reduced with 10 mg kg(-1) day(-1) aliskiren, but only lisinopril normalised systolic blood pressure. In diabetic (mRen-2)27 rats, 10 mg kg(-1) day(-1) aliskiren and lisinopril reduced retinal acellular capillaries and leucostasis to non-diabetic levels. In oxygen-induced retinopathy, neoangiogenesis and retinal inflammation (leucostasis, ED-1 immunolabelling) were partially reduced by 10 mg kg(-1) day(-1) aliskiren and normalised by 30 mg kg(-1) day(-1) aliskiren, whereas lisinopril normalised neoangiogenesis and reduced leucostasis and ED-1 immunolabelling. Aliskiren and lisinopril normalised retinal vascular endothelial growth factor expression; however, only aliskiren reduced intercellular adhesion molecule-1 to control levels. CONCLUSIONS/INTERPRETATION: Aliskiren provided similar or greater retinal protection than ACE inhibition and may be a potential treatment for diabetic retinopathy.

Effect of oxidation and mutation on the conformational dynamics and fibril assembly of amyloidogenic peptides derived from apolipoprotein C-II.

The oxidation of methionine residues in proteins can inhibit the self-assembly of proteins to form amyloid fibrils. For human apolipoprotein (apo) C-II the oxidation of methionine at position 60 inhibits fibril formation by the mature protein and by the core peptides apoC-II(56-76) and apoC-II(60-70). To investigate the molecular nature of these effects, we carried out fully solvated, all-atom molecular dynamics simulations of the structural changes in apoC-II(56-76) associated with substitutions of oxidized methionine (Met ox) at position 60. The results with apoC-II(56-76) (Met ox) showed less flexibility in structure, leading to a perturbation of the hydrophobic core. Valine substitution at position 60 showed an increased tendency to explore a wide range of conformational space, whereas the behavior of the Gln substitution mutant was similar to the wild-type peptide. These simulations are consistent with kinetic measurements which showed that a Met60Gln substitution within apoC-II(56-76) had little effect on the rate of fibril formation whereas substitution of Met ox or Val at position 60 lead to significant inhibition of peptide fibril formation. The effects of amino acid modification and substitutions on the kinetics of peptide fibril formation differ from the effects observed with full-length apoC-II inferring that additional mechanisms are involved in fibril formation by mature apoC-II.

Phase I clinical and pharmacokinetic trial of irofulven.

PURPOSE: To evaluate the clinical tolerability of a new schedule of 6-hydroxymethylacylfulvene (irofulven, MGI 114, HMAF, NSC 683863), a semisynthetic sesquiterpene derived from the cytotoxic mushroom metabolite illudin S. Irofulven has been shown to induce DNA damage and apoptosis in vitro and has shown activity in a number of human tumor xenograft models. A number of drug-resistant cell lines including those that express the mdr phenotype, retain sensitivity to irofulven. METHODS: We conducted a phase I trial of irofulven given as an intravenous infusion (30 min) on a daily x5 schedule every 28 days. A total of ten patients were enrolled and treated at three dose levels, 6, 8, and 11 mg/m2 per day. RESULTS: Irofulven reached steady-state concentrations during the 30-min infusions with biexponential kinetics. Irofulven disappeared rapidly from plasma and was detectable for only 15-30 min after the end of the infusion. The mean half-life was 4.91 min and the mean clearance was 4.57 l/mm per m2. Peak plasma concentrations of irofulven of approximately 300 ng/ml were achieved. Pharmacokinetic parameters did not differ significantly from day 1 to day 5. Irofulven was highly emetogenic. Other prominent toxicities included anorexia and fatigue. One case of delayed-onset metabolic acidosis possibly secondary to irofulven was observed. No other renal or metabolic toxicity was encountered. One patient experienced a late-onset grade 3 extravasation skin injury thought to be secondary to extravasation of irofulven. Minimal marrow suppression was observed. No objective tumor responses were observed. CONCLUSIONS: The recommended phase II dose on this schedule is 6 mg/m2.

Phase I clinical and pharmacokinetic study of perillyl alcohol administered four times a day.

We conducted a phase I dose-escalation trial of perillyl alcohol (POH; NSC 641066) given p.o. on a continuous four times a day basis to characterize the maximum tolerated dose, toxicities, pharmacokinetic profile, and antitumor activity. Sixteen evaluable patients with advanced refractory malignancies were treated at the following doses: level 1 (L1), 800 mg/m2/dose; L2, 1200 mg/m2/dose; L3, 1600 mg/m2/dose. POH was formulated in soft gelatin capsules containing 250 mg of POH and 250 mg of soybean oil. The predominant toxicities seen were gastrointestinal (nausea, vomiting, satiety, and eructation), which were dose limiting. There appeared to be a dose-dependent increase in levels of the two main metabolites, perillic acid and dihydroperillic acid. No significant differences were seen whether the drug was taken with or without food. There was a trend toward decreasing metabolite levels on day 29 compared with days 1 and 2. Peak metabolite levels were seen 1-3 h post ingestion. Metabolite half-lives were approximately 2 h. Approximately 9% of the total dose was recovered in the urine in the first 24 h, the majority as perillic acid. Evidence of antitumor activity was seen in a patient with metastatic colorectal cancer who has an ongoing near-complete response of > 2 years duration. Several other patients were on study for > or = 6 months with stable disease. The maximum tolerated dose of POH given continuously four times a day was 1200 mg/m2/dose. Gastrointestinal toxicity was dose limiting, although significant interpatient variability in drug tolerance was seen.

A phase I study of gemcitabine, 5-fluorouracil and leucovorin in patients with advanced, recurrent, and/or metastatic solid tumors.

INTRODUCTION: This was a dose escalation phase I trial designed to establish the MTD (maximum tolerated dose) and toxicity profile of the combination of gemcitabine, leucovorin and 5-fluorouracil (5-FU). METHODS: Standard eligibility criteria were required for patients with advanced malignancy to enroll. Gemcitabine was escalated from an initial dose of 800 mg/m2. Gemcitabine was administered prior to leucovorin (25 mg/m2) followed by bolus 5-FU (600 mg/m2) every week for 3 weeks followed by 1 week of rest. RESULTS: Of 21 patients enrolled, 20 were eligible for MTD determination. Patients received a median of three 4-week cycles of chemotherapy (range: 1 to 8 cycles). Toxicity was predominantly hematologic or gastroenterologic. Four dose levels were studied. At a gemcitabine dose of 1,500 mg/m2 systemic symptoms of fatigue accompanied hematologic toxicity and patients refused further therapy. At 1,250 mg/m2, full dose intensity was not delivered during the first cycle in 7 of 8 patients treated. Therefore, 1,000 mg/m2 was established as the recommended phase II dose for gemcitabine in this study. Antitumor activity was seen at all dose levels. CONCLUSIONS: The combination of gemcitabine, leucovorin and 5-FU was tolerable at full doses of all 3 drugs with an expected toxicity profile. Recommended phase II dose for gemcitabine was 1,000 mg/m2. Initial evidence of clinical activity was seen in a variety of tumor types.