An evaluation of the drug interaction potential of pazopanib, an oral vascular endothelial growth factor receptor tyrosine kinase inhibitor, using a modified Cooperstown 5+1 cocktail in patients with advanced solid tumors.

Pazopanib, an oral inhibitor of vascular endothelial growth factor receptor, platelet-derived growth factor receptor, and c-kit kinases, inhibits multiple cytochrome P450 (CYP450) enzymes in vitro. This study in patients with advanced cancer evaluated the effect of pazopanib on CYP450 function by comparing the pharmacokinetics of CYP-specific probe drugs in the presence and absence of pazopanib. The probes used included midazolam (CYP3A specific), warfarin (CYP2C9 specific), omeprazole (CYP2C19 specific), caffeine (CYP1A2 specific), and dextromethorphan (CYP2D6 specific). The estimated ratios of the geometric means (90% confidence interval (CI)) for the area under the curve to the last measurable point (AUC(0-t)) for these probe drugs with/without pazopanib were as follows: midazolam, 1.35 (1.18-1.54); omeprazole, 0.81 (0.59-1.12); caffeine, 1.00 (0.77-1.30); and S-warfarin, 0.93 (0.84-1.03). The geometric least-squares (LS) mean ratio of urine dextromethorphan:dextrorphan ranged from 1.33 (0-4-h interval) to 1.64 (4-8-h interval). The data suggest that pazopanib is a weak inhibitor of CYP3A4 and CYP2D6 and has no effect on CYP1A2, CYP2C9, and CYP2C19 in patients with advanced cancer.

Extreme hypoventilation reduces ventilator-induced lung injury during ventilation with low positive end-expiratory pressure in saline-lavaged rabbits.

OBJECTIVE: To compare the degrees of ventilator-induced lung injury caused by two ventilation protocols. DESIGN: Randomized trial. SETTING: University animal laboratory. SUBJECTS: Sixteen New Zealand white rabbits. INTERVENTIONS: After five sequential saline lung lavages, eight pairs of anesthetized rabbits were allocated randomly to receive either of two ventilation protocols for 4 hrs during neuromuscular blockade. Both groups received 3 cm H2O of positive end-expiratory pressure and 100% oxygen. Control group animals received an estimated tidal volume of 12 mL/kg, an inspiratory time of 0.7 sec, and a ventilatory rate adjusted for a PaCO2 of 35 to 45 torr (4.7 to 6 kPa). Study group animals were ventilated through an intratracheal catheter, with inspiratory time of 1.5 secs, ventilatory rate of 20 breaths/min, and peak inspiratory pressure of 4 to 8 cm H2O, adjusted to maintain PaCO2 at 150 to 250 torr (20 to 33 kPa). MEASUREMENTS AND MAIN RESULTS: Arterial blood gases were measured every 30 mins. After 4 hrs, a final lung lavage was performed. Physiologic parameters, cell counts and protein concentration in the final lavage, and lung histology were compared between groups. The alveolar-arterial oxygen tension gradient was higher in the study group over the first 1.5 hrs, but the time profile showed significantly (p = .001) greater improvement in the study group. After 4 hrs, the mean alveolar-arterial oxygen tension gradient was lower in the study group (94 torr [12.5 kPa] vs. 201 torr [26.8 kPa]). The increase in neutrophil count from the initial to the final lung lavage was lower in the study group (0.27 x 10(7) cells/L vs. 2.01 x 10(7) cells/L, p = .037), as was the absolute value of the neutrophil count in the final lavage (1.33 x 10(7) cells/L vs. 3.02 x 10(7) cells/L, p = .04). The median hyaline membrane score was lower in the study group (0.5 vs. 3.0) but the difference was not statistically significant. CONCLUSION: These findings suggest that a very low tidal volume reduces ventilator-induced lung injury in saline-lavaged rabbits during ventilation at low lung volume.

Asthma control during long-term treatment with regular inhaled salbutamol and salmeterol.

BACKGROUND: The adverse effects of long term treatment of asthma with the short acting beta agonist fenoterol have been established in both epidemiological and clinical studies. A study was undertaken to investigate the efficacy and safety of long term treatment with salbutamol and salmeterol in patients with mild to moderate bronchial asthma. METHODS: In a two centre double dummy crossover study 165 patients were randomly assigned to receive salbutamol 400 micrograms q.i.d., salmeterol 50 micrograms b.i.d., or placebo via a Diskhaler. All patients used salbutamol as required for symptom relief. The study comprised a four week run in and three treatment periods of 24 weeks, each of which was followed by a four week washout. Asthma control was assessed by measuring mean morning and evening peak expiratory flow rate (PEFR), a composite daily asthma score, and minor and major exacerbation rates. Washout assessments included methacholine challenge and bronchodilator dose response tests. Analysis was by intention to treat. RESULTS: Data from 157 patients were analysed. Relative to placebo, the mean morning PEFR increased by 30 l/min (95% CI 26 to 35) for salmeterol but did not change for salbutamol. Evening PEFR increased by 25 l/min (95% CI 21 to 30) and 21 l/min (95% CI 17 to 26), respectively (p < 0.001). Salmeterol improved the asthma score compared to placebo (p < 0.001), but there was no overall difference with salbutamol. Only daytime symptoms were improved with salbutamol. The minor exacerbation rates were 0.29, 0.88, and 0.97 exacerbations/patient/year for salmeterol, salbutamol and placebo, respectively (p < 0.0001 for salmeterol). The corresponding major exacerbation rates were 0.22, 0.51 and 0.40, respectively (p < 0.03 for salmeterol). For salbutamol the asthma score deteriorated over time (p < 0.01), and the time spent in major exacerbation was significantly longer compared with placebo (12.3 days (95% CI 4.2 to 20.4) versus 8.4 days (95% CI 5.2 to 11.6), p = 0.02). There was no evidence of rebound deterioration in asthma control, lung function, or bronchial hyper-responsiveness following cessation of either active treatment, and no evidence of tolerance to salbutamol or salmeterol. CONCLUSIONS: Regular treatment with salmeterol is effective in controlling asthma symptoms and reduces minor more than major exacerbation rates. Salbutamol was associated with improved daytime symptoms but subtle deterioration in asthma control occurred over time. Salbutamol should therefore be used only as required.

Heritable genetic alterations in a xeroderma pigmentosum group G/Cockayne syndrome pedigree.

A search for genetic alterations within the XPG gene has been conducted on skin and blood cells cultured from a newly characterized xeroderma pigmentosum (XP) patient (XP20BE). This patient is the ninth known case that falls into the extremely rare XP complementation group G. Four genetic markers within the XPG gene (including two polymorphisms) demonstrated the Mendelian distribution of this gene from the parents to the patient and to an unaffected sibling. The patient (XP20BE) inherited a G to T transversion from his father in exon 1 of the XPG gene that resulted in the conversion of a glutamic acid at codon 11 to a termination codon. The patient also inherited an XP-G allele from his mother that produces an unstable or poorly expressed message. The cause of the latter defect is still uncertain. In addition to these alterations, XP20BE cDNA contained an mRNA species with a large splicing defect that encompassed a deletion from exon 1 to exon 14. This splicing defect, however, appears to be a naturally occurring low-frequency event that results from abnormal splicing that occurs between certain conserved non-consensus splicing signals within the human XPG gene.

Pressure-limited ventilation with permissive hypercapnia and minimum PEEP in saline-lavaged rabbits allows progressive improvement in oxygenation, but does not avoid ventilator-induced lung injury.

OBJECTIVE: To determine whether pressure-limited intermittent mandatory ventilation with permissive hypercapnia and positive end-expiratory pressure (PEEP) titrated to arterial oxygen tension (PaO2) prevents or reduces acute lung injury, compared to conventional ventilation, in saline-lavaged rabbits. DESIGN: Prospective randomised trial. SETTING: University animal laboratory. SUBJECTS: 18 New Zealand White rabbits. INTERVENTIONS: Following five sequential saline lung lavages, anaesthetised rabbits were randomly allocated in pairs to receive either of two ventilation protocols using intermittent mandatory ventilation. The study group had peak inspiratory pressure limited to 15 cm H2O and arterial partial pressure of carbon dioxide (PaCO2) was allowed to rise. The control group received 12 ml/kg tidal volume with rate adjusted for normocarbia. PEEP and fractional inspired oxygen (FIO2) were adjusted to maintain, PaO2 between 8 and 13.3 kPa (60 and 100 mm Hg) using a predetermined protocol. At 10 h or following death, lung lavage was repeated and lung histology evaluated. MEASUREMENTS AND MAIN RESULTS: The mean increase in lavage cell counts and protein concentration and hyaline membrane scores were not significantly different between the groups. Oxygenation progressively improved more in the study group (p = 0.01 vs control for PaO2/FIO2 ratio and alveolar-arterial oxygen tension gradient (AaDO2)). PEEP was similar and the mean airway pressure higher in the control group, suggesting that this probably resulted from less ventilator-induced injury in the study group. Four deaths occurred in the control group (three due to pneumothorax and one to hypoxaemia) and none in the study group (p = 0.08). CONCLUSIONS: This ventilatory protocol may have failed to prevent lung overdistension or it may have provided insufficient PEEP to prevent injury in this model; PEEP greater than the lower inflection point of the pressure-volume curve has been shown to prevent injury almost entirely.

The clinical course of treated and untreated Gaucher disease. A study of 45 patients.

One hundred nineteen patients with Gaucher disease were examined in the past 13 years. Of these 45 were examined 3 or more times over a time-span exceeding one year and all such patients are included in this study. Adult patients showed little progression of disease. There were few alterations in the blood counts, no increase in size of liver and spleen, and changes in skeletal lesions were largely confined to pre-existing lesions. Some children appeared to have more progressive disease, but since many of the children in this study were treated with alglucerase, it is difficult to draw conclusions about the natural progression of the disease at earlier ages. Treatment with alglucerase resulted in gradual normalization of blood counts, decrease in the size of liver and spleen, and parallel decreases in the serum angiotensin converting enzyme and chitotriosidase levels. Skeletal symptoms were decreased in all patients, and skeletal lesions showed modest improvement in patients treated for two years or more. The response of patients to low dose/high frequency (2.3 U/Kg 3 x weekly; 30 U/Kg/Mo) therapy was indistinguishable from the response observed and previously reported by others with much larger doses. Changing the dosage from 30 U/Kg/Mo to 120 U/Kg/Mo was not attended by any significant changes in response. Criteria for the selection of patients for treatment with alglucerase are proposed. We suggest that a starting dose of 15 to 30 U/Kg/month, fractionated 3 times weekly be used for all patients, regardless of severity or site of involvement, and that upward dosage adjustments be made only in such rare patients who may not respond adequately to this dose in 6 to 12 months.

Vitalethine modulates erythropoiesis and neoplasia.

Novel compounds based upon the thiol N-(carboxy)-beta-alanyl-cysteamine (vitaletheine) have strikingly potent and seemingly diverse biological activities. Concentrations of vitaletheine modulators from 1 femtograms/ml to 100 picograms/ml medium regulate RBC production from progenitors initially deprived of erythropoietin. Similarly, as little as attograms/ml concentrations of the disulfide vitalethine stimulate immunological responses of murine splenocytes toward sheep RBC in a hemolytic plaque assay. Because dosages of vitalethine as low as femtograms/kg substantially diminish tumor size and incidence and increase survival to 80% in mice inoculated with a uniformly fatal melanoma (Cloudman S-91), activities of these compounds have in vivo significance. A preliminary probe of the benzyl derivative of vitalethine in a myeloma model (NS-1) suggests efficacy (100% survival) as well. The high potencies of the vitaletheine modulators, both in cell culture and in vivo, indicate that these or similar regulatory components, if constitutively present, probably occur endogenously at vanishingly small concentrations and may be prone to deficiency resulting from metabolic imbalances, irradiation, aging, diet, pathogenic or parasitic infections, or exposure to environmental pollutants. Pathways for the biosynthesis of vitaletheine are proposed and chemical syntheses of the vitaletheine modulators are described. Possible molecular mechanisms of action, including interactions with peptidyl hormones, other endogenous effectors, and xenobiotic and pharmaceutical compounds, are explored. Indications for the treatment of other diseases are identified.

Seemingly diverse activities of beta-alethine.

beta-Alethine (beta-alanyl-cysteamine disulfide) exhibits striking biological activities in diverse systems. At an optimum of about 10 ng/ml, beta-alethine (a) adapts murine liver cells to culture (53 colonies/10(6) cells versus none in controls), (b) delays aging of human IMR-90 fetal lung fibroblasts (102 population doubling levels versus 47 in controls, producing 3 x 10(16) greater biomass), and (c) markedly stimulates antibody-producing plaque-forming cells from murine splenocytes (16,875/10(6) cells versus 55/10(6) cells in controls) or human peripheral blood leukocytes (1826/10(6) cells versus 0/10(6) cells in controls). Early interventions with beta-alethine (1 ng/kg to 100 micrograms/kg) successfully treat NS-1 myeloma in a syngeneic murine tumor model (NS-1 myeloma). Although there are indications in this model that beta-alethine is also effective when intervention is late, beta-alethine is ineffective in an allogeneic murine melanoma model (Cloudman S-91 melanoma). It is inferred that beta-alethine enhances cellular phenotypic expression, function, and vitality in diverse biological systems and may treat certain types of neoplasia. Because atomic spacings between the amide moieties in beta-alethine are the same as in the differentiating agent hexamethylene-bis-acetamide and because the radioprotectors WR 2721 and WR 1065 lack only the carbonyl oxygen of the thiol form (beta-aletheine), biological activities already reported for these compounds are compared with those presented herein for beta-alethine. Although these comparisons have not been made in the same systems, the tentative conclusion is that the amide moieties of beta-alethine may be critical to its potency and lack of obvious toxicity in cell culture and animal models.

Cell surface oligosaccharide modulation during differentiation: VI. The effect of biomodulation on the senescent and neoplastic cell phenotype.

These investigations test the hypothesis developed previously, that there are biomolecules which control and integrate cellular differentiation. Our specific interest in cellular differentiation lies in the area of what we refer to as basal or primitive cellular differentiation mechanisms. These mechanisms are common to all cells, and are required for simple recognition and growth regulation. We have investigated two models, the IMR-90 human fetal lung fibroblast model as a representative of normal growth control, and the CG model, canine glioma cells, a transplantable growth transformed cell line. These two models represent normal, and aberrant cellular differentiation control. In previous studies we have shown that the arrangement of the cell surface oligosaccharide structure on these cell types are predictive of phenotypic transition. We have developed, and partially characterized a series of BIOMODULATORS (BM) which delay the onset of display of neoplastic cells. Three classes of BIOMODULATOR have been explored; (1) a large molecular weight natural product (25-35 kDa), PokeWeed Mitogen (PWM); (2) a small molecular weight natural product (500 Da) Cellular Activator and Differentiator (CAD) and a number of natural and synthetic analogs; and (3) an indolizidine alkaloid natural product, Swainsonine (Sw) which has a known cellular target (oligosaccharide biosynthesis). Preliminary data is presented which structurally links some of these BIOMODULATORS in terms of their effective stereochemistry. These BIOMODULATORS, when used before PDL 38, prevent the cell surface oligosaccharide display changes typical of morphological senescence and delay their onset to PDL 100 or more. These BIOMODULATORS also appear to have regulatory effects on the neoplastic cell models. This re-regulation results in increases in generation time and an increase in the ability of these cells to be recognized by cytotoxic lymphocytes. Proton NMR linewidth measurements of the fraction of 'bound' water associated with the cellular surface of treated and untreated cell populations showed induced physical changes in the cell surface related to the use of the BIOMODULATOR and correlated to the oligosaccharide display changes. These data were interpreted as indicating an increase in the organizational level of these cells. The data for normal and neoplastic cell populations are compared and contrasted in an effort to form the basis for an analytical approach to the control and integration of differentiation mechanisms.