Comparison of two population pharmacokinetic programs, NONMEM and P-PHARM, for tacrolimus

Objectives: To compare the population modelling programs NONMEM and P-PHARM during investigation of the pharmacokinetics of tacrolimus in paediatric liver-transplant recipients. Methods: Population pharmacokinetic analysis was performed using NONMEM and P-PHARM on retrospective data from 35 paediatric liver-transplant patients receiving tacrolimus therapy. The same data were presented to both programs. Maximum likelihood estimates were sought for apparent clearance (CL/F) and apparent volume of distribution (V/F). Covariates screened for influence on these parameters were weight, age, gender, post-operative day, days of tacrolimus therapy, transplant type, biliary reconstructive procedure, liver function tests, creatinine clearance, haematocrit, corticosteroid dose, and potential interacting drugs. Results: A satisfactory model was developed in both programs with a single categorical covariate - transplant type - providing stable parameter estimates and small, normally distributed (weighted) residuals. In NONMEM, the continuous covariates - age and liver function tests - improved modelling further. Mean parameter estimates were CL/F (whole liver) = 16.3 1/h, CL/F (cut-down liver) = 8.5 1/h and V/F = 565 1 in NONMEM, and CL/F = 8.3 1/h and V/F = 155 1 in P-PHARM. Individual Bayesian parameter estimates were CL/F (whole liver) = 17.9 +/- 8.8 1/h, CL/F (cutdown liver) = 11.6 +/- 18.8 1/h and V/F = 712 792 1 in NONMEM, and CL/F (whole liver) = 12.8 +/- 3.5 1/h, CL/F (cut-down liver) = 8.2 +/- 3.4 1/h and V/F = 221 1641 in P-PHARM. Marked interindividual kinetic variability (38-108%) and residual random error (approximately 3 ng/ml) were observed. P-PHARM was more user friendly and readily provided informative graphical presentation of results. NONMEM allowed a wider choice of errors for statistical modelling and coped better with complex covariate data sets. Conclusion: Results from parametric modelling programs can vary due to different algorithms employed to estimate parameters, alternative methods of covariate analysis and variations and limitations in the software itself.

Exposure to automotive pollution increases plasma susceptibility to oxidation

Low-density lipoprotein oxidation is implicated in the development of atherosclerosis. Plasma susceptibility to oxidation may be used as a marker of low-density lipoprotein oxidation and thus predict atherosclerotic risk. In this study the authors investigated the relationship between plasma susceptibility to oxidation and exposure to automotive pollution in a group of automobile mechanics (n = 16) exposed to high levels of automotive pollution, vs. matched controls (n = 13). The authors induced plasma oxidation by a free radical initiator and they determined susceptibility to oxidation by (1) change in absorbance at 234 nm, (2) lag time to conjugated diene formation, and (3) linear slope of the oxidation curve. Mechanics had significantly higher values (mean standard error) for change in absorbance (1.60 +/- 0.05 vs. 1.36 +/- 0.05; p < .002), and slope (1.6 x 10(-3) +/- 0.1 x 10(-3) vs. 1.3 x 10(-3) +/- 0.1 x 10(-3); p < .001), compared with controls. These results indicate that regular exposure to automotive pollutants increases plasma susceptibility to oxidation and may, in the long term, increase the risk of developing atherosclerosis.

Inhibition of rat platelet aggregation by the diazeniumdiolate nitric oxide donor MAHMA NONOate

1 Inhibition of rat platelet aggregation by the nitric oxide (NO) donor MAHMA NONOate (Z-1-{N-methyl-N-[6-(N-methylammoniohexyl)amino]}diazen-l-ium-1,2-diolate) was investigated. The aims were to compare its anti-aggregatory effect with vasorelaxation, to determine the effects of the soluble guanylate cyclase inhibitor, ODQ (1H-[1,2,4]oxadiazolo[4,3-ajquinoxalin-1-one), and to investigate the possible role of activation of sarco-encloplasmic reticulum calcium-ATPase (SERCA), independent of soluble guanylate cyclase, using thapsigargin. 2 MAHMA NONOate concentration-dependently inhibited sub-maximal aggregation responses to collagen (2 - 10 mug ml(-1)) and adenosine diphosphate (ADP; 2 mum) in platelet rich plasma. It was (i) more effective at inhibiting aggregation induced by collagen than by ADP, and (ii) less potent at inhibiting platelet aggregation than relaxing rat pulmonary artery. 3 ODQ (10 mum) caused only a small shift (approximately half a log unit) in the concentration-response curve to MAHMA NONOate irrespective of the aggregating agent. 4 The NO-independent activator of soluble guanylate cyclase, YC-1 (3-(5'-hydroxymethyl-2'-furyl)-1-benzy] indazole; 1 - 100 mum), did not inhibit aggregation. The cGMP analogue, 8-pCPT-cGMP (8-(4-chlorophenylthio)guanosine 3'5' cyclic monophosphate; 0.1 - 1 mm), caused minimal inhibition. 5 On collagen-aggregated platelets responses to MAHMA NONOate (ODQ 10 PM present) were abolished by thapsigargin (200 nm). On ADP-aggregated platelets thapsigargin caused partial inhibition. 6 Results with S-nitrosoglutathione (GSNO) resembled those with MAHMA NONOate. Glyceryl trinitrate and sodium nitroprusside were poor inhibitors of aggregation. 7 Thus inhibition of rat platelet aggregation by MAHMA NONOate (like GSNO) is largely ODQ-resistant and, by implication, independent of soluble guanylate cyclase. A likely mechanism of inhibition is activation of SERCA.

Genes induced by growth hormone in a model of adipogenic differentiation

A substantial number of GH regulated genes have been reported in mature hepatocytes. but genes involved in GH-initiated cell differentiation have not yet been identified. Here we have studied a, ell-characterised model of GH-dependent differentiation, adipogenesis of 3T3-F442A preadipocytes, to identify genes rapidly induced by GH. Using the suppression subtractive hybridisation technique, we have identified eight genes induced within 60 min of GH treatment, and verified these by northern analysis. Six were identifiable as Stat 2. Stat 3, thrombospondin-1. oncostatin M receptor beta chain. a DEAD box RNA helicase. and muscleblind. a developmental transcription factor. Bioinformatic approaches assigned one of the two remaining unknown genes as a novel 436 residue serine,threonine kinase. As each of the identified genes hake important developmental roles. they may be important in initiating GH-induced adipogenesis. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

Coal dust exposures in the longwall mines of New South Wales, Australia: a respiratory risk assessment

This paper presents an analysis of personal respirable coal dust measurements recorded by the Joint Coal Board in the underground longwall mines of New South Wales from 1985 to 1999. A description of the longwall mining process is given. In the study, 11 829 measurements from 33 mines were analysed and the results given for each occupation, for seven occupational groups, for individual de-identified mines and for each year of study. The mean respirable coal dust concentration for all jobs was 1.51 mg/m(3) (SD 1.08 mg/m(3)). Only 6.9% of the measurements exceeded the Australian exposure standard of 3 mg/m(3). Published exposure-response relationships were used to predict the prevalence of progressive massive fibrosis and the mean loss of FEV1, after a working lifetime (40 years) of exposure to the mean observed concentration of 1.5 mg/m(3). Prevalences of 1.3 and 2.9% were predicted, based on data from the UK and the USA, respectively. The mean loss of FEV1 was estimated to be 73.7 ml.

Hemodynamic and ventilatory effects of manual respiratory physiotherapy techniques of chest clapping, vibration, and shaking in an animal model

Chest clapping, vibration, and shaking were studied in 10 physiotherapists who applied these techniques on an anesthetized animal model. Hemodynamic variables (such as heart rate, blood pressure, pulmonary artery pressure, and right atrial pressure) were measured during the application of these techniques to verify claims of adverse events. In addition, expired tidal volume and peak expiratory flow rate were measured to ascertain effects of these techniques. Physiotherapists in this study applied chest clapping at a rate of 6.2 +/- 0.9 Hz, vibration at 10.5 +/- 2.3 Hz, and shaking at 6.2 +/- 2.3 Hz. With the use of these rates, esophageal pressure swings of 8.8 +/- 5.0, 0.7 +/- 0.3, and 1.4 +/- 0.7 mmHg resulted from clapping, vibration, and shaking respectively. Variability in rates and forces generated by these techniques was 80% of variance in shaking force (P = 0.003). Application of these techniques by physiotherapists was found to have no significant effects on hemodynamic and most ventilatory variables in this study. From this study, we conclude that chest clapping, vibration, and shaking 1) can be consistently performed by physiotherapists; 2) are significantly related to physiotherapists' characteristics, particularly clinical experience; and 3) caused no significant hemodynamic effects.

Predicting the HER2 status of breast cancer from basic histopathology data: an analysis of 1500 breast cancers as part of the HER2000 International Study

The tests that are currently available for the measurement of overexpression of the human epidermal growth factor-2 (HER2) in breast cancer have shown considerable problems in accuracy and interlaboratory reproducibility. Although these problems are partly alleviated by the use of validated, standardised 'kits', there may be considerable cost involved in their use. Prior to testing it may therefore be an advantage to be able to predict from basic pathology data whether a cancer is likely to overexpress HER2. In this study, we have correlated pathology features of cancers with the frequency of HER2 overexpression assessed by immunohistochemistry (IHC) using HercepTest (Dako). In addition, fluorescence in situ hybridisation (FISH) has been used to re-test the equivocal cancers and interobserver variation in assessing HER2 overexpression has been examined by a slide circulation scheme. Of the 1536 cancers, 1144 (74.5%) did not overexpress HER2. Unequivocal overexpression (3+ by IHC) was seen in 186 cancers (12%) and an equivocal result (2+ by IHC) was seen in 206 cancers (13%). Of the 156 IHC 3+ cancers for which complete data was available, 149 (95.5%) were ductal NST and 152 (97%) were histological grade 2 or 3. Only 1 of 124 infiltrating lobular carcinomas (0.8%) showed HER2 overexpression. None of the 49 'special types' of carcinoma showed HER2 overexpression. Re-testing by FISH of a proportion of the IHC 2+ cancers showed that only 25 (23%) of those assessable exhibited HER2 gene amplification, but 46 of the 47 IHC 3+ cancers (98%) were confirmed as showing gene amplification. Circulating slides for the assessment of HER2 score showed a moderate level of agreement between pathologists (kappa 0.4). As a result of this study we would advocate consideration of a triage approach to HER-2 testing. Infiltrating lobular and special types of carcinoma may not need to be routinely tested at presentation nor may grade 1 NST carcinomas in which only 1.4% have been shown to overexpress HER2. Testing of these carcinomas may be performed when HER2 status is required to assist in therapeutic or other clinical/prognostic decision-making. The highest yield of HER2 overexpressing carcinomas is seen in the grade 3 NST subgroup in which 24% are positive by IHC. (C) 2003 Elsevier Science Ltd. All rights reserved.

Microstructural evolution of the Serido Belt, NE-Brazil: the effect of two tectonic events on development of c-axis preferred orientation in quartz

The polyphase evolution of the Serido Belt (NE-Brazil) includes D, crust formation at 2.3-2.1 Ga, D-2 thrust tectonics at 1.9 Ga and crustal reworking by D-3 strike-slip shear zones at 600 Ma. Microstructural investigations within mylonites associated with D-2 and D-3 events were used to constrain the tectono-thermal evolution of the belt. D-2 shear zones commenced at deeper crustal levels and high amphibolite facies conditions (600-650 degreesC) through grain boundary migration, subgrain rotation and operation of quartz Q-prism slip. Continued shearing and exhumation of the terrain forced the re-equilibration of high-T fabrics and the switching of slip systems from (c)-prism to positive and negative (a)-rhombs. During D-3, enhancement of ductility by dissipation of heat that came from syn-D-3 granites developed wide belts of amphibolite facies mylonites. Continued shearing, uplift and cooling of the region induced D-3 shear zones to act in ductile-brittle regimes, marked by fracturing and development of thinner belts of greenschist facies mylonites. During this event, switching from (a)-prism to a basal slip indicates a thermal path from 600 to 350 degreesC. Therefore, microstructures and quartz c-axis fabrics in polydeformed rocks from the Serido Belt preserve the record of two major events, which includes contrasting deformation mechanisms and thermal paths. (C) 2003 Elsevier Ltd. All rights reserved.

(-)-CGP 12177 increases contractile force and hastens relaxation of human myocardial preparations through a propranolol-resistant state of the beta1-adrenoceptor

Two forms of the activated beta(1)-adrenoceptor exist, one that is stabilized by (-)-noradrenaline and is sensitive to blockade by (-)-propranolol and another which is stabilized by partial agonists such as (-)-pindolol and (-)-CGP 12177 but is relatively insensitive to (-)-propranolol. We investigated the effects of stimulation of the propranolol-resistant PI-adrenoceptor in the human heart. Myocardium from non-failing and failing human hearts were set up to contract at 1 Hz. In right atrium from non-ailing hearts in the presence of 200 nM (-)-propranolol, (-)-CGP 12177 caused concentration-dependent increases in contractile force (-logEC(50)[M] 7.3+/-0.1, E-max 23+/-1% relative to maximal (-)-isoprenaline stimulation of beta(1)- and beta(2)-adrenoceptors, n=86 patients), shortening of the time to reach peak force (-logEC(50)[M] 7.4+/-0.1, E-max 37+/-5%, n=61 patients) and shortening of the time to reach 50% relaxation (t(50%), -logEC(50)[M] 7.3+/-0.1, E-max 33+/-2%, n=61 patients). The potency and maxima of the positive inotropic effects were independent of Ser49Gly- and Gly389Arg-beta(1)-adrenoceptor polymorphisms but were potentiated by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (-logEC(50)[M] 7.7+/-0.1, E-max 68+/-6%, n=6 patients, P

Effects of glucose-insulin-potassium infusion on chronic ischaemic left ventricular dysfunction

Background: Glucose-insulin-potassium (GIK) infusion improves cardiac function and outcome during acute ischaemia. Objective: To determine whether GIK infusion benefits patients with chronic ischaemic left ventricular dysfunction, and if so whether this is related to the presence and nature of viable myocardium. Methods: 30 patients with chronic ischaemic left ventricular dysfunction had dobutamine echocardiography and were given a four hour infusion of GIK. Segmental responses were quantified by improvement in wall motion score index (WMSI) and peak systolic velocity using tissue Doppler. Global responses were assessed by left ventricular volume and ejection fraction, measured using a three dimensional reconstruction. Myocardial perfusion was determined in 15 patients using contrast echocardiography. Results: WMSI (mean (SD)) improved with dobutamine (from 1.8 (0.4) to 1.6 (0.4), p < 0.001) and with GIK (from 1.8 (0.4) to 1.7 (0.4) p < 0.001); there was a similar increment for both. Improvement in wall motion score with GIK was observed in 55% of the 62 segments classed as viable by dobutamine echocardiography, and in 5% of 162 classed as non-viable. There was an increment in peak systolic velocity after both doputamine echocardiography (from 2.5 (1.8) to 3.2 (2.2) cm/s, p < 0.01) and GIK (from 3.0 (1.6) to 3.5 (17) cm/s, p < 0.001). The GlK effects were not mediated by changes in pulse, mean arterial pressure, lactate, or catecholamines, nor did they correlate with myocardial perfusion. End systolic volume improved after GlK (p = 0.03), but only in 25 patients who had viable myocardium on dobutom ne echocardiography. Conclusions: In patients with viable myocardium and chronic left ventricular dysfunction, GlK improves wall motion score, myocardial velocity, and end systolic volume, independent of effects on haemodynamics or catecholamines. The response to GlK is observed in areas of normal and abnormal perfusion assessed by contrast echocardiography.

Methoxy(2-pyridyl)ketene

Matrix photolysis of 3-methoxycarbonyl-1,2,3-triazolo[1,5-a]pyridine (12) affords s-E-2-pyridylketene (4), but flash vacuum thermolysis of 12 gives methoxy(2-pyridyl)ketene (15), predominantly in the s-Z-conformation. Matrix photolysis of 15 affords 2-acetylpyridine. Copyright (C) 2003 John Wiley Sons, Ltd.

Effects of herbicides diuron and atrazine on corals of the Great Barrier Reef, Australia

In response to recent reports of contamination of the nearshore marine environment along the Queensland coast by herbicides (including areas inside the Great Barrier Reef Marine Park), an ecotoxicological assessment was conducted of the impact of the herbicides diuron and atrazine on scleractinian corals. Pulse-amplitude modulated (PAM) chlorophyll fluorescence techniques were used to assess the herbicide effects on the symbiotic dinoflagellates within the tissues (in hospite) of 4 species of coral (Acropora formosa, Montipora digitata, Porites cylindrica, Seriatopora hystrix) in static toxicity tests, and in freshly isolated symbiotic dinoflagellates from Stylophora pistillata. Using change in the effective quantum yield (DeltaF/F-m') as an effect criterion, diuron (no observable effect concentration, NOEC = 0.3 mug 1(-1); lowest observable effect concentration, LOEC = 1 mug 1(-1); median effective concentration, EC50 4 to 6 mug 1(-1)) was found to be more toxic than atrazine (NOEC = 1 mug 1(-1), LOEC = 3 mug 1(-1), EC50 40 to 90 mug 1(-1)) in short-term (10 h) toxicity tests. In the tests with isolated algae, significant reductions in DeltaF/F-m' were recorded as low as 0.25 mug 1(-1) diuron (LOEC, EC50 = 5 mug 1(-1)). Time-course experiments indicated that the effects of diuron were rapid and reversible. At 10 mug 1(-1) diuron, DeltaF/F-m' was reduced by 25% in 20 to 30 min, and by 50% in 60 to 90 min. Recovery of DeltaF/F-m' in corals exposed to 10 mug 1(-1) diuron and then transferred to running seawater was slower, returning to within 10% of control values inside 1 to 7 h. The effect of a reduction in salinity (35 to 27%) on diuron toxicity (at 1 and 3 mug 1(-1) diuron) was tested to examine the potential consequences of contaminated coastal flood plumes inundating inshore reefs. DeltaF/F-m' was reduced in the diuron-exposed corals, but there was no significant interaction between diuron and reduced salinity seawater within the 10 h duration of the test. Exposure to higher (100 and 1000 mug 1(-1)) diuron concentrations for 96 h caused a reduction in DeltaF/F-m' the ratio variable to maximal fluorescence (F,1F.), significant loss of symbiotic dinoflagellates and pronounced tissue retraction, causing the corals to pale or bleach. The significance of the results in relation to diuron contamination of the coastal marine environment from terrestrial sources (mainly agricultural) and marine sources (antifouling paints) are discussed.

Model studies on the role of citrate, malate and pectin esterification on the enzymatic degradation of Al- and Ca-pectate gels: possible implications for Al-tolerance

Aluminium (At) tolerance in plants may be conferred by reduced binding of Al in the cell wall through low root cation exchange capacity (CEC) or by organic acid exudation. Root CEC is related to the degree of esterification (DE) of pectin in the cell wall, and pectin hydrolysis plays a role in cell expansion. Therefore, it was hypothesised that Al-tolerant plants with a low root CEC maintain pectin hydrolysis in the presence of Al, allowing cell expansion to continue. Irrespective of the DE, binding of Al to pectin reduced the enzymatic hydrolysis of Al-pectin gels by polygalacturonase (E.C. 3.2.1.15). Pectin gels with calcium (Ca) were slightly hydrolysed by polygalacturonase. It was concluded, therefore, that Al tolerance conferred by low root CEC is not mediated by the ability to maintain pectin hydrolysis. Citrate and malate, but not acetate, effectively dissolved Al-pectate gel and led to hydrolysis of the dissolved pectin by polygalacturonase. The organic acids did not dissolve Ca-pectate, nor did they increase pectin hydrolysis by polygalacturonase. It was concluded that exudation of some organic acids can remove Al bound to pectin and this could alleviate toxicity, constituting a tolerance mechanism. (C) 2003 Editions scientitiques et medicales Elsevier SAS. All rights reserved.

Discrete cyanide-bridged mixed-valence Co/Fe complexes: Outer-sphere redox behaviour

The outer-sphere redox behaviour of a series of [LnCoIII-NCFeII(CN)(5)](-) (L-n = n-membered pentadentate aza-macrocycle) complexes have been studied as a function of pH and oxidising agent. All the dinuclear complexes show a double protonation process at pH approximate to 2 that produces a shift in their UV/Vis spectra. Oxidation of the different non-protonated and diprotonated complexes has been carried out with peroxodisulfate, and of the non-protonated complexes also with trisoxalatocobaltate(III). The results are in agreement with predictions from the Marcus theory. The oxidation of [Fe(phen)(3)](3+) and [IrCl6](2-) is too fast to be measured, although for the latter the transient observation of the process has been achieved at pH = 0. The study of the kinetics of the outer-sphere redox process, with the S2O82- and [Co(ox)(3)](3-) oxidants, has been carried out as a function of pH, temperature, and pressure. As a whole, the values found for the activation volumes, entropies, and enthalpies are in the following margins, for the diprotonated and non-protonated dinuclear complexes, respectively: DeltaV(not equal) from 11 to 13 and 15 to 20 cm(3) mol(-1); DeltaS(not equal) from 110 to 30 and -60 to -90 J K-1 mol(-1); DeltaH(not equal) from 115 to 80 and 50 to 65 kJ.mol(-1). The thermal activation parameters are clearly dominated by the electrostriction occurring on outer-sphere precursor formation, while the trends found for the values of the volume of activation indicate an important degree of tuning due to the charge distribution during the electron transfer process. The special arrangement on the amine ligands in the isomer trans[(L14CoNCFeII)-N-III(CN)(5)](-) accounts for important differences in solvent-assisted hydrogen bonding occurring within the outer-sphere redox process, as has been established in redox reactions of similar compounds. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).