A 50 EW/cm;2 Ti:sapphire laser system for studying relativistic light-matter interactions

A 10-Hz repetition rate, 60-TW peak power, Ti:sapphire laser system was developed for use in experiments where relativistic effects dominate the physics. The temporal, spectral, energy and spatial characteristics of the laser pulses were measured in single shot format. The pulse duration ranged from 22 fs to 25 fs and the pulse energy averaged 1.3 J. Atomic photoionization measurements quantified the peak intensity of the laser pulse in situ. The measurements indicated an intensity of at least 510 19 W/cm 2 was produced.

Hepatitis C antibody detection in dried blood spots

In the UK, there have been few studies of the seroprevalence of antibodies to hepatitis C virus (anti-HCV). As part of an ongoing prevalence study of HCV in injecting drug users, we have developed a technique for detecting anti-HCV in blood spots dried on filter paper using a commercially available assay. Subjects with and without serum anti-HCV were studied. The manufacturer's recommended cut-off (CO) for a positive anti-HCV result is kit-dependent, and therefore a ratio of test result (T) to kit CO was used to standardize results. T/CO values greater than 0.99 had a sensitivity of 100% and a specificity of 87.5% for anti-HCV detection. T/CO values greater than 1.99 had a sensitivity of 97.2% and a specificity of 100%. Hence, testing dried blood spots may be useful for detecting anti-HCV in epidemiological studies and as a diagnostic test in patients with poor peripheral venous access.

Calretinin-immunoreactive nerves in the uterus, pelvic autonomic ganglia, lumbosacral dorsal root ganglia and lumbosacral spinal cord

Nerves containing the calcium-binding protein calretinin have been reported in several organs but not in female reproductive organs and associated ganglia. This study was undertaken to determine if nerves associated with the uterus contain calretinin and the source(s) of calretinin-synthesizing nerves in the rat (are they sensory, efferent, or both?). Calretinin-immunoreactive nerves were present in the uterine horns and cervix where they were associated with arteries, uterine smooth muscle, glands, and the epithelium. Calretinin-immunoreactive terminals were apposed to neurons in the paracervical ganglia; in addition, some postganglionic neurons in this ganglion were calretinin positive. Calretinin perikarya were present in the lumbosacral dorsal root ganglia, no-dose ganglia, and lumbosacral spinal cord. Retrograde axonal tracing, utilizing Fluorogold injected into the uterus or paracervical parasympathetic ganglia, revealed calretinin-positive/Fluorogold-labeled neurons in the dorsal root and nodose ganglia. Also, capsaicin treatment substantially reduced the calretinin-positive fibers in the uterus and pelvic ganglia, thus indicating the sensory nature of these fibers. The presence of calretinin immunoreactivity identifies a subset of nerves that are involved in innervation of the pelvic viscera and have origins from lumbosacral dorsal root ganglia and vagal nodose ganglia. Though the exact function of calretinin in these nerves is not currently known, calretinin is likely to play a role in calcium regulation and their function.

Modelling density-dependent resistance in insect-pathogen interactions

We consider a mathematical model for a host-pathogen interaction where the host population is split into two categories: those susceptible to disease and those resistant to disease. Since the model was motivated by studies on insect populations, we consider a discrete-time model to reflect the discrete generations which are common among insect species. Whether an individual is born susceptible or resistant to disease depends on the local population levels at the start of each generation. In particular, we are interested in the case where the fraction of resistant individuals in the population increases as the total population increases. This may be seen as a positive feedback mechanism since disease is the only population control imposed upon the system. Moreover, it reflects recent experimental observations from noctuid moth-baculovirus interactions that pathogen resistance may increase with larval density. We find that the inclusion of a resistant class can stabilise unstable host-pathogen interactions but there is greatest regulation when the fraction born resistant is density independent. Nonetheless, inclusion of density dependence can still allow intrinsically unstable host-pathogen dynamics to be stabilised provided that this effect is sufficiently small. Moreover, inclusion of density-dependent resistance to disease allows the system to give rise to bistable dynamics in which the final outcome is dictated by the initial conditions for the model system. This has implications for the management of agricultural pests using biocontrol agents-in particular, it is suggested that the propensity for density-dependent resistance be determined prior to such a biocontrol attempt in order to be sure that this will result in the prevention of pest outbreaks, rather than their facilitation. Finally we consider how the cost of resistance to disease affects model outcomes and discover that when there is no cost to resistance, the model predicts stable periodic outbreaks of the insect population. The results are interpreted ecologically and future avenues for research to address the shortfalls in the present model system are discussed.

Stability of questionnaire items in sport and exercise psychology: bootstrap limits of agreement

We describe an alternative method for assessing the stability of individual questionnaire items in sport and exercise psychology. To date, the Pearson product-moment correlation coefficient has been widely used in psychometrics. We propose an alternative non-parametric method based on proportion of agreement. Ninety-two male university students completed the revised 9-item Social Physique Anxiety Scale on two occasions, separated by a 2-week interval. Point estimates of the proportion of direct within-individual agreement between the two occasions were calculated separately for each item of the Social Physique Anxiety Scale. Estimates of uncertainty of the agreement were calculated using a bootstrapping resampling technique. For each item, 2000 bootstrap samples (each n = 92 pairs) were redrawn from the original sample. The sample statistic was calculated for each bootstrap sample to provide a bootstrap sampling distribution. The 95% confidence intervals (CI) were then calculated using the percentile method. The three most problematic items were items 7, 8 and 10 (as labelled in the original 12-item scale). These items demonstrated an agreement of 0.46 (95% CI= 0.36 0.56), 0.42 (95% CI = 0.33-0.52) and 0.41 (95% CI = 0.32-0.51) respectively. Our proposed method measures absolute agreement between test-retest responses, is free of normal assumptions, does not depend on high between-individuals variance, and can be applied successfully to individual items in the development of psychological tests.

Effect of stretching duration on active and passive range of motion in the lower extremity

OBJECTIVES

To investigate the effect of different durations of stretching (five or 15 seconds) on active and passive range of motion (ROM) in the lower extremity during a five week flexibility training programme.

METHOD

Twenty four university sport club members (19 men, five women), with a mean (SD) age of 20.5 (1.35) years, were randomly assigned to one of three groups (two treatment and one control). The two treatment groups participated in a static active stretching programme three times a week for a five week period, holding each stretch for a duration of either five or 15 seconds. The total amount of time spent in a stretched position was controlled. The five second group performed each stretch nine times and the 15 second group three times resulting in a total stretching time of 45 seconds for both groups for each exercise. The control group did not stretch. Active and passive ROM were determined during left hip flexion, left knee flexion, and left knee extension before and after the training programme using an inclinometer.

RESULTS

Two factor within subject analysis of variance indicated no significant difference in ROM before and after the training programme for the control group. However, significant improvements in active and passive ROM (p < 0.05) were shown in both treatment groups after the five week training programme. Two factor analysis of variance with repeated measures and post hoc analysis showed significant differences between the treatment groups and the control group for the improvements observed in active (p < 0.05) and passive (p < 0.05) ROM. The five and 15 second treatment groups did not differ from one another when ROM was assessed passively, but significant differences were apparent for active ROM, with the 15 second group showing significantly greater improvements (p < 0.05) than the five second group.

CONCLUSION

These findings suggest that holding stretches for 15 seconds, as opposed to five seconds, may result in greater improvements in active ROM. However, sustaining a stretch may not significantly affect the improvements gained in passive ROM.

Crystallization and preliminary diffraction data analysis of both single and pseudo-merohedrally twinned crystals of rubredoxin oxygen oxidoreductase from Desulfovibrio gigas

Crystals of rubredoxin oxygen oxidoreductase have been obtained and characterized. They belong to space group P2(1)2(1)2, with unit-cell dimensions a = 88.24 (15), b = 101.25 (7), c = 90.80 (3) A. The homodimer (86 kDa) in the asymmetric unit is related by a non-crystallographic twofold rotation axis parallel to the ab 'diagonal' direction, as shown by the self-rotation maximum in the section with chi = 180 degrees. This pseudo-crystallographic symmetry element was also found to be the twinning axis of pseudo-merohedrally twinned crystals, leading to apparent pseudo-tetragonal P42(1)2 crystal symmetry.

A clinical trial of retroviral-mediated transfer of a rev-responsive element decoy gene into CD34(+) cells from the bone marrow of human immunodeficiency virus-1-infected children

Genetic modification of hematopoietic stem cells with genes that inhibit replication of human immunodeficiency virus-1 (HIV-1) could lead to development of T lymphocytes and monocytic cells resistant to HIV-1 infection after transplantation. We performed a clinical trial to evaluate the safety and feasibility of this procedure, using bone marrow from four HIV-1-infected pediatric subjects (ages 8 to 17 years). We obtained bone marrow, isolated CD34(+) cells, performed in vitro transduction with a retroviral vector carrying a rev-responsive element (RRE) decoy gene, and reinfused the cells into these subjects with no evidence of adverse effects. The levels of gene-containing leukocytes in peripheral blood samples in the 1 year after gene transfer/cell infusion have been extremely low. These observations support the potential of performing gene therapy for HIV-1 using hematopoietic cells, but emphasize the need for improved gene transfer techniques.

Adenovirus-mediated gene transfer of the beta2-adrenergic receptor to donor hearts enhances cardiac function

Gene transfer to modify donor heart function during transplantation has significant therapeutic implications. Recent studies by our laboratory in transgenic mice have shown that overexpression of beta2-adrenergic receptors (beta2-ARs) leads to significantly enhanced cardiac function. Thus, we investigated the functional consequences of adenovirus-mediated gene transfer of the human beta2-AR in a rat heterotopic heart transplant model. Donor hearts received 1 ml of solution containing 1 x 1010 p.f.u. of adenovirus encoding the beta2-AR or an empty adenovirus as a control. Five days after transplantation, basal left ventricular (LV) pressure was measured using an isolated, isovolumic heart perfusion apparatus. A subset of hearts was stimulated with the beta2-AR agonist, zinterol. Treatment with the beta2-AR virus resulted in global myocardial gene transfer with a six-fold increase in mean beta-AR density which corresponded to a significant increase in basal contractility (LV + dP/dtmax, control: 3152.1 +/- 286 versus beta2-AR, 6250.6* +/- 432.5 mmHg/s; n = 10, *P < 0.02). beta2-AR overexpressing hearts also had higher contractility after zinterol administration compared with control hearts. Our results indicate that myocardial function of the transplanted heart can be enhanced by the adenovirus-mediated delivery of beta2-ARs. Thus, genetic manipulation may offer a novel therapeutic strategy to improve donor heart function in the post- operative setting.

Heritable variation in resistance to gastro-intestinal nematodes in an unmanaged mammal population

The impact of parasites on natural populations has received considerable attention from evolutionary biologists in recent years. Central to a number of theoretical developments during this period is the assumption of additive genetic variation in resistance to parasites. However, very few studies have estimated the heritability of parasite resistance under field conditions, and those that have are mainly restricted to birds and their ectoparasites. In this paper, to our knowledge, we show for the first time in a free-ranging mammal population, Soay sheep (Ovis aries) living on the islands of St Kilda, that there is significant heritable variation in resistance to gastrointestinal nematodes. This result is consistent with earlier studies on this population which have indicated locus-specific associations with parasite resistance. We discuss our results in the context of current studies examining heritable resistance to parasites in domestic sheep and the possible mechanisms of selective maintenance of genetic variation for resistance to gastrointestinal nematodes in the St Kilda Soay sheep population.

Information system for clinical resource management in a regional setting

The Hospital District of Varsinais-Suomi consists of five hospitals for non-psychiatric diseases to deliver specialised health care for the population of 440,000 inhabitants in South-western Finland. We have applied an open regional information system to aid clinical resource management in such a complex expert organisation. The main areas of application have been assessment of inpatient care usage in different communities and in different diagnosis-related-groups (DRG), measurement of length of hospital stay in different DRGs and comparison of DRG unit weight costs of different hospitals. The open structure of the data base and its distribution to all parties of health care professionals has resulted in mutual decisions on structural changes and increased cost containment activities.

Comparing pediatric intentional injury surveillance data with data from publicly available sources: consequences for a public health response to violence

OBJECTIVE

A hospital based intentional injury surveillance system for youth (aged 3-18) was compared with other publicly available sources of information on youth violence. The comparison addressed whether locally conducted surveillance provides data that are sufficiently more complete, detailed, and timely that clinicians and public health practitioners interested in youth violence prevention would find surveillance worth conducting.

SETTING

The Boston Emergency Department Surveillance (BEDS) project was conducted at Boston Medical Center and the Children's Hospital, Boston.

METHOD

MEDLINE and other databases were searched for data sources that report separate data for youth and data on intentional injury. Sources that met these criteria (one national and three local) were then compared with BEDS data. Comparisons were made in the following categories: age, gender, victim-offender relationship, injury circumstance, geographic location, weapon rates, and violent injury rates.

RESULTS

Of 14 sources dealing with violence, only four met inclusion criteria. Each source provided useful breakdowns for age and gender; however, only the BEDS data were able to demonstrate that 32.6% of intentional injuries occurred among youth aged 12 and under. Comparison data sources provided less detail regarding the victim-offender relationship, injury circumstance, and weapon use. Comparison of violent injury rates showed the difficulties for practitioners estimating intentional injury from sources based on arrest data, crime victim data, or weapon related injury.

CONCLUSIONS

Comparison suggests that surveillance is more complete, detailed, and timely than publicly available sources of data. Clinicians and public health practitioners should consider developing similar systems.

Help seeking behaviour and health and social services utilisation by people suffering from urinary incontinence

It is estimated that urinary incontinence can effect up to 23% of the population at some time during their adult years, with 9% currently experiencing symptoms. This study found that the majority of sufferers had spoken to or had contacted their GP about their incontinence, and that people currently suffering from incontinence were significantly more likely to have seen their GP within the last month than those who were continent. Help seeking behaviour was also influenced by the severity of incontinence, with people suffering from severe incontinence significantly more likely to have sought help than those with light to moderate incontinence. Two thirds of sufferers who did not seek help were too embarrassed to do so. Significantly more people who were incontinent that did not seek help in a health authority without an established continence service did not know that health services were available, compared with those in a health authority having an established continence service. It is important for health care providers to ensure that the public knows what services are on offer and how to access them. Significantly more incontinence sufferers in the health authority with an established continence service chose not to seek help from a health professional compared with those in the health authority without service, which could indicate there was an element of informed choice in not accessing the services available. Significantly more people who were incontinent than continent required help with their activities of daily living and personal self care. They were also significantly more likely than those who were continent to require formal and informal contacts provided by health services, local authority, the church or voluntary sector. It is important that people suffering from incontinence have their health and social needs assessed so that services can be effectively targeted.

Cholinergic neurons of the pelvic autonomic ganglia and uterus of the female rat: distribution of axons and presence of muscarinic receptors

Acetylcholine (ACh) stimulates contraction of the uterus and dilates the uterine arterial supply. Uterine cholinergic nerves arise from the paracervical ganglia and were, in the past, characterized based on acetylcholinesterase (AChE) histochemistry. However, the histochemical reaction for acetylcholinesterase provides only indirect evidence of acetylcholine location and is a nonspecific marker for cholinergic nerves. The present study: (1) reevaluated cholinergic neurons of the paracervical ganglia, (2) examined the cholinergic innervation of the uterus by using retrograde axonal tracing and antibodies against molecules specific to cholinergic neurons, choline acetyltransferase and the vesicular acetylcholine transporter, and (3) examined muscarinic receptors in the paracervical ganglia using autoradiography and a radiolabeled agonist. Most ganglionic neurons were choline acetyltransferase- and vesicular acetylcholine transporter-immunoreactive and were apposed by choline acetyltransferase/vesicular acetylcholine transporter-immunoreactive terminals. Retrograde tracing showed that some cholinergic neurons projected axons to the uterus. These nerves formed moderately dense plexuses in the myometrium, cervical smooth muscle and microarterial system of the uterine horns and cervix. Finally, the paracervical ganglia contain muscarinic receptors. These results clearly reveal the cholinergic innervation of the uterus and cervix, a source of these nerves, and demonstrate the muscarinic receptor content of the paracervical ganglia. Cholinergic nerves could play significant roles in the control of uterine myometrium and vasculature.

The bisindolylmaleimide protein kinase C inhibitor, Ro 32-2241, reverses multidrug resistance in KB tumour cells

Ro 32-2241 is a bisindolylmaleimide that selectively inhibits protein kinase C (PKC) as compared with other protein kinases. Experiments were carried out to examine its potential as a multidrug resistance-reversing agent. Ro 32-2241 inhibited efflux, and increased accumulation, of [3H]-daunomycin in multidrug-resistant (MDR) KB-8-5 and KB-8-5-11 cells and had no effect on drug-sensitive KB-3-1 cells. Ro 32-2241 completely reversed the doxorubicin resistance of KB-8-5 and KB-8-5-11 cells, showing no effect on the sensitivity of drug-sensitive KB-3-1 cells. The potency of Ro 32-2241 was comparable with that of cyclosporin A and better than that of verapamil, known modulators of multidrug resistance. Ro 32-2241 also completely reversed the taxol resistance of KB-8-5 cells and partially reversed the resistance of KB-8-5-11 cells. Vinblastine resistance was also partially reversed. Mechanistic experiments were carried out to determine whether Ro 32-2241 interacted with P-glycoprotein (Pgp) directly. Increased efflux of [14C]-Ro 32-2241 was seen with the more resistant KB-8-5-11 cells (although the percentage effluxed was very low as compared with [3H]-daunomycin), suggesting that Ro 32-2241 can act as a substrate for Pgp. Direct interaction of Ro 32-2241 with Pgp was confirmed by demonstration that it inhibited binding of [3H]-azidopine to Pgp in KB-8-5-11 membranes. In conclusion, Ro 32-2241, acting directly on Pgp (rather than, or in addition to, an effect on PKC), is effective in reducing or reversing resistance to doxorubicin, taxol and vinblastine in human tumour cells with a clinically relevant degree of MDR. However, results of in vivo experiments conducted to investigate the effects of Ro 32-2241 on resistance to doxorubicin suggest that it may not be possible to achieve sufficiently high levels of Ro 32-2241 in vivo to modulate MDR.

The snoring spectrum: acoustic assessment of snoring sound intensity in 1,139 individuals undergoing polysomnography

STUDY OBJECTIVES

To quantify the snoring sound intensity levels generated by individuals during polysomnographic testing and to examine the relationships between acoustic, polysomnographic, and clinical variables.

DESIGN

The prospective acquisition of acoustic and polysomnographic data with a retrospective medical chart review.

SETTING

A sleep laboratory at a primary care hospital.

PARTICIPANTS

All 1,139 of the patients referred to the sleep laboratory for polysomnographic testing from 1980 to 1994.

INTERVENTIONS

The acoustic measurement of snoring sound intensity during sleep concurrent with polysomnographic testing.

MEASUREMENTS AND RESULTS

Four decibel levels were derived from snoring sound intensity recordings. L1, L5, and L10 are measures of the sound pressure measurement in decibels employing the A-weighting network that yields the response of the human ear exceeded, respectively, for 1, 5, and 10% of the test period. The Leq is a measure of the A-weighted average intensity of a fluctuating acoustic signal over the total test period. L10 levels above 55 dBA were exceeded by 12.3% of the patients. The average levels of snoring sound intensity were significantly higher for men than for women. The levels of snoring sound intensity were associated significantly with the following: polysomnographic testing results, including the respiratory disturbance index (RDI), sleep latency, and the percentage of slow-wave sleep; demographic factors, including gender and body mass; and clinical factors, including snoring history, hypersomnolence, and breathing stoppage. Men with a body mass index of > 30 and an average snoring sound intensity of > 38 dBA were 4.1 times more likely to have an RDI of > 10.

CONCLUSIONS

Snoring sound intensity levels are related to a number of demographic, clinical, and polysomnographic test results. Snoring sound intensity is closely related to apnea/hypopnea during sleep. The noise generated by snoring can disturb or disrupt a snorer's sleep, as well as the sleep of a bed partner.

The relationship between abdominal aortic aneurysm wall compliance, maximum diameter and growth rate

AIM

Aortic compliance as measured by the pressure-strain elastic modulus (Ep) and stiffness (beta), may allow a more precise estimate of rupture risk. The aim of this study was to determine the relationships between compliance, maximal aneurysm diameter and growth rate.

METHODS

Sixty abdominal aortic aneurysm patients of median age 73 years, were studied. Growth rate was derived from repeat ultrasound scans obtained over a median period of 21 months (range 6-48). At the end of follow-up, patients underwent measurement of maximum aortic diameter, Ep and beta using the Diamove echo-tracking system.

RESULTS

Growth rate correlated positively (r = 0.6, P < 0.01) with maximum diameter on entry to the study There was a positive correlation between mean arterial pressure and Ep (r = 0.3, P = 0.03), but not between mean arterial pressure and beta (r = 0.8, P = 0.61). A positive correlation was found between final maximum diameter and Ep (r = 0.22, P = 0.04) but not beta (r = 0.16, P = 0.11). There was no significant relationship between growth rate and Ep or beta.

CONCLUSION

Large aneurysms tended to be less compliant. Within a population of abdominal aortic aneurysm of similar maximum diameter there was a 10-fold variation in Ep and beta. Compliance and growth rate were not related. If aortic compliance is related to risk of rupture then this predictive information is likely to be largely independent of that currently obtained from size and growth rate.

Trypanosoma brucei: cis-acting sequences involved in the developmental regulation of PARP expression

The procyclic acidic repetitive protein (PARP or procyclin) of the parasitic protozoan Trypanosoma brucei is a developmentally regulated protein that shows extreme differences in its level of expression in different stages of the parasite's life cycle. Specifically, it is the major surface protein in the procyclic (insect) stage and, although the PARP gene is being actively transcribed in the mammalian bloodstream stage, there is no detectable PARP mRNA or protein in these cells. The 3'-untranslated region (UTR) of PARP, as well as other trypanosome genes, has the ability to confer the appropriate developmental regulation pattern onto chimeric reporter genes. To understand the mechanism of posttranscriptional regulation, selective replacement mutagenesis of the PARP mRNA 3'UTR was done to identify the cis-acting sequences involved in the down-regulation of this mRNA in bloodstream-form T. brucei. Transient transformation of constructs containing the PARP promoter and 5'UTR, the beta-glucuronidase coding region, and the selectively mutagenized or unaltered PARP 3'UTR were performed in procyclic and bloodstream T. brucei. The results of the reporter gene assays on the transformed cells indicate that there are at least two elements in the PARP 3'UTR which in bloodstream cells are involved in regulation of PARP expression and which appear to function as negative elements. In procyclic cells, there are two regions in which mutagenesis indicates positive cis-regulatory sequences, one of which has been previously defined (A. Hehl et al., 1994, Proc. Natl. Acad. Sci. USA 91, 370-374). These results indicate that multiple cis-acting elements within the PARP 3'UTR are involved in the developmental regulation of PARP expression and that regulation is controlled in a complex manner, presumably involving several cellular trans-acting factors.

Utility of hepatocytes to model species differences in the metabolism of loxtidine and to predict pharmacokinetic parameters in rat, dog and man

1. The metabolism of loxtidine (1-methyl-5-[3-[3-[(1-piperidinyl) methyl] phenoxy] propyl] amino-1H-1,2,4-triazole-3-methanol) was studied in freshly isolated rat, dog and human hepatocytes. Metabolism in vitro was comparable with previously available in vivo data in all three species with the marked species differences observed in vivo being reproduced in the hepatocyte model. 2. The major route for the metabolism of loxtidine by rat hepatocytes was N-dealkylation to form the propionic acid and hydroxymethyl triazole metabolites. A minor metabolic route was the oxidation of loxtidine to a carboxylic acid metabolite. The major route of metabolism for loxtidine in dog hepatocytes was glucuronidation with oxidation to the carboxylic acid metabolite being of minor importance. Incubation of loxtidine with human hepatocytes resulted in the drug remaining largely unchanged but with the carboxylic acid metabolite being produced in minor amounts. 3. In vitro studies were undertaken with rat, dog and human hepatocytes to determine the Michaelis-Menten parameters Vmax and Km for the sum of all the metabolic pathways. These kinetic parameters were used to calculate the intrinsic clearance of loxtidine. Using appropriate scaling factors, the predicted in vivo hepatic clearance was then calculated. The predicted intrinsic clearances were 51.4 +/- 12.4, 8.0 +/- 0.8 and 1.0 +/- 0.6 ml/min/kg for rat, dog and human hepatocytes respectively. These data were then used to calculate hepatic clearances of 24.5, 3.1 and 0.2 ml/min/kg for rat, dog and man respectively. 4. In vivo hepatic and intrinsic clearances for loxtidine were determined in rat, dog and human volunteers. The hepatic clearances of loxtidine were 26.6, 6.6 and 0.4 ml/min/kg in rat, dog and man respectively and intrinsic clearances were 58.5, 18.6 and 2.0 ml/min/kg in rat, dog and man respectively. 5. The present studies demonstrate that the hepatocyte model may be a valuable in vitro tool for predicting both qualitative and quantitative aspects of the metabolism of a drug in animals and man at an early stage of the drug development process.

Biological monitoring: the role of toxicokinetics and physiologically based pharmacokinetic modeling

This short review outlines the contribution of modeling techniques, particularly physiologically based pharmacokinetic (PBPK) modeling, in promulgating biological monitoring as a practical tool for the occupational health professional. The impact of modeling techniques is discussed in helping to establish the relevant biomarkers to measure, the appropriate time of sampling, and the relationship between atmospheric exposure limits and concentration of biological analyte. Of particular interest is the use of "population" PBPK techniques. These can explore the influence of physiological differences between workers or of particular susceptible subgroups (e.g., pregnant women, breast-feeding mothers, and infants) on the relationship between atmospheric exposure levels and biomarker concentration. Such techniques will become more widely used as biological monitoring guidance values (e.g., biological exposure indices, biological tolerance values) are increasingly established by various international professional and regulatory bodies.

Structure of catalase HPII from Escherichia coli at 1.9 A resolution

Catalase HPII from Escherichia coli, a homotetramer of subunits with 753 residues, is the largest known catalase. The structure of native HPII has been refined at 1.9 A resolution using X-ray synchrotron data collected from crystals flash-cooled with liquid nitrogen. The crystallographic agreement factors R and R(free) are respectively 16.6% and 21.0%. The asymmetric unit of the crystal contains a whole molecule that shows accurate 222-point group symmetry. The structure of the central part of the HPII subunit gives a root mean square deviation of 1.5 A for 477 equivalencies with beef liver catalase. Most of the additional 276 residues of HPII are located in either an extended N-terminal arm or in a C-terminal domain organized with a flavodoxin-like topology. A small number of mostly hydrophilic interactions stabilize the relative orientation between the C-terminal domain and the core of the enzyme. The heme component of HPII is a cis-hydroxychlorin gamma-spirolactone in an orientation that is flipped 180 degrees with respect to the orientation of the heme found in beef liver catalase. The proximal ligand of the heme is Tyr415 which is joined by a covalent bond between its Cbeta atom and the Ndelta atom of His392. Over 2,700 well-defined solvent molecules have been identified filling a complex network of cavities and channels formed inside the molecule. Two channels lead close to the distal side heme pocket of each subunit suggesting separate inlet and exhaust functions. The longest channel, that begins in an adjacent subunit, is over 50 A in length, and the second channel is about 30 A in length. A third channel reaching the heme proximal side may provide access for the substrate needed to catalyze the heme modification and His-Tyr bond formation. HPII does not bind NADPH and the equivalent region to the NADPH binding pocket of bovine catalase, partially occluded in HPII by residues 585-590, corresponds to the entrance to the second channel. The heme distal pocket contains two solvent molecules, and the one closer to the iron atom appears to exhibit high mobility or low occupancy compatible with weak coordination.

Migrant farm workers' access to pesticide protection and information: Cultivando Buenos Habitos campaign development

Formative evaluation of south Georgian migrant farm workers' access to information and products to promote pesticide protection and understanding of cancer risk associated with pesticide exposure was conducted using field observation, in-depth interviews of Georgia's Migrant Health Program's outreach workers, and structured face-to-face surveys of migrant farm workers. The data indicated that fewer than one-third of the pesticide products reviewed contained messages about pesticide use and exposure risk for humans. Risk information on products appeared in English only. Few protective devices were available for purchase. Migrant farm workers were aware in a very general sense of health risks posed by pesticides, but they were specifically unaware of the reach of pesticides sprayed, as illustrated by their field behaviors. Findings also demonstrated the need to educate outreach workers about migrant farm workers' cancer risk, so that they may act as migrant farm workers' health advocates to reduce the adverse effects associated with pesticide exposure.