Synthesis of [11C]BIIB104, an α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic-Acid-Positive Allosteric Modulator, and Evaluation of the Bio-Distribution in Non-Human Primate Brains Using Positron Emission Tomography

The aim of this study was to measure the brain penetrance and kinetics of BIIB104, a first-in-class AMPA receptor potentiator developed for cognitive impairment associated with schizophrenia. It was recently halted in phase 2 clinical development, and there are a lack of tools to directly measure AMPA receptor engagement. To achieve this, the drug candidate was radiolabeled with carbon-11, and its brain penetrance and kinetics were measured in non-human primates via dynamic PET scans. Radiolabeling was achieved through a three-step nucleophilic [11C]cyanation reaction in one pot, resulting in the high radioactivity and radiochemical purity (>99%) of [11C]BIIB104. The study found that [11C]BIIB104 entered the non-human primate brains at 4-5% ID at peak, with a homogeneous distribution. However, a mild regional heterogeneity was observed in the thalamus. The lack of conclusive evidence for a change in regional values after BIIB104 dosing suggests that any specific binding component of BIIB104 is negligible compared to the free and non-specific components in the living brain. Overall, the study demonstrated high brain uptake with minor variability in [11C]BIIB104 distribution across various brain regions, its kinetics were consistent with those of passive diffusion, and the dominating components were the free concentration and non-specific binding. This information is valuable for understanding the potential effects and mechanisms of BIIB104 in the brain.

Neuromelanin and T2*-MRI for the assessment of genetically at-risk, prodromal, and symptomatic Parkinson's disease

MRI was suggested as a promising method for the diagnosis and assessment of Parkinson's Disease (PD). We aimed to assess the sensitivity of neuromelanin-MRI and T₂* with radiomics analysis for detecting PD, identifying individuals at risk, and evaluating genotype-related differences. Patients with PD and non-manifesting (NM) participants [NM-carriers (NMC) and NM-non-carriers (NMNC)], underwent MRI and DAT-SPECT. Imaging-based metrics included 48 neuromelanin and T₂* radiomics features and DAT-SPECT specific-binding-ratios (SBR), were extracted from several brain regions. Imaging values were assessed for their correlations with age, differences between groups, and correlations with the MDS-likelihood-ratio (LR) score. Several machine learning classifiers were evaluated for group classification. A total of 127 participants were included: 46 patients with PD (62.3 ± 10.0 years) [15:LRRK2-PD, 16:GBA-PD, and 15:idiopathic-PD (iPD)], 47 NMC (51.5 ± 8.3 years) [24:LRRK2-NMC and 23:GBA-NMC], and 34 NMNC (53.5 ± 10.6 years). No significant correlations were detected between imaging parameters and age. Thirteen MRI-based parameters and radiomics features demonstrated significant differences between PD and NMNC groups. Support-Vector-Machine (SVM) classifier achieved the highest performance (AUC = 0.77). Significant correlations were detected between LR scores and two radiomic features. The classifier successfully identified two out of three NMC who converted to PD. Genotype-related differences were detected based on radiomic features. SBR values showed high sensitivity in all analyses. In conclusion, neuromelanin and T₂* MRI demonstrated differences between groups and can be used for the assessment of individuals at-risk in cases when DAT-SPECT can't be performed. Combining neuromelanin and T₂*-MRI provides insights into the pathophysiology underlying PD, and suggests that iron accumulation precedes neuromelanin depletion during the prodromal phase.

CDC field triage criteria accurately predicts outcomes in high impact trauma

BACKGROUND

The precision of emergency medical services (EMS) triage criteria dictates whether an injured patient receives appropriate care. The trauma triage protocol is a decision scheme that groups patients into triage categories of major, moderate and minor. We hypothesized that there is a difference between trauma triage category and injury severity score (ISS).

METHODS

This retrospective, observational study was conducted to investigate a difference between trauma triage category and ISS. Bivariate analysis was used to test for differences between the subgroup means. The differences between the group means on each measure were analyzed for direction and statistical significance using ANOVA for continuous variables and chi square tests for categorical variables. Logistic and linear regressions were performed to evaluate factors predicting mortality, ICU length of stay.

RESULTS

With respect to trauma triage category, our findings indicate that minor and moderate triage categories are similar with respect to ISS, GCS, ICU LOS, hospital LOS, and mortality. However, after excluding for low impact injuries (falls), differences between the minor and moderate categories were evident when comparing to ISS, GCS, ICU LOS, and hospital LOS. Additionally, after excluding for low impact injures, ISS, ICU LOS, and hospital stay were found to correlate well with trauma triage category.

CONCLUSIONS

In this retrospective, observational study significant differences were not seen when comparing ISS with the trauma triage categories of moderate and minor during our initial analysis. However, a difference was found after excluding for low impact injuries. These findings suggest that CDC criteria accurately predicts outcomes in high impact trauma.

The spatiotemporal changes in dopamine, neuromelanin and iron characterizing Parkinson's disease

In Parkinson's disease, there is a progressive reduction in striatal dopaminergic function, and loss of neuromelanin-containing dopaminergic neurons and increased iron deposition in the substantia nigra. We tested the hypothesis of a relationship between impairment of the dopaminergic system and changes in the iron metabolism. Based on imaging data of patients with prodromal and early clinical Parkinson's disease, we assessed the spatiotemporal ordering of such changes and relationships in the sensorimotor, associative and limbic territories of the nigrostriatal system. Patients with Parkinson's disease (disease duration < 4 years) or idiopathic REM sleep behaviour disorder (a prodromal form of Parkinson's disease) and healthy controls underwent longitudinal examination (baseline and 2-year follow-up). Neuromelanin and iron sensitive MRI and dopamine transporter single-photon emission tomography were performed to assess nigrostriatal levels of neuromelanin, iron, and dopamine. For all three functional territories of the nigrostriatal system, in the clinically most and least affected hemispheres separately, the following was performed: cross-sectional and longitudinal inter-group difference analysis of striatal dopamine and iron, and nigral neuromelanin and iron; in Parkinson's disease patients, exponential fitting analysis to assess the duration of the prodromal phase and the temporal ordering of changes in dopamine, neuromelanin or iron relative to controls; voxel-wise correlation analysis to investigate concomitant spatial changes in dopamine-iron, dopamine-neuromelanin and neuromelanin-iron in the substantia nigra pars compacta. The temporal ordering of dopaminergic changes followed the known spatial pattern of progression involving first the sensorimotor, then the associative and limbic striatal and nigral regions. Striatal dopaminergic denervation occurred first followed by abnormal iron metabolism and finally neuromelanin changes in the substantia nigra pars compacta, which followed the same spatial and temporal gradient observed in the striatum but shifted in time. In conclusion, dopaminergic striatal dysfunction and cell loss in the substantia nigra pars compacta are interrelated with increased nigral iron content.

Thematic Analysis of Parent-Child Conversations About COVID-19: "Playing It Safe"

Caregivers have primary responsibility for teaching their children self-protective behaviors, including those behaviors recommended by the Center for Disease Control (CDC) to prevent the spread of COVID-19. Parents have an important role in scaffolding adherence to the CDC recommendations and in managing stress and regulate their emotions to adaptively cope during uncertain times like those facing communities nationwide. The present study is a qualitative, thematic analysis of parent-reported (n = 210; 64.8% female; average age = 39.33; 14.3% ethnic/racial minority) interactions with children (focal child age: 25.2% birth to 5 years old, 36.7% 6 to 11 years old, 37.6% 12 to 18 years old) about topics associated to COVID-19-related viral transmission suppression guidelines and stress/coping behaviors. Themes included discussions about personal and social hygiene, and parent reported sources of child stress, and child stress management efforts. Findings from our thematic analysis indicate parents are motivated to make scaffolding personal hygiene fun and engaging, signaling a positive, developmentally appropriate native approach to their role as sources of coping socialization. These findings also underscore the importance of providing information to parents in ways that can be translated to children in developmentally appropriate conversations about viral transmission suppression activities and stress management during disasters.

Spatiotemporal changes in substantia nigra neuromelanin content in Parkinson’s disease

This study aimed to investigate the spatiotemporal changes in neuromelanin-sensitive MRI signal in the substantia nigra and their relation to clinical scores of disease severity in patients with early or progressing Parkinson’s disease and patients with idiopathic rapid eye movement sleep behaviour disorder (iRBD) exempt of Parkinsonian signs compared to healthy control subjects. Longitudinal T1-weighted anatomical and neuromelanin-sensitive MRI was performed in two cohorts, including patients with iRBD, patients with early or progressing Parkinson’s disease, and control subjects. Based on the aligned substantia nigra segmentations using a study-specific brain anatomical template, parametric maps of the probability of a voxel belonging to the substantia nigra were calculated for patients with various degrees of disease severity and controls. For each voxel in the substantia nigra, probability map of controls, correlations between signal-to-noise ratios on neuromelanin-sensitive MRI in patients with iRBD and Parkinson’s disease and clinical scores of motor disability, cognition and mood/behaviour were calculated. Our results showed that in patients, compared to the healthy control subjects, the volume of the substantia nigra was progressively reduced for increasing disease severity. The neuromelanin signal changes appeared to start in the posterolateral motor areas of the substantia nigra and then progressed to more medial areas of this region. The ratio between the volume of the substantia nigra in patients with Parkinson’s disease relative to the controls was best fitted by a mono-exponential decay. Based on this model, the pre-symptomatic phase of the disease started at 5.3 years before disease diagnosis, and 23.1% of the substantia nigra volume was lost at the time of diagnosis, which was in line with previous findings using post-mortem histology of the human substantia nigra and radiotracer studies of the human striatum. Voxel-wise patterns of correlation between neuromelanin-sensitive MRI signal-to-noise ratio and motor, cognitive and mood/behavioural clinical scores were localized in distinct regions of the substantia nigra. This localization reflected the functional organization of the nigrostriatal system observed in histological and electrophysiological studies in non-human primates (motor, cognitive and mood/behavioural domains). In conclusion, neuromelanin-sensitive MRI enabled us to assess voxel-wise modifications of substantia nigra’s morphology in vivo in humans, including healthy controls, patients with iRBD and patients with Parkinson’s disease, and identify their correlation with nigral function across all motor, cognitive and behavioural domains. This insight could help assess disease progression in drug trials of disease modification.

Initial Challenges of Caregiving During COVID-19: Caregiver Burden, Mental Health, and the Parent-Child Relationship

Research confirms that the mental health burdens following community-wide disasters are extensive, with pervasive impacts noted in individuals and families. It is clear that child disaster outcomes are worst among children of highly distressed caregivers, or those caregivers who experience their own negative mental health outcomes from the disaster. The current study used path analysis to examine concurrent patterns of parents' (n = 420) experience from a national sample during the early months of the U.S. COVID-19 pandemic. The results of a multi-group path analysis, organized by parent gender, indicate good fit to the data [X²(10) = 159.04, p < .01]. Results indicate significant linkages between parents' caregiver burden, mental health, and perceptions of children's stress; these in turn are significantly linked to child-parent closeness and conflict, indicating possible spillover effects for depressed parents and compensatory effects for anxious parents. The impact of millions of families sheltering in place during the COVID-19 pandemic for an undefined period of time may lead to unprecedented impacts on individuals' mental health with unknown impacts on child-parent relationships. These impacts may be heightened for families whose caregivers experience increased mental health symptoms, as was the case for fathers in the current sample.

Testing the Hybrid Battery Approach to Evaluating Sports-Related Concussion in the National Hockey League: A Factor Analytic Study

Purpose

Traditional “paper and pencil” neuropsychological tests and computerized test batteries have been employed in the assessment of sports-related concussion (SRC). Each type of test has inherent strengths and weaknesses. The NHL has constructed a “hybrid” battery of tests that uses both traditional and computerized measures in the evaluation of its players suspected of SRC. The purpose of this paper is to use factor analytic techniques to examine the relationships among the measures that comprise this battery.

Methods

Post-injury neuropsychological test data using the hybrid battery were obtained from 343 NHL players following their first concussion while playing in the league. ImPACT was used as the computer test battery. The traditional battery included: Hopkins Verbal Learning Test, Brief Visuospatial Memory Test, Color Trails, PSU Cancellation, Symbol Digits Modalities Test (including incidental memory), and Verbal Fluency.

Results

Five factors were extracted explaining 64.55% of the variance. The factor labels and the measures principally loading on each factor were as follows: Factor 1, Verbal Learning and Memory (HVLT Total and Delayed Recall); Factor 2, Processing Speed (Color Trails A/B, PSU Cancellation, and SDMT-Total); Factor 3, Visual Memory (BVMT- Total and Delayed); Factor 4, Cued Memory (ImPACT-Visual and Verbal Memory Composites); and Factor 5, Reaction Time (ImPACT Reaction Time and Visual Motor Speed composites).

Conclusion

These data underscore the unique contributions of traditional and ImPACT neuropsychological measures to the evaluation SRC in a sample of professional hockey players. It appears that both approaches measure different aspects of cognitive functioning. The next logical step is to use these data in evaluating the diagnostic utility of these measures as part of a combined battery.

The Utility of the King-Devick Test in Evaluating Professional Ice Hockey Players with Suspected Concussion

Purpose

The King-Devick (KD) is a measure of rapid number naming used in the evaluation of sports-related concussion (SRC). Recent data from the Canadian Football League and Rugby Union suggest that the KD should not be used as a stand-alone measure of SRC. The purpose of this study was to examine the diagnostic utility of the KD in professional ice hockey players.

Methods

NHL players who were suspected of having a concussion were evaluated with the KD and either the SCAT3 or the SCAT5. Players who were evaluated and not diagnosed with concussion served as Active controls. A small group of non-Active control players was also tested twice and was included in the present study for comparison.

Results

1605 players were evaluated with the KD at baseline. Of these, 53 were diagnosed with concussion, 76 were Active controls, and 11 were non-Active controls. Concussed players revealed a decline in performance from baseline to acute evaluation, t(52)=3.05, p<.01, d=.42 while Active controls significantly improved, t(75)=2.05, p<.05, d=.24. No significant change between baseline and acute testing was observed for non-Active controls. Using a cut score of any decline in performance from baseline to suspected injury evaluation yielded Sensitivity=64%, Specificity=61%, Positive Predictive Value=53% and Negative Predictive Value=71%.

Conclusion

Our data are consistent with previous studies suggesting that while the KD is useful in differentiating concussed and not concussed athletes acutely, the relatively low predictive values indicate that a decline in KD performance should not be used as a standalone measure to diagnose concussion.

Cytochrome P450-dependent metabolism of gefitinib

The in vitro metabolism of [(14)C]-gefitinib (1-3 microM) was investigated using human liver microsomes and a range of expressed human cytochrome P450 enzymes, with particular focus on the formation of O-desmethyl-gefitinib (M523595), the major metabolite observed in human plasma. High-performance liquid chromatography with ultraviolet light, radiochemical and mass spectral analysis, together with the availability of authentic standards, enabled quantification and structural identification of metabolites. On incubation with pooled human liver microsomes, [(14)C]-gefitinib underwent rapid and extensive metabolism to a number of metabolites, although M523595 was only a minor microsomal product. Formation of most metabolites was markedly decreased by ketoconazole, but M523595 production was inhibited only by quinidine. Gefitinib was metabolized extensively by expressed CYP3A4, producing a similar range of metabolites to liver microsomes, but M523595 was not formed. CYP1A2, 2C9 and 2C19 produced no measurable metabolism of gefitinib, while CYP3A5 produced a range of metabolites similar to CYP3A4, but to a much lower degree. In contrast, CYP2D6 catalysed rapid and extensive metabolism of gefitinib to M523595. While formation of M523595 was CYP2D6 mediated, the overall metabolism of gefitinib was dependent primarily on CYP3A4, and this was not obviously diminished in liver microsomes from CYP2D6 poor metabolizers.

In vitrometabolism of gefitinib in human liver microsomes

The in vitro metabolism of gefitinib was investigated by incubating [14C]-gefitinib, as well as M537194, M387783 and M523595 (the main metabolites of gefitinib observed in man), at a concentration of 100 microM with human liver microsomes (4 mg ml(-1)) for 120 min. These relatively high substrate and microsomal protein concentrations were used in an effort to generate sufficient quantities of metabolites for identification. HPLC with ultraviolet light, radiochemical and mass spectral analysis, together with the availability of authentic standards, enabled quantification and structural identification of a large number of metabolites. Although 16 metabolites were identified, metabolism was restricted to three regions of the molecule. The major pathway involved morpholine ring-opening and step-wise removal of the morpholine ring and propoxy side chain. O-demethylation of the quinazoline methoxy group was a quantitatively less important pathway, in contrast to the clinical situation, where O-desmethyl gefitinib (M523595) is the predominant plasma metabolite. The third metabolic route, oxidative defluorination, was only a minor route of metabolism. Some metabolites were formed by a combination of these processes, but no metabolism was observed in other parts of the molecule. Incubation of gefitinib produced ten identified metabolites, but the use of the three main in vivo metabolites as additional substrates enabled a more comprehensive metabolic pathway to be constructed and this has been valuable in supporting the more limited data available from the human in vivo study.

Metabolic disposition of gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, in rat, dog and man

Following oral administration of [14C]-gefitinib to albino and pigmented rats, radioactivity was widely and rapidly distributed, with the highest levels being found in liver, kidney, lung and gastrointestinal tract, but with only low levels penetrating the brain. Levels of radioactivity persisted in melanin-containing tissues (pigmented eye and skin). Binding to plasma proteins was high (86-94%) across the range of species examined and was 91% in human plasma. Substantial binding occurred to both human serum albumin and alpha-1 acid glycoprotein. Following oral and intravenous administration of [14C]-gefitinib, excretion of radioactivity by rat, dog and human occurred predominantly via the bile into faeces, with < 7% of the dose being eliminated in urine. In all three species, gefitinib was cleared primarily by metabolism. In rat, morpholine ring oxidation was the major route of metabolism, leading to the formation of M537194 and M608236 as the main biliary metabolites. Morpholine ring oxidation, together with production of M523595 by O-demethylation of the quinazoline moiety, were the predominant pathways in dog, with oxidative defluorination also occurring to a lesser degree. Pathways in healthy human volunteers were similar to dog, with O-demethylation and morpholine ring oxidation representing the major routes of metabolism.

Pharmacokinetics of gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, in rat and dog

The pharmacokinetics of gefitinib and its metabolites in rat and dog were investigated in preclinical studies conducted to support the safety evaluation and clinical development of gefitinib, the first EGFR tyrosine kinase inhibitor approved for the treatment of non-small-cell lung cancer. Following intravenous dosing (5 mg kg(-1), gefitinib plasma half-life was 3-6h in rats and dogs, although studies using a more sensitive HPLC-MS assay produced longer estimates of half-life (7-14h). In these studies, plasma clearance was high (male rat: 25 ml min(-1) kg(-1); female rat: 16 ml min(-1) kg(-1); male dog: 16 ml min(-1) kg(-1)), as was the volume of distribution (8.0-10.41 kg(-1) in rat; 6.31 kg(-1) in dog), and exposure in female rats was double that in males. Following administration of [14C]-gefitinib, concentrations of radioactivity in plasma exceeded gefitinib throughout the profile, indicating the presence of circulating metabolites in both rat and dog. An HPLC-MS assay was developed to measure concentrations of gefitinib and five potential metabolites in plasma. All five metabolites were detected in the rat, but at levels much lower than gefitinib. In the dog, exposure to gefitinib and M523595 was similar, with much lower concentrations of M537194 and only trace levels of the other metabolites. This profile of metabolites is similar to that observed in man.

Minimal contribution of desmethyl-gefitinib, the major human plasma metabolite of gefitinib, to epidermal growth factor receptor (EGFR)-mediated tumour growth inhibition

Desmethyl-gefitinib is a major metabolite of gefitinib observed in human plasma at concentrations similar to those of gefitinib. The epidermal growth factor receptor (EGFR)-related inhibitory effects of gefitinib and desmethyl-gefitinib have been compared both in vitro, using enzyme kinase assays and tumour cell growth inhibition, and in vivo by assessment of tumour xenografts growth inhibition in the mouse. Both gefitinib (IC(50) = 0.022 microM) and its desmethyl metabolite (0.036 microM) inhibited subcellular EGFR tyrosine kinase activity with a similar potency and selectivity. However, desmethyl-gefitinib (IC(50) = 0.76 microM) was 15 times less active than gefitinib (0.049 microM) against EGF-stimulated KB cell growth in a whole cell assay. Following a preliminary pharmacokinetic study to compare apparent oral bioavailability, gefitinib (75 mg kg(-1)) and desmethyl-gefitinib (150 mg kg(-1)) were administered orally for 15 days to female nude mice bearing LoVo tumour xenografts. Tumour concentrations of gefitinib (AUC = 300 microg h g(-1)) were much higher than those of desmethyl-gefitinib (44.3 microg h g(-1)), although plasma concentrations of gefitinib (48.4 microg h ml(-1)) and desmethyl-gefitinib (39.0 microg h ml(-1)) were quite similar at these dose levels. Gefitinib produced significant tumour growth inhibition throughout the course of the study ultimately resulting in a 50% decrease (compared with controls) by day 15. In contrast, although present at comparable plasma levels, desmethyl-gefitinib had little effect on tumour growth and is, therefore, considered unlikely to contribute significantly to the therapeutic activity of gefitinib in the clinical situation.

Presence of Salmonella in the red meat abattoir lairage after routine cleansing and disinfection and on carcasses

Foodborne pathogens, such as Salmonella, may remain in abattoir lairages after cleansing and pose a risk of transfer and contamination from one processing day to the next. These organisms may be transferred to the outer surface of animals held in lairage facilities, and the skin or hide may be a significant source of microbial contamination on the red meat carcasses subsequently produced. Sponge samples were taken from various sites in the lairage (n = 556), and single-pass sponge samples were taken from one side of red meat carcasses (n = 1,050) at five commercial abattoirs in Southwest England and tested for the presence of Salmonella. Of these, 6.5% of lairage samples were positive, containing estimated numbers of up to 10(4) Salmonella organisms per sampled area (50 by 50 cm). Salmonella was found on 9.6% of 240 lamb carcasses, 12.7% of 330 beef carcasses, 31% of 70 pig carcasses, 20% of 80 calf carcasses younger than 14 days of age, and none of 330 cull cow and bull carcasses. Subtyping divided the 137 isolates into seven serogroups and three pulsed-field gel electrophoresis clusters, and sensitivity testing against a bank of 16 antimicrobials indicated that 47 isolates had resistance to one or more antimicrobial agents. These results indicate that Salmonella contamination can persist in the lairage environment from one processing day to the next and that Salmonella is present on red meat carcasses, although the implications of residual lairage contamination on carcass meat microbiology are not clear from this study. Abattoir owners should take steps to reduce the level of contamination in their premises to prevent contamination from being carried over from one processing day to the next.

The normal population distribution of PRNP codon 129 polymorphism

OBJECTIVES

The common prion protein gene (PRNP) codon 129 polymorphism modifies the susceptibility to and the phenotype of prion diseases. However, no truly representative normal population-based data, or data stratified according to age or gender are available on the distribution of this polymorphism.

MATERIAL AND METHODS

Allelic variation of codon 129 in three Finnish populations representing different age groups, and among Finnish, British and Irish blood donors were examined.

RESULTS

The PRNP codon 129 genotype distribution in the total Finnish sample was 49% for methionine-methionine (MM), 42% for methionine-valine (MV) and 9% for valine-valine (VV), for the UK blood donors 42% for MM, 47% for MV and 11% for VV, and for the Irish blood donors 34% for MM, 56% for MV, and 10% for VV.

CONCLUSIONS

The genotype frequencies were almost identical in all three Finnish populations of different ages, with no gender differences, and did not differ from corresponding figures for the Finnish blood donors. However, the PRNP codon 129 genotype distribution in Finland differed significantly from that of the British and the Irish blood donors and the previously published blood donor data on other Western Europeans and Americans.

Phase I study of ZD9331 on short daily intravenous bolus infusion for 5 days every 3 weeks with fixed dosing recommendations

PURPOSE

To conduct a phase I study of ZD9331, a potent, nonpolyglutamatable thymidylate synthase inhibitor using a short daily infusion for 5 consecutive days every 21 days.

PATIENTS AND METHODS

Patients with refractory cancer or cancer for which no standard therapy was available were treated in escalating doses using an accelerated titration design. Plasma and urine samples were collected at timed intervals in the first cycle for pharmacokinetic analysis.

RESULTS

Seventy-four patients were enrolled at 12 dose levels from a starting dose of 0.4 mg/m(2)/d to 16 mg/m(2)/d and 25 mg/d fixed dosing, of which 67 were assessable for toxicity. Maximum-tolerated dose was reached at 16 mg/m(2)/d. Myelosuppression was dose-limiting, consisting of thrombocytopenia associated with neutropenic fever. Body-surface area did not correlate with drug clearance; therefore, fixed daily dosing of 25 mg/d was studied and found to be tolerable, with two of 12 dose-limiting events. Dose-limiting nonhematologic toxicity consisted of grade 3 erythematous maculopapular rash observed in one patient at 12 mg/m(2)/d and one patient at 25 mg/d. Pharmacokinetic analysis showed nonlinearity, with clearance increasing with dose. The mean clearance and terminal half-life of the drug were 6.6 +/- 2.0 mL/min and 71.3 +/- 27.0 hours, respectively. Area-under-the concentration-time curve was a better predictor of toxicity than dose, using multiple linear regression analyses. Minor response (40% shrinkage of tumor) was observed in one patient with colorectal cancer treated at 12 mg/m(2)/d.

CONCLUSION

The recommended dose for ZD9331 on this schedule is 25 mg/d. Neutropenia, thrombocytopenia, and rash were dose-limiting, and efficacy studies in colorectal cancer are indicated.

Isolation of the protein kinase TAO2 and identification of its mitogen-activated protein kinase/extracellular signal-regulated kinase kinase binding domain

We previously reported the cloning of the thousand and one-amino acid protein kinase 1 (TAO1), a rat homolog of the Saccharomyces cerevisiae protein kinase sterile 20 protein. Here we report the complete sequence and properties of a related rat protein kinase TAO2. Like TAO1, recombinant TAO2 selectively activated mitogen-activated protein/extracellular signal-regulated kinase kinases (MEKs) 3, 4, and 6 of the stress-responsive mitogen-activated protein kinase pathways in vitro and copurified with MEK3 endogenous to Sf9 cells. To examine TAO2 interactions with MEKs, the MEK binding domain of TAO2 was localized to an approximately 135-residue sequence just C-terminal to the TAO2 catalytic domain. In vitro this MEK binding domain associated with MEKs 3 and 6 but not MEKs 1, 2, or 4. Using chimeric MEK proteins, we found that the MEK N terminus was sufficient for binding to TAO2. Catalytic activity of full-length TAO2 enhanced its binding to MEKs. However, neither the autophosphorylation of the MEK binding domain of TAO2 nor the activity of MEK itself was required for MEK binding. These results suggest that TAO proteins lie in stress-sensitive kinase cascades and define a mechanism by which these kinases may organize downstream targets.

Isolation of TAO1, a protein kinase that activates MEKs in stress-activated protein kinase cascades

Several components of the budding yeast pheromone-response pathway are conserved in mammalian mitogen-activated protein (MAP) kinase pathways. Thus, we used degenerate oligonucleotides derived from the sequence of the Saccharomyces cerevisiae protein kinase Ste20p to amplify related sequences from the rat. One of these sequences was used to clone a rat Ste20p homolog, which we called TAO1 for its one thousand and one amino acids. Northern analysis shows TAO1 is highly expressed in brain, as is a homolog TAO2. Recombinant TAO1 was expressed and purified from Sf9 cells. In vitro, it activated MAP/extracellular signal-regulated protein kinase (ERK) kinases (MEKs) 3, 4, and 6 of the stress-responsive MAP kinase pathways, but not MEK1 or 2 of the classical MAP kinase pathway. TAO1 activated MEK3 but not MEK4 or MEK6 in transfected cells. MEK3 coimmunoprecipitated with TAO1 when they were expressed in 293 cells. In addition, immunoreactive MEK3 endogenous to Sf9 cells copurified with TAO1 produced from a recombinant baculovirus. The activation of and binding to MEK3 by TAO1 implicates TAO1 in the regulation of the p38-containing stress-responsive MAP kinase pathway.

Pharmacokinetics of meropenem in critically ill patients with acute renal failure treated by continuous hemodiafiltration

The pharmacokinetics of meropenem were studied in nine anuric critically ill patients treated by continuous venovenous hemodiafiltration. Peak levels after infusion of 1,000 mg over 30 min amounted to 103.2 +/- 45.9 microgram/ml, and trough levels at 12 h were 9.6 +/- 3.8 microgram/ml. A dosage of 1,000 mg of meropenem twice a day provides plasma drug levels covering intermediately susceptible microorganisms. Further reductions of the dosage might be appropriate for highly susceptible bacteria or when renal replacement therapies with lower clearances are applied.

A comparison of the pharmacokinetics of meropenem after intravenous administration by injection over 2, 3 and 5 minutes

The pharmacokinetics of meropenem were determined in 9 healthy volunteers after the administration of 1 g dose by injection over 2, 3 or 5 min. Peak plasma concentrations were not significantly different across the three rates of administration and, due to the finite time required for complete mixing of the blood in the central compartment, did not always occur at the end of the injection. Overall exposure to meropenem was unchanged by the more rapid rates of administration. Plasma clearance, terminal half-life and volume of distribution were virtually unchanged. Within 10 min after the start of the injection, the plasma concentrations from all three injections were very similar indicating that dosing over 2, 3 or 5 min would result in similar antimicrobial cover and, therefore, comparable efficacy. Comparison of the data derived from the three injections indicated that rapid administration of meropenem did not appreciably alter its disposition pharmacokinetics. Tolerability of meropenem was unchanged with the more rapid administration rate.

Opportunities for optimizing resource utilization in ambulatory academic practices

Growing emphasis on ambulatory service delivery in academic medical centers has heightened interest in improving operational efficiencies, while providing an optimal educational experience for medical students and residents. One significant challenge in the academic environment is maximizing resource utilization (both physical plant and personnel), through scheduling and operational effectiveness. This article examines how academic ambulatory practices can apply operational and scheduling process redesign methodologies to improve throughput and productivity, while enhancing the educational experience for students/residents.

Activation of mitogen-activated protein kinase cascades by p21-activated protein kinases in cell-free extracts of Xenopus oocytes

In the evolutionarily distant yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe, genetic evidence suggests that activation of pheromone-induced mitogen-activated protein kinase (MAPK) cascades involves the function of the p21cdc42/racl-activated protein kinases (PAKs) Ste20 and Shk1, respectively. In this report, we show that purified Ste20 and Shk1 were each capable of inducing p42MAPK activation in cell-free extracts of Xenopus laevis oocytes, while a mammalian Ste20/Shk1-related protein kinase, p65pak (Pak1), did not induce activation of p42MAPK. In contrast to p42MAPK, activation of JNK/SAPK in Xenopus oocyte extracts was induced by both the yeast Ste20 and Shk1 kinases, as well as by mammalian Pak1. Our results demonstrate that MAPK cascades that are responsive to PAKs are conserved in higher eukaryotes and suggest that distinct PAKs may regulate distinct MAPK modules.

A compilation of meropenem tissue distribution data

Meropenem body fluid and tissue concentration data from both published studies and samples obtained during efficacy evaluation have been compiled and presented according to a consistent format to facilitate comparison. The concentration data have been compared with the mode MIC data available for the pathogens isolated during the clinical evaluation of meropenem. These data support the widespread and rapid penetration of meropenem into the interstitial fluid of those tissues not protected by a tight epithelial barrier. Furthermore, they suggest that the proposed dosages of meropenem 500 mg or 1 g tds would provide an adequate duration of cover at tissue sites for the treatment of a range of commonly occurring pathogens. A higher dosage of 40 mg/kg or 2 g in adults given tds would be recommended for meningitis based on the penetration of meropenem into CSF. Overall, the tissue and body fluid data presented confirm the expectation, based on the plasma concentrations and theoretical arguments, that meropenem is rapidly and readily distributed into the interstitial fluid, thereby producing concentrations in tissues likely to be clinically effective. This is consistent with the available clinical data on the therapeutic efficacy of meropenem.

A comparison of the pharmacokinetics of meropenem after administration by intravenous injection over 5 min and intravenous infusion over 30 min

The pharmacokinetics of meropenem were determined in healthy volunteers after intravenous injection over 5 min or iv infusion over 30 min. Five volunteers received meropenem 500 mg and six volunteers received 1000 mg. For both doses, administration over 5 rather than 30 min doubled the plasma concentrations observed at the end of the dosing period. Comparison of the other data derived from the two modes of administration indicated that rapid administration of meropenem did not appreciably alter its disposition pharmacokinetics. Plasma clearance, renal clearance, non-renal clearance, terminal half-life and volume of distribution were unchanged. Within 1 h of dosing, the plasma concentrations were very similar indicating that dosing over either time period would result in similar antimicrobial cover and thus should not affect efficacy. There were no changes in tolerability of meropenem associated with more rapid administration.

The pharmacokinetics of meropenem in infants and children: a population analysis

Plasma meropenem concentration versus time data collected during a single dose, pharmacokinetic study in infants and children were analysed using the population pharmacokinetics program NONMEM. A total of 300 meropenem concentrations was obtained from 65 patients ranging from 2 months to 12 years of age; weighing between 3.7 and 46 kg. A two-compartment open pharmacokinetic model with a zero-order infusion over 30 min was fitted to the data. The most important determinant of meropenem clearance was the creatinine clearance but an additional improvement occurred when a nonlinear dependence upon age was included. The most important determinant of the volume of distribution in the central and peripheral compartments was the body weight. The distributional clearance showed a nonlinear dependence on body weight. Demographic factors other than weight and age were not found to be influential in the model. Both clearance and distributional clearance were markedly different in the younger (< 2 years) or lighter (< 10 kg) patients, respectively. Thereafter the parameter values slowly approached those found in adults. In this study, a mean of 4.6 samples per patient was used to provide information on the pharmacokinetics and the determinants of the pharmacokinetic variability in infants and children. The findings in the younger, lighter patients, if generally applicable, might have significance for the dosage recommendations for drugs with narrow therapeutic indices.

The pharmacokinetics of meropenem

Meropenem is a new carbapenem antibiotic which differs chemically from imipenem/cilastatin by having a 1-beta-methyl substitution, providing it with excellent intrinsic stability to human renal dehydropeptidase-I. In addition, an altered 2' side chain enhances its anti-pseudomonal activity. The drug has one identified metabolite, a beta-lactam ring-opened form which is devoid of microbiological activity, as would be expected. The parent compound displays linear pharmacokinetics over a dose range of 250 mg to 2 g. The terminal half-life is approximately 1 hour and the plasma clearance is approximately 15.5 L/h/70 kg. The plasma concentrations after a 1 g dose show a trough concentration (8 hours) of slightly greater than 0.25 mg/L. The renal route is the major clearance pathway for this drug and its metabolite, with renal clearance accounting for approximately 70% of the plasma clearance and there being approximately 70% of an administered dose recovered in the urine as intact parent compound over 12 hours. When combined with metabolite, over 90% of administered radiolabel is recovered in the urine over this 12 hour period. As expected, renal functional impairment alters the clearance of meropenem, but the alteration is predictable. Hepatic functional impairment does not alter drug disposition and no dosing alterations are required here. In summary, meropenem's disposition is similar to that seen for imipenem/cilastatin, except that no renal dehydropeptidase-I inhibitor is required. When evaluated against the background of its excellent profile of in vitro activity, it is clear that this is a drug of great promise which should be extensively evaluated in clinical trials of seriously ill patients with nosocomial infections.

Regulation of the MAP kinase cascade

The MAP kinase cascade is regulated by many hormones and growth factors and its activation leads to changes in properties of cytoplasmic, membrane-associated, and nuclear proteins. The MAP kinases themselves are activated by MEKS. MEKs lie at a point of convergence for multiple upstream signals, mediated by distinct protein kinases, Raf, MEK kinase, and Mos, all of which have MEK kinase activity. Additional inputs that stimulate the MAP kinase pathway are the activation of protein kinase C and the yeast protein kinase STE20. Mechanisms of regulation of some of the upstream components of this cascade have not yet been fully elucidated.

Pharmacokinetics of meropenem in subjects with various degrees of renal impairment

Five healthy volunteers and 18 patients with various degrees of renal impairment received 500 mg of meropenem intravenously as a 30-min infusion. Five dialysis patients were dosed 2 h prior to hemodialysis, and four of them were also dosed between hemodialysis treatments. Plasma and urine samples were collected for up to 48 h and 12 h, respectively. Concentrations of meropenem and its open ring metabolite ICI 213,689 were determined by high-performance liquid chromatography and radioimmunoassay, respectively. The subjects were divided into four groups with glomerular filtration rates (GFR) of greater than 80, 30 to 80, 5 to 29, or less than 5 ml/min. There were linear correlations between the GFR and the rates for total plasma clearance as well as renal clearance of meropenem (group mean values for total clearance of 186, 74, 53, and 19 ml/min/1.73 m2, respectively). In subjects with normal renal function, nonrenal clearance accounted for approximately 20% of total elimination, increasing to about 50% in patients with GFR between 5 and 29 ml/min/1.73 m2. The terminal half-life of meropenem increased from 0.9 h in the healthy volunteers to 6.8 h in patients with end-stage renal disease. The half-life of ICI 213,689 was 2.31 h in the healthy volunteers and increased to 23.6 h in patients with GFR of 5 to 29 ml/min. In patients with end-stage renal disease, half-lives could not be measured, as concentrations were hardly declining during the 48-h observation period. The area under the concentration-time curve for meropenem increased more than 10-fold. Both meropenem and its open ring metabolite were readily dialyzable, with dialysis clearances of 79 and 81 ml/min/1.73 m2, respectively.

Pharmacokinetics of meropenem and its metabolite ICI 213,689 in healthy subjects with known renal metabolism of imipenem

Six healthy male subjects who had received imipenem without cilastatin in previous studies, were given 500 mg meropenem as single 30 min intravenous infusions. Plasma and urine samples were collected for 12 h and meropenem and its metabolite were assayed by HPLC and RIA, respectively. The mean plasma half-life of meropenem was 0.8 h, mean plasma clearance 277 ml/min and the mean volume of distribution 20.4 l. The metabolite reached mean peak plasma concentrations of 1.5 mg/l. Renal clearance of meropenem averaged 200 ml/min. The mean urinary recovery of the metabolite was 20% and of unchanged drug 72% of the dose given. The recovery of meropenem ranged from 62.2% to 78.2% and was correlated to the urinary recovery of imipenem when given without cilastatin to the same subjects in previous studies (range 15.2-32.2%, rank correlation coefficient = 0.934). The results indicate that meropenem is much less susceptible to renal metabolism than imipenem. The inter-subject variability observed with meropenem correlates with the extent of urinary recovery of imipenem observed in previous studies with imipenem alone, indicating some susceptibility of meropenem to renal dehydropeptidase-I.

Pharmacokinetics of meropenem compared to imipenem-cilastatin in young, healthy males

Imipenem combined with cilastatin and meropenem was given as intravenous infusions of 1 g to eight young, healthy males on two separate occasions. Blood and urine samples were collected for up to 12 h. The terminal half-lives in plasma were 0.98 h and 1.11 h for meropenem and imipenem, respectively. The volume of distribution was smaller for meropenem than for imipenem (12.5 l and 14.4 l, respectively). The plasma clearance for meropenem was 188 (SD 31) ml/min and for imipenem 183 (SD 25) ml/min. Renal clearance was on average 139 (SD 24) ml/min and 135 (SD 11) ml/min, respectively. About 75% of the administered dose of both compounds was eliminated unchanged in urine. Non-renal clearance accounted for approximately 25% of the total clearance for both drugs. The kinetics of meropenem are very similar to those of imipenem given with cilastatin, and meropenem is as stable against renal metabolic degradation as imipenem combined with cilastatin.

The disposition of 2-cyano-1-methyl 3-(4-(4-methyl-6-oxo-1,4,5,6-tetrahydro-pyridazin-3-yl)phenyl)guanidine in animals

2-Cyano-1-methyl 3-(4-(4-methyl-6-oxo-1,4,5,6-tetrahydro-pyridazin-3-yl)phenyl)guan idine (SK&F 94836), a new positive inotrope/vasodilator, is being evaluated for the treatment of congestive heart failure. The absorption, metabolism, and disposition of the compound have been investigated in the rat, mouse, and dog. SK&F 94836 was rapidly absorbed, widely distributed, and rapidly and completely excreted primarily via the urine. There was no evidence of metabolism of the compound in any of the species studied. The compound showed minimal interaction with cytochrome P-450. The compound contains a chiral center. The enantiomers have been shown not to interconvert in either rat or dog. The serum protein binding was low in all species, including humans, and exhibited no stereoselectivity. Studies conducted in rat and dog using constant rate co-infusion of racemic SK&F 94836 and radiolabeled inulin have demonstrated that SK&F 94836 is eliminated by active tubular secretion.

A context for HIV testing in pregnancy

The use of the human immunodeficiency virus (HIV) antibody test for women of childbearing age is discussed. Serological tests used to determine HIV status are reviewed. Practitioners should be aware of the legal and ethical issues involved in testing. Psychological responses to knowledge of test results are considered. The goal of the counseling session is to provide sufficient information for the woman to make an informed decision about reproductive choices. The format and content of pre- and post-test sessions are outlined, and checklists that may assist the practitioner in post-test counseling appear in the Appendixes.

The pharmacokinetics of meropenem in volunteers

Two human volunteer studies were performed with meropenem: a dose proportionality study of 0.25, 0.5 and 1.0 g and a probenecid interaction study. Six volunteers took part in each study. Meropenem was generally well tolerated: One volunteer was withdrawn from the dose proportionality study because of looseness of stool and abdominal pain after a dose of 1.0 g. The plasma concentrations of meropenem were linearly related to dose. The half-life of meropenem was approximately 1 h and the urinary recovery of unchanged drug was 79%. In the presence of probenecid the plasma half-life of meropenem was increased by 33% but the urinary recovery was unaffected.

A new method of bile duct cannulation allowing bile collection and re-infusion in the conscious rat

A technique is described for collection of bile from the surgically-prepared, conscious rat after a postoperative recovery period of 7 days. This model can also be used to study enterohepatic recirculation.

Occupational safety and health implications of increased coal utilization

An area of major concern in considering increased coal production and utilization is the health and safety of increased numbers of workers who mine, process, or utilize coal. Hazards related to mining activities in the past have been especially serious, resulting in many mine related accidental deaths, disabling injuries, and disability and death from chronic lung disease. Underground coal mines are clearly less safe than surface mines. Over one-third of currently employed underground miners experience chronic lung disease. Other stresses include noise and extremes of heat and cold. Newly emphasized technologies of the use of diesel powered mining equipment and the use of longwall mining techniques may be associated with serious health effects. Workers at coal-fired power plants are also potentially at risk of occupational diseases. Occupational safety and health aspects of coal mining are understood well enough today to justify implementing necessary and technically feasible and available control measures to minimize potential problems associated with increased coal production and use in the future. Increased emphasis on safety and health training for inexperienced coal miners expected to enter the work force is clearly needed. The recently enacted Federal Mine Safety and Health Act of 1977 will provide impetus for increased control over hazards in coal mining.