Financial conflicts of interest among presenters, panellists and moderators at haematology and oncology FDA workshops

OBJECTIVE

To assess the characteristics and financial conflicts of interest of presenters, panellists and moderators at haematology and oncology workshops held jointly with or hosted by the US FDA.

SETTING

We included information on all publicly available haematology or oncology FDA workshop agendas held between 1 January 2018 and 31 December 2022.

EXPOSURE

General and research payments reported on Open Payments, industry funding to patient advocacy organizations reported on their webpages or 990 tax forms and employment in both pharmaceutical and regulatory settings.

RESULTS

Among physicians eligible for payments, 78% received at least one payment from the industry between 2017 and 2021. The mean general payment amount was $82,170 for all years ($16,434 per year) and the median was $14,906 for all years ($2981 per year). Sixty-nine per cent of patient advocacy speakers were representing organizations that received financial support from the pharmaceutical industry. Among those representing regulatory agencies or pharmaceutical companies, 16% had worked in both settings during their careers.

CONCLUSIONS AND RELEVANCE

Our findings in this cross-sectional study show a majority of US-based physician presenters at haematology and oncology workshops held jointly with members of the US FDA have some financial conflict of interest with the pharmaceutical industry. These findings support the need for clear disclosures and suggest that a more balanced selection of presenters with fewer conflicts may help to limit bias in discussions between multiple stakeholders.

Systematic Review and Meta-Analysis of Randomized Trials Testing Interventions to Reduce Physician Burnout

BACKGROUND

Physicians deal with intense professional pressures, which may contribute to increasing burnout. We sought to evaluate the efficacy of interventions designed to reduce burnout in physicians, physicians-in-training, and other health care professionals.

METHODS

We searched PubMed and Embase (through January 6, 2023) and reference lists. We included all randomized studies assessing an intervention designed to reduce professional burnout in physicians and other health care personnel. We adhered to the PRISMA reporting guidelines. We abstracted data on study and participant characteristics, study outcomes, and study quality. We used a random-effects model to pool mean differences in burnout change (pre- and post-intervention) between intervention and control arms.

RESULTS

Thirty-one of the 38 eligible studies (81.6%) used the Maslach Burnout Inventory (MBI) questionnaire to assess burnout. When comparing the intervention and control groups, the mean difference in the emotional exhaustion component of the MBI was -1.11 (95% confidence interval [CI], -2.14 to -0.09; I2: 74.5%; 20 studies); the mean difference in the depersonalization component of the MBI was -0.32 (95% CI, -0.63 to -0.01; I2: 54.2%; 17 studies); and the mean difference in the personal accomplishment component of the MBI was 1.11 (95% CI, -0.21 to 2.43; I2: 94.3%; 16 studies).

CONCLUSIONS

Studies testing interventions to decrease physician burnout led to significant numerical improvements in some domains of burnout, but it is unlikely that these changes result in meaningful changes in clinical burnout. Further, the limited follow-up time, biased assessments, and heterogeneity in intervention efficacy suggest that a more nuanced understanding of the causes of burnout is needed to develop more effective interventions.

Discovery of Novel Quinoline-Based Proteasome Inhibitors for Human African Trypanosomiasis (HAT)

Human African Trypanosomiasis (HAT) is a vector-borne disease caused by kinetoplastid parasites of the Trypanosoma genus. The disease proceeds in two stages, with a hemolymphatic blood stage and a meningo-encephalic brain stage. In the latter stage, the parasite causes irreversible damage to the brain leading to sleep cycle disruption and is fatal if untreated. An orally bioavailable treatment is highly desirable. In this study, we present a brain-penetrant, parasite-selective 20S proteasome inhibitor that was rapidly optimized from an HTS singleton hit to drug candidate compound 7 that showed cure in a stage II mouse efficacy model. Here, we describe hit expansion and lead optimization campaign guided by cryo-electron microscopy and an in silico model to predict the brain-to-plasma partition coefficient K_p as an important parameter to prioritize compounds for synthesis. The model combined with in vitro and in vivo experiments allowed us to advance compounds with favorable unbound brain-to-plasma ratios (K_p,uu) to cure a CNS disease such as HAT.

Reporting Outcomes of Pediatric Intensive Care Unit Patients to Referring Physicians via an Electronic Health Record-Based Feedback System

BACKGROUND

 Many critically ill children are initially evaluated in front-line settings by clinicians with variable pediatric training before they are transferred to a pediatric intensive care unit (PICU). Because clinicians learn from past performance, communicating outcomes of patients back to front-line clinicians who provide pediatric emergency care could be valuable; however, referring clinicians do not consistently receive this important feedback.

OBJECTIVES

 Our aim was to determine the feasibility, usability, and clinical relevance of a semiautomated electronic health record (EHR)-supported system developed at a single institution to deliver timely and relevant PICU patient outcome feedback to referring emergency department (ED) physicians.

METHODS

 Guided by the Health Information Technology Safety Framework, we iteratively designed, implemented, and evaluated a semiautomated electronic feedback system leveraging the EHR in one institution. After conducting interviews and focus groups with stakeholders to understand the PICU-ED health care work system, we designed the EHR-supported feedback system by translating stakeholder, organizational, and usability objectives into feedback process and report requirements. Over 6 months, we completed three cycles of implementation and evaluation, wherein we analyzed EHR access logs, reviewed feedback reports sent, performed usability testing, and conducted physician interviews to determine the system's feasibility, usability, and clinical relevance.

RESULTS

 The EHR-supported feedback process is feasible with timely delivery and receipt of feedback reports. Usability testing revealed excellent Systems Usability Scale scores. According to physicians, the process was well-integrated into their clinical workflows and conferred minimal additional workload. Physicians also indicated that delivering and receiving consistent feedback was relevant to their clinical practice.

CONCLUSION

 An EHR-supported system to deliver timely and relevant PICU patient outcome feedback to referring ED physicians was feasible, usable, and important to physicians. Future work is needed to evaluate impact on clinical practice and patient outcomes and to investigate applicability to other clinical settings involved in similar care transitions.

Practical Indicators for Risk of Airborne Transmission in Shared Indoor Environments and Their Application to COVID-19 Outbreaks

Some infectious diseases, including COVID-19, can undergo airborne transmission. This may happen at close proximity, but as time indoors increases, infections can occur in shared room air despite distancing. We propose two indicators of infection risk for this situation, that is, relative risk parameter (H_r) and risk parameter (H). They combine the key factors that control airborne disease transmission indoors: virus-containing aerosol generation rate, breathing flow rate, masking and its quality, ventilation and aerosol-removal rates, number of occupants, and duration of exposure. COVID-19 outbreaks show a clear trend that is consistent with airborne infection and enable recommendations to minimize transmission risk. Transmission in typical prepandemic indoor spaces is highly sensitive to mitigation efforts. Previous outbreaks of measles, influenza, and tuberculosis were also assessed. Measles outbreaks occur at much lower risk parameter values than COVID-19, while tuberculosis outbreaks are observed at higher risk parameter values. Because both diseases are accepted as airborne, the fact that COVID-19 is less contagious than measles does not rule out airborne transmission. It is important that future outbreak reports include information on masking, ventilation and aerosol-removal rates, number of occupants, and duration of exposure, to investigate airborne transmission.

Practical Indicators for Risk of Airborne Transmission in Shared Indoor Environments and Their Application to COVID-19 Outbreaks

Some infectious diseases, including COVID-19, can undergo airborne transmission. This may happen at close proximity, but as time indoors increases, infections can occur in shared room air despite distancing. We propose two indicators of infection risk for this situation, that is, relative risk parameter (H_r) and risk parameter (H). They combine the key factors that control airborne disease transmission indoors: virus-containing aerosol generation rate, breathing flow rate, masking and its quality, ventilation and aerosol-removal rates, number of occupants, and duration of exposure. COVID-19 outbreaks show a clear trend that is consistent with airborne infection and enable recommendations to minimize transmission risk. Transmission in typical prepandemic indoor spaces is highly sensitive to mitigation efforts. Previous outbreaks of measles, influenza, and tuberculosis were also assessed. Measles outbreaks occur at much lower risk parameter values than COVID-19, while tuberculosis outbreaks are observed at higher risk parameter values. Because both diseases are accepted as airborne, the fact that COVID-19 is less contagious than measles does not rule out airborne transmission. It is important that future outbreak reports include information on masking, ventilation and aerosol-removal rates, number of occupants, and duration of exposure, to investigate airborne transmission.

Updates to referring clinicians regarding critically ill children admitted to the pediatric intensive care unit: a state-wide survey

Background Front-line clinicians are expected to make accurate and timely diagnostic decisions before transferring patients to the pediatric intensive care unit (PICU) but may not always learn their patients' outcomes. We evaluated the characteristics of post-transfer updates received by referring clinicians regarding PICU patients and determined preferences regarding content, delivery, and timing of such updates. Methods We administered an electronic cross-sectional survey to Iowa clinicians who billed for ≥5 pediatric patients or referred ≥1 patient to the University of Iowa (UI) PICU in the year before survey administration. Results One hundred and one clinicians (51 non-UI, 50 UI-affiliated) responded. Clinicians estimated that, on average, 8% of pediatric patients they saw over 1 year required PICU admission; clinicians received updates on 40% of patients. Seventy percent of UI clinicians obtained updates via self-initiated electronic record review, while 37% of non-UI clinicians relied on PICU communication (p = 0.013). Clinicians indicated that updates regarding diagnoses/outcomes will be most relevant to their practice. Among clinicians who received updates, 13% received unexpected information; 40% changed their practice as a result. Conclusions Clinicians received updates on less than half of the patients they referred to a PICU, although such updates could potentially influence clinical practice. Study findings will inform the development of a formal feedback system from the PICU to referring clinicians.

Transgender inmates: A systems-based model for assessment and treatment planning

Concepts of gender, gender roles, and gender norms have continuously adapted with the increased acceptance of diversity throughout the United States in recent decades. Although guidelines exist regarding competent assessment and treatment of transgender individuals, correctional environments place substantial restrictions and complications on this process. Recent legal cases have increased public awareness of such cases, including challenges to the status quo of which responsibilities fall under the purview of correctional systems. This paper describes one model for the assessment and treatment-planning process for transgender inmates. This model follows sequential procedures and involves multidisciplinary collaboration to reach conclusions regarding diagnostic impressions and associated recommendations for treatment and correctional management. Case examples are presented to highlight relevant aspects of the model and identify potential pitfalls. Recommendations are offered for how psychologists can contribute to the success of such programs by using a holistic, multidimensional, systems-based approach to the assessment and treatment-planning process. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Key High-efficiency Practices of Emergency Department Providers: A Mixed-methods Study

OBJECTIVE

The objective of this study was to determine specific provider practices associated with high provider efficiency in community emergency departments (EDs).

METHODS

A mixed-methods study design was utilized to identify key behaviors associated with efficiency. Stage 1 was a convenience sample of 16 participants (ED medical directors, nurses, advanced practice providers, and physicians) identified provider efficiency behaviors during semistructured interviews. Ninety-nine behaviors were identified and distilled by a group of three ED clinicians into 18 themes. Stage 2 was an observational study of 35 providers was performed in four (30,000- to 55,000-visit) community EDs during two 4-hour periods and recorded in minute-by-minute observation logs. In Stage 3, each behavior or practice from Stage 1 was assigned a score within each observation period. Behaviors were tested for association with provider efficiency (relative value units/hour) using linear univariate generalized estimating equations with an identity link, clustered on ED site.

RESULTS

Five ED provider practices were found to be positively associated with efficiency: average patient load, using name of team member, conversations with health care team, visits to patient rooms, and running the board. Two behaviors, "inefficiency practices," demonstrated significant negative correlations: non-work-related tasks and documentation on patients no longer in the ED.

CONCLUSIONS

Average patient load, running the board, conversations with team member, and using names of team members are associated with enhanced provider productivity. Identification of behaviors associated with efficiency can be utilized by medical directors, clinicians, and trainees to improve personal efficiency or counsel team members.

Vascular aging and cardiac maladaptation in growth-restricted preterm infants

OBJECTIVE

To assess arterial morphology and mechanics in preterm infants with fetal growth restriction (FGR) compared with those appropriate for gestational age (AGA) in the early neonatal period.

STUDY DESIGN

This observational study involved 20 preterm FGR infants (28 to 32 weeks) of gestational age (GA) and birth weight (BW) <10th centile and 20 preterm AGA infants. Vascular ultrasound was performed to measure aortic properties.

RESULTS

GA and BW of FGR and AGA infants were 29.8±1.3 vs 30±0.9 weeks (P=0.78) and 923.4±168 vs 1403±237 g (P<0.001), respectively. At 10.5±1.3 (s.d.) days after birth, blood pressure (systolic 51±3 vs 46±4 mm Hg, P<0.001) and maximum aorta intima-media thickness (621±76 vs 479±54 μm; P<0.001) were significantly higher in FGR infants. Arterial wall stiffness and peripheral resistance were also increased in the FGR infants (2.36±0.24 vs 2.14±0.24, P=0.008 and 22.2±5 vs 13.7±2.3 mm Hg min ml^-1, P<0.001), respectively. Significant correlations between vascular mechanics and cardiac function were observed (resistance vs E/E', r=0.7 and Tei index, r=0.79).

CONCLUSION

Maladaptive arterial-ventricular coupling was noted. Early detection may aid in early therapeutic strategies such as afterload reduction.

High temporal variability in airborne bacterial diversity and abundance inside single-family residences

Our homes are microbial habitats, and although the amounts and types of bacteria in indoor air have been shown to vary substantially across residences, temporal variability within homes has rarely been characterized. Here, we sought to quantify the temporal variability in the amounts and types of airborne bacteria in homes, and what factors drive this variability. We collected filter samples of indoor and outdoor air in 15 homes over 1 year (approximately eight time points per home, two per season), and we used culture-independent DNA sequencing approaches to characterize bacterial community composition. Significant differences in indoor air community composition were observed both between homes and within each home over time. Indoor and outdoor air community compositions were not significantly correlated, suggesting that indoor and outdoor air communities are decoupled. Indoor air communities from the same home were often just as different at adjacent time points as they were across larger temporal distances, and temporal variation correlated with changes in environmental conditions, including temperature and relative humidity. Although all homes had highly variable indoor air communities, homes with the most temporally variable communities had more stable, lower average microbial loads than homes with less variable communities.

Microbial analyses of airborne dust collected from dormitory rooms predict the sex of occupants

We have long known that human occupants are a major source of microbes in the built environment, thus raising the question: How much can we learn about the occupants of a building by analyzing the microbial communities found in indoor air? We investigated bacterial and fungal diversity found in airborne dust collected onto heating, ventilation, and air-conditioning (HVAC) air filters and settling plates from 91 rooms within a university dormitory. The sex of the room occupants had the most significant effect on the bacterial communities, while the room occupants had no significant effect on fungal communities. By examining the abundances of bacterial genera, we could predict the sex of room occupants with 79% accuracy, a finding that demonstrates the potential forensic applications of studying indoor air microbiology. We also identified which bacterial taxa were indicators of female and male rooms, and found that those taxa often identified as members of the vaginal microbiome were more common in female-occupied rooms while taxa associated with human skin or the male urogenital microbiota were more common in male-occupied rooms.

Contribution of human-related sources to indoor volatile organic compounds in a university classroom

Although significant progress has been made in understanding the sources and chemistry of indoor volatile organic compounds (VOCs) during the past decades, much is unknown about the role of humans in indoor air chemistry. In the spring of 2014, we conducted continuous measurements of VOCs using a proton transfer reaction mass spectrometer (PTR-MS) in a university classroom. Positive matrix factorization (PMF) of the measured VOCs revealed a 'human influence' component, which likely represented VOCs produced from human breath and ozonolysis of human skin lipids. The concentration of the human influence component increased with the number of occupants and decreased with ventilation rate in a similar way to CO₂ , with an average contribution of 40% to the measured daytime VOC concentration. In addition, the human skin lipid ozonolysis products were observed to correlate with CO₂ and anticorrelate with O₃ , suggesting that reactions on human surfaces may be important sources of indoor VOCs and sinks for indoor O₃ . Our study suggests that humans can substantially affect VOC composition and oxidative capacity in indoor environments.

Identification of SNPs located on BTA 6 and BTA 20 significantly associated with bovine respiratory disease in crossbred cattle

The objective of the present study was to evaluate single nucleotide polymorphisms (SNPs) located in two quantitative trait locus (QTL) regions (BTA 6 and BTA 20) that are associated with bovine respiratory disease (BRD). A population of 323 crossbred steers sired by five purebred sire breeds during 2010-2013 (Angus, Braford, Braunvieh, Charolais, and Simmental) were evaluated for BRD susceptibility during the finishing process at a commercial feedlot. A total of 21 animals representing all sire breeds were affected with BRD at some time during the finishing process over the 4-year period. Although multiple sire breeds were evaluated in the present study, no sire breed effects were detected. A total of 82 SNPs were evaluated (58 on BTA 6 and 24 on BTA 20) in the present study for potential associations with BRD incidence. When evaluating the previously described QTL regions on BTA 6, three SNPs (rs42968895, rs42823614, and rs43448463) were significantly (P < 0.05) associated with BRD incidence. Another three SNPs (rs42477340, rs42512588, and rs42524468) were identified as significantly associated with BRD on the previously described BTA 6 QTL region. For both of these regions, animals inheriting different genotypes differed in BRD incidence during the finishing period. Although multiple SNPs were identified as being significantly associated with BRD incidence in the present study, these SNP associations should be validated in larger and more diverse populations.

Role of mechanical ventilation in the airborne transmission of infectious agents in buildings

Infectious disease outbreaks and epidemics such as those due to SARS, influenza, measles, tuberculosis, and Middle East respiratory syndrome coronavirus have raised concern about the airborne transmission of pathogens in indoor environments. Significant gaps in knowledge still exist regarding the role of mechanical ventilation in airborne pathogen transmission. This review, prepared by a multidisciplinary group of researchers, focuses on summarizing the strengths and limitations of epidemiologic studies that specifically addressed the association of at least one heating, ventilating and/or air-conditioning (HVAC) system-related parameter with airborne disease transmission in buildings. The purpose of this literature review was to assess the quality and quantity of available data and to identify research needs. This review suggests that there is a need for well-designed observational and intervention studies in buildings with better HVAC system characterization and measurements of both airborne exposures and disease outcomes. Studies should also be designed so that they may be used in future quantitative meta-analyses.

Potentially Avoidable Pediatric Interfacility Transfer Is a Costly Burden for Rural Families: A Cohort Study

OBJECTIVES

Interhospital transfer is a common strategy to provide high-quality regionalized care in rural emergency departments (EDs), but several reports have highlighted problems with selection of children for transfer. The purpose of this study is to characterize the burden of potentially avoidable transfer (PAT) and to estimate the medical and family-oriented costs associated with PAT.

METHODS

This study was a cohort study of all children treated in Iowa EDs between 2004 and 2013. PAT was defined as a child who was transferred and then either discharged from the receiving ED or admitted for ≤ 1 day, without having any separately billed procedures performed. Costs of care were estimated from 1) medical costs, 2) ambulance transfer, and 3) family costs (travel and lodging).

RESULTS

Over 10 years, 2,117,317 children were included (1% transferred to another hospital). Only 63% were transferred to a designated children's hospital, and PATs were identified in 39% of all transfers. PAT was associated with $909 in additional cost. The conditions most strongly associated with PAT were seizure (additional cost $1,138), fracture ($814), isolated traumatic brain injury without extra-axial bleeding ($1,455), respiratory infection ($556), and wheezing ($804). Few of these charges are attributable to nonmedical family costs ($21).

CONCLUSIONS

Potentially avoidable pediatric interhospital transfer is common and is responsible for significant healthcare-related costs. Future work should focus on improving selection of children who benefit from interhospital transfer for high-yield conditions, to reduce the costly and distressing burden that PAT places on rural patients and their families.

The effect of suspended sediment on fertilization success in the urchin Evechinus chloroticus: analysis of experimental data using hierarchical Bayesian methods

Terrestrial sediments are a significant stressor on coastal ecosystems, with both suspended and deposited sediment having adverse effects on aquatic organisms. However, information on the effect of suspended sediments on fertilization success for urchin species is lacking. Using sediment levels similar to those encountered in situ, a controlled experiment was conducted to test whether suspended sediment affects fertilization success in the urchin Evechinus chloroticus. Analyses used generalized linear mixed models (GLMMs) and hierarchical Bayesian (HB) regression. Both approaches showed a significant decrease in fertilization success with increased suspended sediment levels. Uncertainties in estimates were narrower for HB models, suggesting that this approach has advantages over GLMMs for sparse data problems sometimes encountered in laboratory experiments. Given future global change scenarios, this work is important for predicting the effects of stressors such as sedimentation that may ultimately impact marine populations.

Neural processes involved in directing attention

Neural processes associated with two aspects of visual-spatial attention were investigated with event-related potential (ERPs): those that direct spatial attention to a given point in space and those that modulate the processing of sensory input after attention has been directed. The subjects were 6- to 9-year-old children (51 boys and 35 girls). An arrow cue directed attention from the central to peripheral visual field; targets were then flashed in the attended or ignored visual field 600 msec after the cue. The directing of attention to the left vs. right visual field was associated with hemispheric differences in slow potentials prior to the presentation of the targets. The earliest potential, which started about 200 msec after the cue and was negative over the hemisphere contralateral to the direction of attention, was greatest over the parietal area and appeared to reflect processes directing attention per se. The last potential, which peaked 60 msec after the target and was positive over the hemisphere contralateral to the direction of attention, was greatest over the occipital-parietal region. It appeared to reflect the modulation of cortical excitability in the regions receiving input from the relevant and irrelevant visual fields. The effects of spatial attention on P1, N1, and P3 ERP components following the targets replicated previous results. Boys appeared more aroused (as indicated by CNVs) and reflected faster and greater selective processing (as indicated by reaction time, and N1-P1 latency and amplitude) than girls.

Spinal cord hypothermia without systemic hypothermia

BACKGROUND AND PURPOSE

Hypothermia has been shown to be beneficial in the setting of acute SCI. However, widespread use has been hindered by the need for systemic hypothermia as the vehicle for achieving spinal cord hypothermia. This study demonstrates that localized spinal cord hypothermia can be achieved via a percutaneous approach while maintaining systemic normothermia.

MATERIALS AND METHODS

Five Yucatan swine underwent catheterization of the subarachnoid space and infusion of room temperature, chilled, and iced PL solutions into the cervical spinal canal, with drainage from the lumbar canal. Thermocouples were placed within the spinal cord and in the subarachnoid space and recorded during infusions and recovery from hypothermia.

RESULTS

Results demonstrated that hypothermia as low as 16.8°C is feasible in the spinal cord with retention of systemic normothermia, with strong (r = 0.95) correlation between the spinal cord temperature and the CSF temperature. Degrees of cooling varied with flow rates and with infusate temperature.

CONCLUSIONS

While the data are preliminary in a small group of animals, the ability to rapidly create a wide range of controlled spinal cord hypothermia while preserving normal body temperature warrants wider exploration. The study also indicates that further investigation of the hypothesis that CSF temperature monitoring may be an acceptable surrogate for direct spinal cord temperature monitoring should be pursued.

Antioxidant therapies: a potential role in perinatal medicine

Pregnancies complicated by impaired placentation, acute severe reductions in oxygen supply to the fetus, or intrauterine infection are associated with oxidative stress to the mother and developing baby. Such oxidative stress is characterized as an upregulation in the production of oxidative or nitrative free radicals and a concomitant decrease in the availability of antioxidant species, thereby creating a state of fetoplacental oxidative imbalance. Recently, there has been a good deal of interest in the potential for the use of antioxidant therapies in the perinatal period to protect the fetus, particularly the developing brain, against oxidative stress in complications of pregnancy and birth. This review will examine why the immature brain is particularly susceptible to oxidative imbalance and will provide discussion on antioxidant treatments currently receiving attention in the adult and perinatal literature - allopurinol, melatonin, α-lipoic acid, and vitamins C and E. In addition, we aim to address the interaction between oxidative stress and the fetal inflammatory response, an interaction that may be vital when proposing antioxidant or other neuroprotective strategies.

Supplementation of fibrin gels with sodium chloride enhances physical properties and ensuing osteogenic response

Modifying the relative concentrations of fibrinogen and thrombin can control the physical properties of fibrin gels, while the viability of associated cells has been linked to the gel's final network structure. It was hypothesized that increasing the gel ionic strength during fabrication through supplementation with sodium chloride (NaCl) would provide an improved approach for tailoring the physical properties of fibrin gels and maintaining the viability and osteogenic potential of entrapped cells. Fibrin gels were formed by mixing fibrinogen, thrombin and calcium chloride with varying masses of NaCl (0-4.40% w/v), and the osteogenic potential of entrapped human mesenchymal stem cells (MSC) was examined over 14 days. Physical properties including gelation time, compressive modulus and fiber diameter were dependent upon NaCl content, with gels containing 2.60% NaCl possessing compressive moduli threefold higher than gels without NaCl. Alkaline phosphatase activity was highest for MSC entrapped in gels containing 2.15-2.60% NaCl after 14 days, and all gels exhibited increased calcium incorporation over the culture period. These data confirm that varying the salt concentration of the pre-gel solution can modulate the material properties of fibrin constructs without additional fibrinogen or thrombin, thereby offering a new approach for generating improved cell transplantation vehicles for use in bone tissue regeneration.

Risky business: Addressing the consequences of predicting violence

Despite major advances in the prediction of violence and risk management, risk evaluations are necessarily imperfect. This article focuses on the role of the evaluator in such assessments and addresses the consequences incurred by clinicians involved in conducting risk assessments. We discuss the risks of overpredicting and underpredicting violence with respect to how these risks can influence an evaluator's opinion. Then, we review how law and psychology inform the clinician's work. Finally, in response to the compelling tendency toward overprediction of violence, we propose a preliminary self-assessment guide as a method of examining influences on the evaluator in assessing violence risk.

Carbon dioxide clathrate in the martian ice cap

Measurements of the dissociation pressure of carbon dioxide hydrate show that this hydrate (CO(2) . 6H(2)O) is stable relative to solid CO(2) and water ice at temperatures above about 121 degrees K. Since this hydrate forms from finely divided ice and gaseous CO(2) in several hours at 150 degrees K, it is likely to be present in the martian ice cap. The ice cap can consist of water ice, water ice + CO(2) hydrate, or CO(2) hydrate + solid CO(2), but not water ice + solid CO(2).

Nonprotein amino acids from spark discharges and their comparison with the murchison meteorite amino acids

All the nonprotein amino acids found in the Murchison meteorite are products of the action of electric discharge on a mixture of methane, nitrogen, and water with traces of ammonia. These amino acids include alpha-amino-n-butyric acid, alpha-aminoisobutyric acid, norvaline, isovaline, pipecolic acid, beta-alanine, beta-amino-n-butyric acid, beta-aminoisobutyric acid, gamma-aminobutyric acid, sarcosine, N-ethylglycine, and N-methylalanine. In addition, norleucine, alloisoleucine, N-propylglycine, N-isopropylglycine, N-methyl-beta-alanine, N-ethyl-beta-alanine alpha,beta-diaminopropionic acid, isoserine, alpha,gamma-diaminobutyric acid, and alpha-hydroxy-gamma-aminobutyric acid are produced by the electric discharge, but have not been found in the meteorite.

Behavioral signs of schizoidia and schizotypy in the biological parents of social anhedonics

A community sample of 88 putative schizotypes (48 social anhedonics, 40 controls), aged 18 to 19 years, and their biological parents (42 mothers of social anhedonics, 37 mothers of controls; 24 fathers of social anhedonics, 20 fathers of controls) receive videotaped diagnostic evaluations that serve as the basis for ratings of behavioral signs of schizoidia and schizotypy. Proband social anhedonics exhibit more atypical interpersonal behaviors characteristic of schizoid and schizotypal personality disorders than controls. Mothers of social anhedonics display more atypical interpersonal behaviors characteristic of schizotypal personality disorder than mothers of controls. In contrast, clinical symptom ratings of schizotypy do not differentiate mothers of social anhedonics from mothers of controls. Meaningful, though not statistically significant, effects are observed for behavioral sign ratings in the smaller sample of fathers of social anhedonics. Results provide preliminary support for the familiality of atypical interpersonal behavior in social anhedonics.

Seasonal Variation and Bioactivity in the Leaf Oil of Liriodendron tulipifera Growing in Huntsville, Alabama

The seasonal variation in the chemical composition of the leaf essential oil of Liriodendron tulipifera has been analyzed by GC-MS. Two individual trees were sampled five times during the course of the growing season. Twenty components were identified in the leaf oils, which were dominated by sesquiterpene hydrocarbons, principally germacrene D and β-elemene, in the early part of the season (42-44% and 18-23%, respectively,) but monoterpene hydrocarbons, largely ( Z)-β-ocimene, dominated the later season leaf oils (40-60%). The leaf oils exhibited in-vitro antibacterial activity against Bacillus cereus and Staphylococcus aureus as well as cytotoxic activity on MDA-MB-231 and Hs 578T human breast tumor cells.

Seasonal variation and bioactivity in the leaf oil of Liriodendron tulipifera growing in Huntsville, Alabama

The seasonal variation in the chemical composition of the leaf essential oil of Liriodendron tulipifera has been analyzed by GC-MS. Two individual trees were sampled five times during the course of the growing season. Twenty components were identified in the leaf oils, which were dominated by sesquiterpene hydrocarbons, principally germacrene D and beta-elemene, in the early part of the season (42-44% and 18-23%, respectively,) but monoterpene hydrocarbons, largely (Z)-beta-ocimene, dominated the later season leaf oils (40-60%). The leaf oils exhibited in-vitro antibacterial activity against Bacillus cereus and Staphylococcus aureus as well as cytotoxic activity on MDA-MB-231 and Hs 578T human breast tumor cells.

The Denver Aerosol Sources and Health (DASH) Study: Overview and Early Findings

Improved understanding of the sources of air pollution that are most harmful could aid in developing more effective measures for protecting human health. The Denver Aerosol Sources and Health (DASH) study was designed to identify the sources of ambient fine particulate matter (PM(2.5)) that are most responsible for the adverse health effects of short-term exposure to PM (2.5). Daily 24-hour PM(2.5) sampling began in July 2002 at a residential monitoring site in Denver, Colorado, using both Teflon and quartz filter samplers. Sampling is planned to continue through 2008. Chemical speciation is being carried out for mass, inorganic ionic compounds (sulfate, nitrate and ammonium), and carbonaceous components, including elemental carbon, organic carbon, temperature-resolved organic carbon fractions and a large array of organic compounds. In addition, water soluble metals were measured daily for 12 months in 2003. A receptor-based source apportionment approach utilizing positive matrix factorization (PMF) will be used to identify PM (2.5) source contributions for each 24-hour period. Based on a preliminary assessment using synthetic data, the proposed source apportionment should be able to identify many important sources on a daily basis, including secondary ammonium nitrate and ammonium sulfate, diesel vehicle exhaust, road dust, wood combustion and vegetative debris. Meat cooking, gasoline vehicle exhaust and natural gas combustion were more challenging for PMF to accurately identify due to high detection limits for certain organic molecular marker compounds. Measurements of these compounds are being improved and supplemented with additional organic molecular marker compounds. The health study will investigate associations between daily source contributions and an array of health endpoints, including daily mortality and hospitalizations and measures of asthma control in asthmatic children. Findings from the DASH study, in addition to being of interest to policymakers, by identifying harmful PM(2.5) sources may provide insights into mechanisms of PM effect.

Chemical composition of the leaf essential oil of Casimiroa edulis La Llave & Lex. (Rutaceae) from Monteverde, Costa Rica

The leaf essential oil of Casimiroa edulis (Rutaceae), collected from Monteverde, Costa Rica, has been obtained by hydrodistillation and analyzed by GC-MS. The leaf oil was dominated by sesquiterpene hydrocarbons, predominately germacrene D (16-22%) and (E)-caryophyllene (16-17%), consistent with the traditional use of this plant as a sedative, sleep inducer and hypotensive.

The danger of weight loss in the elderly

Aging is generally accompanied by weight loss made up of both fat mass and fat-free mass. As more people, including elderly, are overweight or obese, weight loss is recommended to improve health. Health risks are decreased in overweight children and adults by dieting and exercise, but the health benefits of weight loss in elderly, particularly by calorie restriction, are uncertain. Rapid unintentional weight loss in elderly is usually indicative of underlying disease and accelerates the muscle loss which normally occurs with aging. Intentional weight loss, even when excess fat mass is targeted also includes accelerated muscle loss which has been shown in older persons to correlate negatively with functional capacity for independent living. Sarcopenic obesity, the coexistence of diminished lean mass and increased fat mass, characterizes a population particularly at risk for functional impairment since both sarcopenia (relative deficiency of skeletal muscle mass and strength) and obesity have been shown to predict disability. However, indices of overweight and obesity such as body mass index (BMI) do not correlate as strongly with adverse health outcomes such as cardiovascular disease in elderly as compared to younger individuals. Further, weight loss and low BMI in older persons are associated with mortality in some studies. On the other hand, studies have shown improvement in risk factors after weight loss in overweight/obese elderly. The recent focus on pro-inflammatory factors related to adiposity suggest that fat loss could ameliorate some catabolic conditions of aging since some cytokines may directly impact muscle protein synthesis and breakdown. Simply decreasing weight may also ease mechanical burden on weak joints and muscle, thus improving mobility. However, until a strategy is proven whereby further loss of muscle mass can be prevented, weight loss by caloric restriction in individuals with sarcopenic obesity should likely be avoided.

Hippocampal activation in adults with mild cognitive impairment predicts subsequent cognitive decline

OBJECTIVE

To use functional MRI (fMRI) to investigate whether hippocampal activation during a memory task can predict cognitive decline in individuals with mild cognitive impairment (MCI).

METHODS

25 older individuals with MCI performed a visual scene encoding task during fMRI scanning, and were followed clinically for at least 4 years after scanning. A hypothesis driven analysis of fMRI data was performed. First, fMRI data were analysed at the group level to identify the regions of the hippocampal formation that were engaged by this memory task. Parameter estimates of each subject's memory related hippocampal activation (% signal change) were extracted and were analysed with a linear regression model to determine whether hippocampal activation predicted the degree or rate of cognitive decline, as measured by change in Clinical Dementia Rating Sum-of-Boxes (CDR-SB).

RESULTS

Over 5.9 (1.2) years of follow-up after scanning, subjects varied widely in degree and rate of cognitive decline (change in CDR-SB ranged from 0 to 6, and the rate ranged from 0 to 1 CDR-SB unit/year). Greater hippocampal activation predicted greater degree and rate of subsequent cognitive decline (p<0.05). This finding was present even after controlling for baseline degree of impairment (CDR-SB), age, education and hippocampal volume, as well as gender and apolipoprotein E status. In addition, an exploratory whole brain analysis produced convergent results, demonstrating that the hippocampal formation was the only brain region where activation predicted cognitive decline.

CONCLUSIONS

In individuals with MCI, greater memory task related hippocampal activation is predictive of a greater degree and rate of cognitive decline subsequent to scanning. fMRI may provide a physiological imaging biomarker useful for identifying the subgroup of MCI individuals at highest risk of cognitive decline for potential inclusion in disease modifying clinical trials.

Prefrontal-hippocampal-fusiform activity during encoding predicts intraindividual differences in free recall ability: an event-related functional-anatomic MRI study

The ability to spontaneously recall recently learned information is a fundamental mnemonic activity of daily life, but has received little study using functional neuroimaging. We developed a functional MRI (fMRI) paradigm to study regional brain activity during encoding that predicts free recall. In this event-related fMRI study, ten lists of fourteen pictures of common objects were shown to healthy young individuals and regional brain activity during encoding was analyzed based on subsequent free recall performance. Free recall of items was predicted by activity during encoding in hippocampal, fusiform, and inferior prefrontal cortical regions. Within-subject variance in free recall performance for the ten lists was predicted by a linear combination of condition-specific inferior prefrontal, hippocampal, and fusiform activity. Recall performance was better for lists in which prefrontal activity was greater for all items of the list and hippocampal and fusiform activity were greater specifically for items that were recalled from the list. Thus, the activity of medial temporal, fusiform, and prefrontal brain regions during the learning of new information is important for the subsequent free recall of this information. These fronto-temporal brain regions act together as a large-scale memory-related network, the components of which make distinct yet interacting contributions during encoding that predict subsequent successful free recall performance.

Nek3 kinase regulates prolactin-mediated cytoskeletal reorganization and motility of breast cancer cells

Prolactin (PRL) stimulates the cytoskeletal re-organization and motility of breast cancer cells. During PRL receptor signaling, Vav2 becomes phosphorylated and activated, an event regulated by the serine/threonine kinase Nek3. Given the regulatory role of Vav2, the function of Nek3 in PRL-mediated motility and invasion was examined. Overexpression of Nek3 in Chinese hamster ovary transfectants potentiated cytoskeletal re-organization in response to PRL. In contrast, downregulation of Nek3 expression by small-interfering RNA (siRNA) attenuated PRL-mediated cytoskeletal reorganization, activation of GTPase Rac1, cell migration and invasion of T47D cells. In addition, PRL stimulation induced an interaction between Nek3 and paxillin and significantly increased paxillin serine phosphorylation, whereas Nek3 siRNA-transfected cells showed a marked reduction in paxillin phosphorylation. Analysis of breast tissue microarrays also demonstrated a significant up-regulation of Nek3 expression in malignant versus normal specimens. These data suggest that Nek3 contributes to PRL-mediated breast cancer motility through mechanisms involving Rac1 activation and paxillin phosphorylation.

Particle size distributions and concentrations of airborne endotoxin using novel collection methods in homes during the winter and summer seasons

A comparison study of novel collection methods for airborne bacteria and endotoxin was performed in an environmentally controlled chamber and in pilot-field studies. Airborne particulate matter was collected in swirling liquid impingers, air-monitoring filter cassettes, and with a micro-orifice uniform deposit impactor (MOUDI) to evaluate aerodynamic particle size distributions. Environmentally controlled chamber studies showed that impingers and MOUDI recovered significantly more airborne bacteria than filter cassettes, whereas collection methods for airborne endotoxin were not significantly different. In addition, total airborne bacteria and endotoxin concentrations were measured indoors and outdoors at three homes in Boulder, CO during winter and summer seasons. Indoor concentrations collected with the three different samplers were significantly different for airborne endotoxin, but not for airborne bacteria. Total airborne bacteria indoors and outdoors significantly varied with seasons. Outdoor airborne endotoxin significantly varied with season; no seasonal variation was seen for indoor airborne endotoxin. Indoor and outdoor levels were not significantly different for both airborne bacteria and endotoxin. The largest proportion of endotoxin was associated with airborne particulate matter <1 microm.

PRACTICAL IMPLICATIONS

This study compared sampling methods for airborne endotoxin, a potent and nonspecific immune system stimulant which can induce negative health responses. The data from this study showed that swirling liquid impingers and the micro-orifice uniform deposit impactor (MOUDI) recovered significantly more airborne endotoxin than the more widely adapted method of collecting airborne endotoxin on membrane filters, when collection methods were applied in realistic settings (homes). The MOUDI measured the particle size distribution of airborne endotoxin, which can be useful for determining endotoxin respiratory toxicity and its health effects.

Chronic fetal hypoxia increases activin A concentrations in the late-pregnant sheep

OBJECTIVE

To determine whether activin A concentrations are altered in chronic fetal hypoxemia and intrauterine fetal growth restriction (IUGR).

DESIGN

In vivo animal experimental model.

SETTING

Department of Physiology, Monash University.

POPULATION

Chronically catherised fetal sheep in late pregnancy.

METHODS

Chronic fetal hypoxia and IUGR were experimentally induced by single umbilical artery ligation (SUAL) in catheterised fetal sheep. Maternal and fetal blood samples and amniotic fluid (AF) samples were collected during surgery and thereafter on alternate days, until the time of delivery for analyte measurement. Fetal blood gas parameters were measured daily.

MAIN OUTCOME MEASURES

Plasma and AF was used to analyse activin A, prostaglandin E2 (PGE2) and cortisol and fetal blood gas analysis was undertaken in whole blood.

RESULTS

SUAL produced asymmetric IUGR and non-acidaemic chronic fetal hypoxia and resulted in preterm labour (129 [3] days). AF activin A concentrations were 10-fold higher in the SUAL group than in controls whereas levels in the fetal and maternal circulations were similar between groups.

CONCLUSIONS

SUAL-induced IUGR and fetal hypoxaemia increases AF activin A. This may be an important adaptive or protective response to IUGR.

Effect of graded hypoxia on activin A, prostaglandin E2 and cortisol levels in the late-pregnant sheep

The aim of the present study was to determine whether activin A concentrations are dependent on feto–placental oxygen availability and to investigate the temporal relationship of activin A with prostaglandin (PG) E2 and cortisol. Nine fetal sheep (six hypoxic and three control) were instrumented and catheterised at 0.8 gestation. Reduced uterine blood flow was used to achieve three levels of hypoxia (mild = fetal SaO2 40–50%; moderate = fetal SaO2 30–40%; severe = fetal SaO2 20–30%), for 4 h on 3 consecutive days. Activin A, PGE2 and cortisol levels were determined in maternal and fetal blood and amniotic fluid. Moderate and severe hypoxia produced a significant (P < 0.05) increase in fetal plasma activin A concentrations. The amniotic fluid activin A concentrations were 15-fold higher than those in the fetal circulation, but were unchanged by hypoxia. The fetal PGE2 response reflected the degree of hypoxia over the 3 days, with moderate and severe hypoxia producing a significant (P < 0.05) increase in PGE2 concentrations. Fetal plasma cortisol concentrations were increased (P < 0.05) during all levels of hypoxia. Fetal arterial activin A was increased in response to moderate and severe hypoxia, but levels were not maintained over the hypoxic period. The increases in activin A and cortisol concentrations preceded the increase in PGE2.

Detection of optical asymmetry in amino acids by gas chromatography for extraterrestrial space exploration: results of a new soil processing scheme with breadboard instrumentation

The life-detection experiments of the Viking spacecraft are of an active biology type that will attempt to elicit metabolic responses from soil samples. Because bioresponses may be difficult to stimulate, it is desirable also to devise a purely chemical life-detection experiment. The unique chemical property of living systems on which such an experiment could be based is the optical activity of the amino acids that compose its protein. We have devised a new soil processing scheme which has been laboratory tested and for which we have built semi-automated breadboard instrumentation. The system involves the operations of heating, filtering, evaporation, conversion of the isolated amino acids to volatile diastereomers, injection onto a gas chromatographic column, and detection using a flame ionization detector. The breadboard form of the soil processing scheme and instrumentation has been successfully end-to-end tested.

Clinical rib fractures: are follow-up chest X-rays a waste of resources?

Rib fractures (RFs) are estimated to be present in 10 per cent of all traumatic injuries. However, up to 50 per cent of all fractures go undetected on the screening chest X-ray (CXR). The purpose of this study was to identify the incidence of clinical (CRFs) and objective rib fractures (ORFs) as well as to examine the utility of the routine follow-up CXR with regard to patient recovery and healthcare cost. We identified patients sustaining RF in addition to other traumatic injuries with an Injury Severity Score (ISS) < or = 15 and RF as the primary pathology. Five hundred fifty-two patients sustained blunt thoracic trauma with resultant RF. Two hundred nine patients had RFs and an ISS < or = 15. The average ISS was 8. Follow-up films illustrated that 93 per cent of CRFs had resolution of any pathology, 4 per cent had persistent X-ray findings, and 4 per cent were lost to follow-up. Ultimately 93 per cent of patients with CRF were able to resume daily activities without disability and 3 per cent incurred lifestyle changes at home or work, which was significantly better than those with ORFs (P < 0.05). Follow-up films produced no change in clinical management and cost approximately $2000/year. The prognosis for CRFs is excellent if treatment consists of appropriate pain management and pulmonary rehabilitation. We do not advocate routine follow-up CXRs in addition to physical examination for the evaluation of CRFs unless clinical deterioration is evident.

Indoor pollutant levels from the use of unvented natural gas fireplaces in Boulder, Colorado

High CO and NO2 concentrations have been documented in homes with unvented combustion appliances, such as natural gas fireplaces. In addition, polycyclic aromatic hydrocarbons (PAH) are emitted from incomplete natural gas combustion. The acute health risks of CO and NO2 exposure have been well established for the general population and for certain high-risk groups, including infants, the elderly, and people with heart disease or asthma. Health effects from PAH exposure are less well known, but may include increased risk of cancer. We monitored CO emissions during the operation of unvented natural gas fireplaces in two residences in Boulder, CO, at various times between 1997 and 2000. During 1999, we expanded our tests to include measurements of NO2 and PAH. Results show significant pollutant accumulation indoors when the fireplaces were used for extended periods of time. In one case, CO concentrations greater than 100 ppm accumulated in under 2 hr of operation; a person at rest exposed for 10 hr to this environment would get a mild case of CO poisoning with an estimated 10% carboxyhemoglobin level. Appreciable NO2 concentrations were also detected, with a 4-hr time average reaching 0.36 ppm. Similar time-average total PAH concentrations reached 35 ng/m3. The results of this study provide preliminary insights to potential indoor air quality problems in homes operating unvented natural gas fireplaces in Boulder.

Prevalence of CVD risk factors and impact of a two-year education program for premenopausal women

Indicators of cardiovascular disease risk in premenopausal women before, during, and after a 2-year educational intervention measured prevalence of risk and program effectiveness. Women (n = 277) were assigned to either treatment/education (n = 174) or control (n = 103) group. Many had at least one cardiovascular disease risk factor: high BMI (n = 123); high-fat diet (n = 160); and/or high body fat percent (n = 136). The treatment group was significant for change in calories from fat (P <.01). This study shows that premenopausal women have cardiovascular disease risks that should be addressed, and that nutrition education can successfully change dietary behavior.

The origin of life--did it occur at high temperatures?

A high-temperature origin of life has been proposed, largely for the reason that the hyperthermophiles are claimed to be the last common ancestor of modern organisms. Even if they are the oldest extant organisms, which is in dispute, their existence can say nothing about the temperatures of the origin of life, the RNA world, and organisms preceding the hyperthermophiles. There is no geological evidence for the physical setting of the origin of life because there are no unmetamorphosed rocks from that period. Prebiotic chemistry points to a low-temperature origin because most biochemicals decompose rather rapidly at temperatures of 100 degrees C (e.g., half-lives are 73 min for ribose, 21 days for cytosine, and 204 days for adenine). Hyperthermophiles may appear at the base of some phylogenetic trees because they outcompeted the mesophiles when they adapted to lower temperatures, possibly due to enhanced production of heat-shock proteins.

Template-directed synthesis of oligonucleotides under eutectic conditions

One of the most important sets of model prebiotic experiments consists of reactions that synthesize complementary oligonucleotides from preformed templates under nonenzymatic conditions. Most of these experiments are conducted at 4 degrees C using 0.01-0.1 M concentrations of activated nucleotide monomer and template (monomer equivalent). In an attempt to extend the conditions under which this type of reaction can occur, we have concentrated the reactants by freezing at -18 degrees C, which is close to the NaCl-H2O eutectic at -21 degrees C. The results from this set of experiments suggest that successful syntheses can occur with poly(C) concentrations as low at 5 x 10(-4) M and 2MeImpG concentrations at 10(-3) M. It was also anticipated that this mechanism might allow the previously unsuccessful poly(A)-directed synthesis of oligo(U)s to occur. However, no template effect was seen with the poly(A) and ImpU system. The failure of these conditions to allow template-directed synthesis of oligo(U)s supports the previously proposed idea that pyrimidines may not have been part of the earliest genetic material. Because of the low concentrations of monomer and template that would be expected from prebiotic syntheses, this lower temperature could be considered a more plausible geologic setting for template-directed synthesis than the standard reaction conditions.

Current status of the prebiotic synthesis of small molecules

The prebiotic synthesis of small molecules has been accomplished using various simulated atmospheres with CH4, N2, and NH3, H2O being the most effective, but H2, CO, N2, H2O and H2, CO2, N2, H2O also give good yields of organic compounds provided H2/CO > 1 and H2/CO2 > 2. The spark discharge is a very effective source of energy in such experiments, because it is a good source of HCN. Ultraviolet light would also have been important on the primitive earth. Almost all prebiotic amino acids are made by the hydrolysis of an amino nitrile formed from an aldehyde, NH3 and HCN (Strecker synthesis). There are reasonable prebiotic syntheses worked out for the twenty amino acids that occur in proteins, with the exception of lysine, arginine and histidine. The purines are derived from the polymerization of HCN, and the precursor of the pyrimidines is cyanoacetylene. The sugars (including ribose), would have been formed from the base catalyzed polymerization of formaldehyde. There is no good prebiotic synthesis of straight chain fatty acids. Of the vitamin coenzymes, only nicotinic acid has been synthesized under prebiotic conditions. Many of the molecules that are produced in these simulated primitive earth experiments are found in a group of meteorites that contain organic compounds, called the carbonaceous chondrites. Since such prebiotic syntheses took place on the parent body of the carbonaceous chondrites, generally thought to be an asteroid, it is plausible, but not proved, that such syntheses took place on the primitive earth, and that the first living organisms were formed out of these compounds.

Racemization and the origin of optically active organic compounds in living organisms

The organic compounds synthesized in prebiotic experiments are racemic mixtures. A number of proposals have been offered to explain how asymmetric organic compounds formed on the Earth before life arose, with the influence of chiral weak nuclear interactions being the most frequent proposal. This and other proposed asymmetric syntheses give only sight enantiomeric excess and any slight excess will be degraded by racemization. This applies particularly to amino acids where half-lives of 10(5)-10(6) years are to be expected at temperatures characteristic of the Earth's surface. Since the generation of chiral molecules could not have been a significant process under geological conditions, the origins of this asymmetry must have occurred at the time of the origin of life or shortly thereafter. It is possible that the compounds in the first living organisms were prochiral rather than chiral; this is unlikely for amino acids, but it is possible for the monomers of RNA-like molecules.