What is the impact of a pre-hospital geriatrician led telephone 'Silver Triage' for older people living with frailty?

PURPOSE

Most older people are conveyed to hospital via ambulance, therefore presenting a focus to reduce hospitalisation. North Central London has introduced 'Silver Triage', a pre-hospital telephone support scheme where geriatricians support the London Ambulance Service with clinical decision-making.

METHODS

Data from the first 14 months was analysed descriptively.

RESULTS

There have been 452 Silver Triage cases (November 2021 to January 2023). 80% resulted in a decision to not convey. The mode clinical frailty scale (CFS) was 6. CFS did not influence conveyance rates. Prior to triage, paramedics thought hospitalisation was not required in 44% of cases (n = 72/165). All paramedics surveyed (n = 176) would use the service again. Most (66%, n = 108/164) felt they learnt something and 16% (n = 27/164) reported it changed their decision-making process.

CONCLUSION

Silver Triage has the potential to improve the care of older people by preventing unnecessary hospitalisation and has been well received by paramedics.

An in silico pipeline for subject-specific hemodynamics analysis in liver surgery planning

The progresses in fast simulations of the hepatic flow in subject-specific vascular tree have created new toolkits for pre-surgical planning. The aim of this short communication is to introduce a computational pipeline that integrates several recently developed in silico liver models and algorithms. Firstly, a semi-automatic segmentation pipeline is used to digitise hepatic vessels. Then, a constructive constraint optimisation (CCO) algorithm is used to extend the digitised vascular tree, and also to compute the blood pressure and flow velocity in the tree. Couinaud segments are simulated from the diffusion zones of the portal venous tree. The constructed surgical planning model is then deployed cross-platform for use in various scenarios.

Meeting the multiscale challenge: representing physiology processes over ApiNATOMY circuits using bond graphs

We introduce, and provide examples of, the application of the bond graph formalism to explicitly represent biophysical processes between and within modular biological compartments in ApiNATOMY. In particular, we focus on modelling scenarios from acid-base physiology to link distinct process modalities as bond graphs over an ApiNATOMY circuit of multiscale compartments. The embedding of bond graphs onto ApiNATOMY compartments provides a semantically and mathematically explicit basis for the coherent representation, integration and visualisation of multiscale physiology processes together with the compartmental topology of those biological structures that convey these processes.

Managing Older Patients Safely in the Time Critical Environment of an Emergency Department

Demand for emergency department (ED) services is increasing worldwide. The fastest growth in ED presentations is by patients aged ≥65 years, currently representing 18% of all attendances. Older patients present with more complex clinical conditions and multiple co-morbidities. This means they are likely to spend more time in ED, are more likely to be admitted to hospital, and are more likely to re-attend. The Safe Elderly Emergency Discharge (SEED) project aims to determine whether current models of emergency care ensure safe discharge and facilitate optimal health outcomes for older patients; and develop a tailored evidence-based care framework applicable to Australian and international settings. Risk screening for unsafe discharge will be conducted on patients aged ≥65 years discharged home from ED. Patients will be followed for 6 months post-ED presentation to monitor health outcomes and map their care journey. Demographic, clinical, and functional characteristics will be collected. The primary outcome is unsafe discharge, defined as unplanned re-presentation/admission within 30 days of the index presentation. Secondary outcomes include unplanned ED re-presentation/hospital admission within 6 months; patient experience; change in functional status; functional decline; health service utilisation; and death within 6 months. The effectiveness of the ED discharge risk screening tools for predicting unsafe discharge will be evaluated at 30 days and 6 months. SEED will determine the risk factors for unplanned ED re-presentation/hospital admission at 30 days for patients aged ≥65 years presenting to ED; which will inform the development of an evidence-based older patient care framework for EDs.

Can an Intervention with Testosterone and Nutritional Supplement Improve the Frailty Level of Under-Nourished Older People?

OBJECTIVE

To examine whether a testosterone and a high calorie nutritional supplement intervention can reduce frailty scores in undernourished older people using multiple frailty tools.

DESIGN

Randomized controlled trial.

SETTING/PARTICIPANTS

53 community-dwelling, undernourished men and women aged >65 years from South Australia, Victoria and New South Wales.

INTERVENTION

Intervention group received oral testosterone undecanoate and a high calorie supplement (2108-2416 kJ/day) whereas the control group received placebo testosterone and low calorie supplement (142-191 kJ/day).

MEASUREMENTS

Frailty was operationalized using three frailty indices (FI-lab, FI-self-report, FI-combined) and the frailty phenotype.

RESULTS

There were no significant differences in changes in frailty scores at either 6 or 12 months follow up between the two treatment groups for all scales. Participants at the intervention group were 4.8 times more likely to improve their FI-combined score at both time points compared to the placebo group.

CONCLUSION

A testosterone and a high calorie nutritional supplement intervention did not improve the frailty levels of under-nourished older people. Even so, when frailty was measured using a frailty index combining self-reported and lab data we found that participants who received the intervention were more likely to show persistent improvement in their frailty scores.

Requirements for the formal representation of pathophysiology mechanisms by clinicians

Knowledge of multiscale mechanisms in pathophysiology is the bedrock of clinical practice. If quantitative methods, predicting patient-specific behaviour of these pathophysiology mechanisms, are to be brought to bear on clinical decision-making, the Human Physiome community and Clinical community must share a common computational blueprint for pathophysiology mechanisms. A number of obstacles stand in the way of this sharing-not least the technical and operational challenges that must be overcome to ensure that (i) the explicit biological meanings of the Physiome's quantitative methods to represent mechanisms are open to articulation, verification and study by clinicians, and that (ii) clinicians are given the tools and training to explicitly express disease manifestations in direct contribution to modelling. To this end, the Physiome and Clinical communities must co-develop a common computational toolkit, based on this blueprint, to bridge the representation of knowledge of pathophysiology mechanisms (a) that is implicitly depicted in electronic health records and the literature, with (b) that found in mathematical models explicitly describing mechanisms. In particular, this paper makes use of a step-wise description of a specific disease mechanism as a means to elicit the requirements of representing pathophysiological meaning explicitly. The computational blueprint developed from these requirements addresses the Clinical community goals to (i) organize and manage healthcare resources in terms of relevant disease-related knowledge of mechanisms and (ii) train the next generation of physicians in the application of quantitative methods relevant to their research and practice.

The Randomized Control Trial of the Effects of Testosterone and a Nutritional Supplement On Hospital Admissions in Undernourished, Community Dwelling, Older People

OBJECTIVE

In a pilot single centre study we found that treatment of undernourished older, community dwelling people for one year with oral testosterone (placebo-controlled) and a nutritional supplement (no control) was associated with a significant reduction in hospitalizations. A larger, multicentre study was conducted to investigate further this potentially important finding.

DESIGN

One year, randomized, placebo-controlled, multi-centre, double-blind, trial.

SETTING

Community.

PARTICIPANTS

53 undernourished men and women aged 65 years and older.

INTERVENTION

Oral testosterone undecanoate (40 mg/day women, 160 mg/day men) and high energy oral nutritional supplement (2108-2416 kJ/day) or placebo medication and low energy (142-191 kJ/day) "placebo" oral nutritional supplementation.

MEASUREMENTS

Hospital admissions, falls and other variables were assessed.

RESULTS

53 subjects were recruited (64% male and mean age 77 years), which was substantially less than planned. Sixteen subjects (30%) were admitted to hospital at least once, with a total of 29 admissions. Eight subjects (32%) in the placebo arm were admitted to hospital, whilst in the intervention group also there were eight (29%) subjects admitted to hospital during the study period. There was no difference in the number of hospitalisations (P = 0.842), length of hospitalization (P=0.645) or quality of life [mental health P=0.195 and physical health P=0.451) between the treatment arms.

CONCLUSIONS

In undernourished older people, treatment with testosterone and a nutritional supplementation did not reduce the number and length of hospitalisations or improve quality of life.

Post-mortem prediction of primal and selected retail cut weights of New Zealand lamb from carcass and animal characteristics

Post-mortem measurements (cold weight, grade and external carcass linear dimensions) as well as live animal data (age, breed, sex) were used to predict ovine primal and retail cut weights for 792 lamb carcases. Significant levels of variance could be explained using these predictors. The predictive power of those measurements on primal and retail cut weights was studied by using the results from principal component analysis and the absolute value of the t-statistics of the linear regression model. High prediction accuracy for primal cut weight was achieved (adjusted R(2) up to 0.95), as well as moderate accuracy for key retail cut weight: tenderloins (adj-R(2)=0.60), loin (adj-R(2)=0.62), French rack (adj-R(2)=0.76) and rump (adj-R(2)=0.75). The carcass cold weight had the best predictive power, with the accuracy increasing by around 10% after including the next three most significant variables.

RESPOND--A patient-centred programme to prevent secondary falls in older people presenting to the emergency department with a fall: protocol for a multicentre randomised controlled trial

INTRODUCTION

Participation in falls prevention activities by older people following presentation to the emergency department (ED) with a fall is suboptimal. This randomised controlled trial (RCT) will test the RESPOND programme, an intervention designed to improve older persons' participation in falls prevention activities through delivery of patient-centred education and behaviour change strategies.

DESIGN AND SETTING

A RCT at two tertiary referral EDs in Melbourne and Perth, Australia.

PARTICIPANTS

528 community-dwelling people aged 60-90 years presenting to the ED with a fall and discharged home will be recruited. People who require an interpreter or hands-on assistance to walk; live in residential aged care or >50 km from the trial hospital; have terminal illness, cognitive impairment, documented aggressive behaviour or a history of psychosis; are receiving palliative care or are unable to use a telephone will be excluded.

METHODS

Participants will be randomly allocated to the RESPOND intervention or standard care control group. RESPOND incorporates (1) a home-based risk factor assessment; (2) education, coaching, goal setting and follow-up telephone support for management of one or more of four risk factors with evidence of effective interventions and (3) healthcare provider communication and community linkage delivered over 6 months. Primary outcomes are falls and fall injuries per person-year.

DISCUSSION

RESPOND builds on prior falls prevention learnings and aims to help individuals make guided decisions about how they will manage their falls risk. Patient-centred models have been successfully trialled in chronic and cardiovascular disease; however, evidence to support this approach in falls prevention is limited.

TRIAL REGISTRATION NUMBER

The protocol for this study is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12614000336684).

High Resolution 3D Imaging of Lung Tissue using Structured Light Microscopy

A 3D reconstruction microscope has been built in order to investigate the structural details of the airway tree and the vasculature of mouse lungs. The objective is to create an anatomically correct finite element model of a mouse lung in order to validate results from simulations obtained using an existing model of the human lung. The 3D reconstruction microscope consists of a fully automated scanning stage, a vibratome and a structured light optical microscope. Structured light microscopy is a new approach to optical sectioning of tissue and offers several advantages over confocal microscopy.

Modelling biological modularity with CellML

In recent years advances in the construction of mathematical models of biological systems have yielded an array of valuable constructs. The authors seek to provide a 'leading practice' method for implementing modularised kinetic mass-action models in order to obtain a number of advantages in model construction, validation and derived insights. The authors advocate the consideration of 'accounting cycles' or 'chains' to define 'functional' components and the separate consideration of 'messenger' components for mobile or diffusive molecular species. From a conceptual modularisation the authors illustrate, with an example drawn from signal transduction, a component-based formulation in the model exchange format cellular modelling markup language (CellML) 1.1 - demonstrating loose coupling between functionally-focused reusable components. Finally, the authors discuss the dilemmas associated with modelling protein-to-protein interactions, and the vision for using future CellML enhancements to resolve potential duplications when combining independently developed models.

An audit of corneal abrasion management following the introduction of local guidelines in an accident and emergency department

BACKGROUND AND OBJECTIVES

Corneal abrasions are a common presentation to accident and emergency (A&E) departments. Patients can be treated and discharged by A&E staff without the need for an ophthalmologist's attention; complicated cases, however, should be recognised and referred. Inexperience and limited training in ophthalmology may lead to suboptimal patient care and inappropriate use of ophthalmology outpatient clinics. Issues of poor documentation may also arise. The purpose of this audit was to assess the effect of guidelines on the management of corneal abrasion by A&E staff.

METHODS

A retrospective case note audit was performed to assess current management of corneal abrasions. Guidelines for management of corneal abrasions were formulated following a literature search and collaboration between A&E and ophthalmology staff. A prospective case note audit was undertaken to assess management after introduction of the guidelines.

RESULTS

A total of 51 cases were audited before the introduction of the guidelines and 57 cases after. Following the introduction of the guidelines documentation of visual acuity increased to 93% and specific enquiry into contact lens wear rose from 35.3% to 71.9%. A&E staff stopped giving out local anaesthetic eye drops. The follow up profile also improved; appropriate patient discharges increased by 40% whereas inappropriate referrals to eye clinic dropped by 75%. More patients were given abrasion advice (a 101% increase).

CONCLUSIONS

A&E staff members are capable of managing corneal abrasions if they are given guidance and some training. This audit identified shortcomings in current management and showed that guidelines can significantly improve clinical practice.

GENE EXPRESSION OF STRETCH-ACTIVATED CHANNELS AND MECHANOELECTRIC FEEDBACK IN THE HEART

1. Mechanoelectric feedback (MEF) in the heart is the process by which mechanical forces on the myocardium can change its electrical properties. Mechanoelectric feedback has been demonstrated in many animal models, ranging from isolated cells, through isolated hearts to whole animals. In humans, MEF has been demonstrated directly in both the atria and the ventricles. It seems likely that MEF provides either the trigger or the substrate for some types of clinically important arrhythmias. 2. Mechanoelectric feedback may arise because of the presence of stretch-sensitive (or mechano-sensitive) ion channels in the cell membrane of the cardiac myocytes. Two types have been demonstrated: (i) a non-specific cation channel (stretch-activated channel (SAC); conductance of approximately 25 pS); and (ii) a potassium channel with a conductance of approximately 100 pS. The gene coding for the SAC has not yet been identified. The gene for the potassium channel is likely to be TREK, a member of the tandem pore potassium channel gene family. We have recorded stretch-sensitive potassium channels in rat isolated myocytes that have the properties of TREK channels expressed in heterologous systems. 3. It has been shown that TREK mRNA is expressed heterogeneously in the rat ventricular wall, with 17-fold more expression in endocardial compared with epicardial cells. This difference is reflected in the TREK currents recorded from endocardial and epicardial cells using whole-cell patch-clamp techniques, although the difference in current density was less pronounced (approximately threefold). Consistent with this, we show here that when the ventricle is stretched by inflation of an intraventricular balloon in a Langendorff perfused rat isolated heart, action potential shortening was more pronounced in the endocardium (30% shortening at 40 mmHg) compared with that in the epicardium (10% shortening at the same pressure). 4. Computer models of the mechanics of the (pig) heart show pronounced spatial variations in strain in the myocardium with large transmural differences (in the left ventricle in particular) and also large differences between the base and apex of the ventricle. 5. The importance of MEF and the non-homogeneous gene expression and strain distribution for arrhythmias is discussed.

Perception of tap water risks and quality: a structural equation model approach

The present study aims to test a model of tap water risk and quality perception. A questionnaire was designed and applied to a convenience sample of 499 people in Portugal. The model includes aesthetic variables (colour, odour, and flavour), contextual indicators and risk perception. Other variables were also considered, including external information, trust in water companies, familiarity with tap water, and past water-related health problems. A behavioural outcome--drinking tap water--was also studied. Due to multivariate non-normality (Mardia's Coefficient (G2,P) = 460.3), the AGLS estimator was used for the structural equation model (SEM). A triangulation approach with multivariate regression analysis was used to explain the use of tap water to drink and to propose a more holistic model that could not be tested using SEM. Results show that perceived water quality is largely influenced by flavour. Other factors, such as perceived risk and contextual indicators, also have a role but their relevance is relatively weak. On the other hand, risk perception seems to be mainly a result of external information, past health problems, and water colour. Finally, the use of tap water to drink at home can be moderately explained and depends mostly on the ability to use alternatives (i.e. bottled water), tap water taste, and perceived risk.

A national outbreak of multi-resistant Salmonella enterica serovar Typhimurium definitive phage type (DT) 104 associated with consumption of lettuce

Between 1 August and 15 September 2000, 361 cases of Salmonella enterica serotype Typhimurium definitive phage type (DT) 104, resistant to ampicillin, chloramphenicol, streptomycin, sulphonamides, spectinomycin and tetracycline (R-type ACSSuSpT), were identified in England and Wales residents. Molecular typing of 258 isolates of S. Typhimurium DT104 R-type ACSSuSpT showed that, although isolates were indistinguishable by pulsed-field gel electrophoresis, 67% (174/258) were characterized by a particular plasmid profile. A statistically significant association between illness and consumption of lettuce away from home was demonstrated (OR = 7.28; 95% CI=2.25-23.57; P=0.0006) in an unmatched case-control study. Environmental investigations revealed that a number of food outlets implicated in the outbreak had common suppliers of salad vegetables. No implicated foods were available for microbiological testing. An environmental audit of three farms that might have supplied salad vegetables to the implicated outlets did not reveal any unsafe agricultural practices. The complexity of the food supply chain and the lack of identifying markers on salad stuffs made tracking salad vegetables back to their origin extremely difficult in most instances. This has implications for public health since food hazard warnings and product withdrawal are contingent on accurate identification of the suspect product.

Laboratory ascertainment of Cryptosporidium and local authority policies for investigating sporadic cases of cryptosporidiosis in two regions of the United Kingdom

To discover laboratory ascertainment and reporting practice for cases of cryptosporidiosis in two health authority regions, we surveyed laboratories serving Wales and the North West of England for faecal screening policies and methods for detection of Cryptosporidium. Forty-eight of the 49 laboratories responded, of which 39 (81%) screen all stool specimens from symptomatic individuals for Cryptosporidium and 9 (19%) screen selected specimens. Although laboratory screening is more complete than has been reported in other regions, we identified discrepancies where patient age was used as a selection criterion, and we make suggestions to amend this. Forty-two (88%) responding laboratories report confirmed cases to the regional Communicable Disease Surveillance Centre (CDSC) and 45 (94%) report to the local authority environmental health department. We also surveyed local authorities in both regions for policy and practice concerning the investigation of reported cases of cryptosporidiosis in the same regions. All 59 local authorities responded, of which 57 (97%) investigate cases by completion of an exposure questionnaire as well as providing advice on the prevention of spread of infection. Variation in case ascertainment may influence perception of incidence, clusters and outbreaks of cases of cryptosporidiosis.

Teratogenicity of a mutagenised Rift Valley fever virus (MVP 12) in sheep

A 5-fluorouracil mutagenised Rift Valley fever virus strain, which was shown to be attenuated and immunogenic in cattle and sheep, was evaluated for its ability to cause teratogenic effects in pregnant sheep. A group of 50 sheep at various stages of pregnancy was inoculated with the virus and the pregnancies followed to term. There were two abortions and 14% of the lambs produced by vaccinated ewes showed teratogenic effects, the most prevalent being spinal hypoplasia, hydranencephaly, brachygnathia inferior and arthrygryposis. The foetal malformations of the central nervous and musculo-skeletal systems were mostly consistent with those observed in sheep vaccinated with the attenuated Smithburn RVF strain. The teratogenic effects of MVP12 were not seen in previous experiments by other authors as immunisation of sheep took place in the second to third trimester of pregnancy, when the foetal brain tissue has completed most of its cell division.

A monovalent attenuated serotype 2 bluetongue virus vaccine confers homologous protection in sheep

An outbreak of bluetongue caused by bluetongue virus serotype 2 virus in certain Mediterranean countries during 1999/2000, presented an opportunity to produce a monovalent type 2 vaccine. Since no data have been published previously on the protection conferred by the current live attenuated bluetongue vaccine strains used in the polyvalent vaccine, a challenge experiment was performed to determine the degree of homologous protection induced by the type 2 vaccine strain. The standard vaccine dose of 5 x 10(4) pfu of vaccine conferred 99.7% protection against clinical disease and no viraemia was detected in the vaccinates.

Possible undetected outbreaks of cryptosporidiosis in areas of the north west of England supplied by an unfiltered surface water source

We report a ten-year retrospective analysis of laboratory reports of cryptosporidium infection in the North West of England. Weekly report data from six health authorities known to have been affected by outbreaks associated with a single supply were compared with data from other health authorities in the North West. Following graphical representation of report rates, it would appear that outbreaks in the six health authorities were considerably more common than the average recorded in the national outbreak surveillance system.

Surveillance of antimicrobial resistance--what, how and whither?

OBJECTIVE

To express the views of a working party held to consider antibiotic resistance surveillance systems, their strengths and weaknesses, and their current and future applications.

METHODS

The participants, all of whom were experienced in this field, discussed the development of surveillance systems in relation to the increasing prevalence of resistance to antibacterial agents and the current interest in surveillance systems shown by many official bodies, in both the human and veterinary fields. The problems inherent in surveillance systems were considered together with the applications of different systems.

RESULTS

The properties of good antibiotic resistance surveillance systems were defined. Surveillance systems vary widely from those with a narrow base, focusing on few organisms in one disease area, to those covering many diseases, many organisms (including normal flora) and many compounds. Whatever their design, they should be able to detect significant differences and shifts in susceptibility to various antibacterial agents, and the information derived from them should reach as many interested parties as possible in a timely manner. In using this information to decide strategies, criteria for action need to be determined by pragmatic consensus. Funding remains a major problem, with few large studies being supported by official bodies in spite of their professed enthusiasm for surveillance. In consequence, many current systems are funded by the pharmaceutical industry and are of necessity restricted in their focus.

CONCLUSIONS

Antibiotic resistance surveillance studies should and can be well planned and well executed. Many current systems suffer from well-recognized but uncorrected biases. Consortium funding will be necessary for large schemes to be successful. There is no "ideal" surveillance system.

Lumpy skin disease in southern Africa: a review of the disease and aspects of control

This article reviews some of the important aspects of lumpy skin disease (LSD) that may impact on its successful control. A resurgence of the disease in the last decade has highlighted some constraints of the Neethling strain vaccine, but there is no evidence of vaccine breakdowns owing to the presence of heterologous field strains. More research is needed on epidemiology and transmission of LSD in South Africa to formulate control measures.

Genome-directed primers for selective labeling of bacterial transcripts for DNA microarray analysis

DNA microarrays have the ability to analyze the expression of thousands of the same set of genes under at least two different experimental conditions. However, DNA microarrays require substantial amounts of RNA to generate the probes, especially when bacterial RNA is used for hybridization (50 microg of bacterial total RNA contains approximately 2 microg of mRNA). We have developed a computer-based algorithm for prediction of the minimal number of primers to specifically anneal to all genes in a given genome. The algorithm predicts, for example, that 37 oligonucleotides should prime all genes in the Mycobacterium tuberculosis genome. We tested the usefulness of the genome-directed primers (GDPs) in comparison to random primers for gene expression profiling using DNA microarrays. Both types of primers were used to generate fluorescent-labeled probes and to hybridize to an array of 960 mycobacterial genes. Compared to random-primer probes, the GDP probes were more sensitive and more specific, especially when mammalian RNA samples were spiked with mycobacterial RNA. The GDPs were used for gene expression profiling of mycobacterial cultures grown to early log or stationary growth phases. This approach could be useful for accurate genome-wide expression analysis, especially for in vivo gene expression profiling, as well as directed amplification of sequenced genomes.

High-yield production of a human therapeutic protein in tobacco chloroplasts

Transgenic plants have become attractive systems for production of human therapeutic proteins because of the reduced risk of mammalian viral contaminants, the ability to do large scale-up at low cost, and the low maintenance requirements. Here we report a feasibility study for production of a human therapeutic protein through transplastomic transformation technology, which has the additional advantage of increased biological containment by apparent elimination of the transmission of transgenes through pollen. We show that chloroplasts can express a secretory protein, human somatotropin, in a soluble, biologically active, disulfide-bonded form. High concentrations of recombinant protein accumulation are observed (>7% total soluble protein), more than 300-fold higher than a similar gene expressed using a nuclear transgenic approach. The plastid-expressed somatotropin is nearly devoid of complex post-translational modifications, effectively increasing the amount of usable recombinant protein. We also describe approaches to obtain a somatotropin with a non-methionine N terminus, similar to the native human protein. The results indicate that chloroplasts are a highly efficient vehicle for the potential production of pharmaceutical proteins in plants.

Developmental activation of the capability to undergo checkpoint-induced apoptosis in the early zebrafish embryo

In this study, we demonstrate the developmental activation, in the zebrafish embryo, of a surveillance mechanism which triggers apoptosis to remove damaged cells. We determine the time course of activation of this mechanism by exposing embryos to camptothecin, an agent which specifically inhibits topoisomerase I within the DNA replication complex and which, as a consequence of this inhibition, also produces strand breaks in the genomic DNA. In response to an early (pre-gastrula) treatment with camptothecin, apoptosis is induced at a time corresponding approximately to mid-gastrula stage in controls. This apoptotic response to a block of DNA replication can also be induced by early (pre-MBT) treatment with the DNA synthesis inhibitors hydroxyurea and aphidicolin. After camptothecin treatment, a high proportion of cells in two of the embryo's three mitotic domains (the enveloping and deep cell layers), but not in the remaining domain (the yolk syncytial layer), undergoes apoptosis in a cell-autonomous fashion. The first step in this response is an arrest of the proliferation of all deep- and enveloping-layer cells. These cells continue to increase in nuclear volume and to synthesize DNA. Eventually they become apoptotic, by a stereotypic pathway which involves cell membrane blebbing, "margination" and fragmentation of nuclei, and cleavage of the genomic DNA to produce a nucleosomal ladder. Fragmentation of nuclei can be blocked by the caspase-1,4,5 inhibitor Ac-YVAD-CHO, but not by the caspase-2,3,7[, 1] inhibitor Ac-DEVD-CHO. This suggests a functional requirement for caspase-4 or caspase-5 in the apoptotic response to camptothecin. Recently, Xenopus has been shown to display a developmental activation of the capability for stress- or damaged-induced apoptosis at early gastrula stage. En masse, our experiments suggest that the apoptotic responses in zebrafish and Xenopus are fundamentally similar. Thus, as for mammals, embryos of the lower vertebrates exhibit the activation of surveillance mechanisms, early in development, to produce the selective apoptosis of damaged cells.

Murine Gcm1 gene is expressed in a subset of placental trophoblast cells

The gcm gene of Drosophila melanogaster encodes a transcription factor that is an important component in cell fate specification within the nervous system. In the absence of a functional gcm gene, progenitor cells differentiate into neurons, whereas when the gene is ectopically expressed the cells produce excess glial cells at the expense of neuronal differentiation. Recent searches of databases have uncovered high sequence similarity between the Drosophila gem gene and an anonymous human placental cDNA clone (Altschuller et al., 1996; this communication). Here we report the molecular organization of the murine Gcm1, its spatio-temporal pattern of expression in developing placenta, and its map position at E1-E3 on murine chromosome 9. The murine gene is composed of at least 6 exons. The promoter region contains an "initiation sequence" and is GC rich, characteristics of the promoters of several transcription factors. The mRNA has a modest 5'UTR (ca. 200 bases) but an extensive 3' UTR (ca. 2 kb). Northern blot and mRNA in situ hybridization studies showed that Gcm1 expression was readily detectable only in the placenta. It began at embryonic day 7.5 within trophoblast cells of the chorion and continued to about embryonic day 17.5 within a subset of labyrinthine trophoblast cells. Comparison with other transcription factors revealed that Gcm1 expression defines a unique subset of trophoblast cells.

Stretch-induced changes in heart rate and rhythm: clinical observations, experiments and mathematical models

Clinical and research data indicate that active and passive changes in the mechanical environment of the heart are capable of influencing both the initiation and the spread of cardiac excitation via pathways that are intrinsic to the heart. This direction of the cross-talk between cardiac electrical and mechanical activity is referred to as mechano-electric feedback (MEF). MEF is thought to be involved in the adjustment of heart rate to changes in mechanical load and would help to explain the precise beat-to-beat regulation of cardiac performance as it occurs even in the recently transplanted (and, thus, denervated) heart. Furthermore, there is clinical evidence that MEF may be involved in mechanical initiation of arrhythmias and fibrillation, as well as in the re-setting of disturbed heart rhythm by 'mechanical' first aid procedures. This review will outline the clinical relevance of cardiac MEF, describe cellular correlates to the responses observed in situ, and discuss the role that quantitative mathematical models may play in identifying the involvement of cardiac MEF in the regulation of heart rate and rhythm.

Organochlorine contamination in bald eagle eggs and nestlings from the Canadian Great Lakes

Unhatched eggs and plasma samples from prefledged bald eagles (Haliaeetus leucocephalus) from a recovering population in the Canadian Great Lakes Basin were contaminated with organochlorine compounds at levels comparable to those reported for eagle populations in several areas of the United States. PCBs were among the most commonly detected contaminants and occurred at high concentrations in plasma. Plasma PCB concentrations in Lake Erie nestlings were significantly higher than in chicks from Lake Nipigon (0.130 and 0.047 mg/kg wet weight, respectively). Blood levels of mirex were higher in nestlings from Lake Superior compared to those from Lake Erie (0.0012 and 0.0006 mg/kg wet weight, respectively). Migration routes and over-winter locations of avian prey that constitute a part of the bald eagle chick's diet are likely to contribute to these spatial contaminant patterns in plasma. Atmospheric deposition and a cold condensation effect for chlordane compounds may have produced higher levels of these compounds in plasma samples from Lake Superior compared to samples from Lake Erie (0.020 and 0.008 mg/kg wet weight, respectively). Levels of DDE in plasma were generally low, ranging in concentration from 0.02 mg/kg wet weight for lakes Erie and Nipigon to 0.06 mg/kg wet weight for Lake Huron. Concentrations of organochlorines in eaglet plasma remained relatively stable between 1990 and 1996; no significant trends associated with year of sampling were detected. The data from Lake Erie showed no correlation between productivity and plasma levels of PCBs or DDE during this time period. There were no indications that the concentrations of contaminants detected were adversely affecting productivity in Canadian Great Lakes bald eagle populations. Residue levels in eggs from Lake Erie eagle territories were equally or more contaminated than eggs from other highly contaminated environments in the United States such as the Great Lakes and Columbia River estuary. Concentrations of DDE and PCBs in Lake Erie eggs declined significantly between 1974 and 1994. Although dieldrin and chlordane levels showed a similar decline, these relationships were not statistically significant. Mirex concentrations were relatively stable. Eggs from Lake of the Woods were significantly less contaminated than those from Lake Erie (PCBs: 3 and 84 mg/kg wet weight, respectively; DDE: 3 and 24 mg/kg wet weight, respectively). Reproductive success (number of young produced/active nest) remained constant between 1982 and 1996 and productivity is sufficient to maintain an increasing population. The number of active nests has increased during this period indicating that the population is expanding and might be expected to do so until suitable habitat becomes limiting. Reductions in organochlorine levels, reintroduction efforts, immigration from other populations, and changes in habitat quality have likely contributed to the observed growth in the number of breeding pairs.

The efficacy of an experimental oil-adjuvanted encephalomyocarditis vaccine in elephants, mice and pigs

An oil-adjuvanted inactivated encephalomyocarditis (EMC) vaccine was developed to protect a wild population of elephants against a natural outbreak of disease. The experimental vaccine was initially tested for efficacy by challenging mice and pigs. Mice showed protection against challenge and pigs developed high antibody levels. Since both vaccinated and control pigs failed to develop clinical disease, apparently due to the low virulence of the strain in this species, protection in pigs could not be evaluated. Vaccinated elephants developed high antibody titers which protected all vaccinates from a challenge roughly two months post-vaccination, whereas controls developed fatal or sub-clinical myocarditis. This is the first report of an inactivated EMC vaccine inducing high antibody titers in domestic and wild animal species. Due to the potency of this vaccine and the acceptability of the oil adjuvant used, it has potential for use in animals in zoological collections as well as in the pig industry.