Clinical features and natural history of RASopathy-associated hypertrophic cardiomyopathy in children

Background

The RASopathies are a group of genetic disorders caused by germline mutations in genes encoding components of the RAS/MAPK signalling pathway and frequently associated with hypertrophic cardiomyopathy (HCM). The clinical features and outcomes of RASopathy-related HCM are incompletely understood and most published studies are limited by relatively small numbers and incomplete clinical characterisation.

Purpose

To describe the clinical features outcomes in a large, single-centre cohort of patients with RASopathy-associated HCM diagnosed <18 years.

Methods

Data from 105 patients [68 (64.8%) males] diagnosed in childhood with RASopathy-associated HCM at a single specialist centre between 1985 and 2020 were retrospectively analysed.

Results

The RASopathy diagnosis was Noonan syndrome in 69 patients (65.7%); NSML in 10 (9.5%); CFC in 6 (5.7%); Costello in 5 (4.8%) and 15 patients (14.2%) had another Noonan-like variant. 72 patients (68.6%) had a pathogenic/likely pathogenic variant in a RAS-MAPK gene, most commonly PTPN11 [n=25 (34.7%)], followed by RAF 1 [n=13 (18.1%)]. 100 patients (95.2%) were probands, 9 (8.6%) had family history of cardiomyopathy and 2 (1.9%) family history of sudden cardiac death (SCD). 52 (49.5%) had concomitant congenital heart defects (CHD) [ASD 13 (25%), VSD 6 (11.5%), PDA 1 (1.9%), >1 CHD 32 (61.5%)]. 29 (27.6%) had symptoms at baseline assessment and 56 (53.3%) were on cardiac medication. The distribution of left ventricular hypertrophy (LVH) was concentric in 47 (44.7%); 32 (30.5%) had asymmetric septal hypertrophy (ASH), and undocumented in 25 patients (23.8%). 45 patients (42.9%) had biventricular hypertrophy (BVH). Resting left ventricular outflow tract obstruction (LVOTO) was present in 39 (37.1%) with haemodynamically significant LVOTO (≥50mmHg) in 23 (21.9%). Resting right ventricular outflow tract obstruction (RVOTO) was present in 21 (20%). Over a median follow up time of 6 years, 19 patients (18.1%) died [1 (5.3%) SCD; 2 (10.5%) due to Heart Failure-related death; 1 (5.3%) due to another CVS cause; 5 (26.3%) due to a non-CVS cause and for 10 (52.6%) cause of death was unknown]. Incidence rate of death was calculated at 2.7 deaths per 100 person-years. Surgical septal myectomy was performed in 9 patients (8.6%) and 3 (2.9%) underwent cardiac transplantation. 14 patients (13.3%) suffered arrhythmic events [atrial tachycardia 6 (42.9%), Non-Sustained Ventricular Tachycardia 4 (3.8%), and Ventricular Tachycardia/Ventricular Fibrillation 4 (3.8%)].

Conclusion

To our knowledge, this is the largest cohort of RASopathy-associated HCM. The findings show a heterogeneous clinical presentation with a high prevalence of morbidity and mortality. Further work is needed to determine predictors of outcome in this population.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Onassis Foundation

National Hazards Vulnerability and the Remediation, Restoration and Revitalization of Contaminated Sites-1. Superfund

Natural hazards can be prominent and powerful mechanisms that impact the remediation and restoration of contaminated sites and the revitalization of communities associated with these sites. The potential for hazardous material releases following a natural disaster can exacerbate the impact of contaminated sites by causing the release of toxic or hazardous materials and inhibiting the restoration of the site as well as altering the long-term sustainable revitalization of adjacent communities. Disaster-related hazardous releases, particularly in population-dense areas, can create problems as difficult as the original site clean-up. Similarly, exposure of contaminated sites to natural hazards can enhance the probability of future issues associated with the site. This manuscript addresses the co-occurrence of 12 natural hazards (singly and in combination) and individual Superfund sites.

Gulf of Mexico Coastal County Resilience to Natural Hazards

Using a Cumulative Resilience Screening Index (CRSI) that was developed to represent resilience to natural hazards at multiple scales for the United States, the U.S. coastal counties of the Gulf of Mexico region of the United States are compared for resilience for these types of natural hazards. The assessment compares the domains, indicators and metrics of CRSI, addressing environmental, economic and societal aspects of resilience to natural hazards at county scales. The index was applied at the county scale and aggregated to represent states and two regions of the U.S. Gulf of Mexico (GOM) coastline. Assessments showed county-level resilience in all GOM counties was low, generally below the U.S. average. Comparisons showed higher levels of resilience in the western GOM region while select counties Louisiana, Mississippi and Alabama exhibited lowest resilience (<2.0) to natural hazards. Some coastal counties in Florida and Texas represented the highest levels of resilience seen along the GOM coast. Much of this increased resilience appears to be due to higher levels of governance and broader levels of social, economic and ecological services.

Renewed: Protocol for a randomised controlled trial of a digital intervention to support quality of life in cancer survivors

INTRODUCTION

Low quality of life is common in cancer survivors. Increasing physical activity, improving diet, supporting psychological well-being and weight loss can improve quality of life in several cancers and may limit relapse. The aim of the randomised controlled trial outlined in this protocol is to examine whether a digital intervention (Renewed), with or without human support, can improve quality of life in cancer survivors. Renewed provides support for increasing physical activity, managing difficult emotions, eating a healthier diet and weight management.

METHODS AND ANALYSIS

A randomised controlled trial is being conducted comparing usual care, access to Renewed or access to Renewed with brief human support. Cancer survivors who have had colorectal, breast or prostate cancer will be identified and invited through general practice searches and mail-outs. Participants are asked to complete baseline measures immediately after screening and will then be randomised to a study group; this is all completed on the Renewed website. The primary outcome is quality of life measured by the European Organization for Research and Treatment of Cancer QLQ-c30. Secondary outcomes include anxiety and depression, fear of cancer recurrence, general well-being, enablement and items relating to costs for a health economics analysis. Process measures include perceptions of human support, intervention usage and satisfaction, and adherence to behavioural changes. Qualitative process evaluations will be conducted with patients and healthcare staff providing support.

ETHICS AND DISSEMINATION

The trial has been approved by the NHS Research Ethics Committee (Reference 18/NW/0013). The results of this trial will be published in peer-reviewed journals and through conference presentations.

TRIAL REGISTRATION NUMBER

ISRCTN96374224; Pre-results.

Regionalizing resilience to acute meteorological events: Comparison of regions in the U.S

Using a Climate Resilience Screening Index (CRSI) that was developed to represent resilience to acute weather events at multiple scales for the United States, nine regions of the United States are compared for resilience for these types of natural hazards. The comparison examines the domains, indicators and metrics of CRSI addressing environmental, economic and societal aspects of resilience to acute climate events. The index uses indicators and metrics that assess ecosystem, economic, governance and social services at county scales. The index was applied at the county scale and aggregated to represent select regions of the United States. Comparisons showed higher levels of resilience in the Northeast and West while counties in the Southeast and South-Central regions exhibited lower resilience to acute climate events.

EPA Leadership on Science, Innovation, and Decision Support Tools for Addressing Current and Future Challenges

When the U.S. Environmental Protection Agency (EPA) was established nearly 50 years ago, the nation faced serious threats to its air, land, and water, which in turn impacted human health. These threats were effectively addressed by the creation of EPA (in 1970) and many subsequent landmark environmental legislations which in turn significantly reduced threats to the Nation's environment and public health. A key element of historic legislation is research aimed at dealing with current and future problems. Today we face national and global challenges that go beyond classic media-specific (air, land, water) environmental legislation and require an integrated paradigm of action and engagement based on (1) innovation based on science and technology, (2) stakeholder engagement and collaboration, and (3) public education and support. This three-pronged approach recognizes that current environmental problems, include social as well as physical and environmental factors, are best addressed through collaborative problem solving, the application of innovation in science and technology, and multiple stakeholder engagement. To achieve that goal, EPA's Office of Research and Development (ORD) is working directly with states and local communities to develop and apply a suite of accessible decision support tools (DST) that aim to improve environmental conditions, protect human health, enhance economic opportunity, and advance a resilient and sustainability society. This paper showcases joint EPA and state actions to develop tools and approaches that not only meet current environmental and public health challenges, but do so in a way that advances sustainable, healthy, and resilient communities well into the future. EPA's future plans should build on current work but aim to effectively respond to growing external pressures. Growing pressures from megatrends are a major challenge for the new Administration and for cities and states across the country. The recent hurricanes hitting Texas and the Gulf Coast, part of the increase in extreme weather events, make it clear that building resilient infrastructure is a crucial step to sustainability.

Cumulative incidence and risk factors for limber tail in the Dogslife labrador retriever cohort

Limber tail is a condition that typically affects larger working breeds causing tail limpness and pain, resolving without veterinary intervention. It is poorly understood and the disease burden has not been well characterised. Data collected from owners of the Dogslife cohort of Labrador Retrievers have been used to describe incidents and a case-control study was undertaken to elucidate risk factors with 38 cases and 86 controls. The cumulative incidence of unexplained tail limpness was 9.7 per cent. Swimming is not a necessary precursor for limber tail, but it is a risk factor (OR=4.7) and working dogs were more susceptible than non-working dogs (OR=5.1). Higher latitudes were shown to be a risk factor for developing the condition and the case dogs were more related to each other than might be expected by chance. This suggests that dogs may have an underlying genetic predisposition to developing the condition. This study is the first, large-scale investigation of limber tail and the findings reveal an unexpectedly high illness burden. Anecdotally, accepted risk factors have been confirmed and the extent of their impact has been quantified. Identifying latitude and a potential underlying genetic predisposition suggests avenues for future work on this painful and distressing condition.

Antioxidant food supplements and obesity-related inflammation

The obesity prevalence is growing worldwide and largely responsible for the increased incidence of cardiovascular disease, the most common cause of death in the western world. Excessive food intake along with insufficient physical exercise is the basic impetus for this development. The obese state is commonly associated with an increase in leptin levels and chronic immune-mediated inflammation. Despite high leptin levels, the leptin response, normally associated with satiety and satiation, seems to be impaired and individuals continue to consume calorie-rich food. Antioxidant food additives such as sodium sulphite, sodium benzoate and curcumin were shown to suppress the leptin release in lipopolysaccharide- treated murine adipocytes. Based on this, we hypothesize that the insufficient leptin release, caused by excessive consumption of food additives, may lead to a reduced exposure of the central nervous system to leptin and ultimately propagate obesity. On the other hand, leptin has been shown to favor Th1-type activity, which ultimately decreases tryptophan levels. Tryptophan derivatives, serotonin and melatonin, induce satiety/satiation through several mechanisms. In this context, the antioxidant suppression of leptin release and Th1-type activity is beneficial to increase serotonin and melatonin levels. The molecules in the mechanism described in this review are highly integrated in the reward system, and have been implicated in the addiction behavior of obesity. Based on these facts, the involvement of antioxidant food supplements in the mechanisms of the reward-deficiency syndrome which perpetuates obesity will be discussed.

Techniques for minimizing the effects of PCR inhibitors in the chytridiomycosis assay

Chytridiomycosis is an amphibian disease of global conservation concern that is caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd). Since the discovery of Bd in 1998, several methods have been used for detection of Bd; among these polymerase chain reaction (PCR) from skin swabs is accepted as the best method due to its noninvasiveness, high sensitivity and ease of use. However, PCR is not without problems - to be successful, this technique is dependent upon the presence of nondegraded DNA template and reaction contents that are free from inhibitors. Here, we report on an investigation of several techniques aimed at improving the reliability of the Bd PCR assay by minimizing the effects of humic acid (HA), a potent PCR inhibitor. We compared the effectiveness of four DNA extraction kits (DNeasy, QIAamp DNA Stool, PowerLyzer Power Soil and PrepMan Ultra) and four PCR methods (Amplitaq Gold, bovine serum albumin, PowerClean DNA Clean-up and inhibitor resistant Taq Polymerase). The results of this and previous studies indicate that chytridiomycosis studies that use PCR methods for disease detection may be significantly underestimating the occurrence of Bd. Our results suggest that to minimize the inhibitory effects of HA, DNeasy should be used for sample DNA extraction and Amplitaq Gold with bovine serum albumin should be used for the Bd PCR assay. We also outline protocols tested, show the results of our methods comparisons and discuss the pros and cons of each method.

Divergence in parental care, habitat selection and larval life history between two species of Peruvian poison frogs: an experimental analysis

Changes in the nature of the ecological resources exploited by a species can lead to the evolution of novel suites of behaviours. We identified a case in which the transition from large pool use to the use of very small breeding pools in neotropical poison frogs (family Dendrobatidae) is associated with the evolution of a suite of behaviours, including biparental care (from uniparental care) and social monogamy (from promiscuity). We manipulated breeding pool size in order to demonstrate experimentally that breeding habitat selection strategy has evolved in concert with changes in parental care and mating system. We also manipulated intra- and interspecific larval interactions to demonstrate that larval adaptation to the use of very small pools for breeding affected the evolution of larval competition and cannibalism. Our results illustrate the intimate connection between breeding pool ecology, parental care and mating strategies in Peruvian poison frogs.

The value of screening in siblings of patients with abdominal aortic aneurysm

OBJECTIVES

This study aimed to determine the incidence of abdominal aortic aneurysm (AAA) in a large group of siblings of Australian AAA patients to determine if screening in this group is justified.

METHODS

1254 siblings of 400 index AAA patients were identified and offered aortic ultrasound screening. An age and sex matched control group was recruited from patients having abdominal CT scans for non-vascular indications. AAA was defined by an infrarenal aortic diameter of > or =3 cm or a ratio of the infrarenal to suprarenal aortic diameter of > or =2.0. A ratio of 1.0-1.5 was considered normal, and a ratio of >1.5 to <2.0 was considered ectatic. Aortic enlargement was defined as ectasia or aneurysm.

RESULTS

276 (22%) siblings could be contacted and agreed to screening or had previously been diagnosed with AAA. All 118 controls had normal diameter aortas. 55/276 siblings had previously been diagnosed with AAA. The remaining 221 siblings underwent ultrasound screening. Overall, 30% (84/276) had enlarged aortas (5% ectasia, 25% aneurysmal); 43% of male siblings (64/150) and 16% of females siblings (20/126). The incidence was 45% in brothers of female index patients, 42% in brothers of male patients, 23% in sisters of female patients, and 14% in sisters of male index patients.

CONCLUSIONS

The overall incidence of aortic enlargement of 30% found in this study warrants a targeted screening approach with ultrasound for all siblings of patients with AAA. A similar targeted approach for screening of the children of AAA patients would also seem advisable.

Molecular systematics and phylogeography of Amazonian poison frogs of the genus Dendrobates

The study of Amazonian biodiversity requires detailed knowledge of the phylogenetic relationships of closely related taxa distributed across Amazonia. The Amazonian poison frogs of the genus Dendrobates have undergone many taxonomic revisions, but the phylogenetic relationships within this group remain poorly understood. Most previous classifications were based on morphology and skin toxin analyses, with limited use of DNA sequence data. Using mtDNA sequence data from four gene regions (cytochrome b, cytochrome oxidase I, 16S rRNA, and 12S rRNA), we present a molecular phylogenetic analysis of the evolutionary relationships within a representative group of Amazonian Dendrobates. We use the resulting phylogenetic hypothesis to investigate different biogeographic hypotheses concerning genetic divergence and species diversity in Amazonia. The results of the analysis support the presence of ancient paleogeographic barriers to gene flow between eastern and western Amazonia, and indicate substantial genetic divergence between species found in the northern and southern regions of western Amazonia.

Intragenomic conflict and cancer

Intragenomic conflict occurs when some elements within the genome produce effects that enhance their own probability of replication or transmission at the expense of other elements within the same genome. Here it is proposed that mutations involved in intragenomic conflict are particularly likely to be co-opted by evolving lineages of cancer cells, and hence should be associated with the occurrence of cancer. We discuss several types of intragenomic conflict that are associated with various forms of cancer.

Molecular phylogenetic evidence for a mimetic radiation in Peruvian poison frogs supports a Müllerian mimicry hypothesis

Examples of Müllerian mimicry, in which resemblance between unpalatable species confers mutual benefit, are rare in vertebrates. Strong comparative evidence for mimicry is found when the colour and pattern of a single species closely resemble several different model species simultaneously in different geographical regions. Todemonstrate this, it is necessary to provide compelling evidence that the putative mimics do, in fact, form a monophyletic group. We present molecular phylogenetic evidence that the poison frog Dendrobates imitator mimics three different poison frogs in different geographical regions in Peru. DNA sequences from four different mitochondrial gene regions in putative members of a single species are analysed using parsimony, maximum-likelihood and neighbour-joining methods. The resulting hypotheses of phylogenetic relationships demonstrate that the different populations of D.imitator form a monophyletic group. To our knowledge, these results provide the first evidence for a Müllerian mimetic radiation in amphibians in which a single species mimics different sympatric species in different geographical regions.

The lysophospholipids sphingosine-1-phosphate and lysophosphatidic acid enhance survival during hypoxia in neonatal rat cardiac myocytes

The lysophospholipids sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA) stimulate cellular proliferation and affect numerous cellular functions by signaling through G protein-coupled endothelial differentiation gene-encoded (Edg) receptors. S1P and LPA also act as survival factors in many cell types, but have not previously been studied in cardiac myocytes. We incubated neonatal rat cardiac myocytes either in room air/1% CO2 (normoxia) or in an atmosphere of 99% N2/1%CO2 (hypoxia) at 37 degrees C for 18-20 h in the absence of glucose. Cell viability was measured using a calcein ester green fluorescence assay. Under normoxic conditions 88.7+/-1.0% of the cells were viable after 18-20 h. Severe hypoxia reduced viability to 61.3+/-4.3% (n=6, P<0.05). In myocytes preincubated with either 10 microM S1P or 1 microM LPA for 2 h, the effects of severe hypoxia on cell viability were prevented resulting in survival equivalent to normoxia. Neither the protein kinase C inhibitor chelethyrine (1 microM) nor the mitochondrial K(ATP) channel antagonist 5-hydroxydecanoic acid, (5-HD, 100 microM) had any effect on myocyte survival during severe hypoxia, but both agents completely abolished the ability of S1P to rescue cardiac myocytes from hypoxic cell death. We also tested the effects of dimethylsphingosine (DMS), which inhibits sphingosine kinase synthesis of S1P. Incubation of neonatal rat cardiac myocytes with 10 microM DMS for 2 h in the presence of serum resulted in 25-30% cell death during 18-20 h of normoxia. DMS-induced cell death was prevented by concurrent preincubation with either S1P or GM-1, a ganglioside that activates sphingosine kinase to increase intracellular levels of S1P. We conclude that both S1P and LPA are cardioprotective for hypoxic neonatal rat ventricular myocytes. S1P acts through cellular membrane receptors by signaling mechanisms involving protein kinase C and mitochondrial K(ATP) channels. Both endogenous and exogenously applied S1P are effective in preventing cell death induced by inhibition of sphingosine kinase.

The evolution of coloration and toxicity in the poison frog family (Dendrobatidae)

The poison frogs (family Dendrobatidae) are terrestrial anuran amphibians displaying a wide range of coloration and toxicity. These frogs generally have been considered to be aposematic, but relatively little research has been carried out to test the predictions of this hypothesis. Here we use a comparative approach to test one prediction of the hypothesis of aposematism: that coloration will evolve in tandem with toxicity. Recently, we developed a phylogenetic hypothesis of the evolutionary relationships among representative species of poison frogs, using sequences from three regions of mitochondrial DNA. In our analysis, we use that DNA-based phylogeny and comparative analysis of independent contrasts to investigate the correlation between coloration and toxicity in the poison frog family (Dendrobatidae). Information on the toxicity of different species was obtained from the literature. Two different measures of the brightness and extent of coloration were used. (i) Twenty-four human observers were asked to rank different photos of each different species in the analysis in terms of contrast to a leaf-littered background. (ii) Color photos of each species were scanned into a computer and a computer program was used to obtain a measure of the contrast of the colors of each species relative to a leaf-littered background. Comparative analyses of the results were carried out with two different models of character evolution: gradual change, with branch lengths proportional to the amount of genetic change, and punctuational change, with all change being associated with speciation events. Comparative analysis using either method or model indicated a significant correlation between the evolution of toxicity and coloration across this family. These results are consistent with the hypothesis that coloration in this group is aposematic.

Iron, infection and the evolutionary ecology of heart disease

Levels of iron intake and stored iron have been implicated as risk factors for coronary heart disease. More recently, considerable interest has centered on the role of a variety of infectious pathogens, particulary bacterial pathogens, in the development of artherosclerosis and heart disease. The mechanism whereby elevated iron levels increase the risk of coronary heart disease is not well understood. Here it is proposed that the influence of iron levels on the persistence, pervasiveness and intensity of bacterial infections may play an important role in the development of coronary heart disease.

A phase II study to evaluate the combination of fludarabine, mitoxantrone and dexamethasone (FMD) in patients with follicular lymphoma

BACKGROUND

'Molecular response' is being investigated as a therapeutic goal in follicular lymphoma (FL). High response rates in FL with the fludarabine combination 'FMD' have been associated with 'molecular remission'. A phase II study of FMD in FL was therefore conducted.

PATIENTS AND METHODS

Fifty-four patients, ten of whom were newly diagnosed received FMD. Forty-four percent of the previously treated patients had 'chemoresistant' disease. Treatment comprised: fludarabine 25 mg/m2 days 1-3, mitoxantrone 10 mg/m2 day 1, and dexamethasone 20 mg days 1-5. Blood/bone marrow was collected for quantitation of t(14;18) by 'real-time' PCR.

RESULTS

The overall response rate was 37 of 54 (69%), complete responses being seen in 11 patients (20%), with no difference between newly diagnosed and the previously treated patients. However, the response rate in 'chemosensitive' relapse was 84% compared to 44% in patients in whom the last prior regimen had failed. Molecular responses were seen in 17 of 25 and PCR negativity in 8 of 25, although molecular and clinical responses did not always correlate. Toxicity was moderate, 19 patients required admission. However, in 6 of 12 patients, subsequent G-CSF mobilised stem cell harvests failed.

CONCLUSIONS

FMD was well tolerated but with a lower than expected response rate. Molecular responses were seen in the majority of responding patients however, 'molecular remission' was rare.

A UK multicentre phase II study of rituximab (chimaeric anti-CD20 monoclonal antibody) in patients with follicular lymphoma, with PCR monitoring of molecular response

Follicular lymphoma (FL) cells express CD20 and are associated in most cases with the t(14;18) chromosomal translocation. A multicentre study was undertaken between January 1997 and January 1998 to assess the complete response rate (CR) and overall response rate (RR) to rituximab, a chimaeric anti-CD20 monoclonal antibody. Seventy patients with previously treated FL received rituximab (375 mg/m2/week x4, by intravenous infusion). Restaging studies were performed 1 and 2 months after therapy. Molecular monitoring for the presence of cells harbouring the Bcl-2/JH gene rearrangement in the peripheral blood (PB) and bone marrow (BM) was performed before and after treatment using a two-step semi-nested polymerase chain reaction (PCR) assay. The overall RR was 32/70 (46%), being highest in patients who had received only one previous treatment (12/15, 80%). However, only two patients achieved a CR. The median duration of response was 11 months. Thirteen of 21 evaluable 'PCR-positive' patients (62%) became 'PCR-negative' in PB and/or BM samples 1 month after rituximab, although this did not correlate with clinical response. Treatment was generally well tolerated, although one patient developed Stevens-Johnson syndrome. Rituximab was shown to be active in FL, and in some cases PB and/or BM became PCR negative. Studies in combination with cytotoxic chemotherapy to increase the CR rate are warranted.

Visual mate choice in poison frogs

We investigated female mate choice on the basis of visual cues in two populations of Dendrobates pumilio, the strawberry poison frog, from the Bocas del Toro Archipelago in Panama, Central America. Mate choice experiments were carried out by presenting subject females of each of two morphs of this species (orange and green) from two different island populations (Nancy Key and Pope Island) with object frogs (one of each morph) under glass at one end of a terrarium. Recorded calls were played simultaneously from behind both object frogs. The experiments were carried out under two light regimes: (i) white light, and (ii) relatively monochromatic filtered blue light. Subject females from each population displayed a significant preference for their own morph under white light, but not under blue light. These results indicate that female D. pumilio use visual cues in mate choice, and suggest that colour may be the visual cue they use.

Cost-effectiveness of initial therapy with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors to treat hypercholesterolemia in a primary care setting of a managed-care organization

From January 1994 through May 1995, Prudential HealthCare-North Texas prospectively studied 299 member patients diagnosed with hypercholesterolemia for whom pharmacotherapy with one of four 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, also known as statins, was prescribed. The purpose of this study was to measure the relative cost-effectiveness (CE) of these drugs in a real-world setting. This study provides information to assist decision makers in managed-care organizations (MCO) in making formulary selections. The study used a prospective, randomized, balanced cohort design, examining patients who had been prescribed initial therapy with a statin drug as monotherapy. Costs (direct medical and indirect costs) and effectiveness (percent reduction in low-density lipoprotein cholesterol levels) were based on approximately the first 6 months of initial therapy. Both the MCO and patient perspectives were considered. In the base case, mean CE ratios were significantly lower for fluvastatin compared with lovastatin, pravastatin, and simvastatin from both the managed-care perspective and the patient perspective. Sensitivity analysis did not alter the CE conclusions, even under conditions of varying cost structures. Although differences were found in the effectiveness of lovastatin, pravastatin, and simvastatin measured in this study versus efficacy measured for these drugs in controlled clinical trials, sensitivity analysis suggests that these differences alone do not determine the superior CE of fluvastatin. Finally, this study supports the idea that well-designed formularies should consider drug CE (based on safety, effectiveness, and cost) and that integration of the pharmacy benefit management with other medical management is essential. These results provide evidence that fluvastatin may represent a more cost-effective formulary choice among statin products used for initial monotherapy of hypercholesterolemia.

Phenotypic and genetic divergence in three species of dart-poison frogs with contrasting parental behavior

Why some species exhibit remarkable variation among populations while closely related species are relatively uniform remains unclear. The strawberry dart-poison frog (Dendrobates pumillo) exhibits spectacular color and pattern polmorphism among populations in the Bocas del Toro archipelago of Panama. In contrast, two other sympatric species of dart-poison frog, Phyllobates lugubris and Minyobates sp., show little color or pattern variation among island populations. Here we demonstrate that the color and pattern variation among populations of D. pumilio is not matched by higher levels of mitochondrial DNA sequence divergence relative to P. lugubris or Minyobates sp. Thus, neutral divergence in allopatry is unlikely to have caused the geographical differences observed in D. pumilio. We suggest that strong sexual selection associated with female parental care in D. pumilio, which contrasts the male parental care of P. lugubris and Minyobates sp., may have driven divergence in coloration and pattern in D. pumilio.

Three retroviral sequences in amphibians are distinct from those in mammals and birds

We isolated and characterized three endogenous retroviral fragments from the dart-poison frog Dendrobates ventrimaculatus. These are the first retroviral sequences to be identified in amphibians, and consequently retroviruses have now been found in each of the five major vertebrate classes. Comparison of the amphibian retroviral fragments, termed DevI, DevII, and DevIII, with mammalian and avian isolates revealed significant differences between their nucleotide sequences. This suggested that they were only distantly related to the seven currently recognized retroviral genera. Additional analysis by phylogeny reconstruction showed that the amphibian retroviral fragments were approximately equally related to the Moloney leukemia-related viruses, the spumaviruses, and walleye dermal sarcoma virus. Hybridization experiments revealed that viruses closely related to DevI, DevII, and DevIII do not appear to be widespread in other vertebrates and that DevI, DevII, and DevIII are all present at high copy numbers within their amphibian hosts, typically at over 250 copies per genome. The viruses described here, along with two others which have recently been found in a fish and a reptile, indicate that there may be some major differences in the retroviruses harbored by different vertebrate classes. This suggests that further characterization of retroviruses of fish, reptiles, and amphibians will help in understanding the evolution of the whole retroviral family and may well lead to the discovery of retroviruses with novel biological properties.

Cholinesterase inhibitor effects on neurotransmitters in rat cortex in vivo

A microdialysis technique was used to investigate the effect of physostigmine (PHY) and heptylphysostigmine (HEP), administered systemically or locally, on the extracellular levels of acetyl-choline (ACh), norepinephrine, dopamine and 5-hydroxytryptamine in the cerebral cortex of the rat. Levels of these neurotransmitters in dialysates were assayed simultaneously with two different high pressure liquid chromatography systems. No cholinesterase inhibitor was added into the probe to increase detection of ACh after systemic administration. Cholinesterase inhibition and its relation to ACh levels were also studied. Systemic administration of two doses of cholinesterase inhibitor [PHY (30 and 300 micrograms/kg) and HEP (2 and 5 mg/kg)] produced a dose-dependent increase in ACh levels. Local perfusion of these drugs through the probe elicited a strong increase in extracellular ACh. HEP produced a longer lasting inhibition of cholinesterase and a more prolonged elevation of ACh in cerebral cortex than PHY. After systemic administration of PHY (both doses), we observed a significant increase of norepinephrine levels. This effect was weaker after HEP. Local administration through the probe did not modify norepinephrine concentration. Dopamine levels were also increased after systemic administration. ONly HEP perfused into the probe elicited a significant increase in extracellular dopamine. Systemic or local administration did not modify 5-hydroxytryptamine levels. These observations suggest a more favorable pharmacological profile for HEP as a potential drug for Alzheimer disease, as compared to PHY.

Factors affecting ACTH release from perifused equine anterior pituitary cells

The multifactorial control of ACTH is well established. We wished to establish and characterize an in-vitro perifusion system, using equine anterior pituitary cells and physiological concentrations of secretagogues, to investigate factors which affect the dynamics of ACTH secretion. Anterior pituitary tissue was divided for dispersion into cells with collagenase, trypsin or dispase, or by mechanical dispersion. After dispersal followed by 18-h incubation, cells were perifused and the ACTH response to 10-min pulses of arginine vasopressin (AVP; 100 nmol/l), corticotrophin-releasing hormone (CRH; 0.01 nmol/l), and AVP (100 nmol/l) plus CRH (0.01 nmol/l) determined. ACTH responses to these secretagogues were lower (P < 0.05) in cells prepared using the enzymes dispase and trypsin than with the enzyme collagenase. Cells prepared by mechanical methods were not responsive. Collagenase-prepared cells were used in subsequent experiments. In dose-response studies (10-min pulse length), a steep CRH-ACTH dose-response curve was obtained with the minimum effective concentration of CRH between 0.001 and 0.01 nmol/l, and a maximum effective concentration of 1.0 nmol/l. A less steep AVP-ACTH dose-response curve was obtained with a minimum effective concentration of AVP between 0.5 and 5 nmol/l, and no plateau in response up to 5000 nmol AVP/l. Increasing the incubation time between cell preparation and stimulation with AVP from 18 h to 90 h significantly (P < 0.01) increased the ACTH response. Repeated stimulation by AVP (100 nmol/l) or CRH (0.01 nmol/l) (5-min pulses every 30 min for 23 pulses) produced ACTH responses which decreased in an approximately exponential curve with time. When AVP and CRH were given at physiological concentrations, pulse lengths and pulse frequency, the ACTH response to repeated 1-min pulses of AVP, measured as height above basal secretion, was potentiated by the addition of CRH (1, 2.5, 5, 10 and 20 pmol/l) as a constant perifusion at all AVP concentrations tested (1 nmol AVP/l, P < 0.02; 10 nmol AVP/l, P < 0.0005; 25 nmol AVP/l, P < 0.0005). During the 1-min AVP pulse, the AVP concentration at the level of the cells was 30% of the expected concentration. Potentiation was increased both by increasing AVP concentration (P < 0.00005) and by increasing CRH concentration (P < 0.00005) up to 5 pmol CRH/l. The ACTH height response to repeated AVP stimulation significantly (P = 0.034) decreased with time, independent of CRH and AVP concentration. There was a significant (P = 0.014) decrease in ACTH response to CRH infusion with time, independent of CRH concentration.(ABSTRACT TRUNCATED AT 400 WORDS)

Polymorphism in a ferritin H gene from chromosome 6p

This paper addresses the question of whether abnormalities in ferritin expression in the iron storage disease hemochromatosis (HC) involve major deletions or alterations in regions containing the two ferritin H genes that lie near the disease locus on chromosome 6p. We present evidence from analyses of Southern blots that neither gene is deleted in hemochromatosis. We also describe a polymorphism in one of the genes that we have previously shown to be a processed pseudogene. This polymorphism does not correlate with the presence of HC. The PIC value for this polymorphism was calculated as 0.49.

Communicating an evolutionary diagnosis of disability to parents

Communicating a diagnosis of disability to parents, when the diagnosis and prognosis are unclear, is problematic. This is discussed in the light of information received from mothers of such children who attended a counselling and support group. It is concluded that dissatisfaction with diagnosis is not inevitable, if similar guidelines to those suggested for children with Down's syndrome are used. It is essential that parents are involved in management and feel they have something practical to do to help their children. Clinics must organize themselves to avoid swamping parents with information and to provide regular ongoing support.

Ranitidine--bolus or infusion prophylaxis for stress ulcer

Stress ulcer is a dangerous complication for the critically ill patient. Prophylaxis with antacids can undoubtedly reduce this risk, if gastric pH is maintained above 3.5. Histamine receptor antagonists may achieve this more conveniently. We have studied the effects of ranitidine, given either as 50-mg boluses every 6 h or as one of two infusion regimes (125 or 250 micrograms/kg.h), in controlling pH in critically ill patients on a ventilator. The percentage of samples with a pH less than 4 fell in all groups during therapy; while there was no significant difference between groups, pH control was achieved more rapidly in the bolus group. Infusion therapy with ranitidine is an attractive concept but a loading dose must be used. The presence of occult blood in the gastric juice did not correlate with pH and was not affected by ranitidine therapy.

A comparison of two ranitidine intravenous infusion regimens in critically ill patients

The effect of two ranitidine intravenous infusion regimens on intragastric pH was studied in 134 critically ill patients admitted to 15 intensive care units. Intragastric pH was determined hourly for 30 hours. Those patients whose intragastric acidity fell below pH 4.0 for 3 or more of the first 6 hours were considered 'at risk' of developing stress-related gastric lesions and randomized to receive a 50 mg bolus of ranitidine together with a continuous intravenous infusion of either 0.125 or 0.25 mg kg-1 h-1 ranitidine for 24 hours. The maximal elevation in intragastric pH was achieved within 12 hours. The median intragastric pH for the last 20 hours of the infusion period was 5.9 for the higher dose group and 5.6 for the lower dose group. The increase in intragastric pH achieved by the two dosage regimens did not differ significantly throughout the 24 hour period. Patients having two or more of five major risk factors (head injury, major trauma, sepsis, respiratory failure/insufficiency and major surgery) had better overall control of intragastric pH on the higher dose of ranitidine than those receiving the lower dose. The majority of intensive care patients are likely to receive satisfactory treatment with the lower dosage regimen that was tested (0.125 mg kg-1 h-1). Those with multiple risk factors may, however, require treatment with higher doses of ranitidine (0.25 mg kg-1 h-1).

Ranitidine and cimetidine in the healing of duodenal ulcer: meta-analysis of comparative clinical trials

All available ranitidine and cimetidine comparative trials in acute duodenal ulcer disease were examined: of the 44 trials, 36 favoured ranitidine, and there was an overall difference in ulcer healing of 7%. Further stratification enabled examination of trials with common attributes: the most frequent endoscopic assessment was at 4 weeks to compare ranitidine 150 mg twice daily with cimetidine 1 g day-1 or 400 mg b.d. Twenty of these trials had sufficient data to permit pooling. Ranitidine was favoured in 18/20 trials and in three the differences achieved statistical significance. Results of the trials were combined using meta-analysis to calculate differences in ulcer healing. Most studies had sample sizes that were insufficient to detect clinically-important differences; the power to detect a 20% difference was less than 80% in 15/20 trials, and for a 10% difference was less than 80% in all but one trial. Fifteen trials compared ranitidine 150 mg b.d. with cimetidine 1 g day-1: healing after 4 weeks therapy was overall 6% greater for ranitidine. This was statistically significant (P less than 0.05) and the combined total number of patients had a power of 83% to detect this difference. In five trials the dose of cimetidine used was 400 mg b.d.: the 12% difference in healing in favour of ranitidine 150 mg b.d. was statistically significant, and the combined trials had a power of 95% to detect this difference. Ranitidine 150 mg twice daily heals significantly more duodenal ulcers after 4 weeks of therapy than either cimetidine 400 mg b.d. or cimetidine 1 g day-1.

A single night time dose of ranitidine in the acute treatment of gastric ulcer: a European multicentre trial

Four hundred and twenty eight patients with endoscopically diagnosed gastric ulcers, randomly allocated to treatment with ranitidine 300 mg at night or ranitidine 150 mg twice daily, were evaluated in a double blind multicentre trial conducted in 10 European countries. After four weeks, complete ulcer healing was observed in 138 of 211 patients (65%) treated with ranitidine 300 mg nocte and in 155 of 217 patients (71%) receiving 150 mg bd. Cumulative healing rates at eight weeks were 90% and 93%, respectively. There was no statistically significant difference between the healing rates at either four or eight weeks. The treatment regimens were equally effective at rapidly reducing the incidence of ulcer related symptoms. Adverse events reported were minor and equally distributed between the two groups. The results of this trial show that 300 mg of ranitidine administered at night is an effective and safe alternative to the current twice daily regimen for the short term treatment of gastric ulcer.

A single nighttime dose of ranitidine 300 mg versus ranitidine 150 mg twice daily in the acute treatment of duodenal ulcer: a European multicenter trial

Six hundred and five patients with endoscopically diagnosed duodenal ulcer were randomly allocated to treatment with ranitidine 300 mg at night or ranitidine 150 mg twice daily in a prospective double-blind multicenter trial conducted in nine European countries. Endoscopy at 4 weeks showed complete ulcer healing in 246 of 301 patients (82%) treated with ranitidine 150 mg b.i.d. and 230 of 304 patients (76%) treated with ranitidine 300 mg at night. Cumulative healing rates at 8 weeks were 95 and 94% respectively. Both treatment regimens were equally effective at rapidly reducing the incidence of ulcer-related symptoms. Adverse events were few and consistent with those reported in previous studies with ranitidine 150 mg twice daily. The results of this trial indicate that a single nighttime dose of ranitidine is an effective and safe alternative to the twice daily regimen in the acute treatment of duodenal ulcer.

Characteristics of the polar assembly and disassembly of microtubules observed in vitro by darkfield light microscopy

We describe here the continuous observations of the polymerization of individual microtubules in vitro by darkfield microscopy. In homogeneous preparations we verify that polymerization can occur onto both ends of microtubules. The assembly of microtubules is polar, with one end growing at three times the rate of the other. The differential rate of elongation can be used to determine the polarity of growth off cellular nucleating centers. We show that the microtubules grow off the proximal end of ciliary axonemes at a growth rate equal to that of the slow growing end of free microtubules, while growth off the distal end proceeds at the same rate as the fast growing end. Applying this technique to microtubule growth from metaphase chromosomes isolated from HeLa and CHO cells, we demonstrate that chromosomes initiate polymerization with the fast growing end facing away from the chromosome nucleation site. The opposite ends of free microtubules show different sensitivities to microtubule depolymerizing agents such as low temperature, Ca++ or colchicine as measured directly by darkfield microscopy. The differing rates of assembly and disassembly of each end of a microtubule suggest that a difference in polarity of growth off nucleating sites could serve as one basis for regulating the polymerization of different groups of microtubules in the same cell.