Comparison of explicit values clarification method (VCM), implicit VCM and no VCM decision aids for men considering prostate cancer screening: protocol of a randomized trial.

BACKGROUND: Screening with prostate-specific antigen (PSA) test for prostate cancer is considered a preference sensitive decision; meaning it does not only depend on what is best from a medical point of view, but also from a patient value standpoint. Decision aids are evidence-based tools which are shown to help people feel clearer about their values; therefore it has been advocated that decision aids should contain a specific values clarification method (VCM). VCMs may be either implicit or explicit, but the evidence concerning the best method is scarce. We aim to compare the perceived clarity of personal values in men considering PSA screening using decision aids with no VCM versus an implicit VCM versus an explicit VCM. METHODS: Male factory employees from an industrial facility in the Northern region of Portugal aged 50 to 69 years old will be randomly assigned to one of three decision aid groups used to support prostate cancer screening decisions: (i) decision aid with information only (control), (ii) decision aid with information plus an implicit VCM, (iii) decision aid with information plus an explicit VCM. Men will be allowed release time from work to attend a session at their workplace. After a brief oral presentation, those willing to participate in the study will fill the baseline questionnaire, plus a 5 point-Likert scale question about intentions to undergo screening, and will then receive the intervention materials to complete. We estimated a total sample size of 276 participants; with 92 in each group. The primary outcome will be the perceived clarity of personal values assessed by the Portuguese validated translation of the three subscales of the Decisional Conflict Scale. Secondary outcomes will be intention to be screened (before and after the intervention), the total score from the Decisional Conflict Scale and the self-report of having or not undergone screening at 6 months. DISCUSSION: This study will add to the body of evidence on the role of decision aids to support health preference-sensitive choices and provide further insight on the impact of different methods for eliciting people's values embedded within a decision aid. TRIAL REGISTRATION: NCT03988673 - clinicalTrials.gov (2019/06/17).

Self-reported cognitive function in a large international cohort of people with multiple sclerosis: associations with lifestyle and other factors.

BACKGROUND AND PURPOSE: We aimed to estimate the prevalence of perceived cognitive impairment (PCI) and explore its associations with lifestyle and disease characteristics in a large international cohort of people with multiple sclerosis (MS). METHODS: This study was a cross-sectional analysis. Participants rated their cognitive function over the preceding 4 weeks using four questions in a subscale within the Multiple Sclerosis Quality of Life questionnaire (MSQOL-54). These questions assessed perceived concentration, attention and memory by the patient and family/friends. Four definitions of PCI were derived, ranging from lowest to highest specificity. Associations with PCI were assessed by log-binomial regression. RESULTS: The prevalence of PCI in our sample ranged from 41.0% (95% confidence interval, 39.0-43.0) using the least-specific definition to 11.6% (95% confidence interval, 10.3-12.9) using the most specific definition. A number of factors were associated with PCI, increasing in magnitude as the definition specificity increased, including positive associations for smoking and body mass index, whereas physical activity, dietary quality and use of vitamin D/omega-3 supplements were inversely associated with PCI. CONCLUSIONS: Our study reports associations between healthy lifestyle behaviours and PCI in people with MS. Although reverse causality is a potential explanation for our findings, previous studies have shown comparable associations with healthy lifestyle and MS onset and progression. Subject to external validation, these results suggest benefits realized from a healthy lifestyle in people with MS.

Paravertebral block in paediatric abdominal surgery-a systematic review and meta-analysis of randomized trials.

The increased popularity of paravertebral block (PVB) can be attributed to its relative safety and comparable efficacy when compared with epidural analgesia. It has thus been recommended for open cholecystectomy and other less painful surgeries such as inguinal herniorraphy and appendectomy. We performed a systematic review of PVB in paediatric abdominal conditions to assess its clinical efficacy and side effects compared with other analgesic therapies.A search of Medline, Embase, and Web of Science and hand-searching references from inception date to May 2016 was done. Relevant studies were randomized clinical trials in patients 0-18 years old comparing PVB (single shot or continuous catheter) with any comparator and analgesic medication. Pain scores, rescue analgesia and adverse events were compared.The systematic reviews identified six trials enrolling 358 paediatric patients. PVB medications included bupivacaine, ropivacaine, lidocaine, and fentanyl. Surgical procedures included inguinal herniorraphy, cholecystectomy, and appendectomy. The standardized mean difference in early pain scores favoured PVB: 0.85 [95% confidence interval (CI) 0.12-1.58] at 4-6 h and 0.64 (95% CI 0.28-1.00) at 24 h. One study reported a reduced length of stay. Parental [odds ratio (OR) 5.12 (95% CI 2.59-10.1)] and surgeon [OR 6.05 (95% CI 2.25-16.3)] satisfaction were higher in those receiving a PVB. No major complications occurred with a PVB.PVB resulted in minimally improved pain scores for up to 24 h after surgery, reduced rescue analgesia requirements, and increased surgeon and parental satisfaction. PVB is a good alternative to caudal and ilioinguinal block in paediatric abdominal surgery.

Cross-species prediction of human survival probabilities for accelerated anthrax vaccine absorbed (AVA) regimens and the potential for vaccine and antibiotic dose sparing.

Anthrax vaccine adsorbed (AVA, BioThrax) was recently approved by the Food and Drug Administration (FDA) for a post-exposure prophylaxis (PEP) indication in adults 18-65years of age. The schedule is three doses administered subcutaneous (SC) at 2-week intervals (0, 2, and 4weeks), in conjunction with a 60-day course of antimicrobials. The Public Health Emergency Medical Countermeasures Enterprise (PHEMCE) developed an animal model to support assessment of a shortened antimicrobial PEP duration following Bacillus anthracis exposure. A nonhuman primate (NHP) study was completed to evaluate the efficacy of a two dose anthrax vaccine absorbed (AVA) schedule (0, 2weeks) aerosol challenged with high levels of B. anthracis spores at week4- the time point at which humans would receive the third vaccination of the approved PEP schedule. Here we use logistic regression models to combine the survival data from the NHP study along with serum anthrax lethal toxin neutralizing activity (TNA) and anti-PA IgG measured by enzyme linked immunosorbent assay (ELISA) data to perform a cross-species analysis to estimate survival probabilities in vaccinated human populations at this time interval (week4 of the PEP schedule). The bridging analysis demonstrated that high levels of NHP protection also yield high predicted probability of human survival just 2weeks after the second dose of vaccine with the full or half antigen dose regimen. The absolute difference in probability of human survival between the full and half antigen dose was estimated to be at most approximately 20%, indicating that more investigation of the half-antigen dose for vaccine dose sparing strategies may be warranted.

Evaluation of early immune response-survival relationship in cynomolgus macaques after Anthrax Vaccine Adsorbed vaccination and Bacillus anthracis spore challenge.

Anthrax Vaccine Adsorbed (AVA, BioThrax) is approved by the US Food and Drug Administration for post-exposure prophylaxis (PEP) of anthrax in adults. The PEP schedule is 3 subcutaneous (SC) doses (0, 14 and 28 days), in conjunction with a 60 day course of antimicrobials. The objectives of this study were to understand the onset of protection from AVA PEP vaccination and to assess the potential for shortening the duration of antimicrobial treatment (http://www.phe.gov/Preparedness/mcm/phemce/Documents/2014-phemce-sip.pdf). We determined the efficacy against inhalation anthrax in nonhuman primates (NHP) of the first two doses of the PEP schedule by infectious challenge at the time scheduled for receipt of the third PEP dose (Day 28). Forty-eight cynomolgus macaques were randomized to five groups and vaccinated with serial dilutions of AVA on Days 0 and 14. NHP were exposed to Bacillus anthracis Ames spores on Day 28 (target dose 200 LD50 equivalents). Anti-protective antigen (PA) IgG and toxin neutralizing antibody (TNA) responses to vaccination and in post-challenge survivors were determined. Post-challenge blood and selected tissue samples were assessed for B. anthracis at necropsy or end of study (Day 56). Pre-challenge humoral immune responses correlated with survival, which ranged from 24 to 100% survival depending on vaccination group. Surviving, vaccinated animals had elevated anti-PA IgG and TNA levels for the duration of the study, were abacteremic, exhibited no apparent signs of infection, and had no gross or microscopic lesions. However, survivors had residual spores in lung tissues. We conclude that the first two doses of the PEP schedule provide high levels of protection by the scheduled timing of the third dose. These data may also support consideration of a shorter duration PEP antimicrobial regimen.

Interim analysis of the effects of exenatide treatment on A1C, weight and cardiovascular risk factors over 82 weeks in 314 overweight patients with type 2 diabetes.

AIM: Exenatide, an incretin mimetic for the adjunct treatment of type 2 diabetes (DM2), reduced A1C and weight in 30-week placebo-controlled trials. This analysis examined the effects of exenatide on glycaemic control and weight over an 82-week period in patients with DM2 unable to achieve adequate glycaemic control with sulphonylurea (SU) and/or metformin (MET). METHODS: This interim analysis is of 314 patients who received exenatide in the 30-week placebo-controlled trials and subsequently in 52 weeks of open-label uncontrolled extension studies for 82 weeks of exenatide in total. Patients continued their SU and/or MET regimens throughout. RESULTS: Patients completed 82 weeks of exenatide treatment [n = 314, 63% M, age 56 +/- 10 years, weight 99 +/- 21 kg, body mass index 34 +/- 6 kg/m2, A1C 8.3 +/- 1.0% (mean +/- SD)]. Reduction in A1C from baseline to week 30 [-0.9 +/- 0.1% (mean +/- SE)] was sustained to week 82 (-1.1 +/- 0.1%), with 48% of patients achieving A1C < or = 7% at week 82. At week 30, exenatide reduced body weight (a secondary endpoint) from baseline (-2.1 +/- 0.2 kg), with progressive reduction at week 82 (-4.4 +/- 0.3 kg). Similar results were observed for the intent-to-treat population (n = 551), with reductions in A1C and weight at week 82 of -0.8 +/- 0.1% and -3.5 +/- 0.2 kg respectively. The 82-week completer cohort showed statistically significant improvement in some cardiovascular risk factors. The most frequent adverse events were generally mild-to-moderate nausea and hypoglycaemia. CONCLUSION: In summary, 82 weeks of adjunctive exenatide treatment in patients with DM2 treated with SU and/or MET resulted in sustained reduction in A1C and progressive reduction in weight, as well as improvement in some cardiovascular risk factors.

Epidemiology of capsular and surface polysaccharide in Staphylococcus aureus infections complicated by bacteraemia.

Staphylococcus aureus is a leading cause of serious hospital- and community-acquired infections. The discovery of serologically distinct capsular polysaccharides on the surface of clinical isolates has allowed the development of vaccines and passive protective immunity. We have studied patient characteristics, infection characteristics and the surface and capsular polysaccharide serotype distribution in patients with S. aureus infections complicated by bacteraemia admitted to VA hospitals in Maryland between 1995 and 2000. Nine hundred and ninety-three blood cultures from 331 patients were positive for S. aureus. Thirty-eight percent of patients had diabetes, 11% had end-stage renal failure, and 23% were injection drug users. Forty-two percent of infections were caused by methicillin-resistant strains (MRSA), and 60% were acquired during hospitalization. Serotyping of the first available isolate per patient (N=234 isolates) using polyclonal antibodies showed three major phenotypes--42%, type 8 (T8) capsule; 50%, type 5 (T5) capsule; and 8%, 336 polysaccharide. MRSA isolates were significantly more likely to be T5 than methicillin-susceptible isolates (66% vs. 39%, P<0.001). The proportion of T5 MRSA increased significantly (years 1-2: 41%; years 3-4: 65%; years 5-6: 90%, P<0.001). This large sample of patients with serious S. aureus infection confirms that capsular polysaccharides T5 and T8 cause most human infections, and together with serotype 336, account for nearly all those with bacteraemia.

Role of active site binding interactions in 4-chlorobenzoyl-coenzyme A dehalogenase catalysis.

4-Chlorobenzoyl-coenzyme A (4-CBA-CoA) dehalogenase catalyzes the hydrolytic dehalogenation of 4-CBA-CoA to 4-hydroxybenzoyl-CoA (4-HBA-CoA) via a multistep mechanism involving initial attack of Asp145 on C(4) of the substrate benzoyl ring to form a Meisenheimer intermediate (EMc), followed by expulsion of the chloride ion to form an arylated enzyme intermediate (EAr) and then ester hydrolysis in the EAr to form product. This study examines the role of binding interactions in dehalogenase catalysis. The enzyme and substrate groups positioned for favorable binding interaction were identified from the X-ray crystal structure of the enzyme-4-HBA-3'-dephospho-CoA complex. These groups were individually modified (via site-directed mutagenesis or chemical synthesis) for the purpose of disrupting the binding interaction. The changes in the Gibbs free energy of the enzyme-substrate complex (DeltaDeltaG(ES)) and enzyme-transition state complex (DeltaDeltaG) brought about by the modification were measured. Cases where DeltaDeltaG exceeds DeltaDeltaG(ES) are indicative of binding interactions used for catalysis. On the basis of this analysis, we show that the H-bond interactions between the Gly114 and Phe64 backbone amide NHs and the substrate benzoyl C=O group contribute an additional 3.1 kcal/mol of stabilization at the rate-limiting transition state. The binding interactions between the enzyme and the substrate CoA nucleotide moiety also intensify in the rate-limiting transition state, reducing the energy barrier to catalysis by an additional 3.3 kcal/mol. Together, these binding interactions contribute approximately 10(6) to the k(cat)/K(m).

Histidine 90 function in 4-chlorobenzoyl-coenzyme a dehalogenase catalysis.

4-chlorobenzoyl-coenzyme A (4-CBA-CoA) dehalogenase catalyzes the hydrolytic dehalogenation of 4-CBA-CoA by attack of Asp145 on the C4 of the substrate benzoyl ring to form a Meisenheimer intermediate (EMc), followed by expulsion of chloride ion to form an arylated enzyme intermediate (EAr) and, finally, ester hydrolysis in EAr to form 4-hydroxybenzoyl-CoA (4-HBA-CoA). This study examines the contribution of the active site His90 to catalysis of this reaction pathway. The His90 residue was replaced with glutamine by site-directed mutagenesis. X-ray crystallographic analysis of H90Q dehalogenase complexed with 4-HBA-CoA revealed that the positions of the catalytic groups are unchanged from those observed in the structure of the 4-HBA-CoA-wild-type dehalogenase complex. The one exception is the Gln90 side chain, which is rotated away from the position of the His90 side chain. The vacated His90 site is occupied by two water molecules. Kinetic techniques were used to evaluate ligand binding and catalytic turnover rates in the wild-type and H90Q mutant dehalogenases. The rate constants for 4-CBA-CoA (both 7 microM(-1) x s(-1)) and 4-HBA-CoA (33 and 11 microM(-1) x s(-1)) binding to the two dehalogenases are similar in value. For wild-type dehalogenase, the rate constant for a single turnover is 2.3 s(-1) while that for multiple turnovers is 0.7 s(-1). For H90Q dehalogenase, these rate constants are 1.6 x 10(-2) and 2 x 10(-4) s(-1). The rate constants for EMc formation in wild-type and mutant dehalogenase are approximately 200 s(-1) while the rate constants for EAr formation are 40 and 0.3 s(-1), respectively. The rate constant for hydrolysis of EAr in wild-type dehalogenase is 20 s(-1) and in the H90Q mutant, 0.13 s(-1). The 133-fold reduction in the rate of EAr formation in the mutant may be the result of active site hydration, while the 154-fold reduction in the rate EAr hydrolysis may be the result of lost general base catalysis. Substitution of the His90 with Gln also introduces a rate-limiting step which follows catalysis, and may involve renewing the catalytic site through a slow conformational change.

Meeting the needs of future physicians: a core curriculum initiative for postgraduate medical education at a Canadian university.

UNLABELLED: In addition to possessing medical expertise, contemporary physicians are expected to be skilled communicators, critical consumers and users of medical research, teachers, collaborators, health care advocates, and managers. A core curriculum is a common set of learning experiences designed to help prepare physicians for these complex roles. PURPOSE: This article describes the design and implementation of one core curriculum, summarizes the feedback received from residents, and shares some of the lessons we are learning as we use feedback to develop our programme. METHOD: The core curriculum described was implemented at a Canadian university which offers 56 residency programmes with a total enrollment of approximately 360 students. The curriculum consisted of 30 sessions organized around four themes: biostatistics and epidemiology; communications and teaching skills; healthcare management, and ethical, medicolegal and lifestyle issues. Each session in the Core Curriculum was evaluated by residents with respect to the timing, quality, and value of the learning experience. In addition, residents participated in focus group discussions of their Core Curriculum experiences. RESULTS: Key findings related to the characteristics of effective core curriculum learning experiences and to the barriers to implementing a core curriculum across programmes. Of particular salience were findings related to explicit issues of attendance and the diverse needs of learners and programmes, and to more implicit issues of communication and managing change. The specific content and format of the Core Curriculum and the results of the evaluation process will be of interest to others considering a core curriculum for postgraduate medical programmes.

Prion filament networks in [URE3] cells of Saccharomyces cerevisiae.

The [URE3] prion (infectious protein) of yeast is a self-propagating, altered form of Ure2p that cannot carry out its normal function in nitrogen regulation. Previous data have shown that Ure2p can form protease-resistant amyloid filaments in vitro, and that it is aggregated in cells carrying the [URE3] prion. Here we show by electron microscopy that [URE3] cells overexpressing Ure2p contain distinctive, filamentous networks in their cytoplasm, and demonstrate by immunolabeling that these networks contain Ure2p. In contrast, overexpressing wild-type cells show a variety of Ure2p distributions: usually, the protein is dispersed sparsely throughout the cytoplasm, although occasionally it is found in multiple small, focal aggregates. However, these distributions do not resemble the single, large networks seen in [URE3] cells, nor do the control cells exhibit cytoplasmic filaments. In [URE3] cell extracts, Ure2p is present in aggregates that are only partially solubilized by boiling in SDS and urea. In these aggregates, the NH(2)-terminal prion domain is inaccessible to antibodies, whereas the COOH-terminal nitrogen regulation domain is accessible. This finding is consistent with the proposal that the prion domains stack to form the filament backbone, which is surrounded by the COOH-terminal domains. These observations support and further specify the concept of the [URE3] prion as a self-propagating amyloid.

Head lice resistance: itching that just won't stop.

OBJECTIVE: To evaluate the reports of resistance and cross-resistance to pediculicides in the head louse (Pediculus capitis), as well as the mechanisms involved. DATA SOURCES: Literature identified through a MEDLINE search (1966-April 2000) and through other secondary literature databases and/or bibliographies of pertinent articles. DATA SYNTHESIS: Head lice infestation is a common, worldwide problem. The widespread use of insecticide treatments together with inadequate treatment methods has led to a concern regarding the potential development of resistant head lice. This literature review examines the reports of resistance of the head louse as well as the purported mechanisms involved. CONCLUSIONS: Current research suggests that head lice resistance exists, but little is known regarding the actual incidence of this resistance or whether this incidence is increasing. More research is needed to assess the status of this problem. Proposed mechanisms for head lice resistance include knock-down resistance, glutathione S-transferase-based resistance, and monooxygenase-based resistance.

The crystal structure of the nitrogen regulation fragment of the yeast prion protein Ure2p.

The yeast nonchromosomal gene [URE3] is due to a prion form of the nitrogen regulatory protein Ure2p. It is a negative regulator of nitrogen catabolism and acts by inhibiting the transcription factor Gln3p. Ure2p residues 1--80 are necessary for prion generation and propagation. The C-terminal fragment retains nitrogen regulatory activity, albeit somewhat less efficiently than the full-length protein, and it also lowers the frequency of prion generation. The crystal structure of this C-terminal fragment, Ure2p(97--354), at 2.3 A resolution is described here. It adopts the same fold as the glutathione S-transferase superfamily, consistent with their sequence similarity. However, Ure2p(97--354) lacks a properly positioned catalytic residue that is required for S-transferase activity. Residues within this regulatory fragment that have been indicated by mutational studies to influence prion generation have been mapped onto the three-dimensional structure, and possible implications for prion activity are discussed.

Improving knowledge of the prostate cancer screening dilemma among African American men: an academic-community partnership in Washington, DC.

OBJECTIVE: Studies have shown that African American men are at greater risk than other men for prostate cancer in terms of both incidence and mortality. At the same time, the utility of screening asymptomatic men for prostate cancer remains controversial. The combination of high incidence and high mortality with the uncertain benefits of screening poses a difficult problem for African American men. This study was part of an ongoing project that sought to develop and evaluate health education materials designed to help African American men make an informed decision about prostate cancer screening. The project represented a collaboration between the Most Worshipful Prince Hall Grand Lodge of the District of Columbia and the Lombardi Cancer Center of Georgetown University. METHODS: The authors conducted eight focus groups with 44 members of the Prince Hall Masons. The focus groups covered men's understanding of prostate cancer screening and their preferences for methods of health education. RESULTS: Participants demonstrated a high level of awareness of the availability of prostate cancer screening, a low awareness of the screening controversy, and a desire for detailed epidemiologic information and information about the benefits and limitations of screening. The preferred forms of educational materials were video and print-based materials, which the research team has recently developed. CONCLUSIONS: These findings demonstrate the feasibility of developing an academic-community collaboration with the goal of improving a health-related problem in the African American community. A randomized trial is underway to evaluate the impact of the video and print education materials.

Prions of yeast from cytoplasmic genes to heritable amyloidosis.

It was believed that only proteins could carry out enzymatic reactions, and only nucleic acids could mediate inheritance. In recent years, the work of Cech and Altman and others has shown that nucleic acids can catalyze reactions. Now it has been shown that, in yeast, proteins can mediate inheritance. The infectious protein (prion) concept arose from studies of the transmissible spongiform encephalopathies (TSEs) of mammals (1), and several lines of evidence suggest that TSEs are indeed caused by infectious forms of the PrP protein, but the absence of definitive proof has left substantial doubt and disagreement on this point (2-6). The ease of genetic manipulation of yeast offers experimental possibilities not yet available even in the mouse system. This enabled the discovery of yeast prions (7), and has facilitated the rapid characterization of these systems. The parallels between the yeast and mammalian systems are striking. Moreover, because both of the yeast prion systems appear to involve self-propagating amyloid forms of the respective proteins, these systems may also serve as models for the broader class of diseases for which amyloid accumulation is a central feature. The discovery of the [HET-s] prion of the filamentous fungus Podospora, another genetically manipulable system, adds a new dimension to prion studies (8).

Agricultural consultancy--a career choice for veterinarians.

OBJECTIVE: To document the personal, educational and professional skills that characterise veterinarians pursuing careers as agricultural consultants and to determine the future direction for veterinary-related advisory services to agriculture in Australia. DESIGN: Thirty-six veterinarians practising as consultants in agriculture throughout Australia were sent a postal survey in 1994. PROCEDURE: A descriptive analysis was chosen because of the relatively small population available to sample. Comparisons were made on a percentage basis where appropriate. RESULTS: Twenty-four useable responses to the questionnaire were received. Consultants were mostly men with an agricultural background, aged 31 to 40 years. They considered their undergraduate veterinary studies to be a stepping stone into further education and practical experience and ultimately consultancy. Consultants predicted an increased reliance for their work on corporate farms, private agribusiness, research and development and sub-contracted work, rather than on family-owned farms. Consultants disagreed on the wisdom of combining consultancy activities with alternative businesses (for instance mixed veterinary practice). Only 13 consultants derived greater than 76% of their income from consultancy and 14 combined another business with consulting. The need for continuing education was considered important. Consultants predicted various future prospects for the industry. Many predicted that there would not be enough veterinarians to fulfill the demand for this type of work. IMPLICATIONS FOR THE VETERINARY PROFESSION: Results from this survey suggest that veterinary consulting will extend into finance, agronomy and marketing in addition to current skills in animal nutrition, parasite control and animal reproduction. As clients demand specialised skills and knowledge, the formation of co-operatives or companies of specialists may be beneficial to both client and consultant in the future. The consultant's role can be characterised as one of extending relevant information to clients in a useful form. Excellent communication skills are necessary, as is an understanding of rural issues and animal industries.

Prions of yeast as heritable amyloidoses.

Two infectious proteins (prions) of Saccharomyces cerevisiae have been identified by their unusual genetic properties: (1) reversible curability, (2) de novo induction of the infectious prion form by overproduction of the protein, and (3) similar phenotype of the prion and mutation in the chromosomal gene encoding the protein. [URE3] is an altered infectious form of the Ure2 protein, a regulator of nitrogen catabolism, while [PSI] is a prion of the Sup35 protein, a subunit of the translation termination factor. The altered form of each is inactive in its normal function, but is able to convert the corresponding normal protein into the same altered inactive state. The N-terminal parts of Ure2p and Sup35p (the "prion domains") are responsible for prion formation and propagation and are rich in asparagine and glutamine residues. Ure2p and Sup35p are aggregated in vivo in [URE3]- and [PSI]-containing cells, respectively. The prion domains can form amyloid in vitro, suggesting that amyloid formation is the basis of these two prion diseases. Yeast prions can be cured by growth on millimolar concentrations of guanidine. An excess or deficiency of the chaperone Hsp104 cures the [PSI] prion. Overexpression of fragments of Ure2p or certain fusion proteins leads to curing of [URE3].

A conserved motif within the vitamin K-dependent carboxylase gene is widely distributed across animal phyla.

The vitamin K-dependent gamma-glutamyl carboxylase catalyzes the posttranslational conversion of glutamic acid to gamma-carboxyglutamic acid, an amino acid critical to the function of the vitamin K-dependent blood coagulation proteins. Given the functional similarity of mammalian vitamin K-dependent carboxylases and the vitamin K-dependent carboxylase from Conus textile, a marine invertebrate, we hypothesized that structurally conserved regions would identify sequences critical to this common functionality. Furthermore, we examined the diversity of animal species that maintain vitamin K-dependent carboxylation to generate gamma-carboxyglutamic acid. We have cloned carboxylase homologs in full-length or partial form from the beluga whale (Delphinapterus leucas), toadfish (Opsanus tau), chicken (Gallus gallus), hagfish (Myxine glutinosa), horseshoe crab (Limulus polyphemus), and cone snail (Conus textile) to compare these structures to the known bovine, human, rat, and mouse cDNA sequences. Comparison of the predicted amino acid sequences identified a nearly perfectly conserved 38-amino acid residue region in all of these putative carboxylases. In addition, this amino acid motif is also present in the Drosophila genome and identified a Drosophila homolog of the gamma-carboxylase. Assay of hagfish liver demonstrated vitamin K-dependent carboxylase activity in this hemichordate. These results demonstrate the broad distribution of the vitamin K-dependent carboxylase gene, including a highly conserved motif that is likely critical for enzyme function. The vitamin K-dependent biosynthesis of gamma-carboxyglutamic acid appears to be a highly conserved function in the animal kingdom.