Coercive Control Between Intimate Partners: An Application to Nonfatal Strangulation

Nonfatal strangulation between intimate partners represents an extreme controlling form of violent behavior, increasing the risk that intimate partner violence (IPV) becomes lethal. Guided by Dutton and Goodman's conceptualization of coercive control, the present research explored the relation between death threats and subsequent nonfatal strangulation to amplify the credibility of those threats, using a large sample of IPV perpetrators (n = 6,488). Logistic regression analyses determined the relation between overt threats to a partner's life during an initial incident arrest and subsequent nonfatal strangulation postincident arrest, accounting for perpetrator characteristics and assessed risk. Results showed the highly gendered nature of this violent behavior, noting that men were significantly more likely than women to persist in nonfatal strangulation. Given the potential lethality of this violent behavior, the analysis also explored whether treatment service recommendations (family violence education, counseling, and mental health evaluation) mitigate these patterns. These preliminary findings support the further exploration of treatment and intervention efforts for reducing nonfatal strangulation.

Persistence and Potential Lethality in Intimate Partner Violence: Evaluating the Concurrent and Predictive Validity of a Dual Risk Assessment Protocol

This study seeks to determine the concurrent and predictive validity of a dual risk assessment protocol. It combines the risk of persistence in intimate partner violence (IPV) measured via the Domestic Violence Screening Instrument-Revised (DVSI-R) with supplemental items from the Danger Risk Assessment (DRA) bearing on the risk of potential lethality. We further test whether this assessment protocol reproduces disparities by race and ethnicity found in the larger population. Using a sample of 4,665 IPV male defendants with a female victim, analyses support both types of criterion validity. The DRA risk score is associated with felony charges, incarceration at the initial arrest, and the frequency of subsequent dangerous behavior. Results also suggest minimal predictive bias or disparate impact by race and ethnicity. Incorporating supplemental items bearing on potential lethality risk adds important information concerning the risk management strategies of those involved in IPV.

Determination of antimony and barium in UK air quality samples as indicators of non-exhaust traffic emissions

The aim of this study was to determine concentrations of antimony and barium in air quality samples and assess the potential suitability of these metals as tracer elements for non-exhaust traffic emissions sources. Air quality filters sampled at monitoring sites around the UK for the purposes of the UK Heavy Metals Monitoring Network were subjected to microwave digestion in hydrogen peroxide and nitric acid, then analysed by ICP-MS for a suite of metals including antimony and barium. The average antimony concentration found across all the network sites was 1.84 ng m^-3; the average barium concentration was 6.33 ng m^-3. The range of antimony concentrations observed was 0.13-8.02 ng m^-3; barium concentrations ranged from levels below the detection limit of 0.18 to 39.9 ng m^-3. There are no legislative limits for antimony and barium in ambient air, but the maximum concentrations found are well below the Workplace Exposure Limits specified by the UK Health and Safety Executive. The highest concentrations were found at roadside sites situated to monitor traffic environments, supporting the suitability of antimony and barium to be considered tracer elements for traffic emissions sources. Strong correlations were observed between antimony, barium and copper, indicating they share a common traffic-related source. Based on the strong correlation with copper at urban and traffic locations, indicative annual UK atmospheric emission estimates for antimony and barium in brake and tyre wear were calculated as 6 and 19 tonnes respectively.

The Son-Rise Program® intervention for autism

With increasing availability of interventions for children with autism, it is important that these are backed by rigorous evaluation data that have high levels of ecological validity. To achieve this, a key prerequisite for any evaluation is to gather data on typical consumers and typical implementation patterns of the intervention. This study collected such data longitudinally in relation to the Son-Rise Program®, a home-based parent-run intervention for autism. Questionnaires and interview data on family demographics, implementation patterns, and perceived treatment fidelity were gathered three times over the course of a year from families who had attended a Son-Rise® initial training course. Although it proved possible to produce a profile of intervention use, findings indicated that the programme is not always implemented as it is typically described in the literature. The study also highlighted methodological challenges likely to be encountered in any future evaluation of this and similar interventions for autism.

A pilot randomized trial of community-based parent training for immigrant Latina mothers

This paper reports on the development and piloting of the Madres a Madres (Mothers to Mothers) program, a new, community-based parent training program designed for immigrant Latina mothers and their children. Promotoras, or female community health workers of Latina background, delivered the program in a home visitation format. A total of 194 mothers and 194 focal children (87 male, 107 female) ages 7-12 were randomized to the intervention (113 mother-child dyads) or wait-list control condition (81 mother-child dyads) over the study period. Outcomes of interest were mother-reported parenting skills, broad family functioning, and child externalizing and internalizing behaviors. Data collection occurred at pretest, 3-month posttest, and 9-month follow-up periods. Multilevel growth models revealed increases in intervention mothers' reported parenting skills, family support, and family organization, and reductions in child internalizing behavior from pretest to follow-up, relative to the control condition. Outcomes did not vary by focal child age, gender, nativity status, or mother acculturative status (years in the United States). Findings are discussed in the context of future directions for research on the Madres a Madres program and on the implementation and dissemination of empirically-supported parent training practices to culturally diverse families.

Gender and intimate partner violence: does dual arrest reveal gender symmetry or asymmetry?

Research on Intimate Partner Violence (IPV) has ignited considerable controversy about gender and IPV. Feminist scholars have viewed IPV as a manifestation of male dominance and control, with women primarily the victims and men primarily the perpetrators of this behavior (gender asymmetry). Conversely, family violence researchers have viewed IPV as emerging from conflicts in relationships, with both men and women being involved (gender symmetry). The present study was framed within the context of this controversy using new empirical evidence on one person arrested (single arrest) or both persons arrested (dual arrest) in IPV incidents. Data were acquired on the assessed risk of IPV recidivism immediately after arrest and actual IPV recidivism over an 18-month period postassessment across the state of Connecticut involving heterosexual partners (N = 2,155). Though not definitive, the findings showed persistent gender asymmetry on these behavioral characteristics across arrest categories.

Family violence risk assessment: A predictive cross-validation study of the Domestic Violence Screening Instrument-Revised (DVSI-R)

This research was a cross-validation study of the Domestic Violence Screening Instrument-Revised (DVSI-R), using a diverse, statewide sample of 3,569 family violence perpetrators in Connecticut, assessed in February and March of 2007. It analyzed re-arrest data collected during an 18-month period post assessment. Three issues were central, which have been ignored in previous research on family violence risk assessment: (1) analyzing five refined measures of behavioral recidivism, (2) determining whether perpetrator characteristics and types of family and household relationships (beyond just heterosexual intimate partners) moderate the empirical relations between the DVSI-R and the behavioral recidivism measures, and (3) determining whether structured clinical judgment about the imminent risk of future violence to the victim or to others corresponds with recidivism predicted by the DVSI-R total numeric risk scores. The empirical findings showed that the DVSI-R had significant predictive accuracy across all five measures of recidivism. With one exception, these relations did not vary by gender, age, or ethnicity; and again with one exception, no significant evidence was found that types of family or household relationships moderated those empirical relations. In short, the evidence suggested that the DVSI-R was a robust risk assessment instrument, having applicability across different types of perpetrators and different types of family and household relationships. Finally, the empirical findings showed that structured clinical judgment about imminent risk-to-victim and risk-to-others corresponded with the prediction of recidivism by the DVSI-R total numeric risk scores, but the effects of those scores were significantly stronger than the perceived risk-to-victim or the perceived risk-to-others.

Preventing children's aggression in immigrant Latino families: a mixed methods evaluation of the Families and Schools Together program

The effectiveness of the evidence based program, Families and Schools Together (FAST), was examined in two inter-related studies with immigrant Latino (Mexican) families in the U.S. In Study 1, we reported findings from pre-test, 3-month post-test, and 12-month follow-up surveys of parents and children participating in the FAST program. Families were selected from communities that were randomly assigned to either intervention or control groups. A total of 282 parents (263 mothers and 19 fathers) participated in either the intervention (140 parents) or control (142 parents) condition over the course of 3 years. Each of the parents had a participating focal child; thus, 282 children (144 females and 138 males; average age = 9.5 years) participated in the study. A primary focus of the research was to determine whether participation in FAST led to reductions in children's aggression. Using linear growth models, no differences were noted on aggression between intervention and control groups, although intervention children did show significant improvements in social problem-solving skills and perceptions of collective efficacy. In Study 2, we conducted two focus groups with ten FAST participants to explore whether other unmeasured outcomes were noted and to understand better the mechanisms and impact of FAST. All of the parents in the focus groups reported that FAST had helped them better relate to and communicate with their children, and that the greatest effect was on the behavior of their older children. Results are discussed in terms of cultural fit of the FAST program for immigrant Latino families and future directions.

Comb wax mediates the acquisition of nest-mate recognition cues in honey bees

Honey bees, Apis mellifera, acquire nest-mate recognition cues from wax, the predominant material used in nest construction. Exposure of a newly emerged worker bee to wax-comb substrate significantly reduced the acceptability of that worker to sister bees. Cues acquired from the comb provided colony-specific information about the identity of worker bees; moreover, the effect of comb exposure has been previously shown to override individually produced cues. Food odors (anise oil), when dissolved in paraffin wax, affected worker-recognition characteristics but food odors did not affect these characteristics when fed to bees in sugar candy. Paraffin wax alone did not affect the recognition cues of bees, showing that the wax can be a neutral medium for the transmission of cues. The wax comb in the colony and the hydrocarbon outer layer of the bee cuticle may be a continuous medium for any hydrocarbon-soluble substances used by honey bees in nest-mate recognition; if so, a mechanism by which environmental cues are acquired by honey bees is provided.

Preventing youth problem behaviors and enhancing physical health by promoting core competencies

OBJECTIVES

The purpose of the present study was to investigate the longitudinal relations between specific core competencies, problem behaviors, and physical health among adolescents.

METHODS

The study used two waves of data collected 1 year apart from the Add Health data set. The Add Health data set is a nationally representative sample of adolescents in grades 7 to 12. A total of 14,010 respondents were included in this study. There were two outcomes that were examined in this study: problem behavior (as observed by seven different behaviors), and health (general health and physical problems).

RESULTS

We found that problem behavior and health outcomes were two distinct behavioral patterns that were related to one another. The two outcomes also shared common developmental predictors.

CONCLUSIONS

Our findings suggest that a focus on core competencies is an important target for preventive interventions; among the competencies measured low self-control was the strongest single predictor of problem behaviors and adverse health outcomes.

Prevalence and predictors of internet bullying

PURPOSE

With the Internet quickly becoming a new arena for social interaction, it has also become a growing venue for bullying among youth. The purpose of the present study was to contrast the prevalence of Internet bullying with physical and verbal bullying among elementary, middle, and high school boys and girls, and to examine whether key predictors of physical and verbal bullying also predicted Internet bullying.

METHODS

As part of an ongoing, statewide bullying prevention initiative in Colorado, 3,339 youth in Grades 5, 8, and 11 completed questionnaires in 78 school sites during the fall of 2005, and another 2,293 youth in that original sample participated in a follow-up survey in 65 school sites in the spring of 2006. Questionnaires included measures of bullying perpetration and victimization, normative beliefs about bullying, perceptions of peer social support, and perceptions of school climate.

RESULTS

The highest prevalence rates were found for verbal, followed by physical, and then by Internet bullying. Physical and Internet bullying peaked in middle school and declined in high school. Verbal bullying peaked in middle school and remained relatively high during high school. Males were more likely to report physical bullying than females, but no gender differences were found for Internet and verbal bullying. All three types of bullying were significantly related to normative beliefs approving of bullying, negative school climate, and negative peer support.

CONCLUSIONS

Preventive interventions that target school bullying by changing norms about bullying and school context may also impact Internet bullying, given the shared predictors.

Neural transplantation of human MSC and NT2 cells in the twitcher mouse model

BACKGROUND

Accumulating evidence has demonstrated that the NT2 embryonal carcinoma cell line and multipotential stem cells found in BM, mesenchymal stromal cells (MSC), have the ability to differentiate into a wide variety of cell types. This study was designed to explore the efficacy of these two human stem cell types as a graft source for the treatment of demyelinating disorders such as Krabbe's disease and multiple sclerosis (MS).

METHODS

We examined the engraftment and in vivo differentiation of adult MSC and NT2 cells after transplantation into two demyelinating environments, the neonatal and postnatal twitcher mouse brain.

RESULTS

Both types of xenografts led to anatomical integration, without tumor formation, and remained viable in the normal and twitcher mouse brain, showing differentiation into neurons, astrocytes and oligodendrocytes.

DISCUSSION

This study represents a platform for further stem cell transplantation studies in the twitcher model and potentially has important therapeutic implications.

A numerical approach to resonance frequency analysis for the investigation of oral implant osseointegration

Experimental devices based on vibration testing are employed as non-destructive procedures for evaluating implants osseointegration. Their behaviour was evaluated considering the outcome of numerical analysis. The purpose was to use the finite element method for assessing the ability of frequency analysis in detecting the degree of oral implant osseointegration. A three-dimensional model of a mandible was obtained from tomographic survey. A single implant was considered in canine region. Two configurations were analysed, with and without a mass linked to the implant as a cantilever, reproducing experimental devices. Simulation consisted of analysing the response to impulse forces for different osseointegration levels, thus evaluating the biomechanical efficiency of the implant-bone compound. A good correlation between frequency response and osseointegration level was obtained. This was carried out by providing an impulse excitation of the implant that resulted in a vibration pattern. Within the limit of finite element analysis, the outcomes showed that numerical investigation provides understanding the behaviour of testing devices based on frequency measurements, confirming the potential of vibrations technique as non-invasive analysis for osseointegration process.

Empirically examining the risk of intimate partner violence: the revised Domestic Violence Screening Instrument (DVSI-R)

OBJECTIVE

This study extends recent research on assessing the risk of intimate partner violence by determining the concurrent and predictive validity of a revised version of the Domestic Violence Screening Instrument (DVSI-R) and whether evidence of such validity is sustained independent of perpetrator demographic characteristics and forms of intimate violence. The analyses highlight violent incidents involving multiple victims as an indicator of "severe" violence. Previous research did not address these issues.

METHODS

Data were analyzed on 14,970 assessments conducted in the State of Connecticut from September 1, 2004 through May 2, 2005. Hierarchical regression and receiver operating characteristic analyses were used to address the objectives of this research.

RESULTS

The empirical findings support the concurrent and predictive validity of the DVSI-R and show that it is robust in its applicability. The findings further show that incidents involving multiple victims are highly associated with DVSI-R risk scores and recidivistic violence.

CONCLUSION

Validating and demonstrating the robustness of a risk assessment instrument is only a first step in preventing violence involving intimate partners or others in family or family-like relationships. The challenge is to train professionals responsible for addressing the problem of such violence to link valid risk assessments to well-crafted strategies of supervision and treatment so that the victimized or other potential victims are protected and perpetrators are held accountable for their actions.

The effect of feedback training on lumbosacral compression during simulated occupational lifting

This study measured the effect of a feedback training program on lumbar compression during simulated occupational lifting. Two distinct types of feedback were compared: real-time electromyographic feedback, vs. an acceleration index delivered verbally post-lift. Kinematic data were collected from 28 subjects during symmetrical sagittal plane lifts. Following a baseline session, two feedback training sessions were provided, with a 1-week interval between each session. A control group followed the same protocols, but without receiving feedback training. A post-training session, using protocols identical to the baseline session, was used to assess pre-to-post changes in the dependent variable: peak lumbosacral compression computed using a dynamic linked-segment model. All three groups showed reductions in peak compression from pre-to-post: on average the control group improved by 11.2%, the EMG group by 16.7%, and the acceleration group by 25.3%. The results revealed an interaction between the improvement and the group (p=0.023), and a difference between the improvement in the control group and that in the verbal acceleration feedback group (p<0.01). These reductions in lumbosacral compression persisted after a 7-day interval without feedback training, suggesting that this approach could provide sustained risk-reduction during manual materials handling.

Assessing the risk of domestic violence reoffending: a validation study

Little research has been conducted to validate available instruments for assessing the risk of domestic violence reoffending, especially research using some form of prospective design. This study uses a prospective design to determine the reliability and validity of the Domestic Violence Screening Instrument (DVSI). The analysis is based on a sample of 1,465 male domestic violence offenders selected consecutively over a 9-month period. Data on reoffending were collected in a 6-month follow-up period from a subsample of the victims (N = 125) of these perpetrators and from official records for all perpetrators during an 18-month follow-up period. The empirical results suggest that the DVSI was administered reliably, and they provide significant evidence of the concurrent, discriminant, and predictive validity of this instrument. Implications for further research and utilization of the DVSI are discussed.

The Son-Rise Program intervention for autism: an investigation into family experiences

BACKGROUND

Despite the increasing involvement of parents as therapists in interventions for their children with autism, research to date has focused almost exclusively on the outcome for the child, and little is known about the effects of involvement on the whole family. This is true even of highly intensive home-based approaches such as the Son-Rise Program (SRP), the focus of the present paper. A longitudinal questionnaire-based study is reported which investigated a number of potential positive and negative effects for the family, how these changed over time, and their relation to child characteristics and patterns of intervention implementation.

METHODS

Questionnaires examining family demographics, patterns of intervention use and perceived family effects were distributed three times over the course of a year to families who had attended an initial training course in the use of the SRP.

RESULTS

The results indicated that, although involvement led to more drawbacks than benefits for the families over time, family stress levels did not rise in all cases. Few relationships were found between family effects and patterns of intervention use, although there was a strong connection with parental perceptions of intervention efficacy.

CONCLUSIONS

The findings of the present study emphasize the need for those supporting families using home-based interventions to consider the needs of the whole family. This may be especially important if there are periods during which the family find the intervention to be less effective. Families embarking on such intensive approaches may also benefit from considering ways in which any disruption to family life can be minimized.

Multimodality radiotherapy and androgen ablation in the treatment of clinically localized prostate cancer: early results in high risk patients

In patients presenting with clinically localized prostate cancer, the risk of biochemical failure increases significantly with higher Gleason scores, prostate specific antigen (PSA) levels, and clinical stages. Current surgical and radiotherapeutic approaches appear to offer limited success in patients with highly adverse prognostic factors. In an attempt to improve on these outcomes, we have combined external beam radiotherapy (EBRT) with a brachytherapy (BT) boost and neo adjuvant and adjuvant androgen ablation in a population at significant risk of biochemical failure. Here we present early biochemical progression data for this approach. From October 1997 to July 1999, 72 men with a serum PSA >or=10 ng/ml or Gleason score >or=7 or clinical stage >or=T2c (AJC/UICC 1992) underwent EBRT followed by palladium-103 BT. All patients underwent 8 months of combined androgen ablation with leuprolide and an oral antiandrogen beginning 3 months prior to initiation of EBRT. Patients were followed by PSA and digital rectal examination (DRE) at 3-month intervals and a chart review on all patients was carried out during July 2001. To allow comparisons to contemporary literature, Kaplan-Meier survival curves were generated utilizing three alternate definitions of biochemical recurrence: PSA >0.2 ng/ml, PSA >1.0 ng/ml, and the American Society for Therapeutic Radiology and Oncology (ASTRO) consensus definition of three consecutive rising PSAs. Our results indicate that when PSA >0.2 ng/ml was used to define biochemical progression, 88% (95% CI 80-97) of patients remained free of disease at 24 months. When PSA >1.0 ng/ml was used, 97% (CI 92-100) of patients remained disease free at 24 months. ASTRO criteria yielded 90% (CI 82-98) recurrence-free survival at 24 months. In conclusion, this very early report indicates that in patients who are at increased risk of biochemical failure, EBRT with a BT boost in conjunction with short-term androgen ablation offers potentially superior biochemical disease-free survival to contemporary alternative approaches in the literature. Clearly, longer follow-up is required to confirm the durability of this approach.

Head injury and alexithymia: implications for family practice care

BACKGROUND

Alexithymia, a deficit in emotional information processing, and a history of head injury have both been found to be related to high rates of psychosomatic illness, substance abuse, depression, and utilization of primary care services. To date, no study has examined the potential comorbidity of alexithymia and head injury in a family practice setting, a necessary step in evaluating the aetiologic role of head injury in the development of alexithymia. The goals of this study are to establish prevalence of head injury and alexithymia in a family practice setting and to evaluate the relation, if present, between the two.

METHODS

Patients (n =135) of a family practice residency facility were screened using the Traumatic Brain Injury Questionnaire and the Toronto Alexithymia Scale-20.

RESULTS

Forty-nine per cent of the participants reported a history of head injury and 18% were alexithymic. Those with a history of head injury had significantly higher scores of alexithymia. Chi-square analysis indicated a relation between head injury and alexithymia.

CONCLUSIONS

The high rates of self-reported history of head injury in family practice settings, particularly in the context of alexithymia, may adversely affect a physician's ability to care for these patients. Increasing physicians' awareness of head injury and the potential mediating role of alexithymia in medical and psychological illness may facilitate effective diagnosis and patient-physician communication.

A finite element stress analysis of the transmandibular implant system

PURPOSE

The aim of this work was a simulation of the onset of osseointegration of the transmandibular implant system in the mandible. This was achieved by imposing joint elements at the implant-bone interface.

MATERIALS AND METHODS

The geometric model was derived from the anatomic measurement of several mandibles by tomographic scanning. The spring constants of the joint elements interposed at the implant-bone interface were varied between 1 N/mm and 10(9) N/mm to represent the conditions leading to osseointegration.

RESULTS

Increasing the value of the spring constant at the joint elements gradually increases the effective stress in an increasing volume of crestal cortical bone. Additionally, a larger volume of crestal cortical bone assumes a higher stress value as the simulation proceeds.

CONCLUSION

This work indicates that considerable changes in stress magnitude and distribution occur in the crestal cortical bone margins as osseointegration is simulated, which may be the necessary stimulus for bone remodeling.

Correcting out-of-plane errors in two-dimensional imaging using nonimage-related information

Two-dimensional imaging with a single camera assumes that the motion occurs in a calibrated plane perpendicular to the camera axis. It is well known that kinematic errors result if the object fails to remain in this plane and that if both the distance to the calibration plane from the camera and the distance out-of-plane are known, an analytical correction for the out-of-plane error can be made. Less well appreciated is that out-of-plane distance can frequently be acquired from other, nonimage-related information. In the two examples given, the mediolateral center of pressure coordinate of the foot measured from a force plate and the measured landing point of a shot put throw were used. In both cases, the resulting out-of-plane correction improved the accuracy of the 2-D kinematic data dramatically. These examples also demonstrate that the use of nonimage-related data can increase the accuracy of kinematic data without an increase in the complexity of the experiment.

Two two-gene macronuclear chromosomes of the hypotrichous ciliates Oxytricha fallax and O. trifallax generated by alternative processing of the 81 locus

We describe the first know macronuclear chromosomes that carry more than one gene in hypotrichous ciliated protozoa. These 4.9- and 2.8-kbp chromosomes each consist almost exclusively of two protein-coding genes, which are conserved and transcribed. The two chromosomes share a common region that consists of a gene that is a member of the family of mitochondrial solute carrier genes (CR-MSC; [Williams and Herrick (1991): Nucleic Acids Res 19:4717-4724]. Each chromosome also carries another gene appended to its common region: The 4.9-kbp chromosome also carries a gene that encodes a protein that is rich in glutamine and charged amino acids and bears regions of heptad repeats characteristic of coiled-coils. Its function is unknown. The second gene of the 2.8 kbp chromosome is a mitochondrial solute carrier gene (LA-MSC); thus, the 2.8-kbp chromosomes consists of two mitochondrial solute carrier paralogs. Phylogenetic analysis indicates that the two genes were duplicated before ciliates diverged from the main eukaryotic lineage and were subsequently juxtaposed. The CR- and LA-MSC genes are each interrupted by three introns. The introns are not in homologous positions, suggesting that they may have originated from multiple group II intron transpositions. These chromosomes and their genes are encoded in the Oxytricha germline by the 81 locus. This locus is alternatively processed to generate a nested set of three macronuclear chromosomes, the 4.9- and 2.8-kbp chromosomes and a third (1.6 kbp) which consists almost exclusively of the shared common gene, CR-MSC. Such alternative processing is common in macronuclear development of O. fallax [Cartinhour and Herrick (1984): Mol Cell Biol 4:931-938]. Possible functions for alternative processing are considered; e.g., it may serve to physically link genes to allow co-regulation or co-replication by a common cis-acting sequence.

PRMT1 is the predominant type I protein arginine methyltransferase in mammalian cells

Type I protein arginine methyltransferases catalyze the formation of asymmetric omega-N(G),N(G)-dimethylarginine residues by transferring methyl groups from S-adenosyl-L-methionine to guanidino groups of arginine residues in a variety of eucaryotic proteins. The predominant type I enzyme activity is found in mammalian cells as a high molecular weight complex (300-400 kDa). In a previous study, this protein arginine methyltransferase activity was identified as an additional activity of 10-formyltetrahydrofolate dehydrogenase (FDH) protein. However, immunodepletion of FDH activity in RAT1 cells and in murine tissue extracts with antibody to FDH does not diminish type I methyltransferase activity toward the methyl-accepting substrates glutathione S-transferase fibrillarin glycine arginine domain fusion protein or heterogeneous nuclear ribonucleoprotein A1. Similarly, immunodepletion with anti-FDH antibody does not remove the endogenous methylating activity for hypomethylated proteins present in extracts from adenosine dialdehyde-treated RAT1 cells. In contrast, anti-PRMT1 antibody can remove PRMT1 activity from RAT1 extracts, murine tissue extracts, and purified rat liver FDH preparations. Tissue extracts from FDH(+/+), FDH(+/-), and FDH(-/-) mice have similar protein arginine methyltransferase activities but high, intermediate, and undetectable FDH activities, respectively. Recombinant glutathione S-transferase-PRMT1, but not purified FDH, can be cross-linked to the methyl-donor substrate S-adenosyl-L-methionine. We conclude that PRMT1 contributes the major type I protein arginine methyltransferase enzyme activity present in mammalian cells and tissues.

Elevated levels of Ca(II) modulate the activity and inhibition of serine proteases: implication in the mechanism of apoptosis

Elevated levels of intracellular Ca(II) are a prominent feature of apoptosis, a natural form of cell death involved in many physiological and pathological processes. Serine proteases play crucial roles in apoptosis and have been implicated in the genomic DNA degradation and the massive protein degradation that occur during apoptosis. In this study, the effects of the elevated level of Ca(II) on the activity and inhibition of serine proteases were examined by spectrophotometric methods. The effects of the elevated levels of Ca(II), Mg(II), K(I), and Na(I) on the activity and inactivation of three representative members of serine proteases were determined. The level of serine protease activity in CEM-C7-14 leukemic cells was also evaluated in the presence and absence of dexamethasone-induced apoptosis, and also in the presence of A23187, a Ca(II)-ionophore. Among the four metal-ions studied, only Ca(II) was found to significantly enhance the activity of mammalian serine proteases. Ca(II) was also found to significantly protect the enzymes from inhibition, while the other three metal-ions showed no significant effect on the inactivation of the enzymes. Compared to the control sample, the enzymic activity was found to be higher during apoptosis, and in the presence of the Ca(II)-ionophore. Results of this study indicate that Ca(II) can significantly enhance the catalytic efficiency of serine proteases during apoptosis.

Identification of the RNA binding domain of T4 RegA protein by structure-based mutagenesis

The T4 translational repressor RegA protein folds into two structural domains, as revealed by the crystal structure (Kang, C.-H. , Chan, R., Berger, I., Lockshin, C., Green, L., Gold, L., and Rich, A. (1995) Science 268, 1170-1173). Domain I of the RegA protein contains a four-stranded beta-sheet and two alpha-helices. Domain II contains a four-stranded beta-sheet and an unusual 3/10 helix. Since beta-sheet residues play a role in a number of protein-RNA interactions, one or both of the beta-sheet regions in RegA protein may be involved in RNA binding. To test this possibility, mutagenesis of residues on both beta-sheets was performed, and the effects on the RNA binding affinities of RegA protein were measured. Additional sites for mutagenesis were selected from molecular modeling of RegA protein. The RNA binding affinities of three purified mutant RegA proteins were evaluated by fluorescence quenching equilibrium binding assays. The activities of the remainder of the mutant proteins were evaluated by quantitative RNA gel mobility shift assays using lysed cell supernatants. The results of this mutagenesis study ruled out the participation of beta-sheet residues. Instead, the RNA binding site was found to be a surface pocket formed by residues on two loops and an alpha-helix. Thus, RegA protein appears to use a unique structural motif in binding RNA, which may be related to its unusual RNA recognition properties.

Determination of molecular masses of proteins in solution: Implementation of an HPLC size exclusion chromatography and laser light scattering service in a core laboratory

Size exclusion chromatography (SEC) coupled with "on-line" laser light scattering (LS), refractive index (RI), and ultraviolet (UV) detection provides an elegant approach to determining the molecular weights of proteins and their complexes in solution. SEC serves solely as a fractionation step to minimize the ambiguity that otherwise can result from the fact that light scattering provides the weight-average molecular weight (MW) of all species in solution. Our goal is to establish realistic expectations for MW determination using LS coupled with SEC, define sample requirements, and identify possible limitations of SEC/LS analysis. Analyses of 14 protein standards that range from 12 to 475 kd suggest that the molecular weights of native proteins may be determined in a single SEC/LS experiment with an accuracy of +/-5%. The MW determination depends only on the downstream LS and RI detectors, and it is independent of elution position. Unusual elution because of nonglobular shape or interaction with the SEC support has no impact on the MW determination by SEC/LS. With the instrument configuration that was used, the optimal amount of protein needed for SEC/LS is about 50 g for proteins with molecular weight greater than 40 kd. However, analyses of ovalbumin and transferrin demonstrate that even 10 g is sufficient to determine the MW with an error of less than +/-6%. Although SEC/LS has some limitations, such as proteins that contain chromophores whose absorption spectrum overlaps that of the emission spectrum of the laser, it represents a fast and robust approach to determining MW and to monitoring protein oligomerization in solution.

Identification of protein-arginine N-methyltransferase as 10-formyltetrahydrofolate dehydrogenase

S-Adenosylmethionine:protein-arginine N-methyltransferase (EC 2.1.1. 23; protein methylase I) transfers the methyl group of S-adenosyl-L-methionine to an arginine residue of a protein substrate. The homogeneous liver protein methylase I was subjected to tryptic digestion followed by reverse phase high performance liquid chromatography (HPLC) separation and either "on-line" mass spectrometric fragmentation or "off-line" Edman sequencing of selected fractions. Data base searching of both the mass spectrometric and Edman sequencing data from several peptides identified the protein methylase as 10-formyltetrahydrofolate dehydrogenase (EC 1.5.1.6; Cook, R. J., Lloyd, R. S., and Wagner, C. (1991) J. Biol. Chem. 266, 4965-4973; Swiss accession number). This identification was confirmed by comparative HPLC tryptic peptide mapping and affinity chromatography of the methylase on the 5-formyltetrahydrofolate-Sepharose affinity gel used to purify the dehydrogenase. The purified rat liver methylase had approximately 33% of the 10-formyltetrahydrofolate dehydrogenase and 36% of the aldehyde dehydrogenase activity as compared with the recombinant dehydrogenase, which also had protein methylase I activity. Polyclonal antibodies against recombinant dehydrogenase reacted with protein methylase I purified either by polyacrylamide gel electrophoresis or 5-formyltetrahydrofolate affinity chromatography. In each instance there was only a single immunoreactive band at a molecular weight of approximately 106,000. Together, these results confirm the co-identity of protein-arginine methyltransferase and 10-formyltetrahydrofolate dehydrogenase.

Uptake and internalization of exogenous apolipoprotein E3 by cultured human central nervous system neurons

Apolipoprotein E (apoE) has been confirmed as a risk factor for late-onset Alzheimer's disease (AD) and is associated with neurofibrillary tangles and senile plaques, the microscopic pathological characteristics of AD. There has been no direct evidence that human central nervous system neurons can take up and internalize exogenous apoE, which may be important in order for apoE to be involved in the development of the disease. This paper demonstrates by immunohistochemistry and confocal microscopy that cultured human brain neurons can take up and internalize exogenous recombinant human apoE3. We confirm that neurons express the low-density lipoprotein receptor-related protein (LRP) but do not express the low-density lipoprotein receptor. We also demonstrate that the LRP mediates the neuronal uptake of apoE.

Use of liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) for routine identification of enzymatically digested proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis

Automated liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) analysis of >100 tryptic digests carried out on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) separated, Coomassie Blue-stained proteins that were prepared by >50 different laboratories demonstrates that a commercial electrospray/quadrupole ion trap mass spectrometer and the tandem mass correlation algorithm developed by Eng et al. (Am. Soc. Mass Spectrom. 1994, 5, 976-989) provide an extremely robust and facile approach to routine protein identification. By requiring a minimum of two significant matches to peptides that would be predicted to be produced by the protease that was used, low pmol levels of proteins can be identified with high confidence while minimizing the probability of identifying the protease itself and/or the ubiquitous contaminant, keratin. Hence, in only 7% of the digests analyzed was keratin identified and in only 5% of the digests analyzed was the protease itself identified. In contrast, 58% of the analyzed samples were identified and, in many instances, multiple proteins were identified in the same sample. Although the median amount of digest analyzed was 6.1 pmol, the limit of sensitivity (as the instrument is configured with a flow rate of 4 microL/min) appears to be at the 500 fmol level. Since one of the primary reasons for not identifying a sample is that its sequence is not yet in the database searched, the utility of an LC MS/MS approach to protein identification will certainly increase in the future as the sequences of more genomes are completed.

Design of prosthetic cantilever bridgework supported by osseointegrated implants using the finite element method

OBJECTIVES

The aim of the present work was to establish a design procedure for fixed metal prostheses supported by osseointegrated implants in order to prevent permanent deformation and hence failure following loading. Previously, the cantilever cross-sectional shape in the buccal lingual plane has been based on clinical experience and subjectivity.

METHODS

This work has relied on the use of linear elastic finite element analysis in order to generate a maximum effective stress at which permanent deformation commences on loading. A number of different cross-sectional shapes were investigated, both of conventional design as well as new innovative possibilities. Both straight and curved cantilever beams 26 mm long were examined.

RESULTS

The design failure chosen was based on a von Mises plastic collapse principle by comparing the calculated effective stresses with the yield stress of the metal in simple tension. It was found that the "L" shaped design was more rigid than other designs for a given mass, while a framework based on an open "I" section offers good possibilities particularly when used as curved shapes.

SIGNIFICANCE

Assuming a failure criterion based on the von Mises principle, then "L" shaped Co/Cr or stainless steel frameworks, typically 26 mm of cantilever span, undergo permanent deformation at end loadings between 130 and 140 N depending on section curvature. Since it is known biting loads can exceed these values, good design is critical if such failures are to be avoided.

Enzymatic cleavage and HPLC peptide mapping of proteins

Detailed procedures are described for successfully digesting reasonably small quantities (i.e., usually > 10 pmol) of proteins with a variety of proteases and for then isolating the resulting peptides by reverse-phase HPLC. Since sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) appears to be the current method of choice for final purification of proteins for structural analysis, special attention is given to carrying out in-gel proteolytic digests on SDS-PAGE-separated proteins that have usually been stained with Coomassie Blue. A compilation of data from nearly 200 "unknown" samples is used to help provide realistic expectations with respect to the results that are likely to be obtained from carrying out in-gel proteolytic digests on large numbers of proteins.

Site-to-site variability of drug concentrations in skeletal muscle

The homogeneity of drug concentrations in skeletal muscle was assessed in eight fatal overdoses. Ten to 30 random samples were taken from leg muscle weighing 1,650 to 7,985 g. For cases involving paracetamol the mean muscle-to-blood ratio ranged from 0.1 to 1.1 (n = 4) for amitriptyline 1.1 to 3.6 (n = 3), and for dothiepin 0.8 to 2.1 (n = 2). The coefficient of variance was large for all drugs, ranging from 10.5 (carbamazepine) to 50 (thioridazine). Skeletal muscle is not homogeneous with respect to drug concentrations in fatal overdose cases. Of 16 instances of drug detection in blood 2 (nortriptyline and promethazine) were not detected in muscle. Muscle-to-blood drug ratios varied significantly among cases, possibly influenced by survival time after drug ingestion. Quantitative interpretations of muscle drug levels present significant difficulties. However, skeletal muscle can be used for qualitative corroboration of blood analyses and is a suitable specimen for drug detection where none other is available.

Investigation of the integration process of dental implants by means of a numerical analysis of dynamic response

OBJECTIVES

The aim of this work was to present a preliminary numerical analysis of the integration process of dental implants using a finite element simulation of the dynamic response following impulse excitation. Assessment of the osseointegration process has been previously examined using a numerical approach by calculating the natural frequency of a cantilever attached to the implant. The methodology adopted in this work allows a direct measurement of the implant response following impulse loading and avoids the addition of a bulky cantilever set-up.

METHODS

The geometric configuration was obtained by averaging the coordinate data from tomographic scans of 14 mandibles. The materials properties were approximated from experimental analysis performed on trabecular and cortical bone tissue. A load was applied to the top of the implant in one direction resulting in an initial displacement. The implant was then freed and allowed to vibrate over approximately 10 cycles. Three fixity conditions were assumed by changing the properties of the surrounding bone ranging from full integration to a poorly integrated implant typical of the situation during bone healing following surgery. The results of the three fixity conditions were compared by calculating the fundamental displacement amplitudes and frequencies of the vibrating impact.

RESULTS

The calculated results indicated that the implant vibrated at a predominant frequency when partially integrated with a displacement principally in the direction of the applied impulse. However, when the implant was fully integrated a more complex vibration pattern ensued, suggesting the superposition of two or more fundamentals.

SIGNIFICANCE

Attention has been paid to the formulation of the numerical model for validation purposes as well as a reliable reference for the optimum interpretation of the experimental data. In this way it was possible to establish a simulation procedure to investigate the response of the tissues surrounding the implant and their properties at different stages of healing. It should be pointed out that the numerical procedures represented a valid preliminary approach to the problem and were capable of indicating a guide to the optimum design of the experimental apparatus for measurement of displacement and frequency in vivo.

Selection on the protein-coding genes of the TBE1 family of transposable elements in the ciliates Oxytricha fallax and O. trifallax

TBE1s are "cut-and-paste" transposable elements found in high copy number in the germline genomes of the ciliates Oxytricha fallax and O. trifallax. TBE1 "family" sequence (sequence of mixed polymerase chain reaction products generated using primers that match roughly half the TBE1s in host whole-cell DNA) was obtained from both host species. Although family sequence autoradiograms represent thousands of different elements, they are as legible as those representing corresponding sequences of a single TBE1, implying that ideal polymorphisms are rare within the genes examined. Nucleotide polymorphisms among TBE1s (indicated by ambiguities in family sequence) are far more common at third than at first or second positions of codons of genes, implying that selection has conserved the amino acid sequences of these genes in the majority of TBE1s. Portions of the transposase gene and another TBE1 gene have been sequenced from 10 individual TBE1s. None of these portions is interrupted by stop codons or frameshifts, and, for both genes, pairwise comparisons of these sequences show that nonsynonymous differences are significantly less common than synonymous differences, again implicating conservative selection Phylogenetic analysis shows that multiple divergent lineages of TBE1s have evolved under this selection within O. fallax. All these results are unexpected for cut-and-paste transposons in eukaryotic hosts: since transposase encoded by intact elements presumably acts in trans, it can duplicate mutant copies (those that do not encode functional transposase) found in the same genome, and thus no selection is expected to maintain the transposase gene. The selection demonstrated here could act at transposition (if functional TBE1s are preferentially transposed) or at the level of the host (if the host's fitness depends on functional TBE1 genes). TBE1-encoded proteins might be responsible for the precise excision of TBE1s that occurs during development of the host somatic nucleus; selection on hosts for uninterrupted somatic genes would then translate into selection for TBE1 protein-coding competence. We suggest a method for distinguishing between these two classes of explanations by finding and analyzing divergent alleles of ancestral transposable element insertions.

Impulse response of a dental implant in bone by numerical analysis

The osseointegration process of titanium dental implants in bone has been simulated previously using natural frequency and impulse excitation. However, the impulse strength was arbitrarily chosen and may not have yielded the correct frequencies and displacements to be compared with those measured in a clinical situation. In this work the range of impulse excitation strengths applied to a dental implant osseointegrated in bone and the corresponding response have been examined using the finite element method. Both conditions of a dental pin only and a dental pin with attached cantilever integrated in the mandible have been examined. The dynamic analysis indicated that the frequency and displacement responses are indeed sensitive to impulse duration and direction but independent of impulse load. The analysis summarizes the proper impulse excitation values for a correct interpretation of clinically measured frequency response data.

Identification of N(G)-methylarginine residues in human heterogeneous RNP protein A1: Phe/Gly-Gly-Gly-Arg-Gly-Gly-Gly/Phe is a preferred recognition motif

Three sites of N(G),N(G)-arginine methylation have been located at residues 205, 217, and 224 in the glycine-rich, COOH-terminal one-third of the HeLa A1 heterogeneous ribonucleoprotein. Together with the previously determined dimethylated arginine at position 193 [Williams et al., (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 5666-5670], it is evident that all four sites fall within a span of sequence between residues 190 and 233 that contains multiple Arg-Gly-(Gly) sequences interspersed with phenylalanine residues. These RGG boxes have been postulated to represent an RNA binding motif [Kiledjian and Dreyfuss (1992) EMBO J. 11, 2655-2664]. Dimethylation of HeLa A1 appears to be quantitative at each of the four positions. Arginines 205 and 224 have been methylated in vitro by a nuclear protein arginine methyltransferase using recombinant (unmethylated) A1 as substrate. This suggests A1 may be an in vivo substrate for this enzyme. Examination of sequences surrounding the sites of methylation in A1 along with a compilation from the literature of sites that have been identified in other nuclear RNA binding proteins suggests a methylase-preferred recognition sequence of Phe/Gly-Gly-Gly-Arg-Gly-Gly-Gly/Phe, with the COOH-terminal flanking glycine being obligatory. Taken together with data in the literature, identification of the sites of A1 arginine methylation strongly suggests a role for this modification in modulating the interaction of A1 with nucleic acids.

Mode shapes of a damaged and repaired tympanic membrane as analysed by the finite element method

This work makes use of recent finite element discretization of the human tympanic membrane where the known anisotropy of the tympanic membrane is implemented by a series of thin beam elements superimposed on thin shell membrane elements. These thin beam elements were introduced in order to simulate the fibre structure of the tympanic membrane. The onset of tympanosclerosis has been modelled as a gradual increase in tympanic membrane density and modulus in the affected area. This increased density results in a fall of 55% of the first natural frequency for only a 16% area of drum sclerosis. Additionally the amplitude response is significantly reduced. Repair of the membrane was simulated by removal of the fibre system from the affected area. Under these circumstances the natural frequencies virtually return to the healthy state but the mode shapes of vibration do not. The repair to the membrane, although not significantly altering frequency values, has resulted in a disruption to the normal mode shape patterns with consequences in the movements conveyed to the stapes and cochlear fluids.

A dynamic and harmonic damped finite element analysis model of stapedotomy

This study was undertaken in an attempt to better understand the mechanics of sound transmission at the footplate following stapedotomy. The insertion of a Teflon (polytetrafluoroethylene) stapes prosthesis introduces new constraints within the reconstructed ossicular chain which have an effect on the normal vibration patterns of the tympanic membrane. In a finite element model of the ear, constraints have been reproduced as a series of spring constants in the incus/prosthesis/footplate interfaces incorporating damping to simulate the impedance of the inner ear. At zero damping, the frequency response at the pseudo stapes footplate exhibit several maxima and minima between 800 Hz and 2.5 Hz. At higher damping values, these maxima and minima become smoothened out with two or three naturals occurring over the same frequency range. Severe ankylosis of a diseased footplate is reproduced by over-damped conditions. The umbo, incus and stapes footplate vibrate in phase with similar frequencies at light damping levels. The movement of the prosthesis at the pseudo-footplate can be large in the out of plane axis of the ossicular chain, unless sufficient support is provided at the reconstructed footplate. Clinically, this would suggest the vein graft interposed between the piston and stapedotomy hole should endow resistance and elasticity to the system.

Crystal structure of the two RNA binding domains of human hnRNP A1 at 1.75 A resolution

Heterogeneous ribonucleoprotein A1 (hnRNP A1) is an abundant eukaryotic nuclear RNA binding protein. A1 is involved in the packaging of pre-mRNA into hnRNP particles, transport of poly A+ mRNA from the nucleus to the cytoplasm and may modulate splice site selection. The crystal structure of A1(RBD1,2) reveals two independently-folded RNA binding domains (RBDs) connected by a flexible linker. Both RBDs are structurally homologous to the U1A(RBD1), and have their RNA binding platforms oriented in an anti-parallel fashion. The anti-parallel arrangement of the A1 RNA binding platforms suggests mechanisms for RNA condensation and ways of bringing together distant RNA sequences for RNA metabolism such as splicing or transport.

Apolipoprotein E uptake and low-density lipoprotein receptor-related protein expression by the NTera2/D1 cell line: a cell culture model of relevance for late-onset Alzheimer's disease

Apolipoprotein E has been shown to be a risk factor for late-onset Alzheimer's disease, with the apolipoprotein epsilon 4 allele conferring the risk. Apolipoprotein E is found in neurofibrillary tangles and senile plaques, the pathological characteristics of Alzheimer's disease. To date there is no direct evidence that human neurons can take up exogenous apolipoprotein E, which is necessary if apolipoprotein E is involved in the formation of neurofibrillary tangles. To examine apolipoprotein E uptake we employed the human NTera2/D1 cell line, which can be induced by retinoic acid to differentiate into postmitotic NTera2-N neurons, which have the characteristics and morphology of human central nervous system neurons. We defined the cell line as genotype apolipoprotein epsilon 3/3 and demonstrated that the cells do not synthesize apolipoprotein E but can take up and internalize exogenous recombinant apolipoprotein E3. We also confirmed the expression of the low-density lipoprotein receptor-related protein, a known receptor for apolipoprotein E. The NTera2/D1 cell line therefore provides a useful human cell model for examining the effects of other apolipoprotein E isoforms with a view to defining intraneuronal interactions of apolipoprotein E.

Internal eliminated sequences interrupting the Oxytricha 81 locus: allelic divergence, conservation, conversions, and possible transposon origins

Internal eliminated sequences (IESs) often interrupt ciliate genes in the silent germline nucleus but are exactly excised and eliminated from the developing somatic nucleus from which genes are then expressed. Some long IESs are transposons, supporting the hypothesis that short IESs are ancient transposon relics. In light of that hypothesis and to explore the evolutionary history of a collection of IESs, we have compared various alleles of a particular locus (the 81 locus) of the ciliated protozoa Oxytricha trifallax and O. fallax. Three short IESs that interrupt two genes of the locus are found in alleles from both species, and thus must be relatively ancient, consistent with the hypothesis that short IESs are transposon relics. In contrast, TBE1 transposon interruptions of the locus are allele-specific and probably the results of recent transpositions. These IESs (and the TBE1s) are precisely excised from the DNA of the developing somatic macronucleus. Each IES interrupts a highly conserved sequence. A few nucleotides at the ends of each IES are also conserved, suggesting that they interact critically with IES excision machinery. However, most IES nucleotide positions have evolved at high rates, showing little or no selective constraint for function. Nonetheless, the length of each IES has been maintained (+/- 3 bp). While one IES is approximately 33 bp long, three other IESs have very similar sizes, approximately 70 bp long. Two IESs are surrounded by direct repeats of the sequence TTCTT. No other sequence similarities were found between any of the four IESs. However, the ends of one IES do match the inverted terminal repeat consensus sequence of the "TA" IESs of Paramecium. Three O. trifallax alleles appear to have been recipients in recent conversion events that could have been provoked by double-strand breaks associated with IES ends subsequent to IES transposition. Our findings support the hypothesis that short IESs evolved from ancient transposons that have lost most of their sequences, except those necessary for precise excision during macronuclear development.

hnRNP A1 binds promiscuously to oligoribonucleotides: utilization of random and homo-oligonucleotides to discriminate sequence from base-specific binding

To understand the range of possible and probable A1 functions in pre-mRNA biogenesis, it is important that we quantify the relative ability (or inability) of A1 to bind high affinity RNA target sequences and/or structures. Using a fluorescence competition assay we have determined apparent binding affinities for a wide range of 20mer oligos containing putative and possible A1 targets including the high affinity 'winner' sequence identified by selection/amplification [Burd,C.G and Dreyfuss,G. (1994) EMBO J. 13, 1197-1204], AUUUA sequences found in 3'-UTRs of labile mRNAs, 5'- and 3'-splice sites and telomeric sequences. With the exception of a 20mer 'winner' sequence, all other 20mers examined bind A1 with a narrow, approximately 10-fold range of affinities extending from 3.2 x 10(6) to 4.2 x 10(7) M(-1). Studies with homo-oligomers suggest this range reflects nucleotide base rather than sequence specificity and hence, it was possible to predict reasonably accurate affinities for all other 20mers examined except for the 'winner', whose unusually high affinity of 4.0 x 10(8) M(-1) results from a unique higher order structure and sequence. Since there is no known physiological role for the 'winner' 20mer sequence, these data suggest A1 generally binds indiscriminately to all available pre-mRNA sequences. Both the large abundance of A1 in vivo and its binding properties are thus consistent with it playing a structural role in pre-mRNA biogenesis.

Purification and characterization of a recombinant hepatitis E protein vaccine candidate by liquid chromatography-mass spectrometry

A protein with a molecular mass of approximately 62.10(3), derived from open reading frame 2 (ORF-2) of the hepatitis E virus (HEV: Burma strain), was expressed in a baculovirus expression vector and purified to homogeneity. The recombinant 62 kDa protein appeared to be a doublet, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Tryptic digestion in conjunction with laser desorption mass spectrometry (LD-MS) and sequence analysis of the tryptic peptides indicated that the amino terminus was blocked, although no proteolytic degradation occurred. The determined internal sequences of peptides were in agreement with the predicted ORF-2 protein. Reversed-phase liquid chromatography coupled to electrospray mass spectrometry (LC-MS) resolved the doublet proteins into two major components with molecular masses of 56548.5 and 58161.4. Confirmation of the amino terminus of the molecule by LD-MS post-ion decay enabled us to tentatively assign the carboxyl terminus of each species at residues 540 and 525. Sequencing of the intact protein by automated carboxyl terminal sequencing confirmed that the carboxyl terminus was truncated and that the sequence assignment predicted by LC-MS was correct.

Cyclical deformation behaviour of denture soft lining materials

OBJECTIVES

The purpose of the study was to examine and describe the deformation behaviour of five denture soft lining materials under dynamic cyclic loading over a range of applied forces using apparatus designed to simulate masticatory performance.

METHODS

Five lining materials were tested over 5-min periods using an Instron tensile testing machine that was modified to measure load and strain semi-continuously during cyclic loading.

RESULTS

Strain energy and strain energy densities and moduli values for each material were calculated. The strain energy absorbed at separate times during the cycling period demonstrated the elastic behaviour of the materials over the 5-min simulated chewing cycle.

CONCLUSIONS

All materials demonstrated elastic but not perfectly linearly elastic behaviour over the chosen loading and cycling frequency. Molloplast B absorbed most energy at the lower testing loads and Novus absorbed most energy at the higher loads.