Pre-clinical in vivo models for the screening of bone biomaterials for oral/craniofacial indications: focus on small-animal models.

Preclinical in vivo experimental studies are performed for evaluating proof-of-principle concepts, safety and possible unwanted reactions of candidate bone biomaterials before proceeding to clinical testing. Specifically, models involving small animals have been developed for screening bone biomaterials for their potential to enhance bone formation. No single model can completely recreate the anatomic, physiologic, biomechanic and functional environment of the human mouth and jaws. Relevant aspects regarding physiology, anatomy, dimensions and handling are discussed in this paper to elucidate the advantages and disadvantages of small-animal models. Model selection should be based not on the 'expertise' or capacities of the team, but rather on a scientifically solid rationale, and the animal model selected should reflect the question for which an answer is sought. The rationale for using heterotopic or orthotopic testing sites, and intraosseous, periosseous or extraskeletal defect models, is discussed. The paper also discusses the relevance of critical size defect modeling, with focus on calvarial defects in rodents. In addition, the rabbit sinus model and the capsule model in the rat mandible are presented and discussed in detail. All animal experiments should be designed with care and include sample-size and study-power calculations, thus allowing generation of meaningful data. Moreover, animal experiments are subject to ethical approval by the relevant authority. All procedures and the postoperative handling and care, including postoperative analgesics, should follow best practice.

Report of a European Society of Cardiology-European Association of Percutaneous Cardiovascular Interventions task force on the evaluation of coronary stents in Europe: executive summary.

The evaluation for European Union market approval of coronary stents falls under the Medical Device Directive that was adopted in 1993. Specific requirements for the assessment of coronary stents are laid out in supplementary advisory documents. In response to a call by the European Commission to make recommendations for a revision of the advisory document on the evaluation of coronary stents (Appendix 1 of MEDDEV 2.7.1), the European Society of Cardiology (ESC) and the European Association of Percutaneous Cardiovascular Interventions (EAPCI) established a Task Force to develop an expert advisory report. As basis for its report, the ESC-EAPCI Task Force reviewed existing processes, established a comprehensive list of all coronary drug-eluting stents that have received a CE mark to date, and undertook a systematic review of the literature of all published randomized clinical trials evaluating clinical and angiographic outcomes of coronary artery stents between 2002 and 2013. Based on these data, the TF provided recommendations to inform a new regulatory process for coronary stents. The main recommendations of the task force include implementation of a standardized non-clinical assessment of stents and a novel clinical evaluation pathway for market approval. The two-stage clinical evaluation plan includes recommendation for an initial pre-market trial with objective performance criteria (OPC) benchmarking using invasive imaging follow-up leading to conditional CE-mark approval and a subsequent mandatory, large-scale randomized trial with clinical endpoint evaluation leading to unconditional CE-mark. The data analysis from the systematic review of the Task Force may provide a basis for determination of OPC for use in future studies. This paper represents an executive summary of the Task Force's report.

Evaluation of scleral and corneal thickness in keratoconus patients

PURPOSE To determine whether the scleral stroma is affected as much as the corneal stroma in keratoconus. SETTING University Eye Clinic, Bern, Switzerland. DESIGN Comparative case-control study. METHODS Eyes with keratoconus (keratoconus group) and eyes of age-, sex-, and axial length-matched controls (control group) were analyzed. Corneal videokeratometry and pachymetry were performed using a Scheimpflug tomographer (Pentacam). For measurements of the peripheral cornea and the anterior sclera, a spectral-domain anterior segment optical coherence tomography device (Spectralis) was used. RESULTS The study group comprised 51 eyes and the control group, 50 eyes. The mean central corneal thickness in the keratoconus group was statistically significantly lower than in the control group (447.8 μm ± 57.8 [SD] versus 550.5 ± 35.5 μm) (P < .0001). No significant difference in the mean anterior scleral thickness was found between the keratoconus group and the control group (479.1 ± 43.7 μm versus 474.2 ± 43.0 μm) (P =.57). CONCLUSION Although corneal thinning was observed in keratoconus patients, the anterior scleral stroma thickness in these patients seemed to be similar to that in healthy control eyes.

Clinical evaluation of ketamine and lidocaine intravenous infusions to reduce isoflurane requirements in horses under general anaesthesia

OBJECTIVE To compare isoflurane alone or in combination with systemic ketamine and lidocaine for general anaesthesia in horses. STUDY DESIGN Prospective, randomized, blinded clinical trial. ANIMALS Forty horses (ASA I-III) undergoing elective surgery. METHODS Horses were assigned to receive isoflurane anaesthesia alone (ISO) or with ketamine and lidocaine (LKI). After receiving romifidine, diazepam, and ketamine, the isoflurane end-tidal concentration was set at 1.3% and subsequently adjusted by the anaesthetist (unaware of treatments) to maintain a light plane of surgical anaesthesia. Animals in the LKI group received lidocaine (1.5 mg kg(-1) over 10 minutes, followed by 40 microg kg(-1) minute(-1)) and ketamine (60 microg kg(-1) minute(-1)), both reduced to 65% of the initial dose after 50 minutes, and stopped 15 minutes before the end of anaesthesia. Standard clinical cardiovascular and respiratory parameters were monitored. Recovery quality was scored from one (very good) to five (very poor). Differences between ISO and LKI groups were analysed with a two-sample t-test for parametric data or a Fischer's exact test for proportions (p < 0.05 for significance). Results are mean +/- SD. RESULTS Heart rate was lower (p = 0.001) for LKI (29 +/- 4) than for ISO (34 +/- 6). End-tidal concentrations of isoflurane (ISO: 1.57% +/- 0.22; LKI: 0.97% +/- 0.33), the number of horses requiring thiopental (ISO: 10; LKI: 2) or dobutamine (ISO:8; LKI:3), and dobutamine infusion rates (ISO:0.26 +/- 0.09; LKI:0.18 +/- 0.06 microg kg(-1) minute(-1)) were significantly lower in LKI compared to the ISO group (p < 0.001). No other significant differences were found, including recovery scores. CONCLUSIONS AND CLINICAL RELEVANCE These results support the use of lidocaine and ketamine to improve anaesthetic and cardiovascular stability during isoflurane anaesthesia lasting up to 2 hours in mechanically ventilated horses, with comparable quality of recovery.

One gene but different proteins and diseases: the complexity of dystonin and bullous pemphigoid antigen 1.

Since the immunochemical identification of the bullous pemphigoid antigen 230 (BP230) as one of the major target autoantigens of bullous pemphigoid (BP) in 1981, our understanding of this protein has significantly increased. Cloning of its gene, development and characterization of animal models with engineered gene mutations or spontaneous mouse mutations have revealed an unexpected complexity of the gene encoding BP230. The latter, now called dystonin (DST), is composed of at least 100 exons and gives rise to three major isoforms, an epithelial, a neuronal and a muscular isoform, named BPAG1e (corresponding to the original BP230), BPAG1a and BPAG1b, respectively. The various BPAG1 isoforms play a key role in fundamental processes, such as cell adhesion, cytoskeleton organization, and cell migration. Genetic defects of BPAG1 isoforms are the culprits of epidermolysis bullosa and complex, devastating neurological diseases. In this review, we summarize recent advances of our knowledge about several BPAG1 isoforms, their role in various biological processes and in human diseases.

Evaluation of coagulation and fibrinolysis in horses with atrial fibrillation

OBJECTIVE To evaluate horses with atrial fibrillation for hypercoagulability; plasma D-dimer concentrations, as a marker of a procoagulant state; and a relationship between coagulation profile results and duration of atrial fibrillation or presence of structural heart disease. DESIGN Case-control study. ANIMALS Plasma samples from 42 horses (25 with atrial fibrillation and 17 without cardiovascular or systemic disease [control group]). PROCEDURES Results of hematologic tests (ie, plasma fibrinogen and D-dimer concentrations, prothrombin and activated partial thromboplastin times, and antithrombin activity) in horses were recorded to assess coagulation and fibrinolysis. Historical and clinical variables, as associated with a hypercoagulable state in other species, were also recorded. RESULTS Horses with atrial fibrillation and control horses lacked clinical signs of hypercoagulation or thromboembolism. Compared with control horses, horses with atrial fibrillation had significantly lower antithrombin activity. No significant differences in plasma fibrinogen and D-dimer concentrations and prothrombin and activated partial thromboplastin times existed between horse groups. In horses with atrial fibrillation versus control horses, a significantly larger proportion had an abnormal plasma D-dimer concentration (10/25 vs 2/17), test results indicative of subclinical activated coagulation (18/25 vs 6/17), or abnormal coagulation test results (25/121 vs 7/85), respectively. CONCLUSIONS AND CLINICAL RELEVANCE Horses with atrial fibrillation did not have clinical evidence of a hypercoagulable state, but a higher proportion of horses with atrial fibrillation, compared with control horses, did have subclinical activated coagulation on the basis of standard coagulation test results.

STUDIES ON THE PATTERNS OF NUCLEOTIDE AND AMINO ACID SUBSTITUTION (ELECTROPHORESIS, MUTATION RATE, SELECTION, BASE, COMPOSITION)

Theoretical and empirical studies were conducted on the pattern of nucleotide and amino acid substitution in evolution, taking into account the effects of mutation at the nucleotide level and purifying selection at the amino acid level. A theoretical model for predicting the evolutionary change in electrophoretic mobility of a protein was also developed by using information on the pattern of amino acid substitution. The specific problems studied and the main results obtained are as follows: (1) Estimation of the pattern of nucleotide substitution in DNA nuclear genomes. The pattern of point mutations and nucleotide substitutions among the four different nucleotides are inferred from the evolutionary changes of pseudogenes and functional genes, respectively. Both patterns are non-random, the rate of change varying considerably with nucleotide pair, and that in both cases transitions occur somewhat more frequently than transversions. In protein evolution, substitution occurs more often between amino acids with similar physico-chemical properties than between dissimilar amino acids. (2) Estimation of the pattern of nucleotide substitution in RNA genomes. The majority of mutations in retroviruses accumulate at the reverse transcription stage. Selection at the amino acid level is very weak, and almost non-existent between synonymous codons. The pattern of mutation is very different from that in DNA genomes. Nevertheless, the pattern of purifying selection at the amino acid level is similar to that in DNA genomes, although selection intensity is much weaker. (3) Evaluation of the determinants of molecular evolutionary rates in protein-coding genes. Based on rates of nucleotide substitution for mammalian genes, the rate of amino acid substitution of a protein is determined by its amino acid composition. The content of glycine is shown to correlate strongly and negatively with the rate of substitution. Empirical formulae, called indices of mutability, are developed in order to predict the rate of molecular evolution of a protein from data on its amino acid sequence. (4) Studies on the evolutionary patterns of electrophoretic mobility of proteins. A theoretical model was constructed that predicts the electric charge of a protein at any given pH and its isoelectric point from data on its primary and quaternary structures. Using this model, the evolutionary change in electrophoretic mobilities of different proteins and the expected amount of electrophoretically hidden genetic variation were studied. In the absence of selection for the pI value, proteins will on the average evolve toward a mildly basic pI. (Abstract shortened with permission of author.) ^

Bayesian models for the analysis of genetic structure when populations are correlated

Motivation: Population allele frequencies are correlated when populations have a shared history or when they exchange genes. Unfortunately, most models for allele frequency and inference about population structure ignore this correlation. Recent analytical results show that among populations, correlations can be very high, which could affect estimates of population genetic structure. In this study, we propose a mixture beta model to characterize the allele frequency distribution among populations. This formulation incorporates the correlation among populations as well as extending the model to data with different clusters of populations. Results: Using simulated data, we show that in general, the mixture model provides a good approximation of the among-population allele frequency distribution and a good estimate of correlation among populations. Results from fitting the mixture model to a dataset of genotypes at 377 autosomal microsatellite loci from human populations indicate high correlation among populations, which may not be appropriate to neglect. Traditional measures of population structure tend to over-estimate the amount of genetic differentiation when correlation is neglected. Inference is performed in a Bayesian framework.

Sexual orientation and sexual behavior patterns: Evaluation of agreement and variation in a cohort of male, African American drug users in Houston, TX

Background. Sexual orientation and sexual behavior among men have shown disagreement in past studies. The term "on the down low" has been adopted by many to describe "straight" identifying men who have sex with men but do not inform their primary female partner. Methods. This secondary analysis of data collected from the "DASH Project---A Hepatitis B Vaccine Model for HIV Vaccine Trial in Drug Users," assessed sexual behavior patterns among African American drug-using men over time. Using a screener questionnaire to determine sexual orientation and sexual behavior of the men, the study specifically evaluated "straight" identified men who have sex with women only (MSW) to determine what factors were associated with sexual behavior variation to include men during follow-up. The Fisher's Exact Test was used to evaluate the factors. Results. Variation of sexual behavior was highest among "bisexual" identified men followed by "gay" identified men. Fifteen of the original 593 "straight" and MSW men had sexual behavior variation to include men. In the analysis of "straight" and MSW men with variation in sexual behavior compared to those who did not, living on the streets, greater number of sexual partners, trading sex for drugs, and trading sex for money were associated with sexual behavior variation (all p-values <0.01). Conclusions. The factors were only associated when considering the interview when the variation occurred. The same factors at screening were not predictive of sexual behavior variation in the future. Environmental factors, such as living situation, appear to play a role in sexual behavior variations in "straight" and MSW men. ^ Keywords. sexual behavior, sexual orientation, Fisher's Exact Test^

Analysis of prognostic factors for the development of metastases and survival in renal cell carcinoma patients

Introduction and objective. A number of prognostic factors have been reported for predicting survival in patients with renal cell carcinoma. Yet few studies have analyzed the effects of those factors at different stages of the disease process. In this study, different stages of disease progression starting from nephrectomy to metastasis, from metastasis to death, and from evaluation to death were evaluated. ^ Methods. In this retrospective follow-up study, records of 97 deceased renal cell carcinoma (RCC) patients were reviewed between September 2006 to October 2006. Patients with TNM Stage IV disease before nephrectomy or with cancer diagnoses other than RCC were excluded leaving 64 records for analysis. Patient TNM staging, Furhman Grade, age, tumor size, tumor volume, histology and patient gender were analyzed in relation to time to metastases. Time from nephrectomy to metastasis, TNM staging, Furhman Grade, age, tumor size, tumor volume, histology and patient gender were tested for significance in relation to time from metastases to death. Finally, analysis of laboratory values at time of evaluation, Eastern Cooperative Oncology Group performance status (ECOG), UCLA Integrated Staging System (UISS), time from nephrectomy to metastasis, TNM staging, Furhman Grade, age, tumor size, tumor volume, histology and patient gender were tested for significance in relation to time from evaluation to death. Linear regression and Cox Proportional Hazard (univariate and multivariate) was used for testing significance. Kaplan-Meier Log-Rank test was used to detect any significance between groups at various endpoints. ^ Results. Compared to negative lymph nodes at time of nephrectomy, a single positive lymph node had significantly shorter time to metastasis (p<0.0001). Compared to other histological types, clear cell histology had significant metastasis free survival (p=0.003). Clear cell histology compared to other types (p=0.0002 univariate, p=0.038 multivariate) and time to metastasis with log conversion (p=0.028) significantly affected time from metastasis to death. A greater than one year and greater than two year metastasis free interval, compared to patients that had metastasis before one and two years, had statistically significant survival benefit (p=0.004 and p=0.0318). Time from evaluation to death was affected by greater than one year metastasis free interval (p=0.0459), alcohol consumption (p=0.044), LDH (p=0.006), ECOG performance status (p<0.001), and hemoglobin level (p=0.0092). The UISS risk stratified the patient population in a statistically significant manner for survival (p=0.001). No other factors were found to be significant. ^ Conclusion. Clear cell histology is predictive for both time to metastasis and metastasis to death. Nodal status at time of nephrectomy may predict risk of metastasis. The time interval to metastasis significantly predicts time from metastasis to death and time from evaluation to death. ECOG performance status, and hemoglobin levels predicts survival outcome at evaluation. Finally, UISS appropriately stratifies risk in our population. ^

The application of latent variable models to the assessment of determinants of HIV risk behavior

Studies on the relationship between psychosocial determinants and HIV risk behaviors have produced little evidence to support hypotheses based on theoretical relationships. One limitation inherent in many articles in the literature is the method of measurement of the determinants and the analytic approach selected. ^ To reduce the misclassification associated with unit scaling of measures specific to internalized homonegativity, I evaluated the psychometric properties of the Reactions to Homosexuality scale in a confirmatory factor analytic framework. In addition, I assessed the measurement invariance of the scale across racial/ethnic classifications in a sample of men who have sex with men. The resulting measure contained eight items loading on three first-order factors. Invariance assessment identified metric and partial strong invariance between racial/ethnic groups in the sample. ^ Application of the updated measure to a structural model allowed for the exploration of direct and indirect effects of internalized homonegativity on unprotected anal intercourse. Pathways identified in the model show that drug and alcohol use at last sexual encounter, the number of sexual partners in the previous three months and sexual compulsivity all contribute directly to risk behavior. Internalized homonegativity reduced the likelihood of exposure to drugs, alcohol or higher numbers of partners. For men who developed compulsive sexual behavior as a coping strategy for internalized homonegativity, there was an increase in the prevalence odds of risk behavior. ^ In the final stage of the analysis, I conducted a latent profile analysis of the items in the updated Reactions to Homosexuality scale. This analysis identified five distinct profiles, which suggested that the construct was not homogeneous in samples of men who have sex with men. Lack of prior consideration of these distinct manifestations of internalized homonegativity may have contributed to the analytic difficulty in identifying a relationship between the trait and high-risk sexual practices. ^

Disparities in asthma prevalence: The influence of sociodemographic and workplace factors

Asthma is a serious and continuing health problem that affects millions of Americans. Our study was conducted in response to this serious health problem and for purposes of addressing the issue of potential health disparities as outlined in Healthy People 2010. Data from sub-populations of subjects who participated in the National Health and Nutrition Examination Survey (NHANES) from 1999-2004 were used to complete the following specific aims: (1) to update nationally-based estimates of the prevalence of current and lifetime (ever) asthma among adults in the United States (U.S.) and describe by gender the relationships between potential risk factors (e.g., sociodemographics and lifestyle) and asthma; (2) to describe demographic characteristics among working adults in the U.S. and update estimates of the prevalence of asthma in this sub-population, stratified by occupation and industry; and 3) to determine the utility of adapting a population-based Job Exposure Matrix (JEM) for classifying workplace exposures to asthmagens. ^ Our findings suggest the prevalence of asthma among U.S. adults is continuing to rise, with women having a higher prevalence of asthma than men. Living below the poverty threshold, obesity, and prior history of smoking remain important determinants of asthma. Our study also adds to the increasing evidence that health care workers (HCWs) and those employed in education remain at high risk and that appropriate evaluation and control measures need to be implemented. Over 78% of HCWs and 71% of teachers in our study were females suggesting that further exploration of gender-specific risk factors of asthma in working populations is needed. ^ Our study also addressed the feasibility of adapting a population-based asthma-specific JEM to NHANES (1999-2004). We were not able to apply the asthma-specific JEM due to the broad occupational categories within NHANES. This represents a missed opportunity to examine the association between workplace exposures and asthma in U.S. working adults. However, we have identified steps that may be implemented in future population-based studies that would allow the asthma-specific JEM (and other population-based job exposure matrices) to be used in future studies of the U.S. working population.^

THE EVALUATION OF PUBLIC HEALTH COMPONENTS OF INTERNATIONAL DISASTER RELIEF OPERATIONS: INDOCHINESE REFUGEES IN THAILAND, 1979-1982

Refugee populations suffer poor health status and yet the activities of refugee relief agencies in the public health sector have not been subjected previously to comprehensive evaluation. The purpose of this study was to examine the effectiveness and cost of the major public health service inputs of the international relief operation for Indochinese refugees in Thailand coordinated by the United Nations High Commissioner for Refugees (UNHCR). The investigator collected data from surveillance reports and agency records pertaining to 11 old refugee camps administered by the Government of Thailand Ministry of Interior (MOI) since an earlier refugee influx, and five new Khmer holding centers administered directly by UNHCR, from November, 1979, to March, 1982.^ Generous international funding permitted UNHCR to maintain a higher level of public health service inputs than refugees usually enjoyed in their countries of origin or than Thais around them enjoyed. Annual per capita expenditure for public health inputs averaged approximately US$151. Indochinese refugees in Thailand, for the most part, had access to adequate general food rations, to supplementary feeding programs, and to preventive health measures, and enjoyed high-quality medical services. Old refugee camps administered by MOI consistently received public health inputs of lower quantity and quality compared with new UNHCR-administered holding centers, despite comparable per capita expenditure after both types of camps had stabilized (static phase).^ Mortality and morbidity rates among new Khmer refugees were catastrophic during the emergency and transition phases of camp development. Health status in the refugee population during the static phase, however, was similar to, or better than, health status in the refugees' countries of origin or the Thai communities surrounding the camps. During the static phase, mortality and morbidity generally remained stable at roughly the same low levels in both types of camps.^ Furthermore, the results of multiple regression analyses demonstrated that combined public health inputs accounted for from one to 23 per cent of the variation in refugee mortality and morbidity. The direction of associations between some public health inputs and specific health outcome variables demonstrated no clear pattern. ^

The impact of communication and cultural diversity in utilizing dental services among Saudi Arabian students in U.S.A.

Objectives: The purpose of this study is to understand the perceived effects of patient-dental staff communication and cultural diversity on the utilization of dental services in the U.S. by Saudi Arabian students who live in the U.S. and enrolled into the King Abdullah Scholarship program. Methods: The study design was an analytical cross-sectional study. Data for this study was obtained from the Saudi Dental Servicers Utilization Survey, a voluntary internet survey available online for one month through Facebook. Ordered logistic regression analyses and multinomial logistic regression analyses were used to measure the relationships between patient-dental staff communication and cultural diversity on the utilization of dental services. Results: Eight hundred and forty-seven responses were analyzed for this study. Overall, the majority of Saudi students reported having excellent communication experience with dental providers in the U.S. More than 58% of respondents reported at least one regular dental visit last year. Factors that influenced the use of regular dental care were: dentist's explanation of treatment plan, response of dental staff to patient's needs, respectful and polite dental staff, dental staff kindness, availability of up-to-date equipment, and overall communication with dentist. However, the utilization of emergency dental care was not associated with any measurement of patient-dental provider communication. Overall future utilization of dental care is associated with all aspects of patient-dental staff communication measured in this survey. Furthermore, more utilization of regular dental care was related to respondent's perception of the importance of trustworthiness dental staff and the importance of a dentist's reputation was only marginally associated. Respondent's perception of dentist's reputation was associated with more use of emergency dental services. Respondents are more likely to anticipate using dental care in the future if they perceived trustworthiness dental staff, and the dentist's reputation as influencing factors to their usage of dental services. Conclusions: Patient-dental staff communication was partially associated with utilization of regular dental care, not associated with utilization of emergency dental care, and broadly associated with anticipated future utilization of dental care. In addition, trustworthy dental staff, and a dentist's reputation were considered to be strong influencing factors towards utilization of dental services.^