Functional, structural and molecular plasticity of mammalian skeletal muscle in response to exercise stimuli

Biological systems have acquired effective adaptive strategies to cope with physiological challenges and to maximize biochemical processes under imposed constraints. Striated muscle tissue demonstrates a remarkable malleability and can adjust its metabolic and contractile makeup in response to alterations in functional demands. Activity-dependent muscle plasticity therefore represents a unique model to investigate the regulatory machinery underlying phenotypic adaptations in a fully differentiated tissue. Adjustments in form and function of mammalian muscle have so far been characterized at a descriptive level, and several major themes have evolved. These imply that mechanical, metabolic and neuronal perturbations in recruited muscle groups relay to the specific processes being activated by the complex physiological stimulus of exercise. The important relationship between the phenotypic stimuli and consequent muscular modifications is reflected by coordinated differences at the transcript level that match structural and functional adjustments in the new training steady state. Permanent alterations of gene expression thus represent a major strategy for the integration of phenotypic stimuli into remodeling of muscle makeup. A unifying theory on the molecular mechanism that connects the single exercise stimulus to the multi-faceted adjustments made after the repeated impact of the muscular stress remains elusive. Recently, master switches have been recognized that sense and transduce the individual physical and chemical perturbations induced by physiological challenges via signaling cascades to downstream gene expression events. Molecular observations on signaling systems also extend the long-known evidence for desensitization of the muscle response to endurance exercise after the repeated impact of the stimulus that occurs with training. Integrative approaches involving the manipulation of single factors and the systematic monitoring of downstream effects at multiple levels would appear to be the ultimate method for pinpointing the mechanism of muscle remodeling. The identification of the basic relationships underlying the malleability of muscle tissue is likely to be of relevance for our understanding of compensatory processes in other tissues, species and organisms.

Erosive tooth wear: diagnosis, risk factors and prevention

PURPOSE: To provide an overview on diagnosis, risk factors and prevention of erosive tooth wear, which is becoming an increasingly important factor when considering the long- term health of the dentition. RESULTS: Awareness of dental erosion by the public is still not widespread due to the cryptic nature of this slowly progressing condition. Smooth silky-glazed appearance with the absence of perikymata and intact enamel along the gingival margin, with cupping and grooving on occlusal surfaces are some typical signs of enamel erosion. In later stages, it is sometimes difficult to distinguish between the influences of erosion, attrition or abrasion during a clinical examination. Biological, behavioral and chemical factors all come into play, which over time, may either wear away the tooth surface, or potentially protect it. In order to assess the risk factors, patient should record their dietary intake for a distinct period of time. Based on these analyses, an individually tailored preventive program may be suggested to patients. It may comprise dietary advice, optimization of fluoride regimes, stimulation of salivary flow rate, use of buffering medicaments and particular motivation for non-destructive tooth brushing habits. The frequent use of fluoride gel and fluoride mouthrinse in addition to fluoride toothpaste offers the opportunity to minimize abrasion of tooth substance.

Extrinsic causes of erosion. Diet. Chemical factors

pH value, calcium, and phosphate and to a lesser extent fluoride content of a drink or foodstuff are important factors explaining erosive attack. They determine the degree of saturation with respect to tooth minerals, which is the driving force for dissolution. Solutions oversaturated with respect to dental hard tissue will not dissolve it. Addition of calcium (and phosphate) salts to erosive drinks showed protection of surface softening. Today, several Ca-enriched soft drinks are on the market or products with naturally high content in Ca and P are available (such as yoghurt), which do not soften the dental hard tissue. The greater the buffering capacity of the drink or food, the longer it will take for the saliva to neutralize the acid. The buffer capacity of a solution has a distinct effect on the erosive attack when the solution remains adjacent to the tooth surface and is not replaced by saliva. A higher buffer capacity of a drink or foodstuff will enhance the processes of dissolution because more ions from the tooth mineral are needed to render the acid inactive for further demineralization. Further, the amount of drink in the mouth in relation to the amount of saliva present will modify the process of dissolution. There is no clear-cut critical pH for erosion as there is for caries. Even at a low pH, it is possible that other factors are strong enough to prevent erosion.

Long-term effects of heart transplantation: the gap between physical performance and emotional well-being

The purpose of our study was to assess physical and emotional factors in heart transplant patients. A prospective design was used to compare patients' physical symptoms, emotional complaints, and restrictions at admission to the waiting list, immediately after, and 1 and 5 years after heart transplantation. Thirty-three patients were included (30 male, 3 female) in the study. Their mean age at admission was 48 +/- 10.2 years. Of these, 23 suffered from cardiomyopathy, 8 from coronary heart disease, and 2 from valvular insufficiency. At admission, the patients suffered from symptoms of cardiac insufficiency, and were restricted in sports, gardening, hobbies, sexual life, job, food-intake, and mobility. More than three-fourths rated their physical and emotional status as moderate to poor. Emotionally, they suffered from irritability, restlessness, depression, psychic lability, lowered drive, lack of social contact, low self-esteem, and anxiety. At the end of rehabilitation (4-8 weeks after the operation), all physical and emotional complaints, as well as restrictions had significantly decreased (p < 0.0001 to p < 0.001), except for trembling, numbness of hands/feet, and food-intake. One year postoperatively, patients reported even fewer physical complaints (p < 0.01). Three-fourths rated their physical and emotional status good or excellent. Five years postoperatively--in contrast to physical status, restrictions, and physical complaints--the emotional complaints had increased significantly (p < 0.0001). Patients reported excellent physical performance up to 5 years postoperatively. On the other hand, the study revealed that their emotional well-being had significantly deteriorated from 1 to 5 years postoperatively. Attention should, therefore, not only be paid to the good physical health of the survivors, but also to the worsening of their emotional status.

Erosion--diagnosis and risk factors

Dental erosion is a multifactorial condition: The interplay of chemical, biological and behavioural factors is crucial and helps explain why some individuals exhibit more erosion than others. The erosive potential of erosive agents like acidic drinks or foodstuffs depends on chemical factors, e.g. pH, titratable acidity, mineral content, clearance on tooth surface and on its calcium-chelation properties. Biological factors such as saliva, acquired pellicle, tooth structure and positioning in relation to soft tissues and tongue are related to the pathogenesis of dental erosion. Furthermore, behavioural factors like eating and drinking habits, regular exercise with dehydration and decrease of salivary flow, excessive oral hygiene and, on the other side, an unhealthy lifestyle, e.g. chronic alcoholism, are predisposing factors for dental erosion. There is some evidence that dental erosion is growing steadily. To prevent further progression, it is important to detect this condition as early as possible. Dentists have to know the clinical appearance and possible signs of progression of erosive lesions and their causes such that adequate preventive and, if necessary, therapeutic measures can be initiated. The clinical examination has to be done systematically, and a comprehensive case history should be undertaken such that all risk factors will be revealed.

Assessment of soil erosion vulnerability in rural communities in the vicinity of Motozintla de Mendoza, Chiapas, Mexico : a physical and sociological approach

Soil erosion is a natural geological phenomenon resulting from removal and transportation of soil particles by water, wind, ice and gravity. As soil erosion may be affected from cultural factors as well. The physical and social phenomena of soil erosion are researched in six communities in the upper part of Rio Grijalva Basin in the vicinity of Motozintla de Mendoza, Chiapas, Mexico. For this study, the USDA RUSLE model was applied to estimate soil erosion rates in the six communities based on the available data. The RUSLE model is based on soil properties, topography, and land cover and management factors. These results showed that estimated soil erosion rates ranged from a high of 2,050 metric ton ha-1 yr-1 to a low of 100 metric ton ha-1 yr-1. A survey concerning knowledge, attitudes and practices (KAP) related to soil erosion was also conducted in all 236 households in the six communities. The main findings of the KAP survey were: 69% of respondents did not know what soil erosion was, while over 40% of the population perceived that hurricanes are the biggest factors that cause soil erosion, and about 20 % of the interviewees said that the landslides are the consequences of the soil erosion. People in communities did not perceive cultural factors as important in conservation efforts for reduce vulnerability to erosion; therefore, the results obtained are suggested to be useful for informing efforts to educate stakeholders.

Hamilton-Waterloo problem with triangle and C9 factors

The Hamilton-Waterloo problem and its spouse-avoiding variant for uniform cycle sizes asks if Kv, where v is odd (or Kv - F, if v is even), can be decomposed into 2-factors in which each factor is made either entirely of m-cycles or entirely of n-cycles. This thesis examines the case in which r of the factors are made up of cycles of length 3 and s of the factors are made up of cycles of length 9, for any r and s. We also discuss a constructive solution to the general (m,n) case which fixes r and s.

Mechanical and Chemical Stability of Injection-Molded Microcantilevers Used for Sensing

Ultraviolet-ozone treatment is used as a standard surface cleaning procedure for removal of molecular organic contamination from analytical and sensing devices. Here, it is applied for injection-molded polymer microcantilevers before characterization and sensing experiments. This article examines the effects of the surface cleaning process using commercial equipment, in particular on the performance and mechanical properties of the cantilevers. It can be shown that the first chemical aging process essentially consist of the cross linking of the polymer chains together with a physical aging of the material. For longer exposure, the expected thermo-oxidative formation of carbonyl groups sets in and an exposure dependent chemical degradation can be detected. A process time of 20 min was found suitable as a trade-off between cleaning and stability

Being Bullied: Associated Factors in Children and Adolescents 8 to 18 Years Old in 11 European Countries

OBJECTIVES. To analyze the prevalence of bullying victims among children and adolescents aged 8 to 18 years in 11 European countries and to investigate the associated sociodemographic, physical, and psychosocial factors. METHODS. Being a bullying victim was measured by using the social acceptance (bullying) scale from the Kidscreen-52, a health-related quality-of-life questionnaire administered to 16 210 children and adolescents aged 8 to 18 and their parents in postal or school-based surveys in 11 European countries. Standardized mean differences (effect size) were computed to measure the percentage of children/adolescents scoring 1 SD below the mean on the Kidscreen bullying scale. Logistic regression models were used to determine which sociodemographic, physical, and psychosocial factors were associated with being bullied. RESULTS. The percentage of children being bullied was 20.6% for the entire sample, ranging from 10.5% in Hungary to 29.6% in the United Kingdom. In almost all countries the factors most strongly associated with being bullied were younger age, having probable mental health problems, having a low score on the Kidscreen-52 moods and emotions dimensions, and poor social support. Using the grand mean for all countries as the reference category, there was an above-average likelihood of children or adolescents reporting that they had been victims of bullying in 5 countries (Austria, Netherlands, Spain, Switzerland, and the United Kingdom), and a below-average likelihood in 3 countries (France, Greece, Hungary). CONCLUSIONS. This study indicated considerable variation between countries in the prevalence of those perceiving themselves to be victims of bullying but also revealed a clear profile of those likely to be bullied. The study also suggests that the Kidscreen bullying scale could be useful in identifying potential bullying victims.

Shifts in microbial communities do not explain the response of grassland ecosystem function to plant functional composition and rainfall change

Ecosystem functioning in grasslands is regulated by a range of biotic and abiotic factors, and the role of microbial communities in regulating ecosystem function has been the subject of much recent scrutiny. However, there are still knowledge gaps regarding the impacts of rainfall and vegetation change upon microbial communities and the implications of these changes for ecosystem functioning. We investigated this issue using data from an experimental mesotrophic grassland study in south-east England, which had been subjected to four years of rainfall and plant functional composition manipulations. Soil respiration, nitrogen and phosphorus stocks were measured, and the abundance and community structure of soil microbes were characterised using quantitative PCR and multiplex-TRFLP analysis, respectively. Bacterial community structure was strongly related to the plant functional composition treatments, but not the rainfall treatment. However, there was a strong effect of both rainfall change and plant functional group upon bacterial abundance. There was also a weak interactive effect of the two treatments upon fungal community structure, although fungal abundance was not affected by either treatment. Next, we used a statistical approach to assess whether treatment effects on ecosystem function were regulated by the microbial community. Our results revealed that ecosystem function was influenced by the experimental treatments, but was not related to associated changes to the microbial community. Overall, these results indicate that changes in fungal and bacterial community structure and abundance play a relatively minor role in determining grassland ecosystem function responses to precipitation and plant functional composition change, and that direct effects on soil physical and chemical properties and upon plant and microbial physiology may play a more important role.

Prevalence of erosive tooth wear and associated factors in a group of Mexican adolescents.

BACKGROUND Erosive tooth wear is the irreversible loss of dental hard tissue as a result of chemical processes. When the surface of a tooth is attacked by acids, the resulting loss of structural integrity leaves a softened layer on the tooth's surface, which renders it vulnerable to abrasive forces. The authors' objective was to estimate the prevalence of erosive tooth wear and to identify associated factors in a sample of 14- to 19-year-old adolescents in Mexico. METHODS The authors performed a cross-sectional study on a convenience sample (N = 417) of adolescents in a school in Mexico City, Mexico. The authors used a questionnaire and an oral examination performed according to the Lussi index. RESULTS The prevalence of erosive tooth wear was 31.7% (10.8% with exposed dentin). The final logistic regression model included age (P < .01; odds ratio [OR], 1.64; 95% confidence interval [CI], 1.26-2.13), high intake of sweet carbonated drinks (P = .03; OR, 1.81; 95% CI, 1.06-3.07), and xerostomia (P = .04; OR, 2.31; 95% CI, 1.05-5.09). CONCLUSIONS Erosive tooth wear, mainly on the mandibular first molars, was associated with age, high intake of sweet carbonated drinks, and xerostomia. PRACTICAL IMPLICATIONS Knowledge regarding erosive tooth wear in adolescents with relatively few years of exposure to causal factors will increase the focus on effective preventive measures, the identification of people at high risk, and early treatment.

Evaluation of epidemiological and clinical factors in survival of patients with de novo myelodysplastic syndrome at the University of Texas MD Anderson cancer center

Little is known about epidemiological markers that are associated with survival of patients with myelodysplastic syndromes (MDS). We conducted a secondary case-based analysis of 465 de novo MDS patients from the University of Texas MD Anderson Cancer Center (UTMDACC). We investigated the association between demographic as well as occupational exposure markers and survival while incorporating known clinical markers of prognosis. In our patient population, 60.6% were men and the majority were white (93.1%). The distribution of MDS subtypes by the French–American–British (FAB) classification was 81 (19%) refractory anemia (RA), 46 (9.9%) refractory anemia with ringed sideroblasts (RARS), 57 (12.3%) chronic myelomonocytic leukemia (CMML), 173 (37.2%) RA with excess blasts (RAEB), and 86 (18.5%) RAEB in transformation (RAEBT). We found that those older at diagnosis (> 60 years of age) (HR = 1.68, CI = 1.26-2.25) were at a higher risk of dying compared to younger patients. Similarly, high pack years of smoking (>= 30 pack years of smoking) (HR = 1.34, CI = 1.02-1.74), and agricultural chemical exposure (HR = 1.61, CI = 1.05-2.46) were significantly associated with overall lower survival when compared to patients with none or medium exposures. Among clinical markers, greater than 5% bone marrow blasts (HR = 1.81 CI = 1.27-2.56), poor cytogenetics (HR = 3.20, CI = 2.37-4.33)), and platelet cytopenias (<100000/ul) (HR = 1.46, CI = 1.11-1.92) were also significantly associated with overall MDS survival.^ The identification of epidemiological markers could help physicians stratify patients and customize treatment strategies to improve the outcome of MDS based on patient lifestyle information such as smoking exposure and agrochemical exposure. We hope that this study highlights the impact of these exposures in MDS prognosis.^

Annotated record and chemical composition of iron-manganese nodules from the Baltic Sea

Iron-manganese concretions, closely related to lacustrine ores and deep sea manganese nodules, are presently forming in different parts of Gulfs of Bothnia and Finland. They can be divided according to physical form into three distinct groups: (1) round pea-shaped concretions, (2) ring-shaped concrections, and (3) flat sheets and crusts of concretionary material. A definite correlation was found to exist between the form i.e. type of concretions and their chemical composition (Mn/Fe ratio). Trace element concentrations were generally rather high, although not as high as in deep sea manganese nodules. X-ray and DTA was used to study the mineralogy and crystal structure of the concretions. Surface concentrations and geographical distribution of the concretions were estimated on the basis of samples, diving observations and echo-grams.