Impaired 11 beta-hydroxysteroid dehydrogenase contributes to renal sodium avidity in cirrhosis: hypothesis or fact?

Exaggerated renal sodium retention with concomitant potassium loss is a hallmark of cirrhosis and contributes to the accumulation of fluid as ascites, pleural effusion, or edema. This apparent mineralocorticoid effect is only partially explained by increased aldosterone concentrations. I present evidence supporting the hypothesis that cortisol confers mineralocorticoid action in cirrhosis. The underlying molecular pathology for this mineralocorticoid receptor (MR) activation by cortisol is a reduced activity of the 11 beta-hydroxysteroid dehydrogenase type 2, an enzyme protecting the MR from promiscuous activation by cortisol in healthy mammalians.

Power Calculations for Preclinical Studies Using a K-Sample Rank Test and the Lehmann Alternative Hypothesis

Power calculations in a small sample comparative study, with a continuous outcome measure, are typically undertaken using the asymptotic distribution of the test statistic. When the sample size is small, this asymptotic result can be a poor approximation. An alternative approach, using a rank based test statistic, is an exact power calculation. When the number of groups is greater than two, the number of calculations required to perform an exact power calculation is prohibitive. To reduce the computational burden, a Monte Carlo resampling procedure is used to approximate the exact power function of a k-sample rank test statistic under the family of Lehmann alternative hypotheses. The motivating example for this approach is the design of animal studies, where the number of animals per group is typically small.

Extrinsic causes of erosion. Oral hygiene products and acidic medicines

Acidic or EDTA-containing oral hygiene products and acidic medicines have the potential to soften dental hard tissues. The low pH of oral care products increases the chemical stability of some fluoride compounds, favors the incorporation of fluoride ions in the lattice of hydroxyapatite and the precipitation of calcium fluoride on the tooth surface. This layer has some protective effect against an erosive attack. However, when the pH is too low or when no fluoride is present these protecting effects are replaced by direct softening of the tooth surface. Xerostomia or oral dryness can occur as a consequence of medication such as tranquilizers, anti-histamines, anti-emetics and anti-parkinsonian medicaments or of salivary gland dysfunction e.g. due to radiotherapy of the oral cavity and the head and neck region. Above all, these patients should be aware of the potential demineralization effects of oral hygiene products with low pH and high titratable acids. Acetyl salicylic acid taken regularly in the form of multiple chewable tablets or in the form of headache powder as well chewing hydrochloric acids tablets for treatment of stomach disorders can cause erosion. There is most probably no direct association between asthmatic drugs and erosion on the population level. Consumers, patients and health professionals should be aware of the potential of tooth damage not only by oral hygiene products and salivary substitutes but also by chewable and effervescent tablets. Additionally, it can be assumed that patients suffering from xerostomia should be aware of the potential effects of oral hygiene products with low pH and high titratable acids.

Multiple Testing With an Empirical Alternative Hypothesis

An optimal multiple testing procedure is identified for linear hypotheses under the general linear model, maximizing the expected number of false null hypotheses rejected at any significance level. The optimal procedure depends on the unknown data-generating distribution, but can be consistently estimated. Drawing information together across many hypotheses, the estimated optimal procedure provides an empirical alternative hypothesis by adapting to underlying patterns of departure from the null. Proposed multiple testing procedures based on the empirical alternative are evaluated through simulations and an application to gene expression microarray data. Compared to a standard multiple testing procedure, it is not unusual for use of an empirical alternative hypothesis to increase by 50% or more the number of true positives identified at a given significance level.

Mast fruiting of large ectomycorrhizal African rain forest trees: importance of dry season intensity, and the resource limitation hypothesis

Mast fruiting is a distinctive reproductive trait in trees. This rain forest study, at a nutrient-poor site with a seasonal climate in tropical Africa, provides new insights into the causes of this mode of phenological patterning. •  At Korup, Cameroon, 150 trees of the large, ectomycorrhizal caesalp, Microberlinia bisulcata, were recorded almost monthly for leafing, flowering and fruiting during 1995–2000. The series was extended to 1988–2004 with less detailed data. Individual transitions in phenology were analysed. •  Masting occurred when the dry season before fruiting was drier, and the one before that was wetter, than average. Intervals between events were usually 2 or 3 yr. Masting was associated with early leaf exchange, followed by mass flowering, and was highly synchronous in the population. Trees at higher elevation showed more fruiting. Output declined between 1995 and 2000. •  Mast fruiting in M. bisulcata appears to be driven by climate variation and is regulated by internal tree processes. The resource-limitation hypothesis was supported. An ‘alternative bearing’ system seems to underlie masting. That ectomycorrhizal habit facilitates masting in trees is strongly implied.

Short-term effects of hygiene education for preschool (kindergarten) children: a clinical study

AIM: To evaluate the outcomes of short (15 minutes) oral hygiene vs. hand hygiene education for preschool children 4 weeks after these interventions. MATERIALS AND METHODS: Sixty-one preschool children (age range 4-6 years) attending four kindergarten classes participated in a 15-minute health education programme on the importance of body cleanliness for general health. In addition, specific instructions on oral hygiene were provided for two randomly selected classes (30 children), while the remaining two classes (31 children) were given instruction of hand and nail cleaning. The oral hygiene status was assessed usingthe plaque control record (PCR). The cleanliness of the hands and fingernails was determined using a hand hygiene index (HHI) and a nail hygiene index (NHI). All three parameters were assessed before the intervention as well as 4 weeks thereafter. RESULTS: Four weeks after education, the PCR had improved for all children from 79.95% to 72.35% (p < 0.001). The NHI had improved from 74.91% to 61.71% (p < 0.001). In addition, the mean PCR of the children given oral hygiene instruction decreased from 83.67% to 72.40%, while the mean PCR of the children given hand and nail cleaning instruction decreased from 76.23% to 72.29% (interaction effect 'time x type of instruction': p = 0.044). Girls' PCR improved significantly more than boys' PCR (Girls, 80.98 vs. 69.71; boys, 78.33 vs. 75.31; p = 0.021). CONCLUSIONS: The results of the study show that even a short, school-based educational intervention at an early age may affect children's oral health promotion significantly. Teachers should, therefore, be encouraged to educate children from an early age about oral hygiene promotion.

Pain and swelling after periapical surgery related to oral hygiene and smoking

OBJECTIVES: To evaluate pain and swelling during the first week after periapical surgery and its relation to patient age, gender, oral hygiene, and smoking. STUDY DESIGN: One hundred two patients (31 men and 71 women) with a mean age of 40.2 years underwent periapical surgery. Age, gender, and oral hygiene and cigarette smoking before and during the postoperative course were noted. Pain and swelling scores were recorded on a descriptive 4-point scale at 2, 6, and 12 hours after surgery, and each day thereafter for 1 week. The data were statistically evaluated for significant differences. RESULTS: The highest intensity of pain occurred during the first 48 hours, and swelling peaked on the second postoperative day. Patient age and gender had no significant effect on postoperative symptoms (P > .05). Patients with poor oral hygiene before surgery presented greater pain and swelling during the first postsurgical hours, and smokers before surgery also suffered more pain. The number of cigarettes smoked in the postoperative period and oral hygiene after surgery had no effect on pain or inflammation (P > .05). CONCLUSIONS: Periapical surgery caused little pain and moderate swelling during the first 2 days after the intervention; these findings were more distinct in patients with poor oral hygiene before surgery and in smokers.

An EEG approach to the neurodevelopmental hypothesis of schizophrenia studying schizophrenics, normal controls and adolescents

Based on an integrative brain model which focuses on memory-driven and EEG state-dependent information processing for the organisation of behaviour, we used the developmental changes of the awake EEG to further investigate the hypothesis that neurodevelopmental abnormalities (deviations in organisation and reorganisation of cortico-cortical connectivity during development) are involved in the pathogenesis of schizophrenia. First-episode, neuroleptic-naive schizophrenics and their matched controls and three age groups of normal adolescents were studied (total: 70 subjects). 19-channel EEG delta-theta, alpha and beta spectral band centroid frequencies during resting (baseline) and after verbal stimuli were used as measure of the level of attained complexity and momentary excitability of the neuronal network (working memory). Schizophrenics compared with all control groups showed lower delta-theta activity centroids and higher alpha and beta activity centroids. Reactivity centroids (centroid after stimulus minus centroid during resting) were used as measure of update of working memory. Schizophrenics showed partial similarities in delta-theta and beta reactivity centroids with the 11-year olds and in alpha reactivity centroids with the 13-year olds. Within the framework of our model, the results suggest multifactorially elicited imbalances in the level of excitability of neuronal networks in schizophrenia, resulting in network activation at dissociated complexity levels, partially regressed and partially prematurely developed. It is hypothesised that activation of age- and/or state-inadequate representations for coping with realities becomes manifest as productive schizophrenic symptoms. Thus, the results support some aspects of the neurodevelopmental hypothesis.

Effects of Standard Labor-Wear on Swimming and Treading Water

We tested the hypothesis that occupational clothing would impair performance during swimming. The sub questions included: (1) Will the standard work wear of a railway worker or laborer impede swimming ability? (2) Will this clothing impact the individual’s ability to tread water? We addressed the research questions with three hypotheses. Analysis showed statistically significant p-values and all three null hypotheses were rejected in favor of the three research hypotheses, showing strong evidence that standard labor wear had adverse effects on 11.43 meter/12.5 yard swim time, water treading time and rate of perceived exertion (RPE) during water treading. The mean swim time more than doubled when the subjects wore standard labor-wear and their average rate of perceived exertion increased from 11.6 in standard swim wear to 17.1 in standard laborwear. It may be beneficial for those workers who work near water to be exposed to educational programs that allow in-water experiences so they develop an understanding of their abilities in, and respect for, the water.

Support for the predictions of the pollinator-mediated stabilizing selection hypothesis

Aims Floral traits are frequency used in traditional plant systematics because Of their assumed constancy. One potential reason for the apparent constancy of flower size is that effective pollen transfer between flowers depends oil the accuracy of the physical fit between the flower and pollinator. Therefore, dowels are likely to he under stronger stabilizing selection for uniform size than vegetative plant parts. Moreover, as predicted by the pollinator-mediated stabilizing selection (PMSS) hypothesis, all accurate fit between flowers and their pollinators is likely to he more important for specialized pollination systems as found in many species with bilaterally symmetric (zygomorphic) flowers than for species, with radially symmetric (actinomorphic) flowers. Methods In a comparative study of 15 zygomorphic and 13 actinomorphic species ill Switzerland, we tested whether variation in flower size, among and within individuals, is smaller than variation ill leaf size and whether variation in flower size is smaller ill zygomorphic compared to actinomorphic species. Important findings Indeed, variation ill leaf length was significantly larger than variation in flower length and width. Within-individual variation ill flower and leaf sizes did not differ significantly between zygomorphic and actinomorphic species. In line with the predictions of the PMSS, among-individual variation ill flower length and flower width was significantly smaller for zygomorphic species than for actinomorphic species, while the two groups did not differ in leaf length variation. This suggests that plants with zygomorphic flowers have undergone stronger selection for uniform flowers than plants with actinomorphic flowers. This supports that the uniformity of flowers compared to vegetative structures within species, as already observed in traditional plant systematics, is, at least in part, a consequence of the requirement for effective pollination.