Testis size, sperm characteristics and testosterone concentrations in four species of shrews (Mammalia, Soricidae).

The aim of this study was to establish and compare the sperm characteristics in four shrew species in the context of the sperm competition hypothesis. As expected, the large relative testis size in promiscuous species was associated with a high number of cauda epididymal spermatozoa and a high concentration of circulating testosterone. In addition, in Sorex and Neomys, species with high intensity of sperm competition, the spermatozoa stored in cauda epididymis were characterized by high percentage of progressive motility whereas in Crocidura and Suncus, the cauda epididymal spermatozoa were motile but with very low percentage of progressive motility. This capability is achieved only following the passage through the vas gland, a specialized region for sperm storage located along the vas deferens in these shrew species. The hypothesis that sperm competition is positively correlated with spermatozoa length could not be confirmed. In Crocidura and Suncus, the total sperm length is increased by the large sperm head due to a big acrosome. This trait, specific to the subfamily Crocidurinae, may results from a selective pressure independent of the context of sperm competition, related to a specific, but as yet unclear role, for the acrosome during the fertilization.

Size and fat content of gynes in relation to the mode of colony founding in ants (Hymenoptera; Formicidae)

In ants, there are two main processes of colony founding, the independent and the dependent modes. In the first case young queens start colony founding without the help of workers, whereas in the second case they are accompanied by workers. To determine the relation between the mode of colony founding and the physiology of queens, we collected mature gynes of 24 ant species. Mature gynes of species utilizing independent colony founding had a far higher relative fat content than gynes of species employing dependent colony founding. These fat reserves are stored during the period of maturation, i.e. between the time of emergence and mating, and serve as fuel during the time of colony founding to nurture the queen and the brood. Gynes of species founding independently but non claustrally were found to have a relative fat content intermediate between the values found for gynes founding independently and those founding dependently. This suggests that such gynes rely partially on their fat reserves and partially on the energy provided by prey they collect to nurture themselves and the first brood during the time of colony founding. Study of the fat content of mature gynes of all species has shown that it gives a good indication of the mode of colony founding.

Experimental and clinical radiofrequency ablation: proposal for standardized description of coagulation size and geometry.

BACKGROUND: Radiofrequency (RF) ablation is used to obtain local control of unresectable tumors in liver, kidney, prostate, and other organs. Accurate data on expected size and geometry of coagulation zones are essential for physicians to prevent collateral damage and local tumor recurrence. The aim of this study was to develop a standardized terminology to describe the size and geometry of these zones for experimental and clinical RF. METHODS: In a first step, the essential geometric parameters to accurately describe the coagulation zones and the spatial relationship between the coagulation zones and the electrodes were defined. In a second step, standard terms were assigned to each parameter. RESULTS: The proposed terms for single-electrode RF ablation include axial diameter, front margin, coagulation center, maximal and minimal radius, maximal and minimal transverse diameter, ellipticity index, and regularity index. In addition a subjective description of the general shape and regularity is recommended. CONCLUSIONS: Adoption of the proposed standardized description method may help to fill in the many gaps in our current knowledge of the size and geometry of RF coagulation zones.

Relationships of basal metabolic rate, relative testis size and cycle length of spermatogenesis in shrews (Mammalia, Soricidae).

The aim of the present study was to determinate the cycle length of spermatogenesis in three species of shrew, Suncus murinus, Sorex coronatus and Sorex minutus, and to assess the relative influence of variation in basal metabolic rate (BMR) and mating system (level of sperm competition) on the observed rate of spermatogenesis, including data of shrew species studied before (Sorex araneus, Crocidura russula and Neomys fodiens). The dynamics of sperm production were determined by tracing 5-bromodeoxyuridine in the DNA of germ cells. As a continuous scaling of mating systems is not evident, the level of sperm competition was evaluated by the significantly correlated relative testis size (RTS). The cycle durations estimated by linear regression were 14.3 days (RTS 0.3%) in Suncus murinus, 9.0 days (RTS 0.5%) in Sorex coronatus and 8.5 days (RTS 2.8%) in Sorex minutus. In regression and multiple regression analyses including all six studied species of shrew, cycle length was significantly correlated with BMR (r2=0.73) and RTS (r2=0.77). Sperm competition as an ultimate factor obviously leads to a reduction in the time of spermatogenesis in order to increase sperm production. BMR may act in the same way, independently or as a proximate factor, revealed by the covariation, but other factors (related to testes size and thus to mating system) may also be involved.

Body size and early growth in appropriate- and large-for-gestational-age infants.

AIMS: To study weight, length, body composition, sleeping energy expenditure (SEE), and respiratory quotient (RQ) at birth and at 5 mo of age in both adequate-for-gestational-age (AGA) and large-for-gestational-age (LGA) subjects; to compare the changes in body weight and body composition adjusting for gender, age, SEE, RQ and several maternal factors; to investigate the contribution of initial SEE and RQ to changes in body weight and body composition. METHODS: Sixty-nine neonates were recruited among term infants in the University Hospital of Verona, Italy. Forty-nine subjects participated until follow-up. At birth and follow-up, weight and length were measured and arm-fat area and arm-muscle area were calculated from triceps and subscapular skinfolds. SEE and RQ were measured by indirect calorimetry. RESULTS: At birth, weight, length, arm-muscle and arm-fat areas were significantly higher in LGA subjects than in AGA subjects. Weight status, SEE and RQ at birth did not explain the relative weight change after adjusting for gestational weight, placental weight, age at follow-up and gender. Arm-fat area and weight/length ratio at birth were negatively associated with relative changes in body weight after adjusting for the above variables (p < 0.05). CONCLUSION: Early growth from birth to 5 mo of life is significantly affected by body size and adiposity at birth. Fatter newborns had a slower growth rate than thinner newborns.

Determination of the size of quantum dots by fluorescence spectroscopy.

There has been a lack of quick, simple and reliable methods for determination of nanoparticle size. An investigation of the size of hydrophobic (CdSe) and hydrophilic (CdSe/ZnS) quantum dots was performed by using the maximum position of the corresponding fluorescence spectrum. It has been found that fluorescence spectroscopy is a simple and reliable methodology to estimate the size of both quantum dot types. For a given solution, the homogeneity of the size of quantum dots is correlated to the relationship between the fluorescence maximum position (FMP) and the quantum dot size. This methodology can be extended to the other fluorescent nanoparticles. The employment of evolving factor analysis and multivariate curve resolution-alternating least squares for decomposition of the series of quantum dots fluorescence spectra recorded by a specific measuring procedure reveals the number of quantum dot fractions having different diameters. The size of the quantum dots in a particular group is defined by the FMP of the corresponding component in the decomposed spectrum. These results show that a combination of the fluorescence and appropriate statistical method for decomposition of the emission spectra of nanoparticles may be a quick and trusted method for the screening of the inhomogeneity of their solution.

Dispatch centres: what is the right population catchment size?

Literature on medical dispatch is growing, focusing mainly on efficiency (under and overtriage) and dispatch-assisted CPR. But the issue of population catchment size, functional costs and rationalization is rarely addressed. If we can observe a trend toward a decreasing number of dispatch centres in many European countries, there is today no evidence on what is the right catchment size to reach the best balance between quality of services and costs.

Brain dynamics of meal size selection in humans.

Although neuroimaging research has evidenced specific responses to visual food stimuli based on their nutritional quality (e.g., energy density, fat content), brain processes underlying portion size selection remain largely unexplored. We identified spatio-temporal brain dynamics in response to meal images varying in portion size during a task of ideal portion selection for prospective lunch intake and expected satiety. Brain responses to meal portions judged by the participants as 'too small', 'ideal' and 'too big' were measured by means of electro-encephalographic (EEG) recordings in 21 normal-weight women. During an early stage of meal viewing (105-145ms), data showed an incremental increase of the head-surface global electric field strength (quantified via global field power; GFP) as portion judgments ranged from 'too small' to 'too big'. Estimations of neural source activity revealed that brain regions underlying this effect were located in the insula, middle frontal gyrus and middle temporal gyrus, and are similar to those reported in previous studies investigating responses to changes in food nutritional content. In contrast, during a later stage (230-270ms), GFP was maximal for the 'ideal' relative to the 'non-ideal' portion sizes. Greater neural source activity to 'ideal' vs. 'non-ideal' portion sizes was observed in the inferior parietal lobule, superior temporal gyrus and mid-posterior cingulate gyrus. Collectively, our results provide evidence that several brain regions involved in attention and adaptive behavior track 'ideal' meal portion sizes as early as 230ms during visual encounter. That is, responses do not show an increase paralleling the amount of food viewed (and, in extension, the amount of reward), but are shaped by regulatory mechanisms.

Physician behavioral adaptability: A model to outstrip a "one size fits all" approach

Objective: Based on a literature review, we propose a model of physician behavioral adaptability (PBA) with the goal of inspiring new research. PBA means that the physician adapts his or her behavior according to patients' different preferences. The PBA model shows how physicians infer patients' preferences and adapt their interaction behavior from one patient to the other. We claim that patients will benefit from better outcomes if their physicians show behavioral adaptability rather than a "one size fits all" approach. Method: This literature review is based on a literature search of the PsycINFO1 and MEDLINE1 databases. Results: The literature review and first results stemming from the authors' research support the validity and viability of parts of the PBA model. There is evidence suggesting that physicians are able to show behavioral flexibility when interacting with their different patients, that a match between patients' preferences and physician behavior is related to better consultation outcomes, and that physician behavioral adaptability is related to better consultation outcomes. Practice implications: Training of physicians' behavioral flexibility and their ability to infer patients' preferences can facilitate physician behavioral adaptability and positive patient outcomes.

PKA antagonizes CLASP-dependent microtubule stabilization to re-localize Pom1 and buffer cell size upon glucose limitation.

Cells couple growth with division and regulate size in response to nutrient availability. In rod-shaped fission yeast, cell-size control occurs at mitotic commitment. An important regulator is the DYRK-family kinase Pom1, which forms gradients from cell poles and inhibits the mitotic activator Cdr2, itself localized at the medial cortex. Where and when Pom1 modulates Cdr2 activity is unclear as Pom1 medial cortical levels remain constant during cell elongation. Here we show that Pom1 re-localizes to cell sides upon environmental glucose limitation, where it strongly delays mitosis. This re-localization is caused by severe microtubule destabilization upon glucose starvation, with microtubules undergoing catastrophe and depositing the Pom1 gradient nucleator Tea4 at cell sides. Microtubule destabilization requires PKA/Pka1 activity, which negatively regulates the microtubule rescue factor CLASP/Cls1/Peg1, reducing CLASP's ability to stabilize microtubules. Thus, PKA signalling tunes CLASP's activity to promote Pom1 cell side localization and buffer cell size upon glucose starvation.

Environmental control of the Pom1-dependent cell-size regulation pathway in fission yeast

Cells couple their growth and division rate in response to nutrient availability to maintain a constant size. This co-ordination happens either at the G1-S or the G2-M transition of the cell cycle. In the rod-shaped fission yeast, size regulation happens at the G2-M transition prior to mitotic commitment. Recent studies have focused on the role of the DYRK-family protein kinase Pom1, which forms gradients emanating from cell poles and inhibits the mitotic activator kinase Cdr2, present at the cell middle. Pom1 was proposed to inhibit Cdr2 until cells reached a critical size before division. However when and where Pom1 inhibits Cdr2 is not clear as medial Pom1 levels do not change during cell elongation. Here I show that Pom1 gradients are susceptible to environmental changes in glucose. Specifically, upon glucose limitation, Pom1 re-localizes from the poles to the cell sides where it delays mitosis through regulating Cdr2. This re-localization occurs due to microtubule de- stabilization and lateral catastrophes leading to transient deposition of the Pom1 gradient nucleator Tea4 along the cell cortex. As Tea4 localization to cell sides is sufficient to recruit Pom1, this explains the mechanism of Pom1 re-localization. Microtubule destabilization and consequently Tea4 and Pom1 spread depends on the activity of the cAMP-dependent Protein Kinase A (PKA/Pka1), as pka1 mutant cells have stable microtubules and retain polar Tea4 and Pom1 under limited glucose. PKA signaling negatively regulates the microtubule rescue factor CLASP/Cls1, thus reducing its ability to stabilize microtubules. Thus PKA signaling tunes CLASP activity to promote microtubule de-stabilization and Pom1 re-localization upon glucose limitation. I show that the side-localized Pom1 delays mitosis and balances the role of the mitosis promoting, mitogen-associated protein kinase (MAPK) protein Sty1. Thus Pom1 re-localization may serve to buffer cell size upon glucose limitation. -- Afin de maintenir une taille constante, les cellules régulent leur croissance ainsi que leur taux de division selon les nutriments disponibles dans le milieu. Dans la levure fissipare, cette régulation de la taille précède l'engagement mitotique et se fait à la transition entre les phases G2 à M du cycle cellulaire. Des études récentes se sont focalisées sur le rôle de la protéine Pom1, membre de la famille des DYRK kinase. Celle-ci forme un gradient provenant des pôles de la cellule et inhibe l'activateur mitotique Cdr2 présent au centre de la cellule. Le model propose que Pom1 inhibe Cdr2 jusqu'à atteindre une taille critique avant la division. Cependant quand et à quel endroit dans la cellulle Pom1 inhibe Cdr2 n'était pas clair car les niveaux médians de Pom1 ne changent pas au cours de la l'élongation des cellules. Dans cette étude, je montre que les gradients de Pom1 sont sensibles aux changements environnementaux du taux de glucose. Plus spécifiquement, en conditions limitantes de glucose, Pom1 se relocalise des pôles de la cellule pour se distribuer sur les côtés de celle-ci. Par conséquent, un délai d'entrée en mitose est observé dû à l'inhibition Cdr2 par Pom1. Cette délocalisation est due à la déstabilisation des microtubules qui va conduire à une déposition transitoire de Tea4, le nucléateur du gradient de Pom1, tout au long du cortex de la cellule. Comme la localisation de Tea4 sur les côtés de la cellule est suffisante pour recruter la protéine Pom1, ceci explique le mécanisme de relocalisation de celle-ci. La déstabilisation des microtubules et par conséquent la diffusion de Tea4 et Pom1 dépendent de l'activité de la protéine kinase A dépendante de l'AMP cyclique (PKA/Pka1). En absence de pka1, la stabilité des microtubules n'est pas affectée ce qui permet la rétention de Tea4 et Pom1 aux pôles de la cellule même en conditions limitantes de glucose. La signalisation via PKA régule négativement le facteur de sauvetage des microtubules CLASP/Cls1 et permet donc de réduire sa fonction de déstabilisation des microtubules. Ainsi la signalisation via PKA affine l'activité des CLASP pour promouvoir la déstabilisation des microtubules et la relocalisation de Pom1 en conditions limitantes de glucose. Je montre que la localisation sur les côtés retarde l'entrée en mitose et compense l'action de la protéine Sty1, connue pour être une MAPK qui induit l'entrée en mitose. Ainsi, la relocalisation de Pom1 pourrait servir à tamponner la taille de la cellule en condition limitantes de glucose. -- Various cell types in the environment such as bacterial, plant or animal cells have a distinct cellular size. Maintaining a constant cell size is important for fitness in unicellular organisms and for diverse functions in multicellular organisms. Cells regulate their size by coordinating their growth rate to their division rate. This coupling is important otherwise cells would get progressively smaller or larger after each successive cell cycle. In their natural environment cells may face fluctuations in the available nutrient supply. Thus cells have to coordinate their division rate to the variable growth rates shown under different nutrient conditions. During my PhD, I worked with a single-celled rod shaped yeast called the fission yeast. These cells are longer when the nutrient supply is abundant and shorter when the nutrient supply is scarce. A protein that senses changes in the external carbon source (glucose) is called Protein Kinase A (PKA). The rod shape of fission yeast cells is maintained thanks to a structural backbone called the cytoskeleton. One of the components of this backbone is called microtubules, which are small tube like structures spanning the length of the cell. They transport a protein called Tea4, which in turn is important for the proper localization of another protein Pom1 to the cell ends. Pom1 helps to maintain proper shape and size of these rod shaped yeast cells. My thesis work showed that upon reduction in the external nutrient (glucose) levels, microtubules become less stable and show an alteration in their organization. A significant percentage of the microtubules contact the side of the cell instead of touching only the cell tip. This leads to the spreading of the protein Pom1 away from the tips all around the cell periphery. This helps fission yeast cells to maintain the proper size required under these conditions of limited glucose supply. I further showed that the protein PKA regulates microtubule stability and organization and thus Pom1 spreading and maintenance of proper cell size. Thus my work led to the discovery of a novel pathway by which fission yeast cells maintain their size under limited supply of glucose. -- Divers types cellulaires dans l'environnement tels que les bactéries, les plantes ou les cellules animales ont une taille précise. Le maintien d'une taille cellulaire constante est importante pour le fitness des organismes unicellulaire ainsi que pour multiples fonctions dans les organismes multicellulaires. Les cellules régulent leur taille en coordonnant le taux de croissance avec le taux de division. Ce couplage est essentiel sinon les cellules deviendraient progressivement plus petites ou plus grandes après chaque cycle cellulaire. Dans leur habitat naturels les cellules peuvent faire face a des fluctuations dans le taux de nutriment disponible. Les cellules doivent donc coordonner leur taux de division aux taux variables de croissances perçus dans les différentes conditions nutritionnels. Pendant ma thèse, j'ai travaillée sur une levure unicellulaire, en forme de bâtonnet, nommé levure fissipare ou levure de fission. La taille de ces cellules est plus grande quand le taux de nutriments est grand et plus courte quand celui-ci est plus faible. Une protéine qui perçoit les changements dans le taux externe de la source de carbone (glucose) est nommée PKA pour protéine kinase A. La forme en bâtonnet de la cellule est due aux caractères structuraux du cytosquelette. Une composante importante de ce cytosquelette sont les microtubules, dont la structures ressemble à des petit tubes qui vont d'un bout à l'autre de la cellule. Ces microtubules transportent une protéine importante nommée Tea4 qui à leur tour importante pour la bonne localisation d'une autre protéine Pom1 aux extrémités de la cellule. La protéine Pom1 aide à maintenir la taille appropriée des levures fissipares. Mon travail de thèse a montré qu'en présence de taux faible de nutriments (glucose) les microtubules deviennent de moins en moins stables et montrent une désorganisation globale. Un pourcentage significatif des microtubules touche les côtés de la cellule aux lieu d'atteindre uniquement les extrémités. Ceci a pour conséquence une diffusion de Pom1 tout au long du cortex de la cellule. Ceci aide les levures fissipares à maintenir la taille appropriée pendant ce stress nutritionnel. De plus, je montre que PKA régule la stabilité et l'organisation des microtubules et par conséquent la diffusion de Pom1 et le maintien d'une taille constante. En conclusion, mon travail a conduit à la découverte d'un nouveau mécanisme par lequel la levure fissipare maintient sa taille dans des conditions limitantes en glucose.

Validity of silhouette showcards as a measure of body size and obesity in a population in the African region : a practical research tool for general-purpose surveys.

BACKGROUND: The purpose of this study is to validate the Pulvers silhouette showcard as a measure of weight status in a population in the African region. This tool is particularly beneficial when scarce resources do not allow for direct anthropometric measurements due to limited survey time or lack of measurement technology in face-to-face general-purpose surveys or in mailed, online, or mobile device-based surveys. METHODS: A cross-sectional study was conducted in the Republic of Seychelles with a sample of 1240 adults. We compared self-reported body sizes measured by Pulvers' silhouette showcards to four measurements of body size and adiposity: body mass index (BMI), body fat percent measured, waist circumference, and waist to height ratio. The accuracy of silhouettes as an obesity indicator was examined using sex-specific receiver operator curve (ROC) analysis and the reliability of this tool to detect socioeconomic gradients in obesity was compared to BMI-based measurements. RESULTS: Our study supports silhouette body size showcards as a valid and reliable survey tool to measure self-reported body size and adiposity in an African population. The mean correlation coefficients of self-reported silhouettes with measured BMI were 0.80 in men and 0.81 in women (P < 0.001). The silhouette showcards also showed high accuracy for detecting obesity as per a BMI ≥ 30 (Area under curve, AUC: 0.91/0.89, SE: 0.01), which was comparable to other measured adiposity indicators: fat percent (AUC: 0.94/0.94, SE: 0.01), waist circumference (AUC: 0.95/0.94, SE: 0.01), and waist to height ratio (AUC: 0.95/0.94, SE: 0.01) amongst men and women, respectively. The use of silhouettes in detecting obesity differences among different socioeconomic groups resulted in similar magnitude, direction, and significance of association between obesity and socioeconomic status as when using measured BMI. CONCLUSIONS: This study highlights the validity and reliability of silhouettes as a survey tool for measuring obesity in a population in the African region. The ease of use and cost-effectiveness of this tool makes it an attractive alternative to measured BMI in the design of non-face-to-face online- or mobile device-based surveys as well as in-person general-purpose surveys of obesity in social sciences, where limited resources do not allow for direct anthropometric measurements.