Untersuchungen zur Funktion des O-Layers und potentieller divalenter Bindungsstellen des neuronalen SNARE-Komplexes

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EVALUATION OF A RUNNER’S PHYSIOLOGICAL PARAMETERS USING DIFFERENT SPRINT MODELS

INTRODUCTION: Hill’s model of sprinting, based on Newton’s second law of motion, uses two physiological parameters to characterize the sprinter, the maximum propulsive force per unit mass and the resistance-to-motion parameter related to the runner’s internal energy losses. Furusawa et al. (1927) suggested a resistive force law linear in the running speed. Later Keller (1973) and many others based their studies on Hill’s model. Senator (1982) added the effects of air resistance by a term quadratic in speed. Vaughan (1983) used a modification of these approaches by introducing a 0.7-power law. Recently, utilizing the rotational equation of motion for the leg and experimental data for stride frequency, we have shown that the internal and external resistive forces may well be approximated by a combination of linear and quadratic terms in running speed. We have also derived an expression for the internal resistive force in terms of physiological quantities. METHODS: The different models may be classified according to the resistive force law as linear (L), Vaughan (Va), quadratic (Q) and linearquadratic (LQ) models. We give analytical solutions for the distance-time relationships, except for the Va-model. We have used a numerical gradient method to fit the models with measured 100m data at ten equally spaced time stations of the 1988 Olympic Games in Seoul. Wind velocity and reaction times are also taken into account. RESULTS: By considering the residual errors we found that the best fit was given by the Va-model, followed by the LQ-, L-, and Q-models. The average residual error per time station for the Va- and LQ-models was about 0.01 s, which means a good fit throughout the run. We compared the values of the calculated physiological parameters with those in the existing literature. For the L-model the propulsive and resistive forces found by Vaughan and Matravers (1977) are in close agreement with ours, whereas those found by Woodside (1991) and Keller (1973) are too high, as can also be inferred from recent starting block data. For the parameters of the Va-model Vaughan (1983) obtained values somewhat lower than ours, using Ben Johnson, Carl Lewis and Linford Christie. This is to be expected, however, since Vaughan obtained his data for national university sprinters. As far as we know, the LQ-model has not been previously used. CONCLUSIONS: Our results show that the Va- and LQ-models best fit the Olympic 100 m data. There is a noteworthy difference between the interpretation of the linear resistive term in Hill’s theory and in the LQmodel presented in this paper: Hill and his colleagues invoked the concept of the viscosity of the muscles, while we arrived at the linear term by writing the rotational equation of the leg. It must be noted that already Fenn (1930) criticized the viscosity concept and attributed the resistive force to antagonistic muscles and other kinesiological factors. In view of our derivation of the LQ-model, the resistive force stems mainly from the rotational inertia of the leg, whereas the energy losses occur in the antagonistic muscles during the decelerating phases of the back and forth motion of the legs

Identification of the LH surge by measuring intact and total immunoreactivity in urine for prediction of ovulation time

Objectives In our earlier study, we separated three different molecular forms of urinary LH-ir (U-LH-ir) by gel filtration and identified them by immunoassay in urine from regularly menstruating women on periovulatory days. U-LH-ir is composed of intact luteinizing hormone (LH), its free beta-subunit (LH beta), and the core fragment of LH beta (LH beta cf), the latter two establishing the non-intact portion of LH-ir. The aim was to determine whether timing of ovulation can be improved by detecting different molecular forms of U-LH-ir in women of reproductive age. Methods We determined intact and total U-LH-ir in 14 regularly menstruating women on consecutive periovulatory days during the menstrual cycle. Non-intact LH-ir was calculated as the arithmetic difference between total and intact LH-ir. In addition, LH-ir was determined in both serum and urine from four of the women throughout the menstrual cycle. Results During the LH surge, U-LH-ir consisted mainly of intact LH and presented with an abrupt increase. Intact U-LH-ir dropped rapidly within 1 day after the surge, reaching baseline levels at the end of the luteal phase. In contrast, LH beta cf in urine increased further 1 day after the surge. After this, most of the U-LH-ir consisted of LH beta cf and it remained strongly elevated (over fivefold compared to intact LH) for the first 3 days after the LH surge, moderately elevated (over threefold) thereafter until day + 5, and mildly elevated until day + 7. Conclusions Total and non-intact LH-ir are potential add-on characteristics which can be utilized in ovulation predictor kits to measure LH-ir in urine beyond the LH surge during a broader time frame, thereby paving the way for more precise prediction of the timing of ovulation than that obtained with currently available products.Peer reviewe

Study protocol: a multi-professional team intervention of physical activity referrals in primary care patients with cardiovascular risk factors-the Dalby lifestyle intervention cohort (DALICO) study

Background: The present study protocol describes the trial design of a primary care intervention cohort study, which examines whether an extended, multi-professional physical activity referral (PAR) intervention is more effective in enhancing and maintaining self-reported physical activity than physical activity prescription in usual care. The study targets patients with newly diagnosed hypertension and/or type 2 diabetes. Secondary outcomes include: need of pharmacological therapy; blood pressure/plasma glucose; physical fitness and anthropometric variables; mental health; health related quality of life; and cost-effectiveness. Methods/Design: The study is designed as a long term intervention. Three primary care centres are involved in the study, each constituting one of three treatment groups: 1) Intervention group (IG): multi-professional team intervention with PAR, 2) Control group A (CA): physical activity prescription in usual care and 3) Control group B: treatment as usual (retrospective data collection). The intervention is based on self-determination theory and follows the principles of motivational interviewing. The primary outcome, physical activity, is measured with the International Physical Activity Questionnaire (IPAQ) and expressed as metabolic equivalent of task (MET)-minutes per week. Physical fitness is estimated with the 6-minute walk test in IG only. Variables such as health behaviours; health-related quality of life; motivation to change; mental health; demographics and socioeconomic characteristics are assessed with an electronic study questionnaire that submits all data to a patient database, which automatically provides feed-back to the health-care providers on the patients' health status. Cost-effectiveness of the intervention is evaluated continuously and the intermediate outcomes of the intervention are extrapolated by economic modelling. Discussions: By helping patients to overcome practical, social and cultural obstacles and increase their internal motivation for physical activity we aim to improve their physical health in a long- term perspective. The targeted patients belong to a patient category that is supposed to benefit from increased physical activity in terms of improved physiological values, mental status and quality of life, decreased risk of complications and maybe a decreased need of medication

Gender has to be taken into account in diagnosing adult growth hormone deficiency by the GHRH plus arginine test

Objective: Data on the effect of gender on the interpretation of the GHRH plus arginine stimulation test (GHRH + ARG test) is controversial. We validated the GHRH + ARG stimulation test in control subjects and patients with organic or idiopathic pituitary disease and a suspicion of adult growth hormone deficiency (AGHD) using the Immulite 2000 XPi GH assay. Design: We studied 126 apparently healthy adults (median age 38.8 years) and 34 patients with a suspicion of AGHD (median age 42.2 years). Identification of AGHD with the GHRH + ARG test was investigated with commonly accepted BMI-related consensus cut-off limits for peak GH concentrations. Serum samples collected during the GHRH + ARG test were analysed for GH in 2014-2015. Serum IGF-1 concentrations were studied as a reference. Results: In 14 of 65 (22%) control males the GH peak value was below the BMI-related cut-off limits for GH sufficiency indicating a false diagnosis of AGHD. All control females had a normal GHRH + ARG response. Median peak GH response was significantly (p <0.001) higher in female (39.3 mu g/L) than in male controls (21 mu g/L). According to consensus cut-offs all but one young female patient had a deficient response compatible with a diagnosis of AGHD. Conclusions: The GH response to stimulation by GHRH + ARG is gender-dependent, being lower in healthy males than in females. Gender should be considered when defining cut-off limits for peak GH concentrations in the GHRH + ARG test. The presently used BMI-related cut-off levels will lead to a significant misclassification of males as GH deficient.Peer reviewe

CAPS facilitates filling of the rapidly releasable pool of large dense-core vesicles

Calcium-activator protein for secretion (CAPS) is a cytosolic protein that associates with large dense-core vesicles and is involved in their secretion. Mammals express two CAPS isoforms, which share a similar domain structure including a Munc13 homology domain that is believed to be involved in the priming of secretory vesicles. A variety of studies designed to perturb CAPS function indicate that CAPS is involved in the secretion of large dense-core vesicles, but where in the secretory pathway CAPS acts is still under debate. Mice in which one allele of the CAPS-1 gene is deleted exhibit a deficit in catecholamine secretion from chromaffin cells. We have examined catecholamine secretion from chromaffin cells in which both CAPS genes were deleted and show that the deletion of both CAPS isoforms causes a strong reduction in the pool of rapidly releasable chromaffin granules and of sustained release during ongoing stimulation. We conclude that CAPS is required for the adequate refilling and/or maintenance of a rapidly releasable granule pool

Tomosyn Expression Pattern in the Mouse Hippocampus Suggests Both Presynaptic and Postsynaptic Functions

The protein tomosyn decreases synaptic transmission and release probability of vesicles, and is essential for modulating synaptic transmission in neurons. In this study, we provide a detailed description of the expression and localization patterns of tomosyn1 and tomosyn2 in the subareas of the mouse hippocampus. Using confocal and two-photon high-resolution microscopy we demonstrate that tomosyn colocalizes with several pre- and postsynaptic markers and is found mainly in glutamatergic synapses. Specifically, we show that tomosyn1 is differentially distributed in the mouse hippocampus and concentrated mainly in the hilus and mossy fibers. Surprisingly, we found that tomosyn2 is expressed in the subiculum, CA1 and CA2 pyramidal cell bodies, dendrites and spines, and colocalizes with PSD95, suggesting a postsynaptic role. These results suggest that in addition to the well-characterized presynaptic function of tomosyn in neurotransmitter release, tomosyn2 might have a postsynaptic function, and place tomosyn as a more general regulator of synaptic transmission and plasticity

Transcatheter placement of a low-profile biodegradable pulmonary valve made of small intestinal submucosa: A long-term study in a swine model

ObjectiveWe sought to investigate a placement of a percutaneous low-profile prosthetic valve constructed of small intestinal submucosa in the pulmonary position in a swine model.MethodsTwelve female farm pigs were stented at the native pulmonary valve to induce pulmonary insufficiency. Once right ventricular dilation occurred, the small intestinal submucosa valve was implanted. The pigs were followed up with transthoracic echocardiographic Doppler scanning. One animal died of heart failure before valve replacement. Animals were euthanized at 1 day, 1 month, 3 months, 6 months, and 12 months after valve implantation.ResultsThe small intestinal submucosa pulmonary valve showed effective reversal of pulmonary regurgitation. There were no misplacements during deployment. There were no embolizations. One-year echocardiographic follow-up showed minimal regurgitation and no stenosis for a valve/vessel ratio of 0.78 or greater. Histologic examination demonstrated intensive remodeling of the small intestinal submucosal valve. Within 1 month, the surface was covered by endothelium, and fibroblasts invaded the interior. Over the following months, the small intestinal submucosal valve remodeled without apparent graft rejection.ConclusionThe small intestinal submucosa valve has the potential for graft longevity without the need for anticoagulation or immunosuppression. Histologic remodeling of the valve tissue provides a replacement capable of resembling a native valve that can be placed percutaneously with low-profile delivery systems