KINETIC AND KINEMATIC ANALYSIS OF THE BACKSTROKE START

Race start technique in competitive swimming has developed considerably in recent years and is thought to be an important factor governing the outcome of a race. The purpose of this study was to measure the reliability of a new analysis system for swimming (PAS-S), as well as to analyse the backstroke start kinetics and kinematics and to compare the normal backstroke start with the backstroke start with a new start device. 16 high level competitive swimmers were examined in this study, which revealed that the measurements with the PAS-S are reliable. The analysis of the backstroke start showed the importance of a high preload force just before the start signal. Furthermore, if available, swimmers should use the new backstroke start device since the 15 m times were significantly faster even without considerable training with the new start device

KINETIC AND KINEMATIC ANALYSIS OF THE LEG POSITIONING IN THE FREESTYLE TRACK START IN SWIMMING

In swimming competitions, the track start is an important part of the race. The aim of this study was to assess and compare the relative positioning of the dominant leg in the preferential freestyle track start. The data was collected using the (Kistler) Performance Analysis System for Swimming (PAS-S) that includes a force measurement and motion analysis system. The results taken from 15 high level competitive swimmers showed that 67.7 % of the subjects naturally position their dominant leg in front. Starting with the dominant leg in front (6.67±0.24) was significantly (p < 0.001) faster than in the rear position (7.25±0.23). However swimmers had faster starts when using their preferential track start. Detailed analysis of the swimming start and the footedness allows coaches and athletes to train the fastest starting technique

3-(Phenyl-4-oxy)-5-phenyl-4,5-dihydro-(1H)-pyrazole: a fascinating molecular framework to study the enantioseparation ability of the amylose (3,5-dimethylphenylcarbamate) chiral stationary phase. Part I. Structure-enantioselectivity relationships

Chiral stationary phases (CSPs) based on amylose (3,5-dimethylphenylcarbamate) (ADMPC) exhibit awide-range of enantioselectivity in high-performance liquid chromatography (HPLC) and supercriticalfluid chromatography (SFC). Although this class of CSPs has been extensively used, chiral discriminationsat receptorial level, which are useful to develop predictive molecular models, have been rarely reportedin the literature.Herein, we describe the results obtained in the enantioselective HPLC of a set of six C5-chiral 4,5-dihydro-(1H)-pyrazole derivatives on the ADMPC-based Chiralpak AD-3 CSP (CSP) under normal-phaseand polar organic conditions. Using pure methanol as a mobile phase the exceptional enantioseparationfactor value of 50 at 25◦C was found for one of the investigated analytes. To the best of our knowledge, theenantiomeric bias represents the most outstanding enantioseparation ever recorded on ADMPC-basedCSPs.Systematic variations in chemical groups in specific positions of the 3-(phenyl-4-oxy)-5-phenyl-4,5-dihydro-(1H)-pyrazole molecular framework resulted in peculiar changes in retention andenantioselectivity. A careful analysis of the chromatographic data permitted to advance some hypothesesconcerning the role played by the individual chemical groups in determining the exceptional enantiosep-aration.In particular, under methanol-rich mode, the prenyl moiety of the second eluted enantiomer of thebetter resolved analyte was recognized as a critical structural element to establish direct and favorablesolvophobic interactions with apolar portions of selector

Key performance indicators and leg positioning for the kick-start in competitive swimmers

The aim of the study was to (1) assess the test-retest reliability of a novel performance analysis system for swimming (KiSwim) including an instrumented starting block and optical motion capture system, (2) identify key performance indicators (KPI) for the kick-start, (3) determine the most beneficial position of the strong leg and (4) investigate the effect of acute reversal of leg positioning. During three sessions, kick-starts of 15 competitive swimmers were investigated. Eighteen kinematic and kinetic parameters showed high reliability (ICC>0.75) from which principal component analysis identified seven KPI (i.e., time to 15 m, time on-block, depth at 7.5 m, horizontal take-off velocity, horizontal impulse back plate, horizontal peak force back plate and vertical peak force front plate). For the preferred start position, the back plate showed a higher horizontal peak force (0.71 vs. 0.96 x body mass; p < 0.001) and impulse (0.191 vs. 0.28Ns/BW; p < 0.001) compared to front plate. Acute reversal of the leg position reduced performance (i.e., increased time to 15 m and reduced horizontal take-off velocity). However, plate-specific kinetic analysis revealed a larger horizontal peak force (p < 0.001) and impulse (p < 0.001) for the back compared to the front plate in any start position investigated. Therefore, swimmers are encouraged to position the strong leg in the back

Emergency response for evaluating SARS-CoV-2 immune status, seroprevalence and convalescent plasma in Argentina

We report the emergency development and application of a robust serologic test to evaluate acute and convalescent antibody responses to SARS-CoV-2 in Argentina. The assays, COVIDAR IgG and IgM, which were produced and provided for free to health authorities, private and public health institutions and nursing homes, use a combination of a trimer stabilized spike protein and the receptor binding domain (RBD) in a single enzyme-linked immunosorbent assay (ELISA) plate. Over half million tests have already been distributed to detect and quantify antibodies for multiple purposes, including assessment of immune responses in hospitalized patients and large seroprevalence studies in neighborhoods, slums and health care workers, which resulted in a powerful tool for asymptomatic detection and policy making in the country. Analysis of antibody levels and longitudinal studies of symptomatic and asymptomatic SARS-CoV-2 infections in over one thousand patient samples provided insightful information about IgM and IgG seroconversion time and kinetics, and IgM waning profiles. At least 35% of patients showed seroconversion within 7 days, and 95% within 45 days of symptoms onset, with simultaneous or close sequential IgM and IgG detection. Longitudinal studies of asymptomatic cases showed a wide range of antibody responses with median levels below those observed in symptomatic patients. Regarding convalescent plasma applications, a protocol was standardized for the assessment of end point IgG antibody titers with COVIDAR with more than 500 plasma donors. The protocol showed a positive correlation with neutralizing antibody titers, and was used for clinical trials and therapies across the country. Using this protocol, about 80% of convalescent donor plasmas were potentially suitable for therapies. Here, we demonstrate the importance of providing a robust and specific serologic assay for generating new information about antibody kinetics in infected individuals and mitigation policies to cope with pandemic needs.Fil: Ojeda, Diego Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: González López Ledesma, María Mora. Fundación Instituto Leloir; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pallarés, Horacio Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Costa Navarro, Guadalupe Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación Instituto Leloir; ArgentinaFil: Sanchez, Lautaro Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Perazzi, Beatriz Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Villordo, Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Alvarez, Diego Ezequiel. Universidad Nacional de San Martín; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Echavarría, Marcela Silvia. Centro de Educación Médica e Investigaciones Clínicas "Norberto Quirno"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Oguntuyo, Kasopefoluwa Y.. Icahn School of Medicine at Mount Sinai; Estados UnidosFil: Stevens, Christian S.. Icahn School of Medicine at Mount Sinai; Estados UnidosFil: Lee, Benhur. Icahn School of Medicine at Mount Sinai; Estados UnidosFil: Carradori, Jorge. Laboratorio Lemos S.R.L; ArgentinaFil: Caramelo, Julio Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Yanovsky, Marcelo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Gamarnik, Andrea Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentin

Kinetische und kinematische Messungen des Trackstarts zur Leistungsanalyse im Schwimmen

Hintergrund: Der Start ist im Schwimmen für einen erfolgreichen Wettkampf entscheidend. Kistler Instrumente AG konstruierte zur Leistungsanalyse, basierend auf dem OSB11, ein neues Messsystem (PAS-S) mit mehreren Kraftmessplatten undvier Kamerasystemen. Die Ziele dieser Studie waren das Messsystem zu validieren und den Einfluss der Positionierung des dominanten Beins auf die Startperformance beim Trackstart zu untersuchen. Methode: 15 Elite Schwimmer wurden an drei Messtagen untersucht. Die Messapparatur wurde zu Testzwecken zwischen dem ersten und zweiten Messtag demontiert. Die Probanden absolvierten fünf Trackstarts mit dem bevorzugten Bein vorne und hinten. Das stärkere Bein wurde mit einem einbeinigen Sprungtest ermittelt. Kinetische und kinematische Daten der Trackstarts wurden parametrisiert und mittels SPSS statistisch ausgewertet. Ergebnisse: Die Parameter der 3 Messtage waren gleich, das System erwies sich als reliabel. 53.3% der Probanden erzielten mit dem selbsternannten Sprungbein eine geringere maximale Absprungkraft als mit dem anderen. Das hintere Bein erzeugte die grössere maximale Kraft und einen grösseren Impuls. 66.6% platzierten ihr dominantes Bein beim bevorzugten Trackstart vorne. Beim bevorzugten Trackstart war die Schwimmzeit bis 15 m kürzer. Diskussion: Das PAS-S ist ein reliables Instrument um die Startperformance zu untersuchen. Über die Wahl der Beinposition kann die Starperformance beeinflusst werden. Obwohl die grössere maximale Kraft beim hinteren Bein gemessen wurde, scheint es in Bezug auf die 15m Zeit von Vorteil zu sein, das dominante Bein vorne auf dem Block zu positionieren. Die wenigsten Athleten wissen, welches ihr dominantes Bein ist. Daher gibt es noch ein grosses Potential für Trainer und Athleten, die Startperformance beim Trackstart zu verbessern

3-(Phenyl-4-oxy)-5-phenyl-4,5-dihydro-(1H)-pyrazole: a fascinating molecular framework to study the enantioseparation ability of the amylose (3,5-dimethylphenylcarbamate) chiral stationary phase. Part II. Solvophobic effects in enantiorecognition process

The enantiomers of five chiral compounds incorporating the 3-(phenyl-4-oxy)-5-phenyl-4,5-dihydro-(1H)-pyrazole scaffold and differing only in the linear alkyl chain (varying in length from 1 to 5 carbon atoms) linked to the oxygen atom were directly separated on the amylose (3,5-dimethylphenylcarbamate) based Chiralpak AD-3 chiral stationary phase. The effects of the mobile phase composition, the structure of the analytes and temperature on the retention and enantioselectivity were investigated. It was found that the enantiomeric separations were in all cases enthalpy-driven and disfavored by entropic term. U-shape curves obtained by plotting the chromatographic data versus the alcoholic percentage in n-pentane-methanol and n-hexane-ethanol mobile phases highlighted that, at higher alcohol concentrations, solvophobic interactions were operative in the retention mechanism. The unusual trend of such curves was linked to the nature of alkyl chain of the pyrazolines and it was indicative of the solvophobic contribution to the achievement of a high degree of enantioseparation

The anancomeric character of the pharmacophore 1,3,4-thiadiazoline framework in chiral spiro-cyclohexyl derivatives: effects on stereochemistry and spiro-junction lability. Thermodynamic aspects

Three new and easily accessible chiral compounds, containing the pharmacophore 1,3,4-thiadiazoline nucleus joined by a spiro center to a monoalkyl (methyl or t-butyl) substituted cyclohexyl fragment, have been synthesized and fully characterized from the structural and stereochemical point of view. The formation of a spiro-cyclohexyl-thiadiazoline system (sCT) offered the rare opportunity to generate at room temperature both anancomeric structures, displaying alkyl groups bound to the cyclohexyl ring in equatorial position, and other quite stable stereoisomers in which the same alkyl moieties are, instead, inserted in axial position, even for the extreme case represented by the really bulky t-butyl group. DFT calculations led to a clear rationalization of such stereochemical behaviors, pointing out that in all cases they arise from the unexpected strong anancomeric character possessed by the sCT framework in its 4-acetyl substituted version. In consideration of the large number of substances in which the 1,3,4-thiadiazoline heterocycle has been found as the active pharmacophore, the results discussed in this work may provide solid bases to allow a rational design of new chiral bioactive spiro-thiadiazolines characterized by well-defined stereochemical structures and single anancomeric geometries

3-Methylcyclohexanone thiosemicarbazone: Determination of E/Z isomerization barrier by dynamic high-performance liquid chromatography, configuration assignment and theoretical study of the mechanisms involved by the spontaneous, acid and base catalyzed processes

Direct HPLC diastereo- and enantioseparation of 3-methylcyclohexanone thiosemicarbazone (3-MCET) on a polysaccharide-based chiral stationary phase under normal-phase conditions. The optimized chromatographic system was employed in dynamic HPLC experiments (DHPLC), as well as detection technique in a batch wise approach to determine the rate constants and the corresponding free energy activation barriers of the spontaneous, base- and acid-promoted E/Z diastereomerization of 3-MCET. The stereochemical characterization of four stereoisomers of 3-MCET was fully accomplished by integrating the results obtained by chemical correlation method with those derived by theoretical calculations and experimental investigations of circular dichroism (CD). As a final goal, a deepened analysis of the perturbing effect exercised by the stationary phase on rate constant values measured through DHPLC determinations as a function of the chromatographic separation factor α of the interconverting species was successfully accomplished. This revealed quite small deviations from the equivalent kinetic values obtained by off-column batch wise procedure, and suggested a possible effective correction of rate constants measured by DHPLC approac

Elucidation of the mechanisms governing the thermal diastereomerization of bioactive chiral 1,3,4-thiadiazoline spiro-cyclohexyl derivatives towards their anancomeric stereoisomers

The kinetic of the thermal isomerization of some diastereomers of three chiral 1,3,4 thiadiazoline derivatives, selected as case studies of structures resulting by mono-alkyl substitution of the anancomeric 4-acetyl-2-acetamido-1,3,4- thiadiazolinyl-spiro-cyclohexane (TsC) framework has been investigated in order to elucidate the possible mechanistic pathways and the structural factors responsible for the observed spiro-junction lability. The insertion of a methyl or a tbutyl group on the C2 or C3 position with respect to the spiro junction generate two stereogenic centres, so that two pairs of enantiomers exist. The first-order rate constants for the isomerization of the less stable enantiomers into the most stable ones have been measured in different solvents and at different temperatures through batch-wise kinetic determinations. The obtained data have been successfully rationalizedby DFT calculations and Linear Solvation Energy Relationships (LSER) analyses. The achieved elucidation should make possible to plan a more rational synthesis of this kind of pharmacologically active compounds, thus affording a practical tool useful to control the involved stereochemistry and spiro-junctio