The application of principal component analysis to quantify technique in sports.

Analyzing an athlete's "technique," sport scientists often focus on preselected variables that quantify important aspects of movement. In contrast, coaches and practitioners typically describe movements in terms of basic postures and movement components using subjective and qualitative features. A challenge for sport scientists is finding an appropriate quantitative methodology that incorporates the holistic perspective of human observers. Using alpine ski racing as an example, this study explores principal component analysis (PCA) as a mathematical method to decompose a complex movement pattern into its main movement components. Ski racing movements were recorded by determining the three-dimensional coordinates of 26 points on each skier which were subsequently interpreted as a 78-dimensional posture vector at each time point. PCA was then used to determine the mean posture and principal movements (PMk ) carried out by the athletes. The first four PMk contained 95.5 ± 0.5% of the variance in the posture vectors which quantified changes in body inclination, vertical or fore-aft movement of the trunk, and distance between skis. In summary, calculating PMk offered a data-driven, quantitative, and objective method of analyzing human movement that is similar to how human observers such as coaches or ski instructors would describe the movement.

A systematic video analysis of 69 injury cases in World Cup alpine skiing.

We have limited insight into how injuries occur in professional ski racing. The aim of this study was to describe the injury situations in World Cup alpine skiing. Injuries reported through the International Ski Federation Injury Surveillance System for three consecutive World Cup seasons (2006-2009) were obtained on video. In total, 69 injuries and 124 runs of matched controls were analysed by five experts to evaluate the skiing situation, skier behavior, as well as piste-related factors. A chi-square test (95% CI, P ≤ 0.05) was used to examine whether there was a difference between course sections regarding where the injury situation occurred. The skier was most frequently turning (n = 55) or landing from a jump (n = 13) at the time of injury. Most of the injuries to the head and upper body (96%) resulted from crashes, while the majority of knee injuries (83%) occurred while the skier was still skiing. Gate contact contributed to 30% of the injuries, while 9% occurred at contact with safety nets/material. Almost half of the injuries (46%) occurred in the final fourth of the course. A particular concern was the high contribution of inappropriate gate contact and the high-energy impacts to the body when crashing.

Presence of acyl-homoserine lactones in 57 members of the Vibrionaceae family.

AIMS: The aim of this study was to use a sensitive method to screen and quantify 57 Vibrionaceae strains for the production of acyl-homoserine lactones (AHLs) and map the resulting AHL profiles onto a host phylogeny. METHODS AND RESULTS: We used a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) protocol to measure AHLs in spent media after bacterial growth. First, the presence/absence of AHLs (qualitative analysis) was measured to choose internal standard for subsequent quantitative AHL measurements. We screened 57 strains from three genera (Aliivibrio, Photobacterium and Vibrio) of the same family (i.e. Vibrionaceae). Our results show that about half of the isolates produced multiple AHLs, typically at 25-5000 nmol l(-1) . CONCLUSIONS: This work shows that production of AHL quorum sensing signals is found widespread among Vibrionaceae bacteria and that closely related strains typically produce similar AHL profiles. SIGNIFICANCE AND IMPACT OF THE STUDY: The AHL detection protocol presented in this study can be applied to a broad range of bacterial samples and may contribute to a wider mapping of AHL production in bacteria, for example, in clinically relevant strains.

[Six years of experiences from a department of geriatric psychiatry]. / Erfaringer fra en alderspsykiatrisk avdeling gjennom seks år.

After a project period from 1994 to 1997, all hospital-based psychogeriatric services in the Norwegian county of Telemark have been located to one department in the central hospital. The department has three differentiated bed units and one out-patient unit. This article describes the psychogeriatric department before and after the project, and includes an evaluation of the quality of service. The changes following the reorganization have been evaluated with an internal analysis, questionnaires to primary health care personnel and an examination of medical and psychiatric records. In 1995 and 1997, questionnaires were sent to general practitioners and district nurses in Telemark County. An independent consultant examined 40 medical and psychiatric records in 1995 and 1997, evaluating them according to selected quality standards. The response rates among doctors were 59% in 1995 and 48% in 1997. The responses show that primary health care doctors and nurses make use of the department's services and that they are increasingly satisfied with the quality of these services. The examination of medical and psychiatric records shows insufficient documentation of psychiatric symptoms and activities of daily life in 1995, but significant improvements by 1997. There are drawbacks to the evaluation method employed. However, we find it warranted to conclude that the reorganization has been functional and that the quality of services has improved.

I-NjaI, a nuclear intron-encoded homing endonuclease from Naegleria, generates a pentanucleotide 3' cleavage-overhang within a 19 base-pair partially symmetric DNA recognition site.

Different species of the amoebo-flagellate Naegleria harbor optional group I introns in the nuclear ribosomal DNA that contain open reading frames. Intron proteins from Naegleria jamiesoni, Naegleria andersoni, and Naegleria italica (named I-NjaI, I-NanI and I-NitI, respectively) were expressed in Escherichia coli and found to be isoschizomeric homing endonucleases that specifically recognize and cleave intron-lacking homologous alleles of ribosomal DNA. The I-NjaI endonuclease was affinity purified, characterized in more detail, and found to generate five-nucleotide 3' staggered ends at the intron insertion site which differs from the ends generated by all other known homing endonucleases. The recognition site was delimited and found to cover an approximately 19 base-pair partially symmetric sequence spanning both the cleavage site and the intron insertion site. The palindromic feature was supported by mutational analysis of the target DNA. All single-site substitutions within the recognition sequence were cleaved by the purified I-NjaI endonuclease, but at different efficiencies. The center of symmetry and cleavage was found to be completely degenerate in specificity, which resembles that of the subclass IIW bacterial restriction enzymes.

Complex group-I introns in nuclear SSU rDNA of red and green algae: evidence of homing-endonuclease pseudogenes in the Bangiophyceae.

The green alga Scenedesmus pupukensis and the red alga Porphyra spiralis contain large group-IC1 introns in their nuclear small subunit ribosomal RNA genes due to the presence of open reading frames at the 5' end of the introns. The putative 555 amino-acid Scenedesmus-encoded protein harbors a sequence motif resembling the bacterial S9 ribosomal proteins. The Porphyra intron self-splices in vitro, and generates both ligated exons and a full-length intron RNA circle. The Porphyra intron has an unusual structural organization by encoding a potential 149 amino-acid homing-endonuclease-like protein on the complementary strand. A comparison between related group-I introns in the Bangiophyceae revealed homing-endonuclease-like pseudogenes due to frame-shifts and deletions in Porphyra and Bangia. The Scenedesmus and Porphyra introns provide new insights into the evolution and possible novel functions of nuclear group-I intron proteins.

In vivo mobility of a group I twintron in nuclear ribosomal DNA of the myxomycete Didymium iridis.

DiSSU1 is an optional group I twintron present in the nuclear extrachromosomal ribosomal DNA of the myxomycete Didymium iridis. DiSSU1 appears to be complex both in structure and function. At the RNA level it has a twin-ribozyme organization composed of two group I ribozymes with different functions, separated by an open reading frame. Here, we show that DiSSU1 is mobile when haploid intron-containing and intron-less amoebae are mated. The mobility process is fast, being completed in 5-10 nuclear cycles after mating in the developing zygote and plasmodia. Analyses of progeny from genetic crosses confirm intron mobility. DiSSU1 is the first example of a mobile group I twintron. The intron-encoded protein was expressed in Escherichia coli and found to be an endonuclease, I-DirI, that cleaves an intron-less ribosomal DNA allele at the intron-insertion site, and is probably involved in intron homing. The endonuclease I-DirI seems to be a rare example of a protein that is expressed from a ribozyme-processed RNA polymerase I transcript in vivo.

A cell-surface heparan sulfate proteoglycan mediates neural cell adhesion and spreading on a defined sequence from the C-terminal cell and heparin binding domain of fibronectin, FN-C/H II.

FN-C/H II is a heparin binding synthetic peptide from the C-terminal cell and heparin binding domain of fibronectin (FN) that mediates neuronal cell adhesion, spreading, and neurite outgrowth. Cellular interactions with FN-C/H II are inhibited by soluble heparin, suggesting that a cell-surface proteoglycan may mediate interactions with FN-C/H II (Haugen et al., 1990). To test this hypothesis further, heparan sulfate (HS) or chondroitin sulfate (CS) was removed from the cell surface by enzyme treatment. Heparitinase but not chondroitinase treatment of cells inhibited rat B104 neuroblastoma cell adhesion and spreading on FN-C/H II. Additionally, heparitinase treatment decreased the spreading of cells on the 33/66 kDa fragments containing the C-terminal heparin binding domain of FN. Furthermore, antibodies generated against a mouse melanoma HS proteoglycan (HSPG) inhibited B104 cell adhesion to FN-C/H II and the 33/66 kDa FN fragments. 35S-HSPG isolated from B104 cells directly bound to FN-C/H II both in solid phase assays and by affinity chromatography, but failed to bind to a control peptide from this region, CS1. The binding of 35S-HSPG was predominantly mediated by the HS and not the core protein of the HSPG. SDS-PAGE of iodinated HSPG demonstrated a single 78 kDa core protein following heparitinase digestion, which migrated at 51 kDa under nonreducing conditions. Anti-HSPG antibodies recognized the 78 kDa core protein by immunoblotting, and stained the surface of rat B104 neuroblastoma cells and cells of the primary neonatal rat nervous system. These results identify a cell-surface HSPG that likely mediates neuronal cell binding interactions with FN-C/H II.

Central and peripheral neurite outgrowth differs in preference for heparin-binding versus integrin-binding sequences.

Neurons of the CNS and PNS differ in their response to fibronectin (FN) and proteolytic fragments of FN. The 33 kDa C-terminal cell and heparin-binding fragment of FN, in particular, is a strong promoter of CNS neurite outgrowth. To define further the neurite-promoting activity of the 33 kDa fragment, and to investigate further the differences between PNS and CNS responses to FN and the 33 kDa fragment, we contrasted neurite outgrowth by CNS and PNS neurons on three synthetic peptides representing sequences from this fragment of FN: two heparin-binding peptides, FN-C/H I and FN-C/H II (McCarthy et al., 1990), and an integrin-binding peptide, CS1 (Humphries et al., 1987). Spinal cord (SC) neurons, from the CNS, differed from dorsal root ganglion (DRG) neurons, from the PNS, with respect to substratum preference for heparin-binding versus integrin-binding peptides. SC neurite outgrowth was greatest on the heparin-binding peptide FN-C/H II, while DRG neurite outgrowth was greatest on the a4 beta 1 integrin-binding peptide CS1. To test whether the difference in substratum preference was due to differences in the molecular mechanism by which SC and DRG neurons interact with the 33 kDa fragment of FN, anti-beta 1 integrin antibodies and/or soluble heparin were added to the cultures as potential inhibitors of integrin-mediated or proteoglycan-mediated interactions with FN. SC neurite outgrowth was much more sensitive to the effect of heparin than anti-beta 1 integrin, indicating SC neurite outgrowth may involve predominantly a heparin-sensitive mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium transients in skeletal muscle fibres under isometric conditions and during and after a quick stretch.

The transient change in the sarcoplasmic concentration of Ca2+ was measured in intact fibres isolated from the anterior tibial muscle of the frog Litoria moorei. The fibres had been injected with the calcium-sensitive dye arsenazo III and the change of the calcium concentration was calculated from the changes in light absorbance at 570, 600 and 720 nm wavelengths. Absorbance and force were measured under three different conditions: (1) during a normal isometric twitch, (2) when a quick ramp-and-hold stretch had been applied to the fibre during onset of the contraction, and (3) when the fibre was allowed to contract isometrically at a length corresponding to the final length of the stretch. A method was devised to neutralize most of the movement artefacts encountered in such measurements. While the quick stretch caused substantial increase in the level and the duration of the contractile force such as originally described in whole muscle by A. V. Hill, the calcium transients appeared basically unaffected. It thus seems that the mechanism behind the phenomenon of the force enhancement lies at a step in the excitation-contraction coupling subsequent to the calcium release. From the present results, however, it is not clear whether the phenomenon is caused by an increase in the level of activation of the calcium-dependent regulatory system, or whether it is to be found in the acto-myosin interaction itself. The latter alternative would be consistent with the stiffness measurements published earlier.

Recognition of the A chain carboxy-terminal heparin binding region of fibronectin involves multiple sites: two contiguous sequences act independently to promote neural cell adhesion.

Cellular interactions with fibronectin-treated substrata have a complex molecular basis involving multiple domains. A carboxy-terminal cell and heparin binding region of fibronectin (FN) is particularly interesting because it is a strong promoter of neurite outgrowth (Rogers, S.L., J.B. McCarthy, S.L. Palm, L.T. Furcht, and P.C. Letourneau, 1985. J. Neurosci. 5:369-378) and cell attachment (McCarthy, J.B., S.T. Hagen, and L.T. Furcht. 1986. J. Cell Biol. 102:179-188). To further understand the molecular mechanisms of neuronal interactions with this region of FN, we screened two peptides from the 33-kD heparin binding fragment of the FN A chain, FN-C/H II (KNNQKSEPLIGRKKT) and CS1 (Humphries, M.J., A. Komoriya, S.K. Akiyama, K. Olden, and K.M. Yamada. 1987. J. Biol. Chem. 262:6886-6892), for their ability to promote B104 neuroblastoma cell-substratum adhesion and neurite outgrowth. Both FN-C/H II and CS1 promoted B104 cell attachment in a concentration-dependent and saturable manner, with attachment to FN-C/H II exceeding attachment to CS1. In solution, both exogenous FN-C/H II or CS1 partially inhibited cell adhesion to the 33-kD fragment. Similar results were obtained with anti-FN-C/H II antibodies. In contrast, soluble GRGDSP did not affect B104 cell adhesion to FN-C/H II. These results indicate that both FN-C/H II and CS1 represent distinct, RGD-independent, cell adhesion-promoting sites active within the 33-kD fragment, and further define FN-C/H II as a novel neural recognition sequence in FN. B104 adhesion to FN-C/H II and CS1 differs in sensitivity to heparin, yet each peptide inhibited adhesion to the other peptide, suggesting cell adhesion is somehow related at the cellular level. Within the A chain 33-kD fragment, FN-C/H II and CS1 are contiguous, and might represent components of a larger domain with greater neurite-promoting activity since only the 33-kD fragment, and neither individual peptide, was effective at promoting B104 neurite outgrowth. These data further support the hypothesis that cell responses to FN are mediated by multiple sites involving both heparin-sensitive and -insensitive mechanisms.

[Dementia in the elderly. A 3-year project]. / Demenstilstander hos eldre. Et treårig pilotprosjekt.

In order to meet the need of proper examination and treatment of memory problems in the elderly a specialized unit of psychogeriatrics has been established as a pilot project. In the period from September 1986 to April 1988, 146 persons were examined, 42% as outpatients and 58% as inpatients. The average age was 75.3 years. 54% had dementia senilis and 16% other sorts of dementia. 30% were not demented: 14% had a psychiatric illness, 8% organic damage or illness of the brain and 7% were confused. Overdose or wrong use of psychopharmacological drugs was a frequent problem, and cutting out the medication, regulating the dose, or changing to another medicine had surprising consequences. The further treatment was planned in cooperation with the patient's family and the community health service. A follow-up after nine months indicated that this was a positive procedure for the patients, and that the unit was a professional resource to the local health services in the whole district. The hospital has now been allocated funds from the Government to function as a competence centre for part of Eastern Norway.

Interleukin-2 enhances chick and rat sympathetic, but not sensory, neurite outgrowth.

Interactions between the immune and nervous systems could be important for normal development and function of both. To determine if a lymphokine, interleukin-2 (IL-2), represents a link between these two systems, sympathetic and sensory neurons from embryonic chick and neonatal rat were cultured in media containing human recombinant IL-2. In chick sympathetic chain and rat superior cervical ganglia cultures, IL-2 enhanced the number of neurons with neurites and the length of those neurites significantly over control cultures. Sensory neurons from chick and rat dorsal root ganglia were not affected by culture in IL-2. Sympathetic neuron response to IL-2 was concentration-dependent, with an optimum around 2-0.2 U/ml (100-10 pM). Immunofluorescence with an anti-IL-2 receptor antibody demonstrated specific staining of sympathetic neurons, but not sensory neurons, implying that sympathetic neurons may have a receptor for IL-2 on their surface.

Efficacy of short mental tests in the detection of mental impairment in old age.

The usefulness, inter-rater reliability, and validity of six mental tests, the MMS, the GMS, the MSQ, the VRT, the OLT, and the DCT were studied in 81 patients over the age of 75 years. The patients were classified as being mentally impaired or unimpaired by psychogeriatric assessment. All tests had high reliability. The MMS, GMS, MSQ, and OLT were the most feasible and useful. The tests were validated by logistic regression analysis and the most efficient were the MMS, GMS, and OLT. Improvement was achieved when two or all three tests were used simultaneously. The three tests seem to be suitable tools for the detection of mental failure in patients of old age.

The stiffness under isotonic releases during a twitch of a frog muscle fibre.

These investigations were undertaken to elucidate whether the difference between the time courses of the isometric tension and the velocity of shortening upon releases to a given isotonic load various times during a twitch is due to a change in the kinetics of the individual cross-bridges, i.e. in the rate constants governing the transitions between the various strongly bound cross-bridge states. Single skeletal muscle fibres from the frog (Rana temporaria, sarcomere length 2.3 microns, temperature 4-6 degrees C) were stimulated to produce isometric twitches and released after various delays to shorten isotonically against finite loads (P). Force, stiffness (K, measured by longitudinal oscillation 0.3-0.8 nm per half-sarcomere peak-to-peak, 2 kHz), and change in length were measured simultaneously. The velocity of shortening (V) was estimated as the quasi steady-state value, i.e. the value attained after the initial oscillatory transient response to the change in length preceding the isotonic shortening. A reduction in P led to a reduction in K, however, the relative reduction in K was not as great as the relative reduction in P. Thus, when extrapolated to P = O, K was about one third of its peak isometric value. Under the assumption that K is to the first order of approximation proportional to the number of strongly bound cross-bridges, P was divided by K to give an estimate of the average load per cross-bridge yo = P/K.V showed an almost linear dependence on yo (correlation coefficients 0.95-0.998). The slope and intercept of this relation (regression analysis) showed no dependence on the delay after stimulation of the release to the isotonic load. The results can be explained if the kinetic properties of the individual strongly bound cross-bridges are unaffected by the level of activation which changes during the course of the contraction.