Repeated change-of-direction test for collegiate male soccer players.

AIM: The aim of the study was to investigate the applicability of a repeated change-of-direction (RCoD) test for NCAA Division-I male soccer players. METHODS: The RCoD test consisted of 5 diagonal direction changes per repetition with a soccer ball to be struck at the end. Each player performed 15 repetitions with approximately 10 seconds to jog back between repetitions. Data were collected in two sessions. In the first session, 13 players were examined for heart rate responses and blood lactate concentrations. In the second session, 22 players were examined for the test's ability to discriminate the primary from secondary players (78.0±16.1 and 10.4±13.3 minutes per match, respectively). RESULTS: Heart rate data were available only from 9 players due to artifacts. The peak heart rate (200.2±6.6 beats∙min-1: 99.9±3.0% maximum) and blood lactate concentration (14.8±2.4 mmol∙L-1 immediately after) resulted in approximately 3.5 and 6.4-fold increases from the resting values, respectively. These values appear comparable to those during intense periods of soccer matches. In addition, the average repetition time of the test was found to discriminate the primary (4.85±0.23 s) from the secondary players (5.10±0.24 s) (P=0.02). CONCLUSION: The RCoD test appears to induce physiological responses similar to intense periods of soccer matches with respect to heart rate and blood lactate concentration. Players with better average repetition times tend to be those who play major minutes.

Were monocytes responsible for initiating the cytokine storm in the TGN1412 clinical trial tragedy?

The precise biological mechanisms that caused the TGN1412 clinical trial tragedy (also known as 'The Elephant Man Clinical Trial') in March 2006 remain a mystery to this day. It is assumed widely that the drug used in this trial (TGN1412) bound to CD28 on T lymphocytes and following activation of these cells, a massive 'cytokine storm' ensued, leading ultimately to multi-organ failure in all recipients. The rapidity of this in vivo response (within 2 h), however, does not fit well with a classical T lymphocyte response, suggesting that other 'faster-acting' cell types may have been involved. In this study we have activated purified human peripheral blood leucocyte populations using various clones of mouse monoclonal anti-CD28 presented to cells in the form of a multimeric array. Cytokines were measured in cell-free supernatants at 2 h, and specific mRNA for tumour necrosis factor (TNF)-α, thought to be the initiator of the cytokine storm, was also measured in cell lysates by reverse transcription-polymerase chain reaction (RT-PCR). Monocytes were the only cell type found to show significant (P < 0·05) up-regulation of TNF-α at 2 h. Eleven other monocyte cytokines were also up-regulated by anti-CD28 within this time-frame. It therefore seems likely that monocytes and not T cells, as widely believed, were probably responsible, at least in part, for initiating the cytokine storm. Furthermore, we propose that a multimeric antibody array may have formed in vivo on the vascular endothelium via an interaction between TGN1412 and CD64 (FcγRI), and we provide some evidence in support of this hypothesis.

Bone mineral density and content of collegiate throwers: influence of maximum strength.

AIM: Bone changes in size and density in response to different levels of stress. Alterations to bone mineral density (BMD) appear to occur in a site specific manner. Even though BMD has been examined in many populations there is a paucity of data looking at strength-power athletes, such as throwers. Therefore, the purpose of this study was to examine the BMD of a group of USA Division I collegiate throwers (e.g. shot put, discus, etc.). METHODS: Seven throwers (4 males; 3 females) who were 19.0 + or - 0.9 years had their BMD compared to an age matched control group (n = 14; 8 women and 6 men) and normative data. BMD was measured with dual X-ray absorptometry. Potential right/left side and sex difference in BMD were also examined. Maximal isometric strength was assessed using a mid-thigh pull while standing on a forceplate which generated force-time curves. Peak force (PF) and normalized peak force (PFa) were then correlated with BMDs. RESULTS: Generally, throwers had denser bones with male throwers tending to have a greater total BMD (P < or = 0.05). The dominant arm BMD was slightly greater when compared to non-dominant arm (P < or = 0.05). Furthermore, total body BMD was related to PF (r = 0.68, r(2) = 0.46) and PFa (r = 0.56, r(2) = 0.31). CONCLUSIONS: Throwers have greater BMDs than non-athletes and most other athletes. However, throwers only showed a small indication of sidedness. It is likely that the BMDs observed in this study stem from the training intervention (e.g. whole body heavy lifting) undertaken by this population.

Changes in the lateral diffusion of fluorescent lipid analogues in the surface membrane of adult male Schistosoma mansoni.

The effect of serotonin on the fluidity of the tegumental membranes of adult male Schistosoma mansoni was assessed by the fluorescence recovery after photobleaching technique. It was demonstrated that the translational diffusion of 5-N'-octadecanoyl aminofluorescein is reduced by a mechanism involving G-protein coupled activation of adenylate cyclase and lowering of intracellular calcium concentration. Furthermore, the lateral diffusion coefficient and the mobile fraction appear to be controlled by calcium and cAMP dependent pathways respectively. No change in the diffusion of the fluorescent phospholipid N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-phosphatidyl choline was observed, suggesting the two probes used here partition into two different domains that are under independent control. An increase in the amount of protein associating with a membrane cytoskeleton is also demonstrated.

Injury prevention in women's gymnastics.

The most serious problem faced by contemporary gymnasts is injury. Given that prevention is superior to treatment, can the gymnastics community and the scientific and medical community do a better job at injury prevention? Most research in gymnastics has been descriptive in nature. Injury prevention ultimately requires that one can predict the outcome of certain activities and their injurious nature. Making such predictions requires a knowledge of the scientific and medical aspects of injury, but more than that, one must have an intimate knowledge of the sport. Injury prevention efforts must be firmly grounded in science and medicine while making pragmatic linkages to gymnastics as it exists and is practiced. This article attempts to bridge the gap between the scientific and medical community and what actually happens in gymnastics.

Women's gymnastics injuries. A 5-year study.

A 5-year prospective study on the time course of women's gymnastics injuries was conducted on a successful NCAA Division I team. Gymnasts recorded injuries on a computer terminal or via computer dot sheets immediately before each training session, including the injured body part, the event or activity, and the date of the injury. The definition of injury was "any damaged body part that would interfere with training." Athletes recorded injuries on the 1st day of onset and subsequently until the injury was healed. The initial onset of injury was considered a new injury. Subsequent records of the injury were considered continuing injury. Thirty-seven athletes participated through five collegiate seasons. They accounted for 5602 total training exposures with an average of 151.4 exposures per athlete. The analyses showed that gymnasts trained with an injury approximately 71% of the exposures, and a new injury could be expected from a gymnast during approximately 9% of the exposures. The largest number of injuries were of the repetitive stress syndrome type. The time series information showed that total injuries tended to increase until the middle of the competitive season, while new injuries showed prominent increases during specific training periods and during competition preparation and performance.

A comparison of subtalar joint maximal eversion while jogging on the minitrampoline and floor.

The jogging minitrampoline is a common tool for exercise and rehabilitation that is lauded as helpful in reducing lower extremity stresses. The deformable bed of the minitrampoline may result in altered jogging mechanics of the subtalar joint, potentially leading to uncharacteristic mechanics of the lower extremity. The purpose of this study was to examine eversion of the subtalar joint in subjects jogging on the minitrampoline vs. a wooden floor surface. Subjects were instrumented with a flexible electrogoniometer (elgon) taped from the heel to the gastrocnemius along the Achilles tendon. The elgon was interfaced to a personal computer. Data were examined for the average maximal eversion values of five steps during jogging in two experiments. Results of the first experiment (N = 27) indicated significantly greater mean maximal eversion angles while jogging on the minitrampoline than on the floor. The second experiment involved 10 male and 10 female subjects jogging for 20 minutes with a counterbalanced sequence of jogging conditions, alternating between the floor and the minitrampoline. The second experiment indicated that maximal eversion angles were significantly greater on the minitrampoline than on the floor and increasing jogging time resulted in greater eversion angles and a significant interaction between jogging condition and time. Results suggest that people who should avoid valgus deviations to the lower leg should not jog on the jogging minitrampoline.

Kinesiological motion expert system.

Kinesiology builds on anatomical information by establishing which muscles contribute to human motion and to what extent. This 'body as machine' approach seeks to identify particular muscles as contractile 'engines'. The learning of muscular contributions to human motions based on long tables of origins, insertions, innervations, and actions is tedious and often incomplete based on author judgments of which muscles and motions to include. The kinesiological motion expert system (KMES) was developed so that students could easily select joints, actions, and tension types and receive computerized output listing the muscles that could contribute to the motion requested. In addition, a student can select a particular muscle and tension type and the program will return all of the motions that the selected muscle might contribute. The KMES was written in PDC Prolog and has a knowledge base of 1583 movements. Implementation of the KMES in kinesiology classes resulted in an increase in average student final scores of approximately 15% (F(3,190) = 12.11, P < 0.0001).

Peripheral vision and back tuck somersaults.

Although vision appears to enhance performance of somersaulting skills, few studies have investigated the source (foveal or ambient) of useful visual cues that can potentially be used by gymnasts during a somersault. Therefore, the primary objectives were to investigate the possible role of peripheral vision in the control of orientation and landing balance in a back tuck somersault. 10 female gymnasts (age = 11.6 +/- 2.7 yr., competitive level = 8 +/- 1.2, training time in gymnastics = 5.9 +/- 1.6 yr.) performed back tuck somersaults under four visual conditions (full visual field, horizontal peripheral vision limited to 100 degrees, horizonal peripheral vision limited to 60 degrees, and no vision) while wearing electromagnetic sensors that allowed automatic digitizing. Analysis yielded no statistically significant difference on any of the kinematic variables among vision conditions. Despite limiting the gymnasts' available horizontal peripheral vision, joint angles, angular velocities, and timing remained very similar. There were no statistically significant differences in landing balance between the conditions of full vision, 100 degrees peripheral vision, and 60 peripheral vision. However, gymnasts were less stable at landing when vision was absent as compared to the three other vision conditions.

Inhibition of pro-inflammatory cytokine receptor signalling by cAMP in vascular endothelial cells.

The anti-inflammatory effects of the prototypical second messenger cAMP have been extensively documented in multiple cell types. However, in many instances, the molecular mechanisms by which cAMP elevation disrupts specific pro-inflammatory signalling cascades are unknown. In this review, we will describe the importance of the JAK-STAT (where JAK stands for Janus kinase and STAT for signal transducer and activator of transcription) signalling pathway in vascular endothelial cell function, outline key inhibitory processes that serve to reduce cytokine-stimulated tyrosine phosphorylation and activation of STAT proteins, and discuss possible mechanisms by which intracellular cAMP sensors could interact with these inhibitory processes to diminish cytokine receptor-mediated pro-inflammatory signalling.

The role of a phosphatidylcholine-specific phospholipase C in the production of diacylglycerol for nitric oxide synthesis in macrophages activated by IFN-gamma and LPS.

Murine macrophages activated by interferon (IFN)-gamma and bacterial lipopolysaccharide (LPS) produce large amounts of nitric oxide (NO), which is a critical mediator for a variety of biological functions. The expression of this inducible NO synthase (iNOS) involves a protein kinase C (PKC)-dependent pathway, but the mechanism for the PKC activation in this system is unclear. Through analysis of diacylglycerol (DAG) synthesis and choline metabolism in activated macrophages, direct evidence is provided that NO synthesis involves the activation of an unusual phosphatidylcholine-specific phospholipase C (PC-PLC) and not a phosphatidylinositol-specific phospholipase C (PI-PLC) or phospholipase D (PLD).

[Evolution of the physiological profile of gymnasts over the past 40 years. A review of the literature]. / Evolution du profil physiologique des gymnastes durant les 40 dernieres annees (revue de littérature).

Authors illustrate the evolution of the physiological profile of gymnasts over the past 40 years. Gymnasts are demonstrating increased anaerobic power. Maximal power output measured by the Wingate test in high level male gymnasts is currently between 12 and 14 W x kg(-1). Female gymnasts show maximal power between 10 and 12 W x kg(-1). In spite of an increase in the number of training hours, they have a low aerobic aptitude. It is still adequate and sufficient for their practice. Maximal heart rate values measured during gymnastic exercises have mirrored technical and acrobatic demands of increasing difficulty. Currently, exercise heart rates exceed 190 beat x min(-1) as compared to 135 to 151 beat x min(-1) in the seventies. Measurement of higher blood lactate values suggests that anaerobic glycolysis has increased in importance. Glycolytic contributions differ between apparatuses. Data from energy cost studies demonstrate that gymnastics energy demands are greater now than in the seventies.

The role of vision in control of orientation in a back tuck somersault.

During a back tuck somersault, the angular velocity of the head is thought to surpass the visual system's ability to maintain a distinct and continuous picture of the environment. The primary objectives of this research were to determine if differences existed with regard to trunk and lower body kinematics, as well as landing balance, when gymnasts perform back tuck somersaults under different vision conditions. Ten female gymnasts (age = 11.6 +/- 2.67 years, competitive level = 8 +/- 1.15, and training time in gymnastics = 5.9 +/- 1.63 years) performed back tuck somersaults under 4 vision conditions while wearing electromagnetic sensors that allowed automatic digitizing. Although no significant differences were found between vision conditions with regard to timing, joint angles, and joint angular velocities, gymnasts were more stable at landing under conditions that allowed vision during either the entire somersault or the last half of the sumersault.

Inhibition of nitric oxide synthesis by interleukin-4 may involve inhibiting the activation of protein kinase C epsilon.

The murine macrophage cell line, J774, when activated with interferon-gamma (IFN-gamma), expressed high level of inducible nitric oxide synthase (iNOS) and bound significantly more [3H]-phorbol-dibutyrate (PBu2) compared to non-activated cells. The increased PBu2 binding to the particulate fraction of the cells is a measure of activation and translocation of protein kinase C (PKC). Both the expression of iNOS and the enhanced. PBU2 binding in the activated J774 cells were significantly inhibited by the pretreatment of the cells with murine recombinant interleukin-4 (IL-4). Stimulation of J774 cells by IFN-gamma and lipopolysaccharide results in the translocation predominantly of the epsilon isoform of PKC (PKC-epsilon), and this is inhibited by IL-4. The inhibition of PKC activation was also evident by measuring the PKC activity in the cytosolic-fraction of the IL-4-treated cells. Activated J774 cells pretreated with IL-4 or a PKC-specific inhibitor (RO31-8220) failed to express mRNA of iNOS analyzed by PCR. These results, therefore, suggest that the inhibition of nitric oxide synthesis in activated murine macrophages by IL-4 is at the transcriptional level and may involve the inhibition of the activation of PKC-epsilon.

Is the induction of apoptosis the mechanism of the protective effects of TNF alpha in helminth infection?

Tumour necrosis factor alpha has been implicated in protective immune responses to a number of parasitic helminths. However, the final effector mechanisms resulting in death or expulsion of the parasite are unclear. Here we suggest that, by employing phylogenetically conserved mechanisms, the mammalian immune system is able to interfere with helminth development directly and that the protective effects of TNF alpha in helminth infections may operate via the induction of parasite apoptosis.

Mice defective in Fas are highly susceptible to Leishmania major infection despite elevated IL-12 synthesis, strong Th1 responses, and enhanced nitric oxide production.

MRL/MP-lpr/lpr (MRL/lpr) mice have a single mutation (lpr) of the fas apoptosis gene. The mutant mice developed significantly smaller lesions than the wild-type mice at the earlier stage of infection with the intracellular protozoan parasite Leishmania major. However, while all the wild-type mice achieved complete lesion resolution, the disease in the mutant mice progressed inexorably. The mutant mice had more IL-12 and nitrite/nitrate in the serum than wild-type mice following infection. Lymphoid cells from infected MRL/lpr mice produced more IFN-gamma but less IL-4 and IL-5 than cells from MRL-+/+ mice. Peritoneal macrophages from the mutant mice also produced more IL-12 and NO after stimulation with LPS. Thus, Fas expression is essential for resistance against leishmaniasis, and Fas-mediated apoptosis may form an integral part of the Th1-mediated microbicidal function.

Regulation of macrophage IL-12 synthesis by Leishmania phosphoglycans.

It is now generally accepted that IFN-gamma, secreted by Th1 cells, is the most potent cytokine leading to macrophage activation and host resistance against infection with the intracellular protozoan parasite Leishmania. It is also established that IL-12 is a critical cytokine involved in the differentiation and expansion of Th1 cells. Therefore, the ability of Leishmania parasites to actively suppress IL-12 production by host macrophages may be an important strategy for parasite survival. Here we report that a major parasite cell surface molecule, phosphoglycan (PG), of Leishmania could selectively inhibit the synthesis of IL-12(p40, p70) by activated murine macrophages. Furthermore, synthetic PG (sPG) was able to inhibit IL-12 release in a dose-dependent manner. Inhibition was dependent on the galactose(beta1-4)mannose(alpha1)-PO4 repeating units and not the glycophosphoinositol lipid anchor of lipophosphoglycan. At the concentration used, sPG had no effect on the release of TNF-alpha or IL-6 in activated macrophages. The inhibition of IL-12(p40) production was at the transcriptional level, but was not mediated through NF kappaB inhibition. These data demonstrate that PG may be an important molecule for the establishment and survival of the parasite in permissive hosts.