Bone mineral density and lean mass asymmetries are greater in cyclists than non-cyclists.

Cyclists may be at greater risk of developing asymmetrical force and motion patterns than other ground-based athletes. However, functional asymmetries during cycling tend to be highly variable, making them difficult to assess. Dual-energy x-ray absorptiometry (DXA) measurements of areal bone mineral density (aBMD) and lean mass (LM) in the lower limbs may be a more sensitive and consistent method to identify asymmetries in cyclists. The goal of this study was to determine if competitive cyclists have greater levels of asymmetries in the lower body compared to non-cyclists using DXA. A secondary aim was to determine if aBMD and LM asymmetries change over the road cycling season. 17 competitive cyclists and 21 non-cyclist, healthy controls underwent DXA scans. Lower-body asymmetries were greater in cyclists compared to non-cyclists in aBMD and LM for all lower limb segments. However, these asymmetries did not tend to consistently favour a particular side, except for the pelvis having more LM on the dominant side. The were no longitudinal changes in aBMD or LM in the cyclists. Asymmetry analysis via DXA provides evidence that although functional asymmetries during cycling are variable, cyclists have increased lower body LM and aBMD asymmetries compared to non-cyclists.

Effect of temperature on race times on a synthetic surface.

REASONS FOR PERFORMING STUDY: Differences in racing times have been noted on synthetic track surfaces that appear to depend on the temperature of the track. No published study to date has considered this effect in a systematic manner. OBJECTIVES: To investigate the relationship between temperature of track and speed of horses racing on a synthetic surface. Potential changes in the wax component of the synthetic track were investigated as one possible cause of changes in the track speed at the temperatures observed. METHODS: At Del Mar racetrack (California, USA), the air, surface and subsurface temperatures at 4 depths in the synthetic race surface were measured periodically throughout the day over a 42 day period. The 6 furlong (1.2 km) race (afternoon) and fast training 'work' (morning) times were also compiled. Samples of the track were obtained and the wax separated using a solvent separation technique. Differential scanning calorimetry was used to determine the range of temperatures at which the wax from the track underwent softening and other material changes. Transformation temperatures were compared to temperatures acquired from the track to evaluate the likelihood of changes in the wax properties during racing. RESULTS: Average air, surface and subsurface temperatures changed significantly throughout the day. Temperatures were higher during the afternoon race sessions and race times were significantly slower compared to morning work times. Temperatures at which some of the components of the wax began to soften were found to be within the range of temperature measured during track operation. CONCLUSIONS: A correlation was found between temperature of the synthetic track and speed of horse. Wax separated from the track showed that the temperatures experienced in the surface during normal operation exceed the temperatures at which the wax begins to experience thermal transformation. It is therefore hypothesised that the wax may be a cause of the observed changes in the track performance. POTENTIAL RELEVANCE: Future work should include a study of components of the synthetic track responsible for the change and epidemiological association of risk of injury.

Cycling on rollers: Kreitler fan resistance at submaximal levels of effort.

The goal of this investigation was to characterize the commercially available fan unit for the KreitlerAlloy rollers at submaximal levels of effort (< or = 500 W). A single cyclist rode six times at each of three fan inlet settings (closed, half, and full open) and five fan speeds (900, 1800, 2700, 3600, and 4500 rpm). Fan power requirements were isolated by subtracting roller resistance from separate trials. Power requirements relative to fan inlet and fan speed possessed a significant interaction with the main effects for each also significant (all p < 0.001). Power increased to the cube of fan speed, regardless of inlet opening (r2 > or = 0.997). Fan resistance was virtually non existent at 900 rpm. Fan resistance then significantly increased with increasing fan speed and inlet opening. At 4500 rpm power requirements of the fan reached 269 +/- 6, 352 +/- 7, and 406 +/- 9 W with the inlet closed, half, and fully open, respectively (p < 0.001). The rear wheel-roller interaction supplied an additional 19 +/- 2 W on up to 104 +/- 4 W at the highest speed. Therefore, the fan unit increases the functionality of the rollers for a variety of training and testing environments.

The role of nitric oxide in the emotional learning of rats in the plus-maze.

The present study evaluated the role of nitric oxide (NO) in the transfer latency (TL) paradigm in the elevated plus-maze. Male Wistar rats received i.p. injections of either 0.9% Saline, N(omega) Nitro-L-arginine-methyl-ester (L-NAME, an inhibitor of NO synthesis), d-NAME (inert isomer), scopolamine (SCO, antagonist of muscarinic receptors), or MK-801 (antagonist of NMDA receptors) and, after 30 min, were submitted to TL procedure. In an independent experiment, the ability of the same L-NAME treatments in changing the arterial pressure and blood glucose level (BGL) was evaluated in conscious rats. The treatment with SCO (1 mg kg(-1)), MK-801 (0.15 mg kg(-1)) and L-NAME (10 and 50 mg kg(-1)), but not with D-NAME, impaired the TL learning. The L-NAME-induced TL deficit was counteracted by L-ARG (100 and 200 mg kg(-1)), while the co-administration of sub-effective doses of L-NAME and MK-801 failed to impair the TL learning. The L-NAME (50 mg kg(-1)) treatment failed to alter the BGL. All treatments with L-NAME induced hypertension, but the rats treated with L-NAME (5 mg kg(-1)) were still able to learn the TL task. The data indicate that the TL deficit induced by L-NAME (10 and 50 mg kg(-1)) is not due to either hypertension or changes in the BGL. It is also possible to establish that NO production is important for emotional learning underlying the TL procedure in rats.

Inertial effects on mechanically braked Wingate power calculations.

PURPOSE: The standard procedure for determining subject power output from a 30-s Wingate test on a mechanically braked (friction-loaded) ergometer includes only the braking resistance and flywheel velocity in the computations. However, the inertial effects associated with accelerating and decelerating the crank and flywheel also require energy and, therefore, represent a component of the subject's power output. The present study was designed to determine the effects of drive-system inertia on power output calculations. METHODS: Twenty-eight male recreational cyclists completed Wingate tests on a Monark 324E mechanically braked ergometer (resistance: 8.5% body mass (BM), starting cadence: 60 rpm). Power outputs were then compared using both standard (without inertial contribution) and corrected methods (with inertial contribution) of calculating power output. RESULTS: Relative 5-s peak power and 30-s average power for the corrected method (14.8 +/- 1.2 W x kg(-1) BM; 9.9 +/- 0.7 W x kg(-1) BM) were 20.3% and 3.1% greater than that of the standard method (12.3 +/- 0.7 W x kg(-1) BM; 9.6 +/- 0.7 W x kg(-1) BM), respectively. Relative 5-s minimum power for the corrected method (6.8 +/- 0.7 W x kg(-1) BM) was 6.8% less than that of the standard method (7.3 +/- 0.8 W x kg(-1) BM). The combined differences in the peak power and minimum power produced a fatigue index for the corrected method (54 +/- 5%) that was 31.7% greater than that of the standard method (41 +/- 6%). All parameter differences were significant (P < 0.01). The inertial contribution to power output was dominated by the flywheel; however, the contribution from the crank was evident. CONCLUSIONS: These results indicate that the inertial components of the ergometer drive system influence the power output characteristics, requiring care when computing, interpreting, and comparing Wingate results, particularly among different ergometer designs and test protocols.

Staphylococcus aureus isolates from patients with Kawasaki disease express high levels of protein A.

Kawasaki disease (KD) is an acute vasculitis of young children that can be complicated by coronary artery abnormalities. Recent findings suggest that a superantigen(s) may play an important role in stimulating the immune activation associated with the disease, although the origin of this superantigen(s) is unclear. Staphylococcus aureus, isolated from the rectum or pharynx of patients with KD, secretes toxic shock syndrome toxin 1 (TSST-1). The KD isolates express low levels of other exoproteins compared to isolates from patients with toxic shock syndrome (TSS). Thus, it was previously suggested that the KD isolates may be defective in the global regulatory locus agr (for accessory gene regulator), which positively regulates these factors (D. Y. M. Leung et al., Lancet 342:1385-1388, 1993). Here we describe another characteristic of KD isolates. When considered collectively, the KD isolates were found to express higher levels of staphylococcal protein A than the TSS isolates, another characteristic of an agr-defective phenotype. This correlated with a higher level of spa mRNA in these isolates. In contrast, the KD and TSS isolates expressed comparable levels of TSST-1, consistent with previous findings (D. Y. M. Leung et al., Lancet 342:1385-1388, 1993). Analysis of RNAIII transcript levels and nucleotide sequence analysis of the RNAIII-coding region suggested that the KD isolates are not defective in RNAIII, the effector molecule of the agr regulatory system. However, induction of RNAIII transcription in the KD isolates did not result in a dramatic decrease in the amount of spa mRNA, as has been reported for other strains (F. Vandenesch, J. Kornblum, and R. P. Novick, J. Bacteriol. 173:6313-6320, 1991).

Determination of alkylbenzenesulfonates in recent sediments by gas chromatography/mass spectrometry.

Alkylbenzenesulfonates together with soap are the most widely used anionic surfactants. Linear alkylbenzenesulfonates (LAS) were introduced in the mid-1960s as substitutes for the poorly biodegradable tetrapropylenebenzenesulfonates (TPS). A method is presented for the selective and quantitative determination of LAS and TPS in recent sediments. Alkylbenzenesulfonates were extracted from sediments using methanol. The methanolic extract was passed through a strong anionic exchange column. The alkylbenzenesulfonates contained in the acidic eluate were then derivatized to their corresponding trifluoroethyl esters and quantitatively determined by gas chromatography/mass spectrometry using positive chemical ionization. Limits of quantitation for 10 g sediment samples varied between 1.5 and 21 µg/kg of dry sediment for single LAS isomers and between 71 and 220 µg/kg for total LAS. Limits of quantitation for the total of TPS were at ∼200 µg/kg. Relative standard deviations of replicate analyses typically ranged from 5 to 10%. Recovery rates of LAS in spiked sediment samples ranged from 79 to 113%. The presented method was applied to surface and subsurface sediments also containing long-chain (C(14)-C(16))-LAS and mixtures of LAS and TPS.

Staphylococcal toxins and protein A differentially induce cytotoxicity and release of tumor necrosis factor-alpha from human keratinocytes.

It has been proposed that toxins and other bacterial protein products of Staphylococcus aureus can act as triggers or persistence factors in several inflammatory skin diseases. In this study, we examined the S. aureus isolates from the skin of patients with atopic dermatitis and psoriasis. We found that the bacterial isolates from these patients exhibited either characteristic superantigenic toxins or thermolabile toxins believed to be staphylococcal alpha-toxin. All of these staphylococcal strains also secreted extracellular staphylococcal protein A. We found significant differences in the action of these toxins on human keratinocytes and keratinocyte cell lines. The superantigenic toxins toxic shock syndrome toxin-1, staphylococcal enterotoxins A and B, and exfoliative toxin-A, as well as staphylococcal protein A, did not induce significant cytotoxic damage in the keratinocyte cell line HaCaT, whereas the staphylococcal alpha-toxin produced profound cytotoxicity. Keratinocyte cytotoxicity induced by staphylococcal alpha-toxin was time and concentration dependent and demonstrated the morphologic and functional characteristics of necrosis, not apoptosis. Addition of alpha-toxin to keratinocytes simultaneously induced cell lysis and tumor necrosis factor-alpha release into the medium within 30 min; apparently, it was constitutive tumor necrosis factor-alpha. On the other hand, superantigenic toxins and, in particular, protein A showed stimulation of tumor necrosis factor-alpha secretion in keratinocytes and release of this cytokine after 6-12 h of incubation. Thus, staphylococcal protein A, alpha-toxin, and superantigenic toxins found in S. aureus isolates from patients with psoriasis and atopic dermatitis can produce direct pro-inflammatory effects on keratinocytes through the release of tumor necrosis factor-alpha. We propose that these effects may be relevant to the induction and persistence of lesions in these two diseases.

Presence of IgE antibodies to staphylococcal exotoxins on the skin of patients with atopic dermatitis. Evidence for a new group of allergens.

In the current study, we investigated whether Staphylococcus aureus grown from affected skin of atopic dermatitis (AD) patients secreted identifiable toxins that could act as allergens to induce IgE-mediated basophil histamine release. The secreted toxins of S. aureus grown from AD patients were identified by ELISA using antibodies specific for staphylococcal enterotoxin (SE) exfoliative toxin (ET), or toxic shock syndrome toxin (TSST-1). S. aureus isolates from 24 of 42 AD patients secreted identifiable toxins with SEA, SEB, and TSST accounting for 92% of the isolates. 32 of 56 AD sera (57%) tested contained significant levels of IgE primarily to SEA, SEB, and/or TSST. In contrast, although SEA, SEB, or TSST secreting S. aureus could be recovered from the skin of psoriasis patients, their sera did not contain IgE antitoxins. Freshly isolated basophils from 10 AD patients released 5-59% of total histamine in response to SEA, SEB, or TSST-1 but only with toxins to which patients had specific IgE. Basophils from eight other AD patients and six normal controls who had no IgE antitoxin failed to demonstrate toxin-induced basophil histamine release. Stripped basophils sensitized with three AD sera containing IgE to toxin released 15-41% of total basophil histamine only when exposed to the relevant toxin, but not to other toxins. Sensitization of basophils with AD sera lacking IgE antitoxin did not result in release of histamine to any of the toxins tested. These data indicate that a subset of patients with AD mount an IgE response to SEs that can be grown from their skin. These toxins may exacerbate AD by activating mast cells, basophils, and/or other Fc epsilon-receptor bearing cells armed with the relevant IgE antitoxin.

Production of enterotoxins and toxic shock syndrome toxin by bovine mammary isolates of Staphylococcus aureus.

The production of staphylococcal enterotoxin A (SEA), SEB, SEC, SED, and SEE and toxic shock syndrome toxin 1 by bovine mammary isolates of Staphylococcus aureus was evaluated. Enterotoxin secretion was detected by immunodiffusion using specific polyclonal antisera. Of 262 isolates examined, 75 (28.6%) produced one or more toxins. The most common pattern was secretion of both SEC and SED and toxic shock syndrome toxin 1. No isolates secreted SEE, one produced SEA, and seven secreted SEB.

Application of microcolumn liquid chromatography-continuous-flow fast atom bombardment mass spectrometry in environmental studies of sulfonylurea herbicides.

The use of 0.25-mm I.D. packed capillary liquid chromatography columns coupled with continuous-flow fast atom bombardment (FAB) mass spectrometry has proven to be a very valuable technique, especially for the identification of unknown sulfonylurea herbicide metabolites. Several new and unusual heterocycle ring-opened metabolites and hydrolysis products were identified, and metabolic pathways were proposed. Typical column flow-rates are 1-2 microliters/min, which allows direct coupling with no sample splitting. This is important in our metabolite identification work, since we are usually sample-limited. Techniques for increasing injection volume to allow analyses of dilute solutions and the use of polymeric packing for separation of polar metabolites are discussed. The FAB mass spectra usually provide unequivocal molecular weights and structurally useful fragments ions, which often allows structure assignments on exceedingly small quantities of isolated metabolites.

Reaction of toxic shock syndrome toxin 1 with endothelium of human umbilical cord vein.

The binding of toxic shock syndrome toxin 1 (TSST-1) to the endothelium of human umbilical cord veins and arteries was studied. Radiolabeled TSST-1, perfused through a segment of human umbilical cord vein, bound to the vessel at 4 degrees C, with a dissociation constant (Kd) of 6.5 X 10(-10) M. A pre-embedding electron-microscopic immunogold technique revealed that TSST-1 was located in the veins and arteries on the surface of endothelial cells and in the area of cell contacts. Umbilical cord vein segments filled with TSST-1 were incubated for 30 minutes at 37 degrees C, fixed by perfusion and embedded in hydrophilic resin (Lowicryl K4M). Postembedding immunogold staining of ultrathin sections showed TSST-1 in the vesicles crossing the cytoplasm of the veins' endothelial cells and entering underlying elastic and collagen layers.

Effects of blood and different media on the production of toxic shock syndrome toxin 1 by Staphylococcus aureus in the tampon sac method.

The use of three different agar concentrations in the tampon sac method resulted in slightly higher fluid uptake by the tampons when a 0.5% agar concentration was used. However, there was essentially no difference in the total amount of toxin produced. The largest amount of toxic shock syndrome toxin 1 was produced with brain heart infusion agar, followed closely by 3% NZ-amine NAK-1% yeast extract medium. The addition of plasma and serum to the inoculum resulted in increases (62 and 73%, respectively) in toxin production. The addition of whole blood to the inoculum had a variable effect on toxin production, with an increase in the amount of toxin produced with some tampons and not with others. Over fivefold differences in the amount of toxin produced were obtained when duplicate experiments were done on successive days, whereas the differences were less than twofold for experiments done on the same day. This was related to the effect of small changes in the parameters on toxic shock syndrome toxin 1 production.

Chromatofocusing in the purification of staphylococcal enterotoxin D.

A chromatofocusing procedure for the purification of staphylococcal enterotoxin D was developed. The purification included the removal of the toxic protein from culture supernatant fluids of Staphylococcus aureus 1151m by batch adsorption with CG-50 resin, chromatofocusing on Polybuffer Exchanger 94, and gel permeation chromatography on Sephacryl S-200. The purity of the staphylococcal enterotoxin D obtained was approximately 98%.

The erect penis--injury prone organ.

Erection converts the safe, flaccid penis into a vulnerable organ. During erection, the usually thick tunica albuginea becomes very thin and easily fracturable. Penile fracture is an under-reported urologic injury, with only approximately 100 cases reported in the world literature. We report on three cases, one with rupture of one corpus spongiosum and two with rupture of both corpora cavernosa associated with almost complete transection of the urethra. All three cases were treated surgically, with good outcome and no postoperative complications. The authors postulate that some cases of deviation of the penis are actually the result of some minor degree of penile fracture.

Low incidence of toxic shock syndrome in children with staphylococcal infection.

Children have frequent staphylococcal infections, and many lack antibody to TSST-1, a toxin associated with the toxic shock syndrome (TSS). To determine why there have been no nonmenstrual cases of TSS reported in children in Utah, the authors tested S. aureus isolated from children for TSST-1 by radial immunodiffusion and sera from other hospitalized children by radioimmunoassay for antibody to TSST-1. TSST-1 was produced by 25% of S. aureus. Fifty-two children had infections with toxin producing strains. None had TSS. The prevalence of presumably protective levels of antibody (greater than or equal to 1:100) was high in newborns (80%), declined until age 2 years and then gradually increased with age. Therefore, there may have been about 20 children with toxigenic infection who lacked protective antibody but did not show the usual features of TSS. We conclude that the rarity of TSS in children is not caused by misdiagnosis, underreporting, or the absence of toxigenic strains or susceptible patients. Additional factors, such as local conditions or duration of carriage, may influence the clinical presentation of infection with TSST-1 producing staphylococci.

Production of toxic shock syndrome toxin 1 by Staphylococcus aureus as determined by tampon disk-membrane-agar method.

The influence of 17 commercially available tampons on production of toxic shock syndrome toxin 1 (TSST-1) by Staphylococcus aureus was investigated by using a tampon disk method. Filter membranes overlaying agar medium (with or without blood) in small petri dishes were spread inoculated with a TSST-1-producing strain of S. aureus. Disks cut from unrolled tampons were pressed and laid on the inoculated membranes; incubation was for 19 h at 37 degrees C with 5% CO2 in air. CFU on the membranes and in the disks were enumerated, and the presence of TSST-1 in the disks and in the agar layers was determined. Tampons made of different materials supported characteristic levels of cell growth and toxin production in the tampon. Colonization of the interface surface of the tampon disks was heavy. The number of CFU extracted from the tampon disks ranged from 5 X 10(10) to 82 X 10(10). There was little variation in the CFU recovered from the membranes ([1.9 +/- 0.4] X 10(11)). Sixty to 170 micrograms of TSST-1 was recoverable from the agar, with an additional 10 to 90 micrograms recoverable from tampon disks, depending on the type of tampon disk. The amount of toxin in the agar layer from the various tampon disks was relatively constant and indicated an important contribution of toxin from vaginal S. aureus cells not growing in the tampon. The main role of tampons in toxic shock syndrome may be that of providing a fibrous surface for heavy colonization and sufficient air for TSST-1 production.

Production of toxic shock syndrome toxin 1 by Staphylococcus aureus restricted to endogenous air in tampons.

All types of four brands of tampons were tested in triplicate by a tampon sac method for their effect on production of toxic shock syndrome toxin 1 (TSST-1). In this method the available air is limited to that which is in the tampon sac. Tampons were weighed and inserted into dialysis sacs inoculated with a TSST-1-producing Staphylococcus aureus strain; the sacs were submerged into brain heart infusion agar, which was allowed to harden around the sacs, and were incubated for 18 h at 37 degrees C. The tampons were removed, weighed, and extracted; the CFU of staphylococci and the amount of toxin present in the extracts were determined. Glass wool was used in place of the tampons as one control, and inoculated empty sacs were used as a second control. The total CFU were consistently greater than 2 X 10(11) for the tampons and glass wool and less than or equal to 10(11) for the empty sac control. Total toxin production for all tampons tested and the glass wool was 2 to 10 times higher than the toxin produced with the empty sac control. These results indicate that tampons provide increased surface area for the staphylococci to grow and adequate oxygen for toxin production. No significant inhibition of growth of the staphylococci or TSST-1 production by any of the tampons tested was noted.