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.

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.

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.

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.

Oversimplification of diet: coronary heart disease relationships and exaggerated diet recommendations.

The data relating diet to coronary heart disease, when critically examined, clearly show that there is a normal spectrum of blood serum values, and that normal persons do not develop pathological levels upon the ingestion of eggs and other cholesterol-containing the ingestion of large amounts of cholesterol-containing foods. Average data obtained from mixed populations of normal and pathological blood lipid values should not be used to advise the normal majority of that population. The harmful effects of such policy are outlined. The data demonstrating the concept that the risk of coronary heart disease is a function of serum lipids at any level is no longer valid are reviewed. The data of the National Cooperative Pooling Project of the American Heart Association are used to show that up to 250 mg/dl there is no relationship between serum cholesterol concentration and risk.

A commentary on the Rationale of the Diet-Heart Statement of the American Heart Association.

The objective of the Rationale of the Diet-Heart Statement of the American Heart Association was to restate the diet-heart recommendations of the American Heart Association and to quote the original publications on which they are based. Examination of those publications reveals that for the most part, they are obsolete or misquoted. The last section of the Rationale concerns the role of genetics and very briefly reviews the epidemiological and dietary intervention trial evidence. The latter discussion may be summarized as meaning that risk levels are in the 90 percentile group of plasma cholesterol levels and that those levels are due to genetic factors which "dietary changes alone cannot normalize." It admits that "all" dietary intervention trials "were flawed in one or another aspect of experimental design." Hope is expressed that the Multiple Risk Factor Intervention Trial and the Lipid Research Clinics Primary Prevention Trial will support the diet-heart theory. The former did not and the latter was designed to test cholestyramine and not diet.

Plasma lipid and lipoprotein response of humans to beef fat, coconut oil and safflower oil.

This study's purpose was to evaluate the fasting human plasma lipid and lipoprotein responses to dietary beef fat (BF) by comparison with coconut oil (CO) and safflower oil (SO), fats customarily classified as saturated and polyunsaturated. Nineteen free-living normolipidemic men aged 25.6 +/- 3.5 yr consumed centrally-prepared lunches and dinners of common foods having 35% fat calories, 60% of which was the test fat. The test fats were isocalorically substituted, and each fed for five weeks in random sequences with intervening five weeks of habitual diets. Plasma total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) concentrations among individuals follows the same relative rank regardless of diet. Triglycerides (TG) concentrations among individuals also maintain their relative rank regardless of diet but in a different order from that of the cholesterols. Plasma TC, HDL-C, and LDL-C responses to BF were significantly lower and TG higher than to CO. As compared to SO, BF produced equivalent levels of TG, HDL-C, and LDL-C and marginally higher TC. Thus, the customary consideration of BF as "saturated" and grouping it with CO appears unwarranted.

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.

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.

Gas-liquid chromatographic analysis of cyclopropene fatty acids.

A gas-liquid chromatographic method is described for the quantitative estimation of cyclopropene fatty acids as their methyl mercaptan derivatives. This method estimates individual cyclopropene acids as well as normal and cyclopropane acids. Nine seed oils were analyzed for their cyclopropene fatty acid content.Evidence was obtained for the presence of a cyclopropene fatty acid of shorter chain length than malvalic inAlthaea rosea cav and one with a higher chain length than sterculic inBombacopsis glabra seed oil. This method is less accurate for cottonseed oil than for the other oils tested because of the appearance of some unsymmetrical peaks of unknown origin.The mercaptan derivatives of the cyclopropene acids may be isolated by silver ion thin-layer chromatography.Small amounts of cyclopropane fatty acids were found in a number of the oils analyzed for cyclopropene fatty acids.

Gas-liquid chromatography of triglyceride mixtures containing both odd and even carbon number fatty acids.

Quantitative GLC of triglycerides has been extended to natural fats containing both odd and even carbon number fatty acids. A 1.83-m glass column containing 3.0% JXR silicone on 100/120 mesh Gas-Chrom Q resolved triglycerides differing by only one carbon number. Peak resolution was significantly improved by hydrogenating each triglyceride sample prior to GLC analysis.The triglycerides of four fish oils (mullet, tuna, menhaden, and pilchard) and one seed fat (Acanthosyris spinescens) containing odd carbon number fatty acids were analyzed by this technique. The method was also useful for determining the triglyceride composition of the cyclopentene fatty acid oil fromHydnocarpus wightiana seeds.

Resistance of certain long-chain polyunsaturated fatty acids of marine oils to pancreatic lipase hydrolysis.

When whale oil triglycerides were subjected to pancreatic lipase hydrolysis, eicosapentaenoic and docosahexaenoic acids were found mainly in the di- and triglyceride products, suggesting that they are in the 1,3-positions but resistant to the action of the lipase. Their presence in the 1,3-positions was confirmed. Their resistance to pancreatic lipase hydrolysis was demonstrated by analysis of the products of the enzyme action on: (a) a concentrate of highly unsaturated whale oil triglycerides; (b) the latter after randomization; and (c) synthetic 1,2-di-octadecenoyl-3-eicosapentaenoyl glycerol.Docosapentaenoic acid was also shown to be present in the 1,3-position of whale oil triglycerides but was not lipase resistant. It is postulated that the presence of a double bond near the carboxyl group exercises an inhibitory effect, or that the location of the double bonds in the resistant acids places their terminal methyl groups close to the carboxyl, producing a steric hindrance effect.

Gas-liquid chromatography of triglycerides from erucic acid oils and fish oils.

By critically selecting optimum operating conditions, quantitative gas-liquid chromatography of triglycerides has been extended to molecules containing substantial amounts of C(20), C(22), and C(24) fatty acids. The triglycerides of four erucic acid oils (water cress, rapessed, nasturtium, andLunaria annua) and two fully hydrogenated fish oils (menhaden and tuna) have been quantitatively analyzed by this technique. The average fatty acid chain length calculated from the triglyceride composition of each oil agreed closely with that determined by GLC of its respective methyl esters. Several conclusions about the triglyceride composition of the fats analyzed are discussed.

The triglyceride composition of 17 seed fats rich in octanoic, decanoic, or lauric acid.

Seed fats of eight species ofLauraceae (laurel family), six species ofCuphea (Lythraceae family), and three species ofUlmaceae (elm family) were extracted, and the triglycerides were isolated by preparative thin-layer chromatography. GLC of the triglycerides on a silicone column resolved 10 to 18 peaks with a 22 to 58 carbon number range for each fat. These carbon number distributions yielded considerable information about triglyceride compositions of the fats.The most interesting finding was withLaurus nobilis seed fat, which contained 58.4% lauric acid and 29.2-29.8% trilaurin. A maximum of 19.9% trilaurin would be predicted by a 1, 2, 3-random, a 1, 3-random-2-random, or a 1-random-2-random-3-random distribution of the lauric acid(3). This indicates a specificity for the biosynthesis of a simple triglyceride byLaurus nobilis seed enzymes.Cuphea lanceolata seed fat also contained more simple triglyceride (tridecanoin) than would be predicted by the fatty acid distribution theories.