Treating cat allergy with monoclonal IgG antibodies that bind allergen and prevent IgE engagement

Acute allergic symptoms are caused by allergen-induced crosslinking of allergen-specific immunoglobulin E (IgE) bound to Fc-epsilon receptors on effector cells. Desensitization with allergen-specific immunotherapy (SIT) has been used for over a century, but the dominant protective mechanism remains unclear. One consistent observation is increased allergen-specific IgG, thought to competitively block allergen binding to IgE. Here we show that the blocking potency of the IgG response to Cat-SIT is heterogeneous. Next, using two potent, pre-selected allergen-blocking monoclonal IgG antibodies against the immunodominant cat allergen Fel d 1, we demonstrate that increasing the IgG/IgE ratio reduces the allergic response in mice and in cat-allergic patients: a single dose of blocking IgG reduces clinical symptoms in response to nasal provocation (ANCOVA, p = 0.0003), with a magnitude observed at day 8 similar to that reported with years of conventional SIT. This study suggests that simply augmenting the blocking IgG/IgE ratio may reverse allergy.

Shear-sensitive nanocapsule drug release for site-specific inhibition of occlusive thrombus formation

Essentials Vessel stenosis due to large thrombus formation increases local shear 1-2 orders of magnitude. High shear at stenotic sites was exploited to trigger eptifibatide release from nanocapsules. Local delivery of eptifibatide prevented vessel occlusion without increased tail bleeding times. Local nanocapsule delivery of eptifibatide may be safer than systemic antiplatelet therapies.

SUMMARY

Background Myocardial infarction and stroke remain the leading causes of mortality and morbidity. The major limitation of current antiplatelet therapy is that the effective concentrations are limited because of bleeding complications. Targeted delivery of antiplatelet drug to sites of thrombosis would overcome these limitations. Objectives Here, we have exploited a key biomechanical feature specific to thrombosis, i.e. significantly increased blood shear stress resulting from a reduction in the lumen of the vessel, to achieve site-directed delivery of the clinically used antiplatelet agent eptifibatide by using shear-sensitive phosphatidylcholine (PC)-based nanocapsules. Methods PC-based nanocapsules (2.8 × 1012 ) with high-dose encapsulated eptifibatide were introduced into microfluidic blood perfusion assays and into in vivo models of thrombosis and tail bleeding. Results Shear-triggered nanocapsule delivery of eptifibatide inhibited in vitro thrombus formation selectively under stenotic and high shear flow conditions above a shear rate of 1000 s-1 while leaving thrombus formation under physiologic shear rates unaffected. Thrombosis was effectively prevented in in vivo models of vessel wall damage. Importantly, mice infused with shear-sensitive antiplatelet nanocapsules did not show prolonged bleeding times. Conclusions Targeted delivery of eptifibatide by shear-sensitive nanocapsules offers site-specific antiplatelet potential, and may form a basis for developing more potent and safer antiplatelet drugs.

EphA2 promotes infiltrative invasion of glioma stem cells in vivo through cross-talk with Akt and regulates stem cell properties

Diffuse infiltrative invasion is a major cause for the dismal prognosis of glioblastoma (GBM), but the underlying mechanisms remain incompletely understood. Using human glioblastoma stem cells (GSCs) that recapitulate the invasive propensity of primary GBM, we find that EphA2 critically regulates GBM invasion in vivo. EphA2 was expressed in all seven GSC lines examined, and overexpression of EphA2 enhanced intracranial invasion. The effects required Akt-mediated phosphorylation of EphA2 on serine 897. In vitro the Akt-EphA2 signaling axis is maintained in the absence of ephrin-A ligands and is disrupted upon ligand stimulation. To test whether ephrin-As in tumor microenvironment can regulate GSC invasion, the newly established Efna1;Efna3;Efna4 triple knockout mice (TKO) were used in an ex vivo brain slice invasion assay. We observed significantly increased GSC invasion through the brain slices of TKO mice relative to wild type littermates. Mechanistically EphA2 knockdown suppressed stem properties of GSCs, causing diminished self-renewal, reduced stem marker expression and decreased tumorigenicity. In a subset of GSCs, the reduced stem properties were associated with lower Sox2 expression. Overexpression of EphA2 promoted stem properties in a kinase-independent manner and increased Sox2 expression. In addition to suppressing invasion, disrupting Akt-EphA2 crosstalk attenuated stem marker expression and neurosphere formation while having minimal effects on tumorigenesis, suggesting that the Akt-EphA2 signaling axis contributes to the stem properties. Taken together, the results show that EphA2 endows invasiveness of GSCs in vivo in cooperation with Akt and contributes to the maintenance of stem properties.

Insulin-like growth factor-II is produced by, signals to and is an important survival factor for the mature podocyte in man and mouse

Podocytes are crucial for preventing the passage of albumin into the urine and, when lost, are associated with the development of albuminuria, renal failure and cardiovascular disease. Podocytes have limited capacity to regenerate, therefore pro-survival mechanisms are critically important. Insulin-like growth factor-II (IGF-II) is a potent survival and growth factor; however, its major function is thought to be in prenatal development, when circulating levels are high. IGF-II has only previously been reported to continue to be expressed in discrete regions of the brain into adulthood in rodents, with systemic levels being undetectable. Using conditionally immortalized human and ex vivo adult mouse cells of the glomerulus, we demonstrated the podocyte to be the major glomerular source and target of IGF-II; it signals to this cell via the IGF-I receptor via the PI3 kinase and MAPK pathways. Functionally, a reduction in IGF signalling causes podocyte cell death in vitro and glomerular disease in vivo in an aged IGF-II transgenic mouse that produces approximately 60% of IGF-II due to a lack of the P2 promoter of this gene. Collectively, this work reveals the fundamental importance of IGF-II in the mature podocyte for glomerular health across mammalian species.

Predicting the lumbosacral joint centre location from palpable anatomical landmarks

The kinematics of the lumbar spine have previously been described by considering the bearing of the pelvis and lower back. However earlier studies have not described an intersegmental angle measured about a single point; which is necessary for investigation into movement, posture and balance, and lower back pain and injury. This study used computed tomography (CT) scans of 16 pelves to determine the location of palpable bony landmarks, and the junction of the fifth lumbar and first sacral vertebrae within a pelvis axis system. Data were used to derive equations which express the three-dimensional location of the lumbosacral joint centre as an offset from palpable surface landmarks. The magnitude of X, Y, Z offsets was controlled using individual pelvic geometry, and robustness and repeatability of the method was assessed. Regression equations provided the location of the lumbosacral junction to within 8.2mm (+/- 3.4mm) of its true coordinate. Leave-one-out analyses calculated equation coefficients using 15 of the original pelves, with the 16th acting as a control; average errors increased by 6.7 per cent (+/- 0.1 percent). To the authors' knowledge the current method is the most accurate non-invasive means of locating the lumbosacral junction and may be useful for constructing biomechanical models.

HDL therapy: two kinds of right?

Cardiovascular disease remains the leading cause of morbidity and mortality globally. The disease is largely controlled with interventions managing atherogenic lipids including LDL and triglycerides. However a number of studies have shown that increasing HDL levels is likely to provide better outcomes for patients suffering from this disease. There has been an extensive research effort into understanding how HDL levels are regulated in the body and which pathways can be targeted therapeutically. The HDL metabolic pathway is however overwhelmingly complex. This has provided only limited success in trialing drugs designed to raise HDL. To add to the complexity HDL itself is a heterogeneous population of particles and there is controversy surrounding which HDL particle is the most cardio-protective. In addition there is varying opinions on which of the HDL cellular receptors are more important in humans (as opposed to what has been discovered in mice) in regulating these effects. In this article we explore the evidence for and against using the currently suggested methods of raising HDL and provide some evidence for how the adverse effects of these drugs could be corrected.

Optimizing and validating an electromagnetic tracker in a human performance laboratory

Measurement errors have previously been observed using electromagnetic motion trackers in applied laboratories. The aims of this study were to optimize the layout of a human performance laboratory for assessing ergometer rowing technique, and to assess the precision and repeatability of measured rotations and trajectories using the Flock of Birds electromagnetic tracker. Four experiments investigated system performance over a large experimental volume: optimization of laboratory space, repeatability of laboratory layout, precision of measured rotations, and repeatability of measured displacements. Measurement accuracy was influenced by varying the global position of the system transmitter; results suggested a correlation with increasing distance between the electromagnetic source and equivalent sensors. Bringing the transmitter or sensors into closer proximity of metallic items may be another source of measurement error. An optimal location for the transmitter was identified, into which the transmitter was repositioned with good repeatability. Measurements were not negativelyaffected by the presence of a rowing ergometer in the experimental volume. Induced sensor rotations were reconstructed with high precision, and the system calculated small changes in sensor displacement with good repeatability. The system is a suitable technology for measuring the trajectory and rotation of moving body segments in applied human movement laboratories.

Validity of BMI as a measure of obesity in Australian white Caucasian and Australian Sri Lankan children

BACKGROUND

Body mass index (BMI) is used to diagnose obesity. However, its ability to predict the percentage fat mass (%FM) reliably is doubtful. Therefore validity of BMI as a diagnostic tool of obesity is questioned.

AIM

This study is focused on determining the ability of BMI-based cut-off values in diagnosing obesity among Australian children of white Caucasian and Sri Lankan origin.

SUBJECTS AND METHODS

Height and weight was measured and BMI (W/H2) calculated. Total body water was determined by deuterium dilution technique and fat free mass and hence fat mass derived using age- and gender-specific constants. A %FM of 30% for girls and 20% for boys was considered as the criterion cut-off level for obesity. BMI-based obesity cut-offs described by the International Obesity Task Force (IOTF), CDC/NCHS centile charts and BMI-Z were validated against the criterion method.

RESULTS

There were 96 white Caucasian and 42 Sri Lankan children. Of the white Caucasians, 19 (36%) girls and 29 (66%) boys, and of the Sri Lankans 7 (46%) girls and 16 (63%) boys, were obese based on %FM. The FM and BMI were closely associated in both Caucasians (r=0.81, P<0.001) and Sri Lankans (r=0.92, P<0.001). Percentage FM and BMI also had a lower but significant association. Obesity cut-off values recommended by IOTF failed to detect a single case of obesity in either group. However, NCHS and BMI-Z cut-offs detected cases of obesity with low sensitivity.

CONCLUSIONS

BMI is a poor indicator of percentage fat and the commonly used cut-off values were not sensitive enough to detect cases of childhood obesity in this study. In order to improve the diagnosis of obesity, either BMI cut-off values should be revised to increase the sensitivity or the possibility of using other indirect methods of estimating the %FM should be explored.

Hyperalgesia, synovitis and multiple biomarkers of inflammation are suppressed by interleukin 1 inhibition in a novel animal model of gouty arthritis

BACKGROUND

Monosodium urate (MSU) and calcium pyrophosphate dihydrate (CPPD) crystal-induced interleukin 1 beta (IL1beta) release contributes to inflammation in subcutaneous air pouch and peritoneal models of acute gout and pseudogout. However, consequences of IL1 inhibition have not been explored in more clinically relevant models of crystal-induced arthritis.

OBJECTIVE

To develop a novel mouse model of acute gouty ankle arthritis and use it to assess the effects of genetic deletion of IL1 receptor type (IL1R1) and of exogenous mIL1 Trap (a high-affinity blocker of mouse IL1alpha and IL1beta) on pain, synovitis and systemic inflammatory biomarkers.

METHODS

MSU crystals were injected into the mouse ankle joint and pain and ankle swelling were measured over 4 days. The effects of IL1 inhibition were determined in this model, and in the comparator models of crystal-induced peritonitis and subcutaneous air pouch inflammation.

RESULTS

Both IL1R1-null mice and mice pretreated with mIL1 Trap showed reduced neutrophil influx in MSU and CPPD crystal-induced peritonitis and air pouch models (p<0.05). In the ankle joint model, both IL1R1 knockout mice and pretreatment with mIL1 Trap were associated with significant reductions in MSU crystal-induced elevations in hyperalgesia, inflammation, serum amyloid A and the levels of multiple inflammatory cytokines and chemokines (p<0.05). Additionally, it was found that administration of mIL1 Trap after MSU crystal injection reduced established hyperalgesia and ankle swelling.

CONCLUSIONS

IL1 inhibition both prevented and relieved pain and ankle joint inflammation in response to intra-articular MSU crystals in mice. Results suggested that IL1 Trap has the potential to both prevent and treat gouty arthritis.

Association of VEGF polymorphisms with childhood asthma, lung function and airway responsiveness

Vascular endothelial growth factor (VEGF) is an angiogenic factor implicated in asthma severity. The objective of the present study was to determine whether VEGF single nucleotide polymorphisms (SNPs) are associated with asthma, lung function and airway responsiveness. The present authors analysed 10 SNPs in 458 white families in the Childhood Asthma Management Program (CAMP). Tests of association with asthma, lung function and airway responsiveness were performed using PBAT software (Golden Helix, Inc. Bozeman, MT, USA; available at www.goldenhelix.com). Family and population-based, revpeated measures analysis of airflow obstruction were conducted. Replication studies were performed in 412 asthmatic children and their parents from Costa Rica. Associations with asthma, lung function and airway responsiveness were observed in both cohorts. SNP rs833058 was associated with asthma in both cohorts. This SNP was also associated with increased airway responsiveness in both populations. An association of rs4711750 and its haplotype with forced expiratory volume in 1 s (FEV(1))/forced vital capacity (FVC) ratio in both cohorts was observed. Longitudinal analysis in CAMP confirmed an association of rs4711750 with FEV(1)/FVC decline over approximately 4.5 yrs of observation. VEGF polymorphisms are associated with childhood asthma, lung function and airway responsiveness in two populations, suggesting that VEGF polymorphisms influence asthma susceptibility, airflow obstruction and airways responsiveness.

Genetic background of IL-10(-/-) mice alters host-pathogen interactions with Campylobacter jejuni and influences disease phenotype

We hypothesized that particular genetic backgrounds enhance rates of colonization, increase severity of enteritis, and allow for extraintestinal spread when inbred IL-10(-/-) mice are infected with pathogenic C. jejuni. Campylobacter jejuni stably colonized C57BL/6 and NOD mice, while congenic strains lacking IL-10 developed typhlocolitis following colonization that mimicked human campylobacteriosis. However, IL-10 deficiency alone was not necessary for the presence of C. jejuni in extraintestinal sites. C3H/HeJ tlr4(-/-) mice that specifically express the Cdcs1 allele showed colonization and limited extraintestinal spread without enteritis implicating this interval in the clinical presentation of C. jejuni infection. Furthermore, when the IL-10 gene is inactivated as in C3Bir tlr4(-/-) IL-10(-/-) mice, enteritis and intensive extraintestinal spread were observed, suggesting that clinical presentations of C. jejuni infection are controlled by a complex interplay of factors. These data demonstrate that lack of IL-10 had a greater effect on C. jejuni induced colitis than other immune elements such as TLR4 (C3H/HeJ, C3Bir IL-10(-/-)), MHC H-2g7, diabetogenic genes, and CTLA-4 (NOD) and that host genetic background is in part responsible for disease phenotype. C3Bir IL-10(-/-) mice where Cdcs1 impairs gut barrier function provide a new murine model of C. jejuni and can serve as surrogates for immunocompromised patients with extraintestinal spread.

Heterogeneous expression of alpha-methylacyl-CoA racemase in prostatic cancer correlates with Gleason score

AIMS

Alpha-methylacyl-CoA racemase (AMACR) is a sensitive and specific immunohistochemical marker of prostatic malignancy, staining 80-100% of prostatic cancers with absent staining in benign glands. However, positive staining in benign conditions as well as low rates of AMACR reactivity in prostatic cancer variants have been described. Preliminary use of AMACR immunohistochemistry in our institution has suggested lower specificity and sensitivity for prostatic cancer than initially proposed. The aim of this study was to establish true rates of AMACR reactivity in prostatic cancer and benign prostatic hyperplasia (BPH).

METHODS AND RESULTS

AMACR immunohistochemistry was performed on sections from 57 prostatic cancers and 44 BPH resections. Ninety-one percent of cancers were AMACR+, with diffuse (> 75%) tumour staining in 53% of cases. Thirty-eight percent of tumours showed heterogeneous expression (1-75% tumour staining). This was significantly correlated with increased Gleason score. High-grade prostatic intraepithelial neoplasia (PIN) was AMACR+ in 87% of cancers. Eleven percent of BPH showed moderate or strong staining in benign glands, focally mimicking the malignant staining pattern.

CONCLUSIONS

This study confirms heterogeneous AMACR expression in prostatic cancer and shows a correlation with Gleason score. Positive staining in BPH is also documented, thus emphasizing the importance of interpreting AMACR immunohistochemistry in the context of other findings in a diagnostic setting.

Advanced glycation of apolipoprotein A-I impairs its anti-atherogenic properties

AIMS/HYPOTHESIS

AGE contribute to the pathogenesis of diabetic complications, including dyslipidaemia and atherosclerosis. However, the precise mechanisms remain to be established. In the present study, we examined whether AGE modification of apolipoprotein A-I (apoA-I) affects its functionality, thus altering its cardioprotective profile.

MATERIALS AND METHODS

The ability of AGE-modified apoA-I to facilitate cholesterol and phospholipid efflux, stabilise ATP-binding cassette transporter A1 (ABCA1) and inhibit expression of adhesion molecules in human macrophages and monocytes was studied.

RESULTS

The ability of AGE-modified apoA-I to promote cholesterol efflux from THP-1 macrophages, isolated human monocytes and from ABCA1-transfected HeLa cells was significantly reduced (>70%) compared with unmodified apoA-I. This effect was reversed by preventing AGE formation with aminoguanidine or reversing AGE modification using the cross-link breaker alagebrium chloride. AGE-modification of HDL also reduced its capacity to promote cholesterol efflux. AGE-apoA-I was also less effective than apoA-I in stabilising ABCA1 in THP-1 cells as well as in inhibiting expression of CD11b in human monocytes.

CONCLUSIONS/INTERPRETATION

AGE modification of apoA-I considerably impairs its cardioprotective, antiatherogenic properties, including the ability to promote cholesterol efflux, stabilise ABCA1 and inhibit the expression of adhesion molecules. These findings provide a rationale for targeting AGE in the management of diabetic dyslipidaemia.

C57BL/6 and congenic interleukin-10-deficient mice can serve as models of Campylobacter jejuni colonization and enteritis

Campylobacter jejuni is a globally distributed cause of human food-borne enteritis and has been linked to chronic joint and neurological diseases. We hypothesized that C. jejuni 11168 colonizes the gastrointestinal tract of both C57BL/6 mice and congenic C57BL/6 interleukin-10-deficient (IL-10(-/-)) mice and that C57BL/6 IL-10(-/-) mice experience C. jejuni 11168-mediated clinical signs and pathology. Individually housed mice were challenged orally with C. jejuni 11168, and the course of infection was monitored by clinical examination, bacterial culture, C. jejuni-specific PCR, gross pathology, histopathology, immunohistochemistry, and anti-C. jejuni-specific serology. Ceca of C. jejuni 11168-infected mice were colonized at high rates: ceca of 50/50 wild-type mice and 168/170 IL-10(-/-) mice were colonized. In a range from 2 to 35 days after infection with C. jejuni 11168, C57BL/6 IL-10(-/-) mice developed severe typhlocolitis best evaluated at the ileocecocolic junction. Rates of colonization and enteritis did not differ between male and female mice. A dose-response experiment showed that as little as 10(6) CFU produced significant disease and pathological lesions similar to responses seen in humans. Immunohistochemical staining demonstrated C. jejuni antigens within gastrointestinal tissues of infected mice. Significant anti-C. jejuni plasma immunoglobulin levels developed by day 28 after infection in both wild-type and IL-10-deficient animals; antibodies were predominantly T-helper-cell 1 (Th1)-associated subtypes. These results indicate that the colonization of the mouse gastrointestinal tract by C. jejuni 11168 is necessary but not sufficient for the development of enteritis and that C57BL/6 IL-10(-/-) mice can serve as models for the study of C. jejuni enteritis in humans.

Effects of creatine supplementation on aerobic power and cardiovascular structure and function

This project aimed to determine 1) whether creatine (Cr) supplementation affects cardiovascular structure and function and 2) to examine its effect on aerobic power. Eighteen males undertook aerobic testing on a cycle ergometer and echocardiographic assessment of the heart. The experimental group (N = 9) ingested 20g x day(-1) of Cr for seven days followed by l0g x day(-1) for a further 21 days. The control group (N = 9) followed an identical protocol ingesting a placebo for the same period. Assessment was performed pre-, mid- (seven days) and post-testing (28 days). A MANOVA with repeated measures was used to test for group differences before and after supplementation. The Cr group demonstrated a significant increase in body mass for the pre-mid (1.0 +/- 0.6 kg) and the pre-post (1.5 +/- 0.7 kg) testing occasions. Submaximal VO2 decreased significantly from the pre-mid and pre-post testing occasions by between 4.8% to 11.4% with Cr supplementation at workloads of 75 W and 150 W. Other oxygen consumption measures and exercise time to exhaustion, for the Cr group, showed decreasing trends that approached significance. Additionally, there was a significant pre-post decrease in maximum heart rate of 3.7%. There were no changes in any of the echocardiographic or blood pressure measures for either group. The present results suggest short term Cr supplementation has no detectable negative effect on cardiac structure or function. Additionally, Cr ingestion improves submaximal cycling efficiency. These results suggest that the increase in efficiency may be related to peripheral factors such an increase in muscle phosphocreatine, rather than central changes.

Generally applicable methods to purify intracellular coccidia from cell cultures and to quantify purification efficacy using quantitative PCR

The objective of this study was to evaluate the utility of a simple, efficient, and rapid method for the isolation of Sarcocystis neurona merozoites and Besnoitia darlingi tachyzoites from cultured cells. The efficacy of this purification method was assessed by microscopy, SDS-PAGE, Western blotting, immuno-fluorescence, and three novel quantitative PCR assays. Culture medium containing host cell debris and parasites was eluted through PD-10 desalting columns. This purification method was compared to alternatives employing filtration through a cellulose filter pad or filter paper. The estimated recovery of S. neurona merozoites purified by the column method was 82% (+/-3.7) of the original merozoites with 97.5% purity. In contrast, estimated recovery of S. neurona merozoites purified by filter pad and filter paper was 40% and 30% with 76% and 83% purity, respectively. The same procedures were applied to purify B. darlingi tachyzoites from cultured cells. Of the original cultured B. darlingi tachyzoites, 94% (+/-2.5) were recovered from the PD-10 column with 96.5%, purity whereas percentage recovery of B. darlingi tachyzoites purified by filter pad and filter paper were 51% and 35% with 84% and 88% purity, respectively. All described methods maintained sterility so that purified parasites could be subsequently cultured in vitro. However, purification using a PD-10 column minimized parasite loss and the loss of viability as determined by the trypan blue dye exclusion assay, the rate of parasite production, and plaque forming efficiency in cell culture. Moreover, column-purified parasites improved the sensitivity of an immuno-fluorescent (IFA) analysis and real-time quantitative PCR assays targeted to parasite 18S ribosomal DNA and hsp70 genes. This technique appears generally applicable for purifying coccidia grown in cell cultures.

Lessons learned from cervical pseudoarthrosis in ankylosing spondylitis

This case report illustrates three learning points about cervical fractures in ankylosing spondylitis, and it highlights the need to manage these patients with the neck initially stabilised in flexion. We describe a case of cervical pseudoarthrosis that is a rare occurrence after fracture of the cervical spine with ankylosing spondylitis. This went undetected until the development of myelopathic symptoms many months later. The neck was initially stabilised in flexion using tongs, and then slowly extended before anterior and posterior fixation was performed. The myelopathic symptoms resolved, and the patient had a good result at 18 months. We conclude that any increased movement of the spine after trauma in ankylosing spondylitis must be considered suspect and fully investigated.

Nutritional status and energy expenditure in children pre-bone-marrow-transplant

The aims of this study were to establish the nutritional status of children pre-BMT and to determine whether predictive methods of assessing nutritional status and resting energy expenditure (REE) are accurate in this population. We analysed the body cell mass (BCM) (n=26) and REE (n=24) in children undergoing BMT. BCM was adjusted for height (BCM/HT(p)) and expressed as a Z score to represent nutritional status. To determine whether body mass index (BMI) was indicative of nutritional status in children undergoing BMT, BMI Z scores were compared to the reference method of BCM/HT(p) Z scores. Schofield predictive equations of basal metabolic rate (BMR) were compared to measured REE to evaluate the accuracy of the predictive equations. The mean BCM/HT(p) Z score for the subject population was -1.09+/-1.28. There was no significant relationship between BCM/HT(p) Z score and BMI Z score (r=0.34; P>0.05); however there was minimal difference between measured REE and predicted BMR (bias=-11+/-149 kcal/day). The results of this study demonstrate that children undergoing BMT may have suboptimal nutritional status and that BMI is not an accurate indication of nutritional status in this population. However, Schofield equations were found to be suitable for representing REE in children pre-BMT.

Parasitemia in an immunocompetent horse experimentally challenged with Sarcocystis neurona sporocysts

Equine protozoal myeloencephalitis (EPM) is a serious neurological disease of horses in Americans. Most cases are attributed to infection of the central nervous system with Sarcocystis neurona. Parasitemia has not been demonstrated in immunocompetent horses, but has been documented in one immunocompromised foal. The objective of this study was to isolate viable S. neurona from the blood of immunocompetent horses. Horses used in this study received orally administered S. neurona sporocysts (strain SN 37-R) daily for 112 days at the following doses: 100/day for 28 days, followed by 500/day for 28 days, followed by 1000/day for 56 days. On day 98 of the study, six yearling colts were selected for attempted culture of S. neurona from blood, two testing positive, two testing suspect and two testing negative for antibodies against S. neurona on day 84 of the study. Two 10 ml tubes with EDTA were filled from each horse by jugular venipuncture and the plasma fraction rich in mononuclear cells was pipetted onto confluent equine dermal cell cultures. The cultures were monitored weekly for parasite growth for 12 weeks. Merozoites grown from cultures were harvested and tested using S. neurona-specific PCR with RFLP to confirm species identity. PCR products were sequenced and compared to known strains of S. neurona. After 38 days of in vitro incubation, one cell culture from a horse testing positive for antibodies against S. neurona was positive for parasite growth while the five remaining cultures remained negative for parasite growth for all 12 weeks. The Sarcocystis isolate recovered from cell culture was confirmed to be S. neurona by PCR with RFLP. Gene sequence analysis revealed that the isolate was identical to the challenge strain SN-37R and differed from two known strains UCD1 and MIH1. To our knowledge this is the first report of parasitemia with S. neurona in an immunocompetent horse.

The use of air displacement plethysmography in children and adolescents with cystic fibrosis

OBJECTIVES

The purpose of this paper was to evaluate the use of air displacement plethysmography (ADP) in children and adolescents with cystic fibrosis (CF). Specifically, the primary aim of this study was to compare estimates of fat-free mass (FFM) measured from ADP and dual energy X-ray absorptiometry (DEXA) in children and adolescents with CF. The secondary aim was to compare the effect of using predicted thoracic gas volume (VTG) and measured VTG for the calculation of FFM by ADP in this population.

METHODS

Cross-sectional FFM measurements were taken using ADP and DEXA in 52 children and adolescents with CF, ranging in age from 6.3 to 16.6 y.

RESULTS

Bland-Altman analysis showed that ADP values of FFM were on average 0.59 kg higher than DEXA values (95% limits of agreement = 3.61 to -2.43 kg); however this difference was not significant. There was no significant correlation (r = -0.26, P = 0.07) between the mean FFM and difference in FFM between ADP and DEXA. Using either predicted or measured VTG did not significantly affect FFM estimates in individuals with CF who had normal lung function (bias = -0.39 +/- 0.86 kg; r = -0.02, P = 0.93).

CONCLUSIONS

ADP is an appropriate technique for use in children and adolescents with CF.

Comparison of Sarcocystis neurona isolates derived from horse neural tissue

Sarcocystis neurona is a protozoan parasite that can cause neurological deficits in infected horses. The route of transmission is by fecal-oral transfer of sporocysts from opossums. However, the species identity and the lifecycle are not completely known. In this study, Sarcocystis merozoites from eight isolates obtained from Michigan horses were compared to S. neurona from a California horse (UCD1), Sarcocystis from a grackle (Cornell), and five Sarcocystis isolates from feral opossums from Michigan. Comparisons were made using several techniques. SDS-PAGE analysis with silver staining showed that Sarcocystis spp. from the eight horses appeared the same, but different from the grackle isolate. One Michigan horse isolate (MIH6) had two bands at 72 and 25kDa that were more prominent than the UCD1 isolate and other Michigan horse isolates. Western blot analysis showed that merozoites of eight of eight equine-derived isolates, and the UCD1 S. neurona isolate had similar bands when developed with serum or CSF of an infected horse. Major bands were seen at 60, 44, 30, and 16kDa. In the grackle (Cornell) isolate, bands were seen at 60, 44, 29, and 16kDa. DNA from merozoites of each of the eight equine-derived isolates and the grackle-derived isolate produced a 334bp PCR product (Tanhauser et al., 1999). Restriction fragment length polymorphism (RFLP) analysis of these horse isolates showed banding patterns characteristic for S. neurona. The grackle (Cornell) isolate had an RFLP banding pattern characteristic of other S. falcatula species. Finally, electron microscopy examining multiple merozoites of each of these eight horse isolates showed similar morphology, which differed from the grackle (Cornell) isolate. We conclude that the eight Michigan horse isolates are S. neurona species and the grackle isolate is an S. falcatula species.

The effects of pyrantel tartrate on Sarcocystis neurona merozoite viability

Sarcocystis neurona is the etiologic agent of equine protozoal myeloencephalitis, a neurologic disease of horses. The present study was designed to test the hypothesis that pyrantel tartrate can kill S. neurona merozoites growing in equine dermal cell culture. Sarcocystis neurona merozoites were exposed to a range of concentrations of pyrantel tartrate or sodium tartrate ranging from 0.001 to 0.01 M. Merozoites were then placed onto equine dermal cell cultures and incubated for 2 weeks to check for viability. At 1 and 2 weeks after inoculation, plaque counts were compared between treatments and, between treatments and controls. Merozoites exposed to concentrations of pyrantel tartrate higher than 0.0025 M (8.91 x 10(-4) g/ml) did not produce plaques in equine dermal cells, whereas those exposed to similar concentrations of the tartrate salt or medium alone produced significant numbers of plaques. These results demonstrate that pyrantel tartrate has activity against S. neurona merozoites in vitro and suggest that it may have activity against the sporozoite stage of the parasite found in the equine gut.

Prevalence of Dirofilaria immitis infection among shelter cats

OBJECTIVE

To determine prevalence of Dirofilaria immitis infection among shelter cats.

DESIGN

Cross-sectional study.

ANIMALS

239 cats euthanatized at an animal shelter in southeastern Michigan.

PROCEDURE

A gross necropsy focusing on the thoracic cavity, heart, lungs, and pulmonary vessels was performed within 5 hours after cats were euthanatized. Blood was collected directly from the heart of cats found to be infected and tested, using a filter test for microfilariae. Serum was tested for D immitis antigens by use of 2 antigen detection kits and for D immitis-specific antibodies by use of 2 antibody detection kits.

RESULTS

Cats ranged from approximately 4 months to 15 years old. Adult D immitis were found in 6 (2.5%) cats. Blood could not be recovered from 1 of the cats with heartworm infection. For the 5 other cats, results of the filter test were negative, and results of both antigen and both antibody tests were positive.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that cats living in an urban area in the northern part of the United States have a low prevalence of adult D immitis infection. However, this is likely to be an underestimate of the true prevalence of infection, because no attempts were made to identify cats infected with larval or juvenile stages of D immitis.

A G protein-coupled receptor for UDP-glucose

Uridine 5'-diphosphoglucose (UDP-glucose) has a well established biochemical role as a glycosyl donor in the enzymatic biosynthesis of carbohydrates. It is less well known that UDP-glucose may possess pharmacological activity, suggesting that a receptor for this molecule may exist. Here, we show that UDP-glucose, and some closely related molecules, potently activate the orphan G protein-coupled receptor KIAA0001 heterologously expressed in yeast or mammalian cells. Nucleotides known to activate P2Y receptors were inactive, indicating the distinctly novel pharmacology of this receptor. The receptor is expressed in a wide variety of human tissues, including many regions of the brain. These data suggest that some sugar-nucleotides may serve important physiological roles as extracellular signaling molecules in addition to their familiar role in intermediary metabolism.

Philosophy as a missing link between values and behavior

Despite the persistence of social scientists, evaluating the relationship between values and behavior has not yielded clear results. Here, a model is proposed to conceptualize and measure a person's operating philosophy. This assesses a different level of the value structure within personality from separate values or clusters of values; it is the evaluative structure within which a person's values exist. Building on major philosophies, such as utilitarianism or humanism, the model assumes that a person has a predominant Pragmatic, Intellectual, or Human Operating Philosophy. In a sample of 801 subjects, each of these operating philosophies had significant associations with a variety of the expected behaviors evident in work and graduate school, such as initiative and empathy, as well as learning styles, skills, and flexibility. Interpretation of the results is offered as a way to understand the relationship between people's values or beliefs and their behavior and approach to learning.

Improvement of western blot test specificity for detecting equine serum antibodies to Sarcocystis neurona

Equine protozoal myeloencephalitis (EPM) is a neurological disease of horses and ponies caused by the apicomplexan protozoan parasite Sarcocystis neurona. The purposes of this study were to develop the most stringent criteria possible for a positive test result, to estimate the sensitivity and specificity of the EPM Western blot antibody test, and to assess the ability of bovine antibodies to Sarcocystis cruzi to act as a blocking agent to minimize false-positive results in the western blot test for S. neurona. Sarcocystis neurona merozoites harvested from equine dermal cell culture were heat denatured, and the proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in a 12-20% linear gradient gel. Separated proteins were electrophoretically transferred to polyvinylidene fluoride membranes and blocked in 1% bovine serum albumin and 0.5% Tween-Tris-buffered saline. Serum samples from 6 horses with S. neurona infections (confirmed by culture from neural tissue) and 57 horses without infections (horses from the Eastern Hemisphere, where S. neurona does not exist) were tested by Western blot. Horses from both groups had reactivity to the 62-, 30-, 16-, 13-, 11-, 10.5-, and 10-kD bands. Testing was repeated with another step. Blots were treated with bovine S. cruzi antibodies prior to loading the equine samples. After this modification of the Western blot test, positive infection status was significantly associated with reactivity to the 30- and 16-kD bands (P<0.001, Fisher's exact test). The S. cruzi antibody-blocked Western blot had a sample sensitivity of 100% and sample specificity of 98%. It is concluded that the specificity of the Western blot test is improved by blocking proteins not specific to S. neurona and using reactivity to the 30- and 16-kD bands as the criterion for a positive test.

Simplified technique for isolation, excystation, and culture of Sarcocystis species from opossums

Sarcocystis neurona is a protozoan parasite that causes a neurological disease in horses called equine protozoal myeloencephalitis. The route of transmission is speculated to be by fecal-oral transfer of sporocysts shed from opossums. Controversy exists regarding both the natural life cycle for this parasite as well as the species identity of opossum Sarcocystis. To provide stage-specific material for species comparison, 27 opossums from southern Michigan were screened for Sarcocystis spp. sporocysts. Seven opossums were positive for Sarcocystis sporocysts by fecal flotation. A simplified, effective technique for isolation, excystation, and culture of opossum Sarcocystis sp. from mucosal scrapings was developed. All 7 Sarcocystis sp. isolates were successfully cultured to grow long term in equine dermal cells to the merozoite stage. Merozoites were observed between 5 and 15 days after inoculation. In conclusion, opossums shed Sarcocystis sp. sporocysts that may be manipulated to excyst and grow in vitro in equine dermal cell lines to the merozoite stage using the simplified technique described.

Identification of surrogate agonists for the human FPRL-1 receptor by autocrine selection in yeast

We describe a procedure for isolating agonists for mammalian G protein-coupled receptors of unknown function. Human formyl peptide receptor like-1 (FPRL-1) receptor, originally identified as an orphan G protein-coupled receptor related to the formyl peptide receptor (FPR1), was expressed in Saccharomyces cells designed to couple receptor activation to histidine prototrophy. Selection for histidine prototrophs among transformants obtained with a plasmid-based library encoding random peptides identified six different agonists, each of whose production yielded autocrine stimulation of the receptor expressed in yeast. A synthetic version of each peptide promoted activation of FPRL-1 expressed in human embryonic kidney (HEK293) cells, and five of the peptides exhibited significant selectivity for activation of FPRL-1 relative to FPR1. One selective peptide was tested and found to mobilize calcium in isolated human neutrophils. This demonstrates that stimulation of FPRL-1 results in neutrophil activation and suggests that the receptor functions as a component of the inflammatory response. This autocrine selection protocol may be a generally applicable method for providing pharmacological tools to evaluate the physiological roles of the growing number of mammalian orphan G protein-coupled receptors.

Geographic distribution of ticks (Acari: Ixodidae) in Michigan, with emphasis on Ixodes scapularis and Borrelia burgdorferi

A 12-yr (1985-1996) passive survey in Michigan based upon tick submissions from citizens yielded 4,755 ticks of 21 species, 16 of which were probably indigenous in the state. Three species of Dermacentor [most common, D. variabilis Say and D. albipictus (Packard)]; 2 species of Amblyomma [most common, A. americanum (L.)]; and 12 species of Ixodes (most common, I. cookei Packard and I. scapularis Say), as well as Haemaphysalis leporispalustris (Packard), Rhipicephalus sanguineus Latreille, and the soft ticks Ornithodoros kelleyi Cooley & Kohls, and Otobius megnini (Duges) were submitted. New state records were I. kingi Bishopp, I. texanus Banks, I. sculptus Neumann, and I. baergi Cooley & Kohls. Examination of gut smears from dissections of 1,037 ticks of 13 species by indirect immunofluorescent assay, using murine monoclonal H9724 as the primary antibody, revealed that 11 of 175 I. scapularis were infected with Borrelia spp. All positive I. scapularis were from Menominee County in the upper peninsula of the state, which also provided 79.8% of all submitted I. scapularis. Surveys for ticks on 5,449 hunter-killed white-tailed deer were conducted from 1988 to 1990, encompassed deer taken from 65 of the state's 83 counties, and showed that although D. albipictus was distributed widely in the northern part of the state, I. scapularis occurred only on deer taken from southern townships of Menominee County. Of 1,218 canine sera tested for antibodies to B. burgdorferi in 1992 and 1993, 25 of 299 (8.0%) from Menominee County were positive but only 1 of 919 sera submitted from 5 counties in the lower peninsula was positive.

The ability of tests of muscular function to reflect training-induced changes in performance

We examined the ability of isokinetic and isoinertial tests of muscular function to track training-induced changes in performance. Subjects completed the following tests before and after training: (1) two isoinertial tests using concentric and eccentric actions; (2) isokinetic knee extension at two velocities; and (3) a one-repetition maximum squat. Further, a 40 m sprint and 6 s cycle test were conducted as measures of athletic performance. The subjects were split into a weights group, which performed heavy squats, and a control group. The results showed that training significantly enhanced sprint time by 2.2%, and the improvement in cycle performance (9%) approached significance (P = 0.09). However, apart from the squat, no measure of muscular function significantly changed because of training. Furthermore, there was no relationship between the training-induced changes in performance and the training-induced changes in the isokinetic and isoinertial tests. The results suggest that tests of muscular function cannot be used to monitor training-induced changes in performance. We considered this to be due to the large degree of variance unaccounted for in the relationship between the scores on tests of muscle function and performance. Therefore, the effectiveness of training should be based on changes in performance rather than changes in test scores of muscle function.

Influence of load and stretch shortening cycle on the kinematics, kinetics and muscle activation that occurs during explosive upper-body movements

Although explosive power in lower-body movements has been extensively studied, there is a paucity of research examining such movements in the upper body. This study aimed to investigate the influence of load and the stretch shortening cycle (SSC) on the kinematics, kinetics, and muscle activation that occurs during maximal effort throws. A total of 17 male subjects performed SSC and concentric only (CO) bench throws using loads of 15%, 30%, 45%, 60%, 75%, 90% and 100% of their previously determined one repetition maximum bench press. The displacement, velocity, acceleration, force and power output as well as the electromyogram (EMG) from pectoralis major, anterior deltoid, and triceps brachii were recorded for each throw. The results were compared using multivariate analysis of variance with repeated measures. A criterion alpha level of P < or = 0.05 was used. Similar force velocity power relationships were determined for this multijoint upper-body movement as has been found for isolated muscles, single joint movements, and vertical jumping. The highest power output was produced at the 30% [563 (104) W] and 45% [560 (86) W] loads during the SSC throws. Force output increased as a function of load; however, even the lighter loads resulted in considerable force due to the high accelerations produced. Average velocity, average and peak force, and average and peak power output were significantly higher for the SSC throws compared to the CO throws. However, peak velocity and height thrown were not potentiated by performing the pre-stretch because the duration and range of movement allowed the ability of the muscle to generate force at high shortening velocities to dominate the resulting throw. As such, explosive movements involving longer concentric actions than experienced during brief SSC movements may be limited by the ability of the muscle to produce force during fast contraction velocities.

Stretch shorten cycle performance: detrimental effects of not equating the natural and movement frequencies

This study aimed to assess whether the benefits associated with stretch shorten cycle (SSC) movements required the movement frequency to be in resonance with the natural frequency of the elastic structures. Seventeen untrained participants performed SSC and concentric bench press throws. Further, quasi-static muscular actions were also performed in which a brief perturbation was applied to the bar with the resulting damped oscillations providing natural frequency data. It was observed that prior stretch did not facilitate concentric performance. Further, there were large significant differences between the natural frequency of the musculo-tendinous system and the frequency of the SSC movements. The authors hypothesize that the failure to achieve resonance contributed to the poor performance achieved in the SSC actions.

The assessment of human dynamic muscular function: a comparison of isoinertial and isokinetic tests

This investigation compared the relationship of isokinetic and isoinertial tests of muscular function to dynamic upper body performances. The electromiyographic activity of each of the tests of muscular function, as recorded by surface electrodes, were examined to determine whether neural differences underlie the ability of the test to relate to performance. Twenty four subjects performed isokinetic and isoinertial tests of muscular function in a bench press movement. The isokinetic tests were performed at velocities of 60, 90 and 120 deg/s while the isoinertial tests were performed at loads of 30%, 60% and 130% of the one repetition maximum. Subjects also performed the following tests of dynamic performance: a maximum one repetition bench press (1 RM), a seated shotput throw and two drop bench press throws from a height of 0.25 m at various loads. Forces/torques, displacement and electromyographic data were recorded from the isoinertial and isokinetic tests. Both the isoinertial and isokinetic parameters were related to the various measures of upper body performance (r = 0.33-0.94), however, neither was superior at predicting performance. Further, the relationship between the tests of muscular function were consistently high (r = 0.75-0.88). This was the case, even though the magnitude of the EMG signals were significantly higher in the isoinertial, as compared to the isokinetic tests. It is postulated that structural considerations, such as a specific testing position, rather than neural factors, underlie the observed results. These results support previous research which has reported the existence of a generality of strength across dynamic testing modalities.

Weight and plyometric training: effects on eccentric and concentric force production

The study was performed in an effort to gain greater insights into the adaptations invoked by plyometric and weight training. Forty-one previously trained males were randomly allocated in either a control, plyometric, or weight-training group. The experimental groups trained for 8 weeks, performing either heavy lifts or dynamic plyometric exercises. The following test items were performed prior to and at the completion of the training period: (a) vertical jump, (b) a series of isoinertial concentric and eccentric tests, (c) push-up tests, and (d) maximal bench press and squat lifts. Plyometric training significantly enhanced the rate of eccentric lower body force production. The weight-training group primarily enhanced concentric function. These results were attributed to the specific stresses imposed by the differing forms of training and are discussed with reference to methods of enhancing training induced adaptations and the types of movements such training would tend to facilitate.

The use of isometric tests of muscular function in athletic assessment

Isometric assessment of muscular function is a popular form of testing which has been used in exercise science for over 40 years. It typically involves a maximal voluntary contraction performed at a specified joint angle against an unyielding resistance which is in series with a strain gauge, cable tensiometer, force platform or similar device whose transducer measures the applied force. Often both the maximum force and the rate of force development are recorded. These tests have generally shown high reliability in both single and multi-joint test protocols, although the maximum force is typically more reliable than rate of force development. This review outlines the reliability of isometric assessment and discusses a number of methodological considerations designed to enhance reliability and validity, including standardisation procedures, type of instructions, muscular pre-tension, testing position and joint angle. Currently, there appears to be considerable controversy as to the external validity of isometric assessment, particularly the ability of the tests to monitor changes in dynamic performance and their relationship to such performances. Indeed, a number of studies have recently shown that dynamic assessment modalities (isokinetic and isoinertial) are superior in terms of their relationship to dynamic performance and ability to discriminate between athletes of various performance levels compared with isometric assessment. This article reviews the use of isometric assessment in exercise science and consequently outlines a number of neural, mechanical and methodological factors which may have contributed to the contrasting research, and which may limit the ability of isometric assessment to relate to dynamic movement. Because of the large neural and mechanical differences between isometric and dynamic muscular actions, athletic assessment, which is dynamic in its nature, is generally most appropriately accomplished using dynamic muscular assessment methods, and in most instances isometric testing should be avoided.

The specificity of strength training: the effect of posture

There is a paucity of research into the importance of performing strength training exercises in postures specific to the movements they are attempting to facilitate. In addressing this question, 27 previously trained subjects were randomly allocated into heavy weight training and control groups. The weight training group performed 4-6 sets of 6-10 repetitions of the squat and bench press lifts twice a week for 8 weeks. Prior to and after the training period the following tests were conducted: bench press throw at 30% of maximal load, vertical jump, maximal squat and bench press lifts, push-up test performed over a force platform, 40-m sprint, 6-s cycle, and isokinetic tests assessing upper and lower body musculature in varying actions. The results supported the concept that posture is important in training as those exercises conducted in similar postures to the training recorded the greatest improvement in performance. For example, after completion of the training the weight training subjects significantly increased by approximately 12% the maximal load lifted in the bench press exercise and the peak torque in the isokinetic bench press test. However, performance in the isokinetic horizontal arm adduction test was not significantly changed. We speculate that the phenomenon of posture specificity may, at least in part, be caused by the differing postures altering the neural input to the musculature. The results stress the importance of selecting exercises in which the posture closely resembles that of the movements they are attempting to facilitate.

Poor correlations between isometric tests and dynamic performance: relationship to muscle activation

The purpose of this research was to perform isometric tests at two joint angles and examine their relationship to dynamic performance. In addition, electromyograph data were collected from the triceps brachii and pectoralis major muscles to compare underlying neural characteristics between the isometric tests and dynamic movement. A group of 24 healthy male subjects performed two isometric tests in a bench press position, at elbow angles of 90 and 120 degrees. From these data, the maximal force and rate of force development were determined. In addition, each subject performed a seated medicine ball throw as a measure of dynamic upper body performance. Correlations showed that isometric measurements of force (r = 0.47-0.55) and rate of force development (r = 0.08-0.31) were poor predictors of dynamic performance. The angle of isometric assessment had little effect on the relationship between the tests and measurements of performance. The myo-electric data was processed in terms of the integrated electromyogram and the Fourier transformed frequency spectrum. These data demonstrated differences in the neural activation patterns of the musculature, between the isometric 90 degrees test and the medicine ball throw. The poor relationship between isometric tests and medicine ball performance was consequently, at least partially, attributed to differing motor unit activation patterns between isometric and dynamic movement. The results of this research strongly suggest that isometric tests have limited value when assessing dynamic upper body performance.

The validity and reliability of a test of lower body musculotendinous stiffness

The aim of this study was to investigate the validity and reliability of an in vivo test of lower body musculotendinous stiffness. Male subjects (n = 23) with at least 12 months of weight training experience performed a series of quasi-static muscular actions in a supine leg press position during which a brief perturbation was applied. The resulting damped oscillations enabled each subject's maximal musculotendinous stiffness for the lower body musculature to be estimated. To assess the individual's capacity to benefit from active stretch, subjects also performed both a static jump and a countermovement jump. Statistical analysis revealed no significant different between day 1 and day 2 stiffness values (P < 0.01), an interday reliability of r = 0.94 and a coefficient of variance of 8%. It was further demonstrated that maximal stiffness was significantly correlated to both isometric and concentric rate of force development (r = 0.50 and r = 0.54, respectively), and inversely related to the percentage difference between vertical jumps with and without prior stretch (r = -0.54). Such results tend to suggest that the test is valid and are discussed with reference to the restitution of elastic strain energy, muscle potentiation and the interaction effects of elastic recoil on dynamic muscular function. It was concluded that the assessment of stiffness of the lower body using the oscillation technique is a valid and reliable in vivo measure of musculotendinous stiffness.

Strength diagnosis: the use of test data to determine specific strength training

The aim of this study was to determine if pre-training strength and power tests could provide data that effectively discriminated between subjects whose cycling performance improved considerably from training, from those who did not. Twenty active healthy male subjects performed 10 weeks of plyometric or weight training. Prior to and at the completion of the training, the following tests were performed: (1) a 6-s cycle ride; (2) isokinetic leg extension at 1.05 and 5.24 rads s-1; and (3) a maximum isometric squat. The subjects in the two training groups were separated into those whose cycling performance improved significantly as a result of the training (good) and those who did not (poor). The pre-training muscular function tests of the good versus poor achievers were then compared, individually for each form of training, to determine if they could be used to discriminate between the two subject groups. The pre-training isometric data effectively discriminated between those individuals who improved their cycling performance significantly as a consequence of training and those who did not. While this finding has practical implications for the exercise science field, further research is required before generally useful normative data can be used with confidence to prescribe individual specific training programmes.

Musculotendinous stiffness: its relationship to eccentric, isometric, and concentric performance

The purpose of this study was to quantify the relationship between musculotendinous stiffness and performance in eccentric, isometric, and concentric activities. Thirteen trained subjects performed a series of maximal effort eccentric, concentric, and isometric muscular contractions in a bench press-type movement. Additionally, subjects performed a series of quasi-static muscular contractions in a bench press movement. A brief perturbation was applied to the bar while these isometric efforts were maintained, and the resulting damped oscillations provided data pertaining to each subject's musculotendinous stiffness. Musculotendinous stiffness was significantly related to isometric and concentric performance (r = 0.57-0.78) but not to eccentric performance. These results are interpreted as demonstrating that the optimal musculotendinous stiffness for maximum concentric and isometric activities was toward the stiff end of the elasticity continuum. A stiffer musculotendinous unit may facilitate such performances by improving the force production capabilities of the contractile component, due to a combination of improved length and rate of shortening, and additionally by enhancing initial force transmission.