Effects of beta-alanine supplementation and interval training on physiological determinants of severe exercise performance.

INTRODUCTION: We aimed to manipulate physiological determinants of severe exercise performance. We hypothesized that (1) beta-alanine supplementation would increase intramuscular carnosine and buffering capacity and dampen acidosis during severe cycling, (2) that high-intensity interval training (HIT) would enhance aerobic energy contribution during severe cycling, and (3) that HIT preceded by beta-alanine supplementation would have greater benefits. METHODS: Sixteen active men performed incremental cycling tests and 90-s severe (110 % peak power) cycling tests at three time points: before and after oral supplementation with either beta-alanine or placebo, and after an 11-days HIT block (9 sessions, 4 × 4 min), which followed supplementation. Carnosine was assessed via MR spectroscopy. Energy contribution during 90-s severe cycling was estimated from the O2 deficit. Biopsies from m. vastus lateralis were taken before and after the test. RESULTS: Beta-alanine increased leg muscle carnosine (32 ± 13 %, d = 3.1). Buffering capacity and incremental cycling were unaffected, but during 90-s severe cycling, beta-alanine increased aerobic energy contribution (1.4 ± 1.3 %, d = 0.5), concurrent with reduced O2 deficit (-5.0 ± 5.0 %, d = 0.6) and muscle lactate accumulation (-23 ± 30 %, d = 0.9), while having no effect on pH. Beta-alanine also enhanced motivation and perceived state during the HIT block. There were no between-group differences in adaptations to the training block, namely increased buffering capacity (+7.9 ± 11.9 %, p = 0.04, d = 0.6, n = 14) and glycogen storage (+30 ± 47 %, p = 0.04, d = 0.5, n = 16). CONCLUSIONS: Beta-alanine did not affect buffering considerably, but has beneficial effects on severe exercise metabolism as well as psychological parameters during intense training phases.

Beta-alanine supplementation improves jumping power and affects severe-intensity performance in professional alpine skiers.

INTRODUCTION: Supplementation with beta-alanine may have positive effects on severe-intensity, intermittent, and isometric strength-endurance performance. These could be advantageous for competitive alpine skiers, whose races last 45 to 150 s, require metabolic power above the aerobic maximum, and involve isometric muscle work. Further, beta-alanine supplementation affects the muscle force-frequency relationship, which could influence explosiveness. We explored the effects of beta-alanine on explosive jump performance, severe exercise energy metabolism, and severe-intensity ski-like performance. METHODS: Nine male elite alpine skiers consumed 4.8 g/d beta-alanine or placebo for 5 weeks in a double-blind fashion. Before and after, they performed countermovement jumps (CMJ), a 90-s cycling bout at 110% VO2max (CLT), and a maximal 90-s box jump test (BJ90). RESULTS: Beta-alanine improved maximal (+7 ± 3%, d = 0.9) and mean CMJ power (+7 ± 2%, d = 0.7), tended to reduce oxygen deficit (-3 ± 8%, p = .06) and lactate accumulation (-12 ± 31%) and enhance aerobic energy contribution (+1.3 ± 2.9%, p = .07) in the CLT, and improved performance in the last third of BJ90 (+7 ± 4%, p = .02). These effects were not observed with placebo. CONCLUSIONS: Beta-alanine supplementation improved explosive and repeated jump performance in elite alpine skiers. Enhanced muscle contractility could possibly explain improved explosive and repeated jump performance. Increased aerobic energy production could possibly help explain repeated jump performance as well.

Enhanced interleukin-6 in human adipose tissue vein after sprint exercise: Results from a pilot study.

BACKGROUND: Low-volume sprint exercise is likely to reduce body fat. Interleukin (IL-6) may mediate this by increasing adipose tissue (AT) lipolysis. Therefore, the exchange of AT IL-6 and glycerol, a marker of lipolysis, was examined in 10 healthy subjects performing three 30-s all-out sprints. METHODS: Blood samples were obtained from brachial artery (a) and a superficial subcutaneous vein (v) on the anterior abdominal wall up to 9 min after the last sprint and analysed for IL-6 and glycerol. RESULTS: Arterial IL-6 increased 2-fold from rest to last sprint. AT venous IL-6 increased 15-fold from 0.4 ± 0.4 at rest to 7.0 ± 4 pg × mL-1 (p < 0.0001) and AT v-a difference increased 45-fold from 0.12 ± 0.3 to 6.0 ± 5 pg x mL-1 (p < 0.0001) 9 min after last sprint. Arterial glycerol increased 2.5-fold from rest to 9 min postsprint 1 (p < 0.0001) and was maintained during the exercise period. AT venous and v-a difference of glycerol increased 2-fold from rest to 9 min postsprint 1 (p < 0.0001 and p = 0.01, respectively), decreased until 18 min postsprint 2 (p < 0.001 and p < 0.0001), and then increased again until 9 min after last sprint (both p < 0.01). CONCLUSIONS: The concurrent increase in venous IL-6 and glycerol in AT after last sprint is consistent with an IL-6 induced lipolysis in AT. Glycerol data also indicated an initial increase in lipolysis after sprint 1 that was unrelated to IL-6. Increased IL-6 in adipose tissue may, therefore, complement other sprint exercise-induced lipolytic agents.

Decreased mitochondrial-related gene expression in adipose tissue after acute sprint exercise in humans: A pilot study.

The aim was to examine the acute effects of sprint exercise (SIT) on global gene expression in subcutaneous adipose tissue (AT) in healthy subjects, to enhance understanding of how SIT influences body weight regulation. The hypothesis was that SIT upregulates genes involved in mitochondrial function and fat metabolism. A total of 15 subjects performed three 30-s all-out sprints (SIT). Samples were collected from AT, skeletal muscle (SM) and blood (brachial artery and a subcutaneous AT vein) up to 15 min after the last sprint. Results showed that markers of oxidative stress, such as the purines hypoxanthine, xanthine and uric acid, increased markedly by SIT in both the artery and the AT vein. Purines also increased in AT and SM tissue. Differential gene expression analysis indicated a decrease in signaling for mitochondrial-related pathways, including oxidative phosphorylation, electron transport, ATP synthesis, and heat production by uncoupling proteins, as well as mitochondrial fatty acid beta oxidation. This downregulation of genes related to oxidative metabolism suggests an early-stage inhibition of the mitochondria, potentially as a protective mechanism against SIT-induced oxidative stress.

Long-term intermittent hyperoxic exposures do not enhance erythropoiesis.

BACKGROUND: Based on a report of a marked increase in the erythropoietin concentration ([EPO]) a few hours after the cessation of a single 2-h session of O(2) breathing, short periods of O(2) administration have been advocated as a therapy for anaemia. Accordingly, the purpose of the present study was to evaluate this theory by investigating the effect of 10 daily short-term exposures to normobaric O(2) over a 2-week period on the plasma [EPO] in healthy individuals. MATERIAL AND METHODS: Twenty men were assigned to either an experimental (NBO(2)) or to a control (AIR) group. The NBO(2) group breathed 100% normobaric O(2) for 2 h every weekday over a 2-week period. The AIR group breathed air within the same time protocol. Blood samples were collected at the pre-, mid- and post-intervention periods to determine [EPO]. RESULTS: [EPO] of the NBO(2) group was significantly lower than that of the AIR group during the mid- and post-periods (P < 0·001). [EPO] of the NBO(2) group showed a slight, albeit statistically nonsignificant, decrease during the mid (∼11%)- and post (∼16%)-periods. CONCLUSIONS: Daily short-term exposures to normobaric hyperoxia do not increase the [EPO] in healthy individuals. The increased O(2) tension suppresses [EPO]. Hence, administration of pure O(2) to enhance erythropoiesis is not warranted.

Acute short-term hyperoxia followed by mild hypoxia does not increase EPO production: resolving the "normobaric oxygen paradox".

Recent findings suggest that besides renal tissue hypoxia, relative decrements in tissue oxygenation, using a transition of the breathing mixture from hyperoxic to normoxic, can also stimulate erythropoietin (EPO) production. To further clarify the importance of the relative change in tissue oxygenation on plasma EPO concentration [EPO], we investigated the effect of a consecutive hyperoxic and hypoxic breathing intervention. Eighteen healthy male subjects were assigned to either IHH (N = 10) or CON (N = 8) group. The IHH group breathed pure oxygen (F(i)O(2) ~ 1.0) for 1 h, followed by a 1-h period of breathing a hypoxic gas mixture (F(i)O(2) ~ 0.15). The CON group breathed a normoxic gas mixture (F(i)O(2) ~ 0.21) for the same duration (2 h). Blood samples were taken just before, after 60 min, and immediately after the 2-h exposure period. Thereafter, samples were taken at 3, 5, 8, 24, 32, and 48 h after the exposure. During the breathing interventions, subjects remained in supine position. There were significant increases in absolute [EPO] within groups at 8 and 32 h in the CON and at 32 h only in the IHH group. No significant differences in absolute [EPO] were observed between groups following the intervention. Relative (∆[EPO]) levels were significantly lower in the IHH than in the CON group, 5 and 8 h following exposure. The tested protocol of consecutive hyperoxic-hypoxic gas mixture breathing did not induce [EPO] synthesis stimulation. Moreover, the transient attenuation in ∆[EPO] in the IHH group was most likely due to a hyperoxic suppression. Hence, our findings provide further evidence against the "normobaric O(2) paradox" theory.

Metabolic and morphological profile in skeletal muscle of healthy boys and girls.

It was hypothesized that the typical adult pattern of higher glycolytic capacity in skeletal muscle of males compared to females is not observed in children and that fiber cross-sectional area (CSA) is a determinant of glycolytic capacity in children. Biopsies were performed in vastus lateralis in 9-12 years-old healthy boys and girls (N = 27). Fiber types were classified by myofibrillar ATPase staining and CSA was measured using planimetry. Citrate synthase (CS) and lactate dehydrogenase (LD) were analyzed using fluorometric and spectrophotometric methods. There was no significant difference between boys and girls in CS activity (0.45 ± 0.1 µkat g-1 dry muscle in boys and 0.42 ± 0.1 in girls) or LD activity (24 ± 6 µkat g-1 dry muscle in boys and 25 ± 7 in girls). CSA did not differ between boys and girls. CS was inversely related to type I CSA (r = -0.62, p < 0.001) and LD was directly related to type IIA (r = 0.63, p < 0.001) and type IIB CSA (r = 0.72, p < 0.001). CSA was a significant determinant of CS and LD, even after adjusting for sex and relative fiber type area in multiple regression analysis. This suggests that the typical adult pattern of higher muscle glycolytic capacity in males than in females, as estimated by LD activity, was not observed in children. Sex-specific patterns in glycolytic capacity thus appear to develop during the transition from childhood to adulthood. In addition, fiber CSA was a strong determinant of both muscle glycolytic and oxidative capacity in children, regardless of sex.

Time to diagnosis in the National Registry of Veterans with Amyotrophic Lateral Sclerosis.

Our objective was to determine the interval from symptom onset to diagnosis, and to evaluate associated factors in a cohort of U.S. Veterans with motor neuron diseases. We retrospectively evaluated 1359 patients enrolled in the National Registry of Veterans with Amyotrophic Lateral Sclerosis (ALS). The main outcome measures were time from symptom onset to first diagnosis and to second opinion. Predictor variables included age at symptom onset, year of symptom onset, race, onset site, final diagnosis, number of diagnostic tests performed and clinical sites visited. Median time to first diagnosis was 11 months; median time to second opinion was two months. In a multivariable model, more recent calendar year of symptom onset, younger age, bulbar onset and a diagnosis of ALS versus non-ALS motor neuron disease were all significantly associated with a shorter time to first diagnosis. Later year of symptom onset and white race were significantly associated with a shorter time to second opinion. While the interval from symptom onset to diagnosis, and many of the associated factors are similar between our large cohort of U.S. Veterans with ALS and other smaller published cohorts, we found that the diagnostic interval among U.S. Veterans has significantly decreased over time.

Role of Pax genes in eye evolution: a cnidarian PaxB gene uniting Pax2 and Pax6 functions.

PaxB from Tripedalia cystophora, a cubomedusan jellyfish possessing complex eyes (ocelli), was characterized. PaxB, the only Pax gene found in this cnidarian, is expressed in the larva, retina, lens, and statocyst. PaxB contains a Pax2/5/8-type paired domain and octapeptide, but a Pax6 prd-type homeodomain. Pax2/5/8-like properties of PaxB include a DNA binding specificity of the paired domain, activation and inhibitory domains, and the ability to rescue spa(pol), a Drosophila Pax2 eye mutant. Like Pax6, PaxB activates jellyfish crystallin and Drosophila rhodopsin rh6 promoters and induces small ectopic eyes in Drosophila. Pax6 has been considered a "master" control gene for eye development. Our data suggest that the ancestor of jellyfish PaxB, a PaxB-like protein, was the primordial Pax protein in eye evolution and that Pax6-like genes evolved in triploblasts after separation from Cnidaria, raising the possibility that cnidarian and sophisticated triploblastic eyes arose independently.

Strength, power, fiber types, and mRNA expression in trained men and women with different ACTN3 R577X genotypes.

Alpha-actinins are structural proteins of the Z-line. Human skeletal muscle expresses two alpha-actinin isoforms, alpha-actinin-2 and alpha-actinin-3, encoded by their respective genes ACTN2 and ACTN3. ACTN2 is expressed in all muscle fiber types, while only type II fibers, and particularly the type IIb fibers, express ACTN3. ACTN3 (R577X) polymorphism results in loss of alpha-actinin-3 and has been suggested to influence skeletal muscle function. The X allele is less common in elite sprint and power athletes than in the general population and has been suggested to be detrimental for performance requiring high power. The present study investigated the association of ACTN3 genotype with muscle power during 30-s Wingate cycling in 120 moderately to well-trained men and women and with knee extensor strength and fatigability in a subset of 21 men performing isokinetic exercise. Muscle biopsies were obtained from the vastus lateralis muscle to determine fiber-type composition and ACTN2 and ACTN3 mRNA levels. Peak and mean power and the torque-velocity relationship and fatigability output showed no difference across ACTN3 genotypes. Thus this study suggests that R577X polymorphism in ACTN3 is not associated with differences in power output, fatigability, or force-velocity characteristics in moderately trained individuals. However, repeated exercise bouts prompted an increase in peak torque in RR but not in XX genotypes, suggesting that ACTN3 genotype may modulate responsiveness to training. Our data further suggest that alpha-actinins do not play a significant role in determining muscle fiber-type composition. Finally, we show that ACTN2 expression is affected by the content of alpha-actinin-3, which implies that alpha-actinin-2 may compensate for the lack of alpha-actinin-3 and hence counteract the phenotypic consequences of the deficiency.

Factors associated with survival in the National Registry of Veterans with ALS.

The clinical course of patients with ALS is highly variable. While the median survival time from symptom onset is 2-4 years, there are reports of survival ranging from less than a year to more than 40 years. Such variability makes planning difficult for patients and physicians, and complicates clinical trial design. We sought to validate previous predictors of survival and search for new ones using a large group of ALS patients in the National Registry of Veterans with ALS. We were especially interested in how various aspects of military service might affect survival. Subjects were those in the National Registry of Veterans with ALS who had probable or definite ALS (according to El Escorial criteria). A multivariable Cox proportional hazard regression model was used to examine variables for statistical association with ventilator-free survival time (determined from date of first diagnosis). Subjects who had not died or started ventilation by 31 October 2006 were censored. Our group of 1085 US military veterans with ALS was primarily male (98%) and white (94%), with mostly sporadic (95%) and extremity-onset (76%) ALS. Symptom onset occurred at a mean age of 59.3 years (60.6 years for diagnosis). Median survival time from symptom onset was 4.7 years (3.3 years from diagnosis). In our multivariable model, older age at diagnosis (HR 1.41 (95% CI 1.27-1.55) per 10-year increase), non-extremity site of onset (HR 1.55 (1.24-1.94)), and past deployment to Vietnam (HR 1.73 (1.36-2.19)) were all associated with shortened survival. A longer time to diagnosis was associated with better survival (HR 0.77 (0.70-0.84) per one year increase in diagnosis time). In this unique cohort of veterans with ALS, traditional factors of reduced survival remained important. In addition, past deployment to Vietnam was found to be associated with shortened survival as well. This finding could be due to a common exposure, a shared characteristic, an unmeasured confounder, or an enrollment bias. More research will be needed to understand the reasons behind this new finding.

Acute sprint exercise transcriptome in human skeletal muscle.

AIM: To examine global gene expression response to profound metabolic and hormonal stress induced by acute sprint exercise. METHODS: Healthy men and women (n = 14) performed three all-out cycle sprints interspersed by 20 min recovery. Muscle biopsies were obtained before the first, and 2h and 20 min after last sprint. Microarray analysis was performed to analyse acute gene expression response and repeated blood samples were obtained. RESULTS: In skeletal muscle, a set of immediate early genes, FOS, NR4A3, MAFF, EGR1, JUNB were markedly upregulated after sprint exercise. Gene ontology analysis from 879 differentially expressed genes revealed predicted activation of various upstream regulators and downstream biofunctions. Gene signatures predicted an enhanced turnover of skeletal muscle mass after sprint exercise and some novel induced genes such as WNT9A, FZD7 and KLHL40 were presented. A substantial increase in circulating free fatty acids (FFA) was noted after sprint exercise, in parallel with upregulation of PGC-1A and the downstream gene PERM1 and gene signatures predicting enhanced lipid turnover. Increase in growth hormone and insulin in blood were related to changes in gene expressions and both hormones were predicted as upstream regulators. CONCLUSION: This is the first study reporting global gene expression in skeletal muscle in response to acute sprint exercise and several novel findings are presented. First, in line with that muscle hypertrophy is not a typical finding after a period of sprint training, both hypertrophy and atrophy factors were regulated. Second, systemic FFA and hormonal and exposure might be involved in the sprint exercise-induced changes in gene expression.

Gene expression of the mouse corneal crystallin Aldh3a1: activation by Pax6, Oct1, and p300.

PURPOSE: Aldehyde dehydrogenase 3a1 (Aldh3a1) represents approximately 50% of the water-soluble protein of the mouse corneal epithelial cells and thus, by analogy with the abundant lens crystallins, is considered a corneal crystallin. This study was conducted to examine the developmental pattern and transcriptional activation of Aldh3a1 gene expression in the mouse cornea. METHODS: Aldh3a1 mRNA and protein were analyzed by quantitative (Q)-PCR and Western immunoblot analysis. Functional promoter analysis was examined by cotransfecting plasmids containing variable portions of the Aldh3a1 promoter fused to the luciferase reporter gene into COS-7 cells with selected transcription factors. Transcription factor binding sites were identified by electrophoretic mobility shift assays (EMSA) and chromatin immunoprecipitation assays (ChIP). In situ hybridization and immunohistochemistry were used to assess expression of Aldh3a1, Pax6, and Oct1 in the cornea. RESULTS: Aldh3a1 expression is temporally regulated in the cornea beginning at birth and increasing 100-fold by 6 weeks of age. Pax6, Oct1, and p300 synergistically activate the Aldh3a1 promoter approximately 116-fold. One Pax6 and two Oct1 binding sites were identified in vitro and in vivo in the Aldh3a1 promoter fragment analyzed. Pax6 and Oct1 are both present in the nuclei of corneal epithelial cells of the 6-week-old mouse. Finally, a reduction of Aldh3a1 correlated with reduced Pax6 in the corneas of heterozygous Small eye Pax6(+/-) mice. CONCLUSIONS: Pax6, Oct1, and p300 activate gene expression of the corneal crystallin Aldh3a1 in the mouse. These transcription factors are also implicated in the high expression of crystallin genes in the lens, consistent with the "refracton hypothesis" unifying many aspects of the lens and cornea.

Rofecoxib in patients with mild cognitive impairment: further analyses of data from a randomized, double-blind, trial.

A recent clinical trial in patients with Mild Cognitive Impairment (MCI) found an increased rate of possible or probable Alzheimer's disease (AD) diagnoses in patients assigned to rofecoxib compared to placebo. This unexpected finding was difficult to interpret due to methodological issues and a lack of confirmation on secondary endpoints, as well as a lack of confirmation in trials in related populations. We performed additional post hoc analyses to explore explanations for the finding based on possible neuropathological, cardiovascular/cerebrovascular, or cognitive effects of rofecoxib. 1) Neuropathological hypothesis: Of the 189 incident cases of possible or probable AD, 154 were probable AD. In probable AD patients, the treatment hazard ratio was reduced compared to the primary analysis -- a concordant finding would have strengthened a conclusion that rofecoxib accelerated the underlying neuropathology of AD. The treatment hazard ratio was increased in the remaining 35 patients with less certain diagnoses, but there was no single predominant reason for the reduced certainty of diagnosis. 2) Cardiovascular hypothesis: Neither cardiovascular risk status nor mean arterial blood pressure had an overall effect on AD diagnosis or modified the treatment difference. 3) Cognitive side-effects hypothesis: The percentages of patients with non-specific NSAID-type central nervous system adverse events were similar between the treatment groups. In summary, the present analyses are limited by their post hoc nature but provided little support for any of the possible explanations explored. The significance of the observation that rofecoxib increased the rate of conversion from MCI to AD remains uncertain.

Genes and Environmental Exposures in Veterans with Amyotrophic Lateral Sclerosis: the GENEVA study. Rationale, study design and demographic characteristics.

Recent reports of a potentially increased risk of amyotrophic lateral sclerosis (ALS) for veterans deployed to the 1990-1991 Persian Gulf War prompted the Department of Veterans Affairs to establish a National Registry of Veterans with ALS, charged with the goal of enrolling all US veterans with a neurologist-confirmed diagnosis of ALS. The Genes and Environmental Exposures in Veterans with ALS study (GENEVA) is a case-control study presently enrolling cases from the Department of Veterans Affairs registry and a representative sample of veteran controls to evaluate the joint contributions of genetic susceptibility and environmental exposures to the risk of sporadic ALS. The GENEVA study design, recruitment strategies, methods of collecting DNA samples and environmental risk factor information are described here, along with a summary of demographic characteristics of the participants (537 cases, 292 controls) enrolled to date.

Home-based chronic care. An expanded integrative model for home health professionals.

The Chronic Care Model (CCM) developed by is an influential and accepted guide for the care of patients with chronic disease. Wagner acknowledges a current healthcare focus on acute care needs that often circumvents chronic care coordination. He identifies the need for a "division of labor" to assist the primary care physician with this neglected function. This article posits that the role of chronic care coordination assistance and disease management fits within the purview of home healthcare and should be central to home health chronic care delivery. An expanded Home-Based Chronic Care Model (HBCCM) is described that builds on Wagner's model and integrates salient theories from fields beyond medicine. The expanded model maximizes the potential for disease self-management success and is intended to provide a foundation for home health's integral role in chronic disease management.

Are autonomous cities our urban future?

Cities are rapidly expanding in size, wealth and power, with some now larger than nation states. Smart city solutions and strong global urban networks are developing to manage massive urban growth. However, cities exist within a wider system and it may take more than technological advances, innovation and city autonomy to develop a sustainable urban future.

Sustainable urban systems: Co-design and framing for transformation.

Rapid urbanisation generates risks and opportunities for sustainable development. Urban policy and decision makers are challenged by the complexity of cities as social-ecological-technical systems. Consequently there is an increasing need for collaborative knowledge development that supports a whole-of-system view, and transformational change at multiple scales. Such holistic urban approaches are rare in practice. A co-design process involving researchers, practitioners and other stakeholders, has progressed such an approach in the Australian context, aiming to also contribute to international knowledge development and sharing. This process has generated three outputs: (1) a shared framework to support more systematic knowledge development and use, (2) identification of barriers that create a gap between stated urban goals and actual practice, and (3) identification of strategic focal areas to address this gap. Developing integrated strategies at broader urban scales is seen as the most pressing need. The knowledge framework adopts a systems perspective that incorporates the many urban trade-offs and synergies revealed by a systems view. Broader implications are drawn for policy and decision makers, for researchers and for a shared forward agenda.

AMP deaminase deficiency is associated with lower sprint cycling performance in healthy subjects.

AMP deaminase (AMPD) deficiency is an inherited disorder of skeletal muscle found in approximately 2% of the Caucasian population. Although most AMPD-deficient individuals are asymptomatic, a small subset has exercise-related cramping and pain without any other identifiable neuromuscular complications. This heterogeneity has raised doubts about the physiological significance of AMPD in skeletal muscle, despite evidence for disrupted adenine nucleotide catabolism during exercise in deficient individuals. Previous studies have evaluated the effect of AMPD deficiency on exercise performance with mixed results. This study was designed to circumvent the perceived limitations in previous reports by measuring exercise performance during a 30-s Wingate test in 139 healthy, physically active subjects of both sexes, with different AMPD1 genotypes, including 12 AMPD-deficient subjects. Three of the deficient subjects were compound heterozygotes characterized by the common c.34C>T mutation in one allele and a newly discovered AMPD1 mutation, c.404delT, in the other. While there was no significant difference in peak power across AMPD1 genotypes, statistical analysis revealed a faster power decrease in the AMPD-deficient group and a difference in mean power across the genotypes (P = 0.0035). This divergence was most striking at 15 s of the 30-s cycling. Assessed by the fatigue index, the decrease in power output at 15 s of exercise was significantly greater in the deficient group compared with the other genotypes (P = 0.0006). The approximate 10% lower mean power in healthy AMPD-deficient subjects during a 30-s Wingate cycling test reveals a functional role for the AMPD1 enzyme in sprint exercise.

Serial analysis of gene expression (SAGE) in the rat limbal and central corneal epithelium.

PURPOSE: To identify genes preferentially expressed in the stem-cell-rich limbal epithelium of the rat cornea. METHODS: The limbal and central corneal epithelial cells of 6-week-old rats were isolated by microdissection. Serial analysis of gene expression (SAGE) libraries were constructed and analyzed, and in situ hybridization, reverse transcription-polymerase chain reaction (RT-PCR) and cDNA cloning were conducted by conventional procedures. RESULTS: The rat limbal and central corneal epithelial SAGE libraries consisted of 41,894 and 40,691 tags, respectively. After annotation, this was reduced to 759 transcripts specific for the limbal library and 844 transcripts specific for the central corneal library; 2292 transcripts overlapped. Transcripts encoding proteins with metabolic functions comprised the major functional category in both libraries. In situ hybridization and/or RT-PCR results of 12 of the most abundant, highly enriched transcripts in the limbal epithelium were in general agreement with the SAGE data and showed that these proteins are also expressed in the conjunctival epithelium. Interesting limbal-enriched transcripts encode WDNM1-like protein (similar to WDNM1/Expi, a putative secreted proteinase and inhibitor of metastasis), mesothelin (a cancer marker), marapsin (a trypsin-like serine protease that may control cell growth and migration), K4 and K15 (both cytokeratins), and membrane-spanning four-domain subfamily A member 8B. WDNM1-like protein was cloned and confirmed as a member of the four-disulfide core family. CONCLUSIONS: The SAGE results extend the database of genes expressed in the rodent cornea and suggest an association between several genes preferentially expressed in the limbal epithelium with cellular proliferation and migration.