Richard A. Dennis

Exercise-induced gene expression in soleus muscle is dependent on time after spinal cord injury in rats.

Cycling exercise attenuates atrophy in hindlimb muscles and causes changes in spinal cord properties after spinal cord injury in rats. We hypothesized that exercising soleus muscle expresses genes that are potentially beneficial to the injured spinal cord. Rats underwent spinal cord injury at T10 and were exercised on a motor‐driven bicycle. Soleus muscle and lumbar spinal cord tissue were used for messenger RNA (mRNA) analysis. Gene expression of brain‐derived neurotrophic factor (BDNF) and glial cell line‐derived neurotrophic factor (GDNF) was elevated 11‐ and 14‐fold, respectively, in soleus muscle after one bout of exercise performed 5 days after spinal cord transection. Also, c‐fos and heat shock protein‐27 (HSP27) mRNA abundance were increased 11‐ and 7‐fold, respectively. When exercise was started 2 days after the injury, the changes in gene expression were not observed. By contrast, at 2 but not at 5 days after transection, expression of the HSP27 gene was elevated sixfold in the lumbar spinal cord, independent of exercise. Electromyographic activity in soleus muscles was also decreased at 2 days, indicating that the spinal cord was less permissive to exercise at this early time. Long‐term exercise for 4 weeks attenuated muscle atrophy equally well in rats started at 2 days or 5 days after injury. We conclude that BDNF and GDNF released from exercising muscle may be involved in exercise‐induced plasticity of the spinal cord. Furthermore, the data suggest that the lumbar spinal cord undergoes time‐dependent changes that temporarily impede the ability of the muscle to respond to exercise. Muscle Nerve 29: 73–81, 2004

Aging alters macrophage properties in human skeletal muscle both at rest and in response to acute resistance exercise

Macrophages are involved in skeletal muscle repair through pro-inflammatory and alternative functions. We tested the hypothesis that aging alters the abundance and properties of skeletal muscle macrophages that will influence their functional response to acute resistance exercise. Total macrophages (CD 68+), as well as pro- (CD 11b+) and anti-inflammatory (CD 163+) subpopulations and associated cytokine mRNAs were quantified in vastus lateralis biopsies from young (N=17) and elderly (N=17) males pre- and 72 h post-exercise. Pre-exercise, young muscle tended to possess a greater number of macrophages, whereas elderly muscle possessed higher levels of IL-1 beta (P=0.001), IL-1 RA (P=0.003), and IL-10 (P=0.028). Post-exercise, total macrophages did not change in either group, however, the number of CD 11b+ (P=0.039) and CD 163+ (P=0.026) cells increased 55 and 29%, respectively, but only in the young. IL-1 beta (P=0.006), IL-10 (P=0.016), and AMAC-1 (P=0.044) also increased, approximately two-fold, and again only in the young. Quantitation of CD 11b+ and CD 163+ cells suggests that the majority of resident macrophages possess alternative functions, and a small subpopulation participates in the inflammatory response. Both subpopulations increased their activity post-exercise, exclusively in the young. These findings suggest that aging results in a defective regulation of muscle macrophage function, both at baseline and in response to resistance exercise, that may limit muscle hypertrophy in older adults.

Wii-Fit for Improving Gait and Balance in an Assisted Living Facility: A Pilot Study

Objectives. To determine the effects on balance and gait of a Wii-Fit program compared to a walking program in subjects with mild Alzheimers dementia (AD). Methods. A prospective randomized (1 : 1) pilot study with two intervention arms was conducted in an assisted living facility with twenty-two mild AD subjects. In both groups the intervention occurred under supervision for 30 minutes daily, five times a week for eight weeks. Repeated measures ANOVA and paired t-tests were used to analyze changes. Results. Both groups showed improvement in Berg Balance Scale (BBS), Tinetti Test (TT) and Timed Up and Go (TUG) over 8 weeks. However, there was no statistically significant difference between the groups over time. Intragroup analysis in the Wii-Fit group showed significant improvement on BBS (P = 0.003), and TT (P = 0.013). The walking group showed a trend towards improvement on BBS (P = 0.06) and TUG (P = 0.07) and significant improvement in TT (P = 0.06). Conclusion. This pilot study demonstrates the safety and efficacy of Wii-Fit in an assisted living facility in subjects with mild AD. Use of Wii-Fit resulted in significant improvements in balance and gait comparable to those in the robust monitored walking program. These results need to be confirmed in a larger, methodologically sound study.

Interleukin-1 polymorphisms are associated with the inflammatory response in human muscle to acute resistance exercise.

Inflammation appears to play an important role in the repair and regeneration of skeletal muscle after damage. We tested the hypothesis that the severity of the inflammatory response in muscle after an acute bout of resistance exercise is associated with single nucleotide polymorphisms (SNPs) previously shown to alter interleukin‐1 (IL‐1) activity. Using a double‐blind prospective design, sedentary young men were screened (n= 100) for enrolment (n= 24) based upon having 1 of 4 haplotype patterns composed of five polymorphic sites in the IL‐1 gene cluster: IL‐1A (+4845), IL‐1B (+3954), IL‐1B (−511), IL‐1B (−3737) and IL‐1RN (+2018). Subjects performed a standard bout of resistance leg exercise and vastus lateralis biopsies were obtained pre‐, and at 24, and 72 h post‐exercise. Inflammatory marker mRNAs (IL‐1β, IL‐6 and tumor necrosis factor‐α (TNF‐α)) and the number of CD68+ macrophages were quantified. Considerable variation was observed in the expression of these gene products between subjects. At 72 h post‐exercise, IL‐1β had increased in a number of subjects (n= 10) and decreased (n= 4) or did not change (n= 10) in others. Inflammatory responses were significantly associated with specific haplotype patterns and were also influenced by individual SNPs. Subjects with genotypes 1.1 at IL‐1B (+3954) or 2.2 at IL‐1B (−3737) had approximately a 2‐fold higher median induction of several markers, but no increase in macrophages, suggesting that cytokine gene expression is elevated per macrophage. The IL‐1RN (+2018) SNP maximized the response specifically within these groups and was associated with increased macrophage recruitment. This is the first report that IL‐1 genotype is associated with the inflammation of skeletal muscle following acute resistance exercise that may potentially affect the adaptations to chronic resistance exercise.

Titin and nebulin content in human skeletal muscle following eccentric resistance exercise.

We measured titin and nebulin content in muscle biopsies from the vastus lateralis before and 24 h after one bout of high‐intensity eccentric knee extensor resistance exercise in seven men (26 ± 3 years). Titin and nebulin content were significantly (P < 0.05) reduced after exercise by 30 and 15%, respectively. These results suggest that the structural components of the myofibrillar apparatus are degraded following high‐intensity eccentric resistance exercise in humans. Loss of these proteins may have important implications for the mechanisms regulating the adaptive response of skeletal muscle to resistance exercise.

Muscle expression of genes associated with inflammation, growth, and remodeling is strongly correlated in older adults with resistance training outcomes

A group (n = 8) of healthy older (68 +/- 6 yr) adults participated in a 36-session progressive resistance exercise training program targeting the thigh muscles to determine the relationship between muscle gene expression and gains in muscle size and strength. Biopsies were obtained from the vastus lateralis at baseline 72 h after an acute bout of exercise and 72 h after completion of the training program. Training increased thigh muscle size (7%) and strength for the three exercises performed: knee extension (30%) and curl (28%) and leg press (20%). We quantified 18 transcripts encoding factors that function in inflammation, growth, and muscle remodeling that were demonstrated previously to be regulated by aging and acute exercise. The gain in extension strength and muscle size showed a high number of significant correlations with gene expression. These gains were most strongly correlated (P < or = 0.003, R > or = 0.89) with the baseline mRNA levels for insulin-like growth factor-1, matrix metalloproteinase-2 and its inhibitor TIMP1, and ciliary neurotrophic factor. Moreover, strength gains were inversely correlated with the change in these mRNA levels after training (P < or = 0.002 and R < or = -0.90). Changes in gene expression after acute exercise were not associated with training outcomes. These results suggest that higher baseline expression for key genes in muscle conveys an adaptive advantage for certain older adults. Individuals with lower baseline expression of these genes show less adaptation to exercise despite increased gene expression in response to training. These genes hold promise as useful predictors of training outcomes that could be used to design more effective exercise regimens for maintaining muscle function in older adults.

Changes in Prealbumin, Nutrient Intake, and Systemic Inflammation in Elderly Recuperative Care Patients

OBJECTIVES: To determine the relationship between prealbumin, nutrient intake, and indicators of inflammation for recuperative and rehabilitative care patients.

Expression of tissue factor in prostate cancer correlates with malignant phenotype

Tissue factor (TF), apart from its established role in hemostasis, has been implicated in promoting angiogenesis and metastasis in a wide array of tumors including prostate cancer. Expression of TF was evaluated in freshly-resected prostate specimens obtained from patients with localized (n=9) and androgen ablated (n=6) disease using real-time reverse transcription-polymerase chain reaction and Western blot analysis. TF was detected in all specimens in both stages of the disease. We further analyzed for correlations between TF expression and those of several angiogenic growth factors and their receptors. TF RNA expression correlated significantly with expression of vascular endothelial growth factor-A in these specimens (s=0.621, P=0.013). Eighty-one prostate specimens from patients with benign prostatic hyperplasia (n=27), localized prostate cancer (ES, n=32), and advanced disease (n=22) were also evaluated using immunohistochemistry and findings were correlated with clinical parameters. TF expression was detected on epithelial cells of the malignant glands. Furthermore, its expression levels correlated significantly with Gleason score (s=0.58, P=0.0001) and with the stage of the disease (s=0.441, P=0.0001) in these specimens. These data support the role of TF in angiogenesis and disease progression.

Differential expression of insulin-like growth factor binding protein-5 in pancreatic adenocarcinomas: identification using DNA microarray.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by its aggressiveness and resistance to both radiation and chemotherapeutic treatment. To better understand the molecular pathogenesis of pancreatic cancer, DNA array technology was employed to identify genes differentially expressed in pancreatic tumors when compared to non‐malignant pancreatic tissues. RNA isolated from 11 PDACs and 14 non‐malignant bulk pancreatic duct specimens was used to probe Affymetrix U95A DNA arrays. Genes that displayed at least a fourfold differential expression were identified and real‐time quantitative PCR was used to verify the differential expression of selected upregulated genes. Interrogation of the DNA array revealed that 73 genes were upregulated in PDACs and 77 genes were downregulated. The majority of the 150 genes identified have not been previously reported to be differentially expressed in pancreatic tumors, although a number of the upregulated transcripts have been reported previously. Immunohistochemistry was used to correlate calponin and insulin‐like growth factor binding protein‐5 (IGFBP‐5) RNA levels with protein expression in PDACs and revealed peritumoral calponin staining in the reactive stroma and intense focal staining of islets cells expressing IGFBP‐5 at the edge of tumors; thus implicating the interplay of various cell types to promote neoplastic cell growth within pancreatic carcinomas. As a potential modulator of cell proliferation, the overexpression of IGFBP‐5 may, therefore, play a significant role in the malignant transformation of normal pancreatic epithelial cells.

Identification of rat hippocampal mRNAs altered by the mitochondrial toxicant, 3-NPA.

Abstract: 3‐Nitropropionic acid (3‐NPA) is a model mitochondrial inhibitor that causes selective neurodegeneration in brain. 3‐NPA‐induced neurodegeneration occurs via a secondary neurotoxicity, caused initially by ATP depletion and redox changes in the cell. It is known that the hippocampal degeneration caused by mitochondrial dysfunction affects learning and memory, cognitive functions commonly disturbed in neurodegenerative diseases. The 3‐NPA‐ treated animal model can be used to study molecular mechanisms underlying selective degeneration in the brain. In this study, a microarray approach was utilized to define changes in the expression of 530 genes in the rat hippocampus after acute exposure to 3‐NPA at 30 mg/kg, sc. The microarray data were collected at 30 min, 2 h, and 4 h post‐3‐NPA. Statistical modeling using an ANOVA mixed model applied to Van der Waerden scores of rank‐transformed intensity data was used to assign statistical significance to 44 transcripts. These transcripts represent genes associated with energy metabolism, calcium homeostasis, the cytoskeleton, neurotransmitter metabolism, and other cellular functions. Changes in the transcripts of genes encoding 2 transporters [blood‐brain specific anion transporter (Slco1c1) and sodium‐dependent inorganic phosphate cotransporter (Slc17a7)] were confirmed by real‐time RT‐PCR. In conclusion, this study identified 2 new potential targets for enhancement of neuroprotection or inhibition of neurodegeneration associated with ATP depletion in the hippocampus.