Dette temanummer af Periskop drejer sig om, hvordan kunsthistoriefaget praktiseres anno 2022 – især med hensyn til den akademiske disciplin i dansk sammenhæng, som den udfoldes på universiteterne og ...i museumsregi. Vi har valgt at spørge bredt ud til, hvilke erfaringer der gøres med at skrive kunsthistorie pro tempera, hvilke forhold der former og udfordrer disciplinen – og hvilke nye stier der trædes i det faglige landskab. Det er der indkommet nogle tankevækkende bud på, som hver især åbner en dør til et arbejdende fagligt værksted, hvor der tænkes over, hvor faget står, og hvor det skal hen. Hensigten med temanummeret er at lægge op til fortsat samtale og diskussion.
Maximal muscle contraction force and muscle mass are both reduced during the natural aging process. Long-term training may be used to attenuate this age-related loss in muscle function and muscle ...size.
Maximum isometric quadriceps strength (MVC), rate of force development (RFD), and muscle fiber composition and size (CSA) were studied in elderly individuals (68-78 yr) chronically exposed (> 50 yr) to either endurance (E) or strength (S) training, and in age-matched, untrained (U) elderly group.
E and S showed greater MVC than did U. Contractile RFD was elevated in S compared with U, and S also demonstrated greater type II fiber CSA than did U and E. The proportion of type I fibers was greater in E compared with U and S.
Muscle fiber size and mechanical muscle performance, particularly RFD, were consistently elevated in aged individuals exposed to chronic (i.e., lifelong) strength training. This relative preservation in muscle morphology and function may provide an important physical reserve capacity to retain muscle mass and function above the critical threshold for independent living at old age.
NAD+ is a co-factor and substrate for enzymes maintaining energy homeostasis. Nicotinamide phosphoribosyltransferase (NAMPT) controls NAD+ synthesis, and in skeletal muscle, NAD+ is essential for ...muscle integrity. However, the underlying molecular mechanisms by which NAD+ synthesis affects muscle health remain poorly understood. Thus, the objective of the current study was to delineate the role of NAMPT-mediated NAD+ biosynthesis in skeletal muscle development and function.
To determine the role of Nampt in muscle development and function, we generated skeletal muscle-specific Nampt KO (SMNKO) mice. We performed a comprehensive phenotypic characterization of the SMNKO mice, including metabolic measurements, histological examinations, and RNA sequencing analyses of skeletal muscle from SMNKO mice and WT littermates.
SMNKO mice were smaller, with phenotypic changes in skeletal muscle, including reduced fiber area and increased number of centralized nuclei. The majority of SMNKO mice died prematurely. Transcriptomic analysis identified that the gene encoding the mitochondrial permeability transition pore (mPTP) regulator Cyclophilin D (Ppif) was upregulated in skeletal muscle of SMNKO mice from 2 weeks of age, with associated increased sensitivity of mitochondria to the Ca2+-stimulated mPTP opening. Treatment of SMNKO mice with the Cyclophilin D inhibitor, Cyclosporine A, increased membrane integrity, decreased the number of centralized nuclei, and increased survival.
Our study demonstrates that NAMPT is crucial for maintaining cellular Ca2+ homeostasis and skeletal muscle development, which is vital for juvenile survival.
•NAD+ salvage capacity is important for skeletal muscle development and survival.•Skeletal muscle-specific Nampt knockout mice exhibit a dystrophy-like phenotype.•Nampt deletion alters Ca2+ homeostasis and impairs mitochondrial function.•Low NAD+ levels signals mitochondrial permeability transition pore opening.•Cyclosporin A treatment improves sarcolemma integrity and increases survival rate.
Display omitted
Rheumatoid arthritis (RA) is often associated with diminished muscle mass, reflecting an imbalance between protein synthesis and protein breakdown. To investigate the anabolic potential of both ...exercise and nutritional protein intake we investigated the muscle protein synthesis rate and anabolic signaling response in patients with RA compared to healthy controls.
Thirteen RA patients (age range 34-84 years; diagnosed for 1-32 years, median 8 years) were individually matched with 13 healthy controls for gender, age, BMI and activity level (CON). Plasma levels of C-reactive protein (CRP), interleukin (IL)-6 and tumor necrosis factor (TNF)-α were measured using enzyme-linked immunosorbent assay (ELISA) in resting blood samples obtained on two separate days. Skeletal muscle myofibrillar and connective tissue protein fractional synthesis rate (FSR) was measured by incorporation of the amino acid (13)C6-phenylalanine tracer in the overnight fasted state for 3 hours (BASAL) and 3 hours after intake of whey protein (0.5 g/kg lean body mass) alone (PROT, 3 hrs) and in combination with knee-extensor exercise (EX) with one leg (8 × 10 reps at 70 % of 1RM; PROT + EX, 3 hrs). Expression of genes related to inflammatory signaling, myogenesis and muscle growth/atrophy were analyzed by real-time reverse transcriptase-polymerase chain reaction (RT-PCR).
CRP was significantly higher in the RA patients (2.25 (0.50) mg/l) than in controls (1.07 (0.25) mg/l; p = 0.038) and so was TNF-α (RA 1.18 (0.30) pg/ml vs. CON 0.64 (0.07) pg/ml; p = 0.008). Muscle myofibrillar protein synthesis in both RA patients and CON increased in response to PROT and PROT + EX, and even more with PROT + EX (p < 0.001), with no difference between groups (p > 0.05). The gene expression response was largely similar in RA vs. CON, however, expression of the genes coding for TNF-α, myogenin and HGF1 were more responsive to exercise in RA patients than in CON.
The study demonstrates that muscle protein synthesis rate and muscle gene expression can be stimulated by protein intake alone and in combination with physical exercise in patients with well-treated RA to a similar extent as in healthy individuals. This indicates that moderately inflamed RA patients have maintained their muscle anabolic responsiveness to physical activity and protein intake.
STUDY DESIGN.Prospective, randomized, double-blinded, placebo-controlled clinical trial.
OBJECTIVE.To evaluate whether 90-day subcutaneous injections with 20 μg teriparatide increases the volume and ...quality of the fusion mass compared to placebo based on 12-month postop fine cut computed tomography scans. The secondary objective is to evaluate whether parathyroid hormone (PTH) increases fusion rates compared to placebo.
SUMMARY OF BACKGROUND DATA.Few studies have investigated the effects of PTH on fusion in patients undergoing spinal arthrodesis. Early studies showed a more robust fusion mass with PTH after spinal fusion surgery. But the efficiency of PTH on noninstrumented spinal fusion surgery remains unclear.
METHODS.Patients with degenerative spondylolisthesis scheduled for noninstrumented posterolateral fusion were randomized to receive 90-day subcutaneous injections with 20 μg teriparatide (N = 41) or placebo (N = 46) in a 1:1 fashion. Fusion volume and quality was evaluated using 12-month postoperative fine cut computed tomography scans.
RESULTS.The two groups were comparable in terms of age, sex, and numbers of levels operated. PTH treatment was well tolerated but provided no additional benefit versus placebo. Fusion rates, the mean volume, and robustness of the fusion mass were similar between the PTH and placebo groups.
CONCLUSION.Ninety-day subcutaneous administration of 20 μg teriparatide did not increase fusion volume or improve the quality of the fusion mass in elderly patients compared to placebo after noninstrumented spinal fusion surgery for degenerative spondylolisthesis.Level of Evidence1
Due to poor bone stock in the elderly, a noninstrumented fusion is commonly performed in Scandinavia when instability is present. Allograft bone is often used as graft extender with consequent low ...fusion rates. The use of 15 amino acid residue (ABM/P-15) has shown superior fusion rates in dental and cervical spinal surgery but no clinical studies have been conducted in noninstrumented lumbar fusion surgery.
To evaluate patient reported outcomes (PROs) and the intertransverse fusion rate in noninstrumented posterolateral fusion with either ABM/P-15 or allograft.
Double-blind randomized clinical trial.
Patients 60 years or older with degenerative spondylolisthesis undergoing decompression and noninstrumented posterolateral fusion.
Visual analog scales for back and leg pain, Oswestry Disability Index and EuroQoL-5D.
One hundred one patients were enrolled in the study and randomized 1:1 to either ABM/P-15 (mixed 50/50, 5cc/level) or allograft bone (30 g/level), both mixed with local bone graft. PROs were collected at baseline and at 12 and 24 months after surgery. The patients underwent 1-year postoperative fine cut computed tomography-scans (0.9 mm) with reconstructions, independently evaluated by three reviewers. Fusion status was concluded by consensus of two of the three as “fusion” or “no fusion.”
There were 49 patients available for analysis in both cohorts. The two groups were similar in terms of sex distribution, age, and number of levels fused. The fusion rate was significantly higher in the ABM/P-15 group with 50% fused compared with 20% in the allograft group. PROs at baseline and at all follow-up time points were similar between the two groups.
Patients undergoing noninstrumented posterolateral fusion augmented with ABM/P-15 had a statistically significantly higher fusion rate compared with allograft when evaluated with postoperative fine cut computed tomography-scans (0.9 mm) with reconstructions. However, this did not translate to better clinical outcomes.
The morphology of articular cartilage (AC) enables painless movement. Aging and mechanical loading are believed to influence development of osteoarthritis (OA), yet the connection remains unclear.
...This narrative review describes the current knowledge regarding this area, with the literature search made on PubMed using appropriate keywords regarding AC, age, and mechanical loading.
Following skeletal maturation, chondrocyte numbers decline while increasing senescence occurs. Lower cartilage turnover causes diminished maintenance capacity, which produces accumulation of fibrillar crosslinks by advanced glycation end products, resulting in increased stiffness and thereby destruction susceptibility.
Mechanical loading changes proteoglycan content. Moderate mechanical loading causes hypertrophy and reduced mechanical loading causes atrophy. Overloading produces collagen network damage and proteoglycan loss, leading to irreversible cartilage destruction because of lack of regenerative capacity. Catabolic pathways involve inflammation and the transcription factor nuclear factor-κB. Thus, age seems to be a predisposing factor for OA, with mechanical overload being the likely triggering cause.
Background:
Previous studies have shown that eccentric training has a positive effect on Achilles tendinopathy, but few randomized controlled trials have compared it with other loading-based ...treatment regimens.
Purpose:
To evaluate the effectiveness of eccentric training (ECC) and heavy slow resistance training (HSR) among patients with midportion Achilles tendinopathy.
Study Design:
Randomized controlled trial; Level of evidence, 1.
Methods:
A total of 58 patients with chronic (>3 months) midportion Achilles tendinopathy were randomized to ECC or HSR for 12 weeks. Function and symptoms (Victorian Institute of Sports Assessment–Achilles), tendon pain during activity (visual analog scale), tendon swelling, tendon neovascularization, and treatment satisfaction were assessed at 0 and 12 weeks and at the 52-week follow-up. Analyses were performed on an intention-to-treat basis.
Results:
Both groups showed significant (P < .0001) improvements in Victorian Institute of Sports Assessment–Achilles and visual analog scale from 0 to 12 weeks, and these improvements were maintained at the 52-week follow-up. Concomitant with the clinical improvement, there was a significant reduction in tendon thickness and neovascularization. None of these robust clinical and structural improvements differed between the ECC and HSR groups. However, patient satisfaction tended to be greater after 12 weeks with HSR (100%) than with ECC (80%; P = .052) but not after 52 weeks (HSR, 96%; ECC, 76%; P = .10), and the mean training session compliance rate was 78% in the ECC group and 92% in the HSR group, with a significant difference between groups (P < .005).
Conclusion:
The results of this study show that both traditional ECC and HSR yield positive, equally good, lasting clinical results in patients with Achilles tendinopathy and that the latter tends to be associated with greater patient satisfaction after 12 weeks but not after 52 weeks.
1 Institute of Sports Medicine, Bispebjerg Hospital, Copenhagen, Denmark; 2 Saga Nutraceuticals Research Institute, Otsuka Pharmaceutical, Saga, Japan; 3 Research Unit, Department of Anaesthesiology, ...Ribe County Hospital Esbjerg, Esbjerg; and 4 Research Centre of Ageing and Osteoporosis, Department of Geriatrics, Glostrup University Hospital, Glostrup, Denmark
Submitted 3 September 2007
; accepted in final form 29 April 2008
We evaluated the response of various muscle and bone adaptation parameters with 24 wk of strength training in healthy, early postmenopausal women when a nutrient supplement (protein, carbohydrate, calcium, and vitamin D) or a placebo supplement (a minimum of energy) was ingested immediately following each training session. At inclusion, each woman was randomly and double-blindedly assigned to a nutrient group or a placebo (control) group. Muscle hypertrophy was evaluated from biopsies, MRI, and dual-energy X-ray absorptiometry (DEXA) scans, and muscle strength was determined in a dynamometer. Bone mineral density (BMD) was measured using DEXA scans, and bone turnover was determined from serum osteocalcin and collagen type I cross-linked carboxyl terminal peptide. The nutrient group improved concentric and isokinetic (60°/s) muscle strength from 6 to 24 wk by 9 ± 3% ( P < 0.01), whereas controls showed no change (1 ± 2%, P > 0.05). Only the nutrient group improved lean body mass ( P < 0.05) over the 24 wk. BMD responded similarly at the lumbar spine but changed differently in the two groups at the femoral neck ( P < 0.05) control: 0.943 ± 0.028 to 0.930 ± 0.024 g/mm 3 (–1.0 ± 1.4%); nutrient group: 0.953 ± 0.051 to 0.978 ± 0.043 g/mm 3 (3.8 ± 3.4%) when adjusted for age, body mass index, and BMD at inclusion. Bone formation displayed an interaction ( P < 0.05), mainly caused by increased osteocalcin at 24 wk in the nutrient group. In conclusion, we report that nutrient supplementation results in superior improvements in muscle mass, muscle strength, femoral neck BMD, and bone formation during 24 wk of strength training. The observed differences following such a short intervention emphasize the significance of postexercise nutrient supply on musculoskeletal maintenance.
exercise; nutrition; muscle hypertrophy
Address for reprint requests and other correspondence: L. Holm, Institute of Sports Medicine, Copenhagen, Bld. 8 1st, Bispebjerg Hospital, Bispebjerg Bakke 23, DK-2400 Copenhagen NV, Denmark (e-mail: l.holm.isotope{at}gmail.com )
PDF
