Sarcopenia: Aging-Related Loss of Muscle Mass and Function.

Sarcopenia is a loss of muscle mass and function in the elderly that reduces mobility, diminishes quality of life, and can lead to fall-related injuries, which require costly hospitalization and extended rehabilitation. This review focuses on the aging-related structural changes and mechanisms at cellular and subcellular levels underlying changes in the individual motor unit: specifically, the perikaryon of the α-motoneuron, its neuromuscular junction(s), and the muscle fibers that it innervates. Loss of muscle mass with aging, which is largely due to the progressive loss of motoneurons, is associated with reduced muscle fiber number and size. Muscle function progressively declines because motoneuron loss is not adequately compensated by reinnervation of muscle fibers by the remaining motoneurons. At the intracellular level, key factors are qualitative changes in posttranslational modifications of muscle proteins and the loss of coordinated control between contractile, mitochondrial, and sarcoplasmic reticulum protein expression. Quantitative and qualitative changes in skeletal muscle during the process of aging also have been implicated in the pathogenesis of acquired and hereditary neuromuscular disorders. In experimental models, specific intervention strategies have shown encouraging results on limiting deterioration of motor unit structure and function under conditions of impaired innervation. Translated to the clinic, if these or similar interventions, by saving muscle and improving mobility, could help alleviate sarcopenia in the elderly, there would be both great humanitarian benefits and large cost savings for health care systems.

Macrophage-derived glutamine boosts satellite cells and muscle regeneration.

Muscle regeneration is sustained by infiltrating macrophages and the consequent activation of satellite cells1-4. Macrophages and satellite cells communicate in different ways1-5, but their metabolic interplay has not been investigated. Here we show, in a mouse model, that muscle injuries and ageing are characterized by intra-tissue restrictions of glutamine. Low levels of glutamine endow macrophages with the metabolic ability to secrete glutamine via enhanced glutamine synthetase (GS) activity, at the expense of glutamine oxidation mediated by glutamate dehydrogenase 1 (GLUD1). Glud1-knockout macrophages display constitutively high GS activity, which prevents glutamine shortages. The uptake of macrophage-derived glutamine by satellite cells through the glutamine transporter SLC1A5 activates mTOR and promotes the proliferation and differentiation of satellite cells. Consequently, macrophage-specific deletion or pharmacological inhibition of GLUD1 improves muscle regeneration and functional recovery in response to acute injury, ischaemia or ageing. Conversely, SLC1A5 blockade in satellite cells or GS inactivation in macrophages negatively affects satellite cell functions and muscle regeneration. These results highlight the metabolic crosstalk between satellite cells and macrophages, in which macrophage-derived glutamine sustains the functions of satellite cells. Thus, the targeting of GLUD1 may offer therapeutic opportunities for the regeneration of injured or aged muscles.

Implications of mitochondrial fusion and fission in skeletal muscle mass and health.

The continuous dynamic reshaping of mitochondria by fusion and fission events is critical to keep mitochondrial quality and function under control in response to changes in energy and stress. Maintaining a functional, highly interconnected mitochondrial reticulum ensures rapid energy production and distribution. Moreover, mitochondrial networks act as dynamic signaling hub to adapt to the metabolic demands imposed by contraction, energy expenditure, and general metabolism. However, excessive mitochondrial fusion or fission results in the disruption of the skeletal muscle mitochondrial network integrity and activates a retrograde response from mitochondria to the nucleus, leading to muscle atrophy, weakness and influencing whole-body homeostasis. These actions are mediated via the secretion of mitochondrial-stress myokines such as FGF21 and GDF15. Here we will summarize recent discoveries in the role of mitochondrial fusion and fission in the control of muscle mass and in regulating physiological homeostasis and disease progression.

Does previous transurethral resection of the prostate affect the outcomes in robotic assisted radical prostatectomy?

PURPOSE: Transurethral resection of the prostate (TURP) is one of the surgical options for treating enlarged prostates with lower urinary symptoms (LUTS). In this older group of patients, concomitant prostate cancer is not uncommon. However, the fibrosis and distortion of the prostate anatomy by prior TURP can potentially hinder surgical efficacy at robotic-assisted radical prostatectomy (RARP). We aim to evaluate functional, and oncologic outcomes of RARP in patients with and without previous TURP. METHODS: 231 men with previous TURP underwent RARP (TURP group). These men were propensity score matched using clinicopathological characteristics to men without previous TURP who underwent RARP (Control group). Perioperative and postoperative variables were analysed for significant differences in outcomes between groups. Variables analysed included estimated blood loss (EBL), operative time, catheter time, hospitalization time, postoperative complications, positive surgical margins (PSM) rates, cancer status, biochemical recurrence (BCR), potency, and continence rates. RESULTS: Patients in the TURP group showed no statistically significant differences in operative safety measures including median EBL, operative time, catheter time, hospitalization time or postoperative complications. No significant difference between the groups in terms of potency rates and continence rates. Furthermore, there were no statistically significant differences in oncological outcomes, including PSM rates (15% vs 18%, P = 0.3) and BCR. CONCLUSION: In RARP after TURP there is often noticeable distortion of the surgical anatomy. For an experienced team the procedure is safe and provides similar oncologic control and functional outcomes to RARP in patients without previous TURP.

Iron supplementation is sufficient to rescue skeletal muscle mass and function in cancer cachexia.

Cachexia is a wasting syndrome characterized by devastating skeletal muscle atrophy that dramatically increases mortality in various diseases, most notably in cancer patients with a penetrance of up to 80%. Knowledge regarding the mechanism of cancer-induced cachexia remains very scarce, making cachexia an unmet medical need. In this study, we discovered strong alterations of iron metabolism in the skeletal muscle of both cancer patients and tumor-bearing mice, characterized by decreased iron availability in mitochondria. We found that modulation of iron levels directly influences myotube size in vitro and muscle mass in otherwise healthy mice. Furthermore, iron supplementation was sufficient to preserve both muscle function and mass, prolong survival in tumor-bearing mice, and even rescues strength in human subjects within an unexpectedly short time frame. Importantly, iron supplementation refuels mitochondrial oxidative metabolism and energy production. Overall, our findings provide new mechanistic insights in cancer-induced skeletal muscle wasting, and support targeting iron metabolism as a potential therapeutic option for muscle wasting diseases.

Early Diagnosis of Bronchopulmonary Dysplasia with E-Nose: A Pilot Study in Preterm Infants.

Bronchopulmonary dysplasia (BPD) is the most common respiratory disease in preterm and is still associated with increased mortality and morbidity. The great interest lies in identifying early biomarkers that can predict the development of BPD. This pilot study explores the potential of e-nose for the early identification of BPD risk in premature infants by analyzing volatile organic compounds (VOCs) in the exhaled breath condensate (EBC). Fourteen mechanically ventilated very preterm infants were included in this study. The clinical parameters and EBC were collected within the first 24 h of life. The discriminative ability of breath prints between preterms who did and did not develop BPD was investigated using pattern recognition, a machine learning algorithm, and standard statistical methods. We found that e-nose probes can significantly predict the outcome of "no-BPD" vs. "BPD". Specifically, a subset of probes (S18, S24, S14, and S6) were found to be significantly predictive, with an AUC of 0.87, 0.89, 0.82, 0.8, and p = 0.019, 0.009, 0.043, 0.047, respectively. The e-nose is an easy-to-use, handheld, non-invasive electronic device that quickly samples breath. Our preliminary study has shown that it has the potential for early prediction of BPD in preterms.

Impacts on functional and oncological outcomes of Robotic-assisted Radical Prostatectomy 10 years after the US Preventive Service Taskforce recommendations against PSA screening.

OBJECTIVE: In the following years after the United States Preventive Service Task Force (USPSTF) recommendation against prostate cancer screening with PSA in 2012, several authors worldwide described an increase in higher grades and aggressive prostate tumors. In this scenario, we aim to evaluate the potential impacts of USPSTF recommendations on the functional and oncological outcomes in patients undergoing robotic-assisted radical prostatectomy (RARP) in a referral center. MATERIAL AND METHODS: We included 11396 patients who underwent RARP between 2008 and 2021. Each patient had at least a 12-month follow-up. The cohort was divided into two groups based on an inflection point in the outcomes at the end of 2012 and the beginning of 2013. The inflection point period was detected by Bayesian regression with multiple change points and regression with unknown breakpoints. We reported continuous variables as median and interquartile range (IQR) and categorical variables as absolute and relative percent frequencies. RESULTS: Group 1 had 4760 patients, and Group 2 had 6636 patients, with a median follow-up of 109 and 38 months, respectively. In the final pathology, Group 2 had 9.5% increase in tumor volume, 24% increase on Gleason ≥ 4+3 (ISUP 3) , and 18% increase on ≥ pT3. This translated to a 6% increase in positive surgical margins and 24% reduction in full nerve sparing in response to the worsening pathology. There was a significant decline in post-operative outcomes in Group 2, including a 12-month continence reduction of 9%, reduction in potency by 27%, and reduction of trifecta by 22%. CONCLUSIONS: The increasing number of high-risk patients has led to worse functional and oncologic outcomes. The initial rapid rise in PSM was leveled by the move towards more partial nerve sparing. Among some historical changes in prostate cancer diagnosis and management in the period of our study, the USPSTF recommendation coincided with worse outcomes of prostate cancer treatment in a population who could benefit from PSA screening at the appropriate time.

The role of warm ischemia time on functional outcomes after robotic partial nephrectomy: a radionuclide renal scan study from the clock randomized trial.

PURPOSE: To evaluate the relationship between warm ischemia time (WIT) duration and renal function after robot-assisted partial nephrectomy (RAPN). METHODS: The CLOCK trial is a phase 3 randomized controlled trial comparing on- vs off-clamp RAPN. All patients underwent pre- and postoperative renal scintigraphy. Six-month absolute variation of eGFR (AV-GFR), rate of relative variation in eGFR over 25% (RV-GFR > 25), absolute variation of split renal function (SRF) at scintigraphy (AV-SRF). The relationships WIT/outcomes were assessed by correlation graphs and then modeled by uni- and multivariable regression. RESULTS: 324 patients were included (206 on-clamp, 118 off-clamp RAPN). Correlation graphs showed a threshold on WIT equal to 10 min. The differences in outcome measures between cases with WIT < vs ≥ 10 min were: AV-GFR - 3.7 vs - 7.5 ml/min (p < 0.001); AV-SRF - 1% vs - 3.6% (p < 0.001); RV-GFR > 25 9.3% vs 17.8% (p = 0.008). Multivariable models found that AV-GFR was related to WIT ≥ 10 min (regression coefficient [RC] - 0.52, p = 0.019), age (RC - 0.35, p = 0.001) and baseline eGFR (RC - 0.30, p < 0.001); RV-GFR > 25 to WIT ≥ 10 min (odds ratio [OR] 1.11, p = 0.007) and acute kidney injury defined as > 50% increase in serum creatinine (OR 19.7, p = 0.009); AV-SRF to WIT ≥ 10 min (RC - 0.30, p = 0.018), baseline SRF (RC - 0.76, p < 0.001) and RENAL score (RC - 0.60. p = 0.028). The main limitation was that the CLOCK trial was designed on a different endpoint and therefore the present analysis could be underpowered. CONCLUSIONS: Up to 10 min WIT had no consequences on functional outcomes. Above the 10-min threshold, a statistically significant, but clinically negligible impact was found.

Predictors of Ball Velocity in the Sitting Volleyball Serve: A Causal Analysis.

This study explored the performance of the Sitting Volleyball serve by investigating the causal factors associated with ball velocity. Thirty-seven athletes underwent anthropometry and strength assessment and performed ten successful maximal effort serves. Ball velocity was measured using a sports radar gun. The hip, shoulder, elbow and wrist angles at the instant of ball impact as well as the height of ball impact were estimated through two-dimensional motion analysis. The causal relationships between variables were described through a linear Structural Equation Model and a Directed Acyclic Graph. Results showed that a smaller hip angle determines a greater shoulder angle, which in turn causes a greater elbow angle. A more open elbow angle together with a greater vertical reach allowed for a greater height of ball impact. Finally, increased height of ball impact along with greater abdominal strength are beneficial for higher ball velocity. These results underlined that the Sitting Volleyball serve is a multifactorial stroke involving anthropometric, technical and strength factors and suggest that athletes should improve their abdominal strength and master the technique necessary to perform the serve with the shoulder and the elbow joints fully extended in order to produce the greatest possible impact on the ball.

Mitochondrial DNA and TLR9 drive muscle inflammation upon Opa1 deficiency.

Opa1 participates in inner mitochondrial membrane fusion and cristae morphogenesis. Here, we show that muscle-specific Opa1 ablation causes reduced muscle fiber size, dysfunctional mitochondria, enhanced Fgf21, and muscle inflammation characterized by NF-κB activation, and enhanced expression of pro-inflammatory genes. Chronic sodium salicylate treatment ameliorated muscle alterations and reduced the muscle expression of Fgf21. Muscle inflammation was an early event during the progression of the disease and occurred before macrophage infiltration, indicating that it is a primary response to Opa1 deficiency. Moreover, Opa1 repression in muscle cells also resulted in NF-κB activation and inflammation in the absence of necrosis and/or apoptosis, thereby revealing that the activation is a cell-autonomous process and independent of cell death. The effects of Opa1 deficiency on the expression NF-κB target genes and inflammation were absent upon mitochondrial DNA depletion. Under Opa1 deficiency, blockage or repression of TLR9 prevented NF-κB activation and inflammation. Taken together, our results reveal that Opa1 deficiency in muscle causes initial mitochondrial alterations that lead to TLR9 activation, and inflammation, which contributes to enhanced Fgf21 expression and to growth impairment.

Is off-clamp robot-assisted partial nephrectomy beneficial for renal function? Data from the CLOCK trial.

OBJECTIVES: To compare the functional outcomes of on- vs off-clamp robot-assisted partial nephrectomy (RAPN) within a randomized controlled trial (RCT). MATERIALS AND METHODS: The CLOCK study (CLamp vs Off Clamp the Kidney during robotic partial nephrectomy; NCT02287987) is a multicentre RCT including patients with normal baseline function, two kidneys and masses with RENAL scores ≤ 10. Pre- and postoperative renal scintigraphy was prescribed. Renal defatting and hilum isolation were required in both study arms; in the on-clamp arm, ischaemia was imposed until the completion of medullary renorraphy, while in the off-clamp condition it was not allowed throughout the procedure. The primary endpoint was 6-month absolute variation in estimated glomerular filtration rate (AV-GFR); secondary endpoints were: 12, 18 and 24-month AV-GFR; 6-month estimated glomerular filtration rate variation >25% rate (RV-GFR >25); and absolute variation in ipsilateral split renal function (AV-SRF). The planned sample size was 102 + 102 cases, after taking account crossover of cases to the alternate study arm; a 1:1 randomization was performed. AV-GFR and AV-SRF were compared using analysis of covariation, and RV-GFR >25 was assessed using multivariable logistic regression. Intention-to-treat (ITT) and per-protocol analyses (PP) were performed. RESULTS: A total of 160 and 164 patients were randomly assigned to on- and off-clamp RAPN, respectively; crossover was observed in 14% and 43% of the on- and off-clamp arms, respectively. We were unable to find any statistically significant difference between on- vs off-clamp with regard to the primary endpoint (ITT: 6-month AV-GFR -6.2 vs -5.1 mL/min, mean difference 0.2 mL/min, 95% confidence interval [CI] -3.1 to 3.4 [P = 0.8]; PP: 6-month AV-GFR -6.8 vs -4.2 mL/min, mean difference 1.6 mL/min, 95% CI -2.3 to 5.5 [P = 0.7]) or with regard to the secondary endpoints. The median warm ischaemia time was 14 vs 15 min in the ITT analysis and 14 vs 0 min in the PP analysis. CONCLUSION: In patients with regular baseline function and two kidneys, we found no evidence of differences in functional outcomes for on- vs off-clamp RAPN.

External validation of the Palacios' equation: a simple and accurate tool to estimate the new baseline renal function after renal cancer surgery.

PURPOSE: To externally validate the Palacios' equation estimating the new baseline glomerular filtration rate (NB-GFR) after partial or radical-nephrectomy (PN, RN) for Renal cancer carcinoma (RCC). MATERIALS AND METHODS: Our research group recently published two studies that investigated the association between renal function and cancer-specific survival in RCC. The first one included 3457 patients undergone RN or PN for a cT1-2 RCC coming from five high-volume centers; the second one considered 1767 patients undergone RN or PN for a cT1-4 RCC in a single high-volume center. From such datasets, available complete patients' data were used to calculate the predicted NB-GFR through the Palacios' equation: predicted NB-GFR = 35.03 + 0.65 ∙ preoperative GFR - 18.19 ∙ (if radical nephrectomy) - 0.25 ∙ age + 2.83 ∙ (if tumor size > 7 cm) - 2.09 ∙ (if diabetes). The observed NB-GFR was calculated by the CKD-EPI equation on serum creatinine at 3-12 months after surgery. Concordance between observed and predicted NB-GFR was evaluated by Lin's concordance correlation coefficient and Bland-Altman analysis. RESULTS: 2419 patients were included (1210, cohort #1; 1219, cohort #2). The median observed NB-GFR value in cohorts #1 and #2 was 73.0 ml/min/1.73 m2 (IQR 56.1-90.1) and 64.2 ml/min/1.73 m2 (IQR 49.6-83); the median predicted NB-GFR was 71.1 ml/min/1.73 m2 (IQR 58-81.5) and 62.6 ml/min/1.73m2 (IQR 47.9-75.9). The concordance line showed a slope of 0.80 and 0.86, and an intercept at 11.02 and 5.41 ml/min/1.73 m2 in the cohort#1 and #2, respectively. The Palacio's equation moderately over-estimated and under-estimated NB-GFR, for values below and above the cut-off of 50 ml/min/1.73 m2 and 35 ml/min/1.73m2 in cohort#1 and #2. The Lin's concordance correlation coefficient was 0.79 (95% CI 0.77-0.81) and 0.83 (95% CI 0.82-0.85). CONCLUSIONS: We confirm the predictive performances of Palacios' equation, supporting its utilization in clinical practice.

Autophagy maintains stemness by preventing senescence.

During ageing, muscle stem-cell regenerative function declines. At advanced geriatric age, this decline is maximal owing to transition from a normal quiescence into an irreversible senescence state. How satellite cells maintain quiescence and avoid senescence until advanced age remains unknown. Here we report that basal autophagy is essential to maintain the stem-cell quiescent state in mice. Failure of autophagy in physiologically aged satellite cells or genetic impairment of autophagy in young cells causes entry into senescence by loss of proteostasis, increased mitochondrial dysfunction and oxidative stress, resulting in a decline in the function and number of satellite cells. Re-establishment of autophagy reverses senescence and restores regenerative functions in geriatric satellite cells. As autophagy also declines in human geriatric satellite cells, our findings reveal autophagy to be a decisive stem-cell-fate regulator, with implications for fostering muscle regeneration in sarcopenia.

The connection between the dynamic remodeling of the mitochondrial network and the regulation of muscle mass.

The dynamic coordination of processes controlling the quality of the mitochondrial network is crucial to maintain the function of mitochondria in skeletal muscle. Changes of mitochondrial proteolytic system, dynamics (fusion/fission), and mitophagy induce pathways that affect muscle mass and performance. When muscle mass is lost, the risk of disease onset and premature death is dramatically increased. For instance, poor quality of muscles correlates with the onset progression of several age-related disorders such as diabetes, obesity, cancer, and aging sarcopenia. To date, there are no drug therapies to reverse muscle loss, and exercise remains the best approach to improve mitochondrial health and to slow atrophy in several diseases. This review will describe the principal mechanisms that control mitochondrial quality and the pathways that link mitochondrial dysfunction to muscle mass regulation.

Relationships between anthropometric characteristics, block settings, and block clearance technique during the sprint start.

This study aimed to identify how body dimensions interact with anteroposterior block distances to influence lower limb joint angles in the "set" position, how these angles relate to block clearance kinetic and kinematic parameters, and how these biomechanical parameters influence sprint start performance in sprinters of both sexes and of different ability levels. Seventy-eight sprinters performed six maximal-effort 10 m sprints. Joint angles in the "set" position were quantified through 2D video analysis, and the forces generated during block exit were measured by dynamometric starting blocks. Lower limb length was associated with the front block-starting line distance ([FB/SL], partial correlation [rPC] = 0.48) and was a significant predictor of FB/SL (R2 = 0.39). The FB/SL was associated with front hip angle (rPC = 0.38), which was consequently associated with numerous kinetic variables during block clearance (rPC from -0.41 to -0.61). Coaches should be encouraged to explore the interactions between individual lower limb lengths and the FB/SL distance in both male and female sprinters to manipulate the front hip angle in the "set" position in an attempt to achieve more favourable block clearance kinetics.

Comparing the outcomes of robotic assisted radical prostatectomy in black and white men: Experience of a high-volume center.

BACKGROUND: Global cancer incidence ranks Prostate Cancer (CaP) as the second highest overall, with Africa and the Caribbean having the highest mortality. Previous literature suggests disparities in CaP outcomes according to ethnicity, specifically functional and oncological are suboptimal in black men. However, recent data shows black men achieve post radical prostatectomy (RP) outcomes equivalent to white men in a universally insured system. Our objective is to compare outcomes of patients who self-identified their ethnicity as black or white undergoing RP at our institution. MATERIALS AND METHODS: From 2008 to 2017, 396 black and 4929 white patients underwent primary robotic-assisted radical prostatectomy (RARP) with a minimum follow-up of 5 years. Exclusion criteria were concomitant surgery and cancer status not available. A propensity score (PS) match was performed with a 1:1, 1:2, and 1:3 ratio without replacement. Primary endpoints were potency, continence recovery, biochemical recurrence (BCR), positive surgical margins (PSM), and post-operative complications. RESULTS: After PS 1:1 matching, 341 black vs. 341 white men with a median follow-up of approximately 8 years were analyzed. The overall potency and continence recovery at 12 months was 52% vs 58% (p=0.3) and 82% vs 89% (p=0.3), respectively. PSM rates was 13.4 % vs 14.4% (p = 0.75). Biochemical recurrence and persistence PSA was 13.8% vs 14.1% and 4.4% vs 3.2% respectively (p=0.75). Clavien-Dindo complications (p=0.4) and 30-day readmission rates (p=0.5) were similar. CONCLUSION: In our study, comparing two ethnic groups with similar preoperative characteristics and full access to screening and treatment showed compatible RARP results. We could not demonstrate outcomes superiority in one group over the other. However, this data adds to the growing body of evidence that the racial disparity gap in prostate cancer outcomes can be narrowed if patients have appropriate access to prostate cancer management. It also could be used in counseling surgeons and patients on the surgical intervention and prognosis of prostate cancer in patients with full access to gold-standard screening and treatment.

Thulium laser enucleation of prostate versus laparoscopic trans-vesical simple prostatectomy in the treatment of large benign prostatic hyperplasia: head-to-head comparison.

OBJECTIVES: To compare thulium laser enucleation of prostate (ThuLEP) versus laparoscopic trans-vesical simple prostatectomy (LSP) in the treatment of benign prostatic hyperplasia (BPH). MATERIALS AND METHODS: Data of patients who underwent surgery for "large" BPH (>80mL) at three Institutions were collected and analyzed. Two institutions performed ThuLEP only; the third institution performed LSP only. Preoperative (indwelling catheter status, prostate volume (PVol), hemoglobin (Hb), Qmax, post-voiding residual volume (PVR), IPSS, QoL, IIEF-5) and perioperative data (operative time, enucleated adenoma, catheterization time, length of stay, Hb-drop, complications) were compared. Functional (Qmax, PVR, %ΔQmax) and patient-reported outcomes (IPSS, QoL, IIEF-5, %ΔIPSS, %ΔQoL) were compared at last follow-up. RESULTS: 80 and 115 patients underwent LSP and ThuLEP, respectively. At baseline, median PVol was 130 versus 120mL, p <0.001; Qmax 9.6 vs. 7.1mL/s, p=0.005; IPSS 21 versus 25, p <0.001. Groups were comparable in terms of intraoperative complications (1 during LSP vs. 3 during ThuLEP) and transfusions (1 per group). Differences in terms of operative time (156 vs. 92 minutes, p <0.001), Hb-drop (-2.5 vs. -0.9g/dL, p <0.001), catheterization time (5 vs. 2 days, p <0.001) and postoperative complications (13.8% vs. 0, p <0.001) favored ThuLEP. At median follow-up of 40 months after LSP versus 30 after ThuLEP (p <0.001), Qmax improved by 226% vs. 205% (p=0.5), IPSS decreased by 88% versus 85% (p=0.9), QoL decreased by 80% with IIEF-5 remaining almost unmodified for both the approaches. CONCLUSIONS: Our analysis showed that LSP and ThuLEP are comparable in relieving from BPO and improving the patient-reported outcomes. Invasiveness of LSP is more significant.

Neuromuscular junction instability and altered intracellular calcium handling as early determinants of force loss during unloading in humans.

KEY POINTS: Few days of unloading are sufficient to induce a decline of skeletal muscle mass and function; notably, contractile force is lost at a faster rate than muscle mass. The reasons behind this disproportionate loss of muscle force are still poorly understood. We provide strong evidence of two mechanisms only hypothesized until now for the rapid muscle force loss in only 10 days of bed rest. Our results show that an initial neuromuscular junction instability, accompanied by alterations in the innervation status and impairment of single fibre sarcoplasmic reticulum function contribute to the loss of contractile force in front of a preserved myofibrillar function and central activation capacity. Early onset of neuromuscular junction instability and impairment in calcium dynamics involved in excitation-contraction coupling are proposed as eligible determinants to the greater decline in muscle force than in muscle size during unloading. ABSTRACT: Unloading induces rapid skeletal muscle atrophy and functional decline. Importantly, force is lost at a much higher rate than muscle mass. We aimed to investigate the early determinants of the disproportionate loss of force compared to that of muscle mass in response to unloading. Ten young participants underwent 10 days of bed rest (BR). At baseline (BR0) and at 10 days (BR10), quadriceps femoris (QF) volume (VOL) and isometric maximum voluntary contraction (MVC) were assessed. At BR0 and BR10 blood samples and biopsies of vastus lateralis (VL) muscle were collected. Neuromuscular junction (NMJ) stability and myofibre innervation status were assessed, together with single fibre mechanical properties and sarcoplasmic reticulum (SR) calcium handling. From BR0 to BR10, QFVOL and MVC decreased by 5.2% (P = 0.003) and 14.3% (P < 0.001), respectively. Initial and partial denervation was detected from increased neural cell adhesion molecule (NCAM)-positive myofibres at BR10 compared with BR0 (+3.4%, P = 0.016). NMJ instability was further inferred from increased C-terminal agrin fragment concentration in serum (+19.2% at BR10, P = 0.031). Fast fibre cross-sectional area (CSA) showed a trend to decrease by 15% (P = 0.055) at BR10, while single fibre maximal tension (force/CSA) was unchanged. However, at BR10 SR Ca2+ release in response to caffeine decreased by 35.1% (P < 0.002) and 30.2% (P < 0.001) in fast and slow fibres, respectively, pointing to an impaired excitation-contraction coupling. These findings support the view that the early onset of NMJ instability and impairment in SR function are eligible mechanisms contributing to the greater decline in muscle force than in muscle size during unloading.

A Predictive Preoperative and Postoperative Nomogram for Postoperative Potency Recovery after Robot-Assisted Radical Prostatectomy.

PURPOSE: Prediction of potency recovery following robot-assisted radical prostatectomy (RARP) is useful for better patient counseling and postoperative treatment strategies. In this study we propose a preoperative and postoperative nomogram to predict postoperative potency recovery following RARP. MATERIALS AND METHODS: Patients from development set (6,502) were selected to develop the nomograms, and patients in validation set (2,706) were used for validation. Cox regression models were fitted on the development cohort to predict potency recovery after RARP using as prognostic factors the covariates selected. Two nomograms were drawn using the regression coefficients of the preoperative and postoperative Cox models. RESULTS: The discrimination ability of the preoperative model was evaluated on the development cohort using the receiver operator curves estimated at 3, 6, 12 and 24 months. The AUC at these time points was 0.726, 0.734, 0.754, and 0.778, respectively. The areas under the curve of the postoperative model at 3, 6, 12 and 24 months were 0.746, 0.756 and 0.777, and 0.801, respectively. Preoperative and postoperative predictive models were validated using a separate set of 2,706 patients. The AUCs of the preoperative model at 3, 6, 12 and 24 months were 0.789, 0.772, 0.768, and 0.778, respectively. The ROC curves of the postoperative model at 3, 6, 12 and 24 months with AUCs of 0.807, 0.797, 0.793 and 0.798, respectively. Along with age and preoperative sexual function, nerve-sparing technique determines the potency outcomes justifying better AUC for postoperative model vs the preoperative model. CONCLUSIONS: The above nomograms help us to predict with good accuracy the probability of potency recovery within 3, 6, 12 and 24 months following surgery taking into consideration preoperative and postoperative factors. This is a novel tool for the care giver to predict realistic expectation of potency outcomes to the patients, while preoperative and immediate postoperative counseling.

Deviation from the Protocol of a Randomized Clinical Trial Comparing On-Clamp versus Off-Clamp Laparoscopic Partial Nephrectomy (CLOCK II Laparoscopic Study): A Real-Life Analysis.

PURPOSE: We assess factors/additional morbidities related to the conversion of clamping approach during off-clamp vs on-clamp laparoscopic partial nephrectomy in the setting of a randomized study. MATERIALS AND METHODS: Consecutive candidates for laparoscopic partial nephrectomy from 6 institutions were randomized to on-clamp or off-clamp surgery. The present study analyzed 1) off-clamp arm patients, comparing the procedures finalized per protocol without artery clamping (off-clamp) to those needing renal artery clamping (shift-on-clamp) and 2) on-clamp arm patients, comparing the procedures finalized with artery clamping (on-clamp) to those completed without clamping (shift-off-clamp). RESULTS: A total of 123 patients were randomized to on-clamp and 126 to off-clamp surgery. Of the off-clamp patients 41 (32.5%) converted to on-clamp. Of the on-clamp patients 70 (56.9%) completed surgery without clamping the renal artery due to subjective intraoperative decision of the surgeon. Tumor size was greater in shift-on-clamp vs off-clamp cases (4 vs 3, p=0.002). Conversely, tumor size (3.7 vs 3 cm, p=0.002) and R.E.N.A.L. nephrometry score (6 vs 5, p=0.038) were lower in shift-off-clamp cases. Shift-on-clamp cases had longer operative times and greater changes in estimated glomerular filtration rate on postoperative day 1. Shift-off-clamp cases had shorter operative times. A higher proportion of patients who completed on-clamp surgery per protocol had a greater than 25% drop in estimated glomerular filtration rate on postoperative day 1 (29.4%) compared to smaller changes (10.3%, p=0.009) in estimated glomerular filtration rate. Increasing tumor size and complete endophytic growth pattern predicted shift-on-clamp while preventing shift-off-clamp. Body mass index above 28 predicted shift-off-clamp. CONCLUSIONS: The likelihood of shift-on/off-clamp relies on tumor size/complexity. The intraoperative need to convert the planned strategy seemed harmless on postoperative course. An advantage in terms of early functional outcomes does exist when avoiding artery clamping.