Skeletal Muscle

The association between change in temporal muscle mass and treatment of acromegaly

PURPOSE

We aimed to evaluate the relationship between temporal muscle thickness and GH/IGF-1 elevation and the effect of acromegaly treatment on temporal muscle thickness.

METHODS

Patients with acromegaly and healthy controls were included in the study. While laboratory parameters, clinical findings and temporal muscle thickness of acromegaly patients at the time of diagnosis and one year after treatment were evaluated, laboratory parameters and temporal muscle thickness of healthy controls were evaluated only during the period when they were included in the study. Temporal muscle thickness was measured using pituitary MRI. Temporal muscle thickness of patients with acromegaly was compared with healthy controls. We also evaluated how temporal muscle thickness changes with treatment in patients with acromegaly and the association between laboratory parameters and temporal muscle thickness.

RESULTS

In patients with acromegaly, measurements of left, right, and mean temporal muscle thickness at the time of diagnosis were found to be significantly higher than those of healthy controls' measurements at the time of their inclusion in the study (p = 0.007, p = 0.014 and p = 0.018, respectively). However, no significant difference was found when comparing the temporal muscle thickness of the 1st year of acromegaly treatment with the temporal muscle thickness of healthy controls at the time of their inclusion in the study (p = 0.155, p = 0.189, p = 0.198, respectively). In addition, a significant decrease was detected in the left, right and mean temporal muscle thicknesses of patients with acromegaly before and after treatment. While the temporal muscle thickness at the time of diagnosis was thicker in patients with acromegaly receiving surgical + medical treatment than in patients receiving exclusively surgical treatment, statistical significance was only found in the left temporal muscle thickness (p = 0.042).

CONCLUSION

Temporal muscle thickness was found to be associated with treatment modalities in patients with acromegaly.

Assessment of forearm muscles with ultrasound shear wave elastography in patients with acromegaly

PURPOSE

The effects of acromegaly on soft tissues, bones and joints are well-documented, but information on its effects on muscle mass and quality remains limited. The primary goal of this study is to assess the sonoelastographic features of forearm muscles in patients with acromegaly.

METHOD

Forty-five patients with acromegaly and 45 healthy controls similar in terms of gender, age, and body mass index (BMI) were included in a single-center, multidisciplinary, cross-sectional study. The body composition was analyzed using bioelectrical impedance analysis (BIA), and height-adjusted appendicular skeletal muscle index (hSMI) was calculated. The dominant hand's grip strength was also measured. Two radiologists specialized in the musculoskeletal system employed ultrasound shear wave elastography (SWE) to assess the thickness and stiffness of brachioradialis and biceps brachii muscles.

RESULTS

The acromegaly group had significantly higher thickness of both the biceps brachii (p = 0.034) and brachioradialis muscle (p = 0.046) than the control group. However, the stiffness of the biceps brachii (p = 0.001) and brachioradialis muscle (p = 0.001) was lower in the acromegaly group than in the control group. Disease activity has not caused a significant difference in muscle thickness and stiffness in the acromegaly group (p > 0.05). The acromegaly group had a higher hSMI (p = 0.004) than the control group. The hand grip strength was similar between the acromegaly and control group (p = 0.594).

CONCLUSION

The patients with acromegaly have an increased muscle thickness but decreased muscle stiffness in the forearm muscles responsible for elbow flexion. Acromegaly can lead to a permanent deterioration of the muscular structure regardless of the disease activity.

Autophagy and ALS: mechanistic insights and therapeutic implications

Mechanisms of protein homeostasis are crucial for overseeing the clearance of misfolded and toxic proteins over the lifetime of an organism, thereby ensuring the health of neurons and other cells of the central nervous system. The highly conserved pathway of autophagy is particularly necessary for preventing and counteracting pathogenic insults that may lead to neurodegeneration. In line with this, mutations in genes that encode essential autophagy factors result in impaired autophagy and lead to neurodegenerative conditions such as amyotrophic lateral sclerosis (ALS). However, the mechanistic details underlying the neuroprotective role of autophagy, neuronal resistance to autophagy induction, and the neuron-specific effects of autophagy-impairing mutations remain incompletely defined. Further, the manner and extent to which non-cell autonomous effects of autophagy dysfunction contribute to ALS pathogenesis are not fully understood. Here, we review the current understanding of the interplay between autophagy and ALS pathogenesis by providing an overview of critical steps in the autophagy pathway, with special focus on pivotal factors impaired by ALS-causing mutations, their physiologic effects on autophagy in disease models, and the cell type-specific mechanisms regulating autophagy in non-neuronal cells which, when impaired, can contribute to neurodegeneration. This review thereby provides a framework not only to guide further investigations of neuronal autophagy but also to refine therapeutic strategies for ALS and related neurodegenerative diseases.Abbreviations: ALS: amyotrophic lateral sclerosis; Atg: autophagy-related; CHMP2B: charged multivesicular body protein 2B; DPR: dipeptide repeat; FTD: frontotemporal dementia; iPSC: induced pluripotent stem cell; LIR: LC3-interacting region; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MTOR: mechanistic target of rapamycin kinase; PINK1: PTEN induced kinase 1; RNP: ribonuclear protein; sALS: sporadic ALS; SPHK1: sphingosine kinase 1; TARDBP/TDP-43: TAR DNA binding protein; TBK1: TANK-binding kinase 1; TFEB: transcription factor EB; ULK: unc-51 like autophagy activating kinase; UPR: unfolded protein response; UPS: ubiquitin-proteasome system; VCP: valosin containing protein.

The effectiveness of a therapist-oriented home rehabilitation program for a patient with acromegaly: A case study

BACKGROUND

Acromegaly causes numerous functional limitations that negatively impact patients' performance of activities of daily living (ADLs) and contribute to the deterioration of health-related quality of life (HRQoL). Thus, the purpose of the present case study was to evaluate the effect of therapist-oriented home rehabilitation (TOHR) for a patient with acromegaly.

CASE DESCRIPTION

We report the case of a 53-year-old man who was diagnosed with primary acromegaly 17 years ago. He complained of difficulties performing tasks that involved his hands, pain in the lower limbs, and fatigue when he climbed a few flights of stairs. Although he performed ADLs independently, he reported some difficulties or discomfort when performing them.

INTERVENTION AND OUTCOME

The patient underwent a booklet-guided physical exercise program that lasted two months (three times per week, 60 minutes per session). The activities included overall stretching, muscle strengthening, and endurance exercises, along with aerobic conditioning through functional circuit training. After two months of exercise, he reported improved HRQoL as assessed with the Acromegaly Quality of Life Questionnaire, with increases in quadriceps muscle strength and 6-min walking distance. However, none of these benefits remained when the patient was assessed after a 1-month washout period.

CONCLUSION

This study showed that patients with acromegaly may benefit markedly from TOHR, which could provide a novel therapeutic approach as an adjunct to hormone control therapy.

The robustness of diagnostic tests for GH deficiency in adults

Since the 1970s, GH treatment has been an important tool in paediatric endocrinology for the management of growth retardation. It is now accepted that adults with severe GH deficiency (GHD) demonstrate impaired physical and psychological well-being and may benefit from replacement therapy with recombinant human GH. There is, however, an ongoing debate on how to diagnose GHD, especially in adults. A GH response below the cut-off limit of a GH-stimulation test is required in most cases for establishing GHD in adults. No 'gold standard' GH-stimulation test exists, but some GH stimulation tests may be more robust to variations in patient characteristics such as age and gender, as well as to pre-test conditions like heat exposure due to a hot bath or bicycling. However, body mass index (BMI) is negatively associated with GH-responses to all available GH-stimulation tests and glucocorticoid treatment, including conventional substitution therapy, influences the GH-responses. Recently, the role of IGF-I measurements in the clinical decision making has been discussed. The aim of this review is to discuss the available GH-stimulation tests. In this author's opinion, tests which include growth-hormone-releasing hormone (GHRH) tend to be more potent and robust, especially the GHRH+arginine test which has been proven to be of clinical use. In contrast, the insulin tolerance test (ITT) and the glucagon test appear to have too many drawbacks.

Skeletal muscle mass in acromegaly assessed by magnetic resonance imaging and dual-photon x-ray absorptiometry

CONTEXT

GH and IGF-I are nitrogen retaining and anabolic, but the impact of long-term exposure to supraphysiological GH and IGF-I, either from endogenous overproduction in acromegaly or exogenous sources, on skeletal muscle (SM) mass is not clear.

OBJECTIVES

The objectives of the study were to assess SM mass by whole-body magnetic resonance imaging (MRI) in acromegaly and test the hypothesis that dual-energy x-ray absorptiometry (DXA) lean tissue mass-derived estimates of SM accurately estimate true SM mass.

DESIGN, SETTING, AND PATIENTS

The design was a cross-sectional study in 27 acromegaly patients compared with predicted models developed in 315 nonacromegaly subjects and to matched controls.

OUTCOME MEASURES

Mass of SM from whole-body MRI and lean tissue from DXA were measured.

RESULTS

SM mass did not differ from predicted or control values in active acromegaly: 31.75 +/- 8.6 kg (acromegaly) vs. 33.06 +/- 8.9 kg (predicted); SM was 95.6 +/- 12.8% of predicted (range 66.7-122%) (P = 0.088). Lean tissue mass (DXA) was higher in acromegaly than controls: 65.91 +/- 15.2 vs. 58.73 +/- 13.5 kg (P < 0.0001). The difference between lean tissue mass (DXA) and SM in acromegaly patients was higher than that in controls (P < 0.0001) consistent with an enlarged non-SM lean compartment in acromegaly. SM mass predicted by DXA correlated highly with SM mass by MRI (r = 0.97, P < 0.0001). SM (MRI) to SM (DXA predicted) ratio was 1.018 (range 0.896-1.159), indicating high agreement of these measures of SM.

CONCLUSIONS

SM mass in active acromegaly patients did not differ from predicted values. SM mass estimated from DXA agreed highly with SM by MRI, supporting the validity of the DXA model in assessing SM in acromegaly and other disorders of GH/IGF-I secretion.