Sarcopenia and Muscular Dystrophies

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Questions and Answers

What does the term 'penia' refer to in medical terminology?

A type of genetic disorder

An increase in cell count

A lack of something (correct)

A disease characterized by excess

Which statement accurately describes sarcopenia?

It solely involves a decrease in muscle quantity.

It leads to improved muscle strength over time.

It is primarily a muscle disease that affects quality and quantity. (correct)

It is a normal part of the aging process.

What is one primary public health concern associated with sarcopenia?

Increased muscle strength among the elderly

Decreased risk of falls and fractures

Improvement in cognitive function

Higher healthcare costs and hospitalizations (correct)

How does sarcopenia affect daily living activities?

It limits daily living activities leading to a loss of independence. Signup and view all the answers

What is the estimated prevalence range of sarcopenia in community-dwelling populations?

1-30% Signup and view all the answers

Which demographic shows a higher prevalence of sarcopenia according to settings?

Individuals in acute hospital care and long-term care Signup and view all the answers

Sarcopenia has associations with which of the following health issues?

Mobility disorders and cognitive deficits Signup and view all the answers

Which threshold is important for the screening of force loss related to grip strength?

Statistical cut-offs based on birth cohorts Signup and view all the answers

What best defines sarcopenia?

The age-related loss of muscle mass and strength Signup and view all the answers

Which of the following laboratory findings is commonly associated with sarcopenia?

Decreased serum albumin levels Signup and view all the answers

What is a recognized treatment strategy for managing sarcopenia?

Resistance training exercises Signup and view all the answers

What is the primary cause of Duchenne muscular dystrophy (DMD)?

Dystrophin gene mutation Signup and view all the answers

Which pathomechanism is primarily disrupted in DMD?

Cell membrane integrity Signup and view all the answers

How does physical exercise influence the progression of DMD?

It preserves muscle function and slows degradation Signup and view all the answers

What best explains the relationship between cell mechanics and excitability in DMD?

Altered membrane stiffness affects action potentials Signup and view all the answers

Which of the following statements about risk factors for sarcopenia is accurate?

Sedentary lifestyle is a major risk factor Signup and view all the answers

What is one of the primary benefits of physical activity with respect to sarcopenia?

It prevents the onset of sarcopenia. Signup and view all the answers

Which type of muscular dystrophy is specifically associated with proximal muscles of the shoulder and hip?

Limb girdle muscular dystrophy (LGMD) Signup and view all the answers

Which of the following options represents a protein or enzyme associated with certain types of muscular dystrophies?

Sarcomeric proteins Signup and view all the answers

What is a common consequence of muscular dystrophies?

Replacement of muscle by connective and fat tissue Signup and view all the answers

What is the incidence rate of Duchenne muscular dystrophy (DMD) among male births?

1/3500 Signup and view all the answers

Which of the following types of muscular dystrophy is characterized by symptoms affecting the eyes and brain?

Muscle, eye, brain (MEB) dystrophy Signup and view all the answers

Which of the following is NOT a characteristic feature of Duchenne muscular dystrophy?

Normal muscle strength into adulthood Signup and view all the answers

What term describes the common recommendation related to preventive measures for sarcopenia?

Physical activity Signup and view all the answers

What is the function of dystrophin in muscle cells?

Binds actin and structural proteins Signup and view all the answers

Which type of muscular dystrophy involves progressive weakness primarily affecting males?

Duchenne muscular dystrophy (DMD) Signup and view all the answers

What causes the pathology associated with Duchenne muscular dystrophy?

Mutations in the dystrophin gene Signup and view all the answers

What is a common fate for individuals with Duchenne muscular dystrophy by age 30?

Early death from respiratory complications Signup and view all the answers

Which type of muscular dystrophy is known to start in adolescence and results in milder symptoms than Duchenne muscular dystrophy?

Becker muscular dystrophy (BMD) Signup and view all the answers

Which characteristic is associated with Becker muscular dystrophy compared to Duchenne muscular dystrophy?

Longer dystrophin with reduced function Signup and view all the answers

Which protein is crucial for the structural integrity provided by dystrophin?

Actin Signup and view all the answers

In Duchenne muscular dystrophy, what can advanced structural microscopy reveal about muscle fibers?

Disruptions and split fibers Signup and view all the answers

What does the SARC-F screening tool primarily evaluate in relation to sarcopenia?

Severity of sarcopenia cases Signup and view all the answers

Which of the following tests is NOT included in the objective criteria for assessing sarcopenia?

Blood pressure measurement Signup and view all the answers

What characteristic is associated with primary sarcopenia?

Age-related muscle loss Signup and view all the answers

Which imaging technique is mentioned for assessing muscle quantity in sarcopenia?

Magnetic resonance imaging (MRI) Signup and view all the answers

What is a common difficulty encountered with the SARC-F screening tool?

Low sensitivity for detecting severe cases Signup and view all the answers

Which of the following is considered a type of secondary sarcopenia?

Muscle loss related to inactivity Signup and view all the answers

Which method is currently under evaluation as a serum biomarker in the context of sarcopenia?

Inflammation levels Signup and view all the answers

What change occurs in muscle fibers due to aging, as identified in sarcopenia?

Loosely packed muscle fibers Signup and view all the answers

Study Notes

Sarcopenia

Definition derived from Greek: "sarx" meaning flesh, "penia" meaning lack; indicates a muscle disease rather than a normal part of aging.
Low muscle mass leads to decreased muscle strength; critical for earlier diagnosis and predicting adverse outcomes.
A progressive disease characterized by declines in both muscle quantity and quality.
Prevalence varies: 1-30% in the community; over 10% in acute hospital and long-term care settings.
Associated risks include higher likelihood of falls, fractures, mobility issues, and cognitive deficits, impacting quality of life and independence.
Healthcare costs increasing, especially during hospitalization for sarcopenic patients; costs can be double compared to non-sarcopenic patients.

Sarcopenia Assessment Tools

SARC-F Screening Tool: evaluated in three large populations with low to moderate sensitivity but high specificity; detects severe cases reliably.
Objective Criteria:
- Muscle strength assessed by grip strength and chair stand tests.
- Muscle quantity determined through imaging techniques like MRI, CT, and DXA.
- Physical performance measured using gait speed and balance tests.

Subtypes of Sarcopenia

Distinction between primary (age-related) and secondary forms (due to inflammation, cancer, inactivity, or poor nutrition).
Time course can be acute or progressive, with age-related changes in muscle fiber composition.

Role of Physical Activity

Physical activity is a recommended preventive measure against sarcopenia, with various types yielding similar beneficial effects.

Muscular Dystrophies

Characterized by hereditary and progressive muscle necrosis, leading to muscle tissue replacement by fat and connective tissues.
Notable examples include Limb Girdle Muscular Dystrophy (LGMD), Duchenne Muscular Dystrophy (DMD), and Becker Muscular Dystrophy (BMD).
Dystrophies are associated with defects in either sarcolemmal or sarcomeric/nuclear proteins.

Duchenne Muscular Dystrophy (DMD)

An X-linked recessive disease with a frequency of 1 in 3,500 male births; approximately one-third of cases arise from spontaneous mutations.
Initial symptoms develop between ages 2-6, including waddling gait, Gower's sign, and calf pseudohypertrophy due to fatty degeneration.
DMD progression impacts cardiac function and leads to respiratory complications; life expectancy is usually below 30 years.

DMD Pathology

Involves the dystrophin protein (427 kDa), which is crucial for muscle cell integrity; its mutations result in non-functional variants that disrupt muscle function.
Dystrophin is part of a complex that links the cytoskeleton to the extracellular matrix via proteins like dystroglycan and syntrophin.

Cellular and Mechanical Changes in DMD

Advanced microscopy reveals structural disruptions in myofibrils and progressive fiber splitting, affecting muscle contractions.
Changes in calcium (Ca2+) currents contribute to increased cell excitability; studies using mdx mouse models aid in understanding these alterations.

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Description

Explore the intricacies of sarcopenia and muscular dystrophies in this detailed quiz. The material discusses the causes, effects, and management of these conditions. Test your understanding of how they impact muscle health and function.