Multiple types of skeletal muscle atrophy involve a common program of changes in gene expression

Skeletal muscle atrophy is a debilitating response to starvation and many systemic diseases including diabetes, cancer, and renal failure. We had proposed that a common set of transcriptional adaptations underlie the loss of muscle mass in these different states. To test this hypothesis, we used cDNA microarrays to compare the changes in content of specific mRNAs in muscles atrophying from different causes. We compared muscles from fasted mice, from rats with cancer cachexia, streptozotocin-induced diabetes mellitus, uremia induced by subtotal nephrectomy, and from pair-fed control rats. Although the content of >90% of mRNAs did not change, including those for the myofibrillar apparatus, we found a common set of genes (termed atrogins) that were induced or suppressed in muscles in these four catabolic states. Among the strongly induced genes were many involved in protein degradation, including polyubiquitins, Ub fusion proteins, the Ub ligases atrogin-1/MAFbx and MuRF-1, multiple but not all subunits of the 20S proteasome and its 19S regulator, and cathepsin L. Many genes required for ATP production and late steps in glycolysis were down-regulated, as were many transcripts for extracellular matrix proteins. Some genes not previously implicated in muscle atrophy were dramatically up-regulated (lipin, metallothionein, AMP deaminase, RNA helicase-related protein, TG interacting factor) and several growth-related mRNAs were down-regulated (P311, JUN, IGF-1-BP5). Thus, different types of muscle atrophy share a common transcriptional program that is activated in many systemic diseases.

Classification of spinal muscular atrophies

Clinical heterogeneity within the spinal muscular atrophies (SMA) has long been a source of confusion for questions of prognosis and genetic counselling. Comprehensive clinical and genetic analyses of 240 consecutive index cases from two English centres (The English SMA Study) have enabled some nosological questions to be resolved. The different SMA syndromes can be discriminated by (a) age at the first clinical signs of the disease, (b) pattern of muscle involvement, (c) age at death of other patients within an affected kindred, and (d) genetic evidence. Seven different SMA syndromes can be defined clinically and genetically; thirteen mutant genes are incriminated. Prevalence and incidence figures are presented. SMA type I (Werdnig-Hoffman disease) and chronic childhood SMA together comprise 74% of all SMA cases. The classification of the spinal muscular atrophies presented also provides the differential diagnosis for newly presenting cases.

The nosology of the spinal muscular atrophies

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The Scottish Motor Neuron Disease Register: a prospective study of adult onset motor neuron disease in Scotland. Methodology, demography and clinical features of incident cases in 1989

The Scottish Motor Neuron Disease Register (SMNDR) is a prospective, collaborative, population based study of motor neuron disease (MND) in Scotland. The register started in January 1989 with the aim of studying the clinical and epidemiological features of MND by prospectively identifying incident patients. It is based on a system of registration by recruitment from multiple sources, followed by the collection of complete clinical data and follow up, mainly through general practitioners. In this report the register's methodology and the demography and incidence data for the first year of study are presented. One hundred and fourteen newly diagnosed patients were identified in 1989 giving a crude incidence for Scotland of 2.24/100,000/year. Standardised incidence ratios showed a non-significant trend towards lower rates in north eastern regions and island areas.

Electromyographic findings in different forms of infantile and juvenile proximal spinal muscular atrophy

Quantitative electromyography (EMG) was performed in 223 infantile and juvenile cases of spinal muscular atrophy (SMA), which were classified into 3 groups: (A) form Ia, Werdnig-Hoffmann disease; (B) forms Ib and II, intermediate forms; and (C) form III, Kugelberg-Welander disease. The groups differed in the occurrence of spontaneous activity; only groups A and B showed spontaneous rhythmic firing of motor units, whereas in long-standing cases, pseudomyotonic volleys appeared. The parameters of individual motor unit potentials (MUPs) differed in the different forms of the disease. Group A showed, in addition to long potentials of high amplitude, some short and low amplitude potentials, and the histograms of amplitudes and durations were bimodal. In the long-standing cases, the values of these parameters were shifted to longer durations and higher amplitudes of motor unit potentials. However, in long-standing cases of the benign group C, the short, low potentials appeared as well as so-called linked potentials. In the very early stage of the disease, the children who were found to be suffering from chronic forms of SMA--both malignant (form Ib and II or benign group C)--had an EMG record that was slightly different from that of acute form Ia. Their EMG record shows more so-called "spinal" signs, particularly in the benign group C (Kugelberg-Welander disease). These increasing features of chronic anterior horn cell involvement followed a pattern of reinnervation and hypertrophy of muscle fibers. These phenomena were particularly seen in the benign group C. These findings indicate that in the early stage of SMA, the EMG not only has diagnostic, but also prognostic, value.

Post-operative rotator cuff integrity, based on Sugaya's classification, can reflect abduction muscle strength of the shoulder

PURPOSE

Magnetic resonance (MR) imaging is common in structural and qualitative assessment of the rotator cuff post-operatively. Rotator cuff integrity has been thought to be associated with clinical outcome. The purpose of this study was to evaluate the inter-observer reliability of cuff integrity (Sugaya's classification) and assess the correlation between Sugaya's classification and the clinical outcome. It was hypothesized that Sugaya's classification would show good reliability and good correlation with the clinical outcome.

METHODS

Post-operative MR images were taken two years post-operatively, following arthroscopic rotator cuff repair. For assessment of inter-rater reliability, all radiographic evaluations for the supraspinatus muscle were done by two orthopaedic surgeons and one radiologist. Rotator cuff integrity was classified into five categories, according to Sugaya's classification. Fatty infiltration was graded into four categories, based on the Fuchs' classification grading system. Muscle hypotrophy was graded as four grades, according to the scale proposed by Warner. The clinical outcome was assessed according to the constant scoring system pre-operatively and 2 years post-operatively.

RESULTS

Of the sixty-two consecutive patients with full-thickness rotator cuff tears, fifty-two patients were reviewed in this study. These subjects included twenty-three men and twenty-nine women, with an average age of fifty-seven years. In terms of the inter-rater reliability between orthopaedic surgeons, Sugaya's classification showed the highest agreement [ICC (2.1) = 0.82] for rotator cuff integrity. The grade of fatty infiltration and muscle atrophy demonstrated good agreement, respectively (0.722 and 0.758). With regard to the inter-rater reliability between orthopaedic surgeon and radiologist, Sugaya's classification showed good reliability [ICC (2.1) = 0.70]. On the other hand, fatty infiltration and muscle hypotrophy classifications demonstrated fair and moderate agreement [ICC (2.1) = 0.39 and 0.49]. Although no significant correlation was found between overall post-operative constant score and Sugaya's classification, Sugaya's classification indicated significant correlation with the muscle strength score.

CONCLUSIONS

Sugaya's classification showed repeatability and good agreement between the orthopaedist and radiologist, who are involved in the patient care for the rotator cuff tear. Common classification of rotator cuff integrity with good reliability will give appropriate information for clinicians to improve the patient care of the rotator cuff tear. This classification also would be helpful to predict the strength of arm abduction in the scapular plane.

LEVEL OF EVIDENCE

IV.

Shoulder impingement syndromes

OBJECTIVE

Not all shoulder pain conditions are a consequence of rotator cuff injuries secondary to anterior subacromial impingement. Additional causative forms have been identified and classified as posterosuperior glenoid rim, subcoracoid and suprascapular nerve (at spinoglenoid notch) impingement syndromes.

MATERIAL AND METHODS

We reviewed 206 consecutive magnetic resonance examinations carried out with conventional T1- and T2-weighted spin-echo and gradient-echo sequences in patients complaining of shoulder pain. Adjunctive sequences were acquired with the involved arm positioned in abduction and external rotation.

RESULTS

Anterior subacromial impingement is only one of the possible causes of shoulder disorders. Posterosuperior glenoid rim impingement is the most frequent cause of shoulder pain in young throwers. Subcoracoid and spinoglenoid notch suprascapular nerve impingement are additional forms that must be considered in the differential diagnosis because of their frequent occurrence in routine clinical practice.

CONCLUSION

Magnetic resonance imaging is the most useful diagnostic modality for shoulder disorders.

Nosology of juvenile muscular atrophy of distal upper extremity: from monomelic amyotrophy to Hirayama disease--Indian perspective

Since its original description by Keizo Hirayama in 1959, "juvenile muscular atrophy of the unilateral upper extremity" has been described under many nomenclatures from the east. Hirayama disease (HD), also interchangeably referred to as monomelic amyotrophy, has been more frequently recognised in the west only in the last two decades. HD presents in adolescence and young adulthood with insidious onset unilateral or bilateral asymmetric atrophy of hand and forearm with sparing of brachioradialis giving the characteristic appearance of oblique amyotrophy. Symmetrically bilateral disease has also been recognized. Believed to be a cervical flexion myelopathy, HD differs from motor neuron diseases because of its nonprogressive course and pathologic findings of chronic microcirculatory changes in the lower cervical cord. Electromyography shows features of acute and/or chronic denervation in C7, C8, and T1 myotomes in clinically affected limb and sometimes also in clinically unaffected contralateral limb. Dynamic forward displacement of dura in flexion causes asymmetric flattening of lower cervical cord. While dynamic contrast magnetic resonance imaging is diagnostic, routine study has high predictive value. There is a need to lump all the nomenclatures under the rubric of HD as prognosis in this condition is benign and prompt diagnosis is important to institute early collar therapy.

Patterns of abnormal histochemical fibre type differentitation in human muscle biopsies

The histochemical profile of individual human skeletal muscle fibres was analysed by correlating mitochondrial oxidative enzyme activity and that of myofibrillar ATPase at pH 9.5 and after pre-incubation at pH 4.3 and pH 4.6. In normal control muscle, only a small percentage of fibres did not conform to one or other of the normal variants of Type I and Type II fibres. In biopsies from early cases of Werdnig-Hoffmann disease, the denervated fibre populations contained many abnormal Type I and Type II fibres, including "IIc" fibres, but the basic distinction between Type I and Type II was preserved. However, in infantile spinal muscular atrophy patients aged two years and over, this distinction was progressively lost, leading to the total dedifferentiation of the atrophied fibres. In the Kugelberg-Welander form of spinal muscular atrophy, many of the constituent fibres of re-innervated groups displayed normal or near-normal histochemical profiles, but chronically denervated fibres became totally dedifferentiated. In Duchenne dystrophy, the spectrum of histochemical types appeared to be more continuous due to the emergence of fibres with properties intermediate between those of the normal variants, but the basic distinction between Type I and Type II fibres was preserved in the majority of cases. The percentage of severely abnormal fibres was higher in Type II than Type I and probably contributed to the observed decrease in the overall proportion of Type II fibres. Although very small atrophied fibres were observed in biopsies from cases of Becker and Duchenne dystrophy, these did not show the total dedifferentiation seen in the chronically denervated fibres in cases of spinal muscular atrophy.

Chronic proximal spinal muscular atrophy of childhood and adolescence: problems of classification and genetic counselling

Results obtained from a study of 354 cases of chronic proximal spinal muscular atrophy of childhood and adolescence suggest that the condition is not as homogeneous as it was previously thought. A tentative classification based on our results is proposed. Estimates of genetic risks are provided, taking into account the sex and age at clinical onset. In our opinion these factors are more reliable than the data hitherto available because they are based on a considerably larger series.

Unusual pedigree patterns in seven families with spinal muscular atrophy; further evidence for the allelic model hypothesis

Clinical and genetic findings are presented in 18 patients, from 7 pedigrees with different types of spinal muscular atrophy (SMA). The SMA diagnosis was based on EMG and muscle biopsy findings. All 7 pedigrees show an unusual genetic pattern, not consistent with simple autosomal recessive inheritance. Furthermore, in 6 of the 7 pedigrees different types of SMA were present within each pedigree. Our findings can be explained by an extension of a multiple alleles hypothesis originally described by Becker in 1964.

Hereditary motor sensory neuropathy type I presenting as scapuloperoneal atrophy (Davidenkow syndrome) electrophysiological and pathological studies

A 14 year old boy with scapuloperoneal muscular atrophy, pes cavus, areflexia and distal sensory loss (Davidenkow syndrome) is described. Nerve conduction velocities were diminished. Sural nerve biopsy demonstrated a reduction in the number of myelinated fibers and early "onion-bulb" formation. These observations support the hypothesis that the scapuloperoneal amyotrophy associated with distal sensory loss may represent a variant of type I hereditary motor sensory neuropathy.

[Neurogenic muscular atrophy and selective fibre type atrophies : Groundbreaking findings in the biopsy diagnosis of neuromuscular disease]

Neurogenic muscular atrophy (NMA) is the most frequent diagnosis obtained from reading a muscle biopsy. It is characterized by specific histological changes which distinguish NMA from other important muscle pathologies including the primary myopathies such as the muscular dystrophies as well as the inflammatory muscle disorders. Within the group of denervation atrophies, NMAs due to motor neuron diseases are associated with particular histological patterns. The diagnosis of NMA in muscle biopsies requires special methods, mainly enzyme and immunohistochemistry, but also resin histology and in some cases electron microscopy. Analysis of a combined muscle and sural nerve biopsy provides the opportunity to compare the extent of degeneration in the motor and sensory systems, respectively. Muscle fiber typing by enzyme and immunohistochemistry also leads to the detection of selective type 1 and type 2 muscle fiber atrophies which are relevant in the differential diagnosis of neuromuscular diseases.

The thenar index: an objective assessment and classification of thenar atrophy based on static hand imprints and clinical implications

BACKGROUND

The aims of this study were to test the effectiveness of the subjective clinical evaluation and to search for any possibility of constituting an objective assessment system for the diagnosis of thenar atrophy based on static hand imprints.

METHODS

Static hand imprints were obtained from normal subjects (group A, n = 116) and carpal tunnel syndrome patients with thenar atrophy (group B, n = 26). Thenar index and the bilateral thenar index ratio were defined. Cutoff values were considered by analyses with receiver operating characteristic curves.

RESULTS

No statistically significant difference could be demonstrated in thenar index values of dominant and nondominant hands between genders and age groups (p > 0.05). A statistically significant difference was observed between severity groups in group B (p < 0.05). There was a statistically significant difference between thenar index and bilateral thenar index ratio values of groups A and B (p < 0.05). Cutoff values were considered a thenar index of 31 and a bilateral thenar index ratio of 0.8, which revealed acceptable specificity (95.3 percent) and sensitivity (77.4 percent). A new quantitative classification for thenar atrophy severity is proposed.

CONCLUSIONS

Understanding the true onset and natural progression of thenar atrophy can only be anticipated with the aid of an objective assessment system. Currently, this method should be regarded as a system for patient records and comparison for presurgical and postsurgical data. The authors believe that the thenar index classification has some merit for future use. It seems that additional objective and scientific evaluation systems and novel approaches are still needed to demystify the true nature of carpal tunnel syndrome.

An unusual form of spinal muscular atrophy with mental retardation occurring in an inbred population

Three sibs are described suffering from hereditary non-progressive spinal muscular atrophy with non-progressive mental retardation. One of them had in addition signs of pyramidal tract involvement. Muscular weakness was more pronounced proximally than distally and the neck muscles were severely involved. Th.ey all had small skulls and several associated congenital malformations were observed including syndactyly of the left hand in 1 patient. The patients belong to a small inbred community in the Netherlands. Erythropoietic protoporphyria was also present in the family but segregated independently. This combination of "congenital" mental retardation with "congenital" non-progressive spinal muscular atrophy is believed to represent a new syndrome, caused by a rare recessive gene.

Clinical study of proximal spinal muscular atrophy. Report on 89 cases

A report on 89 cases of proximal Spinal Muscular Atrophy with observations on the clinical features, criteria of classification and modes of inheritance. The various forms into which SMA is divided probably represent a single disease that may begin at any age and may vary in severity, due, as a rule, to an autosomal recessive gene.

Multiple types of skeletal muscle atrophy involve a common program of changes in gene expression

Skeletal muscle atrophy is a debilitating response to starvation and many systemic diseases including diabetes, cancer, and renal failure. We had proposed that a common set of transcriptional adaptations underlie the loss of muscle mass in these different states. To test this hypothesis, we used cDNA microarrays to compare the changes in content of specific mRNAs in muscles atrophying from different causes. We compared muscles from fasted mice, from rats with cancer cachexia, streptozotocin-induced diabetes mellitus, uremia induced by subtotal nephrectomy, and from pair-fed control rats. Although the content of >90% of mRNAs did not change, including those for the myofibrillar apparatus, we found a common set of genes (termed atrogins) that were induced or suppressed in muscles in these four catabolic states. Among the strongly induced genes were many involved in protein degradation, including polyubiquitins, Ub fusion proteins, the Ub ligases atrogin-1/MAFbx and MuRF-1, multiple but not all subunits of the 20S proteasome and its 19S regulator, and cathepsin L. Many genes required for ATP production and late steps in glycolysis were down-regulated, as were many transcripts for extracellular matrix proteins. Some genes not previously implicated in muscle atrophy were dramatically up-regulated (lipin, metallothionein, AMP deaminase, RNA helicase-related protein, TG interacting factor) and several growth-related mRNAs were down-regulated (P311, JUN, IGF-1-BP5). Thus, different types of muscle atrophy share a common transcriptional program that is activated in many systemic diseases.

[Diabetic neuropathy. I). Peripheral neuropathy]

This is the first of a series of reports on diabetic neuropathy. Peripheral or somatic diabetic neuropathy is discussed with reference to its major symptoms: central, peripheral and amyotrophic mononeuropathies, symmetrical and asymmetrical polyneuropathies, peripheral arthropathy and finally diabetic cachexia. The various theories on the pathogenesis of peripheral neuropathy are presented. Finally data on 173 type I and II diabetics are presented. These patients, treated in outpatients departments, were paired by sex, weight and age with an equal number of non-diabetic subjects. The results of the survey largely confirm report in the literature. The importance of continuous medical surveillance for the identification and hence prevention of diabetic neuropathy is emphasized. This is particularly necessary since we have still much to learn about the natural history of the disease and for the moment the therapeutic approaches to the various neuropathies concerned are both tentative and symptomatic.