Angulated Fibers Research Articles

Direction-oriented fiber guiding with a tunable tri-layer-3D scaffold for periodontal regeneration.

Multilayered scaffolds mimicking mechanical and biological host tissue architectures are the current prerequisites for successful tissue regeneration. We propose our tunable tri-layered scaffold, designed to represent the native periodontium for potential regenerative applications. The fused deposition modeling platform is used to fabricate the novel movable three-layered polylactic acid scaffold mimicking in vivo cementum, periodontal ligament, and alveolar bone layers. The scaffold is further provided with multiple angulated fibers, offering directional guidance and facilitating the anchorage dependence on cell adhesion. Additionally, surface modifications of the scaffold were made by incorporating coatings like collagen and different concentrations of gelatin methacryloyl to enrich the cell adhesion and proliferation. The surface characterization of our designed scaffolds was performed using tribological studies, atomic force microscopy, contact angle measurement, scanning electron microscopy, and micro-computed tomography. Furthermore, the material characterization of this scaffold was investigated by attenuated total reflectance-Fourier transformed infrared spectroscopy. The scaffold's mechanical characterization, such as strength and compression modulus, was demonstrated by compression testing. The L929 mouse fibroblast cells and MG63 human osteosarcoma cells have been cultured on the scaffold. The scaffold's superior biocompatibility was evaluated using fluorescence dye with fluorescence microscopy, scanning electron microscopy, in vitro wound healing assay, MTT assay, and flow cytometry. The mineralization capability of the scaffolds was also studied. In conclusion, our study demonstrated the construction of a multilayered movable scaffold, which is highly biocompatible and most suitable for various downstream applications such as periodontium and in situ tissue regeneration of complex, multilayered tissues.

Diffuse reflectance spectroscopy of the spine: improved breach detection with angulated fibers.

Accuracy in spinal fusion varies greatly depending on the experience of the physician. Real-time tissue feedback with diffuse reflectance spectroscopy has been shown to provide cortical breach detection using a conventional probe with two parallel fibers. In this study, Monte Carlo simulations and optical phantom experiments were conducted to investigate how angulation of the emitting fiber affects the probed volume to allow for the detection of acute breaches. Difference in intensity magnitude between cancellous and cortical spectra increased with the fiber angle, suggesting that outward angulated fibers are beneficial in acute breach scenarios. Proximity to the cortical bone could be detected best with fibers angulated at for impending breaches between and . An orthopedic surgical device comprising a third fiber perpendicular to the device axis could thus cover the full impending breach range from to .

Alterations in Autophagy and Mammalian Target of Rapamycin (mTOR) Pathways Mediate Sarcopenia in Patients with Cirrhosis

The pathophysiology of sarcopenia in cirrhosis is poorly understood. We aimed to evaluate the histological alterations in the muscle tissue of patients with cirrhosis and sarcopenia, and identify the regulators of muscle homeostasis. Computed tomography images at third lumbar vertebral level were used to assess skeletal muscle index (SMI) in 180 patients. Sarcopenia was diagnosed based on the SMI cut-offs from a population of similar ethnicity. Muscle biopsy was obtained from the vastus lateralis in 10 sarcopenic patients with cirrhosis, and the external oblique in five controls (voluntary kidney donors during nephrectomy). Histological changes were assessed by hematoxylin and eosin staining and immunohistochemistry for phospho-FOXO3, phospho-AKT, phospho-mTOR, and apoptosis markers (annexin V and caspase 3). The messenger ribonucleic acid (mRNA) expressions for MSTN, FoxO3, markers of ubiquitin-proteasome pathway (FBXO32, TRIM63), and markers of autophagy (Beclin-1 and LC3) were also quantified. The prevalence of sarcopenia was 14.4%. Muscle histology in sarcopenics showed atrophic angulated fibers (P= 0.002) compared to controls. Immunohistochemistry showed a significant loss of expression of phospho-mTOR (P= 0.026) and an unaltered phospho-AKT (P= 0.089) in sarcopenic patients. There were no differences in the immunostaining for annexin-V, caspase-3, and phospho-FoxO3 between the two groups. The mRNA expressions of MSTN and Beclin-1 were higher in sarcopenics (P= 0.04 and P= 0.04, respectively). The two groups did not differ in the mRNA levels for TRIM63, FBXO32, and LC3. Significant muscle atrophy, increase in autophagy, MSTN gene expression, and an impaired mTOR signaling were seen in patients with sarcopenia and cirrhosis.

A Comparative Histological and Immunohistochemical Study of the Effect of Oxandrolone and Whey Protein on Disuse Induced Muscle Atrophy in old aged male rats

Background: Periods of immobilization are often associated with pathologies and/or aging. These periods of disuse muscle atrophy could worsen the pathology or elderly frailty. Exercise, the best way to recover muscle mass, is not always applicable. Aim of Work: This study aimed to compare the therapeutic effect of oxandrolone versus whey protein on disuse induced muscle atrophy in old aged male rats with low testosterone level and mobility limitation.Materials and Methods: Twenty four aged male albino rats were included: 6 rats as control (group I). Eighteen rats were subjected to hind limb suspension (HLS) for 2 weeks then were divided into: 6 rats as group II (disuse atrophy) and 12 rats as group III (treated group) which was equally subdivided into: group IIIa (oxandrolone treated) and IIIb (whey protein treated) where oxandrolone 1.23 mg/kg and whey protein 9.25 gm/kg were given orally daily for 4 weeks. Rats were sacrificed after 6 weeks. Gastrocnemius muscle weight and total protein content were measured. Muscle specimens were stained with Hematoxylin and Eosin, PAS and immunohistochemical staining for Myogenin. Morphometric measurements of type I and type II fibers number and cross sectional area (CSA), number of myogenin positive cells (differentiated satellite cells) were taken and statistically analyzed. Results: Group II showed atrophic angulated muscle fibers and significant increase in type II fibers compared to the control. Subgroup IIIa showed muscle fibers with large diameter. Many rounded vesicular nuclei were observed among muscle fibers. A significant increase in type I fibers and number of myogenin positive cells as compared to the control and subgroup IIIb. Conclusion: Oxandrolone and whey protein treated subgroups showed improved muscle mass, CSA, total protein content, histological architecture of muscle fibers and increase of satellite cells number. However, oxandrolone showed better therapeutic potential in ameliorating disuse muscle atrophy.

Reconstruction of white matter fibre tracts using diffusion kurtosis tensor imaging at 1.5T: Pre-surgical planning in patients with gliomas

Tractography studies for pre-surgical planning of primary brain tumors is typically done using diffusion tensor imaging (DTI), which cannot resolve crossing, kissing or highly angulated fibres. Tractography based on the estimation of the diffusion kurtosis (DK) tensor was recently demonstrated to enable tackling these limitations. However, its use in the clinical context at low 1.5T field has not yet been reported. PurposeTo evaluate if the estimation of whole-brain tractography using the DK tensor is feasible for pre-surgical investigation of patients with brain tumors at 1.5T. MethodsEight healthy subjects and 3 patients with brain tumors were scanned at 1.5T using a 12-channel head coil. Diffusion-weighted images were acquired with repetition/echo times of 5800/107 ms, 82 × 82 resolution, 3 × 3 × 3 mm3 voxel size, b-values of 0, 1000, 2000 s/mm2 and 64 gradient sensitising directions. Whole-brain tractography was estimated using the DK tensor and corticospinal tracts (CST) were isolated using regions-of-interest placed at the cerebral peduncles and motor gyrus. Tract size, DK metrics and CST deviation index (highest curvature point) were compared between healthy subjects and patients. ResultsTract sizes did not differ between groups. The CST deviation index was significantly higher in patients compared to healthy subjects. Fractional anisotropy was significantly lower in patients, with higher mean kurtosis asymmetry index at the highest curvature point in patients. ConclusionsCorticospinal fibre bundles estimated using DK tensor in a 1.5T scanner presented similar properties in patients with brain gliomas as those reported in the literature using DTI-based tractography.

G.P.129 Changes of anti-dysferlin immunoreactivity in neurogenic muscle damage

<h2>Abstract</h2> Dysferlin is considered a calcium-regulated fusogen with a major role in skeletal muscle membrane repair and possibly further functions. Absence or severe reduction of anti-dysferlin immunoreactivity from its apparent (sub) sarcolemmal position is typical for disorders caused by mutations in the respective <i>DYSF</i> gene. Less dramatic reductions have been described for diseases arising from mutations in the genes encoding calpain 3 and caveolin 3. However, in the 300+ samples stained since we included anti-dysferlin in our immunohistochemistry (IHC) work-up, the most common cause for reduced sarcolemmal reactivity seems to be neurogenic damage. In particular atrophic fibres show a marked reduction in this location, frequently associated with an increase in sarcoplasmic (i.e. in the cross section) foci of reactivity. In comparison with atrophic fibres from different pathophysiologies, this change appears almost characteristic for neurogenic damage, like small dark angulated fibres or the orange hue these fibres show in the myophosphorylase enzyme histochemistry. A likely explanation for part of this phenomenon is the known increase of sarcotubular profiles (T tubules and sarcoplasmic reticulum), that dysferlin is also associated with, per cross section in denervation atrophy. This is supported by partial co-localisation with anti-ryanodine receptor (RyR) reactivity. Intense and dense immunoreactivity with both anti-dysferlin and anti-RyR is further found in the intermediate zone of target fibres. While anti-caveolin 3 immunoreactivity is found to be strong on all fibres in neurogenic damage, a reduction of calpain 3 mRNA has been reported (in mice), but correlation with IHC is prevented by the protein's rapid turn-over. Changes of dysferlin immunoreactivity in denervated muscle should be considered in diagnostics as well as dysferlin research, particularly whenever models like tissue culture or single fibres that include denervation/non-innervation are used.

Late onset centronuclear myopathy with severe atrophy in an adult Labrador retriever

A three-year-old male Labrador retriever was presented with five-month history of tetraparesis with severe atrophy in the limbs. Prior to this five-month period, the dog had been healthy. At gross necropsy several muscles were atrophic reflecting decreased muscle mass. Histologically, there were atrophic type I and type II fibres, angulated type IIC fibres and an elevated oxidative activity that showed an altered mitochondrial pattern. The rapid progression of the clinical signs and the age at onset could suggest an atypical myopahty in this dog breed.

Neuronal NOS is dislocated during muscle atrophy in amyotrophic lateral sclerosis

Previously, we demonstrated that neuronal nitric oxide synthase (nNOS) is activated and promotes muscle atrophy in skeletal muscle during tail suspension, a model of unloading and denervation. Here, we examined patients with amyotrophic lateral sclerosis (ALS) and mutant (H46R) SOD1 transgenic (Tg) mice model using immunohistochemistry, Western blotting and real time PCR. We found cytoplasmic nNOS staining of angulated muscle fibers in patients with ALS. We also examined mutant SOD1 Tg mice and found cytoplasmic nNOS staining even before the onset of clinical muscle atrophy. In the Tg mice, nNOS was largely extracted with 100 mM NaCl and barely detected in the pellet fraction, suggesting fragile anchoring of nNOS to the sarcolemma. We also showed an elevated expression of atrogin-1, key molecules in muscle atrophy at the end stage. A common nNOS dislocation/atrogin-1/muscle atrophy pathway among tail suspension, denervation and ALS is suggested. nNOS modulation therapy may be beneficial in several types of muscle atrophy.

Histochemical pattern of gastrocnemius muscle in fluoride toxicity syndrome

Objective To evaluate the effect of sodium fluoride (NaF) on cytochemical distribution of proteins, DNA, and RNA in the gastrocnemius muscle of rat in experimental fluorosis. Methods Young Sprague Dawley albino rats were administered with NaF at 30, 45, and 75 mg/kg bw/day subcutaneously for 15 and 30 days, respectively. The control animals were given the vehicle (1cc deionized double distilled water/kg bw/day). Results In the first phase of 15 days experimentation, the gastrocnemius muscle of rats intoxicated with NaF at 30, 45, and 75 mg/kg bw/day showed decline in proteins including α amino acids as compared to control. In the second phase of 30 days experimentation, the muscle fibers of rat showed elevation in sarcolemmal and sarcoplasmic proteins in 30 mg NaF dose group, and angulated fibers exhibited increase in sarcolemmal proteins in 45 mg NaF group. The marginal regions of angular and rim fibers showed deeply stained rings of sarcoplasmic proteins whereas the split fibers were faintly stained in rats treated with NaF at 75 mg/kg bw/day for 30 days. In rats treated with NaF at 30 mg/kg bw/day for 15 days, the hypertrophied peripheral muscle fibers contained more DNA, however the atrophied fibers had more RNA. In 45 mg NaF group, RNA was located in sarcolemmal regions, while DNA content decreased as compared to control. In 75 mg NaF group, the muscle fibers had dark and light staining regions of DNA and RNA. In the 30 days of experimentation, the DNA level decreased whereas RNA content increased in the gastrocnemius muscle fibers of the rat treated with NaF at 30 mg/kg bw/day. In treatment group with NaF at 45 mg/kg bw/day, the RNA content slightly declined in comparison to control, in all treatments for 15 days as well as in treatment group with NaF at 30 mg/kg bw/day for 30 days whereas the amount of DNA slightly increased as compared to treatment group with NaF at 75 mg/kg bw/day for 15 days. The highest dose group revealed elevated amount of RNA whereas DNA content remained stable. Conclusions The findings of present study demonstrate that certain concentrations of fluoride can induce muscle lesions and damage DNA, RNA, and protein in muscle cells and excessive intake and accumulation of fluoride is therefore a serious risk factor for muscular abnormalities in fluorosis.

Type 2 Myotonic Dystrophy Can Be Predicted by the Combination of Type 2 Muscle Fiber Central Nucleation and Scattered Atrophy

The diagnosis of Type 2 myotonic dystrophy (DM2/proximal myotonic myopathy) is often overlooked because of a nonspecific clinical presentation and muscle biopsy findings of a "denervation-like" pattern of unknown specificity that combines increased fiber size variation, central nucleation, small angulated fibers, Type 2 fiber atrophy, and nuclear clumps. We determined the presence of these features in 104 patients designated as having an unidentified myopathy from a series of 2,100 muscle biopsies. Because CCUG expansions form pathogenic ribonuclear accumulations that can be detected by in situ hybridization, we validated and then used automated (CCUG)8 in situ hybridization as a reference standard to evaluate the value of each histologic feature for DM2 detection, identifying 8 DM2-positive and 96 DM2-negative cases. Multivariate analyses identified the combination of Type 2 fiber atrophy and central nucleation as the most predictive of DM2 (sensitivity, 1.0; specificity, 0.92). These features were mutually exclusive in non-DM2 patients (p < 0.0001). The relevance of this combination of features was confirmed in an additional independent series (15 DM2-positive vs 17 DM2-negative). Further investigation revealed that central nucleation selectively affects Type 2 fibers in DM2 and, conversely, that it affects Type 1 fibers in DM1 (p < 0.0001). These results will facilitate the routine detection of DM2 and further support the concept that DM2 has a distinct pathophysiology involving type 2 myofibers.

Neuromuscular Features in the Camera-Marugo-Cohen Syndrome

We describe the case of a 24-year-old Japanese man suffering from obesity, mental retardation, muscle weakness, camptodactyly, syndactyly, and a urinary tract cleft. His muscle weakness, which was slightly distally dominant in the extremities, was almost static and showed slow progression for several years. He had normal blood chromosomes (46, XY) and showed normal levels of sex hormones. A needle electromyographic examination of the upper- and lower-limb muscles revealed a reinnervation pattern with large-amplitude, long-duration motor unit potentials. A muscle biopsy also showed denervation and reinnervation patterns, with small-group atrophy and type grouping, with numerous small, angulated fibers. Our findings suggest that these neuromuscular features of the Camera-Marugo-Cohen syndrome are caused by neurogenic changes rather than myogenic changes.

Muscle histopathology in upper motor neuron-dominant amyotrophic lateral sclerosis

The distinction between primary lateral sclerosis (PLS) and amyotrophic lateral sclerosis (ALS) still remains debated. Recently, PLS patients displaying lower motor neuron (LMN) signs have been defined as 'upper motor neuron (UMN)-dominant ALS', using 'clinically pure PLS' diagnosis to those with no LMN signs. To further characterize the LMN involvement in UMN-dominant ALS we investigated the presence and the extent of neurogenic abnormalities in the skeletal muscle of patients affected with a pyramidal syndrome consistent with UMN-dominant ALS. A total of nine patients affected with UMN-dominant ALS were analysed. In all cases, muscle biopsies showed the presence of scattered or clustered atrophic angulated fibres in small groups, and a mild to moderate fibre type-grouping. Target and targetoid fibres were detected in two cases only. Three patients had a second muscle biopsy which demonstrated a roughly unchanged pattern of chronic denervation with still moderate reinnervation phenomena. This study suggests that in UMN-dominant ALS muscle denervation may be characterized by an early chronic impairment of a restricted number of LMNs. The extent rather than the presence of LMN signs may allow to categorize patients with motor neuron disease involving mainly UMN into distinct entities.

Novel C59T leader peptide mutation in the MPZ gene associated with late‐onset, axonal, sensorimotor polyneuropathy

The objective of this study was to report a novel exon-1 mutation in the myelin protein zero (MPZ) gene, resulting in axonal Charcot-Marie-Tooth neuropathy with recurrent hyper-CK-emia. In a 64-year-old woman slowly progressive distal lower limb weakness, muscle cramps in the lower limb muscles, and stocking-type numbness had developed from the age of 61. Neurologic examination revealed discrete hip flexor weakness, weakness for foot extension, diffuse wasting of the distal lower limb muscles, reduced patella tendon reflexes, and absent Achilles tendon reflexes. There was recurrently elevated creatine kinase with a maximum of 607 U/l (n, <145 U/l). Stimulation of the peroneal and tibial nerves did not evoke a muscular response. Electromyography was neurogenic. Biopsy of the right sural nerve showed diffuse axonal degeneration and loss of axons of all diameters. Muscle biopsy showed increased fiber-size variability, angulated fibers, internalized nuclei, accumulations of nuclei, grouped atrophic muscle fibers, and fiber splitting. Molecular genetic analysis by PCR and direct nucleotide sequencing revealed the heterozygous C59T exon-1 MPZ gene mutation, resulting in the amino acid exchange S20F of the MPZ signal protein domain (leader peptide). The novel C59T mutation in the leader peptide of the MPZ gene is pathogenic and manifests as severe, late-onset, axonal, symmetric sensorimotor polyneuropathy (CMT2) and hyper-CK-emia.

Oculopharyngeal muscular dystrophy with PABPN1 mutation in a Chinese Malaysian woman

Oculopharyngeal muscular dystrophy (OPMD) is an autosomal dominant disorder of middle age presenting as progressive dysphagia and eyelid ptosis, due to short expansions of the GCG trinucleotide repeat (from GCG 6 to GCG 8–13) in the polyadenylate binding-protein nuclear 1 (PABPN1) gene. OPMD is rarely seen in Asians and morphologically and/or genetically confirmed cases have been reported in Japanese kindreds only. We report a 64 year old Chinese–Malaysian woman who presented with progressive dysphagia and bilateral ptosis for about 6 years. Her mother and elder brother (both deceased) were believed to be affected. Muscle histopathology revealed angulated fibres with rimmed vacuoles. Genetic analysis showed repeat expansion in one allele to (GCG) 9 while normal in the other (GCG) 6. This is the first non-Japanese Asian family with genetically confirmed OPMD.

Poster 4: Histopathologic Evaluation of the Levator Ani Muscle in Squirrel Monkeys With/Without Pelvic Relaxation

OBJECTIVES: The value of an animal model is determined by the extent that disease conditions mimic those in humans. The purposes of this study were to evaluate histologic signs of myogenic and neurogenic changes in the levator ani (LA) muscle in the squirrel monkey model of pelvic organ prolapse (POP) and to compare findings with previous studies in women. METHODS: The LA (pubocaudalis and iliocaudalis) muscles were collected from 9 squirrel monkeys aged 4–25 years (n=4 parous females with POP/anterior defect, n=4 nulliparous females without POP, n=one parous female without POP) and processed for histology and immunofluorescence. Serial sections were stained with hematoxylin and eosin, Masson trichrome, and elastin stains. Fiber typing was performed with the use of antifast (type II) and antislow (type I) skeletal myosin antibodies or ATPase histochemistry, and apoptotic nuclei were examined by the TUNEL (dUTP nick-end labeling) assay. Histologic signs for myogenic changes included fibrosis, variation in fiber diameter (defined as standard deviation ≥30% of mean minimum diameter), and centralization of nuclei, whereas signs for neurogenic changes included small angulated fibers and fiber type grouping. RESULTS: The pubocaudalis muscle had a greater percentage of type I fibers compared with the iliocaudalis (39% = pubocaudalis, 28% = iliocaudalis, P<0.001, paired t test). Heit et al reported 66% type I fibers in the pubococcygeus muscle of women. Percentages of type II and I fibers were not altered with POP/parity status or age. Compared with young (4 yr) nulliparous animals, myocyte diameter (in pubocaudalis and iliocaudalis) and LA wet weight were not decreased in animals with POP, but were decreased in an elderly (>20 yr) nulliparous animal. Myogenic changes, including endomysial connective tissue or fibrosis (P=0.048, Fisher exact test), variation in fiber diameter (P=0.018, Fisher exact test), and centralization of nuclei (P=0.013, t test) increased with age regardless of POP/parity status. These changes were more pronounced in the pubocaudalis than the iliocaudalis. Neurogenic changes indicative of denervation without reinnervation (small angulated fibers) and denervation with reinnervation (fiber grouping) were observed in one parous animal that did not have POP. Very few apoptotic myonuclei were detected in any animal. CONCLUSIONS: Myogenic and neurogenic changes similar to those seen in women occur in the squirrel monkey LA muscle and are associated with aging and/or parity. Myogenic changes are most likely a consequence of mechanical stress to this muscle induced by supporting the pelvic organs against gravity, as well as pregnancy and parturition. The neurogenic changes observed in one parous female provide histologic evidence that the squirrel monkey experiences LA denervation injury likely caused by vaginal delivery. Investigation of additional age- and parity-matched animals without POP will help differentiate the effects of POP, parity, and aging on the LA muscle.

Is the histomorphological concept of the female pelvic floor and its changes due to age and vaginal delivery correct?

To compare the histomorphology of pelvic floor specimens of 94 female cadavers, ten male cadavers, and 24 female symptomatic patients who underwent pelvic floor surgery, and to evaluate the association of age, parity, and sex to myogenic and/or neurogenic changes to the levator ani muscle (LAM). The pelvic floor was biopsied at the pubococcygeus, the iliococcygeus and the coccygeus muscle. After staining, signs for myogenic/neurogenic changes to the muscle were evaluated (fibrosis, variation in fiber diameter, centralization of nuclei, small angulated fibers, and type grouping). To identify the intact neuromuscular junction stainings with NCAM (neuronal cell adhesion molecule) and acetylcholinesterase (ACE) were used. A significant influence of age and parity on the histomorphological criteria of myogenic cell-damage was shown in this study. Although these criteria were found even in young nulliparous women, there was a significant increase in older or parous women with at least one vaginal delivery. We failed to demonstrate significant changes between the nulliparous LAM, the male LAM, and the LAM from women with prolapse and incontinence. None of the specimen showed any obvious evidence of neuropathy. We have evaluated histological criteria adapted from the examination of limb muscles in the LAM of nulliparous young women. "Myogenic changes" seem to be a normal finding in the LAM. The increase of these changes with aging and parity points to mechanical stress to the LAM as the most plausible causative factor. We propose that further studies using histomorphological techniques of the pelvic floor muscle in nulliparous and parous women should clarify the potential role of our histological findings.

Hand muscle pathology after long-term vibration exposure.

The morphology of the abductor pollicis brevis muscle was studied in 20 patients suffering from hand-arm vibration syndrome. The main morphological changes observed were centrally located myonuclei and fibre type grouping (found in all 20 muscle biopsies), angulated muscle fibres (found in 19 biopsies), ring fibres and regenerating fibres (found in 18 biopsies) and fibrosis (found in 17 biopsies). The observed abnormalities are believed to reflect damage to both the muscle fibres and the motor nerve. The changes were related to different vibration exposure parameters. The number of fibres demonstrating centrally located nuclei correlated significantly with the cumulative vibration exposure, while the number of angulated fibres correlated significantly with the total vibration exposure time. This indicates that the vibrating tools may cause direct damage to muscle fibres as well as nerves.

Muscle pathology in 57 patients with myotonic dystrophy type 2.

We evaluated muscle biopsies from 57 patients with genetically confirmed myotonic dystrophy type 2/proximal myotonic myopathy (DM2/PROMM). Light microscopy showed myopathic together with "denervation-like" changes in almost all biopsies obtained from four different muscles: increased fiber size variation, internal nuclei, small angulated fibers, pyknotic nuclear clumps, and predominant type 2 fiber atrophy. Quantitative morphometry in 18 biopsies that were immunostained for myosin heavy chain confirmed a predominance of nonselective type 2 fiber atrophy. These histological changes were similar in all patients regardless of the site of biopsy, the predominant clinical symptoms and signs, and the clinical course. It is likely that, in a number of undiagnosed patients, DM2 is the underlying disorder. With a better understanding of the histopathological pattern in DM2, biopsies from patients with undiagnosed neuromuscular disorders can now be reevaluated.

Autosomal dominant hyaline body myopathy: clinical variability and pathologic findings.

To report clinical, morphologic, and immunohistochemical studies on autosomal dominant, clinically nonprogressive, and not previously described progressive forms of hyaline body (HB) myopathy (HBM) in a Saudi Arabian kindred. Muscle biopsies from four patients showed HB in type 1 fibers; they were positive for ATPase at pH 4.3/4.6 and for heavy chain slow myosin (HCSM); some HB were HCSM negative. HB were nonreactive for alphaB-crystallin, ubiquitin, tropomyosin, actins, desmin, and components of sarcolemma. Ultrastructurally, HB were granular and filamentous or amorphous, often with fragments of sarcomeres, and surrounded by a zone of sarcomeric disorganization. All biopsies showed "myopathic" changes, angulated neurogenic fibers, and fiber type grouping. There was no correlation between HB and course of disease; the progressive cases displayed more severe myopathic features. Formation of hyaline bodies in hyaline body myopathy is associated with either myolysis or defective incorporation of heavy chain slow myosin into the cytoskeleton. Hyaline bodies very likely contain additional unidentified proteins. Neurogenic factors are also involved in the hyaline body myopathy pathogenesis.

Report of the 115th ENMC workshop: DM2/PROMM and other myotonic dystrophies: 3rd Workshop, 14–16 February 2003, Naarden, The Netherlands

Myotonic dystrophy (DM1, Steinert’s disease) has been known for about 100 years. Its core features are myotonia, muscle weakness, and cataracts [1]. In 1994 another disorder was published with similar core features but lacking the DM1 mutation [2,3]. The name given to this disorder was proximal myotonic myopathy (PROMM, OMIM *160900). The first ENMC workshop on PROMM in 1997 established the clinical criteria for PROMM [4]. Prior to the second ENMC Workshop on PROMM in 2000, a major breakthrough had been accomplished when, in 1998, Ranum and Day [5] described the mapping of a new genetic locus in a large Minnesota family with myotonic dystrophy-like features on chromosome 3q21. This locus was named DM2. As a result, a new nomenclature emerged and the locus for myotonic dystrophy/Steinert’s disease was renamed DM1 [6]. Subsequent work showed that most PROMM families also mapped to the DM2 locus, whereas another smaller group of PROMM families appeared not to be linked to this locus. One separately described family with marked proximal atrophies, called proximal myotonic dystrophy [7], also mapped to the DM2 locus [8], and the workshop adopted the term myotonic dystrophy type 2 (DM2) for all the progressive myotonic multiorgan disorders linked to the DM2 locus. The clinical course of DM2 appeared to be more favourable compared to DM1. Families with DM2 did not have the severe congenital form of illness that occurs in DM1. Abnormalities in the social and cognitive abilities of adults with DM2 were typically mild or absent, and there was no prominent weakness of the facial and bulbar muscles. In DM2 the manual skills largely remained intact, and hypersomnia and mental retardation were not prominent findings. All these characteristic features of DM2 have not changed since the first ENMC Workshop[4]. They are still valid. In the advent of this 3rd workshop on DM2/PROMM, the definitive milestone of research efforts was achieved in 2001 with the identification of the mutation underlying DM2 by Ranum and Day, in collaboration with Ricker [9]. The mutation is a huge (CCTG)n microsatellite repeat expansion in the first intron of the ZNF9 gene and is thus similar to the (CTG)n repeat causing DM1. The aims with this 3rd ENMC Workshop on DM2/PROMM were: