Modified Gomori Trichrome Stain Research Articles

Disoriented collagen fibers and disorganized, fibrotic orbicularis oris muscle fiber with mitochondrial myopathy in non-syndromic cleft lip

ObjectiveThis study aims to explore and compare the histopathology of upper cleft lip tissue in order to identify the abnormalities and orientation of muscle and collagen fibers in patients affected with non-syndromic cleft lip with or without cleft palate (NSCL±P) and normal controls. Materials and methodsEight fresh lip tissues of consented patients with NSCL±P and two controls were fixed and stained with hematoxylin and eosin (H&E), Masson’s trichrome (MT), and modified Gomori trichrome techniques. The images were captured and examined using imaging cellSens software (Olympus, Tokyo, Japan) and Mirax Scan (Carl Zeiss, Germany). The H&E stained tissues were analysed for muscle fiber size using image processing program (imageJ, USA). Histopathological appearance of epidermal and dermal layers including collagen orientation, as well as muscle fibers abnormalities were observed. ResultsTissues stained with H&E exhibit pseudoepitheliomatous hyperplasia, epidermal and sebaceous glands hyperplasia. Morphometric analysis of muscle fibers showed the diameter was between 6.912 and 10.246 µm. Collagen fibers were densely packed in cleft tissue, but muscle fibers were sparse in MT stain. Modified Gomori trichrome stain revealed hypoplastic muscle with fibrosis, including ragged red fibers. ConclusionDisoriented collagen fibers, significant sparse and disorganized orbicularis oris muscle fibers with classical myopathic appearances proved that cleft tissue had abnormal histology findings. These findings further support the mechanism of collagen and muscle fibers during embryonic development that causing cleft formation.

Telocytes, c-Kit positive cells, Smooth muscles, and collagen in the ureter of pediatric patients with congenital primary obstructive megaureter: elucidation of etiopathology

ABSTRACT Congenital primary obstructive megaureter (POM) is an uncommon pediatric anomaly that is due to obstructive distal ureter leading to the loss of peristalsis with consequent ureterohydronephrosis causing loss of kidney function. The objectives are to elucidate the etiology of POM by demonstrating the presence of interstitial cells of Cajal (ICC), telocytes, smooth muscles, and collage in the obstructive and dilated ureteral segments. The study was carried out on 15 surgical specimens of congenital POM in pediatric patients, age range was 4 to 24 months, they were operated upon by excision of the obstructed segment, tailoring the dilated ureter, and anastomosing it to the bladder. Specimens included the obstructed ureteral segment and part of the dilated ureter. Specimens were examined with hematoxylin and eosin (H&E) stain, Modified Gomori trichrome stain, immunohistochemistry (IHC) with α-muscle actin, and c-kit (CD117), and transmission electron microscopy (TEM). Obstructed segment showed excess collagen intervening between smooth muscles, excess c-Kit positive cells, and presence of telocytes. The dilated segment of the ureteral wall is formed of smooth muscle bundles with scanty collagen. Staining with c-Kit did not demonstrate positive cells. TEM showed myofibroblasts and close adherence of smooth muscle cells to each other with absence of telocytes. The pathophysiology of POM is multifactorial. Loss of interstitial cells and rarity of collagen result in loss of elasticity of dilated segment leading to massive dilatation. While the obstructed segment had no muscle conductivity due to excess collagen irrespective of presence of telocytes.

Megaconial congenital muscular dystrophy secondary to novel CHKB mutations resemble atypical Rett syndrome.

Megaconial congenital muscular dystrophy (CMD)(OMIM #602541), related to CHKB mutation, is a rare autosomal recessive disorder. To date, only 35 confirmed patients are recorded. We present a detailed description of the clinical, histopathological, imaging, and genetic findings of five children from four Indian families. The children had moderate-to-severe autistic behavior, hand stereotypies, and global developmental delay mimicking atypical Rett syndrome. In addition, generalized hypotonia was a common initial finding. The progression of muscle weakness was variable, with two patients having a milder phenotype and three having a severe form. Interestingly, the majority did not attain sphincter control. Only patient 1 had classical ichthyotic skin changes. Muscle biopsy in two patients showed a myopathic pattern with characteristic peripherally placed enlarged mitochondria on modified Gomori trichrome stain and electron microscopy. Genetic analysis in these patients identified three novel null mutations in CHKB [c.1027dupA (p.Ser343LysfsTer86);c.224 + 1G > T (5' splice site); c.1123C > T (p.Gln375Ter)] and one reported missense mutation, c.581G > A (p.Arg194Gln), all in the homozygous state. Megaconial CMD, although rare, forms an important group with a complex phenotypic presentation and accounted for 5.5% of our genetically confirmed CMD patients. Atypical Rett syndrome-like presentation may be a clue towards CHKB-related disorder.

Monoclonal gammopathy of renal significance (MGRS)-related AL amyloidosis complicated by amyloid myopathy: a case report

BackgroundLately, monoclonal gammopathy of renal significance (MGRS) has been defined as a group of renal disorders that are strongly associated with monoclonal protein, including amyloid immunoglobulin light chain (AL) amyloidosis. Amyloid myopathy is rare (1.5% of all patients with amyloidosis) and the prognosis is poor. Furthermore, only approximately 20% of patients with amyloid myopathy are reported to have renal involvement, indicating a lack of data in the literature.Case presentationHere, we report a rare case of MGRS-related AL amyloidosis complicated by amyloid myopathy that presented with muscle weakness in the upper and lower limbs, neck and fingers, and nephrotic syndrome. Blood, urine, and bone marrow examination revealed monoclonal gammopathy of undetermined significance (MGUS) (Bence Jones protein-lambda). Muscle biopsy of the vastus lateralis muscle demonstrated amyloid proteins in the sarcolemma and in the blood vessel walls on Congo red staining, suggesting amyloid myopathy, and tiny inclusions in fibers on modified Gomori trichrome stain. Although we thought they were reminiscent of nemaline bodies, we could not confirm the nature of this structure. Renal biopsy demonstrated amyloid proteins in the mesangial region, part of the capillary walls, and the blood vessel walls on direct fast scarlet staining. As these amyloid proteins were positive for p-component staining and negative for amyloid A staining, β2-microglobulin, and pre-albumin, and as lambda light chains were positive in the mesangial region, we diagnosed the patient with MGRS-related AL amyloidosis. Although he was treated with melphalan and dexamethasone, his symptoms did not improve.ConclusionsAL amyloidosis involving the kidneys and muscles has a poor prognosis, and a delayed diagnosis of amyloid myopathy is common because of its rarity and frequent misdiagnosis, which increases organ function deterioration. Therefore, early detection, therapeutic intervention, and careful follow-up are crucial.

Histological Changes in Skeletal Muscle During Death by Drowning: An Experimental Study.

A diagnosis of drowning is a challenge in legal medicine as there is generally a lack of pathognomonic findings indicative of drowning. This article investigates whether the skeletal muscle undergoes structural changes during death by drowning. Eighteen Wistar rats were divided into 3 equal groups according to the cause of death: drowning, exsanguination, and cervical dislocation. Immediately after death, samples of the masseter, sternohyoid, diaphragm, anterior tibial, soleus, and extensor digitorum longus muscles were obtained and examined by light and electron microscopy.In the drowning group, all muscles except the masseter displayed scattered evidence of fiber degeneration, and modified Gomori trichrome staining revealed structural changes in the form of abnormal clumps of red material and ragged red fibers. Under the electron microscope, there was myofibrillar disruption and large masses of abnormal mitochondria. In the exsanguination group, modified Gomori trichrome staining disclosed structural changes and mitochondrial abnormalities were apparent under light microscopy; however, there was no evidence of degeneration. No alterations were observed in the cervical dislocation group.As far as we know, this is the first time that these histological findings are described in death by drowning and are consistent with rhabdomyolysis and intense anoxia of skeletal muscle.

Comparison of muscle pathology in riboflavin-responsive lipid storage myopathy before and after treatment: one case report and review of literature

Objective To study the muscular pathological characteristics in riboflavin-responsive lipid storage myopathy before and after treatment. Methods A 10-year follow-up visit was made on a patient with riboflavin-responsive lipid storage myopathy, and the changes of serum enzymes, and both histological and ultrastructural data acquired by general muscular pathology, immunohistochemistry and electron microscope were observed before and after treatment by using levocarnitine. ETFDH gene were detected in the patient and his family. Results The patient presented limb weakness, difficulty in raising head and dysphagia, which were typical clinical features of lipid storage myopathy (LSM). The serum creatine kinase (CK) level and lactic dehydrogenase (LDH) level elevated evidently. EMG showed myogenic abnormality, and muscular pathology revealed numerous lipid droplets deposited in the fibers. ATPase staining showed predominant atrophy of typeⅠ fibers and relative increasing of the portion of typeⅡ fibers. Modified Gomori trichrome (MGT) staining did not observe ragged red fibers. Immunohistochemical staining showed positive expression of dystrophin. Sultan Ⅲ staining revealed multiple vacuolated myofibers. ETFDH gene test showed two heterozygous mutations in the patient. After treating with levocarnitine for several years, the patient could live a normal life. The muscular pathological result returned to normal. Conclusions After appropriate therapy, patient with lipid storage myopathy can not only gain complete remission clinically, but also the reversion of lesion pathologically. doi: 10.3969/j.issn.1672-6731.2014.06.005

Clinical pathological and genetic analysis of 2 cases of mitochondrial myopathy presented as acute motor axonal neuropathy

Background The main clinical manifestations of mitochondrial myopathy are chronic limb weakness and muscular soreness. Subclinical peripheral nerve injury is also reported, but acute axonal neuropathy.like syndrome concurrent with lactic acidosis is rare. In this paper the clinical features of 2 patients presenting as acute lactic acidosis and sudden muscle weakness were analyzed. Pathological changes and genetic mutations were detected. Methods Electromyography (EMG) and muscle biopsy were performed. Modified Gomori trichrome (MGT) and succinodehydrogenase (SDH) staining were used to identify pathological changes. Changes of ultra microstructure of muscular tissue were observed under electron microscope. Mitochondrial DNA (mtDNA) full length sequencing was performed using 24 pairs of partially overlapping primers. Results EMG showed a coexistence of neurogenic and myogenic changes. Dramatic decrease of motor nerve amplitude and moderately reduced sensory nerve amplitude were observed but nerve conduction velocity was normal in both patients. Impressive ragged red fibers were seen on MGT staining. Electron microscope showed dramatic mitochondrial abnormalities in Case 1 and paracrystaline inclusions in Case 2. mtDNA sequencing showed 3243A > G mutation in Case 1 and 8344A > G mutation in Case 2. Conclusions Mitochondrial myopathy can present as metabolic crisis like acute lactic acidosis, dyspnea and acute motor axonal neuropathy.like syndrome. It is a life.threatening phenotype that needs more attention. doi: 10.3969/j.issn.1672-6731.2014.06.007

G.P.66 Dysfunction of ESCRT-pathway is associated with formation of rimmed vacuoles and inclusions in sporadic inclusion body myositis

Abstract Sporadic inclusion body myositis (sIBM) is a common inflammatory muscle disease in elderly person. Pathological feature of sIBM is the presence of rimmed vacuoles (RVs) revealed by modified Gomori trichrome staining and multiprotein aggregates made of amyloid β (Aβ) and ubiquitin in muscle fibers. RVs are considered autophagic, since they often contain lysosomal membranous debris, an end product of muscle-fiber digestion, and increased immunoreactivity of some of the lysosomal enzymes. In autophagy-lysosomal pathway, endosomal sorting complex required for transport (ESCRT) shares a role in the transport of ubiquitinated protein to lysosome. Charged multivesicular protein 2B (CHMP2B), one of the subunits in ESCRT-pathway, was reported to be causative for FTD-3. In this study, we examined inclusions and RV among muscular disorders through immunohistochemical analysis of CHMP2B and CHMP2A, a complementary protein of CHMP2B. The muscle biopsy specimens from sIBM ( n = 9), distal myopathy with rimmed vacuoles (DMRV: n = 4), polymyositis (PM: n = 9), Becker muscular dystrophy (BMD: n = 5) were examined. These specimens were subjected to immunohistochemistry, immunofluorescent technique, and western blot, using antibodies against Aβ, CHMP2B, and CHMP2A. In sIBM and DMRV, inclusions and RVs were immunopositive for CHMP2B and CHMP2A. Double immunofluorescence staining showed a colocalization of Aβ and CHMP2B. Western blot indicated decrease of CHMP2B in sIBM and DMRV. This study suggests that the ESCRT-pathway is implicated in the formation of aggregates and RVs in sIBM and DMRV.

P5.35 Inclusion is accumulated by CHMP2B in sporadic inclusion body myositis

Sporadic inclusion body myositis (sIBM) is a common inflammatory muscle disease in elderly person. Outstanding feature of sIBM is the presence of rimmed vacuoles (RV) revealed by modified Gomori trichrome staining and multiprotein aggregates made of amyloid β (Aβ) and ubiquitin in muscle fibers. RV are considered autophagic, since they often contain lysosomal membranous debris, an end product of muscle-fiber digestion, and increased immunoreactivity of some of the lysosomal enzymes. Autophagy is implicated in not only sIBM but also some frontotemporal dementia (FTD).

Delay of denervation atrophy by sensory protection in an end-to-side neurorrhaphy model: A pilot study

Temporary sensory innervation delays the atrophy process. A major disadvantage of most experimental models is that sensory-protected muscles must be denervated a second time to allow reinnervation by the affected nerve. The aim of this study was to assess the effect of sensory protection on denervated gastrocnemius muscle in an end-to-side neurorrhaphy model, in which denervated muscles may be preserved until axons of the native nerve reach their target without the necessity for a second operation. The tibial nerve of 24 female Lewis rats was transected. Twelve animals acted as the controls. In the other 12 animals, the end of the sural nerve was connected to the side of the distal tibial nerve stump (sensory protection group). At 5 and 10 weeks, wet gastrocnemius muscle weight was reported as a ratio of the operated to the unoperated side. For histological analysis, muscle samples were rapidly frozen and sections were stained with haematoxylin and eosin, Oil Red O stain and modified Gomori trichrome stain. The difference between the sensory protection group and the control group was statistically significant at 5 (0.36±0.01 and 0.29±0.01, respectively; p<0.001) and 10 weeks postoperatively (0.28±0.01 and 0.19±0.00, respectively; p<0.001). Histological observations revealed that sensory-protected muscles underwent less atrophy. Sensory protection delays atrophy in an end-to-side neurorrhaphy model.

Tubular aggregate myopathy: A rare form of myopathy

Tubular aggregate myopathy (TAM) is a rare form of myopathy with an autosomal dominant or recessive pattern. Four rare cases of TAM are described. All patients presented with muscle aches and pains, sometimes cramps. Muscle biopsies were snap frozen and processed for routine, special, enzyme, and immunohistochemistry. Tissue was also processed for electron microscopy. Muscle biopsy revealed similar changes characterized by subsarcolemmal accumulation of granular material that stained red with modified Gomori trichrome stain, intense blue with nicotinamide adenine dinucleotide-tetrazolium reductase, but was non-reactive to succinyl dehydrogenase and cytochrome oxidase stains. Ultrastructural examination showed aggregates of hexagonal tubules in the subsarcolemmal region, which are pathognomonic of this entity. This report highlights the importance of histochemistry and electron microscopy for accurate diagnosis; otherwise TAM can be misdiagnosed on clinical grounds as a metabolic or mitochondrial myopathy.

Nemaline rod myopathy: A rare form of myopathy

Nemaline rod myopathy (NM) is a rare form of congenital myopathy characterized by slowly progressive or nonprogressive muscle weakness and pathognomonic rod-like structures within the muscle fibers. To the best of our knowledge, this is first documentation of the clinicopathological features of this rare entity from India. All cases of NM diagnosed in our laboratory were retrieved. Clinical and pathological features were reviewed. During a period of 1.5 years (Jan 2004 to June 2005), we received 750 muscle biopsies for various reasons. Of which, 15 were diagnosed as congenital myopathies and four as nemaline rod myopathies. Thus, NM comprises 0.53% of all muscle diseases and 22.6% of all congenital myopathies. All of them presented in childhood (first five years of life) with generalized hypotonia, feeding problems, repeated respiratory infections and muscle weakness. Both males and females were equally affected. The CPK levels were normal and EMG was myopathic. Microscopic examination revealed minimal changes but characteristic red-colored material was seen on modified Gomori trichrome staining which was immunopositive to alpha actinin. Ultrastructural examination confirmed this material to be nemaline rods. NM, although a rare form of congenital myopathies, should be suspected in children who present with generalized hypotonia, repeated chest infections and slowly progressive muscle weakness. This report highlights the importance of histochemistry and ultrastructural examination in the diagnosis of this entity, in the absence of the availability of methodology for genetic studies.

Peroxisomal proliferator activated receptor agonists as potential therapy for mitochondrial respiratory chain complex (RCC) defects

display slow growth, decreased mitochondrial membrane potential, and impaired respiratory capacity. These defects are reversed upon restoration of fusion capability. The importance of mitochondrial fusion is further underscored by the fact that two neurodegenerative diseases, Charcot– Marie–Tooth disease type 2A (CMT) and autosomal dominant optic atrophy (DOA), are caused by mutations in Mfn2 and OPA1, respectively.To further explore the physiological requirements for mitochondrial fusion, we have created conditional knockout mice for both Mfn1 and Mfn2. Interestingly, Mfn2 is required for proper cerebellar development. When cerebellar primordia is targeted embryonically, pups display severe problems in balance and motility, resulting in feeding problems and death by about two weeks of age. When Purkinje cells, the only efferent processes of the cerebellum, are targeted upon maturity, they actually degenerate, causing the mice to develop tremors and wobble while walking. Thus, mitochondrial fusion is required in the central nervous system along with the peripheral motor neurons and optic nerve affected in CMT and DOA.Disruption of both Mfn1 and Mfn2 in skeletal muscle results in severely runted mice, which die at around two months of age. Muscle mass is greatly reduced in these mice, and cross-sectional analysis reveals significantly decreased muscle fiber widths. A modified Gomori-trichrome stain results in predominantly red fibers. In addition, a succinate-dehydrogenase (SDH) enzymatic assay reveals greatly increased activity in all fibers. The combination of red fibers and increased SDH activity is a hallmark of many mitochondrial diseases, suggesting a common link between deficiencies in mitochondrial fusion and traditional mitochondrial diseases.

Anatomic Study of Laser-Assisted Endoscopic Cricopharyngeus Myotomy

Laser-assisted endoscopic cricopharyngeus muscle (CPM) myotomy has been used to correct dysphagia caused by CPM dysfunction. The aim of this study was to anatomically characterize this procedure in hopes of demonstrating its safety and efficacy. A Dohlman endoscope was used to isolate the CPM in 5 lightly preserved, thawed cadavers. A carbon dioxide laser at 10 W continuous power was used to section through the CPM in conjunction with a micromanipulator connected to an operating microscope. The specimens were then carefully dissected and photographed to demonstrate the anatomy of the pharyngoesophageal segment, including the location of the incision and the condition of the tissue planes. The CPM was harvested for histologic studies, sectioned, and prepared with modified Gomori trichrome stain. Gross examination of the retropharyngeal region revealed the presence of intact buccopharyngeal fascia between the lasered region and the retropharyngeal space. Histologic analysis demonstrated sectioning of the CPM with preservation of this fascia layer. Placement of the endoscope was difficult in 1 cadaver, in which we were unable to properly identify the CPM. The carbon dioxide laser-assisted endoscopic CPM myotomy is a potentially anatomically safe and viable procedure when properly performed. However, the potential for violation of the retropharyngeal space is real.

Histochemical study of the sensory endings of muscle spindles in rat longissimus muscles

Most studies concerning the structure and function of muscle spindles have utilized the hind limbs of experimental animals. However, little is known about muscle spindles of the back muscles. The purpose of this study was to investigate the sensory innervation of muscle spindles of the paravertebral muscle in the rat. The subjects were 10 normal male rats. The longissimus muscles were isolated and frozen in cooled isopentane (-160 degrees C), and serial transverse sections were made with a cryostat. Histochemical preparations were then made using nicotinamide adenine dinucleotide tetrazolium reductase (NADH-TR) stain and modified Gomori-trichrome stain. The muscle spindles in each segment were identified microscopically by observing the equatorial and polar regions. NADH-TR staining was employed to distinguish nuclear bag1, nuclear bag2, and nuclear chain intrafusal muscle fibers. A total of 20 spindle poles were surveyed. The mean polar length of intrafusal fibers as well as that of each region (A, B, and C) were measured. NADH-TR staining also demonstrated the terminal sites of sensory fibers along intrafusal fibers. All spindle poles surveyed were innervated by secondary sensory fibers in addition to primary sensory fibers. Eight spindle poles were intermediate type muscle spindles that were innervated by one primary sensory fiber and one secondary sensory fiber. Twelve spindle poles were complex type muscle spindles that were innervated by one primary sensory fiber and multiple secondary sensory fibers. The mean length of the A region was 223.1+/-37.9 microm (n=8) for intermediate type spindles and 493.8+/-157.0 microm (n=12) for complex type spindles. The length of the A region was significantly longer in the complex type spindles than in the intermediate type spindles (p<0.001). The results suggest that the innervations of secondary sensory fibers were well developed in the longissimus muscle spindles in the rat. The morphological features of muscle spindles of the longissimus muscle may represent the structural basis for qualitatively different afferent discharges that relate to the characteristic types of locomotion served by paravertebral muscles.

Involvement of nervous system in maternally inherited diabetes and deafness (MIDD) with the A3243G mutation of mitochondrial DNA.

The A3243G mutation of mitochondrial DNA (mtDNA) has been associated with maternally inherited diabetes and deafness (MIDD) in a number of reports; however, the involvement of the nervous system has rarely been mentioned, prompting this exploration of the manifestation of neurological disorders in MIDD cases. We investigated four generations of a large Taiwanese family in which MIDD is manifest. We conducted a series of clinical examinations, including computed tomography (CT) and magnetic resonance imaging (MRI) of the head, brain 99mTc-HMPAO single photon emission computed tomography (SPECT), cognitive function tests, and nerve conduction velocity (NCV) studies. Blood levels of creatine kinase (CK) and lactate, pathology of muscle biopsy samples and proportions of mutant mtDNA in blood cells, hair follicles, muscle and skin were also analyzed. Mean follow-up period was 4 years. The patients exhibited the clinical features of diabetes mellitus including sensorineural hearing loss, short stature, and/or histories of spontaneous abortion. No stroke-like episodes were reported. Analysis for mtDNA revealed that the A3243G mutation existed in 11 members (6 symptomatic and 5 asymptomatic members) of this MIDD-prone family, with the proportion of mutant mtDNA ranging from 21% to 47% in leukocytes. Head CT revealed diffuse brain atrophy for all 6 (100%) patients examined and bilateral basal ganglia calcification in 4 of 6 (67%) patients. Brain 99mTc-HMPAO SPECT revealed diminished uptake in the bilateral parieto-occipital or occipital regions for all 6 tested patients, cognitive function for these patients was normal. Results of head CT and SPECT were normal in one asymptomatic member of the family. One muscle biopsy revealed abundant ragged-red fibers with modified Gomori-trichrome stain. Muscle-enzyme activity and serum-lactate levels were normal. We have demonstrated that a wide spectrum of sub clinical pathologies of the central nervous system and muscle are present for this MIDD-prone family, none of whom developed typical MELAS during the 4-year period of follow-up study.

Nebulin is normally expressed in nemaline myopathy.

Since the nebulin gene is located in the candidate gene locus of autosomal recessive nemaline myopathy, 2q21.2-q22, we examined five muscle biopsy specimens with monoclonal and polyclonal antibodies against nebulin in combination with the modified Gomori trichrome stain. We were able to demonstrate immunohistochemically that there was no abnormality in nebulin in the muscle fibers both with and without nemaline bodies. Although the molecular weight of nebulin was normal, it was slightly reduced in amount on immunoblotting.

Sensitivity to Mivacurium in a Patient with Mitochondrial Myopathy

Sensitivity to Mivacurium in a Patient with Mitochondrial Myopathy

Late‐onset mitochondrial myopathy

In the majority of patients with mitochondrial encephalomyopathies, signs and symptoms appear in the first three decades of life. Here we report on a group of 9 older patients (> 69 years old) with late-onset skeletal myopathy characterized by focal accumulations of deleted mitochondrial DNAs (mtDNAs) and altered muscle energy status, suggestive of a primary mitochondrial disease. The clinical phenotype was somewhat variable. However, all patients shared a common feature of insidious moderate proximal muscle weakness; some also showed fatigability and axial muscle weakness. In situ hybridization analysis demonstrated accumulations of messenger RNAs transcribed from deleted mtDNAs in a relatively large number of muscle fibers in the patient group. These fiber segments appeared as ragged red with the modified Gomori trichrome stain and hyperreactive with a modified succinate dehydrogenase stain. Most were negative for cytochrome c oxidase activity. On transverse sections their mean frequency was 0.69% (trichrome) and 1.97% (succinate dehydrogenase) significantly above control levels. Multiple mtDNA deletions were demonstrated by the polymerase chain reaction in both the patients and an age-matched control group, but not in younger control subjects. Phosphorus 13 magnetic resonance spectroscopy of resting muscle showed a decreased phosphocreatine-inorganic phosphate ratio in the patient group. The myopathy in this group of patients appears to result from mitochondrial dysfunction related to the clonal expansion of different mtDNA deletions in individual fiber segments. While the origin of the mtDNA mutations is not clear, the phenotype seems to represent an exaggerated form of what is observed in the normal aging process.

Fatal infantile mitochondrial encephalomyopathy with complex I and IV deficiencies

A 4-month-old male infant had a fatal infantile mitochondrial disease associated with cardiomyopathy. He had elevated lactate concentrations in blood and cerebrospinal fluid and an increased lactate/pyruvate ratio. Histochemical analysis of muscle biopsy revealed several ragged-red fibers on modified Gomori trichrome stain and mildly decreased cytochrome c oxidase (complex IV) activity. Complex I and IV activities of the respiratory chain in muscle were decreased to about 35% of normal values biochemically; subunits of the two complexes were decreased nonselectively on immunoblotting. Mitochondrial DNA analysis failed to detect any mutation. Complex I and IV deficiencies should be considered as one of the causes of fatal infantile mitochondrial disease.