Biomedical subjects
B A Kakulas
Publications and source records attributed to B A Kakulas.
The clinical significance of type 1 fiber predominance.
In the course of investigating children with hypotonia, muscle biopsy of the vastus lateralis frequently demonstrates greater than 55% predominance of the aerobic type 1 fibers of "type 1 fiber predominance" (T1FP). The clinical significance of T1FP is not well known. T1FP can be associated with a variety of neurological disorders but a significant proportion has no apparent cause. We followed up 23 children with T1FP to establish whether a neurological disorder subsequently became apparent or whether a distinct clinical entity of T1FP could be identified. Sixty percent of the children were found to have a specific neurological disorder, while 40% did not and may represent a distinct clinical entity. The majority of children with the clinical entity of T1FP improved although some were left with mild motor disability. Such information is important for counseling when patients with T1FP are first assessed.
Histochemical and contractile property changes during human muscle development.
When the histochemical and contractile properties of infant muscles change postnatally, and what influence muscle function has on these changes, were the focus of this study. Contractile properties were measured in the plantaflexor (PF) and dorsiflexors (DF) of 19 newborns and 36 infants aged 5-16 months. Infants were tested between one and four times at monthly intervals. Measurements included maximal twitch tension (Pt), time to peak tension (TPT), and half-relaxation times (1/2RT). TPT was similar in PF (77 ms) and DF (73 ms) at birth, remained unchanged in DF, and slowed in PF to 110-120 ms between 9 and 12 months. Type I distributions were determined at autopsy in fetal through to adult muscles. Completion of differentiation occurred in soleus at about the age that contractile properties slowed and infants started to use these muscles more. A trend of higher percentages of type I distributions was also noted in children than either newborns or adults in other muscles. The implications of these findings and the clinical use of these methods for evaluating peripheral neuromuscular function is discussed.
Comparison of basic fibroblast growth factor in X-linked dystrophin-deficient myopathies of human, dog and mouse.
Binding of polyclonal antibodies specific for bFGF was examined in tissue sections of myopathic and normal muscles from humans, dogs and mice. The proposal tested was that differences in the amount or distribution of bFGF in muscles of the 3 species, might correlate with the limited muscle regeneration seen in humans and dogs afflicted with x-linked muscular dystrophy, in contrast with the sustained new muscle formation in mdx mice with the homologous myopathy. There was a striking difference between the species in the binding of bFGF antibodies to extracellular matrix, particularly at the periphery of myofibres; binding was pronounced in mouse but weak or absent in human and dog muscle. Binding to muscle nuclei and sarcoplasm was also stronger in mice than in humans and dogs, and in all species was more pronounced in foetal than adult muscle. Increased binding of bFGF antibodies was seen in damaged and regenerating muscle cells in all myopathic specimens where these were present. This was associated with the regenerative process rather than with myopathy, as a similar pattern of bFGF expression was seen in mouse muscle regenerating after experimental crush injury. The higher extracellular staining for bFGF around the periphery of mouse myofibres correlated with the successful muscle regeneration in dystrophic mice. Results suggest that bFGF at the fibre periphery might stimulate a local increase in the numbers of muscle precursor cells which can respond to injury in the mdx mouse.
Two distinct mutations in a single dystrophin gene: chance occurrence or premutation?
We report on a kindred segregating 2 distinct mutations of a dystrophin gene. DNA analysis showed that the second mutation, a deletion, arose in the same gene carrying the primary defect which produced a Becker phenotype in the affected males. The DNA data for this family are reported and the alternative explanations of chance occurrence and premutation are discussed to explain these unusual findings.
Angelman's syndrome: a neuropathological study.
We report the neuropathological findings of a 3-year-old boy with Angelman's syndrome. The main abnormalities were macroscopic consisting of small temporal and frontal lobes which also showed disorganised and irregular gyri. The occipital lobes appeared flattened but were otherwise normal as were the parietal lobes. The brain stem and cerebellum appeared normal externally. Microscopically there was irregular distribution of neurons in layer 3 and in the cerebral white matter a few subcortical ectopic neurons were present in the temporal and frontal lobes. A single "Purkinje" cell heterotopia was seen but otherwise the cerebellum appeared normal.
Recent progress in the molecular genetics of the muscular dystrophies.
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A TaqI map of the dystrophin gene useful for deletion and carrier status analysis.
We describe a partial TaqI map of the dystrophin gene, obtained mainly by analysis of 87 overlapping DMD/BMD deletions with small fragments of the dystrophin cDNA probes; exon 6 of the dystrophin gene was identified on the TaqI map using the polymerase chain reaction. The cDNA probes detect five polymorphisms with TaqI, more than with HindIII (one), BglII (four), or PstI (three). The five polymorphisms are analysed concomitant with screening for deletions on the TaqI map, and in the one-third of DMD/BMD cases with no detected deletion the polymorphism information may be used for counselling. Correlation of the TaqI map with the HindIII map in the region of probes 5b-7 and 8 has allowed the establishment of reading frame. In this region of the dystrophin gene, all of 41 DMD deletions resulted in a shift of reading frame and all of 10 BMD patients maintained reading frame, in agreement with the 'reading frame hypothesis'.
Acute burst fractures. A comparative analysis of a modern fracture classification and pathologic findings.
Ten acute thoracolumbar burst fractures (T11-L3) in eight spinal specimens were investigated regarding injuries to the bony, ligamentous, and neural structures. The fractures were subdivided into three groups, which were compared to the different burst fractures proposed by Denis in 1983. In the specimens, it was impossible to separate Denis Type A and B fractures. The Type D fractures showed pronounced instability. These latter fractures were subdivided into two groups: one with rupture of the bony vertebral arch (D) and one with rupture of the posterior ligaments (D2). The Denis A or B fractures were not associated with macroscopic or microscopic damage to the spinal cord or cauda equina, or both. However, in the six Denis D fractures, the neural tissue was transected in one case and severely compressed in four cases.
The diagnosis of Duchenne and Becker muscular dystrophies: two years' experience in a comprehensive carrier screening and prenatal diagnostic laboratory.
This article describes the diagnostic algorithm being used for the management of the 148 families affected by Duchenne or Becker muscular dystrophy who are known to the Molecular Neurogenetics Laboratory in the Department of Neuropathology, Royal Perth Hospital. In 60 families from whom DNA has been obtained, 41 mutations (39 deletions and two duplications) of the Duchenne muscular dystrophy gene (DMD) have been identified by means of complementary DNA (cDNA) probes. DNA-based screening has clarified the carrier status of 45 at-risk women, and 13 pregnancies have been monitored. In addition, cDNA screening of all relevant patients with autosomal recessive muscular dystrophy, spinal muscular atrophy or limb-girdle muscular dystrophy facilitated the correct diagnosis of Becker muscular dystrophy in three patients.
The natural history of minicore-multicore myopathy.
To determine the natural history of minicore-multicore myopathy (MMM) we studied 5 patients who were found to have this disorder from 6 to 16 years ago. Four of these patients had improved muscle strength since their original assessment and one patient had deteriorated. There were no clinical electrophysiological or pathological features that distinguished this last patient from the others. We conclude, therefore, that most patients with MMM may be expected to improve as time passes but, for unknown reasons, a minority may deteriorate. This information should be helpful to clinicians in their prognostic advice to new patients.
VII International Congress on neuromuscular diseases, Munich, September 16-22, 1990.
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Morphology and histology of the latissimus dorsi muscle.
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Duchenne muscular dystrophy (DMD) gene cDNA 8 PstI and TaqI polymorphisms involve exon 51 of the HindIII map.
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Differentiation of Becker muscular dystrophy from limb-girdle muscular dystrophy and Kugelberg-Welander disease using a cDNA probe.
A 31-year-old man previously investigated for a neuromuscular disorder was diagnosed as having either limb-girdle dystrophy, spinal muscular atrophy, or Becker muscular dystrophy. Extensive clinical and special neurological investigations failed to clarify this differential diagnosis. However, recent DNA studies have shown a deletion of the dystrophin gene, thereby providing an unequivocal diagnosis of Becker muscular dystrophy. The application of molecular genetic techniques in the diagnosis of inherited neuromuscular disorders is discussed.
Limb girdle syndromes. Clinical, morphological and electrophysiological studies.
The clinical syndrome of slowly progressive proximal limb and limb girdle muscular weakness and atrophy, or limb girdle syndromes (LGS), has a diverse aetiology. Several of the congenital, mitochondrial and other metabolic myopathies and spinal muscular atrophies are recently recognized causes of LGS. Thus the position of limb girdle muscular dystrophy (LGMD) as a discrete entity in the nosology of muscle disease deserves reappraisal. We have therefore reevaluated our experience of 33 patients in this light. Detailed clinical, electrophysiological, and pathological studies including autopsies in 2 cases, were performed. As a result we are confident that LGMD does exist as a sporadic or autosomal dominant (2 families) or recessive condition (2 families). There are therefore probably at least 2 distinct genotypes. Typical LGMD (18 patients in our series) is characterized by slowly progressive symmetrical proximal upper and lower limb girdle weakness and atrophy, elevation of the serum creatine kinase at some stage, dystrophic or less severe myopathic muscle lesions on biopsy, and myopathic EMG findings. Two minor subgroups of LGMD were identified in our series with similar clinical and laboratory features but distinguishable by the development of either facial (4 patients) or by distal limb muscle involvement (3 patients). A further group of patients with sporadic LGS (5 patients) had slowly progressive proximal symmetrical upper and lower limb-girdle weakness and atrophy with myopathic or neurogenic features on either EMG or muscle biopsy so that the precise characterization was difficult. Two of these patients had distal limb muscle involvement and contractures. One patient had upper limb-girdle muscle atrophy with normal lower limbs. A disorder affecting muscle, nerve or both remains a possibility in these cases.
Positive immunostaining of ovine congenital progressive muscular dystrophy with antibody against N- and C-terminal dystrophin.
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