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Biomedical subjects

R W Leech

Publications and source records attributed to R W Leech.

At least 19 recordsLinked to original sources
PubMed1992

Rhabdomyolysis in childhood. A primer on normal muscle function and selected metabolic myopathies characterized by disordered energy production.

Patients with rhabdomyolysis present an important clinical problem. In acute episodes immediate treatment may be necessary to prevent significant morbidity and mortality. Evaluation of affected patients necessitates an understanding of basic muscle pathophysiology and of the variety of disturbances that can interfere with muscle energy metabolism. The physician must then pursue a systematic stepwise evaluation (Table 6) that includes obtaining relevant history and laboratory studies, as well as arranging for appropriate provocative testing and muscle biopsy. Once the diagnosis is established, patient and family counseling is necessary, particularly in genetic disorders. Unfortunately, specific therapies have not proven entirely successful, and treatment generally has been directed at reducing the severity of rhabdomyolytic episodes.

Child↗
PubMed1992

A modified Da Fano silver stain for demonstration of neurons and dendrites in glycol methacrylate-embedded brain tissue.

Golgi impregnation techniques are commonly used for characterization of neurons and their dendritic and axonal processes. Most of the widely used techniques require processing of fresh brain tissues, which limits the amount of material available for study. Additionally, the stained blocks must be subsequently embedded in paraffin, which produces considerable cellular shrinkage and distortion artifacts. Modification by one investigator of an early silver impregnation technique, designed to demonstrate the Golgi apparatus, allowed demonstration of neurons and their dendritic processes. Our further modification of the later technique, along with embedding of the stained tissue in glycol methacrylate, permits detailed examination of neurons and their processes in formaldehyde-fixed neonatal human brains. In cerebellar sections, this modified technique impregnates nearly all Purkinje cells, elucidating the fine structural detail of the developing neuronal dendritic tree and spines.

Brain↗
PubMed1991

Cerebral abnormalities in thanatophoric dysplasia.

Neuropathologic evaluation of two infants with thanatophoric dysplasia displayed typical gross morphologic characteristics and a distinct pattern of brain malformations, including anomalies of the temporal lobe gyri and hippocampus, neuroglial heterotopias, fiber tract hypoplasia, and dysplasia of deep nuclei. Increased numbers of horizontal cells of Cajal-Retzius were striking in frequency and distribution. The pattern of abnormalities suggests arrest of cerebral cortical ontogeny late in development. As with the mucopolysaccharidoses, a shared common metabolic pathway is a potential mechanism for development of widespread bony and somatic abnormalities and associated central nervous system anomalies.

Brain↗
PubMed1991

An adult-onset myopathy characterized by a double ring appearance of muscle fibers.

We report a 33-yr-old man with an unusual neuromuscular disorder characterized by progressive generalized weakness of 3 yr duration whose muscle biopsy showed a double ring appearance in most muscle fibers. This double ring appearance was due to a peripheral outer sarcoplasmic mass and an inner ring of annular myofibrils surrounding a core of normal longitudinally oriented myofibrils. Nerve conduction studies were normal. Electromyography showed fibrillations, positive waves, and increased brief duration, low amplitude, polyphasic potentials.

Adult↗
PubMed1991

Spontaneous haematomyelia: a necropsy study.

Spontaneous haematomyelia (intramedullary spinal haematoma), is an uncommon event. Predisposing conditions have been reported including syringomyelia, pregnancy and delivery, angioma, spinal artery aneurysm, and haemophilia, but only rarely has a pathological evaluation been performed. Two such cases studied at necropsy are reported. In one case, the haematoma was restricted to the cervical spinal cord, while in the second case it extended from the medulla into the lowest thoracic cord segments. In both cases the haematomyelia was fatal. In the first case the clinical course was subacute, but in the other the course was more acute. Careful neuropathological examination showed no apparent cause for the haemorrhages.

Aged↗
PubMed1991

Absence of beta-amyloid immunoreactivity in mesial temporal lobe in Cockayne's syndrome.

Cockayne's syndrome is associated with dementia and other physical signs of premature senescence. Death usually occurs in the first or second decade of life. Because previous neuropathologic descriptions have included neurofibrillary tangles and calcific and dystrophic cerebrovascular changes, we examined the mesial temporal lobes of three children with Cockayne's syndrome (confirmed by 254-nm ultraviolet light studies). Immunohistochemistry was used to determine if beta-amyloid immunoreactivity was present in the parenchyma or cerebral blood vessels. Tissues from the mesial temporal lobe of patients with Alzheimer's disease and Down syndrome were used as controls. None of the three temporal lobes from patients with Cockayne's syndrome contained beta-amyloid immunoreactive material in either the parenchyma or vessels; all of the Alzheimer's disease and Down syndrome controls had beta-amyloid immunoreactivity.

Alzheimer Disease↗
PubMed1991

Selective type II muscle fiber hypertrophy in severe infantile spinal muscular atrophy.

The diagnostic muscle biopsy finding in severe infantile spinal muscular atrophy (Werdnig-Hoffmann disease, SMA type 1) is considered to be large-group atrophy with isolated clusters of hypertrophic type I myofibers. We present a unique case of severe infantile spinal muscular atrophy with selective hypertrophy of type II myofibers. A male infant presented at age 2 months with breathing difficulties and by age 4 months was hypotonic and weak. Electromyography revealed denervation in all extremity muscles, and nerve conduction velocities were normal but with small compound muscle action potentials. Quadriceps muscle biopsy revealed many hypertrophied type II myofibers (myofibers with a mean least diameter of 25.4 microns). In contrast, the largest type I myofibers were 20 microns in least diameter (mean diameter, 14.9 microns), and there was a normal-size population of type II fibers (mean diameter, 15.7 microns). In addition, sheets of atrophic type I and type II fibers averaged 2.0 microns in least diameter. Sural nerve biopsy was normal. Breathing difficulties progressed, with death ensuing at age 5 1/2 months. Autopsy revealed atrophy of ventral spinal roots with normal dorsal roots. There was loss of anterior horn cells, while remnant neurons were reduced in size. No other pathologic changes were identified. This case indicates that in severe infantile spinal muscular atrophy, relative sparing of the motor units with type II myofibers may occur.

Biopsy↗
PubMed1990

Spongiform encephalopathies: the physician's responsibility.

The spongiform encephalopathies encompass several diseases affecting humans and animals. In the United States, the most common of these disorders in humans is Creutzfeldt-Jakob disease. The most frequent manifestations include dementia, pyramidal tract signs, and extrapyramidal movement disorder. Several clinically distinct syndromes can be identified. Often the diagnosis is confused with other forms of dementia, and the only definitive method for establishing the diagnosis is autopsy evaluation of brain tissue. Unfortunately, since the recognition of the infectious etiology of Creutzfeldt-Jakob disease, fear has often unreasonably interfered with clinical care and autopsy evaluation of affected patients. In actuality, because of the low and restricted infectivity of the responsible agent, affected individuals present minimal risks to clinical caretakers, and handling of patient specimens is not dangerous if appropriate precautions are taken. These precautions are well established, and physicians and other health care workers should not refuse care of appropriate evaluation (including autopsy) to individuals with suspected Creutzfeldt-Jakob disease.

Aged↗
PubMed1990

Neuroimaging findings in Alexander's disease.

We present the findings from magnetic resonance imaging, computed tomographic scan, and single photon emission computed tomography of the brain in a 2-year-old girl with Alexander's disease. Computed tomographic scans showed prominent low-density white matter throughout the cerebral hemispheres. Magnetic resonance imaging showed increased T2 signal from the cerebral white matter but not the cerebellum or brain stem. Single photon emission computed tomography revealed diminished cerebral metabolism, particularly in the frontal regions, as compared with the cerebellum.

Astrocytes↗
PubMed1990

Dementia: the importance of clinical evaluation, autopsy confirmation, and research.

Because of the increasingly elderly population, dementia is a major public health problem, currently affecting over 50,000 Oklahomans at an approximate cost of one billion dollars annually. The marked overlap in symptomatology between Alzheimer's disease and other primary central nervous system degenerations makes antemortem diagnosis based on a clinical assessment tentative at best, with error rates of 25% commonly reported. Accurate diagnosis is of vital importance in improving our understanding of these illnesses, evaluating potential therapies, and providing appropriate genetic counseling to family members. Direct neuropathologic examination at autopsy is currently the only reliable method for assuring accurate diagnosis and should be undertaken in all demented patients.

Aged↗
PubMed1990

Dementia and Alzheimer's disease: resources in Oklahoma.

Senile dementia and Alzheimer's disease (often considered a single process) rank as the fourth most common cause of death in the United States and outrank in cost to the nation the three leading causes of death combined. Autopsy studies of patients with the clinical diagnosis of dementia have clearly shown that a wide variety of pathological conditions can produce clinically similar symptomatology. In order to address the many possible causes and treatments of these various forms of dementia, the Alzheimer's Association (formerly known as the Alzheimer's Disease and Related Disorders Association), the Oklahoma Autopsy Assistance Network at the Oklahoma Medical Research Foundation, and The Alzheimer's Foundation (also known as the Familial Alzheimer's Disease Research Foundation) have begun a concerted effort to develop a regional network which can aid patients and their relatives in the diagnosis and management of dementia. Awareness of these organizations by all physicians will help in the development and dissemination of the newer and more specific treatments to patients (and their relatives) with Alzheimer's disease and other forms of dementia in Oklahoma.

Alzheimer Disease↗
PubMed1989

Modification of the silver impregnation technique of Bielschowsky for use in glycol methacrylate-embedded brain tissue.

The modified Bielschowsky stain has become the standard silver impregnation technique for use in paraffin-embedded tissue sections for identifying abnormalities of neuritic processes in a variety of neurodegenerative disorders such as Alzheimer's disease. Recently, glycol methacrylate embedding has been used increasingly as a substitute for paraffin embedding of tissue, because it results in less tissue distortion during processing and provides greater clarity and resolution of cellular architecture and structural details. We have been able to modify the Bielschowsky stain for use in glycol methacrylate-embedded brain sections. The use of this technique will permit more accurate quantitation of the histopathologic changes in neuritic processes in neurodegenerative diseases.

Acrylates↗
PubMed1988

Agnathia, holoprosencephaly, and situs inversus: report of a case.

We present the first documented case of agnathia-holoprosencephaly (an uncommon form of craniofacial anomaly) associated with situs inversus. This case may represent the concordance of multiple field complex anomalies, but the possibility of a major midline malformation (situs inversus) caused by a timed insult (environmental or genetic) which affects multiple structures and occurs concurrently with a major field defect during early embryogenesis cannot be excluded.

Abnormalities, Multiple↗
PubMed1988

Massive brain stem necrosis in the human neonate: presentation of three cases with review of the literature.

In neonates suffering hypotensive or asphyxial episodes, the brain stem is particularly vulnerable to selective neuronal necrosis. Typically, the pattern is one of generalized neuronal necrosis within well-defined brain stem cranial nerve nuclei, or random neuronal degeneration within the reticular formation. More recently, isolated cases of severe partial or total cystic necrosis of the brain stem reticular formation have been recorded. The pathogenesis is poorly understood at this time, but may be similar to the less severe (but more often recognized) nuclear or focal neuronal loss. Three infants are presented in which severe necrosis of the brain stem occurred. In each, the clinical setting was one of sudden and abrupt worsening of the patient's cardiovascular status.

Brain Stem↗
PubMed1986

Holoprosencephaly and related midline cerebral anomalies: a review.

We propose a simple pathogenetic mechanism that reduces a bewildering variety of central nervous system malformations to a manageable group sharing defects of midline prosencephalic growth. It is neither new nor innovative, but attempts to summarize many pathologic entities within a concept that accounts for known embryologic events and the sequence and timing of those events. We propose midline prosencephalic dysgenesis as a category of malformations including aprosencephaly, holoprosencephaly, septo-optic dysplasia, and agenesis of the corpus callosum.

Abnormalities, Multiple↗