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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
PubMed2001

Dementia: the University of Oklahoma autopsy experience.

The brain from 98 consecutive patients with the clinical diagnosis of dementia were examined at autopsy in a standardized fashion. Alzheimer's Disease was present in 79 of the cases, 76%, but represented the only diagnosis in 41%. Thus, almost 60% had another associated pathologic disorder. Cerebral amyloid angiopathy (CAA) represented the single largest subset, present in 25 cases. 40% were accompanied by either 1) small, microscopic infarcts or cortical scars, or 2) small collections of macrophages containing hemosiderin or small hemorrhages. CAA occurred with both atherosclerotic cortical infarcts and arteriolosclerotic subcortical pallor or lacunar infarcts. Alzheimer's Disease occurred with Diffuse Lewy Body (DLB) Disease in 13 cases. DLB Disease did not occur as a distinct entity, and thus may represent the second largest subset of Alzheimer's Disease. Both Alzheimer's Disease and DLB Disease accounted for dementia in Parkinson's Disease. Almost 25% of all cases had a disorder other than Alzheimer's Disease.

Alzheimer Disease↗
PubMed1999

Pediatric eighth cranial nerve schwannoma without evidence of neurofibromatosis.

Schwannomas of the eighth cranial nerve are rare in children. We report a 4 10/12 - year-old girl with no evidence of neurofibromatosis who presented with facial droop. Radiographic studies revealed a large cerebellopontine angle tumor. At surgery, the tumor was attached to the eighth cranial nerve and histologically was a schwannoma. This is the youngest reported case of unilateral eighth cranial nerve schwannoma in a patient without the stigmata of neurofibromatosis.

Child, Preschool↗
PubMed1998

Alzheimer's disease as a defect of neuronal autotrophism: a hypothetical analogy with amateur radio operation.

Amyloid precursor protein appears to be a signaling protein that plays a role in neuronal autotrophism, indicating integrity of the nerve terminal and synapse. Analogous to amateur radio operation with a damaged antenna in which further attempts to improve signal propagation can result in damage to the radio equipment, abnormal signaling by the secreted amyloid precursor protein stimulates compensatory metabolic activity in the neuron that ultimately leads to paired helical filament formation (neurofibrillary tangles) and further neuronal dysfunction and death.

Alzheimer Disease↗
PubMed1998

Primary intracerebellar osteosarcoma arising within an epidermoid cyst.

The authors report a case of a primary extraskeletal osteosarcoma arising within an epidermoid cyst in the parenchyma of the cerebellum in a 64-year-old woman. On initial presentation, the tumor involved the midline cerebellum without attachment to the surrounding dura mater or calvarium. Complete medical and radiologic evaluation failed to reveal a primary skeletal or other extraskeletal osteosarcoma. To our knowledge, this is the first reported case of a primary extraskeletal osteosarcoma within the cerebellum. Osteosarcoma as a primary brain tumor is exceedingly rare, and only three cases (all occurring within the cerebral hemispheres) have been reported previously. The histogenesis of primary sarcomas of the brain is not evident. The associated finding of an epidermoid cyst suggests the tumor originated from a teratoma.

Cerebellar Diseases↗
PubMed1995

Rhabdomyolysis following electrical injury.

Severe electrical injury is often associated with acute rhabdomyolysis, evident from massively elevated serum creatine (CK) levels, along with presence of other muscle fiber constituents in the serum and urine, resulting specifically in hyperkalemia, hyperphosphatemia, and myoglobinuria. The acute medical care of the patient with electrical injury must include addressing supportive therapy for the rhabdomyolysis (more fully reviewed in other articles in this issue of Seminars), but understanding the underlying pathophysiology of rhabdomyolysis may allow for the future development of improved therapeutic modalities.

Animals↗
PubMed1994

In situ DNA hybridization study of 'primary' cytomegalovirus (CMV) oophoritis.

We report the case of a 50 year old woman with metastatic breast carcinoma refractory to chemotherapy who died of candidal septicemia after autologous bone marrow transplantation. Although there was no apparent active cytomegalovirus (CMV) infection (negative cultures and serology for active infection), autopsy revealed histologic evidence of CMV inclusions limited to both ovaries. DNA in situ hybridization was performed on multiple organs, and additional foci of infection in one fallopian tube and the adrenal glands were detected. Previous reports of isolated CMV oophoritis may represent sampling error. An ascending route of infection is suggested. Tubo-ovarian changes due to CMV infection may occur more frequently than suspected; they are difficult to diagnose because even actively CMV infected cells may not be detected by routine histology alone, and because, after the active infection 'heals', no evidence of the virus can be found on histologic examination.

Adrenal Gland Diseases↗
PubMed1994

Alzheimer's disease: pathophysiology and the hope for therapy.

The approximately 4.5 million Alzheimer's disease victims in the United States represent a major public health problem resulting in annual expense topping $100 billion, with the Oklahoma share being about $500 million. This problem will be even larger as the baby boomer generation reaches the ages of maximum prevalence of Alzheimer's disease. Research has provided only meager insights into this devastating disease, but has permitted some rational hypotheses concerning potential treatment. Still, the definitive diagnosis of Alzheimer's disease requires pathologic confirmation. In interviews with families following the autopsy, it is apparent that the disease is poorly understood by both the family members and many of the health care workers with which they have dealt. Thus, this review (based upon the questions raised by families and their physicians) examines the currently understood mechanisms and pathogenesis of Alzheimer's disease, the hereditary patterns, and the hope for therapy.

Aged↗
PubMed1993

Midline cerebral dysgenesis, dysfunction of the hypothalamic-pituitary axis, and fetal alcohol effects.

OBJECTIVE: Neuropathologic evaluation was performed on an infant with fetal alcohol effects. DESIGN: Coronal brain sections and representative tissue blocks stained with hematoxylin-eosin, silver stain, and immunocytochemical stains for hypothalamic and pituitary hormones were evaluated for neuropathologic abnormalities. PATIENT: A 2.5-month-old American Indian girl who had been exposed to first-trimester maternal binge alcohol abuse died after persistent problems of growth failure, sodium imbalance, aberrant temperature regulation, respiratory distress, and seizures. RESULTS: Autopsy revealed severe microcephaly, hypertelorism, midfacial hypoplasia, a high-arched palate, shortened palpebral fissures, and a small brain. The frontal lobes were fused anteriorly; olfactory bulbs and tracts were absent; and optic nerves were hypoplastic. An enlarged and bulbous hypothalamus obscured the pituitary gland. The thalamus and caudate nuclei were fused across the midline. Posteriorly, the single ventricle split to form rudimentary lateral horns. The anterior corpus callosum, septum pellucidum, fimbria, and fornices could not be identified. The anterior commissure and supraoptic nuclei were microscopically present. Many Purkinje cells were horizontally positioned, with abnormal dendritic structure. The posterior pituitary lobe was absent, and the infundibulum was flanked by a hypoplastic adenohypophysis and a large subarachnoid heterotopia. Immunocytochemical studies identified only vasopressin and neurophysin in the hypothalamus and only growth hormone and prolactin in the pituitary gland. CONCLUSION: To our knowledge, an association between fetal alcohol effects and a complex cerebral anomaly with features of incomplete holoprosencephaly and septo-optic dysplasia has not previously been reported and suggests a possible common pathogenesis needing further study.

Brain↗
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↗