Search PubMed⌕ Search

Biomedical subjects

R W Leech

Publications and source records attributed to R W Leech.

72 records · Page 4Linked to original sources
PubMed1974

Subependymal and intraventricular hemorrhages in the newborn.

The pathogenesis of intraventricular hemorrhage in the newborn includes that of subependymal hemorrhage (SEH), the single most common pathologic alteration seen in the brains of 417 consecutively autopsied infants. A clearly recognizable relationship of SEH to gestational age and clinical status exists in that all SEH occur in premature infants under 2500 g birthweight (although only 56% of all premature infants have SEH) and 95% of SEH occur in infants with the respiratory distress syndrome (although only 60% of infants with the respiratory distress syndrome have SEH). The pathogenesis appears to involve a combination of hypoxia, metabolic acidosis, venous stasis and rupture of the thin-walled veins so prominent in the germinal matrix.

Birth Weight↗
PubMed1974

Morphologic variations in periventricular leukomalacia.

Periventricular leukomalacia (PVL) usually is manifested as discrete foci of coagulation necrosis of the deep periventricular white matter in the human neonatal brain. During the examination of the brains of 116 infants utilizing an oil red O technic on gelatin-embedded frozen sections, 25 cases of PVL were found with typical foci of coagultion necrosis. Three morphologic varieties of the lesion could be demonstrated. In the first type, rather than being restricted to the periventricular zone, the discrete necrotic foci extended throughout the entire zone of cerebral white matter, even out to just beneath the cortex. The subcortical lesions appeared of short duration, whereas older lesions were always present nearer the ventricle. The second type of lesion presented as linear, some-what serpentine zones of coagulation necrosis radiating into the cerebral white matter. A third type of lesion consisted of a variegated irregular coagulation necrosis which was poorly delineated from more normal tissue. Diffuse pallor of the white matter, the nature of which is still not clear, was associted with the more severe lesions. Although the pathogenesis of PVL is unknown, it is suggested that these new varieties of PVL beyond the discrete periventricular foci of necrosis would be more apt to result in a diffuse loss of white matter and hence mental retardation if the child should survive.

Birth Weight↗
PubMed1974

Glial fatty metamorphosis. An abnormal response of premyelin glia frequently accompanying periventricular leukomalacia.

Within the developing nervous system, there is a complex relationship between the accumulation of sudanophilic lipids in glial cells and gestational and postnatal age. Sudanophilic lipids accumulate to a small degree as a stage of normal premyelin lipogenesis, but large amounts of such accumulations may be considered abnormal. The dividing line between the normal and the abnormal (glial fatty metamorphosis) must be defined for each region of the nervous system, since the time and rate of myelination vary widely. Examination of the brains of premature infants routinely coming to autopsy utilizing the oil red O technic on gelatin-embedded frozen sections has allowed this definition to be made in at least some situations. Glial fatty metamorphosis is characterized by an absolute increase in the amount of lipid droplets in the glial precursor cells and by an absolute increase in the ratio of lipid-containing cells to the total cell population. It is more easily recognized in the corpus callosum in cases of periventricular leukomalacia, but may occur in other disease states, and appears to represent a response of metabolically active immature glial cells to metabolic stress (hypoxia-acidosis).

Age Factors↗
PubMedDate not supplied

Cerebral degenerations producing dementia: importance of neuropathologic confirmation of clinical diagnoses.

Dementia is a major public health concern with our increasing elderly population and currently affects more than three million Americans at an annual cost of $50 billion. The marked overlap in symptomatology between Alzheimer's disease and other primary parenchymal degenerations makes antemortem diagnosis based on clinical assessment tentative at best, with error rates of 25% commonly reported. Accurate diagnosis is of vital importance in order to improve our understanding of these illnesses, evaluate potential therapies, and provide 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. To illustrate the importance of these principles, we present three patients who were clinically diagnosed with Alzheimer's disease, and subsequently found to have other dementing illnesses by careful postmortem neuropathologic examination.

Adult↗
PubMedDate not supplied

Pituitary adenoma: a DNA flow cytometric study of 192 clinicopathologically characterized tumors.

A clinically, immunohistochemically and ultrastructurally characterized series of 192 pituitary adenomas was analyzed for DNA content by flow cytometry. Results were assessed not only relative to tumor immunotype, size, and invasiveness, but also with frequency of recurrence. Case selection was non-random; males predominated (1.8:1) and the ratio of macro-to-microadenomas was 4.2:1. Female patients were slightly younger and, in all adenoma categories, less often had invasive tumors: PRL (15%/30%), ACTH (17%/44%), LH/FSH (8%/27%) and null cell adenomas (0%/27%). With the exception of prolactin cell adenomas, similar proportions of macroadenomas and invasive tumors in all tumor subtypes were diploid and non-diploid. Prolactin adenomas differed in that tumors of males showed a high rate of non-diploidy (65%); such tumors were predominantly macroadenomas, but only 28% were invasive. Among GH-containing tumors 78% were macroadenomas, 40% were nondiploid, and the frequency of invasive macroadenomas was higher (49%) than in PRL tumors (21%). ACTH adenomas were mainly microadenomas (81%), their rate invasion (29%) and of non-diploidy being low (14%). Among "non-functioning" (LH/FSH, null cell adenomas), LH/FSH-producing tumors were all macroadenomas, but with low rates of invasion (23%) and non-diploidy (9%). Null cell adenomas, nearly all macroadenomas, had similar low invasion rate (21%), but were more often non-diploid (39%). In all adenoma subgroups S-phase fractions were higher in non-diploid adenomas by an overall ratio of 2.1:1. Prolactin adenomas showed the highest (15.2%) and LH/FSH adenomas the lowest (5.6%) mean S-phase fraction. When compared to long-term follow-up, neither this parameter nor ploidy correlated with tumor size or invasiveness. Lastly, long-term follow-up showed ploidy to be an unreliable predictor of tumor persistence or recurrence.

Adenoma↗
PubMedDate not supplied

Thalamic dementia: an example of primary astroglial dystrophy of Seitelberger.

Pure thalamic dementia is highly uncommon and typically demonstrates widespread loss of neurons throughout the thalamus associated with reactive gliosis. This report describes an autopsy case in which there is widespread gliosis of subcortical white matter, focal hippocampal sclerosis and a unique proliferation of protoplasmic astrocytes in the thalamus, with limited bilateral focal loss of neurons. The alterations of the protoplasmic astrocytes consist of proliferation of perivascular feet surrounding blood vessels and velate sheets which surround individual neurons. It is proposed that the astrocytic alterations, or astrocytic dystrophy, constitute the primary and critical pathologic-change, sufficiently severe to produce dementia in the presence of a relatively intact neuronal population.

Aged↗
PubMedDate not supplied

Perineurial cell ensheathement of muscle fibers: a new syndrome of fatigable muscle weakness mimicking myasthenia gravis.

Many newly discovered pathological and physiological variants of neuromuscular junction function have been identified. We report a case of a myasthenia gravis-like syndrome with onset of ptosis at age six years and eventual evaluation for peripheral weakness twenty years later. Subsequent muscle biopsy showed a previously unreported finding of perineurial cell ensheathement of the muscle fibers. We suggest that the ensheathement of the muscle cells by perineurial cells may alter the microenvironment interfering with neuromuscular transmission.

Adult↗
PubMedDate not supplied

Primary intracranial choriocarcinoma: a case report.

A 10-year-old girl had a primary choriocarcinoma of the posterior third ventricle. Craniotomy a few hours before death did not yield any tumor tissue. At autopsy, an extensively hemorrhagic tumor abutted the pineal gland. Immunostains were positive for beta-human chorionic gonadotropin (beta-HCG) but were negative for alpha-fetoprotein and carcinoembryonic antigen. The presence of beta-HCG in serum or cerebrospinal fluid may be used as a diagnostic marker and monitor of therapy. HCG is, however, not a unique marker for trophoblastic neoplasms, as a significant number of intracranial germinomas contain cells that are beta-HCG positive. Because of the rarity of primary extragenital choriocarcinomas and the much more common occurrence of metastases of genital choriocarcinomas, it is doubtful whether any investigation less than detailed autopsy can prove the extragenital origin of the tumor.

Cerebral Ventricle Neoplasms↗
PubMedDate not supplied

Etiology of pituitary apoplexy: review and case presentation.

Pituitary apoplexy is an acute neurologic emergency typically occurring in patients who suffer rapid and fatal expansion of a pre-existing adenoma. We report an example of pituitary apoplexy secondary to necrotizing hypophysitis due to a mycobacterial or tuberculous infection with limited systemic infection.

Adult↗
PubMedDate not supplied

Agenesis of cerebellum associated with arrhinencephaly.

Complete cerebellar agenesis or aplasia is an extremely rare condition with few previously reported cases. We identified a 38-week gestation infant with microcephaly who had complete cerebellar agenesis associated with arrhinecephaly. There was complete lack of the efferent and afferent limbs of the cerebellum, including the nuclei of the basis pontis, the inferior olivary nuclei, ascending spinal and medullary afferents, deep cerebellar nuclei and their afferents, and the red nucleus. Although complete cerebellar agenesis is rare, cerebellar hypoplasia is more common and can be sporadic, asymmetric, or represent clinically, genetically, and pathologically diverse examples of primary cerebellar or vermian hypoplasia.

Cerebellum↗