Faculty Bibliography

A child with infantile sialic acid storage disease is reported. Ultrasonography demonstrated fetal ascites. At birth, the infant appeared hydropic and presented with numerous dysmorphic features, including sparse white hair, coarse facies, hypertelorism, epicanthal folds, anteverted nostrils, and a long philtrum. In addition, he had visceromegaly, bilateral inguinal hernias, and a slight gibbus deformity. Lymphocytes were vacuolated and bone marrow contained large numbers of foam cells. There were generalized vacuolations of both reticuloendothelial and parenchymal cells in the examined tissues. Neuropathologic studies revealed wide-spread neuronal storage, myelin loss, axonal spheroids, and gliosis. Neurons, endothelial cells, and Kupffer cells stained with wheat germ agglutinin indicated an accumulation of sialic acid. Free sialic acid was significantly increased in urine and serum, as well as in liver, heart, and brain tissues. The alpha-neuraminidase activity was normal. It is assumed that the basic defect of infantile sialic acid storage disease lies in impaired transport of sialic acid across the lysosomal membrane

A detailed neuropathological and biochemical study was performed to evaluate the accumulation of ceramide trihexoside within the central and peripheral nervous systems of 2 patients with Fabry's disease. Luxol fast blue-staining lipid was noted in the leptomeninges and in the choroidal stroma; biochemical studies showed increased quantities of ceramide trihexoside in the cerebrospinal fluid. The permeable blood-brain barrier regions of the central and peripheral nervous systems contained increased quantities of ceramide trihexoside. Some central nervous system nuclei associated with autonomic function were also noted to store lipid. Other areas of increased ceramide trihexoside accumulation included specific cortical and brainstem structures. Possible sources for this selective accumulation of ceramide trihexoside within the central and peripheral nervous system include transport of glycolipid from the systemic vascular network and retrograde transsynaptic glycolipid transport

Human blood-derived macrophages were cultured in the presence of conduritol-B-epoxide, a specific inhibitor of beta-glucosidase, to induce changes resembling those occurring in the cells of patients with Gaucher's disease. After 24 hours of incubation, only 5% of the original beta-glucosidase activity remained; on removal of the inhibitor, the enzyme activity recovered almost fully to control levels after 5 days. After 30 days of incubation with conduritol-B-epoxide, the macrophages contained almost 10 times as much glucocerebroside as the untreated controls, and the cells displayed morphologic changes reminiscent of Gaucher's cells. This in vitro system may enable detailed studies on the pathogenetic mechanisms associated with glucocerebroside accumulation in human macrophages as well as on the turnover of the accumulated substrate and reversal of the morphologic abnormalities on removal of the inhibitor

Acidic alpha-mannosidase deficiency has been identified in a family of Blue Persian cats. Characterization of the residual activity revealed that the Km for the substrate, 4-methylumbelliferyl-alpha-D-mannoside, increased approximately three-fold with a severe deficiency in Vmax (1-2%) in homogenates of liver and brain of affected cats compared with controls. The residual activity at pH 4.0 in liver homogenates from affected cats is very thermolabile at 51 degrees C while the control activity is stable at this temperature for 1 h. Subcellular fractionation of liver was performed from a control and diseased cat in order to compare the properties of the different alpha-mannosidases localized in these fractions. The residual activity present in the lysosomal fraction from diseased cat liver showed altered pH optimum, two-fold increase in Km with a severely reduced Vmax and increased thermolability compared with the activity in the lysosomal fraction from control liver. The thermal inactivation pattern and Km of the residual activity in the lysosomal fraction is different from the non-lysosomal alpha-mannosidase in the liver of the affected cat. This suggests that the residual activity in the lysosomal fraction of the liver from the affected cat is not due to contamination of non-lysosomal alpha-mannosidase in this fraction. Whether this residual activity represents the properties of the mutant enzyme or yet another minor normal component of lysosomes different from the major inactive mutant or absent lysosomal enzyme remains to be elucidated

Neuronal ceroid-lipofuscinosis is the most common class of neurodegenerative disease in children. After decades of study, the biochemical basis for this group of diseases continues to elude scientists. One obstacle has been the difficulty in establishing specific criteria for diagnosis. This paper reviews case material from 65 patients referred to the Shriver Center for study from January, 1984 to December, 1986. The late-infantile type was the most commonly encountered (35%) with a mean age-of-onset of 3.1 +/- 0.5 yr. The juvenile type was slightly less frequent (32%) with a mean age-of-onset of 7.8 +/- 4 yr. The infantile type ranked third (23%); age-of-onset 11 +/- 4 months) and the adult form of the disease was the least common (10%; age-of-onset 25 +/- 4 yr). Consistent clinical findings were a progressive decline in mental faculties and seizures, predominantly of the myoclonic type. Neuroradiological changes of cerebral and cerebellar cortical atrophy were common when studies were obtained more than a year after clinical onset. Ataxia was a frequent manifestation in the late-infantile and juvenile types whereas dystonia was unique to the latter. There was a diversity of ultrastructural findings in skin biopsies between and within types. The absence of findings in a few familial cases necessitated sampling a second tissue such as muscle, particularly when the history was suggestive and urine dolichols were high. Elevated urine dolichol levels was a nonspecific but helpful finding

Lysosomal alpha-mannosidase activity, oligosaccharide profiles, light and electron microscopy and lectin histochemistry studies were performed on full-term placentae obtained from five litters of cats. They resulted from breeding related cats who are obligate heterozygotes for lysosomal alpha-mannosidase deficiency. alpha-Mannosidase activity in placentae from affected kittens was less than 10 per cent of control, while in placentae from presumptive heterozygotes the activity was less than 50 per cent of control. High-pressure liquid chromatographic analysis of oligosaccharides revealed massive accumulation of undegraded oligosaccharides in placentae of affected kittens. A small elevation was found in placentae from presumptive heterozygous kittens, and none was detected in placentae of normal kittens. Light and electron microscopic examinations revealed vacuolization of fetal endothelial and mesenchymal cells only in placentae of affected kittens. Succinylated wheat germ agglutinin and concanavalin A stained the fetal fibroblasts only in placentae of affected kittens