Tomochika Kato

Hypersialyloligosacchariduria in mucolipidoses: a method for diagnosis.

A method is described for the detection of abnormal oligosaccharides in a small (5 ml) volume of urine, employing filtration on a Bio Gel P-6 column, determination of neutral sugar and bound sialic acid, and determination of creatinine content. With this method increased urinary excretion of sialic acid-rich oligosaccharides has been detected in nine patients with mucolipidoses (five cases of mucolipidosis II and four patients of mucolipidosis, with beta-galactosidase deficiency). The filtration patterns of oligosaccharides in mucolipidoses were clearly distinguishable from those in other inborn errors of metabolism. Total excreted oligosaccharides were increased 5--30-fold in these patients; mucolipidosis II, 640--1350 microgram neutral sugar/mg creatinine; control 54 +/- 20 microgram neutral sugar/mg creatinine. The oligosaccharides consisted of three sialic acid-rich fractions and were common in both types of mucolipidosis. Our data indicate that hypersialyoligosacchariduria is the main biochemical feature of both types of mucolipidosis.

A case of neuraminidase deficiency associated with a partial β-galactosidase defect

Neuraminidase deficiency towards fetuin, 2→3 sialyllactose and 2→6 sialyllactose was found in cultured skin fibroblasts from a 10-year-old Japanese girl who exhibits craniofacial dysmorphism, a short neck, vertebral and pelvic deformities and macular cherry-red spots. Neuraminidase deficiency in this case seems the primary enzyme defect because the enzyme activity of her parents was intermediate. In addition, β-galactosidase in leukocytes and cultured skin fibroblasts from the patient was found to be severely deficient, but could be detected in serum and urine. In the parents, β-galactosidase activity was normal. There were moderately increased levels of urinary sialic acid-rich oligosaccharides and glycopeptides in the patient. The clinical and biochemical observations suggest that this case is very close to mucolipidosis I.

The effects of sucrose loading on lysosomal hydrolases.

SummaryThe addition of 88 mM sucrose to the culture medium of human skin fibroblasts from normal subjects caused remarkable increase in the intracellular lysosomal hydrolase activities. The mechanism of this induction by sucrose loading was carefully studied with several fibroblast strains of different inherited lysosomal storage disorders. In single lysosomal hydrolase defect such as GM1-gangliosidosis, mannosidosis and Sandhoff disease, no induction of the deficient hydrolase was found with 88 mM sucrose loading. In contrast, sucrose loading caused normalization of intracellular lysosomal hydrolase activities in I-cell disease fibroblasts and cytoplasmic inclusion materials disappeared. Subsequent investigations reveal that I-cell disease cells are classified into three subgroups by the degree of hydrolase induction by sucrose loading; a high responding, an intermediate responding and a no-response group. The heterogeneity may be based upon different induction by sucrose loading of the enzyme, probably the residual phosphotransferase which is involved in the processing steps of lysosomal enzyme molecules. With the addition of mannose-6-phosphate and 10 mM NH4Cl to cultured skin fibroblasts, it was shown that sucrose loading caused increased synthesis of lysosomal enzyme proteins. The result of the test with 2,4-dinitrophenol suggests that sucrose is indeed pinocytosed by cultured human skin fibroblasts and localized in lysosomes and that this event is the essential factor to trigger the induction of lysosomal hydrolases. Simultaneous loading of both invertase and sucrose in cultured cells caused no induction of α-mannosidase activity. This result indicates that invertase is also pinocytosed, reaches the lysosomes and hydrolyzes sucrose in the lysosomes. Lysosomal overloading with sucrose resulted in induction of lysosomal hydrolases and invertase blocked the induction of α-mannosidase activity. However, some induction still exists in β-galactosidase and α-fucosidase activity. Thus it is very likely that the induction of lysosomal hydrolases demands a complicated process.In this article, we investigated the effects of sucrose on the lysosomal hydrolases in cultured human skin fibroblasts of several inherited lysosomal storage disorders and normal subjects and discuss the possible mechanism. of the induction of lysosomal hydrolase activities by sucrose loading.

Beta-galactosidase deficient-type mucolipidosis: A complementation study of neuraminidase in somatic cell hybrids

Abstract By cell fusion with polyethylene glycol (PEG) a remarkable increase of neuraminidase activity was observed in the fused cells between ML-II and other two neuraminidase deficient disorders, ML-Gal (mucolipidosis, galactosidase deficient type) and ML-I (mucolipidosis I). No complementation was found in the combination of ML-I and ML-Gal. This result suggests that ML-I and ML-Gal may be allelic mutations and belong to the same genetic disorder as a primary neuraminidase deficiency.

A severe infantile sialidosis (β-galactosidase-α-neuraminidase deficiency) mimicking GM1-gangliosidosis type 1

We observed a 3-month-old Japanese female infant with severe psychomotor retaration, coarse facial appearance, hepatosplenomegaly, and dysostosis multiplex. Only β-galactosidase was found to be deficient when the routine lysosomal hydrolase assay was performed on the patients lymphocytes at 6 months of age. At first GM1-gangliosidosis type 1 seemed the most likely diagnosis. Later, however, additional studies (hydrolase assay in cultured skin fibroblasts, urinary oligosaccharide analysis, genetic complementation study, etc.) revealed that biochemical data of this case were in agreement with those of severe infantile sialidosis. The only important exception was that α-neuraminidase in the patients lymphocytes showed normal activity but abnormal pH dependence toward 4-methylumbellyferyl substrate. In addition, a severely damaged kidney suggested that his case may be classified as a unique type of severe infantile sialidosis (possible nephrosialidosis). These observations stress the importance of careful biochemical diagnosis of a case with GM1-gangliosidosis type 1 phenotype.

Real-World Event Detection Using Flickr Images

This paper proposes a real-world event detection method by using the time and location information and text tags attached to the images in Flickr. Events can generally be detected by extracting images captured at the events which are annotated with text tags frequently used only in specific times and locations. However, such approach can not detect events where only a small number of images were captured. We focus on the fact that semantically related events often occur around the same time at different locations. Considering a group of these events as an event class, the proposed method firstly detects event classes from all images in Flickr based on their similarity of the captured time and text tags. Then, from the images consisting each event class, events are detected based on their similarity of the captured locations. Such two-step approach enables us to detect events where a small number of images were captured.

Ultrastructural study on nervous system of fetus with GM1-gangliosidosis type 1

SummaryThe nervous system of a 22-week-old fetus with GM1-gangliosidosis type 1 was studied by electron microscopy. The tissues thus examined were the cerebral cortex at the parietal region, the cerebellum, the thoracic spinal cord, the Auerbachs myenteric plexus in the large intestine and the radial nerve fibers. In the cerebral cortex, membrane-bound vacuoles, which occasionally contained stacks of fine fibrils, were observed in the large young neurons in the deeper part of the cortical plate. The neurons in the other part of the cerebral cortex carried no storage materials. In the cerebellum, the membrane-bound vacuoles with stacks of fine fibrils were seen only in the Purkinje cells. The neurons in the spinal cord also contained several zebra-like bodies and the above membrane-bound vacuoles. As for the peripheral nervous system (PNS), neurons in the Auerbachs myenteric plexus carried membranous cytoplasmic bodies and zebra-like bodies. Some of the axons in the radial nerve fibers also contained a lot of pleomorphic electron-dense bodies and a few membranous cytoplasmic ones. These results show that the accumulation of storage materials is started in the large neurons which are produced in the early stage of neurogenesis in the central nervous system (CNS). Additionally, the observed membrane-bound vacuoles are considered to be structures which occur before the membranous cytoplasmic bodies and/or the zebra-like bodies. It is also elucidated that the PNS is affected earlier than the cerebral and cerebellar cortices and thoracic spinal cord.

The complementation of β-galactosidase in fused cells of mucolipidosis II with another variants of β-galactosidase deficiency using new single cell enzyme assay

Abstract By cell fusion and new single cell hydroalse assay technique, the complementation was observed between mucolipidosis II and other two hereditary lysosomal β-galactosidase deficient disorders, GM 1 -gangliosidosis, type 2 and β-galactosidase deficient-type mucolipidosis. The possible mechanisms with which abnormal ML-II β-galactosidase was modified and normalized by other two different cell strains were discussed.

Properties of sulfatases in cultured skin fibroblasts of multiple sulfatase deficient patients

Various sulfatase activities were assayed in cultured skin fibroblasts from patients with multiple sulfatase deficiency (MSD). MSD cell lines displayed deficiencies of arylsulfatase A and iduronate sulfatase, but activities of arylsulfatase B, N‐acetylgalactosamine 6‐sulfate sulfatase and N‐acetylglucosamine 6‐sulfate sulfatase were within normal ranges, but not consistently. Arylsulfatase A, minor anionic arylsulfatase and N‐acetylgalactosamine 6‐sulfate sulfatase in MSD cell lines had similar Km, pH optima, inhibitory or activator sensitivity to that of normal skin fibroblasts. Arylsulfatase B in MSD cell lines also had properties similar to that of normal skin fibroblasts, except an abnormal heat stability. From our results, we conclude that properties of arylsulfatase A, minor anionic arylsulfatase and N‐acetylgalactosamine 6‐sulfate sulfatase in MSD fibroblasts were intact. On the other hand, arylsulfatase B in MSD might be a functionally abnormal enzyme.

Degradation of keratan sulfate by ß‐N‐acetylhexosaminidases in GM2‐gangliosidosis

We have prepared a new substrate from a keratan sulfate‐derived‐oligosaccharide (2‐acetamido‐2‐deoxyglucosyl(1–3)‐[1‐3H] Galactitol), which is necessary to measure β‐N‐acetylhexosaminidase activity. This substrate was prepared from a cornea keratan sulfate by digestion with endo‐β‐galactosidase, followed by isolation of disaccharide on gel filtration chromatography and chemical desulfation. Using this substrate, we found that a striking deficiency of β‐N‐acetylhexosaminidase activity was present in the skin fibroblasts of patients with Sandhoff disease but not in Tay‐Sachs disease. Both β‐N‐acetyl‐hexosaminidase A & B contributed to the catabolism of keratan sulfate.