Presence of immunoreactive material in Niemann-Pick type A placenta using anti-sphingomyelinase rabbit gammaglobulins

Human placental sphingomyelinase was highly purified through an original six-step scheme in order to raise a specific rabbit anti-sphingomyelinase antibody. Pure enzyme preparations showed specific activities ranging between 100 and 150 mumol/h per mg protein and gave two constant silver-stained bands (Mr 70,000 and 57,000) on acrylamide after electrophoresis under denaturing conditions. These two bands were the sole areas detected by the described antibody on Western blots from normal placental preparations at various stages of purification. A similar procedure was applied to the separate study of placental sphingomyelinase from two prenatally diagnosed foetuses with confirmed Niemann-Pick disease type A. During purification, the mutant enzyme could be followed owing to its minute but measurable level of catalytic activity, and behaved normally at the various chromatographic steps. In the purified preparations, specific activities of 0.18 and 0.49 mumol/h per mg protein, respectively, were reached. No alteration of the Km value (19 mumol/l) was observed, while the Vmax was 0.5-1% of normal. With immunostaining of Western blots obtained as above, results similar to those described for normal tissue were found, leading to the conclusion that immunoreactive sphingomyelinase is present in Niemann-Pick disease type A.

Screening of degradative enzymes from articular cartilage in experimental osteoarthritis

Sixteen rabbits were killed 12 weeks after sectioning of the right knee anterior cruciate ligament. The left unoperated knee served as a control. The surface area of fibrillated cartilage from femoral condyles and tibial plateau was evaluated and expressed as a percentage of articular surfaces area. Cartilage from the femoro-patellar surfaces was homogenized for the quantification of several degradative activities, based on the release of digested products. Acid phosphatase, several glycosidases and neutral protease activity from the operated joint cartilage were significantly elevated, while collagenolytic activity was unmodified. The percentage of fibrillated cartilage correlated positively with arylsulfatase, glucosidase and neutral protease but negatively with mannosidase and fucosidase. The results may be consistent with the hypothesis of a sequential degradative process leading to cartilage destruction.

Type C Niemann-Pick disease. Abnormal metabolism of low density lipoprotein in homozygous and heterozygous fibroblasts

The esterification of cholesterol derived from human low density lipoprotein (LDL) or fetal bovine serum (FBS) was deficient in cultured fibroblasts from subjects with heterozygous and homozygous type C Niemann-Pick (NPC) disease. Failure to significantly esterify LDL-derived cholesterol resulted in abnormal accumulation of predominantly unesterified cholesterol in homozygous NPC fibroblasts. Compared with normal and homozygous fibroblasts, heterozygous NPC fibroblasts synthesized intermediate levels of cholesteryl ester during the initial 6 h of incubation with LDL. The rate of cholesterol esterification in heterozygous cells was normal when measured over a 24-h period of incubation with LDL. In addition to demonstrating a defect in cholesterol esterification, homozygous NPC fibroblasts accumulated more total cholesterol when incubated with LDL or FBS than normal fibroblasts accumulated. When heterozygous NPC fibroblasts were incubated with LDL or FBS, cellular accumulation of cholesterol reached levels that were high-normal or intermediary between levels observed in normal and homozygous NPC fibroblasts. The partial expression of these metabolic errors in the heterozygous genotype relevantly links these errors to the primary mutation of this disorder.

Type C Niemann-Pick disease. A parallel loss of regulatory responses in both the uptake and esterification of low density lipoprotein-derived cholesterol in cultured fibroblasts

Low density lipoprotein (LDL) internalization by mutant type C Niemann-Pick (NPC) fibroblasts results in uptake of excess total cholesterol. Uptake of excess lipoprotein cholesterol appears to be mediated by the specific LDL receptor pathway. Associated with excessive LDL-cholesterol uptake is a lesion in early intracellular cholesteryl ester synthesis. In vitro acylCoA:cholesterol acyltransferase activity is normal in cell-free extracts of mutant cells. The ability of exogenous sterols to enhance intracellular esterification of [3H]mevalonate-derived [3H]cholesterol was severely limited in mutant cell cultures suggesting that in vivo activation and/or expression of activated acylCoA:cholesterol acyltransferase may be compromised by the primary mutation of type C Niemann-Pick disease. After 2 days of LDL uptake, rates of intracellular cholesteryl ester synthesis in mutant cells paralleled the rates of esterification in normal cells suggesting that specific early in vivo expression of the acyltransferase may be affected in this disorder.

In vitro assembly of rat pancreas tubulin in the presence of taxol

A rat pancreas supernatant was applied to an affinity column where colchicine analogues had been coupled to CNBr-Sepharose 4B, and subsequent elution with 0.35 M sodium chloride gave tubulin among other proteins. Incubation with 5 microM taxol, a natural plant product, resulted in the assembly of tubulin as checked by turbidimetry at 350 nm. Electron microscope observation of the structures obtained revealed (i) the presence of numerous microtubules with the same morphological parameters as brain microtubules, and (ii) that immunoreactive tubulin molecules were well-distributed along the microtubules as shown by the immunogold staining technique. Biochemical evidence indicated that the microtubules obtained were exclusively composed of tubulin, as demonstrated by slab gel polyacrylamide electrophoresis and by immunoblot staining with highly specific tubulin antibodies.

A new variant of sphingomyelinase deficiency (Niemann-Pick): visceromegaly, minimal neurological lesions and low in vivo degradation rate of sphingomyelin

Three males (aged 10 years, 3 years 9 months and 2 years 8 months) with profound sphingomyelinase deficiency are presented. The sphingomyelin storage in the liver biopsies attained 30-fold, 65-fold and 16-fold increases against controls, respectively. Levels of bis(monoacylglyceryl) phosphate were also increased. In two cases the bone marrow contained foam cells with liquid crystals of sphingomyelin. Besides the visceral involvement dominated by hepatosplenomegaly, all three cases showed discrete, so far stationary (8 years, 42 months and 28 months) neuropathic features and retinal lesions resembling the classical cherry-red spot. Electrophysiological examinations showed a variable reduction of peripheral nerve conduction velocity and prolongation of the latencies of somatosensory, visual and auditory evoked potentials. Ultrastructural examination of skin nerves showed a slight storage, mainly in Schwann cells. In some myelinated fibres there were pseudomyelinic ovoids. The cases therefore displayed features of both A and B types of sphingomyelinase deficiency and should be conventionally classified as intermediate. However, the very low levels of in vivo sphingomyelin hydrolysis (not exceeding 6%, against 30 +/- 10% in type B and 77 +/- 5% in controls) were clearly within the range of type A values (5 +/- 2%). Accordingly, we suggest that the cases may be biochemically classified as variants of type A disease.

A defect in cholesterol esterification in Niemann-Pick disease (type C) patients

The demonstration of a defect of cholesterol esterification in a mutant strain of BALB/c mice with an attendant reduction of sphingomyelinase activity [Pentchev, P. G., Boothe, A. D., Kruth, H.S., Weintroub, H., Stivers, J. & Brady, R. O. (1984) J. Biol. Chem. 259, 5784-5791] prompted us to examine the capacity of cultured human Niemann-Pick fibroblasts to esterify exogenously derived cholesterol. Cholesterol was supplied to cell cultures in the form of native or chemically modified, positively charged low density lipoprotein or as non-lipoprotein cholesterol. Cholesterol esterification was not impaired in cell cultures derived from patients with type A or B Niemann-Pick disease. However, esterification of exogenously administered cholesterol was deficient in 20 type C Niemann-Pick cell lines that were available for testing. Fluorescence histochemical staining of unesterified cholesterol in type C cells suggested that these cells were able to internalize and lysosomally process lipoprotein cholesterol. Acyl-CoA:cholesterol acyltransferase activity did not appear deficient in type C cell extracts. The error in cholesterol esterification may provide an opportunity for probing the molecular lesion in this disorder and may afford a useful and reliable means for establishing diagnosis.

Niemann-Pick disease type B: first-trimester prenatal diagnosis on chorionic villi and biochemical study of a foetus at 12 weeks of development

First-trimester prenatal diagnosis of Niemann-Pick disease type B was successfully achieved by sphingomyelinase assay on chorionic villi, performed directly and after 3 weeks' culture. Cultured chorionic cells were normally found to exhibit sphingomyelinase activities 3 times higher than seen in the solid biopsy, and showed a lower residual activity in the affected foetus. Their study may thus prove helpful in dubious cases. Enzyme activities and lipid patterns were studied in several organs of the aborted foetus. Lysosomal sphingomyelinase was deficient in all tissues. The lipid pattern of the brain was normal for the age, but a 4-fold sphingomyelin storage had already taken place in the liver (2.5-fold in the spleen) of this 12-gestational week foetus.

Biochemical studies in Niemann-Pick disease. III. In vitro and in vivo assays of sphingomyelin degradation in cultured skin fibroblasts and amniotic fluid cells for the diagnosis of the various forms of the disease

Sphingomyelinase activities were assayed in vitro in cultured skin fibroblasts of 61 patients with Niemann-Pick disease (NPD). Residual activities found in type A and B were 1% and 4%, respectively, of the mean control values, i.e. significantly higher in type B. In 27 cases with NPD type C, the mean activity was 42% of that in controls, with residual activities ranging from 15% up to normal. Fifteen pregnancies at risk for NPD type A and B were monitored; 4 affected foetuses were found. The uptake of exogenously added radiolabelled sphingomyelin by cultured cells and metabolism of the choline moiety of this lipid were studied in 35 patients with NPD and 14 controls. No difference of uptake between normal and mutant cells was observed. Normally, 77 +/- 5% of the radioactivity taken up was converted to phosphatidylcholine after 18 h incubation, compared to 5 +/- 2% (n = 7) in NPD type A. A substantially greater hydrolysis (31 +/- 12%; n = 8) occurred in NPD type B, and the test allowed complete discrimination between these two types. In NPD type C, 16 patients showed an abnormally low rate of intracellular sphingomyelin degradation (48 +/- 5%) while 4 others were not distinguishable from controls. There was a correlation (r = 0.76) between the results of the in vitro and in vivo assays, but also between the severity of the clinical symptoms and the impairment in sphingomyelin degradation. For the diagnosis of NPD type C, the in vivo test gave more reproducible and more clearcut results than the in vitro assay.

Juvenile dystonic lipidosis (variant of Niemann-Pick disease type C)

In two siblings affected with dementia, epilepsy and vertical supranuclear ophthalmoplegia, foam cells and sea-blue histiocytes were found in the bone marrow. Electron microscopy of skin and neuromuscular biopsies gave presumptive evidence in favour of a storage disorder. Postmortem examination of both cases revealed an intraneuronal polymorphous lysosomal storage in the central nervous system (in the cortex and in many nuclei e.g. the substantia nigra and the reticular formation of the brain stem). In the visceral organs with the spleen most severely affected, the inclusions had a different ultrastructure, being composed of tightly apposed leaflets. The biochemical study revealed accumulation of sphingomyelin and other lipids in liver and spleen, with normal sphingomyelinase activities, which is consistent with the diagnosis of Niemann-Pick disease type C. In the brain, the most striking abnormalities involved the glycolipids. Sphingomyelinase activities were unchanged in cultivated skin fibroblasts. These data compared with those of reported cases, allowed the following conclusions to be made: (1) although the combination of clinical features appears to be unique, none of them, when considered separately, is pathognomonic for juvenile dystonic lipidosis; (2) diagnosis during life can be suggested by careful examination of nerve bundles and fibroblasts with the electron microscope, although the method of choice appears to be the study of bone marrow; but final assessment of the diagnosis, in the absence of demonstrable enzymic deficiency, requires in most cases a study of the lipid profile in a liver biopsy (or better, spleen tissue whenever available); (3) the intralysosomal storage is different, both morphologically and biochemically, in the central nervous system and in the spleen; (4) juvenile dystonic lipidosis represents a juvenile variant of Niemann-Pick disease type C, pending the discovery of the primary defect responsible for this disorder.

Rat pancreas actin: purification and characterization

Isolation of rat pancreas actin was performed with three different technics: polymerization-depolymerization method, affinity chromatography on DNase I-Sepharose 4B or ion exchange chromatography on DEAE-cellulose. Inhibition of DNase I activity, localization by SDS polyacrylamide slab gel electrophoresis and presence of microfilaments allowed its identification. Affinity process led us to obtain actin which kept inhibitory activity (30,000 U per mg) on DNase I when using vacuum dialysis. Actin eluted from DEAE-cellulose associated reversibly in 50-70 A microfilaments in the presence of phalloidin, was pure at 95% and had a satisfactory inhibitor activity (77,000 U per mg).

Chromatofocusing of skin fibroblast sphingomyelinase: alterations in Niemann-Pick disease type C shared by GM1-gangliosidosis

Sphingomyelinase activity of cultivated skin fibroblast extracts from normal individuals was resolved by chromatofocusing in the pH range 8-5 into three major components with pI's of 7.3, 6.3 and 5.9, respectively. Chromatofocusing proved a more efficient and reproducible separation technique than preparative flat-bed isoelectric focusing and it gave a constant profile even when detergent concentration varied. In skin fibroblasts from five patients with Niemann-Pick disease type C, a varying degree of reduction in the proportion of the 7.3 peak was observed. In a patient with clinical features of Niemann-Pick disease type C, the finding of such a profile would thus be a good argument for the diagnosis, but it is not pathognomonic as we found similar changes in two cases with GM1-gangliosidosis, while some cases of Niemann-Pick disease type C have borderline normal profiles. These results challenge the concept of a specific sphingomyelinase isoenzyme deficiency as the basic defect in Niemann-Pick disease type C.

Effect of tricyclic antidepressants on sphingomyelinase and other sphingolipid hydrolases in C6 cultured glioma cells

Cationic amphiphilic drugs, which include tricyclic antidepressants, have been shown to give rise to lipidoses under experimental conditions, with a general increase of lipids especially phospholipids. We report here an early and important decrease in sphingomyelinase activity in C6 glioma cells cultured in the presence of imipramine or desipramine at final concentrations of 0.01 and 0.05 mM. The effect was both dose-dependent and time-dependent and was observed before any lipid accumulation. Cerebroside beta-glucosidase and cerebroside beta-galactosidase had normal activities under the same experimental conditions and thus there was no general effect on membrane-bound sphingolipid hydrolases. A decrease of sphingomyelinase activity has been previously reported for two amphiphilic compounds, perhexiline maleate and AY 9944. These results suggest a potential function of sphingomyelinase in the mode of action of these drugs.

Chromatofocusing of purified placental sphingomyelinase

To establish the profile of the multiple forms of placental lysosomal sphingomyelinase, we have developed in a preliminary step, a new sequence of purification. This protocol has a good yield such that the final preparation is representative of the whole enzyme. Using chromatofocusing, purified sphingomyelinase is resolved into 4 major forms whose pI's are 7.2, 6.5, 5.9 and 5.2. Chromatofocusing is preferable to isoelectric focusing because it is more rapid, more reproducible and above all it provides a constant profile of activity which is not influenced by experimental conditions, in particular, detergent concentration.

Biochemical studies in Niemann-Pick disease. I. Major sphingolipids of liver and spleen

In liver and spleen specimens of 12 patients with Niemann-Pick disease types A or B, sphingomyelin was increased 15-45-fold, total phospholipids 4-10-fold and cholesterol 3-6-fold over the normal values. The storage pattern was qualitatively similar in both types but the degree of accumulation was less in type B. In Niemann-Pick disease type C (16 cases), sphingomyelin was increased 3.5-fold in liver and 6-fold in spleen. In all forms of Niemann-Pick disease, bis(monoacylglycero)phosphate was markedly elevated. Glycosphingolipids were studied in six cases with type C, three cases with type B and two cases with type A. Glucosylceramide showed the largest increase from the normal pattern in all types of Niemann-Pick disease. Highest values were recorded in type C, 14- and 35-fold normal concentrations in liver and spleen, respectively. Other neutral glycosphingolipids, particularly lactosylceramide, were also elevated, and a 2-4-fold increase of ganglioside GM3 occurred. The fatty acid profiles of the sphingolipids showed only minor alterations. In contrast to the largely dominating sphingomyelin storage found in liver and spleen of Niemann-Pick disease types A and B, the major characteristic of the lipid storage in Niemann-Pick disease type C was the absence of any prevailing accumulation and, thus, the concept of this disorder as a primary sphingomyelin storage disease is not founded.

Lipid metabolism and oxygen consumption in a hereditary demyelinating neuropathy, the trembler mouse: an in vitro study

Sciatic nerves from 15-day-old trembler and control mice were maintained in vitro up to 53 h and the metabolism of myelin lipids and the oxygen consumption were investigated [35S]Sulfate was incorporated into sulfatides at a higher rate and turned over more rapidly in trembler nerves than in controls. [14C]Galactose was incorporated into cerebrosides of trembler nerves at a lower rate and turned over like the controls. In contrast, synthesis of sulfatides labeled with [14]galactose was increased in mutants and no significant turnover was observed for both trembler and control nerves during the whole incubation period. Similar results were obtained using [3H]serine as a precursor and no significant differences were observed in the turnover rates of sphingomyelin and phosphatidylcholine between trembler and control nerves. These data suggest the presence of two different pools of cerebrosides, a small one formed by the fast recycling of sulfatides and which does not mix with a second, larger one. The rate of oxygen consumption did not change significantly during the incubation period and was 2-3-fold higher in trembler nerves than in controls, reflecting, at least partly, the increased sulfatide metabolism.

Prenatal diagnosis of Krabbe disease

Krabbe disease was diagnosed prenatally in Göteborg (Sweden) and Lyon (France) by assaying the cerebroside-beta-galactosidase activity with galactosylceramides and lactosylceramides as substrates in cultivated amniotic fluid cells. Altogether, 48 pregnancies at risk were monitored between 1972 and 1980. Ten pregnancies at risk were terminated because of a predicted affection of the fetus. Biochemical examination of material available from 7 of the 10 abortuses confirmed the diagnoses. All the remaining 36 pregnancies ended in the birth of a healthy infant. The study showed that prenatal diagnosis of Krabbe disease is difficult because of the relatively high residual cerebroside-beta-galactosidase activity in some affected fetuses. Except for the large biological variation, the enzyme activity was sensitive to variation in cultivation conditions and differed strikingly between morphologically different cell types. These two factors were controlled by including control cell samples cultivated under identical conditions and by relating the cerebroside-beta-galactosidase activity to that of two marker enzymes. The biological variation was investigated further by measuring the cerebroside-beta-galactosidase activity in cultured skin fibroblasts from infants with Krabbe disease and from their parents. Results obtained in 18 unrelated patients with Krabbe disease, 26 obligate heterozygotes and 63 controls showed a wide range of variation in enzyme activity in the controls, a large overlap between the controls and obligate heterozygotes, and a high residual activity in some patients. Nevertheless, a high residual activity in a patient was combined with a relatively high enzyme activity in the two parents. In the light of the above findings and deliberations, it appears warranted to conclude that laboratories with experienced personnel can make a reliable prenatal diagnosis of Krabbe disease and that the examination should be offered to all known couples at risk.

Use of leukocytes in diagnosis of Krabbe disease and detection of carriers

The optimal conditions for the assay of the cerebroside-beta-galactosidase deficiency in Krabbe disease were studied. Labelled galactosylceramides and lactosylceramides isolated from natural sources were both suitable substrates provided that the lipophilic moieties were identical in labelled and unlabelled portions. Galactosylceramides and lactosylceramides with uniform fatty acid compositions were also tested. The highest specific cerebroside-beta-galactosidase activities were obtained with N-palmitoyl galactosyl- and lactosylceramides. The chromogenic substrate 2-hexadecanoyl-amino-4-nitrophenyl-beta-D-galactopyranoside (HNGal) was shown to be an unreliable substrate requiring large amounts of enzyme protein and giving false normal results. Krabbe disease was diagnosed in 45 patients. With galactosylceramides as substrates the residual cerebroside-beta-galactosidase activity was 7%, with lactosylceramides 8%, and there was no overlap in enzyme activity between the 45 patients and 42 parents. Approximately 50% of the obligate carriers had values within the range for the normal controls, independently of which substrate was used.

Sphingomyelinase activities of various human tissues in control subjects and in Niemann-Pick disease - development and evaluation of a microprocedure

A micromethod was elaborated for the assay of sphingomyelinase activities with native labelled substrate in leukocytes, cultivated skin fibroblasts, liver tissue and cultivated amniotic fluid cells. The optimal assay conditions and specific activities in control samples were investigated for each enzyme souce. No significant difference was found between results obtained either with the micromethod or with our previous procedure. Findings obtained in pathological material from 62 patients with the various forms of Niemann-Pick disease and 21 obligate heterozygotes by one or another method are reported. A generalized severe sphingomyelinase deficiency was observed in all cases with Niemann-Pick disease type A or B, while in Niemann-Pick disease type C, sphingomyelinase activities were normal in leukocytes, elevated in liver tissue and partially deficient in cultivated skin fibroblasts. Six pregnancies at risk were monitored.

Krabbe disease: a galactosylsphingosine (psychosine) lipidosis

The primary genetic defect underlying Krabbe disease or globoid cell leukodystrophy is considered to be a deficiency of galactosylceramide-beta-galactosidase. In the present study of the brains from 18 patients who had died from Krabbe disease at 7-37 months of age, the concentration of galactosylceramide of cerebral and cerebellar white matter was severely reduced to 10-20% of that in age-matched controls. The lowest values were found in the most long-standing cases. Lactosylceramide was reduced to about 50% of normal, while globotriaosylceramide, blobotetraosylceramide and III3-alpha-fucosylneolactotetraosylceramide were increased 10 to 100-fold. Two glycosphingolipids, which have never before been isolated from normal human brains were now isolated and characterized: galactosylsphingosine (psychosine) and galactosyl beta 1 leads to 4 galactosylceramide. We were unable to identify galactosylsphingosine in normal human brains with certainty. We estimate its concentration in the cerebral white matter in Krabbe disease to be increased at least 100-fold (higher than normal). Psychosine was isolated also from the cerebral cortex in Psychosine was isolated also from the cerebral cortex in Krabbe disease after derivatization to the N-acetyl form. Its concentration there was 1 nmol/g tissue compared with 6-10 nmol/g in the white matter. All the neutral glycosphingolipids were isolated and their structure proved by the quantitative determination of their components, degradation by acid and specific glycohydrolases and permethylation and gas-liquid chromatographic-mass spectrometric assay of the methylated sugars. The paradoxical findings of a severely reduced concentration of galactosylceramide and a primary deficiency of cerebroside-beta-galactosidase can be explained by the present finding of the accumulation of galactosylsphingosine in the brains from patients who had died from Krabbe disease. The enzyme has a broad specificity and it normally also degrades galactosylsphingosine. Because of competitive inhibition by the accumulated galactosylceramide its lysosomal hydrolysis will be blocked. The concentration of psychosine will steadily increase and reach toxic levels and kill the oligodendroglial cells. This results in an arrest of the galactosylceramide biosynthesis. Therefore, we feel that galactosylsphingosine and not galactosylceramide is the primary storage substance in the brain in Krabbe disease that the disease is a psychosine lipidosis.

The assay of sphingolipid hydrolases in white blood cells with labelled natural substrates

Methods were elaborated for the assay on leukocytes of sphingolipid hydrolases with native and artificial substrates. The optimal conditions for the isolation of leukocytes and the preparation of labelled sphingolipids were investigated. The KM and Vmax values for all substrates are given as the specific activities of the sphingolipidhydrolases in normal males and females. It is concluded that leukocytes are the enzyme source of choice for the enzymic diagnosis of neurolipidoses.

[Infantile form of Gaucher's disease. Clinical and biological studies in 1 case. Prenatal diagnosis in 2 further normal pregnancies]

A clinical report of a typical case of infantile Gaucher's disease is given. Study of the beta-glucosidase activity in leukocytes and skin fibroblasts confirmed the diagnosis in the patient and established the heterozygote condition of the parents. Two later pregnancies have been monitored by enzymatic study of cultured amniotic fluid cells. Both foetuses were predicted to be healthy, which was confirmed after birth. The report includes a histopathological ultrastructural, chemical and enzymatic study of liver, spleen and brain obtained at autopsy. Possible clues to the physiopathological mechanism of the cerebral lesion are discussed.

Neurovisceral storage disorder simulating Niemann-Pick disease. A new form of oligosaccharidosis?

Two sisters are described with demonstrable splenomegaly already from infancy and, after the age of 2--4 years, signs of slowly progressive encephalophy, vacuolated lymphocytes in the peripheral blood, and peculiar foam cells in the bone marrow aspirates. The died at 7 3/4 and 6 1/2 years. Widely spread in the brain, the nerve cell bodies were found to show extensive ballooning. It was most striking in the brain stem and spinal cord, while cerebellar structures were remarkably well preserved. The cytoplasm of the ballooned nerve cells was filled with finely granular storage material stainable as a readily soluble glycolipid. The spleen, liver and intestinal wall contained numerous foamy PAS-positive macrophages. Chemical assays showed a ten-fold increase of lactosylceramide and a modest one of minor gangliosides brain cortex. No accumulation sphingomyelin could be revealed, and the sphingomyelinase activity was found to be normal. The ganglioside GM1 beta-galactosidase activity of leucocytes was reduced to 20--25% of normal, which indicated a disturbance of the glycosaminoglycan metabolism. The tissue content of glycosaminoglycans was, however, normal, but an accumulation of lactose was demonstrated in the spleen. It is postulated that the primary enzymic defect is a disturbance of a lysosomal beta-galactosidase with a substrate specificity for lactose and other oligosaccharides with a terminal beta-galactosidic linkage.

Lipid and fatty acid composition of human cerebral myelin during development

A development study of major lipid fatty acids in human brain myelin was undertaken and compared to those in cerebral white matter of the same region. The myelin was isolated from 23 subjects at ages from newborn to old age. The proportions of cholesterol and galactolipids increased in myelin during the first 6 months of age and up to 2 years of age in cerebral white matter. During the same periods the individual phospholipids also showed marked variations. Serine phosphoglycerides and especially sphingomyelins increased, and choline phosphoglycerides decreased. The fatty acid patterns of ethanolamine phosphoglycerides (EPG) and sphingomyelins underwent the largest maturation changes. The proportions of saturated fatty acids in EPG diminished rapidly with a corresponding increase of monoenoic acids. Fatty acids of the linoleic acid series showed a peak between 4 months and 12 months of age, and then their proportion slowly diminished to old age. The fatty acid changes in serine phosphoglycerides were much less pronounced than in EPG but of similar type. In sphingomyelin the proportion of saturated long-chain fatty acids diminished while the proportion of monoenoic acids increased--this increase continued at least to the age of 15 years. The same fatty acid changes occurred in cerebrosides and sulfatides as in the sphingomyelins, but they were less pronounced. The fatty acid changes during development were much more pronounced in white matter than in myelin but already from 1-2 years of age the lipids of myelin and white matter had the same patterns--in the galactolipids from 2 months of age. The individual variations of the lipid fatty acid patterns were small except for at the youngest ages and the variations found for this period might depend on the difficulties in determining the gestational age.

[Clinical, ultrastructural and biochemical study of a case of GM1 type 2 gangliosidosis]

Clinical, histological, ultrastructural and biochemical studies have been performed in a living 20-month-old infant with GM1-gangliosidosis type 2. Rectum, brain and liver biopsies were done. The histological and ultrastructural examination revealed the presence of cytoplasmic membranous bodies in the nervous system and a vacuolisation of the visceral parenchymatous cells, particularly histiocytes. The diagnosis was established by the finding of a generalized beta-galactosidase deficiency and an accumulation of GM1-ganglioside in brain. In leukocytes, the activity of p-nitrophenyl-beta-galactosidase was below 5%, and that of GM1-ganglioside beta-galactosidase below 1% of values obtained in controls. In cerebral tissue, GM1 ganglioside constituted 80% of total gangliosides; its concentration was 15 times that in age-matched controls. No accumulation of GM1 could be evidence in liver. Enzymatic examination of leukocytes obtained from the consanguineous parents revealed heterozygote values.

Chemical pathology of Krabbe's disease. III. Ceramide-hexosides and gangliosides of brain

Neutral ceramide-hexosides and gangliosides in cerebral cortex and white matter of children who had died in Krabbe's disease were quantitatively isolated and characterized. The concentrations of galactosylceramides; lactosylceramides and glucosylceramides were normal or slightly increased in cerebral cortex, but all the three glycolipids were diminsihed in white matter, particularly the galactosylceramides. More complex ceramide-hexosides, globotriose, globotetraose and blood-group substance H, present in trace amounts in normal brain, were much more abundant in cerebral cortex and especially in white matter of brains affected by Krabbe's disease. The composition of the ceramide portion suggested that these glycolipids as well as a portion of the lactosylceramides and glucosylceramides were structural components of the globoid cell. The ganglioside distribution was severely altered. GD1a and GM1 were severely reduced in cerebral cortex and white matter, while GD1b and GT1 were slightly decreased in cerebral cortex, but increased in white matter. Normally minor brain gangliosides metabolically related to GD1b and GT1, i.e. GD2, GD3 and GM3, were strongly increased in cerebral cortex and in white matter. For the first time galactosylsphingosine (psychosine) was demonstrated in normal infant brain. In cerebral tissue affected by Krabbe's disease the concentration of psychosine was at least 10 times higher. The large increase in this cytotoxic substance might be the primary lesion in Krabbe's disease.

Chemical pathology of krabbe's disease. IV. Studies of galactosylceramide and lactosylceramide BETA-galactosidases in brain, white blood cells and aminotic fluid cells

Galactosylceramide beta-galactosidase and lactosylceramide beta-galactosidase activities were investigated in normal human brain, leu-kocytes and amniotic fluid cells. The enzymatic assays were performed on brains from 11 patients with Krabbe's disease, on leukocytes from 16 patients and 18 obligate heterozygotes, and on amniotic fluid cells from 9 foetuses at risk. The brain enzyme was solubilized from a 900 g-100000 g pellet. With this enzyme preparation a profound deficiency of galactosylceramide beta-galactosidase activity in brain, approximately 1% of that in age-matched controls was shown. The lactosylceramide beta-galactosidase activity of brain was also strongly reduced, but not to the same extent as the other beta-galactosidase. Galactosylceramide beta-galactosidase activity in leukocytes from patients with Krabbe's disease was generally less than 5% of that in age-matched controls and there was no overlap between the patients and the obligate heterozygotes. Carrier detection by the leukocyte enzyme was, however, not possible because of considerable overlap between heterozygotes and normal controls. The lactosylceramide beta-galactosidase activity was only moderately reduced in leukocytes, but strongly reduced in cerebral tissue from patients with Krabbe's disease. The changes in the glycolipid pattern of cerebral tissue, recently described by us in patients with Krabbe's disease, offers an explanation to the serious glycolipid beta-galactosidase deficiency in CNS.

Polyunsaturated fatty acid lipidosis. II. Lipid biochemical studies

Lipid analyses were performed on cerebral tissue from three children who had died of a progressive encephalopathy and from one living child in an early stage of the disease. In the terminal stage of the disease, the cortex and white matter content of all lipid classes, particularly the sphingolipids, were very low. The concentration of gangliosides of the cerebral cortex was 10%, and of cerebrosides in white matter, 2-3% of the normal values for the age. The porportion of the minor gangliosides with short carbohydrate chains was increased because the reduction affected mainly the four major brain gangliosides GM1, GD1a, GD1b and GT1. In the child from whom the biopsy specimen was obtained in an early phase of the disease the cerebral lipid pattern appeared to be normal. A patient who had died of neuronal ceroid-lipofuscinosis (Janský-Bielschowsky) did not show any major lipid changes. The fatty acid patterns of the phosphoglycerides showed such changes as have never been observed in any other disease. In the three advanced cases the fatty acid compositions in cerebral cortex and white matter were identical. In ethanolamine phosphoglycerides the proportions of 18: 1 and 20: 4 (n-6) were increased, while those of 22: 4 (n-6) and 22: 6 (n-3) were markedly diminished. Similar changes in the fatty acid patterns were found in the other phosphoglycerides. In the early phase of the disease 22: 4 (n-6) was decreased and 18: 1 increased. We propose that this new disease be termed polyunsaturated fatty acid lipidosis (PFAL).