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Biomedical subjects

F Van Hoof

Publications and source records attributed to F Van Hoof.

At least 73 records · Page 4Linked to original sources
PubMed1979

Ocular findings in metachromatic leukodystrophy. An electron microscopic and enzyme study in different clinical and genetic variants.

Histopathological studies of the eyes from three patients affected with the infantile form of metachromatic leukodystrophy (MLD) showed the storage of metachromatic complex lipids in the retinal ganglion cells, in the optic nerve and the ciliary nerves, as well as the storage of a mucopolysaccharide-like material in the nonpigmented epithelium of the ciliary body. The lesions were limited to the optic, ciliary, and sensory nerves in a fourth patient with the juvenile form of the disorder. These morphological aspects, which are probably related to differences in sulfatase A activities, may explain the variability of the ocular manifestations in metachromatic leukodystrophy. Seven children affected with infantile MLD or with mucosulfatidosis were examined by conjunctival biopsy. Typical lesions of the sensory nerves were obvious and allowed the diagnosis of the disease. However, it seemed impossible to separate the different forms by histopathological studies only. The tear enzymes were assayed in most of the cases and demonstrated a profound deficiency of arylsulfatase A, or of arylsulfatase A and B, in the classical MLD and in mucosulfatidosis, respectively.

Cerebroside-Sulfatase↗
PubMed1979

Cellular toxicity of gentamicin.

Subconjunctival injections of gentamicin induced a lysosomal storage process within the conjunctival fibroblasts in rats, rabbits, and humans. Under electron microscopy, the accumulated substance was composed of a granular material and pleomorphic lamellar structures, corresponding to the presence of complex lipids. In animals, the other ocular tissues as well as the cells reached through the bloodstream remained unaffected, except the proximal convoluted tubules of the kidneys, where important lesions were evident. Although human kidneys were not examined in our study, we believe they might present similar alterations.

Animals↗
PubMed1979

[Onychomycoses caused by moulds].

The authors studied in vitro and in vivo the invasion of the nail keratin by saprophytes. This invasion takes palce in the same way in both cases: mycelian filaments and spores penetrate in the hyponychium, filaments penetrate in the upper part of the tablet, filaments and, as far as some saprophytes are concerned, 'boring hyphae' penetrate in the lower part of the tablet. Those ways of invasion are responsible for the clinical pictures (onychomycosis, pachyonychia, leuconychomycosis). Electron microscopically the mycelian filaments appear to be both intercellular and intracellular. The authors insist in the importance of the criteria of evaluation which allow us to establish the saprophytic origin of onychomycosis.

Fungi↗
PubMed1979

Acid hydrolases of trypanosomatid flagellates.

Homogenates from 5 species of Trypanosomatids were screened for the presence of a series of acid hydrolases. The insect flagellae, Crithidia sp., contains 5 enzymes reminiscent of plant parasitism, which were absent from or of very low specific activity in parasites of the genera, Trypanosoma and Leishmania. The latter mammalian parasites, on the other hand, exhibited higher acid proteinase and alpha-D-mannosidase activity levels.

Animals↗
PubMed1977

Ocular findings in I-cell disease (mucolipidosis type II).

The ultrastructural study of the eyes in seven patients affected with I-cell disease (mucolipidosis type II) revealed important changes in the corneal, scleral, and uveal fibroblasts, while other cells were rarely involved. This explains the inconstant corneal clouding and the absence of ophthalmoscopic abnormalities clinically. At any moment of a patient's life, conjunctival biopsy specimens show characteristic alterations and allow the rapid and secure diagnosis of I-cell disease. This examination should be widely used in the screening of lysosomal diseases.

Child, Preschool↗
PubMed1976

A morphologic and biochemical study of the fate of antibody-bearing liposomes.

The effect of the intravenous administration of gamma-globulins, entrapped or not within liposomes, was investigated in rodent liver. Desialation of gamma-globulins did not influence significantly their uptake by this organ. Fluorescein-labeled nonspecific gamma-globulins and antibodies raised against the lysosomal acid alpha-glucosidase were entrapped within two types of liposomes. The administration of negatively charged liposomes made of lecithin, cholesterol, and dicetylphosphate was badly tolerated. Positively charged liposomes, in which dicetylphosphate was replaced by stearylamine, allowed a considerably higher yield of entrapment and were well tolerated by the animals. Approximately half of the fluorescent gamma-globulins were recovered in the liver, and evidence is presented for the intralysosomal localization of positively charged liposomes, both in the reticuloendothelial cells and in the hepatocytes. A striking difference exists, nevertheless, in the appearance of the two types of cells, 1 hour and 7 1/2 hours after injection. The specific antibodies never inhibited more than 50% of the activity of liver acid alpha-glucosidase, and there was no significant modification in the glycogen content of this organ. This work points to the influence of the composition of liposomes, in determining the entrapment of proteins, the toxicity, the uptake by the liver, and the distribution of these lipidic spherules in the different types of cells. This factor will have to be taken into account if liposomes are to be used as vectors in the treatment of lysosomal storage diseases.

Animals↗
PubMed1976

The use of conjunctival biopsy and enzyme analysis in tears for the diagnosis of homozygotes and heterozygotes with Fabry disease.

In most inborn errors of metabolism, the detection of heterozygotes is either impossible, or is feasible only on a statistical basis, so that some uncertainty always remains in that diagnosis. Heterozygote detection is by far more imperative in sex-linked diseases than in autosomal recessive disorders. Indeed, female carriers are at risk of having affected children whatever is the genome of their husband. The method we describe realizes the secure detection of heterozygotes in Fabry disease. It combines the ultrastructural examination of conjunctival biopsies and the assay of thermolabile alpha-galactosidase in tears. The technique is harmless and relatively simple: Both biopsy and tear collection were performed at home in most of the subjects.

Adult↗
PubMed1976

Fucosidosis: ultrastructural study of conjunctiva and skin and enzyme analysis of tears.

Conjunctival and skin biopsies from two new patients with fucosidosis were studied by electron microscopy. In both tissues, the connective tissue cells and the capillary endothelial cells were filled with single membrane limited inclusions of two types: (1) Clear inclusions containing a fibrillogranular reticulum. (2) Dark inclusions with a dense granular material. Specific stainings in ultrastructure suggest that these inclusions contain oligosaccharide chains. The ultrastructural aspect is characteristic for fucosidosis. Enzyme studies on tears realized an easy and secure technique for the diagnosis of the disease.

Biopsy↗
PubMed1975

Glycogen phosphorylase and its converter enzymes in haemolysates of normal human subjects and of patients with type VI glycogen-storage disease. A study of phosphorylase kinase deficiency.

1. The properties of phosphorylase a, phosphorylase b, phosphorylase kinase and phosphorylase phosphatase present in a human haemolysate were investigated. The two forms of phosphorylase have the same affinity for glucose 1-phosphate but greatly differ in Vmax. Phosphorylase b is only partially stimulated by AMP, since, in the presence of the nucleotide, it is about tenfold less active than phosphorylase a. In a fresh human haemolysate phosphorylase is mostly in the b form; it is converted into phosphorylase a by incubation at 20degreesC, and this reaction is stimulated by glycogen and cyclic AMP. Once activated, the enzyme can be inactivated after filtration of the haemolysate on Sephadex G-25. This inactivation is stimulated by caffeine and glucose and inhibited by AMP and fluoride. The phosphorylase kinase present in the haemolysate can also be measured by the rate of activation of added muscle phosphorylase b, on addition of ATP and Mg2+. 2. The activity of phosphorylase kinase was measured in haemolysates obtained from a series of patients who had been classified as suffering from type VI glycogenosis. In nine patients, all boys, an almost complete deficiency of phosphorylase kinase was observed in the haemolysate and, when it could be assayed, in the liver. A residual activity, about 20% of normal, was found in the leucocyte fraction, whereas the enzyme activity was normal in the muscle. These patients suffer from the sex-linked phosphorylase kinase deficiency previously described by others. Two pairs of siblings, each time brother and sister, displayed a partial deficiency of phosphorylase kinase in the haemolysate and leucocytes and an almost complete deficiency in the liver. This is considered as being the autosomal form of phosphorylase kinase deficiency. Other patients were characterized by a low activity of total (a+b) phosphorylase and a normal or high activity of phosphorylase kinase in their haemolysate.

Adenosine Monophosphate↗