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Biomedical subjects

N G Beratis

Publications and source records attributed to N G Beratis.

At least 55 records · Page 3Linked to original sources
PubMed1989

Cardiac involvement in postnatal rubella.

Two cases of rubella myocarditis are reported: a 6-year-old boy who developed a complete, distal to His, atrioventricular block, during the third day of illness; and a 12-year-old boy who developed myocarditis with congestive heart failure 20 days following rubella infection. Although permanent pacing was required in the first patient, six years later he showed a normal growth and maintained normal activity. The second patient has deteriorated markedly and 6 months after the initial illness he had severe heart failure. It should be noted that myocarditis with abnormalities of the conduction system or congestive heart failure may be a complication to postnatal rubella.

Child↗
PubMed1988

Transformation of lymphocytes from immunized Rh(D)-negative subjects by Rh(D) isoantigen.

Since immune memory in Rh(D)-negative isoimmunized subjects remains through life, even in the absence of measurable anti-Rh(D), we investigated the transformation of lymphocytes from such donors by Rh(D) antigen. The time lapse from the last stimulus was up to 13 years. Mononuclear cells from immunized women were stimulated by Rh(D)-positive erythrocyte stroma. Maximum transformation was observed on the sixth day of culture, with a stroma protein concentration of 8 micrograms/mL of culture medium. The stimulation index (SI) in cells from 11 immunized women was 6.8 +/- 3.1 (mean +/- SD), with a range from 3.1 to 15.0. In five different sets of control cultures, the SI ranged from 0.9 +/- 0.2 to 1.3 +/- 0.4. There was no overlap between stimulated and control cultures. No anti-D could be demonstrated in the serum of four of the 11 immunized cases studied. Also, transformation was observed in mononuclear cells from Rh(D)-negative immunized women with Rh(D)-positive erythrocytes. The findings demonstrate that lymphocytes from isoimmunized Rh(D)-negative subjects maintain the immune memory and are transformed in vitro by the Rh(D) isoantigen.

Antigens↗
PubMed1987

Galactose metabolism in transferase-deficient galactosaemic and normal long-term lymphoid cell lines.

The activity (mean +/- SD) of galactose-1-phosphate uridyl transferase in two long-term lymphoid cell lines from Caucasian patients with transferase deficiency galactosaemia, a heterozygote, and eight normal subjects was 0, 78 and 168 +/- 55 nmol UDPG consumed (mg protein)-1h-1, respectively. Also, no activity was found in erythrocytes and cultured fibroblasts from the patients. A small number of cells of the galactosaemic lines cultured in medium, in which galactose was substituted for glucose, survived for 37 days. Normal and galactosaemic lines incubated with D-galactose-[1-14C] liberated 218.2 +/- 65.6 and 18.1 pmol 14CO2 (mg cellular protein)-1 (6h)-1, respectively. The evolution of 14CO2 from D-glucose-[1-14C] was similar in normal and galactosaemic lines. In the presence of [3H]galactose the radioactivity incorporated into TCA-precipitated material of the galactosaemic lines was 6.8% of the normal lines. Approximately 26% and 1.3% of the total radioactivity was incorporated into molecular species with a molecular weight greater than 400,000 daltons in normal and galactosaemic cells, respectively. Similar molecules were identified in the cell-free medium of both normal and deficient cells except for an 18,000 daltons molecule identified only in the medium of the normal cells. These findings indicate that a small amount of galactose is metabolized in galactosaemic lines with no transferase activity.

Carbon Dioxide↗
PubMed1987

Gaucher disease: treatment of hypersplenism with splenic embolization.

Hypersplenism is a frequent complication of Gaucher disease requiring splenectomy. A patient with Gaucher disease and severe hypersplenism was treated with partial splenic embolization to avoid the increased risk of serious infectious complications and deterioration of the disease associated with splenectomy. A first embolization (25% ablation) was performed at 4 years. Because of persisting abdominal discomfort, failure to thrive and signs of hypersplenism a second embolization (40-50% ablation) was performed 18 months later. Subsequently, the patient's health improved remarkably and 4 years later he achieved normal growth, maintains normal haematologic parameters, is free of symptoms and has no skeletal abnormalities. No serious infections have occurred. The size of the liver and the spleen has not changed appreciably. It appears that partial splenic embolization may be preferable to splenectomy in patients with Gaucher disease, especially in those of young age.

Child↗
PubMed1986

Sanfilippo disease in Greece.

In a series of cases collected in most parts of the world, Sanfilippo disease type A is more frequent than type B. Skin biopsies were obtained from Greek patients suspected for Sanfilippo disease and cultured fibroblasts were assayed for both N-acetyl-a-glucosaminidase and sulfamidase activity. Eleven patients with Sanfilippo disease were identified. Ten of them were type B and one type A. The 10 patients with type B came from East-Central Greece and the neighboring areas of Thessaly and Macedonia. Both parents of the type A patient were from the Greek ethnic community of Turkey. It remains unknown whether or not the higher frequency of type B than type A appears only in Greece or if it occurs in other Mediterranean countries as well.

Acetylglucosaminidase↗
PubMed1983

Acid alpha-glucosidase deficiency in cultured fibroblasts with phenotype 2 of acid alpha-glucosidase.

The enzyme acid alpha-glucosidase shows a polymorphism determined by two alleles, namely phenotypes 1, 2-1 and 2. We report that the activity of acid alpha-glucosidase, measured in fibroblasts homozygous for isozyme 2 is significantly reduced. In fibroblasts harvested at early confluency the activity in the strain with phenotype 2 of acid alpha-glucosidase was 23% and 5% compared to the levels in normal phenotype 1 strains using maltose and glycogen as substrate, respectively. At late confluency, the same fibroblasts showed an increase in activity to 60% and 15% of normal, respectively. At both early and late confluency, two fibroblast strains with the adult form of acid alpha-glucosidase deficiency had activity of approximately 7% of the activity in normal phenotype 1 fibroblasts with both substrates. In general, an increased amount of glycogen was measured in deficient fibroblasts, including the strain with phenotype 2, but overlapping was observed with normal cells. These findings show that fibroblasts homozygous for the isozyme 2 allele have a reduced ability to hydrolyse the natural substrate, glycogen.

Cells, Cultured↗
PubMed1983

Genetic heterogeneity in acid alpha-glucosidase deficiency.

Several clinical forms of acid alpha-glucosidase deficiency have been described. Our study was planned to identify differences at the molecular level in acid alpha-glucosidase deficiency. Of nine fibroblast strains derived from patients with the infantile form of the disease, eight were crossreacting material (CRM)-negative and one CRM-positive. This was demonstrated by both agar immunodiffusion and immunotitration. No difference in apparent enzymatic activity was observed between CRM-negative and CRM-positive infantile acid alpha-glucosidase deficiency fibroblasts. In two fibroblast strains with the adult form of acid alpha-glucosidase deficiency, rocket immunoelectrophoresis demonstrated a reduction in the amount of enzyme protein, which was directly proportional to the reduction in enzyme activity. In another fibroblast strain obtained from a patient with the adult form of the disease, the activity was within the range of the infantile form and no CRM could be identified. Fibroblasts with phenotype 2 of acid alpha-glucosidase, considered a normal variant, showed a reduction both in the amount of enzyme protein and in the ability of the enzyme to cleave glycogen. However, the catalytic activity for maltose was normal. The findings demonstrate extensive genetic heterogeneity in acid alpha-glucosidase deficiency. Molecular differences were identified both between the clinical forms of the disease and within the infantile and the adult forms of acid alpha-glucosidase deficiency. It remains unknown whether or not the enzyme deficiency in homozygotes for isozyme 2 of acid alpha-glucosidase will be sufficient to cause glycogen accumulation and lead to the development of muscular dystrophy-like disease later in life.

Adult↗
PubMed1981

Studies of the copper-binding proteins in Menkes and normal cultured skin fibroblast lysates.

Proteins of approximately 10,000 daltons (presumably metallothionein) and greater than 75,000 daltons bound 64Cu when this metal was added to fibroblast lysates. Treatment with either 2-mercaptoethanol or the disodium salt of ethylenediamine tetraacetic acid demonstrated that the high molecular weight copper-binding proteins in lysates prepared from both normal and Menkes fibroblasts exhibited a relatively low affinity for copper compared to the 10,000 dalton protein(s). No difference was detected in the affinity of the low molecular weight protein(s) of normal and Menkes fibroblast lysates for copper. The amount of 64Cu bound to the 10,000 dalton protein(s), however, was approximately two to three times greater in lysates prepared from Menkes fibroblasts than from normal fibroblasts. Mixing experiments indicated that the increased binding of 64Cu to the 10,000 dalton protein(s) in lysates of Menkes fibroblasts did not result from the deficiency of a factor that effects the cleavage of copper from this protein(s), from the presence of a soluble inhibitor, or from the lack of an activator. In addition, the use of lysates, rather than whole cells, demonstrated that the observed differences in copper binding between the normal and the Menkes fibroblasts were not caused by an abnormality in the membrane transport of copper in the mutant cells. Thus the findings suggest that the increased accumulation and the reduced efflux of copper previously observed in cultured Menkes fibroblasts result either from an increased amount of the 10,000 dalton copper-binding protein(s) or from an increased capacity of this molecule(s) for copper.

Brain Diseases, Metabolic↗
PubMed1981

Methionine utilization in long-term human lymphoid cell lines.

Long-term lymphoid cell lines (LTL) cultured under normal conditions use methionine primarily for protein synthesis, although a significant proportion is converted to S-adenosylmethionine (SAM) and used for synthesis of the polyamines, spermidine, and spermine. When LTL are cultured under conditions of high cell density, there is an initial phase of rapid protein synthesis and accumulation of SAM as found under normal culture conditions, but this soon ceases. Polyamine synthesis is small under these conditions, despite the presence of relatively large amounts of SAM.

Blood Proteins↗
PubMed1981

Increased copper metallothionein in Menkes cultured skin fibroblasts.

Menkes fibroblasts contain a significantly greater amount of cysteine-rich 10,000 dalton copper-binding protein(s) (metallotheionein) than normal cells. Mutant fibroblasts incorporated 30 to 40% more tritiated amino acids into 10,000 dalton protein(s) than normal cells. The protein(s) was deficient in aromatic amino acids The amount of 35S-cysteine incorporated by the same protein(s) in Menkes fibroblasts was twice that of normal fibroblasts. Comparison of the 35 S:3H isotopic ratios of chromatographic fractions of both normal and Menkes cell lysates showed that only the proteins eluted in the 10,000 dalton peak were enriched in 35S-cysteine, and this ratio was always greater than in Menkes than in normal cells. The 10,000 molecular weight 35S-cysteine- and 3H-amino acid-labeled peaks coincided with the 64Cu peak in both cell strains. The copper-labeled peak was always greater in Menkes than in normal cells. No difference in the 64Cu:35S isotopic ratio in the 10,000 dalton peak was observed between normal and Menkes fibroblast strains. This finding shows the direct relationship between the amount of cysteine-rich 10,000 dalton protein(s) and the amount of 64Cu bound by this protein(s) in both Menkes and normal fibroblasts. DEAE-cellulose ion-exchange chromatography resulted in a further two-fold enrichment of the 10,000 dalton, sulfur-rich proteins that were eluted from the Sephadex G-75 column. Most of the labeled proteins from both normal and Menkes fibroblasts were eluted from the ion-exchange column in a single peak at a chloride concentration of approximately 30 mM. Polyacrylamide disc gel electrophoresis of pooled fractions of the 10,000 dalton proteins eluted from the G-75 column and the DEAE-cellulose ion-exchange column showed no consistent differences in the staining pattern between normal and mutant fibroblast strains. When th acrylamide gels were sliced and subsequently counted for radioactive content, no band showed a further increase in the 35 S:3H isotopic ratio when compared to the electrophoresed samples that were eluted from the Sephadex G-75 or the ion-exchange columns. Also, no significant increase in the amount of radioactivity associated with a specific protein band could be demonstrated between the Menkes and the normal fibroblast strains.

Amino Acids↗
PubMed1981

Accumulation of ganglioside Gm2 in cerebrospinal fluid of a patient with the variant AB of infantile Gm2 gangliosidosis.

Brain biopsy has been used for the diagnosis of the variant AB of infantile GM2 gangliosidosis. Accumulation of ganglioside GM2 (300 ng of neuraminic acid per milliliter) was observed in the CSF of a patient with this disorder. GM2 was found also in the CSF of a patient with classic Tay-Sachs disease. Normal CSF did not contain any measurable amounts of GM2. In addition, a glycolipid with a mobility, by thin-layer chromatography, similar to that of paragloboside was observed in the CSF of the patient with the variant AB of GM2 gangliosidosis. These findings indicate that the variant AB can be diagnosed by demonstrating accumulation of GM2 in the CSF of patients with normal hexosaminidase activity.

Chromatography, Thin Layer↗
PubMed1980

Transsulfuration by human long term lymphoid lines. Normal and cystathionase-deficient cells.

Long term human lymphoid cells from normal subjects were able to convert [35S]homocysteine to [35S]-cystine. The labeled cystine was found incorporated into proteins. Cells cultured from a patient with vitamin B6-unresponsive cystathioninuria, which contain no measurable cystathionase activity, were unable to perform this conversion. This is the first direct demonstration of transsulfuration by diploid cells in culture.

Cell Line↗
PubMed1980

An isozyme of acid alpha-glucosidase with reduced catalytic activity for glycogen.

Both the common and a variant isozyme of acid alpha-glucosidase have been purified from a heterozygous placenta with CM-Sephadex, ammonium sulfate precipitation, dialysis, Amicon filtration, affinity chromatography by Sephadex G-100, and DEAE-cellulose chromatography. Three and two activity peaks, from the common and variant isozymes, respectively, were obtained by DEAE-cellulose chromatography using a linear NaCl gradient. The three peaks of activity of the common isozyme were eluted with 0.08, 0.12, and 0.17 M NaCl, whereas the two peaks of the variant, with 0.01 and 0.06 M NaCl. The pH optimum and thermal denaturation at 57 degrees C were the same in all enzyme peaks of both isozymes. Rabbit antiacid alpha-glucosidase antibodies produced against the common isozyme were found to cross-react with both peaks of the variant isozyme. The two isozymes shared antigenic identity and had similar Km's with maltose as substrate. Normal substrate saturation kinetics were observed with the common isozyme when glycogen was the substrate, but the variant produced an S-shaped saturation curve indicating a phase of negative and positive cooperativity at low and high glycogen concentrations, respectively. The activity of the variant was only 8.6% and 19.2% of the common isozyme when assayed with nonsaturating and saturating concentrations of glycogen, respectively. A similar rate of hydrolysis of isomaltose by both isozymes was found indicating that the reduced catalytic activity of the variant isozyme toward glycogen is not the result of a reduced ability of this enzyme to cleave the alpha-1,6 linkages of glycogen.

Chromatography↗
PubMed1980

Effect of copper on Menkes' and normal cultured skin fibroblasts.

Skin fibroblasts from normal subjects and from patients with Menkes' disease did not demonstrate any significant differences in morphologic or growth characteristics when cultured in medium without added copper. Addition of CuCl2 to the medium caused a reduction in the growth rate of the fibroblasts. Menkes' fibroblasts were more sensitive to copper than normal cells. Concentrations greater than 50 micrograms CuCl2/ml of medium caused extensive cell death especially in the mutant cells. The rate of DNA synthesis in Menkes' fibroblasts was reduced in the presence of 2--100 micrograms CuCl2/ml. Normal cells showed a reduction in DNA synthesis at CuCl2 concentrations greater than 50 micrograms/ml, whereas at concentrations between 2 and 30 micrograms/ml the rate of DNA synthesis was increased. These findings indicate that CuCl2 is more toxic to Menkes' than to normal fibroblasts and suggest that a similar response of neuronal cells may occur in the patients in vivo.

Brain Diseases, Metabolic↗