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Biomedical subjects

A Larsson

Publications and source records attributed to A Larsson.

At least 469 records · Page 26Linked to original sources
PubMed1981

5-oxoprolinuria due to hereditary 5-oxoprolinase deficiency in two brothers--a new inborn error of the gamma-glutamyl cycle.

Two brothers, aged 16 and 11 years, had recurrent episodes of vomiting, diarrhoea and abdominal pain, starting in infancy. In spite of extensive investigations no cause of their enterocolitis could be established. After several years symptomatic treatment was discontinued without any recurrence of symptoms. Their father and several paternal relatives have had kidney stones. Both boys developed urolithiasis and an oxalate-containing stone was removed from the elder brother's kidney. He had no hypercalciuria. His glomerular and tubular function tests were normal. Gas chromatography of urine from both brothers revealed massive excretion of L-5-oxoproline (pyroglutamic acid). Glutathione levels in erythrocytes of both patients were normal. The activities of enzymes of the gamma-glutamyl cycle were analysed in erythrocytes, leukocytes and cultured skin fibroblasts. The level of glutathione synthetase was normal, as was the affinity of this enzyme for its substrate gamma-glutamyl-cysteine. Feedback inhibition of gamma-glutamyl-cysteine synthetase by glutathione was also normal. Both patients had a specific deficiency of 5-oxoprolinase, the activity of which was 2-4% of that of control subjects. Their parents had intermediate 5-oxoprolinase activities in fibroblasts, indicating a recessive mode of inheritance. Thus, 5-oxoprolinuria in these two patients was due to a lack of 5-oxoprolinase, i.e., a new inborn error in the gamma-glutamyl cycle.

Adolescent↗
PubMed1981

Enzyme histochemistry of developing rat oral mucosa.

The oral mucosa of developing and mature rats was analyzed histochemically for regional enzyme differences. The following enzymes were studied: nonspecific alkaline phosphatase (alkpase), acid phosphatase (acidpase), 5'-nucleotidase (AMPase), adenosine triphosphatase (ATPase), succinate dehydrogenase (SDH), lactate dehydrogenase (LDH), and glucose-6-phosphate dehydrogenase (G-6-pDH). All enzymes were active in the oral mucosa, but regional as well as tissue variations were observed. Epithelium in all regions showed acidpase staining. Oxidoreductases were found in all regions with variations within the epithelium. The epithelium of specific regions stained for alkpase and AMPase, while adjacent epithelium did not. We suggest that the alkpase and AMPase activities are associated with specific functions of the epithelium in these regions.

Aging↗
PubMed1981

Focal epithelial hyperplasia in Sweden.

A prevalence of 0.11% of focal epithelial hyperplasia (FEH) was found among 20,333 adult Swedes. There was no sex difference, the lesion was most prevalent in age groups above 45 years and the lesion was most frequent on the tongue. The frequency of FEH in 15,132 consecutive routine biopsies was 0.26%. Four FEH-cells were ultrastructurally examined. They exhibited a clear cytoplasm with scattered ribosomes, a peripheral condensation of tonofilaments, a central aggregation of chromatin clumps with loss of nuclear membrane and an accumulation of desmosome fragments. No viral particles could be identified in these FEH-cells.

Adolescent↗
PubMed1981

Glutathione and gamma-glutamyl cycle enzymes in human fetal liver.

Human fetal and adult liver were found to have similar concentrations of acid soluble sulfhydryl (SH) groups (7.4 mmol/kg) in the same range as is found in adult mouse and rat liver. The concentration was 4-fold higher than in human fetal adrenal gland tissue. Methods specific for glutathione (GSH) associated SH groups revealed that the postmortem levels of GSH is very low (0.4 mmol/kg) in relation to total SH groups. In contrast, the levels of cysteine were high (2.8 mmol/kg), indicating a rapid cleavage of GSH. Only negligible amounts of gamma-glutamylcysteine and cysteinylglycine were measured. Our findings may be explained by high fetal activity of gamma-glutamyl transpeptidase (which metabolizes GSH) that has been documented previously both in man and in experimental animals. High activities of the two GSH-synthesizing enzymes, gamma-glutamylcysteine synthetase and GSH synthetase were found in the human fetal liver (7.1 and 3.0 mukat/kg, respectively). The activities of these enzymes were in the same range as in human adult liver, whereas that of gamma-glutamyl transpeptidase was 3-fold higher in the fetal liver. Our results demonstrate the presence of high concentration of SH groups and capacity to synthesize GSH already in the first and second trimester of the human fetal gestation. This has more than theoretical interest, since we assume that the SH groups (GSH) have importance for the protection of the fetus against drugs and foreign compounds and their (toxic) metabolites, the formation of which is catalyzed by the fetus itself.

Adrenal Glands↗
PubMed1981

Oxygen enhancement of radiation induced lethality is greatly reduced in glutathione deficient human fibroblasts.

The in vitro clonogenic survival of human fibroblasts with a genetically defined glutathione (GSH) deficiency was studied after irradiation with X-rays in oxygen or in oxygen free argon. Genetically related fibroblasts without GSH deficiency were used as a control. The oxic survival curve of both cell lines was similar. In comparison to the oxic survival curve, the anoxic survival curve of GSH deficient cells indicated an oxygen enhancement ratio (OER) approximately 1.5. An OER approximately 2.9 was calculated in comparing the oxic and anoxic survival curves of the control cell line. The results were discussed in support of the theory according to which oxygen and GSH compete for radiation induced radicals in key molecules, the former irreversibly fixing and the latter repairing the radiation damage.

Anaerobiosis↗
PubMed1981

Histidinaemia in Sweden. Report on a neonatal screening programme.

Histidinaemia screening was included in the epidemiological survey of the Swedish neonatal screening programme, 1971-72. Dried blood samples on filter paper collected neonatally from 171,000 infants were analysed the Guthrie method. A blood histidine level above 0.96 mmol/1 (15 mg per 100 ml) was regarded as a positive test and was found in 639 infants - i.e., 1/270. No further diagnostic measures were taken until 1977 when stored dried blood samples from 273 infants with a positive screening test were analysed for urocanic acid. Four children had undetectable blood urocanic acid. They were studied and histidinaemia was confirmed in two children, and excluded in two. Both histidinaemia children had normal psychomotor development at 7 years of age, in spite of the fact that no dietary treatment was given. The incidence of histidinaemia in Sweden was estimated as 1/37,00, on the basis of neonatal screening. In addition, histidinaemia was diagnosed in four individuals who were not detected in the neonatal screening programme; of these, only one had an IQ less than 85. At present, general neonatal screening histidinaemia in Sweden does not seem justified.

Adolescent↗
PubMed1980

Pyrophosphate analogues as inhibitors of herpes simplex virus type 1 DNA polymerase.

Twenty nine pyrophosphate analogues have been tested for their ability to inhibit herpes simplex virus type 1 (HSV-1) DNA polymerase activity. The structural requirements for active inhibitors and their mechanism of action have been investigated. Active compounds had two negatively charged groups at close proximity. The most active compounds contained free phosphono and/or carboxyl groups. Apart from phosphonoformate and phosphonoacetate, which were strong inhibitors, some other analogues, 2-phosphonopropionate, 2-phenylphosphonoacetate, oxalate, carbonyldiphosphate, methanehydroxy-diphosphonate and hypophosphate also inhibited the HSV-1 DNA polymerase activity. With the exception of hypophosphate the tested compounds inhibited the activity of calf thymus DNA polymerase alpha to a lesser extent than the activity of the HSV-1 DNA polymerase. All inhibitors gave linear uncompetitive inhibition of HSV-1 DNA polymerase with activated DNA as variable substrate. With the four deoxynucleoside triphosphates as variable substrates all inhibitors except hypophosphate gave linear non-competitive inhibition patterns. Hypophosphate caused a more competitive type of inhibition. The inhibition constants for the active compounds have been determined. Phosphonoformate, phosphonoacetate, methanehydroxydiphosphonate and hypophosphate also inhibited HSV-1 plaque formation in cell culture.

Animals↗
PubMed1980

Intraosseous angiolipoma of the mandible.

A case of intraosseous angiolipoma of the mandible is reported. To our knowledge, this represents only the second case involving the jaw to be reported in the literature.

Adipose Tissue↗
PubMed1980

Lack of oxygen effect in glutathione-deficient human cells in culture.

The frequency of X-ray-induced DNA breaks was determined in human cell lines which are deficient in glutathione synthetase and have a greatly reduced glutathione content. Hydroxyapatite chromatography was used for the estimation of the DNA breaks in cell cultures, which were derived either from lymphoblasts transformed by infection with EB virus or from fibroblasts. The dose-effect relationship for the induction of breaks when radiation exposure was made in argon, was similar to that found when exposure was made in air. In control cultures with normal glutathione content, the induction of breaks was enhanced when irradiation was made under aerobic, instead of anaerobic, conditions. Treatment of the glutathione-deficient cells with the hypoxic radiosensitizer misonidazole did not enhance the induction of breaks by radiation delivered either in air or in argon. In control cultures, radiation induction of breaks was enhanced by misonidazole under anaerobic but not under aerobic conditions. When the glutathione-deficient cells were pretreated with cysteamine however, irradiation in the absence of oxygen resulted in a decreased frequency of DNA breaks.

Cells, Cultured↗
PubMed1980

Ultrastructural features of the epithelial-mesenchymal interface in an ameloblastic fibro-odontoma.

The ultrastructural features of the epithelial-mesenchymal interface in a case of an ameloblastic fibro-odontoma was studied with special reference to possible signs of "inductive" processes. In most parts of the tumor, the odontogenic epithelium was separated from the connective tissue by a thick rim of a finely filamentous meshwork in which a basal lamina was occasionally observed. Mesenchymal cells were seen to touch the filamentous meshwork but no membrane bound matrix vesicles were recorded. Small areas of dentin-like tissue were found in the juxtaepithelial connective tissue while enamel-like areas and spherical calcified masses were encountered in epithelial islands. The organic matrix in relation to the enamel-like tissue consisted of either tubular fibers or a fine-granular material. It was assumed that the tubular matrix component directed the formation of long enamel-like crystals, and that the fine-granular matrix was degraded tubular fibers in which spherical calcified masses might arise. Spherical calcified masses could be found in separate follicles also where they were related to a fine-fibrillar matrix or collagenous material. The cell layers forming the wall of the islands had a great resemblance to those of an enamel organ, but the findings of dentin-free, enamel-like areas are not compatible with the inductive theory of normal odontogenesis.

Calcium↗
PubMed1979

Effects of inorganic lead on delta-aminolevulinic acid dehydratase activity and hematological variables in the rainbow trout, Salmo gairdnerii.

The activity of the enzyme delta-aminolevulinic acid dehydratase (ALA-D) was strongly depressed in erythrocytes, spleen and renal tissue of rainbow trouts (Salmo gairdnerii) exposed to sublethal levels of inorganic lead (10, 75 and 300 microgram Pb2+/L) for 30 days. The fish exposed to the highest lead concentration also showed an anemic response and basophilic stippling of erythrocytes. The lead exposure did not cause any alteration of the white blood cell picture. The ALA-D inhibition, the anemia and basophilic stippling seemed to persist in the lead-exposed fish even after a recovery period of seven weeks in lead-free water.

Animals↗