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Biomedical subjects

A Larsson

Publications and source records attributed to A Larsson.

At least 523 records · Page 29Linked to original sources
PubMed1976

Light microscopic and ultrastructural observations of the calcifying zone of the mandibular condyle in the rat.

The hypertrophic stage of development of the rat mandibular condyle was investigated in 16 and 26-day-old rats by electron microscopy. Interest was focused on the zone of mineralization and erosion. It was observed that capillaries invaded the lower level of the hypertrophic zone, without any previous chondroclastic resorption of calcified partitions. The partitions surrounding the hypertrophic chondrocytes were not mineralized around their entire circumference at the level of capillary penetration. The capillaries were accompanied by perivascular cells but these showed no similarities to chondroclasts. Multinucleated chondro- or osteoclasts were however present at a lower level of the subchondral area. It is suggested that there are no inherent differences with respect to the pattern of mineralization and erosion between the epiphyseal growth plate and the developing mandibular condyle.

Animals↗
PubMed1976

Feminization of hepatic S metabolism in male rats with a transplanted (MtT/F4).

After transplantation of MtT/F4 pituitary tumor cells to male rats of the Fisher strain, the masculine type of hepatic steroid metabolism was changed into a feminine pattern of enzyme activities. Liver metabolism of steroid hormones in female rats was relatively unaffected following transplantation of pituitary tumor cells. Futhermore, extract from MtT/F4 tumors and "autonomous" pituitary tissue increased the 5alpha-reductase activity of hepatoma cells in the culture (HTC cells) at subsaturation concentrations of the substrate 4-androstene-3, 17-dione by decreasing the apparent Km of the enzyme. It is concluded that the pituitary tumor (in accord with the secretion from an "autonomous" pituitary gland) secretes "feminotropin," a novel hypophyseal principle that probably is an important regulator of hepatic steriod metabolism. It is suggested that pituitary tumor tissue of the MtT/F4 type could be used as source of feminotropin in purification studies.

Androstenedione↗
PubMed1976

Nodular fascitis in the oral cavity.

Clinical and microscopic features of a deeply situated lesion of the oral buccal mucosa are reported. The lesion suddenly appeared as a small lump, without obvious cause. A histologically alarming picture gave rise to a preliminary diagnosis of a sarcoma. However, features of nodular fascities were subsequently recognized and following local removal there has been no recurrence in the 4 years that have elapsed since operation.

Adult↗
PubMed1976

The frequency of PKU and hyperphenylalaninemia in Sweden - a study in institutions for the mentally retarded as well as in neonates.

In a country-wide screening examination in Sweden, PKU was observed in 75 (4.5 per 1,000) and hyperphenylalaninemia in 14 (0.8 per 1,000) of a total of 16,805 patients in institutions for the mentally retarded. In the national neonatal screening program in 1965-1975, which covered nearly 1 million individuals, PKU was observed in 36 and hyperphenylalaninemia in 19 individuals. The incidences of PKU and hyperphenylalaninemia in newborns are calculated to be 1/26,000 and 1/50,000, respectively. In addition, PKU and hyperphenylalaninemia were diagnosed in 14 and 1 non-institutionalized individuals, respectively, born before September 1965. The total numbers of individuals detected as having PKU and hyperphenylalaninemia in Sweden in the present investigation are 125 and 34, respectively.

Adolescent↗
PubMed1976

Histochemical localization of alkaline pyrophosphate- phosphohydrolase in tooth-forming cells of rat.

The activity of a pyrophosphate-splitting tissue factor in jaws, teeth and intestinal mucosa has been studied by means of histochemistry. Freeze-cut, unfixed sections of whole animals were incubated in a buffered medium (pH 8.6) containing inorganic pyrophosphate (PP) Pb2+, Mg2+, and Zn2+ at various concentrations. The effects of compound R 8231, heat, aldehyde fixation, and demineralization with EDTA were also investigated. In sections showing optimal staining, deposition of incubation products was found in the stratum intermedium and the subodontoblastic cells of the developing tooth, in the osteoblastic layers, and at the surface of the intestinal mucosa. The hard tissues were also stained except in the demineralized sections. Treatment with heat or compound R 8231 resulted in loss of originally observed soft tissue staining while short-time demineralization with EDTA enhanced the staining reaction. It is argued that a nonspecific deposition of the capturing ion, Pb2+, can hardly explain the observed soft tissue staining. The results point to the presence of a PP-splitting enzyme, and it is suggested that the enzyme exhibits features of an alkaline phosphatase with PP-phospholhydrolytic properties rather than of an inorganic pyrophosphatase.

Animals↗
PubMed1976

Light microscopic and ultrastructural observations on the short-term effects of ethylene-1-hydroxy-1, 1-diphosphonate (EHDP) on rat tibia epiphysis.

Ethylene-1-hydroxy-1, 1-diphosphonate (EHDP) was administered intraperitoneally to one-day old rats at a concentration of 30 and 40 mg/kg body weight/injection. Two groups of animals received four doses, respectively, over a 44-hour-period and a third group received two high doses with a 15-hour interval, the total amounts corresponding to 30, 40 and 20 mg/P/kg body weight. Animals in the first two experimental groups showed increased width of the hypertrophic zone as compared with normal controls and lack of calcified septa within the zone of provisional calcification. In the calcification zone, persistent atypical chondrocytes were present and in the septa a large number of matrix vesicles which hardly ever contained any crystals. The ground substance of these septa contained fine precipitates, probably representing proteoglycan complexes which were not seen normally in this zone. In the third group, the septa of the calcification zone were calcified and the hypertrophic zone was not clearly widened. In the metaphysis, remnants of cartilage or osteoid were observed as "islands" covered with osteoblast-like cells which showed signs both of collagen and apatite formation, the latter evidenced by the appearance of crystals within the matrix vesicles. It is suggested that the complex effects observed in calcifying cartilage after administration of high doses of EHDP in vivo are not restricted solely to the stage of crystal formation.

Animals↗
PubMed1976

Streptococcal types in impetigo and acute glomerulonephritis among children in Addis Ababa.

Studies on the streptococcal epidemiology of impetigo in children below 12 years of age in Addis Ababa indicated that most streptococci isolated belonged to the classic serological impetigo strains. Streptococcal type 9 seemed to be a new impetigo strain. Several cases of severe acute glomerulonephritis on impetigo basis were observed during the study.

Acute Disease↗
PubMed1975

Influence of a novel hypophyseal factor on steroid metabolism in cultured hepatoma cells.

A rat hepatoma cell line in tissue culture (HTC cells) was treated with hypophyseal extracts from adult male and female rats. Cell homogenates were then assayed for steroid metabolizing enzymes using 4-androsten-3,17-dione as substrate. The major products were the 5 alpha-reduced derivatives (5 alpha-androstane-3,17-dione, androsterone, and epiandrosterone). When the cells were grown in the presence of female hypophyseal extract the apparent activity of the 5 alpha-reductase increased markedly, whereas treatment with male hypophyseal extract was without effect. Treatment with female hypophyseal extract resulted in a marked decrease in the apparent Km for 5 alpha-reductase from 667 +/- 102 to 99 +/- 4 muM in addition to a decrease in the apparent Vmax from 67 +/- 12 to 46 +/- 2 pmol of product/min per mg of protein. A logarithmic dose-response was obtained with female hypophyseal extract. Treatment of the HTC cells with purified rat hypophyseal follicle-stimulating hormone, luteinizing hormone, growth hormone, thyrotropic hormone, and prolactin had only marginal effects on 5 alpha-reductase activity. Crude female hypophyseal extracts were at least 6-fold more potent than any of the standard hormone preparations and at least 250-fold more potent than male hypophyseal extracts when based on activity per mg of pituitary tissue. Chromatography of crude female hypophyseal extracts on Sephadex G-25 indicated that the factor was of high molecular weight. The identity of this activity with a hypophyseal "feminizing" factor is postulated.

Androstenedione↗
PubMed1975

Destruction of dextran-coated target cells by normal human lymphocytes and monocytes. Induction by a human anti-dextran serum with IgG antibodies restricted to the IgG2 subclass.

A human anti-dextran serum, EAK, with IgG antibodies restricted to subclass IgG2, was tested for its capacity to induce lysis of dextran-coated chicken erythrocytes by normal human lymphocytes or monocytes. Another human anti-dextran serum, RGM, with most antibodies belonging to sublass IgG1, and a hyperimmune rabbit anti-dextran serum were used for reference. In lymphocyte-mediated erythrolysis, serum EAK gave rise to 51-Cr release varying from 20% to 80% in different experiments. The hyperimmune rabbit serum was 100 to 1000 times more active, whereas serum RGM was consistently negative. These results correlated well with the concentration of anti-dextran antibodies in these sera. In monocyte-mediated erythrolysis serum EAK had a somewhat higher titer than in lymphocyte-mediated lysis, and serum RGM had a weak but significant activity at low dilutions. Serum EAK also induced erythrophagocytosis by monocytes. Ultracentrifugation did not significantly decrease the inductive capacity of this serum. The results show that antibodies of human sublass IgG2 are efficient inducers of effector functions in both lymphocytic and monocytic cells. Myeloma proteins of the four IgG subclasses were tested for inhibitory capacity in lymphocyte- or monocyte-mediated erythrolysis. Either serum EAK or the rabbit reference serum was used for induction of erythrolysis. Individual myeloma proteins within and between the subclasses varied considerably in inhibitory power. However, whereas IgG1, IgG2, and IgG3 proteins inhibited lymphocyte-mediated erythrolysis induced by either type of antiserum, the two IgG4 proteins tested were essentially negative. These results suggest a lack of specificity of the Fc receptor for subclasses IgG1, IgG2, and IgG3 in both heterologous and homologous inhibition. In monocyte-mediated erythrolysis, IgG1 and IgG3 were strong inhibitors, whereas inhibition by IgG2 and IgG4 was weak and inconsistent. This pattern was seen regardless of whether and inducing antiserum was of rabbit or human origin. Similar results were obtained in monocyte-induced erythrophagocytosis induced by serum EAK. These and previous results suggest that effector cells of the lymphocytic (K cell) variety have Fc receptors different from those of monocytic cells. However, the basis for the differences observed in the inhibition tests remains to be elucidated.

Animals↗
PubMed1975

In vitro target cell lysis mediated by normal human lymphocytes. Influence of molecular properties and affinity of inducing antibody.

Lysis of DNP-coated chicken erythrocytes by human blood lymphocytes (K cells) was induced by means of rabbit anti-DNP antibodies. Antisera were prepared by injecting the animals with DNP-conjugated proteins emulsified in Freund's complete adjuvant. An ammonium sulphate precipitation technique was used for assay of antibody concentration and affinity. Sephadex G-200 chromatography indicated that 90% of the DNP antibodies were 7S in the bleedings on days 10-16, whereas 99.8% were 7S in later bleedings. 7S antibodies induced K-cell lysis at high dilutions, whereas 19S antibodies were essentially negative. Antibody fractions obtained by DEAE- or CM-cellulose chromatography were used to establish possible heterogeneities in the capacity of 7S antibodies to induce either K-cell- or complement-mediated target cell lysis. No such heterogeneities were founnd. Fifteen IgG preparations containing antibodies of different affinities were compared with regard to their capacity to induce K-cell-mediated lysis. A statistically significant correlation was found between antibody affinity and efficiency in K-cell-mediated lysis. In a similar study of complement-mediated lysis the correlation was not significant at the 5% level but was significant at the 10% level.

Animals↗