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Biomedical subjects

D Platt

Publications and source records attributed to D Platt.

At least 181 records · Page 10Linked to original sources
PubMed1979

Age-dependent physiochemical and biochemical studies of human red cell membranes.

Erythrocyte ghosts of male persons of two age groups, younger than thirty and older than seventy years, were analyzed to investigate the imfluence of age on lipid composition, the physical state of the lipid phase, Na+K+-ATPase activity and sialic acid content. The phospholipid content in red cell membranes of old donors is significantly lower than in young ones. Cholesterol and fatty acid compositions shows no difference between the two donor groups. The membrane fluidity in liposomes prepared from total lipids of old donor decreased. No significant difference in lipid composition and membrane fluidity reflected by the spin labels was observed between blood group A and O. The activity of Na+K+-ATPase of the young donors with blood group A is significantly higher than those of old donors. The results also demonstrate a decrease of sialic acid content of red cells of old donors.

Adolescent↗
PubMed1979

Influence of age and spironolactone on lysosomal enzyme activities, DNA and protein content of the rat liver after partial hepatectomy.

Measurements of DNA and protein content and determinations of lysosomal enzyme activities (beta-glucuronidase, beta-acetylglucosaminidase, cathepsin D) were performed in the rat liver following partial hepatectomy and spironolactone administration. The rats (SIV) were divided into three age-groups: 6 weeks old, 10 months old and 18 months old. 60 h after the administration of spironolactone (2 x 10 mg Aldactone/100 g body weight/day orally via gastric tube for 3 days) partial hepatectomy was performed. The removed two thirds of the liver and the regenerating liver (24 h after partial hepatectomy) were prepared for the biochemical examinations at 4 degrees C. The measurements of the enzyme activities were performed in liver homogenates. The results indicate that the administration of spironolactone cause (1) a weight increase in the normal as well as in the regenerating liver, especially in the older animals; (2) an increase of the protein content of the normal liver in the oldest age-group; (3) a decrease in the DNA content of the normal and regenerating liver of old rats, and (4) an age-dependent increase of decrease of the three lyososomal enzymes beta-glucuronidase, beta-acetylglucosamidase and cathepsin D.

Acetylglucosaminidase↗
PubMed1979

[Theories and models of the biology of aging].

Two main theories of aging were discussed: program theory, error theory. The importance of repair mechanisms is disclosed. 4 models (Lag-phase, proliferative capacity, physical properties of collagen, latency period) display typical phenomenons of the biology of aging.

Aging↗
PubMed1978

Age dependent kinetic studies of cytoplasmic and lysosomal enzymes of the normal and D-galactosamine injured rat liver.

Rats of two age groups (6 weeks and 30 months) received (1) a single dose of 600 mg D-galactosamine (GalN)/kg body weight by intraperitoneal (i.p.) injection, (2) a single dose of 600 mg GalN/kg body weight i.p. combined with 20 mg prednisolone/kg body weight subcutaneously at the beginning of the experiment. The kinetic studies disclose that GalN produces more severe changes in old than in young animals, represented by the activities of cytoplasmic (glutamic oxaloacetic transaminase, glutamic pyruvic transaminase) and lysosomal (beta-acetylglucosaminidase beta-glucuronidase, cathepsin D) enzymes. Prednisolone diminishes the morphological liver changes as well as the biochemical disturbances in young rats. There is only a protecting effect in morphological changes of old animals within the first 12 h. The prevention of cytoplasmic enzyme activity increase is limited to the first 12 h.

Acetylglucosaminidase↗
PubMed1978

[The importance of age dependent changes of the organism for therapy (author's transl)].

Molecular and supramolecular mechanisms of ageing involve biochemical, physiological and morphological alterations of organs. Furthermore physiological disturbances are superimposed by pathological mechanisms of ageing. As a result the number of diseases in higher age increases as well as there are a lot of therapeutical problems. The following paper tries to reveal that physiological and pathological changes of different organs (heart, kidney, lung, brain) influence the therapy of older man. The results demonstrate that it is necessary to stimulate the research of pharmacodynamics and kinetics in the higher age.

Aged↗
PubMed1978

[Influence of age on biochemical parameters of the rat liver following partial hepatectomy (author's transl)].

In the present paper measurements of DNA and protein content and lysosomal enzyme (beta-glucuronidase, beta-acetylglucosaminidase, cathepsin D) acitivities were performed in the rat liver following partial hepatectomy. The rats were divided into three age groups: 6 weeks, 10 months and 18 months. The regenerating liver of the 6 week and 10 month old animals disclosed significant higher concentrations of DNA than the controls. The 18 month old rats revealed no differences of the DNA content. In all age groups the protein content of the regenerating liver was significant diminished. There were age dependent differences of the activities of the three lysosomal enzymes. In comparison to the controls the beta-glucuronidase activity of the regenerating liver was significantly decreased in the 6 week and 18 month old animals, but significantly increased in the 10 month old rats. Refering to the protein content there were no differences of the activities of beta-acetylglucosaminidase and cathepsin D between the regenerating and control livers. Refering to the liver fresh weight the beta-acetylglucosaminidase activity of the regenerating liver was significant diminished in the 10 and 18 month old rats.

Acetylglucosaminidase↗
PubMed1976

[The effect of prednisolone on the development of the galactosamine hepatitis of young and old rats (author's transl)].

The present work reports on kinetic and morphological studies of one hundred female albino rats after the administration of galactosamine and galactosamine and prednisolone. The results demonstrate a significant higher increase of the serum transaminasess got and gpt in the older than in the younger rats as well as a protecting effect of prenisolone against galactosamine produced disturbances. In the thirty months old rats the protection against morphological and biochemical disturbances was only demonstrable for the first twelve hours after the administration of galactosamine.

Age Factors↗
PubMed1976

[Incorporation of 14-C-Glycine during galactosamine hepatitis of young and old rats (author's transl)a*].

The present work reports on incorporation of 14-Cglycine in the proteins of three liver fractions after the application of D-Galactosamine and D-Galactosamine + Prednisolone. 164 females albino rats were used in the experiments. The results demonstrate a higher rate of glycine incorporation in thirty months than in six weeks old animals. There is also a different age depending effect of prednisolone. The results are discussed in the light of reports from the literature.ports from the literature.

Age Factors↗
PubMed1975

[Clinical, biochemical, morphological and electrophysiological studies of glycogenosis Type II in childhood with double deficiency of enzymes (author's transl)].

The clinical, biochemical, morphological and electrophysiological findings in a 13-month-old child, who died of glycogenosis type II, is presented. In addition to the deficiency of alpha-1,4-glucosidase, which is typical for the disease, a deficiency in hyaluronidase could be detected for the first time in the skeletal and heart muscles and in the liver. On the other hand, the beta-glucoronidase and beta-acetylglucosaminidase activity was highly increased. Deposits of a substance, most probably an acid mucopolysaccharide, which could be differentiated from glycogen by chromography and electronmicroscopy, could be detected in the muscle. A pathogenetical connection with the hyaluronidase defect is imminent.

Glucosidases↗
PubMed1975

[Age-dependent biochemical studies on the extrarenal effect of furosemid (author's transl)].

The present study investigated the activities of lysosomal enzymes of the liver after administration of Furosemid. 10 weeks and 1-year old male albino rats were treated with 40 mg Furosemid for 4 subsequent days. According to the method devised by de Duve a sediment rich in lysosomes was produced by fractionated centrifugation and subsequently the enzyme activity of beta-glucuronidase, beta-acetylglucosaminidase, cathepsin D and a collagenolytic enzyme was measured in the sediment as well as in the corresponding lysosomal supernatant. The protein content served as a reference for the enzyme activities. In addition, we investigated the activities of cytoplasmic enzymes such as GOT, GPT, gamma-GT and the alkaline phosphatase. The enzyme activity changes were age-dependent. With Furosemid treatment the activities of beta-glucuronidase and cathepsin D increased in the lysosomal supernatant and the lysosomal sediment of the 1-year old rats, whereas the activities of the collagenolytic enzyme increased in the lysosomal sediment of the same group. In the lysosomal sediment of the 10-weeks old rats a decrease of beta-glucuronidase, beta-acetylglucosaminidase and cathepsin D was observed. These results are discussed in the light of reports from the literature.

Age Factors↗
PubMed1975

Sequential appearance of salivary antibodies after oral immunization of axenic mice.

The purpose of the present investigation was to examine the production of specific salivary antibodies after oral immunization of axenic mice (ICR/CD-1) with formalinized Escherichia coli (ATCC 11775). Three aspects of the humoral response were studied: (i) the sequential appearance of anti-E. coli antibodies; (ii) classes of antibodies produced in response to the antigen; and (iii) antibody specificity. Antibody levels were determined by passive hemagglutination with soluble lipoplysaccharide and bacterial agglutination, using preparations of somatic O and flagellar H antigens. A short latent period of 1 to 3 days was observed when saliva samples were assayed for anti-lipopolysaccharide and anti-O antibodies. The salivary antibody titers peaked at 11 days after initiation of the immunization regimen. Only two of six mice exhibited a change in serum antibody levels against these antigens. The predominant class of early antibody in saliva was immunoglobulin (Ig)G; however by 7 days IgA WAS found to comprise the major portion of specific immunoglobulins. Serum antibodies directed against falgellar antigenic determinants were primarily of the IgM class, whereas the salivary antibodies were IgG in nature.

Administration, Oral↗
PubMed1975

Modification of surface membrane antigens by trypsin.

Cultured 3T3 and PY-3T3 mouse fibroblasts were subjected to mild treatment with twice crystallized trypsin and their immunogenicity tested in ICR/CD-1 mice. Surface antigenic modifications were observed using the foot pad swelling assay for detection of delayed hypersensitive responses. Mice immunized with trypsin-treated 3T3 cells showed cell-mediated immune reactions following challenge with either homologous antigen or untreated PY-3T3 fibroblasts. In contrast, treatment of the virus-transformed cells with trypsin decreased their antigenicity as determined by this in vivo assay.

Animals↗