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Biomedical subjects

W Richter

Publications and source records attributed to W Richter.

At least 271 records · Page 15Linked to original sources
PubMed1976

Passive cutaneous anaphylaxis in guinea pigs elicited by gastric absorption of dextran induced by acetylsalicylic acid.

Passive cutaneous anaphylaxis (PCA) was elicited in guinea pigs sensitized with rabbit antidextran by the absorption of dextran macromolecules from the stomach induced by intragastric acetylsalicylic acid. The gastric contents had a pH sufficiently low to maintain the acid mainly in the unionized form since it is the latter which alters gastric permeability. The acid concentration required to induce PCA was below that which caused mucosal cell loss or bleeding. The maximal molecular weight of the absorbed dextran was approximately 25,000. Dextran was chosen as antigen because of its well-characterized physical and immunological properties. It is suggested that ingestion of acetylsalicylic acid may contribute to sensitization and allergic reactions to antigenic food materials by facilitating their absorption from the stomach.

Absorption↗
PubMed1976

Dextran-induced anaphylactoid reactions in man: role of dextran reactive antibodies.

Dextran reactive antibodies (DRA) were studied in 123 patients having experienced dextran-induced anaphylactoid reactions (DIAR) during 1970-1975. No evidence for reaginic DRA was obtained by radioallergosorbent technique and passive cutaneous anaphylaxis in Cynomolgus monkeys; total IgE levels were within normal range. It is concluded that DIAR are not mediated by dextran-specific reagins. Further, no reaginic antibodies against potential contaminants from the dextran manufacturing process were demonstrable. In two population samples of normal human sera from Sweden and Germany hemagglutinating DRA (IgG, IgA, and IgM classes) were found in 63 and 74%, high titres (16-256) comprising 14 and 25%. In dextran reactors a direct positive correlation between titres of hemagglutinating DRA and increasing severity of DIAR was observed. The accumulation of high DRA titres in severe reactions may be taken as circumstantial evidence for the causal role of hemagglutinating DRA in these cases. However, if high titres of DRA alone were responsible for triggering DIAR, the expected frequency would be more than thousand times higher than the reported global incidence of DIAR. To explain this discrepancy, involvement of certain Ig classes or subgroups, possibly in combination with other predisposing factors is suggested. In mild reactions DRA appear to play a negligible role. Positive dextran wheal and flare reactions, often correlated with high titres of hemagglutinating DRA, were seen in 32% of dextran reactors, indicating that skin tests are of limited predictive value. No significant difference between sexes, age groups, or pre- and intraoperatively started dextran infusions was observed; association with certain diseases was not apparent.

Adolescent↗
PubMed1976

[The hydrodynamic mucosa-cytology by means of ultrastructures filters in upper respiratory tract and oesophagus].

A rinse-and-suck-sound is presented, which conveys cytological material to a special filter mechanism. The heart of the system is a well-known filter, an electric pump, and a new constructed vacuum chamber. After Papanicolaou staining the filters are being cleared and allow a light-microscopical judgement. A reduction of possibilities of error in exfoliative cytology can be noticed.

Biopsy↗
PubMed1975

Effect of substitution on reactivity of B 512 dextran fractions with anti-B 512 dextran in heterologous passive cutaneous anaphylaxis.

The influence of type and degree of substitution of B 512 dextran fractions on reactivity with rabbit antibodies against unmodified B 512 dextran was studied on heterologous passive cutaneous anaphylaxis in guinea pigs. Low degrees of substitution, i.e. 1 substituent group per 7-30 glucose residues, affected reactivity with anti-dextran only slightly or not at all. This was shown for the following substituents: sulphate, carboxymethyl, phosphate, diethylaminoethyl, hydroxypropyl, butyryl, caprylyl, stearoyl, and fluoresceinoyl groups. With high degress of substitution, i.e. 1-3 substituents per 2 glucose residues, reactivity with anti-B-512-dextran is completely abolished for some substituents, and a new immunological identity conferred on the substituted dextran. Stongly charged groups like sulphate, carboxymethyl and diethylaminoethyl abolish reactivity with anti-B-512-dextran at relatively lower degrees of substitution than more neutral groups like methyl and acetyl. The anti-B-512-dextran represents a specific reagent for alpha-1,6-linked polyglucose, as evidenced by complete cross-reactivity with synthetic linear dextran; its specificity is emphasized by non-reactivity with alpha-1,6-linked synthetic manna, the monomeric residues of the two polymers differing only in position of the C-2 hydroxyl groups.

Animals↗
PubMed1975

[Stomatological morbidity study--Berlin 1972. 3. The frequency of dysgnathias and their symptoms in the subjects of an epidemiologic-stomatological study].

Stomatological morbidity study - Berlin 1972. Part III. The frequency of dysgnathias and their symptoms in subjects of an epidemiologic-stomatological study. In the course of a stomatological morbidity study which was performed in Berlin in 1972, the authors investigated the dental conditions of 657 subjects, having an age range from 18 to 30 years. Only 15.2% of the persons under investigation had an eugnathic dentition. Almost 85% of the individuals showed dysgnathias. Apart from the frequency of certain tooth malalignments and malocclusions, associated symptoms were recorded. 15.5 of the subjects under investigation said that they had had orthodontic treatment. Significant differences were found in comparing the results obtained from treated individuals with those from untreated subjects.

Adolescent↗
PubMed1975

[Neurogenesis and regeneration in the brain of teleosts in relation to age. (Autoradiographic studies)].

54 healthy female Lebistes reticulatus and 11 Xiphophorus helleri of various age groups were injected with 3H-thymidin. The duration of the radio-active test was one hour. By means of autoradiograms of serial sections of the brain, the post-natal persistence of matrical zones was demonstrated in the telencephalon, diencephalon, mesencephalon, cerebellum and in the medulla oblongata. The age-dependency of the 3H-thymidin index produced the same results in all matrical zones: high values in young animals, followed by a steep decrease and a steady state in older animals. In 30 other laboratory animals (Lebistes reticulatus-Teleostei), out of which 15 were juvenile and 15 were adult females, a unilateral lesion of the central tectum was effected. On the 5th, 7th, 8th, 15th, and 25th days following operation the animals were given a single injection of 3H-thymidin (absolute activity 10 muCi/g body weight; duration of the radio-active test: one hour). Labelled meningeal cells were observed in the traumatic region. In the course of regeneration there takes place a migration of cells into the puncture channel. No labelled cells were observed in the tissues adjacent to the lesion nor in the cell column. The proliferation of cells takes place in the matrical zones. By determining the 3H-thymidin index we were able to show that the proliferation activity is being increased. In the matrical zones of the non-operated tectum opticum too, the number of DNA synthesizing cells is increased.

Age Factors↗