Calorimetric studies on viroids.

Thermodynamic studies on highly purified viroid preparations were carried out with the help of a very sensitive adiabatic microcalorimeter. Parallel to the change of UV-absorption at 260 nm as a function of temperature, the additional heat capacity of the dilute viroid solution rises sharply within the melting interval, reaches a maximum at T = Tm and declines to a baseline again when the temperature is increased further. From the peak area the molar transition enthalpy can be calculated. The transition enthalpies of citrus exocortis viroid and cucumber pale fruit viroid are 4200 kJ/mol and 3930 kJ/mol, respectively. The calorimetric results are compared to the results obtained from melting studies using UV-absorption.     

Laser Raman studies on cobrotoxin.

Laser Raman spectra of cobrotoxin under various conditions have been obtained. Comparison of the spectra of native cobrotoxin in lyophilized form and in aqueous solution indicates that the secondary structures of cobrotoxin are not significantly affected by the removal of the aqueous solvent. On going from the native to the partially reduced and the completely reduced, carboxy-methylated forms, characteristic peaks of the C-S-S-C and tyrosine ring in the region of 500--900 cm-1 showed definite changes in structure. The partially reduced form gave two peaks at 502 and 524 cm-1, suggesting difference in the conformation of the remaining disulfide bonds. As indicated by the present work, the conformation of the main chain of cobrotoxin in the native unperturbed state, in the partially reduced and in the completely reduced forms are the coexistence of beta-pleated sheet with random-coil structure, predominantly random coil, and predominantly random coil with the existence of an alpha-helix type structure, respectively. The effect of pH on the conformation of cobrotoxin in solution appeared to give rise to the change of the local structure of two aromatic residues common to all snake neurotoxins.     

Immunofluorescent studies on Candida albicans.

The indirect immunofluorescent titres of Candida albicans 0656 CBS hyperimmune rabbit serum were investigated against C. albicans antigens prepared from strains originating from mucous membranes of healthy persons and patients with thrush. Using pathogenic strains as antigens, a definitely strong fluorescent reaction was obtained with hyperimmune rabbit serum in a dilution of 1 : 2500. In the case of apathogenic strains the fluorescent reaction was either very weak or negative in a dilution of 1 : 2000. Absorption studies also seemed to reveal a difference in reactivity between pathogenic and apathogenic strains. Hyperimmune rabbit serum absorbed with apathogenic C. albicans strains showed a positive fluorescent reaction only with pathogenic ones as antigens. In the opposite case a negative reaction was obtained.     

Genetical studies on oenothera. IV

Ohne Zusammenfassung     

Analytical studies on crotamine hydrochloride.

The neurotoxin crotamine, which is a basic low molecular weight protein, was isolated, in the form of its hydrochloride, from a South Brazilian rattlesnake (Crotalus durissus crotaminicus, Crotalus durissus terrificus) venom.Disc electrophoresis, carried out in 7% acrylamide by the method of Reisfeld, at pH 4.5, showed a single band for the purified toxin.The toxin showed the following amino acid composition: Asx₂, Ser₃, Glx₂, Pro₃, Gly₅, Cys₅, Met₁, Ileu₁, Leu₁, Tyr₁, Phe₂, Trp₂, Lys₉, His₂, and Arg₂, which corresponds to a minimum molecular weight of 4760. This assignment of minimum molecular weight is supported by the recovery of 1.0 mole of N-terminal $\text{Tyr}\text{5800}\text{g}$ of crotamine by the Sanger dinitrophenol (DNP) method, 1.0 mole of $\text{Tyr}\text{4880}\text{g}$ by the Udenfriend method, and by uv analysis, which gave a value of 4820. The odd number of half-cystine residues ($\text{5}\text{4760}\text{g}$) cannot be explained on the basis of available analytical data.Tyrosine was the only amino-terminal residue detectable by the Sanger DNP method. Glycine was identified as the only carboxyl-terminal residue by the hydrazinolysis method of Akabori and by release upon treatment with yeast carboxypeptidase.The H⁺ electrometric and Cl^? complexometric titrations of crotamine hydrochloride showed that about 13 moles of HCl are bound per 4760 g of the free base.     

Clinical studies on thyroidal autoantibodies.

In an attempt to clarify autoimmune nature of Grave's disease and Hashimoto's thyroiditis, thyroidal autoantibodies have been studied on 86 cases of Grave's disease, 54 cases of Hashimoto's thyroiditis, 31 cases of simple goiter, 11 cases of primary hypothyroidism a-d 22 cases of thyroid neoplasia as well as on 364 healthy subjects. Two kinds of tanned red cell hemagglutination tests were carreid out on each case. One method using refined human thyroglobulin for sensitization of sheep red cells has been found to be specifice for anti-thyroglobulin antibody and to be frequently positive in Hashimoto patients. However, in another method using human thyroidal microsomes (purified by ultracentrifugation) as sensitizing antigen, some heterogenous antibodies including anti-thyroglobulin antibody might be detected together with the antibody against the antigen proper to thyroidal micorsome (HF antigen)which is derived from hyperfunctioning thyroidal follicular cells of Grave's patients. hAnti-HF antibody is frequently detected both in Hashimoto and Grave's patients. In other thyroid diseases the titers of both thyroidal autoantibodies were generally low, though higher than in healthy subjects. The effect of aging on thyroidal autoantibodies in healthy subjects was clearly observed in females but not in males. From the results of these two test, it is possible to speculate that high=columnar and hyperfunctioning thyroidal follicular cells might exist focally in most cases of Hashimoto's thyroiditis.