Activation of the first component of human complement (C1) by antibody-antigen aggregates.

The activation of subcomponents C1r and C1s in the first component of complement, C1, when bound to antibody-antigen complexes was investigated. Activation was followed both by the splitting of the peptide chains of subcomponents C1r and C1s and by the development of proteolytic activity. For the maximum rate of activation to occur, all components must be present in approximate molar proportions of antibody: C1q:C1r:C1s of 13:1:5:5. For activation of subcomponent C1s, subcomponents C1r or C1r, but not C1r inactivated with iPr2P-F (di-isopropyl phosphorofluorideate), are effective. For activation of subcomponent C1r, subcomponents C1s, C1s or C1s inactivated with iPr2P-F are effective. Subcomponent C1s is activated by C1r, and C1r is activated autocatalytically, probably through the formation of an intermediary C1r. in which the peptide chain is unsplit but a conformational change caused by interaction with the other components has led to the formation of a catalytic site able to split subcomponent C1r to C1r.     

Puffing activity in the salivary gland chromosomes of Rhynchosciara under experimental conditions

By using the techniques of ligation of the larvae (brain and endocrine glands extirpation) and salivary gland implantation, the hormonal dependence of the activity of certain puffs of Rhynchosciara was investigated. Our results have shown that the puffing behaviour — activation and deactivation — varies according to the developmental stage in which the larvae were ligated. When the larvae were ligated just before the drastic changes in the puffing pattern, which occur prior to pupation, these changes fail to occur. When the larvae were ligated after the onset of these changes we have observed: a) some of the puffs active at the time of the ligature regress promptly, earlier than their normal timing observed in controls; b) others remain active indefinitely and c) there are still some which regress accordingly to the normal timing.The puff B2 which behaves as those in b was double checked by means of implantation experiments. Salivary glands which had puff B2 at its maximum expansion were implanted into younger larvae and that puff also remained active in the body cavity of these larvae. Hypotheses to explain the results obtained are discussed.     

Strand scission of DNA by bound adriamycin and daunorubicin in the presence of reducing agents.

Adriamycin and daunorubicin bound to covalently closed circular DNA nick the latter when reduced by sodium borohydride as demonstrated using an ethidium bromide fluorescence assay. The degradation, dependent on oxygen, is strongly inhibited by (i) superoxide dismutase (ii) catalase and (iii) sodium benzoate indicating the intermediacy in the cleavage of superoxide radical anion, hydrogen peroxide and hydroxyl radicals respectively. Less nicking of the DNA is observed by the reduced aglycones, so binding to the DNA by the aminosugar moiety assists the cleavage process. Adriamycin, daunorubicin and both ring C reduced forms bind intercalatively and completely relax supercoiled DNA. The results provide a possible rationale for the degradation of DNA which accompanies anthracycline administration.     

Test of the electro-ultrafiltration method's applicability in soil analysis. Reproducibility of the method

Summary The applicability of the Electro-Ultra-Filtration (EUF) method in soil analyses was studied. The reproducibilities of the amounts of soil extracts, of ion concentrations in the extracts and of the distribution of cations and anions over the cathode and anode extracts by use of fully automatic EUF equipment were tested. The degree of variability among replicates was expressed as coefficient of variation (CV) and as the highest percentual divergence of an individual analytical measurement from the mean (L). The extraction volumes of five replicates of six different soils were found to vary between 1.1–7.1% with an average of 3.8%, as CV and between 1.5–11.3% as L. The reproducibility of desorbed P in the anode extract varied between 2.7–31.7% with an average of 8.7%, as CV and between 3.2–37.9% as L. Corresponding values for CV and L of K desorbed varied between 1.3–13.9% and 1.6–23.8%, respectively. Variations among replicates of desorbed P were especially high in the first 1–2 sub-fractions of a total of seven fractions in a single extraction run. Low K concentrations in the extract had a slightly negative influence on the reproducibility of K desorption. Furthermore, it was found that a portion of the cations is collected in the anode extract and a portion of the anions in the cathode extract, especially at the beginning of an extraction run. Pooling of anode and cathode extracts before analysis is therefore recommended.     

THE SYNTHESIS OF CHOLINE PHOSPHOGLYCERIDES IN THE GIANT FIBRE SYSTEM OF THE SQUID

The mechanisms and pathways of synthesis of phosphatidylcholine in the giant fibre system of the squid (Loligo vulgaris) have been examined by incubating the stellate ganglion-nerve preparation or its separated compartments in an artificial bathing solution with labelled choline. Other experiments were done by dissecting the whole stellate ganglion into axoplasm, axon sheath, giant fibre lobe, small fibres and ganglion residue, after incubation. The initial rate of choline incorporation into choline phosphoglycerides was severalfold higher in the lobe than in the axon. Higher lipid radioactivity was recovered in the axon sheath as compared to the axoplasm, and in the small fibres as compared to the ganglion residue which contains its cell bodies. The production of phosphorylcholine and CDP-choline in the intact ganglion-nerve preparation during incubation with choline points to the occurrence of the net synthesis pathway for phosphatidylcholine in this material. Base-exchange activity was also observed in the axon and giant fibre lobe preparations in vitro, but no indication can yet be given whether it also takes place in intact preparations. Electrical stimulation and‘depolarizing’conditions enhance choline phosphorylation in the squid axon and lobe, but decrease phosphatidylcholine labelling.     

The structure and enzymic activities of the C1r and C1s subcomponents of C1, the first component of human serum complement.

The subcomponents C1r and C1s and their activated forms C-1r and C-1s were each found to have mol.wts. in dissociating solvents of about 83000. The amino acid compositions of each were similar, but there were significant differences in the monosaccharide analyses of subcomponents C1r and C1s, whether activated or not. Subcomponents C1r and C1s have only one polypeptide chain, but subcomponents C-1r and C-1s each contain two peptide chains of approx. mol.wts. 56000 ("a" chain) and 27000 ("b" chain). The amino acid analyses of the "a" chains from each activated subcomponent are similar, as are those of the "b" chains. The N-terminal amino acid sequence of 29 residues of the C-1s "a" chain was determined, but the C-1r "a" chain has blocked N-terminal amino acid. The 20 N-terminal residues of both "b" chains are similar, but not identical, and both show obvious homology with other serine proteinases. The difference in polysaccharide content of the subcomponents C-1r and C-1s is most marked in the 'b' chains. When tested on synthetic amino acid esters, subcomponent C-1r hydrolysed both lysine and tyrosine ester bonds, but subcomponent C-1r did not hydrolyse any amino acid esters tested nor any protein substrate except subcomponent C1s. The lysine esterase activity of subcomponent C1s provides a rapid and sensitive assay of the subcomponent.     

Two cases of trisomy 21 and one XXY case with atypical clinical features

Summary Three patients with mental retardation and multiple congenital abnormalities are described.Although their clinical appearance was not suggestive of Down's syndrome, chromosome studies showed a non-disjunctional trisomy 21 in two of the patients. The third case had an unsuspected XXY karyotype.     

Naturally acquired CD8+ cytotoxic T lymphocytes against the Plasmodium falciparum circumsporozoite protein.

In rodent malaria model systems, protective immunity induced by immunization with irradiated sporozoites is eliminated by in vivo depletion of CD8+ T cells, and adoptive transfer of CTL clones against the circumsporozoite protein protects against malaria. We recently demonstrated that volunteers immunized with irradiated Plasmodium falciparum sporozoites produce CTL against peptide 368-390 of the P. falciparum circumsporozoite protein. To determine whether natural exposure to malaria induced similar CTL, we studied 11 adult, male, life-long residents of a highly malarious area of Kenya, who were selected because their lymphocytes had been shown to proliferate after stimulation with peptides 361-380, 371-390, or 368-390 and because nine had been resistant to malaria in previous studies. In four of the 11 individuals there was peptide-specific, genetically restricted, CTL activity. In all four individuals, this activity was unaffected by depletion of CD4+ T cells. In three volunteers the activity was eliminated or reduced by depletion of CD8+ T cells; in the fourth volunteer the CD8+ T cell depletion was uninterpretable. This first demonstration of CD8+ T cell, genetically restricted, Ag-specific CTL against a malaria protein among individuals exposed to endemic malaria provides a foundation for studying the relationship between circulating CTL and resistance to malaria infection.     

Semicontinuous ethanol fermentation of sugar cane blackstrap molasses by pressed yeast

Summary A mathematical model is proposed to explain the influence of the volume fraction of inoculum on the fermentation time and ethanol productivity in semicontinuous ethanol fermentation of sugar cane blackstrap molasses by pressed yeast.Nomenclature a, b, c, d constants, see equation (5) - E_o initial ethanol concentration - E_f final ethanol concentration - K₁, K₂, K₃ constants, see equation (1) - P ethanol productivity - P_c calculated values of P - P_e experimental values of P - r correlation coefficient - S_o initial TRS concentration - S_m TRS concentration of the feeding mash - T fermentation time (average of the experimental values) - T_c calculated value of T - T_e experimental value of T - TRS total reducing sugars calculated as glucose - U_o initial urea concentration - U_m urea concentration of the feeding mash - V reactor working volume - V_i volume of the inoculum - volume fraction of inoculum=V_i/V