Diet and Health

The role of diet in personal health maintenance is important whether a person is trying to stay healthy or to treat diet-related diseases such as hypercholesterolemia, hypertension, diabetes mellitus or obesity. Dietary recommendations include limiting fat to 30% and protein to 20% of total calories, with the remaining 50% coming from carbohydrate. Maintaining dietary changes for long periods is very difficult for many persons. Specific self-management skills may ease the task.     

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.     

Antibodies distinguishing between intact and alkali-hydrolyzed 7-methylguanosine

Antibodies specific for intact 7-methylguanosine (m7G) were induced in rabbits and mice by immunization with nucleoside-BSA or nucleoside-hemocyanin conjugates. Since m7G undergoes alkali-catalyzed hydrolytic fission of the purine ring, modifications were made in the procedure for conjugation of m7G to proteins. After periodate oxidation, m7G was incubated with protein at pH 9.1 at 4 degrees C for one hour during which the nucleoside was found to be stable. Reduction of the Schiff base was done with t-butylamine borane for 30 minutes, and the conjugated protein was isolated quickly by gel filtration at pH 7.2. Both rabbits and mice produced antibodies that readily distinguished between the intact and hydrolyzed m7G. Antibody specificity depended largely on the presence of an intact 7-substituted imidazole ring and some cross-reaction occurred with 7-methylinosine. A weaker reaction occurred with ribothymidine and thymidine. Mouse antibodies induced by m7G-hemocyanin showed the highest specificity. They also recognized m7G in the isolated mRNA cap structure m7G(5')ppp(5')A.     

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.     

Inhibition of glycoconjugate secretion by colchicine and cytochalasin B

Summary The effects have been analyzed of cytochalasin B and colchicine on the secretion of glycoconjugates by human bronchial expiants labeled in vitro with radioactive glucosamine. Both cytochalasin B and colchicine had no effect on baseline ¹⁴C-labeled glycoconjugate release but caused a dose-dependent (10^–7–10^–4 M) inhibition of ¹⁴C-glycoconjugate release and discharge of labeled macromolecules from mucous and serous cells induced by 5 · 10^–5 M methacholine.Quantitative autoradiographic analyses showed that neither cytochalasin B nor colchicine inhibited ³H-threonine or ³H-glucosamine incorporation into mucous and serous cells of the submucosal glands or goblet cells of the airway epithelium. Colchicine (10^–5 M) but not cytochalasin B significantly reduced the rate at which labeled macromolecules were transported through mucous, serous and goblet cells but this effect was not observed until 4 h after the addition of colchicine. Neither cytochalasin B nor colchicine affected the basal rate of labeled-macromolecule discharge from mucous, serous or goblet cells. At a concentration of 10^–5 M, both agents completely inhibited the increase in labeled-macromolecule discharge induced in mucous and serous cells by methacholine.Our results suggest that in the submucosal gland of human airways microtubules and microfilaments may be important in secretagogue-induced but not in baseline cellular glycoconjugate discharge, implying that the mechanisms of the two processes differ significantly. Furthermore, a role for microtubules is suggested in the transport of secretory granules through mucous, serous and goblet cells.Supported by National Institutes of Health Research Grant 5R01HL22444. The authors gratefully acknowledge the technical assistance of Mr. Tudor Williams, Mr. Eduardo Quintanilla and Ms. Maureen Hayes     

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.     

A comprehensive examination of protein sequences for evidence of internal gene duplication

Summary We have implemented a routine procedure for screening protein sequences for evidence of intragenic duplications. We tested 163 protein sequences representing 116 superfamilies of unrelated proteins. Twenty superfamilies contain proteins with internal gene duplications. The intragenic duplications detected can be divided into two major types. (1) One or more duplications of all or part of a gene produce a protein with two or several detectable regions of sequence homology. Sequences from 18 superfamilies contained this type of duplication. (2) Repeated reduplication of a small DNA segment can produce a protein that is repetitive over most of its length. Three superfamilies contain such repetitive sequences. We also investigated the limits of detection of ancient duplications using sequences derived by random mutation of a model sequence consisting of ten 10-residue repeats. The original repetitive nature of the sequence was usually detected after 250 point mutations even though the ancestral segment could not be accurately reconstructed.