Studies on humoral immunity against Taenia taeniaeformis infection in rats

Rats were infected with doses of 100, 1000, 5000 and 10 000 eggs of Taenia taeniaeformis. Haemagglutinating antibody to cysticerus antigen was detected at the 4th week of infection. The appearance and levels of antibody titre did not vary greatly with the infective dose. An IgM peak appeared at the 6th week, with IgG appearing slightly later and continuing to rise. Transfer of serum from the 1st week onwards from infections with 1000 eggs however could confer significant protection. Dilutions of hyperimmune serum (1 ml volumes) of up to 1/32 conferred significant protection on normal recipients. Hyperimmune serum transferred up to 4 days before challenge could confer 80% protection whereas serum transferred 4 days after challenge was totally non-protective. The significance of this finding is discussed in the light of current knowledge of metacestode immunity.     

Effect of diamfenetide on experimental infections of Fasciola hepatica in lambs: anthelmintic and clinical investigations.

The activity of diamfenetide (N,N'-[oxybis(2,1-ethan diyloxy-4,1-phenylene)] bis acetamide) was studied in lambs experimentally inoculated with Fasciola hepatica. The drug was given orally at a dose level of 100 mg/kg either 1,3,5,7, or 9 weeks postinoculation. It was 100% effective 1, 3, and 5 weeks postinoculation, 73% effective 7 weeks postinoculation, and 57% effective 9 weeks postinoculation. Serum gamma-glutamyl transpeptidase activity remained normal in all lambs for 5 weeks after infection; it then began to increase in infected, untreated lambs at 6 weeks, and had increased 5- to 6-fold 9 weeks postinoculation in infected lambs. This enzyme activity was the most sensitive hematologic parameter used in this test to detect hepatobiliary damage by the parasite. The drug was well tolerated at the dose level used.     

A model for intramolecular recombination of herpesvirus DNA leading to the formation of circular, circular-linear and fragmented genomes.

A model is presented for intramolecular recombination of herpesvirus DNA. It is proposed that the terminal repeat sequences of the viral DNA contain insertion sequences which may integrate with homologous repeat sequences between the long (L) and short (S) components. In class 2 herpes-virus DNA (as defined by Honess &; Watson, 1977) in which the repeat sequences flank the S component only, circular-linear DNA molecules can be formed as an intermediate step. Reorientation of the S component leads to the formation of two DNA isomers. In class 3 herpesvirus DNA in which repeat sequences flank both the L and S components, either circular-linear or 8-shaped DNA molecules are proposed as intermediates leading to the formation of four DNA isomers. Fragmentation of the S component could lead to the formation of small circular DNA molecules.     

Improved synthesis of 16alpha-hydroxylated androgens: intermediates of estriol formation in pregnancy.

16alpha-Hydroxyandrostenedione (16alpha-hydroxyandrost-4-ene-3,17-dione), 16alpha-hydroxytestosterone (16alpha,17beta-dihydroxyandrost-4-en-3-one) and 16alpha-hydroxydehydroepiandrosterone 3-sulfate (3beta, 16alpha-dihydroxyandrost-5-en-17-one 3-monosulfate) were synthesized by a new chemical approach with much improved yield. 16alpha-Bromoandrostendione was converted to the hydrazone of 16alpha-hydroxyandrostenedione which gave 16alpha-hydroxyandrostenedione on acid hydrolysis in total 63% yield. Oxidation of 16alpha-hydroxydehydroepiandrosterone with Jones' reagent also selectively afforded 16alpha-hydroxyandrostenedione. 16alpha-Hydroxytestosterone was observed by selective reduction of 16alpha-hydroxyandrostenedione with sodium borohydride. Reaction of 16alpha-hydroxydehydroepiandrosterone with chlorosulfonic acid in pyridine selectively gave the 3-monosulfate. The structure of the sulfate was deduced from its solvolysis to the starting material, and its acetylation and subsequent solvolysis to 16alpha-hydroxydehydroepiandrosterone 16-acetate. All procedures are suitable for large scale synthesis without the use of microorganisms.     

The fibrous structure of coelacanth scales: A twisted ‘Plywood’

Isopedin is a network of collagen bundles present in the scales of most fishes. The scales of coelacanths show a remarkable three-dimensional arrangement of this network which is similar to a regularly twisted plywood. The successive fibrous layers cross at an angle which differs slightly from a right angle. It results that the whole system is twisted. The progressive rotation of the fibril direction is right-handed. Certain preferential orientations of fibrils have been observed, namely parallel to the growth rings. Such arrangements also exist in the embryonic cornea of birds and in the cuticle of certain insects, but do not present such an extensive and regular development.     

Synthesis of tropomyosin in myogenic cultures and in RNA-directed cell-free systems: qualitative changes in the polypeptides

The synthesis of polypeptides with the properties of alpha and beta tropomyosin was investigated in differentiating cultures of a myogenic cell line and in a wheat germ cell-free system directed by purified RNA extracted at different stages of differentiation. The polypeptides co-migrate with tropomyosin in isoelectric focusing and SDS two-dimensional gel electrophoresis and SDS-urea/SDS two-dimensional gels. Like authentic tropomyosin, these polypeptides change their mobility greatly in the presence of urea and do not become labeled with proline. The beta tropomyosin synthesized in the intact cells and in the cell-free system can be separated by isoelectric focusing into at least two components. One component (designated beta1) is present in a small amount at all developmental stages examined, and a more basic component (beta2) is specific for differentiated cultures. The synthesis of beta2 in the intact cells and the capacity of purified RNA to direct its synthesis in a cell-free system become detectable and increase greatly during the period of fusion of the mononucleated cells into multinucleated fibers. The results suggest that the beta1 and beta2 tropomyosins are coded for by different genes.     

Maintenance of a certain rumen protozoal population in a continuous in vitro fermentation system.

A continuous culture system suitable for maintaining certain rumen protozoa was developed by modifying the procedure of Walter and Pilgrim (R.A. Weller and A.F. Pilgrim, Br. J. Nutr. 32:341-351, 1974) to include a dialyzing system. The concentration of ciliate protozoa, the pH value, and concentrations of volatile fatty acid and ammonia-N could be maintained within normal rumen limits for more than 15 days by appropriate choice of mechanical agitation and of the amount of substrate and physical form of the substrate bags. The average concentration of protozoa in the free fluid around the substrate was about 10% that in the fluid squeezed from solid digesta residues. More than 10(6) protozoa per ml was present in the fresh substrates only 2 h after supplying the substrate. These facts suggest that sequestration of the protozoa among particulate digesta is an important factor in maintaining the concentration of protozoa.     

Catechol and phenol degradation by a methanogenic population of bacteria

An anaerobic population of bacteria became acclimated to catechol and phenol in 32 and 18 days, respectively. Evidence from carbon balance measurements indicates that the aromatic ring is cleaved and that the products are stoichiometrically fermentable to methane and carbon dioxide.     

Arrest of 3T3 cells in G1 phase by low density lipoprotein

Low density lipoprotein (LDL) and high density lipoprotein (HDL) were purified from normal human serum by KBr density gradient centrifugation and gel filtration through Sepharose 4B. LDL reversibly inhibited proliferation of Swiss/3T3 cells, whereas HDL had no inhibitory effect on cell growth. The LDL-induced inhibition was LDL-dose dependent and was reversed by the addition of mevalonate, a product of the reaction of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase (mevalonate: NADP+ oxidoreductase (CoA-acylating), EC 1.1.1.34). These data suggest that a specific reduction in the activity of HMG-CoA reductase produced by the addition of LDL is the main cause of the inhibition of cell proliferation. Studies of the effect of LDL on the cell cycle showed that it inhibited the entry of cells arrested in G0/G1 into the S phase but that it did not affect the transition of cells at the G1/S boundary into the M phase. The cell cycle of 3T3 is arrested solely in G1 by LDL.