Therapy of bovine ocular squamous-cell carcinoma with local doses of interleukin-2: 67% complete regressions after 20 months of follow-up

We have tested the therapeutic potency of peritumorally injected low doses of interleukin-2(IL-2). Seventy tumours of the bovine ocular squamous-cell carcinoma (BOSCC), 1–3 cm in diameter, were treated with 5000, 20 000 or 200 000 U IL-2 from Eurocetus (Chiron) to find the optimal dose for treatment. Injections were given peritumorally on Monday to Friday on 2 consecutive weeks. The size of the tumours was measured before treatment and 1, 3, 4, 9 and 20 months after treatment. After 9 months complete regression was observed in 89% of the tumours treated with 5000 U IL-2, 80% treated with 20 000 U and 67% treated with 200 000 U. After 20 months, there was complete regression of 35%, 31% and 67% of the tumours respectively. The 9-and 20-month results of the 200 000-U treatment are significantly better than those of the 5000-U and 20 000-U treatments taken together. This protocol may be useful to treat advanced inoperable tumours (e.g. of the nasopharynx or skin) of human patients.     

High-level expression in Escherichia coli of calcium-binding domains of an embryonic sea urchin protein

A plasmid expression vector is described having features that facilitate high-level expression of eukaryotic DNA in Escherichia coli. The vector, designated pMAM17, carries the ColE1 rop gene under the control of the thermally inducible lambda PL promoter. The rop gene product is a negative regulator of ColE1 DNA replication, and its high-level expression is lethal to cells. However, cells harboring a plasmid with an insert in the rop gene grow normally under these conditions. pMAM17 has been used to investigate the properties of a family of proteins expressed in the dorsal ectoderm of sea urchin embryos. The coding sequences of these proteins (termed Spec proteins) have homology to the troponin C superfamily. Large amounts of the Rop-Spec fusion protein were produced at 42 degrees C in E. coli. Unfractionated E. coli extracts containing the fusion protein could be used to produce antibodies that were highly specific for Spec proteins present in crude extracts of sea urchin embryos. Analysis of the Rop-Spec fusion protein on SDS-polyacrylamide gels in the presence and absence of EGTA indicated that the fusion protein bound calcium ions in a manner characteristic of proteins of the troponin C superfamily. This behavior provides biochemical evidence that the Spec proteins are functionally homologous to other members of this superfamily.     

Therapeutic application of various immunostimulators on the L2C guinea-pig leukemia

Summary Immunostimulators such as Corynebacterium parvum (C. parvum), Bacillus Calmette-Guerin (BCG), pyran copolymer, and glucan were examined in the guinea pig L ₂ C lymphoblastic leukemia model to determine their capacity for therapeutic modulation of the immune response of the host toward controlling leukemic cell proliferation. The dose, route, and frequency of administration of the stimulators were also evaluated as a function of time in order to obtain an optimal antileukemic effect. Results indicated that only C. parvum and BCG were capable of significantly increasing host survival when given 1 day after an inoculation of 1.5×10 ⁴ viable leukemic cells. Administration of BCG or C. parvum, alone or in combination with irradiated blast cells on either days 4 or 7, was totally ineffective in prolonging survival. In the majority of cases, enhanced leukemic growth was observed on these days. The combination of BCG and/or C. parvum with irradiated syngeneic blast cells given 24 h after leukemia inoculation promoted a synergistic response with a significant increase in median survival time and a number of long-term survivors.This work was supported by contract N01-CP-53566 within the Virus Cancer Program of the National Cancer Institute     

Deoxyribonucleic acid sequence organization of a yeast plasmid.

Two-micrometer deoxyribonucleic acid (DNA), a circular plasmid of Saccharomyces cerevisiae, contains two nontandem repeated sequences which are inverted with respect to one another. These repeated sequences together account for 21% of the molecule length. Restriction endonuclease analysis and electron microscopy demonstrated the existence of two forms of 2-mum DNA differing in the orientation of the interstitial segments bounded by the inverted repeated sequences. The two forms of 2-mum DNA could result from an intramolecular reciprocal recombination between inverted repeat elements. A map containing the restriction endonuclease sites and the units of the inverted repeat has been constructed.     

Acute effects of testosterone on serum PGE2 levels in male dogs

Serum prostaglandin levels are influenced by testosterone. To test the hypothesis that the effect of testosterone is mediated through the prostate gland, testosterone was given acutely to intact and to prostatectomized male dogs. Intact dogs responded to testosterone with an abrupt, transient rise in plasma PGE2 levels; prostatectomized dogs did not respond. We conclude that testosterone has an acute effect on the prostate gland which results in release of PGE2 into the blood stream.     

Receptors for the complement C3d component and the Epstein-Barr virus are quantitatively coexpressed on a series of B-cell lines and their derived somatic cell hybrids

Various human Burkitt lymphoma and LCL lines established in vitro and their derived somatic cell hybrids were tested for their comparative EBV receptor levels in a virus binding assay. Their graded C3b and C3d complement receptor expression was estimated simultaneously by means of isotope labeled rosette marker cells. The receptor concentration of each cell line was related to Raji as the standard of comparison, K 562, P3HR-1, and YACUT were used as negative controls. In general, the charging curves for EBV and C3d receptors parallelled each other (r = 0.97) while C3b receptor charging showed no correlation (r < 0.60). In the Raji hybrids between the C3b receptor positive Raji parent and various patents that were negative for this receptor, C3b receptor expression was low or negative. In contrast, the C3d negative P3HR-1 line gave rise to hybrids, after fusion with receptor-positive cells, that were intermediate with regard to their C3d receptor expression. The host range restriction of the Epstein-Barr virus is determined at the receptor level. The close relationship between the EBV receptor and the C3d receptor, a B-lymphocyte-specific moiety, suggests that the moderate interaction with EBV with the B lymphocytes may have had a selective advantage, favoring the presence of EBV. Since EBV causes lytic infections after artificial introduction into nonnatural host cells, it may represent a B-lymphocyte-specific host range mutant, derived from an originally lytic herpesvirus with a much broader target cell range.     

Improvement of productivity and efficiency in ethanol production with ca-alginate immobilized zymomonas mobilis

Summary A three-stage reactor system was used to obtain high ethanol concentration (74 g/1) with immobilized Zymomonas mobilis DSM 424. The catalyst efficiency was improved by formation of small diameter beads and arrangement of the biocatalyst in a reactor configuration adapted to the kinetics of ethanol production. A higher productivity than reported before was obtained with 56,5 g/lh based on total working volume at a sugar conversion rate of 98%. The bioreactor was run continuously for 65d.