Enhanced natural killer (NK) cell activity and NK-sensitive thymic cells in murine muscular dystrophy

Studies have shown that there is an abnormality in the thymus of dystrophic mice with respect to age-dependent thymus weight changes and altered morphology (T. DeKretser and B. Livett, Nature (London), 263, 682, 1976). Recently, others have shown that natural killer (NK) cells can lyse cells of a large, immature, rapidly dividing cell subpopulation within the thymus of normal young (3 weeks of age) mice (M. Hansson, K. Karre, R. Kiessling, J. Roder, B. Anderson, and P. Hayry, J. Immunol., 123, 765, 1979). The NK susceptibility of dystrophic mouse thymocytes as targets was therefore studied. Spleen cells from normal (+/+) and dystrophic ($\text{dy}{}^{\mathrm{2J}}\text{dy}{}^{\mathrm{2J}}$) male C57BL/6J mice 8–10 weeks old were passed over nylon wool and the nonadherent cells were incubated with ⁵¹Cr-labeled YAC-1 lymphoma target cells or thymocytes in a ⁵¹Cr-release assay. Spleen cells from dystrophic mice killed twofold more YAC-1 target cells than did spleen cells from normal mice. Thymocytes from 3- to 4-week-old dystrophic mice were three to four times more susceptible to NK lysis by dystrophic mouse spleen cells as compared with normal mouse spleen cells. Spleen cells from dystrophic mice had the same NK activity against dystrophic and normal mouse thymocytes as targets. Normal mouse spleen cells killed three- to fourfold more dystrophic mouse thymocytes than that of normal mouse thymocytes as targets. Target cellbinding studies revealed that conjugate-forming cells from nylon nonadherent dystrophic mouse spleen cells were found to be two- to fourfold greater than for normal mouse spleen cells using YAC-1 tumor cells as targets. The number of lymphocytes bound per YAC-1 target cell ranged from 2 to 5 for dystrophic mouse spleen cells as compared with 1 to 2 for the normal control group. Using both normal and dystrophic mouse thymocytes as targets, the conjugate-forming cells from dystrophic mouse spleen cells were also found to be twofold greater than in the normal control group. Cold target inhibition studies revealed that the natural killing of dystrophic mouse thymocytes was due to a YAC-1-reactive NK cell. Effector cell depletion studies using monoclonal anti-Thy-1.2 plus complement treatment and plastic petri dish adherence also revealed that the natural killing of dystrophic mouse thymocytes was not due to either T lymphocytes or macrophages. Taken together, these results show an increase in NK-sensitive thymocyte targets in dystrophic mice, in combination with an increase in splenic NK activity.     

Differential activation of the mouse beta-globin promoter by enhancers.

A series of plasmids was constructed to study the effect of two enhancers, the simian virus 40 72-base-pair repeat and the Harvey sarcoma virus 73-base-pair repeat, on the mouse beta maj-globin promoter. These plasmids contain the mouse beta maj-globin promoter linked to the Escherichia coli galK gene, thus allowing galactokinase enzyme activity to be used as a measure of promoter function. In CV-1 (primate) cells, it was found that an enhancer is required for optimal promoter activity and that the simian virus 40 (primate) enhancer increases galactokinase fourfold more than the Harvey sarcoma virus (mouse) enhancer. In L (mouse) cells, however, the Harvey sarcoma virus enhancer is 1.3-fold stronger than the simian virus 40 enhancer. These data support the hypothesis that enhancer activity can be species specific. Furthermore, when both enhancers are present on the same plasmid, their effect is additive on the beta-globin promoter whether the plasmid is in CV-1 cells or L cells.     

Highly purified particulate guanylate cyclase from rat lung: characterization and comparison with soluble guanylate cyclase

Guanylate cyclase was purified 1000-fold from washed rat lung particulate fractions to a final specific activity of 500 nmoles cyclic GMP produced/min/mg protein by a combination of detergent extraction and chromatography on concanavalin A-Sepharose, GTP-agarose, and blue agarose. Particulate guanylate cyclase has a molecular weight of 200 000 daltons, a Stokes radius of 48 A and a sedimentation coefficient of 9.4 while the soluble form has a molecular weight of 150 000 daltons, a Stokes radius of 44 A, and a sedimentation coefficient of 7.0. Whereas the particulate enzyme is a glycoprotein with a specific affinity for concanavalin A and wheat germ agglutinin, the soluble form of guanylate cyclase did not bind to these lectins. Purified particulate guanylate cyclase did not cross-react with a number of monoclonal antibodies generated to the soluble enzyme. While both forms of the enzyme could be regulated by the formation of mixed disulfides, the particulate enzyme was relatively insensitive to inhibition by cystine. With GTP as substrate both forms of the enzyme demonstrated typical kinetics, and with GTP analogues negative cooperativity was observed with both enzyme forms. These data support the suggestion that the two forms of guanylate cyclase possess similar catalytic sites, although their remaining structure is divergent, resulting in differences in subcellular distribution, physical characteristics, and antigenicity.     

Apparent synergism between amino donors for CTP synthesis in Chinese hamster fibroblasts

The synergistic effects of potential amino donors were studied in the assay of CTP synthetase in extracts of Chinese hamster fibroblasts. We found that L-glutamine was not effective as the sole amino donor, but combinations of L-glutamine with NH4HCO3, L-arginine or potassium phosphate did result in the conversion of UTP to CTP. L-arginine or potassium phosphate were also not effective when used alone, and NH4HCO3 was only slightly effective. Our studies demonstrate that the individual synergistic combinations were not additive; multiple combinations of components decreased rather than increased the formation of CTP. The synergistic combinations of L-glutamine with either NH4HCO3 or L-arginine had an absolute requirement for ATP; when ATP and PEP were absent no conversion of UTP to CTP occurred. The presence of GTP in a reaction mixture slightly increased the formation of CTP when L-glutamine and NH4HCO3 were used and substantially increased CTP formation when L-glutamine and L-arginine were used. De novo CTP synthesis was greatly reduced when nonradioactive CTP was added to an assay mixture, suggesting feedback inhibition. A TLC procedure has been developed that allows for the direct separation of UTP and CTP without requiring prior conversion to the mononucleotide or nucleoside level.     

Structural and functional studies of the adrenal zona glomerulosa in sodium-depleted and sodium-loaded sheep

Cell and Tissue Research - The effects of alterations in sodium status upon the morphology of the adrenal zona glomerulosa in sheep have been examined qualitatively and quantitatively, using...     

Effects of Legal Abortion on Gynaecology

The effect of the Abortion Act on gynaecological work in one provincial teaching hospital is that despite an increase in patient turnover of 45% the waiting list has increased by 200%. It is suggested that the Act has had little effect on the birth rate or illegitimacy and that there may have been an increase in criminal abortion.     

Association of newly synthesized major fl coat protein with infected host cell inner membrane

The bacteriophage fl major coat protein becomes associated with the host cell inner membrane very shortly after it is synthesized. Pulse-chase experiments suggest that the virus is never stably associated with the host cell outer membrane; we propose that it passes directly from the inner membrane to the growth medium.     

Determination of Rubella Hemagglutination-Inhibiting Antibody in Whole Blood

A technique is described for determination of rubella hemagglutination-inhibiting antibody in only 50 to 100 muliters of whole blood.     

Transmission of Salmonella montevideo in Wheat by Stored-Product Insects

Sitophilus oryzae (L.), S. granarius (L.), Tribolium castaneum (Hbst.), Oryzaephilus surinamensis (L.), Rhyzopertha dominica (F.), Tenebroides mauritanicus (L.), and Cryptolestes pusillus (Schon.) transmitted Salmonella montevideo from wheat contaminated with 10(6) organisms/g to clean wheat. The insects were fed on the contaminated grain for 21 days and were then transferred to clean grain and allowed to feed for 21 days. They were subsequently transferred to two more samples of clean wheat. All species carried S. montevideo into the initial sample of clean wheat but not into a second or third sample. Progeny of the original insects that developed in the contaminated wheat exhibited less ability than the original adults to contaminate clean wheat. Data indicated that few S. montevideo could be carried by the stored-product insects in large masses of grain.