Prevention of acute liver failure in rats with reversibly immortalized human hepatocytes

Because of a critical shortage in suitable organs, many patients with terminal liver disease die each year before liver transplantation can be performed. Transplantation of isolated hepatocytes has been proposed for the temporary metabolic support of patients awaiting liver transplantation or spontaneous reversion of their liver disease. A major limitation of this form of therapy is the present inability to isolate an adequate number of transplantable hepatocytes. A highly differentiated cell line, NKNT-3, was generated by retroviral transfer in normal primary adult human hepatocytes of an immortalizing gene that can be subsequently and completely excised by Cre/Lox site-specific recombination. When transplanted into the spleen of rats under transient immunosuppression, reversibly immortalized NKNT-3 cells provided life-saving metabolic support during acute liver failure induced by 90% hepatectomy.     

Operant controlled neural event: formal and systematic approach to electrical coding of behavior in brain

Traditional studies of electrophysiological correlates of behavior contain inherent high variability resulting from the arbitrary choice of behaviors, brain locations, and wave parameters. The operant control of neural events is a formal and systematic approach to the study of prespecified parameters and components of brain activity as they encode behaviors. Two studies in which the electrical activity of brain was the criterion for reinforcement demonstrate the acquisition, under such operant control, of two mutually exclusive behaviors or states which selectively alter evoked potential components.     

Vapor pressures of solid hydrates of nitric Acid: implications for polar stratospheric clouds

Thermodynamic data are presented for hydrates of nitric acid: HNO(3).H(2)O, HNO(3).2H(2)O, HNO(3).3H(2)O, and a higher hydrate. Laboratory data indicate that nucleation and persistence of metastable HNO(3).2H(2)O may be favored in polar stratospheric clouds over the slightly more stable HNO(3).3H(2)O. Atmospheric observations indicate that some polar stratospheric clouds may be composed of HNO(3).2H(2)O and HNO(3).3H(2)O. Vapor transfer from HNO(3).2H(2)O to HNO(3).3H(2)O could be a key step in the sedimentation of HNO(3), which plays an important role in the depletion of polar ozone.     

Mixed lymphocyte reactions and tissue transplantation tolerance

The induction of tolerance of Lewis histocompatibility antigens in BN rats inoculated at birth with BNI Lewis F(1) hybrid bone marrow cells, as revealed by the prolonged survival of Lewis skin grafts, is accompanied by markedly decreased reactivity in the mixed lymphocyte interaction. Blood lymphocytes from animals inoculated with lymph node cell suspensions also display diminished proliferative reactivity to hybrid BN/Lewis cells in the interaction. However, these recipients are not tolerant of Lewis skin grafts. Blood lymphocytes from BN rats inoculated neonatally with Lewis thymocytes fail to display any level of unresponsiveness in vitro, and such animals are not tolerant of Lewis skin grafts. The results suggest that in rats skin and marrow cells have histocompatibility antigens that are absent or poorly expressed on lymph node cells and thymocytes.     

Social Cost of Tail Loss in Uta stansburiand

Tail removal from dominant juvenile Uta stansburiana resulted in a decrease in social status in dyadic encounters. Most lizards were affected after removal of two-thirds of their tails. In some pairs, dominant lizards lost status after removal of one-third of their tails but regained dominance after the other member of the pair lost two-thirds of its tail. Tail loss in nature may impose a social handicap to successful home range acquisition and thereby increase risk of death.     

Suppression of mutations in mitochondrial DNA by tRNAs imported from the cytoplasm

Mitochondrial import of a cytoplasmic transfer RNA (tRNA) in yeast requires the preprotein import machinery and cytosolic factors. We investigated whether the tRNA import pathway can be used to correct respiratory deficiencies due to mutations in the mitochondrial DNA and whether this system can be transferred into human cells. We show that cytoplasmic tRNAs with altered aminoacylation identity can be specifically targeted to the mitochondria and participate in mitochondrial translation. We also show that human mitochondria, which do not normally import tRNAs, are able to internalize yeast tRNA derivatives in vitro and that this import requires an essential yeast import factor.