Ketogenic Diet Increases Glutathione Peroxidase Activity in Rat Hippocampus

Ketogenic diets have been used in the treatment of refractory childhood epilepsy for almost 80 years; however, we know little about the underlying biochemical basis of their action. In this study, we evaluate oxidative stress in different brain regions from Wistar rats fed a ketogenic diet. Cerebral cortex appears to have not been affected by this diet, and cerebellum presented a decrease in antioxidant capacity measured by a luminol oxidation assay without changes in antioxidant enzyme activities—glutathione peroxidase, catalase, and superoxide dismutase. In the hippocampus, however, we observed an increase in antioxidant activity accompanied by an increase of glutathione peroxidase (about 4 times) and no changes in lipoperoxidation levels. We suggest that the higher activity of this enzyme induced by ketogenic diet in hippocampus might contribute to protect this structure from neurodegenerative sequelae of convulsive disorders.     

Insulin-like immunoreactivity in the human brain

Summary The localization and regional distribution of insulin-like immunoreactivity (IRI) was studied in human brain autopsy material using the indirect immunofluorescence technique. A positive reaction for IRI could be observed in many neurons of the hypothalamus, the hippocampus, corpus amygdaloideum, medulla oblongata (especially within the nuclei of cranial nerves IX, X and XII), and the cerebral cortex, whereas the cerebellar cortex was lacking in immunohistochemically detectable insulin-like material. No nerve fibres containing polypeptides could be revealed. Additionally, the inuslin content of various brain regions was estimated by radioimmunosassay. Insulin concentrations in human nervous tissue were found to be elevated in comparison to blood plasma levels.The present investigation was supported by the HFR Neurobiologie und Hirnforschung and the HFR Diabetes mellitus und Fettstoffwechselstörungen of the GDR (Ministries of Higher Education and Health respectively) and the Finnish Ministry of Education     

A putative alpha-helical porin from Corynebacterium glutamicum

The cell wall of Corynebacterium glutamicum contains a mycolic acid layer, which is a protective nonpolar barrier similar to the outer membrane of Gram-negative bacteria. The exchange of material across this barrier requires porins. Porin B (PorB) is one of them. Recombinant PorB has been produced in Escherichia coli, purified, crystallized and analyzed by X-ray diffraction, yielding 16 independent molecular structures in four different crystal forms at resolutions up to 1.8 Å. All 16 molecules have the same globular core, which consists of 70 residues forming four α-helices tied together by a disulfide bridge. The 16 structures vary greatly with respect to the 29 residues in the N- and C-terminal extensions. Since corynebacteria belong to the group of mycolata that includes some prominent human pathogens, the observed structure may be of medical relevance. Due to the clearly established solid structure of the core, the native porin has to be oligomeric, and the reported structure is one of the subunits. An α-helical porin in a bacterial outer envelope is surprising because all presently known structures of such porins consist of β-barrels. Since none of the four crystal packing arrangements was compatible with an oligomeric membrane channel, we constructed a model of such an oligomer that was consistent with all available data of native PorB. The proposed model is based on the required polar interior and nonpolar exterior of the porin, on a recurring crystal packing contact around a 2-fold axis, on the assumption of a simple C_n symmetry (a symmetric arrangement around an n-fold axis), on the experimentally established electric conductivity and anion selectivity and on the generally observed shape of porin channels.     

Transformation of NIH 3T3 fibroblasts by an activated form of p59hck.

Phosphorylation of a tyrosine residue near the carboxy terminus of src-family protein tyrosine kinases is believed to regulate the biological activity of these gene products. Conversion of this tyrosine in p59hck (Tyr-501) to a phenylalanine residue by using oligonucleotide-directed mutagenesis yielded a product (p59hckF501) with very potent transforming activity. Quantitative analysis by a soft-agar cloning assay revealed that p59hckF501 was more than 100-fold more effective than a closely related transforming element, p56lckF505, in colony formation. Cells bearing p59hckF501 had increased levels of protein phosphotyrosine. The ability of p59hckF501 to transform NIH 3T3 cells was abolished by a second mutation believed to destroy the ATP-binding domain.     

Vaccinia Neutralization Test Using a Radioisotope Assay for Virus-induced Enzyme Activity

Vaccinia virus induction of a metabolic activity in host cell cultures forms the basis of a new assay for neutralizing antibodies. A direct relationship between the amount of vaccinia virus infecting cell cultures and the induced incorporation of tritium-labeled thymidine into the acid-insoluble fraction of the cells provided an indicator system. A liquid scintillation spectrometer was used to determine radioactivity associated with cell materials, and it provided a method for partial automation of an immunological procedure. Reproducibility of the method was satisfactory, and agreement with conventional vaccinia serum neutralization tests was demonstrated.     

A comparison of structural characteristics between old-growth and postfire second-growth hemlock–hardwood forests in Adirondack Park, New York, U. S. A.

1 This study compares the structural characteristics of 12 old‐growth and six postfire second‐growth hemlock–northern hardwood stands in north central Adirondack Park, New York, in order to test the null hypothesis that there are no differences in species composition, size structure, age structure and attributes such as dead wood and canopy gaps between old‐growth stands and this type of second‐growth forest. 2 The second‐growth forests of this study regenerated following widespread logging‐related fires in either 1903 or 1908; the old growth and second growth have similar environmental settings. 3 Estimates of stand ages, derived from an increment core of the oldest tree in each stand, range from 88 to 390 years. 4 Structural attributes are related to stand age (i.e. stage of development). In comparison with the second‐growth forests of this study, older stands are characterized as (a) a larger average diameter of canopy trees; (b) a greater basal area of trees; (c) a lower density of canopy trees and of all trees ≥ 10 cm d.b.h.; (d) a higher density of eastern hemlock (Tsuga canadensis (L.) Carrière) trees; (e) a higher density of large trees (≥ 50 cm d.b.h.); (f) larger canopy gaps; and (g) a greater volume of coarse woody debris (both logs ≥ 20 cm d.b.h. and snags ≥ 10 cm d.b.h.). 5 Despite differences between old growth and second growth, especially in species composition, it appears from observations of the 18 stands that second‐growth forests are developing some structural characteristics of old growth. 6 Structural attributes of the old‐growth forests are similar to characteristics of the same forest type in geographically distant areas in eastern USA.     

Myelosarcomatosis of the skin preceding leukemic generalization of acute myelomonocytic leukemia

A case report of a patient with myelosarcomatosis of the skin six months preceding leukemic generalization of acute myelomonocytic leukemia is presented. To the best of our knowledge this is the first case of a myelosarcoma with generalized skin involvement diagnosed before development of an overt myeloproliferative disease.     

Turnover of O-Glucosides of Dihydrozeatin and Dihydrozeatin-9-riboside During the Cell Growth Cycle of Photoautotrophic Cell Suspension Cultures of Chenopodium rubrum

The cellular levels of O-glucosides of ³H-(diH)Z and ³H-(diH)[9R]Z, the major short-term metabolites of ³H-(diH)Z having been exogenously supplied to photoautotrophically growing suspension cell cultures of Chenopodium rubrum, decreased significantly during further culture, irrespective of whether the cells were maintained in the stationary phase or were transferred to conditions restoring cell divison. Metabolism of both compounds was more pronounced during the active growth phase than during the stationary phase. The O-glucosides were converted preferentially to polar compounds of as yet unknown nature, which were partly excreted into the medium. The cellular pools of both glycosides remained compartmented within the vacuole. In contrast to the O-glycosides, the small cellular pools of the aglycones ³H-(diH)Z and ³H-(diH)[9R]Z maintained their level during the experimental period of 30 days. Small amounts of the glucosides, as well as of the aglycones, were recovered from the medium and could have resulted from the lysis of a few cells. The results demonstrate, for the first time, that O-glucosides of cytokinins are not irreversibly deposited within the vacuole of plant cells but may serve to maintain a small, but more or less constant pool of extra-vacuolar, presumably cytosolic, aglycones. (DiH)Z and its derivatives could be demonstrated to be endogenous cytokinins of Chenopodium rubrum suspension cultured cells occurring along with those of the isopentenyladenine and zeatin types.