The discovery of acylated beta-amino acids as potent and orally bioavailable VLA-4 antagonists

Acylated beta-amino acids are described as potent, specific and orally bioavailable antagonists of VLA-4. The initial lead was identified from a combinatorial library. Subsequent optimization using a traditional medicinal chemistry approach led to significant improvement in potency (up to 8-fold) while maintaining good pharmacokinetic properties.     

Epidermal expression of the full-length extracellular calcium-sensing receptor is required for normal keratinocyte differentiation

The importance of the extracellular calcium-sensing receptor (CaR) in the stringent control of extracellular Ca(2+) concentration is well established. However, the presence of CaR in tissues not directly involved in regulating mineral ion homeostasis such as the epidermis suggests a role for CaR in other cellular functions. Although extracellular Ca(2+) regulates the differentiation of epidermal keratinocytes, the role of CaR in this process in the epidermis is not fully understood. In this study we showed using in situ hybridization and immunohistochemistry that CaR is expressed in suprabasal keratinocytes of the mammalian epidermis. We then evaluated the changes in epidermal keratinocyte morphology and differentiation in Casr(-/-) mice lacking the full-length CaR. These mice show increased expression of an alternatively spliced form of CaR which lacks acute Ca(2+)-signaling properties. The absence of the full-length CaR in the epidermis resulted in ultrastructural changes (abnormal keratohyalin granule formation and precocious lamellar body secretion) in the terminally differentiated granular keratinocytes. Furthermore, the expression of both mRNA and protein for the calcium inducible keratinocyte differentiation markers, filaggrin and loricrin, were down-regulated in the epidermis of Casr(-/-) mice, whereas the number of proliferating cells were increased even though the calcium gradient within the epidermis was enhanced. Our results demonstrate that the epidermal expression of the full-length CaR is required for the normal terminal differentiation of keratinocytes.     

Effect of binding of Cd2+ on bacterial reaction center mutants: proton-transfer uses interdependent pathways

In bacterial reaction center of Rhodobacter sphaeroides, Cd2+ binds in stoichiometric amount to the protein. In the wild type, this results into a notable decrease of the rates of electron-transfer between the two quinone acceptors after the first (kAB(1)) and second flash (kAB(2)). We have studied these effects in two single mutants, L209PY and L209PF. L209Pro is situated in a protein region rich in hydrogen-bond networks involving water molecules. We show that (1) the combined effects of Cd2+ binding and point mutations have a cumulative consequence in the two mutants, decreasing very substantially the observed rates of electron-transfer. Interestingly, the [Cd2+] titration curves of kAB(2) in the L209PY and L209PF mutants are nearly superimposable to those previously reported for the M17DN and L210DN mutants (Paddock, M. L., Feher, G., and Okamura, M. Y. (2000) Proc. Natl. Acad. Sci U.S.A. 97, 1548-1553). These observations suggest a common effect of all of these mutations (L209, M17, L210) on the protonation state of the histidine cluster to which Cd2+ binds; (2) in the L209PY mutant, the pH titration curves of kAB(1), kAB(2), and k(H)(+), the proton-transfer rate at the second flash, are systematically downshifted by 1.5-2 pH units in the presence of 300 microM Cd2+, similarly to the wild type RCs (Gerencser, L., and Maroti, P. (2001) Biochemistry 40, 1850-1860). We propose that Cd2+ binding influences the electrostatics of interdependent ways of proton penetration within the protein, involving at least, directly or indirectly, L209P, L210D, and M17D, probably in conjunction with hydrogen-bonded connected water molecules.     

Epstein-Barr virus encoded nuclear protein EBNA-3 binds a novel human uridine kinase/uracil phosphoribosyltransferase

Background  

Epstein-Barr virus (EBV) infects resting B-lymphocytes and transforms them into immortal proliferating lymphoblastoid cell lines (LCLs) in vitro. The transformed immunoblasts may grow up as immunoblastic lymphomas in immuno-suppressed hosts.     

Highly sensitive chromatographic assay for dopamine determination during in vivo cerebral microdialysis in the rat

A highly sensitive, yet simple, isocratic high-performance liquid chromatographic (HPLC) assay with electrochemical detection (ED) for the determination of extracellular dopamine (DA) in brain microdialysates is presented. The method makes possible the detection of less than 100 pM (less than 1 fmol on column) and the quantitation of 200 pM (2 fmol on column) of DA with the use of a narrow-bore rather than capillary or microbore column. Analysis is feasible within an 11-min run-time, and thus is suitable for the relatively short sampling intervals used in microdialysis experiments. In the calibration range of 0.2 to 10 nM, the method has excellent linearity and precision, with intra-day relative standard deviations (RSD) of 0.5-2.4% and between-day RSD of 2.1-4.3%.     

Transglutaminase-Catalyzed Protein Cross-Linking in the Molecular Program of Apoptosis and Its Relationship to Neuronal Processes

1. One type of transglutaminase is usually accumulated in various forms of naturally occurring cell death and apoptosis. The accumulated enzyme is activated during the death process, leading to the formation of cross-linked protein structures. Degradation of the cross-linked apoptotic bodies results in the elevation of the (-glutamyl)lysine isodipeptide concentration in body fluids, which may provide a diagnostic tool to monitor the apoptosis rate in various tissues under normal and pathologic conditions.2. Extensive protein cross-linking may be directly related to the act of killing in some cells. In others, the effect of protein cross-linking is palliative, preventing leakage of macromolecules and enhancing phagocytosis of the dead cells.3. Tissue transglutaminase has been implicated in some physiologic functions of the nervous system.4. The molecular machinery of apoptosis is present and easily evoked in neuronal cells.5. Effector elements of the apoptosis process have been associated with the pathogenesis of neurologic disorders. Tissue transglutaminase, representing one of the effector elements of apoptosis, may be induced and activated in cells following ischemia. It may also participate in the formation of abnormal cell inclusions and A deposits in amyloid plaques.     

Metabolic alterations in cotyledons of Cucurbita pepo infected by cucumber mosaic virus

Changes in the capacities of enzymes in various metabolic pathwayshave been measured during infection of cotyledons of Cucurbitapepo L. with cucumber mosaic virus (CMV). Starch accumulationand low sucrose content, which are characteristic of the earlystages of infection, are reversed in the later stages of infection.The decline in starch correlated with a reduced capacity forstarch synthesis (ADP-glucose pyrophosphorylase) and a risein the capacity for starch degradation (total starch hydrolase,starch phosphorylase). ¹⁴CO₂ feeding experiments, conductedat saturating CO₂ concentration, show that the newly-assimilatedcarbon was lost at a lower rate from infected cotyledons andless was incorporated into structural carbohydrates, phosphorylatedintermediates plus organic acids, more into soluble sugars,amino acids and proteins. At a later stage of infection therewere dramatic increases in respiratory capacity and a substantialalteration of carbohydrate metabolism. The infection had a largestimulatory effect on the capacity for oxidative pentose-phosphatepathway (glucose-6-phosphate dehydrogenase, 6-phospho-gluconatedehydrogenase), glycolysis (ATP- and pyrophosphate-dependentphosphofructokinases), tri-carboxylic acid cycle (isocitratedehydrogenase, fumarate hydratase), anaplerotic reactions (NAD-dependentmalic enzyme, phosphoenolpyruvate car-boxylase) and oxidativeelectron transport (cytochrome c oxidase). While there wereno overall changes in photosynthetic rate (measured in saturatingCO₂), infection either reduced (Rubisco and glycerate kinase)or did not affect (chloroplastic fructose bis-phosphatase andhydroxypyruvate kinase) the capacities of the photosyntheticcarbon reduction pathway or the photosynthetic carbon oxidationpathway. Key words: Plant-virus interaction, sucrose, starch, enzymes, ¹⁴CO₂ incorporation, O₂ flux     

A study on thermal environment for physically handicapped persons. Results from Japanese-Hungarian joint experiment in 1990

1. 1. For the scientific evaluation of thermal environment in relatin to human health and comfort, a number of indices have been proposed in the recent 70 years.

2. 2. However, even the newest indices are still not sufficient to explain the general thermal environment for all people including infants, the aged, the disabled etc., because such indices are based more or less on experiments using college age persons.

3. 3. Series of studies to find required thermal conditions for the disabled and the aged have been carried out from 1976 in Japan and from 1988 in Hungary.

4. 4. In 1990, the Japanese and Hungarian research groups have collaborated in an international joint experiment on the thermal environment for the disabled.

5. 5. This paper reports on the results from the first step examinations of the data from above mentioned joint experiment.

Effect of amino acid analogs on the development of thermotolerance and on thermotolerant cells

Exposure of HA-1 Chinese hamster fibroblasts to amino acid analogs has been shown to have a heat-sensitizing effect as well as inducing the heat shock response (Li and Laszlo, 1985a). In this study, we have examined the effect of amino acid analogs on the development of thermotolerance after a brief heat shock or exposure to sodium arsenite and the effect of amino acid analogs on cells that are already thermotolerant. Exposure of HA-1 cells to amino acid analogs inhibited the development of thermotolerance following a mild heat shock or treatment with sodium arsenite. However, cells that were already thermotolerant were resistant to the sensitizing action of amino acid analogs. The refractoriness of thermotolerant cells to amino acid analog treatment developed in parallel with thermotolerance. The uptake of the arginine analog, canavanine, and its incorporation into proteins was not altered in the thermotolerant cells. Furthermore, another biological consequence of exposure to amino acid analogs, sensitization to ionizing radiation, also was not altered in the thermotolerant cells. The inhibition of the development of thermotolerance by amino acid analogs and the refractoriness of thermotolerant cells to the heat-sensitizing action of amino acid analogs lend further support the role of heat-shock proteins in the phenomenon of thermotolerance. © 1993 Wiley-Liss, Inc.