Eimeria tenella: specific reversal of t-butylaminoethanol toxicity for parasite and host by choline and dimethylaminoethanol.

t-Butylaminoethanol is an anticoccidial compound that is related structurally to the metabolically active substances, dimethylaminoethanol, and choline. Toxic effects of t-butylaminoethanol for chickens and Eimeria tenella are specifically overcome by feeding sufficient amounts of dimethylaminoethanol or choline. Dietary concentrations of the two above metabolites required to totally overcome toxic effiects of t-butylaminoethanol were determined and are expressed as the reversal ratio, inhibitor (t-butylamino-ethanol): metabolite. The inhibitor:choline ratio for total reversal of toxic effects of the inhibitor in chickens is approximately 1:10 over a concentration range of inhibitor from 0.019 to 0.05%. The inhibitor:choline ratio for reversal of antiparasitic effects is approximately 1:200 with a concentration of 0.01% inhibitor. The inhibitor:Dimethylaminoethanol ratio for reversal of toxic effects of the inhibitor in the chicken is approximately 1:7 with a concentration of 0.015% inhibitor. The inhibitor:dimethylaminoethanol ratio for reversal of antiparasitic effects is approxmately 1:20 wth a concentration of 0.01% inhibitor.     

Immune enhancing effect of a growth hormone secretagogue

Growth hormone (GH) has been known to enhance immune responses, whether directly or through the insulin like growth factor-1, induced by GH. Recently a nonpeptidyl small m.w. compound, a GH secretagogue (GHS), was found to induce the production of GH by the pituitary gland. In this study, we examined the effect of GHS in immunological functions of 5- to 6-wk-old and 16- to 24-month-old mice. In young mice, we observed a significant increase in PBLs, but T and B cell-proliferative responses were not consistently enhanced. The old mice, treated with GHS for 3 wk, did not show increases in peripheral lymphocytes, but they exhibited a statistically significant increase in thymic cellularity and differentiation. When inoculated with a transplantable lymphoma cell line, EL4, the treated old mice showed statistically significant resistance to the initiation of tumors and the subsequent metastases. Generation of CTL to EL4 cells was also enhanced in the treated mice, suggesting that GHS has a considerable immune enhancing effect, particularly in the old mice. We have also found that GHS promoted better thymic engraftment in bone marrow transplant of SCID mice. We found more cycling cells in the spleens of treated mice, suggesting that GHS may exert its immune enhancing effect by promoting cell division in lymphoid cells. These observations ascribe to GHS a novel therapy possible for aging, AIDS, and transplant individuals, whose immune functions are compromised.     

Ligand activation domain of human orphan growth hormone (GH) secretagogue receptor (GHS-R) conserved from Pufferfish to humans

Synthetic ligands have been identified that reset and amplify the cycle of pulsatile GH secretion by interacting with the orphan GH-secretagogue receptor (GHS-R). The GHS-R is rhodopsin like, but does not obviously belong to any of the established G protein-coupled receptor (GPCR) subfamilies. We recently characterized the closely related orphan family member, GPR38, as the motilin receptor. A common property of both receptors is that they amplify and sustain pulsatile biological responses in the continued presence of their respective ligands. To efficiently identify additional members of this new GPCR family, we explored a vertebrate species having a compact genome, that was evolutionary distant from human, but where functionally important genes were likely to be conserved. Accordingly, three distinct full-length clones, encoding proteins of significant identity to the human GHS-R, were isolated from the Pufferfish (Spheroides nephelus). Southern analyses showed that the three cloned Pufferfish genes are highly conserved across species. The gene with closest identity (58%) was activated by three synthetic ligands that were chosen for their very high selectivity on the GHS-R as illustrated by their specificity in activating the wild-type human GHS-R but not the E124Q mutant. These results indicate that the ligand activation domain of the GHS-R has been evolutionary conserved from Pufferfish to human (400 million years), supporting the notion that the GHS-R and its natural ligand play a fundamentally important role in biology. Furthermore, they illustrate the power of exploiting the compact Pufferfish genome for simplifying the isolation of endocrinologically important receptor families.     

Thiazole-derived potent, highly bioavailable short duration growth hormone secretagogues.

Replacement of the phenyl in 3 with a 2-pyridyl or 4-thiazolyl group resulted in increased potency in the rat pituitary cell GH release assay and in beagles.     

Similarities in Restriction Fragment Patterns of Mitochondrial DNAs of PhytophthoraSpecies Strongly Depend on the Restriction Enzyme Used Due to Heterogeneous Base Distribution and Sequence Conservation

Mitochondrial DNAs of six morphologically different Phytophthora species were digested with 15 restriction enzymes. The numbers of restriction fragments obtained differed considerably from those theoretically expected for random base distribution. Enzymes with relatively many G and C in their recognition sequences produced significantly larger numbers of fragments. Moreover, fragments generated by most of these enzymes were more often shared by two or more species than those from enzymes with more A and T in their recognition sequence. It is concluded that base distribution in mitochondrial DNA of Phytophthora is heterogeneous,AT-rich stretches occurring scattered over the mitochondrial genome and GC-rich regions present in conserved sequences, presumably genes. A practical consequence for taxonomic RFLP studies is that optimal enzymes can be selected, depending on the desired level of resolution.     

Tetrapod phylogeny inferred from 18S and 28S ribosomal RNA sequences and a review of the evidence for amniote relationships [published erratum appears in Mol Biol Evol 1991 May;8(3):398]

The 18S ribosomal RNAs of 21 tetrapods were sequenced and aligned with five published tetrapod sequences. When the coelacanth was used as an outgroup, Lissamphibia (living amphibians) and Amniota (amniotes) were found to be statistically significant monophyletic groups. Although little resolution was obtained among the lissamphibian taxa, the amniote sequences support a sister-group relationship between birds and mammals. Portions of the 28S ribosomal RNA (rRNA) molecule in 11 tetrapods also were sequenced, although the phylogenetic results were inconclusive. In contrast to previous studies, deletion or down- weighting of base-paired sites were found to have little effect on phylogenetic relationships. Molecular evidence for amniote relationships is reviewed, showing that three genes (beta-hemoglobin, myoglobin, and 18S rRNA) unambiguously support a bird-mammal relationship, compared with one gene (histone H2B) that favors a bird- crocodilian clade. Separate analyses of four other genes (alpha- crystallin A, alpha-hemoglobin, insulin, and 28S rRNA) and a combined analysis of all sequence data are inconclusive, in that different groups are defined in different analyses and none are strongly supported. It is suggested that until sequences become available from a broader array of taxa, the molecular evidence is best evaluated at the level of individual genes, with emphasis placed on those studies with the greatest number of taxa and sites. When this is done, a bird-mammal relationship is most strongly supported. When regarded in combination with the morphological evidence for this association, it must be considered at least as plausible as a bird-crocodilian relationship.      

Highly potent growth hormone secretagogues

During an effort to search for more potent growth hormone secretagogues, we discovered a class of compounds of which the best compound 8 was 7-fold more active in vitro than the best compound in the series we revealed before [Tata, J. R.; Lu, Z.; Jacks, T. M.; Schleim, K. D.; Cheng, K.; Wei, L.; Chan, W.-S.; Butler, B.; Tsou, N.; Leung, K.; Chiu, S.-H. L.; Hickey, G. J.; Smith, R. G.; Patchett, A. A. Bioorg. Med. Chem. Lett.1997, 7, 2319.]. Animal studies show that compound 8 can stimulate growth hormone release at the oral dose as low as 0.06 mpk. Chemistry and biological studies are discussed.