The hooded allele and selection of wild Norway rats Rattus norvegicus for behavior

Selection of wild gray rats for domestication (tame behavior) resulted in a sharp increase in the frequency of heterozygotes at the h allele of hooded, the main locus of rat depigmentation. The observed effect of the selection on the manifestation of the h allele is compared with similar effects giving rise to piebaldness in other animals subjected to experimental domestication. The results are discussed in terms of genetic specificity of piebaldness and of the selection vector.     

Dual inhibition of human type 4 phosphodiesterase isostates by (R, R)-(+/-)-methyl 3-acetyl-4-[3-(cyclopentyloxy)-4-methoxyphenyl]-3- methyl-1-pyrrolidinecarboxylate

Purified recombinant human type 4 phosphodiesterase B2B (HSPDE4B2B) exists in both a low- and a high-affinity state that bind (R)-rolipram with Kd's of ca. 500 and 1 nM, respectively [Rocque, W. J., Tian, G., Wiseman, J. S., Holmes, W. D., Thompson, I. Z., Willard, D. H., Patel, I. R., Wisely, G. B., Clay, W. C., Kadwell, S. H., Hoffman, C. R., and Luther, M. A. (1997) Biochemistry 36, 14250-14261]. Since the tissue distribution of the two isostates may be significantly different, development of inhibitors that effectively inhibit both forms may be advantageous pharmacologically. In this study, enzyme inhibition and binding of HSPDE4B2B by (R, R)-(+/-)-methyl 3-acetyl-4-[3-(cyclopentyloxy)-4-methoxyphenyl]-3-methyl-1-pyrrolidin ecarboxylate (1), a novel inhibitor of phosphodiesterase 4 (PDE 4), were investigated. Binding experiments demonstrated high-affinity binding of 1 to HSPDE4B2B with a stoichiometry of 1:1. Inhibition of PDE activity showed only a single transition with an observed Ki similar to the apparent Kd determined by the binding experiments. Deletional mutants of HSPDE4B2B, which have been shown to bind (R)-rolipram with low affinity, were shown to interact with 1 with high affinity, indistinguishable from the results obtained with the full-length enzyme. Bound 1 was completely displaced by (R)-rolipram, and the displacement showed a biphasic transition that resembles the biphasic inhibition of HSPDE4B2B by (R)-rolipram. Theoretical analysis of the two transitions exemplified in the interaction of (R)-rolipram with HSPDE4B2B indicated that the two isostates were nonexchangeable. Phosphorylation at serines 487 and 489 on HSPDE4B2B had no effect on the stoichiometry of binding, the affinity for binding, or the inhibition of the enzyme by 1. These data further illustrate the presence of two isostates in PDE 4 as shown previously for (R)-rolipram binding and inhibition. In contrast to (R)-rolipram, where only one of the two isostates of PDE 4 binds with high affinity, 1 is a potent, dual inhibitor of both of the isostates of PDE 4. Kinetic and thermodynamic models describing the interactions between the nonexchangeable isostates of PDE 4 and its ligands are discussed.     

Resumption of follicular waves in beef cows is not associated with periparturient changes in follicle-stimulating hormone heterogeneity despite major changes in steroid and luteinizing hormone concentrations

To test the hypothesis that emergence of follicle waves postpartum is associated with a change in circulating FSH isoform distribution, 10 Limousin-cross suckler cows were blood sampled daily from 5 wk prepartum until first ovulation postpartum for FSH, LH, estradiol (E2), and progesterone assay. Follicular growth was monitored daily by ultrasonography from Days 5 to 10 postpartum until first ovulation. Distributions of circulating FSH isoforms were characterized (n = 4 per group) by chromatofocusing at 1) 18-33 days prepartum, 2) 3-5 days prepartum, 3) the first postpartum FSH rise responsible for emergence of the first follicle wave, and 4) the FSH rise that stimulated the ovulatory follicle wave. The interval to detection of the first postpartum dominant follicle (DF) was 9.6 +/- 0.58 days. The number of DF before first ovulation was 2.1 +/- 0.18, and first ovulation occurred at 28.6 +/- 1.54 days postpartum. Serum E2 concentrations were higher (p = 0.0001) in cows during the 5-wk period prepartum (53.8 +/- 6.29 pg/ml) than in the postpartum period up to first ovulation (1.5 +/- 0.15 pg/ml). In late pregnancy, there was an absence of recurrent FSH rises and LH concentrations were decreased (p < 0.0001) compared with those in the postpartum period. The emergence of each follicle wave postpartum was preceded by a 2- to 4-day rise in FSH concentrations. The pattern of FSH isoform distribution did not differ (p > or = 0.75) between the pre- and postpartum periods.     

Molecular modeling of the interaction of diagnostic radiopharmaceuticals with receptor proteins: m2 antagonist binding to the muscarinic m2 subtype receptor

Models of the m2 muscarinic receptor have been built and acetylcholine and an antagonist of the quinuclidinyl benzilate family docked to the putative active site. We have incorporated aspects of homology, site-directed mutagenesis studies and structure-activity studies of specific lead compounds in the construction of our receptor models with a primary focus on the structure of the binding sites. We have observed a deep pocket binding of 5-BrQNT, suggesting a plausible explanation for the observation that agonists and antagonists do not bind competitively. The results of these computational studies are interpreted within the context of the observed in vitro results. Our goal is to assist in the development of subtype receptor selective radiopharmaceuticals for use in PET and SPECT.     

Specific [3H]8-OH-DPAT binding in brain regions of rats genetically predisposed to various defense behavior strategies

BACKGROUND AND PURPOSE: We examined the 20-or-more-year survival and functional levels of 148 stroke survivors and 148 age- and sex-matched control subjects from the Framingham Study Cohort, whom we originally studied in 1972-1974 to ascertain the survival and disability status of stroke survivors compared with that of controls. METHODS: This long-term evaluation was done with use of data from the 1993-1995 Framingham Study Cohort Examination 23 on the 10 stroke survivors and 20 control subjects still living to identify and compare the host characteristics and functional status of each group. The survival curves for both stroke survivors and controls were derived from the ongoing Framingham Study database. RESULTS: Twenty-plus-year stroke survivors experienced a greater mortality than age- and sex-matched controls (92.5% and 81%, respectively). The slopes of the two survival curves were essentially the same. Functional status (eg, walking and independence in activities of daily living) of stroke survivors, however, compared very favorably with that of the control subjects. Stroke survivors were more likely to be female and to have a number of comorbidities, including elevated blood pressures, greater use of medications, less use of alcohol, and less depressive symptomology. CONCLUSIONS: In the Framingham cohort, 20-plus-year stroke survivors showed greater mortality than age- and sex-matched control subjects; functionally, however, the groups were very similar and in general quite independent.     

A hexapeptide VTKFYF from C-terminal part of interleukin-1 receptor antagonist, an inhibitor of IL-1-IL-1 receptor interaction

In order to find the low-molecular-weight interleukin-1 (IL-1) inhibitors we synthesized a series of peptides, derived from three regions of interleukin-1 receptor antagonist (IL-1ra): N-terminal (residues 5-9), central (90-98) and C-terminal (143-148). The decision was based on the thorough analysis of structural and functional properties of IL-1 proteins and the resemblance of some fragments of IL-1ra to well-known immunomodulators, like thymopentin and tuftsin. The competition between our peptides and IL-1 was measured as the inhibition of IL-1 induced IL-2 production in LBRM/CTLL cell line system. The activity of tuftsin (TKPR), a peptide immunomodulator derived from IgG molecule, was also examined. All peptides presented some activity, although the most interesting results (when the range of activity and dose-dependence were taken into account) were obtained for tuftsin and peptide VTKFYF from the C-terminal part of IL-1ra, which is in agreement with the latest reports on the structure of IL-1ra-receptor complex.     

Cyclolinopeptide A (CLA) mediates its immunosuppressive activity through cyclophilin-dependent calcineurin inactivation

The immunosuppressive cyclic nonapeptide cyclolinopeptide A inhibits calcium-dependent, but not calcium-independent, activation of T lymphocytes comparably to the actions of cyclosporin A and FK506. The concentration required for complete inhibition, however, is 10 times higher than that of cyclosporin A. In addition, we demonstrate that calcineurin, a phosphatase which plays an important role in T lymphocyte signalling, is inhibited in vitro by cyclolinopeptide A by a mechanism dependent on the peptidyl-prolyl cis-trans isomerase (PPIase) cyclophilin A but not FKBP12. Direct binding of cyclolinopeptide A to cyclophilin A was confirmed using tryptophan fluorescence studies and PPIase assays. These results represent a third example of the production of a natural product that neutralises calcineurin by a mechanism dependent on the primary binding to a PPIase.