Morphometric Differentiation among Experimental Lines of the Housefly in Relation to a Bottleneck

Differentiation in morphometric traits among experimental populations of the housefly subjected to an experimental bottleneck was examined for replicate lines founded with one, four or 16 pairs of flies. Differentiation among lines within a bottleneck size was significantly greater than predicted by drift in relation to the additive genetic variation for these traits within the founding population. Two models of nonadditive genetic variance were investigated to interpret these results, one involving dominance of allelic effects within loci and another incorporating multiplicative epistasis. Both models generated more variation among lines as a direct result of sampling during the bottleneck than predicted by a model with additive gene action. The pattern of differentiation among our experimental lines in relation to these models conformed more to the model incorporating epistasis. Nevertheless, it may be difficult to distinguish differentiation among lines occurring during a bottleneck as a result of nonadditive gene action from that caused by diversifying selection among lines after the bottleneck.     

Effect of selenium and vitamin E dietary deficiencies on chick lymphoid organ development

Diets specifically deficient in selenium (Se) and/or vitamin E or adequate in both nutrients were fed to chicks from the time of hatching. Lymphoid organs (bursa, thymus, and in some instances, spleen) were collected from chicks 7-35 days of age. Growth of the chicks fed these diets was monitored over the experimental period as was lymphoid organ growth. The development of the primary lymphoid organs was further assessed by histological techniques and the organ contents of vitamin E (alpha-tocopherol) and Se were determined. Specific deficiencies of either Se or vitamin E were found to significantly impair bursal growth as did a combined deficiency. Thymic growth was impaired only by the combined deficiency diet. Severe histopathological changes in the bursa resulted from the combined deficiency and these were detectable by 10-14 days after hatching. These changes were characterized by a gradual degeneration of the epithelium and an accompanying depletion of lymphocytes. Similar changes, although slower to develop and less severe, were observed in the thymus as a result of the combined deficiency. When both serum and tissue levels of vitamin E and Se were monitored, it was observed that these were rapidly and independently depleted by the specific deficiency diets. These data suggest that the primary lymphoid organs are major targets of Se and vitamin E dietary deficiencies and provide a possible mechanism by which immune function may be impaired.     

Relationship between estrone sulfate in plasma and litter size at farrowing for sows and gilts

A positive association (P < 0.01) was detected between estrone sulfate (ES) concentrations in maternal plasma at Day 30 of pregnancy and litter size at parturition in swine. This relationship was best described by a fifth order regression equation (R(2) = 0.5) which indicated that as ES increased from 1 to 7.5 ng/ml on Day 30, litter size increased from 0 (nonpregnant) to 18 piglets farrowed. Day of sampling (P < 0.02), month (P < 0.04) and parity (P < 0.08) were major sources of variation in the model. This indicated that effects of environmental factors such as heat stress, which influence conception rate and embryonic survival, are reflected in changes in maternal ES. Also, larger litter size associated with parous sows is reflected in increased ES in maternal plasma. We conclude that measurement of ES early in gestation may be useful in reproductive management to identify nonpregnant gilts and sows as well as those with small litters.     

Comparison of the Limulus amoebocyte lysate test with plate counts and chemical analyses for assessment of the quality of lean fish.

The quality of lean fish was assessed simply and rapidly with Limulus amoebocyte lysate. The endotoxin levels agreed with aerobic plate counts and chemical indices of spoilage. Correlation between level of endotoxin and level of total volatile bases was found to be highly significant (r = 0.8579; P less than 0.001).     

Bioavailability of selenium accumulated by selenite-reducing bacteria

The bioavailability of selenium (Se) was determined in bacterial strains that reduce selenite to red elemental Se (Se^o). A laboratory strain ofBacillus subtilis and a bacterial rod isolated from soil in the vicinity of the Kesterson Reservoir, San Joaquin Valley, CA, (Microbacterium arborescens) were cultured in the presence of 1 mM sodium selenite (Na₂SeO₃). After harvest, the washed, lyophilizedB. subtilis andM. arborescens samples contained 2.62 and 4.23% total Se, respectively, which was shown to consist, within error, entirely of Se^o. These preparations were fed to chicks as supplements to a low-Se, vitamin E-free diet. Three experiments showed that the Se in both bacteria had bioavailabilities of approx 2% that of selenite. A fourth experiment revealed that gray Se^o had a bioavailability of 2% of selenite, but that the bioavailability of red Se^o depended on the way it was prepared (by reduction of selenite). When glutathione was the reductant, bioavailability resembled that of gray Se^o and bacterial Se; when ascorbate was the reductant, bioavailability was twice that level (3–4%). These findings suggest that aerobic bacteria such asB. subtilis andM. arborescens may be useful for the bioremediation of Se-contaminated sites, i.e., by converting selenite to a form of Se with very low bioavailability.     

A proof of principle experiment for microbeam radiation therapy at the Munich compact light source

Microbeam radiation therapy (MRT), a preclinical form of spatially fractionated radiotherapy, uses an array of microbeams of hard synchrotron X-ray radiation. Recently, compact synchrotron X-ray sources got more attention as they provide essential prerequisites for the translation of MRT into clinics while overcoming the limited access to synchrotron facilities. At the Munich compact light source (MuCLS), one of these novel compact X-ray facilities, a proof of principle experiment was conducted applying MRT to a xenograft tumor mouse model. First, subcutaneous tumors derived from the established squamous carcinoma cell line FaDu were irradiated at a conventional X-ray tube using broadbeam geometry to determine a suitable dose range for the tumor growth delay. For irradiations at the MuCLS, FaDu tumors were irradiated with broadbeam and microbeam irradiation at integral doses of either 3 Gy or 5 Gy and tumor growth delay was measured. Microbeams had a width of 50 µm and a center-to-center distance of 350 µm with peak doses of either 21 Gy or 35 Gy. A dose rate of up to 5 Gy/min was delivered to the tumor. Both doses and modalities delayed the tumor growth compared to a sham-irradiated tumor. The irradiated area and microbeam pattern were verified by staining of the DNA double-strand break marker γH2AX. This study demonstrates for the first time that MRT can be successfully performed in vivo at compact inverse Compton sources.     

Metabolism of selenite to selenosugar and trimethylselenonium in vivo: tissue dependency and requirement for S-adenosylmethionine-dependent methylation

Impaired S-adenosylmethionine (SAM)-dependent transmethylation and methylation capacity feature in diseases related to obesity or aging, and selenium (Se) metabolism is altered in these states. We tested the hypothesis that SAM metabolism is required for methylation and excretion of Se in a rat model. Four hours after selenite and periodate-oxidized adenosine (POA; an inhibitor of SAM metabolism) were administered, circulating markers of single-carbon status were unchanged, except for decreased circulating phosphatidylcholine (P<.05). In contrast, liver and kidney SAM and S-adenosylhomocysteine were elevated (P<.05 for all). Concentrations of total Se were significantly elevated in both liver (P<.001) and kidney (P<.01), however the degree of accumulation in liver was significantly greater than that of kidney (P<.05). Red blood cell Se levels were decreased (P=.01). Trimethylselenonium levels were decreased in liver and kidney (P=.001 for both tissues) and Se-methyl-N-acetylselenohexosamine selenosugar was decreased in liver (P=.001). Urinary output of both trimethylselenonium (P=.001) and selenosugar (P=.01) was decreased as well. Trimethylselenonium production is more inhibited by POA than is selenosugar production (P<.05). This work indicates that low molecular weight Se metabolism requires SAM-dependent methylation, and disrupting the conversion of SAM to S-adenosylhomocysteine prevents conversion of selenite and intermediate metabolites to final excretory forms, suggesting implications for selenium supplementation under conditions where transmethylation is suboptimal, such as in the case of obese or aging individuals.     

Aminoimidazoles as bioisosteres of acylguanidines: novel, potent, selective and orally bioavailable inhibitors of the sodium hydrogen exchanger isoform-1

Inhibition of the sodium hydrogen exchanger isoform-1 (NHE-1) has been shown to limit damage to the myocardium under ischemic conditions in animals. While most known NHE-1 inhibitors are acylguanidines, this report describes the design and synthesis of a series of heterocyclic inhibitors of NHE-1 including aminoimidazoles with undiminished in vitro activity and oral bioavailability.     

Albumin binding as a general strategy for improving the pharmacokinetics of proteins

Plasma protein binding can be an effective means of improving the pharmacokinetic properties of otherwise short lived molecules. Using peptide phage display, we identified a series of peptides having the core sequence DICLPRWGCLW that specifically bind serum albumin from multiple species with high affinity. These peptides bind to albumin with 1:1 stoichiometry at a site distinct from known small molecule binding sites. Using surface plasmon resonance, the dissociation equilibrium constant of peptide SA21 (Ac-RLIEDICLPRWGCLWEDD-NH(2)) was determined to be 266 +/- 8, 320 +/- 22, and 467 +/- 47 nm for rat, rabbit, and human albumin, respectively. SA21 has an unusually long half-life of 2.3 h when injected by intravenous bolus into rabbits. A related sequence, fused to the anti-tissue factor Fab of D3H44 (Presta, L., Sims, P., Meng, Y. G., Moran, P., Bullens, S., Bunting, S., Schoenfeld, J., Lowe, D., Lai, J., Rancatore, P., Iverson, M., Lim, A., Chisholm, V., Kelley, R. F., Riederer, M., and Kirchhofer, D. (2001) Thromb. Haemost. 85, 379-389), enabled the Fab to bind albumin with similar affinity to that of SA21 while retaining the ability of the Fab to bind tissue factor. This interaction with albumin resulted in reduced in vivo clearance of 25- and 58-fold in mice and rabbits, respectively, when compared with the wild-type D3H44 Fab. The half-life was extended 37-fold to 32.4 h in rabbits and 26-fold to 10.4 h in mice, achieving 25-43% of the albumin half-life in these animals. These half-lives exceed those of a Fab'(2) and are comparable with those seen for polyethylene glycol-conjugated Fab molecules, immunoadhesins, and albumin fusions, suggesting a novel and generic method for improving the pharmacokinetic properties of rapidly cleared proteins.