Shelf life of ground beef patties treated by gamma radiation

The effects of irradiation on microbial populations in ground beef patties vacuum package and irradiated frozen at target doses of 0.0, 1.0, 3.0, 5.0, and 7.0 kGy were determined. Irradiated samples were stored at 4 or -18 degrees C for 42 days, and mesophilic aerobic plate counts (APCs) were periodically determined. Fresh ground beef (initial APC of 10(2) CFU/g) treated with 3.0, 5.0, and 7.0 kGy was acceptable (< 10(7) CFU/g) for 42 days at 4 degrees C. The 1.0 kGy-treated beef samples were acceptable microbiologically (< 10(7) CFU/g) after 42 days but developed an unacceptable off-odor after 21 days. Shelf life diminished in fresh ground beef patties with an initial APC of 10(4) CFU/g. Only beef patties treated with 7.0 kGy were found to be acceptable at 42 days. Beef patties treated at 1.0 and 3.0 kGy reached spoilage APC levels (> 10(7) CFU/g) by day 14 and 21, respectively, whereas patties treated at 5.0 kGy did not spoil until 42 days. The nonirradiated control samples for both batches of ground beef spoiled within 7 days. Microbial counts in ground beef patties stored at -18 degrees C did not change over the 42-day period. Shelf life of ground beef patties stored at 4 degrees C may be extended with gamma radiation, especially at 5.0 and 7.0 kGy. Initial microbial load in ground beef samples was an important shelf life factor.     

Anthropocentrism and computers

This paper introduces the multi-dimensional concept of anthropocentrism with respect to computers, the tendency to believe that (1) computers do not possess human physical and psychological capabilities; and (2) it is not acceptable for computers to fill routinized (e.g., auto mechanic), interpretive (e.g., newspaper reporter), and persona) (e.g., baby sitter) roles traditionally held only by people. A mail survey (n = 133) of individuals in Northern California focuses on individual differences rather than differences between technologies. As suggested by the literature on ethnocentrism, experience with other cultures and education are strong predictors of the dimensions of anthropocentrism; surprisingly, experience with computers fails as a predictor.     

Synthetic analogues of TNP-470 and ovalicin reveal a common molecular basis for inhibition of angiogenesis and immunosuppression

TNP-470 (1), a synthetic derivative of the natural product fumagillin (2), potently inhibits angiogenesis in vivo and the growth of endothelial cell cultures in vitro. The structurally related natural product ovalicin (3) also inhibits angiogenesis but possesses potent immunosuppressive activity. The recent finding that all three drugs bind and inhibit the same target, methionine aminopeptidase 2 (MetAP2), raised the question of whether TNP-470 is also immunosuppressive and whether inhibition of MetAP2 underlies both activities of ovalicin. To address these questions, we synthesized a series of analogues of TNP-470 and ovalicin and tested them for their abilities to inhibit the proliferation of either endothelial cell or mixed lymphocyte cultures. TNP-470 and its analogues were found to possess both immunosuppressive and anti-angiogenic activities. A strong correlation was observed between the ability of compounds to inhibit bovine and human endothelial cell growth and their ability to inhibit the mouse mixed lymphocyte reaction (MLR), implying that the two activities share a common molecular basis, i.e., inhibition of MetAP2. Interestingly, ovalicin and several other compounds behaved differently in the human MLR than in either the mouse MLR or human endothelial cell proliferation assays, pointing to possible species-specific and cell type-specific differences in the metabolism or uptake of these compounds.     

Isolation of human osteoblast-like cells and in vitro amplification for tissue engineering

As the field of dental implants continues to grow at a rapid rate so does our quest to find new techniques to enhance bone grafting. Tissue engineering is an exciting new technique in bone grafting. Therefore, the purposes of this study were to develop a simple, reproducible method to isolate human osteoblast-like cells (HOBs) and to evaluate in vitro cell proliferation within 2 different 3-dimensional (3-D) constructs targeted for tissue engineering applications. Ultimately, HOBs that have been amplified within 3-D constructs may be employed for bone regeneration techniques, such as onlay and sinus grafting prior to implant placement. Our cell isolation protocol employed human fetal calvaria tissue sequentially digested with trypsin and collagenase. The HOB cells from only the third and fourth digests were obtained, cultured and evaluated within the constructs. An osteoblast-like phenotype was in part verified for these HOB cells by demonstrating a significantly higher alkaline phosphatase activity than for human gingival fibroblasts, and a comparable level to the osteoblast cell line MG-63. The HOB cells were cultured within either poly (D,L-lactide) (PLA) or a fused fiber ceramic and evaluated for the ability to support in vitro HOB amplification. HOB proliferation was validated by scanning electron microscopy, identifying cells throughout the 3-D constructs. Continuous cell viability was demonstrated for the duration of the 33-day evaluation period and the extent of cell amplification reached approximately 20 times the seeding density. The in vitro amplification results further indicate that tissue engineering strategies with either the PLA or fused fiber construct may be suitable for bone regeneration therapy for dental implants.     

Modulation of CD72 by ligation of B cell receptor complex molecules on CD5+ B cells

B cells expressing CD5 also carry its ligand, CD72. As an approach to understanding the role of CD5 and CD72 on B cells, we have examined the association of CD72 with CD5 and slgM by modulation/co-modulation and capping/co-capping following ligation of these surface molecules with specific antibodies. Modulation and co-modulation were measured after 24 h, whilst capping was measured after 1 h. CD5 and slgM co-modulated each other, CD72 co-modulated with slgM and CD5, but anti-CD72 did not affect either slgM or CD5. CD5 and slgM co-capped each other, whilst CD72 failed to co-cap with either slgM or CD5. The CD5-induced co-modulation of CD72 was partially blocked by specific protein tyrosine kinase inhibitor, but not the slgM-induced co-modulation, Protein kinase C (PKC) inhibitors abrogated the anti-mu- but not the anti-CD5-triggered modulation of CD72, whereas PKC activators prevented the CD5- but not the slgM-induced 24 h modulation of CD72. None of these drugs was able to modify the anti-CD72-induced modulation of CD72. Our data suggest that CD5 is physically associated with slgM in the B cell receptor complex but not with CD72. Furthermore, from the effect of drugs on modulation, there appears to be different associations of CD72 with slgM and CD5. These two pathways differed in some respects, consistent with a co-stimulatory function of CD72 and CD5 in B cell activation.     

Kinetic studies on the fragmentation of the third component of complement (C3) by trypsin

The kinetics of cleavage of C3 by trypsin was analyzed by electrophoresis in agarose and in polyacrylamide gels containing sodium dodecyl sulfate and the data obtained were used to construct an anatomical model for C3 showing the sites of tryptic attack, the fragments generated, and their composition. Trypsin was shown to cleave C3 in a stepwise fashion. The attack was initially directed at the alpha-polypeptide chain and resulted in the generation of C3a and C3b. Further cleavage of the alpha-chain of C3b, converted it into C3b1 and then into C3d and C3c. Cleavage of the beta-chain by trypsin occurred only at the C3c stage with the release of a small peptide (m.w. 12,000) from C3c and the formation of C3c'. On immunoelectrophoresis, C3c' had a less anodal mobility compared to the beta1A mobility of C3c. C3a, once formed could be further cleaved to give residual fragments with decreasing net positive charge. Exposure of C3 to acid conditions, pH 5.0 or below, rendered the molecule exceedingly susceptible to tryptic degradation.     

Conceptual level and structural complexity in language.

The Paragraph Completion Method (PCM) of D. E. Hunt et al (1971) has been used to identify conceptual level (CL) as a process of cognitive structuring that produces language behavior on the part of client and counselor. Independently, a Computer-Assisted Language Analysis System (CALAS) has been used to identify structural features of the counselor's and client's language. In an analysis of 39 exemplary protocols contained in a revised manual for the PCM, relations between ratings of CL and linguistic measures yielded by the CALAS were examined. Simple frequency of usage and the structural complexity of the language accounted for much of the variance in CL scores, but a dimension of CL independent of linguistic features also was identified. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Correlation between regional cerebral blood flow and oxidative metabolism. In vivo studies in man

To test the hypothesis that regional cerebral blood flow (rCBF) is normally regulated by regional metabolic activity, rCBF and the regional cerebral metabolic rate for oxygen (rCMRO2) were compared in selected human subjects. In normal subjects and patients with chronic, stable diseases of brain, rCBF correlated well with rCMRO2. In one individual with mild dementia, rCBF and rCMRO2 were measured before and during exercise of the hand and forearm contralateral to the hemisphere studied. Appropriate parallel changes occurred in both rCBF and rCMRO2 during hand exercise. In patients with acute diseases affecting the hemisphere studied, however, the correlation between rCBF and rCMRO2 was unpredictable.