Characterization of a Novel Mouse Model of Multiple Myeloma and Its Use in Preclinical Therapeutic Assessment

To aid preclinical development of novel therapeutics for myeloma, an in vivo model which recapitulates the human condition is required. An important feature of such a model is the interaction of myeloma cells with the bone marrow microenvironment, as this interaction modulates tumour activity and protects against drug-induced apoptosis. Therefore NOD/SCIDγc^null mice were injected intra-tibially with luciferase-tagged myeloma cells. Disease progression was monitored by weekly bioluminescent imaging (BLI) and measurement of paraprotein levels. Results were compared with magnetic resonance imaging (MRI) and histology. Assessment of model suitability for preclinical drug testing was investigated using bortezomib, melphalan and two novel agents. Cells engrafted at week 3, with a significant increase in BLI radiance occurring between weeks 5 and 7. This was accompanied by an increase in paraprotein secretion, MRI-derived tumour volume and CD138 positive cells within the bone marrow. Treatment with known anti-myeloma agents or novel agents significantly attenuated the increase in all disease markers. In addition, intra-tibial implantation of primary patient plasma cells resulted in development of myeloma within bone marrow. In conclusion, using both myeloma cell lines and primary patient cells, we have developed a model which recapitulates human myeloma by ensuring the key interaction of tumour cells with the microenvironment.     

Identification of an Obese Eating Style in 4‐year‐old Children Born at High and Low Risk for Obesity

This study tested whether children's eating behavior and parental feeding prompts during a laboratory test meal differ among children born at high risk (HR) or low risk (LR) for obesity and are associated with excess child weight gain. At 4 years of age, 32 HR children (mean maternal prepregnancy BMI = 30.4 kg/m²) and 29 LR children (maternal BMI = 19.6 kg/m²) consumed a test meal in which their eating behavior was assessed, including rate of caloric consumption, mouthfuls/min, and requests for food. Parental prompts for the child to eat also were measured at year 4, and child body composition was measured at ages 4 and 6 years. T‐tests, and logistic and multiple regression analyses tested study aims. Results indicated that HR and LR children did not differ in eating rate or parental feeding prompts. Greater maternal BMI, child mouthfuls of food/min, and total caloric intake/min during the test meal predicted an increased risk of being overweight or obese at age 6, whereas greater active mealtime was associated with a reduced risk of being overweight or obese. Regression analyses indicated that only mouthfuls of food/min predicted changes in BMI from 4 to 6 years, and mouthfuls of food/min and gender predicted 2‐year changes in sum of skinfolds and total body fat. Thus, a rapid eating style, characterized by increased mouthfuls of food/min, may be a behavioral marker for the development of childhood obesity.     

Human alpha-globin gene expression. The dominant role of the alpha 2-locus in mRNA and protein synthesis

The two human alpha-globin genes, alpha 1 and alpha 2, are coexpressed in normal erythroid cells and encode identical alpha-globin protein products. Based upon genetic studies, it has been assumed that these two adjacent and highly homologous genes are equally expressed. In previous studies we have, however, demonstrated that the alpha 2 gene encodes a 2-3-fold higher steady state level of mRNA than the alpha 1 gene. In the present study, we monitor the relative levels of protein production from these two loci by quantitating the synthesis of specific alpha-globin structural mutants encoded by each alpha-globin gene. These values are then used to infer the relative contributions of the normal alpha 1 and alpha 2 loci to total alpha-globin production. The results of eight separate studies, each based upon a different alpha-globin structural mutant mapped to either the alpha 1 or the alpha 2 locus, are internally consistent. The data demonstrate that the alpha 2 gene encodes 2-3-fold more protein than the alpha 1 gene. These results suggest that the human alpha-globin gene cluster contains a major and a minor locus. The dominant expression of the alpha 2 gene predicts a greater impact of mutations at this locus, in comparison to mutations at the alpha 1 locus, in the generation of the alpha-thalassemia phenotype.     

Generation of deletions in pTV1ts following transformation of Staphylococcus aureas protoplasts

Plasmid pTV1ts was introduced into Staphylococcus aureus by transformation of protoplasts at frequencies ranging from 6.6 x 10(1) to 2.8 x 10(5) per micrograms of DNA when selection was made for resistance to chloramphenicol and erythromycin, respectively. Phenotypic analysis of regenerated transformants demonstrated three distinct classes. Analysis of the plasmid profiles of several isolates revealed that two classes harboured deleted pTV1ts derivatives.     

Guano exposed: Impact of aerobic conditions on bat fecal microbiota

Bats and their associated guano microbiota provide important terrestrial and subterranean ecosystem services and serve as a reservoir for a wide range of epizootic and zoonotic diseases. Unfortunately, large‐scale studies of bats and their guano microbiotas are limited by the time and cost of sample collection, which requires specially trained individuals to work at night to capture bats when they are most active. Indirectly surveying bat gut microbiota through guano deposits could be a more cost‐effective alternative, but it must first be established whether the postdefecation exposure to an aerobic environment has a large impact on the guano microbial community. A number of recent studies on mammalian feces have shown that the impact of aerobic exposure is highly species specific; therefore, it is difficult to predict how exposure will affect the bat guano microbiota without empirical data. In our study, we collected fresh guano samples from 24 individuals of 10 bat species that are common throughout the arid environments of the American southwest and subjected the samples to 0, 1, and 12 hr of exposure. The biodiversity decreased rapidly after the shift from an anaerobic to an aerobic environment—much faster than previously reported in mammalian species. However, the relative composition of the core guano microbiota remained stable and, using highly sensitive targeted PCR methods, we found that pathogens present in the original, non‐exposed samples could still be recovered after 12 hr of exposure. These results suggest that with careful sample analysis protocols, a more efficient passive collection strategy is feasible; for example, guano could be collected on tarps placed near the roost entrance. Such passive collection methods would greatly reduce the cost of sample collection by allowing more sites or roosts to be surveyed with a fraction of trained personnel, time, and effort investments needed.     

Induction of Mn SOD in human monocytes without inflammatory cytokine production by a mutant endotoxin

Endotoxin selectively induces monocyte Mn superoxide dismutase(SOD) without affecting levels of Cu,Zn SOD, catalase, or glutathione peroxidase. However, little is known about the structure-activity relationship and the mechanism by which endotoxin induces Mn SOD. Inthis study we demonstrated that a mutant Escherichiacoli endotoxin lacking myristoyl fatty acid at the3' R-3-hydroxymyristate position of the lipid A moiety retained its full capacity to coagulate Limulus amoebocyte lysate comparedwith the wild-type E. coli endotoxinand markedly stimulated the activation of human monocyte nuclearfactor-B and the induction of Mn SOD mRNA and enzyme activity.However, in contrast to the wild-type endotoxin, it failed to inducesignificant production of tumor necrosis factor- and macrophageinflammatory protein-1 by monocytes and did not induce thephosphorylation and nuclear translocation of mitogen-activated proteinkinase. These results suggest that1) lipid A myristoyl fatty acid,although it is important for the induction of inflammatory cytokineproduction by human monocytes, is not necessary for the induction of MnSOD, 2) endotoxin-mediated inductionof Mn SOD and inflammatory cytokines are regulated, at least in part,through different signal transduction pathways, and3) failure of the mutant endotoxinto induce tumor necrosis factor- production is, at least in part,due to its inability to activate mitogen-activated protein kinase.

     

Observations on graphing paleozoological data: Suggestions for better graphs

Paleozoologists have long used graphs of diverse styles to describe, analyze, and summarize their data. Some of these graphs provide excellent visual representations of complex data and are readily deciphered. Other graph styles require close study to be interpreted. Ease of visual decoding of information contained in a graph – graph perception – varies from graph style to graph style. Historical instances of graphing paleozoological data indicate some difficult to decipher graph styles have been used for at least a century. Graphs with three-dimensions, moiré effects, superimposed lines, or segmented bars, or which demand simultaneous decipherment of position and magnitude, are ill-advised. Temporal trends in data are best graphed following the principle of superposition such that data from old material is graphed at the bottom and data from younger material is graphed at the top of the diagram.