Effect of increasing dietary vitamin A on bone density in adult dogs.

There has been an increase in vitamin A fortification of livestock feeds resulting in increased residual vitamin A in organ meats, which are often used in canned dog foods. The effect on bone density of feeding various concentrations of vitamin A in a canned dog food product was investigated. Thirty-two random-source dogs were assigned to four treatments in a randomized complete block design. The diets contained 15,000, 50,000, 116,000, or 225,000 IU vitamin A/1,000 kcal ME. Diets were fed up to 1 yr. Computed tomography was used to determine bone density of the right tibia at 0, 3, 6, 9, and 12 mo. Computed tomography is a more sensitive technique for determining bone density in vivo than conventional x-rays. There were no differences (P > .10) in tibia bone or marrow density in any of the dogs fed the various concentrations of vitamin A. There was no interaction of time x diet on bone density (P > .05) or bone marrow density (P > .05). In addition, there were no changes in serum alkaline phosphatase, calcium, or phosphorus. These results indicate that concentrations of vitamin A three times the recommended maximum safe amount (71,429 IU/1,000 kcal ME) are not detrimental to normal bone health in dogs. Therefore, these data support the hypothesis that canines are less sensitive to excess vitamin A in the diet than some other mammals.

Large monocytoid cell in mononuclear cell fraction of bovine blood.

Sodium metrizoate-ficoll separation of bovine mononuclear cells from peripheral blood yielded a granulocyte-free leukocyte population with an average recovery of 76%. A high proportion of the separated cells were of large size and monocytoid in appearance. This cell type was observed in a much smaller percentage in mononuclear preparations separated from defibrinated blood.

Proliferation of human lymphocytes in culutre: determination by measurement of nuclear volume and cell number.

Proliferation of stimulated human lymphocytes was studied in cultures by determining cell counts and nuclear volume enlargement. DNA content and the nuclear volume increase before the cell divides. Volume-frequency curves were obtained of unstimulated and phytohemagglutinin (PHA) stimulated lymphocytes on 0, 3, 6 and 9 days of cultures with the Coulter Counter H4 system. As the number of lymphocytes in the cultures transformed and enlarged in volume, the area under the volume-frequency curve increased proportionately. The fraction of transforming cells was determined by comparing the area under the curve of the unstimulated and the stimulated lymphocytes. This method provides both the fraction of cells transformed and the increment of the number of cells in the culture and is therefore a better indicator of cell proliferation than the commonly used isotope-labeled thymidine uptake method which monitors the fraction of the cells in DNA synthesis phase only.

Proliferation of human lymphocytes in culture : determination by measurement of nuclear volume and cell number.

Proliferation of stimulated human lymphocytes was studied in cultures by determining cell counts and nuclear volume enlargement. DNA content and the nuclear volume increase before the cell divides. Volume-frequency curves were obtained of unstimulated and phytohemagglutinin (PHA) stimulated lymphocytes on 0, 3, 6 and 9 days of cultures with the Coulter Counter H4 system. As the number of lymphocytes in the cultures transformed and enlarged in volume, the area under the volume-frequency curve increased proportionately. The fraction of transforming cells was determined by comparing the area under the curve of the unstimulated and the stimulated lymphocytes. This method provides both the fraction of cells transformed and the increment of the number of cells in the culture and is therefore a better indicator of cell proliferation than the commonly used isotope-labeled thymidine uptake method which monitors the fraction of the cells in DNA synthesis phase only.

Studies on lymphocytes XIII. Nuclear volume measurement as a rapid approach to estimate proliferative fraction.

A rapid method for measuring volume distributions of human, calf and goat lymphocytes and their nuclei is described along with the type of quantitation these measurements can provide by computer analysis. The size distribution studies indicate the presence of two populations of lymphocytes and their nuclei irrespective of the cell source. It is suggested that proliferative fractions of various cell populations may be estimated by determining the nuclear volume distribution.

Endothelial localization of receptor tyrosine phosphatase, ECRTP/DEP-1, in developing and mature renal vasculature.

Developmental assembly of the renal microvasculature requires spatially and temporally coordinated migration, assembly, differentiation, and maturation of endothelial cells in the context of adjacent epithelial and mesangial cells. In this study, endothelial expression and distribution of the receptor tyrosine phosphatase ECRTP/DEP-1 were evaluated during and after developmental assembly of the renal microvasculature. Monoclonal antibodies against ECRTP/DEP-1 ectodomain epitopes localize its expression to membrane surfaces of endothelial cells in glomerular, peritubular capillary, and arterial renal sites of mature human and murine kidney. During kidney development, ECRTP/DEP-1 immunostaining is evident on a subpopulation of metanephric mesenchymal cells and on putative progenitors of glomerular capillary endothelial cells early in their recruitment to developing glomeruli. ECRTP/DEP-1 is prominently displayed on luminal membrane surfaces with punctate accumulations at inter-endothelial contacts that overlap with vascular endothelial-cadherin staining. ECRTP/DEP-1 is recruited to inter-endothelial contacts in confluent cultured human renal and dermal microvascular endothelial cells, yet experimental dissociation of vascular endothelial-cadherin from endothelial junctional complexes fails to redistribute ECRTP/DEP-1. These findings indicate that ECRTP/DEP-1 is expressed in anticipation of glomerular capillary endothelial recruitment during development, and suggest that ECRTP/DEP-1 ectodomain interacts with endothelial surface ligands that are engaged by cell-cell contact.

Analysis of association at single nucleotide polymorphisms in the APOE region.

The discussion of the prospects of using a dense map of single nucleotide polymorphisms (SNPs) to identify disease genes with association analysis has been extensive. However, there is little empiric evidence to support this strategy. To begin to examine the practical issues surrounding this methodology, we identified 10 SNPs in the region immediately surrounding the apolipoprotein E locus (APOE), an established susceptibility gene for Alzheimer disease. Our goal was to examine patterns of allelic association to begin to investigate the question of whether APOE could have been identified using SNPs. Our strongest evidence of association was at the 2 SNPs immediately flanking APOE.