Bovine serum albumin and insulin-dependent diabetes mellitus; is cow's milk still a possible toxicological causative agent of diabetes?

The implication of bovine serum albumin (BSA) in cow's milk as a causative agent for the onset of insulin-dependent diabetes mellitus (IDDM) is a major topic of scientific debate not withstanding the medical and economic implications. A critical survey of the pertinent literature has revealed a number of controversies. For example, an important toxicological aspect of BSA is the presence of ABBOS, a peptide segment of the protein. However, the nature and effect of ABBOS on the death of insulin producing cells (beta-cells of the pancreas) is unclear and hence inconclusive. In addition, studies in diabetes-prone mice and rats appear to show that cow's milk does not alter the frequency of diabetes in these organisms. It is suggested that BSA may not be the cause of diabetes. Instead, IDDM is most likely the result of oxidative stress, due to high local levels of nitric oxide (NO*) and oxygen radicals (O2*-), on the beta-cells of the pancreas, which eventually leads to their destruction.

Cloning and expression of the VHDL receptor from fat body of the corn ear worm, Helicoverpa zea.

In Noctuids, storage proteins are taken up into fat body by receptor-mediated endocytosis. These include arylphorin and a second, structurally unrelated very high-density lipoprotein (VHDL). Previously, we have isolated a single storage protein receptor from the corn earworm, Helicoverpa zea, which binds both VHDL and arylphorin. The receptor protein is a basic, N-terminally blocked, approximately 80 kDa protein that is associated with fat body membranes. Microsequencing of proteolytic fragments of the isolated receptor protein revealed internal sequences that were used to clone the complete cDNA of the VHDL receptor by 3' and 5' RACE techniques. The receptor protein, when expressed in vitro via a suitable insect expression vector, reacted with antibodies against the native VHDL receptor and bound strongly to its ligand VHDL, thus confirming that the cloned cDNA represents indeed the previously purified VHDL receptor. The receptor protein and a second, similar protein also found associated with the fat body membrane show considerable homology to putative basic juvenile hormone suppressible proteins cloned previously from other Noctuid species. Sequence analysis revealed that the receptor is likely a peripheral membrane protein that may mediate the selective uptake of VHDL.

LongSAGE profiling of nine human embryonic stem cell lines.

To facilitate discovery of novel human embryonic stem cell (ESC) transcripts, we generated 2.5 million LongSAGE tags from 9 human ESC lines. Analysis of this data revealed that ESCs express proportionately more RNA binding proteins compared with terminally differentiated cells, and identified novel ESC transcripts, at least one of which may represent a marker of the pluripotent state.

Efficient isolation, purification, and characterization of the Helicoverpa zea VHDL receptor.

The study of fat body receptors (e.g., VHDL receptor) in Lepidoptera has been irksome due to the fact that isolation and purification of these proteins are difficult and resulted in extremely low yields. A rapid and efficient method is presented for the purification of Helicoverpa zea VHDL receptor by the use of VHDL-biotin ligand complexed to streptavidin coated magnetic beads. The technique can be easily applied to other ligands and allows for the purification of membrane proteins with higher yields compared to previously used methods involving immunopurification. Although the purified protein can be characterized by Western and non-radioactive ligand blots using enhanced chemiluminescence (ECL), a non-radioactive ligand blot method using VHDL-FITC is presented, which allows for the quick analysis of the receptor directly from the blot under standard UV light. Sufficient receptor protein has been derived for amino acid analysis, receptor-ligand and xenobiotic binding studies.