Quantitative immunohistochemistry by measuring cumulative signal strength using commercially available software photoshop and matlab.

Currently available techniques for performing quantitative immunohistochemistry (Q-IHC) rely upon pixel-counting algorithms and therefore cannot provide information as to the absolute amount of chromogen present. We describe a novel algorithm for true Q-IHC based on calculating the cumulative signal strength, or energy, of the digital file representing any portion of an image. This algorithm involves subtracting the energy of the digital file encoding the control image (i.e., not exposed to antibody) from that of the experimental image (i.e., antibody-treated). In this manner, the absolute amount of antibody-specific chromogen per pixel can be determined for any cellular region or structure. (J Histochem Cytochem 48:303-311, 2000)     

The molecular basis of truncated forms of apolipoprotein B in a kindred with compound heterozygous hypobetalipoproteinemia

Krul et al. (1) have identified two truncated species of apolipoprotein B-100 in a kindred with familial hypobetalipoproteinemia. Five family members were identified who produce either one or both of two truncated apolipoprotein B-100 proteins estimated to be 40% and 90% the amino-terminal end of apolipoprotein B-100. Low density lipoprotein with the apolipoprotein B-90 binds more strongly to the low density lipoprotein-receptor on cultured fibroblasts. In this present study, we have identified the DNA mutations leading to these truncated apolipoprotein B-100 variants in this kindred. Sequencing of amplified DNA from the proband revealed that deletions of one or two nucleotide bases produced frameshift mutations and generated premature stop codons in both cases. Apolipoprotein B-40 (Val1829----Cys-TERM) is the result of a dinucleotide (TG) deletion in exon 26 that generates a stop codon at position 1830 and produces a protein with a predicted molecular mass of 207.14 kDa. The other truncated apolipoprotein B Glu4034----Arg-Gln-Leu-Leu-Ala-Cys-TERM) is due to a single nucleotide (G) deletion in exon 29. This results in a protein with 4039 amino acids and a predicted molecular mass of 457.6 kDa that is now designated apolipoprotein B-89. Mechanisms by which the removal of the last 497 amino acids might increase the binding of the apoB-89 to the LDL-receptor are discussed.