Application of carbon nanotubes for detecting anti-hemagglutinins based on antigen-antibody interaction.

Carbon nanotube sensors detected anti-hemagglutinin binding to immobilized hemagglutinins. An ultra-sensitive detection method for antibodies or antigens in serum is required. Hemagglutinins were immobilized on the reverse side of a carbon nanotube, thereby producing a source and a drain. Electrode pads covered each edge of the nanotube. The I-V curves between the source and the drain were measured after incubation of anti-hemagglutinins with immobilized hemagglutinins in a buffered solution on the reverse side of the nanotube. The sensitivity of the CNT sensor was higher than that of an ELISA system. This method constitutes a new tool to analyze interaction among biomolecules on a substrate.

Probucol decreases mevalonate pyrophosphate decarboxylase in the rat liver.

It is known that cholesterol biosynthesis in the liver is inhibited by probucol. This inhibition by probucol is caused at least in part by a decrease in 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase activity. In this study, we examined serum cholesterol and the change in the activity or protein level of mevalonate pyrophosphate decarboxylase (MPD), which is involved in cholesterol biosynthesis, in the livers of rats fed probucol. The results indicated that serum cholesterol, MPD activity and MPD protein were decreased by 70, 50 and 60% by probucol, respectively, as compared with those in rats fed normal chow. These data show for the first time that probucol decreases the level of an enzyme involved in cholesterol biosynthesis other than HMG-CoA reductase.

Peroxisome proliferative drugs do not induce an increase of rat mevalonate pyrophosphate decarboxylase.

To determine whether or not the expression of mevalonate pyrophosphate decarboxylase (MPD) depends on the proliferation of peroxisomes, we examined change in the protein level of MPD in the crude extract, the cytosol and the peroxisome-enriched fraction of the livers of rats administered peroxisome proliferative drugs. No increase of MPD was observed in any of these fractions. These data suggest that the expression of MPD is independent of the proliferation of peroxisomes and may be maintained via a specific regulatory mechanism different from that of the expression of peroxisome proliferator-activated receptor alpha.

Comparison of subcellular distribution of mevalonate pyrophosphate decarboxylase between stroke-prone spontaneously hypertensive rat and Wistar Kyoto rat.

We previously reported that the lower activity of mevalonate pyrophosphate decarboxylase (MPD) was caused by the reduced amount of this enzyme in stroke-prone spontaneously hypertensive rat (SHRSP) by immunoblot analysis using 20,000 x g supernatant containing cytosol and microsomes. A recent study showed that at least three different subcellular compartments, including peroxisomes, are involved in cholesterol synthesis. In this study, we examined the subcellular distribution of 45- and 37-kDa MPD in the liver of SHRSP and compared normotensive Wistar Kyoto rat (WKY) and SHRSP. 45-kDa MPD was detected in the cytosol and peroxisomes of SHRSP, while 37-kDa MPD was detected in the cytosol of SHRSP, but not in the peroxisomes. The relative enrichment of 45-kDa MPD in peroxisomes was lower than that of LDH, suggesting the possibility that 45-kDa MPD of SHRSP did not exist in the peroxisomes. Also, 45-kDa MPD was decreased in the crude extract containing 1% Triton X-100, cytosol and peroxisomes of SHRSP, and 37-kDa MPD was decreased in the crude extract containing 1% Triton X-100 and cytosol of SHRSP, as compared with WKY. These data indicate that the cholesterol synthesis in the liver of SHRSP by the reduced amount of MPD is significantly reduced.