Shinichi Kamachi

Quantitative enzyme immunoassay for human granulocyte colony stimulating factor (G-CSF)

Human granulocyte colony stimulating factor (G-CSF) was detected at the pM level by a simple sequential sandwich enzyme immunoassay. The polyclonal antiserum obtained by immunizing rabbits with recombinant G-CSF did not recognize other colony stimulating factors. The EIA developed gave satisfactory reproducibility as judged by an intra-assay precision of 4.3-6.2% and an interassay precision of 6.2-9.0%. Results from this assay procedure correlated well with those of a bioassay. The method could be performed within 6 h.

Radioimmunoassay for erythropoietin using anti-recombinant erythropoietin antibody with high affinity.

A sensitive radioimmunoassay (RIA) for the detection of erythropoietin (EPO) was developed using anti-recombinant EPO antibody with high affinity. The sensitivity was 100 amol/tube (5 mIU/ml) and it was possible to detect a serum EPO level between 5 and 200 mIU/ml. This method enabled us to measure native EPO as well as recombinant EPO. With this method we determined serum EPO levels in healthy individuals and patients with chronic renal disease, rheumatoid arthritis and iron deficiency anemia. Values in patients with chronic renal disease were lower than those in healthy individuals, while values in patients with rheumatoid arthritis, or iron deficiency anemia were significantly higher than those in healthy individuals.

Vascular levels and cGMP-increasing effects of nicorandil administered orally to rats

We examined a relation between cyclic guanosine monophosphate (cGMP) production in thoracic aorta, as an indicator probably reflecting the vascular response, and the vascular as well as plasma levels of nicorandil administered orally to rats. Nicorandil (3 mg/kg) given orally was rapidly absorbed, reaching the maximal plasma (approximately 2,600 ng/ml) and vascular concentrations (approximately 176 ng/g) at 15 min after the dosing and thereafter decreased rapidly. Even 2 h after the dosing, the level of the vascular cGMP formation in vivo remained significantly higher (approximately 1,000 fmol/mg increase from the control level) in the nicorandil-treated group, compared with the vehicle-treated one, and was enough to develop pronounced muscle relaxation in in vitro aortic preparations. However, it seems that the vascular cGMP increase in vivo was not always correlated to the plasma concentration of nicorandil, because the plasma concentration (approximately 750 ng/ml corresponding to 3.5 microM) at 2 h after the dosing, caused only relatively low cGMP production (300-400 fmol/mg increase from the control level), when tested in in vitro aortic preparations. Our study may indicate, therefore, that the vascular cGMP elevation in vivo is due to the content of nicorandil effectively remaining at its vascular targets of action as well as the plasma nicorandil concentration.

Interrelationship of cardiovascular effects, plasma levels of nicorandil, and vascular cGMP formation in conscious rats.

The relationship between the dual activity of nicorandil (KATP channel‐opening activity and nitrate‐like action), plasma levels, and changes in vascular cGMP levels and cardiovascular parameters was investigated in conscious rats.

Orange-I laurate, a new chromogenic substrate for the assay of lipase in blood

Abstract Eight long-chain fatty acid esters (laurates, myristates, palmitates and stearates) of sodium m - or p -(4-hydroxy-1-naphthylazo)-benzenesulfonate were synthesized and assessed as chromogenic substrates for the assay of lipase. All are hydrolyzed in the presence of lipase, the laurates most rapidly. Orange-I laurate (the p -compound) was selected for detailed study. A very selective assay of lipasein the presence of other esterases was achieved by adding sodium dodecylbenzenesulfate and protamine sulfate as inhibitors. Orange-I laurate could be used as a substrate for lipase in serum.