Biomedical subjects

Noriko Okada

Publications and source records attributed to Noriko Okada.

44 records · Page 3Linked to original sources

PubMed2002

Inactivation of C3a and C5a octapeptides by carboxypeptidase R and carboxypeptidase N.

Pro-carboxypeptidase R (proCPR), also known as thrombin-activatable fibrinolysis inhibitor (TAFI), precursor of carboxypeptidase U and plasma carboxypeptidase B is present in plasma and following activation by thrombin/thrombomodulin and/or plasmin can remove arginine from the carboxyterminal of C3a and C5a. We have shown that this enzyme can remove terminal arginine from the C5a octapeptide much more efficiently than the classical anaphylatoxin inactivator, carboxypeptidase N (CPN). Since we have previously demonstrated that proCPR is significantly upregulated in the inflammatory state, this enzyme would appear to significantly contribute to the inactivation of C5a, the most potent of the complement derived anaphylatoxins.

Carboxypeptidase B2↗

PubMed2002

A novel genetic algorithm for designing mimetic peptides that interfere with the function of a target molecule.

We designed a new computer program (MIMETIC), which generates a series of peptides for interaction with a target peptide sequence. The genetic algorithm employed ranks the sequences obtained from one generation to the next by "goodness of fit" to the target. MIMETIC designed recognition peptides to various regions of HIV-1 reverse transcriptase. Among ten peptide candidates synthesized, three inhibited reverse transcription in vitro. TLMA2993 and PSTW1594 both targeted the connection domain of reverse transcriptase and ESLA2340 targeted the thumb domain.

Algorithms↗

PubMed2002

Heat stability of carboxypeptidase R of experimental animals.

Carboxypeptidase N (CPN) and carboxypeptidase R (CPR) are present in fresh serum, and cleave C-terminal arginine or lysine residues from bioactive peptides such as anaphylatoxins and kinins resulting in regulation of peptide activity. Although CPN is present in the active form in plasma, CPR is generated from proCPR by trypsin-like enzymes such as thrombin. CPR regulates not only inflammatory peptides but also restricts fibrinolysis. To elucidate the complex role of CPN and CPR in vivo, studies in animal models will be essential. CPR of guinea pig, rat and rabbit decayed at 37 C rapidly as in the case of human CPR. However, at 25 C, CPR of those species decayed to some extent, although human serum CPR did not decay within 60 min. In the presence of thrombin inhibitor, CPR in the sera of animals tested decayed more rapidly than CPR in serum without thrombin inhibitor suggesting that additional generation of CPR may have been prevented during decay evaluation. However, human serum CPR decayed more rapidly in the absence of thrombin inhibitor indicating that thrombin may accelerate the decay in human serum.

Animals↗

PubMed2002

Elastase from activated human neutrophils activates procarboxypeptidase R.

Carboxypeptidase R (EC 3.4.17.20; CPR) is an unstable basic carboxypeptidase found in fresh serum in addition to carboxypeptidase N (CPN) which is a stable enzyme. CPR in fresh serum is generated from its zymogen (proCPR) during coagulation by trypsin-like enzymes such as thrombin and thrombin/thrombomodulin complexes. Since removal of the C-terminal arginine abrogates the anaphylatoxin activity of C3a and C5a, CPR and CPN are regarded as anaphylatoxin inactivators. We report here that the culture supernatant of activated human neutrophils converts proCPR to CPR. Addition of an elastase specific inhibitor, N-methoxysuccinyl-Ala-Ala-Pro-Val-chloromethyl ketone (MSAAPVCK) to the supernatant of stimulated neutrophils completely inhibited activation of proCPR. On the other hand, a thrombin specific inhibitor, p-Nitrophenyl-p'-amidinophenyl-methanesulfonate hydrochloride (pNP-pAPMS) inhibited only 16% of proCPR activation by the neutrophil supernatant. Furthermore, purified elastase converted proCPR to CPR. Therefore, elastase can activate proCPR directly, or indirectly through activation of some proteases, which have been contaminating in reagents. Release of CPR generating enzymes from neutrophils should play an important role in regulation of excess inflammation.

Amino Acid Chloromethyl Ketones↗

PubMed2002

Double-stranded nef RNA interferes with human immunodeficiency virus type 1 replication.

RNA interference (RNAi) has been reported to be post-transcriptional gene silencing (PTGS) by approximately 500 nucleotide-(nt)-long double-stranded (ds) RNA that specifically targets homologous sequences of messenger RNA. In this report, we describe inhibition of HIV-1 transcription by synthetic dsRNAs constructed with mutated nef genes (nef dsRNAs) derived from long-term non-progressors (LTNPs) using cotransfection of the target gene-expressing plasmid and dsRNA. The effects of nef dsRNAs were examined with luciferase (Luc) reporter which is combined with the HIV-1 (SF2) LTR in persistently HIV-1-infected T cell and macrophage cell lines. At 48 hr, a defective nef dsRNA (556 nt) suppressed Luc activity more potently than did SF2 full-length nef dsRNA (744 nt), suggesting that approximately 500 nt-long nef dsRNA could interfere with the HIV-1 transcription.

Gene Products, nef↗

PubMed2002

Distribution of rat C5a anaphylatoxin receptor.

The anaphylatoxin, complement 5a (C5a), plays a key role in mediating various inflammatory reactions following complement activation. Several investigators have reported that C5a receptor (C5aR) is expressed in non-myeloid cells under certain conditions or in different cell lines. In our study, the abundance of C5aR-positive myeloid cells in rats depended on the organs examined. C5aR was usually expressed at the site of exposure to pathogens, such as in salivary gland or lung, and was up-regulated in liver in the inflammatory state induced by lipopolysaccharide (LPS) administration. Furthermore, the increased expression of C5aR antigen was not accompanied by an increase in C5aR mRNA in Kupffer cells following LPS challenge.

Animals↗

PubMed2002

Soluble complement receptor type 1 protects rats from lethal shock induced by anti-Crry antibody following lipopolysaccharide priming.

BACKGROUND: In rats primed with a trace amount of lipopolysaccharide (LPS), acute lethal shock is induced following the injection of monoclonal antibody against a membrane inhibitor of complement (anti-Crry). Administration of cobra venom factor to exhaust complement before the LPS priming can prevent the lethal reaction. Therefore, we evaluated whether soluble complement receptor type 1 (sCR1), which inhibits complement reaction, can interfere with lethal shock when administered after LPS priming or even after anti-Crry injection. METHODS: sCR1 was administered intravenously before or after the administration of anti-Crry, and the effects on blood pressure and acute lethality were determined. RESULTS: Administration of sCR1 could rescue rats from lethal shock even when it was administered after anti-Crry injection, which immediately causes a blood pressure decrease leading to lethal shock. CONCLUSION: sCR1 may be an effective treatment for acute shock involving complement activation.

Animals↗

PubMed2002

[Human monoclonal antibodies to HIV-1 infection].

HIV-1, which causes AIDS, has infected over 50 million and killed over 20 million individuals world wide since the beginning of the epidemic two decades ago. The introduction of highly active anti-retroviral therapy(HAART) has resulted in the control of the disease progression. Furthermore, supervised treatment interruption(STI) of HAART might be expected significantly to boost immune function and slow the progression of AIDS. On the other hand, several combinations of human monoclonal antibodies(hu-mo-Ab) against HIV-1 has been identified, and demonstrates the efficacy of the triple combination of hu-mo-Ab with neutralizing activity in macaque model. Therefore, a combination of chemotherapy and immunotherapy, such as hu-mo-Ab will be prove to be the most effective route for HIV-1 therapy.

Animals↗