Abstract: A hybridoma producing a monoclonal antibody recognizing the C-terminus of human brain natriuretic peptide (hBNP) was cultivated in a medium or the abdominal cavity of a mouse to recover the monoclonal antibody from the medium or ascites accumulated in the abdominal cavity. An immunoassay for hBNP was established using the monoclonal antibody. The immunoassay for hBNP of the invention is so sensitive that the minimum detection limit is 1 pg/ml and can therefore determine the hBNP level in blood plasma directly, without the extraction of hBNP from blood plasma. It is useful for diagnosing diseases such as hypertension and the like, and states of the heart, kidney, and the like by using the increase/decrease of the hBNP level as an index.

Abstract: A hybridoma producing a monoclonal antibody recognizing the C-terminus of human brain natriuretic peptide (hBNP) was cultivated in a medium or the abdominal cavity of a mouse to recover the monoclonal antibody from the medium or ascites accumulated in the abdominal cavity. An immunoassay for hBNP was established using the monoclonal antibody. The immunoassay for hBNP of the invention is so sensitive that the minimum detection limit is 1 pg/ml and can therefore determine the hBNP level in blood plasma directly, without the extraction of hBNP from blood plasma. It is useful for diagnosing diseases such as hypertension and the like, and states of the heart, kidney, and the like by using the increase/decrease of the hBNP level as an index.

Abstract: A hybridoma producing a monoclonal antibody recognizing the C-terminus of human brain natriuretic peptide (hBNP) was cultivated in a medium or the abdominal cavity of a mouse to recover the monoclonal antibody from the medium or ascites accumulated in the abdominal cavity. An immunoassay for hBNP was established using the monoclonal antibody. The immunoassay for hBNP of the invention is so sensitive that the minimum detection limit is 1 pg/ml and can therefore determine the hBNP level in blood plasma directly, without the extraction of hBNP from blood plasma. It is useful for diagnosing diseases such as hypertension and the like, and states of the heart, kidney, and the like by using the increase/decrease of the hBNP level as an index.

Abstract: The radioactive iodine compound of this invention or an intermediate for preparing the compound is represented by the following formula (I): ##STR1## wherein R is H or .sup.125 I. The radioactive compound can readily introduce a radioactive isotope element such as .sup.125 I into an antibody molecule without damaging the activity of the antibody molecule. Therefore, the compound can preferably be used to label an antibody of immunoradiometric assay, and allow a higher degree of measurement sensitivity.

Abstract: The disclosed peptide derivative of the formula:Y--Tyr--Gly--RWherein, Y represents a hydrogen atom or an amino protecting group, Tyr represents a tyrosine residue wherein at least one of the hydrogen atoms on the phenyl ring may be substituted by a radioactive iodine, Gly represents a glycine residue, and R represents a peptide residue corresponding to an amino acid sequence which includes at least positions 7 through 21 of human proinsulin C-peptide proves to be useful for determining C-peptide level in human serum.

Abstract: A polypeptide of the formula:X.sub.1 --Tyr--Ser--X.sub.2 --X.sub.3 --His--Phe--Arg--Trp--Gly--Lys--Pro--Val--Gly--(Lys).sub.n --Ywherein X.sub.1 is .alpha.-aminoisobutyric acid, .beta.-alanine, L-serine, D-serine, glycine, D-alanine, .gamma.-aminobutyric acid or sarcosine residue; X.sub.2 is L-methionine, L-norleucine, L-isoleucine or L-norvaline residue; X.sub.3 is L-glutamic acid or L-glutamine residue; n is an integer of 5-10; and Y is --R.sub.1, ##STR1## wherein R.sub.1 is hydroxy or lower alkoxy having 1-5 carbon atoms; R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each hydrogen or lower alkyl having 1-5 carbon atoms; m is an integer of 1-10 and Y is a group bound to the carbonyl group of the C-terminal lysine residue; non-toxic acid addition salts thereof; and complexes thereof; being useful as a medicament owing to their strong adrenal-stimulating activity with protracted action and little side effects.

Abstract: A polypeptide of the formula:X.sub.1 -Tyr-Ser-X.sub.2 -X.sub.3 -His-Phe-Arg-Trp-Gly-Lys-Pro-Val-Gly-(Lys).sub.n -Ywherein X.sub.1 is .alpha.-aminoisobutyric acid, .beta.-alanine, L-serine, glycine, D-serine, D-alanine, .gamma.-aminobutyric acid or sarcosine residue; X.sub.2 is L-methionine, L-norleucine, L-isoleucine or L-norvaline residue; X.sub.3 is L-glutamic acid or L-glutamine residue; n is an integer of 1-4 and Y is a group of ##STR1## which is linked to the carbonyl group of the C-terminal lysine residue, wherein R.sub.1 and R.sub.2 are each hydrogen or the same or different lower alkyl having 1-5 carbon atoms, and R.sub.1 and R.sub.2, when taken together with or without another hetero atom, form a substituted or unsubstituted nitrogen containing heterocyclic ring, with the proviso that a peptide when X.sub.1 is a .alpha.-aminoisobutyric acid or D-serine, R.sub.1 and R.sub.