Synthesis and biological evaluation of novel pyrazoles and indazoles as activators of the nitric oxide receptor, soluble guanylate cyclase.

Database searching and compound screening identified 1-benzyl-3-(3-dimethylaminopropyloxy)indazole (benzydamine, 3) as a potent activator of the nitric oxide receptor, soluble guanylate cyclase. A comprehensive structure-activity relationship study surrounding 3 clearly showed that the indazole C-3 dimethylaminopropyloxy substituent was critical for enzyme activity. However replacement of the indazole ring of 3 by appropriately substituted pyrazoles maintained enzyme activity. Compounds were evaluated for inhibition of platelet aggregation and showed a general lipophilicity requirement. Aryl-substituted pyrazoles 32, 34, and 43 demonstrated potent activation of soluble guanylate cyclase and potent inhibition of platelet aggregation. Pharmacokinetic studies in rats showed that compound 32 exhibits modest oral bioavailability (12%). Furthermore 32 has an excellent selectivity profile notably showing no significant inhibition of phosphodiesterases or nitric oxide synthases.

Neuronal and inducible nitric oxide synthase and nitrotyrosine immunoreactivities in the cerebral cortex of the aging rat.

Neuronal and inducible nitric oxide synthase (nNOS and iNOS) and nitrotyrosine immunoreactivities were localized and semiquantitatively assessed in the cerebral cortex of aged rats by means of light microscopic immunocytochemistry and Western blotting, using a new series of specific polyclonal antibodies. In the aged rats the strongly nNOS-immunoreactive multipolar neurons found in layers II-VI of the cortex of young rats were seen in similar numbers, but showed varicose, vacuolated, and fragmented processes, with an irregular outline and loss of spines. A large number of more weakly nNOS-positive neurons, characterized by a ring of immunoreactive cytoplasm, and not seen in young rats, were observed in layers II-VI of aged rat cortex. While no iNOS-immunopositive neurons were found in the cortex of young rats, a large number of such neurons appeared throughout the aged rat cortex. Nitrotyrosine-positive cells outnumbered total NOS-positive neurons in the cortex of young rats, but this relation was inverted in the aged rats, although these showed a slight increase in the number and staining intensity of nitrotyrosine-positive cells. Western blots of brain extracts showed a several-fold increase in both nNOS- and iNOS-immunoreactive bands in the aged rat, but a less marked increase in nitrotyrosine-containing proteins. The results suggest that while nNOS and iNOS expression is substantially increased in the aged rat cortex, this is not necessarily accompanied by a proportionate increase in nitric oxide synthesis. The mechanisms underlying the increased expression of nNOS and iNOS, and the functional implications of this increase, require elucidation.

Specific cleavage of histidine-containing peptides by copper(II).

Copper(II) cleaves with moderate specificity peptides containing Ser-His or Thr-His sequences, at the N-terminal side of the hydroxyaminoacyl residue. The reaction is slow, and is first-order in peptide: CuII complex, with a half-life of several hours at 62 degrees C in sodium bicarbonate buffer, pH 8. Cleavage of other histidine-containing peptides also occurs, at a rate around 10-100-fold less. EDTA completely quenches the cleavage. The reaction is stoichiometric in CuII and is inhibited by amine-containing buffer components; Tris at 19 mM inhibits cleavage by 50%. The reaction has a complex pH-dependence, being very slow below pH 5, and with rates increasing with pH from pH 7 to pH 9.5. Slower degradative side reactions do occur, with destruction of tyrosine residues, particularly in the presence of high concentrations of chloride ion, but the specific cleavage appears to be a hydrolysis, as determined by amino-acid analysis and mass spectrometry of the products. The cleavage is clearly different from the previously described oxidative degradation of proteins catalysed by copper ions. Cleavage of denatured IgG protein occurs with sufficient specificity to reveal distinct bands on SDS-polyacrylamide gel electrophoresis under reducing conditions.

Monoclonal antibodies to a peptide of human rhinovirus type 2 with different specificities recognize the same minimum sequence.

Monoclonal antibodies (MAbs) raised against a synthetic peptide including residues 156-170 of protein VP2 of human rhinovirus type 2 (HRV2) have previously been shown to be of differing specificities. The basis for these differences has now been examined in greater detail by ELISA, radioimmunoprecipitation and virus neutralization. Reactions with a panel of HRV2 mutant viruses indicated that substitution of some residues could enhance the apparent activity of one of the neutralizing anti-peptide MAbs. For one such substitution, VP2 P164H, there appeared to be a correlation between increased neutralizing activity and enhanced binding. Mapping experiments identified two overlapping neutralization epitopes (amino acids 156-163 and 160-165) and several non-neutralizing epitopes. Although some differences in antibody reactivity were due to epitope specificity alone, the explanation for others was less obvious. Significantly, the majority of MAbs that recognized, and in some cases neutralized, native virus had the same minimum binding sequence and critical residue requirement as others which recognized virus particles only after distortion. This demonstrates that factors other than the linear sequence of the peptide can be crucial in determining the fine specificity, and hence biological relevance, of peptide antigens.

The nucleotide sequence of the structural-protein-coding region of foot-and-mouth disease virus serotype SAT3.

The nucleotide sequence coding for the structural proteins and nonstructural protein P2A has been determined for a foot-and-mouth disease virus (FMDV) isolated in Africa. This virus, serotypically designated SAT3 (South African Territories type 3), shows about 60% homology at the nucleotide level to prototype viruses from the O, A and C serotypes of FMDV. The highest region of variability was shown in structural protein VP1, presumably a consequence of its position on the surface of the virus and its exposure to selection pressure by neutralising antibody. Within this region amino acids (aa) 141-160, which have been shown to represent an immunodominant region in other FMDV serotypes, showed hypervariability as well as the insertion of 5 or 9 additional aa relative to the O1 and C1 serotypes, respectively. In contrast, the sequence of nonstructural protein P2A was completely conserved indicating a probable important role in virus replication.

Host cell selection of antigenic variants of foot-and-mouth disease virus.

Foot-and-mouth disease virus (FMDV) A22 Iraq 24/64 adapted to grow in BHK monolayer cells induced antibodies which neutralized many isolates belonging to the A serotype. Plaque-purified virus isolated from this stock also induced broadly reactive antibodies, showing that this property is not due to the combined response to a mixture of variants in the original stock virus. However, viruses obtained by passage in suspension BHK cells of either the monolayer cell-adapted virus or a virus cloned from this stock resulted in the selection of virus which induced antibodies with highly specific neutralizing activity. In addition to their antigenic properties the monolayer and suspension cell-adapted viruses could be distinguished by plaque morphology, tendency to aggregate and ability to attach to BHK cells. Monoclonal antibodies (MAbs) induced with the plaque-purified monolayer-adapted virus had neutralizing activity almost as broad as polyclonal serum, showing that this property can be represented by a single epitope on the virus. These neutralizing MAbs recognize a trypsin-sensitive epitope on the virus. Surprisingly, sequence analysis of the structural protein-coding regions of the genomic RNAs of monolayer and suspension cell-adapted viruses showed no amino acid differences in VP1, the protein known to contain the major neutralization epitope in FMDV and to be the only protein susceptible to cleavage by trypsin in the virus particle. Although three coding differences were found in the capsid protein these were all located in VP2.

The sequence of foot-and-mouth disease virus RNA to the 5' side of the poly(C) tract.

The nucleotide sequence of foot-and-mouth disease virus (FMDV) RNA to the 5' side of the poly(C) tract (S fragment) has been determined for representatives of the A and O serotypes of the virus. The two S fragments differ in length by five nucleotides (nt), with 367 nt for O1 compared with 362 nt for A10, due to a number of insertions/deletions. However, the two sequences show 86% homology. There are no conserved open reading frames (ORFs). Secondary structure predictions reveal a high degree of potential base-pairing, such that the entire S fragment sequence can be folded into a hairpin structure.

Tuberculous pseudotumour of the liver developing during antituberculous chemotherapy.

A 29-year-old Chinese woman presented with a liver mass 2 months after initiation of chemotherapy for disseminated tuberculosis. A percutaneous liver biopsy revealed tuberculous pseudotumour. Although acid-fast bacilli were seen in the biopsy specimen, no organism could be cultured. No changes were made in the antituberculous chemotherapy, and the mass subsequently resolved. The patient was still well 18 months after presentation. To the authors' knowledge, the features of tuberculous pseudotumour seen with ultrasonography and computerized tomography have not previously been described, nor has this condition previously been reported in patients already receiving antituberculous chemotherapy.