Molecular characterization and chromosomal localization of mouse Puralpha gene

Puralpha is a 39-kDa sequence-specific single-stranded DNA/RNA binding protein with the ability to modulate transcription of several genes containing the Pur element in their promoter region. Human and mouse Puralpha exhibit an extraordinary degree of conservation with only two changes at amino acid residues 49 and 306. A 15-kb genomic clone encompassing the mouse Puralpha gene was isolated by screening the mouse genomic library, using a PCR-amplified fragment from human Puralpha cDNA. Results from sequencing analysis confirmed the isolated genomic clone to be Puralpha and not the other members of the Pur family, including Purbeta. Characterization of the mouse Puralpha gene by restriction analysis/Southern blotting and sequencing revealed that the Puralpha gene contains only one intron within the 5' UTR and the open reading frame was intact. Using chromosomal markers, the Puralpha gene was mapped to chromosome 18 in mouse and rat.

New (sulfonyloxy)piperazinyldibenzazepines as potential atypical antipsychotics: chemistry and pharmacological evaluation

A series of 2- or 8-trifluoromethylsulfonyloxy (TfO) and 2- or 8-methylsulfonyloxy (MsO) 11-piperazinyldibenzodiazepines, -oxazepines, and -thiazepines were synthesized and evaluated in pharmacological models for their potential clozapine-like properties. In receptor binding assays, the 2-TfO analogues (18a, GMC2-83; 24, GMC3-06; and previously reported GMC1-169, 9a) of the dibenzazepines have profiles comparable to that of clozapine, acting on a variety of CNS receptors except they lack M1 receptor affinity. Introduction of 2-TfO to clozapine leads to compound 9e (GMC61-39) which has a similar binding profile as that of clozapine including having M1 receptor affinity. Interestingly, the MsO analogues, as well as the 8-TfO analogues, have no or weak dopaminergic and serotonergic affinities, but all 8-sulfonyloxy analogues do have M1 affinities. In behavioral studies performed to indicate the potential antipsychotic efficacy and the propensity to induce EPS, 2-TfO analogues blocked effectively the apomorphine-induced climbing in mice in a dose-dependent manner with ED50 values (mg/kg) of 2.1 sc for 9a, 1.3 po for 18a, 2.6 sc for 24, and 8.2 sc for 9e. On the other hand, they showed a clear dose separation with regard to their ED50 values (mg/kg) for indicating catalepsy in rats (>44 sc for 9a, 28 po for 18a, 30 sc for 24, and >50 sc for 9e, respectively), thus implicating a more favorable therapeutic ratio (K/A, ED50 climbing/ED50 catalepsy) in comparison with typical neuroleptics such as haloperidol and isoclozapine. Furthermore, compound 18a was also demonstrated to be an orally potent DA antagonist with an ED50 value of 0.7 mg/kg po in the ex vivo L-DOPA accumulation model. The present study contributes to the SAR of 11-piperazinyldibenzazepines, and the 2-TfO analogues of 11-piperazinyldibenzazepines are promising candidates as clozapine-like atypical antipsychotics with low propensity to induce EPS.

Synthesis and muscarinic receptor pharmacology of a series of 4,5,6,7-tetrahydroisothiazolo[4,5-c]pyridine bioisosteres of arecoline

A series of O- and ring-alkylated derivatives of 4,5,6,7-tetrahydroisothiazolo[4,5-c]pyridin-3-ol was synthesized via treatment of appropriately substituted 4-benzylamino-1,2,5,6-tetrahydropyridine-3-carboxamides with hydrogen sulfide and subsequent ring closure by oxidation with bromine. The muscarinic receptor affinity as well as estimated relative efficacy and subtype selectivity of this series of bicyclic arecoline bioisosteres were determined using rat brain membranes and a number of tritiated muscarinic receptor ligands. The effects at the five cloned human muscarinic receptor subtypes of a selected series of chiral analogues, with established absolute stereochemistry, were studied using receptor selection and amplification technology (R-SAT). The potency, relative efficacy, and receptor subtype selectivity of these compounds were related to the structure of the O-substituents and the position and stereochemical orientation of the piperidine ring methyl substituents.

Assaying for structural variation in the parvovirus capsid and its role in infection

The capsid of canine parvovirus (CPV) was assayed for susceptibility to proteases and for structural variation. The natural cleavage of VP2 to VP3 in CPV full (DNA containing) particles recovered from tissue culture occurred within the sequence Arg-Asn-Glu-Arg Ala-Thr. Trypsin, chymotrypsin, bromelain, and cathepsin B all cleaved >90% of the VP2 to VP3 in full but not in empty capsids and did not digest the capsid further. Digestion with proteinase K, Pronase, papain, or subtilisin cleaved the VP2 to VP3 and also cleaved at additional internal sites, causing particle disintegration and protein degradation. Several partial digestion products produced by proteinase K or subtilisin were approximately 31-32.5 kDa, indicating cleavage within loop 3 of the capsid protein as well as other sites. Protease treatment of capsids at pH 5.5 or 7.5 did not significantly alter their susceptibility to digestion. The isoelectric point of CPV empty capsids was pH 5.3, and full capsids were 0.3 pH more acidic, but after proteolysis of VP2 to VP3, the pI of the full capsids became the same as that of the empty capsids. Antibodies against various capsid protein sequences showed the amino termini of most VP2 molecules were on the outside of full but not empty particles, that the VP1-unique sequence was internal, and that the capsid could be disintegrated by heat or urea treatment to expose the internal sequences. Capsids added to cells were localized within the cell cytoplasm in vesicles that appeared to be lysosomes. Microinjected capsids remained primarily in the cytoplasm, although a small proportion was observed to be in the nucleus after 2 h. After CPV capsids labeled with [35S]methionine were bound to cells at 0 degrees C and the cells warmed, little cleavage of VP1 or VP2 was observed even after prolonged incubation. Inoculation of cells with virus in the presence of proteinase inhibitors did not significantly reduce the infection.