Development of intramolecularly quenched fluorescent peptides as substrates of angiotensin-converting enzyme 2

Angiotensin-converting enzyme 2 (ACE2 or ACEH) is a novel angiotensin-converting enzyme-related carboxypeptidase that cleaves a single amino acid from angiotensin I, des-Arg bradykinin, and many other bioactive peptides. Using des-Arg bradykinin as a template, we designed a series of intramolecularly quenched fluorogenic peptide substrates for ACE2. The general structure of the substrates was F-X-Q, in which F was the fluorescent group, Abz, Q was the quenching group (either Phe(NO(2)) or Tyr(NO(2))), and X was the intervening peptide. These substrates were selectively cleaved by recombinant human ACE2, as shown by MS and HPLC. Quenching efficiency increased as the peptide sequence was shortened from 8 to 3 aa, and also when Tyr(NO(2)) was used as a quenching group instead of Phe(NO(2)). Two of the optimized substrates, TBC5180 and TBC5182, produced a signal:noise ratio of better than 20 when hydrolyzed by ACE2. Kinetic measurements with ACE2 were as follows: TBC5180, K(m)=58 microM and k(cat)/K(m)=1.3x10(5)M(-1)s(-1); TBC5182, K(m)=23 microM and k(cat)/K(m)=3.5 x 10(4)M(-1)s(-1). Thus, based on hydrolysis rate, TBC5180 was a better substrate than TBC5182. However, TBC5180 was also hydrolyzed by ACE, whereas TBC5182 was not cleaved, suggesting that TBC5182 was a selective for ACE2. We conclude that these two peptides can be used as fluorescent substrates for high-throughput screening for selective inhibitors of ACE2 enzyme.     

Dysregulated expression of MIC-1/PDF in human prostate tumor cells

As a part of the study to identify genes associated with hormone-refractory stage of human prostate cancer, we have recently identified several genetic and epigenetic changes that seem to be associated with the progression of androgen-sensitive to androgen-independent prostate tumor cells. In the present study, we report a novel gene, macrophage inhibitory cytokine-1 (MIC-1) also known as prostate derived factor (PDF), that was highly expressed in androgen-independent LNCaP-C81 cells and its metastatic variant LNCaP-Ln3 compared to androgen-sensitive LNCaP-C33 cells. The MIC-1/PDF expression was dysregulated (very low to non-detectable) in the androgen-independent PC3 and DU145 cells. Interestingly, serum factors demonstrated a differential regulation of MIC-1/PDF in the androgen-sensitive and the androgen-independent cells of LNCaP cells. Immunohistochemical analysis on 15 prostatic adenocarcinomas showed a weak staining in the benign prostatic glandular area (intensity score 2.38+/-0.25; n=13), while the immunoreactivity was significantly stronger (p<0.05) in areas of adenocarcinoma (score 7.33+/-0.88; n=15). Altogether, these data suggest that the serum factors (including androgens and cytokines) might contribute to the regulation of the MIC-1/PDF gene that seems to be associated with the progression of prostate cancer.     

Novel drug designing approach for dual inhibitors as anti-inflammatory agents: implication of pyridine template

Compounds incorporating thiophene moiety, a pi excess five membered heterocycle, have attracted a great deal of research interest, owing to the therapeutic utility of the template as useful drug molecular scaffolding. We report the synthesis and pharmacological evaluation of thiophenes substituted with 4-methanesulfonyl benzoyl moiety at the fifth position of the ring, as possible anti-inflammatory lead candidates. The aryl sulfonyl methyl thiophene analogs AP29, AP82, and AP37, when screened for anti-inflammatory activity in carrageenin induced rat paw edema, an acute in vivo model, exhibited moderate to good activity at a dose level of 100 mg/kg body weight P.o compared to Ibuprofen. In a five day formalin induced rat paw edema, a chronic in vivo anti-inflammatory model, candidates AP29, AP82, and AP37 inhibited the disease progression by 53%, 34%, and 65%, respectively on the fifth day, at a dose level of 100 mg/kg body weight P.o compared to Rofecoxib, Ibuprofen, and Dexamethasone at therapeutic doses which gave a protection of 53.8%, 81.5%, and 81.5%, respectively. The replacement of the 4-methanesulfonyl benzoyl moiety in AP82 with the pyridine template, 3,5-dimethyl-4-methoxy-2-pyridyl function, gave rise to AP84, which was less active in the acute model, but gave 54% and 75% protection both during the first day and fifth day, respectively, in the chronic model. A dual mechanism of action is proposed for AP84, a non-steroidal drug which has exhibited remarkable activity when compared to the steroid dexamethasone. These results open up new avenues in designing novel anti-inflammatory drugs as dual inhibitors with the incorporation of a pyridine template as part of the pharmacophore.     

Allosteric activator domain of maintenance human DNA (cytosine-5) methyltransferase and its role in methylation spreading

The human maintenance DNA (cytosine-5) methyltransferase (hDNMT1) consists of a large N-terminal regulatory domain fused to a catalytic C-terminal domain by randomly repeated Gly-Lys dipeptides. Several N-terminal deletion mutants of hDNMT1 were made, purified, and tested for substrate specificity. Deletion mutants lacking 121, 501, 540, or 580 amino acids from the N-terminus still functioned as DNA methyltransferases, methylated CG sequences, and preferred hemimethylated to unmethylated DNA, as did the full-length hDNMT1. Methylated DNA stimulated methylation spreading on unmethylated CpG sequences for the full-length and the 121 amino acid deletion hDNMT1 equally well but not for the mutants lacking 501, 540, or 580 amino acids, indicating the presence of an allosteric activation determinant between amino acids 121 and 501. Peptides from the N- and C-termini bound methylated DNA independently. Point mutation analysis within the allosteric region revealed that amino acids 284-287 (KKHR) were involved in methylated DNA-mediated allosteric activation. Allosteric activation was reduced in the double point mutant enzymes D25 (K284A and K285A) and D12 (H286A and R287A). Retinoblastoma gene product (Rb), a negative regulator of DNA methylation, bound to the allosteric site of hDNMT1 and inhibited methylation, suggesting Rb may regulate methylation spreading.     

A comparative study of foot dimension between adult male and female and evaluation of foot hazards due to using of footwear

Using footwear often becomes troublesome and creates many problems. Most of these problems are associated with the wearing of ill-fitting footwear, as it leads to biomechanical imbalance and ultimately give rise to different foot problems. In the present investigation different foot problems, viz., discomfort, pain and other hazards related to the use of footwear have been evaluated and attempts have been made to study different foot dimensions of men and women that are related to the design of footwear. For the present study different foot dimensions of both right and left feet of the subjects were measured on 300 Bengalee (Indian) subjects having the age range of 20-35 years. The subjects reported that they had got discomfort, pain, blister and corn due to using different footwear. It was noted that the occurrence of these problems in right foot was greater than that in left foot. There was no significant correlation between foot troubles and type of footwear. Results also showed that there was no significant difference in most of the foot dimensions between left foot and right foot. However, significant difference (P < 0.001) in all foot dimensions was observed between male and female subjects. Correlation coefficient among different foot dimensions has also been evaluated and it was noted that foot length was highly correlated with stature and foot volume, particularly in left foot. Footwear should be made according to the foot dimensions of the user population. The database collected from the Bengalee (Indian) population may be a helpful guide for manufacturing different footwear.     

Dynamics of chromosome compaction during mitosis

We have quantitatively studied the space-time dynamics of mitotic chromosome compaction in cultured amphibian cells. After collecting digital phase-contrast images we have done digital image analysis to study spatial correlations in density. We find a characteristic distance at which the strongest correlations occur, which provides a quantitative measure of the size of patches of dense chromatin during interphase and early prophase. Later in mitosis, this length corresponds to the thickness of prophase and metaphase chromosomes. We find that during interphase strong correlations exist at a few-micrometer length; during prophase this correlation length progressively drops as the chromosomes are compacted. Our data are explained by a model based on assembly of chromatin loops onto already fiberlike interphase chromosomes. To test this model we have microinjected cobalt hexamine trichloride into interphase nuclei and have observed the rapid condensation of the interphase chromatin into thick fibers with a spacing similar to the native-state interphase correlation length determined from our image analysis.     

MQ-HCN-based pulse sequences for the measurement of 13C1′-1H1′, 13C1′-15N, 1H1′-15N, 13C1′-13C2′, 1H1′-13C2′, 13C6/8-1H6/8, 13C6/8-15N, 1H6/8-15N, 13C6-13C5, 1H6-13C5 dipolar couplings in 13C, 15N-labeled DNA (and RNA)

A suite of multiple quantum (MQ) HCN-based pulse sequences has been developed for the purpose of collecting dipolar coupling data in labeled nucleic acids. All the pulse sequences are based on the robust MQ-HCN experiment which has been utilized for assignment purposes in labeled nucleic acids for a number of years and provides much-needed resolution for the dipolar coupling measurements. We have attempted to collect multiple couplings centered on the 13C1' and 13C6/8 positions. Six pulse sequences are described, one each for measurement of one-bond 13C1'-1H1' and 13C6/8-1H6/8 couplings, one for measurement of one-bond 13C1'-15N and two-bond 1H1'-15N couplings, one for measurement of one-bond 13C6/8-15N and two-bond 1H6/8-15N couplings, one for measurement of one-bond 13C1'- 13C2' and two-bond 1H1'-13C2' couplings, and one for measurement of one-bond 13C6-13C5 and two-bond 1H6-13C5 couplings in the bases of C and T. These sequences are demonstrated for a labeled 18 bp DNA duplex in a 47 kDa ternary complex of DNA, CBFbeta, and the CBFalpha Runt domain, thus clearly demonstrating the robustness of the pulse sequences even for a very large complex.     

Stepwise self-assembled poly(amidoamine) dendrimer and poly(styrenesulfonate) microcapsules as sustained delivery vehicles

Hollow microcapsules comprised of poly(styrenesulfonate) (PSS) and a fourth generation poly(amidoamine) dendrimer (4G PAMAM) were prepared by depositing PSS/4G PAMAM multilayers on melamine formaldehyde (MF) colloid particles by the layer-by-layer self-assembly technique and subsequently dissolving the templated cores. The PSS/4G PAMAM layers were unstable toward the core removal procedure (pH approximately 1), resulting in a low yield of intact hollow capsules (<10% for 3.5 microm diameter MF templates). Stretching of the multilayer film due to core swelling during MF core dissolution leads to partial or complete destruction of capsules, giving discrete PSS-4G PAMAM complexes. Yields were increased by increasing inter- and intramolecular attractive forces between the PSS chains in the capsules through electrostatic, hydrophobic, and a combination of these interactions. The yields, however, were practically unaffected by enhancing such effects between dendrimer molecules. Transmission electron microscopy and scanning force microscopy measurements show no deformation for 3.5 microm capsules stabilized through the various interactions stated above. Further, capsules were filled with low molecular weight dextran sulfate and subsequently loaded with a model, therapeutically active molecule, doxorubicin hydrochloride (DOX). Release of DOX from the capsules was also studied to highlight the drug delivery potential of the dendrimer-based microcapsules.     

Evidence for sequence-dependent and reversible nonspecific effects of PS-capped antisense treatment after intracerebral administration

Phosphorothioate (PS)-capped phosphodiester (PE) oligodeoxynucleotides (ODNs) were used to determine whether the dopamine-dependent locomotor-stimulant effect of nicotine is mediated via a4 subunit-containing nicotinic receptors. To this end, rats received direct intraventral tegmental area infusion of a4 antisense via osmotic minipump, and their locomotor response to nicotine (0.2 mg/kg, s.c.) was tested. Eight antisense ODNs were screened, but only one inhibited nicotine-induced locomotion. This inhibition was reversible and selective, insofar as basal (saline) activity was unaffected, and a mismatch ODN was without effect. However, antisense treatment also caused sequence-dependent toxic effects, including neuronal degeneration in the ventral tegmental area, dopaminergic denervation, and weight loss. We conclude that despite previous reports, PS-capped PE-ODNs can cause severe neurotoxicity on chronic infusion into brain tissue. Moreover, sequence dependence and temporal reversibility, two generally accepted criteria of antisense action, may sometimes reflect the occurrence of toxic effects and resultant functional compensation.