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Biomedical subjects

K Raj

Publications and source records attributed to K Raj.

At least 19 recordsLinked to original sources
PubMed2006

Antihyperglycemic and antidyslipidemic agent from Aegle marmelos.

The plant Aegle marmelos belongs to the family of Rutaceae. From the leaves of A. marmelos an alkaloidal-amide, Aegeline 2, was isolated and found to have antihyperglycemic activity as evidenced by lowering the blood glucose levels by 12.9% and 16.9% at 5 and 24h, respectively, in sucrose challenged streptozotocin induced diabetic rats (STZ-S) model at the dose of 100mg/kg body weight. Aegeline 2 has also significantly decreased the plasma triglyceride (Tg) levels by 55% (P<0.001), total cholesterol (TC) by 24% (P<0.05), and free fatty acids (FFA) by 24%, accompanied with increase in HDL-C by 28% and HDL-C/TC ratio by 66% in dyslipidemic hamster model at the dose of 50mg/kg body weight. The reasonable mapping of compound 2 to validated pharmacophoric hypothesis and 3D QSAR model with an estimated activity (283nM) suggest that the compound 2 might be a beta(3)-AR agonist.

Adrenergic beta-3 Receptor Agonists↗
PubMed2005

Rituximab is effective in the management of refractory autoimmune cytopenias occurring after allogeneic stem cell transplantation.

Autoimmune haemolytic anaemia (AIHA), immune thrombocytopenia (ITP) and autoimmune neutropenia (AIN) are well-recognised complications of allogeneic stem cell transplantation (SCT), but have previously only been reported in the context of myeloablative conditioning regimens. Management of AIHA, ITP or AIN occurring after allogeneic SCT is unsatisfactory since they frequently prove refractory to conventional therapies including splenectomy. As a consequence, autoimmune cytopenias occurring after allogeneic SCT are associated with substantial morbidity and mortality. We report four patients who developed AIHA or ITP after allogeneic transplantation -- three of which occurred after a reduced-intensity conditioning (RIC) regimen. All patients demonstrated a complete response to Rituximab, having failed to respond to conventional treatment including high-dose prednisolone and intravenous immunoglobulin (IVIg). We conclude that Rituximab can be a valuable agent in the management of autoimmune cytopenias occurring after allogeneic SCT and that autoimmune cytopenias may be a hitherto unrecognised complication of RIC regimens.

Adult↗
PubMed2002

Solid-phase synthesis and bioevaluation of lupeol-based libraries as antimalarial agents.

The use of the triterpenoid lupeol as a scaffold for the synthesis of lupeol-based libraries is described. Lupeol was anchored to a solid support (Rink amide/Sieber Amide) through aliphatic dicarboxylic acid moieties, which also served as a site for introducing diversity. The resulting polymer linked 3beta-O (resin-alkanoyl)-lup-20(29)-ene 3 was used to generate key intermediates 3beta-O (resin-alkanoyl)-30-bromo-lup-20(29)-ene 4 and 3beta-O (resin-alkanoyl)-30-amino-lup-20(29)-ene 6 for the generation of libraries based on disubstituted lupeol derivatives. A 96-member library was screened for its in-vitro antimalarial activity against Plasmodium falciparum.

Animals↗
PubMed2001

Cinnamoyl shikonin.

The title compound, 1-(5,8-dihydro-1,4-dihydroxy-5,8-dioxo-2-naphthyl)-4-methylpent-3-en-1-yl cinnamate, C(25)H(22)O(6), crystallizes in space group P2(1). The phenyl ring of the cinnamate is anti to the carbonyl group of the same moiety [C-C-C-C = -175.6 (2) degrees] and is nearly parallel to the naphthyl ring system. Two six-membered rings formed by intramolecular hydrogen bonds, with O-H...O distances of 2.587 (2) and 2.589 (2) A, occur on either side of the fused ring system, creating a tetracyclic pyrene-shaped system. The phenyl ring forms an intermolecular stack with the benzoquinone ring, as a result of aromatic pi-pi interactions.

Cinnamates↗
PubMed2001

Virus-mediated killing of cells that lack p53 activity.

A major goal of molecular oncology is to identify means to kill cells lacking p53 function. Most current cancer therapy is based on damaging cellular DNA by irradiation or chemicals. Recent reports support the notion that, in the event of DNA damage, the p53 tumour-suppressor protein is able to prevent cell death by sustaining an arrest of the cell cycle at the G2 phase. We report here that adeno-associated virus (AAV) selectively induces apoptosis in cells that lack active p53. Cells with intact p53 activity are not killed but undergo arrest in the G2 phase of the cell cycle. This arrest is characterized by an increase in p53 activity and p21 levels and by the targeted destruction of CDC25C. Neither cell killing nor arrest depends upon AAV-encoded proteins. Rather, AAV DNA, which is single-stranded with hairpin structures at both ends, elicits in cells a DNA damage response that, in the absence of active p53, leads to cell death. AAV inhibits tumour growth in mice. Thus viruses can be used to deliver DNA of unusual structure into cells to trigger a DNA damage response without damaging cellular DNA and to selectively eliminate those cells lacking p53 activity.

Apoptosis↗
PubMed2001

Modified iridoid glycosides as anti-implantation agents: inhibition of cell adhesion as an approach for developing pregnancy interceptive agents.

Structural modifications in iridoid glycosides and evaluation of their efficacy on adhering capability (in vitro) of immature hamster uterine epithelial cells to the substratum have been studied. Out of 31, eight compounds in vitro, five compounds in utero and two in vivo showed adhesion/implantation preventing activity, respectively. The results provide an indication for further exploration in the line of development of anti-adhesive agents.

Animals↗
PubMed2000

Effect of alkali metal cationization and multiple alkali metal exchange on the collision-induced dissociation of loganic acid studied by electrospray ionization tandem mass spectrometry

Under electrospray ionization conditions loganic acid undergoes alkali metal (Li, Na and K) exchange and alkali metal cationization. Multiple exchanges of up to four alkali metal ions are observed. Different populations of metal exchanged species are produced during electrospray ionization. Collision-induced dissociation of ammonium cationized species is compared with that of metal cationized species to study the effect of metal cationization. Glycosidic cleavage and ring cleavages of aglycone and sugar moieties are the major fragmentation pathways observed during collision-induced dissociation. The fragmentations of the highly metal exchanged species indicate the opening of the pyran ring. Collision-induced dissociation of the various metal exchanged and metal cationized species also reveals the nature of the different populations. Copyright 2000 John Wiley & Sons, Ltd.

Journal Article↗
PubMed2000

Effect of metal cationization on the low-energy collision-induced dissociation of loganin, epi-loganin and ketologanin studied by electrospray ionization tandem mass spectrometry

The effect of alkali metal and silver cationization on the collision-induced dissociation (CID) of loganin (1), epi-loganin (2) and ketologanin (3) is discussed. Their protonated molecular ions fragment mainly by glycosidic cleavages. The epimeric pairs (1 and 2) show differences in the abundances of the resulting fragment ions. Lithium cationization induces new dissociation pathways such as the retro-Diels-Alder (RDA) fragmentation followed by rearrangement. Unlike the dissociation of protonated molecular ions, the dissociation of lithiated molecules also provides lithiated sugar fragments. The CID of dilithiated molecules is substantially different from that of the monolithiated precursors. RDA reaction appears to be favoured by the presence of the additional lithium atom in the molecule. In addition, other ring cleavages are also induced. The abundances of the various fragment ions are different in the CID spectra of the epimeric pairs. Extensive D labelling and (6)Li labelling experiments confirmed many of the ion structures proposed. The CID spectra of the sodiated ions are generally weaker, although similar to those of the corresponding lithiated species. Higher alkali metal ion (K(+), Rb(+) and Cs(+)) adducts generated only the corresponding metal ions as products of CID. Similar fragmentations were also observed in the CID of the [M + Ag](+) ions of these compounds, the epimeric pairs showing characteristic differences in their CID behaviour. Copyright 2000 John Wiley & Sons, Ltd.

Journal Article↗
PubMed2000

The E1E4 protein of human papillomavirus type 16 associates with a putative RNA helicase through sequences in its C terminus.

Human papillomavirus type 16 (HPV16) infects cervical epithelium and is associated with the majority of cervical cancers. The E1E4 protein of HPV16 but not those of HPV1 or HPV6 was found to associate with a novel member of the DEAD box protein family of RNA helicases through sequences in its C terminus. This protein, termed E4-DBP (E4-DEAD box protein), has a molecular weight of 66,000 (66K) and can shuttle between the nucleus and the cytoplasm. It binds to RNA in vitro, including the major HPV16 late transcript (E1E4. L1), and has an RNA-independent ATPase activity which can be partially inhibited by E1E4. E4-DBP was detectable in the cytoplasm of cells expressing HPV16 E1E4 (in vivo and in vitro) and could be immunoprecipitated as an E1E4 complex from cervical epithelial cell lines. In cell lines lacking cytoplasmic intermediate filaments, loss of the leucine cluster-cytoplasmic anchor region of HPV16 E1wedgeE4 resulted in both proteins colocalizing exclusively to the nucleoli. Two additional HPV16 E1E4-binding proteins, of 80K and 50K, were identified in pull-down experiments but were not recognized by antibodies to E4-DBP or the conserved DEAD box motif. Sequence analysis of E4-DBP revealed homology in its E4-binding region with three Escherichia coli DEAD box proteins involved in the regulation of mRNA stability and degradation (RhlB, SrmB, and DeaD) and with the Rrp3 protein of Saccharomyces cerevisiae, which is involved in ribosome biogenesis. The synthesis of HPV16 coat proteins occurs after E1E4 expression and genome amplification and is regulated at the level of mRNA stability and translation. Identification of E4-DBP as an HPV16 E1E4-associated protein indicates a possible role for E1E4 in virus synthesis.

Cell Nucleus↗
PubMed2000

Productive replication of adeno-associated virus can occur in human papillomavirus type 16 (HPV-16) episome-containing keratinocytes and is augmented by the HPV-16 E2 protein.

We used a sensitive assay to test whether an adeno-associated virus (AAV) productive replication cycle can occur in immortalized human keratinocytes carrying episomal human papillomavirus type 16 (HPV-16) DNA. Following transfection with cloned AAV DNA, infectious AAV was produced, and the infectivity was blocked by anti-AAV antiserum. The HPV-16 E2 protein substantially increased the yield of AAV. Other HPV early proteins did not, in our experiments, show this ability. E2 has been shown to be able to affect p53 levels and to block cell cycle progression at mitosis. We tested the effect of changes in p53 expression on AAV replication and found that large differences in the level of p53 did not alter AAV DNA replication. In extension of this, we found that cellular help for AAV in response to stress was also independent of p53. To test if a mitotic block could trigger AAV DNA replication, we treated the cells with the mitotic inhibitor nocodazole. AAV DNA replication was stimulated by the presence of nocodazole in these and a number of other cell types tested. Yields of infectious virus, however, were not increased by this treatment. We conclude that the HPV-16 E2 protein stimulates AAV multiplication in these cells and propose that this occurs independently of the effects of E2 on p53 and cell cycle progression. Since the effect of E2 was not seen in keratinocytes lacking the HPV-16 episome, we suggest that E2 can help AAV by working in concert with other HPV-16 proteins.

Animals↗
PubMed1999

Expression of human papillomavirus 16 E2 protein in Schizosaccharomyces pombe delays the initiation of mitosis.

Infection by some types of human papillomavirus (HPV) is associated with the development of cervical cancer. Analysis of viral DNA from cervical tumours shows that the E2 gene is frequently disrupted during integration into the host cell's DNA. It has therefore been suggested that loss of E2p is an important step in malignant transformation. Expression of E2p in the fission yeast Schizosaccharomyces pombe retards the G2-M transition, by delaying activation of Cdc2p kinase. In contrast, S phase progression, and commitment to cell division in late G1 are not affected. The delay is independent of the transcriptional trans-activation function of E2p, and does not result from E2p DNA binding mimicking DNA damage. Increased expression of E2p also delays mitotic initiation in mammalian cells. S. pombe may thus provide a simple model for the analysis of E2p function.

Adenosine Triphosphatases↗
PubMed1998

Infectious human papillomavirus type 18 pseudovirions.

Human papillomavirus type 18 (HPV18) capsid proteins L1 and L2, synthesised in mammalian cells using recombinant vaccinia viral expression vectors, are transported to the nucleus and assembled into virus-like particles. When 293T cells, which express SV40 T antigen, were transfected with plasmid DNAs containing an SV40 origin of replication then infected with vaccinia viral vectors encoding L1 and L2, plasmid DNA was encapsidated into the particles. The DNAs ranged in size from 5.4 to 7.9 kb. By encapsidating plasmids containing either the beta-galactosidase gene or the puromycin-resistance gene, the pseudovirions were shown to be infectious in that they could transfer beta-galactosidase activity or confer resistance to puromycin to a number of cell types, indicating that the uptake and decapsidation of HPV particles are not the main determinants of cell type specificity of HPV. Episomal HPV16 DNA in a cervical keratinocyte line could also be encapsidated. Further investigation showed that DNA encapsidation is independent of HPV DNA sequences and of T antigen-mediated plasmid DNA replication. Instead, the minor capsid protein, L2, was found to be attached to plasmid mini-chromosomes extracted from these cells, suggesting a role for L2 in encapsidation. Consistent with this, the L1 protein alone was unable to encapsidate DNA, although it was able to form virus-like particles. The results suggest that intracellular episomal DNAs of suitable size can be encapsidated by the HPV18 L1 and L2 proteins without the need of any HPV packaging signal, and reintroduced into cells.

Capsid↗
PubMed1995

The interaction between human papillomavirus type 16 E1 and E2 proteins is blocked by an antibody to the N-terminal region of E2.

Replication of papillomavirus DNA requires two virally encoded proteins, E1 and E2. We expressed human papillomavirus (HPV) type 16 E1 and E2 in bacteria and showed that purified full-length E2 protein interacted directly with E1, in the absence of HPV16 DNA. It was established that the first 142 amino acids of E1 were not required for binding as E2 protein was able to interact with E1 devoid of this region. The interaction of E2 with E1 could be blocked by a monoclonal antibody that bound E2 in the region of amino acids 18-41 of E2 whereas a monoclonal antibody reactive with a nearby part of the molecule (amino acids 2-17) only partially blocked this interaction. These results suggest that a region in the N-terminus of E2 around amino acids 18-41 is a site of interaction with the E1 protein.

Adenosine Triphosphatases↗
PubMed1995

The ATP-binding and ATPase activities of human papillomavirus type 16 E1 are significantly weakened by the absence of prolines in its ATP-binding domain.

The E1 protein of human papillomavirus (HPV) type 16 is the only known papillomavirus E1 which does not contain any proline residues in the phosphate-loop (P-loop) of its ATP-binding site. To ascertain whether this feature influences the activities of HPV-16 E1, we generated a mutant HPV-16 E1 (E1Pro) in which prolines are inserted in place of alanines in this site, making the P-loop identical to its bovine papillomavirus type 1 counterpart. Glutathione S-transferase (GST) fusion proteins (GSTE1wt and GSTE1Pro) were produced, purified and used to assay for ATP-binding ability, ATPase activity and ability to complex with the HPV-16 E2 protein. The results show that the lack of prolines in the P-loop, which is unique to HPV-16 E1, significantly weakens its ATP-binding and ATPase activities without affecting its ability to complex with the HPV-16 E2 protein.

Adenosine Triphosphatases↗