Specific molecular recognition of mixed nucleic acid sequences: an aromatic dication that binds in the DNA minor groove as a dimer

Phenylamidine cationic groups linked by a furan ring (furamidine) and related compounds bind as monomers to AT sequences of DNA. An unsymmetric derivative (DB293) with one of the phenyl rings of furamidine replaced with a benzimidazole has been found by quantitative footprinting analyses to bind to GC-containing sites on DNA more strongly than to pure AT sequences. NMR structural analysis and surface plasmon resonance binding results clearly demonstrate that DB293 binds in the minor groove at specific GC-containing sequences of DNA in a highly cooperative manner as a stacked dimer. Neither the symmetric bisphenyl nor bisbenzimidazole analogs of DB293 bind significantly to the GC containing sequences. DB293 provides a paradigm for design of compounds for specific recognition of mixed DNA sequences and extends the boundaries for small molecule-DNA recognition.     

Hepatic steatosis and the risk of hepatocellular carcinoma in chronic hepatitis C

BACKGROUND AND AIM: Obesity associated hepatic steatosis has been suggested to have a premalignant potential. We determined whether hepatic steatosis predisposes to liver cancer in persons with chronic hepatitis C virus (HCV) infection. METHODS: We compared the histological severity of steatosis in the index liver biopsies of 25 patients with chronic hepatitis C who subsequently developed hepatocellular carcinoma (HCC) with matched controls who did not. Cases were aged (mean) 54.7 years, 84% males, 76% genotype 1, and 64% fibrosis stage 4; and controls were matched for these characteristics. Those with a sustained virologic response to antiviral therapy were excluded. RESULTS: Duration of HCV infection, concomitant alcohol intake, body mass index and indices of past hepatitis B virus (HBV) infection were comparable between the groups. Controls were followed for a longer period after the index liver biopsy than were cases (113 months vs 55 months, P < 0.001). As determined by percentage area of biopsy core occupied by steatosis on computer assisted morphometric evaluation, and graded by semiquantitative histological assessment, steatosis was comparable among cases and controls. The odds of developing HCC among those with steatosis grades 1 and 2 did not differ significantly from those without steatosis. There was no association between increasing morphometric percentage area occupied by steatosis and the subsequent development of HCC. Neither steatosis grade or percent area of steatosis on biopsy were selected in multivariate regression analysis as independent predictors for the development of HCC. CONCLUSIONS: Hepatic steatosis does not augment the risk of hepatocarcinogenesis in patients with chronic HCV infection.     

Outcome after autologous stem cell transplantation for multiple myeloma in patients with preceding plasma cell disorders

A third of patients with multiple myeloma (MM) have a preceding diagnosis of plasma cell proliferative disorder (PCPD), mostly monoclonal gammopathy of undetermined significance (MGUS), smoldering MM (SMM) or plasmacytoma. While autologous stem cell transplantation (SCT) improves survival in MM, it is not clear if patients with preceding PCPD have a different outcome. We identified 151 patients with preceding PCPD from among 804 patients undergoing SCT, and their outcomes were compared. The response rates, including complete responses, were similar between the groups. Patients with a preceding diagnosis of MGUS had longer time to progression (TTP; 27·5 months vs. 17·2 months, P  = 0·01), and longer overall survival (OS) from transplant (80·2 months vs. 48·3 months, P  = 0·03) compared to those with de novo myeloma. However no differences were seen among those with a preceding diagnosis of SMM or plasmacytoma in terms of TTP or OS from transplant when compared to those with de novo myeloma. Multivariate analysis indicated that the presence of MGUS prior to myeloma was prognostic for post-transplant relapse independent of other known risk factors. Patients with pre-existing MGUS prior to myeloma diagnosis have a better outcome following HDT, reflecting more indolent disease and a favourable biology than those presenting with de novo myeloma.     

Seasonal variations of in vivo and in vitro melatonin production in a passeriform bird, the house sparrow (Passer domesticus)

Melatonin, released from the pineal gland, is an important signal within the circadian pacemaking system of passeriform birds. Until now, seasonal variations in melatonin production have only been examined in a few avian species and the role of melatonin in the regulation of annual rhythms in birds is unclear. We investigated plasma melatonin in a group of house sparrows kept in an outside aviary in spring (March/April), summer (May/June), autumn (September/October), and winter (December/January). The durations of elevated melatonin values mirrored the seasonal changes in night length to a certain degree, the melatonin signal being longest in winter and shortest in summer. Additionally, plasma melatonin peak amplitudes differed significantly among seasons, with highest values in spring and summer and lowest values in winter. Cultured explanted pineal glands obtained from animals in winter and summer showed patterns of in vitro melatonin release comparable to in vivo circulating melatonin with different durations of elevated melatonin and peak amplitude values. These data indicate that the circadian pacemaking system of the house sparrow changes properties seasonally, either as a result of endogenous mechanisms or in response to environmental conditions. These properties are maintained in the pineal gland even after isolation from the animal.     

Emerging role of uterine natural killer cells in establishing pregnancy

Normal pregnancy has been considered as a controlled state of inflammation at an early stage of blastocyst implantation that subsequently develops systemically. Till recent past most popular hypotheses regarding status of immune system in pregnancy were dominated by the Th1 and Th2 hypothesis, in which the fetus avoids maternal rejection through a bias towards T-helper (Th2) cytokine production. Recent findings have shown that predominant immune interactions in the human deciduas are between the placental trophoblast and maternal uterine natural killer (uNK) cells rather than the T cells. Thus NK cells are emerging as important players in the uterine immune response to invasive forms of placenta, as in cases of hemochorial placenta. In humans there is a lack of evidence for T-cell responses to trophoblast cells; therefore it was thought that uterine NK cells are the key factors by which the maternal immune system recognizes trophoblast cells. In this review we are trying to summarize the role of uNK cells in the maintenance of normal pregnancy in humans.     

Inhibition of hepatitis B virus DNA replicative intermediate forms by recombinant interferon-γ

AIM: To evaluate the in vitro anti-HBV activity of recombinant human IFN-γ, alone and in combination with lamivudine.METHODS: A recombinant baculovirus-HBV/HepG2 culture system was developed which could support productive HBV infection in vitro. Expression of HBsAg and HBeAg in infected HepG2 culture medium was detected by commercial enzyme immunoassays. HBV DNA replication intermediates were detected in infected cells by Southern hybridization and viral DNA load was determined by dot hybridization.RESULTS: IFN-γ at 0.1 to 5 μg/L efficiently down regulated HBsAg expression in transduced HepG2 cells.At 5 μg/L, IFN-γ also suppressed HBV DNA replication in these cells. While treatment with a combination of lamivudine and IFN-γ showed no additive effect,sequential treatment first with lamivudine and then IFN-γ was found to be promising. In this culture system the best HBV suppression was observed with a pulse of 2 μmol/L lamivudine for two days, followed by 1 μg/L IFN-γ for another four days. Compared to treatment with lamivudine alone, the sequential use of 0.2 μmol/L lamivudine for two days, followed by 5 μg/L IFN-γ for six days showed a 72% reduction in HBV cccDNA pool.CONCLUSION: This in vitro study warrants further evaluation of a combination of IFN-γ and lamivudine,especially in IFN-α non-responder chronic hepatitis B patients. A reduced duration of lamivudine treatment would also restrict the emergence of drug-resistant HBV mutants.     

Influence of quasispecies on virological responses and disease severity in patients with chronic hepatitis C

AIM： To elucidate the influence of quasispecies on virological response and disease severity in patients with chronic hepatitis C.
METHODS： Forty seven patients with hepatitis C [32 with chronic active hepatitis （CAH）, 9 with cirrhosis, and 6 with hepatocellular carcinoma （HCC）] were screened for the presence of quasispecies by single stranded conformational polymorphism （SSCP） analysis in the hypervariable region （HVR） and non-structural 5B （NS5B） viral genes of hepatitis C virus. The 41 patients excluding those with HCC were on therapy and followed up for a year with the determination of virological response and disease severity. Virus isolated from twenty three randomly selected patients （11 non-responders and 12 showing a sustained virological response） was sequenced for the assessment of mutations.
RESULTS： The occurrence of quasispecies was proportionately higher in patients with HCC and cirrhosis than in those with CAH, revealing a significant correlation between the molecular evolution of quasispecies and the severity of disease in patients with hepatitis C. The occurrence of complex quasispecies has a significant association （P 〈 0.05） with the non-responders, and leads to persistence of infection. Significant differences （P 〈 0.05） in viral load （log10 IU/mL） were observed among patients infected with complex quasispecies （CQS）, those infected with simple quasispecies （SQS） and those with no quasispecies （NQS）, after 12 wk （CQS-5.2 ± 2.3, SQS-3.2 ± 1.9, NQS-2.8 ± 2.4） and 24 wk （CQS-3.9 ± 2.2, SQS-3.0 ± 2.2, NQS-2.1 ± 2.3） in the HVR region. However, a statistically significant difference （P 〈 0.05） was observed between the viral loads of patients infected with CQS and those infected with NQS in NS5B viral gene after 24 wk （CQS-3.9 ± 2.2, SQS-3.0 ± 2.2, and NQS-2.1 ± 2.3） and 48 wk （CQS-3.1 ± 2.7, SQS-2.3 ± 2.4, NQS-2.0 ± 2.3） of therapy. Disease severity was significantly associated with viral load during th     

Endothelin as a therapeutic target in the treatment of cardiovascular disease

Endothelins, a family of peptides derived from the vascular endothelium and smooth muscle cells possess vasoconstrictor and mitogenic properties. By acting predominantly in a paracrine fashion, these peptides activate specific receptors and have protean effects in normal and diseased organ systems. The wide distribution of these receptors in various tissues mediate the multiplicity of physiologic actions attributed to endothelins. Much of our understanding about endothelins has come from the development of an array of receptor-specific and mixed receptor antagonists. Based on the promising results from animal studies, active research and drug development programs are under way to investigate the clinical potential of endothelin antagonism for treatment of cardiovascular disease.