A review of molecular modelling studies of dihydrofolate reductase inhibitors against opportunistic microorganisms and comprehensive evaluation of new models

Dihydrofolate reductase (DHFR) has been used as a target for antimicrobial drug discovery against a variety of pathogenic microorganisms, including opportunistic microorganisms; Pneumocystis carinii (pc), Toxoplasma gondii (tg) and Mycobacterium avium complex (ma). In this regard, several DHFR inhibitors are reported against pc and tg and ma. However, selectivity issue of these inhibitors over human DHFR often preclude their development and clinical use. In the first part of this work, various computational approaches including available crystallographic structures, binding affinity prediction, pharmacophore mapping, QSAR, homology modelling used for design of DHFR inhibitors against opportunistic microorganisms are reviewed, to understand specific interactions required for inhibition of microbial DHFR. Secondly, comprehensive molecular modelling techniques were used, to establish structure-chemical-feature-based pharmacophore models for pcDHFR, tgDHFR and mammalian DHFR. The results show that, the information encoded by ligand based approaches like pharmacophore mapping and 3D-QSAR methods are in well agreement with the information coded in the receptor structure. A combination of ligand and structure based approaches provides understanding of ligand-receptor interactions. The study indicated that the value of small alkyl moieties at position 5 of the bicyclic nitrogen containing nucleus along with a bulky group attached at the C-6 via suitable linker could optimize activity, with regard to both potency and selectivity.     

Targeting lung cancer using an infectivity enhanced CXCR4-CRAd

Conventional treatments are not adequate for the majority of lung cancer patients. Conditionally replicating adenoviruses (CRAds) represent a promising new modality for the treatment of neoplastic diseases, including non-small cell lung cancer. Specifically, following cellular infection, the virus replicates selectively in the infected tumor cells and kills the cells by cytolysis. Next, the progeny virions infect a new population of surrounding target cells, replicate again and eradicate the infected tumor cells while leaving normal cells unaffected. However, to date, there have been two main limitations to successful clinical application of these CRAd agents; i.e. poor infectivity and poor tumor specificity. Here we report the construction of a CRAd agent, CRAd-CXCR4.RGD, in which the adenovirus E1 gene is driven by a tumor-specific CXCR4 promoter and the viral infectivity is enhanced by a capsid modification, RGD4C. This agent CRAd-CXCR4.RGD, as expected, improved both of the viral infectivity and tumor specificity as evaluated in an established lung tumor cell line and in primary tumor tissue from multiple patients. As an added benefit, the activity of the CXCR4 promoter was low in human liver as compared to three other promoters regularly used for targeting tumors. In addition, this agent has the potential of targeting multiple other tumor cell types. From these data, the CRAd-CXCR4.RGD appears to be a promising novel CRAd agent for lung cancer targeting with low host toxicity.     

Human papillomavirus type 77 E7 protein is a weak deregulator of cell cycle

Human Papillomavirus type 77 is a skin type found in non-melanoma skin cancers of immuno-compromised individuals. Although, the HPV77 E6 oncoprotein has been well studied, nothing is known about E7. Studies on mucosal HPV types (e.g. HPV16) showed that E7 deregulates the cell cycle by binding to and promoting degradation of retinoblastoma protein (pRb). Here, we characterized the impact of HPV77 E7 on the cell cycle. We observed that HPV77 E7 associated with pRb with a lower affinity than HPV16 E7, promoting weakly its degradation. Although, HPV16 E7 led to cellular proliferation and accumulation of the cell cycle inhibitor p16(INK4a), both events were not clearly observed in HPV77 E7 cells. Together, these data indicate that HPV77 E7 does not efficiently deregulate the cell cycle, in contrast to several E7s of mucosal HPV types.     

Management of hindfoot disease in rheumatoid arthritis

There is a wide variety of hindfoot disease seen in patients with rheumatoid arthritis. Initial treatment is conservative including optimizing medical management to control the disease process. Should symptoms persist, surgical treatment may be performed, although there is an increased complication rate related to both the disease and the side effects of the medications used to treat it.     

S100A4 is upregulated in injured myocardium and promotes growth and survival of cardiac myocytes

OBJECTIVE: The multifunctional Ca2+-binding protein S100A4 (also known as Mts1 and Fsp1) is involved in fibrosis and tissue remodeling in several diseases including cancer, kidney fibrosis, central nervous system injury, and pulmonary vascular disease. We previously reported that S100A4 mRNA expression was increased in hypertrophic rat hearts and that it has pro-cardiomyogenic effects in embryonic stem cell-derived embryoid bodies. We therefore hypothesized that S100A4 could play a supportive role in the injured heart. METHODS AND RESULTS: Here we verify by quantitative real-time PCR and immunoblotting that S100A4 mRNA and protein is upregulated in hypertrophic rat and human hearts and show by way of confocal microscopy that S100A4 protein, but not mRNA, appears in cardiac myocytes only in the border zone after an acute ischemic event in rat and human hearts. In normal rat and human hearts, S100A4 expression primarily colocalizes with markers of fibroblasts. In hypertrophy elicited by aortic banding/stenosis or myocardial infarction, this expression is increased. Moreover, invading macrophages and leucocytes stain strongly for S100A4, further increasing cardiac levels of S100A4 protein after injury. Promisingly, recombinant S100A4 protein elicited a robust hypertrophic response and increased the number of viable cells in cardiac myocyte cultures by inhibiting apoptosis. We also found that ERK1/2 activation was necessary for both the hypertrophy and survival effects of S100A4 in vitro. CONCLUSIONS: Along with proposed angiogenic and cell motility stimulating effects of S100A4, these findings suggest that S100A4 can act as a novel cardiac growth and survival factor and may have regenerative effects in injured myocardium.     

Functional comparison of mouse CIRE/mouse DC-SIGN and human DC-SIGN

CIRE/mDC-SIGN is a C-type lectin we originally identified as a molecule differentially expressed by mouse dendritic cell (DC) populations. Immunostaining with a CIRE/mDC-SIGN-specific mAb revealed that CIRE/mDC-SIGN is indeed on the surface of some CD4+, CD4- 8- DCs and plasmacytoid pre-DCs, but not on CD8+ DCs. It has been proposed that CIRE/mDC-SIGN is the functional orthologue of human DC-SIGN (hDC-SIGN), a molecule that both enhances T cell responses and facilitates antigen uptake. We assessed if CIRE/mDC-SIGN and hDC-SIGN exhibit functional similarities. CIRE/mDC-SIGN is down-regulated upon activation, but unlike hDC-SIGN, incubation with IL-4 and IL-13 did not enhance CIRE/mDC-SIGN expression, indicating differences in gene regulation. Like hDC-SIGN, CIRE/mDC-SIGN bound mannosylated residues. However, we could detect no role for CIRE/mDC-SIGN in T cell-DC interactions and the protein did not bind to pathogens known to interact with hDC-SIGN, including Leishmania mexicana, cytomegalovirus, HIV and lentiviral particles bearing the Ebolavirus glycoprotein. The binding of CIRE/mDC-SIGN to hDC-SIGN ligands was not rescued when CIRE/mDC-SIGN was engineered to express the stalk region of hDC-SIGN. We conclude that there are significant differences in the fine specificity of the C-type lectin domains of hDC-SIGN and CIRE/mDC-SIGN and that these two molecules may not be functional orthologues.     

A common mutation in the CBS gene explains a high incidence of homocystinuria in the Qatari population

We report the results of a study carried out to delineate genetic and epidemiological aspects of homocystinuria in the Qatari population. Sixty-four patients with homocystinuria (37 males, 27 females, age 1 to 29 years) from 31 nuclear families were ascertained over a period of more than four years. The incidence of homocystinuria in Qatar was calculated to be > or =1:3000, the highest in the world known so far. All patients in whom data were available were vitamin B6-nonresponsive. Molecular studies were performed in all patients. All 53 patients from tribe M and all three patients from tribe K were homozygous for the mutation c.1006C>T (p.R336C) in the CBS gene, with an additional seven patients resulting from mixed marriages between tribe M and tribe K. A single patient from tribe S was homozygous for mutation c.700G>A (p.D234N) in the CBS gene. Both mutations have been previously reported but involve hypermutable CpG dinculeotides and may be recurrent mutations in the Qatari population. The results of this study illustrate a strong founder effect causing a high prevalence of an autosomal recessive disease in a highly consanguineous Arabian population. Molecular neonatal screening may be suitable for early detection of homocystinuria in this population.     

Pregnancy outcome in women presenting with pre-eclampsia at less than 25 weeks gestation

OBJECTIVE: We aimed to (i) assess maternal and perinatal outcomes in pre-eclampsia at < 25(0) weeks; and (ii) determine if any antenatal factors were associated with adverse maternal and perinatal outcomes. DESIGN: A retrospective study. SETTING: Tertiary referral hospital, Auckland, New Zealand. METHODS: Data were extracted from the clinical record and hospital database. The study population involved women admitted with pre-eclampsia at < 25(0) weeks, with a live singleton pregnancy, from 1997 to 2004 and managed expectantly. OUTCOME MEASURES: Maternal morbidity, perinatal death, neurodevelopmental outcome at 18 months, small for gestational age assessed by population and customised birthweight centiles. RESULTS: Gestation at admission was the only antenatal variable associated with adverse perinatal outcome. Of 14 women admitted < 23 weeks, no babies survived, but eight (62%) babies of women admitted in the 24th week (24(0)-24(6)) survived. Neurodevelopmental outcome was assessed in eight of nine survivors; two (25%) had moderate and two (25%) had minor disability. All babies in this cohort had birthweights < 5th customised centile. Only one baby (10%) weighing < 500 g survived. CONCLUSION: Maternal morbidity was high in this expectantly managed cohort. As no babies survived when pre-eclampsia occurred before 23 weeks, induction of labour should be considered. In the 24th week two-thirds of babies survived and 25% had moderate handicap. This information may help clinicians and women in the future to make informed choices about management.     

Lack of Association of VDR Gene Polymorphisms with Thyroid Autoimmune Disorders: Familial and Case/Control Studies

We study the association between three Vitamin D receptor gene polymorphisms (rs10735810, rs1544410, rs731236) and susceptibility to thyroid autoimmune diseases. Seventy-six affected subjects, belonging to a large family, as well as one hundred unrelated Tunisian patients and one hundred healthy Tunisian controls were genotyped. A family-based association test and a standard chi-square test were used to assess association in family and case-control data, respectively. Our results showed no significant association of the Vitamin D receptor gene polymorphisms with the susceptibility to thyroid autoimmune diseases in the family. Moreover, allele frequencies for the three polymorphisms in the Tunisian population were similar to those reported in the Tunisian control population and none was associated with the disease. These results suggest a lack of association between the Vitamin D receptor gene polymorphisms and susceptibility to thyroid autoimmune diseases in Tunisian population, in agreement with data from the UK, but in conflict with studies from the Far East.