Synthesis and antifungal activities of miltefosine analogs

Miltefosine is an alkylphosphocholine that shows broad-spectrum in vitro antifungal activities and limited in vivo efficacy in mouse models of cryptococcosis. To further explore the potential of this class of compounds for the treatment of systemic mycoses, nine analogs (3a-3i) were synthesized by modifying the choline structural moiety and the alkyl chain length of miltefosine. In vitro testing of these compounds against the opportunistic fungal pathogens Candida albicans, Candida glabrata, Candida krusei, Aspergillus fumigatus, and Cryptococcus neoformans revealed that N-benzyl-N,N-dimethyl-2-{[(hexadecyloxy)hydroxyphosphinyl]oxy}ethanaminium inner salt (3a), N,N-dimethyl-N-(4-nitrobenzyl)-2-{[(hexadecyloxy)hydroxyphosphinyl]oxy}ethanaminium inner salt (3d), and N-(4-methoxybenzyl)-N,N-dimethyl-2-{[(hexadecyloxy)hydroxyphosphinyl]oxy}ethanaminium inner salt (3e) exhibited minimum inhibitory concentrations (MIC) of 2.5-5.0 μg/mL against all tested pathogens, when compared to miltefosine with MICs of 2.5-3.3 μg/mL. Compound 3a showed low in vitro cytotoxicity against three mammalian cell lines similar to miltefosine. In vivo testing of 3a and miltefosine against C. albicans in a mouse model of systemic infection did not demonstrate efficacy. The results of this study indicate that further investigation will be required to determine the potential usefulness of the alkylphosphocholines in the treatment of invasive fungal infections.

Associations between coronary heart disease and individual components of the metabolic syndrome according to glucose tolerance status

OBJECTIVE

To assess whether the contributions of individual metabolic syndrome components to coronary heart disease (CHD) risk vary in patients with different glucose tolerance.

METHODS

A total of 1619 patients were included in this cross-sectional study. CHD, metabolic syndrome and glucose tolerance were assessed using coronary angiography, anthropometric and biochemical parameters, and an oral glucose tolerance test, respectively. Associations between CHD and components of metabolic syndrome were determined using logistic regression analysis.

RESULTS

Low high-density lipoprotein-cholesterol (HDL-C) was the only CHD risk factor in patients with both CHD and metabolic syndrome who had normal glucose tolerance, after adjustments for age, smoking and low-density lipoprotein-cholesterol (LDL-C) concentration. In patients with CHD plus metabolic syndrome and prediabetes, the most important risk factor was hypertension; additional risk factors were high postprandial blood glucose (PBG) and low HDL-C. In patients with CHD plus metabolic syndrome and diabetes, high PBG was the strongest risk factor, followed by hypertension, high FBG and high waist circumference.

CONCLUSIONS

Individual components of metabolic syndrome contributed variously to CHD across different glucose tolerance statuses.

Discovering thiamine transporters as targets of chloroquine using a novel functional genomics strategy

Chloroquine (CQ) and other quinoline-containing antimalarials are important drugs with many therapeutic benefits as well as adverse effects. However, the molecular targets underlying most such effects are largely unknown. By taking a novel functional genomics strategy, which employs a unique combination of genome-wide drug-gene synthetic lethality (DGSL), gene-gene synthetic lethality (GGSL), and dosage suppression (DS) screens in the model organism Saccharomyces cerevisiae and is thus termed SL/DS for simplicity, we found that CQ inhibits the thiamine transporters Thi7, Nrt1, and Thi72 in yeast. We first discovered a thi3Δ mutant as hypersensitive to CQ using a genome-wide DGSL analysis. Using genome-wide GGSL and DS screens, we then found that a thi7Δ mutation confers severe growth defect in the thi3Δ mutant and that THI7 overexpression suppresses CQ-hypersensitivity of this mutant. We subsequently showed that CQ inhibits the functions of Thi7 and its homologues Nrt1 and Thi72. In particular, the transporter activity of wild-type Thi7 but not a CQ-resistant mutant (Thi7^T287N) was completely inhibited by the drug. Similar effects were also observed with other quinoline-containing antimalarials. In addition, CQ completely inhibited a human thiamine transporter (SLC19A3) expressed in yeast and significantly inhibited thiamine uptake in cultured human cell lines. Therefore, inhibition of thiamine uptake is a conserved mechanism of action of CQ. This study also demonstrated SL/DS as a uniquely effective methodology for discovering drug targets.

By using a novel SL/DS methodology in the model organism yeast, we discovered that the antimalarial drug CQ inhibits thiamine transporters and consequently causes thiamine (vitamin B1) deficiency and growth defects. This mechanism of action (MOA) is conserved in human cells and possibly also in other organisms. Given that both thiamine deficiency and treatment with CQ cause retinal, neurological, and cardiovascular disorders in humans, our results suggest that thiamine deficiency might be a root cause of some of CQ's adverse effects, which might be preventable with concomitant dietary thiamine supplementation. Such a MOA by CQ could also be responsible for its therapeutic effects against malarial parasites, which need exogenous thiamine for survival. Such a possibility needs to be investigated before dietary thiamine supplementation can be used to prevent CQ's adverse effects.

DANPOS: dynamic analysis of nucleosome position and occupancy by sequencing

Recent developments in next-generation sequencing have enabled whole-genome profiling of nucleosome organizations. Although several algorithms for inferring nucleosome position from a single experimental condition have been available, it remains a challenge to accurately define dynamic nucleosomes associated with environmental changes. Here, we report a comprehensive bioinformatics pipeline, DANPOS, explicitly designed for dynamic nucleosome analysis at single-nucleotide resolution. Using both simulated and real nucleosome data, we demonstrated that bias correction in preliminary data processing and optimal statistical testing significantly enhances the functional interpretation of dynamic nucleosomes. The single-nucleotide resolution analysis of DANPOS allows us to detect all three categories of nucleosome dynamics, such as position shift, fuzziness change, and occupancy change, using a uniform statistical framework. Pathway analysis indicates that each category is involved in distinct biological functions. We also analyzed the influence of sequencing depth and suggest that even 200-fold coverage is probably not enough to identify all the dynamic nucleosomes. Finally, based on nucleosome data from the human hematopoietic stem cells (HSCs) and mouse embryonic stem cells (ESCs), we demonstrated that DANPOS is also robust in defining functional dynamic nucleosomes, not only in promoters, but also in distal regulatory regions in the mammalian genome.

Correlation between plasma amino acid profiles and the various stages of hepatitis B infection

The amino acid metabolism in patients with hepatitis B virus (HBV) infection is significantly changed. In this study, we analyzed the relationship between the amino acid profiles and varying clinical stages of HBV infection, and investigated their significance. The plasma amino acid concentrations in 115 patients with HBV infection and 32 healthy donors were detected and analyzed, and the main indicators of liver function were measured. Correlation analysis was performed between the amino acid profiles (Fischer's ratio, branched-chain amino acid to tyrosine ratio [BTR]) and the key indicators of liver function in patients with HBV infection. Fisher's ratio and the BTR of patients with HBV infection was found to differ from that of the healthy controls, and was also found to significantly correlate with the stage of HBV infection. Changes in the BTR were closely related to the level of key indicators of liver function, and a significant relationship was detected between the Fischer's ratio and the BTR (r=0.928, p<0.001). These results suggest that Fischer's ratio and the BTR can indirectly reflect the degree of liver cell injury. Determining and tracking the plasma amino acid profiles could, therefore, be used for the diagnosis, treatment selection, and prognosis of patients with varying stages of HBV infection.

Vaspin Serum Concentration in Patients with Type 2 Diabetes and Carotid Plaque

Objective:

To examine whether there is an association between the serum concentration of vaspin and the presence of carotid plaque in early stage type 2 diabetes mellitus (T2DM).

Methods:

Patients ( n = 61) with T2DM within 3 years of diagnosis were divided into those with and those without carotid plaque. Fasting serum vaspin levels, measured by enzymelinked immunosorbent assay, and blood pressure were compared between these two groups and also with an age-matched, apparently healthy control group ( n = 26).

Results:

Fasting serum vaspin concentrations were significantly higher in patients with T2DM without carotid plaque than in controls, but significantly lower in T2DM patients with carotid plaque than inthose without. Multivariate logistic regression analysis showed a significant positive association between the presence of carotid plaque and systolic blood pressure and a significant inverse association between the presence of carotid plaque and fasting serum vaspin concentration.

Conclusion:

A significant inverse association was found, in patients with T2DM within 3 years of diagnosis, between serum vaspin concentration and the presence of carotid plaque.

The Fun30 nucleosome remodeller promotes resection of DNA double-strand break ends

Chromosomal double-strand breaks (DSBs) are resected by 5′-nucleases to form 3′ single-strand DNA (ssDNA) substrates for binding by homologous recombination and DNA damage checkpoint proteins. Two redundant pathways of extensive resection were described both in cells ^1-3 and in vitro^4-6, one relying on Exo1 exonuclease and the other on Sgs1 helicase and Dna2 nuclease. However, it remains unknown how resection proceeds within the context of chromatin where histones and histone-bound proteins represent barriers for resection enzymes. Here, we have identified the yeast nucleosome remodeling enzyme Fun30 as novel factor promoting DSB end resection. Fun30 is the major nucleosome remodeler promoting extensive Exo1- and Sgs1-dependent resection of DSBs while the RSC and INO80 chromatin remodeling complexes play redundant roles with Fun30 in resection adjacent to DSB ends. ATPase and helicase domains of Fun30, which are needed for nucleosome remodeling ⁷, are also required for resection. Fun30 is robustly recruited to DNA breaks and spreads around the DSB coincident with resection. Fun30 becomes less important for resection in the absence of the histone-bound Rad9 checkpoint adaptor protein known to block 5′ strand processing ⁸ and in the absence of either histone H3 K79 methylation or γ-H2A, which mediate recruitment of the Rad9 ^{9, 10}. Together these data suggest that Fun30 helps to overcome the inhibitory effect of Rad9 on DNA resection.

Engineered domain-based assays to identify individual antibodies in oligoclonal combinations targeting the same protein

Quantitation of individual monoclonal antibodies (mAbs) within a combined antibody drug product is required for preclinical and clinical drug development. We have developed two antitoxins, XOMA 3B and XOMA 3E, each consisting of three mAbs that neutralize type B and type E botulinum neurotoxin (BoNT/B and BoNT/E) to treat serotype B and E botulism. To develop mAb-specific binding assays for each antitoxin, we mapped the epitopes of the six mAbs. Each mAb bound an epitope on either the BoNT light chain (LC) or translocation domain (H(N)). Epitope mapping data were used to design LC-H(N) domains with orthogonal mutations to make them specific for only one mAb in either XOMA 3B or XOMA 3E. Mutant LC-H(N) domains were cloned, expressed, and purified from Escherichia coli. Each mAb bound only to its specific domain with affinity comparable to the binding to holotoxin. Further engineering of domains allowed construction of enzyme-linked immunosorbent assays (ELISAs) that could characterize the integrity, binding affinity, and identity of each of the six mAbs in XOMA 3B and 3E without interference from the three BoNT/A mAbs in XOMA 3AB. Such antigen engineering is a general method allowing quantitation and characterization of individual mAbs in a mAb cocktail that bind the same protein.

Polymorphisms in the IL-13 and IL-4R genes are associated with the development of renal cell carcinoma

BACKGROUND

Cytokines are the important modulators that bind to their relevant receptors in response to some stimuli to mediate the homeostasis. It has been suggested that the imbalance of immune system of the host might affect the generation of diseases, including cancers.

PATIENTS AND METHODS

We investigated the association between six functional polymorphisms of IL-4, IL-13, and IL-4R genes and susceptibility to renal cell cancer in a hospital-based study, including 620 renal cell carcinoma (RCC) patients and 623 controls. Logistic regression model was used to assess the genetic effects on the development of RCC.

RESULTS

Overall, individuals with IL-4R Ile50Val CT/TT genotypes had a 0.34-fold significantly decreased RCC risk (CT/TT versus CC), and the T variant allele was associated with a decreased risk of RCC in a dose-response manner (Ptrend=0.009). In addition, we also observed that IL-13 C-1055T and Arg130Gln polymorphisms could decrease the risk of RCC [TT versus

CC/CT

odds ratio=0.36, 95% confidence interval (CI)=0.16-0.78; AA versus GG/GA: 0.66, 0.44-0.97, respectively]. Furthermore, a multiplicative interaction association between the combined IL-4R Ile50Val and IL-13 C-1055T genotypes was observed to decrease the risk of RCC (P=0.036).

CONCLUSION

IL-13 and IL-4R may play an important role in the etiology of RCC.

Recent advances in antiangiogenic agents with VEGFR as target

Angiogenesis is required for invasive tumor growth and metastasis and constitutes an important point in the control of cancer progression. Its inhibition may be a valuable approach to cancer therapy. Antiangiogenic agents are designed to attack the tumor vasculature and cut off the tumor's supply of nutrients. Systemic blockade of angiogenesis has been recently approved for the treatment of several types of human cancers. Antiangiogenic therapy presents various advantages as compared to conventional treatment. Vascular endothelial growth factor (VEGF) is considered to be one of the most important regulators of angiogenesis and a key target in anticancer treatment. VEGF binding to its receptor (VEGFR) leads to cell proliferation and new vascular formation by tyrosine kinase (TK) pathway. VEGF/VEGFR pathway is becoming attractive target for anticancer drug design. It is believed to be important in the control of angiogenesis. Antiangiogenic therapy based on inhibition of VEGFR was reported to be powerful clinical strategies. In this review, the authors describe the existing literature regarding VEGFR inhibitors in the last few years. We attempt to cover all essential publications on the medicinal chemistry in terms of chemical structure, pharmacological profile and structure-activity relationships.