Oral and intestinal Candida colonization in patients undergoing hematopoietic stem-cell transplantation

We investigated (1) the prevalence and quantity of, as well as risk factors for, orointestinal Candida colonization in patients undergoing hematopoietic stem-cell transplantation (HSCT) and (2) the genetic relatedness of colonizing C. albicans strains. Mouth-wash and stool samples were collected from 77 patients before they underwent HSCT and on days 1, 8, and 15 and were quantitatively cultured. C. albicans isolates were genotyped by microsatellite-marker analysis. The prevalence and quantity of orointestinal Candida colonization varied over time. In 48% (13/27) of multicolonized patients, the same Candida genotype was present in oral and intestinal samples. Oral colonization and decontamination of the gut by vancomycin and paromomycin were risk factors for intestinal Candida colonization.     

An orthotopic model of pancreatic somatostatin receptor (SSTR)-positive tumors allows bimodal imaging studies using 3T MRI and animal PET-based molecular imaging of SSTR expression

Somatostatin receptor (SSTR) scintigraphy is currently used as one standard imaging modality in neuroendocrine tumors (NETs). However, future optimization of NET imaging may be achieved with positron emission tomography based methods utilizing more sensitive and specific tracers in combination with computed tomography or magnetic resonance imaging. Here we established an orthotopic mouse model that reflects relevant aspects of human pancreatic NETs such as SSTR expression, dense vascularization and metastatic disease. This model was then utilized to test the feasibility of combined magnetic resonance imaging and animal positron emission tomography. Orthotopic implantation of amphicrine, SSTR-positive pancreatic AR42J cells resulted in rapidly growing tumors, with concomitant metastatic spread into abdominal lymph nodes and peritoneal cavity. Primary tumors as well as their metastases expressed the neuroendocrine markers chromogranin A and synaptophysin. For imaging experiments, the SSTR ligands (68)Ga-DOTATOC or (68)Ga-DOTANOC were injected intravenously, and animals were subsequently examined in an animal positron emission tomography scanner and a clinical 3T (tesla) magnetic resonance imager. All animals showed radionuclide accumulation in the primary tumor. Definite anatomical correlation was achieved using digital image fusion of the positron emission tomography and magnetic resonance imaging data. (68)Ga-DOTANOC strongly accumulated in the tumor tissue (mean 6.6-fold vs. control tissues) when compared to (68)Ga-DOTATOC, which showed a higher renal clearance. In good agreement with the biodistribution data, the kidney-to-tumor ratio was higher for (68)Ga-DOTATOC (2.43-fold vs. 1.75-fold). Consequently, (68)Ga-DOTANOC achieved better signal enhancement in the primary tumor and allowed for detection of metastatic lesions. In summary, we established a novel orthotopic pancreatic SSTR-positive tumor model and used this model to provide proof of principle for the diagnostic combination of SSTR-based molecular imaging and magnetic resonance imaging. Specifically, the animal model allowed the comparative evaluation of (68)Ga-DOTANOC and (68)Ga-DOTATOC, with (68)Ga-DOTANOC providing better tumor-specific accumulation and renal activity. We conclude that this animal model will be of innovative value for further investigation in the imaging of NETs.     

No association between systemic sclerosis and C77G polymorphism in the human PTPRC (CD45) gene

OBJECTIVE: The functional variant C77G (rs17612648) of PTPRC (CD45) was described to confer risk for systemic sclerosis (SSc) in German Caucasians. We analyzed this association in an independent, larger German cohort. METHODS: We genotyped 171 cases and 179 controls. Cases were subgrouped according to sex, autoantibody profiles, or clinical subsets. RESULTS: No association of SSc with C77G was detected in the whole dataset, in subgroups, or in combined analyses with a previous study. CONCLUSION: The results do not confirm PTPRC C77G as a general and independent risk factor for development of SSc.     

Computational toxicology in drug development

Computational tools for predicting toxicity have been envisaged for their potential to considerably impact the attrition rate of compounds in drug discovery and development. In silico techniques like knowledge-based expert systems (quantitative) structure activity relationship tools and modeling approaches may therefore help to significantly reduce drug development costs by succeeding in predicting adverse drug reactions in preclinical studies. It has been shown that commercial as well as proprietary systems can be successfully applied in the pharmaceutical industry. As the prediction has been exhaustively optimized for early safety-relevant endpoints like genotoxicity, future activities will now be directed to prevent the occurrence of undesired toxicity in patients by making these tools more relevant to human disease.     

Biodegradable, cationic methacrylamide-based polymers for gene delivery to ovarian cancer cells in mice

A series of cationic, methacrylamide polymers was tested for use as a biodegradable gene carrier in ovarian cancer. Tumor transfection activity of polyplexes consisting of a reporter gene and different methacrylamide polymers was assessed, after intraperitoneal injection in mice bearing an ovarian cancer xenograft. In this model, polyplexes based on poly(HPMA-DMAE) showed transfection activity similar to polyplexes based on the nondegradable and rather toxic polyethylenimine (PEI22). The tumor transfection activity of the pHPMA-DMAE polyplexes was remarkable considering their poor transfection activity in in vitro assays. Polyplexes based on pHPMA-DMAE were devoid of any cytotoxicity and mediated highest transfection activity at the highest N/P ratio investigated. Tumor cell gene expression after a single administration of these polyplexes rapidly declined within time, at a similar rate to that observed after injection with polyplexes based on PEI22. Incubation of the polyplexes with hyaluronic acid (HA), a polyanion accumulating in the ascitic fluid of ovarian cancer bearing mice, changed the physical characteristics of the pHPMA-DMAE and PEI22 polyplexes. The transfection activity of PEI22-based polyplexes, but not that of pHPMA-DMAE based polyplexes, was strongly impaired by HA. Differences in HA sensitivity might have contributed to the in vivo gene expression activities of pHPMA-DMAE- and PEI22-based polyplexes. pHPMA-DMAE-based polyplexes have potential for use in ovarian cancer therapy due to their considerable transfection activity, their low cytotoxicity, and their HA resistance.     

Similarity searching and scaffold hopping in synthetically accessible combinatorial chemistry spaces

Large collections of combinatorial libraries are an integral element in today's pharmaceutical industry. It is of great interest to perform similarity searches against all virtual compounds that are synthetically accessible by any such library. Here we describe the successful application of a new software tool CoLibri on 358 combinatorial libraries based on validated reaction protocols to create a single chemistry space containing over 10 (12) possible products. Similarity searching with FTrees-FS allows the systematic exploration of this space without the need to enumerate all product structures. The search result is a set of virtual hits which are synthetically accessible by one or more of the existing reaction protocols. Grouping these virtual hits by their synthetic protocols allows the rapid design and synthesis of multiple follow-up libraries. Such library ideas support hit-to-lead design efforts for tasks like follow-up from high-throughput screening hits or scaffold hopping from one hit to another attractive series.     

Clofibrate treatment up-regulates novel organic cation transporter (OCTN)-2 in tissues of pigs as a model of non-proliferating species

Recent studies have shown that treatment of rodents with agonists of peroxisome proliferator-activated receptor (PPAR)-alpha causes an up-regulation of novel organic cation transporter (OCTN)-2, a carnitine transporter, and increases carnitine concentration in the liver. This study was performed to investigate whether such effects occur also in pigs which like humans have a lower expression of PPAR alpha and are less responsive to treatment with PPAR alpha agonists than rodents. An experiment with 18 pigs was performed which were fed a control diet or the same diet supplemented with 5 g clofibrate/kg for 28 days. Pigs treated with clofibrate had higher relative mRNA concentrations of OCTN2 in liver (3.1-fold), skeletal muscle (1.5-fold) and epithelial cells from small intestine (1.8-fold) than control pigs (P<0.05). Pigs treated with clofibrate had also higher concentrations of free and total carnitine in the liver and a higher concentration of free carnitine in skeletal muscle than control pigs (P<0.05). Concentrations of gamma-butyrobetaine, the precursor of endogenous formation of carnitine, in liver, muscle and plasma did not differ between both groups; the activity of gamma-butyrobetaine dioxygenase, the rate limiting enzyme of carnitine synthesis, in the liver was lower in pigs treated with clofibrate than in control pigs (P<0.05). This study shows for the first time that treatment with a PPAR alpha agonist causes an up-regulation of OCTN2 in liver, muscle and enterocytes from small intestine of pigs. This in turn increases carnitine concentrations in liver and muscle probably by enhancing carnitine uptake into cells.     

Mutations close to functional motif IV in HSV-1 UL5 helicase that confer resistance to HSV helicase-primase inhibitors, variously affect virus growth rate and pathogenicity

Herpes simplex virus (HSV) helicase-primase (HP) is the target for a novel class of antiviral compounds, the helicase-primase inhibitors (HPIs), e.g. BAY 57-1293. Although mutations in herpesviruses conferring resistance to nucleoside analogues are commonly associated with attenuation in vivo, to date, this is not necessarily true for HPIs. HPI-resistant HSV mutants selected in tissue culture are reported to be equally pathogenic compared to parental virus in animal models. Here we demonstrate that a slow-growing HSV-1 mutant, with the BAY 57-1293-resistance mutation Gly352Arg in UL5 helicase, is clearly less virulent than its wild-type parent in a murine zosteriform infection model. This contrasts with published results obtained for a mutant containing a different HPI-resistance substitution (Gly352Val) at the same location, since this mutant was reported to be fully pathogenic. We believe our report to be the first to describe an HPI-resistant HSV-1 mutant, that is markedly less virulent in vivo and slowly growing in tissue culture compared to the parental strain. Another BAY 57-1293-resistant UL5 mutant (Lys356Gln), which showed faster growth characteristics in cell culture, however, was at least equally virulent compared to the parent strain.