SGI-110: DNA Methyltransferase Inhibitor Oncolytic.

SGI-110 is a second-generation hypomethylating prodrug whose active metabolite is the well-characterized drug decitabine. This novel compound is an oligonucleotide consisting of decitabine linked through a phosphodiester bond to the endogenous nucleoside deoxyguanosine. The dinucleotide configuration provides protection from drug clearance by deamination, while maintaining at least equivalent effects on gene-specific and global hypomethylation both in vitro and in animal model systems. This agent is currently being tested in phase I and II clinical trials in humans and has been demonstrated to be safe and well tolerated as a single agent, with evidence of promising activity in heavily pretreated (including currently FDA approved hypomethylating drugs) myelodysplastic syndrome and acute myeloid leukemia patients. Ongoing trials are also open in platinum-resistant ovarian cancer and hepatocellular carcinoma.

Targeting PIM kinase enhances the activity of sunitinib in renal cell carcinoma.

BACKGROUND: Upregulation of PIM kinase expression has been reported in many malignancies, suggesting that inhibition of PIM kinase activity may be an attractive therapeutic strategy. We hypothesised that inhibition of PIM kinase activity with SGI-1776, a novel small molecule inhibitor of PIM kinase activity, would reduce the viability of renal cell carcinoma (RCC) cells and enhance the activity of sunitinib. METHODS: Immunoblotting, qRT-PCR, and gene expression arrays were carried out to identify genes modulated by SGI-1776 treatment. The anticancer activity of SGI-1776 and sunitinib was determined by viability and apoptosis assays and in tumour xenografts in vivo. RESULTS: Treatment with SGI-1776 led to a decrease in phosphorylated and total c-Myc levels, which resulted in the modulation of c-Myc target genes. SGI-1776 in combination with sunitinib induced a further reduction in c-Myc levels, which was associated with enhanced anticancer activity. siRNA-mediated knockdown of c-Myc demonstrated that its expression has a key role in regulating the sensitivity to the combination of SGI-1776 and sunitinib. Importantly, the combination significantly reduced tumour burden in two RCC xenograft models compared with single-agent therapy and was very well tolerated. CONCLUSION: These data indicate that targeting PIM kinase signalling is a promising treatment strategy for RCC.

[Prevalence and clinical significance of incidental cardiac findings in non-ECG-gated chest CT scans]. / Prävalenz und klinische Bedeutung inzidenteller Herzbefunde im nicht EKG-getriggerten Thorax-CT.

BACKGROUND: The purpose of this study was to evaluate the prevalence and clinical significance of incidental cardiac findings in non-ECG-gated chest CT. PATIENTS AND METHODS: Non-ECG-gated chest CT examinations of 300 patients were retrospectively analyzed for incidental cardiac findings. Subsequently, these findings were evaluated for their clinical relevance by a cardiologist. RESULTS: A total of 107 out of 300 examined patients had 174 incidental cardiac findings including coronary calcification (90), aortic/mitral valve calcification (42), iatrogenic changes (23), pericardial effusion (6), dilatation of the heart (4), myocardial changes (3), thrombus in the left ventricle (2), constrictive pericarditis (2) and atrial myxoma (1). Of the cardiac findings 51% were described in the written report and in 53 out of the 107 patients the cardiac findings were unknown. Newly detected incidental findings from 8 patients were rated as clinically significant: pericardial effusion (4), constrictive pericarditis (1), thrombus in the left ventricle (1), atrial myxoma (1) and dilatation of the heart (1). CONCLUSION: Incidental cardiac findings are frequent in non-ECG-gated chest CT and may have a high clinical relevance.

Plasma and cerebrospinal fluid pharmacokinetics of MP470 in non-human primates.

PURPOSE: MP470 is a multi-targeted tyrosine kinase inhibitor with potent activity against mutant c-Kit, PDGFRα, Flt3, c-Met and c-Ret that is being evaluated as an anticancer agent. The plasma and cerebrospinal fluid (CSF) pharmacokinetics of MP470 were studied in a non-human primate model that is highly predictive of CSF penetration in humans. METHODS: Oral MP470, 300 mg, was administered to four non-human primates. Serial samples of blood were collected from four animals and CSF samples from three animals for pharmacokinetic studies. Plasma and CSF concentrations were measured using an LC-MS/MS assay. Both model-independent and model-dependent methods were used to analyze the pharmacokinetic data. RESULTS: Following a one-time oral dose of 300 mg, the MP470 plasma area under the curve (AUC) was 1,690 ± 821 nM h (mean ± SD). The half-life of MP470 in the plasma was 11.0 ± 3.4 h. There was no measurable MP470 in the CSF. CONCLUSIONS: Although CSF penetration is minimal, MP470 has demonstrated potent activity against cancer cell lines in vitro and in vivo, and further clinical investigation is warranted.

[Cardiac pathologies incidentally detected with non-gated chest CT]. / Inzidentelle Pathologien des Herzens im Thorax-CT.

Cardiac imaging using electrocardiogram-gated multi-detector computed tomography (MDCT) permits noninvasive diagnosis of congenital and acquired cardiac pathologies and has thus become increasingly important in the last years. Several studies investigated the incidence and relevance of incidental extracardiac structures within the lungs, mediastinum, chest wall, and abdomen with gated coronary CT. This resulted in the general acceptance of the review of extracardiac structures as a routine component of coronary CT interpretation. On the other hand radiologists tend to neglect pericardial and cardiac pathologies in non-gated chest CT, which is primarily performed for the evaluation of the respiratory system or for tumor staging. Since the introduction of multi-detector spiral CT technology, the incidental detection of cardiac and pericardial findings has become possible using non-gated chest CT. This article reviews the imaging appearances and differential diagnostic considerations of incidental cardiac entities that may be encountered in non-gated chest CT.

A theoretical study of substituent effects on allylic ion and ion pair SN2 reactions.

An ab initio study of ionic and ion pair displacement reactions involving allylic systems has been carried out at the RHF/6-31+G* level. The geometries and natural charges show the absence of conjugative stabilization in the ionic transition states, thus differing from traditional explanations. The high reactivity of allyl halides is explained by electrostatic polarization of the double bond. Substituent effects were also studied; in general, electron-withdrawing groups lower the barriers of the ionic S(N)2 reactions but increase the barriers of the ion pair reactions. The allylic reactions are compared with related benzylic systems. Hammett correlations give rho of opposite sign for the ionic and ion pair displacement reactions, in agreement with some experimental results.

Capture of rare cells in suspension with antibody-coated polystyrene beads.

A method for the separation of one cell type present in small number from a predominant mixture of cell types using macroscopic polystyrene beads is demonstrated. An antibody specific to murine leukocytes (CD45) was adsorbed to the surface of the beads. Beads and murine hybridoma B cells were placed in test tubes and periodically inverted at fixed time intervals, causing the beads to settle through the suspension under creeping flow conditions. Capture was dependent upon interception: the captured cells must have traveled along streamlines that brought them to within a cell radius of the bead surface. B cells attached to 99-micrometer beads (maximum shear rate 8.1 s-1) were captured with greater efficiency but in lesser quantity than those attached to 170-micrometer beads (maximum shear rate 13.9 s-1). Cell capture unexpectedly reached a plateau in less than 2 h, a phenomenon that appears to involve changes in both the cells and the beads. Capture of cells was effective out to dilutions of 1:10 000 with purity in the captured population of better than 74%. This method allows for the study of physical parameters important for cell attachment and capture as well as for practical separation of rare cells.

Anti-HLA alloantibody is found in children but does not correlate with a lack of HIV type 1 transmission from infected mothers.

Searching for mechanisms of natural resistance to HIV infection with which to guide HIV vaccine design, we have examined antibody responses to HLA class I antigens in children of HIV-1-infected mothers. Anti-HLA antibodies are known to block HIV infectivity in vitro and can be protective against SIV challenge in macaques immunized with purified class I HLA. It was hypothesized that alloantibody to maternal HLA in children might contribute to the prevention of mother-to-child transmission of HIV-1. In fact, a surprisingly high proportion of the children examined, 22%, were found to have antibody against class I alloantigens. This alloantibody, however, did not correlate with the HIV status of the children and was found in a similar proportion of children of HIV-negative mothers. The HLA specificity of the antibody was not correlated with noninherited maternal HLA alleles and occurred with a higher frequency in older children. This result suggests environmental factors, rather than exposure to maternal cells, are involved in the formation of the alloantibody. The finding that anti-allo-class I HLA antibodies are not associated with a decreased risk of mother-to-child transmission indicates that this humoral immune response is unlikely to be the natural mechanism that accounts for the lack of transmission observed in many births. This result, however, does not preclude the further investigation of cellular alloimmune responses, or the use of alloimmunization as an artificial HIV immunization strategy.

Naturally occurring IgG anti-HLA alloantibody does not correlate with HIV type 1 resistance in Nairobi prostitutes.

In an effort to identify an immunological basis for natural resistance to HIV-1 infection, we have examined serum antibody responses to HLA class I antigens in female prostitutes of the Nairobi Sex Workers Study. Anti-HLA antibodies are known to block HIV infectivity in vitro and can be protective against SIV challenge in macaques immunized with purified class I HLA. Thus, it was postulated that broadly cross-reactive alloantibodies recognizing common HLA alleles in the client population might contribute to the prevention of heterosexual transmission of HIV. In fact, 12% of the women were found to have serum IgG antibodies against class I alloantigens. However, this alloantibody did not correlate with the HIV status of the women and was found in a similar proportion of HIV-positive and HIV-resistant women. The observed levels of alloantibody did not increase with HIV infection in susceptible individuals, suggesting that potential antigenic mimicry between HIV and host HLA class I antigens does not significantly increase levels of anti-class I antibodies. The lack of correlation between serum anti-allo-class I HLA antibodies and the risk of sexual transmission indicates that this humoral immune response is unlikely to be the natural mechanism behind the HIV-resistance phenotype of persistently HIV-seronegative women. This result, however, does not preclude the further investigation of alloimmunization as an artificial HIV immunization strategy.

A review of respiratory syncytial virus infection in infants and children.

By the age of 2, nearly every child becomes infected with the respiratory syncytial virus (RSV), the most common cause of lower respiratory tract infections (RTIs) in infants and children. Yearly epidemics occur from October to May. Most infections are mild, producing nothing more than a cold, and can be managed at home. Some cases, however, are more severe, leading to bronchiolitis, pneumonitis, pneumonia, and even death.

The benefits of in-home pharmacy evaluation for older persons.

OBJECTIVE: To assess the potential benefit of a pharmacist performing in-home medication evaluations on frail older people. DESIGN: Prospective analysis with pre-post comparison. SETTING: A hospital-based home care program at the Sepulveda Veterans Affairs Medical Center. PARTICIPANTS: Male veterans in a home care program who live within 15 miles of the medical center and take three or more prescription medications (N = 20, mean age: 75.1 years). MEASURES: Prescribed medications were documented from the medical records and compared with regimens actually being followed in the home. In addition, the home was inspected, patients were educated, and recommendations were made to the prescribing physicians when necessary. RESULTS: At first visit, patients had a mean of 6.0 prescribed daily medications but were only taking 4.7 of these regularly. Also noted were many potentially unnecessary medications (70% of subjects) and multiple problems with the medication regimen (e.g., incorrect drug frequency or dosage, expired medications, medication omission). Follow-up visit revealed a significant decrease in medication discrepancies and problems (P < or = .05). CONCLUSION: An in-home pharmacy assessment reveals many problems with drug administration not otherwise detected easily. These assessments can lead to potentially useful interventions that can improve medication regimens and compliance. Determination of long-term effects must await controlled trials.

Inhibition of protein synthesis in Krebs 2 ascites cells and cell-free systems by phenylalanine and its effect on leucine and lysine in the amino acid pool.

1. The inhibition of incorporation of (14)C-labelled amino acids into protein of whole cells by phenylalanine has been reproduced in a cell-free system. In both cases only the l-isomer was inhibitory. 2. The effect of phenylalanine on incorporation of [(14)C]leucine and [(14)C]lysine into protein was different in both whole cells and cell-free systems. 3. In whole cells inhibition of incorporation of leucine at 2.5mug./ml. was very rapid, but when the concentration was increased to 100mug./ml. the inhibition was not apparent for about 1hr. The kinetics of inhibition of lysine was the same at both these concentrations and was similar to that found with leucine at 100mug./ml. 4. Neither a lower specific radioactivity of the two amino acids in the pool nor a decrease in their pool size could be consistently related with inhibition of protein synthesis. 5. In the cell-free system l-phenylalanine inhibited the incorporation of leucine but not of lysine. 6. Charging of transfer RNA by leucine was markedly decreased in the presence of phenylalanine, whereas charging of transfer RNA by lysine was not.