Artificial Space Weathering to Mimic Solar Wind Enhances the Toxicity of Lunar Dust Simulants in Human Lung Cells

During NASA's Apollo missions, inhalation of dust particles from lunar regolith was identified as a potential occupational hazard for astronauts. These fine particles adhered tightly to spacesuits and were unavoidably brought into the living areas of the spacecraft. Apollo astronauts reported that exposure to the dust caused intense respiratory and ocular irritation. This problem is a potential challenge for the Artemis Program, which aims to return humans to the Moon for extended stays in this decade. Since lunar dust is "weathered" by space radiation, solar wind, and the incessant bombardment of micrometeorites, we investigated whether treatment of lunar regolith simulants to mimic space weathering enhanced their toxicity. Two such simulants were employed in this research, Lunar Mare Simulant-1 (LMS-1), and Lunar Highlands Simulant-1 (LHS-1), which were added to cultures of human lung epithelial cells (A549) to simulate lung exposure to the dusts. In addition to pulverization, previously shown to increase dust toxicity sharply, the simulants were exposed to hydrogen gas at high temperature as a proxy for solar wind exposure. This treatment further increased the toxicity of both simulants, as measured by the disruption of mitochondrial function, and damage to DNA both in mitochondria and in the nucleus. By testing the effects of supplementing the cells with an antioxidant (N-acetylcysteine), we showed that a substantial component of this toxicity arises from free radicals. It remains to be determined to what extent the radicals arise from the dust itself, as opposed to their active generation by inflammatory processes in the treated cells.

Infectious Agents Induce Wnt/β-Catenin Pathway Deregulation in Primary Liver Cancers

Interaction between infectious agents and liver tissue, as well as repeated and extreme biological events beyond adaptive capacities, may result in pathological conditions predisposing people to development of primary liver cancers (PLCs). In adults, PLCs mainly comprise hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA). Various infectious agents in the hepatic microenvironment can destabilize normal liver cell functions by modulating the Wnt/β-catenin pathway components. Among them, hepatotropic viruses B, C, and D are involved in Wnt/β-catenin signaling dysregulation. Other microbial agents, including oncogenic viruses such as Epstein-Barr virus (EBV) and human papilloma virus (HPV), bacteria, e.g., Mycoplasma hyorhinis and Salmonella Typhi, the protozoan parasite Toxoplasma gondii, the fungus Aspergillus flavus, and liver flukes such as Clonorchissinensis or Opisthorchis viverrini, may induce malignant transformation in hepatocytes or in target cells of the biliary tract through aberrant Wnt signaling activation. This review focuses on new insights into infectious agents implicated in the deregulation of Wnt signaling and PLC development. Since the Wnt/β-catenin pathway is a driver of cancer following viral and bacterial infections, molecules inhibiting the complex axis of Wnt signaling could represent novel therapeutic approaches in PLC treatment.

Wingless/It/β-catenin signaling in liver metastasis from colorectal cancer: A focus on biological mechanisms and therapeutic opportunities

The liver is the most common site of metastases in patients with colorectal cancer. Colorectal liver metastases (CRLMs) are the result of molecular mechanisms that involve different cells of the liver microenvironment. The aberrant activation of Wingless/It (Wnt)/β-catenin signals downstream of Wnt ligands initially drives the oncogenic transformation of the colon epithelium, but also the progression of metastatization through the epithelial-mesenchymal transition/mesenchymal-epithelial transition interactions. In liver microenvironment, metastatic cells can also survive and adapt through dormancy, which makes them less susceptible to pro-apoptotic signals and therapies. Treatment of CRLMs is challenging due to its variability and heterogeneity. Advances in surgery and oncology have been made in the last decade and a pivotal role for Wnt/β-catenin pathway has been re-cognized in chemoresistance. At the state of art, there is a lack of clear understanding of why and how this occurs and thus where exactly the opportunities for developing anti-CRLMs therapies may lie. In this review, current knowledge on the involvement of Wnt signaling in the development of CRLMs was considered. In addition, an overview of useful biomarkers with a revision of surgical and non-surgical therapies currently accepted in the clinical practice for colorectal liver metastasis patients were provided.

Targeting Wnt/β-Catenin Pathways in Primary Liver Tumours: From Microenvironment Signaling to Therapeutic Agents

Primary liver cancers (PLCs) are steadily increasing in incidence and mortality in the world. They have a poor prognosis due to their silent nature, late discovery and resistance to common chemotherapy. At present, there are limited treatment alternatives, and the understanding of PLC molecular aspects is essential to develop more efficient drugs and therapeutic surgical and loco-regional strategies. A clear causal link with liver damage, inflammation, and regeneration has been found in the occurrence of PLC over the last few decades. Physiologically, Wingless/It (Wnt)-β-catenin signaling plays a key role in liver development, metabolic zonation and regeneration. Loss of functional homeostasis of this pathway appears to be a major driver of carcinogenesis in the liver parenchyma. In the hepatic microenvironment, molecular deregulations that exceed the Wnt signaling biological capacity can induce tumor initiation and progression. Indeed, somatic mutations are identified in key components of canonical and non-canonical Wnt signaling and in PLCs and precancerous lesions. In this review, the altered functions of Wnt/β-catenin signaling are considered in human PLCs, with emphasis on hepatocellular carcinomas (HCC), cholangiocarcinomas (CCA) and hepatoblastomas (HB). Based on recent literature, we also focused on liver cancerogenesis through Wnt deregulation. An overview of preclinical and clinical studies on approved and experimental drugs, targeting the Wnt/β-catenin cascade in PLCs, is proposed. In addition, the clinical implication of molecule inhibitors that have been shown to possess activity against the Wnt pathway in association with conventional surgical and loco-regional therapies are reviewed.

MUTYH: Not just polyposis

MUTYH is a base excision repair enzyme, it plays a crucial role in the correction of DNA errors from guanine oxidation and may be considered a cell protective factor. In humans it is an adenine DNA glycosylase that removes adenine misincorporated in 7,8-dihydro-8-oxoguanine (8-oxoG) pairs, inducing G:C to T:A transversions. MUTYH functionally cooperates with OGG1 that eliminates 8-oxodG derived from excessive reactive oxygen species production. MUTYH mutations have been linked to MUTYH associated polyposis syndrome (MAP), an autosomal recessive disorder characterized by multiple colorectal adenomas. MAP patients show a greatly increased lifetime risk for gastrointestinal cancers. The cancer risk in mono-allelic carriers associated with one MUTYH mutant allele is controversial and it remains to be clarified whether the altered functions of this protein may have a pathophysiological involvement in other diseases besides familial gastrointestinal diseases. This review evaluates the role of MUTYH, focusing on current studies of human neoplastic and non-neoplastic diseases different to colon polyposis and colorectal cancer. This will provide novel insights into the understanding of the molecular basis underlying MUTYH-related pathogenesis. Furthermore, we describe the association between MUTYH single nucleotide polymorphisms (SNPs) and different cancer and non-cancer diseases. We address the utility to increase our knowledge regarding MUTYH in the light of recent advances in the literature with the aim of a better understanding of the potential for identifying new therapeutic targets. Considering the multiple functions and interactions of MUTYH protein, its involvement in pathologies based on oxidative stress damage could be hypothesized. Although the development of extraintestinal cancer in MUTYH heterozygotes is not completely defined, the risk for malignancies of the duodenum, ovary, and bladder is also increased as well as the onset of benign and malignant endocrine tumors. The presence of MUTYH pathogenic variants is an independent predictor of poor prognosis in sporadic gastric cancer and in salivary gland secretory carcinoma, while its inhibition has been shown to reduce the survival of pancreatic ductal adenocarcinoma cells. Furthermore, some MUTYH SNPs have been associated with lung, hepatocellular and cervical cancer risk. An additional role of MUTYH seems to contribute to the prevention of numerous other disorders with an inflammatory/degenerative basis, including neurological and ocular diseases. Finally, it is interesting to note that MUTYH could be a new therapeutic target and future studies will shed light on its specific functions in the prevention of diseases and in the improvement of the chemo-sensitivity of cancer cells.

Epidrugs in the Immunotherapy of Cutaneous and Uveal Melanoma

Epigenetic modifications can affect numerous mechanisms used by neoplastic cells to evade immune control. In melanoma epigenetic defects, caused by dysregulations in the expression of genome writers, erasers, or readers, play a significant role in the reduced expression of molecules required for efficient immune recognition as well as antigen presentation and processing. Alterations in gene expression were identified in tumor-associated antigens (TAAs), human leukocyte antigen (HLA) complex, co-stimulatory/accessory molecules, antigen processing machinery (APM), and NKG2D ligands that have shown to be silenced or down-regulated in melanoma. In agreement with the inherent reversibility of epigenetic silencing, epigenetic drugs such as inhibitors of DNA methyltransferases (DNMTs), histone deacetylases (HDACs), histone methyltransferase enhancer of Zeste homolog 2 (EZH2), and modifiers of microRNA (miRNA) dysregulation or antagomirs can restore the expression of these molecules, favouring the recognition of cancer cells by immune responses, reducing the resistance to Natural Killer (NK) and cytotoxic T cells (CTL), and enhancing the functions of antigen presenting cells. Moreover, inhibitors of reader proteins seem to preferentially affect the NF-kB-induced activation of pro-inflammatory cytokine genes. At present an increasing interest is shown toward new combined therapeutic approaches employing epidrugs or new molecular inhibitors and in vivo immunotherapies, such as vaccines and adoptive T-cell transfer (ACT). This review summarizes the current understanding of the role of epidrugs in the modulation of molecules involved in the melanoma immune response and focuses on their future clinical use in new therapeutic combinations for melanoma treatment.

DSS1 promoter hypomethylation and overexpression predict poor prognosis in melanoma and squamous cell carcinoma patients

Previous studies have found a link between high expression levels of the Deleted in Split hand/Split foot 1 (DSS1) gene and cancer progression. The aim of this study was to examine whether overexpression of DSS1 is a feature of melanoma and squamous cell carcinoma (SCC) and if any epigenetic modifications are involved. Evaluation of DSS1 expression profile indicated that the gene is overexpressed in 112 of 130 cutaneous melanomas (86.1%), 41 of 64 uveal melanomas (64.1%), 67 of 82 mucosal melanomas (81.7%), and 61 of 75 SCC samples (81.3%), relative to normal skin. An inverse correlation between DSS1 expression and methylation status of the promoter was found. In vitro studies showed that treatment of DSS1-methylated melanoma and SCC cells with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine significantly increased DSS1 expression at mRNA and protein levels. Interestingly, a significant association between high DSS1 expression levels and some clinicopathological variables, such as metastasis, ulceration, and reduced overall/disease-free survival was observed. In summary, these data suggest that the extent of promoter methylation plays a role in modulating DSS1 gene expression and highlight that promoter hypomethylation is a frequent event in melanoma and SCC closely linked to poor prognosis.

DNA methylation-induced E-cadherin silencing is correlated with the clinicopathological features of melanoma

E-cadherin, a calcium-dependent cell-cell adhesion molecule, has an important role in epithelial cell function, maintenance of tissue architecture and cancer suppression. Loss of E-cadherin promotes tumor metastatic dissemination and predicts poor prognosis. The present study investigated the clinicopathological significance of E-cadherin expression in cutaneous, mucosal and uveal melanoma related to epigenetic mechanisms that may contribute to E-cadherin silencing. E-cadherin expression was reduced in 55/130 cutaneous (42.3%), 49/82 mucosal (59.7%) and 36/64 uveal (56.2%) melanoma samples as compared to normal skin controls and was inversely associated with promoter methylation. Of the 10 different CpG sites studied (nt 863, 865, 873, 879, 887, 892, 901, 918, 920 and 940), two sites (nt 892 and 940) were 90-100% methylated in all the melanoma specimens examined and the other ones were partially methylated (range, 53-86%). In contrast, the methylation rate of the E-cadherin gene was low in normal tissues (range, 5-24%). In all the three types of melanoma studied, a significant correlation was found between reduced levels of E-cadherin and reduced survival, high mitotic index and metastasis, accounting for the predilection of lymph nodal localization. In cutaneous and mucosal melanoma, low E-cadherin expression was positively correlated also with head/neck localization and ulceration. A high frequency of reduced E-cadherin levels occurred in choroid melanomas. In vitro experiments showed that E-cadherin transcription was restored following 5-aza-2'-deoxycytidine (5-aza-dC) treatment or DNMT1 silencing and was negatively correlated with the invasive potential of melanoma cells. The significant relationship between E-cadherin silencing and several poor prognostic factors indicates that this adhesion molecule may play an important role in melanomagenesis. Therefore, the inverse association of E-cadherin expression with promoter methylation raises the intriguing possibility that reactivation of E-cadherin expression through promoter demethylation may represent a potential therapeutic strategy for the treatment of melanoma.

Involvement of epimutations in meningioma

Epimutations are heritable and reversible cell markers, which can influence cell function going beyond the effects of DNA mutations. They result from multiple and coordinated mechanisms able to modulate gene expression. Regarding the significance of epigenetics in meningioma, few and somehow contradictory results are available, although promising information has been obtained. Here we highlight the most recent advances about the impact of DNA methylation, histone modifications, and microRNA regulation on meningioma development as well as the interplay between genetic and epigenetic alterations. Data indicate that epigenetics can help to identify novel candidate genes for the management and treatment of meningioma.

Integrative analysis of hereditary nonpolyposis colorectal cancer: the contribution of allele-specific expression and other assays to diagnostic algorithms

The identification of germline variants predisposing to hereditary nonpolyposis colorectal cancer (HNPCC) is crucial for clinical management of carriers, but several probands remain negative for such variants or bear variants of uncertain significance (VUS). Here we describe the results of integrative molecular analyses in 132 HNPCC patients providing evidences for improved genetic testing of HNPCC with traditional or next generation methods. Patients were screened for: germline allele-specific expression (ASE), nucleotide variants, rearrangements and promoter methylation of mismatch repair (MMR) genes; germline EPCAM rearrangements; tumor microsatellite instability (MSI) and immunohistochemical (IHC) MMR protein expression. Probands negative for pathogenic variants of MMR genes were screened for germline APC and MUTYH sequence variants. Most germline defects identified were sequence variants and rearrangements of MMR genes. Remarkably, altered germline ASE of MMR genes was detected in 8/22 (36.5%) probands analyzed, including 3 cases negative at other screenings. Moreover, ASE provided evidence for the pathogenic role and guided the characterization of a VUS shared by 2 additional probands. No germline MMR gene promoter methylation was observed and only one EPCAM rearrangement was detected. In several cases, tumor IHC and MSI diverged from germline screening results. Notably, APC or biallelic MUTYH germline defects were identified in 2/19 probands negative for pathogenic variants of MMR genes. Our results show that ASE complements gDNA-based analyses in the identification of MMR defects and in the characterization of VUS affecting gene expression, increasing the number of germline alterations detected. An appreciable fraction of probands negative for MMR gene variants harbors APC or MUTYH variants. These results indicate that germline ASE analysis and screening for APC and MUTYH defects should be included in HNPCC diagnostic algorithms.

Nonfluorescent denaturing HPLC-based primer-extension method for allele-specific expression: application to analysis of mismatch repair genes

BACKGROUND

Altered germline expression of genes may represent a powerful marker of genetic or epigenetic predisposition to cancer or other diseases.

METHODS

We developed and validated a method of nonfluorescent primer extension that uses a single dideoxynucleotide and denaturing HPLC (DHPLC) to analyze the relative allele expression. We devised 5 independent assays for measuring allele-specific expression (ASE) to exploit different markers of mismatch repair genes MLH1 [mutL homolog 1, colon cancer, nonpolyposis type 2 (E. coli)] and MSH2 [mutS homolog 2, colon cancer, nonpolyposis type 1 (E. coli)]. We initially confirmed method reproducibility with genomic DNA (gDNA) from individuals heterozygous for a frequent single-nucleotide polymorphism in the MLH1 gene. After this preliminary validation with gDNA, we confirmed assay reproducibility with cDNA templates from control individuals. Relative allele expression was estimated by comparing the heights of the peaks corresponding to the 2 alleles. Results obtained with gDNA templates were used to normalize cDNA results.

RESULTS

With these DHPLC-based primer-extension assays, we detected and confirmed a 5-fold imbalance in MLH1 allele expression in a mutation-negative patient with hereditary nonpolyposis colorectal cancer and in another patient with a modest degree of imbalance in MLH1 expression. Among control individuals, the relative expression of MLH1 alleles displayed a narrow range of variation.

CONCLUSIONS

Independent DHPLC-based primer-extension assays for measuring and confirming ASE can be developed for different sequence variants of interest. This DHPLC application provides a cost-effective method for detecting ASE in cases for which conventional screening fails to detect pathogenic mutations in candidate genes and may be applicable for confirming ASE revealed by other methods, such as those used for transcriptome-wide analyses. .

Gastric adenomas: relationship between clinicopathological findings, Helicobacter pylori infection, APC mutations and COX-2 expression

Gastric adenomas are rare neoplastic growths characterized by localized polypoid proliferations of dysplastic epithelium that tend to progress to infiltrating adenocarcinoma. Therefore, the identification of molecular markers that could reliably recognize adenomas at risk of progression is advocated in the clinical management. In this study we investigated, in a series of gastric adenoma specimens from an area at high risk of gastric cancer, the relationship between clinicopathological characteristics of adenoma and Helicobacter pylori infection, APC mutational status, and COX-2 and the down-stream enzyme mPGES1 expression. Helicobacter pylori infection, detected in 24%, and 33% by histology and PCR analyses, respectively, did not show any relationship with growth pattern, localization, size, dysplasia grade and presence of synchronous cancer. Pathogenetic mutations of MCR region (codons 1269-1589) of the APC gene were detected only in one case corresponding to a single, small size, low grade, H. pylori-negative adenoma. The expression of COX-2 largely matched that of mPGES(1). Both were overexpressed in 79% of cases showing a relationship with high-grade dysplasia, size >10 mm and presence of a synchronous carcinoma. In conclusion, COX-2 may play a key role in the development and progression of gastric adenoma and could be an attractive target in the management of gastric adenoma at major risk of cancer development.

Patterns of K-ras mutation in colorectal carcinomas from Iran and Italy (a Gruppo Oncologico dell'Italia Meridionale study): influence of microsatellite instability status and country of origin

BACKGROUND

K-ras mutations are a key step in colorectal cancer progression. Such mutations have been widely studied in case series from Western countries but there are few data on the rate and spectrum of mutations in tumors from countries where the epidemiological features of the disease are different.

PATIENTS AND METHODS

Tumor samples from 182 Iranian colorectal cancer patients (170 sporadic cases and 12 HNPCC cases) were screened for K-ras mutations at codons 12, 13 and 61 by sequencing analysis. The cases were also characterized for microsatellite instability at mononucleotide repeats by PCR and fragment analysis, and classified according to microsatellite instability status. The frequency and the spectrum of K-ras mutations were compared with those observed in a series of colorectal cancer patients from Italy.

RESULTS

K-ras mutations were observed in 68/182 (37.4%) cases. Mutation frequencies were similar in HNPCC-associated, sporadic MSI-H and sporadic microsatellite-stable (MSS) tumors. However, the G13D substitution was more frequent in HNPCC (3/4, 75%) and sporadic MSI-H (7/11, 63.6%) tumors compared to sporadic MSS tumors (11/53, 20.4%) (P <0.01). Comparison of mutations in the two series from Iran and Italy showed a significantly higher frequency of G13D among Italian patients.

CONCLUSIONS

While the frequency of K-ras mutations could be similar, the mutational spectrum could be differentially influenced by genetic and environmental factors.

Sporadic childhood hepatoblastomas show activation of beta-catenin, mismatch repair defects and p53 mutations

Hepatoblastoma, a rare embryonic tumor that may arise sporadically or in the context of hereditary syndromes (familial adenomatous polyposis and Beckwith-Wiedemann's) is the most frequent liver cancer of childhood. Deregulation of the APC/beta-catenin pathway occurs in a consistent fraction of hepatoblastomas, with mutations in the APC and beta-catenin genes implicated in familial adenomatous polyposis-associated and sporadic hepatoblastomas, respectively. Alterations in other cancer-related molecular pathways have not been reported. We investigated a series of 21 sporadic paraffin-embedded hepatoblastoma cases for mutations in the p53 (exons 5-8) and beta-catenin (exon 3) genes, loss of heterozygosity at APC, microsatellite instability and immunohistochemical expression of beta-catenin and of the two main mismatch repair proteins, MLH1 and MSH2. No loss of heterozygosity at APC was detected. We found mutations in beta-catenin and p53 in 4/21 (19%) and 5/21 (24%) cases respectively, beta-catenin protein accumulation in 14/21 cases (67%), microsatellite instability in 17/21 cases (81%), of which eight resulted positive for high-level of microsatellite instability (in four cases associated with loss of MLH1/MSH2 immunostaining). No correlations between involved molecular pathway(s) and hepatoblastoma histotype(s) emerged. This study confirms that beta-catenin deregulation is involved in sporadic hepatoblastoma and also suggests that mismatch repair defects and p53 mutations contribute to this rare liver cancer. Sporadic hepatoblastoma appears to be molecularly and phenotypically heterogeneous and may reflect different pathways of liver carcinogenesis.

Combined use of MLPA and nonfluorescent multiplex PCR analysis by high performance liquid chromatography for the detection of genomic rearrangements

Large genomic rearrangements are recognized as playing a pathogenic role in an increasing number of human genetic diseases. It is important to develop efficient methods for the routine detection and confirmation of these germline defects. Multiplex ligation-dependent probe amplification (MLPA) is considered an early step for molecular diagnosis of several genetic disorders. However, artifacts might hamper the interpretation of MLPA analysis, especially when rearrangements involve a single exon. Therefore, rearrangements must be verified by two independent methods. In this study, we developed nonfluorescent multiplex-PCR coupled to high-performance liquid chromatography (NFMP-HPLC) and analyzed whether the use of this method combined with MLPA could be helpful in the detection and confirmation of gross MSH2 and MLH1 genomic rearrangements. A total of nine nonfluorescent multiplex-PCRs were developed to analyze the 16 MSH2 and 19 MLH1 exons. Reliable multiplex amplifications and nonfluorescent peak quantitation were obtained with a limited number of cycles (< or = 25) using a denaturing HPLC (DHPLC) instrument under nondenaturing conditions. The results obtained by NFMP-HPLC were highly reproducible. The combined use of MLPA and NFMP-HPLC identified and independently confirmed putative MLH1 and MSH2 deletions in eight out of 50 unrelated patients with hereditary nonpolyposis colorectal cancer (HNPCC). In five cases, the deletions affected a single exon and in three cases multiple contiguous exons. These results were in agreement with breakpoint and complementary DNA (cDNA) analyses. Considering that MLPA and NFMP-HPLC are unlikely to be affected by the same artifacts, their combined use could also provide a robust and cost-effective strategy for routine screening and confirmation of putative rearrangements in other genes, especially when a single exon is involved or a precise characterization of breakpoints is not achieved.

Mutations of APC and MYH in unrelated Italian patients with adenomatous polyposis coli

The analysis of APC and MYH mutations in adenomatous polyposis coli patients should provide clues about the genetic heterogeneity of the syndrome in human populations. The entire coding region and intron-exon borders of the APC and MYH genes were analyzed in 60 unrelated Italian adenomatous polyposis coli patients. APC analysis revealed 26 point mutations leading to premature termination, one missense variant and one deletion spanning the entire coding region in 32 unrelated patients. Novel truncating point mutations included c.1176_1177insT (p.His393_PhefsX396), c.1354_1355del (p.Val452_SerfsX458), c.2684C>A (p.Ser895X), c.2711_2712del (p.Arg904_LysfsX910), c.2758_2759del (p.Asp920_CysfsX922), c.4192_4193del (p.Ser1398_SerfsX1407), c.4717G>T (p.Glu1573X) and a novel cryptic APC exon 6 splice site. MYH analysis revealed nine different germline variants in nine patients, of whom five were homozygotes or compound heterozygotes. The mutations included 4 novel MYH missense variants (c.692G>A, p.Arg231His; c.778C>T, p.Arg260Trp; c.1121T>C, p.Leu374Pro; and c.1234C>T, p.Arg412Cys) affecting conserved amino acid residues in the ENDO3c or NUDIX domains of the protein and one novel synonymous change (c.672C>T, p.Asn224Asn). Genotype-phenotype correlations were found in carriers of APC mutations but not in carriers of biallelic MYH mutations, except for a negative correlation with low number of polyps. A distinctive characteristic of patients negative for APC and MYH mutations was a significantly (p<0.0001) older age at diagnosis compared to patients with APC mutations. Moreover, the proportion of cases with an attenuated polyposis phenotype was higher (p = 0.0008) among patients negative for APC and MYH mutations than among carriers of APC or biallelic MYH mutations.

Mutations in the p53 and Ki-ras genes, microsatellite instability and site of tumor origin in colorectal cancer

Using PCR-SSCP screening and direct sequencing we analyzed a series of 28 colorectal carcinomas for mutations in p53 (exons 5-8) and Ki-ras (codons 12, 13 and 61), and for micro-satellite instability (MSI) at BAT25 and BAT26, supplementing data with the analysis of the IARC colorectal cancer p53 mutation database. Mutations were correlated with the site of tumor origin (proximal or distal to the splenic flexure). We identified 19 mutations in p53, 9 in Ki-ras, and 4 MSI-positive cases in a total of 20 tumors. Only 6/20 cases (30%) carried mutations in both p53 and Ki-ras. Mutations in p53 were detected at similar frequencies in proximal and distal tumors, while IARC data pointed to a strong association of p53 mutations with distal cancers. Ki-ras mutations were more frequent in proximal tumors, and MSI occurred at similar frequencies in proximal and distal tumors and was associated with mutations in p53 or Ki-ras. The p53 mutations detected in the series analyzed, as well as those retrieved from the IARC database, were predominantly transitions, with no preferential sequence localization or nucleotide position. Ki-ras mutations were predominantly transversions in position 2 at codon 12. MSI-H occurred at similar frequencies in proximal and distal tumors and was associated with either p53 or Ki-ras mutations. Overall these data suggest that distinct mutagenic factors target p53 and Ki-ras in colorectal epithelium irrespective of MSI-H status.

X-ray Absorption Spectroscopy of Liquid Methanol Microjets: Bulk Electronic Structure and Hydrogen Bonding Network

We have measured the X-ray absorption (XA) spectrum of liquid (298 K) methanol at the oxygen and carbon K edges. The 4a(1) orbital at the O K edge exhibits a pronounced sensitivity to the formation of intermolecular hydrogen bonds, with significant differences observed between the vapor and bulk spectra, whereas the C K edge reveals only subtle corresponding spectral changes. Comparison with DFT computed spectra of model methanol clusters indicates that the bulk liquid comprises long chains (n > 6) and rings of hydrogen-bonded monomers.

Comparison of drug substance impurity profiles generated with extended length columns during packed-column SFC

The current study assesses the effect of extending column length during gradient packed column sub/supercritical fluid chromatography (PCSFC) experiments on the detection of known and unknown impurities in a drug substance sample. Quantitative drug substance impurity profiles were generated and compared using multiple column PCSFC and HPLC conditions. Also, chromatographic figures of merit were estimated and compared for components of a standard mixture during PCSFC experiments, which used one column, four columns, and six columns in series.

Aspects of column fabrication for packed capillary electrochromatography

Various parameters have been evaluated to develop a process for optimization of column manufacture for packed capillary electrochromatography (CEC). Spherisorb ODS-1 was packed into 75 microm I.D. capillaries to establish a standard set of packing conditions to afford high-performance columns free of voids. Numerous silica-based packing materials including porous and non-porous reversed-phase and ion-exchange phases were employed to evaluate the applicability of the standard conditions. Success of column manufacture and performance demonstrate a relationship to the colligative properties of the packing materials under the applied conditions. Frequently encountered difficulties arising from inadequate column conditioning and void formation in the packed bed are identified and discussed.

Evaluation of 1.5 microM reversed phase nonporous silica in packed capillary electrochromatography and application in pharmaceutical analysis

Reversed-phase nonporous silica (RP-NPS) of 1.5 microm dp is employed to demonstrate rapid and efficient separations in packed capillary electrochromatography (CEC). Two methods for packing capillaries and two techniques to manufacture frits used to hold the packing in place are evaluated for their effect upon separation performance using polyaromatic hydrocarbons (PAHs) and polar neutral pharmaceutical compounds. Attention is given to conditioning of the packed capillaries for high efficiency separations without necessity for sodium dodecyl sulfate (SDS). Separation conditions for the nonporous materials were modified from those previously determined on porous reversed-phase silica. Feasibility for method development and validation of a parent pharmaceutical compound and related impurities in the range of 0.1-120% of a 5 mg/mL concentration was assessed and reported. An approach to improving detection sensitivity through use of large-bore capillaries is briefly discussed.

Method development in pharmaceutical analysis employing capillary electrochromatography

Capillary electrochromatography (CEC) has been employed to explore method development for a series of structurally related polar neutral compounds of pharmaceutical relevance. Capillaries with dimensions of 75 microm ID x 25 cm length (34.5 cm total) were packed with Spherisorb ODS-1, Hypersil phenyl, and Hypersil MOS (all 3 microm particles) and were compared in the reversed-phase mode in order to determine which phase provided the best initial performance and thus serve as the phase of choice for additional method development experiments. The various separation parameters examined for their effect on efficiency, k', resolution, and linear velocity included percent and type of organic modifier, buffer concentration, voltage, and temperature. All separations were conducted with an acidic mobile phase (aqueous mobile phase component, pH 3.0). The separation efficiencies obtained were on the order of 200,000-260,000 plates/m, which equates to reduced plate heights of 1.22 for columns packed with Spherisorb ODS-1. Repeatable column-to-column separation performance was demonstrated.

Comparison of measures of visual acuity in infants: Teller acuity cards and sweep visual evoked potentials

PURPOSE

This study compares the development of acuity in the same infants during one testing session using Teller acuity cards (TAC) and sweep visual evoked potentials (sVEP). We asked whether different testing methods in two centers would produce different developmental time courses.

METHODS

Forty-eight infants were tested in two centers. The standard procedure for TAC was used. For sVEP acuity, the amplitude response curve derived from time-locked cortical activity was used to extrapolate to zero response, giving an acuity estimate for each infant.

RESULTS

sVEP acuity was generally higher than TAC acuity. The rate of development was steeper for TAC than sVEP acuity with TAC starting at a much lower level. The ratio of sVEP to TAC acuity decreased exponentially with age reaching an asymptote of about 1.44 at 6 months.

CONCLUSIONS

Results were indistinguishable between centers suggesting that comparison of acuity measures obtained using variations of these methods across centers is possible.

Ion-pairing high-performance liquid chromatographic method for the determination of 5-aminosalicylic acid and related impurities in bulk chemical

An ion-pairing high-performance liquid chromatographic method has been developed for the determination of 5-aminosalicylic acid (5-ASA) bulk chemical in the presence of thirteen potential synthetic process impurities. In addition, the method is suitable for the determination of the in process intermediate, 5-nitrosalicylic acid. A selective method was achieved on a Hypersil-BDS reversed-phase column using 1-heptanesulfonic acid sodium salt as the ion-pairing reagent in a 0.08 M sodium phosphate buffer (pH 2) containing 0.005 M 1-heptanesulfonic acid sodium salt and 0.07 M sodium chloride-methanol-tetrahydrofuran (85:11:4, v/v/v) isocratic mobile phase. The method was validated using a multi-day, intra-laboratory protocol. The validation addressed linearity, accuracy, precision, sensitivity, and ruggedness of the method. The validated method characterizes the purity of 5-ASA bulk chemical.

Mechanism of misoprostol stabilization in hydroxypropyl methylcellulose

The stability of misoprostol oil is significantly improved in a hydroxypropyl methylcellulose (HPMC) dispersion (1:100). In order to understand the enhanced stability of misoprostol oil in HPMC, the physical state of misoprostol oil in HPMC films was investigated using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and transmission IR (TIR). Further, to determine the effect of polymer structure and the mobility of both water and misoprostol on misoprostol stability, the rate of misoprostol degradation was investigated in the misoprostol/HPMC dispersion (1:100) at 55 degrees C. The water sorption isotherm of the dispersion at 55 degrees C was determined, at seven different relative humidities, ranging from zero to 81%. The DSC and DMA measurements indicated that misoprostol oil, up to 29% in dry weight, is molecularly dispersed in the glassy HPMC. The TIR studies showed no evidence of complexation between misoprostol and HPMC. Stability studies of the misoprostol/HPMC (1:100) dispersion indicated that the first-order rate constants for misoprostol degradation increased in a concave-up fashion as the water content of the dispersion increased. Below two percent water content, the rate of misoprostol degradation was found to be minimal. Overall, it is suggested that misoprostol is stabilized in the dispersion by being molecularly dispersed in HPMC. Further, the glassy state of HPMC should reduce the mobility of misoprostol and water, leading to a minimal rate of degradation for misoprostol at low moisture levels.

Stabilization of misoprostol with hydroxypropyl methylcellulose (HPMC) against degradation by water

The stability of misoprostol oil is significantly improved in a hydroxypropyl methylcellulose (HPMC) dispersion (1:100). In order to assess the effect of water on misoprostol stability, the rate of misoprostol degradation was investigated in the misoprostol/HPMC dispersion at 55 degrees C, along with the water sorption isotherm, under seven different relative humidity (RH) conditions ranging from 0 to 81%. The results indicated that the first-order rate constants of misoprostol degradation increased in a concave-up fashion as the water content of the dispersion increased. Below 30% relative humidity (approximately 2% water), the first-order rate constants of misoprostol degradation were found to be minimum. The results of the stability study were interpreted in terms of the changing structure of HPMC as it related to the mobility of water and misoprostol within the HPMC dispersion.

Use of cerebellar cGMP in the measurement and characterization of the diazepam/ethanol interaction

The characterization and measurement of the benzodiazepine and ethanol interaction has been of major interest for many years. Various pharmacological and biochemical studies have been employed to investigate this interaction, which is believed to occur predominantly in the CNS, but localization of one particular brain area has not been investigated. This research employed the rat cerebellum as a site to study the diazepam/ethanol interaction. The measurement of cerebellar ethanol and diazepam, by gas chromatography, demonstrated an enhancement of diazepam levels by ethanol. Ethanol and diazepam, alone and in combination, displayed a significant depression of cerebellar 3',5'-Guanosine Cyclic Monophosphate (cGMP). The depression seen by the combination was significantly greater than the simple algebraic sum, but insignificantly different from the corrected algebraic sum. The double reciprocal plot of the data demonstrated a common ordinate intercept for the diazepam line and the diazepam/ethanol (2 g/kg) line, thus indicating a competitive mechanism of action.