PTEN mutational spectra,expression levels,and subcellular localization in microsatellite stable and unstable colorectal cancers

PTEN on 10q23.3 encodes a dual-specificity phosphatase that negatively regulates the phosphoinositol-3-kinase/Akt pathway and mediates cell-cycle arrest and apoptosis. Germline PTEN mutations cause Cowden syndrome and a range of several different hamartoma-tumor syndromes. Hereditary nonpolyposis colon cancer (HNPCC) syndrome is characterized by germline mutations in the mismatch repair (MMR) genes and by microsatellite instability (MSI) in component tumors. Although both colorectal carcinoma and endometrial carcinoma are the most frequent component cancers in HNPCC, only endometrial cancer has been shown to be a minor component of Cowden syndrome. We have demonstrated that somatic inactivation of PTEN is involved in both sporadic endometrial cancers and HNPCC-related endometrial cancers but with different mutational spectra and different relationships to MSI. In the current study, we sought to determine the relationship of PTEN mutation, 10q23 loss of heterozygosity, PTEN expression, and MSI status in colorectal cancers (CRCs). Among 11 HNPCC CRCs, 32 MSI+ sporadic cancers, and 39 MSI- tumors, loss of heterozygosity at 10q23.3 was found in 0%, 8%, and 19%, respectively. Somatic mutations were found in 18% (2 of 11) of the HNPCC CRCs and 13% (4 of 32) of the MSI+ sporadic tumors, but not in MSI- cancers (P = 0.015). All somatic mutations occurred in the two 6(A) coding mononucleotide tracts in PTEN, suggestive of the etiological role of the deficient MMR. Immunohistochemical analysis revealed 31% (14 of 45) of the HNPCC CRCs and 41% (9 of 22) of the MSI+ sporadic tumors with absent or depressed PTEN expression. Approximately 17% (4 of 23) of the MSI- CRCs had decreased PTEN expression, and no MSI- tumor had complete loss of PTEN expression. Among the five HNPCC or MSI+ sporadic CRCs carrying frameshift somatic mutations with immunohistochemistry data, three had lost all PTEN expression, one showed weak PTEN expression levels, and one had mixed tumor cell populations with weak and moderate expression levels. These results suggest that PTEN frameshift mutations in HNPCC and sporadic MSI+ tumors are a consequence of mismatch repair deficiency. Further, hemizygous deletions in MSI- CRCs lead to loss or reduction of PTEN protein levels and contribute to tumor progression. Finally, our data also suggest that epigenetic inactivation of PTEN, including differential subcellular compartmentalization, occurs in CRCs.     

Mechanical heart valve prostheses:: identification and evaluation (erratum)

Mechanical heart value prostheses have been in use since the 1950s. Many prostheses have been used for a while and then discontinued. Today, there are a large number and variety of prostheses in use and an even larger variety that are in place in patients. These may be explanted at any time for a number of reasons. It is essential for the practicing pathologist to be able to identify the prosthesis and be aware of some of its reported complications and modes of failure. This article, and a second one on bioprosthetic heart valves, is designed as a ready reference guide to heart valve prostheses, their important identifying features, their common complications, and modes of failure. It should help in the accurate identification of explanted prosthetic valves and more definitive reports. This accuracy of identification as well as tracking of abnormalities noted will, we hope, permit the identification of new failure modes and the recording of causes of failure of new (or even modified) prosthetic heart valves.     

Polymorphisms in the MAOA, MAOB, and COMT genes and aggressive behavior in schizophrenia.

Some studies have reported associations between COMT and MAO genotypes and aggression, though results have been inconsistent. We examined the relationship between Overt aggression scale (OAS) scores, and both MAOA and MAOB polymorphisms in a well-powered sample of 346 subjects with schizophrenia. We also examined COMT in a Stage II replication sample of 150 individuals, and combined these results with our previously reported (Stage I) findings for COMT. We found no evidence of any associations between OAS ratings and any of the polymorphisms investigated under different genetic models. There was no evidence of epistatic interaction between MAOA and COMT on OAS scores. These results fail to support the theory that functional polymorphisms within the MAOA, MAOB, or COMT genes, as determinants of catecholamine enzymatic activity, are risk factors for aggressive behavior.     

Management of unruptured incidentally found intracranial saccular aneurysms

Neurosurgical Review - Unruptured intracranial saccular aneurysms occur in 3–5% of the general population. As the use of diagnostic medical imaging has steadily increased over the past few...     

Large‐scale bone mineral histomorphometry – report of a simplified technique

Karantzoulis V, Liapi C & Papaggelopoulos P
(2012) Histopathology
Large‐scale bone mineral histomorphometry – report of a simplified technique Aims: The aim of this study was the development of a simplified technique for bone mineral histomorphology on large undecalcified bone samples. Established techniques, such as undecalcified bone thin sectioning, ultrathin grinding, surface‐stained block grinding and micro‐computerized tomography (CT), are expensive, time‐consuming and put very high demands on equipment, safety standards, personnel and laboratory facilities. Methods and results: The method is based on the surface‐stained block‐grinding principle; however, its novelty lies in the selection of user‐friendly, safe and low‐cost materials, equipment and digitization techniques. We describe in detail the relevant steps, as well as many practical tips for their successful implementation: accurate bone cutting in thin sections with a customized arrangement on a commercial bandsaw, defatting with sodium hypochlorite, embedding in epoxy resin blocks at room temperature, silicon carbide paper grinding, von Kossa staining, flatbed scanner digitization and image processing. Conclusion: We believe that the proposed methodology could contribute to the expansion of the study of bone tissue, as it enables the rapid examination of bone specimens on a large scale with minimal laboratory requirements and consumables costs.     

Biochemical screening and PTEN mutation analysis in individuals with autism spectrum disorders and macrocephaly

Unlike some other childhood neurodevelopmental disorders, no diagnostic biochemical marker has been identified in all individuals with an autism spectrum disorder (ASD). This deficit likely results from genetic heterogeneity among the population. Therefore, we evaluated a subset of individuals with ASDs, specifically, individuals with or without macrocephaly in the presence or absence of PTEN mutations. We sought to determine if amino or organic acid markers could be used to identify individuals with ASDs with or without macrocephaly in the presence or absence of PTEN mutations, and to establish the degree of macrocephaly in individuals with ASDs and PTEN mutation. Urine, blood and occipital–frontal circumference (OFC) measurements were collected from 69 individuals meeting DSM-IV-TR criteria. Urine and plasma samples were subjected to amino and organic acid analyses. PTEN was Sanger-sequenced from germline genomic DNA. Germline PTEN mutations were identified in 27% (6/22) of the macrocephalic ASD population. All six PTEN mutation-positive individuals were macrocephalic with average OFC+4.35 standard deviations (SDs) above the mean. No common biochemical abnormalities were identified in macrocephalic ASD individuals with or without PTEN mutations. In contrast, among the collective ASD population, elevation of urine aspartic acid (87% 54/62), plasma taurine (69% 46/67) and reduction of plasma cystine (72% 46/64) were observed. PTEN sequencing should be carried out for all individuals with ASDs and macrocephaly with OFC ≥2SDs above the mean. A proportion of individuals with ASDs may have an underlying disorder in sulfur amino acid metabolism.     

Treatment of calcified coronary artery lesions

Heavily calcified coronary plaques represent a complex lesion subset and a challenge to the interventional cardiologist, as they are often resistant to simple plaque modification with conventional balloon angioplasty. Inadequate plaque modification can lead to stent underdeployment, which itself predisposes to in-stent restenosis and stent thrombosis. Over the years, a number of mechanical devices ranging from modified angioplasty balloons to atherectomy devices have become available in order to tackle such lesions. Here we review these devices concentrating on the evidence behind their use.     

KLLN epigenotype–phenotype associations in Cowden syndrome

Germline KLLN promoter hypermethylation was recently identified as a potential genetic etiology of the cancer predisposition syndrome, Cowden syndrome (CS), when no causal PTEN gene mutation was found. We screened for KLLN promoter methylation in a large prospective series of CS patients and determined the risk of benign and malignant CS features in patients with increased methylation both with and without a PTEN mutation/variant of unknown significance. In all, 1012 CS patients meeting relaxed International Cowden Consortium criteria including 261 PTEN mutation-positive CS patients, 187 PTEN variant-positive CS patients and 564 PTEN mutation-negative CS patients, as well as 111 population controls were assessed for germline KLLN promoter methylation by MassARRAY EpiTYPER analysis. KLLN promoter methylation was analyzed both as a continuous and a dichotomous variable in the calculation of phenotypic risks by stepwise logistic regression and Kaplan–Meier/standardized incidence ratio methods, respectively. Significantly increased KLLN promoter methylation was seen in CS individuals with and without a PTEN mutation/VUS compared with controls (P<0.001). Patients with high KLLN promoter methylation have increased risks of all CS-associated malignancies compared with the general population. Interestingly, KLLN-associated risk of thyroid cancer appears to be gender and PTEN status dependent. KLLN promoter methylation associated with different benign phenotypes dependent on PTEN status. Furthermore, increasing KLLN promoter methylation is associated with a greater phenotype burden in mutation-negative CS patients. Germline promoter hypermethylation of KLLN is associated with particular malignant and benign CS features, which is dependent on the PTEN mutation status.