Long-term function after restorative proctocolectomy

PURPOSE

Early functional outcome after restorative proctocolectomy and formation of an ileoanal pouch is known to be good, but there are minimal data on the long-term function of the pouch. The aim of this study was to look at the long-term functional outcome in patients who had undergone restorative proctocolectomy and formation of an ileoanal pouch.

METHODS

A total of 151 consecutive patients (96 males, 55 females) who underwent ileoanal pouch surgery between April 1983 and May 1993 were identified. Functional outcomes from the previous 12 months were appraised by a standardized questionnaire.

RESULTS

The median age at surgery was 31 years (range, 6-63 years), with a median follow-up of 142 months (range, 100-221 months). Eighteen patients have had their pouches excised, with another patient being defunctioned. Therefore 19 patients (13 percent) had suffered pouch failure. Altogether, 115 patients were available for follow-up, and 98 patients (85 percent) returned questionnaires. The median pouch-emptying frequency was five times (range, 1-17) during the day and one time (range, 0-6) at night. A total of 74 percent of patients had perfect continence during the day. Most of the patients had no life-style restrictions related to the pouch, and 98 percent of patients would recommend a pouch to others.

CONCLUSIONS

Long-term functional outcome after ileoanal pouch surgery is good in most patients. For patients requiring proctocolectomy, ileoanal pouch surgery can now be recommended as an excellent long-term option.

Purification of anthrax edema factor from Escherichia coli and identification of residues required for binding to anthrax protective antigen

The structural gene for anthrax edema factor (EF) was expressed in Escherichia coli under the control of a powerful T5 promoter to yield the 89-kDa recombinant protein that reacted with anti-EF antibodies. Recombinant EF was purified to homogeneity by a two-step procedure involving metal chelate affinity chromatography and cation-exchange chromatography. From 1 liter of culture, 2.5 mg of biologically active EF was easily purified. This is the first report of purification of anthrax EF from E. coli. EF purified from E. coli was biologically and functionally as active as its Bacillus anthracis counterpart. The recombinant protein could compete with lethal factor for binding to protective antigen. Sequence analysis revealed a stretch of seven amino acids, Val Tyr Tyr Glu Ile Gly Lys, present both in EF (residues 136 to 142) and lethal factor (residues 147 to 153). To investigate the role of these seven residues in binding to protective antigen, the residues were individually mutated to alanine in EF. Mutations in residues Tyr137, Tyr138, Ile140, and Lys142 of EF specifically blocked its interaction with anthrax protective antigen. The adenylate cyclase activity of the mutants remained unaffected. The results suggested that residues Tyr137, Tyr138, Ile140, and Lys142 are required for binding of EF to anthrax protective antigen, which facilitates its entry into susceptible cells.

Hydrophobic residues Phe552, Phe554, Ile562, Leu566, and Ile574 are required for oligomerization of anthrax protective antigen

Anthrax protective antigen (PA) plays a central role in facilitating the entry of active toxin components, namely, lethal factor and edema factor, into the cells. PA is also the main immunogen of both human and veterinary vaccine against anthrax. During host cell intoxication, protective antigen binds to the receptors on cell surface, gets proteolytically activated, oligomerizes to form a heptamer and binds to lethal factor or edema factor. The complex, formed by binding of lethal factor or edema factor to oligomerized PA, is internalized by receptor-mediated endocytosis. Acidification of the endosome results in the insertion of the heptamer into the membrane, thereby forming a pore through which lethal factor or edema factor can translocate into the cytosol. In this study we have identified hydrophobic residues, Phe552, Phe554, Ile562, Leu566, and Ile574, which are required for oligomerization of anthrax protective antigen. Mutation of these conserved residues to alanine impaired the oligomerization of protective antigen. Consequently, these mutants became nontoxic in combination with lethal factor and edema factor. Therapeutic importance of these mutants and their potential as vaccine candidates is discussed.

Rapid purification of recombinant anthrax-protective antigen under nondenaturing conditions

Anthrax-protective antigen is the central moiety of the anthrax toxin complex that mediates the entry of the other two toxin components, lethal factor and edema factor into the cells. It is also the main immunogen of the cell-free vaccine against anthrax. However, in addition to PA, the vaccine contains trace amounts of other culture-derived proteins that contribute to the side effects of the vaccine like pain, edema, erythrema, etc. Thus there is a need to develop high-resolution purification methods to purify PA to homogeneity. In this study we have presented a purification strategy for rapid purification of recombinant protective antigen under nondenaturing conditions, which ensures that not only biological activity but also the conformational integrity of immunological epitopes is well-preserved. The protein was purified to homogeneity in a two-step purification procedure that takes just 6 h for completion. Three milligrams of recombinant protective antigen obtained from 1-liter culture was comparable to B. anthracis protective antigen in terms of functional and biological activity. Moreover, the immunogenicity elicited by the purified protein in mice was also studied. The studies reported here are part of continuing research that aims to provide a safe and efficacious alternative to the current vaccine against anthrax.

Accelerated age-related CpG island methylation in ulcerative colitis

CpG island hypermethylation is a mechanism of gene silencing that can be usurped by neoplastic cells to inactivate undesirable genes. In the colon, hypermethylation often starts in normal mucosa as a function of age and is markedly increased in cancer. To test the hypothesis that subjects at increased risk of colon cancer have higher levels of methylation in their nonneoplastic mucosa, we studied methylation patterns of five genes in the normal and dysplastic mucosa of patients with ulcerative colitis (UC), a condition associated with a marked increased risk of colon cancer. One gene (Mlh1) was unmethylated in all tissues examined. All four remaining genes had low but detectable levels of methylation in the epithelium of UC patients without evidence of dysplasia, and this methylation was not different from non-UC controls. By contrast, all four genes were highly methylated in dysplastic epithelium from high-grade dysplasia (HGD)/cancer patients with UC; methylation in HGD versus controls averaged 40.0% versus 7.4% (P = 0.00003) for ER, 44.0% versus 3.0% (P < 0.00003) for MYOD, 9.4% versus 2.4% (P = 0.03) for p16 exon 1, and 57.5% versus 30.6% (P = 0.01) for CSPG2. Importantly, three of the four genes were also highly methylated in the normal appearing (nondysplastic) epithelium from these same HGD/cancer patients, indicating that methylation precedes dysplasia and is widespread in these patients. Compared with controls, methylation averaged 20.1% versus 7.2% (P = 0.07) for ER, 18.4% versus 3.0% (P < 0.008) for MYOD, and 7.9% versus 2.4% (P = 0.007) for p16 exon 1. These results are consistent with the hypothesis that age-related methylation marks (and may lead to) the field defect that reflects acquired predisposition to colorectal neoplasia. Furthermore, the data suggest that chronic inflammation is associated with high levels of methylation, perhaps as a result of increased cell turnover, and that UC can be viewed as resulting in premature aging of colorectal epithelial cells.

Organic catatonia: a review

Catatonia is a clinical syndrome associated with a wide variety of psychiatric, medical and neurological disorders. Despite several reports in the literature of a wide range of medical and neurological diseases causing catatonia, there has been a tendency to consider catatonia as purely psychiatric disorder. The review attempts to look at the concept of organic catatonia from a historical viewpoint, including its place in the psychiatric classification, discusses the various etiological causes of organic catatonia, and them goes through some important management issues in organic catatonia. The review suggests that organic catatonic disorder must be first considered in every patient with catatonic signs, particularly in a patient with new onset catatonia.

Aging, methylation and cancer

Alterations in methylation are widespread in cancers. DNA methylation of promoter-associated CpG islands is an alternate mechanism to mutation in silencing gene function, and affects tumor-suppressor genes such as p16 and RBI, growth and differentiation controlling genes such as ER and many others. Evidence is now accumulating that some of these methylation changes may initiate in subpopulations of normal cells as a function of age and progressively increase during carcinogenesis. Age-related methylation appears to be widespread and is one of the earliest changes marking the risk for neoplasia. In colon cancer, we have shown a pattern of age-related methylation for several genes, including ER, IGF2, N33 and MyoD, which progresses to full methylation in adenomas and neoplasms. Hypermethylation of these genes is associated with gene silencing. Age-related methylation involves at least 50% of the genes which are hypermethylated in colon cancer, and we propose that such age-related methylation may partly account for the fact that most cancers occur as a function of old age. Age-related methylation, then, may be a fundamental mark of the field defect in patients with neoplasia. The causes of age-related methylation are still unknown at this point, but evidence points to an interplay between local predisposing factors in DNA (methylation centers), levels of gene expression and environmental exposure. The concept that age-related methylation is a predisposing factor for neoplasia implies that it may serve as a diagnostic risk marker in cancer, and as a novel target for chemoprevention. Studies in animal models support this hypothesis and should lead to novel approaches to risk-assessment and chemoprevention in humans.

Distinct genetic profiles in colorectal tumors with or without the CpG island methylator phenotype

Colorectal cancers (CRCs) are characterized by multiple genetic (mutations) and epigenetic (CpG island methylation) alterations, but it is not known whether these evolve independently through stochastic processes. We have recently described a novel pathway termed CpG island methylator phenotype (CIMP) in CRC, which is characterized by the simultaneous methylation of multiple CpG islands, including several known genes, such as p16, hMLH1, and THBS1. We have now studied mutations in K-RAS, p53, DPC4, and TGFbetaRII in a panel of colorectal tumors with or without CIMP. We find that CIMP defines two groups of tumors with significantly different genetic lesions: frequent K-RAS mutations were found in CIMP(+) CRCs (28/41, 68%) compared with CIMP(-) cases (14/47, 30%, P = 0.0005). By contrast, p53 mutations were found in 24% (10/41) of CIMP(+) CRCs vs. 60% (30/46) of CIMP(-) cases (P = 0.002). Both of these differences were independent of microsatellite instability. These interactions between CIMP, K-RAS mutations, and p53 mutations were preserved in colorectal adenomas, suggesting that they occur early in carcinogenesis. The distinct combinations of epigenetic and genetic alterations in each group suggest that activation of oncogenes and inactivation of tumor suppressor genes is related to the underlying mechanism of generating molecular diversity in cancer, rather than simply accumulate stochastically during cancer development.

Aberrant methylation in gastric cancer associated with the CpG island methylator phenotype

Aberrant methylation of 5' CpG islands is thought to play an important role in the inactivation of tumor suppressor genes in cancer. In colorectal cancer, a group of tumors is characterized by a hypermethylator phenotype termed CpG island methylator phenotype (CIMP), which includes methylation of such genes as p16 and hMLH1. To study whether CIMP is present in gastric cancer, the methylation status of five newly cloned CpG islands was examined in 56 gastric cancers using bisulfite-PCR. Simultaneous methylation of three loci or more was observed in 23 (41%) of 56 cancers, which suggests that these tumors have the hypermethylator phenotype CIMP. There was a significant concordance between CIMP and the methylation of known genes including p16, and hMLH1; methylation of p16 was detected in 16 (70%) of 23 CIMP+ tumors, 1 (8%) of 12 CIMP intermediate tumors, and 1 (5%) of 21 CIMP- tumors (P<0.0001). Methylation of the hMLH1 gene was detected in three of five tumors that showed microsatellite instability, and all three of the cases were CIMP+. The CIMP phenotype is an early event in gastric cancer, being present in the normal tissue adjacent to cancer in 5 of 56 cases. These results suggest that CIMP may be one of the major pathways that contribute to tumorigenesis in gastric cancers.

CpG island methylator phenotype in colorectal cancer

Aberrant methylation of promoter region CpG islands is associated with transcriptional inactivation of tumor-suppressor genes in neoplasia. To understand global patterns of CpG island methylation in colorectal cancer, we have used a recently developed technique called methylated CpG island amplification to examine 30 newly cloned differentially methylated DNA sequences. Of these 30 clones, 19 (63%) were progressively methylated in an age-dependent manner in normal colon, 7 (23%) were methylated in a cancer-specific manner, and 4 (13%) were methylated only in cell lines. Thus, a majority of CpG islands methylated in colon cancer are also methylated in a subset of normal colonic cells during the process of aging. In contrast, methylation of the cancer-specific clones was found exclusively in a subset of colorectal cancers, which appear to display a CpG island methylator phenotype (CIMP). CIMP+ tumors also have a high incidence of p16 and THBS1 methylation, and they include the majority of sporadic colorectal cancers with microsatellite instability related to hMLH1 methylation. We thus define a pathway in colorectal cancer that appears to be responsible for the majority of sporadic tumors with mismatch repair deficiency.

Methylation and silencing of the Thrombospondin-1 promoter in human cancer

Neovascularization is a common feature of many human cancers, but relatively few molecular defects have been demonstrated in genes regulating angiogenesis. Decreased expression of Thrombospondin-1 (THBS1), a P53 and Rb regulated angiogenesis inhibitor, has been observed in some human tumors, including glioblastoma multiforme (GBM). To study whether methylation-associated inactivation is involved in down-regulating THBS1 expression in cancer, we analysed the methylation status of THBS1 in several cell lines and primary tumors. Three cell lines (RKO, CEM and RAJI) were completely methylated at several CpG sites within the THBS1 5' CpG island, and had no detectable expression by RT-PCR. THBS1 expression was readily reactivated using the methylation-inhibitor 5-deoxy-azacytidine in all three lines. Furthermore, THBS1 methylation was present in 33% (14/42) of primary GBMs. Thus, de novo methylation may serve as a potential way to inactivate THBS1 expression in human neoplasms.

Identification of differentially methylated sequences in colorectal cancer by methylated CpG island amplification

CpG island methylation has been linked to tumor suppressor gene inactivation in neoplasia and may serve as a useful marker to clone novel cancer-related genes. We have developed a novel PCR-based method, methylated CpG island amplification (MCA), which is useful for both methylation analysis and cloning differentially methylated genes. Using restriction enzymes that have differential sensitivity to 5-methyl-cytosine, followed by adaptor ligation and PCR amplification, methylated CpG rich sequences can be preferentially amplified. In a model experiment using a probe from exon 1 of the p16 gene, signal was detected from MCA products of a colorectal cancer cell line but not in normal colon mucosa. To identify novel CpG islands differentially methylated in colorectal cancer, we have applied MCA coupled with representational difference analysis to the colon cancer cell line Caco2 as a tester and normal colon mucosa as a driver. Using this strategy, we isolated 33 differentially methylated DNA sequences, including fragments identical to several known genes (PAX6, Versican, alpha-tubulin, CSX, OPT, and rRNA gene). The association of hypermethylation of the clones obtained and transcriptional suppression in colorectal cancer was confirmed by examining the Versican gene, which we found to be silenced in methylated cell lines and reactivated by the methylation inhibitor 5-aza-2'-deoxycytidine. We therefore propose that MCA is a useful technique to study methylation and to isolate CpG islands differentially methylated in cancer.

High prevalence of delusional parasitosis in an Indian setting

Epidemiology and the study of subtypes of delusional disorders is a poorly researched area. This study tries to fill this lacuna and provides the evidence contrary to the accepted fact that the persecutory type is the most common subtype of persistent delusional disorder (paranoia). Out of 4234 patients who attended psychiatry outpatient department during the year 1994-1997, 45 patients received the ICD-10 diagnosis of persistent delusional disorder. Charts of these patients were used for the study. The prevalence of delusional disorder and delusional parasitosis were around 1% and 0.5% respectively making delusional parasitosis the most common sub-type in our setting. Patients with delusional parasitosis had significantly lesser education compared to the patients with persecutory or jealous delusions. These observations are explained on the basis of cultural practices and linguistic competence.

Activation of phospholipase C and protein kinase C is required for expression of anthrax lethal toxin cytotoxicity in J774A.1 cells

Anthrax lethal toxin (LT) comprises two proteins: the protective antigen (PA) and the lethal factor (LF). The LT is cytotoxic to macrophage-like cell line J774A.1. Pre-treatment of these cells with neomycin, a phospholipase C inhibitor, protected them against anthrax LT cytotoxicity. Protection obtained with neomycin indicated that LT stimulates phospholipase C in these cells. It was found that levels of inositol 1,4,5-triphosphate (IP3) dramatically increased in toxin-treated cells. The rise in IP3 levels was proportional to the dose of LF that was allowed to bind to receptor-bound PA. By using protein kinase C (PKC) inhibitors, we found that the activation of PKC is required for mediating anthrax LT cytotoxicity. Activation of phospholipase C or PKC is not required for the binding of PA to the cell surface receptors or for the uptake or internalisation of the toxin. In this study, we demonstrate that the IP3 signalling cascade is initiated by anthrax lethal toxin in J774A.1 cells. The second messengers generated during the cascade aid LF in mediating lethality only after its translocation into the cytosol.

Aging and DNA methylation in colorectal mucosa and cancer

DNA methylation of promoter-associated CpG islands may function as an alternate mechanism of silencing tumor suppressor genes in multiple neoplasias including colorectal cancer. De novo methylation of genes appears to be an early and frequent event in most neoplasias. For the ER and IGF2 genes, we have previously shown that methylation actually begins in the normal colon mucosa as an age-related event and progresses to hypermethylation in cancer. In this study, we have determined the frequency of age-related methylation in normal colonic mucosa among the genes hypermethylated in colorectal cancer. We studied six genes, including N33, MYOD, p16, HIC-1, THBS1, and CALCA. The N33 gene showed partial methylation in normal colon mucosa, which was age-related (r = 0.7; P = 0.003 using regression analysis). Adenomas and cancers showed further hypermethylation at this locus. Similarly, the MYOD gene showed age-related methylation in normal colon mucosa (r = 0.7; P < 0.00001 using regression analysis) and hypermethylation in cancers. Age-related methylation seems to be gene specific, because p16, THBS1, HIC-1, and CALCA were not affected. Furthermore, this process may also be modulated by tissue-specific factors. Our study suggests that aging is a major contributing factor to hypermethylation in cancer.

Concordant methylation of the ER and N33 genes in glioblastoma multiforme

Methylation of promoter-associated CpG islands appears to be a potential way by which tumor suppressor genes are inactivated in cancer. Using Southern blot analysis, we have studied the methylation of several genes in glioblastoma multiforme (GBM), trying to determine their contribution to tumorigenesis. Genes studied included the estrogen receptor (ER), N33, the candidate tumor-suppressors P15, P16 and HIC1 and a control gene, c-abl. Hypermethylation of N33, ER, HIC1, P16, P15 and c-abl were found in 61%, 59%, 60%, 5%, 2% and 0% of GBM respectively. HIC1 methylation was detected in normal brain as well, but appeared to be more extensive in tumors. ER and N33 methylation were significantly more frequent in tumors from individuals over the age of 40 (70% and 88% vs 36% and 14%). In addition, there was a strong association between ER and N33 methylation, which were concordant in 81% of the cases (P<0.01). ER and N33 methylation in GBM may therefore appear as a result of shared etiologic factors, which may relate in part to aging cell populations in the brain.

Incidence and functional consequences of hMLH1 promoter hypermethylation in colorectal carcinoma

Inactivation of the genes involved in DNA mismatch repair is associated with microsatellite instability (MSI) in colorectal cancer. We report that hypermethylation of the 5' CpG island of hMLH1 is found in the majority of sporadic primary colorectal cancers with MSI, and that this methylation was often, but not invariably, associated with loss of hMLH1 protein expression. Such methylation also occurred, but was less common, in MSI- tumors, as well as in MSI+ tumors with known mutations of a mismatch repair gene (MMR). No hypermethylation of hMSH2 was found. Hypermethylation of colorectal cancer cell lines with MSI also was frequently observed, and in such cases, reversal of the methylation with 5-aza-2'-deoxycytidine not only resulted in reexpression of hMLH1 protein, but also in restoration of the MMR capacity in MMR-deficient cell lines. Our results suggest that microsatellite instability in sporadic colorectal cancer often results from epigenetic inactivation of hMLH1 in association with DNA methylation.

Association between CpG island methylation and microsatellite instability in colorectal cancer

De novo methylation of promoter region CpG islands has been increasingly associated with transcriptional inactivation of important genes in neoplasia. To study the potential mechanisms underlying aberrant methylation in cancer, we have determined the methylation patterns of selected genes in colorectal cancers with and without microsatellite instability (MI), which results from defects in one of several base mismatch repair genes. A total of 47 colorectal cancers were analyzed, of which 15 were MI+ (32%). We now report that both the frequency and the extent of de novo methylation are strikingly increased in MI+ cancers. Hypermethylation of the p16 gene was found in 60% of MI+ cancers, compared to only 22% in MI- cancers (P = 0.02). Similarly, hypermethylation of the thrombospondin-1 (TSP-1) gene, an angiogenesis inhibitor, was increased in MI+ cancers (27% versus 0%; P = 0.008). Extensive methylation of insulin-like growth factor II (IGF2) and hypermethylated in cancer-1 (HIC-1) genes was observed in 60 and 80% of MI+ cancers, respectively, as contrasted with 6 and 38% of MI- cancers (P = 0.0002 and 0.01, respectively). Furthermore, 60% of the MI+ cancers displayed the hypermethylation events at two or more loci in a concordant manner compared to only 9% of the MI- cancers (P < 0.001). These results demonstrate a strong link between promoter hypermethylation and genetic instability due to deficient DNA repair.

Multiscale image segmentation by integrated edge and region detection

This paper is concerned with the detection of low-level structure in images. It describes an algorithm for image segmentation at multiple scales. The detected regions are homogeneous and surrounded by closed edge contours. Previous approaches to multiscale segmentation represent an image at different scales using a scale-space. However, structure is only represented implicitly in this representation, structures at coarser scales are inherently smoothed, and the problem of structure extraction is unaddressed. This paper argues that the issues of scale selection and structure detection cannot be treated separately. A new concept of scale is presented that represents image structures at different scales, and not the image itself. This scale is integrated into a nonlinear transform which makes structure explicit in the transformed domain. Structures that are stable (locally invariant) to changes in scale are identified as being perceptually relevant. The transform can be viewed as collecting spatially distributed evidence for edges and regions, and making it available at contour locations, thereby facilitating integrated detection of edges and regions without restrictive models of geometry or homogeneity. In this sense, it performs Gestalt analysis. All scale parameters of the transform are automatically determined, and the structure of any arbitrary geometry can be identified without any smoothing, even at coarse scales.

Parallel distributed detection of feature trajectories in multiple discontinuous motion image sequences

Concerns the 3D interpretation of image sequences showing multiple objects in motion. Each object exhibits smooth motion except at certain time instants when a motion discontinuity may occur. The objects are assumed to contain point features which are detected as the images are acquired. Estimating feature trajectories in the first two frames amounts to feature matching. As more images are acquired, existing trajectories are extended. Both initial detection and extension of trajectories are done by enforcing pertinent constraints from among the following: similarity of the image plane arrangement of neighboring features, smoothness of the 3D motion and smoothness of the image plane motion. The constraints are incorporated into energy functions which are minimized using 2D Hopfield networks. Wrong matches that result from convergence to local minima are eliminated using a 1D Hopfield-like network. Experimental results on several image sequences are shown.