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J M Rhodes

Publications and source records attributed to J M Rhodes.

At least 19 recordsLinked to original sources
PubMed2006

Strategies for detecting colon cancer and/or dysplasia in patients with inflammatory bowel disease.

BACKGROUND: Patients with longstanding ulcerative colitis and colonic Crohn's disease have an increased risk of colorectal cancer compared with the general population. This review assesses the evidence that endoscopic surveillance may prolong life by allowing earlier detection of colon cancer or its pre-cursor lesion, dysplasia, in patients with inflammatory bowel disease. OBJECTIVES: To assess the effectiveness of cancer surveillance programs in reducing the death rate from colorectal cancer in patients with ulcerative colitis and colonic Crohn's disease. SEARCH STRATEGY: The following strategies were used to identify relevant studies:1. MEDLINE and the Cochrane Central Register of Controlled Trials were searched from 1966 to August 2005. The medical subject headings "Ulcerative Colitis", "Crohn Disease" or "Inflammatory Bowel Disease" and "Surveillance" or "Cancer" were used to perform key-word searches of the databases.2. Hand searching of reference lists from papers. SELECTION CRITERIA: Potentially relevant articles were reviewed independently and unblinded by three authors to determine if they fulfilled the selection criteria. Each article was rated as being eligible, ineligible, or without sufficient information to determine eligibility. Any disagreement between reviewers was resolved by consensus. Any trials published in abstract form were only considered if it was possible to obtain full details of the protocol and results from the authors. DATA COLLECTION AND ANALYSIS: Eligible articles were reviewed in duplicate and the results of the primary research trials were abstracted onto specially designed data extraction forms. The proportion of patients dying from bowel cancer or other causes in the control and surveillance groups of each study was derived from life tables, survival curves or where possible, by calculating life tables from the data provided. Data from the original research articles were converted into 2x2 tables (survival versus death x surveillance versus control) for each of the individual studies for comparable follow-up intervals. The presence of significant heterogeneity among studies was tested by the chi-square test. Because this is a relatively insensitive test, a P value of less than 0.1 was considered statistically significant. Provided statistical heterogeneity was not present, the fixed effects model was used for the pooling of data. The 2x2 tables were combined into a summary test statistic using the pooled relative risk (RR) and 95% confidence intervals as described by Cochrane and Mantel and Haenszel. MAIN RESULTS: Karlen 1998a in a nested case-control study comprising 142 patients from a study population of 4664 UC patients, found that 2/40 patients dying of colorectal cancer had undergone surveillance colonoscopy on at least one occasion compared with 18/102 controls (RR 0.28, 95% CI 0.07 to 1.17). One of 40 patients who died from colorectal cancer had undergone surveillance colonoscopies on two or more occasions compared with 12/102 controls (RR 0.22, 95% CI 0.03 to 1.74) in contrast to a more modest effect observed for patients who had only one colonoscopy (RR 0.43, 95% CI 0.05 to 3.76). Choi 1993 found that carcinoma was detected at a significantly earlier stage in the surveilled patients; 15/19 had Duke's A or B carcinoma in the surveilled group compared to 9/22 in the non-surveilled group (P = 0.039). The 5-year survival rate was 77.2% for cancers occurring in the surveillance group and 36.3% for the no-surveillance group (P = 0.026). Four of 19 patients in the surveillance group died from colorectal cancer compared to 11 of 22 patients in the non-surveillance group (RR 0.42, 95% CI 0.16 to 1.11). Lashner 1990 found that four of 91 patients in a surveillance group died from colorectal cancer compared to 2 of 95 patients in a non-surveilled group (RR 2.09, 95% CI 0.39 to 11.12). Colectomy was less common in the surveillance group, 33 compared to 51 (P < 0.05) and was performed four years later (after 10 years of disease) in the surveillance group. For the pooled data analysis 8/110 patients in the surveillance group died from colorectal cancer compared to 13/117 patients in the non-surveillance group (RR 0.81, 95% CI 0.17 to 3.83). AUTHORS' CONCLUSIONS: There is no clear evidence that surveillance colonoscopy prolongs survival in patients with extensive colitis. There is evidence that cancers tend to be detected at an earlier stage in patients who are undergoing surveillance, and these patients have a correspondingly better prognosis, but lead-time bias could contribute substantially to this apparent benefit. There is indirect evidence that surveillance is likely to be effective at reducing the risk of death from IBD-associated colorectal cancer and indirect evidence that it may be acceptably cost-effective.

Biopsy↗
PubMed2006

Altered colonic glycoprotein expression in unaffected monozygotic twins of inflammatory bowel disease patients.

BACKGROUND AND AIMS: Previous chromatographic analysis of colonic mucins from monozygotic twins with inflammatory bowel disease (IBD) suggested a genetic mucin alteration in ulcerative colitis (UC). This study explores this further by assessing mucosal expression of the oncofetal carbohydrate antigen TF (galactose beta1, 3 N-acetylgalactosamine alpha-), among the same IBD twins. MATERIALS AND METHODS: Formalin fixed paraffin embedded rectal biopsies were studied from 22 monozygotic twin pairs with IBD. These included eight UC twin pairs and 14 Crohn's disease (CD) twin pairs, with six pairs concordant for disease and 16 unaffected twin siblings. Closely adjacent sections were assessed by peanut lectin histochemistry for TF expression and immunohistochemically for nuclear factor kappaB (NFkappaB) activation with investigators blinded to the diagnosis. RESULTS: Unaffected twins were almost all TF positive (15/16) compared with 5/29 histologically normal controls (p<0.0001). Unaffected UC (7/8) and CD twins (8/8) were similarly TF positive. TF positivity was confined mainly to the superficial epithelium and absent from the stem cell compartment of the lower crypts, suggesting that glycosylation changes are acquired rather than genetically determined. Activated NFkappaB was present in the surface epithelium of mucosal biopsies from 13/14 unaffected IBD twins but in only 6/22 histologically normal controls (p=0.0004). All 22 affected IBD twins were TF positive and 18 were positive for activated NFkappaB. CONCLUSIONS: Altered mucosal glycosylation in unaffected identical twins of IBD patients was confirmed in this study. This occurred in both UC and CD twins. The changes are probably acquired rather than congenital and may reflect "preinflammatory" NFkappaB activation.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed2005

Lessons for inflammatory bowel disease from rheumatology.

There are several areas of overlap between gastroenterology and rheumatology, some related to the side effects of drugs but others related to the similarities in probable pathogenic mechanisms and treatments. This is best illustrated by comparison between inflammatory bowel disease and rheumatoid arthritis-conditions of uncertain aetiology that are due to a combination of genetic and environmental factors and are associated with chronic inflammation in the absence of any clearly recognisable pathogen. Medical research is increasingly specialised but careful comparison of the relevant gastroenterological and rheumatological literatures suggests several common areas that are worthy of greater attention than they are currently receiving. These could include studies to address the following questions: (1) What are the functional and antigen-binding differences of the HLA class II alleles that are differently associated with rheumatoid arthritis and ulcerative colitis? (2) Why are both Crohn's disease and rheumatoid arthritis associated with smoking, yet, with one condition (Crohn's disease) increasing recently in incidence and the other (rheumatoid arthritis) becoming less common? (3) Which genetic and/or environmental factors distinguish the Turkish patients with HLA-B51-associated Behcet's disease who tend not to develop colitis and the Japanese patients with HLA-B51-associated Behcet's disease who develop colitis? (4) Is pANCA directly involved in the pathogenesis of ulcerative colitis-given evidence of its direct involvement in the pathogenesis of vasculitis? (5) Given the arguably greater similarity between rheumatoid arthritis and ulcerative colitis than with Crohn's disease, is etanercept effective in ulcerative colitis? (6) Do the very different risks of cancer in chronically inflamed colon and inflamed joints imply that cancer development requires both NFkappaB activation, to inhibit apoptosis, and the presence of agents, such as bacteria, to initiate DNA damage?

Arthritis, Rheumatoid↗
PubMed2004

Strategies for detecting colon cancer and/or dysplasia in patients with inflammatory bowel disease.

BACKGROUND: Patients with longstanding ulcerative colitis and colonic Crohn's disease have an increased risk of colorectal cancer compared with the general population. This review assesses the evidence that endoscopic surveillance may prolong life by allowing earlier detection of colon cancer or its pre-cursor lesion, dysplasia in patients with inflammatory bowel disease. OBJECTIVES: To assess the effectiveness of cancer surveillance programs in reducing the death rate from colorectal cancer in patients with ulcerative colitis and colonic Crohn's disease. SEARCH STRATEGY: The following strategies were used to identify relevant studies: 1. MEDLINE and the Cochrane Central Register of Controlled Trials were searched from 1966 to December 2002. The medical subject headings "Ulcerative Colitis", "Crohn Disease" or "Inflammatory Bowel Disease" and "Surveillance" or "Cancer" were used to perform key-word searches of the databases. 2. Hand searching of reference lists from papers. SELECTION CRITERIA: Potentially relevant articles were reviewed independently and unblinded by three authors to determine if they fulfilled the selection criteria. Each article was rated as being eligible, ineligible, or without sufficient information to determine eligibility. Any disagreement between reviewers was resolved by consensus. Any trials published in abstract form were only considered if it was possible to obtain full details of the protocol and results from the authors. DATA COLLECTION AND ANALYSIS: Eligible articles were reviewed in duplicate and the results of the primary research trials were abstracted onto specially designed data extraction forms. The proportion of patients dying from bowel cancer or other causes in the control and surveillance groups of each study was derived from life tables, survival curves or where possible, by calculating life tables from the data provided. Data from the original research articles were converted into 2x2 tables (survival versus death x surveillance versus control) for each of the individual studies for comparable follow-up intervals. The presence of significant heterogeneity among studies was tested by the chi-square test. Because this is a relatively insensitive test, a p value of less than 0.1 was considered statistically significant. Provided statistical heterogeneity was not present (p>0.10), the fixed effects model was used for the pooling of data. The 2x2 tables were combined into a summary test statistic using the pooled relative risk (RR) and 95% confidence intervals as described by Cochrane and Mantel and Haenszel. MAIN RESULTS: Karlen 1998a found that 2/40 of the patients dying of colorectal cancer had undergone surveillance colonoscopy on at least one occasion compared with 18/102 of the controls (RR 0.28, 95% confidence interval 0.07 to 1.17). One of 40 patients who died from colorectal cancer had undergone surveillance colonoscopies on two or more occasions compared with 12/102 controls (RR 0.22, 95% confidence interval 0.03 to 1.74) in contrast to a more modest effect observed for patients who had only one colonoscopy (RR 0.43, 95% confidence intervals 0.05 to 3.76). Choi 1993 found that carcinoma was detected at a significantly earlier stage in the surveillance group; 15/19 had Duke's A or B carcinoma in the surveilled group compared to 9/22 in the non-surveilled group (P= 0.039). The 5-year survival rate was 77.2% for cancers occurring in the surveillance group and 36.3% for the no-surveillance group (P= 0.026). Four of 19 patients in the surveillance group died from colorectal cancer compared to 11 of 22 patients in the non-surveillance group (RR 0.42, 95% CI 0.16 to 1.11). Lashner 1990 found that four of 91 patients in the surveillance group died from colorectal cancer compared to 2 of 95 patients in the non-surveilled group (RR 2.09, 95% CI 0.39 to 11.12). Colectomy was less common in the surveillance group, 33 compared to 51 (p < 0.05) and was performed four years later (after 10 years of disease) in the surveillance group. For the pooled data analysis 8/110 patients in the surveillance group died from colorectal cancer compared to 13/117 patients in the non-surveillance group (RR 0.81, 95% CI 0.17 to 3.83). REVIEWERS' CONCLUSIONS: There is no clear evidence that surveillance colonoscopy prolongs survival in patients with extensive colitis. There is evidence that cancers tend to be detected at an earlier stage in patients who are undergoing surveillance and these patients have a correspondingly better prognosis but lead-time bias could contribute substantially to this apparent benefit. There is indirect evidence that surveillance is likely to be effective at reducing the risk of death from IBD-associated colorectal cancer and indirect evidence that it is acceptably cost-effective.

Biopsy↗
PubMed2004

Management of inflammatory bowel disease.

Ulcerative colitis and Crohn's disease result from an interaction between genetic and environmental factors. Only one gene, NOD2/CARD15, has been clearly identified; a minority of people with alteration of this gene develop Crohn's disease. The NOD2/CARD15 protein is thought to be involved in defence against intracellular bacteria. This supports the idea that Crohn's disease and ulcerative colitis result from altered immunological responses to the normal intestinal flora. Life expectancy is normal in ulcerative colitis and nearly so in Crohn's disease, but both conditions cause considerable morbidity. Approximately 80% of patients with Crohn's disease eventually require surgery, and about 25% of patients with ulcerative colitis require colectomy. Treatment of ulcerative colitis is generally by corticosteroids for acute disease and mesalazine for maintenance, but the range of therapies for Crohn's disease is expanding. Alternative therapies include immunosuppressives, enteral nutrition, antibiotics, anti-TNF antibody (infliximab), corticosteroids, and surgery. High dosages of corticosteroids may provide symptomatic relief in Crohn's disease but do not affect the long term natural history of the disease, and management strategies should avoid using steroids whenever possible.

Chronic Disease↗
PubMed2003

An unusual cause of acute renal failure in systemic sclerosis.

BACKGROUND: Scleroderma renal crisis is one of the most life threatening complications of scleroderma. Enteric hyperoxaluria complicates extensive disease or resection of the small intestine in the presence of an intact colon, and is associated with calcium oxalate nephrolithiasis. This cause of renal failure may be underestimated and should be considered in all patients with malabsorption and renal failure. CASE REPORT: A 78 year old woman with systemic sclerosis affecting the bowel developed acute renal failure caused by oxalate nephropathy. RESULTS: The patient's renal failure improved on an oxalate free diet.

Acute Kidney Injury↗
PubMed2003

Detection of sulfated glycoproteins in intestinal metaplasia: a comparison of traditional mucin staining with immunohistochemistry for the sulfo-Lewis(a) carbohydrate epitope.

BACKGROUND: Premalignant Barrett's oesophagus (BO) and gastric intestinal metaplasia (IM) show phenotypic variability. Incompletely differentiated sulfomucin rich gastric IM (type III) may have increased malignant potential. The types of sulfated oligosaccharide structures present in IM, BO, and colon have not been fully characterised. AIMS: To compare sulfo-Lewis(a) epitope tissue distribution with high iron diamine (HID) positive sulfomucin in metaplastic, dysplastic, and neoplastic tissues from oesophagus and stomach. METHODS: Sections containing gastric IM or BO (some associated with dysplasia or adenocarcinoma) were stained by the HID/alcian blue (AB) method and immunohistochemically (antibody 91.9H) to detect sulfo-Lewis(a). Based on HID/AB staining, IM was subtyped into type I (complete) or types II and III (incomplete). RESULTS: In total, 125 sections from 38 subjects were studied. Normal squamous oesophagus, normal gastric epithelium, and type I IM were negative for sulfomucin and sulfo-Lewis(a). In type II IM, occasional goblet cells were HID and sulfo-Lewis(a) positive, but sialomucin secreting (AB positive) columnar cells were sulfo-Lewis(a) negative. Type III IM was always sulfo-Lewis(a) positive. Sulfomucin staining in dysplasia and cancer was variable, but HID positive areas were always sulfo-Lewis(a) positive. CONCLUSIONS: Sulfo-Le(a), which is expressed on colonic mucin, is invariably present on sulfomucins in gastric IM and BO. Its presence in incomplete variants of IM and its absence from type I IM emphasises the phenotypic differences between complete and incomplete forms of metaplasia. 91.9H immunostaining is useful in IM subtyping. Characterising the molecular basis of sulfo-Lewis(a) expression may help understand the process of aberrant differentiation.

Adenocarcinoma↗
PubMed2002

Agaricus bisporus (edible mushroom lectin) inhibits ocular fibroblast proliferation and collagen lattice contraction.

The edible mushroom lectin from Agaricus bisporus (ABL) has antiproliferative effects on a range of cell types. This investigation was undertaken to test whether it might have inhibitory activity on Tenon's capsule fibroblasts in in vitro models of wound healing and therefore have a use in the modification of scar formation after glaucoma surgery.Human ocular fibroblasts in monolayers and in three-dimensional collagen lattices were exposed to ABL (0-100 microg ml(-1)). Proliferation was studied by the MTS assay and by counting haematoxylin-stained cells; contraction was measured as a change in the diameter of three-dimensional collagen lattices. Toxicity was investigated using a fluorescent viability assay. FITC-labelled lectin was used to study cell binding and internalization of ABL.ABL caused a dose-dependent inhibition of proliferation and lattice contraction without significant toxicity. Proliferation was inhibited by 5-40% in the dose range 20-100 microg ml(-1) Significant inhibition of lattice contraction was achieved with 40 microg ml(-1) ABL, and at 100 microg ml(-1) contraction was completely prevented. FITC-ABL binds to the cell surface and accumulates around the nuclear envelope when internalized. These experiments have shown that ABL possesses key features required of an agent that might control scarring processes and suggest that ABL might be especially useful where subtle modification of healing is needed. Further evaluation is warranted.

Cell Death↗
PubMed2002

Dietary lectins can stimulate pancreatic growth in the rat.

Lectins are proteins or glycoproteins of nonimmune origin, which bind specifically to carbohydrate structures. They are widespread in the human diet, and many are resistant to digestion. High doses of lectins have been shown to stimulate intestinal and pancreatic growth. The aim of the present study was to investigate the long-term actions of low doses of lectins on the rat intestine and pancreas. A long-term carcinogenesis study was performed using low levels (40 micro g/rat/day) of peanut (PNA) or mushroom lectin (ABA) which bind to O-linked (mucin-type) oligosaccharides in the gut. While this was primarily designed as a colon carcinogenesis study, the pancreas was also investigated. No significant changes in colon carcinogenesis were seen, however, the colons were slightly heavier in the lectin treated groups. The weight of the pancreas was significantly greater (by 18 and 23%) in both lectin treated groups (P < 0.03/0.001). The weights of the acini and septal tissue were also increased by 39-46% in PNA and ABA fed animals, respectively (P < 0.002); there was no significant change in the endocrine pancreas. In conclusion, long-term feeding of low doses of lectin can influence pancreatic growth, and this trophic action may have potential adverse implications for the development of pancreatic cancer in humans.

Animals↗
PubMed2001

Opposite effects on human colon cancer cell proliferation of two dietary Thomsen-Friedenreich antigen-binding lectins.

Increased cell surface expression of the Thomsen-Friedenreich antigen (TF antigen, Galbeta1-3GalNAcalpha-) is a common feature in malignant and pre-malignant epithelia. Our previous studies have shown that dietary TF-binding lectins from peanut (Arachis hypogea) and edible mushroom (Agaricus bisporus) produce marked but different effects on human intestinal epithelial cell proliferation. This study investigates the proliferative effects of the other two known dietary TF-binding lectins: jacalin (Artocarpus integrifolia, JAC) and amaranth lectin (Amaranthus caudatus, ACA). JAC produced dose-dependent and non-cytotoxic inhibition of proliferation in HT29 human colon cancer cells with maximal effects of 46 +/- 4% at 20 microg/ml, whereas ACA produced dose-dependent stimulation of proliferation with maximal effects of 22 +/- 3% at 20 microg/ml when assessed both by incorporation of [3H]thymidine into DNA and by cell counting. The lectin-mediated effects were inhibitable by the presence of appropriate Galbeta1-3GalNAc-expressing glycoproteins but differences existed between JAC and ACA in their patterns of inhibition by such substances. Ligand binding equilibrium studies using iodinated lectins revealed different Kd of the two lectins for HT29 cell surface glycoproteins. Lectin blots of cell membrane extracts showed different binding patterns in all the four TF-binding lectins. These results provide further evidence that dietary TF-binding lectins can have marked effects on the proliferation of human malignant gastro-intestinal epithelial cells and hence may play a role in intestinal cancer development, and also show that the biological effects of dietary lectins cannot be predicted solely from their carbohydrate binding properties.

Adjuvants, Immunologic↗
PubMed2001

Reduction in wound morbidity rates following endoscopic saphenous vein harvest.

To determine whether less-invasive saphenous vein harvest reduces morbidity in patients undergoing infrainguinal bypass, we retrospectively compared 61 patients undergoing endoscopic harvest (ENDO) with 49 patients undergoing conventional harvest (OPEN) over the past 13 months. Patients were classified as potential short-stay if adjunctive suprainguinal inflow procedures or foot amputations were not required and the patient was ambulatory prior to elective operation. Mean endoscopic harvest time was 50+/-18 (range 25-90) min, and no more than three 5-cm incisions were required in 87% of cases. Szilagyi class II or III wound complications occurred after 1 of the 61 (2%) ENDO procedures and 7 of the 49 (14%) OPEN (p < 0.01), and any complication occurred in 13 (21%) vs. 25 (51%) of ENDO and OPEN procedures, respectively (p < 0.002). Mean postoperative length of stay was significantly shorter in the 24 short-stay ENDO (4.0+/-2.4 days) vs. 25 short-stay OPEN (6.0+/-3.2 days) patients (p < 0.02). Thirty-day patency rates between the two groups were not different. Endoscopic saphenous vein harvest is associated with a reduced incidence of serious wound complications and, in selected patients, shortened postoperative hospital stay.

Aged↗
PubMed2001

Use of a biosensor to determine the binding kinetics of five lectins for Galactosyl-N-acetylgalactosamine.

The dietary lectins, edible mushroom (ABL) and Jacalin (JAC) inhibit the proliferation of colonic cancer cells, whereas Amaranth (ACL) and peanut (PNA) stimulate their proliferation. All these lectins share as their preferred ligand the Thomsen-Friedenreich (TF) antigen galactosyl beta1,3 N-Acetylgalactosamine (Galbeta1,3GalNAc), but differ in their finer specificities for modifications of this determinant and in their specificities for cancerous epithelia. We have investigated, using a resonant mirror biosensor, the kinetics of binding of these lectins, and Maclura pomifera lectin (MPL), which is similar to JAC, to two different Gal-GalNac bearing glycoproteins, antarctic fish antifreeze glycoprotein (AFG) and asialofetuin. JAC had the highest affinity for AFG [K(d) 0.027 microM] due to a fast association rate constant [k(ass) 610,000 (Ms)(-1)]. The other lectins had considerably lower affinities, with K(d) ranging from 0.16 microM (ABL) to 5.7 microM (PNA), largely due to slower k(ass) [ABL 74,000 (Ms)(-1) to PNA 2700 (Ms)(-1)]. Similarly, JAC had a much higher affinity for asialofetuin [K(d) 0.083 microM] than the other lectins [K(d) 1.0 microM-4.5 microM]. Affinities were also calculated from the extent of binding at equlibrium and were generally similar to those calculated from the kinetic parameters indicating the true nature of these values.

Acetylgalactosamine↗
PubMed2001

Comparison of the effects of concanavalin-A and epidermal growth factor on epithelial cell proliferation in the rat intestine.

BACKGROUND: Concanavalin-A, the lectin present in Jack beans, binds to mannose- and glucose-containing residues and can interact with the epidermal growth factor receptor and moderate cell proliferation in vitro. AIM: To compare the actions of concanavalin-A and epidermal growth factor on the gastrointestinal tract in vivo. METHODS: Rats maintained on total parenteral nutrition were given intragastric concanavalin-A, intravenous epidermal growth factor or concanavalin-A and epidermal growth factor. Cell proliferation and crypt fission were assayed in 'micro-dissected' crypts. RESULTS: Concanavalin-A and epidermal growth factor both significantly elevated proliferation in the small intestine and colon. No significant interaction between the effects of these two agents was seen, except in the mid small intestine where there was a synergistic interaction. Concanavalin-A had no effect on crypt branching. Epidermal growth factor significantly reduced branching in the distal small intestine and mid colon. CONCLUSION: The effects of the two agents appeared to be separate, except in the mid small intestine where they were additive. This is in marked contrast with the actions reported in vitro, where concanavalin-A is a powerful inhibitor of epidermal growth factor-induced cell proliferation. Concanavalin-A thus has potential for enhancing the functions of the small intestine.

Animals↗
PubMed2001

Human lung adenocarcinoma alpha1,3/4-L-fucosyltransferase displays two molecular forms, high substrate affinity for clustered sialyl LacNAc type 1 units as well as mucin core 2 sialyl LacNAc type 2 unit and novel alpha1,2-L-fucosylating activity.

Human lung tumor alpha1,3/4-L-fucosyltransferase (FT) was purified (2000-fold, 29% recovery) from 290 g of tissue by including a chromatography step on Affinity Gel-GDP. Two molecular forms (FTA, larger size carrying 15% alpha1,4-FT activity; FTB, the major form with 85% activity) were separated by further fractionation on a Sephacryl S-100 HR column. A difference in the electrophoretic mobilities of these two activities was also found on native polyacrylamide gel electrophoresis (PAGE). Both forms were devoid of typical alpha1,2-fucosylating activity but were associated with the novel alpha1,2-fucosylating ability of converting the Lewis a determinant to Lewis b. Based on percentage activity toward 2-O-MeGalbeta1,3GlcNAcbeta-O-Bn, both forms exhibited the same extent of activity toward various acceptors, which included sulfated, sialylated, or methylated LacNAc type 1 or type 2 as well as mucin core 2 acceptors. However, FTA and FTB exhibited a difference in their ability to act on mucin core 2 3'-sialyl LacNAc (activities 24.2% and 40.8%, respectively, as compared to 2-O-MeGalbeta1,3GlcNAcbeta-O-Bn). The unsubstituted LacNAc type 1 acceptors were 15-20 times as active as the corresponding LacNAc type 2 acceptors. The 3-O-substitution on the beta1,4-linked Gal (methyl, sulfate, or sialyl) in mucin core 2 acceptors increased the efficiency of these acceptors five- to eightfold. The most efficient acceptor for FTA and FTB was 3-O-sulfoGalbeta1,3GlcNAcbeta-O-Al (K(m) 100 and 47 microM, respectively). The K(m) (mM) values for 2-O-methyl Galbeta1,3GlcNAcbeta-O-Bn and 3-O-sialyl Galbeta1,3GlcNAcbeta-O-Bn were 0.40 and 2.5 (FTA) and 0.16 and 0.67 (FTB), respectively. The 35-kDa glycoprotein ancrod (from Malayan pit viper venom) containing 36% complex N-glycans with the antennae NeuAcalpha2,3Galbeta1,3GlcNAcbeta- acted as the best macromolecular acceptor substrate (K(m): 45 microM), as examined with FTB. On desialylation the acceptor efficiency dropped to approximately 50% (K(m) for asialo ancrod: 167 microM). Sialylglycoproteins, such as carcinoembryonic antigen, fetuin, and bovine alpha(1)-acid glycoprotein, were better acceptors than asialo fetuin. On the contrary, fetuin triantennary glycopeptide containing predominantly NeuAcalpha2,3Galbeta1,4GlcNAcbeta- was only 55% active as compared to the asialo glycopeptide (K(m): 1.43 and 0.63 mM, respectively). Thus, the human lung tumor alpha1,3/4-L-FT has the potential to generate clustered sialyl Lewis a and Lewis b determinants in N-glycans and sialyl Lewis x determinant in mucin core 2 structures.

Adenocarcinoma, Mucinous↗
PubMed2001

Increasing the intra-Golgi pH of cultured LS174T goblet-differentiated cells mimics the decreased mucin sulfation and increased Thomsen-Friedenreich antigen (Gal beta1-3GalNac alpha-) expression seen in colon cancer.

Mucins in ulcerative colitis and colon cancer share common properties of reduced sulfation and increased oncofetal carbohydrate antigen expression. It has previously been shown that there is no simple correlation between these changes and the activity of the relevant glycosyl-, sialyl-, and sulfo-transferases. We examined mucin sulfation and expression of oncofetal Thomsen-Friedenreich (TF) antigen (galactosyl beta1-3N-acetylgalactosamine alpha-) in the goblet cell-differentiated human colon cancer cell line LS174T following treatment with bafilomycin A(1, )which raises intra-Golgi pH, or monensin, which disrupts medial-trans Golgi transport. Cells were dual-labeled with sodium [(35)S]-sulfate and D-[6-(3)H(N)]-glucosamine hydrochloride, or labeled with L-[U-(14)C]-threonine alone. Mucin was purified using Sepharose CL-4B gel filtration. Mucin sulfo-Lewis(a) and TF antigen expression were assessed using the F2 anti-sulfo-Lewis(a) monoclonal antibody and peanut agglutinin binding respectively. Bafilomycin (0.01 microM; 48 h) reduced total mucin sulfation, expressed relative to incorporation of glucosamine, to 0.50 +/- 0.04 d.p.m. [(35)S]-sulfate per d.p.m. [(3)H]-glucosamine compared to control, 0.84 +/- 0.05 (p < 0.001, n = 16). This was accompanied by 50.3 +/- 8.0% increased expression of TF antigen (p < 0.01) and 50.1 +/- 5.5% decreased expression of sulfo-Lewis(a) (p < 0.01). The reduced sulfate:glucosamine ratio was largely due to increased incorporation of glucosamine into newly synthesized mucin rather than reduction in total sulfate incorporation. In contrast, monensin only reduced total mucin glycosylation at concentrations > 0.1 microM and had no significant effect on mucin sulfation or TF expression. Intra-Golgi alkalinization affects mucin glycosylation, resulting in decreased mucin sulfation and increased expression of TF antigen, changes that mimic those seen in cancerous and premalignant human colonic epithelium.

Anti-Bacterial Agents↗
PubMed2001

Cell surface-expressed Thomsen-Friedenreich antigen in colon cancer is predominantly carried on high molecular weight splice variants of CD44.

Increased mucosal expression of TF, the Thomsen-Friedenreich oncofetal blood group antigen (galactose beta1-3 N-acetylgalactosamine alpha-) occurs in colon cancer and colitis. This allows binding of TF-specific lectins, such as peanut agglutinin (PNA), which is mitogenic to the colorectal epithelium. To identify the cell surface TF-expressing glycoprotein(s), HT29 and Caco2 colon cancer cells were surface-labeled with Na[(125)I] and subjected to PNA-agarose affinity purification and electrophoresis. Proteins, approximately 110-180 kDa, present in HT29 but not Caco2 were identified by Western blotting as high molecular weight splice variants of CD44 (CD44v). Selective removal of TF antigen by Streptococcus pneumoniae endo-alpha-N-acetylgalactosaminidase substantially reduced PNA binding to CD44v. Immunoprecipitated CD44v from HT29 cell extracts also expressed sialyl-Tn (sialyl 2-6 N-acetylgalactosaminealpha-). Incubation of PNA 15 microg/ml with HT29 cells caused no additional proliferative effect in the presence of anti-CD44v6 mAb. In colon cancer tissue extracts (N = 3) PNA bound to CD44v but not to standard CD44. These data show that CD44v is a major PNA-binding glycoprotein in colon cancer cells. Because CD44 high molecular weight splice variants are present in colon cancer and inflammatory bowel disease tissue but are absent from normal mucosa, these results may also explain the increased PNA reactivity in colon cancer and inflammatory bowel disease. The coexpression of oncofetal carbohydrate antigens TF and sialyl-Tn on CD44 splice variants provides a link between cancer-associated changes in glycosylation and CD44 splicing, both of which correlate with increased metastatic potential.

Antibodies, Monoclonal↗