Impaired detoxication of hydrogen sulfide in ulcerative colitis?

Impaired butyrate oxidation and raised counts of sulfate-reducing bacteria in the colon of patients with ulcerative colitis (UC) indicate that the disease may be induced or aggravated by hydrogen sulfide toxicity. We aimed to examine enzymatic removal of H(2)S in erythrocytes and colonic mucosa from controls and patients with UC and Crohn's disease (CD). Rhodanese (RHOD) and thiol methyltransferase (TMT) activities were measured in rectal mucosa and erythrocytes, and plasma thiocyanate was determined. Four groups were analyzed: patients with UC, patients with CD, hospital controls (patients with dyspepsia or IBS), and a group of healthy volunteers. RHOD and TMT activity in rectal biopsies did not differ significantly between controls and patients with UC or CD (n=56). Control levels of RHOD were significantly higher in men than in women (212+/-25 and 132+/-14 nmol/mg/min, respectively; P<0.01). In erythrocytes (n=128) RHOD activity was significantly higher in UC patients than in hospital or volunteer controls (1.15+/-0.12 compared with 0.88+/-0.12 and 0.66+/-0.02 nmol/mg/min; P<0.05 and P<0.02, respectively). TMT activity was also significantly higher in erythrocytes from UC patients and hospital controls than volunteer controls (2.02+/-0.13 pmol/mg/min [P<0.001], 1.51+/-0.21 pmol/mg/min [P<0.05], and 1.17+/-0.18 pmol/mg/min, respectively). We found no evidence of defective enzymic detoxication of sulfide by RHOD or TMT in patients with UC or CD.

Sulfide-detoxifying enzymes in the human colon are decreased in cancer and upregulated in differentiation.

H2S is highly toxic and selectively inhibits butyrate oxidation in colonocytes. Ineffective detoxification may result in mucosal insult, inflammation, and ultimately in colorectal cancer (CRC). Rhodanese can detoxify H2S and is comprised of two isoenzymes: thiosulfate sulfurtransferase (TST) and mercaptopyruvate sulfurtransferase (MST). Using specific antisera to discriminate TST from MST, we found that only TST could detoxify H2S. In sections of normal colon, both enzymes were located on the luminal mucosal surface, and they were expressed in the colonocytes but not in the mucin-secreting goblet cells. Expression of both enzymes was focally lost in ulcerative colitis and markedly reduced in advanced colon cancer, the disease progression correlating with the decreased expression of MST and TST. In HT-29 cells, a human colon cancer cell line, TST activity and expression were significantly increased by butyrate and by histone deacetylase inhibition, agents that promote HT-29 cell differentiation. Sulfide (0.1 mM) also increased TST activity, but higher sulfide concentrations (0.3-3 mM) were toxic. Preincubation in butyrate to increase TST expression, decreased sensitivity of the cells to sulfide toxicity. We conclude that decreased expression of TST (or MST) is a tumor marker for CRC. TST expression is increased in colonocyte differentiation. Dysregulation of TST expression and activity resulting in inability to effectively detoxify could be a factor in the cell loss and inflammation that accompany ulcerative colitis and ultimately then in CRC.

Systemic hypertension and glaucoma: mechanisms in common and co-occurrence.

AIMS: To determine whether systemic hypertension and glaucoma might coexist more often than expected, with possible implications for treatment. METHODS: Case-control study using general practitioner database of patients with glaucoma matched with controls for age and sex. RESULTS: Hypertension was significantly more common in the 27,080 patients with glaucoma (odds ratio 1.29, 95% confidence intervals 1.23 to 1.36, p<0.001) than in controls. Treatment by oral beta blockade appeared to protect from risk (odds ratio 0.77, 95% CI 0.73 to 0.83, p<0.0001), but oral calcium channel antagonists or angiotensin converting enzyme (ACE) inhibitors did not (odds ratios 1.34, 1.24 to 1.44 and 1.16 1.09-1.24, respectively, p<0.0001 in each case). Oral corticosteroid treatment was associated with enhanced risk (odds ratio 1.78, 1.61 to 1.96). CONCLUSION: Common pathogenetic mechanisms in ciliary and renal tubular epithelia may explain coincidence of glaucoma and systemic hypertension. The choice of cardiovascular treatment, could substantially influence glaucoma incidence, with beta blockade protecting and ACE inhibitors or calcium channel blockers not affecting underlying risk.

Initiation of antihypertensive therapy among new users of cyclooxygenase-2-selective and nonselective NSAIDs.

BACKGROUND: The comparative effects of cyclooxygenase-2- (COX-2) selective inhibitors and nonselective, nonsteroidal anti-inflammatory drugs (NSAIDs) on blood pressure are debated. Clinicians have been concerned about the need for antihypertensive treatment following therapy with these agents. OBJECTIVE: To compare initiation of antihypertensive treatment among new users of the COX-2-selective inhibitor rofecoxib and of nonselective NSAIDs in clinical practice. METHODS: Retrospective cohort study using the MediPlus (UK) database that covers 1.8 million patients throughout the UK. Patients included were at least 50 years of age, had at least 1 prescription for either diclofenac, ibuprofen, naproxen or rofecoxib (drugs of interest, DOIs), and had no prescription for any NSAID, COX-2 inhibitor, or antihypertensive treatment during the 6 months prior to their first/index prescription date. A subset of patients, classified as chronic and persistent new users, had at least 3 prescriptions of the index prescription DOI and did not switch to another DOI during the 6-month follow-up period. Logistic regression analysis, adjusted for potential predictors, was used to assess initiation of new antihypertensive treatment. RESULTS: 18,737 suitable patients were identified (diclofenac 7,861, ibuprofen 8,423, naproxen 1,556 and rofecoxib 897). Those using rofecoxib were older and more likely to be female than those using NSAIDs. During the 6 months following the index prescription, 7.0% of all new users and 11.5% of chronic and persistent new users initiated antihypertensive treatment. After adjusting for potential predictors there were no statistically significant differences in the risk of initiating antihypertensive treatment between new or chronic and persistent new users of rofecoxib, diclofenac, ibuprofen and naproxen (p > 0.05). CONCLUSION: The results of this study did not indicate any significant differences in the initiation of antihypertensive therapy among patients who were prescribed rofecoxib and NSAIDs, even after multiple prescriptions.

Discrepancies between population-based data and adverse reaction reports in assessing drugs as causes of acute pancreatitis.

BACKGROUND: Many drugs are believed, clinically, to cause acute pancreatitis. We used information held on the UK General Practitioner Research Database to compare risks for drugs for which reports of pancreatitis were common or uncommon. METHODS: Drug prescriptions were examined in 3673 patients with acute pancreatitis and in matched controls. Odds ratios were calculated for recent (1-90 days before the episode), past (91-360 days before the episode) or continuing (prescription in both periods) use. RESULTS: Odds ratios were markedly increased for recent antisecretory use in non-ulcer patients only [all H2-antagonists, 12.4 (9.5-16.4); all proton pump antagonists, 9.3 (6.6-13.0)], with smaller increases for past [3.1 (2.5-3.7) and 3.5 (2.6-4.6), respectively] and continuing [2.6 (2.2-3.1) and 3.7 (2.9-4.7), respectively] use in patients without ulcer. Recent users of mesalazine showed a markedly increased risk [9.0 (1.8-44.6)], with smaller increases in past and continuing users [4.5 (1.3-16.0) and 2.5 (1.2-5.0), respectively]. Odds ratios for other drugs, suspect or not, were modestly increased, irrespective of whether the use was recent, past or continuing. The presence of gall-stones was not associated with a modified risk. CONCLUSIONS: Mesalazine, azathioprine and antisecretory drugs in non-ulcer subjects may increase the risk of pancreatitis, but warnings of drug-induced pancreatitis are generally not accompanied by increased population risks.

Non-steroidal anti-inflammatory drugs: overall risks and management. Complementary roles for COX-2 inhibitors and proton pump inhibitors.

Non-steroidal anti-inflammatory drugs (NSAIDs) are well recognised as causing peptic ulceration and ulcer complications. However, several critical issues, including the amount of both gastrointestinal and non-gastrointestinal disease affected by NSAIDs, their interaction with ancillary risk factors, and how to optimise management in subgroups, remain poorly understood. In this article, strategies for subgroups that take account of non-specific gastrointestinal risks, minimisation of residual risk, and the importance of non-gastrointestinal toxicity are suggested, and areas for research identified.

Dose-response relationships between individual nonaspirin nonsteroidal anti-inflammatory drugs (NANSAIDs) and serious upper gastrointestinal bleeding: a meta-analysis based on individual patient data.

AIMS: To define by amalgamation of data obtained in contemporaneous case-control studies, the risks associated with individual nonaspirin nonsteroidal anti-inflammatory drugs (NANSAIDs) according to doses used. METHODS: Meta-analysis of individual patient data from three retrospective case-control studies using similar data collection protocols was carried out in hospitals in Catalonia, England, Scotland and Sweden. 2472 cases of upper gastrointestinal bleeding and 5877 controls were studied. Main outcome measures were risks associated with individual NANSAIDs according to dose used and the period of time for which they were given. RESULTS: Ibuprofen showed the lowest odds ratio (OR = 1.7; 95% confidence interval 1.1, 2.5), followed by diclofenac (4.9; 3.3, 7.1), indomethacin (6.0; 3.6, 10.0), naproxen (9.1; 6.0-13.7), piroxicam (13.1; 7.9-21.8) and ketoprofen (34.9; 12.7, 96.5). Striking dose-response relationships were seen with four to eight-fold increases in risk within conventionally used dose ranges for all except ketoprofen, where numbers were too few to allow dose analysis. Across the class, risk was highest during the first week of use (11.7; 6.5, 21.0), decreased thereafter with continuing use (5.6; 4.6, 7.0), and fell to 3.2 (2.1, 5.1) 1 week after discontinuing use. Concurrent use of more than one NANSAID substantially increased risk. CONCLUSIONS: The risk of upper gastrointestinal bleeding with NANSAIDs varies twenty-fold depending on the drug, and by three to seven-fold depending on the dose chosen. Risk is maximal during the first week and decreases thereafter. Paracetamol (acetaminophen) is not associated with upper gastrointestinal bleeding at any dose and should be the first-line analgesic wherever possible.

Sulphasalazine and mesalazine: serious adverse reactions re-evaluated on the basis of suspected adverse reaction reports to the Committee on Safety of Medicines.

BACKGROUND: 5-aminosalicylates are extensively prescribed for the treatment of ulcerative colitis but have a wide range of described adverse effects. AIMS: To determine whether serious adverse effect profiles differ for sulphasalazine and mesalazine. METHODS: Analysis of suspected serious adverse reactions reported to the Committee on Safety of Medicines of the UK in 1991-1998. Adverse effect profiles were categorised for interstitial nephritis, pancreatitis, serious skin reactions, hepatitis and hepatic failure, and blood dyscrasias. Report rates were calculated using prescribing data from the Department of Health and compared for mesalazine and sulphasalazine. Further analysis was undertaken for sulphasalazine according to disease indication of inflammatory bowel disease or rheumatoid arthritis. RESULTS: A total of 4.7 million prescriptions were dispensed for sulphasalazine compared with 2.8 million for mesalazine. Interstitial nephritis was only described for mesalazine, with 11.1 reports per million prescriptions. Pancreatitis was reported seven times as frequently for mesalazine (7.5 per million prescriptions) compared with sulphasalazine (1.1 per million prescriptions) (odds ratio (OR) 7.0; 95% confidence interval (CI) 2.6-18.6; p<0.001). There were no reports of serious skin disorders in patients prescribed sulphasalazine for inflammatory bowel disease. Blood dyscrasias were reported significantly more often in patients receiving sulphasalazine for rheumatoid arthritis than for inflammatory bowel disease (OR 5.31; 95% CI 2.6-11.0; p<0.001), and there was a similar trend for hepatic disorders. CONCLUSIONS: Spontaneous reports suggest that within the five sets of disorders considered, there is no evidence to indicate a safety advantage of mesalazine over sulphasalazine in the treatment of inflammatory bowel disease. Pancreatitis and interstitial nephritis appear significantly more common with mesalazine, and advice on renal monitoring in patients who receive mesalazine may need reinforcing.

Oestrogen-induced apoptosis in colonocytes expressing oestrogen receptor beta.

Epidemiological studies of postmenopausal hormone replacement therapy show a reduction in the risk of developing colon cancer, and animal studies using 17beta-oestradiol (E(2)) demonstrate a decreased incidence of chemically-induced colon cancer. Using the colon cancer cell line, COLO205, we found that E(2) induced a dose-dependent increase in DNA fragmentation and nuclear condensation, significant effects being seen at 10(-12 )mol/l. BSA-conjugated E(2), which cannot enter cells, was ineffective at inducing apoptosis in COLO205 cells, indicating that E(2) was not acting through a cell-membrane receptor. E(2) did not induce the morphological changes characteristic of differentiation. Using RT-PCR we found that the oestrogen receptor alpha (ERalpha) isoform was absent in the COLO205 cell line in contrast to CACO-2, LoVo and SW620 cells, but mRNAs for ERbeta1, -beta2, -beta5 and -beta6 isoforms were detected. Western immunoblotting results showed full-length ERbeta protein but no detectable ERalpha in COLO205 cells. In normal human colon tissue samples immunoreactive ERbeta was found but ERalpha was barely detectable. Expression of ERbeta was lost in some colon cancer specimens and reduced in others. We conclude that E(2), through ERbeta, at concentrations found during replacement therapy, may inhibit the development of colon cancer by inducing apoptosis.

Ketorolac, diclofenac, and ketoprofen are equally safe for pain relief after major surgery.

BACKGROUND: Ketorolac is approved for the relief of postoperative pain but concerns have been raised over a possible risk of serious adverse effects and death. Two regulatory reviews in Europe on the safety of ketorolac found the data were inconclusive and lacked comparison with other non-steroidal anti-inflammatory drugs. The aim of this study was to compare the risk of serious adverse effects with ketorolac vs diclofenac or ketoprofen in adult patients after elective major surgery. METHODS: This prospective, randomized multicentre trial evaluated the risks of death, increased surgical site bleeding, gastrointestinal bleeding, acute renal failure, and allergic reactions, with ketorolac vs diclofenac or ketoprofen administered according to their approved parenteral and oral dose and duration of treatment. Patients were followed for 30 days after surgery. RESULTS: A total of 11,245 patients completed the trial at 49 European hospitals. Of these, 5634 patients received ketorolac and 5611 patients received one of the comparators. 155 patients (1.38%) had a serious adverse outcome, with 19 deaths (0. 17%), 117 patients with surgical site bleeding (1.04%), 12 patients with allergic reactions (0.12%), 10 patients with acute renal failure (0.09%), and four patients with gastrointestinal bleeding (0.04%). There were no differences between ketorolac and ketoprofen or diclofenac. Postoperative anticoagulants increased the risk of surgical site bleeding equally with ketorolac (odds ratio=2.65, 95% CI=1.51-4.67) and the comparators (odds ratio=3.58, 95% CI=1.93-6.70). Other risk factors for serious adverse outcomes were age, ASA score, and some types of surgery (plastic/ear, nose and throat, gynaecology, and urology). CONCLUSION: We conclude that ketorolac is as safe as ketoprofen and diclofenac for the treatment of pain after major surgery.

Sulphide-induced energy deficiency in colonic cells is prevented by glucose but not by butyrate.

BACKGROUND: In ulcerative colitis, hydrogen sulphide is postulated to impair colonocyte butyrate metabolism, leading to cellular energy deficiency and dysfunction. AIMS: To determine the effects of sulphide exposure on butyrate metabolism and adenosine triphosphate levels of HT29 colonic epithelial cancer cells, and to establish whether energy deficiency can be prevented by increased butyrate concentrations or the presence of glucose. METHODS: HT29 cells were maintained in medium containing 3 mM butyrate, 5 mM glucose, or both substrates. Oxidation rates were measured by 14CO2 release from 14C-labelled substrates. Cellular adenosine triphosphate was assayed using the luciferin/luciferase chemiluminescent method. The effects of sulphide (0-5 mM) on substrate oxidation and adenosine triphosphate levels and of increasing butyrate concentration (0-30 mM) with sulphide were observed. RESULTS: HT29 cells showed similar energy substrate usage to primary colonocyte cultures. Sulphide exposure inhibited butyrate oxidation and led to a reduction in cellular adenosine triphosphate. This fall was prevented by co-incubation with glucose, but not by increasing concentrations of butyrate. CONCLUSIONS: HT29 cells utilize butyrate as an energy substrate and represent a useful in vitro model of the effects of sulphide on colonocytes. Sulphide inhibits butyrate oxidation and leads to demonstrable energy deficiency, prevented by the presence of glucose but not by increased butyrate concentrations.

Mucosal protection against sulphide: importance of the enzyme rhodanese.

BACKGROUND: Hydrogen sulphide (H(2)S) is a potent toxin normally present in the colonic lumen which may play a role in ulcerative colitis (UC). Two enzymes, thiol methyltransferase (TMT) and rhodanese (RHOD), are thought to be responsible for sulphide removal but supportive evidence is lacking. AIMS: To determine the distribution of TMT and RHOD in different sites throughout the gastrointestinal tract and their efficacy as detoxifiers of H(2)S. METHODS: Enzyme activities were measured in normal tissue resected from patients with cancer. TMT and RHOD activities were determined using their conventional substrates, 2-mercaptoethanol and sodium thiosulphate, respectively. For measurement of H(2)S metabolism, sodium sulphide was used in the absence of dithiothreitol. Thiopurine methyltransferase (TPMT), which in common with TMT methylates sulphydryl groups but is not thought to act on H(2)S, was also examined. RESULTS: TMT, RHOD, and TPMT activities using their conventional substrates were found throughout the gastrointestinal tract with highest activity in the colonic mucosa. When H(2)S was given as substrate, no reaction product was found with TMT or TPMT but RHOD was extremely active (Km 8.8 mM, Vmax 14.6 nmol/mg/min). Incubation of colonic homogenates with a specific RHOD antibody prevented the metabolism of H(2)S, indicating that RHOD is responsible for detoxifying H(2)S. A purified preparation of RHOD also detoxified H(2)S. CONCLUSIONS: RHOD, located in the submucosa and crypts of the colon, is the principal enzyme involved in H(2)S detoxication. TMT does not participate in the detoxication of H(2)S.