Interferon-gamma released from omental adipose tissue of insulin-resistant humans alters adipocyte phenotype and impairs response to insulin and adiponectin release

BACKGROUND

Inflammatory factors derived from adipose tissue have been implicated in mediating insulin resistance in obesity. We sought to identify these using explanted human adipose tissue exposed to innate and adaptive immune stimuli.

METHODS

Subcutaneous and omental adipose tissue from obese, insulin-resistant donors was cultured in the presence of macrophage and T-cell stimuli, and the conditioned medium tested for its ability to inhibit insulin-stimulated glucose uptake into human Simpson-Golabi-Behmel Syndrome (SGBS) adipocytes. The nature of the inhibitory factor in conditioned medium was characterized physicochemically, inferred by gene microarray analysis and confirmed by antibody neutralization.

RESULTS

Conditioned medium from omental adipose tissue exposed to a combination of macrophage- and T-cell stimuli inhibited insulin action and adiponectin secretion in SGBS adipocytes. This effect was associated with a pronounced change in adipocyte morphology, characterized by a decreased number of lipid droplets of increased size. The bioactivity of conditioned medium was abolished by trypsin treatment and had a molecular weight of 46 kDa by gel filtration. SGBS adipocytes exposed to a bioactive medium expressed multiple gene transcripts regulated by interferon-gamma (IFN-γ). Recombinant human IFN-γ recapitulated the effects of the bioactive medium and neutralizing antibody against IFN-γ but not other candidate factors abrogated medium bioactivity.

CONCLUSIONS

IFN-γ released from inflamed omental adipose tissue may contribute to the metabolic abnormalities seen in human obesity.

Weight loss after laparoscopic adjustable gastric band and resolution of the metabolic syndrome and its components

BACKGROUND

Substantial weight loss in the setting of obesity has considerable metabolic benefits. Yet some studies have shown improvements in obesity-related metabolic comorbidities with more modest weight loss. By closely monitoring patients undergoing bariatric surgery, we aimed to determine the effects of weight loss on the metabolic syndrome and its components and determine the weight loss required for their resolution.

METHODS

We performed a prospective observational study of obese participants with metabolic syndrome (Adult Treatment Panel III criteria) who underwent laparoscopic adjustable gastric banding. Participants were assessed for all criteria of the metabolic syndrome monthly for the first 9 months, then 3-monthly until 24 months.

RESULTS

There were 89 participants with adequate longitudinal data. Baseline body mass index was 42.4±6.2 kg m^-2 with an average age was 48.2±10.7 years. There were 56 (63%) women. Resolution of the metabolic syndrome occurred in 60 of the 89 participants (67%) at 12 months and 60 of the 75 participants (80%) at 24 months. The mean weight loss when metabolic syndrome resolved was 10.9±7.7% total body weight loss (TBWL). The median weight loss at which prevalence of disease halved was 7.0% TBWL (17.5% excess weight loss (EWL)) for hypertriglyceridaemia; 11% TBWL (26.1-28% EWL) for high-density lipoprotein cholesterol and hyperglycaemia; 20% TBWL (59.5% EWL) for hypertension and 29% TBWL (73.3% EWL) for waist circumference. The odds ratio for resolution of the metabolic syndrome with 10-12.5% TBWL was 2.09 (P=0.025), with increasing probability of resolution with more substantial weight loss.

CONCLUSIONS

In obese participants with metabolic syndrome, a weight loss target of 10-12.5% TBWL (25-30% EWL) is a reasonable initial goal associated with significant odds of having metabolic benefits. If minimal improvements are seen with this initial target, additional weight loss substantially increases the probability of resolution.

Axis I disorders in adjustable gastric band patients: the relationship between psychopathology and weight loss

BACKGROUND

Bariatric surgery candidates have higher rates of co-morbid psychological illnesses than those in the general population. The effect of weight loss on these illnesses is unclear.

METHODS

This prospective observational study explored psychiatric co-morbidities and weight loss outcomes in 204 gastric banding surgery candidates. Psychiatric co-morbidities were assessed prior to surgery and 2 years post-surgery. One hundred and fifty patients (74%) completed assessments at both time points.

RESULTS

At baseline, 39.7% of the patients met the criteria for a current axis I disorder as defined by the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV). Mood disorders were the most frequent (26.5%), followed by anxiety disorders (15.2%) and binge eating disorder (13.2%). Preoperative psychopathology predicted clinical psychopathology at 2 years. No preoperative or post-operative axis I disorder was significantly related to weight loss at 2 years. The frequency of current axis I disorders decreased significantly from 39.7% preoperatively to 20% 2 years post-surgery.

CONCLUSIONS

The point prevalence of psychopathology in this sample of Australian bariatric candidates is high. Psychopathology, preoperatively and at 2 years of follow-up, was not associated with weight loss at 2 years.

Controversies in bariatric surgery

BACKGROUND

There are many controversies related to bariatric surgery. This review explores selected areas.

METHODS

A combination of randomized clinical trials (RCTs), systematic reviews and expert opinion have been brought together to highlight areas of importance or conflict.

RESULTS AND CONCLUSION

Metabolic surgery is an increasingly preferred term rather than bariatric or obesity surgery. Reporting should be standardized to include appropriate weight measures, valid disease measures and data on loss to follow-up. There are many putative mechanisms of effect of key bariatric procedures, but satiety and early satiation appear central. Weight loss must be durable. Long-term outcome studies (more than 10-year follow-up) show that biliopancreatic diversion is most effective, with 72 per cent excess weight loss (EWL). Roux-en-Y gastric bypass and laparoscopic adjustable gastric banding (LAGB) are equally effective, with 54 per cent EWL. There are no long-term data on vertical sleeve gastrectomy. Type II diabetes is a common and serious disease, usually associated with increased weight. Multiple RCTs have shown that bariatric surgery provides clear benefits over continuing with non-surgical therapies. The earlier the treatment, the more likely and durable will be the remission. Bariatric surgery should be available to all who are obese (body mass index over 30 kg/m(2) ). LAGB, a safe, effective, reversible outpatient procedure, is the author's preferred primary option.

GPR119 regulates genetic markers of fatty acid oxidation in cultured skeletal muscle myotubes

Gene knockout and agonist studies indicate that activation of the G protein-coupled receptor, GPR119, protects against diet-induced obesity and insulin resistance. It is not known if GPR119 activation in skeletal muscle mediates these effects. To address this uncertainty, we measured GPR119 expression in skeletal muscle and determined the effects of PSN632408, a GPR119 agonist, on the expression of genes and proteins required for fatty acid and glucose oxidation in cultured myotubes. GPR119 expression was readily detected in rat skeletal muscle and mRNAs were induced by 12 weeks of high-fat feeding. Treatment of cultured mouse C₂C₁₂ myotubes with 5 μM PSN632408 or 0.5 mM palmitate reduced expression of mRNAs encoding fatty acid oxidation genes to similar extents. More so, treatment with PSN632408 decreased AMPKα (Thr172 phosphorylation) activity in the absence of palmitate and ACC (Ser79 phosphorylation) activity in the presence of palmitate. In human primary myotubes PSN632408 decreased expression of PDK4 and AMPKα2 mRNA in myotubes derived from obese donors. These data suggest GPR119 activation in skeletal muscle may impair fatty acid and glucose oxidation.

Brown adipocyte progenitor population is modified in obese and diabetic skeletal muscle

Brown adipose tissue mitochondria express the unique thermogenic uncoupling protein-1. Recently, brown adipocyte progenitors have been identified in the CD34+ cell population of human skeletal muscle. The aims of this study were firstly to determine if obesity and diabetes have altered amounts of muscle brown adipocyte progenitors and, secondly, to establish if the latter are correlated with clinical parameters of obesity and diabetes. Body mass index (BMI), plasma glucose, insulin, cholesterol and triglycerides as well as homeostasis model assessment were measured in lean (n=10), obese (n=18) and obese-diabetic (n=15) subjects and muscle biopsies were taken from the rectus abdominus. CD34 being also expressed on endothelial cells, we measured CD31, another endothelial marker, and expressed the brown adipocyte progenitors, as the CD34/CD31 mRNA ratio. The latter was significantly reduced in the obese vs lean subjects suggesting a smaller pool of brown adipocyte progenitors. More strikingly, for lean and obese subjects negative correlations were observed between the CD34/CD31 mRNA ratios and BMI, fasting insulin levels and homeostasis model assessment. These correlations highlight the potential physiological relevance of the muscle CD34/CD31 mRNA ratio.

Night eating syndrome and nocturnal snacking: association with obesity, binge eating and psychological distress

OBJECTIVE

Night eating syndrome (NES) is characterized by a time-delayed pattern of eating relative to sleep, where most food is consumed in the evening and night. This study aimed to investigate the clinical significance of NES and nocturnal snacking by exploring the relationship between NES and (1) obesity, (2) binge eating disorder (BED) and (3) psychological distress.

SUBJECTS

One hundred and eighty bariatric surgery candidates, 93 members of a non-surgical weight loss support group and 158 general community respondents (81 males/350 females, mean age: 45.8+/-13.3 years, mean body mass index (BMI): 34.8+/-10.8 and BMI range: 17.7-66.7).

METHODS

NES diagnosis required within the previous 3 months: (1) no appetite for breakfast, (2) consumption of > or =50% of daily energy after 1900 hours and (3) sleep difficulties > or =3 nights/week. Nocturnal snacking (awakening to eat) was recorded. Validated questionnaires assessed BED, symptoms of depression, appearance dissatisfaction (AD) and mental health-related quality of life (MHQoL). NES and binge eating (BE) (> or =1 episode/week) were confirmed by interview.

RESULTS

NES criteria were met by 11.1% of the total cohort. Across all groups, BE (P=0.001), BMI (P=0.003) and male gender (P=0.013) explained 10% of NES variance. Individuals with co-morbid NES and BE reported similarly elevated psychological distress as other binge eaters. NES alone was not associated with psychological distress. Those with NES who consumed nocturnal snacks reported poorer MHQoL (P=0.007) and greater depressive symptoms (P=0.039) and hunger (P=0.013) than others with NES. Low MHQoL (P=0.007) and male gender (P=0.022) explained 27% of the variance in the nocturnal snacking group.

DISCUSSION

In this study, NES was positively associated with BMI, BE and male gender. Elevated psychological distress was only apparent in those who consumed nocturnal snacks. Further characterization and understanding of the clinical significance of NES and nocturnal snacking is required.

Changes in fat-free mass during significant weight loss: a systematic review

OBJECTIVE

To identify the proportion of weight lost as fat-free mass (FFM) by various weight loss interventions.

METHODS

Medline and Embase were systematically searched for reliable measurements of FFM before and after weight loss of >10 kg and eligible data were pooled. In a fixed effect model of % FFM loss/weight loss (%FFML), linear regression analysis was used to determine the influence of degree of caloric restriction, exercise, magnitude of weight loss, initial body mass index (BMI) and type of surgery.

RESULTS

Data were included from 26 cohorts treated with dietary and behavioral interventions and 29 cohorts of bariatric surgery patients. The degree of caloric restriction was positively associated with %FFML (r (2)=0.31, P=0.006) and in three randomized controlled trials exercise was shown to decrease %FFML. Compared with laparoscopic adjustable gastric banding (LAGB), biliopancreatic diversion (BPD) and roux en Y gastric bypass (RYGB) caused greater log(e) (natural log) %FFML (r (2)=0.453, P<0.001). Differences in log(e) %FFML between surgical procedures were independent of initial BMI and magnitude of weight loss.

CONCLUSIONS

The degree of caloric restriction, exercise and rate of weight loss influence the proportion of weight lost as FFM after non-surgical interventions. For surgical interventions, BPD and RYGB result in greater %FFML than LAGB.

Polysomnography before and after weight loss in obese patients with severe sleep apnea

OBJECTIVE

While obstructive sleep apnea (OSA) is strongly related to obesity, few studies have examined polysomnographic (PSG) changes with major weight loss. We examined the effect of weight loss following laparoscopic adjustable gastric banding (LAGB) on the PSG changes in patients with severe OSA. In addition, we studied daytime sleepiness, the metabolic syndrome and quality of life (QOL).

METHODS

A prospective study was conducted of 25 severely obese patients (17 men, eight women) with paired diagnostic PSG, biochemical and questionnaire studies, the first prior to LAGB and the second at least 1 y later. Subjects with a baseline apnea-hypopnea index (AHI) >25/h were included.

RESULTS

Subject baseline age was 44.7 y, weight 154 kg and body mass index 52.7 kg/m(2). The second PSG study was conducted 17.7+/-10 (range 12-42) months after surgery and mean percentage of excess loss and weight loss were 50.1+/-15% (range 24-80%) and 44.9+/-22 kg (range 18-103 kg), respectively. There was a significant fall in AHI from 61.6+/-34 to 13.4+/-13, improved sleep architecture with increased REM and stage III and IV sleep, daytime sleepiness, as measured by Epworth Sleepiness Scale, of 13+/-7.0 to 3.8+/-3.0, and fewer patients requiring nasal continuous positive airways pressure (CPAP). There were also major improvements in the metabolic syndrome, QOL, body image and fewer symptoms of depression (P<0.05 for all).

CONCLUSION

Weight loss provides major improvement or resolution of OSA and CPAP requirements. It also reduces daytime sleepiness, and improves the metabolic syndrome and QOL. LAGB placement should be considered a broadly effective therapy for sleep apnea in the severely obese patient.

Body composition changes following laparoscopic gastric banding for morbid obesity

Most reports of outcome following obesity surgery report weight and co-morbidity changes only. We studied body composition changes in 17 adult patients (15 F, 2 M, age 43+/-2 years, range 28-58 years), with morbid obesity (initial BMI 40.4+/-4.9 kg/m(2), range 34.7-48.8) who were managed surgically by laparoscopically inserting an adjustable gastric band. Body composition was studied before and after surgery (mean interval of 909+/-51 days, range 441-1155 days) using anthropometry (abdominal circumference, AC, sum of four skinfold thicknesses, SFSUM), whole-body potassium counting (TBK), in vivo neutron activation analysis total body nitrogen (TBProtein) and whole-body dual-energy ray absorptiometry (total body percent fat TBF%, and total body bone mineral density TBBMD). Weight loss over the study period was 23.4+/-2.5 kg. ( p<0.0003) with an AC reduction of 20.0+/-4.5 cm ( p<0.008). Both SFSUM and TBF% were significantly reduced ( p<0.02 and p<0.0005 respectively). Both TBK and TBProtein after normalization for sex and height, were significantly ( p<0.0054 and p<0.001 respectively) reduced, but the ratio of loss of fat mass to fat-free mass, at 4.4:1 was usual for weight loss, and there was no significant changes in the ratio of potassium to protein. TBBMD, after normalization relative to a young same sex adult, was not significantly changed. In this group of patients, most of the substantial weight loss over a 2- to 3-year period was due to loss of fat mass, with relatively less reduction in the components of fat-free mass. Adjustable laparoscopic gastric banding induces fat loss without significant other deleterious effects on body composition.

Improvements in insulin sensitivity and beta-cell function (HOMA) with weight loss in the severely obese. Homeostatic model assessment

AIMS

To examine the effect of weight loss on insulin sensitivity and beta-cell function in severely obese subjects of varying glycaemic control.

PATIENTS AND METHODS

Subjects were 254 (F:M 209:45) patients having adjustable gastric banding for severe obesity, with paired biochemical data from before operation and at 1-year follow up. The homeostatic model assessment method was used to calculate insulin sensitivity (HOMA%S) and beta-cell function (HOMA%B). Subjects were grouped by diabetic status and by pre-weight loss HbA1c.

RESULTS

Initial mean (sd) weight and body mass index were 128 (26) kg and 46.2 (7.7) kg/m2, respectively, and at 1-year were 101 (22) kg and 36.4 (6.7) kg/m2. The percentage of excess weight lost (%EWL) was 44.3 (14)%. HOMA%S improved from 37.5 (16)% presurgery to 62 (25)% (P < 0.001). %EWL was the only predictor of HOMA%S improvement (r = 0.28, P < 0.001). Subjects with normal fasting glucose, impaired fasting glucose and Type 2 diabetes had a fall, no change and increase in HOMA%B, respectively. The improvement in HOMA%B in subjects with diabetes (n = 39) was inversely related to the time with diabetes (r = -0.36, P = 0.02). In non-diabetic subjects the HOMA%S-HOMA%B relationship was favourably altered with weight loss, so that for any given HOMA%S there was an increase in HOMA%B (f = 11.8, P = 0.001). This improvement in HOMA%B was positively related to %EWL (r = 0.25, P = 0.019).

DISCUSSION

There are beneficial changes in both insulin sensitivity and beta-cell function with weight loss. Modern laparoscopic obesity surgery may have an important early role in the management of Type 2 diabetes in obese subjects.

Reduced plasma homocysteine in obese red wine consumers: a potential contributor to reduced cardiovascular risk status

BACKGROUND

Moderate alcohol consumption is associated with improved vascular risk profile and decreased mortality in the middle aged. An elevated homocysteine concentration is an independent risk factor for cardiovascular disease.

OBJECTIVE

To examine the relationship between alcohol consumption and homocysteine concentrations in severely obese patients (body mass index (BMI)>35).

DESIGN

A careful alcohol history was obtained from 350 (male:female 1:5) consecutive patients as part of preoperative assessment for surgical treatment of obesity. Data were obtained concerning amount, frequency, timing and type of alcohol consumption. Fasting homocysteine, serum folate and vitamin B(12) concentrations were measured. Differences between groups were assessed using Student t-test, and ANOVA. Linear regression was used to assess factors influencing homocysteine concentration.

RESULTS

There is a U-shaped relationship between alcohol consumption and homocysteine concentrations, with light to moderate consumption being associated with lower concentrations. Those consuming <100 g/week (n=165) of alcohol had geometric mean (95% CI of mean) serum homocysteine concentrations of 8.5 (8.2-8.9) micromol/l compared with 9.5 (9.1-9.9) micromol/l for non or rare consumers (n=153; P=0.001). The lower concentrations of homocysteine in regular consumers were associated with higher folate concentrations of 9.4 (8.6-10.2) ng/ml when compared with non-consumers 7.5 (7.1-7.8) ng/ml (P=0.001). Red wine consumers (n=42) had lower fasting concentrations of homocysteine 7.8 (7.5-8.1) micromol/l compared with 153 non-consumers 9.4 (9.0-9.8) micromol/l (P<0.001), 82 beer and spirit consumers 9.0 (8.4-9.7) micromol/l (P=0.005) and 73 white wine consumers 8.8 (8.2-9.4 micromol/l (P=0.013). Red wine consumption was an independent predictor for lower homocysteine concentrations.

CONCLUSION

Mild to moderate alcohol consumption, especially red wine consumption, in obese subjects is associated with lower fasting homocysteine concentrations. This may reduce cardiovascular risk and help explain the 'French paradox'.

Inhibition of beta-catenin translocation in rodent colorectal tumors: a novel explanation for the protective effect of nonsteroidal antiinflammatory drugs in colorectal cancer

In a rodent colorectal cancer model, nonsteroidal antiinflammatory drugs reduce tumor mass by increasing the rate of tumor cell apoptosis and decreasing proliferation. We have examined beta-catenin as a potential target for these agents in colorectal cancer. Carcinogen-treated rats were treated for 23 weeks with a range of nonsteroidal antiinflammatory drugs. Control animals received vehicle alone. Intracellular beta-catenin was examined using immunohistochemistry. In tumors from untreated animals, staining was seen in the cytoplasm and nucleus (median 24% of nuclei). The frequency of nuclear beta-catenin staining correlated directly with the volume of tumor and inversely with the rate of apoptosis. In tumors from treatment groups, the cytoplasmic staining for beta-catenin was unchanged; however, nuclear staining was absent except in the celecoxib group, where it was reduced to a median of 14%. Colorectal tumors from animals treated with NSAIDs show reduced levels of nuclear beta-catenin immunoreactivity.

Quality of life after lap-band placement: influence of time, weight loss, and comorbidities

OBJECTIVE

To assess the quality of life (QOL) in severely obese subjects before and after Lap-Band gastric restrictive surgery and identify factors that may influence change.

RESEARCH METHODS AND PROCEDURES

All patients, over a 3-year period, attending for preoperative assessment (n = 459) or annual review after surgery (n = 641) have completed the Short Form-36 (SF-36) health survey. Eight domain and physical component summary (PCS) and mental component summary (MCS) scores were calculated. Scores were analyzed in groups based on time after surgery and compared with community normal (CN) values. Paired preoperative and 1-year scores (n = 218) data were used to find predictors of QOL change.

RESULTS

All preoperative mean scores (n = 459) were lower than CN values, with greater impairment in the PCS (36.8 +/- 9.5 vs. CN: 51.3 +/- 8.3, p < 0.001) than in the MCS (45.7 +/- 8.2 vs. CN: 48.8 +/- 9.5, p < 0.001) scores. After 1 year, scores were closer to CN scores (PCS: 52.4 +/- 8.2 and MCS: 48.4 +/- 7.7), and these remained closer for 4 years. Preoperative obesity comorbidity, especially physical disability, was the best predictor of poor preoperative SF-36 scores and of improvement in scores at 1 year. The percentage of excess weight loss at 1 year (46 +/- 16%) was of little predictive value of improved QOL.

DISCUSSION

Severely obese subjects have poor health-related QOL as measured by the SF-36 health survey. Lap-Band surgery for this group has provided a dramatic and sustained improvement in all measures of the SF-36. Improvement is greater in those with greater preoperative disability, and the extent of weight loss is not a good predictor of improved QOL.

Pregnancy after Lap-Band surgery: management of the band to achieve healthy weight outcomes

BACKGROUND

Severely obese women have higher obstetric risks and poorer neonatal outcomes. Weight loss reduces obstetric risk. The introduction of a laparoscopically-placed adjustable gastric band, a safe and effective method of weight loss, has given us the ability and responsibility to adjust the band in relation to pregnancy.

OBJECTIVE

Our aim was to devise a safe management plan to achieve healthy maternal weight gain (Institute of Medicine 1990) during pregnancy.

METHODS

In a cohort group of 650 patients to have a Lap-Band placement for severe obesity, we have reviewed the management of the band and pregnancy outcomes of all women (n=20) to complete a pregnancy (n=22) with a band in-situ.

RESULTS

All 22 pregnancies were singleton, with no primary caesarean sections (3 for recurring indications). The mean maternal weight gain was 8.3 kg compared with 15.2 kg for the 15 previous pregnancies of women in this group (p<0.05). There was no difference in birth weights. Obstetric complications were minimal, and there were no premature or low birth weight infants. 11 of 15 subjects with active management of the band achieved a maternal weight gain within the advised range compared with only 2 of 7 prior to this.

CONCLUSION

The ability to adjust gastric restriction allows optimal control of maternal weight change in pregnancy and should help avoid the risks of excessive weight change.

Nonalcoholic fatty liver disease: predictors of nonalcoholic steatohepatitis and liver fibrosis in the severely obese

BACKGROUND AND AIMS

Nonalcoholic fatty liver disease (NAFLD) is common in severely obese subjects and can progress to cirrhosis and liver failure. Predicting advanced or progressive disease may help in selecting patients for liver biopsy and assist the development of therapeutic options.

METHODS

Liver biopsies were taken at laparoscopic obesity surgery in 105 consecutive patients. The clinical and biochemical variables were analyzed for correlation with specific histologic features.

RESULTS

Twenty-six patients (25%) were found to have nonalcoholic steatohepatitis (NASH), and 11 (42%) of these had advanced fibrosis. A raised index of insulin resistance (odds ratio [OR] 9.3, 95% confidence interval [CI] 3.4-26), systemic hypertension (OR 5.2, 95% CI 2.0-13.5), and raised alanine aminotransferase (OR 8.6, 95% CI 3.1-23.5) were independent predictors of NASH. A combination of 2 or 3 of these predictors allows a sensitivity of 0.8 and specificity of 0.89 for NASH. Alcohol consumption was associated with a reduction in NASH (OR 0.35, 95% CI 0.12-1.00) and diabetes (OR 0.18, 95% CI 0.047-0.67).

CONCLUSION

Insulin resistance and systemic hypertension, features of the metabolic syndrome, are independently associated with advanced forms of NAFLD. Moderate alcohol consumption seems to reduce the risk of NAFLD in the severely obese, possibly by reducing insulin resistance.

Rat colorectal tumours treated with a range of non-steroidal anti-inflammatory drugs show altered cyclooxygenase-2 and cyclooxygenase-1 splice variant mRNA expression levels

Non-steroidal anti-inflammatory drugs (NSAIDs) reduce tumour mass by increasing the rate of tumour cell apoptosis and decreasing cell proliferation. The classically recognized target for NSAID action are the two isoforms of the cyclooxygenase (COX) gene, which is responsible for prostaglandin production. In the rat, the COX-1 gene expresses an alternatively spliced mRNA COX-1 splice variant (SV) which may, at best, code for a truncated COX-1 protein. Previously, we reported that COX-1SV mRNA is differentially expressed in the ageing stomach. In this study, carcinogen treated rats were treated for 23 weeks with celecoxib, sulindac or sulindac sulfone, while untreated rats received vehicle alone. For each animal, the number and volume of tumour per animal was recorded and histology was performed. Using competitive polymerase chain reaction, we determined whether COX gene expression was altered in colorectal tumours and in regions of adjacent and distant macroscopically normal intestine, from vehicle or NSAID treated rats. In addition, we immunolocalized COX-1 and COX-2 in the same tumour and normal colonic tissue. Tumours from animals treated with vehicle or celecoxib expressed significantly elevated levels of COX-2 mRNA in comparison with the adjacent normal mucosa. In contrast, tumours from sulindac and sulindac sulfone treated rats expressed significantly less COX-2 mRNA than tumours from vehicle treated rats. The expression of COX-1 mRNA remained unchanged in all tissues examined. However, COX-1SV mRNA levels were elevated in colorectal tumours and reduced after NSAID treatment to the levels observed in normal colonic mucosa. Our results indicate that the anti-neoplastic actions of NSAIDs may be attributed to COX dependent and/or COX independent mechanisms of action. We also demonstrate the presence and differential expression of COX-1SV mRNA in colon tumours. COX-1SV mRNA represents 2% of the total COX-1 mRNA expressed and its role in colon cancer remains to be established.

Non-steroidal anti-inflammatory drugs with activity against either cyclooxygenase 1 or cyclooxygenase 2 inhibit colorectal cancer in a DMH rodent model by inducing apoptosis and inhibiting cell proliferation

BACKGROUND

Standard non-steroidal anti-inflammatory drugs (NSAIDs) reduce the risk of colorectal cancer by 40-60% but the mechanism by which this occurs is uncertain. Selective cyclooxygenase 2 inhibitors are potentially ideal chemopreventive agents as they are less toxic than standard NSAIDs. No study has compared the efficacy of these drugs at clinically relevant doses in a tumour model.

AIMS

To assess the efficacy of a range of NSAIDs with varying activity against the two cyclooxygenase isoforms in a rodent colorectal carcinogen model at anti-inflammatory doses and to explore the effect of NSAIDs on the rate of tumour apoptosis and proliferation.

METHODS

Colorectal tumours were induced in six week old Sprague-Dawley rats with five weekly doses of 1,2 dimethylhydrazine. Test agents were: indomethacin 2 mg/kg/day, meloxicam 0.6 mg/kg/day, celecoxib 6 mg/kg/day, and sulindac sulphone 40 mg/kg/day. Sulindac was tested at its chemoprotective dose of 20 mg/kg/day. After 23 weeks the number and volume of tumours per animal were recorded. Histology was performed. Tumour apoptosis was quantified on haematoxylin-eosin sections. Tumour proliferation was quantified using an immunohistochemical stain for bromodexoyuridine incorporation.

RESULTS

Test agents effectively reduced the number and volume of tumours developing in the treatment period. In all groups there was an increase in the rate of tumour apoptosis and a reduced rate of proliferation.

CONCLUSIONS

These data suggest that the chemopreventive effect of NSAIDs is independent of their cyclooxygenase inhibitory profile. One potential mechanism for their action may be through induction of apoptosis and inhibition of proliferation.

Combretastatin A4 prodrug study of effect on the growth and the microvasculature of colorectal liver metastases in a murine model

Combretastatin A4P (CA4P) is a prodrug that, in active form, binds to tubulin microtubules of capillary endothelial cells. Studies to date indicate it has significant activity as a specific tumor vascular targeting agent. The goals were to assess the effects of CA4P on tumor growth and microvasculature of colorectal liver metastases in the mouse model, using stereological and histological methods to measure tumor growth, and vascular corrosion casting and laser doppler flowmetry to assess effect on the microvasculature. Continuous s.c. infusion of CA4P produced a major reduction in tumor growth. The percentage of the liver occupied by metastases decreased from 20.55 +/- 13.3% in controls to 7.46 +/- 5.99% in treated animals (P = 0.03). Ultrastructural study of tumor microvasculature after a single dose of CA4P revealed marked effects 1 h after treatment. There was loss of patent microvessels at the normal liver-tumor interface. Central microvascular density was reduced, with constriction and tapering of vessels. CA4P appeared to cause no damage to normal liver tissue or vasculature. Tumor blood flow decreased from 37.6 +/- 13.9% in controls to 24.4 +/- 6.1% in tumors >5 mm in diameter, 1 h after treatment with CA4P (P < 0.03). Quantitative histology of tissue at 6 and 24 h after CA4P treatment showed a significant increase in tumor necrosis (48.7 +/- 21% and 55.5 +/- 19% compared with controls, 20.6 +/- 8%; P = 0.01). Continuous infusion with CA4P causes marked reduction in tumor volume. A single dose of CA4P causes major changes of the tumor microvasculature, reduction of tumor blood flow, and increase in tumor necrosis. CA4P has a potential role in the management of patients with liver metastases.

Pre-operative predictors of weight loss at 1-year after Lap-Band surgery

BACKGROUND

The authors studied a range of preoperative factors for their predictive value of effectiveness of Lap-Band placement, using the percentage of excess weight loss at 1-year as the outcome measure (%EWL1).

METHODS

All factors were measured and recorded prior to surgery. Factors included: patient demographics, family, medical and weight history. Laboratory measures and the responses to the SF-36 Health Survey were also assessed. Factors were assessed for correlation with %EWL1.

RESULTS

The group (N=440, F:M 383:57) had mean age 40.0+/-9.5 years, weight of 126+/-25 kg, and BMI 45.6+/-7.5 kg/m2 pre-operatively. At 1-year follow-up, the group had mean weight 97.6< or =20 kg, BMI 35.6 = 6.3 kg/m2, and %EWL1 45.8< or =17%. Increasing age (R= -0.13, p<0.01) and preoperative BMI (R=-0.22, p<0.001) were significantly associated with less %EWL1 and all other factors were controlled for these before assessing significance. Important factors associated with a lower %EWL1 included: hyperinsulinemia (R=-0.36, p<0.001), insulin resistance (R=-0.33, p<0.001) and disease associated with insulin resistance, poor physical ability, pain, and poor general health responses to the SF-36 Health Survey. Patients who consumed alcohol regularly had a better rate of weight loss (R= 0.23, p<0.005). Factors that had no influence included gender, a history of mental illness and measures of mental health, previous bariatric surgery, and a history of many medical conditions associated with obesity.

CONCLUSION

Important physical factors have been found to influence the rate of weight loss. Those with increased age, pain, physical disability and insulin resistance have a great deal to gain from weight loss. Although this study has identified factors that are associated with less weight loss, we have not found any factor that predicts an unacceptably low weight loss and thus provides a contraindication to Lap-Band placement. The findings of this study allow us to set more realistic goals for the rate of weight loss in specified sub-groups of our patients.

Elevated homocysteine levels with weight loss after Lap-Band surgery: higher folate and vitamin B12 levels required to maintain homocysteine level

OBJECTIVE

To investigate homocysteine levels and their relationship with serum folate and vitamin B12 concentrations with weight loss after the Lap-Band form of gastric restrictive surgery, with the view to minimizing risk.

METHODS

We measured levels of fasting plasma homocysteine (tHcy), folate (serum and RBC) and vitamin B12 in two groups. The study group was 293 consecutive patients at 12 (n=192) or 24 (n=101) months review after surgery. The controls were 244 consecutive patients presenting for this surgery.

RESULTS

The group losing weight had higher geometric mean tHcy levels: 10.4 (95% CI, 9.8-10.8) micromol/l compared with 9.2 (95% CI, 8.9-9.7) in controls (P<0.001). This occurred with higher folate levels and unchanged vitamin B12 levels. Levels of folate and B12 together explained 35% (r (2)) of the homocysteine variance in the weight loss group compared with only 9% (r (2)) in controls (P<0.001). Those taking regular multivitamin supplements had lower tHcy levels: 9.6 (9.1-10.0) micromol/l vs 12.3 (11.4-13.3) in those not taking supplements (P<0.001). A low normal plateau of tHcy levels occurred at levels of folate >15 ng/l and B12)600 ng/ml. A curvilinear relationship exists between these cofactors and tHcy levels, with the dose-response relationship shifted to the right in the weight loss group.

CONCLUSION

This study shows elevated tHcy levels with weight loss, without lower serum folate or vitamin B(12) levels. There is an altered dose-response relationship with higher serum B(12) and folate levels required to maintain recommended tHcy levels. Patients losing weight have significant health benefits; however, they may be at greater risk of vascular events or fetal abnormality in association with raised tHcy levels. Multivitamin supplementation is effective in lowering tHcy levels.

Sleep disturbance and obesity: changes following surgically induced weight loss

BACKGROUND

Obesity causes sleep disturbance and is the most significant risk factor for sleep apnea. Only surgical methods provide substantial sustained weight loss for most severely obese subjects.

OBJECTIVE

To study sleep disturbance in patients undergoing laparoscopic adjustable gastric banding with a commercially available product (Lap-Band).

METHODS

In this study, 313 consecutive patients with severe obesity (body mass index [calculated as weight in kilograms divided by the square of height in meters] >35) completed a preoperative sleep questionnaire and clinical assessment. One hundred twenty-three patients completed the same assessment 12 months after surgery. The characteristics of sleep disturbance and changes in responses to weight loss have been assessed.

RESULTS

There was a high prevalence of significantly disturbed sleep in men (59%) and women (45%), with women less likely to have had their sleep disturbance investigated. Observed sleep apnea was more common in men, but daytime sleepiness was not affected by sex. Waist circumference was the best clinical measure predicting observed sleep apnea (R = 0.36; P<.001). The group lost an average of 48% (SD, 16%) of excess weight by 12 months. There was a significant improvement in the responses to all questions at follow-up, with habitual snoring reduced to 14% (preoperative value, 82%), observed sleep apnea to 2% (preoperative value, 33%), abnormal daytime sleepiness to 4% (preoperative value, 39%), and poor sleep quality to 2% (preoperative value, 39%) (P<.001 for all).

CONCLUSIONS

Obesity-related sleep disorders improve markedly with weight loss. Sustainable weight loss should be a primary aim in the management of severely obese patients with significant sleep disturbance, including sleep apnea. Low-risk laparoscopic obesity surgery should be considered for selected patients with this important comorbidity.

Non-steroidal anti-inflammatory drugs with different cyclooxygenase inhibitory profiles that prevent aberrant crypt foci formation but vary in acute gastrotoxicity in a rat model

BACKGROUND

Standard non-steroidal anti-inflammatory drugs (NSAIDs) reduce the risk of colorectal cancer; however, their use as preventive agents is limited by their inherent toxicity. Drugs that selectively inhibit cyclooxygenase-2 (COX-2) may be useful in this setting as they are supposedly less toxic. No study has directly compared the ability of standard NSAIDs and selective COX-2 inhibitors to inhibit colorectal cancer at clinically relevant doses.

METHODS

Aberrant crypt foci (ACF) were induced in Sprague-Dawley rats by using 1,2-dimethylhydrazine (DMH). Test agents or vehicle were then administered for 3 weeks, twice daily through orogastric gavage. At the end of this period, the number and multiplicity of ACF were determined. The agents tested at equivalent anti-inflammatory doses were: sulindac and indomethacin (standard NSAIDs), meloxicam (selective COX-2 inhibitor), celecoxib (specific COX-2 inhibitor) and sulindac sulfone (no known COX activity). Acute gastrotoxicity of NSAID in rats was compared by using quantitative histology.

RESULTS

All test agents reduced the number of ACF. There was a 42% reduction with indomethacin, 46% with sulindac, 46% with meloxicam, 22% with celecoxib and 36% with sulindac sulfone. Only the COX-2 inhibitors caused no significant gastrotoxicity in rats.

CONCLUSIONS

Cyclooxygenase-2 inhibitors are potentially ideal chemopreventive agents as they inhibit ACF and are not gastrotoxic.

Restoring control: the Acticon Neosphincter artificial bowel sphincter in the treatment of anal incontinence

PURPOSE

Anal incontinence is a socially disabling problem affecting 1 to 2 percent of the population. Anal sphincter replacement is a treatment option if the problem is severe and not amenable to direct repair. The artificial bowel sphincter is an innovative approach. We report the technique for placement and the outcomes which have occurred in an initial series of 13 patients.

METHODS

The Acticon Neosphincter artificial bowel sphincter consists of an inflatable cuff of silicone elastomer placed around the anal canal and connected to a pressure-regulating balloon in the iliac fossa via a control pump placed in the labium or scrotum. Thirteen patients with severe anal incontinence not amenable to other methods were treated. Causes of incontinence included obstetric damage in eight patients, surgical damage in two patients, imperforate anus in two patients, and spina bifida in one patient.

RESULTS

Surgical placement of the device was straightforward, mean operating time was 65 minutes, and median length of stay was 3.6 days. One infection of the perineal wound occurred in the early postoperative period necessitating removal of the device. In two further patients the artificial bowel sphincter was removed because of late infection in one at seven months and because of erosion through the skin in another at three months. The artificial bowel sphincter has been activated in ten patients resulting in full continence to solids and liquids except in one patient with postvagotomy diarrhea who had some leakage of liquids during episodes of diarrhea. The mean (+/- standard deviation) continence score (Cleveland Clinic system; maximal incontinence = 20) changed from 18.7 +/- 1.6 preoperatively to 2.1 +/- 2.6 after activation (P < 0.0001). Quality of life measured using a continence-specific series of up to 39 questions changed from 77 +/- 16 percent of maximal reduction of quality preoperatively to 12 +/- 19 percent postoperatively (P < 0.001).

CONCLUSIONS

The artificial bowel sphincter can be placed without technical difficulty and with low morbidity. Preliminary experience shows full restoration of continence in most patients and ease of use. Longer follow-up is needed to determine the extent of problems with infection, erosion, and mechanical failure.

5-aminosalicyclic acid and olsalazine inhibit tumor growth in a rodent model of colorectal cancer

The ability of 5-aminosalicylic acid and olsalazine to inhibit colonic aberrant crypts and tumors was investigated in 1,2-dimethylhydrazine-treated rats. The effect of these drugs on the rates of tumor apoptosis and proliferation was studied as potential mechanisms for their action. 5-Aminosalicylic acid reduced the number of aberrant crypt foci by over one third, while olsalazine had no effect on this parameter. However, both agents effectively reduced tumor number and load, increased the rate of tumor apoptosis, and reduced the rate of tumor cell proliferation. In conclusion, 5-aminosalicylic acid and olsalazine are both ultimately effective chemopreventive agents in this model; however, only 5-aminosalicylic acid inhibited the formation of aberrant crypt foci. The inhibitory effect of these agents in tumors is related to the inhibition of proliferation and the induction of apoptosis.

Cyclooxygenase-1 and an alternatively spliced mRNA in the rat stomach: effects of aging and ulcers

Prostaglandins play a critical role in gastric mucosal cytoprotection and decrease progressively with age. Cyclooxygenase (COX), the rate-limiting enzyme for prostaglandin synthesis, exists in two isoforms, COX-1 and COX-2. The rat COX-1 gene expresses an alternatively spliced mRNA COX-1 splice variant (SV) that may, at best, code for a truncated COX-1 protein. With the use of competitive PCR, we determined whether COX gene expression was altered in the stomach with increasing age and after gastric ulcer induction. COX-1 mRNA was significantly reduced in the aged, and COX-1SV mRNA was significantly higher in the adults compared with the young and aged stomach. Levels of COX-1 and COX-2 were similarly expressed in the normal stomach. In acute gastric ulcers, only COX-2 mRNA levels were significantly elevated. When ulcers were undergoing healing and repair, COX-1 and COX-2 mRNA levels were significantly elevated. Age-related changes in COX-1 and COX-1SV but not COX-2 mRNA may alter gastric mucosal cytoprotection. Furthermore, COX-1 and COX-2 may both contribute to the healing of a gastric ulcer.

Inhibition of rat colon tumors by sulindac and sulindac sulfone is independent of K-ras (codon 12) mutation

Nonsteroidal anti-inflammatory drug (NSAID) use reduces the risk of colorectal cancer by 40-50%. Previous studies suggest that effective inhibition of colorectal cancer by NSAIDs may be dependent on the presence or absence of a K-ras mutation. This study was aimed at determining the relationship between inhibition of colorectal cancer by sulindac and sulindac sulfone and the presence of activating K-ras mutations in the 1,2-dimethylhydrazine dihydrochloride rat model. Sulindac (20 mg x kg(-1) x day(-1)), sulindac sulfone (40 mg x kg(-1) x day(-1)), or vehicle was administered orally to male Sprague-Dawley rats for a 4-wk period beginning 20 wk after tumor induction. Tumor number and volume were measured before treatment by laparotomy and colonoscopy and again after treatment. Sulindac and sulindac sulfone treatment significantly reduced the number and volume of colorectal tumors compared with control rats. For K-ras (codon 12) mutation detection, frozen tumor tissue was collected at the endpoint. We found K-ras codon 12 mutations in 11 of 21 (52%) control tumors. The proportion of tumors with K-ras mutations in the sulindac-treated group [5 of 8 (62%); odds ratio = 1.51 (95% confidence interval = 0.29, 8.33)] and the proportion of sulindac sulfone-treated tumors [9 of 14 (64%); odds ratio = 1.63 (95% confidence interval = 0.41, 6.66)] were not significantly different from controls. Tumor inhibition did not correlate with K-ras (codon 12) mutation status, which suggests that the mechanism of inhibition of rat colorectal cancer by sulindac and sulindac sulfone is independent of K-ras mutation.

Gastroesophageal reflux in obesity: the effect of lap-band placement

BACKGROUND

Gastroesophageal reflux disease (GERD) is a common condition which is often aggravated by morbid obesity. Lap-Band surgery provides effective weight loss in the morbidly obese. There have been several reports that gastric banding causes or aggravates reflux. The aim of this study was to evaluate the effect of Lap-Band placement on GERD.

METHODS

All patients with a significant history of GERD who had a Lap-Band inserted over a 2-year period were evaluated postoperatively to assess any change in impact on reflux. Resolution required absence of reflux symptoms and no anti-reflux drug therapy.

RESULTS

There were 48 (16%) of 274 consecutive patients with a significant history of reflux esophagitis requiring regular therapy preoperatively. The median age was 39 (range 23-58) and M:F ratio was 5:43. We confirm a high prevalence of GERD in patients with morbid obesity: 17% with symptoms requiring regular therapy (Community Norm 7%). Total resolution of all reflux symptoms occurred in 36 (76%) patients, improvement in 7 (14%), no change in 3 (6%), and aggravation of symptoms in 2 (4%). Patients with severe and moderate symptoms had similar improvement. Resolution or improvement was reported soon after surgery.

CONCLUSION

Rapid and major improvement in symptoms of GERD occurs after Lap-Band placement. The placement of the band probably acts directly to reduce reflux. This result contrasts with reports which have found gastric banding causes or aggravates GERD.

Prediction of outcome in intensive care unit trauma patients: a multicenter study of Acute Physiology and Chronic Health Evaluation (APACHE), Trauma and Injury Severity Score (TRISS), and a 24-hour intensive care unit (ICU) point system

OBJECTIVE

To conduct a multicenter study to validate the accuracy of the Acute Physiology and Chronic Health Evaluation (APACHE) II system, APACHE III system, Trauma and Injury Severity Score (TRISS) methodology, and a 24-hour intensive care unit (ICU) point system for prediction of mortality in ICU trauma patient admissions.

METHODS

The study population consisted of retrospectively identified, consecutive ICU trauma admissions (n = 2,414) from six Level I trauma centers. Probabilities of death were calculated by using logistic regression analysis. The predictive power of each system was evaluated by using decision matrix analysis to compare observed and predicted outcomes with a decision criterion of 0.50 for risk of hospital death. The Youden Index (YI) was used to compare the proportion of patients correctly classified by each system. Measures of model calibration were based on goodness-of-fit testing (Hosmer-Lemeshow statistic less than 15.5) and model discrimination were based on the area under the receiver operating characteristic curve (AUC).

RESULTS

Overall, APACHE II (sensitivity, 38%; specificity, 99%; YI, 37%; H-L statistic, 92.6; AUC, 0.87) and TRISS (sensitivity, 52%; specificity, 94%; YI, 46%; H-L statistic, 228.1; AUC, 0.82) were poor predictors of aggregate mortality, because they did not meet the acceptable thresholds for both model calibration and discrimination. APACHE III (sensitivity, 60%; specificity, 98%; YI, 58%; H-L statistic, 7.0; AUC, 0.89) was comparable to the 24-hour ICU point system (sensitivity, 51%; specificity, 98%; YI, 50%; H-L statistic, 14.7; AUC, 0.89) with both systems showing strong agreement between the observed and predicted outcomes based on acceptable thresholds for both model calibration and discrimination. The APACHE III system significantly improved upon APACHE II for estimating risk of death in ICU trauma patients (p < 0.001). Compared with the overall performance, for the subset of patients with nonoperative head trauma, the percentage correctly classified was decreased to 46% for APACHE II; increased to 71% for APACHE III (p < 0.001 vs. APACHE II); increased to 59% for TRISS; and increased to 62% for 24-hour ICU points. For operative head trauma, the percentage correctly classified was increased to 60% for APACHE II; increased to 61% for APACHE III; decreased to 43% for TRISS (p < 0.004 vs. APACHE III); and increased to 54% for 24-hour ICU points. For patients without head injuries, all of the systems were unreliable and considerably underestimated the risk of death. The percentage of nonoperative and operative patients without head trauma who were correctly classified was decreased, respectively, to 26% and 30% for APACHE II; 33% and 29% for APACHE III; 33% and 19% for TRISS; 20% and 23% for 24-hour ICU points.

CONCLUSION

For the overall estimation of aggregate ICU mortality, the APACHE III system was the most reliable; however, performance was most accurate for subsets of patients with head trauma. The 24-hour ICU point system also demonstrated acceptable overall performance with improved performance for patients with head trauma. Overall, APACHE II and TRISS did not meet acceptable thresholds of performance. When estimating ICU mortality for subsets of patients without head trauma, none of these systems had an acceptable level of performance. Further multicenter studies aimed at developing better outcome prediction models for patients without head injuries are warranted, which would allow trauma care providers to set uniform standards for judging institutional performance.

Prospective study of a laparoscopically placed, adjustable gastric band in the treatment of morbid obesity

BACKGROUND

Surgical control of morbid obesity should benefit from a minimally invasive approach and the ability to adjust the degree of gastric restriction.

METHODS

The Lap-Band adjustable gastric banding system was evaluated prospectively in a consecutive series of 302 patients, and data on perioperative outcome and weight loss pattern at up to 4 years of follow-up are presented. Some 302 patients (89 per cent women; mean age 39 years, mean weight 124 kg) were entered into the study. Laparoscopic placement was used in 277 patients. Previous gastric stapling surgery was the principal reason for an elective open approach.

RESULTS

The incidence of significant early complications was 4 per cent and included two perforations of the stomach after open placement. The mean length of stay after laparoscopic placement was 3.9 days and only one complication (infected reservoir site) occurred in these patients. The principal late complication of prolapse of the stomach through the band occurred in 27 patients (9 per cent). Significant modification of technique and patient care has enabled reduction of this complication in the latter part of the series. Mean(s.d.) excess weight loss was 51.0(17) per cent at 12 months (n = 120), 58.3(20) per cent at 24 months (n = 43), 61.6(2) per cent at 36 months (n = 25) and 682(21) per cent at 48 months (n = 12).

CONCLUSION

The Lap-Band is an effective method for achieving good weight loss in the morbidly obese at up to 4 years of follow-up. Laparoscopic placement has been associated with a short length of stay and a low frequency of complications. The ability to adjust the setting of the device to achieve different degrees of gastric restriction has enabled progressive weight loss throughout the period of study.

Sulindac inhibits colorectal tumour growth, but not prostaglandin synthesis in the rat

We have determined the dose-response relationship between sulindac administration and inhibition of tumour growth in the rat. The effect of tumour-inhibiting doses of sulindac on the production of prostaglandin E in tumours and macroscopically normal colon was then examined. Growth of pre-existing tumours was significantly reduced following administration of sulindac at 0.1 (P=0.004), 1 (P=0.01), 3 (P<0.001) and 10 mg/kg b.d. (P=0.002) for 4 weeks. There was no significant difference in prostaglandin E synthesis between tumours from control rats and those treated with sulindac at either 3 or 10 mg/kg b.d. (P=0.09 and 0.4, respectively). Prostaglandin E synthesis was reduced by 33 and 32% in macroscopically normal tissue from these treatment groups. These data show that sulindac inhibits tumour growth at low doses and do not support a role for the inhibition of prostaglandin synthesis, by sulindac, in the inhibition of tumour growth.

Tiaprofenic acid inhibits mucosal prostaglandin E2 synthesis without delaying experimental gastric ulcer healing

Increasing evidence suggests that non-steroidal anti-inflammatory drugs (NSAID) differ in gastrotoxicity. This study aimed to compare the effects of a short-acting NSAID, tiaprofenic acid, with indomethacin on experimental gastric ulcer healing in a rat model. Similar anti-inflammatory and prostaglandin-inhibitory doses of indomethacin (1 mg/kg) and tiaprofenic acid (2 mg/kg) were administered to rats with acetic acid-induced ulcers. After 2 weeks treatment, rats were killed and ulcer size determined. In addition, histological sections of ulcers were assessed for ulcer contraction and mucosal regeneration. The degree of inhibition of prostaglandin E2 (PGE2) synthesis was 72% at 2 h after tiaprofenic acid and 64% at 2 h after indomethacin administration, respectively. Rats treated with indomethacin for 2 weeks had significantly larger ulcers, both macroscopically and microscopically, than controls. Rats treated with tiaprofenic acid for 2 weeks had ulcers of a similar size to those of controls. Indomethacin-treated ulcers showed a failure in mucosal regeneration. Tiaprofenic acid-treated ulcers had significantly more regeneration than indomethacin-treated ulcers. We conclude that tiaprofenic acid inhibits mucosal prostaglandin levels but does not inhibit experimental gastric ulcer healing. These findings suggest that inhibition of PGE2 synthesis is not the only factor in generating gastrotoxicity and that a shift to low gastrotoxic NSAID may be clinically worthwhile.

Tamoxifen inhibits colorectal cancer metastases in the liver: a study in a murine model

Liver metastases account for over 70% of deaths resulting from colorectal carcinoma, with survival rates varying between 6-18 months. At present, surgical resection offers the only hope for a cure, while chemotherapy, focal destructive techniques and selective internal radiation offer palliative care. Tamoxifen, a non-steroidal anti-oestrogen is primarily known for treating oestrogen receptor (ER)-positive breast cancer. Some studies suggest that tamoxifen may have beneficial effects in malignancies other than breast cancer. These inhibitory effects, which have been shown to be independent of the ER, highlight new mechanisms of therapeutic action. Using an intrasplenic animal model we report the efficacy of tamoxifen on experimental liver metastases. In this model, a dimethyl hydrazine-induced colon carcinoma cell suspension is introduced into the portal circulation via the spleen, which results in secondary tumour deposits in the liver in virtually all animals. Tamoxifen was administered at a dose of 1 mg/kg suspended in 1.0% methyl cellulose. The control group received an equal volume of the vehicle. The reagents were administered s.c. on the day of metastases induction and were continued daily over a 4 week period. The effect of tamoxifen on tumour growth was assessed by stereology and bromodeoxyuridine immunohistochemistry at selected time points. Data were assessed by a multiple analysis of variance where P < 0.05 was considered significant. In the control group the volume of metastases increased from 44 +/- 41 mm3 at day 10 to 517 +/- 380 mm3, 1394 +/- 598 mm3 and 2082 +/- 675 mm3 by days 16, 22 and 28, respectively. Daily administration of tamoxifen exerted an inhibitory effect on tumour growth during the first 3 weeks, recording a volume of 421 +/- 299 mm3 by day 22 compared with the control group at that time point (P = 0.00004). The inhibitory effect diminished by the fourth week recording a tumour volume of 1344 +/- 674 mm3 by day 28. Inhibition of tumour growth at day 22 coincides with a reduction of cells in the S phase of the cell cycle. The percentage of brdU-positive nuclear profiles in metastases of tamoxifen-treated mice at 3 weeks was 35.87 +/- 5.60% compared with 48.01 +/- 3.96% in the control group (P = 0.001). These data suggest that tamoxifen has a potent inhibitory action on colorectal liver metastases by exerting an effect on cell proliferation.

Changes in sulfated macromolecules produced in vivo during normal and indomethacin-delayed ulcer healing in rats

The aim of this study was to examine the synthesis of sulfated glycosaminoglycans during normal healing of experimental acetic acid-induced gastric ulcer in rats and to investigate the effect of indomethacin, a drug known to delay ulcer healing, on this synthesis using an in vivo labelling system. Analysis revealed the presence of two major sulfated species in control tissue; a population of sulfated mucins and glycosaminoglycans, predominantly galactosaminoglycans. The incorporation of [35S]sulfate label into glycosaminoglycans synthesized in the granulation tissue of healing ulcers increased significantly (P < 0.05) as compared to day 0 and control levels at day 14. Treatment of animals with indomethacin (1 mg/kg daily) resulted in a further significant (P < 0.01) rise in sulfated glycosaminoglycan synthesis in indomethacin-treated ulcer tissue compared to that found in healing ulcers at day 14. The increased glycosaminoglycan synthesis was due to increased levels of chondroitin sulfate and dermatan sulfate. Glycosaminoglycan synthesis is elevated at the ulcer site during healing of experimental gastric ulcers; however, indomethacin treatment, which delays ulcer healing, significantly increases the synthesis of glycosaminoglycans above that seen in healing ulcers. Changes in the sulfated glycosaminoglycan content of the ulcer may play a role in the healing process and may give further insight into the mechanisms by which indomethacin delays ulcer healing.

Expression of adhesion molecules and leukocyte recruitment into gastric mucosa following ischemia-reperfusion

Leukocyte infiltration is an important step in postischemic tissue damage. This study aimed to determine the expression of adhesion molecules and their relationship with leukocyte infiltration in the postischemic gastric mucosa. Gastric tissue was obtained from rats subjected to 30 min gastric ischemia followed by reperfusion. Sections were stained with specific antibodies against (1) L-selectin and (2) LFA-1 on leukocytes, (3) ICAM-1 on endothelial cells, (4) PMNs, and (5) monocytes. Stained cells or blood vessels in mucosal tissue were counted using image analysis. Results showed that from 5 min of reperfusion, numbers of L-selectin-positive cells decreased, whereas LFA-1-positive cells and PMNs increased compared with controls. ICAM-1 expression did not increase until 60 min of reperfusion. Monocyte numbers were unaffected by reperfusion. We conclude that gastric ischemia-reperfusion results in a rapid influx of LFA-1-positive cells, the majority of which are PMN. L-Selectin is shed from these cells allowing them to adhere to the microvasculature via constitutively expressed ICAM-1.

Microvascular architecture of hepatic metastases in a mouse model

Development of effective treatment for hepatic metastases can be initiated by a better understanding of tumour vasculature and blood supply. This study was designed to characterise the microvascular architecture of hepatic metastases and observe the source of contributory blood supply from the host. Metastases were induced in mice by an intrasplenic injection of colon carcinoma cells (10(6) cells/ml.) Vascularization of tumours was studied over a three week period by scanning electron microscopy of microvascular corrosion casts. Metastatic liver involvement was observed initially within a week post induction, as areas approximately 100 microns in diameter not perfused by the casting resin. On histology these spaces corresponded to tumour cell aggregates. The following weeks highlighted the angiogenesis phase of these tumours as they received a vascular supply from adjacent hepatic sinusoids. Direct sinusoidal supply of metastases was maintained throughout tumour growth. At the tumour periphery most sinusoids were compressed to form a sheath demarcating the tumour from the hepatic vasculature. No direct supply from the hepatic artery or the portal vein was observed. Dilated vessels termed vascular lakes dominated the complex microvascular architecture of the tumours, most tapering as they traversed towards the periphery. Four vascular branching patterns could be identified as true loops, bifurcations and trifurcations, spirals and capillary networks. The most significant observation in this study was the direct sinusoidal supply of metastases, together with the vascular lakes and the peripheral sinusoidal sheaths of the tumour microculature.

Influence of age on natural and delayed healing of experimentally-induced gastric ulcers in rats

This study aimed to investigate the effect of age on natural ulcer healing and delayed ulcer healing induced by nonsteroidal antiinflammatory drugs, using a rat model. Gastric ulcers were induced in young, adult, and aged rats using serosal or mucosal (kissing ulcers) application of acetic acid. Rats were treated with indomethacin 1 mg/kg/day subcutaneously or vehicle for two weeks. Ulcers were assessed by macroscopic and histological measurements of ulcer size. Ulcer induction was affected by age. Aged rats developed significantly smaller ulcers when induced by serosal application of acetic acid and significantly larger ulcers from mucosal application of acetic acid. However, measurements of ulcer size from both models showed no age-related differences in natural ulcer healing. Similarly, indomethacin-induced delayed gastric ulcer healing was not effected by age. We conclude that there are age-related differences in the development of gastric ulcers but there are no age-related differences in natural or delayed ulcer healing in rats.

Inhibition of colon cancer precursors in the rat by sulindac sulphone is not dependent on inhibition of prostaglandin synthesis

The non-steroidal anti-inflammatory drug, sulindac, inhibits the growth of colorectal tumours in animal models of colon cancer and causes regression of polyps in patients with familial adenomatous polyposis. The mechanism by which sulindac exerts this inhibitory effect is not known, but it has been postulated to be via the inhibition of prostaglandin synthesis. However, two recent studies have indicated that sulindac sulphone, the non-prostaglandin inhibiting metabolite of sulindac, may be important in tumour inhibition. In the present study, we examined the effect of sulindac sulphone on the formation of aberrant crypt foci, the earliest identifiable lesions in the development of colorectal cancer, in the rat colon. We have previously shown that sulindac causes a dose dependent inhibition of aberrant crypt formation in this model. Aberrant crypt foci were induced with two oral doses of 1,2-dimethyl hydrazine at 25 mg/kg per dose. Treatment with sulindac sulphone at either 10 mg/kg b.d., or 20 mg/kg, b.d., was started on the day following administration of the first carcinogen dose and was continued for 3 weeks. Colons were then removed and examined for aberrant crypt foci. Colonic crypts were visualized by staining the unsectioned colon in 0.2% methylene blue solution. There was a significant reduction in the number of aberrant foci in rats treated with sulindac sulphone at 20 mg/kg, b.d. (ANOVA, P = 0.0054). The mechanism by which non-steroidal anti-inflammatory drugs inhibit formation of aberrant crypt foci is not clear; however, these data suggest that it is not due to the inhibition of prostaglandin synthesis.

The microvascular structure of the normal colon in rats and humans

The colonic microcirculation may be expected to have a central role in the absorptive, secretory, and protective functions of the colon. To characterize the microvascular structure of the colon in rats and humans, microvascular casts were prepared and examined by scanning electron microscopy. Quantitative measures of the microvasculature were obtained from histological sections. The overall organization of microvessels was found to be similar in the rat and human colon. Capillaries in the colonic mucosa formed a honeycomb-like network around each of the mucosal glands. This capillary plexus was supplied by arterioles which divide into their capillary branches at the level of the submucosa. Mucosal capillaries drain into venules at the luminal surface of the mucosa. Venules then pass to submucosal veins without receiving further capillary branches. Examination of vascular casts also showed that in both the rat and the human colon, there was an increased density of subluminal capillaries in the cecum and proximal colon compared to that of the rest of the colon. This was supported by quantitative measures which indicated a significantly greater microvascular surface area in the rat cecum (24.1 mm2/mm3) compared to that of the midcolon (19.8 mm2/mm3) (P = 0.04) and the distal colon (19.1 mm2/mm3) (P = 0.03). Similarly in the human colon there was a significantly greater total microvascular volume in the proximal colon (13.4%) compared to that of the distal colon (7.7%) (P < 0.0005) and there was a significantly greater total microvascular surface area in the proximal colon (22.4 mm2/mm3) compared to that of the distal colon (17.5 mm2/mm3)(P=0.032). This study details quantitative vascular data for the colon in rats and humans which has not previously been documented, despite its important role in the absorptive function of the colon and in many disease processes affecting the colon. These data provide the normal values with which pathological conditions of the colon which affect the vasculature can be compared.

Sulindac and indomethacin inhibit formation of aberrant crypt foci in the colons of dimethyl hydrazine treated rats

Aberrant crypt foci are microscopic lesions found in the colons of rodents treated with carcinogens, and in patients with premalignant colorectal conditions. They consist of single or multiple abnormal crypts and show cellular changes ranging from dysplasia to microscopic adenomacarcinoma. It is thought that these lesions represent the initial stages of the adenomacarcinoma path that results in the development of colorectal neoplasia. We have examined the effect of sulindac and indomethacin on the formation of aberrant crypt foci in rats treated with dimethylhydrazine (DMH). Aberrant crypt foci were induced in male Sprague-Dawley rats with two oral doses of dimethyl hydrazine at 25 mg/kg per dose. Rats were randomized to receive sulindac at 3 mg/kg (n = 20) or 10 mg/kg (n = 18) b.d., indomethacin at 1 mg/kg per day (n = 18) or 2 mg/kg per day (n = 19) or control (n = 37). Drug treatment was started on the day following the first dose of carcinogen and continued for 3 weeks. Colons were fixed flat overnight in 10% formalin and stained with 0.2%. Methylene Blue solution before being studied. There was a significant reduction in the number of aberrant crypt foci in rats treated with 10 mg/kg b.d., sulindac (P = 0.001) and indomethacin at 2 mg/kg per day (P = 0.0002). Sulindac, at 3 mg/kg b.d., and indomethacin, at 1 mg/kg per day, did not have a statistically significant effect (P = 0.089 and P = 0.052, respectively). None of the drug treatments affected the relative frequency of single crypt vs multiple crypt foci. Previous studies have shown that sulindac and indomethacin will significantly inhibit the growth and development of tumours in DMH treated rats. The current data suggest that one of the pathways of action of NSAID is to inhibit the formation of early preneoplastic lesions.

Characterization of an animal model of hepatic metastasis

The experimental study of possible therapies for control of the growth of liver metastases requires the availability of a model which is technically feasible and appears to exhibit growth characteristics similar to human tumours. We report on the development of an intrasplenic injection model of liver metastases, and describe the histology, growth pattern and blood flow demonstrated by light microscopy, stereology and laser Doppler flowmetry. The hepatic metastases were induced in mice by intrasplenic injection of dimethylhydrazine (DMH) induced primary colonic carcinoma cells (10(6) cells in 1 mL). The growth and development of metastases was studied over a period of 3 weeks at predetermined time points. Tumour cells were visible in the hepatic sinusoids by day 7 by light microscopy. Macroscopically visible tumours with a diameter of 0.18 +/- 0.02 cm (mean +/- s.d.) were seen by day 10. By this time the tumours had derived a blood supply from the hepatic sinusoids adjacent to the tumour periphery. With further vascularization the tumours reached a diameter of 0.96 +/- 0.50 cm by day 22. Metastatic growth was quantitated by stereological analysis of tumour volume in relation to non-diseased hepatic tissue. Normal mouse liver had a mean volume of 1.13 +/- 0.14 cm3. Tumour growth occurred in three phases. During the initial slow phase the volume of metastases increased from 0.03 +/- 0.02 cm3 at day 10 to 0.22 +/- 0.24 cm3 by day 16. Rapid tumour growth, occurring over the next 3 days, constituted the intermediate phase with metastatic volume reaching 1.21 +/- 0.74 cm3 by day 19 (P = 0.0003 compared with day 16). This growth was followed by a plateau phase when the metastatic volume was 1.40 +/- 0.55 cm3 at day 22. The volume of total liver and of tumour necrosis followed a similar growth pattern. A necrotic tumour volume of 0.004 +/- 0.006 cm3 first seen on day 10 increased to 0.05 +/- 0.06 cm3 by day 16, and to 0.25 +/- 0.20 cm3 by day 22 (P = 0.0022 compared with day 16). The blood flow in metastases measured by laser Doppler flowmetry was lower compared to the non-diseased liver. Tumour blood flow, expressed as a percentage of normal liver blood flow, was 63.31 +/- 26.28% at day 10 and diminished to 27.91 +/- 8.99% by day 22, with an increase in tumour size and age. The decrease in flow was significant between days 13 and 16 (P = 0.0015). This intrasplenic mouse model of metastases is reproducible and should prove useful in the study of treatment of hepatic metastases.

NSAID-induced delay in gastric ulcer healing is not associated with decreased epithelial cell proliferation in rats

Nonsteriodal antiinflammatory drugs initiate gastric ulceration and delay gastric ulcer healing. This study aimed to investigate the role of epithelial cell proliferation in delayed ulcer healing and to identify the most reproducible technique for measuring cell proliferation. Rats with acetic acid-induced gastric ulcers were treated for two weeks with indomethacin (1 mg/kg), aspirin (200 mg/kg), or vehicle control. Ulcers were assessed by macroscopic measurement of ulcer area, quantitative histological measurement of mucosal regeneration, and 5-bromo-2'-deoxyuridine immunohistochemistry to assess epithelial cell proliferation. Indomethacin and aspirin significantly delayed ulcer healing and inhibited mucosal regeneration. Three techniques for assessing cell proliferation were compared, and a scoring system, designed to take into account the entire tissue, was shown to be the most reproducible technique. Indomethacin significantly enhanced cell proliferation in the fundic area of ulcer and aspirin had no effect on cell proliferation. We conclude that aspirin and indomethacin delay ulcer healing by an inhibition of mucosal regeneration, but they do not inhibit epithelial cell proliferation.

Acetaminophen-induced microvascular injury in the rat liver: protection with misoprostol

Studies into the mechanism of acetaminophen (APAP)-induced hepatotoxicity have focused mainly at the hepatocellular level. This study aimed to investigate the effect of acetaminophen on the hepatic microvasculature using a vascular casting technique. Acetaminophen was administered at a dose of 650 mg/kg body weight (intraperitoneally) to fasted male Long Evans rats. Microvascular casting was performed at various points after drug administration. Liver casts from control rats showed good patency with normal hepatic microvasculature. Thirty-six hours after overdose with acetaminophen, liver casts showed rounded centrilobular cavities of various sizes, representing regions in which cast-filled sinusoids were absent with relatively normal microvasculature within periportal regions. Evidence of microvascular injury occurred as early as 5 hours after acetaminophen overdose. This injury consisted of changes to centrilobular sinusoids including areas of incomplete filling and dilated centrilobular sinusoids. Misoprostol (a prostaglandin E1 analog) treatment (6 x 25 micrograms/kg) given before and after acetaminophen administration markedly reduced the extent of microvascular injury with only small focal unfilled areas in the casts and a generally intact microvasculature. In conclusion, this study shows that overdosage with APAP resulted in an extensive, characteristic pattern of hepatic microvascular injury in the centrilobular region. The results also suggest that microvascular injury is an early event in the pathogenesis of acetaminophen hepatotoxicity. Misoprostol was found to protect against injury occurring at the microvascular level.

Sulphated macromolecules produced by in vivo labelling in the rat gastric mucosa

The aim of this study was to investigate the nature and distribution of sulphated macromolecules of the extracellular matrix in rat gastric mucosa. This was achieved by developing an in vivo labelling system. An intraperitoneal injection of 1 mCi [35S]-sulphate was given for either 4 h (0.01% incorporation into macromolecular fraction) or 8 h (0.13% incorporation). At the end of the labelling period the stomach was removed and the mucosa and submucosa was either taken as a single combined sample or separated into four layers by blunt dissection. Each sample was papain digested and analysed by ion-exchange chromatography. This analysis revealed sulphated species of differing charge existing in differing proportions throughout the mucosa. These sulphated species eluted at NaCl concentrations of approximately 0 (A), 0.19 (B), 0.34 (C) and 0.78 mol/L (D) from a Q-Sepharose ion exchange column. Further analysis by size exclusion chromatography and chemical and enzymatic digestion showed that peaks B and C had molecular weights of 2.4 x 10(5) and 2.8 x 10(5), respectively and were resistant to chondroitinase ABC, heparitinase and nitrous acid digestion. Peak D was found to contain a polydisperse population of molecules with a molecular weight range of approximately 1 x 10(4) to 6 x 10(4). This sample was susceptible to nitrous acid and chondroitinase ABC digestion and was found predominantly in the sample isolated from deeper in the tissue. We have thus developed an in vivo labelling technique for sulphated macromolecules that can be used in the further study of injury to the gastric mucosa.

Microvascular structure of benign and malignant tumors of the colon in humans

Studies of experimental tumors in rodents indicate that there are morphological abnormalities of the tumor microcirculation compared to normal tissues. The aim of this study was to examine the structure of the microvasculature in benign and malignant colonic tumors in humans using microvascular casting techniques. There were 15 adenocarcinomas, four benign sporadic adenomas, and three specimens from patients with familial adenomatous polyposis (FAP). A cast of the microvessels of these tumors was prepared by intraarterial administration of acrylic resin (Mercox) and the cast examined by scanning electron microscopy. Quantitative measures of the microvasculature were obtained from histological sections using stereological techniques in four carcinomas, two sporadic adenomas, and 12 adenomas from patients with FAP. Vascular casts of benign colonic adenomas showed that the microvasculature had a similar organization to normal colon. However, capillaries and venules were elongated and had increased diameters compared to normal. In adenomas greater than 3 mm in diameter, there was an increased density of microvessels in the spaces between tumor cells. Vascular casts of colonic carcinomas were characterized by a disorganized structure and increased density of microvessels. The organization of microvessels within carcinomas had a similar overall pattern to normal colon. However, the increased number and density of microvessels resulted in formation of nodular clusters of capillaries, formation of "sheets" of frequently anastomosing capillaries, or almost complete packing of the interstitial spaces of the tumor by capillaries in places. Most capillaries had a long and tortuous course and numerous capillary sprouts were identified. Tumor microvessels had greater mean diameters than normal. Extravasation of resin from microvessels in carcinomas was frequently seen. The vascular volume of carcinomas (23.1% +/- 12.2), sporadic adenomas (16.3% +/- 3.4), and adenomas > 3 mm diameter in patients with FAP (17.7% +/- 3.0) were significantly greater than in normal colon (11.0% +/- 4.2). This study indicates that there is an increased vascular density in benign and malignant tumors of the colon compared to normal colon. The presence of profusely anastomotic microvessels and frequent capillary sprouts is evidence of active neovascularization and suggests control of tumor growth could be achieved by modifiers of angiogenesis.