Diet changes due to urbanization in South Africa are linked to microbiome and metabolome signatures of Westernization and colorectal cancer.

Transition from traditional high-fiber to Western diets in urbanizing communities of Sub-Saharan Africa is associated with increased risk of non-communicable diseases (NCD), exemplified by colorectal cancer (CRC) risk. To investigate how urbanization gives rise to microbial patterns that may be amenable by dietary intervention, we analyzed diet intake, fecal 16 S bacteriome, virome, and metabolome in a cross-sectional study in healthy rural and urban Xhosa people (South Africa). Urban Xhosa individuals had higher intakes of energy (urban: 3,578 ± 455; rural: 2,185 ± 179 kcal/d), fat and animal protein. This was associated with lower fecal bacteriome diversity and a shift from genera favoring degradation of complex carbohydrates (e.g., Prevotella) to taxa previously shown to be associated with bile acid metabolism and CRC. Urban Xhosa individuals had higher fecal levels of deoxycholic acid, shown to be associated with higher CRC risk, but similar short-chain fatty acid concentrations compared with rural individuals. Fecal virome composition was associated with distinct gut bacterial communities across urbanization, characterized by different dominant host bacteria (urban: Bacteriodota; rural: unassigned taxa) and variable correlation with fecal metabolites and dietary nutrients. Food and skin microbiota samples showed compositional differences along the urbanization gradient. Rural-urban dietary transition in South Africa is linked to major changes in the gut microbiome and metabolome. Further studies are needed to prove cause and identify whether restoration of specific components of the traditional diet will arrest the accelerating rise in NCDs in Sub-Saharan Africa.

Differences in Fecal Gut Microbiota, Short-Chain Fatty Acids and Bile Acids Link Colorectal Cancer Risk to Dietary Changes Associated with Urbanization Among Zimbabweans.

The incidence of colorectal cancer (CRC) is gradually rising in sub-Saharan Africa. This may be due to dietary changes associated with urbanization, which may induce tumor-promoting gut microbiota composition and function. We compared fecal microbiota composition and activity in 10 rural and 10 urban Zimbabweans for evidence of a differential CRC risk. Dietary intake was assessed by a food frequency questionnaire. Fecal microbiota composition, metabolomic profile, functional microbial genes were analyzed, and bile acids and short chain fatty acids quantified. Animal protein intake was higher among urban volunteers, but carbohydrate and fiber intake were similar. Bacteria related to Blautia obeum, Streptococcus bovis, and Subdoligranulum variabile were higher in urban residents, whereas bacteria related to Oscillospira guillermondii and Sporobacter termitidis were higher in rural volunteers. Fecal levels of primary bile acids, cholic acid, and chenodeoxycholic acid (P < 0.05), and secondary bile acids, deoxycholic acid (P < 0.05) and ursodeoxycholic acid (P < 0.001) were higher in urban residents. Fecal levels of acetate and propionate, but not butyrate, were higher in urban residents. The gut microbiota composition and activity among rural and urban Zimbabweans retain significant homogeneity (possibly due to retention of dietary fiber), but urban residents have subtle changes, which may indicate a higher CRC risk.

Randomised placebo-controlled trial of teduglutide in reducing parenteral nutrition and/or intravenous fluid requirements in patients with short bowel syndrome.

BACKGROUND AND AIMS: Teduglutide, a GLP-2 analogue, may restore intestinal structural and functional integrity by promoting repair and growth of the mucosa and reducing gastric emptying and secretion, thereby increasing fluid and nutrient absorption in patients with short bowel syndrome (SBS). This 24-week placebo-controlled study evaluated the ability of teduglutide to reduce parenteral support in patients with SBS with intestinal failure. METHODS: In 83 patients randomised to receive subcutaneous teduglutide 0.10 mg/kg/day (n = 32), 0.05 mg/kg/day (n = 35) or placebo (n = 16) once daily, parenteral fluids were reduced at 4-week intervals if intestinal fluid absorption (48 h urine volumes) increased ≥ 10%. Responders were subjects who demonstrated reductions of ≥ 20% in parenteral volumes from baseline at weeks 20 and 24. The primary efficacy end point, a graded response score (GRS), took into account higher levels and earlier onset of response, leading to longer duration of response. The intensity of the response was defined as a reduction from baseline in parenteral volume (from 20% to 100%), and the duration of the response was considered the response at weeks 16, 20 and 24. The results were tested according to a step-down procedure starting with the 0.10 mg/kg/day dose. RESULTS: Using the GRS criteria, teduglutide in a dose of 0.10 mg/kg/day did not have a statistically significant effect compared with placebo (8/32 vs 1/16, p=0.16), while teduglutide in a dose of 0.05 mg/kg/day had a significant effect (16/35, p = 0.007). Since parenteral volume reductions were equal (353 ± 475 and 354 ± 334 ml/day), the trend towards higher baseline parenteral volume (1816 ± 1008 vs 1374 ± 639 ml/day, p=0.11) in the 0.10 mg/kg/day group compared with the 0.05 mg/kg/day group may have accounted for this discrepancy. Three teduglutide-treated patients were completely weaned off parenteral support. Serious adverse events were distributed similarly between active treatment groups and placebo. Villus height, plasma citrulline concentration and lean body mass were significantly increased with teduglutide compared with placebo. CONCLUSIONS: Teduglutide was safe, well tolerated, intestinotrophic and suggested pro-absorptive effects facilitating reductions in parenteral support in patients with SBS with intestinal failure. ClinicalTrials.gov number NCT00172185.

The effect of severe undernutrition and subsequent refeeding on whole-body metabolism and protein synthesis in human subjects.

BACKGROUND: To determine the consequences of severe undernutrition and refeeding on whole-body metabolism and protein synthesis. METHODS: Respiratory quotient (RQ), resting energy expenditure (REE), and whole-body protein synthesis (WBPS) were assessed in undernourished patients, with anorexia nervosa (n = 8) or with coexistent disease (n = 17). Results were compared with 17 healthy controls. Six anorexic patients and 13 disease patients consented to study after nutrition support. RESULTS: Mean body mass index was 12.46 +/- 0.53 kg/m2 in the anorexia patients and 13.81 +/- 0.40 kg/m2 in the disease patients (controls 23.71 +/- 0.72 kg/m2; p < .001). Compared with controls, RQ was similar in anorexia patients (0.85 +/- 0.05 vs 0.90 +/- 0.05) but lower in the disease patients (0.76 +/- 0.03 vs 0.90 +/- 0.05; p = .02). REE was lower in the patients (anorexia 1058 +/- 134.0 kcal/d, disease 1189 +/- 101.4 kcal/d vs 1828 +/- 89.76 kcal/d; p < .001); however, expressed as kcal/kg/d, it was higher (anorexia 32.17 +/- 4.25, disease 31.30 +/- 2.14 vs 25.07 +/- 1.00; p < .05). WBPS was lower in the patients (anorexia 140.9 +/- 10.54 g/d, disease 119.8 +/- 8.57 g/d vs 305.0 +/- 21.64 g/d; p < .001); however, when expressed as g/kg/d, the anorexia patients were similar to controls, whereas the disease patients were lower (3.11 +/- 0.24 vs 4.27 +/- 0.32; p < .05). Refeeding increased RQ in the disease patients (0.84 +/- 0.03 vs 0.76 +/- 0.03; p < .05), and normalized REE (anorexia 27.65 +/- 3.05 kcal/kg/d, disease 28.90 +/- 1.85 kcal/kg/d). WBPS increased in the disease patients (173.6 +/- 16.38 g/d vs 116.5 +/- 10.15 g/d; p < .01). CONCLUSIONS: Undernutrition is associated with increased REE (kcal/kg/d). Reduction in RQ and protein synthesis (g/kg/d) was evident in those patients with coexistent disease. Refeeding resulted in normalization of RQ, REE (kcal/kg/d), and protein synthesis (g/kg/d).

Impaired gastric acid and pancreatic enzyme secretion in patients with Crohn's disease may be a consequenece of a poor nutritional state.

INTRODUCTION: Impaired pancreatic function has been reported in Crohn's disease, the cause of which is uncertain. This study investigated the effect of malnutrition, and subsequent re-feeding, on digestive function and protein synthesis in Crohn's disease patients. METHODS: Gastric acid and pancreatic secretion studies were performed on malnourished Crohn's patients before, and after a period of intensive nutritional support. Whole body, as well as pancreatic enzyme protein synthesis was investigated by [14C]leucine isotope incorporation studies. Results were evaluated in comparison to normal healthy volunteers. RESULTS: The mean body mass index (BMI) of the Crohn's patients was 14.14 kg/m2. The Crohn's patients had reduction in the secretion of gastric acid (7.36 versus 25.53 mEq/h; P < 0.01), and the pancreatic enzymes, amylase (759.6 versus 2305 U/h; P < 0.01), lipase (33.01 versus 118.6 U/h; P < 0.01) and trypsin (97.43 versus 341.4 U/h; P < 0.01). Resting energy expenditure (REE), expressed in relation to body mass, was greater in the malnourished Crohn's disease patients (38.25 versus 25.36 kcal/kg/d; P = 0.01). Total body protein synthesis was reduced (2.82 versus 4.39 g protein/kg/d; P < 0.05), with significant impairment in the synthesis of pancreatic enzymes, and reduction of zymogen stores. Following re-feeding, the BMI of the Crohn's patients improved to 16.80 +/- 0.66 kg/m2. Pancreatic enzyme synthesis improved, with significant increase in pancreatic enzyme stores and secretion, to levels similar to control values. Gastric acid secretion also improved, although still lower than the control value. CONCLUSION: Malnutrition may play a significant role in the impairment of gastric acid and pancreatic secretion in Crohn's disease patients.

Impaired pancreatic secretion in severely malnourished patients is a consequence of primary pancreatic dysfunction.

Severe undernutrition has been associated with reduced secretions of gastric acid and pancreatic enzymes. This may be the result of an impaired gut mucosal response to food and primary gastric parietal and pancreatic acinar cell secretory dysfunction as a consequence of the poor nutritional state. To investigate the relative contributions of these factors, severely undernourished patients underwent enteral-meal-stimulated (ES; n = 7) or intravenous hormone (pentagastrin and cholecystokinin-8)-stimulated (HS; n = 12) gastric acid and pancreatic enzyme secretion before and after a period of nutritional support. Results were evaluated in comparison with normal healthy control subjects (ES = 7, HS = 10). In the control subjects, enteral-meal and cholecystokinin-8 stimulation resulted in similar outputs of the pancreatic enzymes amylase (2213 versus 2305 U/h), lipase (84.93 versus 118.6 U/h), and trypsin (498.9 versus 341.4 U/h), whereas acid output was significantly lower in the ES group (10.90 versus 25.53 mEq/h; P < 0.01). Compared with controls, malnourished groups had significantly reduced secretions of amylase (ES = 870.1 U/h, HS = 686.5 U/h; P < 0.02), lipase (ES = 30.68 U/h, HS = 25.96 U/h; P < 0.02), and trypsin (ES = 175.6 U/h, HS = 109.3 U/h; P < 0.01). The response to enteral-meal or CCK-8 stimulation was comparable. Gastric acid was similarly reduced in the undernourished patients (ES = 4.39 mEq/h, HS = 5.04 mEq/h; P < 0.01). After refeeding, secretion of amylase (ES = 2351 U/h, HS = 2228 U/h) and lipase (ES = 58.83 U/h, HS = 84.91 U/h) improved to levels not significantly different from controls, whereas trypsin (ES = 226.4 U/h, HS = 213.1 U/h; P < 0.03) and acid secretion (ES = 3.52 mEq/h, HS = 11.85 mEq/h; P < 0.01) remained significantly impaired. Severe undernutrition was associated with primary gastric parietal and pancreatic acinar cell dysfunction, which, at least in the case of pancreatic enzymes, appeared to be the determining factor controlling secretion in these patients.

Nutrition in acute pancreatitis.

The majority of patients (80%) admitted with acute pancreatitis recovers after a few days of bowel rest and intravenous fluids. However, some cases progress to a fulminant disease complicated by a severe systemic inflammatory response and multiple organ failure, a condition in which mortality is related to the degree of negative nitrogen balance. The goal of nutrition support in this situation is to cover the increased metabolic demands without stimulating pancreatic secretion and exacerbating the "autodigestion" that characterizes the condition. Although human and animal studies have shown conflicting results regarding the effect of composition and location of feeding on pancreatic enzyme secretion, there is consensus that total parenteral nutrition (TPN), given at moderate infusion rates, does not significantly stimulate secretion in humans and that enteral diets stimulate enzyme secretion unless delivered below the jejunum. Consequently, until recently TPN has been the standard of therapy. The fact that the cost and complications of TPN can often outweigh its benefits (catheter sepsis, hyperglycemia) has led to a series of recent controlled clinical trials of modified enteral diets in which the diet is delivered by nasojejunal tube. Results have demonstrated that enteral nutrition, with either elemental or polymeric formulas, was cheaper, safer, and at the same time more effective in reducing the systemic inflammatory response. The pathophysiologic explanation for these observations needs further investigation.

The exacerbation of pancreatic endocrine dysfunction by potent pancreatic exocrine supplements in patients with chronic pancreatitis.

BACKGROUND: Chronic pancreatitis often culminates in maldigestion and diabetes. Clinical management is complex as the correction of maldigestion often disturbs diabetic control. STUDY: In the following study, we examined the effects of a potent new commercial pancreatic enzyme on food absorption and blood glucose control. Enzymes were manufactured in enteric-coated mini-microsphere form (0.7--1.6 mm), designed to prevent gastric acid degradation and facilitate co-migration with food, and given in quantities calculated to cover normal digestion requirements (four capsules with meals, two with snacks; content/capsule: lipase 10,000 USP units, protease 37,500 units, amylase 33,200 units). Forty patients with chronic pancreatitis were screened during a run-in nonenzyme-supplemented phase; only those with stool fat excretion rates over 10 g/d (n = 29) were advanced to a 14-day parallel randomized placebo versus enzyme supplement group comparison. RESULTS: Of these, 62% were diabetic (50% insulin-dependent) and 52% were malnourished (body mass index less than 20 kg/m(2) ). After enzyme supplementation, stool fat and nitrogen excretion decreased, whereas fat absorption increased from 54.0 +/- 9.7% to 80.8 +/- 3.8% per day (p = 0.002) and protein from 80.5 +/- 3.4% to 86.8 +/- 2.2% per day (p = 0.004). Changing treatment from active enzyme supplementation to placebo (and vice versa) resulted in major problems with glucose control; blood glucose levels became abnormal in 28 of 29 patients, one patient required hospitalization for symptomatic hypoglycemia (0.9 mmol/L) during placebo treatment, and one developed diabetic ketoacidosis after recommencing active enzyme supplementation. CONCLUSIONS: In conclusion, high-dose pancreatin mini-microspheres improved, but did not normalize, fat absorption, possibly because of the residual influence of diabetes and malnutrition on absorptive function. In view of the brittle nature of blood glucose control in malnourished insulin-dependent patients, enzyme adjustment should be carefully supervised in-hospital.

Serum-induced monocyte differentiation and monocyte chemotaxis are regulated by the p38 MAP kinase signal transduction pathway.

Regulation by the p38 mitogen-activated protein (MAP) kinase signaling pathway of monocytic inflammatory functions was evaluated using L-790,070, a potent and selective inhibitor of p38 MAP kinase. Three major functions of monocytes were investigated: differentiation, chemotaxis, and phagocytosis. L-790,070 inhibited serum-induced monocyte differentiation with an IC50 of 0.5 nM. Monocyte chemotaxis induced by RANTES, macrophage inflammatory protein-1alpha (MIP-1alpha), monocyte chemotactic protein- (MCP-1), and fMLP were all sensitive to L-790,070. When titrated, L-790,070 inhibited MCP-1-induced chemotaxis in a concentration-dependent manner with an IC50 of 0.3 nM. However, the ability of serum-derived macrophages to phagocytose apoptotic neutrophils was unaffected by L-790,070. The concentration with which L-790,070 inhibited both differentiation and chemotaxis was similar to that necessary to inhibit p38 MAP kinase activation of MAPKAP kinase (0.3 nM) in response to stimulation by lipopolysaccharide. Therefore, the data in this report suggest that the mechanism by which L-790,070 blocked monocyte differentiation and prevented chemotaxis was by inhibiting p38 MAP kinase activity.

L-selectin signaling of neutrophil adhesion and degranulation involves p38 mitogen-activated protein kinase.

The adhesion molecules known as selectins mediate the capture of neutrophils from the bloodstream. We have previously reported that ligation and cross-linking of L-selectin on the neutrophil surface enhances the adhesive function of beta(2)-integrins in a synergistic manner with chemotactic agonists. In this work, we examined degranulation and adhesion of neutrophils in response to cross-linking of L-selectin and addition of interleukin-8. Cross-linking of L-selectin induced priming of degranulation that was similar to that observed with the alkaloid cytochalasin B. Activation mediated by L-selectin of neutrophil shape change and adhesion through CD11b/CD18 were strongly blocked by Merck C, an imidazole-based inhibitor of p38 mitogen-activated protein kinase (MAPK), but not by a structurally similar non-binding regioisomer. Priming by L-selectin of the release of secondary, tertiary, and secretory, but not primary, granules was blocked by inhibition of p38 MAPK. Peak phosphorylation of p38 MAPK was observed within 1 min of cross-linking L-selectin, whereas phosphorylation of ERK1/2 was highest at 10 min. Phosphorylation of p38 MAPK, but not ERK1/2, was inhibited by Merck C. These data suggest that signal transduction as a result of clustering L-selectin utilizes p38 MAPK to effect neutrophil shape change, integrin activation, and the release of secondary, tertiary, and secretory granules.

The effect of severe undernutrition, and subsequent refeeding on digestive function in human patients.

BACKGROUND: Severe undernutrition may adversely affect gut function. AIMS: To investigate the effects of severe undernutrition and subsequent refeeding on human digestive function. METHODS: Severely undernourished patients (body mass index (BMI) < 17 kg/m2) were studied before, and after a period of intensive nutritional support. Standard intestinal absorption tests (faecal fat and urinary xylose excretion), pentagastrin-stimulated acid secretion, and cholecystokinin octapeptide (CCK-8)-stimulated pancreatic enzyme secretion tests were performed. In addition, duodenal biopies were taken to assess gut mucosal morphology. Findings were evaluated in comparison to a group of normal healthy volunteers. RESULTS: Mean BMI of the patients prior to nutritional support was 13.41 kg/m2, with improvement to 16.12 kg/m2 after. Duodenal histology showed evidence of villous atrophy in six of 14 (43%) undernourished patients. Mean xylose excretion following a 5 g oral dose was 0.62 g/5 h in the group of undernourished patients prior to nutritional support (normal > 1 g/5 h), with improvement to 1.40 g/5 h (P < 0.01) after feeding. Maximal gastric acid output was significantly impaired in the undernourished group, as compared to the controls (6.94 mEq/l vs 25.53 mEq/l, P < 0.02), with a significant improvement to 12.30 mEq/l (P < 0.05) following nutritional support. Pancreatic enzyme output was significantly reduced (amylase 830.9 U/h vs 2304 U/h, P < 0.01; lipase 38.0 U/h vs 118.6 U/h, P < 0.01; trypsin 119.7 U/h vs 341.4 U/h, P < 0.01). Following a period of nutritional support there was a significant improvement in amylase and lipase outputs to 1819 U/h and 85.5 U/h, respectively (P < 0.01). These levels were not significantly different from the normal controls. Trypsin output, however, remained significantly impaired at 174.3 U/h (P < 0.01). CONCLUSIONS: Severe undernutrition is associated with significant impairment of digestive function, with improvement occurring following nutritional support. These changes may affect initial tolerance to enteral feeding, particularly in those patients with co-existent gut disease.

Efficacy and tolerability of 20 mg pantoprazole versus 300 mg ranitidine in patients with mild reflux-oesophagitis: a randomized, double-blind, parallel, and multicentre study.

BACKGROUND AND AIM: The aim of this study was to compare the efficacy and tolerability of low dose pantoprazole (20 mg) (a gastric proton pump inhibitor) with standard dose ranitidine (300 mg) (a histamine-receptor antagonist), in their ability to relieve symptoms and heal oesophageal lesions associated with gastrooesophageal reflux disease (GORD). METHODS: Patients with endoscopically established mild GORD (stage I, modified Savary-Miller classification) were enrolled into a multicentre, randomized, double-blind, parallel-group comparison study (intention-to-treat population, n = 201; age range, 18-82 years). Patients took either oral pantoprazole 20 mg in the morning (n = 101) or ranitidine 300 mg in the evening (n = 100) once daily for 4 weeks or, if the healing was not complete, 8 weeks. Relief from key symptoms (heartburn, acid regurgitation, pain on swallowing) was assessed after 2, 4, and if applicable, 8 weeks. Healing of lesions was confirmed endoscopically after 4 and, if applicable, 8 weeks. RESULTS: Complete relief from key symptoms was noted after 2 weeks in 70/88 (80%) patients treated with pantoprazole vs 45/89 (51%) patients treated with ranitidine ('per-protocol and key-point available' populations, P < 0.001); the corresponding results after 4 weeks were 77/88 (88%) vs 51/88 (58%) (P < 0.001). Complete healing of lesions after 4 weeks of treatment was seen in 74/88 (84%) vs 49/89 (55%) in the pantoprazole and ranitidine group, respectively (P < 0.001, per-protocol); by week 8 the cumulative healing rates were 84/88 (95%) vs 69/89 (78%) in the pantoprazole and ranitidine group, respectively (P < 0.001). For the intention-to-treat populations, the corresponding values for healing after 4 and 8 weeks were 73% vs 49% (P < 0.001) and 83% vs 69% (P < 0.05), respectively. Both study medications were well tolerated. CONCLUSION: Compared to ranitidine 300 mg, the regimen with pantoprazole 20 mg provides faster relief from symptoms and is significantly more effective in healing of oesophageal lesions in patients with mild reflux-oesophagitis. Thus, the low dose of pantoprazole offers a treatment approach which minimizes drug exposure and costs while retaining high efficacy.

Activation of JNK3 alpha 1 requires both MKK4 and MKK7: kinetic characterization of in vitro phosphorylated JNK3 alpha 1.

JNK3 alpha 1 is predominantly a neuronal specific MAP kinase that is believed to require, like all MAP kinases, both threonine and tyrosine phosphorylation for maximal enzyme activity. In this study we investigated the in vitro activation of JNK3 alpha 1 by MAP kinase kinase 4 (MKK4), MAP kinase kinase 7 (MKK7), and the combination of MKK4 + MKK7. Mass spectral analysis showed that MKK7 was capable of monophosphorylating JNK3 alpha 1 in vitro, whereas both MKK4 and MKK7 were required for bisphosphorylation and maximal enzyme activity. Measuring catalysis under Vmax conditions showed MKK4 + MKK7-activated JNK3 alpha 1 had Vmax 715-fold greater than nonactivated JNK3 alpha 1 and MKK7-activated JNK3 alpha 1 had Vmax 250-fold greater than nonactivated JNK3 alpha 1. In contrast, MKK4-activated JNK3 alpha 1 had no increase in Vmax compared to nonactivated levels and had no phosphorylation on the basis of mass spectrometry. These data suggest that MKK7 was largely responsible for JNK3 alpha 1 activation and that a single threonine phosphorylation may be all that is needed for JNK3 alpha 1 to be active. The steady-state rate constants kcat, Km(GST-ATF2++), and Km(ATP) for both monophosphorylated and bisphosphorylated JNK3 alpha 1 were within 2-fold between the two enzyme forms, suggesting the addition of tyrosine phosphorylation does not affect the binding of ATF2, ATP, or maximal turnover. Finally, the MAP kinase inhibitor, SB203580, had an IC50 value approximately 4-fold more potent on the monophosphorylated JNK3 alpha 1 compared to the bisphosphorylated JNK3 alpha 1, suggesting only a modest effect of tyrosine phosphorylation on inhibitor binding.

Empiric treatment based on Helicobacter pylori serology cannot substitute for early endoscopy in the management of dyspeptic rural black Africans.

BACKGROUND: Evidence that chronic gastric Helicobacter pylori (HP) infection is an aetiological factor in dyspepsia, peptic ulcer disease, gastric carcinoma and lymphoma has led to the suggestion that all serologically positive dyspeptic patients should be treated empirically with antibiotics to eradicate the infection, without endoscopic diagnosis. The following study was performed to determine whether such a policy would prove to be of benefit in rural Africa, where endoscopic facilities are lacking and infection rates high. METHODS: Four district clinics were visited and 97 consecutive patients with persistent upper gastro-intestinal symptoms studied. After history-taking and physical examination, a blood sample was taken for HP serology (IgG anti-HP EIA) and endoscopy was performed. RESULTS: In comparison with similar studies in westernised countries HP was considerably more common (80%), and similar to that reported for the background population (83-86%), but peptic ulceration (17%) and gastric cancer (1%) were not. HP status and antibody levels failed to predict the presence of serious disease; patients with 'alarm' signs (78%), cancer (78%) and peptic ulcers (81%) had similar seropositivity rates to patients with non-ulcer dyspepsia (81%). Interestingly, many patients with distal oesophagitis were seronegative (40%). Haemoglobin concentrations and nutritional status were similar in HP-positive and negative patients. On the basis of published decision analysis strategies, empiric treatment of HP-positive patients with uncomplicated dyspepsia could be expected to produce symptomatic relief in 50% of cases, but would have delayed the diagnosis of 3 cases of cancer if patients over the age of 45 were included. CONCLUSION: The lack of association between HP serology and upper gastro-intestinal disease indicates that serological investigation cannot substitute for endoscopy in the management of black Africans with dyspepsia, and that empiric anti-HP therapy cannot be justified.

Design and synthesis of potent, selective, and orally bioavailable tetrasubstituted imidazole inhibitors of p38 mitogen-activated protein kinase.

Novel potent and selective diarylimidazole inhibitors of p38 MAP (mitogen-activated protein) kinase are described which have activity in both cell-based assays of tumor necrosis factor-alpha (TNF-alpha) release and an animal model of rheumatoid arthritis. The SAR leading to the development of selectivity against c-Raf and JNK2alpha1 kinases is presented, with key features being substitution of the 4-aryl ring with m-trifluoromethyl and substitution of the 5-heteroaryl ring with a 2-amino substituent. Cell-based activity was significantly enhanced by incorporation of a 4-piperidinyl moiety at the 2-position of the imidazole which also enhanced aqueous solubility. In general, oral bioavailability of this class of compounds was found to be poor unless the imidazole was methylated on nitrogen. This work led to identification of 48, a potent (p38 MAP kinase inhibition IC50 0.24 nM) and selective p38 MAP kinase inhibitor which inhibits lipopolysaccharide-stimulated release of TNF-alpha from human blood with an IC50 2.2 nM, shows good oral bioavailability in rat and rhesus monkey, and demonstrates significant improvement in measures of disease progression in a rat adjuvant-induced arthritis model.

Rarity of colon cancer in Africans is associated with low animal product consumption, not fiber.

OBJECTIVE: To investigate whether the rarity of colon cancer in black Africans (prevalence, < 1:100,000) can be accounted for by dietary factors considered to reduce risk, and by differences in colonic bacterial fermentation. METHODS: Samples of the adult black South African population were drawn from several rural and urban regions. Food consumption was assessed by home visits, food frequency questionnaires, computerized analysis of 72-h dietary recall, and blood sampling. Colonic fermentation was measured by breath H2 and CH4 response to a traditional meal, and to 10-g of lactulose. Cancer risk was estimated by measurement of epithelial proliferation indices (Ki-67 and BrdU) in rectal mucosal biopsies. Results were evaluated by comparison to measurements in high-risk white South Africans (prevalence, 17:100,000). RESULTS: Epithelial proliferation was significantly lower in rural and urban blacks than whites. The diets of all the black subgroups were characterized by a low animal product and high boiled maize-meal content, whereas whites consumed more fresh animal products, cheese, and wheat products. Blacks consumed below RDA quantities of fiber (43% of RDA), vitamin A (78%), C (62%), folic acid (80%) and calcium (67%), whereas whites consumed more animal protein (177% of RDA) and fat (153%). Fasting and food-induced breath methane production was two to three times higher in blacks. CONCLUSIONS: The low prevalence of colon cancer in black Africans cannot be explained by dietary "protective" factors, such as, fiber, calcium, vitamins A, C and folic acid, but may be influenced by the absence of "aggressive" factors, such as excess animal protein and fat, and by differences in colonic bacterial fermentation.

Molecular basis for p38 protein kinase inhibitor specificity.

p38 is a member of the mitogen-activated protein (MAP) kinase family and is a critical enzyme in the proinflammatory cytokine pathway. Other MAP kinase group members that share both structural and functional homology to p38 include the c-Jun NH2-terminal kinases (JNKs or SAPKs) and the extracellular-regulated protein kinases (ERKs). In this study, we determined the molecular basis for p38alpha inhibitor specificity exhibited by five compounds in the diarylimidazole, triarylimidazole, and triarylpyrrole classes of protein kinase inhibitors. These compounds are significantly more potent inhibitors of p38 compared to the JNKs and ERKs. Three active site ATP-binding domain residues in p38, T106, M109, and A157, selected based on primary sequence alignment, molecular modeling, and X-ray crystal structure data, were mutated to assess their role in inhibitor binding and enzymatic catalysis. All mutants, with the exception of T106M, had kinase activity within 3-fold of wild-type p38. Mutation of T106 to glutamine, the residue present at the corresponding position in ERK-2, or methionine, the corresponding residue in p38gamma, p38delta, and the JNKs, rendered all five inhibitors ineffective. The diarylimidazoles had approximately a 6-fold decrease in potency toward M109A p38. For the mutant A157V, all diarylimidazoles and triarylimidazoles tested were 5-10-fold more potent compared with wild-type p38. In contrast, two triarylpyrroles were 15-40-fold less potent versus A157V p38. These results showed that the molecular basis for the specificity of the p38 inhibitors was attributed largely to threonine 106 in p38 and that methionine 109 contributes to increased binding affinity for imidazole based inhibitors.

The activation state of p38 mitogen-activated protein kinase determines the efficiency of ATP competition for pyridinylimidazole inhibitor binding.

The serine/threonine kinase p38 is a ubiquitous, highly conserved, stress responsive, signal-transducing enzyme. It regulates the production of proinflammatory mediators and is the target of the cytokine synthesis inhibitory pyridinylimidazoles. We have expressed human p38 in Drosophila S2 cells and characterized preparations of mixed unphosphorylated/monophosphorylated (inactive) and homogeneously diphosphorylated (active) forms of the enzyme. We observed that only the active preparation of the enzyme has significant kinase activity when assayed using an ATF2-GST fusion protein as the substrate. We determined that the value of KM[ATP] in this reaction is 25 microM and that the pyridinylimidazole inhibitor of p38 kinase activity, SB203580, competes with ATP. We have found that a tritiated pyridinylimidazole, SB202190, has an equal affinity for both the active and inactive forms of the enzyme and that SB203580 competes with it equally well for binding to either form of the enzyme. However, ATP can compete with the tritiated inhibitor for binding to only the active form of the enzyme. Further, we demonstrate in vivo that at concentrations consistent with its IC50 as a cytokine inhibitor, SB203580 can inhibit stimulus-induced phosphorylation of p38 at the Thr-Gly-Tyr activation motif. Our observations suggest that pyridinylimidazoles may block the biological activity of p38 kinase by binding to the inactive form of p38 and reducing its rate of activation. Under these conditions, ATP would not effectively compete with the inhibitors in vivo.

The influence of intravenous infusions of glucose and amino acids of pancreatic enzyme and mucosal protein synthesis in human subjects.

BACKGROUND: Animal studies have shown that the synthesis and secretion of pancreatic enzymes and the turnover of mucosal proteins is strongly influenced by diet. METHODS: To determine whether the absorbed products of digestion are responsible for these changes, we investigated in groups of five healthy volunteers, the effects of i.v. infusions of amino acids (0.08 g/kg/h) and glucose (0.3 g/kg/h) on pancreatic enzyme and mucosal protein synthesis. Proteins were labeled in vivo by a 4-hours i.v. infusion of 14C-leucine and the enteric infusion of 3H-leucine tracer, during simultaneous cholecystokinin stimulation and duodenal collection of secreted pancreatic enzymes. Labeling of mucosal proteins was measured by endoscopic biopsy. RESULTS: The amino acid infusions elevated plasma amino acid levels, and the glucose infusions increased both glucose and insulin concentrations. The rates for amylase and trypsin secretion were significantly lower during the first 2 hours of glucose infusion and the rate of synthesis of trypsin was delayed by i.v. amino acid infusions from 52.1 +/- 4.1 to 77.6 +/- 8.5 minutes. Mucosal protein turnover rates were unaffected. 3H-labeling via the enteral route showed similar enzyme synthesis rates but variable mucosal incorporation rates. CONCLUSIONS: I.v. nutrients do not appear to stimulate the synthesis of pancreatic and mucosal proteins in human subjects.