PubMed Health⌕ Search

Biomedical subjects

S J O'Keefe

Publications and source records attributed to S J O'Keefe.

At least 19 recordsLinked to original sources
PubMed2001

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.

Adult↗
PubMed2001

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.

Acute Disease↗
PubMed2001

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.

Adult↗
PubMed2000

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.

Cell Adhesion↗
PubMed2000

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.

Activating Transcription Factor 2↗
PubMed2000

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.

Cachexia↗
PubMed2000

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.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2000

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.

Adult↗
PubMed2000

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.

Adolescent↗
PubMed1999

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.

Administration, Oral↗
PubMed1999

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.

Adult↗
PubMed1998

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.

Adenosine Triphosphate↗
PubMed1998

Pyrroles and other heterocycles as inhibitors of p38 kinase.

Investigation of furans, pyrroles and pyrazolones identified 3-pyridyl-2,5-diaryl-pyrroles as potent, orally bioavailable inhibitors of p38 kinase. 3-(4-pyridyl-2-(4-fluoro-phenyl)-5-(4-methylsulfinylphenyl)-pyrrol e (L-167307) reduces secondary paw swelling in the rat adjuvant arthritis model: ID50 = 7.4 mg/kg/b.i.d.

Animals↗
PubMed1998

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.

Adenosine Triphosphate↗
PubMed1998

A tacrolimus-related immunosuppressant with biochemical properties distinct from those of tacrolimus.

BACKGROUND: Tacrolimus (FK506) is an immunosuppressive drug 50-100 times more potent than cyclosporine (CsA), the current mainstay of organ transplant rejection therapy. Despite being chemically unrelated, CsA and tacrolimus exert their immunosuppressive effects through the inhibition of calcineurin (CaN), a critical signaling molecule during T-lymphocyte activation. Although numerous clinical studies have proven the therapeutic efficacy of drugs within this class, tacrolimus and CsA also have a strikingly similar profile of unwanted side effects. METHOD: Our objective has been to identify a less toxic immunosuppressant through the modification of ascomycin (FK520). Quantitative in vitro immunosuppression and toxicity assays have demonstrated (see the accompanying article, p. 18) that we achieved our goal with L-732,531 (indolyl-ascomycin; indolyl-ASC), a 32-O-(1-hydroxyethylindol-5-yl) ascomycin derivative with an improved therapeutic index relative to tacrolimus. RESULTS: We report that the attributes of indolyl-ASC may result from its distinctive biochemical properties. In contrast to tacrolimus, indolyl-ASC binds poorly to FK506 binding protein 12 (FKBP12), the major cytosolic receptor for tacrolimus and related compounds. However, the stability of the interaction between the FKBP12-indolyl-ASC complex and CaN is much greater than that of the FKBP12-tacrolimus complex. These distinguishing properties of indolyl-ASC result in the potent inhibition of CaN within T lymphocytes but may lower the accumulation of the drug at sites of toxicity. CONCLUSIONS: Indolyl-ASC may define those properties needed to increase the therapeutic efficacy of a macrolactam immunoregulant for treating both human autoimmune disease and organ transplant rejection.

Base Sequence↗
PubMed1998

Effect of chronic duodenal ulceration and its treatment with lanzoprazole or sucralfate on gastroduodenal mucosal protein turnover and TGF-alpha, bFGF, and EGF receptor expression in humans.

In order to investigate whether chronic duodenal ulcer disease is a consequence of disturbed mucosal turnover and growth factor expression, we studied 16 patients with duodenal ulcers before, during, and after endoscopic healing with lansoprazole or sucralfate. Before treatment, gastric fundal and antral mucosal protein turnover rates were higher in patients than controls, without parallel increases in growth factors. Both forms of therapy produced similar changes, with overall increases in duodenal mucosal turnover and transforming growth factor-alpha (TGF-alpha) and epidermal growth factor receptor (EGF-r) levels. Measurements after healing showed persistent elevations of mucosal turnover in the antrum and duodenum and depressions of basic fibroblast growth factor (bFGF) in gastric fundal and duodenal mucosa. We conclude that mucosal turnover is abnormally high in patients with chronic duodenal ulcer disease and is not easily explained by growth factor changes. The failure of lansoprazole and sucralfate to normalize rates, despite endoscopic healing, may explain the high ulcer relapse rates in non-HP-eradicated patients.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1997

Kinetic mechanism for p38 MAP kinase.

p38 has been shown to be a critical enzyme in the pro-inflammatory cytokine pathway and is a member of the mitogen-activated protein (MAP) kinase family. While the details for p38 activation and subsequent signal transduction have begun to be elucidated, little is known about the kinetic mechanism for p38. In this study, we have determined the kinetic mechanism for p38 MAP kinase. Data from initial velocity patterns in the presence and absence of a dead-end inhibitor and two triarylimidazole p38 inhibitors were consistent with an ordered sequential mechanism for p38 with protein substrate, glutathione S-transferase-activating transcription factor 2 (GST-ATF2), binding before ATP. The ATP analog, adenylyl methylenediphosphonate (AMP-PCP), and two triarylimidazoles were competitive inhibitors versus ATP and uncompetitive inhibitors versus GST-ATF2. Equilibrium binding studies utilizing a tritiated ATP-competitive inhibitor were also consistent with this mechanism and suggest an inability of ATP to bind to p38 in the absence of protein substrate. Moreover, the Michaelis constant for GST-ATF2 was 12-fold greater than the dissociation constant, indicating that the binding of ATP affected the binding of GST-ATF2. An ordered sequential mechanism with protein substrate binding first is unique to p38 compared to cyclic AMP-dependent protein kinase (cAPK) and most tyrosine kinases and helps to explain the interaction between enzyme, substrates, and inhibitors.

Activating Transcription Factor 2↗