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Biomedical subjects

J L Adams

Publications and source records attributed to J L Adams.

At least 37 records · Page 2Linked to original sources
PubMed1999

Pyridinylimidazole compound SB 203580 inhibits the activity but not the activation of p38 mitogen-activated protein kinase.

p38 MAPK is a Ser/Thr protein kinase activated by various inflammatory cytokines and a variety of stress stimuli. It is involved in many physiological processes, including the production of inflammatory cytokines. We have previously reported the design and synthesis of a series of pyridinylimidazole compounds that are selective inhibitors of p38 MAPK. These compounds, exemplified by SB 203580, are exceptionally effective in cell-based assays, including the inhibition of inflammatory cytokine production. SB 203580 is widely used as a tool to dissect the role of p38 MAPK in various physiological processes. It has previously been established that SB 203580 acts primarily to block the catalytic activity of p38 MAPK. However, it has been suggested that in cells, the compounds could also inhibit p38 MAPK activation by virtue of their ability to bind to the inactive enzyme. We undertook careful studies to definitively demonstrate that treatment with SB 203580 had no effect on Thr(180) and Tyr(182) phosphorylation, and hence activation of p38 in vivo. SB 203580, however, potently inhibited the activity of p38 MAPK as demonstrated by the inhibition of the activation of MAPKAP K2, a specific physiological substrate of p38 MAPK. This was observed regardless of stimuli or cell type. Identical results were obtained when the p38 MAPK cascade was partially reconstituted in vitro. Thus, our data clearly indicate that SB 203580 specifically inhibits the activity of p38 MAPK but not its activation by upstream MAPKK.

Animals↗
PubMed1999

A substrate combinatorial array for caspases.

An efficient strategy for the synthesis of a tetrapeptidyl substrate combinatorial array directed toward the caspases is described. Testing of this array with caspases 1 and 4 gave substrate hydrolytic profiles characteristic of each caspase, and permitted the identification of efficiently processed substrates. A comparison of this approach to that using a positional scanning library is presented.

Caspase 1↗
PubMed1999

Enteral tube feeding in the intensive care unit: factors impeding adequate delivery.

OBJECTIVE: To evaluate those factors that impact on the delivery of enteral tube feeding. DESIGN: Prospective study. SETTING: Medical intensive care units (ICU) and coronary care units at two university-based hospitals. PATIENTS: Forty-four medical ICU/coronary care unit patients (mean age, 57.8 yrs; 70% male) who were to receive nothing by mouth and were placed on enteral tube feeding. INTERVENTIONS: Rate of enteral tube feeding ordered, actual volume delivered, patient position, residual volume, flush volume, presence of blue food coloring in oropharynx, and stool frequency were recorded every 4 hrs. Duration and reason for cessation of enteral tube feeding were documented. MEASUREMENTS AND MAIN RESULTS: Physicians ordered a daily mean volume of enteral tube feeding that was 65.6% of goal requirements, but an average of only 78.1% of the volume ordered was actually infused. Thus, patients received a mean volume of enteral tube feeding for all 339 days of infusion that was 51.6% of goal (range, 15.1% to 87.1%). Only 14% of patients reached > or = 90% of goal feeding (for a single day) within 72 hrs of the start of enteral tube feeding infusion. Of 24 patients weighed before and after, 54% were noted to lose weight on enteral tube feeding. Declining albumin levels through the enteral tube feeding period correlated significantly with decreasing percent of goal calories infused (p = .042; r2 = .13). Diarrhea occurred in 23 patients (52.3%) for a mean 38.2% of enteral tube feeding days. In >1490 bedside evaluations, patients were observed to be in the supine position only 0.45%, residual volume of >200 mL was found 2.8%, and blue food coloring was found in the oropharynx 5.1% of the time. Despite this, cessation of enteral tube feeding occurred in 83.7% of patients for a mean 19.6% of the potential infusion time. Sixty-six percent of the enteral tube feeding cessations was judged to be attributable to avoidable causes. CONCLUSIONS: The current manner in which enteral tube feeding is delivered in the ICU results in grossly inadequate nutritional support. Barely one half of patient caloric requirements are met because of underordering by physicians and reduced delivery through frequent and often inappropriate cessation of feedings.

Energy Intake↗
PubMed1999

Impact of rpoS deletion on Escherichia coli biofilms.

Slow growth has been hypothesized to be an essential aspect of bacterial physiology within biofilms. In order to test this hypothesis, we employed two strains of Escherichia coli, ZK126 (DeltalacZ rpoS(+)) and its isogenic DeltarpoS derivative, ZK1000. These strains were grown at two rates (0.033 and 0.0083 h(-1)) in a glucose-limited chemostat which was coupled either to a modified Robbins device containing plugs of silicone rubber urinary catheter material or to a glass flow cell. The presence or absence of rpoS did not significantly affect planktonic growth of E. coli. In contrast, biofilm cell density in the rpoS mutant strain (ZK1000), as measured by determining the number of CFU per square centimeter, was reduced by 50% (P < 0.05). Deletion of rpoS caused differences in biofilm cell arrangement, as seen by scanning confocal laser microscopy. In reporter gene experiments, similar levels of rpoS expression were seen in chemostat-grown planktonic and biofilm populations at a growth rate of 0.033 h(-1). Overall, these studies suggest that rpoS is important for biofilm physiology.

Bacterial Proteins↗
PubMed1999

A novel method of guideline development for the diagnosis and management of mild to moderate hypertension.

BACKGROUND: There are large numbers of clinical guidelines available covering many clinical areas. However, the variable quality of their content has meant that doctors may have been offered advice that has been poorly researched or is of a conflicting nature. It has been shown that local involvement in guideline development increases the likelihood of their use. AIM: To develop a guideline to be used by general practitioners in six practices in Birmingham from existing evidence-based guidelines. METHOD: Recommendations from the four most cited international hypertension guidelines, and the more recently published New Zealand guidelines, were divided into subject areas and tabulated to facilitate direct comparison. Where there was complete or majority (> or = 3/5) agreement, the recommendation was taken as acceptable for inclusion in the new guideline. Where there was disagreement (< or = 2/5), recommendations were based on the best available evidence following a further MEDLINE literature search and critical appraisal of the relevant literature. Each recommendation was accompanied by a grade of evidence (A-D), as defined by the Canadian Hypertension Society, and an 'action required' statement of either 'must', 'should', or 'could', based on the Eli-Lilly National Clinical Audit Centre Hypertension Audit criteria. The recommendations were summarized into a guideline algorithm and a supporting document. The final format of both parts of the guideline was decided after consultation with the practice teams. The practices individually decided on methods of data collection. RESULTS: The guideline was presented as a double-sided, A4 laminated sheet and an A4 bound supporting document containing a synthesis of the original guidelines in tabular form, a table of the resulting recommendations, and appendices of current literature reviews on areas of disagreement. The content of the final Birmingham Clinical Effectiveness Group (BCEG) guideline differed minimally from any of the original guidelines. CONCLUSION: The main strength of this method of guideline development may lie, not in the actual content of the resulting guideline, but in the strength of ownership felt by the BCEG and the practices following its development. While the full process is unlikely to be possible for general practitioners working outside an academic environment, the techniques used could provide a framework for practitioners to adapt national and international guidelines for use at a local level.

Decision Trees↗
PubMed1998

Pyrimidinylimidazole inhibitors of CSBP/p38 kinase demonstrating decreased inhibition of hepatic cytochrome P450 enzymes.

Pyrimidine analogs of the pyrimidinylimidazole class of CSBP/p38 kinase inhibitors were prepared in an effort to reduce the potent inhibition of hepatic cytochrome P450 observed for the pyridinyl compounds. The substitution of pyrimidin-4-yl, 2-methoxypyrimidin-4-yl, or 2-methylaminopyrimidin-4-yl for pyridin-4-yl effectively dissociates CSBP/p38 kinase from P450 inhibition for this series and furthermore achieves an increase in oral activity.

Animals↗
PubMed1998

Structural basis of inhibitor selectivity in MAP kinases.

BACKGROUND: The mitogen-activated protein (MAP) kinases are important signaling molecules that participate in diverse cellular events and are potential targets for intervention in inflammation, cancer, and other diseases. The MAP kinase p38 is responsive to environmental stresses and is involved in the production of cytokines during inflammation. In contrast, the activation of the MAP kinase ERK2 (extracellular-signal-regulated kinase 2) leads to cellular differentiation or proliferation. The anti-inflammatory agent pyridinylimidazole and its analogs (SB [SmithKline Beecham] compounds) are highly potent and selective inhibitors of p38, but not of the closely-related ERK2, or other serine/threonine kinases. Although these compounds are known to bind to the ATP-binding site, the origin of the inhibitory specificity toward p38 is not clear. RESULTS: We report the structural basis for the exceptional selectivity of these SB compounds for p38 over ERK2, as determined by comparative crystallography. In addition, structural data on the origin of olomoucine (a better inhibitor of ERK2) selectivity are presented. The crystal structures of four SB compounds in complex with p38 and of one SB compound and olomoucine in complex with ERK2 are presented here. The SB inhibitors bind in an extended pocket in the active site and are complementary to the open domain structure of the low-activity form of p38. The relatively closed domain structure of ERK2 is able to accommodate the smaller olomoucine. CONCLUSIONS: The unique kinase-inhibitor interactions observed in these complexes originate from amino-acid replacements in the active site and replacements distant from the active site that affect the size of the domain interface. This structural information should facilitate the design of better MAP-kinase inhibitors for the treatment of inflammation and other diseases.

Adenosine Triphosphate↗
PubMed1998

Acquisition of sensitivity of stress-activated protein kinases to the p38 inhibitor, SB 203580, by alteration of one or more amino acids within the ATP binding pocket.

Pyridinyl imidazole inhibitors of p38 mitogen-activated protein kinase compete with ATP for binding. Mutation of 23 residues in the ATP pocket indicated that several residues which affected binding of pyridinyl imidazole photoaffinity cross-linker 125I-SB 206718 did not affect kinase activity, and vice versa, suggesting that pyridinyl imidazoles bind p38 differently than ATP. Two close homologues of p38, SAPK3 and SAPK4, are not inhibited by SB 203580 and differ from p38 by three amino acids near the hinge of the ATP pocket. Substitution of the three amino acids in p38 by those in SAPK3/4 (Thr-106, His-107, and Leu-108 to Met, Pro, and Phe) resulted in decreased 125I-SB 206718 cross-linking and loss of inhibition by SB 203580. Substitution of just Thr-106 by Met resulted in incomplete loss of inhibition. Conversely, substitution of the three amino acids of p38 into SAPK3, SAPK4, or the more distantly related JNK1 resulted in inhibition by SB 203580, whereas mutation of just Met-106 to Thr resulted in weaker inhibition. These results indicate that these three amino acids can confer specificity and sensitivity to SB 203580 for at least two different classes of MAPKs.

Adenosine Triphosphate↗
PubMed1997

Pyridinyl imidazole inhibitors of p38 mitogen-activated protein kinase bind in the ATP site.

The site of action of a series of pyridinyl imidazole compounds that are selective inhibitors of p38 mitogen-activated protein kinase in vitro and block proinflammatory cytokine production in vivo has been determined. Using Edman sequencing, 125I-SB206718 was shown to cross-link to the nonphosphorylated Escherichia coli-expressed p38 kinase at Thr175, which is proximal to the ATP binding site. Titration calorimetric studies with E. coli-expressed p38 kinase showed that SB203580 bound with a stoichiometry of 1:1 and that binding was blocked by preincubation of p38 kinase with the ATP analogue, FSBA (5'-[p-(fluorosulfonyl)benzoyl]adenosine), which covalently modifies the ATP binding site. The intrinsic ATPase activity of the nonphosphorylated enzyme was inhibited by SB203580 with a Km of 9.6 mM. Kinetic studies of active, phosphorylated yeast-expressed p38 kinase using a peptide substrate showed that SB203580 was competitive with ATP with a Ki of 21 nM and that kinase inhibition correlated with binding and biological activity. Mutagenesis indicated that binding of 125I-SB206718 was dependent on the catalytic residues K53 and D168 in the ATP pocket. These findings indicate that the pyridinyl imidazoles act in vivo by inhibiting p38 kinase activity through competition with ATP and that their selectivity is probably determined by differences in nonconserved regions within or near the ATP binding pocket.

Adenosine↗
PubMed1997

Regulation of stress-induced cytokine production by pyridinylimidazoles; inhibition of CSBP kinase.

Members of three classes of pyridinylimidazoles bind with varying affinities to CSBP (p38) kinase which is a member of a stress-induced signal transduction pathway. Based upon SAR and protein homology modeling, the pharmacophore and three potential modes of binding to the enzyme are presented. For a subset of pyridinylimidazoles, binding is shown to correlate with inhibition of CSBP kinase activity, whereas no significant inhibition of PKA, PKC alpha and ERK kinase activity is observed.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1996

Bicyclic N-hydroxyurea inhibitors of 5-lipoxygenase: pharmacodynamic, pharmacokinetic, and in vitro metabolic studies characterizing N-hydroxy-N-(2,3-dihydro-6-(phenylmethoxy)-3-benzofuranyl)urea.

A series of N-hydroxyurea derivatives have been prepared and examined as inhibitors of 5-lipoxygenase. Oral activity was established by examining the inhibition of LTB4 biosynthesis in an ex vivo assay in the mouse. The pharmacodynamic performance in the mouse of selected compounds was assessed using an ex vivo LTB4 assay and an adoptive peritoneal anaphylaxis assay at extended pretreat times. Compounds with an extended duration of action were re-examined as the individual enantiomers in the ex vivo assay, and the (S) enantiomer of N-hydroxy-N-[2,3-dihydro-6-(phenylmethoxy)-3-benzofuranyl]urea, (+)-1a (SB 202235), was selected as the compound with the best overall profile. Higher plasma concentrations and longer plasma half-lives were found for (+)-1a relative to its enantiomer in the mouse, monkey, and dog. In vitro metabolic studies in mouse liver microsomes established enantiospecific glucuronidation as a likely mechanism for the observed differences between the enantiomers of 1a. Enantioselective glucuronidation favoring (-)-1a was also found in human liver microsomes.

Animals↗
PubMed1996

Tumour necrosis factor-alpha-induced phosphorylation and activation of cytosolic phospholipase A2 are abrogated by an inhibitor of the p38 mitogen-activated protein kinase cascade in human neutrophils.

The role of the newly identified p38 mitogen-activated protein kinase (MAP kinase) in terminally differentiated cells, such as human neutrophils, is totally unknown. In order to examine the possible role of this MAP kinase in the phosphorylation and activation of cytoplasmic phospholipase A2 (cPLA2), we tested the effect of the recently synthesized inhibitor of p38 MAP kinase, SB 203580, on the phosphorylation and activation of both p38 MAP kinase and cPLA2. We found that while tumour necrosis factor-alpha (TNF-alpha)-stimulated tyrosine phosphorylation of p38 MAP kinase is affected only slightly by SB 203580, its stimulated kinase activity is greatly reduced in human neutrophils in suspension treated with this inhibitor. Furthermore, the TNF-alpha-stimulated phosphorylation and activation of cPLA2 are completely abolished in cells treated with SB 203580. Based on these data, it is reasonable to conclude that an SB 203580-sensitive kinase, or kinases and/or phosphatases, are involved in the phosphorylation and activation of cPLA2 in intact human neutrophils in suspension stimulated by TNF-alpha. The possible role of the p38 MAP kinase cascade in the phosphorylation and activation of cPLA2 is discussed.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1996

1-substituted 4-aryl-5-pyridinylimidazoles: a new class of cytokine suppressive drugs with low 5-lipoxygenase and cyclooxygenase inhibitory potency.

A series of 1-alkyl- or -aryl-4-aryl-5-pyridinylimidazoles (A) were prepared and tested for their ability to bind to a recently discovered protein kinase termed CSBP and to inhibit lipopolysaccharide (LPS)-stimulated TNF production in mice. The kinase, CSBP, appears to be involved in a signaling cascade initiated by a number of inflammatory stimuli and leading to the biosynthesis of the inflammatory cytokines IL-1 and TNF. Two related imidazole classes (B and C) had previously been reported to bind to CSBP and to inhibit LPS-stimulated human monocyte IL-1 and TNF production. The members of the earlier series exhibited varying degrees of potency as inhibitors of the enzymes of arachidonic acid metabolism, PGHS-1 and 5-LO. Several of the more potent CSBP ligands and TNF biosynthesis inhibitors among the present series of N-1-alkylated imidazoles (A) were tested as inhibitors of PGHS-1 and 5-LO and were found to be weak to inactive as inhibitors of these enzymes. One of the compounds, 9 (SB 210313) which lacked measureable activity as an inhibitor of the enzymes of arachidonate metabolism, and had good potency in the binding and in vivo TNF inhibition assays, was tested for antiarthritic activity in the AA rat model of arthritis. Compound 9 significantly reduced edema and increased bone mineral density in this model.

Animals↗
PubMed1996

Constitutive cyclooxygenase (COX-1) and inducible cyclooxygenase (COX-2): rationale for selective inhibition and progress to date.

While a great deal has been discovered concerning the potential physiological and pathological role of prostanoids, much is left to be determined. The widespread distribution of both COX-1 and COX-2 coupled with the capacity of most vascular beds, smooth muscle, as well as leukocytes to respond to prostanoids make drawing generalities difficult. The problems with the majority of currently used NSAIDs are clear and ulcerogenic liability is of obvious concern. Interestingly enough, the mechanism of that damage is still the subject of controversy as illustrated by the recent review and hypothesis of Somasundaram et al. In this treatise, the suggestion is made that the initial gastric damage is the result of uncoupling of oxidative phosphorylation which is independent but simultaneous with COX inhibition. At least two currently marketed NSAIDs have improved G.I. liability (nabumetone and etodolac) with efficacy equivalent to other more ulcerogenic NSAIDs. These drugs appear to have achieved that by a mechanism distinct from selective inhibition of COX-2. Whether or not selective COX-2 inhibitors will demonstrate an improved profile over these compounds remains to be shown. Unfortunately, clinical experience with nimsulide and CGP 28238 suggest that NSAID-like toxicity may still be an issue. The promise of selective COX-2 inhibitors remains largely untested. It is with great interest and expectation that the clinical evaluation of the more selective compounds of different structural types is awaited.

Animals↗
PubMed1996

Polymerase chain reaction analysis of TNF-alpha and IL-6 mRNA levels in whole blood from cattle naturally or experimentally infected with Mycobacterium paratuberculosis.

Johne's disease is characterized by a chronic enteritis that results in granulomatous inflammation, cachexia, and eventual death of cattle infected with Mycobacterium paratuberculosis. The cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) have been associated with granuloma formation and wasting in other disease syndromes. The potential role of these cytokines in the development and progression of Johne's disease has not been investigated. Using the polymerase chain reaction (PCR) and specific bovine oligonucleotide cytokine primers and probes, we examined the expression of messenger RNA for these cytokines in whole blood from M. paratuberculosis infected and uninfected cattle. Cytokine mRNA levels were examined before and after in vitro incubation with E.coli lipopolysaccharide (LPS) and lipoarabinomannan (LAM) purified from M. paratuberculosis. Uninfected calves, experimentally infected calves, and naturally infected cattle all displayed similar cytokine mRNA expression patterns. However, individual animals demonstrated variability in the levels of IL-6 and TNF-alpha mRNA expression as determined by a semiquantitative PCR method using 32P-labelled oligonucleotide probes.

Animals↗
PubMed1996

Pharmacological profile of SB 203580, a selective inhibitor of cytokine suppressive binding protein/p38 kinase, in animal models of arthritis, bone resorption, endotoxin shock and immune function.

SB 203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4- pyridyl)imidazole], a selective cytokine suppressive binding protein/p38 kinase inhibitor, was evaluated in several models of cytokine inhibition and inflammatory disease. It was demonstrated clearly to be a potent inhibitor of inflammatory cytokine production in vivo in both mice and rats with IC50 values of 15 to 25 mg/kg. SB 203580 possessed therapeutic activity in collagen-induced arthritis in DBA/LACJ mice with a dose of 50 mg/kg resulting in significant inhibition of paw inflammation and serum amyloid protein levels. Antiarthritic activity was also observed in adjuvant-induced arthritis in the Lewis rat when SB 203580 was administered p.o. at 30 and 60 mg/kg. Evidence for disease-modifying activity in this model was indicated by an improvement in bone mineral density and by histological evaluation. Additional evidence for beneficial effects on bone resorption was provided in the fetal rat long bone assay in which SB 203580 inhibited 45Ca release with an IC50 of 0.6 microM. In keeping with the inhibitory effects on lipopolysaccharide-induced tumor necrosis factor-alpha in mice, SB 203580 was found to reduce mortality in a murine model of endotoxin-induced shock. In immune function studies in mice treated with SB 203580 (60 mg/kg/day for 2 weeks), there was some suppression of an antibody response to ovalbumin, whereas cellular immune functions measured ex vivo were unaffected. This novel profile of activity strongly suggests that cytokine inhibitors could provide significant benefit in the therapy of chronic inflammatory disease.

Animals↗