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G W Carter

Publications and source records attributed to G W Carter.

At least 73 records · Page 4Linked to original sources
PubMed1987

High-level C5a gene expression and recovery of recombinant human C5a from Escherichia coli.

Poor expression of a synthetic gene for the inflammatory mediator, C5a, was observed in E. coli grown in rich media. Varying the media composition markedly improved expression, although C5a levels still declined rapidly at the end of log phase. Using a protease-deficient strain, C5a was recovered at stationary phase in high yield (13 mg/liter of culture). Recovery was dependent on guanidinium hydrochloride extraction to solubilize the protein and glutathione treatment to promote correct folding. Two-thirds of the C5a retained an amino-terminal methionine. Both forms of recombinant C5a had activity similar to serum-derived C5a in binding to human neutrophil receptors and inducing chemotaxis. The 700-fold improvement in yield made it feasible to obtain gram amounts of C5a and provides an efficient system for site-directed mutagenesis.

Cloning, Molecular↗
PubMed1987

Structural requirements for the inhibition of 5-lipoxygenase by 15-hydroxyeicosa-5,8,11,13-tetraenoic acid analogues.

The structural requirements for inhibition of RBL-1 (rat basophilic leukemia) 5-lipoxygenase by 15-hydroxyeicosa-5,8,11,13-tetraenoic acid (15-HETE, 1) were studied by systematic chemical modifications of the molecule at the hydroxyl and carboxyl groups, the double bonds, and the carboxylate and omega side chains. The most potent inhibitors were analogues that contained a 5,8-cis,cis-diene system and acted as alternate substrates for the enzyme. However, several analogues in which the 5,8-diene had been reduced were also found to inhibit the enzyme. Inhibition of 5-lipoxygenase by 15-hydroxyeicosa-11,13-dienoic acid (15-HEDE) analogues was optimal in compounds that generally contained a free carboxyl group, a carboxylate side chain of nine carbons, an omega side chain of five or six carbons, a cis,trans- or trans,cis-11,13-diene or 11,13-diyne system, and a 15-hydroxyl group. Conversion of 15-HEDE to its 16-membered lactone reduced but did not eliminate 5-lipoxygenase inhibitory activity. In contrast, a 3- to 10-fold enhancement of activity occurred when 5,15-diHETE (58) or 5-HETE (56) were cyclized to their respective delta-lactones. Molecular modeling of 15-HEDE analogues, modified in the C11-C15 region, showed that inactive analogues protrude into regions in space not occupied by active analogues. These structural studies indicate that multiple regions are important for 5-lipoxygenase inhibition by both 15-HETE and 15-HEDE analogues and that no single region plays a predominant role in inhibition.

Animals↗
PubMed1987

Hydroxamic acid inhibitors of 5-lipoxygenase.

The hydroxamic acid functionality can be incorporated in a variety of simple molecules to produce potent inhibitors of 5-lipoxygenase. As an example of this, the structure-activity relationships in a series of omega-phenylalkyl and omega-naphthylalkyl hydroxamic acids are presented. Among the features described are the influence of hydrophobicity, aryl substitution, and modifications of the hydroxamate group on enzyme inhibitory potency. To assist in the selection of more potent hydroxamic acid inhibitors, a simple hypothesis about the nature of enzyme-inhibitor binding was devised. In this hypothesis, the structures of compounds were matched to a proposed geometry of arachidonic acid when bound to the enzyme. Compounds that match best without extending into disfavored regions were predicted to be the best inhibitors. Three series of hydroxamates selected according to this approach are described. Within these series are some of the most potent inhibitors of 5-lipoxygenase reported to date.

Arachidonate Lipoxygenases↗
PubMed1987

Synthesis and 5-lipoxygenase inhibitory activity of 5-hydroperoxy-6,8,11,14-eicosatetraenoic acid analogues.

A series of eicosatetraenes (2-24) were designed, synthesized, and evaluated in vitro for inhibitory activity against 5-lipoxygenase (20000g supernatant from homogenized rat basophilic leukemia cells). All compounds were found to be active with the potencies (IC50's) ranging from 0.19 to 97 microM. Compounds containing the hydroxamic acid functionality (10-12) exhibited the best activity (IC50 = 0.19-2.8 microM). The most potent inhibitor was 5-[(hydroxyamino)carbonyl]methyl]-6,8,11,14-eicosatetraenoic acid (11), which was 10 times more active than the C-1 hydroxamates of arachidonic acid or 5-HETE. Cyclization of the linear eicosanoids 2 and 14 in the C-1 to C-5 region produced compounds (21 and 24, respectively) with several-fold greater potency.

Animals↗
PubMed1987

In vivo characterization of hydroxamic acid inhibitors of 5-lipoxygenase.

The hydroxamic acid functionally can be incorporated into simple molecules to produce potent inhibitors of 5-lipoxygenase. The ability of many of these hydroxamates to inhibit leukotriene synthesis in vivo has been measured directly with a rat peritoneal anaphylaxis model. Despite their potent enzyme inhibitory activity in vitro, many orally dosed hydroxamic acids only weakly inhibited leukotriene synthesis in vivo. This discrepancy is attributable at least in part to the rapid metabolism of hydroxamates to the corresponding carboxylic acids, which are inactive against the enzyme. A study of the structural features that affect this metabolism revealed that 2-arylpropionohydroxamic acids are relatively resistant to metabolic hydrolysis. Several members of this class of hydroxamates are described that are orally active inhibitors of leukotriene synthesis.

Administration, Oral↗
PubMed1986

High-level expression of a gene encoding the human complement factor C5a in Escherichia coli.

The synthetic C5a gene was initially found to be expressed poorly in Escherichia coli. We undertook studies to determine the reasons for poor expression and to increase expression. The work was focused on the role of the mRNA structure in C5a expression and stability of its product in E. coli. We present data on the effects of varying the sequence at the 5' end of mRNA as well as different ribosome-binding sites on expression. Evaluation of the stability of C5a showed rapid degradation of C5a in wild-type E. coli (half-life 3-5 min). Screening of several protease-deficient strains of E. coli showed that C5a was much more stable in an htpR strain carrying a mutation in the sigma subunit of RNA polymerase that is specific for heat shock promoters. The mutation is associated with a proteolytic deficiency. The half-life of C5a was increased to 20 min. By manipulating the expression vector, the regulatory region for the C5a gene, the host strain, growth conditions and methods for recovering the protein, C5a levels were increased 300-fold over previously reported amounts to about 3% of total cellular protein.

Base Sequence↗
PubMed1985

Purification of a mammalian 5-lipoxygenase from rat basophilic leukemia cells.

5-Lipoxygenase (5-lipox) has been purified to homogeneity from the 20,000 xg supernatant of sonicated rat basophilic leukemia (RBL-1) cells using a 4-step procedure. Purification was achieved primarily through the use of anion-exchange HPLC on two different media. Using the supernatant from 1 X 10(9) cells, approximately 33 micrograms of the enzyme can be routinely isolated with an estimated net yield of 5-10%. Purified 5-lipox consists of a single Mr 73,000 band on SDS gels (reduced or unreduced). When the purified enzyme was incubated with radiolabeled arachidonic acid and products analyzed by both straight phase and reversed phase HPLC, 5-hydroperoxyeicosatetraenoic acid (5-HPETE) was the only enzymatic product detected. The purified enzyme exhibits the same characteristic lag phase and premature cessation of reaction as does the 5-lipox activity seen in crude cell homogenates.

Animals↗
PubMed1985

Chemical synthesis of a gene encoding the human complement fragment C5a and its expression in Escherichia coli.

A gene coding for the C5a fragment of the fifth component of human complement has been chemically synthesized, cloned, and expressed in Escherichia coli. The 253-base-pair gene fragment was built through a two-step enzymic assembly of 16 oligonucleotides, the average length of each being 32 residues. The oligonucleotides were synthesized by using the phosphoramidite method. The gene was cloned in a pBR322-derivative plasmid downstream from the lac up-promoter mutant, UV5-D. The expression of C5a was detected and measured by immunoassay and a radioligand binding assay. C5a from E. coli was comparable to C5a purified from human serum in inhibiting binding of human 125I-labeled C5a to its putative receptor on polymorphonuclear leukocytes. Studies of smooth muscle contraction in isolated guinea pig ileum showed that the recombinant C5a was biologically active and produced cross-tachyphylaxis with human serum-derived C5a. The results demonstrate the feasibility of expressing C5a anaphylatoxin in bacteria and provide a system for mutagenesis of the C5a protein.

Animals↗
PubMed1984

Granulocyte response to oxidized FMLP. Evidence for partial inactivation of FMLP.

We prepared FMoxLP by oxidation of FMLP and evaluated its ability to trigger a variety of granulocyte responses. FMoxLP was found to depolarize granulocyte membranes; increase granulocyte oxygen consumption, superoxide production, and hydrogen peroxide production; compete with FMLP for binding to granulocytes; and stimulate granulocyte chemotaxis. Against all of these granulocyte functions, FMoxLP was considerably less potent than the parent FMLP. When luminol-dependent-granulocyte chemiluminescence (CL) was studied, FMoxLP was observed to be a more potent stimulus of this response than FMLP. This increased CL activity of FMoxLP may be related to nonoxidative burst mechanisms. Our results indicate that FMoxLP retains a significant amount of the biological activity of FMLP (albeit in general less potent). The biological importance of the observed activities of FMoxLP must await further investigation.

Animals↗
PubMed1984

Heinz bodies, methemoglobinemia, and hemolytic anemia induced in rats by 3-amino-1-[m-(trifluoromethyl)phenyl]-2-pyrazoline.

Sprague-Dawley CD strain rats were given 18, 35, 70, or 140 mg/kg/day of 3-amino-1-[m-(trifluoromethyl)phenyl]-2-pyrazoline by gavage for 2 weeks. Heinz bodies were seen in the erythrocytes of rats given 140 mg/kg/day. Dose-related increases in methemoglobin were found at 35 mg/kg/day or more. Hemolytic anemia was characterized by dose-related decreases in hematocrit, hemoglobin, and total erythrocyte count. Reticulocytosis, decreased myeloid:erythroid ratio, splenomegaly, extramedullary hematopoiesis, increased serum total bilirubin, and icterus were also observed. This compound was found to oxidize oxyhemoglobin to methemoglobin in vitro, suggesting that the parent compound is capable of causing the hematological changes observed in vivo without conversion to active metabolites.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1983

2-[(Phenylthio)methyl]pyridine derivatives: new antiinflammatory agents.

2-[(Phenylthio)methyl]pyridine derivatives inhibited the dermal reverse passive Arthus reaction (RPAR) in the rat. In the same model, indomethacin was inactive, and hydrocortisone was active. Compounds Ia-d also significantly reduced exudate volume and white blood cell accumulation in the pleural RPAR. This pattern of activity was similar to that of hydrocortisone and different from that of indomethacin.

Animals↗
PubMed1982

The effects of anti-inflammatory and other agents on the rat dermal arthus reaction.

The inhibitory effects of selected drugs on the Arthus reaction, a model of immune-complex-induced tissue injury, were studied. The reverse passive Arthus reaction (RPAR) was elicited in the dorsal skin of rats, using bovine serum albumin and the gamma-globulin fraction of rabbit anti-BSA. The optimal amounts of antigen and antibody required to elicit the reaction, as well as the reaction kinetics, were examined. Chlorpheniramine, cyproheptadine, d-penicillamine, chloroquine, indomethacin, phenylbutazone, naproxen, and mefenamic acid were found to be inactive despite high doses; aspirin and ibuprofen were only weakly active. Hydrocortisone and colchicine were strong inhibitors of the RPAR: the calculated ED50 values were 13 mg/kg p.o. and 0.3 mg/kg i.v., respectively. The RPAR exhibits a different sensitivity to drug inhibition than conventional models of inflammation (e.g., carrageenin paw edema) end may be useful to detect new types of anti-inflammatory agents.

Animals↗
PubMed1980

Pharmacological studies in the rat with [2-(1,3-didecanoyloxy)-propyl]2-acetyloxybenzoate (A-45474): an aspirin pro-drug with negligible gastric irritation.

A triglyceride of aspirin, A-45474: [2-(1,3-didecanoyloxy)-propyl]2-acetyloxybenzoate, was developed to reduce the direct gastric irritant properties of aspirin. Studies in the rat show that oral administration of A-45474 produces anti-inflammatory activity comparable to aspirin with negligible gastric irritation. Compared with aspirin, plasma salicylate levels of A-45474 appeared less rapidly and were more sustained. It is concluded that incorporation of aspirin in the 2-position of a triglyceride bearing n-decanoyl groups in the 1- and 3-positions markedly reduces the gastric irritating properties of aspirin while maintaining its pharmacological effects.

Administration, Oral↗
PubMed1980

Glycerides as prodrugs. 3. Synthesis and antiinflammatory activity of [1-(p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetyl]glycerides (indomethacin glycerides).

Mono-, bis-, and tris[1-(p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetyl]glycerides and 1,3-dialkanoyl-2-[1-(p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetyl]glycerides were synthesized and evaluated for antiinflammatory activity in the rat paw carrageenin edema assay. Three of the most active compounds (4, 18a, and 18e) were tested in the rat adjuvant arthritis model and found to be essentially equivalent in activity to indomethacin. On a molar basis, the acute gastric irritating properties of 18a and 18e were seven to eight times less than indomethacin, resulting in a 2.5- to 3-fold improvement in the ratio of antiedema activity to ulcerogenicity.

Animals↗
PubMed1980

Glycerides as prodrugs. 2. 1,3-Dialkanoyl-2-(2-methyl-4-oxo-1,3-benzodioxan-2-yl)glycerides (cyclic aspirin triglycerides) as antiinflammatory agents.

A series of 1,3-dialkanoyl-2-(2-methyl-4-oxo-1,3-benzodioxan-2-yl)glycerides ("cyclic aspirin triglycerides") was synthesized. They demonstrated essentially all the systemic antiinflammatory activity associated with aspirin in the carrageenin-induced rat paw edema test. Examination of the rat stomachs showed that the 1,3-didecanoyl derivative did not cause gastric lesions.

Animals↗