Use of a murine cell line for identification of human nitric oxide synthase inhibitors

INTRODUCTION

Nitric oxide (NO) has been implicated in a wide range of physiological and pathological processes. Low concentrations of this mediator play homeostatic roles, whereas many acute and chronic responses are associated with excessive production of NO. This upregulation is due in part to the induction of inducible nitric oxide synthase (iNOS) by proinflammatory cytokines in several different cell types, including macrophages and their CNS derivative, microglia.

METHODS

The crystal structures of the oxygenase domains of mouse and human iNOS were superimposed using the "align by homology" feature in Sybyl (SYBYL 7.0, Tripos Inc.). NOS isoform expression was assessed by TaqMan, Western blotting, and activity assays.

RESULTS

We demonstrate that there is a high degree of three-dimensional overlap between the mouse and human iNOS active centers and propose that the murine isoform can serve as a suitable substitute for the human in assays. We also demonstrate that LPS stimulation of the mouse macrophage cell line RAW 264.7 induces the expression of iNOS, but not nNOS or eNOS, at the levels of mRNA transcription and protein expression. Furthermore, the pharmacology and calcium dependency of the NO formation support the finding that it is due to iNOS alone. Also reported is the demonstration of LPS-induced RAW 264.7 macrophages in simple cell-based and cell-free screening assays for iNOS inhibitors. Both assays were reproducible, as demonstrated by Z' factors of 0.69 and 0.71, and had high signal to noise ratios of 11- and 6-fold for the cell-based and cell-free assay, respectively.

DISCUSSION

Our computational analyses indicate that there is a high degree of three-dimensional overlap between the oxygenase domains of human and murine iNOS. This observation together with the selective induction of murine iNOS in RAW 264.7 macrophages demonstrates the potential utility of the mouse iNOS assay to identify inhibitors of the human enzyme.

Pyrazolidine-3,5-diones and 5-Hydroxy-1H-pyrazol-3(2H)-ones, Inhibitors of UDP-N-acetylenolpyruvyl Glucosamine Reductase

A series of pyrazolidine-3,5-dione and 5-hydroxy-1H-pyrazol-3(2H)-one inhibitors of Escherichia coli UDP-N-acetylenolpyruvyl glucosamine reductase (MurB) has been prepared. The 5-hydroxy-1H-pyrazol-3(2H)-ones show low micromolar IC(50) values versus E. coli MurB and submicromolar minimal inhibitory concentrations (MIC) against Staphylococcus aureus GC 1131, Enterococcus faecalis GC 2242, Streptococcus pneumoniae GC 1894, and E. coli GC 4560 imp, a strain with increased outer membrane permeability. None of these compounds show antimicrobial activity against Candida albicans, a marker of eukaryotic toxicity. Moreover, these compounds inhibit peptidoglycan biosynthesis, as assessed by measuring the amount of soluble peptidoglycan produced by Streptococcus epidermidis upon incubation with compounds. A partial least squares projection to latent structures analysis shows that improving MurB potency and MIC values correlate with increasing lipophilicity of the C-4 substituent of the 5-hydroxy-1H-pyrazol-3(2H)-one core. Docking studies using FLO and PharmDock produced several binding orientations for these molecules in the MurB active site.

4-Alkyl and 4,4'-dialkyl 1,2-bis(4-chlorophenyl)pyrazolidine-3,5-dione derivatives as new inhibitors of bacterial cell wall biosynthesis

Over 195 4-alkyl and 4,4-dialkyl 1,2-bis(4-chlorophenyl)pyrazolidine-3,5-dione derivatives were synthesized, utilizing microwave accelerated synthesis, for evaluation as new inhibitors of bacterial cell wall biosynthesis. Many of them demonstrated good activity against MurB in vitro and low MIC values against gram-positive bacteria, particularly penicillin-resistant Streptococcus pneumoniae (PRSP). Derivative 7l demonstrated antibacterial activity against both gram-positive and gram-negative bacteria. Derivatives 7f and 10a also demonstrated potent nanomolar Kd values in their binding to MurB.

Identification and characterization of small molecule modulators of KChIP/Kv4 function

Potassium channels and their associated subunits are important contributors to electrical excitability in many cell types. In this study, a yeast two-hybrid assay was used to identify inhibitors such as a diaryl-urea compound (CL-888) that binds to and modulates the formation of the Kv4/KChIP complex. CL-888 altered the apparent affinity of KChIP1 to Kv4.3-N in a Biacore assay, but did not dissociate the two proteins in size-exclusion chromatography experiments. Kv4.2/KChIP1 current amplitude and kinetics were altered with compound exposure, supporting the hypothesis of a compound-induced conformational change in the protein complex. Fluorescence spectroscopy of a unique tryptophan residue in KChIP1 was consistent with compound binding to the protein. Molecular modeling using the KChIP1 crystal structure indicates that compound binding may occur in a small tryptophan-containing binding pocket located on the hydrophilic side of the protein.

Phenyl thiazolyl urea and carbamate derivatives as new inhibitors of bacterial cell-wall biosynthesis

Over 50 phenyl thiazolyl urea and carbamate derivatives were synthesized for evaluation as new inhibitors of bacterial cell-wall biosynthesis. Many of them demonstrated good activity against MurA and MurB and gram-positive bacteria including MRSA, VRE and PRSP. 3,4-Difluorophenyl 5-cyanothiazolylurea (3p) with clog P of 2.64 demonstrated antibacterial activity against both gram-positive and gram-negative bacteria.

Two N-terminal domains of Kv4 K(+) channels regulate binding to and modulation by KChIP1

The family of calcium binding proteins called KChIPs associates with Kv4 family K(+) channels and modulates their biophysical properties. Here, using mutagenesis and X-ray crystallography, we explore the interaction between Kv4 subunits and KChIP1. Two regions in the Kv4.2 N terminus, residues 7-11 and 71-90, are necessary for KChIP1 modulation and interaction with Kv4.2. When inserted into the Kv1.2 N terminus, residues 71-90 of Kv4.2 are also sufficient to confer association with KChIP1. To provide a structural framework for these data, we solved the crystal structures of Kv4.3N and KChIP1 individually. Taken together with the mutagenesis data, the individual structures suggest that that the Kv4 N terminus is required for stable association with KChIP1, perhaps through a hydrophobic surface interaction, and that residues 71-90 in Kv4 subunits form a contact loop that mediates the specific association of KChIPs with Kv4 subunits.

Structure-based design approaches to cell wall biosynthesis inhibitors

This review summarizes some of the published attempts to incorporate protein and NMR structures in the design of new antibiotics that specifically target Cell Wall biosynthesis. Most of the steps involved in peptidglycan synthesis have been investigated as potential strategies against cell wall inhibition. Structural information has been most useful in the design of molecules in the Mur enzyme pathway, penicillin binding proteins and lactamases, as well as proteins that are part of the final steps of transglycosylation - in particular, d-Ala-d-Ala ligase. Several unique issues exist in the design of effective antibacterials, such as the significant differences in protein structure between organisms, such as the case of MurB in which a large amino acid loop that occupies the active site of the E. Coli is gone in the Staph aureus enzyme. Additionally, bacterial resistance is an important issue, and in some cases, structural information can be used to understand the source of this resistance. For example, mutations within the d-Ala-d-Ala ligases lead to the inability of Vancomycin antibiotics to bind.

Design, synthesis, SAR, and biological evaluation of highly potent benzimidazole-spaced phosphono-alpha-amino acid competitive NMDA antagonists of the AP-6 type

A series of 2-amino-(phosphonoalkyl)-1H-benzimidazole-2-alkanoic acids was synthesized and evaluated for NMDA receptor affinity using a [3H]CPP binding assay. Functional antagonism of the NMDA receptor complex was evaluated in vitro using a stimulated [3H]TCP binding assay and in vivo by employing an NMDA-induced seizure model. Several compounds of the AP-6 type demonstrated potent and selective NMDA antagonistic activity both in vitro and in vivo. In particular, [R(-)]-2-amino-3-(5-chloro-1-phosphonomethyl-1H-benzoimidazol-2-yl)-propionic acid (1) displayed an IC(50) value of 7.1 nM in the [3H]CPP binding assay and an ED(50) value of 0.13 mg/kg (ip) in the NMDA lethality model. Compound 1, when administered intravenously as a single bolus dose of 3 mg/kg following permanent occlusion of the middle cerebral artery in the rat, reduced the volume of infarcted brain tissue by 45%. These results support a promising therapeutic potential for compound 1 as a neuroprotective agent.

New generation dopaminergic agents. 1. Discovery of a novel scaffold which embraces the D2 agonist pharmacophore. Structure-activity relationships of a series of 2-(aminomethyl)chromans

A series of 2-(aminomethyl)chromans (2-AMCs) was synthesized and evaluated for their affinity and selectivity for both the high- and low-affinity agonist states (D2High and D2Low, respectively) of the dopamine (DA) D2 receptor. The 7-hydroxy-2-(aminomethyl)chroman moiety was observed to be the primary D2 agonist pharmacophore. The 2-methylchroman moiety was discovered to be an entirely novel scaffold which could be used to access the D2 agonist pharmacophore. Attaching various simple alkyl and arylalkyl side chains to the 7-hydroxy 2-AMC nucleus had significant effects on selectivity for the D2High receptor vs the 5HT1A and alpha 1 receptors. A novel DA partial agonist, (R)-(-)-2-(benzylamino)methyl)chroman-7-ol [R-(-)-35c], was identified as having the highest affinity and best selectivity for the D2High receptor vs the alpha 1 and 5HT1A receptors. Several regions of the 2-AMC nucleus were modified and recognized as potential sites to modulate the level of intrinsic activity. The global minimum conformer of the 7-hydroxy-2-AMC moiety was identified as fulfilling the McDermed model D2 agonist pharmacophoric criteria and was proposed as the D2 receptor-bound conformation. Structure-activity relationships gained from these studies have aided in the synthesis of D2 partial agonists of varying intrinsic activity levels. These agents should be of therapeutic value in treating disorders resulting from hypo- and hyperdopaminergic activity, without the side effects associated with complete D2 agonism or antagonism.

Structure-activity relationships among analogues of pemedolac, cis-1-ethyl-1,3,4,9-tetrahydro-4-(phenylmethyl)pyrano[3,4-b]indo le-1-a cetic acid, a potent analgesic agent

The syntheses of analogues of pemedolac (cis-1-ethyl-1,3,4,9-tetrahydro-4-(phenylmethyl)pyrano[3,4-b]indol e-1-acetic acid), a potent analgesic, are described. They were tested for analgesic and antiinflammatory effects in vivo and for inhibition of prostaglandin production in vitro. Analysis of structure-activity relationships shows that analgesic activity in this series is associated with 1S-cis stereochemistry, the presence of a pi-system (allyl or benzyl) at position 4, and a log P value greater than 4.0.

Synthesis and analgesic activity of pemedolac (cis-1-ethyl-1,3,4,9-tetrahydro-4-(phenylmethyl)pyrano[3,4-b]ind ole-1- acetic acid)

The synthesis of cis-1-ethyl-1,3,4,9-tetrahydro-4-(phenylmethyl)pyrano[3,4-b]indole -1-acetic acid, pemedolac (USAN), is described. This compound has been found to be a potent analgesic agent in primary screening. Pemedolac has been resolved and the active (+)-enantiomer assigned a 1S,4R absolute configuration on the basis of a crystallographic analysis of its (S)-(-)-borneol ester.

Thyroid carcinoma

Differentiated thyroid carcinoma was studied with regard to mode of presentation, initial findings, treatment and survival. The classic signs, symptoms, physical and scan findings were found to be present in approximately 70% of the patients. Thirty percent of the patients had either unusual presentations or findings. Prognosis was found to be dependent on age of presentation more than any other factor. The effects of neck metastasis, extracapsular invasion and recurrent laryngeal nerve involvement on long-term survival are studied in detail. patients with prior exposure to radiation were found to have more extensive disease and require more extensive surgery but ultimately had the same prognosis for 15-year cure. Treatment for distant metastatic disease by surgery, radioactive iodine and external radiation all resulted in long-term survival in certain cases.

Evolution of the clinically negative neck

A retrospective study was done of 602 patients with primary squamous cell carcinoma of the upper aerodigestive tract and a clinically negative neck (No) seen at the University of Illinois Hospital between 1960-1975. There was no uniform policy as to the treatment of No neck during this period; therefore in many of the patients, cervical lymph nodes were treated with elective neck dissection and others were followed until they became positive clinically. It was this difference which formed the basis for this study. All the patients were treated surgically; the patients were placed into two groups depending on whether they had radical neck dissection at the same time as resection of the primary. Group 1 consisted of 149 patients and had surgery for the primary only. The 253 patients of group 2 had surgery for the primary and also had a neck dissection. Both groups were analyzed for recurrences in the cervical region. In group 1, 12.9% of the patients developed either ipsilateral or contralateral metastases. Of the group 2 patients, 22% developed palpable nodal disease. The evolution of palpable nodal disease was analyzed by primary site, T-stage, and according to whether the tumor at the primary was controlled. Only 3% of the patients developed lymph nodes when the primary was controlled. The pathology reports of the neck specimens were studied to determine the relationship between a) positive node histology and b) number of nodes positive to the recurrence rate in the neck. Our results showed a 23% failure rate for the histologically positive group and a 21% failure rate for the negative group. The number of positive nodes did not seem to affect the recurrence rate.

Self-care is not a solipsistic trap: a reply to critics

This paper is an answer to criticism of the self-care, self-help movement in health recently advanced by Robert Crawford and other writers. The authors review the multiple and varied origins, motivations, and ideologies associated with self-care developments. It is maintained that the self-care movement embodies a broad, popular social resistance to the ills, inequities, and iatrogenic elements in highly technological health care systems. Empirical examination of specific programs and formulations of this movement reveals that it cannot be fitted into a simplistic "victim-blaming" ideology, but instead operates to decrease dependence and heighten individual and political/social awareness of hazards to health.

Genetic counseling in chronic disease

The counseling of those who are affected directly or indirectly by genetic disorders had traditionally been provided by physicians and geneticists. The author, using the example of hemophilia, argues that this type of counseling should be carried out not exclusively by medical personnel, but by social workers and others trained to deal with the social and psychological implications of such diseases.

Otologic complications of radiation therapy

Radiation therapy has proved to be a valuable modality in the management of patients with nasopharyngeal tumors. Routine follow-up of patients in the tumor clinic of the University of Illinois Eye and Ear Infirmary appeared to indicate an increasing incidence of otologic pathology. For this reason, a retrospective study focusing on the otologic findings in patients whose radiation therapy for nasopharyngeal tumors included the external auditory canal, middle ear space, or eustachian tube was performed. The results of this study are discussed in relationship to total radiation dosage, time of survival after therapy, and pretreatment otologic status. The complications covered a spectrum from intermittent serous otitis media to osteoradionecrosis of the external auditory canal. Possible contributing factors are discussed, and preventive neasures are suggested.