Aminoacetyl moiety as a potential surrogate for diacylhydrazine group of SC-51089, a potent PGE2 antagonist, and its analogs.

8-Chlorodibenz[b,f][1,4]oxazepine-10(11H)-carboxylic acid, 2-[1-oxo-3-(4-pyridinyl)propyl]hydrazide, monohydrochloride (1, SC-51089) is a functional PGE2 antagonist selective for the EP1 receptor subtype with antinociceptive activity. During metabolism in cultured rat hepatocytes, SC-51089, which contains a diacylhydrazine moiety, has been shown to release hydrazine. Analogs of SC-51089, in which the diacylhydrazine functionality has been replaced by isosteric and isoelectronic groups, have been synthesized and have been shown to be analgesics and PGE2 antagonists of the EP1 subtype. This report discusses the structure-activity relationships within these series.

Systemic analgesic activity and delta-opioid selectivity in [2,6-dimethyl-Tyr1,D-Pen2,D-Pen5]enkephalin.

The cyclic peptide [2,6-dimethyl-Tyr1,D-Pen2,D-Pen5]enkephalin (2) was synthesized by solid-phase techniques and contains the optically pure unnatural amino acid 2,6-dimethyltyrosine (DMT) as a replacement for the Tyr1 residue of [D-Pen2,D-Pen5]enkephalin (DPDPE, 1). This structural modification resulted in a 10-fold increase in the potency of 2 at the delta opioid receptor and a 35-fold increase in potency at the mu receptor while substantial delta receptor selectivity was maintained. In addition, 2 was 86-fold more effective than 1 at inhibiting electrically stimulated contractions of the mouse vas deferens. In the hot plate test, 2 was 7-fold more potent than 1 after intracerebroventricular administration in the mouse. While 1 was inactive following systemic administration of doses as high as 30 mg/kg, subcutaneous administration of 2 significantly inhibited writhing with an ED50 of 2.6 mg/kg. These results demonstrate that the potency and systemic activity of DPDPE are significantly increased by replacement of Tyr1 with DMT.

Analogs of the delta opioid receptor selective cyclic peptide [2-D-penicillamine,5-D-penicillamine]-enkephalin: 2',6'-dimethyltyrosine and Gly3-Phe4 amide bond isostere substitutions.

In order to develop systemically-active opioid peptides, the delta-selective, opioid pentapeptide [D-Pen2,D-Pen5]-enkephalin (DPDPE) was modified by esterification and by substitution of 2',6'-dimethyltyrosine for tyrosine to yield 4. Compound 4 was on the order of 8- and 800-fold more active than DPDPE in both delta and mu opioid radioligand binding assays, respectively, in rat neural membrane suspensions. Compound 4 was considerably more potent than DPDPE at inhibiting contractions of electrically-stimulated mouse vas deferens in vitro, and this effect was very sensitive to naltrindole, a delta-selective opioid antagonist. These observations can be taken as indication that 4 exerts its effects through delta opioid receptors. This interpretation is supported by the finding that the EC50 value of 4 derived in the smooth muscle assay is very similar to that derived in NG108-15 neuroblastoma cells, a preparation devoid of mu receptors. Unlike DPDPE, 4 exhibited significant, naloxone-sensitive, antinociceptive activity when administered systemically, as measured by inhibition of phenylbenzquinone-induced stretching in mice (ED50 = 2.1 mg/kg). Compound 4 also displayed significant antinociceptive activity following systemic administration as measured by its action in mice to increase latencies for tail withdrawal from radiant heat (ED50 = 50 mg/kg). Compound 4 did not produce morphine-like discriminative stimulus effects in rats trained to discriminate 3.0 mg/kg morphine from vehicle at doses ranging from 30 to 120 mg/kg. This observation can be interpreted as indication that within this dosage range there is an absence of morphine-like subjective effects. Physical dependence, however, could be induced in mice at higher doses of 4 under a progressively-graded, 4-day dose regimen. Congeners of 4 with amide bond surrogates for the Gly-Phe amide bond (oxymethylene, trans-double bond, and bismethylene isosteres) in the cyclic core of DPDPE were prepared in an attempt to increase the antinociceptive activity of 4. While some of the congeners were active in the in vitro assays, they did not display significant antinociceptive activity following systemic administration. The preparation of all the compounds was accomplished by solution-phase methods. The mechanisms which might underlie the biological and systemic activity of 4 are discussed.

Enkephalin analogs as systemically active antinociceptive agents: O- and N-alkylated derivatives of the dipeptide amide L-2,6-dimethyltyrosyl-N-(3-phenylpropyl)-D-alaninamide.

A number of O- and N-alkylated derivatives of the antinociceptive, orally active, mu-opioid-selective truncated enkephalin analog L-2,6-dimethyltyrosyl-N-(3-phenylpropyl)-D-alaninamide (2, SC-39566) were synthesized to explore the structure-activity relationships of the series. The parent molecule is quite forgiving of substitution on the tyrosyl phenolic moiety and on the alanyl nitrogen. The tyrosyl and (phenylpropyl)amide NH sites, however, appear to be critical to interactions with the receptor, for even modest changes at these sites cause great loss of binding potency.

N-substituted dibenzoxazepines as analgesic PGE2 antagonists.

8-Chlorodibenz[b,f][1,4]oxazepine-10(11H)-carboxylic acid, 2-acetylhydrazide (1, SC-19220) has been previously reported by us and others to be a PGE2 antagonist selective for the EP1 receptor subtype with antinociceptive activities. Analogs of SC-19220, in which the acetyl moiety has been replaced with pyridylpropionyl groups and their homologs, have been synthesized as illustrated by compounds 13 and 29. These and other members of this series have been shown to be efficacious analgesics and PGE2 antagonists of the EP1 subtype. This report discusses the structure activity relationships within this series.

Use of Counter and rocket immunoelectrophoresis in acute respiratory infections due to Streptococcus pneumoniae.

The use of Counter immunoelectrophoresis (CIE) for the detection of pneumococcal capsular antigen in the sputum and serum of patients suffering from acute respiratory infections is described. The CIE of sputum gave positive results in 224 (99%) out of 225 samples in which Streptococcus pneumoniae was isolated by cultural techniques, and in 23 (9%) out of 262 samples in which no or other potential pathogens had been isolated. In the detection of capsular antigen in serum, CIE was positive in 32 (35%) out of 92 pneumonia cases and was associated with an increase in mortality.

Laboratory contamination of blood cultures.

A prospective study of the use of a laminar flow cabinet, an exhaust-ventilated safety hood, and the open bench for the microbiological examination of blood is described. Blood samples from 1600 patients were subcultured on the open bench, 2700 in a safety hood, and 2607 in a laminar flow cabinet. Use of the laminar flow cabinet produced a significantly greater level of contamination than the other methods, and it is concluded that the exhaust-ventilated safety hood should be used for this procedure.

Evaluation of a dehydrated test strip for the detection of yeasts.

Use of a dehydrated test strip for the detection of yeasts is compared with traditional culture on Sabouraud's agar containing 50 mug/ml chloramphenicol. While the selective medium of the strip is satisfactory for the isolation of species of Candida, Torulopsis glabrata grows only very slowly. The strip has the advantage of a long storage life without deterioration, but a high cost may preclude general usage. The numbers of yeasts collected by a bacteriological swab disadvantages of the selective medium, and the value of direct microscopy in the examination of vaginal swabs are discussed.

SC-46275: a potent and highly selective agonist at the EP3 receptor.

The agonist properties of SC-46275 have been investigated in EP receptor subtype-specific smooth muscle assays. In the isolated guinea pig vas deferens (GPVD), prostaglandin E2 (PGE2), via the EP3 receptor, potently inhibited electrically induced contractions with an EC50 of 5.4 +/- 1.1 nM. Sulprostone and misoprostol were both potent relaxers of the GPVD yielding EC50s of 1.6 +/- 0.4 nM and 4.3 +/- 0.9 nM, respectively, while butaprost (10,000 nM) was inactive. SC-46275 was by far the most potent agonist in the GPVD exhibiting an EC50 of 0.04 +/- 0.02 nM. PGE2, via the EP1 receptor, stimulates contractions in the longitudinal muscle layer of the guinea pig ileum (GPIL) with an EC50 of 74.4 +/- 10.6 nM. SC-46275 was extremely weak in this preparation, generating only 33% of the maximal PGE2 effect at 30,000 nM. The circular muscle layer of guinea pig ileum (GPIC) is responsive to inhibition of electrically stimulated contractions by PGE2 (EC50 = 179.6 +/- 20.8 nM) via the EP2 receptor. SC-46275 (up to 10,000 nM) was completely inactive in this preparation. We conclude from these findings that SC-46275 is a very potent and highly selective EP3 receptor agonist. SC-46275 should prove to be an extremely valuable tool in probing the physiological significance of EP3 receptors. The high potency of SC-46275 at the EP3 receptor may account for its antisecretory and cytoprotective actions, while its lack of activity at the EP1 or EP2 sites may explain its very weak diarrheagenic potential.

Human nail dust and precipitating antibodies to Trichophyton rubrum in chiropodists.

The toe-nail dust produced in chiropodial practice causes allergic hypersensitivity and Trichophyton rubrum is the most common fungal cause of nail dystrophy. Use of drills and burrs to reduce the thickness of hyperkeratotic nails generates dust and chiropodists develop precipitins to T. rubrum. A survey into the prevalence of these antibodies in 11.2% of state-registered chiropodists is described and 14% of the profession estimated to have antibodies to T. rubrum. In response to a questionnaire 49% stated that toe-nail dust troubled them; complaints of nasal and eye symptoms were 72 and 41% respectively. In 384 chiropodists ventilatory function was tested with a vitalograph. Restrictive lung disease appears to be more common in chiropodists than other sedentary workers.

2,4-Disubstituted oxazoles and thiazoles as latent pharmacophores for diacylhydrazine of SC-51089, a potent PGE2 antagonist.

8-Chlorodibenz[b,f][1,4]oxazepine-10(11H)-carboxylic acid, 2-[1-oxo-3-(4-pyridinyl)propyl]hydrazide, monohydrochloride (1, SC-51089) is a functional PGE2 antagonist selective for the EP1 receptor subtype with antinociceptive activity. Analogues of SC-51089, in which the diacylhydrazine moiety has been replaced with 2,4-disubstituted-oxazoles and-thiazoles, are described.

Antinociception produced by oral, subcutaneous or intrathecal administration of SC-39566, an opioid dipeptide arylalkylamide, in the rodent.

This study characterized the prototypic "minimum structure" enkephalin SC-39566 [2,6-dimethyl-L-tyrosinyl-D-alanine-(3-phenyl-1-propyl)-amide hydrochloride]. SC-39566 bound with highest affinity to mu opioid receptors (Ki, 0.13 nM), as well as to delta (Ki, 4.0 nM) opioid receptors in the rat brain, and with much lower affinity to kappa opioid receptors (Ki, 83.8 nM) in the guinea pig brain. In the mouse, SC-39566 inhibited phenylbenzoquinone-induced writhing and increased tail-flick and hot-plate latencies in a dose-dependent manner after either s.c. or p.o. (i.g.; intragastrical) administration. This antinociception was antagonized by the opioid antagonist naloxone, but not by alpha adrenergic, serotonergic, histaminergic, muscarinic cholinergic or dopaminergic receptor antagonists. In the rat, SC-39566 dose-dependently inhibited acetic-acid-induced writhing after s.c. or i.g. administration and increased response latencies in the tail-flick and hot-plate test after s.c. or intrathecal (i.t.) administration. The increase in tail-flick latency produced by s.c. SC-39566 in the rat was antagonized by s.c. naloxone with an apparent pA2 value of 7.9. Pretreatment with naltrindole, a delta opioid receptor antagonist, increased the ED50 of SC-39566 by only 1.7-fold. In addition, the increase in tail-flick latency produced by i.t. SC-39566 was not antagonized by i.t. administration of naltrindole or nor-binaltorphimine, a kappa receptor antagonist. These data suggest that the antinociceptive activity of SC-39566 is mediated predominantly by mu opioid receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibiotic sensitivity of bacteria associated with community-acquired urinary tract infection in Britain.

Twelve laboratories in different parts of Britain each supplied approximately 80 consecutive urinary bacterial isolates from community patients. All strains were identified by a central laboratory, where sensitivity to a variety of orally administered antimicrobials was determined by microtitre broth dilution. 65.1% of isolates were Escherichia coli, 23.4% 'coliforms' other than E. coli, 4.6% Proteus and Morganella spp., 1.8% Pseudomonas spp., 2.4% enterococci, 0.7% group B streptococci, 1.5% coagulase-negative staphylococci and 0.5% Staphylococcus aureus. Using previously published breakpoint sensitivity values, 98.9% of all isolates were found to be sensitive to norfloxacin and to ciprofloxacin, 95.7% to co-amoxiclav, 86.8% to nitrofurantoin, 77.4% to cephalexin, 75.6% to trimethoprim, 75.0% to cephradine and 51.7% to amoxycillin. There were some differences in sensitivities between centres, particularly those of the cephalosporins. Using standard breakpoints, submitting laboratories were found to overestimate sensitivity to nitrofurantoin and to underestimate sensitivity to the quinolones and to co-amoxiclav; there was considerable overestimation of sensitivity to cephalosporins.