The pharmacology of GR203040, a novel, potent and selective non-peptide tachykinin NK1 receptor antagonist.

1. The in vitro and in vivo pharmacology of GR203040 ((2S, 3S)-2-methoxy-5-tetrazol-1-yl-benzyl-(2-phenyl-piperidin-3-y l)-amine), a novel, highly potent and selective non-peptide tachykinin NK1 receptor antagonist, was investigated in the present study. 2. GR203040 potently inhibited [3H]-substance P binding to human NK1 receptors expressed in Chinese hamster ovary (CHO) and U373 MG astrocytoma cells, and NK1 receptors in ferret and gerbil cortex (pKi values of 10.3, 10.5, 10.1 and 10.1 respectively). GR203040 had lower affinity at rat NK1 receptors (pKi = 8.6) and little affinity for human NK2 receptors (pKi < 5.0) in CHO cells and NK3 receptors in guinea-pig cortex (pKi < 6.0). With the exception of the histamine H1 receptor (pIC50 = 7.5). GR203040 had little affinity (pIC50 < 6.0) at all non-NK1 receptors and ion channels examined. Furthermore, GR203040 produced only weak inhibition of Na+ currents in SH-SY5Y neuroblastoma and superior cervical ganglion cells (pIC50 values < 4.0). GR203040 produced only weak antagonism of Ca(2+)-evoked contractions of rat isolated portal vein (pKn = 4.1). The enantiomer of GR203040, GR205608 (2R, 3R)-2-methoxy-5-tetrazol-1-yl-benzyl-(2-phenyl-piperidin-3-y l)-amine), had 10,000 fold lower affinity at the human NK1 receptor expressed in CHO cells (pKi = 6.3). 3. In gerbil ex vivo binding experiments, GR203040 produced a dose-dependent inhibition of the binding of [3H]-substance P to cerebral cortical membranes (ED50 = 15 micrograms kg-1 s.c. and 0.42 mg kg-1 p.o.). At 10 micrograms kg-1 s.c., the inhibition of [3H]-substance P binding was maintained for > 6 h. In the rat, GR203040 was less potent (ED50 = 15.4 mg kg-1 s.c.) probably reflecting, at least in part, its lower affinity at the rat NK1 receptor. 4. In guinea-pig isolated ileum and dog isolated middle cerebral and basilar arteries, GR203040 produced a rightward displacement of the concentration-effect curves to substance P methyl ester (SPOMe) with suppression of the maximum agonist response (apparent pKB values of 11.9, 11.2 and 11.1 respectively). 5. In anaesthetized rabbits, GR203040 antagonized reductions in carotid arterial vascular resistance evoked by SPOMe, injected via the lingual artery (DR10 (i.e. the dose producing a dose-ratio of 10) = 1.1 micrograms kg-1, i.v.). At a dose 20 fold greater than its DR10 value (i.e. 22 micrograms kg-1, i.v.), significant antagonism was evident more than 2 h after GR203040 administration. 6. In anaesthetized rats, GR203040 (3 and 10 mg kg-1, i.v.) produced a dose-dependent inhibition of plasma protein extravasation in dura mater, conjunctiva, eyelid and lip in response to electrical stimulation of the trigeminal ganglion. 7. It is concluded that GR203040 is one of the most potent and selective NK1 receptor antagonists yet described, and as such, has considerable potential as a pharmacological tool to characterize the physiological and pathological roles of substance P and NK1 receptors. GR203040 may also have potential as a novel therapeutic agent for the treatment of conditions such as migraine, emesis and pain.     

A series of novel, highly potent and selective agonists for the kappa-opioid receptor.

1. This paper describes the opioid receptor pharmacology and in vivo activity of several novel benzene-acetamidopiperidine and benzeneacetamidopiperazine analogues. 2. These compounds all showed potent, naloxone-reversible, full agonist activity in the field-stimulated rabbit vas deferens, indicating that they are kappa-opioid agonists; but showed very little activity in the rat or hamster vas deferens, indicating good selectivity with regard to mu- and delta-opioid receptors. 3. They were all potent antinociceptive agents, the most potent compound, GR 103545, having an ED50 value in the mouse abdominal constriction test of 0.25 micrograms kg-1 s.c. The compounds also produced sedation and diuresis, but had little effect on respiration rate or gastrointestinal motility. 4. It is concluded that the seven novel compounds described are all potent and selective agonists for the kappa-opioid receptor.     

Pneumatic retinopexy versus scleral buckle. Preferences of Vitreous Society members, 1990.

A survey was conducted among the 1990 members of the Vitreous Society in order to measure their acceptance of pneumatic retinopexy. They were asked which treatment they would prefer should they suffer a hypothetical detachment. The choices were limited to pneumatic retinopexy or scleral buckling (encircling or segmental). The majority of respondents selected a scleral buckling procedure for a phakic retinal detachment with two adjacent superior temporal quadrant tears. Surgeons who had been in practice for 10 years or less (median for entire group = 10 years) were significantly more likely to select a pneumatic retinopexy procedure. As the details of the hypothetical detachment became more complicated with myopia, additional tears, vitreous hemorrhage, or lattice degeneration with a positive family history, the respondents selected a scleral buckling procedure with greater frequency, and the differences between the choices of the surgeons became nonsignificant. This survey shows that many surgeons feel pneumatic retinopexy is an acceptable alternative to buckling surgery in select cases. There were no trends by geographic location.     

Novel mutations in the thymidine kinase and DNA polymerase genes of acyclovir and foscarnet resistant herpes simplex viruses infecting an immunocompromised patient.

BACKGROUND: Mutations in the thymidine kinase (TK) and DNA polymerase (pol) genes of herpes simplex virus (HSV) may confer resistance to antiviral drugs, particularly in the context of immunosuppression induced by infection with the human immunodeficiency virus (HIV). OBJECTIVES: To characterise the HSV type 2 (HSV-2) TK and DNA pol genes in an immunocompromised patient with clinical resistance to both acyclovir and foscarnet. STUDY DESIGN: The TK and DNA pol genes of isolates obtained over a 2-year period from an AIDS patient with severe genital herpes infection were characterised both phenotypically and genotypically. RESULTS: HSV strains that were acyclovir resistant/foscarnet sensitive, acyclovir sensitive/foscarnet sensitive and acyclovir resistant/foscarnet resistant were isolated during this time. The TK gene of all the acyclovir resistant isolates contained a large 969 bp deletion which extended into a downstream untranslated region. The foscarnet resistance was associated with an S725G mutation in a conserved region (region II) of the herpesvirus DNA pol gene. CONCLUSIONS: Clinical and virological suppression of the infection was not always associated with subsequent reactivation with wild-type virus. Mutations of the nature we describe have not previously been reported occurring simultaneously in HSV strains isolated from patients treated with acyclovir and foscarnet.     

Lipid and insulin concentrations in obese postmenopausal women: separate effects of energy restriction and weight loss.

The separate effects of energy restriction and weight loss on serum lipids were studied in 24 postmenopausal moderately obese women before and after weight loss of greater than 10 kg to normal weight. Fasting serum triglycerides (TGs), total cholesterol (TC), high-density-lipoprotein (HDL) and low-density-lipoprotein (LDL) cholesterol, and insulin were measured at the end of four 10-d in-hospital phases, two before and two after weight loss: phase I, stable weight; phase II, 3350 kJ/d(800 kcal/d), followed by outpatient weight loss; phase III, 3350 kJ/d (800 kcal/d); and phase IV, stable weight. Diet composition and exercise were constant the entire study. Energy-restriction effect was determined by comparing average values in stable-weight phases (I and IV) with low-energy phases (II and III); weight-loss effect was determined by comparing values in obese phases (I and II) with reduced-weight phases (III and IV). Energy restriction lowered TG, TC, LDL cholesterol, the LDL-HDL cholesterol ratio, and insulin and raised HDL cholesterol (all P less than 0.05). Weight loss lowered TG, TC, LDL cholesterol, and insulin (all P less than 0.01) but did not change HDL cholesterol or the LDL-HDL cholesterol ratio. The results suggest that reduction to a weight-steady nonobese state significantly lowers TG, TC, and LDL cholesterol but does not improve HDL cholesterol or the LDL-HDL cholesterol ratio.     

Liver transplant in a patient with a ventriculoperitoneal shunt.

There are no published accounts of patients with ventriculoperitoneal shunts undergoing liver transplantation in the literature. Because patients with ventriculoperitoneal shunts are prone to infections, this may be a theoretical contraindication to transplantation. We present a case of a patient with cirrhosis who had a ventriculoperitoneal shunt placed many years prior to transplantation. The patient had no neurological complications and the shunt was intact and functioning. Prior to transplantation, the patient underwent a ventriculoperitoneal to ventriculopleural shunt conversion that was reversed posttransplantation. Apart from some minor complications, the patient has done remarkably well from a graft and neurological perspective. In conclusion, patients who have ventriculoperitoneal shunts may be considered for liver transplantation as the risk of infectious and neurological complications is low and there are no deleterious effects on graft survival.