Different muscarine receptors mediate the prejunctional inhibition of [3H]-noradrenaline release in rat or guinea-pig iris and the contraction of the rabbit iris sphincter muscle

Summary To investigate the muscarine receptor type mediating inhibition of [³H]-noradrenaline release from the isolated rat and guinea-pig iris we have determined the potency of antimuscarinic drugs to antagonize the methacholine-induced inhibition of [³H]-noradrenaline overflow evoked by field stimulation (3 Hz, 2 min). The prejunctional apparent affinities were compared with those obtained for postjunctional muscarine receptors mediating the methacholine-induced contraction of the isolated rabbit iris sphincter muscle.Prejunctional apparent affinity constants of pirenzepine (6.67), himbacine (8.51), methoctramine (7.92), 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP, 8.00), hexahydro-difenidol enantiomers (6.92, (R); 5.77, (S)) in the rat iris and methoctramine (7.58) in the guinea-pig iris indicate the presence of M₂ receptors. Although the post-junctional affinity constants in the rabbit iris sphincter of methoctramine (5.93), gallamine (3.92), and 4-DAMP (9.07) confirm our previous suggestions of the presence of M₃-like receptors, the results obtained with the hexahydro-difenidol enantiomers do not agree with that concept. The post-junctional affinity constants of the hexahydro-difenidol enantiomers were not different from the prejunctional values (6.86, (R); 5.55, (S)), indicating a similar and low degree of stereoselectivity for these stereoisomers at both receptor sites (14 and 17, (R)/(S)-ratios, respectively). Hence, the postjunctional muscarine receptor in the rabbit iris sphincter fails to exhibit the high degree of stereo selectivity observed for hexahydro-difenidol enantiomers at M₃ receptors on other smooth muscles.This study was supported by the Deusche Forschungsgemeinschaft (Fu 163/2) Send offprint requests to H. Fuder at the above address     

Influenza A Strain-Dependent Pathogenesis in Fatal H1N1 and H5N1 Subtype Infections of Mice

To determine if fatal infections caused by different highly virulent influenza A viruses share the same pathogenesis, we compared 2 different influenza A virus subtypes, H1N1 and H5N1. The subtypes, which had shown no pathogenicity in laboratory mice, were forced to evolve by serial passaging. Although both adapted viruses evoked diffuse alveolar damage and showed a similar 50% mouse lethal dose and the same peak lung concentration, each had a distinct pathologic signature and caused a different course of acute respiratory distress syndrome. In the absence of any virus labeling, a histologist could readily distinguish infections caused by these 2 viruses. The different histologic features described in this study here refute the hypothesis of a single, universal cytokine storm underlying all fatal influenza diseases. Research is thus crucially needed to identify sets of virulence markers and to examine whether treatment should be tailored to the influenza virus pathotype.     

Adalimumab for psoriasis patients who are non-responders to etanercept: open-label prospective evaluation

Background  Targeted biologic therapies have made a significant impact on the treatment for moderate to severe psoriasis. In the United Kingdom, the National Institute for Health and Clinical Excellence recommends etanercept, a human recombinant tumour necrosis factor (TNF) receptor fusion protein, for moderate to severe psoriasis patients who have failed conventional therapies. There is, however, no data available on the role of other TNF antagonists for patients who have failed etanercept. Adalimumab, a fully human, anti-TNF monoclonal antibody, is approved for treatment of moderate to severe psoriasis.
Objectives  To assess the efficacy and safety of adalimumab (40 mg weekly) in psoriasis patients who were non-responders to high-dosage etanercept (50 mg twice weekly).
Methods  All patients attending a tertiary referral service for severe psoriasis who were non-responders to high-dosage etanercept [i.e. failed to achieve ≥ 50% improvement in Psoriasis Area and Severity Index (PASI 50) after 12 weeks of treatment] were considered for open-label adalimumab therapy for 12 weeks. Details on clinical course, PASI, Dermatology Life Quality Index (DLQI) and adverse events were recorded at baseline and weeks 2, 4, 8, and 12.
Results  Four of five patients in this study had reached at least PASI 50 by week 12. Of these, two patients achieved a 75% improvement in PASI (PASI 75). No serious adverse events were reported.
Conclusions  Initial data from this open-label prospective evaluation suggests that weekly adalimumab therapy is an effective treatment for patients with severe psoriasis who had failed to respond to at least 3 months of high-dosage etanercept.     

Binding affinities of hexahydro-difenidol and hexahydro-sila-difenidol analogues at four muscarinic receptor subtypes: constitutional and stereochemical aspects

Hexahydro-sila-difenidol and eight analogues behaved as simple competitive inhibitors of [3H]N-methyl-scopolamine binding to homogenates from human neuroblastoma NB-OK 1 cells (M1 sites), rat heart (M2 sites), rat pancreas (M3 sites), and rat striatum 'B' sites (M4 sites). Pyrrolidino- and hexamethyleneimino analogues showed the same selectivity profile as the parent compound. Hexahydro-sila-difenidol methiodide and the methiodide of p-fluoro-hexahydro-sila-difenidol had a higher affinity but a lower selectivity than the tertiary amines. Compounds containing a p-methoxy, p-chloro or p-fluoro substituent in the phenyl ring of hexahydro-sila-difenidol showed a qualitatively similar selectivity profile as the parent compound (i.e., M1 = M3 = M4 greater than M2), but up to 16-fold lower affinities. o-Methoxy-hexahydro-sila-difenidol has a lower affinity than hexahydro-sila-difenidol at the four binding sites. Its selectivity profile (M4 greater than M1, M3 greater than M2) was different from hexahydro-sila-difenidol. Replacement of the central silicon atom of hexahydro-sila-difenidol, p-fluoro-hexahydro-sila-difenidol and their quaternary (N-methylated) analogues by a carbon atom did not change their binding affinities significantly. The four muscarinic receptors showed a higher affinity for the (R)- than for the (S)-enantiomers of hexahydro-difenidol, p-fluorohexahydro-difenidol and their methiodides. The stereoselectivity varied depending on the receptor subtype and drug considered.     

Accuracy of dual-energy radiographic absorptiometry of the lumbar spine: cadaver study

Dual-energy radiographic absorptiometry (DRA) was used to measure the bone mineral content and area density of lumbar vertebrae (L2-L3) in 11 cadavers. These data were subsequently compared with measured ash content and density. Excellent correlation was obtained between bone mineral content measured with DRA and ash weight (r = .963, P less than .0001). The accuracy error in determining mineral content in lumbar vertebrae with DRA was about 9%. In addition, strong correlation was observed between bone mineral density measured with DRA and ash density (r = .881, P less than .0001).     

A comparative study of the effects on the skin of a classical bar soap and a syndet cleansing bar in normal use conditions and in the soap chamber test

Background/aims: The skin irritation potential of a body cleansing product is often compared under exaggerated test conditions, although the product is intended to be used at home with repetitive and brief contact with the skin. The aim of this study was to determine how much patch testing is predictive of the clinical, sub-clinical and subjective cutaneous effects of products used at home by consumers for their normal hygienic cleansing.
Methods: A double-blind comparative study of the normal use of an alkaline soap bar and a syndet at home during 10 consecutive weeks was performed on two identical groups of 25 healthy female subjects. The eventual skin changes observed at different anatomical skin sites were evaluated by clinical visual examination and by bioengineering measurements before the start of the study and then every 2 weeks. The objective measurements were compared with the subject's perceptions of dryness, tightness and product irritancy during the testing.
Results: The bioengineering measurements did not show any significant changes on all the anatomical skin sites, except for a small increase in skin pH with the classical soap bar. However, a trend appeared, showing that the alkaline soap bar is perceived by the subjects themselves as more of an irritant than the syndet bar. In the soap chamber test, the bar soap showed a significantly higher irritancy than the syndet bar.
Conclusion: This study showed that cutaneous irritation induced by cleansing products in patch testing is not necessarily predictive of the irritation likely to occur in normal use conditions. Finally, a clear relationship could be demonstrated between the results of the soap chamber test and the consumer perception of both cleansing bars.     

Detection of QTc interval prolongation using jacket telemetry in conscious non-human primates: comparison with implanted telemetry

Background and Purpose: During repeat-dose toxicity studies, ECGs are collected from chemically or physically-restrained animals over a short timeframe. This is problematic due to cardiovascular changes caused by manual restraint stress and anesthesia, and limited ECG sampling. These factors confound data interpretation, but may be overcome by using a non-invasive jacket-based ECG collection (JET). The current study investigated whether a jacketed external telemetry system could detect changes in cardiac intervals and heart rate in non-human primates (NHPs), previously implanted with a PCT transmitter.Experimental Approach: Twelve male cynomolgus monkeys were treated weekly with vehicle or sotalol (8, 16, 32 mg kg⁻¹) p.o. ECGs were collected continuously for 24 hours, following treatment, over 4 weeks. A satellite group of six NHPs was used for sotalol toxicokinetics.Key Results: Sotalol attained C_max values 1–3 hours after dosing, and exhibited dose-proportional exposure. In jacketed NHPs, sotalol dose-dependently increased QT/QTc intervals, prolonged PR interval, and reduced heart rate. Significant QTc prolongation of 27, 54 and 76 msec was detected by JET after 8, 16, and 32 mg kg⁻¹ sotalol, respectively, compared with time-matched vehicle-treated animals. Overall, JET-derived PR, QT, QTc intervals, QRS duration, and heart rate correlated well with those derived from PCT.Conclusions and Implications: The current findings clearly support the use of JET to quantify cardiac interval and rhythm changes, capable of detecting QTc prolongation caused by sotalol. JET may be a preferred method compared to restraint-based ECG because high-density ECG sampling can be collected in unstressed conscious monkeys, over several weeks.     

The cytoskeleton in Chediak-Higashi syndrome fibroblasts

The Chediak-Higashi syndrome (CHS) trait is expressed in cultured human skin fibroblasts as an abnormal perinuclear concentration of moderately enlarged lysosomes. The cytoskeleton of CHS fibroblasts appears intact. Microtubules are normal in number and morphology, as assessed by colchicine binding studies, antitubulin immunofluorescence, and electron microscopy. Deformability by shear force is unaltered and microfilaments are abundant. However, CHS lysosomes appear to interact abnormally with the cytoskeleton, since the perinculear aggregation partially disperses after depolymerization of cell microtubules with colchicine. These results suggest that CHS is associated with a defect of either the lysosomal membrane itself or of lysosomal membrane- microtubule interaction.