Uniportal robotic assisted surgery for anatomical lung resection-First German experience

BACKGROUND

Uniportal robotic-assisted thoracic surgery (uRATS) has emerged as a promising technique with potential advantages over multiportal approaches. This study aims to evaluate our initial outcomes of uRATS.

MATERIAL AND METHODS

Five patients underwent anatomic lung resections with systematic nodal dissection through a uniportal robotic approach by one surgeon. The results were compared to the results of the first five uniportal video-assisted thoracic surgery (uVATS) anatomical resections performed by the same surgeon.

RESULTS

No adverse events occurred during the uRATS-procedures. Comparable surgical outcomes were observed between uRATS and uVATS, including hospital stays, complication rates, and blood loss. The average procedural time was slightly but non-significantly longer in the uRATS-group. Average pain-scores were lower in the uRATS group. One patient in each group experienced major postoperative complications, with one case of in-hospital mortality in the uRATS-group.

CONCLUSION

The outcomes of uRATS/uVATS were comparable, highlighting the potential and the feasibility of this technique. Prospective studies comparing the learning curves, complication rate and hospital-stay are required in order to justify the superiority of robotics over uVATS.

Swiss Practice Recommendations for the Management of Hidradenitis Suppurativa/Acne Inversa

Hidradenitis suppurativa (HS) is a painful, inflammatory, debilitating skin disease with a chronic intermittent course. The central pathogenetic event seems to be the occlusion of the hair follicle. HS has a 1-year prevalence of about 1%. It typically presents after puberty with painful, deep-seated, inflamed lesions in the apocrine gland-bearing areas of the body: most commonly the axillae, inguinal, and anogenital regions. HS has a high negative impact on patients' quality of life even in patients with only limited disease burden, and the diagnosis of HS is often made with a long diagnostic delay. In this practical short version we present diagnostic and therapeutic recommendations which are based on a systematic literature search as well as an informal expert consensus of Swiss dermatologists and dermatosurgeons.

Grover's-like drug eruption in a patient with metastatic melanoma under ipilimumab therapy

Background

Dermatologic toxicity is an important adverse effect of immune checkpoint inhibitors targeting cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and programmed cell death 1 receptor (PD-1) or PD ligand 1 (PD-L1). Skin toxicity most commonly includes a maculopapular erythematous rash and pruritus. Rarely life threatening complications such as Steven’s Johnson syndrome or toxic epidermal necrolysis may occur.

Case presentation

Here we report the uncommon event of a drug-induced transient acantholytic dermatosis (Grover’s disease) in a 73-year-old Caucasian male treated with ipilimumab for metastatic melanoma. Five weeks after initiation of therapy, the patient developed a widespread polymorphic papulovesicular dermatosis on the trunk and proximal extremities with intense pruritus. Skin biopsy showed acantholytic dyskeratosis with interface dermatitis consistent with a Grover’s-like drug eruption.

Conclusions

These findings should raise awareness for uncommon immune-related dermatological toxicities of immunomodulatory antibodies targeting the CTLA-4 signaling axis. We recommend biopsies of unexpected skin lesions to rapidly identify dermatological adverse events of immune checkpoint inhibitors.

Vitrectomy with or without encircling band for pseudophakic retinal detachment: a multi-centre, three-arm, randomised clinical trial. VIPER Study Report No. 1--design and enrolment

PURPOSE

Scleral buckling is currently used in addition to vitrectomy for the treatment of pseudophakic retinal detachment (PRD) to better support the vitreous base and better visualisation of the periphery.

AIMS

The aims of this study are to evaluate (1) whether the combination of 20 G vitrectomy and scleral buckling is superior to 20 G vitrectomy alone (control) (confirmatory), and (2) whether transconjunctival 23/25 G vitrectomy is non-inferior to 20 G vitrectomy (both without scleral buckling) regarding operation success (exploratory).

METHODS

The VIPER (Vitrectomy Plus Encircling Band Vs. Vitrectomy Alone For The Treatment Of Pseudophakic Retinal Detachment) study is an unmasked, multi-centre, three-arm randomised trial. Patients with PRD were eligible, excluding complicated retinal detachment or otherwise severe ophthalmologic impairment. Patients were randomised to one of three interventions: 20 G vitrectomy alone (control C), combination of 20 G vitrectomy and circumferential scleral buckling (experimental treatment E1) or 23/25 G vitrectomy alone (experimental treatment E2). The primary endpoint is the absence of any indication for a retina re-attaching procedure during 6 months of follow-up. Secondary endpoints include best corrected visual acuity, retina re-attaching procedures, complications and adverse events.

RESULTS

From June 2011 to August 2013, 257 patients were enrolled in the study. The internet randomisation service assigned 100 patients each to the treatment arms C and E1, and 57 patients to treatment E2. The imbalance is due to the fact that several retinal surgeons did not qualify for performing E2. The random assignment was stratified and balanced (ie, 1:1 or 1:1:1 ratio) by surgeon.

CONCLUSIONS

The described study represents a methodologically rigorous protocol evaluating the benefits of three different vitrectomy approaches to PRD. The projected results will help to establish their overall efficacy and will permit conclusions regarding their relative value.

TRIAL REGISTRATION NUMBER

DRKS00003158 (German Clinical Trials Register, DRKS).

Vesicle solubilization by bile salts: comparison of macroscopic theory and simulation

Lipid metabolism is accompanied by the solubilization of lipid bilayer membranes by bile salts. We use Brownian dynamics simulations to study the solubilization of model membranes and vesicles by sodium cholate. The solubilization pathways of small and large vesicles are found to be different. Both results for small and large vesicles can be compared with predictions of a macroscopic theoretical description. The line tension of bilayer edges is an important parameter in the solubilization process. We propose a simple method to determine the line tension by analyzing the shape fluctuations of planar membrane patches. Macroscopic mechanical models provide a reasonable explanation for processes observed when a spherical vesicle consisting of lipids and adsorbed bile salt molecules is transformed into mixed lipid-bile salt micelles.

[Small red sports on the feet and diarrhoea with 63]

We report a case of a 63 year old woman with progressive small red spots that can not be diminished with pressure. They appeared on the feet first and spread out to the legs, trunk and arms. This was accompanied with non-bloody diarrhoea and the laboratory diagnostics showed minor impairment of the kidney. The biopsy of the skin showed deposits of immunoglobulin A and C3 complement in the stratum papillare of the small vessels and a necrosis of the wall, which made the diagnosis of the Schönlein-Henoch purpura clear. It was accompanied by a systemic participation of the gastrointestinal tract. The quick reversible renal insufficiency was rather interpreted as a prerenal cause, than as an origin of the Schönlein-Henoch purpura. We further discussed the diagnostic methods, the aetiology and the possible therapy options.

Factors contributing to severe early childhood caries in south-west Germany

OBJECTIVES

The purpose of this study is to investigate the contribution of selected variables to the occurrence of severe early childhood caries (S-ECC) in 3- to 5-year-old kindergarten children.

METHODS

A cross-sectional study was conducted in 2010 in 30 randomly selected kindergartens in the German Rhein-Neckar district. After informed consent, parents were asked to complete a questionnaire. The oral examinations took place in the selected kindergartens and the WHO methods as well as the criteria proposed by the American Academy of Pediatric Dentistry were followed. Logistic regression was applied to explore the main factors contributing to S-ECC in a multivariate model.

RESULTS

In all, 1,007 children aged 3 to 5 years with an average age of 4.1 (SD = 0.8) years were examined. Five variables were associated significantly with the occurrence of S-ECC: breastfeeding for more than 12 months (OR = 3.27), use of the nursing bottle in bed (OR = 3.08), start of tooth brushing after the first anniversary (OR = 2.42), regular visits at the dentists (OR = 0.14) and mother with immigration background (OR = 4.05). Prevalence rate of S-ECC was 9.5 %. The mean d(3+4)mft values were 5.69 (S-ECC group) and 0.23 (non-S-ECC group).

CONCLUSION

These results show that occurrence of S-ECC is a complex interaction between socioeconomic, psychological and behavioural factors of parents. New and specific ways to provide preventive dental care for toddlers and infants of caries risk groups have to be developed.

CLINICAL RELEVANCE

Parents of newborn children have to receive information about timely start of tooth brushing and adequate use of nursing bottles.

Lattice energies for crystals of colloidal spheroids

Attractive interactions between adjacent spheroids and excluded volume effects favor their parallel alignment. Parallel spheroids can be arranged into a variety of densely packed two-dimensional and three-dimensional lattice configurations. All of these configurations turn out to have the same lattice energy. A similar degeneracy is also found for several classes of lattices with lower volume density. We discuss implications of this degeneracy for the stability of colloidal crystals consisting of spheroids.

Treating menopausal symptoms with a complex remedy or placebo: a randomized controlled trial

OBJECTIVE

To evaluate the efficacy and safety of a complex remedy compared with placebo to treat menopausal symptoms.

METHODS

A total of 102 peri- and postmenopausal women requiring treatment for menopausal symptoms were randomized to receive a complex anthroposophic remedy prepared in the homeopathic manner (Apis regina tota GL D4, Argentum metallicum D5, Ovaria bovis GL D4), 3 × 10 globuli daily (2 × 12 weeks) and placebo (12 weeks) in different orders of remedy (R) and placebo (P) (1: R/R/P, 2: P/R/R, 3: R/P/R). The primary endpoint was change in climacteric symptoms assessed by the Menopause Rating Scale II (MRS II) after 12 weeks. Secondary endpoints were changes of symptoms and safety throughout the study.

RESULTS

Reduction of symptoms after 12 weeks did not differ between remedy and placebo (total score MRS II: -1.4, 95% confidence interval (CI) -2.8 to 0 vs. -2.3, 95% CI -4.4 to -0.3, p = 0.441) and had no clinical relevance (defined as reduction in MRS II ≥ -3.5). Comparison of secondary outcomes at 12 weeks between remedy and placebo or between groups after the 2nd or 3rd period compared to previous periods did not differ. Treatment with remedy for 24 consecutive weeks did not reach clinical relevance either. However, total reduction of symptoms after three periods in Group 1 (R/R/P) (-5.0, 95% CI -7.5 to -2.5) and Group 2 (P/R/R) (-5.9, 95% CI -8.7 to -3.1) reached clinical relevance whereas almost no decrease of symptoms after three periods was seen in Group 3 (R/P/R) (-0.5, 95% CI -2.9 to 1.9).

CONCLUSIONS

Treatment with the complex remedy for 12 or 24 weeks did not result in clinically significant improvement of menopausal symptoms.

Interactions between spheroidal colloidal particles

Using Derjaguin's approximation, we have evaluated the interaction energy associated with van der Waals, electrostatic, depletion, and capillary forces between colloidal spheroids. If the interaction range between spheroids is distinctly smaller than the lengths of their principal axes, then simple pair potentials that depend on particle distance and orientation can be derived. Attractive interactions between adjacent spheroids favor their parallel alignment. Parallel spheroids can be arranged into a variety of densely packed configurations. All of these configurations turn out to have the same lattice energy. We discuss the implications of this degeneracy with respect to the stability of photonic crystals consisting of spheroids.

Applications of PZT and Related Thin Films in Piezoelectric Microsensors

Ferroelectric thin films have been deposited on polycrystalline silicon micromechanical structures to form both physical microsensors and microactuator devices. These devices which include acoustic pressure sensors, infrared detectors, micropositioners, and stepper motors are based on either the piezoelectric or pyroelectric properties of sol-gel Pb(ZrxTi1-x)O3 or PbTiO3 deposited on surface-machined microelectromechanical structures. Several materials, micromachining, process integration, and performance issues are introduced in the description of these devices.

Depletion force between anisometric colloidal particles

A simple mathematical model for the depletion force between two arbitrarily shaped large convex colloidal particles immersed in a suspension of small spherical particles is proposed. Using differential geometry, the interaction potential is expressed in terms of the mean and Gaussian curvature of the particle surfaces. The accuracy of theoretical results is tested by Monte Carlo simulations for parallel and nonparallel circular cylinders. The agreement between theoretical results and simulated data is very good if the density of the depletion agent is not too high.

Monte Carlo study of the self-assembly of achiral bolaform amphiphiles into helical nanofibers

It is shown by coarse-grained off-lattice Monte Carlo simulations that a geometrically induced frustration of the parallel arrangement of rigid achiral bolaform amphiphiles can cause chirality in self-assembled nanostructures. The amphiphilic molecules are represented as rigid linear chains of 8 equally sized hydrophobic spheres (tail) and a hydrophilic sphere (head) at each end. The hydrophilic and hydrophobic spheres differ in size. A very simple interaction scheme consisting of only hard-core repulsion between all spheres and square-well attraction between hydrophobic spheres is sufficient for self-assembly into helical fibers for molecules with head/tail diameter ratios ranging from 1.3 to 1.8.

Monte Carlo simulations of small vesicles under osmotic pressure

A simple model for amphiphilic molecules is sufficient to predict self-assembly into spherical vesicles. The model is also useful to study the influence of osmotic pressure on the shape of vesicles, which serve as carriers in biological cells. The stability of small vesicles subjected to relatively high osmotic pressures is demonstrated. Fluctuations of small vesicles under osmotic stress are found to be in semiquantitative agreement with a macroscopic description. Small deviations between simulated results for vesicle fluctuations and macroscopic elasticity theory could result from the relative large membrane thickness in comparison to the vesicle radius. The simulations demonstrate that an osmotic pressure exerted by solute molecules outside a spherical vesicle can cause a shape transition, in agreement with results based on the elasticity theory of membranes.

Monte Carlo simulation of surfactant adsorption on hydrophilic surfaces

Monte Carlo simulations have been carried out to study the adsorption behavior of small flexible amphiphilic molecules on solid surfaces from aqueous solutions. A simple coarse-grained solvent-free off-lattice model, with a square-well pair potential and hard core excluded volume effect, has been used. Adsorption isotherms for weakly and strongly hydrophilic homogeneous surfaces have been determined. The adsorbed layer displays a coexistence region with an upper critical point. Below the critical temperature a densely packed patch coexists with a two-dimensional gas-analogous phase. Above the critical temperature, a percolating network forms at higher surfactant concentrations. Depending on the ratio between the strength of the hydrophobic effect and the adsorption energy, a large variety of associates has been observed. Monolayers, bilayers, admicelles, small clusters, and percolating networks as typical associate structures have been found. In the four-region model, which is extended by the coexistence region, a characteristic adsorbed layer structure for each region can be detected. Intermediate structure types have been produced by variation of the adsorption energy.

Second malignancy risk associated with treatment of Hodgkin's lymphoma: meta-analysis of the randomised trials

BACKGROUND

Despite several investigations, second malignancy risks (SMR) following radiotherapy alone (RT), chemotherapy alone (CT) and combined chemoradiotherapy (CRT) for Hodgkin's lymphoma (HL) remain controversial.

PATIENTS AND METHODS

We sought individual patient data from randomised trials comparing RT versus CRT, CT versus CRT, RT versus CT or involved-field (IF) versus extended-field (EF) RT for untreated HL. Overall SMR (including effects of salvage treatment) were compared using Peto's method.

RESULTS

Data for between 53% and 69% of patients were obtained for the four comparisons. (i) RT versus CRT (15 trials, 3343 patients): SMR were lower with CRT than with RT as initial treatment (odds ratio (OR) = 0.78, 95% confidence interval (CI) = 0.62-0.98 and P = 0.03). (ii) CT versus CRT (16 trials, 2861 patients): SMR were marginally higher with CRT than with CT as initial treatment (OR = 1.38, CI 1.00-1.89 and P = 0.05). (iii) IF-RT versus EF-RT (19 trials, 3221 patients): no significant difference in SMR (P = 0.28) although more breast cancers occurred with EF-RT (P = 0.04 and OR = 3.25).

CONCLUSIONS

Administration of CT in addition to RT as initial therapy for HL decreases overall SMR by reducing relapse and need for salvage therapy. Administration of RT additional to CT marginally increases overall SMR in advanced stages. Breast cancer risk (but not SMR in general) was substantially higher after EF-RT. Caution is needed in applying these findings to current therapies.

Monte carlo simulations of self-assembled surfactant aggregates

Monte Carlo simulations provide some insight into the self-assembly of amphiphiles in aqueous environment. A rather simple solvent-free model, with only two adjustable parameters in the effective pair potential, allows one to describe the formation of micelles, stable curved membranes, and metastable vesicles. Characteristic features of the self-assembled aggregates, such as the distribution of the micelle size and the value of the curvature elastic constant for membranes, can be obtained from simulated data. The capability of the simple approach was demonstrated for a surfactant model with three spherical segments. The extension of the simulation to molecules with more segments and branched amphiphiles is straightforward.

Monte Carlo study of surfactant adsorption on heterogeneous solid surfaces

The equilibrium between free surfactant molecules in aqueous solution and adsorbed layers on structured solid surfaces is investigated by lattice Monte Carlo simulation. The solid surfaces are composed of hydrophilic and hydrophobic surface regions. The structures of the surfactant adsorbate above isolated surface domains and domains arranged in a checkerboard-like pattern are characterized. At the domain boundary, the adsorption layers display a different behavior for hydrophilic and hydrophobic surface domains. For the checkerboard-like surfaces, additional adsorption takes place at the boundaries between surface domains.

Solid tumors in patients treated for Hodgkin's disease: a report from the German Hodgkin Lymphoma Study Group

BACKGROUND

Long-term survivors of successfully treated Hodgkin's disease (HD) are at risk for late complications. Among these, secondary solid tumors are most serious because they are often fatal. The aim of this retrospective analysis was to assess the incidence, relative risk and risk factors of secondary solid tumors in HD patients registered in the database of the German Hodgkin Lymphoma Study Group (GHSG).

PATIENTS AND METHODS

From 1983 to 1998, the GHSG conducted three generations of clinical trials for early, intermediate and advanced stage HD (HD1-HD9) involving a total of 5367 patients. Data on incidence, risk factors and relative risk were updated in March 2003.

RESULTS

A total of 127 patients with secondary solid tumors were identified. Among these, lung cancer (23.6%), colorectal cancer (20.5%) and breast cancer (10.2%) were the most frequent. After a median follow-up of 72 months the cumulative risk of developing a solid tumor was 2%, with an overall relative risk (RR) of 2.4 (lung cancer, 3.8; colorectal cancer, 3.2; breast cancer, 1.9). For most patients (n=67; 52.8%) developing a secondary solid tumor, treatment modality consisted of chemotherapy combined with radiotherapy in extended field technique (RR = 3.3).

CONCLUSIONS

With a median follow-up of 72 months, there were 127 patients developing solid tumors out of a total of 5367 HD patients treated in the GHSG studies HD1-HD9. The cumulative risk of 2% is expected to increase over time due to the rather short median observation time and slow progression of solid malignancies.

Adhesion force of a wedge

The macroscopic theory of capillarity is usually applied to evaluate the adhesion forces produced by fluid bridges between solid particles. A refined mesoscopic description incorporates the disjoining pressure, which results from the long range forces between the fluid and the solid substrates. In the case of simple nonpolar fluids the influence of the disjoining pressure on adhesion is expected to be negligibly small. Water bridges, however, sometimes have very large disjoining pressures on various substrates. Then mesoscopic theory leads to pull-off forces which differ from the predictions of the macroscopic approach.

Congenital self-healing langerhans cell histiocytosis with atrophic recovery of the skin: clinical correlation of an immunologic phenomenon

The pathophysiology and pathogenesis of congenital self-healing Langerhans cell histiocytosis (CSHLCH) as well as that of the other types of Langerhans cell histiocytosis is not well understood. Some authors postulate deregulated immunologic mechanisms that result in overproduction of cytokines. We examined a neonate with disseminated papulonodular eruptions containing lymphoid aggregates of B lymphocytes in the chorial layer. The diagnosis of a CSHLCH was made and the follow-up showed a complete involution of the eruptions, leaving atrophic lesions in the sites corresponding to the initial findings. We discuss a possible imbalance of the immune response as a pathogenetic mechanism.

[Oral pemphigus vulgaris. Successful treatment with minocycline and nicotinamide]

Minocycline is another possible alternative therapy for pemphigus vulgaris. We successfully treated a Jewish patient with oral pemphigus vulgaris with with minocycline and nicotinamide. Minocycline may be a useful second-line drug for therapy- resistant cases of pemphigus vulgaris.

Factor VII deficiency and a copper metabolism disorder in a patient with Klippel-Trenaunay syndrome

We report on a patient with Klippel-Trenaunay (KT) syndrome, a factor VII deficiency and a copper metabolism disorder. The KT syndrome involved the left leg and, histologically, the liver. Dermatological examination, duplex ultrasonography and a skin and liver biopsy verified the KT syndrome. A long prothrombin time prompted clotting studies revealing a factor VII deficiency while the other factors were in the normal range. Further laboratory examinations showed a copper metabolism disorder similar to Wilson's disease with a low serum ceruloplasmin level, elevated copper concentration in the urine and increased copper deposition in the liver. Neither liver cirrhosis nor a Kayser-Fleischer corneal ring was present. Sequencing analysis of the Wilson's disease gene ATB7B showed no mutations. The occurrence of these three uncommon pathologies in a single patient has not been described to date, which may suggest a mutation in a hypothetical common regulatory gene leading to this unusual phenotype.

Plant growth using EMCS hardware on the ISS

Under separate contracts with ESA (FUMO and ERM Study) and as a link in the development of the European Modular Cultivation System's (EMCS) functionality and biocompatibility, plant studies have been performed at The Plant Biocentre in Trondheim, Norway. The main goal was to test whether the breadboards containing the major components planned for use in the EMCS would be optimal for space experiments with plant material. The test plans and the experimental set-up for the verification of biocompatibility and biological functionality included the use of a few model plant species including cress (Lepidium sativum L.) and Arabidopsis thaliana. The plants were tested at different developmental levels of morphological and physiological complexity (illumination, life support, humidity control, water supply, observation, short- and long-term plant growth experiments and contamination prevention). Results from the tests show that the EMCS concept is useful for long duration plant growth on the ISS.

[Henoch-Schoenlein syndrome in an 80-year-old patient]

HISTORY AND CLINICAL FINDINGS

An 80-year old female patient, hospitalised with pneumonia and myocardial infarction, suddenly developed fever, dyspnoea, malaise, arthralgia and crampy abdominal pain. On the following day, she developed a petechial rash and on the 6 (th) day, macroscopic haematuria. On physical examination, the patient presented with a temperature of 40 degrees C, tachypnoea, tachycardia, and on auscultation coarse crepitations at the left lower base. The abdomen was tender upon deep palpation but bowel sounds were normal. Initially the petechial rash was located at the trunk, later progressing towards the extremities.

INVESTIGATIONS

Chest X-ray and laboratory tests were consistent with left lower lobe pneumonia. The clinical picture was not consistent with any haematological causes, coagulopathy or any medication the patient was taking. Rheumatological blood tests (involving ANA, ANCA, rheumatoid factors) were basically negative. A skin biopsy revealed microvessel necrosis and IgA deposits, verifying Henoch-Schoenlein Purpura. An immune electrophoresis revealed a selective IgG-deficiency, which may explain the cause for the patient's recurrent pneumonias.

COURSE

The patient recovered well under antibiotic treatment and skin lesions healed without sequelae.

CONCLUSION

We present an unusual case of Henoch Schoenlein purpura associated with strictly petechial rash in an 80 year old female.

Experiments with small animals in BIOLAB and EMCS on the International Space Station

Two ESA facilities will be available for animal research and other biological experiments on the International Space Station: the European Modular Cultivation System (EMCS) in the US Lab "Destiny" and BIOLAB in the European "Columbus" Laboratory. Both facilities use standard Experiment Containers, mounted on two centrifuge rotors allowing either research in microgravity or acceleration studies with variable g-levels from 0.001 to 2.0 x g. Standard interface plates provide each container with power and data lines, gas supply (controlled CO2, O2 concentration and relative humidity), and--for EMCS only--connectors to fresh and waste water reservoirs. The experiment hardware inside the containers will be developed by the user, but ESA conducted a feasibility study for several kinds of Experiment Support Equipment with potential use for research on small animals: design concepts for experiments with insects, with aquatic organisms like rotifers and nematodes, and with small aquatic animals (sea urchin larvae, tadpoles, fish youngsters) are described in detail in this presentation. Also ESA's initial steps to support experiments with rodents on the Space Station are presented.

Short-term inverse-agonist treatment induces reciprocal changes in delta-opioid agonist and inverse-agonist binding capacity

This study assessed the effects of short-term treatment (30-min) with inverse agonists on receptor protein levels and on the ability of agonists, inverse agonists, and neutral antagonists to bind to the human delta-opioid receptor (h delta OR). Incubation of human embryonic kidney 293s cells stably expressing h delta OR with the inverse agonist ICI174864 (1 microM) induced reciprocal changes in agonist and inverse-agonist binding. The total number of binding sites recognized by the agonists [(3)H]bremazocine and [(3)H][D-Pen(2),D-Pen(5)]-enkephalin was reduced by 33 and 57%, respectively, whereas binding capacity for the radiolabeled inverse-agonist [(3)H]Tyr-TicY[CH(2)NH]Cha-Phe-OH increased by 44%. In contrast, total receptor protein and sites labeled by neutral antagonists [(3)H]naltrindole and [(3)H]Tyr-D-Tic-Phe-Phe-OH remained unchanged. Pertussis toxin (PTX) and 5-guanylylimidodiphosphate (GppNHp) mimicked the outcome of ICI174864 pretreatment in promoting the loss of agonist binding sites. The lack of an additive effect on [(3)H]bremazocine binding when these three agents were combined indicates that inverse agonists may, in part, share the mechanism by which GppNHp and PTX reduce agonist binding capacity. Spontaneous recovery of maximal agonist binding capacity after inverse-agonist treatment was slow, suggesting a decrease in the isomerization rate between agonist- and inverse agonist-preferring conformations. Overall, the data presented are consistent with the idea that h delta ORs exist in multiple states capable of discriminating among ligands of different levels of efficacy and show that, after short-term treatment with an inverse agonist, the receptor ability to adopt conformations preferentially induced by agonist ligands is reduced.

Indirect interaction of colloidal particles adsorbed on smectic films

Colloidal particles like peptides and proteins adsorbed on a stack of lipid bilayers cause elastic deformations which disturb the smectic order. Two adsorbed particles attract each other due to the superposition of their deformation fields. The effective pair potential attributed to this substrate-mediated force decays exponentially with the particle distance. The range of this potential coincides with the decay length of elastic deformations, and is found to be proportional to the square root of the stack thickness. If the stack is sufficiently thick, the substrate-mediated interaction is estimated to be strong enough to overcome the entropic barrier and enforce aggregation or even crystallization of the adsorbate.