Atomic force microscopy for the characterisation of pinning effects of seawater micro-droplets in n-decane on a calcite surface

HYPOTHESIS

Roughness is an important parameter in applications where wetting needs to be characterized. Micro-computed tomography is commonly used to characterize wetting in porous media but the main limitation of this approach is the incapacity to identify nanoscale roughness. Atomic force microscopy, AFM, however, has been used to characterize the topography of surfaces down to the molecular scale. Here we investigate the potential of using AFM to characterize wetting behavior at the nanoscale.

EXPERIMENTS

Droplets of water on cleaved calcite under decane were imaged using quantitative imaging QI atomic force microscopy where a force-distance curve is obtained at every pixel.

FINDINGS

When the AFM tip passed through the water droplet surface, an attraction was observed due to capillary effects, such that the thickness of the water film was estimated and hence the profile of the droplet obtained. This enables parameters such as the contact angle and contact angle distribution to be obtained at a nanometer scale. The contact angles around the 3-phase contact line are found to be quasi-symmetrically distributed between 10-30°. A correlation between the height profile of the surface and contact angle distribution demonstrates a quasi-proportional relationship between roughness on the calcite surface and contact angle.

AB0161 THE IMPACT OF BIOLOGICAL AGENTS ON CARDIOVASCULAR RISK FACTORS OF PATIENTS DIAGNOSED WITH RHEUMATOID ARTHRITIS

Background:

The risk of cardiovascular disease in patients with rheumatoid arthritis (RA) is 1.5-2 fold higher than in people of the same age and sex of the general population.1,2,3 This marked risk is attributed to the systemic chronic inflammation which is characteristic of the disease.

Objectives:

The aim of this study is to evaluate cardiovascular risk factors and early atherosclerosis in rheumatoid arthritis patients, treated with biological agents.

Methods:

This is a prospective, observational study. Thirty-five patients treated with synthetic DMARDs with no previous history of a cardiovascular event included. We compared total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), triglycerides (TGs), Apolipoprotein A1 (ApoA1), Apolipoprotein B (ApoB) and Lipoprotein A (LpA), the titer of autoantibodies against oxidised LDL(anti-oxLDL), systolic blood pressure, inflammatory markes as C-reactive protein (CRP) and erythrocytes sedimentation rate (ESR) between baseline and after 6 months of biological agents initiation. An ultrasonographic measurement of intima-media thickness (IMT) of carotids was also performed by an experienced sonographer at baseline and after one-year follow-up.

Results:

As regards the demographic characteristics of patients, the mean (SD) age was 54(14) years, disease duration 4,3(1.4) years, 22.9% were smokers and 68,6% were women. Anti-TNF was administered in 71,4% of patients while the rest non anti-TNF was given as treatment. Six months after treatment initiation, patients presented with a significant increase in mean (SD) HDL[69(19)vs58(15)] and ApoA1[177(34)vs162(31)] levels (p value <0,001) with a simultaneous significant reduction of mean (SD) systolic blood pressure [128(12)vs136(14)] and the titer of anti-oxLDL[0,132(0,042)vs0,190(0,056)]. ΙΜΤ was also reduced after one-year reassessment [0,8(0,3) mm vs 0,9(0,3)mm, (p value <0,001 for all comparisons)].

Conclusion:

Biological agents administration was accompanied by an improved lipid profile in a six-month period and a significant reduction of IMT, confirming that RA patients are prone to early atherosclerosis and probably biological agents initiation correlates strongly with cardiovascular risk reduction.

References:

[1]Avina-Zubieta JA, Choi HK, Sadatsafavi M, Etminan M, Esdaile JM, Lacaille D. Risk of cardiovascular mortality in patients with rheumatoid arthritis: a meta-analysis of observational studies. Arthritis and rheumatism. 2008 Dec 15;59(12):1690–1697.

[2]Avina-Zubieta JA, Thomas J, Sadatsafavi M, Lehman AJ, Lacaille D. Risk of incident cardiovascular events in patients with rheumatoid arthritis: a meta-analysis of observational studies. Annals of the rheumatic diseases. 2012 Sep;71(9):1524–1529.

[3]Solomon DH, Karlson EW, Rimm EB, Cannuscio CC, Mandl LA, Manson JE, et al. Cardiovascular morbidity and mortality in women diagnosed with rheumatoid arthritis. Circulation. 2003 Mar 11;107(9):1303–1307.

Disclosure of Interests:

None declared

Outcome of refractory to conventional and/or biologic treatment adult Still's disease following canakinumab treatment: Countrywide data in 50 patients

OBJECTIVE

To assess the efficacy and safety of the IL-1b inhibitor canakinumab in all adults with refractory Still's disease identified from the National Organization For Medicines for off-label drug use.

METHODS

In a retrospective longitudinal multicenter cohort of 50 patients (median age 39 years) with active Still's disease despite treatment with corticosteroids (n = 11), conventional and synthetic (n = 34) and/or biologic disease modifying anti-rheumatic drugs (n = 30), we assessed the efficacy of canakinumab 150-300 mg administered every 4 (n = 47) or 8 weeks (n = 3) as combination therapy or monotherapy (n = 7) during a median follow-up of 27 (3-84) months.

RESULTS

Α complete response was initially observed in 78% of patients within 3 months (median), irrespective of age at disease onset. A partial response was evident in 20%. One patient had resistant disease. Treatment de-escalation was attempted in 15 of 39 complete responders and a complete drug discontinuation in 21 patients for 8 months (median). Eleven patients (22%) relapsed during treatment, one during de-escalation process, and 11 after treatment discontinuation. Overall, 9 of 11 relapses were successfully treated with canakinumab treatment intensification or re-introduction. At last visit, 18% of patients were off treatment due to remission and 26% due to disease activity. Canakinumab had a significant corticosteroid sparing effect allowing weaning in 21 of 41 cases. Infections (20%, severe 4%) and leucopenia (6%) led to treatment cessation in one patient.

CONCLUSION

High rates of sustained remission were observed in this, largest so far, real-life cohort of adult patients with refractory Still's disease treated with canakinumab.

FRI0493 THE INTERLEUKIN-1B INHIBITOR CANAKINUMAB FOR REFRACTORY STILL’S DISEASE: LONG-TERM EXPERIENCE IN 50 CONSECUTIVE PATIENTS

Background:

Interleukin-1 (IL-1) is a major mediator of the inflammatory cascade in Still’s disease and an established therapeutic target.

Objectives:

To assess the efficacy and safety of the IL-1b inhibitor canakinumab in adolescent and adult patients with refractory Still’s disease.

Methods:

We conducted a retrospective longitudinal outcome study of 50 consecutive patients aged 39 years (median, range 14-72), fulfilling the Yamaguchi disease classification criteria, with active disease despite treatment with corticosteroids (CS) (n=11) and/or methotrexate (n=9) and/or biologics (n=30) [tumor necrosis factor inhibitors (n=13), IL-6 blockade (n=7), abatacept (n=2), anakinra (n=24); ≥1 biologics (n=13)]. Canakinumab 150-300 mg was administered sc, starting every 4 (n=48) or 8 weeks (n=2), for a median of 24 months (range 3-84). Concomitant treatment included CS (n=41), methotrexate (n=12) and leflunomide (n=3).

Results:

Complete remission was initially achieved in 78% of patients within a median time of 3 months, irrespective of age at disease onset. Partial clinical and laboratory response was evident in 20%. Canakinumab was discontinued in one patient with resistant disease (primary failure) and in 6 out of 10 initial responders, who relapsed during treatment (secondary failure). Of 39 patients in complete remission, increase in drug administration interval and/or drug dose reduction was attempted in 7, of which only 1 relapsed, whereas drug discontinuation was attempted in 19 patients for a median time of 8 months (range 3-68), of which 8 relapsed. Overall, in half of all disease flares, canakinumab re-introduction or intensification was successful. Canakinumab had a significant CS sparing effect permitting weaning in 21 of 41 cases. Infections (20%, severe 4%) and leucopenia (6%) led to treatment cessation in one patient.

Conclusion:

In this largest so far real-life patient cohort with refractory Still’s disease, high rates of sustained remission were induced by canakinumab both in adolescent and adult patients.

Disclosure of Interests:

Katerina Laskari: None declared, Panagiotis Athanassiou Grant/research support from: MSD, Genesis pharma, Janssen, Consultant of: Roche, Genesis pharma, Janssen, Speakers bureau: MSD, Janssen, Roche, Genesis pharma, Athanasios Georgiadis: None declared, Charalampos Gerodimos: None declared, Georgia Gkoni: None declared, Dimitrios Daoussis: None declared, Theodoros Dimitroulas: None declared, Despoina Dimopoulou: None declared, Chrysoula Iliou: None declared, Ioannis Kallitsakis Grant/research support from: MSD, Speakers bureau: Genesis pharma, Bristol-Myers Squibb, Dimitrios Karamitsos: None declared, Christina Katsiari: None declared, Stamatis-Nick Liossis: None declared, Clio Mavragani: None declared, CHARALAMPOS PAPAGORAS: None declared, Dimitrios Pikazis: None declared, Ioannis Raftakis: None declared, Theodosios Sarikoudis: None declared, Loukas Settas: None declared, Prodromos Sidiropoulos: None declared, Despoina Soukera: None declared, Evangelos Theodorou: None declared, Panagiota Tsatsani: None declared, Eleni Tsiakou: None declared, Dimitrios Vassilopoulos: None declared, PANAYIOTIS VLACHOYIANNOPOULOS: None declared, Georgios Vosvotekas: None declared, Paraskevi V. Voulgari: None declared, Marina Zakalka: None declared, Maria Tektonidou Grant/research support from: AbbVie, MSD, Novartis and Pfizer, Consultant of: AbbVie, MSD, Novartis and Pfizer, Petros Sfikakis Grant/research support from: Grant/research support from Abvie, Novartis, MSD, Actelion, Amgen, Pfizer, Janssen Pharmaceutical, UCB

Model-free classification of X-ray scattering signals applied to image segmentation

This article describes a modeling framework to relate the molecular orientation of nanostructures to polarized resonant soft X-ray scattering measurements using the Born approximation and a full tensor treatment.

In most cases, the analysis of small-angle and wide-angle X-ray scattering (SAXS and WAXS, respectively) requires a theoretical model to describe the sample’s scattering, complicating the interpretation of the scattering resulting from complex heterogeneous samples. This is the reason why, in general, the analysis of a large number of scattering patterns, such as are generated by time-resolved and scanning methods, remains challenging. Here, a model-free classification method to separate SAXS/WAXS signals on the basis of their inflection points is introduced and demonstrated. This article focuses on the segmentation of scanning SAXS/WAXS maps for which each pixel corresponds to an azimuthally integrated scattering curve. In such a way, the sample composition distribution can be segmented through signal classification without applying a model or previous sample knowledge. Dimensionality reduction and clustering algorithms are employed to classify SAXS/WAXS signals according to their similarity. The number of clusters, i.e. the main sample regions detected by SAXS/WAXS signal similarity, is automatically estimated. From each cluster, a main representative SAXS/WAXS signal is extracted to uncover the spatial distribution of the mixtures of phases that form the sample. As examples of applications, a mudrock sample and two breast tissue lesions are segmented.

Correction: Development of an optimized AAV2/5 gene therapy vector for Leber congenital amaurosis owing to defects in RPE65

The authors originally published this article under the incorrect license type; this has now been corrected and is published under the CC-BY license.

Development of an optimized AAV2/5 gene therapy vector for Leber congenital amaurosis owing to defects in RPE65

Leber congenital amaurosis is a group of inherited retinal dystrophies that cause severe sight impairment in childhood; RPE65-deficiency causes impaired rod photoreceptor function from birth and progressive impairment of cone photoreceptor function associated with retinal degeneration. In animal models of RPE65 deficiency, subretinal injection of recombinant adeno-associated virus (AAV) 2/2 vectors carrying RPE65 cDNA improves rod photoreceptor function, and intervention at an early stage of disease provides sustained benefit by protecting cone photoreceptors against retinal degeneration. In affected humans, administration of these vectors has resulted to date in relatively modest improvements in photoreceptor function, even when retinal degeneration is comparatively mild, and the duration of benefit is limited by progressive retinal degeneration. We conclude that the demand for RPE65 in humans is not fully met by current vectors, and predict that a more powerful vector will provide more durable benefit. With this aim we have modified the original AAV2/2 vector to generate AAV2/5-OPTIRPE65. The new configuration consists of an AAV vector serotype 5 carrying an optimized hRPE65 promoter and a codon-optimized hRPE65 gene. In mice, AAV2/5-OPTIRPE65 is at least 300-fold more potent than our original AAV2/2 vector.

The effect of the reductions in social interactions due to the economic crisis on the subjective well-being of non-insurance health care seekers in Greece

Background

Social interactions have an important effect on the subjective well-being of individuals. However, in periods of financial crisis these interactions are reduced, affecting thus the mental health of the individuals as well.

Aim

To investigate the effect of the reduction in social interactions, as a result of the economic crisis, on the subjective well-being of non-insurance health care seekers in Greece.

Method

Two hundred and sixty-six individuals participated in this study, 90 (35.6%) males and 163 (64.4%) females, with a mean age of 47. Analysis of data was conducted with Anova, using the SPSS software.

Results

The findings showed that reductions in social interactions, caused by the financial crisis, led to significant reductions in the subjective well-being of individuals as well (F(1.259) = 13.276, P < 0.001 for social activities and F(1,258) = 14.531, P < 0.001 for peer socialization). More specifically, individuals whose social interactions were greatly affected by the financial crisis reported significantly lower subjective well-being than individuals who reported a medium effect (M = −2.952, SD = .764, P < 0.001). Furthermore, individuals who reported that the economic crisis had a great effect on their peer socialization reported significantly lower subjective well-being compared to both those who reported a medium (M = −1.868, SD = .658, P < 0.015) or low (M = −2.77, SD = .809, P < 0.001) effect of the crisis.

Conclusion

The results of this research showed that the financial crisis reduced the well-being of affected individuals through reductions in their social interactions. Further research is needed to investigate appropriate interventions to reduce the negative impact that the financial crisis has on the well-being of affected individuals.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Capillary saturation and desaturation

Capillary desaturation experiments produce disconnected (trapped) ganglia of mesoscopic sizes intermediate between pore size and system size. Experimental evidence for interactions between these mesoscale clusters during desaturation is analyzed and discussed within the established microscopic and macroscopic laws of Newton, Young-Laplace, and Darcy. A theoretical expression for capillary number correlations is introduced that seems to have remained unnoticed. It expresses capillary desaturation curves in terms of stationary capillary pressures and relative permeabilities. The theoretical expression shows that the plateau saturation in capillary desaturation curves may in general differ from the residual nonwetting saturation defined through the saturation limit of the main hysteresis loop. Hysteresis effects as well as the difference between wetting and nonwetting fluids are introduced into the analysis of capillary desaturation experiments. The article examines experiments with different desaturation protocols and discusses the existence of a mesoscopic length scale intermediate between pore scale and sample scale. The theoretical expression is derived entirely within the existing traditional theory of two-phase flow in porous media and compared to a recent experiment.

Pore-scale micro-computed-tomography imaging: nonwetting-phase cluster-size distribution during drainage and imbibition

We investigated the cluster-size distribution of the residual nonwetting phase in a sintered glass-bead porous medium at two-phase flow conditions, by means of micro-computed-tomography (μCT) imaging with pore-scale resolution. Cluster-size distribution functions and cluster volumes were obtained by image analysis for a range of injected pore volumes under both imbibition and drainage conditions; the field of view was larger than the porosity-based representative elementary volume (REV). We did not attempt to make a definition for a two-phase REV but used the nonwetting-phase cluster-size distribution as an indicator. Most of the nonwetting-phase total volume was found to be contained in clusters that were one to two orders of magnitude larger than the porosity-based REV. The largest observed clusters in fact ranged in volume from 65% to 99% of the entire nonwetting phase in the field of view. As a consequence, the largest clusters observed were statistically not represented and were found to be smaller than the estimated maximum cluster length. The results indicate that the two-phase REV is larger than the field of view attainable by μCT scanning, at a resolution which allows for the accurate determination of cluster connectivity.

Ultrasound diagnosis of recurring Jeune's syndrome: a case report

Jeune's Syndrome or asphyxiating thoracic dystrophy (ATD) is a rare autosomal recessive skeletal dysplasia syndrome characterized by a small and narrow chest, short extremities, and often polydactyly associated with multiple organ manifestations. The severity of complications ranges from mild to lethal. This is a report of two cases of ATD diagnosed in successive pregnancies of a nonconsanguineous couple. The contribution of sonography in prenatal diagnosis of the syndrome is highlighted.

Vanishing twins in diamniotic dichorionic in vitro fertilization gestation in mid-second trimester

The authors report a diamniotic dichorionic twin pregnancy after in vitro fertilization (IVF) in mid-second trimester. The dead fetuses were delivered by cesarean section at the 20th week of gestation. The authors discuss management aspects and review of the literature.

Intrauterine growth restriction may not suppress bone formation at term, as indicated by circulating concentrations of undercarboxylated osteocalcin and Dickkopf-1

The objective was to investigate circulating concentrations of bone formation markers (undercarboxylated osteocalcin [Glu-OC], an established marker of bone formation during fetal and early postnatal life], and Dickkopf-1 [DKK-1], a natural inhibitor of osteoblastogenesis during fetal development]) in intrauterine-growth-restricted (IUGR; associated with impaired fetal skeletal development) and appropriate-for-gestational-age (AGA) pregnancies. Circulating concentrations of Glu-OC and DKK-1 were determined by enzyme immunoassay in 40 mothers and their 20 asymmetric IUGR and 20 AGA singleton full-term fetuses and neonates on postnatal day 1 (N1) and 4 (N4). Parametric tests were applied in the statistical analysis. No significant differences in Glu-OC concentrations were observed between IUGR and AGA groups, whereas fetal DKK-1 concentrations were lower in the IUGR group (P = .028). In both groups, maternal Glu-OC and DKK-1 concentrations were lower than fetal, N1, and N4 concentrations (P ≤ .012 in all cases), whereas fetal Glu-OC concentrations were higher than N1 and N4 ones (P ≤ .037 in all cases). In addition, N1 Glu-OC concentrations were higher than N4 concentrations (P = .047). Finally, maternal Glu-OC and DKK-1 concentrations positively correlated with fetal, N1, and N4 ones (r ≥ 0.404, P ≤ .01 in all cases). Fetal/neonatal bone formation may not be impaired in full-term asymmetric IUGR infants, as indicated by the similar Glu-OC concentrations in both groups. Fetal DDK-1 concentrations are lower in the IUGR group, representing probably a compensatory mechanism, favoring the formation of mineralized bone. Fetal/neonatal bone turnover is markedly enhanced compared with maternal one and seems to be associated with the latter in both late pregnancy and early postpartum.

The challenging trisomy 16: a case report

BACKGROUND

Trisomy 16 is a very frequent autosomal anomaly accounting for about 2% of first trimester abortions. In most pregnancies the chromosomal genome found in the fetus is also present in the placenta. Confined placental mosaicism is frequently detected in the placental region along with a structurally normal fetus.

CASE

We present the case of a 39-year-old primigravida with confined placental mosaicism diagnosed with chorionic villus sampling. Amniocentesis showed a normal karyotype (46, XX). Detailed scanning revealed no structural fetal anomalies, but severe oligohydramnios.

CONCLUSION

Diagnosis of trisomy 16 does not necessarily mean that the newborn has anatomical abnormalities.

AAV-mediated knockdown of peripherin-2 in vivo using miRNA-based hairpins

Gene therapy for inherited retinal degeneration in which expression of a mutant allele has a gain-of-function effect on photoreceptor cells is likely to depend on efficient silencing of the mutated allele. Peripherin-2 (Prph2, also known as peripherin/RDS) is an abundantly expressed photoreceptor-specific gene. In humans, gain-of-function mutations in PRPH2 result in both autosomal dominant retinitis pigmentosa and dominant maculopathies. Gene-silencing strategies for these conditions include RNA interference by short hairpin RNAs (shRNAs). Recent evidence suggests that microRNA (miRNA)-based hairpins may offer a safer and more effective alternative. In this study, we used for the first time a virally transferred miRNA-based hairpin to silence Prph2 in the murine retina. The results show that an miRNA-based shRNA can efficiently and specifically silence Prph2 in vivo as early as 3 weeks after AAV2/8-mediated subretinal delivery, leading to a nearly 50% reduction of photoreceptor cells after 5 weeks. We conclude that miRNA-based hairpins can achieve rapid and robust gene silencing after efficient vector-mediated delivery to the retina. The rationale of using an miRNA-based template to improve the silencing efficiency of a hairpin may prove valuable for allele-specific silencing in which the choice for an RNAi target is limited and offers an alternative therapeutic strategy for the treatment of dominant retinopathies.

Signal Transduction by IL-2 and its Receptors as Target in Treatment of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic and destructive arthropathy with systemic features, the etiopathogenesis of which remains unclear. It is characterized by relapsing and remitting inflammation and hyperplasia of synovial cells. Proinflammatory cytokines, such as interleukin-2 (IL-2), play an important role in maintaining cartilage damage and severe destruction of the joints due to an uncontrolled activation of cellular immunity. An imbalance between proinflammatory and anti-inflammatory mediators is likely to contribute to the chronicity of the disease. Therefore, insight into the activation state of T-cells in different stages of the disease may be important to understand pathogenetic mechanisms underlying RA and could be a lead for the design of future therapeutic strategies. Because of the central role of the IL-2/IL-2 receptor (IL-2R) system in mediation of the immune system, monitoring and manipulation of this system has important diagnostic and therapeutic implications. New approaches in RA therapy with anticytokine agents, which block cytokines and their receptors, are now used as antirheumatic drugs in clinical practice.

Stable rAAV-mediated transduction of rod and cone photoreceptors in the canine retina

Recombinant adeno-associated virus (rAAV) vectors are attractive candidates for the treatment of inherited and acquired retinal disease. Although rAAV vectors are well characterized in rodent models, a prerequisite to their clinical application in human patients is the thorough evaluation of their efficacy and safety in intermediate animal models. In this study, we describe rAAV-2-mediated expression of GFP reporter gene in retinal cells following local vector delivery in dogs. Subretinal delivery of rAAV.CMV.GFP was performed unilaterally in eight normal dogs from 6 weeks of age. The area of retinal transduction was maximized by the optimization of surgical techniques for subretinal vector delivery by pars-plana vitrectomy and the use of fine-gauge subretinal cannulae to create multiple retinotomies. rAAV-2 vectors mediated efficient stable reporter gene expression in photoreceptors and retinal pigment epithelial cells. We found efficient transduction of cone photoreceptors in addition to rods in both the canine retina and after subretinal vector delivery in another intermediate animal model, the feline retina. GFP expression in dogs was confined to the area of the retinal bleb and was sustained in cells at this site for at least 18 months. Electroretinography demonstrated a modest reduction in global rod-mediated retinal function following subretinal delivery of rAAV.CMV.GFP. Three of the eight animals developed delayed-onset intraocular inflammation, in two cases associated with a serum antibody response to GFP protein. We conclude that rAAV-2 vectors mediate efficient sustained transgene expression in rod and cone photoreceptors following subretinal delivery in this intermediate animal model. The possibility of adverse effects including intraocular immune responses and reduced retinal function requires further investigation prior to clinical applications in patients.

Clinical course and outcome of early rheumatoid arthritis

We studied whether patients with seropositivity in early rheumatoid arthritis (RA) comprise a different clinical group than those with seronegativity. Four hundred seventeen patients with early RA according to the American College of Rheumatology criteria (disease duration less than 1 year) were retrospectively studied by analysis of demographic, clinical, laboratory, radiological, and therapeutic disease characteristics from the time of diagnosis until the end of the study period (1981 1999) using a data base. There were 248 seropositive patients and 169 seronegative patients with RA. No statistically significant differences were seen between the two groups before commencement of the study period in relation to age of disease onset, male:female ratio, and disease duration. However, seropositive patients showed longer medical follow-up. In addition, at disease onset, seropositive RA patients presented more frequently with symmetrical polyarthritis and small joint involvement than seronegative patients. The seropositive group also had more tender and swollen joints, weaker grip strength, and higher erythrocyte sedimentation and C-reactive protein rates during the follow-up period. In contrast, the seronegative group had less severe radiological findings and greater functional ability at the end of the study. In Greek patients with early RA, rheumatoid factor seems to be a predictor of more severe disease activity.

Cerebral hemodynamics during induced tachycardia in routine electrophysiologic studies: a transcranial Doppler study

Supraventricular and ventricular tachyarrhythmia are established causes of syncope. We investigated the mean blood flow velocities (Vmean) of the middle cerebral arteries (MCA) during routine cardiac electrophysiologic studies in patients with supraventricular and ventricular tachyarrhythmias in order to evaluate the changes in cerebral hemodynamics associated with pre-syncopal and syncopal states. Thirty-two patients with a history of supraventricular (n = 14) or ventricular (n = 18) tachyarrhythmias were investigated in the nonsedated, post-absorptive state in supine position. Vmean was assessed in both MCAs by means of transcranial Doppler under resting conditions, during atrial and ventricular pacing at constant rates (n = 28) and during induction of tachyarrhythmia (n = 4). Mean arterial blood pressure (MABP) and heart rate were also recorded. Seven patients suffered pre-syncope at a heart rate of 187 +/- 45 bpm (mean +/- SD) with an average drop of 44% in the Vmean MCA, and statistically insignificant changes in MABP. Five patients suffered syncope during tachyarrhythmia (mean heart rate 283 +/- 42 bpm) with a reduction of 69% in the Vmean MCA. MABP could be assessed in two of those patients and showed a drop of 15 and 43 mmHg, respectively. During tachyarrhythmia pre-syncope and syncope are associated with an average reduction in Vmean MCA by 44% and 69%, respectively. The decrease in MCA blood flow velocity is a more important predictive factor for the development of pre-syncope and syncope than the MABP.

Use of the excimer laser in stapes surgery and ossiculoplasty of middle ear ossicles: preliminary report of an experimental approach

Surgery of the stapes may cause a number of complications, including hearing deficits and balance disorders. This has made it necessary to look for improved techniques. Small-fenestra stapedotomy has recently been popularized. Lasers have been advocated for use in fenestrating the stapes footplate. On the other hand, sculpting the middle ear ossicles during tympanoplasty is often necessary for the reconstruction of the ossicular chain and the improvement of sound conduction. Using an excimer laser with a wavelength of 193 nm, fenestrations of the footplate and ossicular sculpting were performed on ossicles obtained during ear surgery and from human cadaver temporal bones. The results indicate that the excimer laser can be used effectively and accurately on an experimental basis and that further research is needed before this method can be used for clinical purposes.

Laser in situ keratomileusis

A new laser refractive procedure is being developed in a rabbit model. With a modified microkeratome, central corneal flaps were created. An ArF excimer laser was used to produce 3-mm-diameter circular ablations on the central part of the exposed stromal bed. One group of animals was sacrificed immediately postoperatively, and both the dissected and ablated areas were studied using scanning electron microscopy. A second group of animals was sacrificed 4 weeks postoperatively. In this group, the subsequent healing of the corneas was studied using light microscopy. At 3 days, the wounded stromal areas showed some degree of haze. Haze was progressively reduced over 1 month, but it could be still discerned biomicroscopically. A hemicircular opacification corresponding to the flap edges was also apparent on slit-lamp examination. Microscopic observation showed that the epithelium was normal, except at the flap margins, where it was thickened. An increased number of keratocytes was observed in the interface between the flap stroma and the ablated area. The procedure might induce stable corneal changes because of the preservation of the anterior layers of the cornea.

Comparative study of natural and synthetic retinoids as inhibitors of arachidonic acid release and metabolism in rat peritoneal macrophages

The effect of several natural and synthetic retinoids on the release and metabolism of arachidonic acid (20:4) in rat peritoneal macrophages (M phi), stimulated in vitro by either Ca2+ ionophore A23187 (A23187), opsonized zymosan (OZ) or 12-O-tetradecanoylphorbol-13-acetate (TPA), was investigated. With the exception of Ro 10-1670, the retinoids containing a free carboxylic acid group [i.e., all-trans-retinoic acid (all-trans-RA), 13-cis-RA, Ro 13-7652, Ro 12-7310 and Ro 13-7410] inhibited 20:4 metabolite formation in A23187- and OZ-stimulated Mø at 1-33 microM. However, only all-trans-RA, Ro 12-7310 and Ro 13-7410 inhibited the formation of 20:4 metabolites in TPA-stimulated Mø. These data suggest that part of the therapeutic effect of retinoids in inflammatory, hyperproliferative dermatologic conditions might be attributed to reduced 20:4 metabolite production.

A method for the bioassay of intestinal secretory activity in the conscious rat: studies with arachidonic acid and prostaglandin E2

A method to study the kinetics of intestinal absorption and secretion in the unanesthetized rat is described. This procedure consists of the perfusion of the small intestine with isotonic NaCl-KCl-[36Cl]NaCl and polyethylene glycol-6000 as a nonabsorbable marker. Secretagogues [arachidonic acid (AA) or PGE2] were administered by continuous infusion via the superior mesenteric artery. Samples of perfusate, taken every 15 min, were analyzed for Na, Cl, 36Cl, K, and PEG-6000 to calculate solute and volume movement. In control rats, net absorption of water and electrolytes increased steadily throughout the 2-hr duration of the perfusion. Water, Na, and Cl moved across the intestine in parallel proportions. Net absorption of K was lower than that of the other electrolytes. AA, at the intraarterial dose of 1 mg/kg/hr did not produce a significant effect; at 4 mg/kg/hr it impaired net absorption, and at 8 mg/kg/hr it gradually enhanced net secretion of both water and electrolytes, especially K. Secretion was also demonstrated with the intraarterial infusion of PGE2 (312 microgram/kg). It is concluded that this new rat model is suitable for the bioassay of intestinal secretory stimulants and can be used for the search of intestinal antisecretory drugs.

Increased glucagon secretion in protein-fed rats: lack of relationship to plasma amino acids

This investigation was designed to test the hypothesis that protein feeding stimulated glucagon secretion because amino acids liberated during protein digestion function as glucagon secretagogues. Rats were fed high-protein (HP) or control diets for 9--10 days and blood taken from the aorta or portal vein (PV) at 0800, 1300, 1700, 1900, 2100, and 2300 for determination of amino acids, glucose, insulin, and glucagon. Glucose, insulin, and glucagon of control rats showed little change. In HP rats, PV glucose rose during fasting (0800-1700) and declined during feeding (1700-0800), changes that reflected alterations of glucagon and insulin secretion. PV glucagon in HP rats that was elevated 2--4 times rose during fasting, whereas PV and arterial amino acids declined. HP feeding caused enhanced glucagon release that was associated with increased amino acids in PV and arterial plasma, especially the branched-chain group. Although these findings suggest that protein feeding promotes glucagon release because branched-chain amino acids are elevated, these amino acids are known to have little effect on alpha cell function. Thus, we conclude that protein feeding influences glucagon secretion through some mechanism other than increased blood amino acid levels.

[beta2-Microglobulin in ankylosing spondylitis and in Reiter's syndrome (author's transl)]

In patients with ankylosing spondylitis (AS) the plasma level of beta2-microglobulin (beta2m) is signficantly higher (1.95 +/- 0.48 mg/l) than in osteoarthritis (1.48 +/- 0.47 mg/l). In Reiter's syndrome the level of beta2m is also higher than in controls, but the paucity of results do not allow definite conclusions. The plasma level of beta2m in AS and in Reiter's syndrome is not related to the presence of HLA B 27 antigen, neither to other biological parameters as sedimentaton rate, blood cell counts, electrophoresis of plasma proteins. In rheumatoid arthritis the plasma level of beta2m is 2,67 +/- 0.84 mg/l, significantly higher than in osteoarthritis or in AS even without any association with Sjögren's syndrome. In synovial fluid, the beta2m level is closely related to the degree of inflammation, suggesting a local production of this substance.