Transdermal iontophoretic delivery of apomorphine in patients improved by surfactant formulation pretreatment.

The objective of the present study is to evaluate the efficacy and the safety of transdermal iontophoretic delivery of R-apomorphine, a potent dopamine agonist, in combination with surfactant pretreatment in patients with advanced Parkinson's disease. Iontophoresis patches were applied in 16 patients for 3.5 h, with 0.5 h of passive delivery followed by 3 h of current application at a current density of 250 microA/cm2. Eight of these patients were treated with a surfactant formulation prior to iontophoresis. The pharmacokinetics, pharmacodynamic effects, systemic and local side effects of R-apomorphine were assessed. The plasma concentration vs. time profiles upon iontophoresis of R-apomorphine were described successfully by a novel pharmacokinetic model. The model suggests that only 1.9% of the dose that has been released from the patch accumulated in the skin. The patients treated with the surfactant formulations showed a statistically significant increase of bioavailability (from 10.6+/-0.8% to 13.2+/-1.4%) and of the steady state input rate (from 75.3+/-6.6 to 98.3+/-12.1 nmol/cm2 h) compared to the control patients (iontophoresis without absorption enhancers). In five out of eight patients in the study group and in three out of eight patients in the control group, clinical improvement was observed.     

Full-Genome Sequence of Influenza A(H5N8) Virus in Poultry Linked to Sequences of Strains from Asia,the Netherlands, 2014

Genetic analyses of highly pathogenic avian influenza A(H5N8) virus from the Netherlands, and comparison with strains from Europe, South Korea, and Japan, showed a close relation. Data suggest the strains were probably carried to the Netherlands by migratory wild birds from Asia, possibly through overlapping flyways and common breeding sites in Siberia.     

Seasonal risk of low pathogenic avian influenza virus introductions into free‐range layer farms in the Netherlands

Poultry can become infected with avian influenza viruses (AIV) via (in) direct contact with infected wild birds. Free‐range chicken farms in the Netherlands were shown to have a higher risk for introduction of low pathogenic avian influenza (LPAI) virus than indoor chicken farms. Therefore, during outbreaks of highly pathogenic avian influenza (HPAI), free‐range layers are confined indoors as a risk mitigation measure. In this study, we characterized the seasonal patterns of AIV introductions into free‐range layer farms, to determine the high‐risk period. Data from the LPAI serological surveillance programme for the period 2013–2016 were used to first estimate the time of virus introduction into affected farms and then assess seasonal patterns in the risk of introduction. Time of introduction was estimated by fitting a mathematical model to seroprevalence data collected longitudinally from infected farms. For the period 2015–2016, longitudinal follow‐up included monthly collections of eggs for serological testing from a cohort of 261 farms. Information on the time of introduction was then used to estimate the monthly incidence and seasonality by fitting harmonic and Poisson regression models. A significant yearly seasonal risk of introduction that lasted around 4 months (November to February) was identified with the highest risk observed in January. The risk for introduction of LPAI viruses in this period was on average four times significantly higher than the period of low risk around the summer months. Although the data for HPAI infections were limited in the period 2014–2018, a similar risk period for introduction of HPAI viruses was observed. The results of this study can be used to optimize risk‐based surveillance and inform decisions on timing and duration of indoor confinement when HPAI viruses are known to circulate in the wild bird population.     

Modulation of stratum corneum lipid composition and organization of human skin equivalents by specific medium supplements

Our in‐house human skin equivalents contain all stratum corneum (SC) barrier lipid classes, but have a reduced level of free fatty acids (FAs), of which a part is mono‐unsaturated. These differences lead to an altered SC lipid organization and thereby a reduced barrier function compared to human skin. In this study, we aimed to improve the SC FA composition and, consequently, the SC lipid organization of the Leiden epidermal model (LEM) by specific medium supplements. The standard FA mixture (consisting of palmitic, linoleic and arachidonic acids) supplemented to the medium was modified, by replacing protonated palmitic acid with deuterated palmitic acid or by the addition of deuterated arachidic acid to the mixture, to determine whether FAs are taken up from the medium and are incorporated into SC of LEM. Furthermore, supplementation of the total FA mixture or that of palmitic acid alone was increased four times to examine whether this improves the SC FA composition and lipid organization of LEM. The results demonstrate that the deuterated FAs are taken up into LEMs and are subsequently elongated and incorporated in their SC. However, a fourfold increase in palmitic acid supplementation does not change the SC FA composition or lipid organization of LEM. Increasing the concentration of the total FA mixture in the medium resulted in a decreased level of very long chain FAs and an increased level of mono‐unsaturated FAs, which lead to deteriorated SC lipid properties. These results indicate that SC lipid properties can be modulated by specific medium supplements.     

The importance of free fatty acid chain length for the skin barrier function in atopic eczema patients

An important feature of atopic eczema (AE) is a decreased skin barrier function. The stratum corneum (SC) lipids – comprised of ceramides (CERs), free fatty acids (FFAs) and cholesterol – fulfil a predominant role in the skin barrier function. In this clinical study, the carbon chain length distribution of SC lipids (FFAs and CERs) and their importance for the lipid organization and skin barrier function were examined in AE patients and compared with control subjects. A reduction in FFA chain length and an increase in unsaturated FFAs are observed in non‐lesional and lesional SC of AE patients. The reduction in FFA chain length associates with a reduced CER chain length, suggesting a common synthetic pathway. The lipid chain length reduction correlates with a less dense lipid organization and a decreased skin barrier function. All changes are more pronounced in lesional SC compared with non‐lesional skin. No association was observed between lipid properties and filaggrin mutations, an important predisposing factor for developing AE. The results of this study demonstrate an altered SC lipid composition and signify the importance of these changes (specifically regarding the CER and FFA chain lengths) for the impaired skin barrier function in AE. This provides insights into epidermal lipid metabolism as well as new opportunities for skin barrier repair.     

Iontophoretic enhancement of timolol across human dermatomed skin in vitro

The objective of this study was to assess the in vitro the iontophoretic delivery of Timolol across human dermatomed skin in order to determine whether therapeutic doses of this drug can be delivered. Anodal iontophoresis of Timolol was performed by manipulating the donor vehicle and the current density. It was observed that by reducing simultaneously the competitive ions (NaCl) from 8 to 4 g/l and the pH from 7.4 to 4.7, the iontophoretic flux was significantly increased by a factor of 1.5 (669+/-81 microg/cm h). In order to simulate the situation in a transdermal patch, the iontophoretic delivery of Timolol was also studied after adding an artificial porous membrane placed between the Timolol formulation and the human dermatomed skin. No significant difference was observed in the steady state flux across the skin when an artificial membrane was added. Furthermore, a linear relationship was found between current density and steady state flux. These results indicate that the iontophoretic delivery of Timolol can be accurately controlled by the applied current. Assuming a one to one in vitro/in vivo correlation the Timolol transport in vitro results in therapeutic plasma concentrations in humans with very low current densities limiting possible skin irritation.     

Morphological changes of the dermatophyte Trichophyton rubrum after photodynamic treatment: a scanning electron microscopy study.

Treatment strategies for superficial mycosis caused by the dermatophyte Trichophyton rubrum consist of the use of topical or oral antifungal preparations. We have recently discovered that T. rubrum is susceptible to photodynamic treatment (PDT), with 5,10,15-tris(4-methylpyridinium)-20-phenyl-[21H,23H]-porphine trichloride (Sylsens B) as a photosensitizer. The susceptibility appeared to depend on the fungal growth stage, with PDT efficacy higher with microconidia when compared to mycelia. The aim of this study was to investigate, with the use of scanning electron microscopy, the morphological changes caused by a lethal PDT dose to T. rubrum when grown on isolated human stratum corneum. Corresponding dark treatment and light treatment without photosensitizer were used as controls. A sub-lethal PDT dose was also included in this investigation The morphologic changes were followed at various time points after the treatment of different fungal growth stages. Normal fungal growth was characterized by a fiber-like appearance of the surface of the hyphae and microconidia with the exception of the hyphal tips in full mycelia and the microconidia shortly after attachment to the stratum corneum. Here, densely packed globular structures were observed. The light dose (108 J/cm2) in the absence of Sylsens B, or the application of the photosensitizer in the absence of light, caused reversible fungal wall deformations and bulge formation. However, after a lethal PDT, a sequence of severe disruptions and deformations of both microconidia and the mycelium were observed leading to extrusion of cell material and emptied fungal elements. In case of a non-lethal PDT, fungal re-growth started on the remnants of the treated mycelium.     

Long-chain polyunsaturated fatty acids and neurological developmental outcome at 18 months in healthy term infants

Aim: Previously, we found a beneficial effect of 2 mo supplementation of infant formula with long-chain polyunsaturated fatty acids (LC-PUFA) on neurological condition at 3 mo in healthy term infants. The aim of the present follow-up study was to evaluate whether the effect on neurological condition persists until 18 mo. Methods: A prospective, double-blind, randomized control study was conducted. Three groups were formed: a control (CF; n=169), an LC-PUFA-supplemented (LF; n=146) and a breastfed (BF; n=159) group. Information on potential confounders was collected at enrolment. At the age of 18 mo, neurodevelopmental condition was assessed by the age-specific neurological examination of Hempel and the Bayley scales. The Hempel assessment resulted in a clinical neurological diagnosis, a total optimality score and a score on the fluency of motility. The Bayley scales resulted in mental and psychomotor developmental indices. Attrition at 18 mo was 5.5% and non-selective. Multivariate regression analyses were carried out to evaluate the effect of type of feeding while adjusting for confounders. Results: None of the children had developed cerebral palsy and 23 (CF: n=8; LF: n=10; BF: n=5) showed minor neurological dysfunction. The groups did not show statistically significant differences in clinical neurological condition, neurological optimality score, fluency score, and the psychomotor and mental development indices. Multivariate analysis confirmed that there was no effect of type of feeding on neurological condition.

Conclusion: This study indicates that the beneficial neurodevelopmental effect of 2 mo LC-PUFA supplementation in healthy term infants can not be detected at the age of 18 mo.     

Pharmacokinetics and pharmacodynamics analysis of transdermal iontophoresis of 5-OH-DPAT in rats: in vitro-in vivo correlation

Pharmacokinetics and dopaminergic effect of dopamine agonist 5-OH-DPAT in vivo were determined following transdermal iontophoresis in rats based on drug concentration in plasma (C(p)) and dopamine levels in striatum (C(DA)). Correlation of the in vitro transport with the pharmacokinetic-pharmacodynamic (PK-PD) profiles was characterized in the transport in dermatomed rat skin (DRS) and rat stratum corneum (RSC). The integrated in vivo PK-PD and in vitro transport models successfully described time course of C(p), C(DA), and in vitro flux in DRS and RSC. Population value of steady-state flux (J(ss)) in vivo (31 nmol/cm(2) . h with 95% confidence interval (CI) = 20-41) is closer to J(ss) in vitro in DRS (61 nmol/cm(2) . h, CI = 54-67) than in vitro J(ss) in RSC (98 nmol/cm(2) . h, CI = 79-117). On the other hand, skin release rate constant (K(R)) in vivo was similar to the K(R) in RSC (4.8/h, CI = 2.4-7.1 vs. 2.6/h, CI = 2.5-2.6). Kinetic lag time (t(L)) in vivo was negligible, which is close to in vitro t(L) in RSC (0.0 h, CI = 0.0-0.1). Based on nonlinear mixed-effect modeling, profiles of C(p) and C(DA) were successfully predicted using in vitro values of J(ss) in DRS with K(R) and t(L) in RSC. A considerable dopaminergic effect was achieved, indicating the feasibility to reach therapeutically effective concentrations of 5-OH-DPAT upon transdermal iontophoresis.     

X-ray microanalysis of cryopreserved human skin to study the effect of iontophoresis on percutaneous ion transport

Purpose. To study at the ultrastructural level which part of the skin is associated with percutaneous iodide transport by passive diffusion and iontophoresis. Methods. Following passive diffusion or iontophoresis of iodide, the morphology and the ion distribution of the skin was preserved by rapid freezing. The skin was kept frozen until and during examination by transmission electron microscopy (TEM) and X-ray microanalysis (XRMA). The intrinsic electron absorbing characteristics of cryopreserved skin allow direct TEM examination without additional staining. XRMA can be used to obtain in a relatively nondestructive way in situ information on ion distributions across the skin. Results. After passive diffusion, iodide was mainly found in the stratum corneum (SC), whereas there was little iodide in the viable epidermis. Iontophoresis up to 300 A/cm² did not significantly affect this distribution. With iontophoresis at 1000 A/cm², the amount of iodide increased dramatically and was equally distributed over the SC and viable epidermis. The presence of iodide in the SC suggests that iodide is present inside corneocytes. Conclusions. Iontophoresis up to 300 A/cm² does not significantly perturb skin structures in contrast to iontophoresis at 1000 A/cm². The presence of iodide inside corneocytes suggests the possibility of transcellular percutaneous iodide transport.