Effects of mild vitamin a deficiency on lung maturation in newborn rats: a morphometric and morphologic study

OBJECTIVE To evaluate the effects of a 60% vitamin A deficiency (VAD) on the two postnatal stages of lung development: alveolarization and microvascular maturation. Lungs from deficient rats were compared to age-matched controls. STUDY DESIGN Starting at 3 weeks before mating, female rats were maintained under a diet lacking vitamin A. Due to the slow depletion of the vitamin A liver stores the pregnant rats carried to term and delivered pups under mild VAD conditions. Mothers and offspring were then kept under the same diet what resulted in a mean reduction of vitamin A plasma concentration of about 60% vs. controls during the whole experimental period. Pups were sacrificed on days 4, 10 and 21 and their lungs fixed and analyzed by means of a combined morphologic and morphometric investigation at light and electron microscopic levels. RESULTS During the whole experiment, body weights of VAD animals were lower than controls with a significant decrease on day 10. On days 4, 10 and 21 the pulmonary structure was in a comparable gross morphologic state in both groups. Despite this morphologic normality, quantitative alterations in some functional parameters could be detected. On day 4, lung volume and the volume and surface area of air spaces were decreased, while the arithmetic mean barrier thickness and type 2 pneumocyte volume were increased in the VAD group. On day 21, some changes were again manifest mainly consisting in an augmentation of the vascularization and a decrease in interstitial volume in deficient animals. CONCLUSIONS Mild VAD causes no gross disturbances in the postnatal phases of lung development in rats. However, a body weight-related transient retardation of lung maturation was detectable in the first postnatal week. At 3 weeks, the VAD lungs showed a more mature vascular system substantiated by an increase in volume of both capillary volume and the large non-parenchymal vessels. In view of these quantitative alterations, we suspect that mild VAD deregulates the normal phases of body and lung growth, but does not induce serious functional impairments.

Single Molecular Conductance of Tolanes: Experimental and Theoretical Study on the Junction Evolution Dependent on the Anchoring Group

Employing a scanning tunneling microscopy based beak junction technique and mechanically controlled break junction experiments, we investigated tolane (diphenylacetylene)-type single molecular junctions having four different anchoring groups (SH, pyridyl (PY), NH2, and CN) at a solid/liquid interface. The combination of current–distance and current–voltage measurements and their quantitative statistical analysis revealed the following sequence for junction formation probability and stability: PY > SH > NH2 > CN. For all single molecular junctions investigated, we observed the evolution through multiple junction configurations, with a particularly well-defined binding geometry for PY. The comparison of density functional theory type model calculations and molecular dynamics simulations with the experimental results revealed structure and mechanistic details of the evolution of the different types of (single) molecular junctions upon stretching quantitatively.

Effects of neonatal high-dose short-term glucocorticoid treatment on the lung: a morphologic and morphometric study in the rat

Glucocorticoids are often applied in neonatology and perinatology to fight the problems of respiratory distress and chronic lung disease. There are, however, many controversies regarding the adverse side effects and long-term clinical benefits of this therapeutic approach. In rats, glucocorticoids are known to seriously impair the formation of alveoli when applied during the first two postnatal weeks even at very low dosage. The current study investigates short-term and long-term glucocorticoid effects on the rat lung by means of morphologic and morphometric observations at light and electron microscopic levels. Application of a high-dosage protocol for only few days resulted in a marked acceleration of lung development with a precocious microvascular maturation resulting in single capillary network septa in the first 4 postnatal days. By postnatal d 10, the lung morphologic phenotype showed a step back in the maturational state, with an increased number of septa with double capillary layer, followed by an exceptional second round of the alveolarization process. As a result of this process, there was an almost complete recovery in the parenchymal lung structure by postnatal d 36, and by d 60, there were virtually no qualitative or quantitative differences between experimental and control rats. These findings indicate that both dosage and duration of glucocorticoid therapy in the early postnatal period are very critical with respect to lung development and maturation and that a careful therapeutic strategy can minimize late sequelae of treatment.

Equine pastern vasculitis: a clinical and histopathological study.

Equine pastern vasculitis is clinically challenging and the underlying aetiopathogenesis is unclear. The aims of this retrospective study were to establish histopathological criteria for pastern vasculitis, to look for an underlying cause, to investigate whether the histopathological lesions are associated with a distinct clinical picture, to assess if and how the clinical picture varies, and to determine the treatment response. Skin biopsies and clinical data from 20 horses with a diagnosis of vasculitis of the distal extremities were investigated and histology was compared to biopsies from healthy horses. It was concluded that intramural inflammatory cells, leukocytoclasia with nuclear dust, thickening and oedema of the vessel walls, and microhaemorrhages are highly specific histological findings in equine pastern vasculitis. Based on the feedback from the clinicians, the lesions were mostly seen on the lateral and medial aspects of un-pigmented legs. Lesions in white skin were characterised by exudation and crusts, whereas those in pigmented skin were alopecic and characterised by scaling. The response to treatment was poor and the prognosis guarded. No association was found between any of the histopathological findings and a distinct clinical picture. An underlying cause of equine pastern vasculitis could not be identified. Considering the large number of confounding factors, the causative agents are difficult to identify, but may involve drugs or a hypersensitivity reactions to yet unknown antigens.

Tetrathiafulvalene - Benzothiadiazoles as Redox-Tunable Donor - Acceptor Systems: Synthesis and Photophysical Study

Electrochemical and photophysical analysis of new donoracceptor systems 2 and 3, in which a benzothiadiazole (BTD) unit is covalently linked to a tetrathiafulvalene (TTF) core, have verified that the lowest excited state can be ascribed to an intramolecular-charge-transfer (ICT) (TTF)*(benzothiadiazole) transition. Owing to better overlap of the HOMO and LUMO in the fused scaffold of compound 3, the intensity of the 1ICT band is substantially higher compared to that in compound 2. The corresponding CT fluorescence is also observed in both cases. The radical cation TTF+. is easily observed through chemical and electrochemical oxidation by performing steady-state absorption experiments. Interestingly, compound 2 is photo-oxidized under aerobic conditions.