Modeling individual-specific human optic nerve head biomechanics. Part I: IOP-induced deformations and influence of geometry

Glaucoma, the second most common cause of blindness worldwide, is an ocular disease characterized by progressive loss of retinal ganglion cell (RGC) axons. Biomechanical factors are thought to play a central role in RGC loss, but the specific mechanism underlying this disease remains unknown. Our goal was to characterize the biomechanical environment in the optic nerve head (ONH)—the region where RGC damage occurs—in human eyes. Post mortem human eyes were imaged, fixed at either 5 or 50 mmHg pressure and processed histologically to acquire serial sections through the ONH. Three-dimensional models of the ONH region were reconstructed from these sections and embedded in a generic scleral shell to create a model of an entire eye. We used finite element simulations to quantify the effects of an acute change in intraocular pressure from 5 to 50 mmHg on the ONH biomechanical environment. Computed strains varied substantially within the ONH, with the pre-laminar neural tissue and the lamina cribrosa showing the greatest strains. The mode of strain having the largest magnitude was third principal strain (compression), reaching 12–15% in both the lamina cribrosa and the pre-laminar neural tissue. Shear strains were also substantial. The distribution of strains in all ONH tissues was remarkably similar between eyes. Inter-individual variations in ONH geometry (anatomy) have only modest effects on ONH biomechanics, and may not explain inter-individual susceptibility to elevated intraocular pressure. Consistent with previous results using generic ONH models, the displacements of the vitreo-retinal interface and the anterior surface of the lamina cribrosa can differ substantially, suggesting that currently available optical imaging methods do not provide information of the acute deformations within ONH tissues. Predicted strains within ONH tissues are potentially biologically significant and support the hypothesis that biomechanical factors contribute to the initial insult that leads to RGC loss in glaucoma. Ian A. Sigal now a post-doctoral research fellow at Ocular Biomechanics Laboratory, Devers Eye Institute, Legacy Health Research. Portland, OR, USA. (isigal@deverseye.org).     

Biology of Ixodes (Pholeoixodes) hexagonus under laboratory conditions. Part I. Immature stages

A rearing method for Ixodes (Pholeoixodes) hexagonus, the hedgehog tick, was established which enabled the life cycle of immature stages to be studied under laboratory conditions. Larvae were fed on Swiss mice and nymphs on the cars of New Zealand rabbits. The feeding time of the larvae and nymphs on both hosts was 4–17 days. Larvae moulted to nymphs 15–21 days after detachment from mice. The premoulting period was 13–26 days for newly emerged males and 15–27 days for females. Engorged nymphs which developed into males weighed less (5.64±0.91 mg) than those that developed into females (6.019±88mg). The sex ratio (male: female) under laboratory conditions was 1:1.13.     

Myasis due to Cordylobia anthrophaga (Diptera: Calliphoirdae): description of a clinical case and review of the literature]

A case of myiasis due to Cordylobia anthropophaga is reported. The patient, an Italian man 44 years old, had come back from Nigeria and Ghana. He presented two nodular erythematous lesions of about 1 cm in diameter, on his back and right arm. From the lesions two third larval stage of C. anthropophaga were extracted. The authors report a short review about myiasis cases described in the scientific literature in Italy.     

First description of heavy skeletal deformations in Palaemon shrimp populations of European estuaries: the case of the Gironde (France)

This study aims at analyzing morphological deformities in Palaemon population in the Gironde estuary. The most frequent abnormalities affected cephalothorax and rostrum, and to a lesser extent scaphocerites and uropods (with spectacular dissymmetry), whilst only few cases of antenna and telson deformities were observed. References on morphological abnormalities of crustaceans can be found in the literature, but dealing with only isolated individuals and not for Palaemonids species, whilst in the Gironde estuary up to 40% of adult individuals are affected. Deformities likely depend on water pollutants, among others heavy metals and PCBs. This hypothesis should be tested considering other European estuaries with similar features. Handling editor: P. Viaroli     

Antarctic icefishes (Channichthyidae): a unique family of fishes. A review, Part I

Icefish or white-blooded fish are a family of species, unique among vertebrates in that they possess no haemoglobin. With the exception of one species which occurs on the southern Patagonian shelf, icefish live only in the cold-stable and oxygen-rich environment of the Southern Ocean. It is still questionable how old icefish are in evolutionary terms: they may not be older than 6 Ma, i.e. they evolved well after the Southern Ocean started to cool down or they are 15–20 Ma old and started to evolve some time after the formation of the Antarctic Circumpolar Current. Individuals of most icefish species with the exception of species of the genus Champsocephalus have been found down to 700–800 m depth, a few even down to more than 1,500 m. Icefish have been shown to present organ-level adaptations on different levels to compensate for the ‘disadvantages’ of lacking respiratory pigments. These include a low metabolic rate, well perfused gills, increased blood volume, increased cardiac output, cutaneous uptake of oxygen, increased blood flow with low viscosity, enlarged capillaries, large heart, and increased skin vascularity. Biological features, such as reproduction and growth, are not unique and are comparable to other notothenioids living in the same environment. Icefish produce large yolky eggs which have a diameter of more than 4 mm in most species. Consequently, the number of eggs produced is comparatively small and exceeds 10,000–20,000 eggs in only a few cases. With the exception of species of the genus Champsocephalus which mature at an age of 3 to 4 years, icefish do not attain maturity before they are 5–8 years old. Spawning period of most icefish species is autumn-winter. The incubation period spans from 2 to 3 months in the north of the Southern Ocean to more than 6 months close to the continent. Growth in icefish to the extent it is known is fairly rapid. They grow 6–10 cm in length per annum before they reach spawning maturity. Icefish feed primarily on krill and fish. Some icefish species were abundant enough to be exploited by commercial fisheries, primarily in the 1970s and 1980s with Champsocephalus gunnari as the main target species. Most stocks of this species had been overexploited by the beginning of the 1990s, some had further declined due to natural causes. Other species taken as by-catch species in fisheries were Chaenocephalus aceratus, Pseudochaenichthys georgianus, and Chionodraco rastrospinosus. Chaenodraco wilsoni was the only species exploited on a commercial scale in the high-Antarctic. Part II will be published in the following issue. DOI 10.1007/s00300-005-0020-6.     

Classification of the flea families (Siphonaptera): I. Family Hystrichopsyllidae (Part 5)

Based on analysis of homologous character states and considering the molecular-biological data (Whiting et al., 2008), phylogenetic relationships of the tribes and subfamilies of the family Hystrichopsyllidae are discussed. In some cases, homologous states of the skeleton characters mark the clades revealed by the moleculargenetic analysis, but are shared by taxa from other clades. In contrast to the molecular-genetic data, morphological characters indicate the phylogenetic integrity of the family Hystrichopsyllidae. Morphological characters depict the subfamily Anomiopsyllinae as a monophyletic taxon (having synapomorphic states of the metaphragma, metasternite, and the mesosternal apodeme) closest to the subfamilies Neopsyllinae and Rhadinopsyllinae. The subfamilies Neopsyllinae, Rhadinopsyllinae, and Stenoponiinae have a non-thickened metasternite; the former two subfamilies also have in common a similar structure of articulation of the digitoid with the clasper, type of the metaphragma modification, and the presence of the sclerotized central sclerite. Homologous modifications of the metaphragma are also present in fleas of the subfamily Stenoponiinae. Close to this group are the subfamily Hystrichopsyllinae whose representatives also possess non-thickened metasternal apodemes, and the subfamily Listropsyllinae with its frontal sclerotized tubercle being a specialized modification of the frontal sclerotized fold. A specific feature shared by fleas of the subfamilies Hystrichopsyllinae and Listropsyllinae is the presence of the metasternal furca with high sharp processes and a high medial ridge. The closeness of these taxa is supported by the results of molecular-genetic analysis. The subfamilies Doratopsyllinae and Ctenophthalminae (tribes Ctenophthalmini and Carterettini) are united by the type of the attachment of the mesopleural rod to the special ridge at the upper margin of the mesopleuron. According to the molecular-genetic data, the tribe Neotyphloceratini is related to these subfamilies, even though its members have no ridge on the mesopleuron. The similarity in the structure of the furca (the presence of high dorsal processes with rounded apices and a high median ridge) and in the length ratio of the fulcrum lobes relates the subfamilies Ctenophthalminae and Dinopsyllinae.     

Regulation of action potential duration under acute heat stress by I(K,ATP) and I(K1) in fish cardiac myocytes

The mechanism underlying temperature-dependent shortening of action potential (AP) duration was examined in the fish (Carassius carassius L.) heart ventricle. Acute temperature change from +5 to +18 degrees C (heat stress) shortened AP duration from 2.8 +/- 0.3 to 1.3 +/- 0.1 s in intact ventricles. In 56% (18 of 32) of enzymatically isolated myocytes, heat stress also induced reversible opening of ATP-sensitive K+ channels and increased their single-channel conductance from 37 +/- 12 pS at +8 degrees C to 51 +/- 13 pS at +18 degrees C (Q10 = 1.38) (P < 0.01; n = 12). The ATP-sensitive K+ channels of the crucian carp ventricle were characterized by very low affinity to ATP both at +8 degrees C [concentration of Tris-ATP that produces half-maximal inhibition of the channel (K1/2)= 1.35 mM] and +18 degrees C (K1/2 = 1.85 mM). Although acute heat stress induced ATP-sensitive K+ current (IK,ATP) in patch-clamped myocytes, similar heat stress did not cause any glibenclamide (10 microM)-sensitive changes in AP duration in multicellular ventricular preparations. Examination of APs and K+ currents from the same myocytes by alternate recording under current-clamp and voltage-clamp modes revealed that changes in AP duration were closely correlated with temperature-specific changes in the voltage-dependent rectification of the background inward rectifier K+ current IK1. In approximately 15% of myocytes (4 out of 27), IK,ATP-dependent shortening of AP followed the IK1-induced AP shortening. Thus heat stress-induced shortening of AP duration in crucian carp ventricle is primarily dependent on IK1. IK,ATP is induced only in response to prolonged temperature elevation or perhaps in the presence of additional stressors.     

The Cu(II)-fluconazole complex revisited. Part I: Structural characteristics of the system

Protonation equilibria and Cu(II) binding processes by an antifungal agent fluconazole, α-(2,4-difluorophenyl)-α-(1H-1,2,4-triazol-1-yl-methyl)-1H-1,2,4-triazole-1-ethanol, were studied using the UV-Vis, EPR and NMR spectroscopic techniques. The protonation constant of fluconazole was determined from NMR titration and attributed to N4′ nitrogen atoms using the DFT methods. The spectroscopic data suggest that at pH as low as 0.4 the first complex is formed, in which one or two Cu(II) ions are bound to one of the nitrogen atoms (N4′) from triazole rings. Above pH 1.5 each Cu(II) ion is surrounded by two nitrogen atoms (also N4′) from two different ligand molecules, forming primary monomeric complexes and above pH = 5, both dimeric or oligomeric species occur, which is well registered by the EPR technique.The mixture of Cu(NO₃)₂ with fluconazole in a 1:1 molar ratio in a water (pH = 4.5)/ethanol solution gave crystals of [Cu₂(H₂O){(C₆H₃-2,4-F₂)(CH₂N₃C₂H₂)₂C-OH}{(C₆H₃-2,4-F₂)(CH₂N₃C₂H₂)₂C-O}(NO₃)](NO₃)₂·9(H₂O). This complex is the first example of a cupric 3D polymeric structure with a fluconazole ligand coordinated via both N2′ and N4′ atoms from the same triazole rings. At higher pH values, we obtained a binuclear complex [Cu₂(L)₂(H₂O)₂(NO₃)₂], in which the copper(II) atoms were bridged by the oxygen atoms of the deprotonated OH group of fluconazole.The hypothetical oxidative properties of this system were also examined, however it failed to generate either reactive oxygen species or DNA scission products.     

Complements to the description of Tityus dedoslargos (Scorpiones: Buthidae)

The female of the Costarican scorpion Tityus dedoslargos Francke and Stockwell, 1987 is described for the first time and new data on its morphological variation and natural history are given. The female differs from the male mainly in having an enlarged basal median lamellae on the pectines, and lacking modified pedipalps. The species type locality relocated. This species is recorded from only two Costarican provinces: San Jose and Puntarenas.     

关于新现病毒的简述(第二部分)

4疾病"新现"的原因在公共卫生层面,新现或再现疾病的威胁不仅来自病原的不断演化,同样受社会和环境的影响。自然环境的改变在决定疾病模式方面的作用与日俱增,而目前日趋多变的气候加上经济不稳定、战争和自然灾害,更加剧了这一过程。这些因素的共同作