Effects of combined influence of ionizing radiation and light on the retina

The continuous irradiation of rats with a light (3500 1x) for 48 hours led to destruction of 7.5 +/- 0.43% of neurosensoric cells (the control value was 0.2 +/- (0.02%). Longer photodamage caused progressing decrease in a population of the cells, narrowing followed by disappearance of corresponding layers of retina by the 30th day of the experiment. Preliminary exposure to X-rays with a dose of 5 Gy modified light damages of retina. The combination of two factors caused death of more than 30% of neurosensoric cells and redused the number of rows of nucleis of the external nuclear layer twice for the first 48 hours of illumination. After a longer influence of light a preliminary ionizing irradiation increased the number of destructively changed neurosensoric cells, reaching minimun of 41.7% by 30th day of the experiment. At the same time after a long combined irradiation less changes in row number quantity, numerical density of nucleus of the external nuclear layer and a population of neurosesoric cells in general was observed than after only one light exposure. Changes of choriocapillaries (thrombosis, obliteration, narrowing of a gap) which were more expressed at a combination of factors, led to infringement of blood circulation and played the important role in mechanisms of retina degeneration. Radial glia and neurons of internal layers of retina showed relative resistance to the investigated influences.     

The damage of the neural retina and of the retinal pigment epithelium of eyes of rats exposed to highly intensive visible light under alloxanic diabetes

The experiments on white mongrel rats showed that the light with the intensity of 6000 1x lasting for 6 hours resulted the destruction of the retinal pigment epithelium, of the internal and the external neurosensory cellular processes with subsequent nuclei piknosis and radial glia replacement. On the 7th day after exposure to light focal effusion of the retina corresponding layers. Under the irradiation in diabetes the amount of cells with karyopyknosis increases in 1.6 times in comparision with the findings in case free of diabetes. Was found, that the alloxanic diabetes in its early stage increases the light impairment of the neurosensory cells of the retina.     

An unusual presentation of a malignant jejunal tumor and a different management strategy

BACKGROUND: Malignant small bowel tumors are very rare and leiomyosarcoma accounts for less than 15% of the cases. Management of these tumors is challenging in view of nonspecific symptoms, unusual presentation and high incidence of metastasis. In this case report, an unusual presentation of jejunal sarcoma and management of liver metastasis with radiofrequency ablation (RFA) is discussed. CASE PRESENTATION: A 45-year-old male presented with anemia and features of small bowel obstruction. Operative findings revealed a mass lesion in jejunum with intussusception of proximal loop. Resection of bowel mass was performed. Histopathological findings were suggestive of leiomyosarcoma. After 3-years of follow-up, the patient developed recurrence in infracolic omentum and a liver metastasis. The omental mass was resected and liver lesion was managed with radiofrequency ablation. CONCLUSION: Jejunal leiomyosarcoma is a rare variety of malignant small bowel tumor and a clinical presentation with intussusception is unusual. We suggest that an aggressive management approach using a combination of surgery and a newer technique like RFA can be attempted in patients with limited metastatic spread to liver to prolong the long-term survival in a subset of patients.     

Species loss of stoneflies (Plecoptera) in the Czech Republic during the 20th century

1. Rapid expansion and intensification of anthropogenic activities in the 20th century has caused profound changes in freshwater assemblages. Unfortunately, knowledge of the extent and causes of species loss (SL) is limited due to the lack of reliable historical data. An unusual data set allows us to compare changes in the most sensitive of aquatic insect orders, the Plecoptera, at some 170 locations in the Czech Republic between two time periods, 1955–1960 and 2006–2010. Historical data (1890–1911) on assemblages of six lowland rivers allow us to infer even earlier changes. 2. Regional stonefly diversity decreased in the first half of the 20th century. Streams at lower altitudes lost a substantial number of species, which were never recovered. In the second half of the century, large‐scale anthropogenic pressure caused SL in all habitats, leading to a dissimilarity of contemporary and previous assemblages. The greatest changes were found at sites affected by organic pollution and a mixture of organic pollution and channelisation or impoundment. Colonisation of new habitats was observed in only three of the 80 species evaluated. 3. Species of moderate habitat specialisation and tolerance to organic pollution were most likely to be lost. Those with narrow specialisations in protected habitats were present in both historical and contemporary collections. 4. Contemporary assemblages are the consequence of more than a 100 years of anthropogenic impacts. In particular, streams at lower altitude and draining intensively exploited landscapes host a mere fragment of the original species complement. Most stonefly species are less frequently present than before, although their assemblages remain almost intact in near‐natural mountain streams. Our analyses demonstrate dramatic restriction of species ranges and, in some cases, apparent changes in altitudinal preference throughout the area.     

Moderate alcohol consumption is associated with better endothelial function: a cross sectional study

Background

Natural heterologous valved conduits with a diameter greater than 22 mm that can be used for right ventricular outflow tract reconstruction in adults are not commercially available. The purpose of this study was to measure by ultrasonography the maximum diameter of the distended jugular veins of horses and cattle, respectively, to identify a population of animals that would be suitable for post-mortem collection of jugular veins at sizes greater than 22 mm.

Methods

The study population included 60 Warmblood horses, 25 Freiberger horses, 20 Brown Swiss cows, and 20 Holstein cows (including 10 Holstein and 10 Red Holstein). The maximum cross-sectional diameter of the distended jugular veins was measured at a location half-way between the mandibular angle and the thoracic inlet. The thoracic circumference (heart girth length) was used as a surrogate of body size. The jugular vein diameters of the different populations were compared by analysis of variance and the association between heart girth length and jugular vein diameter was determined in each of the four study populations by linear regression analysis.

Results

There was considerable individual variation of jugular vein diameters within each of the four study populations. There was no statistically significant relationship between thoracic circumference and jugular vein diameter in any of the populations. The jugular vein diameters of Brown Swiss cows were significantly larger than those of any of the other populations. Warmblood horses had significantly larger jugular vein diameters compared to Freiberger horses.

Conclusion

The results of this study suggest that the production of bovine or equine xenografts with diameters of greater than 22 mm would be feasible. Differences between species and breeds need to be considered. However, prediction of the jugular vein diameter based on breed and heart girth length in an individual animal is inaccurate.     

Early ultrastructural reactions in various parts of the visual analyzer in guinea pigs after thermogenic microwave irradiation]

A single total radiation of guinea pigs by means of microwaves of thermogenic intensity (energy density stream 60 mVt/sm2) and exposition for 10 min produces ultrastructural reactions in various parts of the visual analyser, differing in their manifestation degree. The most essential alterative changes have been revealed in the retina, appearing in 6 h after radiation, as degeneration of the membrane disks of the photoreceptors and as enhancement of phagocytic activity of pigmentocytes, and immediately after the radiation--as destructive disturbances of mitochondria in radial glyocytes and as reaction of the synaptic apparatus. In the cerebral visual centers a higher reactivity of neurons of the external geniculate bodies than in the visual cortex is noted, but ultrastructural disturbances of the hematoencephalic barrier and synapses of the visual cortex are more manifested. Early ultrastructural changes in the optic nerve are least manifested.     

Study of structure-activity relationship among similar analogues of GSB-106, a dipeptide mimetic of a brain-derived neurotrophic factor

In the previous work, we synthesized a dimeric dipeptide mimetic of the 4th loop of BDNF, i.e., hexamethylenediamide bis(N-monosuccinil-L-seryl-L-lysine) (GSB-106), which has neuroprotective activity in vitro in a concentration range of 10^?5–10^?8 M and antidepressant activity in vivo at intraperitoneal doses of 0.1 and 1 mg/kg in rats. We studied the structural and functional relationships among analogues of GSB-106. A glycine scan was performed, and a number of corresponding compounds were synthesized: GT-105 (where lysine was replaced by glycine), GT-107 (where serine was replaced by glycine), and GT-106Ac (where the monosuccinic radical was replaced by the acetyl group). We studied the dependence of the activity on the configuration of amino acid residues in the following compounds: GT-107D (D-enantiomer of GT-107), GT-106DL (L-serine was replaced by D-serine), GT-106LD (L-lysine was replaced by D-lysine). The investigation of these compounds in the HT22 cell culture in conditions of oxidative stress showed that only two analogues of GSB-106 had the neuroprotective effect, i.e., in the case of the replacement of serine by glycine and the succinic radical by the acetic group. This effect disappeared when the lysine residue was replaced by glycine or D-lysine and the L-serine residue, by D-serine. The results indicate the key role of the lysine side group in GSB-106 for its neuroprotective activity. The L-configuration is necessary for both the lysine and serine residues. The configuration of the lysine residue remains critical in the absence of the serine side group. Thus, the minimum neuroprotective pharmacophore of the beta-turn of the 4th loop of BDNF is the following fragment: HOOC-CH₂-CH₂-CO-NH-(S)CH(CH2OH)-CO-NH-(S)CH((CH₂)₄NH₂)-CO-NH-(CH₂)₃ Only GT-106Ac out of two analogues of GSB-106 having the neuroprotective activity showed the antidepressant activity. This indicates more stringent structural requirements for the manifestation of the antidepressant activity. The results can be useful for designing new active mimetics of BDNF.     

Neuronal Gap Junctions in Cortical Columns and Nuclei of the Ventral Thalamus of Rats

Functional cortical columns and nuclei of the ventral thalamus play a key role in processing of sensory information; therefore, detailed studies on formation of neuron-to-neuron gap junctions in these areas are of great theoretical and practical importance. In the present study, we applied electron-microscopy methods to examine the structure and specific distribution of interneuronal gap junctions in the cortical layer IV and thalamic nuclei, including VPM, RTN, Pom, and VPL. In the cortex, we found more interneuronal gap junctions than in thalamic nuclei. In all structures studied we revealed and described axo-dendritic, dendrodendritic, and “mixed” synapses. We report on the axo-dendritic gap junctions for the first time. It is suggested that this type of contacts plays some functional role in local synchronization of neuronal activity within one ensemble on the presynaptic level.     

Intragenic duplication and divergence in the spectrin superfamily of proteins

Many structural, signaling, and adhesion molecules contain tandemly repeated amino acid motifs. The alpha-actinin/spectrin/dystrophin superfamily of F-actin-crosslinking proteins contains an array of triple alpha-helical motifs (spectrin repeats). We present here the complete sequence of the novel beta-spectrin isoform beta(Heavy)- spectrin (beta H). The sequence of beta H supports the origin of alpha- and beta-spectrins from a common ancestor, and we present a novel model for the origin of the spectrins from a homodimeric actin-crosslinking precursor. The pattern of similarity between the spectrin repeat units indicates that they have evolved by a series of nested, nonuniform duplications. Furthermore, the spectrins and dystrophins clearly have common ancestry, yet the repeat unit is of a different length in each family. Together, these observations suggest a dynamic period of increase in repeat number accompanied by homogenization within each array by concerted evolution. However, today, there is greater similarity of homologous repeats between species than there is across repeats within species, suggesting that concerted evolution ceased some time before the arthropod/vertebrate split. We propose a two-phase model for the evolution of the spectrin repeat arrays in which an initial phase of concerted evolution is subsequently retarded as each new protein becomes constrained to a specific length and the repeats diverge at the DNA level. This evolutionary model has general applicability to the origins of the many other proteins that have tandemly repeated motifs.      

Comparisons of the molecular evolutionary process at rbcL and ndhF in the grass family (Poaceae)

We examine rate heterogeneity among evolutionary lineages of the grass family at two plasmid loci, ndhF and rbcL, and we introduce a method to determine whether patterns of rate heterogeneity are correlated between loci. We show both that rates of synonymous evolution are heterogeneous among grass lineages and that are heterogeneity is correlated between loci at synonymous sites. At nonsynonymous sites, the pattern of rate heterogeneity is not correlated between loci, primarily due to an aberrant pattern of rate heterogeneity at nonsynonymous sites of rbcL. We compare patterns of synonymous rate heterogeneity to predictors based on the generation time effect and the speciation rate hypotheses. Although there is some evidence for generation time effects, neither generation time effects nor speciation rates appear to be sufficient to explain patterns of rate heterogeneity in the grass plastid sequences.