In the present work we focus on cubic type I Ba-Ge-based clathrates, where Ge in \(\rm Ba_8Ge_{43} \square_3\) (where □ is a vacancy) is substituted by Cu, Zn, Pd, and Si. Structural investigations in all cases confirm cubic primitive symmetry consistent with the space group type \(Pm\bar{3}n\) of a typical type I clathrate structure with lattice parameter a ≈ 1.06 nm. Electronic transport has been studied in a broad temperature range from 4.2 K to about 800 K, demonstrating that substitution allows fine-tuning of the charge carrier density, shifting the materials into the proximity of a metal-to-insulator transition. This is evidenced from giant thermopower reaching values of 400 μV/K in the case of Ba8Cu5.2Zn0.8Ge40.0 at temperatures well below room temperature (T max S  ≈ 150 K).

Purpose: Demonstrate the possibilities of successful surgical treatment of patients with late complications after filtering surgery. Methods: This study shows patients who have developed a cystically dilated or leaking filtering bleb in the late post-surgical period after filtering surgery. Excision of the indadequate filtering bleb has been performed in the patient with a cystic bleb. After the failure of less invasive methods of treatment, we have proceeded to bleb revision with a scleral patch graft in the patient with a leaking bleb. Results: Patients treated with either bleb excision or scleral patch graft showed no signs of neither hypotonia nor secretion during the six-months post-surgical period. During that period, complicated cataracts developed. After cataract surgery the function of the filtering bleb was preserved. Conclusions: During the several months of patients' follow-up, reconstructive methods of treatment have shown to be successful in high-risk patients who have developed post-surgical complications in the form of leaking or inadequate filtering bleb.

Purpose: To determine the incidence of unwanted light images after cataract surgery and the relationship between various intraocular lens (IOL) types. Methods: Prospective study included 50 patients who filled up a written questionnaire where reported on incidence of glare, light sensitivity and unwanted images. Patients were included in the study only if they had uneventful cataract surgery and no additional ocular pathology. They were excluded if they had refractive errors which could cause similar phenomena. The study was performed in three month postoperative period. Results: A significant number of patients reported symptoms. Patients with acrylic IOL were at increased risk. At last control more than 1/3 of symptoms resolved spontaneously. No one reported negative dysphotopsia and there was no IOL exchange. Conclusions: Intraocular lenses can introduce stray light artifacts into the eye. While positive dysphotopsia has been largely attributed to edge effects of the implant, negative dysphotopsia appears to be more related to the patient's anatomical structure than to specific lens designs or materials.

Purpose: It has been hypothesized that isolated human communities are particularly favourable for identifying genetic variants underlying complex human traits and diseases because of their reduced genetic and environmental diversity. The aim of this study was to identify genomic loci that may control variation in visual quantitative traits in 1,057 examinees in isolated island of Vis, Croatia, by positional cloning. Methods: Using refractometer, ultrasound and Canon CR-DGI non-mydriatic fundus retinal camera we obtained a number of visual quantitative and qualitative traits in our set of examinees. All measurements have been adjusted for potential confounders that were identifyied through an appropriate questionnaire. Both linkage analysis and and genome-wide association approach were used (PLINK and GENABEL softwares) to identify genomic loci that may have significant contribution to the variation observed in those traits. Results: A number of loci have been identified in the genome that approached formal significance levels after Bonaferroni correction of 10-6. Those loci now require repeat in other populations to eliminate false positive findings, and further study in bioinformatics and functional genomics to understand their potential role in trait variation and possible development of pathological states. Conclusions: This study showes that mapping genetic variants underlying complex human traits in isolated population is a feasible and powerful approach. We aim to expand our studies to other Croatian islands to further increase the power of the study.

Overexpression of acetylcholinesterase (AChE) in mice causes cholinergic deficits with memory impairment. In this study, AChE overexpressing (hAChE-Tg) and control (FVB/N) mice were treated with the AChE inhibitor (AChEI) galantamine (4 mg/kg/day) for 10 days. The concentration of galantamine in plasma was 75-80 ng/ml. The inhibition of AChE was 20% in red blood cells (RBC) and 30% in brain cortical tissue. A significant increase in [(3)H]cytisine (alpha4 nicotinic receptor) binding was measured in the CA1 and CA3 area of the hippocampus of FVB/N mice following galantamine treatment. Similarly, a significant increase in [(125)I]alphabungarotoxin (alpha7 nicotinic receptor) binding was found in the frontal cortex, retrosplenial gr. cortex, motor cortex and thalamus in galantamine treated FVB/N compared to saline treated mice. No significant changes in nicotinic receptor binding sites were observed in galantamine treated hAChE-Tg mice. Significant decreases in the muscarinic receptors measured by [(3)H]AF-DX-384 (M2 muscarinic receptor) and [(3)H]pirenzepine (M1 muscarinic receptor) were observed in several brain regions of galantamine treated FVB/N and hAChE-Tg mice. This study shows regional and receptor subtype specific changes in the nicotinic receptor subtypes compared to the muscarinic receptors following galantamine treatment in FVB/N and hAChE-Tg mice.

Ten days treatment with nicotine reduced insoluble amyloid Abeta1-40 and Abeta1-42 peptides by 80% in the cortex of 9-month-old APPsw mice, which is more than that observed in 14.5-month-old mice following nicotine treatment for 5.5 months. A reduction in Abeta associated with cerebral vessels was observed in addition to that deposited as parenchymal plaques after 5.5 months treatment. The diminution in Abeta peptides observed was not accompanied by changes in brain alpha, beta or gamma secretase-like activities, NGF or BDNF protein expression measured in brain homogenates. A significant increase in sAPP was observed after nicotine treatment of SH-SY5Yneuroblastoma cells that could be blocked by the nicotinic antagonist mecamylamine. Attenuation of elevated [I-125]-alphabungarotoxin binding (alpha7) in APPsw mice was observed after 5.5 months nicotine treatment. Both these observations suggest that the reduction in insoluble Abeta by nicotine might be in part mediated via the alpha7 nicotinic receptor. Further studies are required to identify potential mechanisms of the nicotine's amyloid-reducing effect.

Transgenic mice over-expressing human acetylcholinesterase (hAChE-Tg) display memory impairments, cholinergic deficits and reduced dendritic branching. In this study, we found a reduced number of N-Methyl-D-Aspartate (NMDA) binding sites and reduced levels of low molecular weight (LMW) microtubule associated protein 2 (MAP-2), in addition to an increased number of α4 and α7 nicotinic receptor (nAChR) binding sites in the brain of hAChE-Tg mice. Treatment with memantine, 20 mg/kg/day during 14 days, significantly increased the number of [125I]αbungarotoxin (α7 nAChR) binding sites in the frontal- and retrosplenial cortex of hAChE-Tg mice and synaptophysin- and LMW MAP-2 levels in the cortex of both hAChE-Tg and FVB/N controls. The findings reveal an alteration of the glutamatergic system in hAChE-Tg mice. Whether the effect of memantine on α7 nAChRs, synaptophysin- and LMW MAP-2 levels is a direct effect, or an indirect effect via the NMDA receptors, has to be further evaluated.

In this study, we investigated regulatory mechanisms and plasticity of the nicotinic acetylcholine receptors (nAChRs) in the brain and adrenal glands of two transgenic mice models over-expressing human beta-amyloid precursor protein (APP(SWE)Tg) and human AChE enzyme (hAChE-Tg), respectively. All animals were studied at 3 months of age. Binding studies showed higher (125)I-alpha-bungarotoxin (alpha7 nAChRs) and (3)H-epibatidine (alpha3 and alpha4 nAChRs) binding in the brain cortex and adrenal glands of hAChE-Tg mice compared to control mice. The APP(SWE)Tg mice showed a significantly lower relative level for the alpha4 mRNA in the brain cortex as well as a lower level of alpha3 mRNA, and higher level of alpha7 mRNA in the adrenal glands compared to control mice. A higher relative mRNA level of alpha3 and alpha4 nAChRs was observed in the brain as well as of alpha3 and alpha7 nAChRs in the adrenal glands of hAChE-Tg mice compared to control mice. Different nicotinic receptor plasticity is revealed in the brain cortex and adrenal glands in two transgenic mice models with different underlying pathophysiological mechanisms. Deposition of beta-amyloid (Abeta) may impair neurotransmitter activity in brain as well as in the adrenal gland.

Subtypes of nicotinic (α4 and α7) as well as muscarinic (M1 and M2) receptor binding sites were quantified in the brain of transgenic mice overexpressing human acetylcholinesterase (AChE) at different ages using selective radioligands. A significant increase in [3H]cytisine (α4) binding was found in the cortex and striatum of AChE transgenic (hAChE-Tg) mice from 3 days to 12 months of age in comparison to non-transgenic mice. In addition a significant increase in [3H]AF-DX-384 (M2) binding was found in the striatum of hAChE-Tg mice at 3 months of age compared to controls. No major alteration was observed in the [125I]α-bungarotoxin (α7) or the [3H]pirenzepine (M1) binding sites. The persistent increase in α4 and M2 receptor binding sites in hAChE-Tg mice suggests that these receptor subtypes may play an important role in compensatory mechanisms facilitating the impaired cholinergic neurotransmission in hAChE-Tg.

The nicotinic (nAChRs) and muscarinic (mAChRs) acetylcholine receptors and acetylcholinesterase (AChE) activity were studied in the brains of APP(SWE) transgenic mice (Tg+) and age-matched nontransgenic controls (Tg-) that were between 4 and 19 months of age. A significant increase in the binding of 125I-labeled alpha-bungarotoxin (alpha7 nAChRs) was observed in most brain regions analyzed in 4-month-old Tg+ mice, preceding learning and memory impairments and amyloid-beta (Abeta) pathology. The enhanced alpha7 receptor binding was still detectable at 17-19 months of age. Increase in [3H]cytisine binding (alpha4beta2 nAChRs) was measured at 17-19 months of age in Tg+ mice, at the same age when the animals showed heavy Abeta pathology. No significant changes in [3H]pirenzepine (M1 mAChRs) or [3H]AFDX 384 (M2 mAChRs) binding sites were found at any age studied. The upregulation of the nAChRs probably reflects compensatory mechanisms in response to Abeta burden in the brains of Tg+ mice.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder, of which the pathogenesis is thought to involve increased β-amyloid (Aβ) deposition and abnormal immunological responses. To elucidate the mechanisms involved in Aβ-mediated inflammation, we used immunocytochemistry and in situ hybridization to study the potential role of the cytokines interferon-γ (IFN-γ), interleukin (IL)-12 and IL-4 in transgenic mice APPSWE (Tg2576) that overexpress the human β-amyloid precursor protein gene. Cytokine and cytokine mRNA expression was detected in brain sections from cortical regions at various postnatal ages ranging from 3 to 19 months. High levels of IFN-γ and IL-12 mRNA expression, as well as their protein production, appeared early at 9 months and peaked at 17–19 months in Tg2576 mice. Significantly increased transcripts of IFN-γ and IL-12 genes were found in the reactive microglia and astrocytes surrounding β-amyloid deposits. In accordance with the kinetics of mRNA levels, the expression of IFN-γ and IL-12 at the protein level was positively correlated with age and reached a maximum in 17–19-month-old mice. Both findings suggest a role for the pro-inflammatory cytokines IFN-γ and IL-12 in early disease development and are consistent with microglial activation related to β-amyloid formation. In contrast, transcription and production of IL-4 in brain sections was almost undetectable in transgenic mice up to post-natal ages of 17–19 months. These results suggest a major pro-inflammatory role for IL-12 and IFN-γ in Tg2576 transgenic mice that may provide the association between β-amyloid plaque formation and microglial and astrocyte activation in these animals. These observations call for further studies on the potential role of anti-inflammatory therapeutic strategies for AD.

Alzheimer's disease neuropathology is characterised by beta-amyloid plaques and neurofibrillary tangles. Inhibition of beta-amyloid accumulation may be essential for effective therapy in Alzheimer's disease. In this study we have treated transgenic mice carrying the Swedish mutation of human amyloid precursor protein [Tg(Hu.APP696X670N-M671L)25761, which develop brain beta-amyloid deposits, with nicotine in drinking fluid (200 mug/mL) from 9-14.5 months of age (5.5 months). A significant reduction in amyloid beta peptide 1-42 positive plaques by more than 80% (p < 0.03) was observed in the brains of nicotine treated compared to sucrose treated transgenic mice. In addition, there was a selective reduction in extractable amyloid &beta; peptides in nicotine treated mice; cortical insoluble 1-40 and 1-42 peptide levels were lower by 48 and 60%, respectively (p < 0.005), whilst there was no significant change in soluble 1-40 or 1-42 levels. The expression of glial fibrillary acidic protein was not affected by nicotine treatment. These results indicate that nicotine may effectively reduce amyloid beta peptide aggregation in brain and that nicotinic drug treatment may be a novel protective therapy in Alzheimer's disease.

Neuronal nicotinic receptors (nAChRs) are expressed in the brain but also in the peripheral tissues including the adrenal medulla. However, it is unclear which nAChRs are present in the human adrenal medulla. In the study, receptor binding assay, Western blot and RT-PCR have been performed to investigate the expression of nAChRs in adrenal medulla from human, rat and mouse. The results showed that in human adult adrenal medulla, mRNAs for nAChR α3, α4, α5, α7, β2, β3, and β4 subunits but not β2 in the fetal human adrenal medulla were expressed. Saturation binding of [3H]epibatidine showed two binding sites in human aged adrenal medulla. The specific binding of [3H]epibatidine (0.1 nM) was significantly higher in human fetal compared to human aged adrenal medulla. mRNAs for the α3, α4, α5, α7, β2, and β4 subunits but not the β3 were detectable in adult rat and mouse adrenal medulla. No differences in gene-expression of the nAChRs were observed between new born, adult and aged rat adrenal medulla. Saturation binding of [3H]epibatidine showed only one binding site in rat adrenal medulla. Lower protein levels for the nAChR subunits were observed in the rat adrenal medulla compared to rat brain. There was lower protein levels of the nAChRs in aged rat adrenal medulla compared to the young rats. Sub-chronic treatment of nicotine to rats did not influence level of the nAChRs in the adrenal medulla. In conclusion, the expression of nAChRs in adrenal medulla is age- related and species dependent.

The basal forebrain cholinergic neurons are implicated in the pathogenesis of neurodegenerative diseases including Alzheimer's disease (AD). The nicotinic acetylcholine receptors (nAChRs) have been found to be significantly afflicted in AD. To study the underlying mechanisms for dysfunction of the basal forebrain cholinergic neurons development of suitable animal models is warranted. In this study we investigated the effects of bilateral lesions of the nucleus basalis magnocellularis on nAChRs in the rat brain using the cholinergic system selective immunotoxin 192-IgG saporin and non-selective excitotoxin ibotenic acid. Changes in nAChRs were measured by 3H-cytisine and 3H-epibatidine, two ligands with different selectivity for nAChRs subtypes. In the parietal cortex of ibotenic acid lesioned rates, the choline acetyltransferase activity (ChAT) was decreased by 24% while no changes were detected in the frontal cortex or hippocampus. Similarly, a 40% decrease was observed in the number of nAChRs labelled by 3H-cytisine, but not by 3H-epibatidine, in the parietal cortex, while no changes were found in the frontal cortex or hippocampus. Although the 192-IgG saporin induced lesions reduced the ChAT activity in the frontal cortex, parietal cortex and hippocampus by 77, 50 and 21%, respectively, no changes were observed in the number of nAChRs as studied by 3H-cytisine or 3H-epibatidine. The results indicate a difference in vulnerability of the cortical nAChR subtypes to experimental lesions of the nucleus basalis magnocellularis. The findings in this study suggest that a major portion of the nAChRs might be located on non-cholinergic neurons in the brain.

The effect of the nicotinic acetylcholine receptors (nAChRs) agonist (+/-)epibatidine on the modulation of dopamine (DA) release was investigated by microdialysis in vivo in the frontal cortex and the nucleus accumbens of naive and chronic nicotine-treated awake rats. (+/-)Epibatidine (2.5 mug/kg, s.c.), contrary to (-)nicotine (0.5 mg/kg, s.c.), decreased the extracellular concentrations of DA in the brain of naive rats. Subchronic nicotine treatment (0.45 mg/kg, s.c., twice daily for 7 days) attenuated the (+/-)epibatidine induced decrease in the DA level. The extracellular concentrations of the DA metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were elevated by (+/-)epibatidine administration in both naive and subchronic treated rats.The findings suggest that the decrease in DA extracellular concentrations induced by the high affinity nAChRs agonist (+/-)epibatidine might be due to inactivation of nAChRs, which can be overcome by subchronic treatment with nicotine. Different mechanisms in modulation of DA release appears to be involved in the rat brain by (+/-)epibatidine compare to (-)nicotine. (C) 2004 Elsevier Ltd. All rights reserved.