Formation of Precipitation Ellipsoidal Disks and Spheres in the Wake of a Planar Diffusion Front.

Pattern formation is one of the examples of self-organization. In the generation of patterns, the coupling between the mass transport of the chemical species and their chemical reactions plays an important role. Periodic precipitation (Liesegang phenomenon) is a type of pattern formation in which layered precipitation structures form in the wake of the diffusion front. Here, we show a new type of precipitation pattern formation in zeolitic imidazolate framework-67 in a solid hydrogel column in a test tube manifested in the generation of precipitation ellipsoidal disks and spheres in the wake of the planar diffusion front of the outer electrolyte (2-methylimidazole). To increase the probability of the emergence of ellipsoidal disks and spheres, the surfaces of the borosilicate test tubes were chemically treated and functionalized. To support the experimental findings, we developed a reaction-diffusion model that qualitatively describes the formation of precipitate ellipsoidal disks and spheres in a test tube.

Correlation between calcium, water contents and ultrasonographic appearance of atherosclerotic lesions of carotid artery lesions.

BACKGROUND: We tested the hypothesis whether there is a correlation between the echogenicity and calcium and water contents of carotid plaques. PATIENTS AND METHODS: Ninety carotid befurcations from 45 deceased patients were removed during autopsy. Thirty-four plaques were categorized as homogenous echolucent (HEL), homogenous echogenic (HEG) and heterogenous (HE) plaques based on premortem B-mode image. Water content was expressed in % of wet weight. Ca was determined by proton-induced X-ray emission and expressed in ppm. Relative optical density of the B-mode images was analyzed offline using a computer program. RESULTS: HEL plaques had lower Ca content (medians and IQRs: 6,145 [4,465-6,536 ppm]) compared to HEG (74,100 [15,300-1,44,500-ppm]), P ≤ 0.001). HE plaques showed an intermediate calcium content (7,310 [4,840-9,920 ppm]) that was statistically not different from echolucent plaques. Water content of HEG plaques was statistically not different from HEL and HE (HEG:53.5 [35.5-64%], HEL: 73.5 [69.7-78.5%], HE: 70.6 [67.4-73.9%]). HEG plaques had the highest relative optical densities (196 [188-217%]). HEL and HE had similar relative optical densities (HEL: 176 [164-187%], HE: 164 [144-188%], respectively). A significant positive correlation was found between the Ca content and relative optical density of plaques. CONCLUSIONS: Echogenicity of carotid plaques increases along with their calcium content. Water content may be an important factor in differentiation of different plaques.

Intra-arterial Thrombolysis in Second Trimester of Pregnancy. A Case Report.

Here we present a successful intra-arterial thrombolysis performed in the second trimester of pregnancy (21 weeks). The intervention resulted in complete recanalization of the occluded right middle cerebral artery and favourable clinical and gestational outcome. Together with cases described in respective medical literature our report affirms that in pregnancy acute ischemic stroke could be treated effectively applying intra-arterial thrombolysis (using rt-PA). This therapy could provide opportunity to help in such desperate situations.

Signal transduction pathway activity compensates dopamine D2/D3 receptor density changes in Parkinson's disease: a preliminary comparative human brain receptor autoradiography study with [³H]raclopride and [³5S]GTPγS.

The degeneration of dopaminergic nigrostriatal pathway in Parkinson's disease (PD) results in alterations of the dopamine receptor system. In the present study we have investigated the relationship between the disease related changes of expressed dopamine D2/D3 receptor density and the corresponding intracellular signal transduction route in cortical and sub-cortical brain structures in the human brain. Dopamine D2/D3 receptor autoradiography (ARG), using [³H]raclopride, and agonist stimulated [³5S]GTPγS (guanosine 5'-O-[γ-thio]triphosphate) binding autoradiography have been performed in human striatum, cingulate gyrus and medial frontal gyrus samples obtained from six deceased PD patients and six age matched control subjects. Receptor densities were expressed as fmol/gram tissue protein for [³H]raclopride; agonist stimulated [³5S]GTPγS binding was expressed in fmol/gram tissue and its change was expressed in percentage values above basal binding. Our results indicate that whereas there is a decrease of the dopamine D2/D3 receptors in the striatum demonstrated by classical receptor autoradiography (controls and PD: 24.08±2.06 fmol/gram (mean±SEM) and 18.43±2.82 fmol/gram, respectively; p<0.05), the corresponding agonist stimulated [³5S]GTPγS binding autoradiography shows unchanged basal [³5S]GTPγS binding (controls and PD: 199±17 fmol/g and 198±21 fmol/g, respectively; n.s.) and, at the same time, no change in stimulation (controls and PD: 0.40±4.57% and 1.51±2.27%, respectively; n.s.). In cingular gyrus and medial frontal gyrus neither the dopamine D2/D3 receptor densities nor the [³5S]GTPγS binding displayed significant differences between PD and age matched control brain samples, whereas the [³5S]GTPγS binding values were markedly higher in PD. These preliminary findings may indicate a possible compensatory mechanism in striatal regions of PD brains: the loss of the dopamine receptors in the striatum appears to be compensated by an increased post-synaptic intracellular signal transduction route activity. However, the accurate interpretation of the present findings requires detailed further studies.

The decrease of dopamine D2/D3 receptor densities in the putamen and nucleus caudatus goes parallel with maintained levels of CB1 cannabinoid receptors in Parkinson's disease: a preliminary autoradiographic study with the selective dopamine D2/D3 antagonist [³H]raclopride and the novel CB1 inverse agonist [¹²5I]SD7015.

Cannabinoid type-1 receptors (CB1Rs) modulate synaptic neurotransmission by participating in retrograde signaling in the adult brain. Increasing evidence suggests that cannabinoids through CB1Rs play an important role in the regulation of motor activities in the striatum. In the present study, we used human brain samples to examine the relationship between CB1R and dopamine receptor density in case of Parkinson's disease (PD). Post mortem putamen, nucleus caudatus and medial frontal gyrus samples obtained from PD patients were used for CB1R and dopamine D2/D3 receptor autoradiography. [¹²5I]SD7015, a novel selective CB1R inverse agonist, developed by a number of the present co-authors, and [³H]raclopride, a dopamine D2/D3 antagonist, were used as radioligands. Our results demonstrate unchanged CB1R density in the putamen and nucleus caudatus of deceased PD patients, treated with levodopa (L-DOPA). At the same time dopamine D2/D3 receptors displayed significantly decreased density levels in case of PD putamen (control: 47.97 ± 10.00 fmol/g, PD: 3.73 ± 0.07 fmol/g (mean ± SEM), p<0.05) and nucleus caudatus (control: 30.26 ± 2.48 fmol/g, PD: 12.84 ± 5.49 fmol/g, p<0.0005) samples. In contrast to the putamen and the nucleus caudatus, in the medial frontal gyrus neither receptor densities were affected. Our data suggest the presence of an unaltered CB1R population even in late stages of levodopa treated PD. This further supports the presence of an intact CB1R population which, in line with the conclusion of earlier publications, may be utilized as a pharmacological target in the treatment of PD. Furthermore we found discrepancy between a maintained CB1R population and a decreased dopamine D2/D3 receptor population in PD striatum. The precise explanation of this conundrum requires further studies with simultaneous examination of the central cannabinoid and dopaminergic systems in PD using higher sample size.

[¹²5I]SD-7015 reveals fine modalities of CB1 cannabinoid receptor density in the prefrontal cortex during progression of Alzheimer's disease.

The cannabinoid type-1 receptor (CB1R) is one of the most abundant members of the G protein-coupled receptor family in the central nervous system. Once activated by their cognate ligands, endocannabinoids, CB1Rs generally limit the timing of neurotransmitter release at many cortical synapses. Prior studies have indicated the involvement of CB1R in neurodegeneration and in various neuronal insults, with an emphasis on their neuroprotective role. In the present study we used a novel selective CB1R radioligand to investigate regional variations in CB1R ligand binding as a factor of progressive Braak tau pathology in the frontal cortex of Alzheimer's disease (AD) patients. The frontal cortex was chosen for this study due to the high density of CB1Rs and their well-characterized involvement in the progression of AD. Post-mortem prefrontal cortex samples from AD patients from Braak stages I to VI and controls were subjected to CB1R autoradiography with [¹²5I]SD-7015 as radioligand. Regional concentration of [¹²5I]SD-7015, corresponding to, and thereby representing, regional CB1R densities, were expressed in fM/g_tissue. The results show that CB1R density inversely correlates with Braak tau pathology with the following tendency: controls

Visualization of the ischemic core on native human brain slices by potassium staining method.

The potassium staining method is based on the formation of potassium cobaltnitrite crystals after the treatment by sodium cobaltnitrite of brain tissue. The degree of staining correlates with the distinct potassium content of infracted and non-infarcted brain areas. The aim of the present study was to prove that potassium staining technique is a reliable method for localization of ischemic core on native whole hemisphere cryosections of stroke patients. Furthermore, potassium stained sections have been compared with appropriate postmortem MRI images of respective brains. Brains of stroke patients were removed within 24h after death and postmortem MRI scanning was performed. Horizontal cryosections of frozen brains were taken and potassium staining was performed. Using the stained whole hemisphere sections as "map" tissue sampling has been made in order to determine water and potassium content. Potassium content of infarcted samples was significantly decreased in comparison with intact regions (0.7346+/-0.2142 mg/L and 1.928+/-0.447 mg/L, respectively, p<0.01) (mean values+/-SD). Water content of affected areas (expressed in percents) has been found to be above non-infarcted regions (81.657%+/-4.07 and 72.96%+/-6.37, respectively, p<0.01). According to our results the potassium staining method of human whole hemisphere brain sections reliably differentiates focal ischemic areas from intact brain regions. In conclusion, the postmortem examination of ischemic brain could be started with making the potassium map of infarcted whole hemisphere cryosections providing guidance for targeted tissue sampling and base of comparison for further examinations.