Phase transformation in the "Brodie graphite oxide-acetonitrile" system - influence of the oxidizing level of the material.

Reversible phase transformation in the Brodie graphite oxide-acetonitrile system, which is intercalation or release of part of the sorbed liquid from the interplanar space accompanied by an increase or a decrease in interplanar distances, is commonly observed in twice-oxidized materials. We observed this phenomenon for once-, twice- and thrice-oxidized materials using the EPR spin probe technique, DSC, and temperature programmed XRD. It was shown that all materials under study formed similar low temperature (LT) and high temperature (HT) swollen structures with acetonitrile. The phase transformation of these structures is observed for materials with different oxidation levels in the same temperature range (∼20 K). The twice- and thrice-oxidized Brodie graphite oxides form swollen structures with the same parameters, while the once-oxidized material sorbs less acetonitrile at lower temperatures, but shows the same interplanar distances as those in twice- and thrice-oxidized materials. The spin probe technique has proven its sensitivity to the appearance of small amounts of the new forming swollen structures, which makes this method useful in studies of phase transformations.

Sorption of Polar Sorbents into GO Powders and Membranes.

The comparative study of sorption of polar substances acetonitrile and water into powders and membranes (>10 µm thick) of modified Hummers (HGO) and Brodie (BGO) graphite oxides was performed using isopiestic method (IM) and differential scanning calorimetry (DSC). Additional sorption data were obtained for pyridine and 1-octanol. Sorption measurements were accompanied by conventional XRD and XPS control. Electron paramagnetic resonance (EPR) was additionally used to characterize ordering of the membranes. The impact on sorption of synthetic procedure (Brodie or Hummers), method of making membranes, chemical nature of the sorbent, and method of sorption was systematically examined. It was demonstrated that variations in synthetic procedures within both Hummers and Brodie methods did not lead to changes in the sorption properties of the corresponding powders. Sorption of acetonitrile and pyridine was reduced by approximately half when switching from powders to membranes at ambient temperature. DSC measurements at a lower temperature gave equal sorption of acetonitrile into HGO powder and membranes. Water has demonstrated unique sorption properties. Equal sorption of water was measured for HGO membranes and powders at T = 298 K and at T = 273 K. It was demonstrated that lowering the orientational alignment of the membranes led to the increase of sorption. In practice this could allow one to tune sorption/swelling and transport properties of the GO membranes directly by adjusting their internal ordering without the use of any composite materials.

The Use of Atomic Force Microscopy in Comprehensive Assessment of the "Mother-Placenta-Fetus" System in Obstetric and Endocrine Pathology during Pregnancy.

Atomic force microscopy is not very popular in practical health care, therefore, its potential is not studied enough, for example, in obstetrics when studying the "mother-placenta-fetus" system. Our study summarizes the possibilities of using atomic force microscopy for detection of various circulatory disorders and vascular changes at the microscopic level in the uterus (endometrium and myometrium), placenta, and umbilical cord in the main variants of obstetric and endocrine pathology. For instance, in the case of endocrine pathologies, changes in the form of stasis, sludge, diapedesis, ischemia, destruction and separation of endotheliocytes in villous blood vessels were found in the mother. The oxygen content in erythrocytes also naturally decreased in pathologies; poikilo- and anisocytosis were observed.

[Uteroplacental blood flow in maternal diabetes mellitus]. / Matochno-platsentarnyi krovotok pri sakharnom diabete u materi.

Various uteroplacental blood flow disorders, their diagnosis, and correction, especially if the maternal obstetric history is burdened by endocrinopathy, still remain an urgent obstetric problem. OBJECTIVE: To study blood flow in the vessel-red blood cell segment and to search for changes in both the vessels of the villous tree of the placenta and uterus and the properties of blood corpuscles, by using modern microscopy methods (scanning probe microscopy, atomic force microscopy). MATERIAL AND METHODS: For macroscopic and microscopic examinations, fragments of the placenta, umbilical cord, and uterus were taken; venous blood samples were collected from patients without endocrinopathy, with gestational diabetes mellitus (GDM) or type 1 and type 2 diabetes mellitus (DM) prior to delivery. The data were statistically processed using both parametric (Student's t-test) and nonparametric (Fisher's exact test) methods. RESULTS: The authors found that microangiopathy and other metabolic changes in diabetes mellitus could lead to villous stromal sclerosis, the appearance of intermediate villi, changes in blood vessel shape, relief tortuosity, depth, and area, endothelial cell destruction, stasis, and thrombosis. In these endocrinopathies, there were also changes in maternal red blood cells: their polymorphism was observed and geometric parameters and deformability were impaired. In this case, cell shape impairment correlated with the severity of the above described vascular complications. CONCLUSION: The use of modern microscopy methods makes it possible to diagnose uteroplacental blood flow changes even in early pregnancy and to prevent the progression of uteroplacental blood flow disorders and placental insufficiency.

Use of Soil and Litter Ants (Hymenoptera: Formicidae) as Biological Indicators of Soil Quality Under Different Land Uses in Southern Rwanda.

The use of soil and litter arthropods as biological indicators is a way to assess environmental changes, where ant species in particular may serve as important indicators of soil quality. This study aimed at relating the abundance of soil and litter ant species to soil parameters under different tree species, both native and exotic, and varieties of coffee and banana plantations. Variations were found in soil physicochemical parameters. A total of 30 species belonging to 14 genera, and four subfamilies, the Formicinae, Dorylinae, Myrmicinae, and Ponerinae were identified. Higher abundance was found in coffee plantations compared to banana plantations, exotic and native tree species. Species of Camponotus cinctellus and Odontomachus troglodytes occurred in all land uses which is a sign of tolerance to a wide range of soil properties. In addition, these species, together with Myrmicaria SP02, Phrynoponera gabonensis, Camponotus SP06, Myrmicaria opaciventris, Pheidole SP03, Tetramorium simillimum, Pheidole SP01, and Tetramorium laevithorax were not strongly correlated with soil physicochemical parameters. Species of Pheidole SP02 and Camponotus SP05 were restricted to specific soil physicochemical properties, while species of Tetramorium zonacaciae and Bothroponera talpa discriminated between native tree species, coffee plantations, soil organic carbon, sandy soil texture, and aggregate stability. We concluded that these ant species can differently indicate the soil quality depending on the land use. We recommended further studies in order to generalize these findings.

The role of 5-HT1A receptors in mediating acute negative effects of antidepressants: implications in pediatric depression.

Acute antidepressant exposure elevates the frequency of impulsive behavior and suicidal thoughts in children and adolescents with major depressive disorder (MDD). Long-term antidepressant treatment, however, is beneficial for pediatric MDD, so it is necessary to explore novel treatments that prevent the potentially dangerous consequences of acute antidepressant initiation. In the present study, a treatment strategy designed to reverse the acute negative behavioral effects of antidepressants was tested in rodents. Co-administration of the 5-HT1A receptor (5-HT1AR) antagonist WAY-100635 reversed the negative effects of acute fluoxetine, a serotonin reuptake inhibitor, but not reboxetine, a norepinephrine reuptake inhibitor, supporting the involvement of 5-HT1AR in mediating the negative consequences of acute selective serotonin reuptake inhibitor (SSRI) treatment. No 5-HT1AR antagonists are currently approved for use in pediatric populations, so alternative strategies should be explored. One such strategy was suggested based on the hypothesis that the rate of 5-HT1AR activation and the subsequent inhibition of serotonergic neuron activity caused by acute SSRI administration is proportional to the loading rate of an antidepressant. Existing pharmacological data were examined, and significant correlations were observed between the half-life of antidepressants and the rate of suicide-related events (SREs). Specifically, antidepressants with longer half-lives have lower rates of SREs. On the basis of these data, novel dosing strategies were developed for five antidepressants to mimic the pharmacological profile of the antidepressant with the longest half-life, fluoxetine. These dosing strategies could be used to decrease the rate of SREs associated with acute antidepressant treatment in pediatric MDD until an improved pharmacological treatment is developed.

Glutamate in CNS neurodegeneration and cognition and its regulation by GCPII inhibition.

Glutamate, first identified in 1866, is the primary excitatory neurotransmitter in the brain. While it is critically important in many highly regulated cortical functions such as learning and memory, glutamate can be much like the magic the Sorcerer's Apprentice used in Goethe's poem: when conjured under unregulated conditions glutamate can get quickly out of control and lead to deleterious consequences. Two broad types of glutamate receptors, the ionotropic and metabotropic, facilitate glutamatergic neurotransmission in the CNS and play key roles in regulating cognitive function. Excessive activation of these receptors leads to excitotoxicity, especially in brain regions that are developmentally and regionally vulnerable to this kind of injury. Dysregulation of glutamate signaling leads to neurodegeneration that plays a role in a number of neuropsychiatric diseases, prompting the development and utilization of novel strategies to balance the beneficial and deleterious potential of this important neurotransmitter. Inhibition of the enzyme glutamate carboxypeptidase II (GCPII) is one method of manipulating glutamate neurotransmission. Positive outcomes (decreased neuronal loss, improved cognition) have been demonstrated in preclinical models of ALS, stroke, and Multiple Sclerosis due to inhibition of GCPII, suggesting this method of glutamate regulation could serve as a therapeutic means for treating neurodegeneration and cognitive impairment.

Thalidomide for acute treatment of neurosarcoidosis.

STUDY DESIGN: Case report. CLINICAL SETTING: Johns Hopkins University School of Medicine, Baltimore, MD, USA. CASE REPORT: Sarcoidosis is a multi-system granulomatous disease of unknown etiology with worldwide distribution. The involvement of the nervous system is common-neurosarcoidosis. Immune responses play an important role in the inflammatory process and granuloma formation. We report a case of neurosarcoidosis that was refractory to two courses of intravenous steroids. Upon initiation of oral thalidomide, the patient showed dramatic improvement clinically and on magnetic resonance imaging. CONCLUSION: Thalidomide is an immunomodulatory agent that acts to inhibit production of tumor-necrosis factor-alpha (TNF-alpha), an important mediator in CNS inflammation, by enhancing TNF-alpha mRNA degradation. Corticosteroids have been the mainstay of treatment of neurosarcoidosis with success at halting progression of the immune process in 50% cases. Thalidomide offers unique opportunities at managing CNS inflammation due to neurosarcoidosis. DISCLOSURES: None.

Idiopathic transverse myelitis: corticosteroids, plasma exchange, or cyclophosphamide.

Transverse myelitis is a focal disorder of the spinal cord in which an immune-mediated process results in neural injury. In this large retrospective study, we compare patients who received one of four treatments to identify the most effective therapies. We identified subsets of patients who received clinical benefit from plasma exchange or cyclophosphamide being included in their treatment regimen.

Differential neuronal localizations and dynamics of phosphorylated and unphosphorylated type 1 inositol 1,4,5-trisphosphate receptors.

Type 1 inositol 1,4,5-trisphosphate receptors are phosphorylated by cyclic-AMP-dependent protein kinase A at serines 1589 and 1755, with serine 1755 phosphorylation greatly predominating in the brain. Inositol 1,4,5-trisphosphate receptor protein kinase A phosphorylation augments Ca(2+) release. To assess type 1 protein kinase A phosphorylation dynamics in the intact organism, we developed antibodies selective for either serine 1755 phosphorylated or unphosphorylated species. Immunohistochemical studies reveal marked variation in localization. For example, in the hippocampus the phosphorylated type 1 inositol 1,4,5-trisphosphate receptor is restricted to CA1, while the unphosphorylated receptor occurs ubiquitously in CA1-CA3 and dentate gyrus granule cells. Throughout the brain the phosphorylated type 1 inositol 1,4,5-trisphosphate receptor is selectively enriched in dendrites, while the unphosphorylated receptor predominates in cell bodies. Focal cerebral ischemia in rats and humans is associated with dephosphorylation of type 1 inositol 1,4,5-trisphosphate receptors, and glutamatergic excitation of cerebellar Purkinje cells mediated by ibogaine elicits dephosphorylation of type 1 inositol 1,4,5-trisphosphate receptors that precedes evidence of excitotoxic neuronal degeneration. We have demonstrated striking variations in regional and subcellular distribution of inositol 1,4,5-trisphosphate receptor phosphorylation that may influence normal physiological intracellular Ca(2+) signaling in rat and human brain. We have further shown that the subcellular distribution of inositol 1,4,5-trisphosphate receptor phosphorylation in neurons is regulated by excitatory neurotransmission, as well as excitotoxic insult and neuronal ischemia-reperfusion. Phosphorylation dynamics of type 1 inositol 1,4,5-trisphosphate receptors may modulate intracellular Ca(2+) release and influence the cellular response to neurotoxic insults.

Purified inositol hexakisphosphate kinase is an ATP synthase: diphosphoinositol pentakisphosphate as a high-energy phosphate donor.

Diphosphoinositol pentakisphosphate (PP-IP5) and bis(diphospho)inositol tetrakisphosphate (bis-PP-IP4) are recently identified inositol phosphates that possess pyrophosphate bonds. We have purified an inositol hexakisphosphate (IP6) kinase from rat brain supernatants. The pure protein, a monomer of 54 kDa, displays high affinity (Km = 0.7 microM) and selectivity for inositol hexakisphosphate as substrate. It can be dissociated from bis(diphospho)inositol tetrakisphosphate synthetic activity. The purified enzyme transfers a phosphate from PP-IP5 to ADP to form ATP. This ATP synthase activity indicates the high phosphate group transfer potential of PP-IP5 and may represent a physiological role for PP-IP5.

Reduced nicotinamide adenine dinucleotide-selective stimulation of inositol 1,4,5-trisphosphate receptors mediates hypoxic mobilization of calcium.

To evaluate the relationship of inositol 1,4,5-trisphosphate (IP3) receptor-mediated signal transduction and cellular energy dynamics, we have characterized effects of nucleotides on IP3 receptor (IP3R)-mediated calcium (Ca2+) flux in purified IP3 receptors reconstituted in lipid vesicles (IP3RV) and examined hypoxia-induced augmentation of intracellular Ca2+ in intact cells. Reduced nicotinamide adenine dinucleotide (NADH) increases IP3-mediated Ca2+ flux in IP3RV. This effect is highly specific for NADH. Hypoxia elicited by brief exposure of nerve growth factor-differentiated PC12 cells or cerebellar Purkinje cells to cyanide elicits rapid increased in internal [Ca2+], which derives from IP3-sensitive stores. Blockade of this effect by 2-deoxyglucose and inhibition of glyceraldehyde-3-phosphate dehydrogenase implicates enhanced glycolytic production of NADH in the Ca2+ stimulation. Internal [Ca2+] is markedly and specifically increased by direct intracellular injection of NADH, and this effect is blocked by heparin, further implicating IP3R stores. These findings indicate that direct regulation of IP3R by NADH is responsible for elevated cytoplasmic [Ca2+] occurring in the earliest phase of hypoxia. This link of IP3R activity with cellular energy dynamics may be relevant to both hypoxic damage and metabolic regulation of IP3 signaling processes.

Immunophilin FK506 binding protein associated with inositol 1,4,5-trisphosphate receptor modulates calcium flux.

The immunophilin FK506 binding protein 12 (FKBP12) is associated with and modulates the ryanodine receptor calcium release channel of skeletal muscle. Ryanodine receptor has amino acid homology and functional similarity with another intracellular Ca2+ release channel, the inositol 1,4,5-trisphosphate receptor (IP3R). In the present study we show that highly purified preparations of IP3R contain FKBP12. The complex of these two proteins is disrupted by the immunosuppressants FK506 and rapamycin, both of which are known to bind FKBP12 with high affinity. Disrupting the IP3R-FKBP12 interaction increases Ca2+ flux through IP3R, an effect that is reversed by added FKBP12. FKBP12 appears to be physiologically linked to IP3R, regulating its Ca2+ conductance.

Purified reconstituted inositol 1,4,5-trisphosphate receptors. Thiol reagents act directly on receptor protein.

Thimerosal, a sulfhydryl oxidizing reagent, has been shown to induce Ca2+ mobilization in several cell types and to increase the sensitivity of intracellular Ca2+ stores to inositol 1,4,5-trisphosphate (IP3). Using purified IP3 receptor (IP3R) protein reconstituted in vesicles, we demonstrate pronounced stimulation by thimerosal of its Ca2+ channel activity. Effects of thimerosal are dependent on the redox state of the receptor, implying an action of thimerosal on a critical sulfhydryl group(s) of IP3R. Thimerosal enhances the affinity of IP3R for IP3 binding. The manner in which thimerosal modulates IP3R responsiveness to IP3 provides evidence for receptor heterogeneity with implications for mechanisms of quantal Ca2+ release. These results clarify regulation of IP3R activity by redox modulation.

Protein traffic between distinct plasma membrane domains: isolation and characterization of vesicular carriers involved in transcytosis.

We have isolated a population of vesicular carriers involved in the transport (transcytosis) of proteins from the basolateral to the apical plasma membrane of hepatocytes. The obtained fraction was enriched in compartments containing known transcytosed proteins and depleted in elements of the secretory pathway, Golgi elements, basolateral plasma membrane, as well as early endosomal components. The fraction was analyzed by biochemical and immunological procedures. Antibodies raised against the proteins in the fraction recognized a single 108K antigen. Based on its subcellular distribution, the 108K antigen may represent a novel marker for transcytotic vesicular carriers.