Aluminophosphate monoliths with high CO2-over-N2 selectivity and CO2 capture capacity

Monoliths of microporous aluminophosphates (AlPO₄-17 and AlPO₄-53) were structured by binder-free pulsed current processing.

Cerebrospinal fluid sorbitol and myoinositol in diabetic polyneuropathy

Changes in cerebrospinal fluid (CSF) concentrations of sorbitol and myoinositol in 21 patients with diabetic polyneuropathy were studied with gas-liquid chromatography. The sorbitol concentration was significantly increased in diabetic patients with elevated plasma glucose. Myoinositol concentration was significantly decreased in patients with polyneuropathy compared with the controls. Both alterations in polyol concentrations of the CSF were present already two months from onset of symptoms of diabetes. Patients with peripheral polyneuropathy receiving oral hypoglycemic drugs did not have elevated plasma glucose and CSF sorbitol levels, but showed significantly decreased CSF myoinositol concentrations compared with the controls. These observations suggest that myoinositol concentration may be decreased in the central nervous system in adult onset mild diabetes with normal plasma glucose and that the decrease in the myoinositol in CSF possibly is connected with the development of neuropathy.

Morbid obesity, gastric plication and a severe neurological deficit

A 39-year-old man had protracted vomiting after gastric plication for morbid obesity. Within three months he lost 53 kg in weight and developed neuromuscular weakness, especially in the lower extremities. Clinical and laboratory studies suggested both radicular and peripheral neuropathy. One year later the condition was only marginally improved: he took only few steps unsupported. The apparent etiology is malnutrition but the primary cause remained unknown.

Nandrolone decanoate administration dose-dependently affects the density of kappa opioid peptide receptors in the rat brain determined by autoradiography

The kappa opioid receptor ligand [(3)H]CI-977 was used to autoradiographically determine the density of kappa opioid receptors in the male rat brain following chronic treatment with the anabolic androgenic steroid nandrolone decanoate at two different doses. As compared to controls, significantly lower densities of the kappa opioid receptor were encountered after two weeks of high dose nandrolone decanoate (15 mg/kg) in the nucleus accumbens shell (16%), lateral hypothalamic area (36%), ventromedial hypothalamic nucleus (37%), dorsomedial hypothalamic nucleus (49%), central amygdaloid nucleus, capsular part (28%), lateral globus pallidus (35%) and in the stria terminalis (24%). Furthermore, an up-regulation of the receptor level was observed in the caudate putamen (18%) and in the dorsal endopiriform nucleus (23%). These alterations in the kappa opioid receptor expression are possibly attributed to a previously observed pronounced impact of nandrolone decanoate on the dynorphinergic system and could also include involvement of the dopaminergic reward system.

Intriguing asexual life in marginal populations of the brown seaweed Fucus vesiculosus

Reproduction of attached large brown algae is known to occur only by sexual zygotes. Using microsatellites we show evolution of asexual reproduction in the bladder wrack promoting population persistence in the brackish water Baltic Sea (< 6 psu). Here a dwarf morph of Fucus vesiculosus is dominated by a single clone but clonal reproduction is also present in the common form of the species. We describe a possible mechanism for vegetative reproduction of attached algae, and conclude that clonality plays an important role in persistence and dispersal of these marginal populations, in which sexual reproduction is impaired by low salinity.

The anabolic-androgenic steroid nandrolone induces alterations in the density of serotonergic 5HT1B and 5HT2 receptors in the male rat brain

Anabolic-androgenic steroids (AAS) are partly misused by males in order to become brave and intoxicated and these agents are highly associated with psychosis, disinhibition, aggression and acts of violence. Since such behavioral states have been related to an imbalanced serotonergic system and the involvement of the serotonergic 5HT(1B) and the 5HT(2) receptors, it was important to discern the impact of AAS on these receptors. The objective of our study was to investigate the effects of 2 weeks of treatment with the AAS nandrolone decanoate at three different doses (1, 5, 15 mg/kg/day) on the total specific binding of the radioligands [(125)I]-(+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) (5HT(2) receptors) by autoradiography. All doses caused a significant down-regulation of the 5HT(1B) receptor density in the hippocampal CA(1) and in the medial globus pallidus and a significant up-regulation of the 5HT(2) receptor density in the nucleus accumbens shell. Alterations in receptor density were also observed in the lateral globus pallidus, ventromedial hypothalamus, the amygdala and in the intermediate layers of various cortex regions. In conclusion, serotonergic 5HT(1B) or 5HT(2) receptors are likely to play important roles in mediating observed emotional states and behavioral changes among AAS abusers.

Alcohol-preferring AA rats show a derangement in their central melanocortin signalling system

The AA (Alko, Alcohol) rats are selectively bred for their preference of alcohol to water, contrasting to ANA rats that avoid alcohol. They also exhibit a lower growth rate compared to ANA rats, as well as differences in their response to substances affecting food intake. The melanocortin (MC) system is involved in the regulation of feeding behaviour and in mechanisms underlying drug addiction and tolerance. Recently, administration of an MC receptor agonist proved to reduce alcohol intake in AA rats. We predicted that the ratio of endogenous MC receptor agonists (proopiomelanocortin, POMC) and antagonists (agouti-related protein, AgRP) would differ from ANA rats, and that subsequent differences in MC receptor levels would be detectable. We used in situ hybridization to detect an increased ratio of POMC/AgRP mRNA in the arcuate nucleus (Arc) of AA rats. Receptor autoradiography indicated that MC3 receptor binding differed in the nucleus accumbens and several hypothalamic nuclei, possibly reflecting differences in MC peptide transmission in the AA rats. Our results support the claim that AA rats have a high ratio of POMC/AgRP expression, and that this observation is accompanied by differences in MC3 receptor levels.

Spectral gamma-ray signatures of cosmological dark matter annihilations

We propose a new signature for weakly interacting massive particle (WIMP) dark matter, a spectral feature in the diffuse extragalactic gamma-ray radiation. This feature, a sudden drop of the gamma-ray intensity at an energy corresponding to the WIMP mass, comes from the asymmetric distortion of the line due to WIMP annihilation into two gamma rays caused by the cosmological redshift. Unlike other proposed searches for a line signal, this method is not very sensitive to the exact dark matter density distribution in halos and subhalos.

The MC4 receptor mediates alpha-MSH induced release of nucleus accumbens dopamine

Strong evidence suggests a functional link between the melanocortin and dopamine systems. alpha-Melanocyte stimulating hormone (alpha-MSH) induced grooming behaviour, which can be blocked by dopamine receptor antagonists, is associated with increased dopaminergic transmission in the striatal regions. Whether this effect is mediated specifically by melanocortin (MC) receptors has not previously been established. Using in vivo microdialysis on anesthesized rats we have shown that alpha- MSH administered into the ventral tegmental area induced a significant increase in dopamine and DOPAC levels in the nucleus accumbens. This increase was completely blocked by pre-treatment with the MC4 receptor selective antagonist HS131, indicating that the effects of alpha-MSH on dopamine transmission may be mediated by the MC4 receptor.

Effects of neonatal handling on nociceptin/orphanin FQ and opioid peptide levels in female rats

Animals exposed to short periods of handling during the critical period of development, i.e., the first 21 days of life in rats, show attenuated neuroendocrine responses to stress in adult life. We have previously reported long-term changes in brain dynorphin (DYN) peptide levels in male Sprague-Dawley rats after neonatal handling. The purpose of this study was to investigate whether neonatal handling, 15-min individual separation from the mother during postnatal days 1-21, can induce long-term changes in DYNB, Met-enkephalin Arg(6)Phe(7) (MEAP) and nociceptin/orphanin FQ (N/OFQ) immunoreactive (ir) levels in female Sprague-Dawley rats. The peptides were measured in brain and pituitary gland 2 months after the handling procedure. The results reveal that handled (H) rats had increased ir levels of N/OFQ, DYNB and MEAP in the periaqueductal gray (PAG) as compared to nonhandled (NH) controls. Furthermore, H rats had decreased ir levels of DYNB in the frontal cortex and in the amygdala. In contrast to previous findings in male rats, DYNB levels were unaffected in areas related to the hypothalamo-pituitary-adrenal (HPA)-axis. The results indicate that a manipulation early in life can induce persistent neurochemical changes in the N/OFQ and opioid peptide system in female Sprague-Dawley rats.

Observation of high-energy neutrinos using Cerenkov detectors embedded deep in Antarctic ice

Neutrinos are elementary particles that carry no electric charge and have little mass. As they interact only weakly with other particles, they can penetrate enormous amounts of matter, and therefore have the potential to directly convey astrophysical information from the edge of the Universe and from deep inside the most cataclysmic high-energy regions. The neutrino's great penetrating power, however, also makes this particle difficult to detect. Underground detectors have observed low-energy neutrinos from the Sun and a nearby supernova, as well as neutrinos generated in the Earth's atmosphere. But the very low fluxes of high-energy neutrinos from cosmic sources can be observed only by much larger, expandable detectors in, for example, deep water or ice. Here we report the detection of upwardly propagating atmospheric neutrinos by the ice-based Antarctic muon and neutrino detector array (AMANDA). These results establish a technology with which to build a kilometre-scale neutrino observatory necessary for astrophysical observations.

The anabolic-androgenic steroid nandrolone decanoate affects the density of dopamine receptors in the male rat brain

In recent years a male group of anabolic-androgenic steroid misusers has been identified to share socio-demographic and personality related background factors with misusers of psychotropic substances, as well as being involved in habits of multiple drug use. The present study aimed to assess whether anabolic-androgenic steroids (AAS) would affect the density of the dopamine receptors in areas implicated in reward and behaviour in the male rat brain. The effects of 2 weeks of treatment with i.m. injections of nandrolone decanoate (15 mg/kg/day) on the expression of the D(1)-like and D(2)-like receptors were evaluated by autoradiography. Specific binding of D(1)-like receptors was significantly down regulated in the caudate putamen, the nucleus accumbens core and shell. D(2)-like receptor densities were down regulated in the nucleus accumbens shell, but up regulated in the caudate putamen, the nucleus accumbens core and the ventral tegmental area. These results are compatible with nandrolone induced neuroadaptive alterations in dopamine circuits associated with motor functions and behavioural paradigms known to be affected following AAS misuse.

Downregulation of melanocortin receptors in brain areas involved in food intake and reward mechanisms in obese (OLETF) rats

The melanocortin (MC)4 receptor is important for food intake and weight homeostasis as it mediates the orexigenic and anorexigenic effects of the MCs. OLETF (Otsuka-Long-Evans-Tokushima-Fatty) rats are a selective inbred strain of polygenic variant rats which overeat and develop obesity with elevated leptin levels. We investigated by autoradiography if the expression of MC receptors were altered in ovariectomized estradiol-replaced female OLETF rats compared to their controls (Long-Evans-Tokushima-Otsuka (LETO) rats). We found that OLETF rats show a reduction in total [125I]NDP-MSH MC receptor binding in the ventromedial hypothalamic nucleus, perhaps reflecting an increased release of MC peptides in this region. The levels of MC receptors in the arcuate nucleus and the paraventricular hypothalamic nucleus were not changed. Interestingly, the OLETF rats also showed reduced MC-receptor binding in areas such as the nucleus accumbens shell, and the ventral tegmental area, both of which are believed to be involved in reward systems. Similarities in the changes of MC receptor expression in obese animals and in animals treated with opiates may suggest a neurobiological link between food intake mediated through the MC receptors and reward.

Orthokinetic Aggregation in Two Dimensions of Monodisperse and Bidisperse Colloidal Systems

Orthokinetic aggregation of colloids trapped at the air-liquid interface was studied by direct imaging in a couette cell. This method allowed us to follow the temporal evolution of both the cluster-mass distribution and the cluster structure at a shear rate where Brownian aggregation is suppressed. The interactions between the monodisperse latex particles floating at the air-liquid interface were controlled either by varying the electrolyte concentration or by creating a bidisperse system through the addition of small particles. The results show that the clusters in all of the systems are characterized by a high fractal dimension, indicating that the clusters are rearranged and densified by the shear. Kinetic analysis suggests that aggregation of monodisperse systems mainly proceeds through homogeneous aggregation, i.e., large clusters sticking to other large clusters. The bidisperse system, finally, with a size ratio around 10, favored a more heterogeneous aggregation among small and large clusters throughout the aggregation process; a slightly lower fractal dimension was observed compared to the strongly aggregated monodisperse system. Copyright 1999 Academic Press.

Neonatal handling in rats induces long-term effects on dynorphin peptides

The effects of neonatal handling on the opioid dynorphin peptides in the brain and pituitary gland of Sprague-Dawley rats were investigated. Ten weeks after the neonatal handling, handled rats had higher tissue levels of dynorphin A and B in the hypothalamus, pituitary gland and striatum and slightly higher dynorphin B levels in the hippocampus, medulla oblongata and midbrain as compared with non-handled controls. The results indicate a persistent upregulation of the dynorphin system in certain brain areas after neonatal handling, which could contribute to the behavioural changes in these rats observed later in life. Observation in the open field and the elevated plus-maze tests confirmed behavioural effects of neonatal handling, i.e. showing that handled rats exhibit attenuated fearfulness in novel environments as compared with non-handled rats.

Dissolution Kinetics of Silicon Nitride in Aqueous Suspension

A general system of equations describing the dissolution of polydisperse solids having a porous particulate structure is set up and applied to study the hydrolysis and subsequent dissolution of silicon nitride powder in aqueous suspensions. The latter process has been found to follow a simple kinetic equation, c(t) = c(s)[1 - exp(-kt)], with the dissolution rate constant k = 2.3 x 10(-6) s(-1) (or 2.5 x 10(-11) mol m(-2) s(-1)) and the saturation concentration c(s) = 3.2 mmol dm(-3) at room temperature and pH 9. The role of diffusion is unimportant, so the concentration of soluble species in pore water changes almost simultaneously with their concentration in the surrounding solution. Copyright 1999 Academic Press.

Perikinetic Aggregation of Alkoxylated Silica Particles in Two Dimensions

Aggregation and cluster formation of a two-dimensional colloidal system consisting of 2-µm alkoxylated silica particles trapped at the air-toluene interface have been studied. This novel system allows particle interactions to be controlled by varying the length of the grafted alkyl chains; simple estimates suggest particle bond strengths of 15 and 30 kT for the octadecyl- and octyl-coated system, respectively. Video-enhanced microscopy and image analysis enabled a simultaneously study of kinetics and structure of the ensemble of clusters in situ. The octyl system displayed a DLCA-like structure, D(f) approximately 1.45, whereas the octadecyl system resulted in a more dense structure, D(f) approximately 1.55. The temporal evolution of the cluster-mass distribution displayed a transition point between regimes of slower and faster aggregation for both systems, which was interpreted as a transition from DLCA to convection-limited cluster aggregation (CLCA). Copyright 1999 Academic Press.

Viscoelastic Properties of Particle Gels

The effect of strength of attraction and volume fraction on the mechanical properties of alumina particle networks were investigated. Alumina particle gels were formed reversibly and in situ in the rheometer by cooling alumina particle suspensions with adsorbed poly(12-hydroxy stearic acid) suspended in a marginal solvent, hexanol. The collapse of the polymer layer with decreasing solvency (temperature) induces flocculation when the long-range van der Waals force overcomes the remaining steric repulsion. The gelation temperature depends on volume fraction. At the gel temperature, Tgel, the gel becomes predominantly elastic; at temperatures below Tgel, the elasticity increases with decreasing temperature. We find that the elastic modulus data, measured over a wide range of volume fraction (0.2 < &phi; < 0.425) and temperature (10-14 degreesC), follows: G = G0(&phi; - &phi;g)s. This scaling suggests the prefactor and exponent to be independent of temperature. We present some arguments for why subjecting a particle gel to a preshear procedure might result in an temperature-dependent prefactor. By invoking such an effect, we are able to rescale and collapse previously published moduli data on presheared suspensions according to the (&phi; - &phi;g) expression. Copyright 1999 Academic Press.

Evaluation of Surface Ionization Parameters from AFM Data

A new application of atomic force microscopy (AFM) for evaluation of surface ionization parameters on the basis of a charge-regulation model is demonstrated. Interactions between symmetrical silicon nitride and silica surfaces have been measured in aqueous electrolytic solutions at different pHs and separations from a few Debye lengths down to zero. The obtained experimental data are reported and interpreted on a quantitative level in the framework of Derjaguin's approximation; the computational procedure used for this purpose is outlined. Surface charge density, surface potential, and species concentrations are calculated as functions of pH and separation, unveiling the limits of applicability of classical constant-charge and constant-potential approximations. The integrity of the results on the charge properties of interacting surfaces is discussed in reference to electrokinetic and titration data, potential problems caused by the existence of non-DLVO forces and surface irregularities being highlighted. Copyright 1998 Academic Press.

Autoradiographic discrimination of melanocortin receptors indicates that the MC3 subtype dominates in the medial rat brain

In the present study, we developed an autoradiographic method to visualize the distribution of melanocortin (MC) receptors 3 and 4 in sagittal sections of the rat brain. The method takes advantage of the MC3 and MC4 receptor selective compounds, gamma1-MSH and HS014. First, we characterized the binding of gamma1-MSH, HS014 and the radioligand [125I]NDP-MSH to the rat MC3 and MC4 receptors expressed in COS cells. [125I]NDP-MSH was found to be non-selective, whereas gamma1-MSH showed a 40-fold preference for the rat MC3 receptor, and HS014 an over 300-fold preference to the rat MC4 receptor. Second, to discriminate between the MC3 and MC4 receptors in rat brain sections, the sections were incubated with [125I]NDP-MSH in the presence of graded concentrations of the MC3 selective ligand, gamma1-MSH, or the MC4 selective ligand, HS014. From the autoradiograms thus made, competition curves of gamma1-MSH and HS014 could be constructed for different regions of the rat brain. Our results indicate that in the nucleus accumbens shell, the medial preoptic area, and the ventromedial nucleus of the hypothalamus, there is a clear dominance of the MC3 receptor, whereas in the lateral septum and the olfactory tubercle, there seem to be present both MC3 and MC4 receptors, although the MC3 receptor may still be the dominating subtype. In the optic layer of the superior colliculus, our data indicate a more abundant expression of the MC4 receptor. In the ventral tegmental area, there might be an additional MSH-peptide binding site of unknown origin.

Optical properties of deep ice at the South Pole: absorption

We discuss recent measurements of the wavelength-dependent absorption coefficients in deep South Pole ice. The method uses transit-time distributions of pulses from a variable-frequency laser sent between emitters and receivers embedded in the ice. At depths of 800-1000 m scattering is dominated by residual air bubbles, whereas absorption occurs both in ice itself and in insoluble impurities. The absorption coefficient increases approximately exponentially with wavelength in the measured interval 410-610 nm. At the shortest wavelength our value is approximately a factor 20 below previous values obtained for laboratory ice and lake ice; with increasing wavelength the discrepancy with previous measurements decreases. At ~415 to ~500 nm the experimental uncertainties are small enough for us to resolve an extrinsic contribution to absorption in ice: submicrometer dust particles contribute by an amount that increases with depth and corresponds well with the expected increase seen near the Last Glacial Maximum in Vostok and Dome C ice cores. The laser pulse method allows remote mapping of gross structure in dust concentration as a function of depth in glacial ice.

Optical properties of deep ice at the South Pole: scattering

Recently, absorption and scattering at depths 800-1000 m in South Pole ice have been studied with transit-time distributions of pulses from a variable-frequency laser sent between emitters and receivers embedded in the ice. At 800-1000 m, scattering is independent of wavelength and the scattering centers are air bubbles of size ? wavelength. At 1500-2000 m it is predicted that all bubbles will have transformed into air-hydrate clathrate crystals and that scattering occurs primarily at dust grains, at liquid acids concentrated along three-crystal boundaries, and at salt grains. Scattering on decorated dislocations, at ice-ice boundaries, and at hydrate-ice boundaries will be of minor importance. Scattering from liquid acids in veins at three-crystal boundaries goes as ~lambda(-1) to ~lambda(-2) and should show essentially no depth dependence. Scattering from dust grains goes as ~lambda(-2) and should show peaks at depths of ~1050, ~1750, and ~2200 m in South Pole ice. If marine salt grains remain undissolved, they will scatter like insoluble dust grains. Refraction at ice-ice boundaries and at hydrate-ice boundaries is manifested by a multitude of small-angle scatters, independent of wavelength. The largest contribution to Rayleigh-like scattering is likely due to dislocations decorated discontinuously with impurities. Freshly grown laboratory ice exhibits a large Rayleigh-like scattering that we attribute to the much higher density of decorated dislocations than in glacial ice.

Diminution of preprosomatostatin-mRNA in cerebral cortex of the aged rat

The aim of the present study was to examine the effect of normal aging on somatostatin neurotransmission. Somatostatin gene expression was analysed in several regions of the cerebral cortex and hippocampus in 3, 7 and 21 month-old Sprague-Dawley rats using quantitative in situ hybridization with a 48mer oligodeoxynucleotide antisense probe. Furthermore the distribution of 125I-Tyr11 somatostatin receptor binding sites was studied using quantitative receptor autoradiography. The results demonstrated a significant reduction of preprosomatostatin-mRNA in the frontal cortex of the aged (21 month) group compared with the young (3 month) and the middle-aged (7 month) groups. The receptor binding densities of the aged (21 month) group tended to be lower, compared to the other groups although no significant region-specific changes were evident. These results indicate neurochemical changes in somatostatin-containing neurons in the frontal cortex during aging.

Somatostatinergic phenotype markers in the human neuroblastoma cell-line LA-N-2

We have characterized somatostatinergic phenotype markers of the human neuroblastoma, LA-N-2. A single mRNA-transcript (approximately 850bp) and two cellular somatostatin immunoreactivity forms, a high molecular weight form (M(r) 15,000) and a fragment corresponding to somatostatin-28 was found, while the somatostatin-14 peptide was absent. Saturation binding experiments demonstrated a single class of high-affinity somatostatin receptors with Kd and Bmax of 0.27 +/- 0.03 nM and 45 +/- 1 fmol/mg protein. Partial G-protein uncoupling (30%) was demonstrated, using GTP gamma S, with an affinity of 9.7 nM. The LA-N-2 cell line, previously shown to be cholinergic, may serve as a simplified system to elucidate heterologous neurotransmittor interactions. Such studies are of interest since dysfunctions of the cholinergic basal forebrain neurons and somatostatin immunoreactive interneurons have been consistently observed in Alzheimer's disease.

Influence of place learning on somatostatin levels in the rat brain following environmental deprivation

We have previously reported increased somatostatin levels in the cerebral cortex of rats housed in impoverished environment and subsequently subjected to a behavioural testing procedure, consisting of open-field exposure and spatial learning. The aim of the present study was to evaluate the degree of neurochemical specificity of the activation of somatostatin neurotransmission and to examine whether the altered levels were due to learning stimulation. Adult rats, previously housed individually for 30 days, were exposed to repeated sessions of a spatial learning task (2 days or 14 days) or repeated sessions of free swimming (14 days). The training sessions of the 14 day group consisted in recurrently changed position of the platform in a learning-set paradigm. Our data showed increased somatostatin immunoreactivity, and unchanged substance P immunoreactivity in the posterior part of the cerebral cortex. However, somatostatin levels increased to a similar extent following 14 days of repeated spatial learning sessions as free swimming sessions. We conclude that the activity of the cortical somatostatin system appears to be sensitive to environmentally induced sensorimotor stimulation in general, rather than learning per se. Thus, external stimulation of early clinical dementia patients with preserved sensorimotor receptivity, in an attempt to restore cognitive function, might be associated with altered somatostatin levels.