Function Of CB Research Articles

Reactions of the different breeding season corns as a function of injury of cotton bollworm (Helicoverpa armigeraHbn.)

The aim of present investigations was the increasing of knowledge of the cotton bollworm’s (Helicoverpa armigera Hbn.) (CB) damages in the different breeding season corns. The damage examinations were made in a 29.2 hectares acreage between Igal and Kazsok villages (Somogy county) on the basis of the flight observation at the end of August 2008. We examined the measure of damages and yield losses based on the collected ears belonging to different breeding season corns (FAO 200-299, FAO 300-399, FAO 400-499, FAO 500-599). The relationship between the breeding season and the damages was examined by variance analysis (one-way anova). The collected samples were examined in analytic laboratory in order to calculate the quantitative alteration of the fundamental in-kernel air dry content values (raw protein, raw fat, starch). Our results proved the significant increasing of damage percentages (FAO 200-299: 8.66%; FAO 500-599: 15.33%), surface damages (cm 2 ) (P = 0.026) and the calculated weight loss of damaged ears (P=0.014) parallel with the increasing of the breeding season length. We confirmed the “forced maturing” in the case of the earlier hybrids in the consequence of the damage. We recorded a decreasing percentage (correlate to the draw matter) of the starch and the raw fat (average decreasing: starch: 1.72; raw fat: 0.26) as well as the increasing starch loss per one hectare, agreeing with the breeding season length increase (starch loss/one hectare: FAO 200-299: 1.54%; FAO 500-599: 2.72%). We observed the quantitative increasing of the raw protein as a function of CB’s damage too, which can be explained by a physiological response to the biotic stress.

Synergistic immunomopharmacological effects of N-alkylamides in Echinacea purpurea herbal extracts

Echinacea purpurea extracts are used in the production of standardized herbal medicines for the prevention and treatment of upper respiratory infections. Unsaturated N-alkylamide lipids, the main constituent of E. purpurea and E. angustifolia preparations capable of activating the cannabinoid receptor type-2 (CB 2) have been suggested to play a role as potential anti-inflammatory and immune-modulatory principles. Here we show that ethanolic E. purpurea radix and herba extracts produce synergistic pharmacological effects on the endocannabinoid system in vitro. Superadditive action of N-alkylamide combinations was seen at the level of intracellular calcium release as a function of CB 2 receptor activation. Likewise, synergism of the radix and herba tinctures was observed in experiments measuring LPS-stimulated cytokine expression from human PBMCs. While the expression of the anti-inflammatory cytokine IL-10 was significantly superstimulated, the expression of the pro-inflammatory TNF-α protein was inhibited more strongly upon combination of the extracts. We show that N-alkylamides act in concert and exert pleiotropic effects modulating the endocannabinoid system by simultaneously targeting the CB 2 receptor, endocannabinoid transport and degradation.

Recessive congenital methaemoglobinaemia: cytochrome b5 reductase deficiency

Some 60 years ago, Quentin Gibson reported the first hereditary disorder involving an enzyme when he deduced that familial methaemoglobinaemia was caused by an enzymatic lesion associated with the glycolysis pathway in red blood cells. This disorder, now known as recessive congenital methaemoglobinaemia (RCM), is caused by NADH-cytochrome b5 reductase (cb(5)r) deficiency. Two distinct clinical forms, types I and II, have been recognized, both characterized by cyanosis from birth. In type II, the cyanosis is accompanied by neurological impairment and reduced life expectancy. Cytochrome b(5) reductase is composed of one FAD and one NADH binding domain linked by a hinge region. It is encoded by the CYB5R3 (previously known as DIA1) gene and more than 40 mutations have been described, some of which are common to both types of RCM. Mutations associated with type II tend to cause incorrect splicing, disruption of the active site or truncation of the protein. At present the description of the sequence variants of cb(5)r in the literature is confusing, due to the use of two conventions which differ by one codon position. Herein we propose a new system for nomenclature of cb(5)r based on recommendations of the Human Genome Variation Society. The development of a heterologous expression system has allowed the impact of naturally occurring variants of cb(5)r to be assessed and has provided insight into the function of cb(5)r.

Dysregulation of the endogenous cannabinoid system in adult rats prenatally treated with the cannabinoid agonist WIN 55,212-2

Cannabis is widely abused by women at reproductive age and during pregnancy. Animal studies showed a particular vulnerability of the developing brain to prenatal chronic cannabinoid administration. We determined whether prenatal exposure to WIN 55,212-2, a potent cannabinoid receptor agonist, affected (1) density, affinity and/or function of cannabinoid CB(1) receptors, (2) endogenous levels of the endocannabinoid anandamide, (3) activities of the major anandamide synthesising and hydrolysing enzymes, N-acyl-phosphatidylethanolamine-specific phospholipase D (NAPE-PLD) and fatty acid amide hydrolase (FAAH), respectively, in brain areas of adult male offspring rats. Furthermore, the effect of prenatal WIN 55,212-2 on spontaneous motility was analyzed. Pregnant rats were treated daily with WIN 55,212-2 (0.5 mg/kg, gestation day 5-20) or vehicle. [(3)H]CP 55,940 and WIN 55,212-2-stimulated [(35)S] GTPgammaS binding were carried out in cerebellum, cerebral cortex, hippocampus, striatum and limbic areas of male adult offspring. Levels of anandamide, FAAH and NAPE-PLD activity were also determined. EC(50) values for WIN 55,212-2-stimulated [(35)S]GTPgammaS binding were significantly different in hippocampus (-26%) and striatum (+27%) in WIN 55,212-2-treated rats. Cannabinoid CB(1) receptor density and affinity were not affected in any analyzed region. In the striatum, increased anandamide levels were associated with reduced FAAH and enhanced NAPE-PLD activities. Opposite changes in anandamide levels and enzymatic activities were detected in limbic areas of WIN 55,212-2-treated rats. Ambulatory activity between WIN 55,212-2- and vehicle-treated adult offspring did not vary. Our results show that prenatal exposure to cannabinoid agonist induces a long-term alteration of endocannabinoid system in brain areas involved in learning-memory, motor activity and emotional behavior.

Functionalized Cucurbiturils and Their Applications

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Functionalized cucurbiturils and their applications

Cucurbit[n]uril (CB[n], n = 5-10), a new family of molecular hosts comprising n glycoluril units, have gained much attention in the new millennium for their exceptional molecular recognition ability. The CB homologues have brought dynamism to CB chemistry, as witnessed by the heightened interest in the field for the last several years. Compared to the chemistry of cyclodextrins and calixarenes, however, that of CB[n] has developed slowly until recently, which may be attributed mainly to their poor solubility in common solvents, and inability to functionalize these molecules. The direct functionalization method of CB[n] propelled CB chemistry to a new height as this new method not only solved the solubility problem but also opened up the gateway to the generation of tailor-made CB[n] derivatives. The functionalization of CB[n] led us to investigate numerous applications including artificial ion channels, vesicles, stationary phases in chromatography, ISEs, polymers, nanomaterials, and many others. This tutorial review describes the recent advances and challenges in the functionalization of CBs along with the applications of functionalized CBs.

Subchronic haloperidol increases CB1 receptor binding and G protein coupling in discrete regions of the basal ganglia

The present study was designed to test whether chronic neuroleptic treatment, which is known to alter both expression and density of dopamine D(2) receptors in striatal regions, has effects upon function and binding level of the cannabinoid CB(1) receptor in the basal ganglia by using receptor autoradiography. As predicted, subchronic haloperidol treatment resulted in increased binding of (3)H-raclopride and quinpirole-induced guanosine 5'-O-(gamma-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) in the striatum when compared to that measured in control animals. This increased D(2) receptor binding and function after 3 days washout was normalized after a 2-week washout period. Effect of haloperidol treatment was studied for CB(1) receptor binding and CP55,940-stimulated [(35)S]GTPgammaS in the striatum, globus pallidus, and substantia nigra. (3)[H]CP55,940 binding levels were found in rank order from highest to lowest in substantia nigra > globus pallidus > striatum. Furthermore, subchronic haloperidol treatment resulted in elevated binding levels of (3)[H]CP55,940 in the striatum and the substantia nigra and CB(1) receptor-stimulated [(35)S]GTPgammaS bindings in the substantia nigra after 3 days washout. These increased binding levels were normalized at 1-4 weeks after termination of haloperidol treatment. Haloperidol treatment had no significant effect on CB(1) receptor or [(35)S]GTPgammaS binding levels in globus pallidus. The results help to elucidate the underlying biochemical mechanism of CB(1) receptor supersensitivity after haloperidol treatment.

Developmental expression of cannabinoid receptors in the chick retinotectal system

The cannabinoid system has been suggested to participate in processes such as antinociception, cognition, motor control, and, more recently, development of the nervous system. This study describes the expression of the CB 1 cannabinoid receptor in the developing chick retina and optic tectum by means of conventional immunoperoxidase protocols. CB 1 immunoreactivity was initially detected around the embryonic day 4 (E4) in both the retina and tectum. In the retina, CB 1 immunoreactivity was first observed in presumptive ganglion cells and, subsequently, in the inner plexiform layer and two populations of neurons of the inner nuclear layer. The post-hatched chick exhibited a pattern of staining that included four sublayers of the inner plexiform layer, a few stained cells in the ganglion cell layer, and labeled neurons both in the inner and central parts of the inner nuclear layer. The latter two types of neurons appear to be amacrine and bipolar cells, respectively. In the tectum, CB 1 first appeared in its most superficial zone and later in several tectal laminae, including a white matter layer (stratum album centrale; Cajal's layer 14). There was a remarkable and transient increase of labeling at E10, followed by a continuous reduction of staining until E18. In the post-hatched chick, tectal staining was mostly confined to layers 2–3 and 5–6. Stained perikarya were seldom observed in the tectum at any stage. These data are in agreement with a possible developmental function of CB 1, as it is expressed several days before synaptogenesis ensues and exhibits transient expression in the optic tectum.

NMR Structural Comparison of the Cytoplasmic Juxtamembrane Domains of G-protein-coupled CB1 and CB2 Receptors in Membrane Mimetic Dodecylphosphocholine Micelles

The fourth cytoplasmic domain, the so-called C-terminal juxtamembrane segment or helix VIII, has been identified in numerous G-protein-coupled receptors and exhibits unique functional characteristics. Efforts have been devoted to studying the juxtamembrane segment in order to understand the biological importance of the segment in G-protein activation of the cannabinoid CB1 and CB2 receptors. Recent biochemical data revealed that the CB1 C-terminal juxtamembrane peptide fragment CB1-(401-417) can directly activate the G-protein and also showed that the specificity of the signal transduction activation by the C-terminal juxtamembrane region is unique to the CB1 receptor but not to the CB2 receptor (Mukhopadhyay, S., and Howlett, A. C. (2001) Eur. J. Biochem. 268, 499-505). However, there is experimental work, not yet reported, on the conformational analyses and structural comparison between the respective helix VIII segments of the two receptors. In the present study, we have examined the conformational specificities of the cytoplasmic helical domains for both cannabinoid receptors. Three-dimensional structural features of two synthetic CB1 and CB2 peptides, CB1I397-G418 and CB2I298-K319, respectively, in membrane mimetic DPC micelles were studied using a combined high resolution NMR and computer modeling approach. Comparisons of the NMR-determined structures of the two peptides as well as their correspondent mutant peptides revealed their conformational properties and salt bridge dissimilarity, which might help us to understand the different structural roles of the fourth cytoplasmic helices in the function and regulation of CB1 and CB2 receptors.

Cannabinoids inhibit striatonigral GABAergic neurotransmission in the mouse

The substantia nigra pars reticulata (SNR) belongs to the brain regions with the highest density of CB 1 cannabinoid receptors. Anatomical studies indicate that the great majority of CB 1 receptors in the SNR are localized on terminals of GABAergic axons arriving from the caudate-putamen (striatonigral axons). The aim of the present experiments was to clarify the role of CB 1 receptors on terminals of striatonigral axons. Oblique sagittal slices, including the caudate-putamen and the substantia nigra, were prepared from brains of young mice. Electrical stimulation in the caudate-putamen elicited GABAergic inhibitory postsynaptic currents (IPSCs) in the SNR, which were studied by patch-clamp techniques. The long latency of IPSCs (14±1 ms) suggests that striatonigral axons were indeed activated within the caudate-putamen. The synthetic CB 1/CB 2 cannabinoid receptor agonist WIN55212-2 (R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazin-yl]-(1-naphthalenyl)methanone mesylate; 10 −5 M) decreased the amplitude of IPSCs by 93±1%. CP55940 ((−)- cis-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]- trans-4-(3-hydroxypropyl)cyclohexanol; 10 −5 M), another CB 1/CB 2 receptor agonist, also reduced IPSC amplitude, by 76±4%. The CB 1 cannabinoid receptor antagonist SR141716A ( N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-3-pyrazole-carboxamide; 10 −6 M) prevented the inhibition produced by WIN55212-2 (10 −5 M). Depolarization of SNR neurons led to suppression of IPSCs; this suppression was prevented by SR141716A (10 −6 M). Three observations indicate that the agonists inhibited neurotransmission presynaptically. (1) CP55940 (10 −5 M) enhanced the ratio of amplitudes of two IPSCs which were elicited by two electrical stimuli 100 ms apart (paired pulses). (2) WIN55212-2 (10 −5 M) did not change the amplitude of miniature IPSCs recorded in the presence of tetrodotoxin. (3) WIN55212-2 (10 −5 M) also had no effect on currents elicited in SNR neurons by ejection of the GABA A receptor agonist muscimol from a pipet. In summary, we have established a method which allows selective examination of GABAergic neurotransmission between striatonigral axons and SNR neurons. Using this method, the function of CB 1 cannabinoid receptors on terminals of striatonigral axons was unequivocally clarified. Activation of these receptors causes strong presynaptic inhibition of GABAergic neurotransmission between striatonigral axons and SNR neurons. This effect may be one explanation of the catalepsy observed in animals after cannabinoid administration. Endocannabinoids released from SNR neurons can modulate striatonigral neurotransmission by inhibiting GABA release from terminals of striatonigral axons.

Cajal body finds its function

The Cajal body (CB, formerly coiled body) is a prominent nuclear structure, yet its function remains obscure. Now, Xavier Darzacq, Tamas Kiss (CNRS, Universite Paul Sabatier, Toulouse, France), and colleagues speculate that the CB is where small nuclear RNAs go for modification. Figure Novel guide RNAs localize to CBs. Last year, Kiss's team identified a small guide RNA, U85, that directs both 2'-O- methylation and pseudouridylation of the spliceosomal component U5 snRNA. This year, they've identified six more RNAs, U87-U92, dubbed small Cajal body–specific RNAs, or scaRNAs. The new scaRNAs resemble U85 in structure, and they contain sequences complimentary to pol II–transcribed UsnRNAs, suggesting that the scaRNAs may be guides for posttranscriptional modification of the UsnRNAs. The scaRNAs are immunoprecipitated by antibodies against fibrillarin and GAR, proteins that are likely to be involved in these modification reactions. Most important, says Kiss, is the fact that these RNAs localize entirely to the CB, even when heavily overexpressed, making them unique in the world of CB biology. Previously, the best marker for the structure was p80-coilin, but only a fraction is in the CB—the rest floats free in the nucleoplasm. This implies that the scaRNAs are functioning in the CB, not just being stored there. Add in the fact that both snRNAs and snoRNAs seem to transit through the CB, and Kiss thinks he's found the elusive CB function. “This strongly, strongly indicates that at least one function of Cajal bodies is the posttranscriptional modification of the snRNAs,” he says. ▪ Reference: Darzacq, X., et al. 2002. EMBO J. 21:2746–2756. [PubMed]

Ultra-highly doped Si1−xGex(001):B gas-source molecular-beam epitaxy: Boron surface segregation and its effect on film growth kinetics

Si 1−x Ge x (001) layers doped with B concentrations CB between 2×1016 and 2×1021 cm−3 were grown on Si(001)2×1 at Ts=500–700 °C by gas-source molecular-beam epitaxy (GS-MBE) from Si2H6, Ge2H6, and B2H6. Secondary-ion mass spectrometry measurements of modulation-doped structures demonstrate that B doping has no effect on the Ge incorporation probability. Steady-state B and Ge surface coverages (θB and θGe) were determined as a function of CB using in situ isotopically tagged temperature-programmed desorption. Results for Si0.82Ge0.18 layers grown at Ts=500 °C show that θGe remains constant at 0.63 ML while the bulk B concentration increases linearly up to 4.6×1020 cm−3, corresponding to saturation coverage at θB,sat=0.5 ML, with the incident precursor flux ratio ξ=JB2H6/(JSi2H6+JGe2H6). B is incorporated into substitutional electrically active sites over this entire concentration range. At higher B concentrations, CB increases faster than ξ and there is a large decrease in the activated fraction of incorporated B. The B segregation enthalpy during Si0.82Ge0.18(001) growth is −0.42 eV, compared to −0.53 and −0.64 eV during Si(001):B and Ge(001):B GS-MBE, respectively. Measured segregation ratios rB=θB/xB, where xB is the bulk B fraction, range from 15 to 500 with a temperature dependence which is consistent with equilibrium segregation. Film deposition rates RSiGe(CB) decrease by up to a factor of 2 with increasing CB⩾5×1019 cm−3, due primarily to a B-segregation-induced decrease in the dangling bond density. The above results were used to develop a robust model for predicting the steady-state H coverage θH, θB, θGe, and RSiGe as a function of ξ and Ts.

On the adsorbed mass of polymers on surfaces

It is shown that for ideal polymers interacting with a surface via the pseudopotential of a delta function, the number of contacts between the monomer units and the surface as a function of concentration cb is a dependence of the form cb/(1-cb). The architecture of the polymer, the degree of polymerization, the interaction energy between a monomer unit and the surface, the area of the surface and the monomer length are embodied in the parameters and. The above dependence of the adsorbed mass of a polymer on the concentration is confirmed by the experimental results of Takahashi and his collaborators. For linear polystyrene of molecular weight 134 105,interacting with a chrome plate, the parameters and are, respectively, about equal to (89938/273)-6 m and (-19300/273)m3 kg-1.

Ge(001):B gas-source molecular beam epitaxy: B surface segregation, hydrogen desorption, and film growth kinetics

Ultrahigh B-doped Ge(001) layers, with concentrations CB up to 8×1021 cm−3, were grown by gas-source molecular beam epitaxy from Ge2H6 and B2H6 at temperatures Ts=325 °C (in the surface-reaction-limited regime) and 600 °C (in the flux-limited regime). The samples were quenched, D site exchanged for H, and D2 temperature-programed desorption (TPD) used to determine B coverages θB as a function of CB and Ts by comparison with B-adsorbed Ge(001) reference samples with known θB values. During Ge(001):B film growth, strong surface B segregation to the second layer was observed with surface-to-bulk B concentration ratios ranging up to 6000. The TPD spectra exhibited α2 and α1 peaks associated with dideuteride and monodeuteride desorption as well as lower-temperature B-induced α2* and α1* peaks associated with deuterium desorption from Ge* surface atoms with B backbonds. Increasing θB expanded the area under α2* and α1* at the expense of α2 and α1 and decreased the total D coverage θD. The TPD results were used to determine the B segregation enthalpy, −0.64 eV, and to explain and model the effects of high B coverages on Ge(001) growth kinetics. At Ts=325 °C, where B segregation is kinetically hindered, film deposition rates RGe are not a strong function of CB, exhibiting only a small decrease at CB≳5×1018 cm−3. However, at Ts=600 °C, RGe decreases by up to 40% with increasing CB≳1×1018 cm−3. This is due primarily to the combination of B-induced Ge dimer vacancies and the deactivation of surface dangling bonds caused by charge transfer to Ge–B backbonds. Calculated RGe(CB,Ts) curves, based upon equilibrium segregation, exhibit very good agreement with deposition rate data at Ts=600 °C and overestimate the effect of B on RGe at 325 °C.

Si(001):B gas-source molecular-beam epitaxy: Boron surface segregation and its effect on film growth kinetics

B-doped Si(001) films, with concentrations CB up to 1.7×1022 cm−3, were grown by gas-source molecular-beam epitaxy from Si2H6 and B2H6 at Ts=500–800 °C. D2 temperature-programed desorption (TPD) spectra were then used to determine B coverages θB as a function of CB and Ts. In these measurements, as-deposited films were flash heated to desorb surface hydrogen, cooled, and exposed to atomic deuterium until saturation coverage. Strong B surface segregation was observed with surface-to-bulk B concentration ratios ranging up to 1200. TPD spectra exhibited β2 and β1 peaks associated with dideuteride and monodeuteride desorption as well as lower-temperature B-induced peaks β2* and β1*. Increasing θB increased the area under β2* and β1* at the expense of β2 and β1 and decreased the total D coverage θD. The TPD results were used to determine the B segregation enthalpy, −0.53 eV, and to explain and model the effects of high B coverages on Si(001) growth kinetics. Film deposition rates R increase by ⩾50% with increasing CB>̃1×1019 cm−3 at Ts⩽550 °C, due primarily to increased H desorption rates from B-backbonded Si adatoms, and decrease by corresponding amounts at Ts⩾600 °C due to decreased adsorption site densities. At Ts⩾700 °C, high B coverages also induce {113} facetting.

Critical Bandwidth in Other Species

The hypothesis was offered some years ago (Greenwood, 1961) that critical bandwidth in man was an exponential function of distance on the basilar membrane. Integration of the function yielded directly a frequency-position curve fitting Békésy's data. Thus critical bandwidth in man was apparently proportional, and if distance was scaled in millimeters, numerically equal, to the derivative of the frequency-position function. It was unlikely, however, that critical bandwidth would correspond to the same distance in species with cochleas of different sizes. Scale relations between frequency-position functions of a few species, and between displacement envelopes in four species (Greenwood, 1962), suggested that critical bandwidth might correspond to scale-related distances, implying changes among species in the constant of proportionality to the derivative of the frequency-position function. Based on a 1-mm distance in man, some unpublished calculations of scaled distances were made for other species. Subsequently, a revised CB function was suggested for man (Greenwood, 1971) in which critical bandwidth corresponds to 1.25 mm. Based on this distance, scale-related functions are suggested for cat, squirrel monkey, and guinea pig in which critical bandwidth corresponds, respectively, to distances of about 0.78, 0.71 +, and 0.61 mm. These values may be related to distance measures derived from physical and physiological data in those species.

X-ray emission spectra of VCx, NbCx, TaCx, and ZrC

A quantitative LEED study of the Pt25Co75(111) surface (in the substitutionally disordered state) shows weak relaxations of interlayer spacings (Δd12/dbulk, Δd23/dbulk, Δd34/dbulk) = (000-1.9, −1.4, 3.6)%, no st but a significant oscillatory composition profile (C1, C2, C3) = (46, 3, 37) at% Pt. This behaviour is very close to the ge observed for PtNi(111) surfaces as a function of the bulk concentration Cb and in good agreement with the predictions of the tight binding Ising model of Treglia, Legrand and Ducastelle and of the embedded atom method results of Lundberg.

PROPRIOCEPTION BY THE COXO-BASAL CHORDOTONAL ORGAN, CB, IN LEGS OF THE CRAB, CARCINUS MAENAS.

ABSTRACT The chordotonal organ, CB, spanning the coxo-basal joint in walking legs of the crab, not being attached to a muscle tendon like the receptors of the more distal joints, is stretched during extension of the joint (i.e. limb depression) and relaxes during flexion (elevation). Afferent impulses have been recorded extracellularly from whole sensory nerves of CB, and from fibres isolated from it: (a) during passive movement of the coxo-basal joint, with CB in situ in a preparation containing no other joints, and (b) during stretching and releasing of the excised receptor strand. Unidirectional movement fibres and unidirectional position fibres for both directions were recorded. Thus, of the afferents responding primarily during movement, with a constant frequency for steady movement over the whole joint arc, some responded only during extension (or stretch of receptor), others only during flexion (release). Similarly, distinct fibres responded tonically in the extended positions of the joint (stretched), and others in the flexed (relaxed) positions. Fibres intermediate between true movement and true position fibres, and phasic movement—or ‘acceleration’— fibres, were also observed. Since the scolopidia of CB are isodynal, with only ciliary-type distal processes (Whitear, 1962), the simple hypothesis that the ciliary cell responds solely to relaxation of the receptor strand—and the paraciliary cell to stretch—is now untenable. Alternative hypotheses on the mechanism of activation of crab chordotonal organs, and on the function of CB in the intact animal, are discussed.