Anomalous magnetic field dependence of the thermodynamic transition line in the isotropic superconductor (K,Ba)BiO3

Thermodynamic (specific heat, reversible magnetization, tunneling spectroscopy) and transport measurements have been performed on high quality (K,Ba)BiO3 single crystals. The temperature dependence of the magnetic field H(C(p)) corresponding to the onset of the specific heat anomaly presents a clear positive curvature. H(C(p)) is significantly smaller than the field H(Delta) for which the superconducting gap vanishes but is closely related to the irreversibility line deduced from transport data. Moreover, the temperature dependence of the reversible magnetization presents a strong deviation from the Ginzburg-Landau theory emphasizing the peculiar nature of the superconducting transition in this material.

IMPAN cells: a pancreatic model for differentiation into endocrine cells

It is currently believed that pancreatic progenitor or stem cells exist in the ductal cell population and that these cells have the ability to be grown and differentiated into endocrine cells for the treatment of diabetes. In this study, we have examined this potential in IMPAN (Immortalized Pancreatic) cells. These cells are derived from the adult H-2K(b)-tsA58 transgenic mouse. We observed an increased mRNA expression of insulin, proendocrine gene neurogenin 3, and beta-cell transcription factor Pdx1 when the cells were grown on bovine collagen I gels. The induction profile of these three genes was similar under the tested conditions. No glucagon or other endocrine-specific transcription factors were detectable. Application of GIP, GLP-1 derivative NN2211, and activin-A/betacellulin to IMPAN cells in normal culture did not lead to endocrine differentiation. In conclusion, it appears that the ability of IMPAN cells to mature to endocrine cells is limited.

Sleep and the cholinergic rem sleep induction test in patients with primary alcoholism

Sleep disturbances of alcoholics while actively drinking and at the beginning of, and during, abstinence were frequently reported. Recently, Gillin et al. (1994) showed that a high "REM sleep pressure" at the time of admission to a 1-month inpatient alcohol treatment program predicted the relapse in nondepressed patients with primary alcoholism at 3 months following hospital discharge. We investigated 24 patients with primary alcoholism after 2-3 weeks abstinence in the sleep laboratory; in 15 of these patients the cholinergic REM sleep induction test (CRIT) with 10 mg galanthamine was performed additionally. In comparison with an age- and sex-matched healthy control group, patients had a heightened "REM sleep pressure" including shortened REM latency and increased REM density. A decrease of serotonergic neurotransmission is proposed as being the neurochemical mechanism to explain the results in alcoholic subjects. Follow-up investigations will clarify whether the sleep abnormalities in alcoholism are state- or trait-markers and whether they are suitable to predict the relapse risk.

Evidence for diverging barriers in the disordered vortex solid in the (K,Ba)BiO(3) superconducting oxide

Vortex dynamics has been investigated in the cubic (K,Ba)BiO (3) superconductor using ac susceptibility measurements on a large frequency range (0.03 Hz<omega<60 kHz). Power law diverging barriers have been obtained on both sides of the order-disorder transition line. The mu exponent remains close to 5/2 (elastic creep value) in some part of the disordered phase and finally decreases at high temperature and/or high field, in good agreement with the recent plastic collective creep theory [J. Kierfeld, H. Nordborg, and V. M. Vinokur, Phys. Rev. Lett., 85, 4948 (2000)].

A Bragg glass phase in the vortex lattice of a type II superconductor

Although crystals are usually quite stable, they are sensitive to a disordered environment: even an infinitesimal amount of impurities can lead to the destruction of crystalline order. The resulting state of matter has been a long-standing puzzle. Until recently it was believed to be an amorphous state in which the crystal would break into 'crystallites'. But a different theory predicts the existence of a novel phase of matter: the so-called Bragg glass, which is a glass and yet nearly as ordered as a perfect crystal. The 'lattice' of vortices that contain magnetic flux in type II superconductors provide a good system to investigate these ideas. Here we show that neutron-diffraction data of the vortex lattice provides unambiguous evidence for a weak, power-law decay of the crystalline order characteristic of a Bragg glass. The theory also predicts accurately the electrical transport properties of superconductors; it naturally explains the observed phase transitions and the dramatic jumps in the critical current associated with the melting of the Bragg glass. Moreover, the model explains experiments as diverse as X-ray scattering in disordered liquid crystals and the conductivity of electronic crystals.

Evidence for two superconducting energy gaps in MgB(2) by point-contact spectroscopy

Experimental support is found for the multiband model of the superconductivity in the recently discovered system MgB(2) with the transition temperature T(c) = 39 K. By means of Andreev reflection, evidence is obtained for two distinct superconducting energy gaps. The sizes of the two gaps ( Delta(S) = 2.8 meV and Delta(L) = 7 meV) are, respectively, smaller and larger than the expected weak coupling value. Because of the temperature smearing of the spectra the two gaps are hardly distinguishable at elevated temperatures, but when a magnetic field is applied the presence of two gaps can be demonstrated close to the bulk T(c) in the raw data.

Allelic distribution of HLA-B*5 in HLA-B5-positive Israeli patients with Behçet's disease

In order to investigate the sub-typing of the B5 antigen in Israeli (Jewish and Arabic) patients with Behçet's disease (BD) allele-specific genotyping of B51 and B52 alleles was performed in Israeli BD patients and healthy controls. Among the HLA-B51-positive BD patients, B*5101 was found to be the predominant allele, identified in 62% of all BD patients and 78% of Jewish BD patients. HLA-B*5101 was also the predominant allele in HLA-B51-positive healthy controls. HLA-B*5108 and B*5104 alleles were identified in 23% and 15% of B51-positive BD patients, respectively. The HLA-B*5201 allele was identified in all HLA-B52-positive patients and controls. Our study suggests that both HLA-B*5101 and HLA-B*5201 are the dominant alleles of HLA-B5 in Israeli BD patients.

Wing disc development in the fly: the early stages

The establishment of the wing anlage in Drosophila is dependent on the presence of two organizing centers located at the boundaries of the dorsoventral and anteroposterior compartments. How these boundaries are defined was not understood until recently. Furthermore, nothing was known about how the hinge region of the wing is defined. Recent data have now started to provide some insight in the molecular processes required for the definition of the major boundaries and subdivision of the wing anlage into the hinge and blade region.

Characterization of murine immunoglobulin G antibodies against human amyloid-beta1-42

It has been demonstrated that immunization of transgenic mouse models of Alzheimer's disease (AD) with amyloid-beta1-42 peptide (Abeta1-42) results in amelioration of AD-like pathology, including reduced soluble and deposited beta-amyloid and decreased cognitive impairment. Based on the proposed importance of immunoglobulin G (IgG) anti-Abeta antibodies (Abs) in these effects, we sought to characterize these Abs in splenocytes from mice immunized with Abeta1-42. Data show that a more aggregated preparation of Abeta1-42 gives a robust IgG anti-Abeta Ab response, while these Abs are almost undetectable when a less aggregated preparation of Abeta1-42 is used as the immunogen. Importantly, IgG anti-Abeta Ab production is detected after just 12 weeks of Abeta1-42 treatment. Analysis of anti-Abeta Ab IgG isotypes reveals that the majority of these Abs are IgG1, with significantly fewer Abs of the IgG2a or IgG2b isotypes (IgG1>IgG2a>IgG2b), suggesting a T lymphocyte helper type II response after Abeta1-42 immunization. To determine the epitope of Abeta recognized by IgG anti-Abeta Abs, intact Abeta and Abeta peptide fragments were analyzed for their ability to bind these Abs. Data show that these Abs specifically recognize an amino-terminal epitope of Abeta between amino acids one and twelve, with higher affinity for a more soluble preparation of Abeta1-42. These data further indicate the immunogenic potential of Abeta1-42 and offer insight into the nature of the IgG anti-Abeta Ab response.

Role of cytokine gene polymorphism in hepatitis C recurrence and allograft rejection among liver transplant recipients

BACKGROUND

Cytokines play a key role in the regulation of immune responses. The maximal capacity of cytokine production varies between individuals and was shown to correlate with polymorphism in cytokine gene promoters. The objective of this study was to analyze the role of cytokine allelic variations in susceptibility to early graft rejection episodes and recurrence of hepatitis C infection in liver transplant (LTx) recipients.

METHODS

The genetic profile of five cytokines was studied in 68 LTx recipients and 49 controls using polymerase chain reaction sequence specific primers. All individuals were genotyped as high or low producers of TNF-alpha and IL-6 and high, intermediate, or low producers of transforming growth factor beta (TGF-beta), interferon gamma (IFN-gamma), and interleukin 10 (IL-10) based on single nucleotide substitutions.

RESULTS

No statistically significant differences were observed between patients with or without early rejection episodes. A significant proportion of patients more prone to rejection were genotyped as having a low production profile of IL-10 compared with the control population (P=0.04). These data are in accordance with reports regarding other solid-organ transplant recipients. Patients with no recurrence of hepatitis C had the inherent ability to produce higher TGF-beta levels than did patients with recurrent disease (P=0.042). Among nonrecurrent patients, the percentage of genetically low IL-10 producers was higher than among recurrent patients (P=0.07). Furthermore, a genetic tendency to produce higher levels of IFN-gamma was noted among LTx recipients with nonrecurrent hepatitis C than among those with recurrent hepatitis C.

CONCLUSIONS

While no significant correlation was detected between particular cytokine profile and early rejection episodes, our data strongly suggest an association between cytokine gene polymorphism of TGF-beta, IL-10, and INF-gamma and recurrence of hepatitis C in LTx recipients.

Determination of clenbuterol in bovine liver by combining matrix solid-phase dispersion and molecular imprinted solid-phase extraction followed by liquid chromatography/electrospray ion trap multiple-stage mass spectrometry

Matrix solid-phase dispersion (MSPD) is a new sample pretreatment for solid samples. This technique greatly simplifies sample pretreatment but, nonetheless, the extracts often still require an extra cleanup step that is both laborious and time-consuming. The potential of combining MSPD with molecularly imprinted solid-phase extraction (MISPE) was investigated in this study. Liver samples were ground in a mortar with C18 sorbent and the homogenized mixture packed into an SPE cartridge and placed on top of a MISPE cartridge. Subsequently, clenbuterol was eluted from the MSPD cartridge onto the MISPE cartridge using acetonitrile containing 1% acetic acid. The ability of the molecularly imprinted polymer to selectively adsorb analyte in acetonitrile was exploited for re-extracting clenbuterol directly from this acetonitrile extract via the double cartridge tandem system. The analyte was eluted from the MISPE cartridge using acidified methanol. A clear eluate was obtained, which was subsequently evaporated, redissolved, and analyzed by HPLC electrochemical detection (ECD) or ion trap mass spectrometry (LC/IT-MS). The MISPE cartridge used in this study was imprinted using bromoclenbuterol, a structural analogue of clenbuterol, as the template. These MISPE cartridges showed excellent stability. The complete extraction procedure was rapid, and recoveries exceeded 90% for the target analyte. The method detection limit for the LC/IT-MS procedure was < 0.1 microg/kg. This method, therefore, satisfies the stringent requirements of European Union regulation EEC 2377/90.

Close association of HLA-B52 and HLA-B44 antigens in Israeli Arab adolescents with recurrent aphthous stomatitis

OBJECTIVES

To investigate the incidence and clinical features of recurrent aphthous stomatitis (RAS) among Israeli Arab adolescents and to determine the HLA typing profile in affected subjects.

STUDY DESIGN

Cross-sectional study.

SETTING

Junior high school in the largest Arab town in Israel.

PARTICIPANTS

Four hundred seventy-seven Israeli Arab junior high school students filled out a questionnaire. Students who reported more than 4 episodes of RAS during the previous year were interviewed by telephone. Those whose responses were confirmed were invited to the clinic. Of these, 22 were chosen at random for HLA typing. Findings were compared with those in 117 healthy Israeli Arabs who were candidate donors of bone marrow to patients at the Institute of Hematology-Oncology, Schneider Children's Medical Center of Israel, Petah Tiqva.

RESULTS

Recurrent aphthous stomatitis was confirmed in 80 subjects (16.7%). Of the 22 patients who underwent HLA typing, 7 (31.4%) had HLA-B52 antigens and 8 (36.4%) had HLA-B44 antigens; corresponding figures for the control group were 10 subjects (8.5%) (P = .007) and 9 subjects (7.7%) (P = .001), respectively.

CONCLUSIONS

There is a close association of HLA-B52 and HLA-B44 in Israeli Arab youths with RAS. Long-term follow-up is needed to determine the relationship between RAS and Behçet disease.

The inhibitory potency and selectivity of arginine substrate site nitric-oxide synthase inhibitors is solely determined by their affinity toward the different isoenzymes

We have investigated various nitric oxide (NO) synthase inhibitors for their affinity and selectivity toward the three human isoenzymes in radioligand binding experiments. Therefore, we developed the new radioligand [(3)H]2-amino-4-picoline to measure binding of these compounds to the three human NO synthase (NOS) isoenzymes. Aminopicoline is a potent and nonselective inhibitor of all three isoforms. [(3)H]2-amino-4-picoline bound saturably and with high affinity to human NOSs. Affinity constants (K(D) values) of 59, 111, and 136 nM were obtained for the inducible, neuronal, and endothelial NOS isoforms (iNOS, nNOS, eNOS). Binding of [(3)H]2-amino-4-picoline was competitive with the substrate arginine. From all the inhibitors tested, AMT (2-amino-5, 6-dihydro-6-methyl-4H-1,3-thiazine hydrochloride) showed the highest affinity and no selectivity. L-NIL [L-N(6)-(1-Iminoethyl)lysine hydrochloride] and aminoguanidine were moderately iNOS-selective while L-NA (N(G)-nitro-L-arginine) and L-NAME (N(G)-nitro-L-arginine methyl ester hydrochloride) showed selectivity toward the constitutive isoforms. High iNOS versus eNOS selectivity was found for 1400W, whereas several isothiourea derivatives and 1400W displayed moderate n- versus eNOS selectivity. To relate the affinity of these compounds to their inhibitory potency, we measured the inhibitory potency under almost identical conditions using a new microtiter plate assay. The inhibitory potency of selective and nonselective NOS inhibitors was almost exactly mirrored by their affinity toward the different isoenzymes. Highly significant correlations were obtained between the potency of enzyme inhibition and the inhibition of [(3)H]2-amino-4-picoline binding for all three isoenzymes. These data show that the potency and selectivity of NOS inhibitors are solely determined by their affinity toward the different isoforms. Furthermore, these data identify the new radioligand [(3)H]2-amino-4-picoline as a very useful radiolabel for the investigation of the substrate binding site of all three isoforms.

Predisposing factors and gross examination findings in periodontal disease

Periodontal disease is the most frequently encountered condition by small animal practitioners. A complete oral examination including visual examination, periodontal probing, and intraoral radiographs are necessary to determine the grades of disease present, and the predisposing factors contributing to it.

Induction of interleukin-4 (IL-4) by legionella pneumophila infection in BALB/c mice and regulation of tumor necrosis factor alpha, IL-6, and IL-1beta

Infection of BALB/c mice with a sublethal concentration of Legionella pneumophila causes an acute disease that is resolved by innate immune responses. The infection also initiates the development of adaptive Th1 responses that protect the mice from challenge infections. To study the early responses, cytokines induced during the first 24 h after infection were examined. In the serum, interleukin-12 (IL-12) was detectable by 3 h and peaked at 10 h, while gamma interferon was discernible by 5 h and peaked at 8 h. Similar patterns were observed in ex vivo cultures of splenocytes. A transient IL-4 response was also detected by 3 h postinfection in ex vivo cultures. BALB/c IL-4-deficient mice were more susceptible to L. pneumophila infection than were wild-type mice. The infection induced higher serum levels of acute-phase cytokines (tumor necrosis factor alpha [TNF-alpha], IL-1beta, and IL-6), and reducing TNF-alpha levels with antibodies protected the mice from death. Moreover, the addition of IL-4 to L. pneumophila-infected macrophage cultures suppressed the production of these cytokines. Thus, the lack of IL-4 in the deficient mice resulted in unchecked TNF-alpha production, which appeared to cause the mortality. Monocyte chemoattractant protein-1 (MCP-1), a chemokine that is induced by IL-4 during Listeria monocytogenes infection, was detected at between 2 and 30 h after infection. However, MCP-1 did not appear to be induced by IL-4 or to be required for the TNF-alpha regulation by IL-4. The data suggest that the early increase in IL-4 serves to regulate the mobilization of acute phase cytokines and thus controls the potential harmful effects of these cytokines.

Two different activities of Suppressor of Hairless during wing development in Drosophila

The Notch pathway plays a crucial and universal role in the assignation of cell fates during development. In Drosophila, Notch is a transmembrane protein that acts as a receptor of two ligands Serrate and delta. The current model of Notch signal transduction proposes that Notch is activated upon binding its ligands and that this leads to the cleavage and release of its intracellular domain (also called Nintra). Nintra translocates to the nucleus where it forms a dimeric transcription activator with the Su(H) protein. In contrast with this activation model, experiments with the vertebrate homologue of Su(H), CBF1, suggest that, in vertebrates, Nintra converts CBF1 from a repressor into an activator. Here we have assessed the role of Su(H) in Notch signalling during the development of the wing of Drosophila. Our results show that, during this process, Su(H) can activate the expression of some Notch target genes and that it can do so without the activation of the Notch pathway or the presence of Nintra. In contrast, the activation of other Notch target genes requires both Su(H) and Nintra, and, in the absence of Nintra, Su(H) acts as a repressor. We also find that the Hairless protein interacts with Notch signalling during wing development and inhibits the activity of Su(H). Our results suggest that, in Drosophila, the activation of Su(H) by Notch involve the release of Su(H) from an inhibitory complex, which contains the Hairless protein. After its release Su(H) can activate gene expression in absence of Nintra.

Is there social transmission of feather pecking in groups of laying hen chicks?

Feather pecking is an abnormal behaviour where laying hens peck the feathers of conspecifics, damaging the plumage or even injuring the skin. If it occurs in a flock, more and more birds show it within a short period of time. A possible mechanism is social transmission. Several studies have shown that laying hen chicks, Gallus gallus domesticus, are able to modify their own behaviour when observing the behaviour of other chicks, for example, when feeding and foraging. As there is good experimental evidence that feather pecking originates from foraging behaviour, we hypothesized that feather pecking could also be socially transmitted. To test this, we reared 16 groups of 30 chicks. After week 4, the birds were regrouped into 16 groups of 20 chicks into each of which we introduced either five chicks that showed high frequencies of feather pecking or, as controls, five chicks that had not developed feather pecking. We then determined the feather-pecking rate and the frequency of foraging, dustbathing, feeding, drinking, preening, moving, standing and resting of all birds in a group. Data from the introduced birds were analysed separately and excluded from the group data. Chicks in groups with introduced feather-pecking chicks had a significantly higher feather-pecking rate than chicks in the control groups. In addition, birds in groups with introduced feather peckers showed significantly lower foraging frequencies than those in the control groups, although the housing conditions were identical and there were no differences in either the number or the quality of the stimuli relevant to foraging behaviour. The study therefore suggests that feather pecking is socially transmitted in groups of laying hen chicks. Copyright 2000 The Association for the Study of Animal Behaviour.

Structural requirements for notch signalling with delta and serrate during the development and patterning of the wing disc of Drosophila

The delta and Serrate proteins interact with the extracellular domain of the Notch receptor and initiate signalling through the receptor. The two ligands are very similar in structure and have been shown to be interchangeable experimentally; however, loss of function analysis indicates that they have different functions during development and analysis of their signalling during wing development indicates that the Fringe protein can discriminate between the two ligands. This raises the possibility that the signalling of delta and Serrate through Notch requires different domains of the Notch protein. Here we have tested this possibility by examining the ability of delta and Serrate to interact and signal with Notch molecules in which different domains had been deleted. This analysis has shown that EGF-like repeats 11 and 12, the RAM-23 and cdc10/ankyrin repeats and the region C-terminal to the cdc10/ankyrin repeats of Notch are necessary for both delta and Serrate to signal via Notch. They also indicate, however, that delta and Serrate utilise EGF-like repeats 24–26 of Notch for signalling, but there are significant differences in the way they utilise these repeats.

Distribution and cellular localization of prostacyclin synthase in human brain

Prostacyclin (PGI(2)) is a labile, lipid-derived metabolite of arachidonic acid synthesized through the sequential action of cyclo-oxygenase (COX) and prostacyclin synthase (PGIS). In addition to its well-characterized vasodilatory and thrombolytic effects, an increasing number of studies report an important role of PGI(2) in nociception in various animal species. In this study we investigated the regional distribution of PGIS in human brain by immunohistochemistry and in situ hybridization. PGIS-immunoreactive (ir) protein was localized to blood vessels throughout the brain. Neuronal cells and glial cells, such as microglia and oligodendrocytes, also showed intense labeling. The strongest expression of PGIS was seen in large principal neurons, such as pyramidal cells of the cortex, pyramidal cells of the hippocampus, and Purkinje cells of the cerebellum. Abundance of PGIS mRNA was observed in blood vessels and large neurons and correlated well with the immunohistochemical findings. The expression of PGIS in human brain was further demonstrated by immunoblotting and detection of 6-keto-PGF (1alpha), the stable degradation product of prostacyclin in human brain homogenate. These results demonstrate a widespread expression of PGIS in the central nervous system and suggest a potentially important role of prostacylin in modulating neuronal activity in human brain.