The role of 3d electrons in the appearance of ferromagnetism in the antiferromagnetic Ru2MnGe Heusler compound: a magnetic Compton scattering study.

The antiferromagnetism in Ru(2)MnGe can be suppressed by the substitution of V by Mn and ferromagnetism appears. Synchrotron-based magnetic Compton scattering experiments are used in order to investigates the role of 3d electrons in the indirect/direct exchange interactions for the appearance of ferromagnetism. A small spin moment for the itinerant electron part on the magnetic Compton profile indicates that the metallic ferromagnet Ru(2)Mn(0.5)V(0.5)Ge has a weak indirect exchange interaction between the d-like and sp-like (itinerant) electrons. This suggests that the appearance of ferromagnetism is caused by the enhancement of the direct exchange interactions between d-d electrons in the Ru(2)MnGe Heusler compound. These findings indicate that the indirect exchange interaction between itinerant electrons and localized electrons is a significant key point for the appearance of ferromagnetism in this system.

Variation of the Ru moment in the Ca(0.3)Sr(0.7)Ru(1-x)Mn(x)O3 system.

The variation of the magnetic moment on Ru and Mn atoms in the Ca(0.3)Sr(0.7)Ru(1-x)Mn(x)O(3) system was investigated by the magnetic Compton scattering technique using synchrotron radiation. The Ca(0.3)Sr(0.7)Ru(1-x)Mn(x)O(3) system has ferrimagnetism with an antiferromagnetic coupling between Ru and Mn, and the dominant magnetic component changes from ferromagnetic Ru to ferromagnetic Mn at x ∼0.25 as the Mn substitution proceeds. The mechanism for the change in the magnetism of Ca(0.3)Sr(0.7)Ru(1-x)Mn(x)O(3) is discussed.

Magnetic ground states of CaRu(1-x)Mn(x)O(3)(0.2 ≤ x ≤ 0.9): a magnetic Compton scattering study.

The magnetism of CaRu(1-x)Mn(x)O(3)(0.2≤x≤0.9) was studied by the magnetic Compton scattering experiment. The result of the spin-polarized electron momentum density distributions (magnetic Compton profiles) and the absolute value of spin moment indicate that Mn doping introduces magnetic moments on Ru ions, and the Ru and Mn spin moments were antiferromagnetically coupled. Moreover the spin moment of Ru ions increased proportionally in the x range. These results were explained by a mixed valence model and inhomogeneous magnetic structure, where the inhomogeneous magnetic ground state in CaRu(1-x)Mn(x)O(3) would be formed by a ferrimagnetic network from the Mn(3.5+) and Ru(4.5+) clusters in the paramagnetic matrix CaRuO(3) for x<0.5 and in the antiferromagnetic matrix CaMnO(3) for x>0.5.

Orbital magnetic moment in Ir doped CaMnO(3).

The magnetism of CaMn(0.55)Ir(0.45)O(3) has been studied using the magnetic Compton scattering technique. The analysis of the magnetic Compton profile shows that the spin moments of Mn and Ir form an antiparallel configuration, establishing ferrimagnetism. Moreover, the experimental results indicate the existence of an orbital moment 0.2  µ(B)/f.u.. The possible model for these results has been discussed under the framework of the localized electron model by taking account of the electronic states of the Ir(4+) ion.

Ferromagnetism in CaMn(1-x)Ir(x)O(3).

The crystallographic, magnetic, and electric properties of CaMn(1-x)Ir(x)O(3) (0≤x≤0.6) were investigated. The lattice constants increase with increasing content of Ir. Specimens of 0.05≤x≤0.2 show antiferromagnetic behavior; however, ferromagnetism is observed for specimens of 0.3≤x≤0.6. T(N) decreases as the Ir content increases. T(N) is superseded by T(C) without passing 0 K and T(C) continues to increase in the ferromagnetic composition range. The effective moment µ(eff) decreases as the Ir content increases. The Weiss temperature is negative for small x; however, it continues to increase while changing its sign at about x = 0.3. The results were explained by assuming a mixed valence state of Mn(3+), Mn(4+), Ir(4+), and Ir(5+) ions. The composition dependence of µ(eff) could be explained qualitatively using the ion fractions estimated from the Ir content dependence of the unit cell volume. Experimental results suggest the coexistence of antiferromagnetic and ferromagnetic phases. When the volume fraction of the ferromagnetic phase dominates that of the antiferromagnetic phase, the system seems to show ferromagnetism.

Suppression of allergic reaction by lambda-carrageenan: toll-like receptor 4/MyD88-dependent and -independent modulation of immunity.

BACKGROUND: Recognition of foreign substances by innate immunity through pattern recognition receptors (PRRs) regulates acquired immunity such as allergic reaction. Because PRRs recognize heterogeneous ligands, daily food intake can potentially regulate immune allergic reaction. OBJECTIVE: Elucidation of the effect of lambda-carrageenan on allergic reactions was aimed. METHOD: IFN-gamma and IL-4 was measured in in vitro T cell-stimulated culture. Cytokine production from macrophages in response to lambda-carrageenan was measured as indicator for innate immunity activation. Mice were immunized with OVA in alum to induce specific IgE, and then histamine release was induced by systemic injection of OVA. RESULTS: Activation of innate immunity by lambda-carrageenan is dependent on Toll-like receptor-4 (TLR4) and MyD88, in which induction of pro-inflammatory cytokines such as TNF-alpha and IL-6 was largely impaired in macrophages from TLR4- and MyD88-deficient mice. Footpad oedema, a model for in vivo inflammatory reactions, was significantly reduced in these mice. Similar to recent evidence showing a preference for the stimulation of Th1 via TLR/MyD88 signalling, lambda-carrageenan showed enhanced IFN-gamma and decreased IL-4 in stimulated T cell cultures. Interestingly, increased IFN-gamma production was still seen in TLR4- and MyD88-deficient splenocytes. Oral administration of lambda-carrageenan to immunized mice successfully decreased OVA-specific IgE, and lambda-carrageenan was also effective in previously immunized mice. Further, serum histamine release upon systemic challenge of OVA was significantly inhibited. Neither OVA-specific IgG1/IgG2a nor cytokine secretion from in vitro cultures were altered, suggesting the involvement of multiple PRRs as demonstrated by TLR4/MyD88-independent IFN-gamma up-regulation. The simultaneous feeding of OVA with lipopolysaccharide abrogated oral tolerance, but lambda-carrageenan was not only devoid of such an effect but was also found to promote oral tolerance in the absence of TLR4. CONCLUSION: lambda-Carrageenan was suggested to be a useful dietary supplement to ameliorate allergic reactions while maintaining oral tolerance-dependent intestinal homeostasis.

Photodegradation products of methylprednisolone suleptanate in aqueous solution--evidence of a bicyclo[3.1.0]hex-3-en-2-one intermediate.

Two major photodegradation products of methylprednisolone suleptanate (sodium 11 beta, 17 alpha-dihydroxy-6 alpha-methyl-21-[[8-[methyl(2-sulfoethyl)amino]-1,8-dioxooctyl+ ++]oxy]-pregna-1,4-diene-3,20-dione) in aqueous solution irradiated with white fluorescent light at 2000 lux for 28 days at 25 degrees C were isolated by preparative high-performance liquid chromatography and characterized. Structures of the photodegradation products were determined as sodium 11 beta,17 alpha-dihydroxy-5 alpha, 6 alpha-dimethyl-21-[[8-[methyl(2-sulfoethyl)amino]-1,8-dioxoocty l]-oxy]-19-norpregna-1(10),3-diene-2,20-dione and sodium 1 beta, 11 beta-epoxy-17 alpha-hydroxy-6 alpha-methyl-21-[[8-[methyl(2-sulfoethyl)amino]-1, 8-dioxooctyl]oxy]-19 alpha-pregn-4-ene-2.20-dione. Formation of these compounds, especially the 1,11-epoxy analogue, strongly supports the existence of the bicyclo[3.1.0]hex-3-en-2-one intermediate in the photorearrangement of steroidal cross-conjugated dienones. The intermediate can account for all the major ketonic and phenolic products; these products are generated from the intermediate after subsequent transformations and/or further skeletal rearrangements. The 1,11-epoxy analogues were obtained from the prednisolone steroids in high yields by irradiation with a high-pressure mercury lamp.

Jejunal varices as a cause of massive gastrointestinal bleeding.

Jejunal varices are not a common manifestation of portal hypertension. This report describes a 46-yr-old man with recurrent massive gastrointestinal bleeding from jejunal varices arising in an area of adhesions between the intestine and the omentum. The bleeding site was identified by exploratory laparotomy. Medical therapy, including vasopressin infusion via the superior mesenteric artery, was of limited success for controlling acute variceal bleeding. However, jejunal resection and anastomosis resulted in complete resolution of the bleeding, and the patient has experienced no recurrent bleeding over a 3-yr follow-up period. A review of the literature shows that this syndrome is characterized by portal hypertension, generally due to liver cirrhosis; frequently, there is a history of abdominal surgery, and the syndrome presents with hematochezia but without hematemesis. Accurate preoperative diagnosis is often difficult. We propose that bleeding from jejunal varices, though uncommon, should be considered under such clinical conditions.

Renal kinin and kallikrein excretion in cirrhotic patients.

Urinary kinin and urinary kallikrein activity were measured in 33 liver cirrhotics, and the values were correlated with the severity of the liver disease. A significant relationship was observed between urinary kinin excretion and urinary kallikrein excretion (r = 0.53; p less than 0.01). Both urinary kinin and kallikrein excretion were significantly lower in Child's group C than in Child's groups A and B (p less than 0.05) and showed positive correlations with serum albumin (r = 0.47, p less than 0.01 and r = 0.46, p less than 0.01, respectively). Increases in urinary kinin and kallikrein excretion after endoscopic variceal sclerotherapy were observed in 18 patients (p less than 0.01 and p less than 0.05, respectively). These results suggest that the renal kallikrein-kinin system in suppressed in severe liver disease in proportion to the severity of the underlying liver disease. In this study possible activation of this system after sclerotherapy was also demonstrated.

Manifestations of temporary symptoms during endoscopic variceal sclerotherapy using thrombin as a sclerosant.

We performed 93 sclerotherapy sessions on liver cirrhosis patients with recurrent variceal bleedings. In each session, hypertonic glucose, thrombin and 1% polidocanol were consecutively injected into the varices, and changes in the hemostatic system were examined in relation to the symptoms observed during the treatment. Patients underwent sclerotherapy with no complaints in 62 (67%) sessions, and complained of slight symptoms of general fatigue and headache in 19 (20%). In the other 12 (13%) sessions, the procedure was discontinued due to marked manifestations of these symptoms. All symptoms were temporary and disappeared completely after the procedure. These temporary symptoms were closely related to changes in coagulation tests similar to those of disseminated intravascular coagulation, which were observed just after the treatment. Possible activation of the renal kallikrein-kinin system following injection sclerotherapy was also demonstrated.

Effects of endoscopic variceal sclerotherapy using GT XIII on blood coagulation tests and the renal kallikrein-kinin system.

Forty-six sclerotherapy sessions were performed on liver cirrhotics with high-risk esophageal varices using GT XIII, a sclerosant composed of gelatin, thrombin and coagulation factor XIII. GT XIII was effective for the prevention of temporary symptoms and transient hypotension observed in 55 sclerotherapy sessions using thrombin. In 42 (91%) sessions, patients underwent sclerotherapy with no symptoms, and in the other four (9%) sessions, only slight symptoms of general fatigue and headache were observed. Changes in the mean arterial pressure were significantly smaller in sessions using GT XIII than in those using thrombin (-12.3 +/- 13.6 vs. -26.8 +/- 20.7 mmHg, P less than 0.01). Changes in coagulation tests, similar to those of disseminated intravascular coagulation (DIC), were also reduced in sessions using GT XIII. Urinary kallikrein and kinin excretion significantly increased after the procedure (P less than 0.01), indicating activation of the renal kallikrein-kinin system. Increases in urinary kallikrein and kinin excretion showed a significant relationship with the consumed plasma fibrinogen levels (r = -0.51, P less than 0.01 and r = -0.58, P less than 0.01, respectively), and it was suggested that activation of the glandular kallikrein-kinin system caused by abrupt DIC-like changes in the hemostatic system might play a role in manifestations of temporary complications occurring with the use of hemostatic agents containing thrombin.

Highly sensitive assay for acetylcholinesterase activity by high-performance liquid chromatography with electrochemical detection.

A highly sensitive assay for acetylcholinesterase (AChE) activity was devised by high-performance liquid chromatography with electrochemical detection. It is based on the separation of acetylcholine and choline on an octadecylsilane reversed-phase column, followed by their enzymatic conversion into hydrogen peroxide through the post-column reaction with immobilized AChE and choline oxidase. The system is highly sensitive, and the relationship between the peak height and the amount of choline is linear over the range 5 pmol to 5 nmol. When homogenate of bovine caudate nucleus was used as enzyme, the Michaelis constant of the enzyme for acetylcholine was 0.4 mM. The regional distribution of AChE activity in rat brain was examined, and the order of the activity from the highest to the lowest agreed with the reported brain distribution of AChE: striatum, thalamus plus hypothalamus, pons plus medulla oblongata, cerebral cortex, olfactory bulb, and cerebellum.