Analytical model for spin dynamics in radical pairs under the spin-locking condition.

Spin dynamics in triplet radical pairs are theoretically studied under the spin-locking condition, where singlet-triplet mixing is blocked by the resonant microwave field. A key assumption in the theory is simultaneous excitations of T+-T0 and T--T0 transitions in triplet radical pairs. This assumption allows for the application of a three-state model [Yago, J. Chem. Phys. 151, 214501 (2019)] to describe the spin dynamics of triplet radical pairs. The analysis based on the three-state model shows that the triplet states are quantized along the direction of a microwave-induced magnetic field (B1) in the rotating frame under the spin-locking condition. This gives rise to a new spin-locking phenomenon where T+-T0 and T--T0 mixing are most enhanced at magnetic fields that deviate from the resonance by ±B1. It is also shown that the quantum beats observed under the spin-locking condition originate from the spin dynamics in triplet radical pairs.

Low magnetic field effects on triplet pair annihilations at canonical orientations.

Using the density operator formalism, a simple analytical model is developed to study low magnetic field effects on triplet pair annihilations in organic solids. Analysis is restricted to canonical orientations where two identical triplet molecules have the same orientation and the direction of the external magnetic field is parallel to one of the principle axes of the dipolar coupling tensor for a triplet. The analytical solution reveals that the low magnetic field effect in the triplet pair arises from the anisotropic dipole-dipole coupling in a triplet. In the presence of the dipole-dipole coupling, the spin quantization axis for each triplet gradually changes with the increase of the external magnetic field from zero field to high field. The low magnetic field effect reaches a maximum when the Zeeman splitting between the spin states matches a dipole-dipole coupling component orthogonal to the external magnetic field direction. The result is also discussed with the low magnetic field effect in the radical pair with one isotropic hyperfine coupling.

Anti-glucose-6-phosphate isomerase, anti-cyclic citrullinated peptide antibodies and HLA-DRB1 genotypes in Japanese patients with early rheumatoid arthritis.

OBJECTIVE: Our goal was to evaluate the associations of antibodies (Abs) to glucose-6-phosphate isomerase (GPI) with Abs to cyclic citrullinated peptide (CCP) and HLA-DRB1 genotypes in Japanese patients with early rheumatoid arthritis (RA). METHODS: One hundred and eight patients with early RA (85 female, 23 male) who visited our clinic within 1 year of symptom onset were examined for anti-GPI and anti-CCP Ab levels, and HLA-DRB1 genotype. Anti-GPI and anti-CCP Ab levels, and HLA-DRB1 genotypes were also determined in 63 controls and 265 healthy controls, respectively. RESULTS: Of the 108 patients with early RA and the 63 controls, 20 (18.5%) and 3 (4.8%) were anti-GPI Ab-positive, respectively. Of the 20 patients with anti-GPI Abs, 17 (85%) were positive for anti-CCP Abs. HLA-DRB1*0405 and shared epitope (SE) carrier frequencies were significantly increased not only in anti-GPI Ab-positive patients (p=0.00057, odds ratio [OR] 4.6, 95% CI 1.8-11.8; p=0.0011, OR 5.0, 95% CI 1.7-14.0), but also in anti-GPI Ab-negative patients (p=0.0017, OR 2.2, 95% CI 1.3-3.7; p=0.00011, OR 2.6, 95% CI 1.6-4.3), when compared with controls. In addition, the carrier frequency of HLA-DRB1*1201 was significantly increased in anti-GPI Ab-positive patients compared with controls (p=0.0056, OR 4.3, 95% CI 1.4-13.2). CONCLUSIONS: The majority of anti-GPI Ab-positive RA patients constitute a subset of HLA-DRB1* SE-associated, anti-CCP Ab-positive RA patients.

Differential association of HLA-DRB1 alleles in Japanese patients with early rheumatoid arthritis in relationship to autoantibodies to cyclic citrullinated peptide.

OBJECTIVE: To evaluate the role of HLA-DRB1 genotypes and antibodies to cyclic citrullinated peptides (anti-CCP antibodies) in the development and radiographic progression of Japanese patients with rheumatoid arthritis (RA). METHODS: One hundred and ten patients with early RA (88 female, 22 male) who visited our clinic within 1 year of symptom onset were examined for anti-CCP antibody levels and HLA-DRB1 genotypes. HLA-DRB1 genotypes were also determined in 265 healthy controls. Radiographic progression over a 2-year interval was evaluated using the Larsen's method in 66 patients. RESULTS: Among the 110 patients with early RA, 82 patients (74.5%) were anti-CCP positive. Carrier frequency of HLA-DRB1*0405 was significantly increased in RA patients with anti-CCP antibodies compared with controls and RA patients without anti-CCP antibodies (odds ratio [OR] 3.4, 95% confidence interval [95% CI] 2.0-5.7 and OR 3.3, 95% CI 1.3-8.6, respectively). Carriership of one or two SE alleles was significantly associated with production of anti-CCP antibodies (OR 2.7, 95% CI 1.1-6.7 and OR 9.3, 95% CI 1.1-78.2, respectively). On the other hand, allele frequency of HLA-DRB1*0901 was significantly increased in RA patients without anti-CCP antibodies compared with controls and RA patients with anti-CCP antibodies (OR 2.2, 95% CI 1.1-4.1 and OR 3.0, 95% CI 1.4-6.4, respectively). CONCLUSION: In Japanese patients with RA, HLA-DRB1 SE alleles are associated with production of anti-CCP antibodies and HLA-DRB1 alleles appear to be differently associated with early RA depending on anti-CCP positivity as in Caucasian patients with RA.

Two Japanese cases with MAGIC syndrome (mouth and genital ulcers with inflamed cartilage).

We describe two cases, a 28-year-old woman and a 46-year-old man, with mouth and genital ulcers with inflamed cartilage (chondritis of the nose and ears) (MAGIC syndrome). The conditions of both patients were resolved by treatment with corticosteroid and colchicine. We also review the English literature related to this rare syndrome.

[A randomized crossover comparison of azasetron and granisetron in the prophylaxis of emesis induced by chemotherapy including cisplatin].

The clinical application of 5-HT3 receptor antagonists has enabled continuation of the course of chemotherapy including cisplatin, which induces strong nausea and vomiting, and to prevent the delay of curative treatment for cancer patients receiving neoadjuvant chemotherapy. However, with the development of basic research on the mechanisms of vomiting, each 5-HT3 receptor antagonist has appeared to have different pharmacological actions and, subsequently, the difference in the clinical efficacy of each drug has been reported in Europe and USA. In freshly advanced head and neck carcinoma cases, a randomised crossover study was performed to compare the efficacy and safety profile of a single intravenous dose for 7 days of azasetron (10 mg/day) or granisetron (3 mg/day) in the prophylaxis of nausea and vomiting induced by multi-drug chemotherapy including cisplatin (50 mg/m2 or 60 mg/m2). Anti-emetic effects were evaluated by the protective rates for nausea and vomiting for 7 days following the start of cisplatin administration. Both 5-HT3 receptor antagonists were highly effective in the prophylaxis of acute and delayed emesis induced by chemotherapy, whereas the efficacies of azasetron on day 3 and 4 were superior to those of granisetron. No adverse effect of either drug was observed in this study.

[Comparison of granisetron alone and granisetron plus dexamethasone or hydroxyzine hydrochloride for the prevention of nausea and vomiting during chemotherapy including cisplatin].

The comparative study among granisetron alone and granisetron combined with hydroxyzine hydrochloride or dexamethasone was undertaken for the prevention of nausea and vomiting during chemotherapy including cisplatin in patients with advanced head and neck carcinomas. The results indicated that the combination antiemetic therapies were more effective than granisetron alone for acute nausea and vomiting, whereas a significant difference was not observed among these three groups in the acute adverse effects. Otherwhile, there were statistically significant improvements in the prevention of delayed nausea and vomiting for patients receiving granisetron combined with the other antiemetic drugs, especially the combination antiemetic therapy with dexamethasone. These results confirm the antiemetic activity of granisetron in acute nausea and vomiting induced by cisplatin and show that it has an additive effect in combination with dexamethasone.

[The expression of ICAM-1 on head and neck squamous cell carcinoma cell lines].

Intercellular adhesion molecule-1 (ICAM-1) is one of the cell adhesion molecules. This molecule is a glycoprotein of about 90 KDa belonging to the immunoglobulin (Ig) superfamily and is widely expressed by hematopoietic and non-hematopoietic cells which play a role in the immune system. ICAM-1 is also a ligand or counter-receptor for the leukocyte integrin lymphocyte-function associated antigen-1 (LFA-1). We investigated the expression of ICAM-1 on the surfaces of cells from fifteen head and neck squamous carcinoma cell lines and the modulation of ICAM-1 expression by IFN-gamma, using an immunohistochemical stain. We categorized four types of stain degree. (-): < 10% of cells positive (+/-): 10-40% of cells positive (+): < 40-70% of cells positive (++): > 70% of cells positive Four cell lines showed (-) type. Three cell lines: (+/-). One cell line: (+). Seven cell lines: (++). The primary site of cell lines and the degree of ICAM-1 expression were not detectable. Connection between pathological differentiation and the degreed expression were not apparent, either. IFN-gamma up-regulated the degree of ICAM-1. All cell lines, when stimulated by IFN-gamma, showed (++) type.

[Angiogenesis in head and neck tumor].

To clarify the correlation between tumor angiogenesis and tumor growth in head and neck carcinomas, we investigated the number of microvessels, using immunohistochemical factor VIII. No correlations among this number, differences in the primary lesion, histological differentiation and T classification were detected. The incidence of neck lymph node metastases increased as microvessel numbers increased in tumor sites. The number of microvessels increased as N and Stage classification progressed. The number of microvessels in CR cases after induction chemotherapy were increased. The numbers of microvessels in patients without recurrence were apparently greater than those in patients with recurrence. The results of this study suggest that the number of microvessels in a primary tumor correlates with the metastatic ability of the tumor.

P-selectin binding promotes the adhesion of monocytes to VCAM-1 under flow conditions.

This study examined the adhesive interaction of peripheral blood monocytes with VCAM-1 and analyzed the effect of P-selectin binding to monocytes on the adhesive interaction with VCAM-1 under flow conditions. P-selectin glycoprotein ligand-1 is expressed on most monocytes. Furthermore, most monocytes bind soluble P-selectin derived from platelets. P-selectin binding to monocytes did not alter the amount of expression of alpha4 integrin on monocytes. However, the mean channel fluorescence value for binding Cy2-conjugated soluble VCAM-1 to P-selectin-bound monocytes was slightly more than that for binding Cy2-conjugated soluble VCAM-1 to untreated monocytes. Under flow conditions, the number of P-selectin-bound monocytes bound to VCAM-1 was much higher than that of untreated monocytes bound to VCAM-1. These bindings were abolished by pretreatment of untreated monocytes and P-selectin-bound monocytes with anti-VCAM-1 mAb or anti-alpha4 integrin mAb. Furthermore, P-selectin binding to monocytes increased shear resistance and thus increased the adhesive strength of monocytes to VCAM-1. These findings indicate that P-selectin binding to monocytes enhances the adhesive interaction of monocytes with VCAM-1. It is suggested that P-selectin glycoprotein ligand-1/P-selectin interaction and alpha4 integrin/VCAM-1 interaction can act sequentially in the adhesion cascade that regulates monocyte trafficking to inflammatory and atherosclerotic lesion.

Production of granulocyte colony-stimulating factor by head and neck carcinomas.

Detectable levels of G-CSF by enzyme-linked immunosorbent assay (ELISA) were found in sera of 4 out of 15 patients with head and neck carcinomas. Also cells prepared from the tumors of these 4 patients secreted G-CSF. The supernatants of cells derived from all 15 patients did not contain granulocyte-monocyte CSF, monocyte CSF, tumor necrosis factor-alpha, transforming growth factor-beta 1, epidermal growth factor, interleukin (IL)-1 beta and IL-6. These findings suggest that leukocytosis in patients with carcinomas might be due to the production of G-CSF by tumor cells.

A tumor cell line producing granulocyte colony-stimulating factor and an immune suppressive factor.

From a patient, both a cell line incapable of secreting granulocyte colony-stimulating factor (G-CSF) (TC873) and a cell line capable of secreting G-CSF (TCM902) were established. The effector cells induced, with TC873 cells showed a high lytic capacity against two types of tumor cells. The effector cells induced by TCM902 cells did not show such capacity. Furthermore, the TCM902 cells excreted a factor suppressing the proliferation of lymphokine activated killer (LAK) cells and the autologous tumor cell lysis of tumor associated lymphocytes. This factor probably is TFG-beta 1.

Secretion of a fibronectin-like substance from head and neck carcinomas.

The secretion of a fibronectin-like substance in culture supernatants of cell lines of head and neck squamous cell carcinomas was observed. Culture supernatants of some tumor cells had a high cell-attachment activity. Enzyme-linked immunosorbent assay with an antifibronectin antibody showed that the supernatant with cell attachment activity contained fibronectin. Furthermore, the cell attachment activity was clearly inhibited by the addition of a monoclonal antibody to fibronectin. These findings strongly suggest that the fibronectin produced by cancer cells is one of the potent mediators of the cell attachment.

Analysis of an initial step of T cell adhesion to endothelial monolayers under flow conditions.

We analyzed an initial step of T cell adhesion to endothelial cells under flow conditions. An initial step in T cell-endothelial cell interactions was characterized either by a rolling phase, or by an immediate arrest without rolling. Anti-E- and P-selectin Abs inhibited T cell rolling on endothelial cells under flow conditions. The rolling velocity of T cells on endothelial cells increased after treatment of endothelial cells with anti-E- or P-selectin Abs. Also, rolling of T cells was observed on E-selectin-transfected CHO cells but not on ICAM-1-transfected CHO cells. Thus, rolling of T cells under flow condition was dependent on E-selectin as well as P-selectin expressed on endothelial cells. In contrast, neither anti-E- nor P-selectin Abs inhibited the immediate arrest of T cells on endothelial cells significantly and anti-ICAM-1 Abs also failed to inhibit the immediate arrest of T cells. Therefore, other adhesion molecules may play an important role in the immediate arrest of T cells under flow conditions. The number of CD45RA- T cells rolling on E-selectin-transfected CHO cells was much higher than that of CD45RA+ T cells.

Epitope selection in major histocompatibility complex class I-mediated pathway is affected by the intracellular localization of an antigen.

We analyzed the mode of antigen presentation of an endogenous antigen localized in the cytoplasm or in the mitochondria. Pseudomonas aeruginosa PAO leucine-, isoleucine-, valine-binding protein (LIVAT-BP) encoded by the braC gene was used as a model antigen. Using mouse BALB/3T3 cells, we established two LIVAT-BP transfectants by transfection of a plasmid harboring the intact braC or braC gene fused with the mitochondrial transport signal derived from the yeast COXIV gene. One of the resulting transfectants, BC-15, expressed LIVAT-BP in the cytoplasm, while YZ-710 cells expressed LIVAT-BP in the mitochondria. The splenic effector cells derived from BALB/c mice primed with BC-15 cells exhibited cytotoxic T lymphocyte (CTL) activity against BC-15 cells, but not against YZ-710 cells, whereas splenic effector cells primed with YZ-710 cells exhibited CTL activity against YZ-710 cells, but not against BC-15 cells. Neither group of splenic effector cells showed CTL activity against parental BALB/3T3 cells. These CTL belonged to the CD8+ alphabeta T cell subset. Furthermore, we observed that the CTL activity against t BC-15 cells or YZ-710 cells was blocked with anti-H2-K(d) mAb, but not with anti-H2-D(d) or H2-L(d) mAb. The CTL against BC-15 or YZ-710 cells could kill parental BALB/3T3 cells in the presence of peptides produced by alkali lysis of the LIVAT-BP, suggesting that these CTL indeed recognized the peptide(s) derived from LIVAT-BP. We determined that the epitope for the CTL against BC-15 cells was QYGEGIATEV, corresponding to residues 162-171, and that the epitope recognized by the CTL against YZ-710 cells was GYKLIFRTI, corresponding to residues 123-131 of LIVAT-BP, respectively. Thus, we show here that epitope selection for MHC class I expression is affected by the intracellular localization of the antigenic protein.

Analysis of initial attachment of B cells to endothelial cells under flow conditions.

This study examined the adhesive interactions of peripheral blood B cells with TNF-alpha-activated endothelial monolayers, and analyzed the roles of E-selectin, P-selectin, or VCAM-1 molecules expressed on activated HUVEC. B cell interaction occurred on activated HUVEC, but not on resting HUVEC under flow conditions. The majority of peripheral blood B cells expressed P-selectin glycoprotein ligand-1 and alpha4 integrin. However, the expression of cutaneous lymphocyte Ag on B cells was low. Under flow conditions, B cells could bind to P-selectin-coated tubes and VCAM-1-transfected Chinese hamster ovary cells. In contrast, B cells could not bind to E-selectin-coated tubes. Adhesion activity of B cells to P-selectin-coated tubes was weaker than that of T cells. Furthermore, adhesion activity of B cells to VCAM-1-transfected Chinese hamster ovary cells was similar to that of T cells. Treatment of activated HUVEC with anti-VCAM-1 mAb reduced interaction of B cells under flow conditions. However, the treatment of activated HUVEC with anti-P-selectin mAb did not reduce interaction. These data indicated that the interaction of VCAM-1 with alpha4 integrin plays a major role in an initial attachment of B cells to endothelial monolayers under flow conditions.

IL-12 promotes the adhesion of NK cells to endothelial selectins under flow conditions.

This study examined the adhesive interactions of peripheral blood NK cells with P- and E-selectin and analyzed the effect of IL-12 on the binding of NK cells to these selectins. P-selectin glycoprotein ligand-1 (PSGL-1) is expressed on most resting and IL-12-activated NK cells. However, the percentage of resting NK cells bound to P-selectin-IgG was 15%, and that of activated NK cells bound to P-selectin-IgG was 65%. Furthermore, the number of IL-12-activated NK cells bound to P-selectin-transfected Chinese hamster ovary cells was significantly higher than that of resting NK cells under flow conditions. These interactions were abolished by the incubation of these NK cells with anti-PSGL-1 (PL-1) mAb. Thus, PSGL-1/P-selectin interaction is important in the binding of resting and activated NK cells to P-selectin. NK cells express sialyl-Lewis(x) (sLe(x)) structure recognized by anti-sLe(x) mAb (KM-93), and IL-12 activation of NK cells increased the mean fluorescence intensity of KM-93-reactive NK cells. Adhesion of IL-12-activated NK cells to E-selectin-transfected Chinese hamster ovary cells was stronger than that of resting NK cells under flow conditions. These interactions were reduced markedly by incubation with anti-sLe(x) mAb. Thus, sLe(x) is the major ligand of resting and activated NK cells for E-selectin. These findings indicate that IL-12 stimulation of NK cells promotes their adhesion activity to endothelial selectins.

Dimerization of a selectin and its ligand stabilizes cell rolling and enhances tether strength in shear flow.

Selectins mediate rolling of leukocytes by rapid formation and dissociation of selectin-ligand bonds, which are assumed to require high mechanical strength to prevent premature dissociation by the forces applied in shear flow. This assumption is based largely on the observation that increasing wall shear stress increases only modestly the dissociation of transient leukocyte tethers on very low selectin densities. P-selectin binds to the N-terminal region of P-selectin glycoprotein ligand-1 (PSGL-1), a mucin on leukocytes. Both PSGL-1 and P-selectin are extended homodimers. We perfused transfected cells expressing wild-type dimeric PSGL-1 or a chimeric monomeric form of PSGL-1 on immobilized dimeric or monomeric forms of P-selectin. Cells expressing dimeric or monomeric PSGL-1 tethered to P-selectin at equivalent rates. However, cells expressing dimeric PSGL-1 established more stable rolling adhesions, which were more shear resistant and exhibited less fluctuation in rolling velocities. On low densities of dimeric P-selectin, increasing wall shear stress more rapidly increased transient tether dissociation of cells expressing monomeric PSGL-1 than dimeric PSGL-1. Tether dissociation on low densities of monomeric P-selectin was even more shear sensitive. We conclude that dimerization of both PSGL-1 and P-selectin stabilizes tethering and rolling, probably by increasing rebinding within a bond cluster. Because transient tethers may have more than one bond, the mechanical strength of selectin-ligand bonds is likely to be lower than initially estimated. Tether strength may rely more on bond clusters to distribute applied force.