Electrically induced changes in Ca2+ in Helisoma neurons: regional and neuron-specific differences and implications for neurite outgrowth

The present experiments addressed the questions of how electrical stimulation influenced the magnitude, time course, and regional levels of free intracellular calcium of different identified neurons. The calcium concentration in the growth cones, neurites and cell bodies of Helisoma buccal neurons B4 and B19 was measured while somata were electrically stimulated via an intracellular electrode. The findings showed that calcium levels in B4 and B19 increased monotonically with increasing stimulation frequency. However, the range of calcium levels evoked by electrical stimulation differed significantly for each type of neuron. The greater increase in calcium concentration in B4 was correlated with its longer duration action potential compared to B19. The increase in calcium concentration was much smaller in the cell bodies than in the growth cones and neurites. Extending the duration of the B19 action potential produced a sixfold increase in the change in calcium concentration at 2 Hz stimulation. Under conditions where the electrical stimulation produced a calcium concentration of < 160 nM, the elevated level of free intracellular calcium remained constant. When calcium concentration increased above 200 nM in both identified neurons, an initial peak concentration was followed by a decline to a lower concentration suggesting increased calcium buffering occurring above 200 nM. By correlating the calcium concentration data herein with growth data from a previous study, we suggest that specific calcium levels that influence neurite outgrowth may differ widely between neurons.     

Histological features of the contralateral ovary in patients with unilateral ovarian cancer: a case control study

It has been suggested that schizophrenia and alcoholism are associated with violent behavior. But so far there are no published studies from unselected cohorts quantifying the actual risk associated with schizophrenia both with and without comorbid alcoholism. In this study, an unselected birth cohort (n = 11,017) was prospectively followed to the age of 26, and data on psychiatric disorders and crimes were collected from national registers. The odds ratios for violent offenses and recidivism were calculated for each diagnostic group. Men who abused alcohol and were diagnosed with schizophrenia were 25.2 (95% confidence interval (CI) 6.1-97.5) times more likely to commit violent crimes than mentally healthy men. The risk for nonalcoholic patients with schizophrenia was 3.6 (95% CI 0.9-12.3) and for other psychoses, 7.7 (95% CI 2.2-23.9). None of the patients with schizophrenia who did not abuse alcohol were recidivists (> 2 offenses), but the risk for committing more crimes among alcoholic subjects with schizophrenia was 9.5-fold (95% CI 2.7-30.0). This study suggests that to prevent the crimes being committed by people with schizophrenia, it is important that clinicians watch for comorbid alcohol abuse.     

Loss of the tight junction MAGUK ZO-1 in breast cancer: relationship to glandular differentiation and loss of heterozygosity

Membrane-associated guanylate kinase homologs (MAGUKs) may play a role in cellular functions preventing tumorigenesis as indicated by the neoplastic phenotype caused by genetic loss of the MAGUK Dlg in Drosophila. To test this possibility, we examined the expression and subcellular localization of the tight junction MAGUK ZO-1, as well as the cell adhesion molecule E-cadherin, in paraffin-embedded breast cancer samples, using immunohistochemistry and confocal microscopy. As expected, normal tissue showed intense staining for ZO-1 at the position of the epithelial tight junctions, but this staining was reduced or lost in 69% of breast cancers analyzed (n = 48). In infiltrating ductal carcinomas (n = 38) there was a reduction in staining in 42% of well differentiated, in 83% of moderately differentiated and 93% of poorly differentiated tumors. ZO-1 staining was positively correlated with tumor differentiation (P = .011) and more specifically with the glandular differentiation of tumors (P = .0019). Reduction in ZO-1 staining was strongly correlated with reduced E-cadherin staining (P = 4.9 x 10(-5)). The results suggest that down-regulation of ZO-1 expression and its failure to accumulate at cell junctions may be causally related to cancer progression. To detect loss of heterozygosity, the ZO-1 gene tjp-1 was mapped relative to other markers in 15q13 and polymorphic markers flanking tjp-1 were identified. The marker D15S1019 showed loss of heterozygosity in 23% of informative tumors (n = 13). Loss of a tjp-1-linked marker suggests that genetic loss may, in some cases, be responsible for the reduction in ZO-1 expression in breast cancer.     

Selective outgrowth of a posttransplant B-immunoblastic lymphoma expressing a latent membrane protein-1 deletion variant

BACKGROUND: Posttransplant lymphoproliferative disorders are generally associated with Epstein-Barr virus (EBV) and are of B cell origin. We report the case of a B-immunoblastic lymphoma that developed in a pretransplantation EBV-seronegative woman 4 months after kidney transplant from her HLA-haploidentical brother. The patient successfully underwent immunotoxin therapy for lymphoma and has been in remission for 36 months. METHODS: Latent EBV genomes were identified by polymerase chain reaction, and the purified amplification products were directly sequenced with [35S]dATP. RESULTS: Molecular analysis of the latent membrane protein (LMP)1 oncogene of EBV, which was expressed in most tumor cells, revealed a 30-base pair deletion. No wild-type LMP1 sequences were found. Analysis of peripheral blood mononuclear cells from the EBV-seropositive donor showed the presence of both the LMP1 deletion variant and the wild-type sequence. The LMP1 deletion variant and the wild-type sequence were also identified within peripheral blood mononuclear cells of the EBV-seroconverted kidney recipient 20 months after lymphoma therapy. CONCLUSION: This pattern is consistent with a natural growth advantage of B cells expressing the LMP1 deletion variant in the immunocompromised host.     

Reduced turnover of the D1 polypeptide and photoactivation of electron transfer in novel herbicide resistant mutants of Synechocystis sp. PCC 6803

Two missense mutants, A263P and S264P, and a deletion mutant des-Ala263, Ser264, have been constructed in the D1 protein of the cyanobacterium Synechocystis sp PCC 6803. All were expected to induce a significant conformational change in the QB-binding region of photosystem II (PSII). Although the des-Ala263, Ser264-D1 mutant accumulated some D1 protein in the thylakoid membrane it was unable to grow photoautotrophically or evolve oxygen. Thermoluminescence and chlorophyll fluorescence studies confirmed that this deletion mutant did not show any functional PSII activity. In contrast, [S264P]D1 was able to grow photoautotrophically and give light-saturated rates of oxygen evolution at 60% of the rate of the wild-type control strain, TC31. The A263P missense mutant was also able to evolve oxygen at 50% of TC31 rates although it did not readily grow photoautotrophically. Thermoluminescence, flash oxygen yield and chlorophyll fluorescence measurements indicated that in both missense mutants electron transfer from QA to QB was significantly impaired in dark adapted cells. However, QA to QB electron transfer could be photoactivated in the mutants by background illumination. Both the A263P and S264P mutants also showed an increase in resistance to the s-triazine family of herbicides although this feature did not hold for the phenolic herbicide, ioxynil. Of particular interest was that the two missense mutants, especially S264P, possessed a slower rate of turnover of the D1 protein compared with TC31 and in vivo contained detectable levels of a 41-kDa adduct consisting of D1 and the alpha subunit of cytochrome b559. When protein synthesis was blocked by the addition of lincomycin, D1 degradation was again slower in S264P than TC31. The results are discussed in terms of structural changes in the QB-binding region which affect herbicide and plastoquinone binding and perturb the normal regulatory factors that control the degradation of the D1 protein and its synchronisation with the synthesis of a replacement D1 protein.     

Specific activity of polypyrrole nanoparticulate immunoreagents: comparison of surface chemistry and immobilization options

PURPOSE: Angioscopy for in situ vein graft preparation has been criticized on the basis that the trauma of instrumentation may predispose to accelerated intimal hyperplasia, jeopardizing patency rates following infrainguinal revascularization. The aim of this study was to assess the effects of angioscopic preparation on endothelial integrity and smooth muscle cell (SMC) behavior in an established organ culture model of human saphenous vein (HSV). METHODS: HSV was harvested from 12 patients during bypass surgery before and after angioscopic preparation. Endothelial integrity was evaluated by immunohistochemical staining with JC-70 and scanning electron microscopy (SEM); remaining segments of pre- and postangioscopy vein were maintained in culture for 14 days in medium supplemented with 30% fetal calf serum. Viability was confirmed by measurement of tissue adenosine triphosphate on day 14 and thickness of the neointima was measured by computerized image analysis of histologic sections. Monoclonal antibodies to proliferating cell nuclear antigen (PCNA) were used as an immunohistochemical marker for proliferating SMCs. RESULTS: There was a significant reduction in the percentage staining by JC-70 (71.3% versus 20.4%) in pre- versus postangioscopy vein (p = 0.002 by Wilcoxon's rank test; n = 12). This was supported by SEM images. Despite this, there were no significant differences between the pre- and postangioscopy HSVs after 14 days of culture with respect to neointimal thickness (61 versus 56 microns) and staining with PCNA (4.80 versus 4.08 nuclei per 10 microns), all according to Wilcoxon's rank test. CONCLUSIONS: Angioscopic vein graft preparation is associated with endothelial cell loss but does not induce additional neointimal hyperplasia in HSV in vitro. These results suggest that angioscopic manipulation does not alter SMC behavior.     

Insertion signal sequence fused to minimal peptides elicits specific CD8+ T-cell responses and prolongs survival of thymoma-bearing mice

CD8+ T-lymphocytes (TCD8+) recognize minimal peptides of 8-10 residues which are the products of intracellularly processed proteins and are presented at the cell surface by major histocompatibility complex class I molecules. An important step in this process is the translocation of processed proteins from the cytosol across the endoplasmic reticulum membrane, mediated by transporter associated with antigen-processing proteins or alternatively by endoplasmic reticulum-insertion signal sequences located at the NH2-terminus of the precursor molecules. We report here that the addition of an endoplasmic reticulum-insertion signal sequence at the NH2-terminus of TCD8+ epitopes from chicken ovalbumin (amino acids 257-264) or a naturally occurring tumor antigen expressed by the murine mastocytoma P815 (P1A amino acids 35-43) significantly enhanced the priming of specific TCD8+ in vivo. The signal sequence did not enhance peptide immunogenicity by merely increasing the hydrophobicity of the peptide, since ovalbumin amino acids 257-264 peptide with the signal sequence at its COOH-terminus did not demonstrate enhanced efficacy. The signal sequence did not act as a helper epitope, since TCD8+ responses were not diminished in class II-deficient transgenic mice or in mice depleted of CD4+ T-cells in vivo. Importantly, a single immunization with the fusion peptide significantly prolonged survival of mice challenged with E.G7OVA, a thymoma transfected with the complementary DNA of chicken ovalbumin.     

Thermodynamics of several lewis-acid-base stabilized transition metal alloys

High-temperature (1425 to 2750 K) thermodynamic activities of one or both components of twenty-five binary alloys of a group IVB-VIB element (Ti, Zr, Hf, Nb, Ta, or W) with a platinum group element (Ru, Os, Ir, Pd, Pt, or Au) have been determined by equilibrating the alloy with the appropriate carbide and graphite, equilibrating with the nitride and nitrogen gas, or measuring the partial vapor pressure(s) thermogravimetrically or mass spectrometrically. The extraordinary stability of this class of transition metal alloy is attributed to a generalized Lewis-acid-base interaction involving valenced electrons, and the results of these investigations are interpreted within the context of this effect. Among the conclusions made are that a non-spherically-symmetrical crystal field significantly reduces the bonding effectiveness of certain valenced orbitals; the effect of the extent of derealization of these orbitals is also considered. Formerly Graduate Student Research Assistant, Materials and Molecular Research Division, Lawrence Berkeley Laboratory, and Department of Chemistry, University of California, Berkeley