Esr and Spin-Trapping Study of Free Radicals in γ-Irradiated Solid Lysozyme

Free radicals produced by γ-irradiation of solid lysozyme were investigated by a technique combining ESR, spin-trapping and enzymatic digestion. MNP and DMPO were used as spin-trapping reagents. The solid lysozyme was first γ-irradiated and then dissolved in an aqueous solution containing the spin-trapping reagent to stabilize free radicals. The spin adducts of lysozyme were digested to oligopeptides to get ESR spectra having a well-resolved hyperfine structure. The ESR spectra obtained showed that carbon-centered radicals, CH-, at the side chains of amino acids, and thiyl radicals, -CH₂-_-S^-, at disulfide bridges were produced in γ-irradiated solid lysozyme.     

Characterization of a suppressor cell line which downgrades experimental autoimmune uveoretinitis in the rat

A Ts lymphocyte line was isolated from spleens of rats primed with the retinal soluble Ag (SAg) in the anterior chamber of the eye. This line could inhibit in vitro SAg-driven proliferation of uveitogenic Th lymphocytes, in a radioresistant, Ag-independent manner. Adoptively transferred Ts line cells were found to downgrade experimental autoimmune uveoretinitis in actively immunized syngeneic recipients. The initial surface phenotype (OX8+) of the Ts line was unstable in vitro, however, the cells expressed suppressor function irrespective of phenotype. The mechanism of suppression did not appear to involve consumption of IL-2 or direct cytolysis of uveitogenic Th lymphocytes, but rather the production of a soluble suppressor factor. These findings may suggest an in vivo role for suppressor lymphocytes, capable of inhibiting primed Th cells, in the regulation of experimental autoimmune uveoretinitis.     

tra-2 encodes a membrane protein and may mediate cell communication in the Caenorhabditis elegans sex determination pathway.

The Caenorhabditis elegans sex-determining gene, tra-2, promotes female development in XX animals. In this paper we report the cDNA sequence corresponding to a 4.7 kb tra-2 mRNA and show that it is composed of 23 exons, is trans-spliced to SL2, and contains a perfect direct repeat in the 3' untranslated region. This mRNA is predicted to encode a 1475 amino acid protein, named pTra2A, that has a secretory signal and several potential membrane-spanning domains. The molecular analysis of tra-2 loss-of-function mutations supports our open reading frame identification and suggests that the carboxy-terminal domain is important for tra-2 activity. We propose that in XX animals the carboxy-terminal domain of pTra2A negatively regulates the downstream male promoting fem genes. In XO animals, tra-2 is negatively regulated by her-1, which acts cell nonautonomously. Because hydropathy predictions suggest that pTra2A is an integral membrane protein, pTra2A might act as a receptor for the her-1 protein. We propose that in XO animals, the her-1 protein promotes male development by binding and inactivating pTra2A. The role of cell communication in C. elegans sex determination might be to ensure unified sexual development throughout the animal. If so, then regulation of sexual fate by her-1 and tra-2 might provide a general model for the coordination of groups of cells to follow a single cell fate.     

Special AT‐rich sequence binding protein 1 is required for maintenance of T cell receptor responsiveness and development of experimental autoimmune encephalomyelitis

The genome organizer special AT‐rich sequence binding protein 1 (SATB1) regulates specific functions through chromatin remodeling in T helper cells. It was recently reported by our team that T cells from SATB1 conditional knockout (SATB1cKO) mice, in which the Satb1 gene is deleted from hematopoietic cells, impair phosphorylation of signaling molecules in response to T cell receptor (TCR) crosslinking. However, in vivo T cell responses upon antigen presentation in the absence of SATB1 remain unclear. In the current study, it was shown that SATB1 modulates T cell antigen responses during the induction and effector phases. Expression of SATB1 was upregulated in response to TCR stimulation, suggesting that SATB1 is important for this antigen response. The role of SATB1 in TCR responses and induced experimental autoimmune encephalomyelitis (EAE) was therefore examined using the myelin oligodendrocyte glycoprotein peptide 35‐55 (MOG35‐55) and pertussis toxin. SATB1cKO mice were found to be resistant to EAE and had defects in IL‐17‐ and IFN‐γ‐producing pathogenic T cells. Thus, SATB1 expression appears necessary for T cell function in the induction phase. To examine SATB1 function during the effector phase, a tamoxifen‐inducible SATB1 deletion system, SATB1cKO‐ER‐Cre mice, was used. Encephalitogenic T cells from MOG35‐55‐immunized SATB1cKO‐ER‐Cre mice were transferred into healthy mice. Mice that received tamoxifen before the onset of paralysis were resistant to EAE. Furthermore, no disease progression occurred in recipient mice treated with tamoxifen after the onset of EAE. Thus, SATB1 is essential for maintaining TCR responsiveness during the induction and effector phases and may provide a novel therapeutic target for T cell‐mediated autoimmune diseases.     

Exposure of Astrocytes to Hypoxia/Reoxygenation Enhances Expression of Glucose-Regulated Protein 78 Facilitating Astrocyte Release of the Neuroprotective Cytokine Interleukin 6

Abstract: Astrocytes exposed to hypoxia (H) or hypoxia/reoxygenation (H/R) maintain cell viability and display changes in protein biosynthesis. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of metabolically labeled astrocytes exposed to H showed induction of an ≈78-kDa polypeptide that demonstrated sequence identity with glucose-regulated protein (GRP) 78. Cell lysates from H/R astrocytes displayed induction of neuroprotective interleukin (IL) 6, which was present in a high-molecular-weight complex also containing GRP78, suggesting that GRP78 might be functioning as a chaperone during cellular stress consequent on H/R. Introduction of anti-sense oligonucleotide to GRP78 into astrocytes prevented expression of the protein and suppressed H/R-induced astrocyte release of IL-6 by ≈50%. These data indicate that modulation of astrocyte properties during oxygen deprivation results, in part, from intracellular glucose depletion and subsequent expression of GRP78, which sustains generation of neuroprotective IL-6 under the stress of H/R.     

α-Phenyl N-Tert-Butyl Nitrone (PBN) Increases the Cortical Cerebral Blood Flow by Inhibiting the Breakdown of Nitric Oxide in Anesthetized Rats

The effects of intravenous administration of a-phenyl N-tert-butyl nitrone (PBN) on cortical cerebral blood flow (CBF) were examined in Wistar rats under pentobarbital anesthesia and artificial ventilation. The cortical CBF in parietal cortex was measured by laser Doppler flowmetry. Intravenous administrations of 2 mg/kg and 20 mg/kg of PBN dose-dependently produced significant increases in cortical CBF and decreases in systemic blood pressure (BP). To examine whether these increased responses in cortical CBF produced by PBN were associated with the vasodilatation system of nitric oxide (NO), the NO synthase inhibitor L-N^G-nitroarginine (L-NOArg), which is an analog of L-arginine, was used to inhibit the NO-related-vasodilatative system. Since the PBN-induced responses in the cortical CBF were much attenuated in L-NOArg-treated rats (30 mg/kg, iv.), it was inferred that NO-related vasodilatation was strongly associated with the PBN-induced increase in cortical CBF.     

A Dithiothreitol-Sensitive Tetrameric Protease from Spinach Thylakoids Has Polyphenol Oxidase Activity

Polyclonal antibody raised against a dithiothreitol-sen-sitivetetrameric protease (DSTP) from PSII membranes specificallyinhibited the polyphenol oxidase (PPO) activity of spinach thylakoids.DSTP was copurified with PPO activity on an affinity columnprepared with antibody against DSTP. These results suggest thatDSTP and PPO are the same protein. During purification of DSTP,Tween 20 was essential for stabilization of the protein, whichwas degraded in the absence of the detergent. Gel-filtrationchromatog-raphy of the purified DSTP revealed the presence of230-kDa (tetramer) and 60-kDa (monomer) species. The coppercontent of monomer species was determined to be 0.4 Cu atomper protein molecule, when the molecular weight of the proteinwas calculated to be 62,243, which is the value reported forspinach PPO [Hind et al. (1995) Biochemistry 34: 8157]. PurifiedDSTP caused the degradation as well as the dimerization of theextrinsic 23-kDa protein of PSII. The degradation of the proteinwas suppressed under anaerobic conditions induced by the presenceof glucose oxidase and glucose together. This fact suggeststhat oxygen molecules are involved in the proteolytic reactionand that the proteolytic activity and PPO activity may be correlatedwith each other. (Received September 27, 1996; Accepted December 4, 1996)     

Urinary Dysfunction in Progressive Supranuclear Palsy Compared with Other Parkinsonian Disorders

Background

Autonomic urinary dysfunction affects patients with progressive supranuclear palsy (PSP); however, the severity and prevalence of urinary dysfunctions in these patients compared with those observed in patients with Parkinson’s disease (PD) and multiple system atrophy (MSA) are unknown.

Objective

We compared urinary dysfunction characteristics in patients with PSP, PD, and MSA.

Patients and Methods

Forty-seven patients who satisfied the probable or possible criteria of the National Institute for Neurological Diseases and Stroke and Society for PSP were assessed using the urinary symptoms questionnaire and the urodynamic study at Chiba and Toho Universities (n = 26 and 21, respectively). The results were compared with those of patients with PD and MSA (n = 218 and 193, respectively).

Results

The mean disease duration of PSP and the mean age were 2.97 ± 0.26 and 71.4 ± 0.88 years, respectively. The mini-mental state examination and frontal assessment battery scores were 22.6 ± 0.70 and 10.7 ± 0.49, respectively. Urinary storage and voiding symptoms were observed in 57% and 56% of patients with PSP, respectively. Detrusor overactivity in the urodynamic study was detected in 81% of patients with PSP, which was slightly more than that found in patients with PD (69%) and MSA (67%); however, this was not statistically significant. Postvoid residual volume in patients with PSP was significantly more than that in patients with PD (P < 0.01), but was equivalent to that in patients with MSA.

Conclusions

The present study demonstrated that patients with PSP experienced various urinary dysfunctions. Urinary storage dysfunction in patients with PSP was not different from that in patients with PD or MSA, whereas urinary voiding dysfunction in patients with PSP was milder than that in patients with MSA and more severe than that in patients with PD. These features should be taken into account for the differentiation of PSP from PD and MSA.     

Evidence for the formation of strand-break precursors in hydroxy-attacked thymidine 5'-monophosphate by the spin trapping method

A method combining spin trapping, ESR, and HPLC was employed to obtain evidence for the formation of sugar radicals in OH-attacked TMP with special emphasis on the detection of strand-break precursors of DNA. OH radicals were produced by irradiating an N2O-saturated aqueous solution with X-rays. When an N2O-saturated aqueous solution containing TMP and a spin trapping reagent, MNP, was irradiated with X-rays, it was estimated on the basis of theoretical calculations using rate constants that 94% of the TMP radicals were induced by OH radicals. Since several spin adducts between TMP radicals and MNP, as well as the byproducts of the spin trapping reagent itself, were produced, reverse-phase HPLC was used to separate them. The presence of six spin adducts was confirmed by ESR examination. Further examination of these spin adducts by UV absorbance spectrophotometry showed the presence of a chromophore at 260 nm in three adducts. Since a gradual increase in the release of unaltered base from these adducts was observed when they were allowed to stand for 0-22 h at room temperature, they could be regarded as the spin adducts of sugar radicals and MNP. ESR spectra from the spin adducts were consistent with hydrogen abstraction radicals at the C1', C4', and C5' positions of the sugar moiety. These radicals appeared to be precursors of AP sites and strand breaks. In addition to these spin adducts, ESR spectra that were consistent with the spin adducts of base radicals (the C5 and C6 radicals) and MNP were observed.     

Induction of DNA double-strand breaks in Chinese hamster V79 cells by 2-chlorodeoxyadenosine

2-Chlorodeoxyadenosine was found to induce DNA double-strand breaks as well as cell death in log-phase Chinese hamster V79 cells. The induction of DNA double-strand breaks, measured by a neutral elution technique, was observed after a 2-h incubation of the cells in the presence of 5 microM of 2-chlorodeoxyadenosine, but these breaks were almost rejoined by a subsequent 1-h incubation, even though this drug was present in the medium during incubation. This repair was prevented by the addition of nicotinamide, which is known to inhibit poly(ADP-ribose) synthesis that is strongly associated with the DNA ligation, but not prevented by the addition of 9-beta-D-arabinofuranosyladenine (araA), which is known to inhibit DNA polymerization. These results suggest that the repair of CdA-induced double-strand breaks is achieved by ligation alone without DNA polymerization. When 35 microM of cycloheximide and 1.3 mM of dibutyryl cAMP were added to the medium, it was found that the induction of double-strand breaks by 2-chlorodeoxyadenosine was suppressed, while the cytotoxicity of 2-chlorodeoxyadenosine measured by colony-forming ability was not interfered with. These results suggest that the induction of DNA double-strand breaks is not associated with the cytotoxicity of this drug.