Role of Superoxide Dismutase in Ischemic Brain Injury: A Study Using SOD-1 Transgenic Mice

1. Nitric oxide radicals (NO) play an important role in the pathophysiology of focal cerebral ischemia.2. Vascular NO can reduce ischemic brain injury by increasing CBF, whereas neuronal NO may mediate neurotoxicity following brain ischemia, mainly by its reaction with superoxide to generate peroxynitrite.3. These findings could contribute to a strategy for the treatment of cerebral ischemia.     

Rapid identification of Leishmania species from formalin-fixed biopsy samples by polymorphism-specific polymerase chain reaction

The precise identification and classification of Leishmania species is important for public health surveillance since different species cause different clinical features of the disease. A highly specific polymerase chain reaction (PCR) panel was developed to enable the identification of the five major Leishmania species that cause New World cutaneous leishmaniases. The primers used for this panel were designed to distinguish the polymorphism in sequences of commonly amplified DNA bands of the parasites produced by arbitrarily primed PCR. These polymorphism-specific PCR diagnoses were performed with formalin-fixed biopsy specimens of the leishmanial lesions from four patients in Ecuador and one hamster skin lesion, and these lesions were determined to be caused by Leishmania (Viannia) panamensis, L. (Leishmania) mexicana, and L. (L.) amazonensis. The PCR panel may offer an important and practical approach to the standardized identification of Leishmania species in field examinations.     

Protein H — a surface protein of Streptococcus pyogenes with separate binding sites for lgG and albumin

Protein H, a molecule expressed at the surface of some strains of Streptococcus pyogenes, has affinity for the constant (lgGFc) region of immunoglobulin (lg) G. In absorption experiments with human plasma, protein H–sepharose could absorb not only lgG but also albumin from plasma. The affinity constant for the reaction between albumin and protein H was 7.8 × 10⁹M⁻¹, which is higher than the affinity between lgG and protein H (K_a= 1.6 × 10⁹ M⁻¹). Fragments of protein H were generated with deletion plasmids and polymerase chain reaction (PCR) technology. Using these fragments in various protein–protein interaction assays, the binding of albumin was mapped to three repeats (C1–C3) in the C-terminal half of protein H. On the albumin molecule, the binding site for protein H was found to overlap the site for protein G, another albumin- and lgGFc-binding bacterial surface protein. Aiso lgGFc-binding could be mapped with the protein H fragments and the region was found N-terminally of the C repeats. A synthetic peptide (25 amino acid residues long) based on a sequence in this region was shown to inhibit the binding of protein H to immobilized lgG or lgGFc. This sequence was not found in previously described lgGFc-binding proteins. However, two other cell surface proteins of S. pyogenes exhibited highly homologous regions. The results identify lgGFc- and albumin binding regions of protein H and further define and emphasize the convergent evolution among bacterial surface proteins interacting with human plasma proteins.     

Changes in magnetic resonance images in human skeletal muscle after eccentric exercise

To investigate the time-course of changes in transverse relaxation time (T₂) and cross-sectional area (CSA) of the quadriceps muscle after a single session of eccentric exercise, magnetic resonance imaging was performed on six healthy male volunteers before and at 0, 7, 15, 20, 30 and 60 min and 12, 24, 36, 48, 72 and 168 h after exercise. Although there was almost no muscle soreness immediately after exercise, it started to increase 1 day after, peaking 1–2 days after the exercise (P<0.01). Immediately after exercise, T₂ increased significantly in the rectus femoris, vastus lateralis and intermedius muscles (P<0.05) and decreased quickly continuing until 60 min after exercise. At and after the 12th h, a significant increase was perceived again in the T₂ values of the vastus lateralis and intermedius muscles (P<0.01) [maximum 9.3 (SEM 2.8)% and 10.9 (SEM 2.2)%, respectively]. The maximal values were exhibited at 24–36 h after exercise. In contrast, the rectus femoris muscle showed no delayed-stage increase. Also, in CSA, an increase after 12 h was observed in addition to the one immediately after exercise in the vastus lateralis, intermedius and medialis and quadriceps muscles as a whole (P < 0.01), reaching the maximal values at 12–24 h after exercise. The plasma creative kinase activity remained unchanged up to 24 h after and then increased significantly 48 h after exercise (P < 0.05). Beginning 12 h after exercise, the subjects whose T₂ and CSA increased less than the others displayed a faster decrease in muscle soreness. These results suggested that T₂ and CSA displayed bimodal responses after eccentric exercise and the time-courses of changes in them were similar to those in muscle soreness.     

Studies on the biosynthesis of ralfuranones in Ralstonia solanacearum

Ralfuranones, aryl-furanone secondary metabolites, are involved in the virulence of Ralstonia solanacearum in solanaceous plants. Ralfuranone I (6) has been suggested as a biosynthetic precursor for other ralfuranones; however, this conversion has not been confirmed. We herein investigate the biosynthesis of ralfuranones using feeding experiments with ralfuranone I (6) and its putative metabolite, ralfuranone B (2). The results obtained demonstrated that the biosynthesis of ralfuranones proceeded in enzymatic and non-enzymatic manners.