Molecular characterization and physiological role of ascorbate peroxidase from halotolerant Chlamydomonas sp. W80 strain.

A cDNA clone encoding an ascorbate peroxidase was isolated from the cDNA library from halotolerant Chlamydomonas W80 by a simple screening method based on the bacterial expression system. The cDNA clone contained an open reading frame encoding a mature protein of 282 amino acids with a calculated molecular mass of 30,031 Da, preceded by the chloroplast transit peptide consisting of 37 amino acids. In fact, ascorbate peroxidase was localized in the chloroplasts of Chlamydomonas W80 cells; the activity was detected in the stromal fraction but not in the thylakoid membrane. The deduced amino acid sequence of the cDNA showed 54 and 49% homology to chloroplastic and cytosolic ascorbate peroxidase isoenzymes of spinach leaves, respectively. The enzyme from Chlamydomonas W80 cells was purified to electrophoretic homogeneity. The molecular properties of the purified enzyme were similar to those of the other algal ascorbate peroxidases rather than those of ascorbate peroxidases from higher plants. The enzyme was relatively stable in ascorbate-depleted medium compared with the chloroplastic ascorbate peroxidase isoenzymes of higher plants. The presence of NaCl (3%) as well as of beta-d-thiogalactopyranoside was needed for the expression of Chlamydomonas W80 ascorbate peroxidase in Escherichia coli.

A region of the muscarinic-gated atrial K+ channel critical for activation by G protein beta gamma subunits.

Complementary DNAs encoding two types of inwardly rectifying K+ channels, GIRK1 and IRK1, have been cloned from rat atrium and mouse macrophage, respectively. GIRK1 expressed in Xenopus oocytes was activated by acetylcholine when m2 muscarinic acetylcholine receptor was coexpressed. The acetylcholine-induced activation of GIRK1 was enhanced by coexpression with the G protein beta 1 gamma 2 subunit but not the beta 1 gamma 1 or alpha subunits. Deletion of the C-terminus of GIRK1 impaired the channel activation associated with the beta 1 gamma 2 subunit. Moreover, replacement of the C-terminus of IRK1 with that of GIRK1 produced a chimera channel that was activated by the beta 1 gamma 2 subunit, whereas intact IRK1 was not activated by the beta 1 gamma 2 subunit. These findings define the C-terminus of GIRK1 as a regulatory region for the G protein beta gamma subunit.

[Urinary managements of 332 stroke patients in the chronic phase].

Urinary managements of 332 stroke patients in the chronic phase were performed at Bobath hospital. Cerebrovascular accidents (CVA) were caused by cerebral infarction in 178 (53.6%), intracerebral hemorrhage in 123 (37.1%) and subarachnoid hemorrhage in 31 (9.3%). Voluntary urination appeared in 124 patients before treatment, however in 29 of them occasional incontinence were observed. One hundred forty-three patients used diapers and 64 were controlled by indwelling catheters. The remaining one patient was treated by intermittent catheterization. Sixty-two patients who seemed to have communicative abilities in daily living were assessed with regard to their cerebrovascular dementia by Hasegawa's Dementia Rating Scale. After treatment 235 patients (70.8%) were able to urinate voluntarily, and only 15 of them remained incontinent and could use small pads successfully. TURP was effective for the stroke patients with benign prostatic hypertrophy (BPH) or bladder neck sclerosis (BNS). Fifty-three patients (16.0%) with persistent urinary incontinence were managed by diapers or a system of condom drainage. Thirty-nine patients (11.7%) were kept dry with intermittent catheterization at home, and long-standing use of indwelling catheters were required in the remaining 5 patients (1.5%). These results indicate that the lower level of activity, mobility and mental state tended to prevent the stroke patients from improvement of urinary disorders.