Biochemical similarity of Schizosaccharomyces pombe ras1 protein with RAS2 protein of Saccharomyces cervisiae.

Schizosaccharomyces pombe contains single ras oncogene homologue, ras1, that functions in the signal transduction pathway conducting the cell's mating processes. To understand the biochemical basis of yeast ras proteins, we have purified the ras1 protein and compared the major biochemical constants with those of RAS2 protein from Saccharomyces cerevisiae and mammalian ras proteins. The purified ras1 protein showed a remarkably high Kd value for GDP binding (178 nM) and for binding with ATP. In contrast, the Kd value for GTP binding and the rate of GTPase activity were 64 nM and 77 x 10(-6) s-1 at 37 degrees C, respectively; both were higher than normal p21ras protein, but at the same level as the RAS2 protein. We directly measured rate of GTP binding and GDP binding which were 3.9 x 10(-3) s-1 and 1.8 x 10(-3) s-1 at 30 degrees C, respectively. On the other hand, exchange rates between bound and free nucleotides remained almost constant throughout the tested combination of GTP and GDP, and were several-fold lower than the binding rate. These results suggest that the release of the guanine nucleotide is the rate-limiting step in the ras-GTP/GDP cycle. As a whole, the biochemical properties of the ras1 protein are close to those of the RAS2 protein, although these two proteins function differently in the signal transduction pathway in the cells.

[Effect of 1 alpha-OH-D3 on the bone metabolism after high tibial osteotomy].

The effect of 1-hydroxycholecalciferol (1 alpha-OH-D3) on bone metabolism during osteotomized bone healing was investigated. The study based on 19 female patients with gonarthrosis who underwent the high tibial osteotomy. In 10 selected randomly from these patients 1 alpha-OH-D3 (1.0 micrograms/day) was administered before and after the surgery. After operation the changes in bone density (by MD-method) and biochemical parameters were followed. In the non-treated group the serum level of [Ca] x [P] product temporarily decreased at 3 days after surgery. Average bone density at two months after the surgery was 8.8% lower than the preoperative value. In contrast, 1 alpha-OH-D3 treated group showed significantly less decrease of serum [Ca] x [P] product at the third day than the control group and no significant decrease of bone density at two months after the operation. From these results, it was concluded that the 1 alpha-OH-D3 suppresses the decrease of serum Ca and P level and systemic osteopenia after osteotomy and may have an beneficial effect on fracture healing.

Tissue specific expression of the plasma glutathione peroxidase gene in rat kidney.

Rat plasma glutathione peroxidase (GSH-Px) was purified 1,400-fold from rat serum by a combination of phenyl Sepharose, DEAE Sephacel, blue Sepharose and Sephacryl S-200 column chromatographies. The purified GSH-Px migrated as a single band corresponding to a molecular weight of 22,500 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme was used for the immunization of chickens to obtain a specific antibody and for determination of its amino acid sequence. Two overlapping cDNA clones for rat plasma GSH-Px were isolated from a placental cDNA library. The composite nucleotide sequence is 1,529 base-pairs long and encodes 226 amino acids. The deduced amino acid sequence completely coincided with the sequences of five individual peptide fragments derived from the purified plasma GSH-Px on digestion with lysyl endopeptidase. In order to identify the tissue(s) generating this plasma GSH-Px, immunoblot analysis was performed on homogenates prepared from 13 tissues. A single immunoreactive band of 22.5 kDa, corresponding to plasma GSH-Px, was detected for the kidney homogenate. A much fainter band was observed for the lung preparation, but liver, spleen, bone marrow, and other tissues examined were negative. Northern blot analysis further revealed that the expression level of the plasma GSH-Px gene was high in kidney and low in lung. No transcript was detected in liver or spleen. These results indicate that plasma GSH-Px is predominantly synthesized and secreted by renal cells.

Problems with repeated arthroscopic surgery in the discoid meniscus.

To identify the main causes of repeated arthroscopic surgery of the knee joint and to find out the points of therapeutic approaches, we evaluated 139 patients who underwent arthroscopic meniscectomy in our department and in affiliated hospitals between 1983 and 1987. Two or more arthroscopic surgeries were needed in 9 knees of 8 patients (6.5%). In 5 knees with no known injuries, the primary reason for repeated surgery was horizontal tears of remnant meniscus after partial resection of lateral discoid meniscus. The most appropriate initial treatment for lateral discoid menisci in cases without tear should be observation of the clinical course with minimal treatment using diagnostic arthroscopy.

Characterization of metallothionein cDNAs induced by cadmium in the nematode Caenorhabditis elegans.

cDNAs of metallothioneins (MTs) in the nematode Caenorhabditis elegans were characterized. The MT-II clone encodes 62 amino acid residues and the predicted Mr is 6462. The MT-I clone contains an additional 12 residues at the C-terminal end, and the predicted Mr is 7959. There is a considerable similarity between MT-I and MT-II. Both of these proteins are cysteine-rich and, with a few exceptions, show a good alignment of cysteine residues. No obvious sequence relationship in the coding region was discernible between C. elegans MTs and mammalian MTs, aside from Cys-Cys, Cys-Xaa-Cys, and Cys-Xaa-Xaa-Xaa-Cys segments. However, 3'-untranslated region of cDNAs of C. elegans MT-I and -II have some consensus sequences found in mammalian MT cDNAs, suggesting that these regions may have some roles in the regulation of MT-gene expression.

Herpes zoster ophthalmicus with delayed contralateral hemiparesis.

A 35-year-old previously healthy woman developed left hemiparesis sixteen weeks after the onset of right herpes zoster ophthalmicus. Cerebral angiography showed complete occlusion of right middle cerebral artery at the origin and segmental narrowing of the right posterior cerebral artery. Computerized tomography (CT) and magnetic resonance imaging (MRI) also revealed a right hemispheric lesion consistent with angiographic findings. Reports from the literature along with the present case suggest that arteritis followed by cerebral infarction is the most probable cause of delayed contralateral hemiparesis.

Molecular cloning of cDNA coding for rat plasma glutathione peroxidase.

The plasma glutathione peroxidase (PGSH-PO), which is different from erythrocyte glutathione peroxidase (EGSH-PO) in immunochemical property and substrate specificity, was purified from male Wistar rat serum. The amino acid sequence of 5 independent peptides were determined and a cDNA clone for this enzyme was isolated from placental cDNA library. The nucleotide sequence of the cDNA revealed that, similar to EGSH-PO cDNA, the seleno-cysteine was genetically encoded by "TGA" codon. On comparing the nucleotide sequences of EGSH-PO and PGSH-PO, no significant homology was found in the vicinities of "TGA" codons of both enzymes.

[Electromyographic studies on the musculature of the knee with osteoarthritis].

Action of muscles around the knee in walking on a treadmill was studied by electromyography in young normal subjects and in patients with osteoarthritis of the knee. The followings were concluded. The quadriceps femoris stabilizes the knee joint in the sagittal plane, showing higher activity with an increase in faster walking. The tensor fasciae latae and gluteus medius muscles are important in the frontal plane stability, working primarily in the slow walk. Hamstring controls finely the knee joint under various circumstances. The muscle of those with osteoarthritis of the knee on walking slowly shows a similar pattern of activity as that of the normal fast walking. All of the muscles apparently are put into stabilizing mechanism of the joint in the stance phase leaving less reserve in their activity. A forward bending in posture results in changes of muscle activity around the knee, which can play an important role in the development of osteoarthritis of the knee.