Omnipotent Suppressors Effective in psi Strains of SACCHAROMYCES CEREVISIAE: Recessiveness and Dominance.

We have characterized recessive and dominant omnipotent suppressor mutations obtained by conversion of the leu2-1 UAA mutation and the met8-UAG mutation in a psi(+) strain of Saccharomyces cerevisiae. The suppressors that act recessively upon these markers fell into two complementation groups; the sup47 and sup36 suppressors show linkage to the tyr1 locus and the aro1 locus, respectively. Of the suppressors acting dominantly upon both markers, those linked to the tyr1 locus are alleles of the SUP46 ribosomal mutation. The sup47 suppressors differ from the SUP46 suppressors not only in their suppressor activities in heterozygous diploids but also in their map positions relative to the tyr1 locus and their effects on the S11 ribosomal protein. The remaining dominant suppressors are not alleles of sup36 as judged by linkage analysis. The recessive suppressors and the dominant suppressors also differ in their effects on cell growth.

An actin point-mutation neighboring the 'hydrophobic plug' causes defects in the maintenance of cell polarity and septum organization in the fission yeast Schizosaccharomyces pombe.

The fission yeast cps8 mutation gives rise to abnormally enlarged and dispolarized cells, each of which contains several nuclei with aberrant multisepta. Molecular cloning and sequence analysis of the cps8 gene indicated that it encodes an actin with an amino acid substitution of aspartic acid for glycine at residue 273 in the hydrophobic loop that is located between actin subdomains 3 and 4. Fluorescence microscopy using phalloidin and anti-actin antibody revealed changes in the F-actin structure and distribution in the mutant cells. These results indicate that the hydrophobic loop plays an essential role for creating normal F-actin structure, only by which cell polarity and the late mitotic events can be maintained properly.

Ultrastructure of cell wall of the cps8 actin mutant cell in Schizosaccharomyces pombe.

A Schizosaccharomyces pombe cps8 mutant, of which the gene encodes a mutant actin with an amino acid substitution of Asp for Gly(273) [J. Ishiguro and W. Kobayashi (1996) FEBS Lett. 392, 237-241], was used to determine the role of the actin cytoskeleton in cell wall formation. In the cps8 mutant cells, atomic force microscopic and scanning electron microscopic images showed abnormal depolarized and branched morphology. Fibrous material covered a part of the surface of growing cps8 cells. Transmission electron microscopic images showed variable thickness of the cell wall due to multilayering of cell wall materials, and aberrant multisepta due to diagonal growth of the primary septum, whereas the normal primary septum grows at a right angle from the cortex. This abnormal septum formation may induce abnormality of the cell with multinuclei and/or multisepta, caused by non-separation of daughter cells. These results indicate that actin plays an important role in cell wall and septum formation.

Combination therapy of transcatheter chemoembolization and percutaneous ethanol injection therapy for unresectable hepatocellular carcinoma.

The therapeutic effectiveness of a combination therapy--pretreatment with transcatheter arterial chemoembolization (TACE) followed by percutaneous ethanol injection (PEI) therapy--for large (> 3 cm in diameter) unresectable hepatocellular carcinoma (HCC) was compared with that of TACE alone. PEI therapy was performed in 24 cases of unresectable HCC that had previously been treated with TACE using doxorubicin 30-60 mg or epirubicin 50-90 mg. In all, 2-10 ml of 90% ethanol mixed with carbocaine was repeatedly injected through a 21-gauge, closed-end needle (PEIT needle) for a median of 3.6 injections and 31.1 ml of ethanol. As adverse effects, transient localized pain and a burning sensation were observed in 75.0% of the cases; fever, in 66.7%; and transient hypotension, in two cases. A small unresectable tumor is a good indication for PEI therapy. In cases with a larger tumor, i.e., measuring more than 3 cm in diameter, or multiple tumors, the 1-year survival rate obtained with this combination therapy, i.e., TACE and PEI, was 87.0%, and the 2-year survival rate was 65.2%. These rates were greater than those obtained with TACE alone. Accordingly, additional PEI therapy was effective for larger tumors and multiple tumors previously treated with TACE.

Genetic control of fission yeast cell wall synthesis: the genes involved in wall biogenesis and their interactions in Schizosaccharomyces pombe.

The fungal cell wall is an essential structure which protects cells from various environmental stresses such as hyper- or hypo-osmosis, and endows them with specific morphology in response to their life or cell division cycle. In addition, the cell wall has a variety of enzymatic activities per se, which are required for nutritional uptake, secretion, and cell adhesion including mating processes. In addition to these cytological interests, clinical demands to clarify the regulatory mechanisms of cell wall synthesis have been increasing, since the cell wall is a unique and effective target of antifungal agents. However, the molecular mechanisms are poorly understood at present, although the role of several signal transduction pathways have recently been implicated in regulation. In this review, the author focuses on genes and their interactions which are involved in fission yeast cell wall biogenesis.

Characterization of a fission yeast mutant which displays defects in cell wall integrity and cytokinesis.

The fission yeast cps6-153 mutant was originally isolated based on its hypersensitivity to the spindle poison isopropyl N-3-chlorophenyl carbamate (CIPC). The mutant also shows defects in both cell wall integrity and cytokinesis, resulting in the accumulation of unseparated cells with weakened cell walls. The arrested cells display a disoriented alignment of cytoplasmic microtubules. When the mutant cells are cultivated at high temperature (35 degrees C), both cell walls and septa become very thick. Electron microscopy revealed the disorganized structure of the thickened cell walls and septa, in which fibrillar components were not completely masked with an amorphous matrix. rad25+ was cloned from a genomic library by complementation of the mutant phenotypes, suggesting the involvement of Rad25p, one of two 14-3-3 proteins in S. pombe, in the pathway of cell wall integrity and cytokinesis.

Is diabetic heart muscle disease related to cardiac ischemia or autonomic neuropathy?

Whether diabetic heart muscle disease is related to cardiac ischemia or autonomic neuropathy was investigated employing thallium-201 and [123I]meta-iodobenzylguanidine (MIBG) myocardial scintigraphy. Among ischemic hearts, displayed by TI201 scintigraphy, a distinctly dilated and hypokinetic left ventricle could not be detected. In autonomically denervated hearts, however, well demonstrated by MIBG imaging, distinct dysfunction was found. But, even in these hearts, interacting effects of some concomitant complications could not be excluded.

Antibacterial and pharmacokinetic properties of M14659, a new injectable semisynthetic cephalosporin.

In vitro and in vivo antibacterial activities and pharmacokinetics of M14659 were investigated. In vitro activity of M14659 was superior to that of ceftazidime against Staphylococcus aureus. Against Gram-negative bacteria except Pseudomonas aeruginosa, its activity was almost equal to that of ceftazidime. M14659 was more active against P. aeruginosa including multi-drug resistant strains than cefsulodin, cefoperazone or ceftazidime. Affinities of M14659 for penicillin-binding proteins (PBPs) of Escherichia coli and P. aeruginosa were 2 to 14 times higher for PBP-1A and PBP-1B than found for ceftazidime, and almost the same for PBP-3. In vivo activity of M14659 against S. aureus was superior to that of cefamandole, cefotaxime or ceftazidime. Against Gram-negative bacteria including P. aeruginosa, M14659 was 2 to 220 times more active than cefotaxime or ceftazidime. Plasma half-life of M14659 in mice was about 3 times longer than that of ceftazidime. M14659 administered intravenously to mice was mainly excreted in urine without metabolism, and its recovery rate was almost equal to that of ceftazidime.

[Clinical evaluation of patients with right ventricular infarction detected by dual SPECT imaging of thallium-201 and technetium-99m pyrophosphate].

We evaluated clinical significance of dual-nuclide SPECT imaging (D-SPECT) of thallium-201 and technetium-99m pyrophosphate (PYP) in patients of acute inferior left ventricular infarction with PYP uptake in the right ventricle (PYP (+) group) in comparison with those without PYP uptake (PYP (-) group). There was no difference in coronary risk factors, history of angina, blood pressure, heart rate, and hemodynamics on admission between PYP (+) group and PYP (-) group. The duration from onset to admission was longer in PYP (+) group and coronary reperfusion therapies were carried out in few cases. In 7 of 8 PYP-positive patients, the diagnosis of right ventricular infarction was made only by D-SPECT. Four of 8 were complicated with shock within three days, and the duration of hospitalization was longer. Coronary angiography demonstrated many proximal lesions (50%) in PYP (+) group but few ones (18%) in PYP (-) group. D-SPECT was very useful for diagnosing acute right ventricular infarction, and it might contribute to the prevention of shock if performed within a few days.