BEGAIN (brain-enriched guanylate kinase-associated protein), a novel neuronal PSD-95/SAP90-binding protein

PSD-95/SAP90 is a synaptic membrane-associated guanylate kinase with three PDZ, one SH3, and one guanylate kinase (GK) domain. PSD-95/SAP90 binds various proteins through the PDZ domains and organizes synaptic junctions. PSD-95/SAP90 also interacts with the postsynaptic density (PSD) fraction-enriched protein, named SAPAP (also called GKAP and DAP), through the GK domain. SAPAP is Triton X-100-insoluble and recruits PSD-95/SAP90 into the Triton X-100-insoluble fraction in the transfected cells, suggesting that SAPAP may fix PSD-95/SAP90 to the PSD. Here we report a novel protein interacting with the GK domain of PSD-95/SAP90, BEGAIN. BEGAIN is specifically expressed in brain and enriched in the PSD fraction. BEGAIN is Triton X-100-soluble in the transfected cells but is recruited to the Triton X-100-insoluble fraction by SAPAP when coexpressed with PSD-95/SAP90. BEGAIN may be a novel PSD component associated with the core complex of PSD-95/SAP90 and SAPAP.

Characterization and primary structure of a base non-specific and acid ribonuclease from Dictyostelium discoideum

A base non-specific and acid RNase was isolated from cellular slime mold (Dictyostelium discoideum) cells in a homogeneous state (about 2.4 kDa) by SDS-polyacrylamide gel electrophoresis. The RNase (RNase DdI) has a pH optimum of 5.0. The amino acid sequence of RNase DdI was determined by a combination of protein chemistry, a search of Data base, Dicty cDB and further sequence analysis of cDNA from the same bank. RNase DdI consists of 198 amino acid residues, and about 13.3, 0.9, 1.2, 3.3, and 1.0 residues of mannose, xylose, glucose, GlcNAc, and GalNAc, respectively. RNase DdI has two characteristic conserved segments of the RNase T2 family, and thus belongs to the RNase T2 family. Considering the fact that most of the RNase activity of D. discoideum is present in the lysosomal fraction [Wiener and Ashworth (1970) Biochem. J. 118, 505-512], it was concluded that the lysosomal RNase in D. discoideum is a member of the RNase T2 family. The amino acid sequence of RNase DdI is highly homologous with that of Physarum polycephalum RNase (RNase Phyb), and its amino acid sequence seems to be similar to those of plant/animal type RNases, rather than fungal RNases. The location of RNase DdI in the phylogenetic tree of the RNase T2 family was estimated.

Role of bile acids in duodenal migrating motor complexes in dogs

Previous studies have suggested that enterohepatic circulation of bile acids is essential for regular cycling of duodenal migrating motor complexes (MMCs). The present study was an attempt to clarify the role of bile acids in the enterohepatic circulation system in initiating duodenal MMCs. Seven dogs underwent total external biliary diversion that resulted in the loss of MMCs originating from the duodenum. Sodium ursodeoxycholate (6 mg/kg/hr) was then given either through the portal vein or a peripheral vein, and motility of the gastrointestinal tract was serially recorded. When sodium ursodeoxycholate was given either through the portal vein or a peripheral vein during external biliary diversion, duodenal MMCs restarted. The cyclic change in plasma motilin levels during an MMC cycle as induced by sodium ursodeoxycholate was almost the same as in a normal MMC cycle. Total bile acid concentration in the portal vein changed cyclically with MMC cycles when bile flow was intact but did not change cyclically with MMC cycles restarted by intravenous bile salt infusion. Bile acid stimulation of putative receptors existing between the portal vein and intrahepatic bile ducts may be involved in initiating normal duodenal MMC cycles.

A novel multiple PDZ domain-containing molecule interacting with N-methyl-D-aspartate receptors and neuronal cell adhesion proteins

At synaptic junctions, pre- and postsynaptic membranes are connected by cell adhesion and have distinct structures for specialized functions. The presynaptic membranes have a machinery for fast neurotransmitter release, and the postsynaptic membranes have clusters of neurotransmitter receptors. The molecular mechanism of the assembly of synaptic junctions is not yet clear. Pioneering studies identified postsynaptic density (PSD)-95/SAP90 as a prototypic synaptic scaffolding protein to maintain the structure of synaptic junctions. PSD-95/SAP90 belongs to a family of membrane-associated guanylate kinases and binds N-methyl-D-aspartate receptors, potassium channels, and neuroligins through the PDZ domains and GKAP/SAPAP/DAP through the guanylate kinase (GK) domain. We performed here a yeast two-hybrid screening for SAPAP-interacting molecules and identified a novel protein that has an inverse structure of membrane-associated guanylate kinases with an NH2-terminal GK-like domain followed by two WW and five PDZ domains. It binds SAPAP through the GK-like domain and NMDA receptors and neuroligins through the PDZ domains. We named this protein S-SCAM (synaptic scaffolding molecule) because S-SCAM may assemble receptors and cell adhesion proteins at synaptic junctions.

Biochemistry of frog ribonucleases

Frogs have unique pyrimidine base-specific RNases, with structures similar to those of turtle, iguana and chicken RNases. Among the four frog RNases discussed here, three from Rana pipiens, R. catesbeiana and R. japonica oocyte cells show antitumour activity, and the latter two show lectin activity towards sialic acid-rich glycoproteins. In this review, (i) we compare their unique primary structures with respect to the locations of their disulphide bridges, three-dimensional structure, base specificity and heat stability as compared with RNase A, and (ii) we summarize current knowledge about the mode of action of lectin and the antitumour activities of the three frog RNases.

Characterization of ribonucleases from culture medium of Lentinus edodes

Lentinus edodes (shiitake) cultivated in potato dextrose medium produced five RNases in the culture filtrate. The two major RNases (RNase Le37 and RNase Le45) were highly purified and their molecular masses, base specificities, N-terminal amino acid sequences, and amino acid compositions were analyzed and compared to RNase Le2 isolated from the fruit bodies of the same mushroom. RNase Le37 and RNase Le45 are base non-specific and adenylic acid preferential RNases like RNase Le2 and their N-terminal sequences are very similar to RNase Le2, but they are glycoproteins and their amino acid compositions are significantly different from that of RNase Le2. In addition to these enzymes, a guanylic acid-specific RNase with a molecular mass 13 kDa was partially purified. Since RNase Le2, which has very similar N-terminal sequence to RNase Le37 and RNase Le45, was not excreted from the mycelia, the analysis of the structures of these two excreted RNase may shade a light on the mechanism of excretion of RNases in this organism.

Registration system for growth hormone (GH) treatment with standardized immunoreactive GH values in Japan

The Foundation for Growth Science has been controlling the use of GH by its registration system, which includes a scoring system for the eligibility for GH treatment according to the diagnostic criteria for GH deficiency (GHD) established by the Study Group for Hypothalamo-pituitary Disorder of the Ministry of Health and Welfare. Until 1995, 28,876 patients with GHD (19,432 boys and 9,444 girls) had been registered as eligible for GH treatment. The number of patients registered in a year increased gradually till 1990 due to the unlimited hGH supply by recombinant techniques and the change in the criteria for GH treatment and the number registered became stable after 1990. The frequency of GH-treated patients is calculated to be 55.2/100,000 persons (72.2/100,000 in boys and 37.1/100,000 in girls) in patients born between 1960 and 1990. The highest frequency was 148.4/100,000 persons (191.7/ 100,000 boys and 103.7/100,000 girls) in 1981, when 2,278 patients (1,508 boys and 770 girls) were born. Eligibility for GH treatment is assessed according to the scoring system which is basically dependent on peak GH values in provocation tests so that standardization of GH values measured with the various commercial GH kits is required to avoid inequality of patients' access to the treatment. In samples obtained by GRF test in 10 normal volunteers, hGH was measured with seven human GH (hGH) kits at a laboratory center. Since the RIA value has been used historically for the diagnosis of GHD, the mean of two RIA measurements was selected as the basis for the standardization procedure and the linear regression formula was used for each hGH kit. After the freely available supply of hGH obtained by recombinant DNA techniques, the role of the Foundation for Growth Science has changed to avoid hGH abuse. Even with this regulation, the frequency of registered patients may indicate a tendency to GH overuse.

Changes in colonic motility in dogs after a resection of the inferior mesenteric ganglion and plexus

In a curative resection for advanced sigmoid or rectal cancer, an extensive dissection of the regional lymph nodes is generally required. This often necessitates the removal of the autonomic nerves around the inferior mesenteric artery. The present study was done in an attempt to clarify the influence of a neurectomy around the inferior mesenteric ganglion and plexus on the motility of the colon. In eight dogs, we resected the ganglion and plexus around the inferior mesenteric artery, together with an implantation of strain gauge force transducers in various parts of the colon, and 7-10 days later, colonic motility was examined. The percentage of contractile states and contractile forces increased at both the distal colon in fasting dogs, as well as at the middle colon in the late postprandial period. At the distal colon, contractile forces were noted in the early and late postprandial periods. These contractile abnormalities at the middle and distal colon may thus explain the frequent bowel movements or diarrhea often observed after extensive surgery in patients with sigmoid or rectal cancer.

Fluorescence readout of near-field photochromic memory

The fluorescence- and transmittance-detection readout methods of a near-field photochromic optical memory by a scanning-probe technique were studied theoretically. Shot noise, as the principal noise, was taken into account in an analysis of the signal-to-noise ratio (SNR). Under most conditions, fluorescence-detection readout yielded a better SNR than did transmittance-detection readout. For a transmittance change of 0.9-1.0 as a result of recording, a readout light power of approximately 100 nW, and a system bandwidth of 1 MHz, only the fluorescence-detection readout method, under the condition that the fluorescent layer of the medium have a fluorescence quantum yield greater than 0.4, can produce a sufficiently large SNR.

A protease sensitive region of plant and animal ribonucleases belonging to the RNase T2 family

Recombinant RNase LE from tomato and squid liver RNase Tp, typical plant/animal type RNases belonging to the RNase T2 family, were subjected to limited digestion with several proteases, and the cleavage sites were analyzed by Edman degradation. Recombinant RNase LE was cleaved specifically at the 24th Lys by lysylendopeptidase and trypsin, and RNase Tp was cleaved at the 21st Glu by V8 protease. These cleavage sites are located very close to those where the cleavage during preparation of several animal RNase T2 family enzymes was observed. From this finding, it was concluded that the short segment around the 20th amino acid residue in plant/animal RNases is located on the surface of the molecules and forms loops, and is thus very sensitive to proteases.

Primary structure of porcine spleen ribonuclease: sequence homology

The primary structure of porcine spleen RNase (RNase Psp1) was investigated as a mean of assessing the structure-function relationship of base non-specific ribonucleases of animal origin. N-terminal analysis of RNase Psp1 yielded three N-terminal sequences. These peptides were separated by gel-filtration on Superdex 75HR, after reduction and S-carboxymethylation of RNase Psp1. Determination of the amino-acid sequence of these peptides indicated that the RNase Psp1 preparation consisted of three peptides having 20 (RCM RNase Psp1 pep1), 15 (RCM RNase Psp1 pep2), and 164 (RCM RNase Psp1 pro) amino-acid residues, respectively. It possessed two unique segments containing most of the active site amino-acid residues of the RNases of the RNase T2 family. The alignment of these three peptides in RNase Psp1 was determined by comparison with the other enzymes in the RNase T2 family. The overall results showed that RCM RNase Psp1 pep1 and RCM RNase Psp1 pep2 are derived from the N-terminal and C-terminal regions of RNase Psp1, respectively, probably by processing by some protease. The molecular mass of the protein moiety of RNase Psp1 was 23235 Da.

[Psychosocial evaluation on the correct recollection of periodic medical checkups of workers. 2. Long-term change in the recalled results of medical checkups]

A self-administered questionnaire study of 333 workers (male 253, female 80) in a manufacturing company was carried out one month after informing the workers of the results of their medical checkups in 1993. The questionnaire included several items such as recalled abnormal findings of health examination and ways of overcoming the abnormal findings, recalled results of their medical checkups in 1992, self-confidence in their recollection of the results, and the usefulness of medical checkups. The following were investigated: the relationship between actual as well as recalled results of medical checkups in 1992 and the recollection of them after one year, the effects of examinations after medical checkups in 1992 on their recollection of the checkup results after one year, the effects of actual as well as recalled 1992 checkup results on the recollection of the results one month after informing the workers of the results of their medical checkups in 1993, assurance of correct recollection of the results, the relationship between the usefulness of medical checkups, explanation of abnormal findings and the percentage of correct answers to the results of medical checkups in 1993 one month after informing the workers of their results. It was found that the percentage of correct answers to the results after one year was significantly lower than that after one month in 1992. The rate decreased with the increase in the number of abnormal items in medical checkups. Moreover, the rate also decreased when the results were abnormal. Further examinations in addition to the medical checkups influenced their recollection somewhat after one year. The results that the workers still remembered in 1992 had a stronger effect on their recalling the results one month after informing them in 1993 than the actual results in 1992. The workers' confidence in their recollection of the results was untrustworthy in the same way as their recollection of the results, and they were not able to maintain the recollection of the correct results, although many of the workers realized the usefulness of the medical checkups. Our results suggest that explanation of abnormal medical findings in 1993 was effective because the percentage of partial concordance between actual and recalled results was much higher in the workers who received the explanation than in the workers who did not receive it.

Interaction of rat lin-10 with brain-enriched F-actin-binding protein, neurabin-II/spinophilin

We have recently isolated a rat homologue of the Caenorrhabditis elegans lin-10 product. Although rat lin-10 is expressed in the cytosol and membrane fractions of various tissues, it is distributed only in the membrane fraction in brain where it is enriched in the synaptic plasma membrane and postsynaptic density fractions. We have isolated here a rat lin-10-interacting protein from rat brain and identified it to be neurabin-II/spinophilin, which has recently been isolated as a protein interacting with protein phosphatase I and F-actin. Neurabin-II/spinophilin is ubiquitously expressed but enriched in brain, especially in the synaptic plasma membrane and postsynaptic density fractions. We discuss the physiological significance of the interaction of rat lin-10 with neurabin-II/spinophilin.

Flexural properties and swelling after storage in water of polyacid-modified composite resin (compomer)

The flexural properties, flexural strength, flexural modulus and modulus of resilience, of four commercially available compomers, and one resin-modified glass ionomer cement and one microfilled resin comosite (as controls) immediately after light-activation and after 1 week of water storage were tested to assess the mechanical properties. The water swelling after storage in water was also tested to assess the characteristics in water of compomers. The flexural test showed compomers to be statistically stronger and more resilient than the resin-modified glass ionomer cement or the microfilled composite, when tested immediately after light-activation and after 1 week of water storage. Water swelling of compomers was statistically less than the resin-modified glass ionomer cement after 1 week of water storage.

Molecular cloning and characterization of rat lin-10

In Caenorhabditis elegans, the vulval induction is mediated by tyrosine kinase receptor/Ras signal transduction pathway composed of the lin-3, let-23, and let-60 products. In addition to these gene products, the lin-2, lin-7, and lin-10 products are also implicated in this pathway. Lin-2 encodes a MAGUK and lin-7 encodes a small protein with one PDZ domain. The lin-10 product has no homology to known proteins. Here, we have cloned a rat homologue of the lin-10 product and characterized it. Rat lin-10 is ubiquitously expressed in various rat tissues and distributed in both the cytosol and membrane fractions. In brain, however, rat lin-10 is distributed only in the membrane fraction and enriched in the synaptic plasma membrane and postsynaptic density fractions. These results suggest that rat lin-10 is involved at least in synaptic functions in brain.

Primary structure of a squid acid and base non-specific ribonuclease

Squid (Todarodes pacificus) liver RNase (RNase Tp) was purified. RNase Tp was a base non-specific and acid RNase. Upon hydrolysis of RNA, RNase Tp released four mononucleotides in the order of G > A > U > C. RNase Tp consisted of two peptides with 198 and 23 amino acid residues. The amino acid sequences of these peptides were analyzed. The large peptide had two unique segments containing most of the active site amino acid residues of RNase T2 family enzymes. From the comparison of the sequence of short peptide with the sequences of the other RNase belonging to RNase T2 family RNases, it was found that the amino acid sequence of the short peptide was very similar to that of the C-terminal portion of RNases of the RNase T2 family. Thus, we concluded that the short peptide was a C-terminal part of RNase Tp. The molecular mass of the protein moiety of RNase Tp was 25,582 daltons. The amino acid sequence of RNase Tp most resembles that of oyster RNase (91 amino acid residues identical) in the RNase T2 family RNases. However, the N-terminal portion of RNase Tp was unusually similar to those of plant RNases, rather than the other animal RNases.

[Effect of walking during all weekdays, holidays, and at work on mental and physical health in workers]

In order to clarify the effects of walking under various psychosocial and occupational conditions on psychophysiological health, we examined the relationship between the number of steps walked in several situations, such as on all weekdays, at work, and over the weekend, and the results of medical checkups, psychological tests, Breslow's 7 health practices, and other attitudes toward walking as well as health by using a pedometer in a certain manufacturing company. Most of the workers estimated their usual number of steps walked as being less than actual levels on both weekdays and holidays. Generally, the increased number of steps walked was significantly correlated with increased HDL-cholesterol levels, and decreased Triglyceride levels. Contrary to such physical effects, there were more variations with respect to the relationship between walking and psychological health. Moreover, the development of a walking habit at work resulted in some factors becoming worse, such as relaxation, trait anxiety, and serum AST levels when compared to those on all weekdays and over the weekend. In conclusion, it is necessary to consider several situations in which workers usually walk and we must also practice counseling and education for health promotion, to promote walking for health care in the workplace.

Primary structure of porcine spleen ribonuclease: sequence homology

The primary structure of porcine spleen RNase (RNase Psp1) was investigated as a mean of assessing the structure-function relationship of base non-specific ribonucleases of animal origin. N-terminal analysis of RNase Psp1 yielded three N-terminal sequences. These peptides were separated by gel-filtration on Superdex 75HR, after reduction and S-carboxymethylation of RNase Psp1. Determination of the amino-acid sequence of these peptides indicated that the RNase Psp1 preparation consisted of three peptides having 20 (RCM RNase Psp1 pep1), 15 (RCM RNase Psp1 pep2), and 164 (RCM RNase Psp1 pro) amino-acid residues, respectively. It possessed two unique segments containing most of the active site amino-acid residues of the RNases of the RNase T2 family. The alignment of these three peptides in RNase Psp1 was determined by comparison with the other enzymes in the RNase T2 family. The overall results showed that RCM RNase Psp1 pep1 and RCM RNase Psp1 pep2 are derived from the N-terminal and C-terminal regions of RNase Psp1, respectively, probably by processing by some protease. The molecular mass of the protein moiety of RNase Psp1 was 23235 Da.

Syntheses and antifungal activity of dl-griseofulvin and its congeners. III

Several congeners (1b-g), with novel substituents on the benzene ring of griseofulvin, were prepared by the application of a synthetic method developed by us. Antifungal activity of these congeners decreased in order of dl-griseofulvin (1a) = 1d > 1b, c >> 1e-f (inactive). The relationship between the antifungal activity and the position or kind of substituents on the benzene ring of griseofulvin is discussed.

[Psychosocial evaluation on the correct recollection of periodic medical checkups of workers. 1. The ratio of correctly recalled results of medical checkups]

To investigate the usefulness of a periodic medical checkup at the workplace from the standpoint of remembering the results, a survey was performed by a self-rating questionnaire on 424 industrial workers in a certain manufacturing company. The questionnaire included several items, such as their recalled abnormal medical findings and follow-up toward them, Breslow's 7 health practices, Goldberg's 12 selected items from the Japanese version of the General Health Questionnaire, and other original health related items. The study was conducted a month after the workers received their results. A total of 391 (290 males and 101 females) or 92.2% responded to the questionnaire. Several factors, such as age, gender, the type of occupation, and perceived health status were significantly correlated to the recalled results of medical checkups, but, only age and the way of observing the results were in accordance with the actual results. Only forty-nine percent of the responders correctly remembered their results. Age and perceived health status were significantly correlated to the exact recollection of the results. In particular, those who had poor perceived health status tended to have a wrong understanding of their medical results. Furthermore, there were those with the highest averaged GHQ scores who responded as having some abnormal findings even though no abnormalities were discovered in the medical checkups. On the other hand, there were those with the lowest averaged GHQ scores who answered that they had no abnormal findings even though some abnormalities were revealed in the medical checkups. The frequency of correct follow-up of the results was lower than the exact recalling of the results. In addition, those who made a mistake in the follow-up were inclined to have an optimistic view. Therefore, comprehensive health care for precise recalling of the results of medical checkups should be required to improve abnormal findings or maintain a good health status.

Enzymatic properties of double mutant enzymes at Asp51 and Trp49 and Asp51 and Tyr57 of RNase Rh from Rhizopus niveus

Mutation of Asp51 of a base-nonspecific RNase, RNase Rh, to Ser, Thr, or Gln makes the enzyme more preferential for the dinucleoside phosphate (XpY) having G and C at the 5'-side (X). On the other hand the mutation of one of the B1 site components, Tyr57 to Trp, and Trp49 to Phe makes the enzyme more preferential for purine bases and pyrimidine bases, respectively. In this study, to obtain more specific RNases and RNases with different base specificity, we prepared double-mutant enzymes that have Ser, Thr, and Asn at the 51st position and Trp at the 57th position or Phe at the 49th position, and their enzymatic specificities were studied with XpYs as substrates. The double-mutant enzymes D51SY57W and D51TY57W are more guanylic acid preferential than the mother single-mutant enzymes, D51S and D51T, respectively. They are extremely guanylic preferential RNases. D51NY57W is more a guanylic acid preferential enzyme than D51N, but cytidylic acid preference is of a similar order to that of D51N. The double mutant enzymes D51NW49F and D51TW49F showed an increased cytidylic acid preference as well as guanylic acid preference as compared to the mother single-mutant enzymes, D51T and D51N. The results of analysis of base specificity by the release of mononucleotides from RNA and the rates of hydrolysis of homopolynucleotides led to the same conclusion as in the case of the hydrolysis of XpY.

Binding of neuroligins to PSD-95

PSD-95 is a component of postsynaptic densities in central synapses. It contains three PDZ domains that localize N-methyl-D-aspartate receptor subunit 2 (NMDA2 receptor) and K+ channels to synapses. In mouse forebrain, PSD-95 bound to the cytoplasmic COOH-termini of neuroligins, which are neuronal cell adhesion molecules that interact with beta-neurexins and form intercellular junctions. Neuroligins bind to the third PDZ domain of PSD-95, whereas NMDA2 receptors and K+ channels interact with the first and second PDZ domains. Thus different PDZ domains of PSD-95 are specialized for distinct functions. PSD-95 may recruit ion channels and neurotransmitter receptors to intercellular junctions formed between neurons by neuroligins and beta-neurexins.

[Structures and functions of ribonucleases]

1. In order to understand the differences in pH optima and reaction rates of RNase A towards low molecular weight substrates and polymer substrates, the subsite structure of bovine pancreatic RNase A was studied. The kinetic studies of various sizes of oligouridylic acids showed that the size of the subsite is three nucleotides long. The kinetic studies on the inhibition of pUp, X-ray crystallographies of RNase A-ApC and pTp complexes, 31P-NMR studies on the binding of RNase A-pAp, and pTp showed the presence of P0, P2 and B3 sites. The location of the P0 site was assigned to be Lys66 by X-ray crystallography of the RNase A-pTp complex. The location of the P2 and/or P3/B3 site was determined by studying the enzymatic activities of several S-peptide analogs in which N-Leu was substituted for Lys7 and/or Lys1 coupled with S-protein toward various chain lengths of oligouridylic acids. The experiment suggested that P2 is Lys7 and P3/B3 is Lys1. 2. Several new pyrimidine base specific RNases were isolated and their primary structures were determined. They were two non-secretory RNases, a bovine liver alkaline RNase, a bovine brain RNase, and a bullfrog liver RNase. The bovine brain RNase has extra 16 amino acids at the C-terminus with O-glycosylated Ser. The bullfrog liver RNase was an extremely heat-stable RNase so far known. 3. Two new RNases belonging to RNase T1 family were isolated and their primary structures were elucidated. They were RNases isolated from Aspergillus saitoi and a mushroom (hiratake). The former RNase has a similar structure to RNase T1, but it was a base non-specific and guanylic acid preferential enzyme. From the results of X-crystallographic studies of this RNase, we suggested that the mechanism of RNase T1 RNase is essentialy a general acid-base catalysis between His40 and Glu58. 4. We isolated several fungal, plant and animal base non-specific acid RNases with a molecular mass about 24 kDa or more, and elucidated their primary structures. These RNases contain two sequences containing common 7-8 amino acid residues in common which include most of the amino acid residues important for the catalysis. Therefore, we proposed to designate these RNases as RNase T2 family RNase. On the basis of chemical modifications, kinetic studies and protein engineering studies of RNase Rh from Rhizopus niveus and RNase M from A. saitoi, we assigned that the catalytic site of RNase Rh consists of His46, His104, His109, Glu105, and Lys108. In the mechanism we proposed for RNase Rh, His46 and His109 work as a general acid and base catalysts. His104 was a phosphate binding site, and Glu105 and Lys108 might work to polarize a P=O bond of the substrate or stabilize the pentacovalent intermediate. However, in the reverse reaction of the transfer reaction step and the hydrolysis step of RNase Rh, His109 and His46 work as an acid and base catalyst, respectively. The X-ray crystallographic studies of RNase Rh, an RNase Rh-2'-AMP or d(ApC)complex, and the protein engineering studies of several mutant enzymes assigned the components of the major base recognition site (B1 site) and the minor base recognition site (B2 sites) of RNase Rh. The enzymatic studies of several mutant enzymes indicated that (i) Asp51 is very crucial for adenine base recognition, and the replacement of Asp51 by other amino acid, such as Thr, Ser, Glu, Asn makes RNase Rh more guanylic acid preferential, (ii) the replacement of Trp49 by Phe, and Tyr57 by Trp make the enzyme more pyrimidine and purine bases preferential, respectively. These trials are the first example of marked artificial change in the base specificity of RNases.

Effect of resin-modified glass ionomer cements on secondary caries

PURPOSE

To evaluate the in vitro secondary caries inhibitory effect of two resin-modified glass ionomer cements (R-GICs).

MATERIALS AND METHODS

Class V cavities were prepared at the cementoenamel junction on facial and lingual surfaces of 32 extracted upper premolars. The facial cavities were restored with a conventional glass ionomer cement (GIC) (Fuji II), while the lingual cavities were restored with either one of the R-GICs (Fuji II LC, Photac Fil, Vitremer), or a resin composite (Z-100). The margins of the restorations were subjected to a 20-day in vitro cariogenic challenge and the degree of demineralization was analyzed by microradiography. The amounts of fluoride released into distilled water from disc specimens of the materials tested were also measured for immersion time up to 161 days.

RESULTS

The R-GICs and GIC's released similar cumulative amounts of fluoride over 161 days. Photac-Fil showed significantly higher amounts of fluoride release over the same period. The depth of the outer lesion and the thickness of the acid-resistant layer showed no significant difference among the R-GICs and GIC's. Moreover, the residual fluoride and calcium in the dentin adjacent to the R-GICs and GIC's were correlated with the thickness of acid-resistant layers in the dentin adjacent to the R-GICs and GIC's by electron probe microanalysis. However, the inhibitory effect of the R-GICs was not directly related to the fluoride concentrations eluted from them.

[The relationship between workers' attitudes towards health, lifestyle and mental health]

In order to investigate the relationship between health practices, various psychosocial factors, and mental health, a survey was conducted by means of a self-rating questionnaire on 424 industrial workers. The questionnaire included items concerning Goldberg's 12 selected items from the Japanese version of the General Health Questionnaire, the Type A scale used in the Framingham study, Breslow's 7 health practices, and other original psychosocial, health practicing items. A total of 391 or 92.2% responded to the questionnaire. Among them, 354 (266 males and 88 females) complete responders to the GHQ were analysed for the present study. As a result, several factors such as decrease in age, perceived present illness, worsening of perceived health status, increase in anxiety concerning health, exacerbation of alcohol and smoking related behaviour, decrease in physical exercise, reduction of Breslow's 7 health practices, perceived stress and difficulty in dealing with stress, increase in stress content, negative and malfunctional coping strategies, and decrease in relaxation were, according to the GHQ scores, related to negative mental health. Furthermore, Type A scores were significantly correlated to GHQ scores, the number of stress factors, and Breslow's 7 health practices in males, but they were weak or had no correlation in females. It is considered that favorable health practices and attitudes towards health might help to maintain positive mental health, but further analysis is needed to determine their causal relationships because of the cross-sectional design of the present study.

SAPAPs. A family of PSD-95/SAP90-associated proteins localized at postsynaptic density

PSD-95/SAP90 is a member of membrane-associated guanylate kinases localized at postsynaptic density (PSD) in neuronal cells. Membrane-associated guanylate kinases are a family of signaling molecules expressed at various submembrane domains which have the PDZ (DHR) domains, the SH3 domain, and the guanylate kinase domain. PSD-95/SAP90 interacts with N-methyl-D-aspartate receptors 2A/B, Shaker-type potassium channels, and brain nitric oxide synthase through the PDZ (DHR) domains and clusters these molecules at synaptic junctions. However, neither the function of the SH3 domain or the guanylate kinase domain of PSD-95/SAP90, nor the protein interacting with these domains has been identified. We have isolated here a novel protein family consisting of at least four members which specifically interact with PSD-95/SAP90 and its related proteins through the guanylate kinase domain, and named these proteins SAPAPs (SAP90/PSD-95-Associated Proteins). SAPAPs are specifically expressed in neuronal cells and enriched in the PSD fraction. SAPAPs induce the enrichment of PSD-95/SAP90 to the plasma membrane in transfected cells. Thus, SAPAPs may have a potential activity to maintain the structure of PSD by concentrating its components to the membrane area.

Primary structure of base non-specific and acid ribonuclease from bullfrog (Rana catesbeiana)

A base non-specific acid ribonuclease (RNase RCL2) was purified from bullfrog liver [H. Yagi et al. Biol. Pharm. Bull., 18, 219-222 (1992)]. The sequence study and comparison of the amino acid sequence of the enzyme with homologous RNases from oyster, drosophila and chicken liver suggested that the RNase RCL2 consisted of two components, large protein fraction (182 amino acid residues) and peptide 2 (20 amino acid residues) or peptide 1 (18 amino acid residues), and that both components bind with disulfide bridge. The RNase preparation was probably formed from a single polypeptide protein by processing with some proteases. The amino acid sequence of RNase RCL2 showed that the RNase belongs to the RNase of RNase T2 family and its sequence most resembles chicken liver acid RNase. In RNase RCL2, the amino acid residues which consist of the active site and major base recognition site of RNase Rh, a typical RNase of RNase T2 family, are very well conserved except for Tyr57 (RNase Rh numbering), and part of the amino acid residues of the minor base recognition site (Phe101 and Pro92) are also conserved.

Role of histidine 46 in the hydrolysis and the reverse transphosphorylation reaction of RNase Rh from Rhizopus niveus

In order to study the reaction mechanism of RNase Rh from Rhizopus niveus, the rates of cleavage of four 2',3'-cyclic nucleotides by mutant enzymes of RNase Rh, H46F, H109F, E105Q, and K108L were measured. H46F is virtually inactive towards cyclic nucleotides, but H109F hydrolyzed these substrates at 0.7-4.5% of the rates of the native RNase Rh. The other mutants hydrolyzed 2',3'-cyclic nucleotides at 15-20% of the rates of the native enzyme. Relative enzymatic activities towards four cyclic nucleotides of H109F in the hydrolysis reaction (2nd step) were much higher than in the transphosphorylation reaction (the 1st step). In the presence of a 13-fold excess of uridine, H109F catalyzed the transphosphorylation reaction of 2',3'-cyclic AMP (A>p) to ApU. However, this reaction was not catalyzed by H46F mutant or native RNase Rh. These results showed that His46 is crucial to the hydrolysis reaction, and to the reversed reaction of the transphosphorylation reaction. We suggest that His46 in RNase Rh plays a major role in these reactions by acting as a base catalyst to activate water and the 5'-hydroxyl group of nucleosides, respectively.

The base specificities of tomato ribonuclease (RNase LE) and its Asp44 mutant enzyme expressed from yeast cells

RNase LE from cultured tomato cells is a member of the RNase T2 family. It is, however, distinguishable from RNase Rh from Rhizopus niveus, a typical RNase of the RNase T2 family, by its CD spectrum in the 200-250 nm region. In order to reinvestigate the base specificity of RNase LE and to study the role of Asn44 in RNase LE, which is considered to correspond to the base recognition site Asp51 of RNase Rh, RNase LE, and its Asp mutant at the 44th position were expressed from yeast cells with the same expression system as RNase Rh [K. Ohgi, et al., J. Biochem., 109, 776-785 (1991)]. RNase LE with four extra amino acid residues at the 2nd amino acid residue of mature RNase LE and its Asp44 mutant were secreted from yeast cells to give a yield of 10 mg/liter and 0.5 mg/liter culture broth, respectively. The expressed RNase LE (RNase RNAP LE) had the same characteristics as native RNase LE in the CD spectrum and specific activity. This is the first example of the expression of plant RNase from microbes and in sufficient amount to perform further enzymological research. The base specificity of RNase LE was guanylic acid preferential and that of N44D was changed to a more adenylic acid preference as compared to that of RNase LE. These experiments showed that Asn44 of RNase LE is crucial for base recognition as the case of Asp51 in RNASE Rh, and also suggested that the base recognition mechanism of RNase LE is very similar to that of RNase Rh.

Role of Kupffer cell-derived reactive oxygen intermediates in alcoholic liver disease in rats in vivo

The pathophysiology of alcoholic liver disease (ALD) remains largely unknown. In this work, we have developed an experimental rat model to elucidate the mechanism of liver injury, including ALD, in which Kupffer cell-derived reactive oxygen intermediates (ROIs) might be involved. Groups of male Wistar rats were pair-fed on a liquid high-fat diet containing ethanol (36% of total calories) or isocaloric carbohydrate with or without dietary carbonyl iron (0.5% w/v) for 3 weeks. In this rat model, we investigated Kupffer cell-derived ROI generation, which affected hepatocellular injury and hepatic fibrosis in ALD. The production of ROIs in Kupffer cells isolated from the iron-fed, the ethanol-fed, and the ethanol plus iron-fed rats were significantly increased, compared with that in Kupffer cells isolated from control rats (iron > ethanol+iron > ethanol > > control). However, hepatic vitamin E content in the ethanol plus iron-fed rats was decreased rather than that in the iron-fed rats. Then, lipid peroxidation of isolated microsomes was assessed as malondialdehyde equivalents determined by thiobarbituric acid assay. Compared with controls, the malondialdehyde equivalents were elevated in experimental groups (ethanol+iron > ethanol > iron > control). Serum ALT levels were greatly elevated in rats fed a diet containing both ethanol and iron (ethanol+iron > iron > ethanol > control). Hepatic content of hydroxyproline was significantly increased in ethanol plus iron-fed rats, compared with rats other than the ethanol plus iron-fed group (ethanol+iron > iron > ethanol > control). These results suggested that the enhanced Kupffer cell-derived ROI generation could itself contribute to the increased susceptibility to lipid peroxidation, which might cause hepatocellular injury and lead to hepatic fibrosis in ALD.

Marginal sealability of resin-modified glass ionomers for base/liner: effect of hygroscopic expansion and bond strength

The present study investigates the effect of storage in water on hygroscopic expansion and shear bond strength to dentin at periods up to 1 week, of the resin-modified glass ionomers for base/liner, and to analyze the effect on the marginal gaps in dentin cavities. For polishing after storage in water for 1 day, the material indicated significantly smaller marginal gaps both in dentin and in Teflon cavities than in those immediately after light-activation. For the results of after storage in water for 1 day, the material indicated significantly greater bond strength than material immediately after light-activation. The improvement of marginal sealability in dentin cavities may be performed not only by hygroscopic expansion during storage in water but also by greater bond strength after the setting reaction which continues to advance during storage in water.

Base specificity and primary structure of poly U-preferential ribonuclease from chicken liver

The primary structure and base specificity of chicken liver RNase CL1 which has been reported by Miura et al. [Chem. Pharm. Bull., 32, 4053-4060 (1984)] as poly U-preferential RNase, were extensively studied. The sequence study of this enzyme and comparison of the amino acid sequence of the enzyme with homologous RNases from oyster and Drosophila melanogaster suggested that RNase CL1 consists of three peptides with 17, 19, and 163 amino acid residues. The amino acid sequence of these three peptides were identified. The two small peptides are joined to the large peptide by disulfide bridges. The amino acid sequence of RNase CL1 had 62 (31.2%) and 63 residues (31.6%) identical with oyster RNase and D. melanogaster RNase, respectively, and belongs to the RNase T2 family RNase. Reassessment of the base specificity of RNase CL1 found that it is guanylic acid, then uridylic acid-preferential, and not poly U preferential.

Immunohistochemical localization of metallothionein in the olfactory pathway of dogs

Dogs raised in the open air were used in this study. Metallothionein (MT) immunoreactivity was observed in the nucleus and/or cytoplasm of sustentacular cells of the olfactory epithelium in the nasal mucosa, whereas there was few MT-positive cells in the respiratory epithelium. MT immunoreactivity was also observed in astrocytes in all layers of the the olfactory bulb cortex; glial cells surrounding the glomeruli in the olfactory bulb showed prominent immunoreactivity for MT. Adult dogs exhibited stronger immunoreactivity for MT than young. Northern blot analysis demonstrated substantial levels of MT mRNA in the olfactory mucosa and olfactory bulb. Physiological roles of MT localized in the olfactory pathway of dogs were discussed.

Enzymatic activities of several K108 mutants of ribonuclease (RNase) Rh isolated from Rhizopus niveus

We previously investigated the role of the Lys108 residue of ribonuclease (RNase) Rh from Rhizopus niveus, and suggested that Lys108 probably acts to stabilize the pentacovalent intermediate, and that an Arg residue could replace the role of Lys108. In RNase Le2 from Lentinus edodes, a homologous enzyme of RNase Rh, Lys108 is replaced by Thr. In this paper, the enzymatic properties of a K108T mutant and its analogous enzyme, K108S, were investigated to determine the effect of Thr and its analog, Ser at the 108th position on enzyme activity. The enzymatic properties of these mutant enzymes were compared with those of other mutant enzymes at this position (K108M, K108A, K108L). The results showed that Thr and Ser could replace Lys108 but resulted in only 2-20% of the activity of the native enzyme depending on the substrates used.

Enzymatic properties of mutant forms of RNase Rh from Rhizopus niveus as to Asp51

In order to determine the role of Asp51 of RNase Rh from Rhizopus niveus, enzymes with mutations at the 51st position, D51N, D51E, D51Q, D51S, D51T, D51A, and D51K, were prepared, and their enzymatic properties were investigated as to specific activity and base specificity. All the mutant enzymes showed relatively high activity toward poly I and poly C, and markedly reduced activity toward poly A and poly U. In particular, the enzymatic activities toward poly I of D51T and D51S were higher than that of RNase RNAP Rh. Among the mutant enzymes, D51N, D51S, and D51T showed more than ca. 30% of the activity of RNase Rh, when RNA, poly I and poly C were used as substrates, respectively. The substitution of Ala, Glu, or Lys at Asp51 is unfavorable for enzymatic activity. Among XpGs (X = A, G, U, or C), D51N, D51S, and D51T showed higher activity toward GpG then CpG. Therefore, Asp51 in RNase Rh plays a critical role in the adenylic acid preference of RNase T2 family enzymes. Our results obtained with a protein engineering technique provide basic insights into the control of the base specificity of RNase Rh.

The crystal structure of ribonuclease Rh from Rhizopus niveus at 2.0 A resolution

The three-dimensional structure of ribonuclease Rh (RNase Rh), a new class of microbial ribonuclease from Rhizopus niveus, has been determined at 2.0 A resolution. The overall structure of RNase Rh is completely different from those of other previously studied RNases, such as RNase A from bovine pancreas and RNase T1 from Aspergillus oryzae. In the structure of RNase Rh, two histidine residues (His46 and His109) and one glutamic acid residue (Glu105), which were predicted to be critical to the activity from the chemical modification and mutagenesis experiments, are found to be located close together, constructing the active site. The indole ring of Trp49 plays an important role in preserving the active site structure by its stacking interactions with the imidazole ring of His 109, and by hydrogen bonding with the carboxyl group of Glu105. There exists a hydrophobic pocket around the active site, which contains the aromatic side-chain of Trp49 and Tyr57. The results of mutagenesis studies suggest that this pocket is the base binding site of the substrate.

[Psychosomatic effect of a health program on obese employees]

A 12-week training period including exercise and diet was undertaken to determine the effects of a newly developed health program on the physical and phychological parameters in 24 obese employees of a certain company. The association between a number of somatic parameters and psychological variables, including the attitude toward better health, and the level of mental health (General Health Questionnaire) were analysed before, immediately or 1 year after the program. After the program, significant overall improvements were found in several physical parameters. Those who had higher initial levels of attitudes toward better health showed greater exercising/dieting achievements during the program. Furthermore, these considerable health-related attitudes seemed to be concerned with higher HDL levels preceding the program, and minor improvements in diastolic blood pressure due to the program. The GHQ scores tended to increase in proportion to decreased exercising/ dieting achievements during the program and undesirable lifestyle that ignored any form of exercising.

Enzymatic properties of mutant enzymes at Trp49 and Tyr57 of RNase Rh from Rhizopus niveus

In order to establish the role of Tyr57 and Trp49 in the enzymatic reaction of RNase Rh, several mutant enzymes at Tyr57 and Trp49 were prepared by protein engineering and their enzymatic properties were investigated. Among the four mutant enzymes at Trp49 (W49F, W49Y, W49A, and W49I), W49F showed 16% of the activity of the native enzyme, but the others (W49Y, W49A, and W49I) showed greatly decreased activity. The data showed that Trp49 is very important for the enzyme activity. Among 8 mutant enzymes at the 57th position, Y57F and Y57W showed similar enzymatic activity toward RNA to that of the wild-type enzyme, but the others (Y57G, Y57A, Y57V, Y57M, and Y57K) are more active toward RNA and less active toward XpGs. The reason for the apparent increase for RNA activity is discussed from the view point of substrate inhibition. It is noteworthy that W49F and Y57W became more pyrimidine base- and purine base-preferential, respectively.

Base non-specific acid ribonuclease from Irpex lacteus, primary structure and phylogenetic relationships in RNase T2 family enzyme

Two base non-specific acid RNases (RNase Irp1 and RNase Irp2) were purified from a commercial enzyme, "Driselase" (Irpex lacteus) in a homogenous state on SDS-PAGE by several steps of chromatographic separations. RNAse Irp2 was a simple polypeptide with 235 amino acid residues and RNase Irp1 was a glycopeptide with 248 amino acid residues. The amino acid sequences of both RNases were identified by Edman degradation of the peptides derived from these RNAses. RNase Irp1 was composed of the RNase Irp2 and extra C-terminal 13 residues of peptide. The phylogenetic relation of these RNases with the other fungal RNases already known was discussed. The sequence of RNase Irp2 was very highly homologous (67.5%) with that of RNase Le2 from Lentinus edodes.

Nucleotide sequence of hepatitis B virus isolated from subjects without serum anti-hepatitis B core antibody

The nucleotide sequences of the precore/core and X open reading frames (ORFs) of hepatitis B virus (HBV) were studied in four subjects who were serologically negative for anti-hepatitis B core antibody. These subjects were positive for serum hepatitis B surface antigen and were considered to be asymptomatic HBV carriers. Sequencing of the precore/core ORF revealed precore wild type and 3 to 8 nucleotide substitutions (replacing 0 to 2 amino acids) in the core region compared with the sequence of subtype adr. These substitutions were not considered to have changed the epitope of the core antigen, resulting in the absence of anti-HBc as determined by a conventional diagnostic kit. The X ORF showed 1 to 5 nucleotide substitutions (replacing 1 to 3 amino acids) and the structure of the X protein and the core promoter/enhancer II complex appeared to be conserved. These findings strongly suggest that the absence of serum anti-HBc is not due to mutation of the HBV DNA but to an aberrant immune reaction of the host to HBV.

Crystallization and preliminary crystallographic analysis of a 2,3-dihydroxybiphenyl dioxygenase from Pseudomonas sp. strain KKS102 having polychlorinated biphenyl (PCB)-degrading activity

Crystals have been obtained for a 2,3-dihydroxybiphenyl dioxygenase (conventionally called BphC) from a polychlorinated biphenyl (PCB)-degrader, Pseudomonas sp. strain KKS102. The crystals were grown using both ammonium sulfate and MPD as the precipitating agents. The crystals belonged to a tetragonal space group (I422) and diffracted to 2.5 A.

Purification and characterization of the 2nd 5'-nucleotide-forming nuclease from Lentinus edodes

The 2nd endonuclease (nuclease Le3) which hydrolyzes both RNA and heat denatured DNA to 5'-nucleotides was purified from the fruit bodies of Lentinus edodes to a homogeneous state by SDS PAGE. The nuclease was different from the nuclease Le1 previously characterized [H. Shimada et al. Chem. Pharm. Bull., 39, 2633-2637 (1991)] in molecular weight, optimal pH and N-terminal amino acid sequence. The N-terminal amino acid sequence of nuclease Le3 analyzed up to the 20th residue showed that 50% of the amino acid residues are identical to nuclease Le1.

Effect of immersion in water on linear expansion and strength of three base/liner materials

The purpose of this study was to characterize three base/liner materials in the initial stage of setting, i.e., dual-cured (light-activated glass ionomer), light-cured (light-activated glass ionomer analogue), and chemically-cured (conventional glass ionomer) materials. Changes in dimension, weight and flexural strength were examined from immediately after setting to the end of one week following immersion in water. The results obtained from these three types of material differed from each other, and showed a statistically significant correlation between changes in dimension and weight. This may be attributed to hygroscopic expansion. They also showed different flexural strength, indicating differences in the polymerization system. From these results, it appeared that marginal gaps following setting would be compensated for by hygroscopic expansion during immersion in water for one day or more. Physical properties would be favourably improved following the setting process which continues to advance during immersion in water.

[A study on the usefulness of stress assessment based on the THP health measurement--comparison with the general health questionnaire]

Although the "Total Health Promotion Plan (THP)" drawn up by the Labor Ministry includes a self-administered stress checklist (THP-SC) as a health measurement, THP-SC has not been utilized in the way that it had been planned. Hence, we studied the usefulness of this list by comparing it with the General Health Questionnaire (GHQ). We made a questionnaire that included both THP-SC and the 60-item GHQ, and collected answers from 261 white-collar workers (male, average age 43.7). The GHQ was evaluated using the Goldberg's method. When analyzing THP-SC, the number of answers indicating stress was counted, and the respondents were divided into two groups based on the cut-off points of 75 percentile or 90 percentile. In the 60-item GHQ, 48 respondents out of 243 with valid answers had a higher score than the cut-off point, and in the 12-item GHQ, 77 out of 256 had a higher score. The average number of THP-SC was 5.67 +/- 3.19. Concerning the relationship with GHQ, many items of the 'A' section of THP-SC were significant. The comparison also suggested that four or more items checked in 'A' section or seven or more items checked in the whole list would mean that a respondent may be under stress.