Identification of a frameshift mutation resulting in premature termination and loss of cell wall anchoring of the PAc antigen of Streptococcus mutans GS-5

Most strains of Streptococcus mutans possess a 190-kDa protein antigen (PAc) on their cell surfaces, while strain GS-5 produces extracellularly a 155-kDa PAc protein. The pac gene of strain GS-5 consists of 3,477 bp and codes for a protein of 1,158 amino acids. One insertion of an adenine into the 3,469th, 3,470th, or 3,471st position from the start codon results in a frameshift mutation at codon 1157 with subsequent termination after 3 additional codons.

Cloning and characterization of novel gene, DCRR1, expressed from Down's syndrome critical region of human chromosome 21q22.2

The new gene, DCRR1, from the proximal part of the Down's syndrome critical region (DCR) was identified by the GRAIL analysis of the 97-kb nucleotide sequence of two P1 DNAs and the cDNA for DCRR1 gene was cloned. A 7.36-kb cDNA encodes the imcompleted open reading frame composed of 1941 amino acid residues (220.2 kDa). The deduced amino acid sequence contains the conserved domain for protein phosphatases at the N-terminus. The domain encoding the rod-like tail of a myosin heavy chain was also found near the C-terminal region besides the signature for an actin binding protein, profilin, suggesting its possible role as a microtuble-associated protein. Two different sizes (7.9 and 9.0 kb) of mRNAs were detected in the poly(A)+ RNA from abundant tissues by the Northern analysis. The smaller transcript was only transcribed at a high level in the testis. The imbalance of the DCRR1 gene dosage may contibute to the pathogenesis of Down's syndrome.

Age-related changes in the compound action potentials of the eighth nerve in guinea pigs

The eighth nerve compound action potential (CAP) in 95 guinea pigs was measured using click stimuli to investigate age-related changes in their neural auditory thresholds. The animals were separated into three groups: group A (n = 43, 86 ears; 2-4 months old); group B (n = 29; 58 ears, 13-15 months old); and group C (n = 23; 46 ears, 23-25 months old). With increasing age, a gradual elevation of CAP thresholds was clearly seen among the three groups. The negative peak (N1) latencies of the CAP were prolonged, and the N1 amplitudes of the CAP decreased. There were significant differences in N1 latencies among the three groups and in N1 amplitudes between groups A and B, and between groups A and C. However, the rate of decline of the thresholds as well as the input-output function curves of the CAP varied in some of the oldest animals, suggesting that there were some individual differences in degenerative aging processes of the auditory system.

The relationship between orthostatic dizziness and hypotension in male medical students

We carried out a questionnaire survey regarding symptoms of orthostatic dysregulation (OD) and administered the Schellong test (orthostatic test) to 123 normal male medical students aged 21-29 years to investigate the relationship between orthostatic dizziness and hypotension. OD was identified in 15 (12.2%) of the subjects based on the questionnaire results. Orthostatic dizziness was noted in 40.7% of the subjects (50/123). The occurrence of orthostatic dizziness was most significantly related to systolic pressure decrease during the procedure for the Schellong test. These results suggest that the testing procedure introduced by Schellong can be useful, and clinically applicable to the assessment of orthostatic dizziness, since it presents the advantage of being simple enough to carry out in clinical practice.

Activation of Na+ channels in GH3 cells and human pituitary adenoma cells by PACAP

The effects of pituitary adenylate cyclase activating polypeptide (PACAP) on ion channels were examined in GH3 cells human pituitary adenoma cells. In GH3 cells, PACAP-38 (10-9 M) reversibly activated tetrodotoxin-sensitive NA+ channels but had little effect on nicardipine-sensitive Ca2+ channels. PACAP-induced increase in Na+ currents was inhibited by PACAP (6-38), a specific PACAP receptor antagonist, and Rp-cAMPs, an inhibitor for protein kinase A, and mimicked by 8-bromo-cAMP. In human pituitary adenoma cells, PACAP also activated tetrodotoxin-sensitive Na+ channels and growth hormone secretion. These results suggest the possibility that PACAP can activate voltage-gated Na+ channels via adenylate cyclase-protein kinase A pathway in the pituitary.

[Reliability and validity of a self-administered questionnaire of patient health care behavior and satisfaction]

The reliability of a self-administered questionnaire of health care behavior and patient satisfaction, and also the validity of measuring patient satisfaction by a single question, were investigated on 754 outpatients and 204 inpatients. In order to assess the reliability and the validity, the questionnaire was administrated twice. Subjects for reliability tests were 194 outpatients and 91 inpatients and validity tests were performed with 280 outpatients and 84 inpatients. To assess the validity of patient satisfaction, supplementary questions about satisfaction (outpatients 22 items, inpatients 14 items) were included in the questionnaire. Reliability was assessed using kappa coefficient and proportion of agreement. To assess validity, principal component analysis was performed, and the correlation between principal-components and the score of patient satisfaction was analyzed. With the exception of patient understanding of the doctor's explanation and patient satisfaction, kappa coefficient and proportion of agreement were high (kappa: 0.4 approximately 0.82), indicating that question contents were objective and easily understood. By making the question categories simple, a higher kappa coefficient and proportion of agreement in patient understanding about doctor's explanation and patient satisfaction were achieved. This suggests that in questionnaire, similar question category must be made simple or similar categories should be put together in analysis. Spearman's correlation coefficient between the question about patient satisfaction and the first principal component (which summarizes all of the questions about patient satisfaction) was high (outpatients: 0.63, inpatients: 0.67). Therefore the validity of measuring general information about patient satisfaction by using a single question is suggested.

Influence of ileal pouch capacity and anal sphincteric function on the clinical outcome after ileal pouch-anal anastomosis

This study was designed to determine the influence of ileal pouch capacity and anal sphincteric function on the clinical outcome after ileal pouch-anal anastomosis. A total of 24 patients who had undergone ileal pouch-anal anastomosis (J pouch) for ulcerative colitis were studied. The 24-hour stool frequency was found to be inversely correlated with the sensitivity threshold volume (STV), maximal tolerance volume (MTV), and distensibility, but was independent of the maximal resting pressure and maximal squeeze pressure. Patients experiencing nocturnal fecal incontinence had maximal resting pressures that were significantly lower than those of nocturnally continent patients. Among the patients with fecal incontinence, those with frequent soiling had lower resting pressures, STV, and distensibility than the patients with intermittent spotting. In addition, the STV in patients needing nocturnal evacuation were lower than those of patients who did not evacuate after falling asleep. The conclusions are as follows. Both stool frequency and the need for nocturnal pouch evacuation correlated directly with pouch volume. Anal incontinence was more common in patients with low internal sphincteric function. In addition, frequent and gross nocturnal incontinent patients demonstrate a worse function in both the anal sphincter and reservoir than those with intermittent spotting.

Function of a cell adhesion molecule, plexin, in neuron network formation

Plexin is a type I membrane protein which was identified in Xenopus nervous system by hybridoma technique. Molecular cloning studies demonstrated that the extracellular segment of the plexin protein possesses three internal repeats of cysteine cluster which are homologous to the cysteine-rich domain of the c-met proto-oncogene protein product. A cell aggregation test revealed that the plexin protein mediated cell adhesion via a homophilic binding mechanism, in the presence of calcium ions. Plexin was expressed in the neuronal elements composing particular neuron circuits in Xenopus CNS and PNS. These findings indicate that plexin is a new member of the Ca(2+)-dependent cell adhesion molecules, and suggest that the molecule plays an important role in neuronal cell contact and neuron network formation.

Gene identification in 1.6-Mb region of the Down syndrome region on chromosome 21

The Down syndrome (DS) region has been defined by analyses of partial trisomy 21. The 2.5-Mb region between D21S17 and ERG is reportedly responsible for the main features of DS. Within this 2.5-Mb region, we focused previously on a distal 1.6-Mb region from an analysis of Japanese DS patients with partial trisomy 21. Previously we also performed exon-trapping and direct cDNA library screening of a fetal brain cDNA library and identified a novel gene TPRD. Further screening of a fetal heart cDNA library was performed and a total of 44 possible exons and 97 cDNA clones were obtained and mapped on a BamH1 map. By rescreening other cDNA libraries and a RACE reaction, we isolated nearly full-length cDNAs of three additional genes [holocarboxylase synthetase (HCS), G protein-coupled inward rectifier potassium channel 2 (GIRK2), and a human homolog of Drosophila minibrain gene (MNB)] and a coding sequence of a novel inward rectifier potassium channel-like gene (IRKK). The gene distribution and direction of transcription were determined by mapping both ends of the cDNA sequences. We found that these genes, except IRKK, are expressed ubiquitously and are relatively large, extending from 100 kb to 300 kb on the genome. These nearly full-length cDNA sequences should facilitate understanding of the detailed genome structure of the DS region and help to elucidate their role in the etiology of DS.

Effect of pilocarpine on striatal acetylcholine release in dopamine-depleted rats

We have previously demonstrated that the systemic administration of pilocarpine stimulates striatal acetylcholine (ACh) release in rats using a brain microdialysis technique. In the present study, we investigated whether a nigro-striatal dopaminergic system is involved in the pilocarpine-induced increase in striatal ACh release using dopamine-depleted rats under urethane anesthesia. The application of pilocarpine (0.1-10 mM) via the microdialysis tube increased striatal ACh release in normal rats in a concentration-dependent manner, but it had no effect on the release of glutamate or gamma-aminobutyric acid (GABA) from the striatum. The increase in striatal ACh release caused by pilocarpine (1 mM) was enhanced by reserpine and alpha-methyl-p-tyrosine treatment, which completely depleted dopamine in the striatum. These results suggest that pilocarpine selectively increases striatal ACh release by acting at the striatum, and that the nigro-striatal dopaminergic neurons play an inhibitory role in the pilocarpine-induced ACh release.

Nitric oxide mediates central activation of sympathetic outflow induced by interleukin-1 beta in rats

The excitatory mechanism of central sympathetic outflow induced by interleukin-1 beta was investigated in urethane-anesthetized rats. Intracerebroventricular administration of interleukin-1 beta induced a gradually developing elevation of plasma noradrenaline levels in a dose-dependent manner (50, 100 and 200 ng/animal), while the levels of adrenaline were not affected. The elevation of noradrenaline levels induced by interleukin-1 beta (100 ng/animal i.c.v.) was abolished by the following treatments with: (1) a chemical sympathectomizer, 6-hydroxydopamine (15 mg/kg i.v., 3 days before); (2) a prostaglandin synthesis inhibitor, indomethacin (500 micrograms/animal i.c.v.); (3) a nitric oxide synthase inhibitor, L-NG-nitroarginine methyl ester (100 micrograms plus 10 micrograms/min i.c.v.); and (4) a nitric oxide scavenger, oxyhemoglobin (32.3 micrograms plus 3.23 micrograms/min i.c.v.). In contrast to these results, D-NG-nitroarginine methyl ester, an inactive isomer of L-NG-nitroarginine methyl ester, and methemoglobin, a metabolite of oxyhemoglobin, were without effect. Furthermore, prostaglandin E2 (100 ng/animal i.c.v.) rapidly and markedly elevated the plasma level of noradrenaline but not adrenaline. This prostaglandin E2-induced elevation of plasma noradrenaline levels was not attenuated by L-NG-nitroarginine methyl ester (100 micrograms plus 10 micrograms/min i.c.v.). The present results suggest that nitric oxide is involved in the interleukin-1 beta-induced central activation of sympathetic outflow. Furthermore, there probably exists nitric oxide-linked prostaglandin-generating system in the brain.

Central antinociceptive effects of mitragynine in mice: contribution of descending noradrenergic and serotonergic systems

Mitragynine is a major alkaloidal constituent of young leaves of Mitragyna speciosa Korth, that is known to exhibit narcotic-like activity. In this study, we investigated the roles of central monoaminergic systems in the antinociceptive action of mitragynine by means of the tail-pinch and hot-plate tests in mice. Mitragynine (1.0-10 micrograms) injected i.c.v. exerted a dose-dependent antinociceptive activity in both tests. The activity of mitragynine (10 micrograms, i.c.v.) in the tail-pinch test was antagonized by reserpine, 6-hydroxydopamine plus nomifensine, and p-chlorophenylalnine treatment, whereas the antinociceptive activity of morphine (3 micrograms) given i.c.v. in this test was attenuated by 6-hydroxydopamine plus nomifensine but not by p-chlorophenylalanine treatment. Moreover, the activity of i.c.v. mitragynine was also antagonized by the alpha 2-adrenoceptor antagonist, idazoxan (10 micrograms), and cyproheptadine (1 microgram) administered intrathecally (i.t.). On the other hand, the antinociceptive action of i.c.v. mitragynine (10 micrograms) in the hot-plate test was abolished by reserpine and 6-hydroxydopamine plus nomifensine, but not by p-chlorophenylalanine treatment. This action was also antagonized by i.t. injection of idazoxan (10 micrograms). These results suggest that both descending noradrenergic and serotonergic systems are involved in the antinociceptive activity of supraspinally administered mitragynine on the mechanical noxious stimulation, while the descending noradrenergic system predominantly contributes to the effect of supraspinal mitragynine on the thermal noxious stimulation. The mechanisms underlying the suppressive action of mitragynine on the nociceptive response may differ from those of morphine in mice.

Antibody responses and protection in mice immunized orally against influenza virus

Antibody responses and protection were studied in BALB/c mice immunized orally with formalin-inactivated influenza viruses (A/PR/8/34) combined with cholera toxin B subunit as adjuvant. Influenza virus-specific IgA as well as IgG antibody responses were induced in the mice, depending on the oral dosage frequency. The oral immunization by multiple doses resulted in reduction of viral replication in the nose and prevention of development of infection in the lung after intranasal (i.n.) challenge. The protective effect in the nose was thought to be related to the nasal IgA antibody response. The oral immunization was, however, less efficient for induction of the IgA antibody response and protection in the nose, compared with an i.n. immunization. The oral immunization following subcutaneous priming led to the complete protection in the nose, accompanied-by a prompt local IgA antibody response.

Molecular cloning of a complementary DNA for a membrane cofactor protein (MCP, CD46)/measles virus receptor on Vero cells and its functional characterization

We isolated a 1257-bp cDNA encoding a membrane cofactor protein (MCP, CD46)/measles virus (MV) receptor-like protein from a cDNA library of Vero cells, in which wild MV strains were established. Vero cells contain MCP mRNA splice products encoding different cytoplasmic tails like human cells. The deduced amino acid sequence of the cDNA was 86% identical to that of human MCP. Vero cell MCP expressed on CHO cells was recognized by monoclonal antibodies against human MCP, and served as a potent MV receptor. In addition, Vero MCP was as effective as human MCP in human factor I-mediated C3b cleavage. Thus, the high MV susceptibility of Vero cells can in part be attributed to an MCP-like molecule that is structurally and functionally similar to human MCP.

[Perioperative managements for postoperative severe infections in compromised host]

The incidence of postoperative infections, especially due to multi-drug resistant strains such as Pseudomonas sp., Enterococcus sp., and Methicillin resistant Staphylococcus aureus (MRSA), is high in compromised hosts. Among them, respiratory infection, catheter sepsis, and drug-associated enteritis are frequently observed and respiratory infection is liable to fall into serious illness. These infections have characteristics in causative organisms. Pseudomonas aeruginosa or MRSA are frequently isolated in respiratory infections and Candida or coagulase-negative staphylococcus are frequently isolated in catheter sepsis. G-test in addition to blood culture is necessary for early diagnosis of Candida sepsis, vancomycin should be administered in early phase of antibiotic-associated enteritis, since this infection is usually caused by MRSA or Clostridium difficile and frequently falls into serious illness. The patients with protein-calorie malnutrition, liver cirrhosis, renal failure, diabetes melitis, administration of anticancer drugs and/or radiation therapy, serious injury, or severe operative stress are considered to be compromised hosts in surgical field, and the adequate perioperative managements according to these disorders should be carried out against postoperative infections.

Lipid composition of commercial bakers' yeasts having different freeze-tolerance in frozen dough

The lipid composition of some commercial bakers' yeasts having different freeze-sensitivity in frozen dough was investigated to clarify the correlation between their lipid composition and freeze-tolerance. The total lipid content including neutral lipid, free fatty acid, sterol, and phospholipid ranged between 23.0 to 32.2 mg/100 mg protein of the yeasts tested. Phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidylserine were the main phospholipids found in all yeast strains, but no distinct difference in these components between freeze-tolerant and freeze-sensitive strains was observed. Palmitoleic (C16:1), oleic (C18:1), palmitic (16:0), and stearic (C18:0) acids were the major fatty acids present in total lipid and phospholipid, and unsaturation indices of fatty acid in these lipid components were almost equal by the strains. The molar ratios of sterol to phospholipid of freeze-sensitive strains were higher than those of freeze-tolerant strains. The difference in the sterol-phospholipid ratio that influences the fluidity of plasma membranes in yeast cells was supposed to reflect the difference in freeze-sensitivity of bakers' yeast.

Life with 6000 genes

The genome of the yeast Saccharomyces cerevisiae has been completely sequenced through a worldwide collaboration. The sequence of 12,068 kilobases defines 5885 potential protein-encoding genes, approximately 140 genes specifying ribosomal RNA, 40 genes for small nuclear RNA molecules, and 275 transfer RNA genes. In addition, the complete sequence provides information about the higher order organization of yeast's 16 chromosomes and allows some insight into their evolutionary history. The genome shows a considerable amount of apparent genetic redundancy, and one of the major problems to be tackled during the next stage of the yeast genome project is to elucidate the biological functions of all of these genes.