Epitope mapping of the influenza A virus RNA polymerase PA using monoclonal antibodies

Summary.  To obtain reagents to functionally map the PA protein, we produced monoclonal antibodies specific to this protein. Twenty-two monoclonal antibodies reacting with PA protein in ELISA were divided into 10 groups on the basis of competitive binding patterns to this protein. Of these, seventeen monoclonal antibodies bound to PA polypeptide spanning amino acids 101–400 and three bound to that of amino acids 518–600, while the other two did not react with any PA polypeptides tested with the exception of full-length PA. Among these monoclonal antibodies, only five reacted with PA in A/PR/8/34 virus-infected cells in indirect immunofluorescence assay. Thus, we obtained monoclonal antibodies that recognize at least 10 distinct regions of the PA molecule. These monoclonal antibodies should be useful in dissecting functions of the PA protein. Received September 6, 1999/Accepted January 5, 2000     

Characterization of a viroid associated with avocado sunblotch disease

A viroid has been purified from avocado leaves infected by sunblotch disease and designated the avocado sunblotch viroid. It is a covalently closed circular RNA molecule with a molecular weight lower than that of chrysanthemum stunt viroid and citrus exocortis viroid while hybridization analysis with 32P-labeled complementary DNA indicated that it is a single RNA species. It could be detected as a stainable RNA band on polyacrylamide tube gel electrophoresis of partially purified extracts of only two of four avocado isolates with positive symptoms of sunblotch disease. However, the viroid was detected in all four isolates by hybridization analysis with 32P-complementary DNA; this procedure has potential use for the rapid indexing of sunblotch disease since the viroid was not present in an isolate of healthy avocado. It has yet to be shown that the viroid is the causative agent of sunblotch disease.     

Changes in the somatosensory N250 and P300 by the variation of reaction time

We investigated the relationship between somatosensory event-related potentials (ERP) and the variation of reaction time (RT). For this purpose, we recorded the ERPs (N250 and P300) in fast- and slow-reaction trials during a somatosensory discrimination task. Strong, standard, and weak target electrical stimuli were randomly delivered to the left median nerve at the wrist with a random interstimulus interval (900–1,100 ms). All the subjects were instructed to respond by pressing a button with their right thumb as fast as possible whenever a target stimulus was presented. We divided all the trials into fast- and slow-RT trials and averaged the data. N250 latency tended to be delayed when the RT was slow, but not significantly. P300 latency was delayed significantly when the RT was slow, but to a much lesser extent than the RT delay, so we concluded that the change of RT was not fully determined by the processes reflected by the somatosensory N250 or P300. Furthermore, the larger and earlier P300 in the fast-RT trials implied that when larger amounts of attentional resources were allocated to a given task, the speed of stimulus evaluation somewhat increased and RT was shortened to a great extent. N250 amplitude did not significantly vary in the two RT clusters. In conclusion, the somatosensory N250 reflects active target detection, which is relatively independent of the modulation of the response speed, whereas the somatosensory P300 could change without manipulation of either the stimulus or the response processing demand. Electronic Publication     

Roles of Department of Clinical Laboratory in infection control

The Department of Clinical Laboratory plays an important role in the hospital and has much information about patients and pathogens. Laboratory data are essential to support clinical physicians who diagnose and treat patients. For nosocomial infections, laboratory-based surveillance is recognized as essential to confirm outbreaks. Therefore, the role of the Department of Clinical Laboratory is very important in infection control. In Tohoku University Hospital, we have an Infection Control Unit located in the Department of Clinical Laboratory. The core role of the Infection Control Unit is diagnosis, treatment and preventative healthcare associated with infections. The Infection Control Team (ICT) performs rounds in the hospital (The ICT members are ICN, ICD, a microbiological technologist and a dietician), consultations about clinical cases, infection control, and organize the regional infection control network, "Miyagi Infection Control Network". The ICT rounds are performed once a week in two wards, and two times a year for one ward. The consultations are an important role of the ICD, and concern clinical infection cases and infection control in our hospital and the other regional hospitals, and produce advice on appropriate clinical information. The regional network is important for the collection of information about the pathogens and the susceptibility of antimicrobial agents in the region. "Miyagi Infection Control Network" has held a forum 5 times a year from 1999, and 300-400 healthcare workers join the forum and discuss infection control.     

Effects of bilobalide on gamma-aminobutyric acid levels and glutamic acid decarboxylase in mouse brain

We have previously demonstrated that bilobalide, a constituent of the Ginkgo biloba extract, possesses anticonvulsant activity, and suggested that the mechanism of its anticonvulsant action involves modulation of y-aminobutyric acid (GABA)-related neuronal transmission. This study examined the effects of bilobalide on the level of GABA and glutamate, the activity and the amount of glutamic acid decarboxylase (EC 4.1.1.15), and the function of GABA(A) receptors in the hippocampus, cerebral cortex and striatum of the mouse. GABA levels, glutamic acid decarboxylase activity, and the protein amount of 67 kDa glutamic acid decarboxylase in the hippocampus of mice treated with bilobalide (30 mg/kg, p.o., once a day for 4 days) were significantly higher than those in controls. However, there were no significant differences in glutamate levels or, the number and the dissociation constants of GABA(A) receptors in the hippocampus between control and bilobalide-treated mice. These results suggest that the anticonvulsant effect of bilobalide is due to elevation of GABA levels, possibly through potentiation of glutamic acid decarboxylase activity and enhancement of the protein amount of 67 kDa glutamic acid decarboxylase by bilobalide.     

Interhemispheric cooperation of left- and right-handers in mental calculation tasks

Relations between handedness and interhemispheric processing in cognitive tasks were examined. Thirty six right-handers and thirty left-handers (familial and nonfamilial left-handers) were asked to add two numbers which were presented tachistoscopically. Two numbers were displayed either to one visual field, or one to the left and one to the right visual field simultaneously. In Experiment 1, the numbers were displayed in Arabic numerals, and in Experiment 2 one of the numbers was displayed in Kanji and one in Arabic numerals. The results of Experiment 1 showed a bilateral advantage, however no subject group difference was shown in the performance of the three (left unilateral, right unilateral, and bilateral) presentation conditions. Though familial left-handers showed a weaker tendency to different patterns than right and non-familial left-handers, the results of Experiment 2 were largely similar to those of Experiment 1. These findings suggest that interhemispheric processing may not differ between left- and right-handers.     

Language processing in partial English-Japanese bilinguals: evidence from Stroop-test results

Possible hemispheric functional differences between adolescent partial English-Japanese bilinguals and Japanese monolinguals were examined with a reversed auditory Stroop test. Subjects were requested to press their left/right hand button when they heard the target Japanese word "Otoko (male)/Onna (female)" as fast as possible. In one condition, the word and the speaker's sex weed congruent and in the other condition they were incongruent. The results of the reaction times showed that Stroop effects appeared with both responding hands in the bilingual group. On the other hand, the results of the monolinguals revealed that the Stroop effect was shown only with the left hand and not with the right hand. These results suggest that in nonproficient bilinguals, the right hemisphere may be involved in processing word meaning.