Molecular Design of Heat Resistant Polyimides Having Excellent Processability and High Glass Transition Temperature

The relationship between the imide structures and morphology are discussed in order to develop heat resistant polyimides having excellent processability and toughness. Addition-type imide oligomers consisting of asymmetric 2,3,3′,4′-biphenyltetracarboxylic dianhydride (a-BPDA) and 3,4′-oxydianiline (3,4′-ODA) and/or 4,4′-oxydianiline (4,4′-ODA) with 4-phenylethynyl phthalic anhydride (PEPA) were synthesized and characterized. The imide oligomers derived from 3,4′-ODA; 4,4′-ODA (50:50) comonomer having molecular weights of 5240 g mol−1 (Oligo-10) and 1340 g mol−1 (Oligo-1.5) showed good solubility in aprotic solvents such as DMAc and NMP, and were successfully cured at 370°C for one hour. The thermal curing process, and thermal and rheological properties of the imide oligomers were investigated by FT-IR, differential scanning calorimetry, thermogravimetric analysis, and dynamic rheometry. It was observed that the melt flow dramatically decreased above the Tg for Oligo-1.5, resulting in a viscosity as low as 200 Poise at 300°C. Whereas, a melt viscosity for Oligo-10 was 20 000 Poise at 365°C. The glass transition temperatures of these cured oligomers were 341°C and 308°C, respectively. In addition to the excellent melt property, the cured oligomers exhibited good thermo-oxidative stability. Furthermore, the cured imide oligomer consisting of a-BPDA and 4,4′-ODA with PEPA (Oligo-4.5) exhibited over 13% flexural elongation and a Tg of 343°C. Their T-300 carbon fibre composites were also well consolidated demonstrating excellent processability and properties. It is concluded that amorphous, aromatic imide structures without any weak linkages such as alkyl and methylene groups are very effective in the molecular design of heat resistant, addition-type polyimides. The excellent properties exhibited in a-BPDA based polyimides demonstrate a promising potential for future aerospace applications.

Inadequate management for secondary fracture prevention in patients with distal radius fracture by trauma surgeons

We evaluated the secondary fracture prevention in 1445 patients with distal radius fracture by trauma surgeons. The rate of patients with distal radius fracture who underwent bone mineral density (BMD) examination was low, suggesting that appropriate treatment for osteoporosis by trauma surgeons is not performed at present.

INTRODUCTION

To clarify the status of osteoporosis interventions after distal radial fractures by trauma surgeons who play the main role in treatment for these fractures, we performed a survey involving multiple institutions in Japan.

METHODS

We asked 155 board members of the Japanese Society for Fracture Repair for their cooperation and performed a survey in 48 institutions with which members who gave cooperation were affiliated. The subjects consisted of consecutive patients with distal radial fractures occurring between January and December 2012. The presence or absence of a diagnosis of osteoporosis and bone mineral density examination after fracture was investigated.

RESULTS

A total of 1445 patients with distal radial fractures were evaluated in this study. BMD examination for diagnosis and treatment for osteoporosis after fracture was performed respectively in 126 (8.7 %) and 193 (13.4 %) of 1445 patients. Treatment for osteoporosis was performed in 93 (73.8 %) of 126 patients who underwent BMD examination after fracture and 100 (8.2 %) of 1219 who did not undergo BMD examination. Of the 126 patients who underwent BMD examination after fracture, 89 showed a BMD <80 % of the young adult mean as a criterion for the initiation of drug treatment for osteoporosis in Japan and 77 (86.5 %) of the 89 patients were treated with drugs.

CONCLUSIONS

The rate of patients with distal radial fractures who underwent BMD examination was low, suggesting that appropriate treatment for osteoporosis by trauma surgeons is not performed at present.

Dual aptamer-immobilized surfaces for improved affinity through multiple target binding in potentiometric thrombin biosensing

We developed a label-free and reagent-less potentiometric biosensor with improved affinity for thrombin. Two different oligomeric DNA aptamers that can recognize different epitopes in thrombin were introduced in parallel or serial manners on the sensing surface to capture the target via multiple contacts as found in many biological systems. The spacer and linker in the aptamer probes were optimized for exerting the best performance in molecular recognition. To gain the specificity of the sensor to the target, an antifouling molecule, sulfobeaine-3-undecanethiol (SB), was introduced on the sensor to form a self-assembled monolayer (SAM). Surface characterization revealed that the aptamer probe density was comparable to the distance of the two epitopes in thrombin, while the backfilling SB SAM was tightly aligned on the surface to resist nonspecific adsorption. The apparent binding parameters were obtained by thrombin sensing in potentiometry using the 1:1 Langmuir adsorption model, showing the improved dissociation constants (Kd) with the limit of detection of 5.5 nM on the dual aptamer-immobilized surfaces compared with single aptamer-immobilized ones. A fine control of spacer and linker length in the aptamer ligand was essential to realize the multivalent binding of thrombin on the sensor surface. The findings reported herein are effective for improving the sensitivity of potentiometric biosensor in an affordable way towards detection of tiny amount of biomolecules.

Cross-cultural adaptation and validation of the Oxford 12-item knee score in Japanese

INTRODUCTION

With the high incidence of knee osteoarthritis (OA) in Japan, there is a strong need not only for surgical therapies, but also for validated outcome measures. For this study, we completed cross-cultural adaptation, testing and validation of the Oxford knee score (OKS) for prospective use in national and international clinical studies involving Japanese patients.

MATERIALS AND METHODS

The Japanese version of the OKS was developed according to the standard cross-cultural adaptation guidelines. For validation, the OKS was tested on 54 patients diagnosed with OA, osteonecrosis, ligament or meniscus injury. Reliability was tested using the intraclass correlation coefficient (ICC). Internal consistency or homogeneity was assessed using Cronbach's alpha. The correlation between the Japanese OKS, WOMAC and SF-36 questionnaires was used to assess construct validity.

RESULTS

No major difficulties were encountered with the translation and pre-testing stages. For reliability and validity, the Japanese OKS was completed without any missed responses by 53 (98.15%) and 52 (96.30%) patients at the first and second distribution, respectively. The total OKS showed good reliability with an ICC of 0.85. Internal consistency was strong (Cronbach's alpha = 0.90). Strong construct validity (ICC values of 0.51-0.84) was obtained against the WOMAC and SF-36 (physical functioning, role-physical, bodily pain, and social functioning subscales) scores. Notable "ceiling" effects of the OKS were reported for 11 of the 12 questionnaire items.

CONCLUSION

The Japanese OKS has proven to be a reliable and valid instrument for the self-assessment of knee pain and function in Japanese speaking patients with knee OA and other knee complaints.

Complication reporting in orthopaedic trials. A systematic review of randomized controlled trials

BACKGROUND

The nature and frequency of complications during or after orthopaedic interventions represent critical clinical information for safety evaluations, which are required for the development or improvement of orthopaedic care. The goal of this systematic review was to check whether essential data regarding the assessment of the prevalence, severity, and characteristics of complications related to orthopaedic interventions are consistently provided by the authors of papers on randomized controlled trials.

METHODS

Five major peer-reviewed orthopaedic journals were screened for randomized controlled trials published between January 2006 and July 2007. All relevant papers were obtained, anonymized, and evaluated by two external reviewers. A checklist consisting of three main parts (definition, evaluation, and reporting) was developed and applied for the assessment of complication reporting. The results were stratified into surgical and nonsurgical categories.

RESULTS

One hundred and twelve randomized controlled trials were identified. Although complications were included as trial outcomes in two-thirds of the studies, clear definitions of anticipated complications were provided in only eight trials. In 83% of the trials, the person or group assessing the complications was not identified. No trial involved a data safety review board for assessment and classification of complications.

CONCLUSIONS

The lack of homogeneity among the published studies that we reviewed indicates that improvement in the reporting of complications in orthopaedic clinical trials is necessary. A standardized protocol for assessing and reporting complications should be developed and endorsed by professional organizations and, most importantly, by clinical investigators.

Apnea, glial apoptosis and neuronal plasticity in the arousal pathway of victims of SIDS

Of 27,000 infants whose sleep-wake characteristics were studied under the age of 6 months, 38 died unexpectedly 2-12 weeks after the sleep recording in a pediatric sleep laboratory. Of these infants, 26 died of sudden infant death syndrome (SIDS), and 12 of definitely identified causes. The frequency and duration of sleep apneas were analysed. Sleep recordings and brainstem histopathology were studied to elucidate the possible relationship between sleep apnea and neuropathological changes within the arousal system. Immunohistochemical analyses were conducted using tryptophan hydroxylase (TrypH), a serotonin synthesizing enzyme, and growth-associated phosphoprotein 43 (GAP43), a marker of synaptic plasticity. The terminal-deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method was used for apoptosis. The pathological and physiological data were correlated for each infant. In the SIDS victims, statistically significant positive correlations were seen between the number of TrypH-positive neurons in the dorsal raphe nucleus of the midbrain and the duration of central apneas (p = 0.03), between the number of TUNEL-positive glial cells in the pedunculopontine tegmental nucleus (PPTN) and the average number of spines in GAP43-positive neurons in the PPTN (p = 0.04). These findings in the dorsal raphe nucleus of the midbrain and PPTN, that play important roles in the arousal pathway suggest a possible link between changes in arousal and SIDS.

Sudden infant deaths: stress, arousal and SIDS

The prevalence of the Sudden Infant Death Syndrome (SIDS) has dropped in most countries following the development of education campaigns on the avoidance of preventable risk factors for SIDS. These include factors in the infant's micro environment, such as prenatal passive smoking, administration of sedative drugs, prone sleep, high ambient temperature or sleeping with the face covered. Sleep laboratory studies have shown that these risk conditions contribute to the development of respiratory and autonomic disorders and reduce the child's arousability. The opposite effects were seen when studying factors protective from SIDS, such as breastfeeding or the use of a pacifier. In victims of SIDS, similar breathing, autonomic and arousal characteristics were recorded days or weeks before their death. It is concluded that in some infants, already immature control mechanisms can be aggravated by environmental factors.

Sudden infant deaths: from epidemiology to physiology

The incidence of sudden infant death syndrome (SIDS) has dropped significantly in most countries following the development of education campaigns on the avoidance of risk factors for SIDS. However, questions have been raised about the physiological mechanism responsible for the effects of these environmental risk factors. Since 1985, a series of prospective, multicentric studies have been developed to address these questions; over 20,000 infants were recorded during one night in a sleep laboratory and among these, 40 infants eventually died of SIDS. In this review, the following methods were employed: sleep recordings and analysis, monitoring procedure, data analysis of sleep stages, cardiorespiratory and oxygen saturation, scoring of arousals, spectral analysis of the heart rate and the determination of arousal thresholds, and statistical analysis and the results including sleep apneas, arousals and heart rate and autonomic controls in both future SIDS victims and normal infants were introduced separately. In addition, the physiological effect of prenatal risk factors (maternal smoking during gestation) and postnatal risk factors (administration of sedative drugs, prone sleeping position, ambient temperature, sleeping with the face covered by a bed sheet, pacifiers and breastfeeding) in normal infants were analyzed. In conclusion, the physiological studies undertaken on the basis of epidemiological findings provide some clues about the physiological mechanisms linked with SIDS. Although the description of the mechanisms responsible for SIDS is still far from complete, it appears to involve both arousal responses and cardiac autonomic controls during sleep-wake processes.

Analysis of SIDS-related civil and criminal court cases in Japan

Thirty-three sudden infant death syndrome (SIDS)-related civil and criminal lawsuits in Japan were retrieved from judicial precedent databases "Hanrei Masutar (Judicial Decisions Master)" and "Hanrei Taikei (Judicial Decisions System) using "SIDS" as a keyword. Sleeping posture and developmental stage of occurrence were studied in each of the cases retrieved, whether or not a legal autopsy had been performed. The influence exerted on court decisions by Japanese definitions of SIDS as well as the relationship between causes of death and court decisions were studied. Of 33, two were criminal cases (business/professional negligence on the part of the defendants, leading to death), and the rest were civil cases (claims for damages). Because the decision handed down in both criminal cases was "cause of death unknown", these defendants were found innocent. One of these cases was argued in both the court of appeals and the superior court: these courts found SIDS to be the cause of death and consequently the claim for damages was rejected. Both criminal and civil courts dealt with another case: the former found the cause of death to be "unknown" and the defendant innocent, while the latter, finding SIDS the cause of death, declined to review. In cases where the sleeping posture was prone, courts tended to decide the cause of death to be suffocation, especially with neonates. Because diagnosis by exclusion is required in cases of a legal autopsy for SIDS, the diagnosis is difficult without an autopsy. Disagreements between the results of legal autopsy and court decisions occurred in eight cases. With such a discrepancy, a detailed case examination is necessary. In 1983, SIDS was defined in Japan in two different ways; one in a more strict sense and the other being more inclusive. The wider and narrower definitions were unified in 1995 by requiring a survey of the circumstances of death in addition to the narrower definition. Because of this situation, the two cases in the 1980s when legal autopsy was not enforced fell into the category of "SIDS in a wider sense." In no case was a defendant found guilty when the cause of death was judged to be either SIDS/ALTE or unknown. Four cases were rejected when the cause of death was judged to be neither due to suffocation nor SIDS, while seven were accepted either as cases of "joint faults that canceled each other," or as "partial acceptance." In Japan, official views concerning a SIDS diagnosis differ among pediatricians, legal scholars of forensic medicine and pathologists. These differences appeared to influence the legal decisions. Several conferences should be convened as soon as possible to provide an opportunity to resolve the main points of difference between these three professional groups and, thus, attain a unified view.

Molecular biology in cerebral cortex of sudden infant death syndrome

Full-scale investigations of sudden infant death syndrome (SIDS) by methods of molecular pathology have been carried out. This paper reports the basic preliminary data of SIDS cerebral cortex analyzed by restriction landmark genomic scanning (RLGS) method, which is the second dimension electrophoresis of DNA recently developed in Japan. The RLGS method was carried out separately using the cerebral cortex of a 4-month-old infant with SIDS and using the cerebral cortex of a 3-month-old infant as a control to investigate SIDS-specific spots. As a result, the coincidence rate of spots between the infant with SIDS and the infant without SIDS was 98.12%. The average coincidence rate of spots in humans is usually 99.07%. Therefore, it was confirmed that the coincidence rate of spots by RLGS between the infant with SIDS and the infant without SIDS was lower than that in humans. In addition, the incidence of SIDS-specific spots was 1.19% and the incidence of non-SIDS-specific spots was 0.6%.

Research for improving the autopsy rate for infant death--medical economic assessment of the forensic autopsy system in Japan

The rate at which autopsies are performed in Japan for cases of infant death is not adequate for diagnosing sudden infant death syndrome (SIDS). In Japan, it will be necessary to increase the autopsy rate at the time of infant deaths in order to improve the certainty of diagnosing SIDS and improving the accuracy of determining the cause of death with respect to infant death. The objective of this research is to provide basic documentation required for administrative implementation of this objective. In Japan, the Medical Examiner System and its related Approved Autopsy System are not deployed nationwide. The estimated budget in the case of deploying the Medical Examiner System nationwide for the purpose of improving the infant death autopsy rate is in excess of 5 trillion yen, and that in the case of deploying the Approved Autopsy System nationwide is estimated at roughly 130 million US dollars. However, since the rate of autopsies performed for SIDS has not changed following the implementation of approved autopsies, the efficacy of the Approved Autopsy System has come to be viewed questionably. In addition, it is also necessary to enact legislation that mandates the conducting of autopsies for all cases of infant death as is done in Scandinavia. The required cost in the case of performing autopsies for all cases of abnormal infant death is estimated at 200,000-700,000 US dollars and is considered to be within a range that could be implemented through local government regulations. In addition, the cost per body of an autopsy performed at the State Crime Laboratory in the State of Arkansas in the US in 1999 was about 6000 US dollars. In contrast, the same cost at the Tokyo Medical Examiner Office is much less at only about 4000 US dollars.

Study on social responses (encouraging public awareness) to sudden infant death syndrome: evaluation of SIDS prevention campaigns

The sudden infant death syndrome (SIDS) prevention campaign promulgated by the SIDS Family Associations was initiated and directed to medical professionals in 1996 and to mothers in 1997. In mid-1998, the Ministry of Health and Welfare began to support this campaign. In parallel with these moves and with cooperation from the study group of the Ministry of Health and Welfare and the SIDS Family Associations of Japan, a Japanese segment of the International Child Care Practices Survey (ICCPS) was conducted in two phases--from 1996 to 1997 and from 1998 to 1999--to observe the trends in risk factors for SIDS that may exist in the child rearing environment in Japan. Consequently, after the SIDS prevention campaign, the risk factors for SIDS, such as the practice of placing infants in a prone posture, smoking, and formula feeding, were reduced. Correspondingly, it was shown that the incidence of SIDS in Japan and in Kanagawa Prefecture where the survey was carried out considerably decreased (0.42-0.24 per 1000 live births). These data indicate that this prevention campaign has been effective.

Comparison between SIDS-related court cases in the United States and Japan--a trend seen in legal precedents in the United States

A bibliographic search of "Lexis", a database on foreign legal cases, was conducted, using sudden infant death syndrome (SIDS) as a key word to retrieve legal cases related to SIDS in the United States. The procedure yielded 156 cases, which included many that were brought to the courts for reasons other than SIDS. The following explanation was given for this outcome: because the public in the United States is much better informed about SIDS than in Japan, few cases are brought to the courts with SIDS as the main cause of the argument; the acronym, SIDS, is simply quoted during the court proceedings. Nevertheless, 26 cases that were particularly related to SIDS were selected and compared against 33 cases recorded and retrieved in the previous year in Japan to find the difference in the trends in legal disputes. The difference in the trends in litigation in the two countries was evident: in most cases in Japan, the legal dispute was over the recognition of SIDS or asphyxiation as the cause of death that had occurred in a nursery or hospital, with the family acting as the plaintiff and the nursery or hospital as the defendant. In the majority of cases in the United States, on the other hand, the state was the plaintiff and the family or baby sitter the defendant; the focal point of the dispute was the distinction between SIDS and child abuse. Compared with the trend in Japan, a much greater number of cases were brought before the court of final appeals in the United States. As the public becomes more aware of SIDS through campaigns and other means, the pattern seen in the legal disputes refer to SIDS lawsuits in Japan may change into that seen in the United States.

Study to increase the frequency of autopsies performed for cases of infant deaths--proposed revision of the law on postmortem examination and corpse preservation and other related regulations

By definition, sudden infant death syndrome (SIDS) requires diagnosis through exclusion by conducting an autopsy. To obtain a reliable diagnosis of this disease, an autopsy is essential. However, the frequency with which autopsies are conducted in Japan is not sufficient to meet the need associated with the diagnosis of SIDS. To improve this frequency, various public policies, such as nationwide implementation of the administrative autopsy system (medical examiner system), the application of the practice of autopsy approved by families, and legally required autopsies, are being considered; but none has been put into practice. On the other hand, attention has been called to the fact that the Law on postmortem examination and corpse preservation, which was instituted at the end of the Second World War, requires updating. In the current report, it is proposed that the following be added to Article 8, item 3 of this Law: "the Metropolitan or Prefectural Governor must insist that an autopsy be conducted on all cases of a sudden and unexpected death of an infant to investigate the cause of this death." At present, the annual incidence of SIDS in Japan is reported to be 500. To put the above-recommended legal requirement into practice, the estimated annual addition to the budget, if conducted as approved or an administrative autopsy, will be in the order of 150,000-500,000 dollar, which is within the prescribed limits for an appropriation.

Japanese national SIDS project: 1998-2000 research for the improvement of infant mortality

The aim of the present study is to see if by conducting research on sudden infant death syndrome (SIDS), one of major contributing factors to infant mortality in Japan, infant mortality can be reduced. Concrete approaches taken in this study took four different directions: elucidation of SIDS etiology, prevention, elucidation of its social aspects (education) and the investigation of administrative aspects. At the same time, an attempt was made to get better grasp on the epidemiological trends in infant mortality, including that of SIDS. The idea behind this etiological approach was to unify hitherto separate approaches taken by those in epidemiological, physiological and pathological fields. A molecular-biological approach was also added. Physiologically hypothesized causes of SIDS--apnea and arousal disorder--together with the epidemiologically presumed risk factor of sleeping position, were examined jointly from a pathological viewpoint. Research in the first 2 years of the grant found that hypoxia reflected by gliosis in the brain stem arousal pathway was related to the duration of sleep apnea. Research in the final year of the grant found the possibility of organic fragility in the brain stem arousal pathway, particularly in periaqueducal gray matter and pedunculopontine nucleus reflected by apoptosis and neuronal plasticity. These findings gave support to the arousal disorder hypothesis in SIDS. Application of the restriction landmark genomic scanning (RLGS) method supported the possibility of locating a site for a SIDS-specific gene. The US collaborative home infant monitoring evaluation (CHIME) currently in use was evaluated. In addition, three new monitoring methods were developed: a non-invasive multi-channel pressure-sensing bed, microwave radar, and a pacifier that functions as a suckometer which can be used to evaluate a neonate's autonomic nervous functions. Social (educational) activities included: surveys of the current state of educational campaigns on SIDS in other countries, epidemiological evaluation of campaigns run by the Japan SIDS families' Association to evaluate the effectiveness of the SIDS campaign, and creation of a home page, mostly to inform the public about the output from this research group. "Guidelines for Death Scene Investigation of Sudden, Unexplained Infant Deaths: Recommendations of Interagency Panel on Sudden Infant Death Syndrome" was translated into japanese. Activities that concerned administrative measures included clarification of the unique nature of SIDS-related trials in Japan when compared to those in the United States. Other concrete administrative proposals were: a pressing need to increase the rate of SIDS-related autopsies to facilitate a better etiological understanding and, for this purpose, establishing regulations in local jurisdictions and amending Article 8 of the Postmortem Examination and Corpse Preservation Act, keeping in perspective the medico-economic evaluation of the japanese medical examiner system. For these proposals to be realized, establishment of a new office in charge of administrative and approved autopsies at the national level of government is desirable. Also pointed out were the different opinions held among specialists concerning the diagnosis of SIDS and their need to hold multiple conferences to unify their views. Basic data for these conferences were provided from epidemiological examinations of infant mortality.

Comparative evaluation of diagnostic guidelines for sudden infant death syndrome (SIDS) in Japan

It is a well-recognized fact among professionals that the diagnosis of sudden infant death syndrome (SIDS) involves difficult elements; a SIDS diagnosis is not uniform throughout Japan; and such a diagnosis is not made based on any internationally recognized definition. Faced with this situation, guidelines have been prepared and proposals have been made to standardize and improve the accuracy of SIDS diagnoses, viz. the following three can be cited: "guideline for diagnosis of SIDS" prepared by a Study Group of the Ministry of Health and Welfare; "case studies of SIDS" and a "guideline for its diagnosis" prepared by the Case Study Committee of Japan SIDS Research Society; and a "proposal on the principles of medico-legal pathology concerning SIDS", included in the research report supported by a Grant-in-Aid for Scientific Research from the Ministry of Education. In the current study, a comparison was made focusing on the discrepancies among these three documents. The major discrepancies among these three are: (1) handling of the patient's age (by months or years) in the diagnosis of SIDS; (2) dealing with those cases for which no autopsy has been conducted; (3) attitudes concerning whether sleeping in a prone posture is a cause for asphyxia and (4) opinions concerning the aspiration of vomited milk. It is anticipated that these discrepancies will invite confusion and affect judgments and recognition of SIDS-related cases that will be brought to court. It is essential that those involved with these three documents have an opportunity at the earliest time to discuss the matter and come to a uniform understanding.

Amperometric determination of acetic acid with a trienzyme/poly(dimethylsiloxane)-bilayer-based sensor

A trienzyme sensor for the amperometric determination of acetic acid was prepared by immobilizing acetate kinase (AK), pyruvate kinase (PK), and pyruvate oxidase (PyOx) on a poly(dimethylsiloxane) (PDMS)-coated electrode. AK catalyzes the phospho-transferring reaction between acetic acid and ATP to form ADP; PK, the phospho-transferring reaction between ADP and phosphoenolpyruvate to form pyruvic acid; and PyOx, the oxidation of pyruvic acid with oxygen. The oxygen consumption could be monitored by using the PDMS-coated electrode without interference from the PyOx reaction product, hydrogen peroxide. Thus, the concentration of acetic acid (5 microM-0.5 mM) could be determined from the decrease in the cathodic current at -0.4 V vs Ag/AgCl. This is the first example of a biosensor that can be used for the determination of acetic acid in ethanol-containing food samples. The acetate-sensing electrode could be used for more than one month.

Prefrontal cortical representation of visuospatial working memory in monkeys examined by local inactivation with muscimol

In primates, dorsolateral areas of the prefrontal cortex (PFC) play a major role in visuospatial working memory. To examine the functional organization of the PFC for representing visuospatial working memory, we produced reversible local inactivation, with the local injection of muscimol (5 microg, 1 microl), at various sites (n = 100) in the dorsolateral PFC of monkeys and observed the behavioral consequences in an oculomotor delayed-response task that required memory-guided saccades for locations throughout both visual fields. At 82 sites, the local injection of muscimol induced deficits in memory-guided saccades to a few specific, usually contralateral, target locations that varied with the location of the injection site. Such deficits depended on the delay length, and longer delays were associated with larger deficits in memory-guided saccades. The injection sites and affected spatial locations of the target showed a gross topographical relationship. No deficits appeared for a control task in which the subject was required to make a visually guided saccade to a visible target. These findings suggest that a specific site in the dorsolateral PFC is responsible for the working memory process for a specific visuospatial coordinate to guide goal-directed behavior. Further, memoranda for specific visuospatial coordinates appear to be represented in a topographical memory map within the dorsolateral PFC to represent visuospatial working memory processes.

The effects of dopamine and its antagonists on directional delay-period activity of prefrontal neurons in monkeys during an oculomotor delayed-response task

To examine the role of dopamine receptors in the memory field of neurons for visuospatial working memory in the prefrontal cortex (PFC), dopamine and its antagonists (SCH23390 for the D1-antagonist and sulpiride for the D2-antagonist) were applied iontophoretically to neurons of the dorsolateral PFC in monkeys that performed an oculomotor delayed-response task. In this task, the subject made a memory-guided saccade to a remembered target location that had been cued by a visuospatial stimulus (right, up, left, or down; 15 degrees in eccentricity) prior to a 4-s delay period. We focused here on PFC neurons that showed directional delay-period activity; i.e., an increased activity during the delay period, the magnitude of which varied significantly with the target location. Iontophoretic application of SCH23390 (usually 50 nA) decreased or increased the activities of most of these neurons (n=48/62, 77%); most neurons showed a decrease (n=43/62, 69%). For the neurons affected by SCH23390, a directional index of directional delay-period activity was attenuated by SCH23390, whereas the preferred direction was not greatly affected. The decreasing effect of SCH23390 was dose-dependent; the extent of the decrease was less with a lower dose (20-nA current) than with the ordinary dose (50-nA current), although the effect of the lower dose of SCH23390 on delay-period activity was similar in nature to that of the ordinary dose of SCH23390. Furthermore, the application of dopamine itself augmented directional delay-period activity in most of the neurons tested (n=12/16, 75%). Sulpiride did not have any significant effects in most of the neurons tested (n=15/17). These results suggest that the activation of D1-dopamine receptors play a facilitating role in the memory field of PFC neurons for visuospatial working memory processes.

Characteristics of suicide among children and adolescents in Budapest

BACKGROUND

In Europe, the suicide rate among children and adolescents is the highest in Hungary. In the young age group (10-14 and 15-19 years), the suicide mortality rate had not showed a decrease.

METHODS

This study examined suicide cases committed by children and adolescents highlighted from the extraordinary death cases in Budapest between 1994 and 1998. The 72 suicide cases, which included 59 males and 13 females, were processed by sex, age, method and time of commitment, and distribution by districts.

RESULTS

Leaping off high places or hanging was the highest frequency among the methods of commitment. Accurate data about the frequency, type, time and location of death cases are indispensable to decrease the number of children's and adolescents' suicides.

CONCLUSIONS

Studies of epidemiology and risk factors may provide a basis of development of a specific suicide prevention programme including educational, health and welfare elements.

Comparative analysis of differences by gender in sudden infant death syndrome in Hungary and Japan

We examined the sex ratio in sudden infant death syndrome (SIDS) cases in Hungary, in Tokyo and Japan between 1985 and 1996. From all the infant death cases in Hungary 395 (240 male, 155 female) were SIDS (odds ratio (OR)=1.179, with 95% confidence interval (CI)=0.961, 1.446), in Japan 4348 (2550 male, 1798 female) were SIDS (OR=1.145, with 95% CI=1.076, 1.218) and in Tokyo 307 (178 male, 129 female) were SIDS (OR=1.128, with 95% CI=0.894, 1.423). Male infants showed a significantly higher birth rate than females. The male infants are more vulnerable (p<0.005), however, higher mortality among male infants should not be considered a characteristic feature for SIDS.

International Child Care Practices Study: infant sleeping environment

BACKGROUND

The International Child Care Practices Study (ICCPS) has collected descriptive data from 21 centres in 17 countries. In this report, data are presented on the infant sleeping environment with the main focus being sudden infant death syndrome (SIDS) risk factors (bedsharing and infant using a pillow) and protective factors (infant sharing a room with adult) that are not yet well established in the literature.

METHODS

Using a standardised protocol, parents of infants were surveyed at birth by interview and at 3 months of age mainly by postal questionnaire. Centres were grouped according to geographic location. Also indicated was the level of SIDS awareness in the community, i.e. whether any campaigns or messages to "reduce the risks of SIDS" were available at the time of the survey.

RESULTS

Birth interview data were available for 5488 individual families and 4656 (85%) returned questionnaires at 3 months. Rates of bedsharing varied considerably (2-88%) and it appeared to be more common in the samples with a lower awareness of SIDS, but not necessarily a high SIDS rate. Countries with higher rates of bedsharing appeared to have a greater proportion of infants bedsharing for a longer duration (>5 h). Rates of room sharing varied (58-100%) with some of the lowest rates noted in centres with a higher awareness of SIDS. Rates of pillow use ranged from 4% to 95%.

CONCLUSIONS

It is likely that methods of bedsharing differ cross-culturally, and although further details were sought on different bedsharing practices, it was not possible to build up a composite picture of "typical" bedsharing practices in these different communities. These data highlight interesting patterns in child care in these diverse populations. Although these results should not be used to imply that any particular child care practice either increases or decreases the risk of SIDS, these findings should help to inject caution into the process of developing SIDS prevention campaigns for non-Western cultures.

Unmasking of silent "task-related" neuronal activity in the monkey prefrontal cortex by a GABA(A) antagonist

To examine the role of GABA on prefrontal neuronal activity in the control of behavior, a GABA(A) receptor antagonist, bicuculline methiodite (BMI), was iontophoretically applied to prefrontal neurons while monkeys performed a visual reaction time task. Iontophoretic application of BMI uncovered "task-related" activity of silent neurons (n=40), which did not show any activity during performance of the task. The distribution, by type, of these silent "task-related" neurons differed from that of standard (i.e. active) task-related neurons (N=95), and a particular type of silent "task-related" neuron was found most frequently. These findings suggest that GABA continuously and preferentially suppresses neuronal activity via GABA(A) receptors to limit the population of prefrontal neurons related to behavior, thereby organizing neuronal activities for behavior mediated by the prefrontal cortex.

Parallel visuospatial and audiospatial working memory processes in the monkey dorsolateral prefrontal cortex

The dorsolateral area of the prefrontal cortex (PFC) in primates is involved in visuospatial working memory, but the cellular basis of spatial working memory for auditory information is poorly understood. Here we examined dorsolateral PFC neurons using visual and auditory oculomotor delayed-response tasks. We found that the dorsolateral PFC contains two groups of neurons, each showing directional delay-period activity depending on the location of the visual or auditory cue, suggesting that parallel neuronal processes for visual and auditory spatial working memory occur in the dorsolateral PFC.