Potent and specific action of the mGlu1 antagonists YM-298198 and JNJ16259685 on synaptic transmission in rat cerebellar slices

BACKGROUND AND PURPOSE

Specific and selective inhibitors for mGlu1 receptors are presently inadequate. A new generation of non-competitive mGlu1 antagonists with low nanomolar potencies is emerging. We evaluated two new compounds, YM-298198 and JNJ16259685, for effectiveness, potency and specificity for the first time in a brain slice preparation.

EXPERIMENTAL APPROACH

Patch-clamp recording of Purkinje neurones in cerebellar slices were obtained. The slow mGlu1-mediated EPSP was used to establish a concentration-response curve. Fast excitatory synaptic inputs were tested for non-specific effects.

KEY RESULTS

YM-298198 and JNJ16259685 inhibited the synaptic activation of mGlu1 in a concentration-dependent manner (IC(50) values of 24 nM and 19 nM, respectively). The antagonists were slow to inhibit and to reverse on washout, probably due to their lipophilic nature. There were no non-specific effects on fast AMPA receptor-mediated synaptic transmission in the cerebellum.

CONCLUSIONS AND IMPLICATIONS

These compounds are more than a thousand-fold more potent than previously available compounds. Their selectivity and specificity will be very useful for studying the role of mGlu1 receptors both in vitro and in vivo.

[Association between life events, subjective health status and health practices in a rural population]

A survey has been conducted on subjective health status, experience of life events in recent 1 year, and health practices in the rural of Kagawa prefecture. The survey was performed from March 1995 to May 1995 with 4,013 participants, aged 40 to less than 80. The proportion of respondents who recognized their physical conditions as good decreased with age. However, the proportion of respondents who recognized their life satisfaction as good increased with age. 'Health-related' life events were the most common experienced life events for both male and female. The proportion of respondents who had life events of type 'family', 'financial', 'at workplace or job', 'in the community', and 'others' decreased with age. Men had higher proportion of 'at workplace or job' life events. The higher proportion of respondents who experienced life events recognized their subjective health status poor. For male, it observed that poor physical health status had significant association with experience of type 'in the community' and 'environmental' life events. Poor mental health status significantly associated with experience of type 'at workplace and job' life events for male, and with 'health-related' and 'family' life events for female. Poor life satisfaction significantly associated with 'at workplace or job' and 'in the community' life events for male, and with 'health related' and 'family' life events. Higher proportion of the respondents who experienced life events and recognized their subjective health status poor had low health practice scores. Logistic regression analysis showed that experience of life events and poor subjective health status had significant association with the poor health practices, especially with 'body weight changed' for both male and female.

Abundance of polymers degrading microorganisms in a sea-based solid waste disposal site

In order to assess the degradability of plastics in solid waste disposal landfill sites, microbial populations capable of degrading five kinds of plastic-constituting polymers, poly epsilon-caprolactone (PCL), polylactic acid (PLA), polyethylene glycol (PEG), poly-beta-hydroxybutyrate (PHB) and cellulose acetate (CA), in a sea-based solid waste disposal site were investigated. Enumeration of aerobic and anaerobic polymers-degrading microorganisms (PDMs) was performed against to total 8 leachate samples, which were seasonally collected from the facultative pretreatment pond and the aerated lagoon. Both aerobic and anaerobic PDMs for natural polymers, PHB and CA, were found in all of the samples, while those for chemically-synthesized polymers, PCL, PLA and PEG, could not be always detected. In most cases, the ratios of the PHB- and CA-degraders to the heterotrophic bacterial population were more than 0.1%. On the other hand, the ratios of PCL-, PLA- and PEG-degraders were often much lower. These data indicate that the plastics degradation potential is commonly present in the studied disposal site, and that the degradation potential for plastics composed of chemically-synthesized polymers is inferior to that of natural polymers. Population sizes of the PDMs correlated to those of heterotrophic bacteria, and the counts of aerobic heterotrophic bacteria and PDMs in the aerated lagoon tended to be higher than those of anaerobic ones, indicating that the aeration of the leachate resulted in the activation of growth of whole aerobic microbial community including the PDMs.

[Factors associated with participation in chest X-ray screening by young and middle aged residents]

We investigated the factors that affect participation rates in chest X-ray mass screenings among 20-59 year-old residents in A city, Kagawa prefecture. 1) Participation rates in employees and non-employees were 78.3% and 33.9% respectively. In the employees whose firms do not provide health check-ups, participation rate was 15.9%. 2) Among participants, about 90% of the employees whose firms do not provide health check-ups and about 60% of non-employees utilized mass screenings provided by the local government. 3) Among non-participants, 53.7% of the employees whose firms do not provide health check-ups and 70% of the others (employees whose firms provide health check-ups and non-employees) were aware of the screening system. Most of the young did not know of the system. 4) Principal reasons for nonparticipation were "inconvenient" and "unnecessary because healthy" in job holders and "unnecessary because healthy" in non-job holders. 5) Participants had better health practices than non-participants. Participation rates of chest X-ray mass screenings were high in employees and low in non-employees. Local governments are expected to supplement the existing mass screening system at work-sites by providing accessibility screening. In tuberculosis prevention, nonparticipation in mass screenings is one of the main issues. The association between participation and health practice suggests that methods for linking with primary prevention activities are necessary for stimulating interest and promoting participation in mass screenings.

[A study of health behavior of the elderly without occupation--correlation between participation in health examinations and health behavior]

A survey on the health behavior of inhabitants without occupations, aged 60 or over who lived in city A in Kagawa prefecture (400 people), was performed. The results are summarized as follows: 1. The rates of participation in the general health checkup and the screening for colon cancer were high. In females, significant correlations were observed between the rates of participation in health examinations/screenings and age, but they were not significant in males. 2. The rates of good health practices were high in the items "Taking breakfast", "No change of body weight", "Sleeping adequately" and "Drinking moderately or no drinking". The rate of "Exercise" for males was higher than for females, and the rate of "No smoking" was lower for males than for females. For females, a correlation was observed between the score of good health practices and age, and this score decreased with age, but in males there was no significant difference. 3. The rate of participation in health education or health consultation was about 40 percent, and the rate of participation was larger for female inhabitants than for male inhabitants. 4. Persons who participated in the health examinations/screenings had more healthful practices than who did not participate. A correlation was observed between the rates of participation in health examinations/screenings and "Exercise." 5. Persons who participated in health education or health consultation had more healthful practices than who did not participate. 6. Correlations were observed between the rates of participation in health examinations/screenings and the rate of participation in the health education, or health itself. In this analyzed sample population, the health behavior of primary prevention and secondary prevention were related to each other, and the existence of common factors among health behavior for primary prevention and secondary prevention was estimated. Differences were observed between males and females concerning correlations between health behavior and age. It is thus necessary to improve health behavior via a continuous approach to the lifestyle for women. We think that good health behavior which continues over a long period of time can be instilled by approaching the lifestyle at the time of retirement for men.

[Health activity for prevention of hearing impairment in regional child health]

The role of the regional health administration in to the prevention of hearing impairment in children is to identify children with hearing impairment, ensure timely treatment at a medical facility, and provide appropriate co-ordination with the medical institution. The following three measures are important: 1. Accurate execution of audiological screening and appropriate health guidance are needed. 2. Promotional activity to emphasize early diagnosis and treatment at medical facilities showed be provided. 3. Co-ordination, social changes, report function and support function for usual and complicated cases should be provided should be considered. Behavior at aspects when these measures are accomplished. Not only screening and co-ordination but also to accurate knowledge and changes in attitudes and behavior are necessary for proper advancement of prevention service. In terms of execution of these measures, while provided by the municipal administration, the public health center administration, and medical institutions, the important role of the health center should be emphasized.

[Measurement of ethylene oxide at a medical sterilization site]

Although ethylene oxide gas is widely used as a sterilizing agent for medical instruments because of its disinfection property, the effects of its use in medical settings have not been clarified. In the present study, we measured the ethylene oxide gas concentration (EOGC) within a hospital sterilization unit and in the ambient air near the unit. Before the sterilizer was turned on (about 9:00), the ambient air EOGC was below the detection limit (0.1 ppm). When the door was opened to place the instruments in the sterilizer, the maximum EOGC near the door of the sterilizer was 1.71 ppm. Before the sterilizer door was opened, the residual EOGC within the sterilizer was 0.10-24.56 ppm. During the operation of the sterilizer (9:00-17:00), ethylene oxide gas could not be detected in the air near the unit. When the sterilizer door was opened at the end of the routine operation of the sterilizer (about 17:00), EOGC near the door was 2.10-2.73 ppm. After the door was closed, the ambient air EOGC level was 0.5-0.57 ppm. These findings indicate that the personnel near the unit were exposed to ethylene oxide gas for about 15 min during the transfer. However, no ethylene gas could be detected by the ethylene oxide gas monitor (3M Co., #3551). The finding that EOGC in sterilized medical instruments after 24 h of aeration was about 2 ppm also suggests that the personnel using these instruments were exposed to ethylene oxide gas.(ABSTRACT TRUNCATED AT 250 WORDS)

[Assessment of cadmium and lead released from cigarette smoke]

Cigarette smoke, which contains many harmful compounds, affects not only the smoker's health but also indoor air quality. To evaluate indoor air contamination by cadmium (Cd) and lead (Pb), we measured Cd and Pb contained in the mainstream and sidestream smoke exhaled by experimental smoking of Japanese cigarettes and also determined urinary and blood Cd and Pb levels in smokers and non-smokers and air Cd and Pb levels in smoky environments. 1. One cigarette of each of 7 Japanese brands contained about 1 microgram each of Cd and Pb, of which about 50 ng each was released to the mainstream and 250 ng of Cd and 50 ng of Pb to the sidestream by smoking. 2. The blood Cd level in the smokers was significantly higher than that in the non-smokers. The urinary Cd level in the smokers was slightly higher than that in the non-smokers. The blood Cd level was related to the number of cigarettes smoked daily. Blood and urinary Pb levels did not differ between the smokers and non-smokers, but the blood Pb level was also related to the number of cigarettes smoked daily. 3. The air Cd levels in smoky places such as the smoking car of the special express train, an office, and a pachinko parlor were markedly higher than that in outdoor air. The air Cd concentration was well correlated with the environmental tobacco smoke concentration. On the other hand, the air Pb level was slightly higher in the above smoky places than outdoors. The mean air Pb concentration was not correlated with the environmental tobacco smoke concentration but was higher at higher environmental tobacco smoke concentration in each place.

Electrophysiological and behavioral studies on the taste of umami substances in the rat

Electrophysiological and behavioral experiments were performed to reveal taste properties of "umami" substances such as monosodium glutamate (MSG) and disodium inosine monophosphate (IMP) in rats. To eliminate the taste effects of Na ions contained in these umami substances, we dissolved them in 0.01 mM amiloride, which is known to block sodium responses. In the electrophysiological study, taste responses of the whole chorda tympani nerve were recorded. The magnitude of responses to MSG (or IMP) at concentrations below 0.1 M (or 0.01 M) was less than 10% of that to 0.1 M NaCl. On the other hand, the mixtures of MSG and IMP showed responses 2-7 times larger than the arithmetric sum of the responses to each component of the mixtures. A new sweet taste inhibitor (Gymnema sylvestre extract) strongly suppressed neural responses to mixtures of MSG and IMP as well as sucrose, but only weakly or negligibly to individual solutions of these umami substances. In the behavioral study, the brief exposure two-bottle preference test and conditioned taste aversion paradigm were used. MSG was most preferred at 0.3 M (preference ratio = 57%), IMP, at 0.01 M (61%), and both were less preferred or rejected at higher concentrations. In contrast, mixtures of MSG and IMP were more preferred at a broad concentration range (e.g., 82% for 0.1 M MSG + 0.01 M IMP). Aversive conditioning to umami substances was generalized to sucrose, and vice versa, but not to 0.1 M NaCl, 0.01 M HCl, and 0.1 mM quinine hydrochloride.(ABSTRACT TRUNCATED AT 250 WORDS)