Impact of occlusal force on decline in body mass index among older Japanese adults: Finding from the SONIC study

OBJECTIVES

To determine any independent influence of occlusal force and of number of natural teeth on decline in body mass index (BMI) among older Japanese adults.

DESIGN

Longitudinal study over a 3- to 6-year period.

SETTING

Urban and rural area in Japan.

PARTICIPANTS

Independently living Japanese adults aged 69-71 years and 79-81 years at baseline. This analysis excluded participants who were defined as underweight at baseline.

MEASUREMENTS

Information was collected on age, gender, occlusal force, the number of teeth, BMI, socioeconomic factors, medical history, the number of daily prescription medications, cognitive function, depressive symptoms, hand grip strength, and physical function. Maximal occlusal force was measured with a pressure-sensitive sheet. Nutritional status was assessed using BMI, and participants with BMI <21.5 were defined as underweight. Then, they were divided into two groups: a "BMI declined" group who were defined as underweight at either 3- or 6-year follow-up survey, and a "BMI maintained" group who were not defined as underweight at both follow-up surveys. Logistic generalized estimating equation (GEE) models were used to assess the effect of occlusal force and the number of teeth at baseline on decline in BMI over 3 or 6 years, after adjusting for possible covariates associated with nutritional status.

RESULTS

The final analysis included 704 participants. Eighty-six (12.2%) participants were classified into the BMI declined group. Logistic GEE models showed that the number of teeth was not significantly associated with decline in BMI. However, occlusal force was significantly associated with decline in BMI (odds ratio = 0.90, 95% confidence interval = 0.83-0.97) after adjusting for covariates.

CONCLUSION

Participants with lower occlusal force were more likely to be in the BMI less than 21.5 kg/m² . The findings suggest that to prevent decline in oral function is important to maintain nutritional status.

Factors Influencing the Localization of Mandibular Third Molars in Twins

PURPOSE

The aim of the present study was to evaluate the genetic and environmental factors influencing the localization of mandibular third molars by analyzing the panoramic radiographs of twins. We examined the mandibular third molars of Japanese monozygotic (MZ) and dizygotic (DZ) twins recruited by the Osaka University Center for Twin Research.

MATERIALS AND METHODS

The present study included 49 pairs (98 participants) of MZ twins and 11 pairs (22 participants) of DZ twins. Using panoramic radiography, we evaluated the degree of eruption of mandibular third molars according to the height of the alveolus bone and the third molar space/crown width ratio. Using co-twin control analysis and a generalized linear mixed model, we evaluated the effects of various factors, including gender, age, body height, number of teeth, length of the lower dental arch, existence of a second molar, bruxism, and previous orthodontic therapy.

RESULTS

Body height, third molar space/crown width ratio, and length of the mandibular dental arch were related to the degree of mandibular third molar eruption and were strongly influenced by genetic factors rather than common or unique environmental factors.

CONCLUSIONS

The degree of third molar eruption was more similar among MZ twins than among DZ twins; therefore, genetic factors can be expected to have more significant influence than will environmental factors. These results can help identify the trend of third molar eruption from a young age, allowing us to advise the early extraction of mandibular third molars for patients with a short stature, narrow retromolar space, or short mandibular dental arch. In addition, if the genes that influence the degree of eruption were identified, we would be better equipped to predict an individual's risk of impaction, and indications for extraction might change.

Relationship between oral stereognostic ability and dietary intake in older Japanese adults with complete dentures

PURPOSE

Oral stereognostic ability (OSA) is a useful indicator of oral perception to recognize food characteristics during mastication. Previous studies have shown associations between dietary intake and oral health status, such as taste perception. However, the effect of oral sensory ability on dietary intake is unclear. The purpose of this study was to investigate the association between oral sensory ability and dietary intake in older Japanese complete denture wearers.

METHODS

This cross-sectional study included 164 participants aged 69-71 or 79-81years old, wearing both maxillary and mandibular complete dentures. OSA test was used to evaluate oral tactile perception. Diet during the preceding month was assessed using a self-administered diet history questionnaire. Multivariable linear regression analysis was conducted to assess the association between OSA score and food and nutrient intake after adjusting for age, sex, socioeconomic factors, and occlusal force.

RESULTS

The bivariate analysis showed that OSA score was significantly and positively correlated with intake of green and yellow vegetables and negatively correlated with intake of cereals among examined foods. OSA score was also positively correlated with intake of vitamins A, B₂, and C and α-tocopherol (as a substitute for vitamin E) among examined nutrients. After adjusting for age, sex, socioeconomic factors, and occlusal force, OSA score remained significantly associated with intake of green and yellow vegetables and α-tocopherol.

CONCLUSIONS

OSA was significantly associated with intake of green and yellow vegetables in older complete denture wearers.

Association of handgrip strength with various oral functions in 82- to 84-year-old community-dwelling Japanese

OBJECTIVE

The purpose of this study was to elucidate the associations between muscle strength and several oral functions in a large cohort of community-dwelling, 82- to 84-year-old community-dwelling Japanese people.

BACKGROUND DATA DISCUSSING THE PRESENT STATUS OF THE FIELD

Several studies have examined the relationships between physical performance and oral functions. However, no studies have investigated the associations of muscle strength with various objectively evaluated oral functional parameters in a large cohort of very old adults.

MATERIALS AND METHODS

This study included 809 community-dwelling Japanese people (407 men and 402 women) aged 82-84 years. The oral functions examined were the maximal occlusal force, masticatory performance, stimulated salivary flow rate, repetitive saliva-swallowing test (RSST) score, tongue pressure and mouth-opening distance. Handgrip strength was measured, and its correlations with oral functions were assessed. Multiple linear and logistic regression analyses were performed to investigate the relationships between oral functions and handgrip strength.

RESULTS

Multivariate analysis revealed that handgrip strength was correlated with not only the maximal occlusal force, masticatory performance and tongue pressure but also the RSST score and mouth-opening distance after adjustment for sex, number of teeth, use of removable denture, periodontal condition, instrumental activities of daily living, body mass index. When we examine the elderly people whose handgrip strength is declining, we should predict that their various oral functions may be declining.

CONCLUSION

Handgrip strength was related to various oral functions after adjustment for the number of teeth in this population of community-dwelling 82- to 84-year-old Japanese.

Occlusal force is correlated with cognitive function directly as well as indirectly via food intake in community-dwelling older Japanese: From the SONIC study

BACKGROUND

Growing evidence suggests that oral health may be an important factor associated with cognitive function in aged populations. However, many previous studies on this topic used insensitive oral indicators or did not include certain essential covariates. Thus, we examined the association between occlusal force and cognitive function in a large sample of older adults, controlling for dietary intake, vascular risk factors, inflammatory biomarkers, depression, and genetic factors.

METHODS

In this cross-sectional study of older community-dwelling Japanese adults, we examined data collected from 994 persons aged 70 years and 968 persons aged 80 years. Cognitive function was measured using the Japanese version of the Montreal Cognitive Assessment (MoCA-J). Oral status and function were evaluated according to the number of remaining teeth, periodontal pocket depth, and maximal occlusal force. Associations between MoCA-J scores and occlusal force were investigated via bivariate and multivariate analyses.

RESULTS

Education level, financial status, depression score, and intake of green and yellow vegetables, as well as number of teeth and occlusal force, were significantly correlated with MoCA-J scores in both age groups. Among individuals aged 80 years, CRP and periodontal status were weakly but significantly associated with MoCA-J score. After controlling for all significant variables via bivariate analyses, the correlation between maximal occlusal force and cognitive function persisted. A path analysis confirmed the hypothesis that cognitive function is associated with occlusal force directly as well as indirectly via food intake.

CONCLUSIONS

After controlling for possible factors, maximal occlusal force was positively associated with cognitive function directly as well as indirectly through dietary intake.

Dietary Intake Is Associated with Occlusal Force Rather Than Number of Teeth in 80-y-Old Japanese

There has been a growing interest in the association between the number of teeth and dietary intake in older populations. However, people around the age of 80 y have frequently lost most of their teeth, and dental prostheses replacing the missing teeth play an important role in masticatory function. Therefore, masticatory function cannot be evaluated by the number of teeth alone. The occlusal force of the complete dental arches is an index of masticatory function, reflecting not only the number of teeth, but the effect of removable dentures. The purpose of this cross-sectional study was to determine the relative importance of the number of teeth and occlusal force in association with dietary intake in 80-y-old Japanese people.

This study included 760 community-dwelling Japanese people aged 79 y to 81 y. The authors measured bilateral maximal occlusal force in the intercuspal position using pressure-sensitive sheets. Removable denture wearers kept their dentures in place during the measurements. Energy-adjusted food groups and nutrient intake during the preceding month were assessed by a brief self-administered diet history questionnaire. The authors assessed linear trends in food and nutrient intake in relation to the number of teeth and occlusal force after adjusting for gender and socioeconomic status (education level, financial status, family structure, resident area and BMI). P values of < 0.05 were considered to be statistically significant.

The authors found that the number of teeth was not associated with the energy-adjusted intake of any food group examined. In contrast, a decline in occlusal force was significantly associated with a lower intake of vegetables, fish and shellfish, protein, polyunsaturated fatty acids, dietary fiber and most vitamins and minerals ( P for trend < 0.05). We conclude that food and nutrient intake was more closely associated with occlusal force than the number of teeth in community-dwelling Japanese people aged 79 y to 81 y.

Knowledge Transfer Statement: This cross-sectional study of older Japanese people showed that, after controlling for considerable covariates, occlusal force rather than the number of teeth is positively associated with energy-adjusted intake of vegetables, fish and shellfish, protein, polyunsaturated fatty acids, dietary fiber and most of vitamins and minerals. This means that reduced occlusal force may unconsciously lead older people toward a habitual unhealthy dietary intake. Older people have frequently lost most of their teeth and require prosthetics to restore masticatory function. Bilateral occlusal force is therefore a better measure of masticatory function than the number of remaining teeth. Our findings suggest that prosthetic rehabilitation is a significant factor in the prevention and management of chronic diseases and frailty through better dietary intake in older populations.

Association between salivary flow rate and depressive symptoms with adjustment for genetic and family environmental factors in Japanese twin study

OBJECTIVES

The association between salivary flow rate (SFR) and depressive symptoms have been inconclusive. The present study aimed to investigate the association between SFR and depressive symptoms with and without adjustment for genetic and family environmental factors.

MATERIALS AND METHODS

We conducted a cross-sectional study using twins and measured SFR and depressive symptoms as the outcome and explanatory variables, respectively. We also performed three-step regression analyses by first analysing the association between SFR and depressive symptoms without adjustment for genetic and family environmental factors (individual-level analyses). We then performed between-within analyses using monozygotic (MZ) and same-sex dizygotic (DZ) twin pairs, and finally using only MZ twin pairs. These between-within analyses estimated the coefficients adjusted for genetic and family environmental factors. Furthermore, differences in the associations between individual-level and between-within suggest confounding by genetic and family environmental factors.

RESULTS

We conducted 448 twins aged ≥20 years. In individual-level analyses in males and between-within analyses using MZ and same-sex DZ male twin pairs, SFR associated with depressive symptoms. In between-within analyses using only MZ male twin pairs, SFR did not associate with depressive symptoms. In females, SFR did not associate with depressive symptoms in both individual-level and between-within analyses.

CONCLUSIONS

The present study revealed that the association between SFR and depressive symptoms was affected by common genetic factors in males.

CLINICAL RELEVANCE

Understanding this association between SFR and depressive symptoms with adjustment for genetic and family environmental factors could lead to an important consideration for the prevention and treatment of hyposalivation.

A field survey of the partially edentate elderly: Investigation of factors related to the usage rate of removable partial dentures

Although the shortened dental arch (SDA) concept has been known to all over the world, acceptance of the SDA concept as an oral health standard can be questionable from the patients' point of view, even if it is biologically reasonable. Furthermore, because the health insurance system covers removable partial dentures (RPDs) for all citizens in Japan, SDA patients seem to prefer to receive prosthetic treatment to replace the missing teeth. However, there were few field surveys to investigate the usage rate of RPDs in Japan. The purpose of this study was to determine the usage rate of RPDs in older Japanese subjects and to investigate the factors related to the usage of RPDs. Partially edentate participants (n = 390) were included in this study. Oral examinations were conducted to record several indices. The Cochran-Armitage trend test was used to evaluate the relationship between the number of missing teeth and the usage rate of RPDs. Chi-squared tests and logistic regression analysis were conducted to evaluate the factors related to the usage rate of RPDs. Usage of RPDs had a significantly positive association with the number of missing distal extension teeth and bilaterally missing teeth. The usage rate of RPDs increased as the number of missing distal extension teeth increased (P for trend < 0·001). The conclusion of this study was that participants with missing distal extension teeth had higher usage rates of RPDs than other participants, and the usage rate increased as the number of missing distal extension teeth increased.

Examination of the Relationship between Oral Health and Arterial Sclerosis without Genetic Confounding through the Study of Older Japanese Twins

OBJECTIVE

Although researchers have recently demonstrated a relationship between oral health and arterial sclerosis, the genetic contribution to this relationship has been ignored even though genetic factors are expected to have some effect on various diseases. The aim of this study was to evaluate oral health as a significant risk factor related to arterial sclerosis after eliminating genetic confounding through study of older Japanese twins.

SUBJECTS AND METHODS

Medical and dental surveys were conducted individually for 106 Japanese twin pairs over the age of 50 years. Maximal carotid intima-media thickness (IMT-Cmax) was measured as a surrogate marker of arterial sclerosis. IMT-Cmax > 1.0 mm was diagnosed as arterial sclerosis. All of the twins were examined for the number of remaining teeth, masticatory performance, and periodontal status. We evaluated each measurement related with IMT-Cmax and arterial sclerosis using generalized estimating equations analysis adjusted for potential risk factors. For non-smoking monozygotic twins, a regression analysis using a "between within" model was conducted to evaluate the relationship between IMT-Cmax and the number of teeth as the environmental factor controlling genetic and familial confounding.

RESULTS

We examined 91 monozygotic and 15 dizygotic twin pairs (males: 42, females: 64) with a mean (± standard deviation) age of 67.4 ± 10.0 years. Out of all of the oral health-related measurements collected, only the number of teeth was significantly related to arterial sclerosis (odds ratio: 0.72, 95% confidence interval: 0.52-0.99 per five teeth). Regression analysis showed a significant association between the IMT-Cmax and the number of teeth as an environmental factor (p = 0.037).

CONCLUSIONS

Analysis of monozygotic twins older than 50 years of age showed that having fewer teeth could be a significant environmental factor related to arterial sclerosis, even after controlling for genetic and familial confounding.

Influence of genetic and environmental factors on oral diseases and function in aged twins

This study was conducted to quantify the genetic and environmental contributions to oral disease and function in twins. Participants were middle-aged and old twins, 116 monozygotic and 16 dizygotic pairs whose mean age was 66·1 ± 10·3 (SD) years. Number of teeth, percentage of decayed, filled and missing teeth and periodontal status were recorded as indicators of oral disease. The widths of upper and lower dental arch served as indicators of morphological figures. Furthermore, stimulated salivary flow rate, occlusal force and masticatory performance were measured as indicators of oral function. Univariate genetic analysis with monozygotic and dizygotic twin pairs was conducted to detect the fittest structural equation model of each outcome. Both number of teeth and periodontal status fitted the model composed of common environmental factor and unique environmental factor. Decayed, filled and missing teeth, morphological figures and measurements of oral function fitted the model composed of additive genetic factor and unique environmental factor. The model fitting of each measurement suggested that periodontal disease was mainly affected by environmental factors, while morphological figures and oral functions were influenced by both genetic and environmental factors.

Overeruption of teeth opposing removable partial dentures: a preliminary study

One of the purposes of prosthodontic treatment is to prevent overeruption of opposing teeth, but there is currently minimal literature describing the efficacy of removable partial dentures (RPDs) in performing this function. This study investigated overeruption following RPD treatment. The study participants were 33 patients treated with RPDs, and overeruption was evaluated by comparing the surface computeraided design data of dental casts made at two different time points-before and after RPD treatment. Overeruption was observed in 38.1% of teeth opposed by the RPD, which was much less than the proportion of teeth that overerupted when not opposed by the RPD.

Comparison of GOHAI and OHIP-14 measures in relation to objective values of oral function in elderly Japanese

OBJECTIVES

The aims of this study were to assess the correlations between the Geriatric Oral Health Assessment Index (GOHAI) and the Oral Health Impact Profile-14 (OHIP-14) and to examine which survey is more sensitive to objectively measured oral function in the Japanese elderly.

METHODS

The subjects were 290 community-dwelling, cognitively healthy, and independently living people over the age of 60 years (mean: 66.3 years). Measures included the GOHAI and OHIP-14 questionnaires, as well as self-rating of general and oral health, dry mouth, number of residual teeth, and objective values of occlusal force, masticatory performance, and salivary flow rate. Bivariate and linear regression analyses were used to identify which of these variables predicted GOHAI and OHIP-14 scores.

RESULTS

Spearman's correlation coefficient between the GOHAI and OHIP-14 scores was 0.728 (P < 0.001), although the OHIP-14 showed a greater number of 0 scores, suggesting a greater floor effect. At the bivariate level, self-rating of general and oral health, dry mouth, number of residual teeth, occlusal force, and masticatory performance were associated with GOHAI and OHIP-14 scores. Multiple linear regression analyses showed that after controlling for the other significant variables, both the occlusal force (standardized regression coefficient [β] = -0.164, P = 0.004) and masticatory performance (β = -0.125, P = 0.019) had significant associations with the GOHAI score, whereas this association was not found with the OHIP score.

CONCLUSIONS

Although the GOHAI and OHIP-14 had a strong correlation, the GOHAI was more sensitive to the objective values of oral functions among independently living elderly persons in Japan.

Clinically acceptable restorations may be a hotbed for cariogenic microbes

OBJECTIVE

The aim of this study was to investigate the cross-sectional association of dental restorations with salivary cariogenic pathogens among the elderly to establish effective parameters of caries risk for this population.

MATERIALS AND METHODS

Stimulated whole saliva was collected from 289 community-dwelling older adults (66.2 ± 3.9 years old) who had 20 or more teeth. Salivary levels of three cariogenic bacteria (Streptococcus mutans, Streptococcus sobrinus and lactobacilli) were estimated using quantitative polymerase chain reaction (real-time PCR) method.

RESULTS

The mean number of residual teeth was 26.4, and restored teeth with crowns, inlays and composite resin were 7.35, 3.88 and 0.68, respectively. The number of crowns correlated positively with salivary S. mutans, S. sobrinus and lactobacilli. Multiple linear regression analyses showed that the number of restored teeth with crowns was independently associated with salivary S. mutans, S. sobrinus and lactobacilli after controlling for age, gender, number of residual teeth and salivary flow rate. Salivary flow rate was independently associated with salivary S. mutans and lactobacilli.

CONCLUSION

The number of crowns had an association with salivary levels of cariogenic bacteria, suggesting that this parameter may be a caries risk indicator for the elderly population.

Shortening the xerostomia inventory

OBJECTIVES

The aim of this study was to determine the validity and properties of the Summated Xerostomia Inventory-Dutch Version in samples from Australia, The Netherlands, Japan, and New Zealand.

STUDY DESIGN

Six cross-sectional samples of older people from The Netherlands (n = 50), Australia (n = 637; n = 245), Japan (n = 401), and New Zealand (n = 167; n = 86) were enrolled. Data were analyzed by using the Summated Xerostomia Inventory-Dutch Version.

RESULTS

All datasets revealed a single extracted factor which explained about one-half of the variance, with Cronbach alpha values ≥0.70. When mean scale scores were plotted against a "gold-standard" xerostomia question, statistically significant gradients were observed, with the highest score seen in those who always had dry mouth, and the lowest in those who never had it.

CONCLUSIONS

The Summated Xerostomia Inventory-Dutch Version is valid for measuring xerostomia symptoms in clinical and epidemiologic research.

Association of masticatory performance with age, gender, number of teeth, occlusal force and salivary flow in Japanese older adults: is ageing a risk factor for masticatory dysfunction?

OBJECTIVE

In general, ageing is a risk factor for sensory and motor deterioration, with the rate of decline varying amongst individuals. Concerning masticatory function, missing teeth along with oral disease seem to accelerate the dysfunction. Here, we aimed to confirm whether masticatory dysfunction by ageing is inevitable. This study investigated the effect of age, gender, number of natural teeth, occlusal force and salivary flow on the masticatory performance in a large sample of elderly adults.

DESIGN

The study sample consisted of 1288 independently living people aged 60-84 years. Masticatory performance was determined by the comminuted particles of test food. Bilateral maximal occlusal force in the intercuspal position was measured with pressure sensitive sheets. Stimulated whole saliva was collected.

RESULTS

Masticatory performance was significantly correlated to age, number of residual teeth, occlusal force and stimulated salivary flow rate by Pearson's correlation test. The multiple linear regression analysis showed that, with other variables controlled, masticatory performance was significantly associated with the number of residual teeth (β=0.456, P<0.001), occlusal force (β=0.244, P<0.001) and stimulated salivary flow rate (β=0.069, P=0.003). Age was not related to masticatory performance (β=-0.007, P=0.753).

CONCLUSIONS

Declines in the number of residual teeth, occlusal force and salivary flow were associated with a reduction of masticatory performance in older adults. If tooth loss is not considered as an attribute of physiological ageing, then ageing by itself may not be a risk factor for masticatory dysfunction.

Incidence and association of root fractures after prosthetic treatment

PURPOSE

Common reasons for tooth extractions include periodontal disease, dental caries and root fracture. The purpose of this study was to investigate the association of tooth loss after prosthetic treatment, particularly incidences due to root fracture, which occur frequently and are difficult to prevent.

METHODS

Data were collected from consecutively selected medical records of patients taken over 3 years after their initial visit to Osaka University Dental Hospital. Collected data included (1) age and gender, (2) number of teeth at the initial visit and number of extracted teeth, (3) reasons for extraction, (4) restored with or without a post and (5) abutment of removable partial dentures (RPDs). A Chi-squared test was applied among the reasons for extraction, whether the tooth was restored with a post or not and clasped or not. A logistic regression analysis was used to determine the associations of root fracture with the patient data.

RESULTS

This study included 101 patients (296 extracted teeth). The reasons for extraction included periodontal disease (64.6%), caries (25.3%) and root fracture (10.1%). The percentage of root fracture was significantly higher for female than male, for restored teeth with posts than without posts and for abutment of RPDs than for non-abutment teeth. Logistic regressions showed that root fractures were significantly associated with gender and abutments.

CONCLUSION

The most frequently stated reasons for tooth extraction after prosthetic treatment were periodontal disease and dental caries, followed by root fracture. Root fractures were significantly associated with gender and abutment teeth of RPDs.

[Survival in patients with clear cell carcinoma of the ovary]

Thirty-one patients with clear cell ovarian carcinoma who underwent primary surgery and postoperative therapy were retrospectively evaluated. Eighteen patients (58%) had International Federation of Gynecology and Obstetrics (FIGO) stage I disease, 3 patients (9.7%) stage II disease, and 10 patients (32.3%) stage III and IV disease. Patients with stage III and IV disease demonstrated a significantly poor prognosis compared with patients who had stage I or II disease (p < 0.01). No patients with stage III and IV disease survived 5 years. p53 protein expression and proliferative activity (PA) were studied by immunohistochemical methods using p53 molecule and antibodies to PCNA (proliferative cell nuclear antigen). Intranuclear accumulations of p53 product were observed in 15 of 31 (48.4%). On the other hand, 15 of 31 (48.4%) patients stained positively for PCNA (> or = 60% of cancer cells stained positively). Positive p53 staining and highly PA were associated with poor survival. Two patients with stage I a relapsed were positive p53 and highly PA. Accordingly, consolidation chemotherapy is necessary for patients with stage I a who are positive p53 and highly PA. Platinum-based chemotherapy for patients who had minimal residual tumor was effective, but 5 patients who had > or = 2 cm tumor burden were not effective at all. The response rate for platinum-based chemotherapy was 20% (1/5) among p53 positive, in contrast to 66.7% (4/6) among p53 negative patients. So it seems that p53 positive patients are chemoresistant.

[Anti-C100-3 antibody titration using 4-parameter logistic curve (results in its application to hepatitis C cases treated with interferon]

We evaluated titers of C100-3 antibody by ELISA using a 4-parameter logistic fitting curve and examined the transition of the values in the cases of interferon treatment. The 4-parameter logistic fitting curve produced a standard curve in a wider range using a micro plate reader than the logarithmic curve. The values of C100-3 antibody during and after the treatments of interferon were changed in parallel with the alterations of ALT. The anti-C100-3 antibody titers assayed in the complete or partial responders were significantly reduced at the end of interferon therapy. These findings suggest the clinical usefulness of the evaluation of anti C100-3 antibody titers.

Purification and characterization of abundant secreted protein in suspension-cultured pumpkin cells : abundant secreted protein may be a chitinase

The abundant secreted protein with molecular weight of 32,000 was purified from the culture medium of suspension-cultured pumpkin (Cucurbita sp.) cells. Two steps, ammonium sulfate fractionation and Sepharose 6B column chromatography, were sufficient for purification to homogeneity. Antibodies against the pure protein were used to show that a protein of the same size is made by callus cells. There is considerable homology between the amino-terminal amino acid sequence of this secreted protein and chitinase isolated from tobacco (Nicotiana tabacum L.) or bean (Phaseolus vulgaris L.).

Procurement and biological significance of pure 11C-glucose

Biological significance of 11C-glucose purity has been a controversial matter. In order to understand the contribution of impurities contained in the photosynthetic 11C-glucose, its analysis and biodistribution in mice was studied. Studies indicated the interference of impurities, particularly 11C-fructose in the injectate, with the quantitative evaluation of glucose metabolic rate in brain. Furthermore, results obtained offered a good basis for search of simpler and easier separation methodology. Namely, good selection and combination of commercially available high performance liquid chromatography (HPLC) column provided 11C-glucose with high radiochemical purity. The radiochemical yield achieved was 6-10% at 75 min after the end of bombardment including the HPLC purification. The imaging study by positron computed tomography in a rabbit showed the suitability of 11C-glucose as a radiopharmaceutical for the diagnosis of the brain function.

[Constant infusion system of 15O labeled-water]

The quantitative measurement of regional blood flow and regional extravascular lung water, called for a design of 15O labeled water production and administration under continuous and constant flow. In our search for simple methodology, suitable for clinical routine facilities, two remote-controlled systems were designed and their applicability for continuous and constant infusion of H215O were tested. In system (A), H215O was prepared from C15O2 based on the fast exchange reaction between carbon dioxide and carbonic acid. In the system (B), the reaction of 15O2 with H2 using palladium as a catalyst was adopted. In the both systems, the radioactivity level of the infusate was kept constant by using a buffer reservoir. Clinical applicability of both fully automated systems for the production of sterile H215O at a continuous and constant rate was discussed. Namely, system (A), being very simple seems more suitable for any closely located facility but system (B) is more suited for the production of higher radioactivity.