PubMed Health⌕ Search

Biomedical subjects

R Sasa

Publications and source records attributed to R Sasa.

At least 19 recordsLinked to original sources
PubMed2005

Localization and properties of respiratory neurons in the rostral pons of the newborn rat.

The distribution and discharge pattern of respiratory neurons in the 'pneumotaxic center' of the rostral pons in the rat has remained unknown. We performed optical recordings and whole-cell patch clamp recordings to clarify respiratory neuron activity in the rostral pons of a brainstem-spinal cord preparation from a newborn rat. Inspiratory nerve activity was recorded in the 4th cervical nerve and used as a trigger signal for optical recordings. Respiratory neuron activity was detected in the limited region of the rostral-lateral pons. The main active region was presumed to be primarily the Kölliker-Fuse nucleus. The location of respiratory neurons was further confirmed by Lucifer Yellow staining after conducting whole-cell recordings. From a membrane potential analysis of the respiratory neurons in the rostral pons, the respiratory neurons were divided into four types: inspiratory neuron (71.9%), pre-inspiratory neuron (5.3%), post-inspiratory neuron (19.3%), and expiratory neuron (3.5%). A noticeable difference between pontine and medullary respiratory neurons was that post-inspiratory neurons were more frequently encountered in the pons. Application of a mu-opioid agonist, [d-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin, transformed the burst pattern of post-inspiratory neurons into that of pre-inspiratory neurons. The electrical stimulation of the sensory root of the trigeminal nerve induced three types of responses in 85% of pontine respiratory neurons: inhibitory postsynaptic potentials (42.7%), excitatory postsynaptic potentials (37.7%) and no response (15.1%). Our findings provide the first evidence in the rat for the presence of respiratory neurons in the rostral pons, with localization in the lateral region approximately overlapping with the Kölliker-Fuse nucleus.

Animals↗
PubMed2004

Species-specific PCR method for identification of Streptococcus downei.

AIMS: To establish a rapid method to differentiate Streptococcus downei and S. sobrinus by multiplex PCR. METHODS AND RESULTS: A PCR primer pair specific to S. downei was designed on the basis of the nucleotide sequence of the dextranase gene of S. downei NCTC 11391T. The primer pair specifically detected S. downei, but none of the other mutans streptococci (16 strains of six species). The PCR procedure was capable of detecting 1 pg of genomic DNA purified from S. downei NCTC 11391 and as few as 14 CFU of S. downei cells. The mixture of primer pairs specific to each S. downei (this study) and S. sobrinus (Igarashi et al. 2000) detected only the strains of these two species among all the mutans streptococcal strains, and concomitantly differentiated the two species by species-specific amplicons of different lengths. CONCLUSIONS: The present PCR method is highly specific to S. downei and is useful for detection and identification of S. downei. SIGNIFICANCE AND IMPACT OF THE STUDY: Multiplex PCR using dextranase gene primers is a useful method for simultaneous detection and differentiation of S. downei and S. sobrinus.

DNA, Bacterial↗
PubMed2002

Effect of multiple application of dentin bonding agent on marginal integrity of resin composite.

The purpose of the present study was to examine the effect of multiple application of dentin bonding agent to the adhesive surface on the marginal integrity of resin composite. The effect of multiple applications was evaluated by measuring the wall-to-wall polymerization contraction gap and by SEM observation. Multiple application of dentin bonding agent was found to prevent formation of the contraction gap. Although monomer penetration into the enlarged collagen network has been widely discussed as the possible mechanism of the dentin bonding agent and dentin primer, the true detailed mechanism of the dentinal bonding agent and dentin primer should be consistently explained by the prevention of monomer diffusion into the dentin and water contamination of the adhesive interface.

Acid Etching, Dental↗
PubMed2001

Identification of Streptococcus salivarius by PCR and DNA probe.

AIMS: To establish species-specific PCR and DNA probe methods for Streptococcus salivarius and to clarify the distribution of dextranase in oral isolates of Strep. salivarius. METHODS AND RESULTS: A pair of PCR primers and a DNA probe were designed based on the nucleotide sequence of the dextranase gene of Strep. salivarius JCM5707. Both the PCR primer and the DNA probe specifically detected Strep. salivarius but none of the other oral streptococci (23 strains of 13 species). The primer and the probe were capable of detecting 1 pg and 1 ng of the genomic DNA, respectively, purified from Strep. salivarius JCM5707. All oral isolates (130 strains from 12 subjects) of Strep. salivarius from human saliva were positive by both methods. CONCLUSION: The present PCR and DNA probe methods are highly specific to Strep. salivarius and are useful for the its detection and identification of this bacterium. The dextranase widely distributes among oral isolates of Strep. salivarius. SIGNIFICANCE AND IMPACT OF THE STUDY: The DNA sequence of a dextranase gene present in the genome of Strep. salivarius is useful as the target DNA of the species-specific PCR and DNA probe.

DNA Primers↗
PubMed2001

Efficacy of dentin adhesives in primary and permanent teeth.

The purpose of the present study was to investigate the efficacy of dentin adhesives and to examine acid resistance in primary and permanent teeth. The efficacy of dentin adhesives was evaluated by SEM observation and by measuring the wall-to-wall polymerization contraction gap and dentin hardness before and after conditioning. The detailed mechanism of dentin bonding was the same in both primary and permanent teeth.

Acid Etching, Dental↗
PubMed2000

Two distinct hemolysins in Trichomonas tenax ATCC 30207.

An oral protist Trichomonas tenax ATCC 30207 was investigated for the ability to lyse erythrocytes of sheep, rabbits, horses and humans. Five fractions, including intact cells, culture supernatant, culture filtrate, cell debris and lipid-enriched fractions, were prepared from the protozoan cells, and their hemolytic activities were assayed under various conditions. All the samples except culture supernatant had hemolytic activities, which were due to two different kinds of hemolysins. One hemolysin was protein-like and mainly found in cell-free fractions: culture supernatant and culture filtrate. It was heat-labile and inhibited by various cysteine-proteinase inhibitors. The other hemolysin was lipid-like and found in cell-associated fractions: intact cells, cell-debris and lipid-enriched fractions. It was heat-stable, organic solvent-tolerant and unaffected by various proteinase inhibitors and stimulators. These results suggested that T. tenax ATCC 30207 possessed two distinct hemolysins, protein and lipid.

Animals↗
PubMed2000

Fructooligosaccharide consumption enhances femoral bone volume and mineral concentrations in rats.

We examined whether the enhanced mineral absorption resulting from fructooligosaccharide (FOS) consumption affects femoral bone structure and mineral concentrations, using histomorphometrical and X-ray microanalysis. Male Wistar rats (n = 16; 42 d old) were divided into two groups, a control group (n = 8) and a FOS group (5 g/100 g FOS in the diet, n = 8). After a 3-d adaptation period, constant amounts of calcium (95 mg/d) and magnesium (8 mg/d) were fed to the rats in each group, using a pair-feeding protocol. At age 60 d, a 3-d metabolic study was initiated. Calcium and magnesium absorptions were calculated. The rats were then killed, and the right femur was embedded in polyester resin. The distal metaphysis was sagittal-sectioned, and the middle of the diaphysis and neck were cross-sectioned. Calcium, magnesium and phosphorus concentrations in the three samples were then measured. Calcium and magnesium absorptions were significantly greater in FOS-fed rats. Trabecular bone volume at the metaphysis and bone volume at the neck of the femur in FOS-fed rats were also significantly greater than those in control rats. The mineral concentration (Ca, Mg and P) in each region of the bone surface was greater in FOS-fed rats. There was a significant relationship between absorbed calcium and calcium concentrations in bone (r = 0.722, P < 0.001), and a similar relationship was found for magnesium (r = 0.720, P < 0.001). These results suggest that the enhanced calcium and magnesium absorption due to FOS consumption might enhance femoral bone volume and mineral concentrations.

Absorption↗
PubMed2000

2-year observation of attachment loss in a rural Chinese population.

BACKGROUND: Risk indicators for periodontitis seem to vary with study population. The purpose of this study was to determine whether risk indicators of additional attachment loss differ between generations of Chinese villagers in a rural area of China over a 2-year period. METHODS: The study population consisted of 310 subjects aged 15 to 44. In each subject, 2 quadrants from either the upper or lower jaw were randomly selected and 6 sites on each tooth were examined. Clinical parameters included plaque scoring system (PSS), calculus index (CI), probing depth (PD), attachment level (AL), and sulcus bleeding index (SBI). The second examination was done 2 years after the first. RESULTS: In the 15- to 24-year-old age group, mean PSS, CI, and SBI were significantly higher in subjects with additional attachment loss > or =3 mm (AL+) than in those without attachment loss (AL-). In the 25- to 34-year-old age group, mean PD was significantly higher in AL+ than in AL-, and mean PD and AL were significantly higher in AL+ than in AL- in the 35- to 44-year-old age group. Although the number of subjects with AL+ increased with age, the mean number of sites with AL+ per subject did not differ by generation. In addition, smokers tended to exhibit attachment loss more often than non-smokers. CONCLUSIONS: The present results suggest that the clinical parameters associated with attachment loss differ between generations and that gingival inflammation is likely associated with the onset of periodontitis more strongly than progression of periodontitis, whereas PD and/or AL are associated with the progression of periodontitis.

Adolescent↗
PubMed2000

Detection of bisphenol-A in dental materials by gas chromatography-mass spectrometry.

The xenoestrogenic substance bisphenol-A is widely used as a synthetic precursor of resin monomers, such as bisphenol-A diglycidyl methacrylate. Reports describing the release of bisphenol-A from polymerized resin into saliva have aroused considerable concern regarding exposure to xenoestrogen by dental treatment. The purpose of the present study was to demonstrate a reliable methodology of detecting the trace amounts of bisphenol-A in dental materials. Bisphenol-A was separable from bisphenol-A diglycidyl methacrylate, which is often employed as the principal dimethacrylate monomer, by selective extraction with a Sep-Pak C18 cartridge. Using this extraction method in combination with a gas-chromatography mass-spectrometry, we have obtained evidence that all unpolymerized materials used in this study were contaminated with bisphenol-A. Quantitative analysis using a deuterium-labeled compound as an internal standard revealed bisphenol-A contents in commercial dental materials ranging from < 1 microgram/g material to about 20 micrograms/g material. The polymerized dental materials released up to 91.4 ng bisphenol-A/g material into phosphate buffered saline during 24-h incubation. These results indicate that bisphenol-A can be released from dental materials, however the leachable amount would be less than 1/1000 of the reported dose (2 micrograms/kg body weight/day) required for xenoestrogenisity in vivo.

Benzhydryl Compounds↗
PubMed1999

A DNA probe specific to Streptococcus sobrinus.

Three DNA fragments (SSB-1, -2 and -3) in the dextranase gene (dex) of Streptococcus sobrinus were amplified by polymerase chain reaction and used as DNA probes. The probes were examined for the specificity and the sensitivity of hybridization with DNA of oral streptococcal species. While probes SSB-1 and SSB-2 were specific to both S. sobrinus and Streptococcus downei, SSB-3 was specific only to S. sobrinus. SSB-3 was able to detect 5 ng of chromosomal DNA purified from S. sobrinus NIDR6715 and DNA extracted from 1 x 10(5) cells of the strain. In addition, SSB-3 could differentiate clinical isolates of S. sobrinus from Streptococcus mutans. These results suggest that SSB-3 is an effective DNA-probe to detect and to identify S. sobrinus.

Bacterial Proteins↗
PubMed1999

Attachment loss in rural Chinese children over a 3-year period.

OBJECTIVES: The periodontal condition of 84 children (9-14 years old, 38 males and 46 females) in a rural area of China was monitored over a 3-year period in order to determine the clinical parameters that act as risk factors for attachment loss. METHODS: Plaque and calculus accumulation (PSS and CI), modified gingival index (MGI), pocket depth (PD) and attachment level (AL) of two quadrants of each child were examined in 1993 and 1996. Following calculation of the mean of each of these parameters and statistical analysis of the change in each of the clinical parameters over the 3-year period, the relationship between attachment loss and clinical parameters was analyzed using multiple regression analysis. RESULTS: At the beginning of this study, the mean values for males and females were 3.66 and 3.58 for PSS, 1.22 and 1.17 for MGI, 1.07 and 0.90 for CI, 2.21 and 2.22 for PD, and both 0.02 for AL respectively. No significant difference between males and females was observed. After 3 years, all except mean PSS had increased significantly. Multiple regression analysis indicated that AL correlated only to age (P<0.01). In 1993, although the AL was > or =1 mm for at least one site in 21 children, none had an AL> or =3 mm. In 1996, the number of children with an AL> or =1 mm had increased to 63, and nine of these children exhibited 3 mm AL (one to six sites per child). No other significant differences were observed between the clinical data of these nine children and those of the other children. CONCLUSION: Although attachment loss tended to increase with age, no clinical parameters correlated with attachment loss in children.

Adolescent↗
PubMed1999

Resin content in cement liquids of resin-modified glass ionomers.

Qualitative and quantitative analyses were conducted on four kinds of resin-modified glass ionomer (RMGI) cement liquids, LC, LC II, LC III (hereinafter referred to as LCs) and VM, using HPLC and laser Raman spectroscopic methods. HPLC revealed that among the RMGI liquids LCs contain 31-32% HEMA (2-Hydroxyethyl methacrylate), and VM contains 18% of the same. The composition of RMGI cement liquids varied significantly between manufacturers. In Raman spectroscopic analyses, the spectra of liquids of various ratios of polyacrylic acid and HEMA were measured, and calculations were made on the peak intensity ratios of C=C stretch vibration to C=O stretch vibration, common in both HEMA and polyacrylic acid. The composition ratio of polycarboxylic acid to HEMA of commercial glass ionomer cements was assessed by the regression curve generated by a combination of peak intensity ratios and composition ratios. In addition, Raman spectroscopy was able to identity the differences in form of the methacryloyloxy group.

Carboxylic Acids↗
PubMed1998

Sexual dimorphism in the tooth crown dimensions of the second deciduous and first permanent molars of Taiwan Chinese.

Sexual dimorphism in the crown components in the second deciduous molar (dm2) and the first permanent molar (M1) of the dental casts taken from Chinese living in Kaohsiung (Taiwan) was investigated. Mesiodistal and buccolingual crown diameters, and 4 main-cusp sizes in the maxillary molars and mesiodistal diameters of the trigonid and talonid in the mandibular molars were measured using a digital caliper (0.01 mm). Percentage sexual differences were calculated. With the exception of trigonid mesiodistal diameters, the mean values of males were larger than females. In both of dm2 and M1 the mean values of the trigonid mesiodistal diameters were slightly larger in females than in males, but the differences were not significant. Percentage sexual dimorphism was smaller in the mesiodistal diameters than in the buccolingual in both dm2 and M1. The crown components showed larger sexual difference in dm2 than in M1, while in the maxilla the external crown size showed larger sexual difference in M1 than in dm2. The buccal cusps showed larger sexual difference than the lingual in the maxillary molars and the talonid showed larger sexual difference than the trigonid in the mandibular. Sexual dimorphism of dm2 and M1 in their crown components displayed similar pattern, although the different degree was noted. This result is thought to relate to the fact these molars belong to the first dentition embryologically.

China↗
PubMed1991

[Studies on the changes of adaptation with children in the dental setting. The relationship between the changes of adaptation and various psychological tests].

The purpose of this study was to discover the changes in the adaptation of children to the Dental setting, and to discover the relationship between the adaptation, and the personality of the child, the personality of the mother, as well as the relationship between the mother and child. The subjects were 60 two to six year old children and their mothers who visited at the Department of Pedodontics, School of Dentistry, Showa University. The results were as follows: 1) The changes of adaptation were classified in groups of four classes. Four groups: Continuous Adaptability (45.0%) Acquired Adaptability (18.3%) Continuous Inadaptability (16.7%) Extreme Inadaptability (20.0%) 2) The inadaptability groups (Continuous Inadaptability and Extreme Inadaptability) of the two to three year old children did not correlate to the change of adaptation and personality of the child, and the relationship between the mother and child. 3) The extreme inadaptability group with the four year old children showed a connection with the change of adaptation and the various Psychological Tests. Concerning personality, the children showed elements of "dependence" "retrogression" and "maladaptation to school (kindergarten)". Concerning the mother child relationship, there were elements of "anxiety" "dotage" "follow blindly" "disagreement". 4) Nobody showed extreme inadaptability in the group of five to six year old children. Continuous Inadaptability group with the five to six year old children showed scarcely any problems. 5) The Personality of mother did not correlate to the change of adaptation of children in the dental setting.

Adaptation, Psychological↗
PubMed1990

[Dental findings in a case of Chondrodysplasia Punctata].

Chondrodysplasia Punctata is a disease belonging to the metaphysia syndrome. This disease is characterized by endochondral punctata calcification of epiphysis or apophysis, short legs and hands, arthrogryposis, saddle nose, ichthyosis, cataract and mental retardation. This report concerns a case of Chondrodysplasia Punctata (Rhizomeric form) in a 4 year 1 month old girl. Observations were made from the dental point of view, and the findings were as follows: 1) The mesio-distal and bucco-lingual lengths of all primary teeth were smaller than the standard size. 2) Measuring the dental cast, the width of the dental arch was found to be larger, but the length of the arch was found to be smaller than the standard size. 3) The value of the palatal height was slightly smaller, compared with that of the normal children. 4) According to X-ray cephalometric analysis, the growth of the mandible was insufficient. 5) An enlargement of the angles of the teeth axes of the upper and lower central incisors was found. 6) The growth of the basal arches of the maxilla and mandible were shown to be retarded in the anterior portion. 7) Measurement of the area of the tubella sella triangle, revealed the posterior parts to be large and almost standard in the mesofacial part, and small in the mandibulo-facial parts.

Child, Preschool↗