Protein-to-wet weight relationships in supragingival plaques from caries-prone tooth surfaces.

The ratio of protein to wet weight in unpooled samples of supragingival plaques from sound and carious tooth surfaces was studied. Protein was assayed by a procedure developed for the study, in order to achieve a sensitivity of 1 microgram with minimum effects upon quantitation from protein composition and nonprotein components. Ratios of protein to wet weight in plaque specimens from caries-free surfaces were almost equally distributed into two main categories of 9.4% and 6.5%. Corresponding values for specimens from carious surfaces were 9.1% and 5.0%. The occurrence of high and of low values among samples from each type of surface indicated that the plaques differed quantitatively in protein, water, or a nonprotein component, possibly extracellular polysaccharide. Although compositional differences between plaques from the two types of surfaces were indicated by the lower ratios of 6.5% from noncarious and 5.0% from carious surfaces, they were not indicated by the higher ratio values, which were similar. These results suggest either that protein-to-wet weight ratios are not related to caries, or that the ratio values are related to caries for some but not all types of plaques.     

Dental caries in a Portuguese identified skeletal sample from the late 19th and early 20th centuries

Dental caries was investigated in 600 adult dentitions belonging to the identified osteological collections of the Museum of Anthropology, University of Coimbra, Portugal (late 19th/early 20th centuries). The main advantage of this sample compared to an archaeological source is the presence of known demographic parameters such as age, sex, and occupation. The aim of this study is to investigate the issues involved in comparing caries data derived from archaeological death assemblages with statistics compiled from clinical studies of the living. When only the upper dentition was considered, higher rates were observed in females than in males. No differences were found between sexes for lower teeth. In both sexes, both the percentage of carious teeth and the severity of lesions were found to increase with age, demonstrating that caries activity continued throughout life. The slight decrease observed for the age group 70–79 years is probably due to the increased antemortem tooth loss in the elderly. Caries was most common at contact areas (32.9%) and rarest at smooth crown surfaces (6.5%). Root surface caries was graphed in relation to the exposure of roots, and it was confirmed that the degree of root exposure was not strongly related to the frequency of carious lesions on the exposed root surface, although both increased with age. Molars were attacked more frequently by caries as a whole than premolars, canines or incisors. The results are similar to studies of recent living populations with a limited access to professional dental care. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.     

Endogenous opioids modulate fetal rabbit lung maturation

To test the hypothesis that endogenous opioids modulate fetal lung development, separate groups of pregnant rabbits received daily injections of saline, morphine (1 mg/kg body wt), or the opioid antagonist naloxone (0.4 and 5.0 mg) for 10 days during their last trimester of pregnancy. The corresponding groups of fetuses were then delivered prematurely on day 28 of gestation (term approximately 31 days) and evaluated with respect to differences in body weight, lung weight, and the ratios of wet to dry lung weight and lung dry weight to body weight, the static inflation and deflation air and saline pressure-volume (P-V) characteristics of the lungs, and lung morphology. Mean values for body weight, lung weight, and the ratios of lung wet to dry weight and lung dry weight to body weight were not significantly different among the saline control (C), morphine (M)-, and naloxone (NLX)-treated fetuses. On the other hand, the fetal air P-V curves varied significantly (P less than 0.001), wherein the M-treated group depicted increased lung distensibility and alveolar stability on lung deflation, whereas the opposite was obtained in the NLX-treated fetuses. Moreover, morphometric analyses demonstrated that the mean alveolar air space-to-tissue ratio in lungs from M-treated fetuses were significantly greater than that observed either in C or in NLX-treated fetuses (P less than 0.05); however, the air space-to-tissue ratio did not significantly vary between the C and NLX-treated animals. These observations provide new evidence that endogenous opioids enhance fetal lung maturation.     

The effectiveness of 10% chlorhexidine varnish treatment on dental caries incidence in adults with dry mouth

Objectives: This study compared a 10% chlorhexidine varnish treatment with placebo and sham treatments for preventing dental caries in adult patients with xerostomia (dry mouth). Design: The study was a multicentred, randomized, parallel group, double blind, placebo‐controlled clinical trial. Setting: All examinations and procedures were performed at Tuft's University, Boston, MA, the University of British Columbia, Vancouver, BC or the University of Western Ontario, London, ON. Subjects: Subjects were adults with recent or current dental caries experience, high salivary levels of cariogenic microorganisms and low salivary flow rates. Results: 236 subjects completed at least one post‐treatment examination. There were 697 new carious lesions diagnosed, 446 (64%) located on coronal surfaces and 251 (36%) located on root surfaces. The mean attack rate was 0.23 surfaces/100 surfaces at risk. A treatment difference observed between the Active and Placebo groups was statistically significant for root caries increment (p=.02) and total caries increment (p=.03). A treatment difference observed between the Active and Sham groups was not statistically significant for coronal, root or total caries increment. Analysis of variance of treatment group differences was performed using mutans streptococci counts, salivary flow rates, age, sex, caries prevalence, medications, time to first event and early withdrawal as co‐variables. These factors did not meaningfully alter the findings. Conclusions: The difference between the 10% chlorhexidine varnish and placebo treatments is considered to be highly clinically significant for root caries increment (41% reduction) and for total caries increment (25% reduction) but only for coronal caries increment (14%).     

Ten-year cross-sectional and incidence study of coronal and root caries and some related factors in elderly Swedish individuals

Objective: The 10‐year incidence of dental caries was related to some associated factors in a random sample of 65, 75 and 85‐year‐old inhabitants of Gothenburg. Subjects: Of the 208 persons examined at baseline, 102 (49%) participated in the follow‐up examination; 56, 37 and nine, respectively, in the different age groups. For the purpose of time‐trend comparisons, a new random sample of 98 individuals aged 55 years was examined. Results: Ninety‐five per cent of the participants had developed one or more carious lesions during the 10‐year period and the incidence of coronal and root caries increased with age. In the 65‐year‐olds, 9% of the root surfaces had decayed during the period, compared with 25% in the 85‐year‐olds. Secondary caries predominated over primary caries and prosthetic crowns accounted for 70% of the restored tooth surfaces. Twenty per cent of the individuals were daily smokers and 61% were taking drugs with hyposalivatory side‐effects. The mean saliva secretion rates were lower in the older groups compared with the ‘younger’ ones. The overall salivary counts of mutans streptococci and lactobacilli had increased during the period and the values were highest in the oldest age groups. Salivary levels of lactobacilli and mutans streptococci, number of teeth, daily numbers of cigarettes and drugs and oral hygiene were the best predictors of the incidence of caries. Conclusion: The findings indicate that there is an increased risk of dental caries with age owing to unfavourable caries‐related factors.     

Brief communication: A pilot study: Smooth surface early caries (caries incipiens) detection with kavo diagnodent in historical material

In many odontological studies concerning archeological material, there is no analysis of early caries lesions (caries incipiens) that manifest as a carious spot. At this stage of caries, the enamel is still hard, and thus, it is impossible to diagnose caries by visual methods. We assessed the usefulness of the DIAGNODent pen (DD laser) in analyzing noncavity lesions on the smooth surface sites of crowns from historical populations. Twenty‐seven individuals were examined: 18 from Radom (Poland), and nine from Tell Masaikh and Terqa (Syria). A total of 562 teeth were characterized. The series represented different climatic zones, but were dated from the similar period, 18th to 19th century AD. We used four diagnostic techniques: visual, DD laser, radiographic, and histological as the gold standard. DD laser showed that the mean values of healthy enamel in both series did not exceed 15 units. The mean values of smooth and rough spots in the Syrian population were significantly higher than those from Poland. This study showed that all the noncarious spots from the Radom series did not exceed 30 units. In the Syrian samples, this limit was higher at 44 units. These results were confirmed by histology and radiography. The DD laser provided good results in detecting dentine carious lesions in historical material, but its efficiency in diagnosing early caries (caries incipiens) remains uncertain based on the presented series. Am J Phys Anthropol, 2013. © 2013 Wiley Periodicals, Inc.     

Spectral characteristics of caries autofluorescence obtained from different locations and caries severities

Dental caries usually occurs at interproximal and occlusal surfaces. The purpose of the present study was to determine if characteristic spectral factors extracted from autofluorescence (AF) spectra are informative regarding caries detection and the determination of caries stage as compared with DIAGNOdent results. AF spectra were obtained from caries lesions of different severities at two locations using a 405 nm laser. Three spectral factors, that is, spectral slope at 550 to 600 nm, spectral area under the curve at 500 to 590 nm and two‐peak ratio between 625 and 667 nm, were extracted. The values of three spectral factors linearly decreased as caries progressed. According to micro‐CT images, conventional visual and tactile inspections of lesions under or overestimated (25%‐65%) caries states, and brown or thickly stained layer on interproximal or occlusal surfaces, respectively, caused misclassifications of caries stage. Of the spectral factors examined, spectral slope and area under curve for interproximal and occlusal surfaces, respectively, were found to be significantly related to caries stage and showed least data overlap. For interproximal and occlusal surfaces, DIAGNOdent readings of different stages overlapped considerably though their mean values were significantly different regardless of stage.      

Aluminum concentrations in human deciduous enamel and dentin related to dental caries

The aluminum (Al) concentrations in the enamel and dentin of 314 human deciduous teeth were determined in order to examine the relationship between Al and dental caries. The sample teeth were divided into three groups: the sound tooth group, carious tooth group and filled tooth group. The teeth of the carious tooth group were further classified into three groups depending on the stage of caries. The Al content was determined using graphite furnace atomic absorption spectrometry. In both the enamel and dentin, the Al concentrations were unaffected by sex, but did depend on tooth type. In enamel, the Al concentration was significantly higher in the sound tooth group (42.8 +/- 37.3 microg/g) than in the three carious groups (20.7 +/- 17.1-24.9 +/- 22.0 microg/g) and the filled tooth group (27.3 +/- 25.5 microg/g). As for dentin, the Al concentration was also significantly higher in the sound tooth group (36.2 +/- 35.1 microg/g) than in the three carious groups (15.1 +/- 13.3-24.5 +/- 23.4 microg/g) and the filled tooth group (17.2 +/- 20.6 microg/g). Even when analyzing incisors alone, the Al concentrations were significantly higher in the sound tooth group than in the other groups, for both enamel and dentin. Furthermore, the Al levels in carious enamel and dentin did not decrease with the advance of caries. These findings indicated that the deciduous teeth containing higher Al concentrations on average had less caries than the teeth with lower Al concentrations, and suggest that Al acts as a possible cariostatic agent by itself.     

儿童口腔内变形链球菌、乳酸杆菌的检出情况分析

调查评估年龄<12岁儿童口腔内变形链球菌及乳酸杆菌的检出情况及其与龋病的相关性。100例纳入实验的受试者根据不同龋敏感程度分为无龋组(DMFS=0)50人,高龋组(DMFS≥6)50人,按照不同龋敏感度、不同部位采集样本,用乳酸杆菌选择性培养基Rogosa和变形链球菌选择性培养基MSB,将乳酸杆菌和变形链球菌分离,经形态学及生化鉴定。统计2种细菌在不同分组中的检出率及不同致龋菌病例数,研究二者的致龋相关性。乳酸杆菌在100例研究对象中乳酸杆菌在龋坏深层检出率最高76%与光滑面(40%)、窝沟(48%)及唾液(40%)检出率比较有统计学意义(P<0.05),而龋坏深层变形链球菌检出率46%与光滑面(84%)、窝沟(68%)及唾液(78%)检出率比较最低(P<0.05);高龋人群变形链球菌检出率88%,乳酸杆菌检出率为76%均较无龋组相应细菌检出率26%、28%差异有统计学意义(P<0.05)。变形链球菌和乳酸杆菌随着龋敏感度的增加,乳酸杆菌和变形链球菌检出率增高;在龋坏深层更适于乳酸杆菌生长,且其对变形链球菌有一定的抑制作用。     

Observations of dental diseases among prehistoric populations of Hungary

The incidence of dental disease among people in developing countries today raises questions about the variation in the oral health of prehistoric populations. Considering these questions, we offer observations describing several types of dental disease which occurred among certain prehistoric populations of Hungary. The dental remains of 162 individuals recovered from seven sites of the Neolithic, Copper, and Bronze Age periods were examined for evidence of caries, hypoplasia, and periodontal disease. Appropriate methods were used to describe and record these dental lesions. The incidence of dental caries was low by comparison to other prehistoric agriculturists except for two forms of root caries: cervical and cemental. These types accounted for 68% of all the carious teeth recorded. Enamel hypoplasia was also lower than expected, occurring on only 4% of the total number of teeth. Periodontal abscesses were rare but other milder forms of periodontal lesions were frequent. Alveolar bone resorption occurred in varying degrees and followed the expected age distribution. The few exceptions were children or adolescents whose crania had other lesions suggesting a mineral metabolic disturbance. The lower incidence of enamel caries is likely due to high fluoride ingestion which also may have influenced the expression of enamel hypoplasia. No clear population trends were seen in dental disease incidence except for cemental caries which were found among Copper and Bronze Age remains.     

Candida albicans promotes tooth decay by inducing oral microbial dysbiosis

Candida albicans has been detected in root carious lesions. The current study aimed to explore the action of this fungal species on the microbial ecology and the pathogenesis of root caries. Here, by analyzing C. albicans in supragingival dental plaque collected from root carious lesions and sound root surfaces of root-caries subjects as well as caries-free individuals, we observed significantly increased colonization of C. albicans in root carious lesions. Further in vitro and animal studies showed that C. albicans colonization increased the cariogenicity of oral biofilm by altering its microbial ecology, leading to a polymicrobial biofilm with enhanced acidogenicity, and consequently exacerbated tooth demineralization and carious lesion severity. More importantly, we demonstrated that the cariogenicity-promoting activity of C. albicans was dependent on PHR2. Deletion of PHR2 restored microbial equilibrium and led to a less cariogenic biofilm as demonstrated by in vitro artificial caries model or in vivo root-caries rat model. Our data indicate the critical role of C. albicans infection in the occurrence of root caries. PHR2 is the major factor that determines the ecological impact and caries-promoting activity of C. albicans in a mixed microbial consortium.Subject terms: Biofilms, Bacteria, Fungi     

Rehardening of caries-like lesions in root surfaces by saliva substitutes

Objective: This study sought to evaluate whether root dentine caries‐like lesions could be remineralised by saliva substitutes. Methods: Root dentine slabs (3 × 3 × 2 mm) were cut from bovine incisors, ground flat, polished and pre‐tested for Knoop microhardness (KHN) at five locations spaced 500 μm apart and 500 μm from the left edge of each sectioned piece. After 60 out of the 100 slabs had been selected based upon their KHN values, specimens were coated with wax except for their outer surface. Specimens were then cycled through a highly cariogenic challenge model to induce caries‐like lesions, whose formation was confirmed by KHN measurements located 500 μm from the right edge of the specimen. According to a randomised complete block design, the experimental units (n = 15) were exposed to 1.5 ml of saliva substitutes, based on either mucin (MC) or carboxymethylcellulose (CM), to natural human saliva (HS) or to 100% relative humidity (RH) over 20 days. Remineralisation was verified by KHN measurements located 1000 μm apart from the right edge of the specimen. Results: Analysis of variance indicated a significant (p < 0.0001) difference among the KHN values attained by the carious root dentine after exposure to the remineralising agents. Tukey's test ascertained that remineralisation was greatest with MC, intermediate with CM and least with HS, but rehardening did not reach the pre‐caries lesion formation values. Conclusion: Saliva substitutes may provide partial remineralisation to preformed caries‐like lesions in root dentine.     

Analysis of 35 Inorganic Elements in Teeth in Relation to Caries Formation

As caries is a most common affliction of teeth, which are predominantly composed of inorganic elements, it was considered worthwhile to determine their elemental composition and to find if it bears any relation to caries formation. For this purpose, 35 inorganic elements were determined in 15 non-carious and an equal number of carious whole teeth after their dissolution in nitric acid. The results showed that out of 35 elements, strontium was the only element found to be present in significantly lower amount in carious teeth, thus strongly suggesting that its deficiency may help form caries. The decrease in Ca, Mg, Ti, P, Li, Be, V, Ni, Zn, Nb, Ag, Cd, Sb, Ba, La , W, Pb, and Bi and slight increase in K, Cr, Cu, and As was not statistically significant. However, statistically significantly greater amount of boron, manganese, molybdenum, and fluorine in the carious teeth indicates towards their possible role in predisposing or causing dental caries.     

Relationship of functional residual capacity to various body measurements in normal sheep.

Functional residual capacity (FRC) was determined by nitrogen washout in 55 normal sheep. Data on various external body measurements were collected which included body weight, chest circumference, chest width, body length, height, and sternum length. In addition, data on wet lung weight and wet lung weight/body weight ratio were collected on 10 of the sheep. A significant correlation was found between FRC and all measured parameters except height and sternum length. Multiple linear regression of all external body measurements showed the best correlation of FRC to body weight and body length, while the addition of chest circumference and/or chest width did not significantly improve the correlation. Significant deviation from the population was noted in three sheep (5.5%) that had lung weight/body weight ratios which were significantly lower than the rest of the population.     

Chemische Zusammensetzung und Biomasseparameter der OhrenqualleAurelia aurita

During summer 1982 and 1983, measurements on the chemical composition and biomass parameters ofAurelia aurita from Kiel Fjord, Western Baltic, were made. The relationships between size vs. wet weight and wet weight vs. carbon content were determined. Dry weight accounted for less than 2% of wet weight in both years. Carbon, nitrogen and phosphorus content of whole medusae were 51–52, 14 and 1.4 mg/g dry weight (dw) respectively. The C:N ratio (by weight) was about 3.7 and the C:N:P-ratio (by atoms) was determined to be 94:22:1. Proteins and carbohydrates made up 59 and 29 mg/g dw. Lipids were estimated to be 19 mg/g dw. Using these data, it was possible to calculate the caloric content of the medusae to be about 0.55 cal/mg dw. In summer 1982, the organic content of different tissues (gonad, oral arm, umbrella) in unfertilized and fertilized females was studied. In unfertilized females, the gonads exhibited the highest values, the umbrella had the lowest values and the values of oral arm tissue were intermediate. However, in fertilized females the oral arm tissue was enriched, whereas the gonads were impoverished; both types of tissues exhibited very similar values. This pattern can be explained by the transfer of fertilized eggs from the gonads into the brood pouches of the oral arms.     

High Resolution Proton NMR Spectroscopy of Multiple Sclerosis Lesions

Abstract: Tissue from postmortem multiple sclerosis and normal control brains was extracted with perchloric acid and analysed using proton NMR spectroscopy. The content of N -acetyl-derived groups (the sum of N -acetylaspartate, acetate, and N -acetylaspartylglutamate) was decreased in multiple sclerosis plaques compared with normal control white matter (mean, 4.36 vs. 6.64 µmol/g wet weight). In normal appearing white matter adjacent to plaques a corresponding decrease was seen, with no change in white matter distant from plaques. A decrease in the content of total creatine was observed in multiple sclerosis plaques in comparison with normal control white matter (mean, 4.64 vs. 6.56 µmol/g wet weight), which correlated strongly with the decrease in N -acetyl-derived groups. No changes in other metabolites such as total choline or myo -inositol were seen. The decreases in content of N -acetyl-derived groups are in agreement with observations from in vivo proton NMR spectroscopy in multiple sclerosis patients. The decrease in total creatine is in contrast to most of the observations made in vivo where total creatine is assumed to be unchanged and metabolite levels are often expressed as a total creatine ratio. The use of a total creatine ratio in vivo could lead to an underestimation of reductions in N -acetylaspartate and an apparent increase in other metabolites in the multiple sclerosis lesion.     

Daily ration of adult perch, Perca fluviatilis L. during summer in Loch Leven, Scotland

Adult perch, Perca fluviatilis L., were sampled at 3-hourly intervals throughout 24-h periods from June-September 1971, and in June and August 1972. The wet weight of each major food component from the stomachs was expressed in parts per 10 000 of the fresh weight of the fish. From samples at capture, and others taken from caged fish at known time-intervals after capture, the rate of stomach evacuation was estimated. Food consumption between netting times was calculated as the increment between successive initial values of stomach contents, plus the amount evacuated in the interval. As the evacuation rate of caged fish was slower than that of free fish the estimates of food turnover are minimal ones. The perch were consuming 6.5 % of their wet body weight per day in June, and this ration had decreased to 3.2% by September.     

Effects of hypoxia or hyperoxia on the lung of the chick embryo

Newborn mammals in chronic hypoxia or hyperoxia experience, respectively, an increase or decrease in lung weight:body weight ratios, possibly because of the mechanical effect on the lung accompanying the ventilatory response. Because the avian lung does not expand or contract with the breathing cycle, we asked whether or not qualitatively similar changes could be observed in the lung of chick embryos incubated in hypoxic or hyperoxic conditions. Hypoxic embryos (10% O2, days 14-18) were smaller than controls incubated in normoxia, with higher hematocrit values and larger lung weight:body weight ratios (both wet and dry). Both the total pulmonary DNA (reflecting the cellular component) and the DNA concentration were decreased in hypoxia. Hyperoxic embryos (50% O2, days 7-18 or days 14-18) had lower hematocrit values and smaller dry lung weight:body weight ratios than controls, with similar DNA concentrations. In general, the differences from controls were more apparent in those embryos hyperoxic from day 14 to 18 of incubation than from day 7 to 18. We conclude that changes in lung weights qualitatively similar to those occurring in the chronically hypoxic or hyperoxic newborn mammal can also be observed in the hypoxic or hyperoxic chick embryo, suggesting that they are not necessarily caused by changes in mechanical stretch on the lung.     

Carbon monoxide-dependent chemolithotrophic growth of Clostridium thermoautotrophicum.

The acetogen Clostridium thermoautotrophicum was cultivated under CO-dependent chemolithotrophic conditions. CO-dependent growth profiles and energetics indicated that supplemental CO2 was fundamental to efficient growth at the expense of CO. Overall product stoichiometry approximated 6.5CO----CH3CO2H + 3.5CO2 + 0.6 cell C + 0.5 unrecovered C. Initial CO/CO2 ratios of 2 to 4 yielded optimal doubling times and cell yields. Maximal YCO values approximated 2.5 g of cell dry weight per mol of CO consumed; YH2 was considerably lower than YCO. Cross-transfer growth experiments and protein profiles indicated differential expression of genes between CO and methanol cultures.     

Digestion of native collagen, denatured collagen, and collagen fragments by extracts of rat liver lysosomes.

Extracts of highly purified lysosomes from rat liver were examined for their ability to degrade native collagen and thermally denatured collagen at pH values between 3.5 and 7.0. After a 24-h digestion at 36 degrees with the lysosomal extract at a pH of 5.5 or lower (collagen/lysosomal protein; 2/1 or 8/1), both native and denatured collagen were degraded to an extent equivalent to 60 to 70% of that observed upon total acid hydrolysis in 6 N HCl as measured by the ninhydrin reaction (570 nm). At a pH of 6.0, native collagen and denatured collagen were degraded by the mixture of lysosomal proteinases to 11% and 40% of total acid hydrolysis, respectively. At pH 6.5 AND 7.0, the corresponding values were 3% versus 33% and 0.3% versus 11%, respectively. Fragments of collagen (TCA and TCB) are produced when mammalian collagenase degrades native collagen at 25 degrees. These fragments were degraded by the lysosomal extract at 36 degrees to an extent equivalent to 28% and 8% of total acid hydrolysis at pH 6.5 and 7.0, respectively. The experiments at pH 6.5 and 7.0 were done using a collagen/lysosomal protein ratio of 2/1. At pH 5.0 (a pH which is found within secondary lysosomes), the lysosomal extracts degraded collagen to a mixture of free amino acids and small peptides. Amino acid analysis established that approximately 30% of the amino acid residues of the collagen appeared in the lysosomal hydrolysate as free amino acids. Hydroxyproline and perhaps hydroxylysine were the only amino acids found in collagen which did not appear at least to some extent as the free amino acid in this hydrolysate.