[Root canal anatomy of maxillary second premolars at various ages observed by cone-beam CT].

Objective: To observe the morphological changes of root canals in maxillary second premolars at various ages by using cone-beam CT (CBCT) in order to provide imaging and theoretical reference for clinical treatments. Methods: The digital CBCT data of the maxillary second premolars in 440 cases from the patients in Department of Stomatology, The First Affiliated Hospital, Jinan University during March 2011 and December 2017 were collected. The CBCT images were divided into 4 groups according to the patients' ages: groups ≤20, 21-40, 41-60 and>60 years old, respectively. Changes of morphologies of root canals with aging including such parameters as types of the root canal, incidence of double root canals in single rooted teeth, distance between both root canal orifices of double rooted canals, and morphological change of the cross section of roots. Chi-square test and liner trend test were adopted in statistical analysis in the present study. Results: Most maxillary second premolars had only one root [95.2% (419/440)]. Type Ⅰ of the root canals was the most common type [57.3% (252/440)], and the following prevalent groups were type Ⅱ[16.8% (74/440)], type Ⅳ [10.2% (45/440)] and type Ⅲ [8.9% (39/440)]. The distribution of type Ⅰ~Ⅳ of the root canals were significantly different amongst various aged groups (P<0.05). Along with aging, the percentages of type Ⅰ decreased while type Ⅱ increased. However, there were no remarkable changes of type Ⅲ and type Ⅳ observed. The incidence of double canal in single rooted teeth gradually increased with aging especially in 20-year-old and above groups, e.g. 13.1% (13/99) in group of ≤20 years old and 45.0% (86/191) in group of 21-40 years old. However, there was no significant increase observed after the age of 40. The distance between two root canal orifices of double rooted canals became shorter with aging except in groups of 40-year-old and above. The morphologies of the cross sections of root canals in most groups were flat shaped [57.8% (1 121/1 938)] and oval shape [31.3% (607/1 938)]. Along with aging, the percentage of circular shape gradually increased while flat and oval shapes decreased. Conclusions: The morphology of root canal could be clearly showed by the CBCT images. Most maxillary second premolars had only one root and one apical foramen. Along with aging, the morphology of the root canals became more and more complicated.

Root canal anatomy of maxillary second premolars at various ages observed by cone-beam CT / 中华口腔医学杂志

Objective@#To observe the morphological changes of root canals in maxillary second premolars at various ages by using cone-beam CT (CBCT) in order to provide imaging and theoretical reference for clinical treatments.@*Methods@#The digital CBCT data of the maxillary second premolars in 440 cases from the patients in Department of Stomatology, The First Affiliated Hospital, Jinan University during March 2011 and December 2017 were collected. The CBCT images were divided into 4 groups according to the patients′ ages: groups ≤20, 21-40, 41-60 and>60 years old, respectively. Changes of morphologies of root canals with aging including such parameters as types of the root canal, incidence of double root canals in single rooted teeth, distance between both root canal orifices of double rooted canals, and morphological change of the cross section of roots. Chi-square test and liner trend test were adopted in statistical analysis in the present study.@*Results@#Most maxillary second premolars had only one root [95.2% (419/440)]. Type Ⅰ of the root canals was the most common type [57.3% (252/440)], and the following prevalent groups were type Ⅱ[16.8% (74/440)], type Ⅳ [10.2% (45/440)] and type Ⅲ [8.9% (39/440)]. The distribution of type Ⅰ~Ⅳ of the root canals were significantly different amongst various aged groups (P<0.05). Along with aging, the percentages of type Ⅰ decreased while type Ⅱ increased. However, there were no remarkable changes of type Ⅲ and type Ⅳ observed. The incidence of double canal in single rooted teeth gradually increased with aging especially in 20-year-old and above groups, e.g. 13.1% (13/99) in group of ≤20 years old and 45.0% (86/191) in group of 21-40 years old. However, there was no significant increase observed after the age of 40. The distance between two root canal orifices of double rooted canals became shorter with aging except in groups of 40-year-old and above. The morphologies of the cross sections of root canals in most groups were flat shaped [57.8% (1 121/1 938)] and oval shape [31.3% (607/1 938)]. Along with aging, the percentage of circular shape gradually increased while flat and oval shapes decreased.@*Conclusions@#The morphology of root canal could be clearly showed by the CBCT images. Most maxillary second premolars had only one root and one apical foramen. Along with aging, the morphology of the root canals became more and more complicated.

Lens internal curvature effects on age-related eye model and lens paradox.

The gradient index (GRIN) model is the most accurate way to represent the eye lens which, because of its growth mode, is a lamellar, shell-like structure. The GRIN is thought to provide optical properties that counteract age-related changes in curvature that would otherwise create an increasingly myopic eye: the so-called lens paradox. This article investigates how fine-tuning the refractive index and the internal curvatures of the lenticular indicial contours may prevent the ageing eye from becoming myopic. A system matrix approach is applied for analysis of a shell model with 200 shells to obtain the paraxial characteristics of the eye model.

Crystalline lens paradoxes revisited: significance of age-related restructuring of the GRIN.

The accommodating volume-constant age-dependent optical (AVOCADO) model of the crystalline lens is used to explore the age-related changes in ocular power and spherical aberration. The additional parameter m in the GRIN lens model allows decoupling of the axial and radial GRIN profiles, and is used to stabilise the age-related change in ocular power. Data for age-related changes in ocular geometry and lens parameter P in the axial GRIN profile were taken from published experimental data. In our age-dependent eye model, the ocular refractive power shows behaviour similar to the previously unexplained "lens paradox". Furthermore, ocular spherical aberration agrees with the data average, in contrast to the proposed "spherical aberration paradox". The additional flexibility afforded by parameter m, which controls the ratio of the axial and radial GRIN profile exponents, has allowed us to study the restructuring of the lens GRIN medium with age, resulting in a new interpretation of the origin of the power and spherical aberration paradoxes. Our findings also contradict the conceptual idea that the ageing eye is similar to the accommodating eye.

Accommodating volume-constant age-dependent optical (AVOCADO) model of the crystalline GRIN lens.

The purpose of this manuscript is to introduce a new age-dependent model of the human lens with two GRIN power distributions (axial and radial) that allow decoupling of its refractive power and axial optical path length. The aspect ratio of the lens core can be held constant under accommodation, as well as the lens volume by varying the asphericity of the lens external surfaces. The spherical aberration calculated by exact raytracing is shown to be in line with experimental data. The proposed model is compared to previous GRIN models from the literature, and it is concluded that the features of the new model will be useful for GRIN reconstruction in future experimental studies; in particular, studies of the accommodation-dependent properties of the ageing human eye. A proposed logarithmic model of the lens core enables decoupling of three fundamental optical characteristics of the lens, namely axial optical path length, optical power and third-order spherical aberration, without changing the external shape of the lens. Conversely, the near-surface GRIN structure conforms to the external shape of the lens, which is necessary for accommodation modelling.

OCT-based crystalline lens topography in accommodating eyes.

Custom Spectral Domain Optical Coherence Tomography (SD-OCT) provided with automatic quantification and distortion correction algorithms was used to measure anterior and posterior crystalline lens surface elevation in accommodating eyes and to evaluate relationships between anterior segment surfaces. Nine young eyes were measured at different accommodative demands. Anterior and posterior lens radii of curvature decreased at a rate of 0.78 ± 0.18 and 0.13 ± 0.07 mm/D, anterior chamber depth decreased at 0.04 ± 0.01 mm/D and lens thickness increased at 0.04 ± 0.01 mm/D with accommodation. Three-dimensional surface elevations were estimated by subtracting best fitting spheres. In the relaxed state, the spherical term accounted for most of the surface irregularity in the anterior lens (47%) and astigmatism (70%) in the posterior lens. However, in accommodated lenses astigmatism was the predominant surface irregularity (90%) in the anterior lens. The RMS of high-order irregularities of the posterior lens surface was statistically significantly higher than that of the anterior lens surface (x2.02, p<0.0001). There was significant negative correlation in vertical coma (Z3 (-1)) and oblique trefoil (Z3 (-3)) between lens surfaces. The astigmatic angle showed high degree of alignment between corneal surfaces, moderate between corneal and anterior lens surface (~27 deg), but differed by ~80 deg between the anterior and posterior lens surfaces (including relative anterior/posterior lens astigmatic angle shifts (10-20 deg).

Assessment of imaging with extended depth-of-field by means of the light sword lens in terms of visual acuity scale.

We present outcomes of an imaging experiment using the refractive light sword lens (LSL) as a contact lens in an optical system that serves as a simplified model of the presbyopic eye. The results show that the LSL produces significant improvements in visual acuity of the simplified presbyopic eye model over a wide range of defocus. Therefore, this element can be an interesting alternative for the multifocal contact and intraocular lenses currently used in ophthalmology. The second part of the article discusses possible modifications of the LSL profile in order to render it more suitable for fabrication and ophthalmological applications.

Genetics of aging, health, and survival: dynamic regulation of human longevity related traits.

BACKGROUND: The roles of genetic factors in human longevity would be better understood if one can use more efficient methods in genetic analyses and investigate pleiotropic effects of genetic variants on aging and health related traits. DATA AND METHODS: We used EMMAX software with modified correction for population stratification to perform genome wide association studies (GWAS) of female lifespan from the original FHS cohort. The male data from the original FHS cohort and male and female data combined from the offspring FHS cohort were used to confirm findings. We evaluated pleiotropic effects of selected genetic variants as well as gene-smoking interactions on health and aging related traits. Then we reviewed current knowledge on functional properties of genes related to detected variants. RESULTS: The eight SNPs with genome-wide significant variants were negatively associated with lifespan in both males and females. After additional QC, two of these variants were selected for further analyses of their associations with major diseases (cancer and CHD) and physiological aging changes. Gene-smoking interactions contributed to these effects. Genes closest to detected variants appear to be involved in similar biological processes and health disorders, as those found in other studies of aging and longevity e.g., in cancer and neurodegeneration. CONCLUSIONS: The impact of genes on longevity may involve trade-off-like effects on different health traits. Genes that influence lifespan represent various molecular functions but may be involved in similar biological processes and health disorders, which could contribute to genetic heterogeneity of longevity and the lack of replication in genetic association studies.

Correlation of root and root canal diameter of maxillary central incisors with age in Chinese Han popula-tion / 实用口腔医学杂志

Objective:To investigate the correlation between root and root canal diameter of maxillary central incisors and age by cone-beam computed tomography(CBCT).Methods:CBCT images of 420 cases of Chinese Han population were divided into 7 age groups as follows:1 5 -24,25 -34,35 -44,45 -54,55 -64,65 -74 and 75 -84(n =60).Root diameter and root canal diameter of maxillary central incisors at the 3 /4 level from the cemenal-enamel junction(CEJ)to root apical were measured.Linear-regression a-nalysis was used to analyze the correlation between root and root canal diameter of the teeth and age,T-test was used to examine the gender difference.Results:Mean root diameter(mm)of the teeth in males and females were 5.81 ±0.445 and 5.53 ±0.489(P <0.05),mean root canal diameter(mm)1 .20 ±0.396 and 0.96 ±0.236(P <0.05),mean of the ratio of root canal diameter and root diameter of the teeth 0.21 ±0.072 and 0.1 7 ±0.043(P <0.05)respectively.There were negative correlations between the ratio of root canal diameter and root diameter of the teeth with age (R2 =0.576,P <0.05).Conclusion:The ratio of root canal diameter and root diameter of maxillary central incisors is negitively correlated with age in Chinese Han population.The decrease of root canal diame-ter in males is more significant than that in females.

The aging human cochlear nucleus: Changes in the glial fibrillary acidic protein, intracellular calcium regulatory proteins, GABA neurotransmitter and cholinergic receptor.

The human auditory system is highly susceptible to environmental and metabolic insults which further affect the biochemical and physiological milieu of the cells that may contribute to progressive, hearing loss with aging. The cochlear nucleus (CN) is populated by morphologically diverse types of neurons with discrete physiological and neurochemical properties. Between the dorsal and the ventral cochlear nucleus (DCN and VCN), the VCN is further sub-divided into the rostral (rVCN) and caudal (cVCN) sub-divisions. Although, information is available on the age related neurochemical changes in the mammalian CN similar reports on human CN is still sparse. The morphometry and semiquantitative analysis of intensity of expression of glial fibrillary acidic protein (GFAP), calcium binding proteins (calbindin, calretinin and parvalbumin), gamma amino butyric acid (GABA) and nicotinic acetyl choline receptor (nAchR) beta 2 immunostaining were carried out in all three sub-divisions of the human CN from birth to 90 years. There was increased GFAP immunoreactivity in decades 2 and 3 in comparison to decade 1 in the CN. But no change was observed in rVCN from decade 4 onwards, whereas intense staining was also observed in decades 5 and 6 in cVCN and DCN. All three calcium binding proteins were highly expressed in early to middle ages, whereas a significant reduction was found in later decades in the VCN. GABA and nAchR beta 2 expressions were unchanged throughout in all the decades. The middle age may represent a critical period of onset and progression of aging changes in the CN and these alterations may add to the deterioration of hearing responses in the old age.

[Trends in interregional migration in Estonia since 1947]. / L'evolution des migrations inter-regionales en Estonie depuis 1947.

Migration trends in Estonia since 1947 are reviewed. The analysis indicates that the country's age distribution began to change earlier than that of other Eastern European countries. "Immigration started earlier too, first with the influx from the Estonia hinterland into the capital, then, after the second world war, with the gradual common workforce influx from the Republics of the Soviet Union." The author concludes that in-migration, combined with greater migration among younger people, has resulted in increased demographic aging, a trend that has to be taken into account when developing social policy. (SUMMARY IN ENG AND SPA)

[Aging and state expenditures]. / Vieillissement et depenses de l'Etat.

PIP: The debate concerning the impact of demographic aging in developed countries is reviewed, with particular attention to the situation in Canada. The author first reviews the available data on which forecasts of future trends in demographic aging are based. He then summarizes results of studies on the effect of these trends on government costs in specific areas, such as health, and on overall government costs. He concludes that Canada's position in this regard is more favorable than that of developed countries as a whole.^ieng

Demographic aging in Romania.

PIP: Trends in demographic aging in Romania during the period 1930-1986 are discussed. Consideration is given to age and sex distribution, causes and characteristics of demographic aging, and projections and implications of the increase in the population over 60 years of age. Data are from official sources.^ieng

A country profile: the Soviet Union. The demographic situation and policy.

PIP: The author presents an overview of the demographic situation in the Soviet Union. The discussion includes trends in mortality, fertility, nuptiality, population growth, population characteristics, demographic aging, labor force, and internal migration. Data are from the 1987 UN/USSR Interregional Demographic Training and Research Program in Population and Development Planning. Consideration is also given to population policy that is currently being established and its possible demographic impact. (SUMMARY IN TUR)^ieng

Attitudes towards population trends and population policy in the Netherlands, compared with some data from other Western European countries.

PIP: In the netherlands fertility has been below replacement level for the last decade. The overall age specific fertility rate is at an all time low of about 1.5. The relatively young age structure of the population implies a continuing population growth for some time, but at present it is less than 0.4% per year. In the coming years the Netherlands will be confronted with a considerable demographically determined increase in the labor supply, a consequence of, compared to neighboring countries, an initially high birthrate. It is in light of this demographic transition situation that the results of the 1983 survey of the Dutch population aged 20-64 have to be considered. The representative sample of 952 people were interviewed about their knowledge and opinions concerning certain aspects of the population issue and about their attitudes with regard to demographically relevant government politics. The survey primarily investigated the acceptance (with regard to opinions and behavioral intentions) of population/family policies in relation to reproductive behavior. This discussion fcuses on prevalent attitudes with respect to fertility trends, future population growth and decline, aging, and more direct government involvement. For the sake of illustration some findings are compared to results from recent surveys conducted in Belgium, France, and the Federal Republic of German. Te majority of those interviewed had some knowledge of the decline in the number of births which has occurred since the 1960s. The drop in the number of births which actually occurred was considered positive by 47% of those interviewed and negative by 13%. Compared to the results of a survey held in 1980 in the Dutch speaking part of Belgium, the large pecentage (40%) of Dutch people w had no definite opinion is notable. In the belgian survey, the same question resulted in 54% of those questioned judging the decline as positive, 29% negative, with 17% having no opinion. A reduction in the size of the population as a consequence of birth trends was viewed as a positive development by 1/3 of the population and as a negative development by another 1/3. 82% of the respondents were acquainted either with the fact that in the next 15 years the number of popple aged over 65 will increase considerably. 49% viewed this trend as an outright problem, while 15% considered it in a positive light. There was a certain consistency between the attitudes with respect to aging and those with respect to the fertility decline. According to 40% of those included in th Survey, the government may (in the most extremity) take it upon itself to influence the size of the population. With regard to the matter of whether the government may have a hand in determining the number of births, the answers were more reserved. Only 19% agreed that the government can (if need be).^ieng

AGING CHANGES IN TYROSINE HYDROXYLASE IMMUNOREATIVE NEURONS IN THE LOCUS COERULEUS OF THE RAT / 西安交通大学学报(医学版)

Aging changes of tyrosine hydroxylase (TH) -immuno reactive neurons in the locus coeruleus were examined in young (3 month-old). adult(12 month-old) and aged(20 month-old) Wistar male rats, using the IGSS method and image quantitative analysis. The results obtained are as follows: ① The number of TH-immunoreactive neurons docreased markedly (P

A MORPHOMETRY ANALYSIS OF GALT AND ITS AGING ASSOCIATED CHANGES / 解剖学报

The amount of gastrointestinal associated lymphoid tissue (GALT) of 99 cases of autopsy died from various accidents has been examined by Videoplan. The results showed that the density of GALT in appendix (0.24mm~2/mm-length of GIT) is the maximum, the next is in ileum (0.0941/mm~2/mm). Since the total area of ileum is much more larger than that of appendix, it is suggested that ileum may possess the primarily important immunefunction in GIT.No statistical difference of aging associated changes of the amount of GALT could be identified in this study, however, a tendency of decline existed. The factors related with this result were discussed.

AGING CHANGES OF SOMATOSTATIN mRNA-POSITIVE NEURONS IN THE DORSAL HIPPOCAMPUS OF THE RAT / 解剖学报

Aging changes of somatostatin (SS) mRNA-positive neurons in the dorsal hippocampus of old rats were studied by in situ hybridization histochemistry and image analysis. In the young rats,SS mRNA-positive cell bodies were mainly located in the pyramidal and polymorphic cell layers of the CA1 and CA2 regions, and in the strata radiatum and polymorphic cell layer of the CA3 region, and in the polymorphic cell layer of dentate gyrus. In the old rats,SS mRNA-positive cell bodies were concentrated in the polymorphic cell layer and denate gyrus. A marked decrease of number of SS mRNA-positive cell bodies and a significant increase of gray value of SS mRNA-positive cell bodies were found in the dorsal hippocampus and dentate gyrus of the old rats as compared with the young rats. No significant age difference in the sectional area of SS mRNA-positive cell bodies was observed in the dorsal hippocampus. The results showed that there were apparent changes with aging of the SS mRNA-positive cell bodies in the dorsal hippocampus of the rats. The significance of the changes remains to be studied further.

AGING CHANGES OF NEUROTENSIN-LIKE AND GALANIN-LIKE NEURONS IN THE CENTRAL AMYGDALOID NUCLEUS OF THE RAT / 解剖学报

Aging changes of neurotensin-like (NT-L) and galanin-like (GAL-L) cell bodies and fiber terminals in the central amygdaloid nucleus between the young and old rats were studied by means of immunohistochemical and microspectrophotometric techniques. NT-L cell bodies were mainly located in the central part (CeLn) of, centrolateral amygdaloid nucleus, a few of NT-L neurons were also found in the centrolateral amygdaloid nucleus, capsular part (CeLc) and centromedial amygdaloid nucleus (CeM). NT-L fiber terminals were seen mainly in the CeLn and CeLc. GAL-L cell bodies were observed only in the CeM. A marked decrease of density of NT-L cell bodies and fiber terminals in the central amygdaloid nucleus was found in the old rats as compared with young animals. No significant age difference in number of GAL-L cell bodies was observed in the central amygdaloid nucleus, but the staining intensity of GAL-L cell bodies was reduced remarkably. The results show that there are apparent changes with aging of the NT-L and GAL-L neurons in the central amygdaloid nucleus of the rat. The significance of the changes remains to be studied further.