湖北郧西黄龙洞更新世晚期人类牙齿

对2004—2006年在湖北省郧西县黄龙洞发现的7枚更新世晚期人类牙齿进行了观测与分析, 在此基础上与相关的化石人类及近代现代人类标本进行了对比。本研究发现:黄龙洞人类牙齿总体特征与现代人接近, 同时也保留部分可能属于更新世晚期人类的特点, 包括前部牙齿(侧门齿与犬齿)尺寸及粗壮程度都明显大于现代人。黄龙洞人类牙齿呈现的铲形门齿、双铲形门齿及臼齿釉质延伸说明,当时人类已经具有了东亚人群的典型牙齿形态特征。     

Number of teeth and risk of root caries

Objective: This study aimed to investigate the association between number of natural teeth and prevalence of root caries. Design: A cross‐sectional design was adopted. A stratified multi‐stage purposive sampling method was used to select a wide range of elderly people from all social classes, educational levels and sexes. Data was collected through interviews and clinical examinations. Setting: Urban area in Chiang Mai‐Thailand. Participants: 549 elderly dentate aged 60‐74 years. Main Outcome Measures: Teeth with decay and filled roots (DF‐T). Results: The prevalence of root caries was 18.2% with a mean DF‐T of 0.58 (S.D. 2.02). Results of multiple logistic regression showed that number of teeth, DMF‐S scores, sex, and socio economic factors were statistically significantly associated with root caries (P<0.05). Adjusted odds ratios demonstrated a 14% increase in the chance of having root caries when the number of teeth increased one unit. Similarly, a 3% increase was observed for each unit increase in the DMF‐S scores (p<0.001). Being male, having more than four years of education and earning more than 1500 baht/month increased the chances of root caries by 76%, 139% and 85% respectively (p<0.001). Recession and age were not statistically significantly associated with root caries. Conclusions: Having more teeth, higher DMF‐S scores, earning more than 1500 baht/month, having more than 4 years of education and being male increased the likelihood of having root caries.     

硅藻鼠科(哺乳纲,啮齿目)与亚洲中始新世啮齿类的双脊齿(英文)

亚洲特有的啮齿类硅藻鼠科自渐新世以来分布于东亚和南亚。现生硅藻鼠类的分布只限于老挝的喀斯特地区。就目前所知,这些具有豪猪型头骨-松鼠型下颌的啮齿类的颊齿都是不同程度的横向双脊齿。时代最早的硅藻鼠类产于巴基斯坦渐新世地层中,其颊齿的双脊齿构造上仍保留齿尖残迹,基本符合双脊齿型牙齿结构。至渐新世末期,硅藻鼠科的牙齿出现分化。中新世及以后硅藻鼠类的化石记录相对较少。分子生物学证据将硅藻鼠类归入Ctenohystrica,这种归属也从始新世梳趾鼠类的臼齿形态上得到一定的支持。除此之外,有关硅藻鼠类的起源问题几乎一无所知。亚洲中始新世的Hydentomys臼齿表现出轻微的双脊型,然而其他方面却与硅藻鼠类不同。另一个具双脊齿的啮齿类Dolosimus(新属)产于江苏中始新世,其具有更为发育的双脊齿,特别是臼齿型下牙。新属的不完整记录及其形态不能解决如下问题:它是否与后来出现的像硅藻鼠类和跃兔类这些具有明显双脊齿型颊齿的啮齿类有亲缘关系,或者只是这种形态发育中没有留下后继者的早期试验品。     

A new therian mammal from the Rhaetic locality of Saint-Nicolas-de-Port (France)

In this paper a new taxon of Kuehneotheriidae is described and diagnosed, mainly by comparison with the genus Kuehneotherium . By its greater age and its more primitive evolutionary state, Woutersia mirabilis gen. et sp. nov. is a particularly interesting element of the fauna and enlarges the concept of the Kuehneotheriidae.
Dans cet article est dAecrit et défini un nouveau taxon de Kuehneotheriidés, Woutersia mirabilis gen. et sp. nov., par comparaison avec Kuehneotherium . Son âge plus ancien et son stade évolution considéré comme plus primitif en font un élément particuliérement intéressant, qui élargit en outre le concept des Kuehneotheriidés.     

Relationship between age and deposit of peritubular dentine

Peritubular dentine is a mineralised deposit formed centripetally in the dentine tubules with advancing age, so that the tubular diameter is smaller in teeth from older persons. The aim of the present study was to investigate the relationship between age in humans and the amount of peritubular dentine and the extent of the consequent obliteration of the tubules, and to find out whether this relationship was strong enough to be used as a parameter for age estimation. Fifty mandibular central and lateral human incisors were ground on the lingual aspect of the root and examined in a scanning electron microscope (SEM). The number of open tubules was counted and the diameter of the tubules measured both before and after etching with 35% orthophosphoric acid. The difference in the number of tubules in unetched and etched specimens was taken to be the number of occluded tubules, and the difference in radii before and after etching to be the thickness of peritubular dentine. The results did not demonstrate a significant relationship between age and the reduction in the number of tubules. One explanation might be that a certain age has to be reached before obliterated dentine tubules can be observed. The correlation between age and the thickness of peritubular dentine was not significant in teeth extracted because of periodontal disease, so these teeth were excluded from the regression analysis with age as the dependent variable. Only the thickness of peritubular dentine was included in the regression (r=0.69); this factor was a better indicator of age than the tubular diameter, but not so closely related to age that it can be recommended for general use in forensic and archaeological age estimations.     

Puncture-Resistance of Gloves for Handling Bats

ABSTRACT We quantified protection given by a variety of gloves against bat bites by using steel indenters to simulate teeth and measuring forces needed to puncture the gloves. Level of protection given by gloves was compared to expected bite forces and tooth sharpness of bats. Cotton, plastic-coated synthetic fabric, and proprietary materials advertised as puncture- and cut-resistant were easy to penetrate compared to leather gloves. Split leather gives the highest level of protection, but with reduced dexterity. These are best for handling larger bats (>40 g) or if higher safety is preferred. Deerskin gives reasonable protection without much loss in dexterity for handling bats <40 g.     

Intrastriatal transplantation of stem cells from human exfoliated deciduous teeth reduces motor defects in Parkinsonian rats

Background

This study explored the neural differentiation and therapeutic effects of stem cells from human exfoliated deciduous teeth (SHED) in a rat model of Parkinson's disease (PD).