Cuspal Enamel Growth and Crown Enamel Thickness in Modern-Day African Pastoralists and Farmers

European and African populations have exhibited limited variation in dental development. However, it remains unclear whether tooth growth, specifically enamel formation, varies between modern human populations with differing diets. Enamel growth and thickness were compared between two modern human ethnic populations, the Fulbe and Nso, from Cameroon. There is a cultural focus on milk-drinking and consuming milk-based products in the Fulbe which is not present in the Nso, who have a broad-based modern diet including agricultural produce. This study aimed to determine whether enamel formation differed between these populations and, if so, whether these variations correlated with their diets. Standard histological methods were used to analyse cuspal enamel growth rates, average enamel thickness and tooth crown size in 35 permanent molars (Fulbe n= 9; Nso n= 26). Prism widths were measured using scanning electron microscopy. Cuspal enamel growth rates and average enamel thickness were also measured in a comparative European (British) sample. The speed at which tooth crowns extended in height was significantly (p= 0.005) faster in the Fulbe (n= 7, mean= 23.61µm/day) than the Nso (n= 7, mean= 14.41µm/day). Prism widths were also larger (Fulbe mean= 5.68µm; Nso mean= 5.24µm). The comparative European sample had accelerated extension rates (n= 20, mean= 28.39µm/day) which were more similar to the results for the Fulbe than the Nso. Tooth crown size was significantly (p< 0.005) larger in the Nso molars than the Fulbe molars. Crown enamel thickness was greater in the combined African (Fulbe and Nso) molars (mean= 1.49 mm) than the European molars (mean= 1.14 mm) from this study, as well as other comparative datasets from previous publications. No consistent differences were found between pre-weaning (first molars) and post-weaning (second and third molars) cuspal enamel growth rates in either the pastoralists or farmers. These results imply there is more variation in modern human tooth growth than previously reported. Further research into cuspal enamel growth rates across geographic and regional populations is necessary to establish the full extent of human variation. The lack of difference between the first and distal molars suggests post-weaning diets, including those which emphasise the continued consumption of milk and milk-based products, have a limited effect on enamel formation. This means dietary shifts, such as weaning, may not be easily detected from dental samples in the fossil hominin record using histological techniques

An Investigation of Melanin-concentrating Hormone Receptor Internalization – Or Lack Thereof

Melanin-concentrating hormone (MCH), a cyclic peptide hormone involved in energy homeostasis, is known to bind to two G protein-coupled receptors (GPCRs) in mammals. These receptors, melanin-concentrating hormone receptor 1 (MCHR1) and melanin-concentrating hormone receptor 2 (MCHR2), have been a popular target for MCH antagonists in an effort to fight the ongoing epidemic of obesity. In the presence of prolonged stimulus it is common for GPCRs to undergo rapid desensitization. However, the desensitization mechanisms of MCHR1 and MCHR2 are as yet poorly understood. This study aims to create epitope-tagged expression vectors to allow for the expression of MCHR1 and MCHR2 in a tissue model. Utilizing a modified cell-based ELISA and fluorescence microscopy, the sequestration of MCHR1 and MCHR2 would be measured after agonist stimulus. Receptor interactions with GRK2 and ?-arrestins would also be measured. The over expression of both MCHR1 and MCHR2 proved to be cytotoxic to BHK570 cells. The overexpression of GRK2, ?-arrestin 1, and ?-arrestin 2 showed a relatively small but statistically significant increase in receptor internalization. Fluorescence microscopy suggests that the interaction between MCHR1 and ?-arrestins were transient in nature. These finding suggest that MCHR1 can be internalized via the clathrin-mediated pathway. It is likely MCH signaling is mediated a cell specific manner based on the cellular expression levels of GRKs and ?-arrestins.SUNY BrockportBiologyMaster of Science (MS)Biology Master’s These

An Investigation of Melanin-concentrating Hormone Receptor Internalization – Or Lack Thereof

Melanin-concentrating hormone (MCH), a cyclic peptide hormone involved in energy homeostasis, is known to bind to two G protein-coupled receptors (GPCRs) in mammals. These receptors, melanin-concentrating hormone receptor 1 (MCHR1) and melanin-concentrating hormone receptor 2 (MCHR2), have been a popular target for MCH antagonists in an effort to fight the ongoing epidemic of obesity. In the presence of prolonged stimulus it is common for GPCRs to undergo rapid desensitization. However, the desensitization mechanisms of MCHR1 and MCHR2 are as yet poorly understood. This study aims to create epitope-tagged expression vectors to allow for the expression of MCHR1 and MCHR2 in a tissue model. Utilizing a modified cell-based ELISA and fluorescence microscopy, the sequestration of MCHR1 and MCHR2 would be measured after agonist stimulus. Receptor interactions with GRK2 and β-arrestins would also be measured. The over expression of both MCHR1 and MCHR2 proved to be cytotoxic to BHK570 cells. The overexpression of GRK2, β-arrestin 1, and β-arrestin 2 showed a relatively small but statistically significant increase in receptor internalization. Fluorescence microscopy suggests that the interaction between MCHR1 and β-arrestins were transient in nature. These finding suggest that MCHR1 can be internalized via the clathrin-mediated pathway. It is likely MCH signaling is mediated a cell specific manner based on the cellular expression levels of GRKs and β-arrestins

An optimal cost approach to aircraft structural design

The efficiency of the structure of a civil aircraftmay be gauged by the financial performance of the aircraftover its life span.In this thesis a method of structural design is proposedwith the object of maximising the life-cycle profit for theairline operating the aircraft. In the formulation of thedesign process. original contributions have been made in variousaspects of optimal cost design theory.The design process is applied to the optimisation of aspecimen structure, which is representative of an idealisedaircraft wing. The results of the analysis are of importance,since they indicate the manner in which the optimal configurationof a practical structure will vary with the individualcharacteristics of the aircraft design in which the structureis to be incorporated.The degree to which the optimisation process is degradedby those errors encountered in a practical environment isascertained by means of sensitivity analyses

THE LANGUAGE OF MODERN NEWS AND TIMELESSNESS: REFORMING JOURNALISM IN THE NON-OCCIDENTAL WORLD

ABSTRAK Satu transformasi diperlukan dalam etos berita, komentar dan kewartawanan dengan membabitkan dimensi-dimensi keabadian dan bersifat transendan. Makalah ini mencadangkan amalan kini yang tidak menerima ketidakserasia

Metal-Substituted Microporous Aluminophosphates

This chapter aims to present the zeotypes aluminophosphates (AlPOs) as a complementary alternative to zeolites in the isomorphic incorporation of metal ions within all-inorganic microporous frameworks as well as to discuss didactically the catalytic consequences derived from the distinctive features of both frameworks. It does not intend to be a compilation of either all or the most significant publications involving metal-substituted microporous aluminophosphates. Families of AlPOs and zeolites, which include metal ion-substituted variants, are the dominant microporous materials. Both these systems are widely used as catalysts, in particular through aliovalent metal ions substitution. Here, some general description of the synthesis procedures and characterization techniques of the MeAPOs (metal-contained aluminophosphates) is given along with catalytic properties. Next, some illustrative examples of the catalytic possibilities of MeAPOs as catalysts in the transformation of the organic molecules are given. The oxidation of the hardly activated hydrocarbons has probably been the most successful use of AlPOs doped with the divalent transition metal ions Co2+, Mn2+, and Fe2+, whose incorporation in zeolites is disfavoured. The catalytic role of these MeAPOs is rationalized based on the knowledge acquired from a combination of the most advanced characterization techniques. Finally, the importance of the high specificity of the structure-directing agents employed in the preparation of MeAPOs is discussed taking N,N-methyldicyclohexylamine in the synthesis of AFI-structured materials as a driving force. It is shown how such a high specificity could be predicted and how it can open great possibilities in the control of parameters as critical in catalysis as crystal size, inter-and intracrystalline mesoporosity, acidity, redox properties, incorporation of a great variety of heteroatom ions or final environment of the metal site (surrounding it by either P or Al)