Human deciduous teeth from the Middle Stone Age layers of Sibudu Cave (South Africa)

Abstract: In the African Pleistocene, the fossil evidence for early Homo sapiens populations is still relatively limited. Here we present two additional specimens (two deciduous teeth) recovered from the Middle Stone Age (MSA) deposits of Sibudu Cave (KwaZulu‐Natal, South Africa). We describe their morphology and metrics, using three‐dimensional models of the teeth obtained from high‐resolution micro‐CT images. The first specimen is a Ldm1 (HUM. TO 1) recovered in the BS5 layer dated 77.3 ± 2.7 ka, and associated with stone tools assigned to the “pre‐Still Bay” assemblage. The other specimen is a Rdi1 (HUM. TO 2) coming from the Pinkish Grey Sand (PGS) layer, dated 64.7±2.3 ka, and associated with a Howieson’s Poort industry. Both teeth are well preserved, with minor post mortem cracks not affecting the overall morphology, and they comprise the intact, worn crown and the remnants of the roots, naturally resorbed. A large carious lesion occupies most of the distal face and part of the occlusal surface in the Ldm1; also a chip of enamel is missing from the disto‐buccal corner. In the Rdi1 average enamel thickness and relative enamel thickness values have been measured. For both teeth, we compared mesiodistal (MD) and bucco‐lingual (BL) diameters with those of other Late Pleistocene deciduous teeth and extant Homo sapiens. The analysis has shown that the teeth are comparable in size with the other MSA specimens described in the literature

Potential role of low kV ex vivo micro-CT for 3D morphometry of paraffin embedded coronary vessels before histology

Purpose: Micro CT is an established tool for non destructive 3D inspection of small specimens. Aim of the study was to demonstrate that despite its limitations in differentiation of soft materials, micro CT can reliably display coronary vessel structure and surrounding tissues after paraffin embedding. Data were obtained from coronary specimens of pig, physical phantoms and numerical simulations. Preliminary images with dual-energy techniques are also shown. Methods: A micro CT scanner built by our group was used for the experiments. The x-ray tube was set up in the range of 20-50 kV; the voxel size was set to 21 μm. A phantom composed of formalin fixed fat and myocardium of rat, dehydrated and paraffin embedded, was used to measure the contrast of different tissues with respect to background. Similar acquisitions were simulated numerically. Real samples of pig excised coronary arteries were processed in the same way and acquired with the same settings; resulting images were compared to those obtained by histology. Results: In phantom, the myocardium contrast vs. paraffin varied from 40% at 20 kV to 29% at 50 kV. The fat contrast vs. background was 2% at 20 kV, whereas it was indistinguishable from the background at 50 kV; all the contrasts in phantom appeared lower than those expected from simulations, probably because of tissue shrinkage. In the samples from pig (see Figure), the vessel wall contrast was 25% greater than the myocardium contrast; the pericardium and a balloon induced stenosis were clearly distinguished. All micro CT scans were shorter than 1 hour. Conclusion: Micro CT is a useful complementary tool for the 3D morphometry of coronary vessels after paraffin embedding, and it can help for the preliminary identification of features of interest for subsequent histological analysis

Ex-vivo micro-CT for the assessment of the structure of paraffin embedded coronary vessels before histology

Purpose: Aim of the study was to demonstrate that absorption-based single low-energy micro-CT can reliably display coronary vessel structure and surrounding tissues after paraffin embedding. Methods and Materials: A micro-CT scanner built by our group was used for the experiments. The x-ray tube was set up in the range of 20-50 kV. A phantom composed of formalin fixed fat and myocardial tissues of rat, dehydrated and paraffin embedded, was used to measure the image contrast of relevant tissues with respect to the background. Similar acquisitions were simulated using standardized attenuation functions and simulated spectra. Real samples of pig excised coronary arteries were also processed in the same way and acquired with similar settings; resulting images were compared to those obtained by histology. The voxel size in the micro-CT images was 21 μm. Results: In phantom, the myocardium contrast vs. paraffin varied from 40% at 20 kV to 29% at 50 kV. The fat contrast was 2% at 20 kV, whereas it was indistinguishable from the background at 50 kV. The pericardium and a balloon induced stenosis were clearly distinguished. A noncalcified fatty streak was also identified. All contrasts in phantom appeared lower than those expected from simulations, probably because of the sample processing. The image quality was sufficient for segmentation purposes, allowing quantitative morphometry within the selected Volume of Interest (VOI). Conclusion: Micro-CT is a useful complementary tool for the assessment of coronary vessels structure after sample embedding in paraffin prior to histological examination. This type of imaging can help for the identification of features for subsequent histological analysis in experimental models of restenosis and atherogenesis

Maternal and Sex Dependency of Insulin Resistance: Longitudinal PET and Echocardiography Study from the Healthy Fetus to the Adult Minipig

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Combined Effect of Fatty Diet and Cognitive Decline on Brain Metabolism, Food Intake, Body Weight, and Counteraction by Intranasal Insulin Therapy in 3×Tg Mice

Obesity and cognitive decline can occur in association. Brain dysmetabolism and insulin resistance might be common underlying traits. We aimed to examine the effect of high-fat diet (HFD) on cognitive decline, and of cognitive impairment on food intake and body-weight, and explore efficacy of chronic intranasal insulin (INI) therapy. We used control (C) and triple transgenic mice (3×Tg, a model of Alzheimer’s pathology) to measure cerebral mass, glucose metabolism, and the metabolic response to acute INI administration (cerebral insulin sensitivity). Y-Maze, positron emission-computed tomography, and histology were employed in 8 and 14-month-old mice, receiving normal diet (ND) or HFD. Chronic INI therapy was tested in an additional 3×Tg-HFD group. The 3×Tg groups overate, and had lower body-weight, but similar BMI, than diet-matched controls. Cognitive decline was progressive from HFD to 3×Tg-ND to 3×Tg-HFD. At 8 months, brain fasting glucose uptake (GU) was increased by C-HFD, and this effect was blunted in 3×Tg-HFD mice, also showing brain insulin resistance. Brain mass was reduced in 3×Tg mice at 14 months. Dentate gyrus dimensions paralleled cognitive findings. Chronic INI preserved cognition, dentate gyrus and metabolism, reducing food intake, and body weight in 3×Tg-HFD mice. Peripherally, leptin was suppressed and PAI-1 elevated in 3×Tg mice, correlating inversely with cerebral GU. In conclusion, 3×Tg background and HFD exert additive (genes*lifestyle) detriment to the brain, and cognitive dysfunction is accompanied by increased food intake in 3×Tg mice. PAI-1 levels and leptin deficiency were identified as potential peripheral contributors. Chronic INI improved peripheral and central outcomes

Non-enhanced micro-CT of paraffin embedded coronary vessels: a tool for experimental atherosclerosis

Purpose. To assess and quantify morphometric parameters of full-length coronary arteries in three dimensions at high resolution by micro-CT (?CT), and to evaluate the possible integration with in vivo information by invasive coronary angiography (ICA) and and intravascular ultrasound (IVUS). Methods and Materials. Excised left coronary artery (LMCA and LAD) and underlying myocardium from pigs on a high-cholesterol diet were fixed in formalin, dehydrated and embedded in paraffin as a whole sample inside a Falcon-type test tube. In vivo information obtained by ICA and IVUS were also available for the same animals. After the ?CT scan, the samples were further processed in order to perform standard histological stains. Results. For each sample, we have obtained a reconstructed volume of 512x512x1400 isotropic voxels, with a voxel size of 57.4^3 ?m^3. The ?CT images provided good discrimination between fat, muscle and calcium, allowing a reliable segmentation of walls and lesions. The profiles of total area, wall area and calcium along the entire coronary artery allowed a comprehensive evaluation of the progress of atherosclerosis in terms of intimal thickening, plaque formation and calcification. Microcalcifications down to 0.2 nl (nanoliters) were localized and displayed in 3D. The integration with IVUS allowed also to recover the lumen area under in vivo physiological state. Conclusion. Micro-CT allows a comprehensive evaluation in 3D and at high resolution of plaque evolution in an experimental model of coronary artery disease in pigs. The integration with ICA and IVUS can lead to the full characterization of disease progression

Probing the Epoch of Reionization with Milky Way Satellites

While the connection between high-redshift star formation and the local universe has recently been used to understand the observed population of faint dwarf galaxies in the Milky Way (MW) halo, we explore how well these nearby objects can probe the epoch of first light. We construct a detailed, physically motivated model for the MW satellites based on the state-of-the-art Via Lactea II dark-matter simulations. Our model incorporates molecular hydrogen (H_2) cooling in low-mass systems and inhomogeneous photo-heating feedback during the internal reionization of our own galaxy. We find that the existence of MW satellites fainter than M_V ~ -5 is strong evidence for H_2 cooling in low-mass halos, while satellites with -5 > M_V > -9 were affected by hydrogen cooling and photoheating feedback. The age of stars in very low-luminosity systems and the minimum luminosity of these satellites are key predictions of our model. Most of the stars populating the brightest MW satellites could have formed after the epoch of reionization. Our models also predict a significantly larger dispersion in M_300 values than observed and a number of luminous satellites with M_300 as low as 10^6 solar masses.Comment: 11 pages, 6 figures. Accepted by MNRAS. Updated to accepted versio

Peptides and proteins in a confined environment: NMR spectra at natural isotopic abundance

Confinement of proteins and peptides in a small inert space mimics the natural environment of the cell, allowing structural studies in conditions that stabilize folded conformations. We have previously shown that confinement in polyacrylamide gels (PAGs) is sufficient to induce a change in the viscosity of the aqueous solution without changing the composition and temperature of the solvent. The main limitation of a PAG to run NMR experiments in a confined environment is the need for labelling the peptides. Here we report the use of the agarose gel to run the NMR spectra of proteins and peptides. We show that agarose gels are completely transparent in NMR experiments, relieving the need for labelling. Although it is necessary to expose biomolecules to fairly high temperatures during sample preparation, we believe that this is not generally an obstacle to the study of peptides, and found that the method is also compatible with temperature-resistant proteins. The mesh of agarose gels is too wide for direct effects of confinement on the stability of proteins but confinement can be easily exploited to interact the proteins with other reagents, including crowding macromolecules that can eventually lead to fold stabilization. The use of these gels is ideally suited for low-temperature studies; we show that a very flexible peptide at subzero temperatures is stabilized into a well-folded conformation