Missing defects? A comparison of microscopic and macroscopic approaches to identifying linear enamel hypoplasia

Linear enamel hypoplasia (LEH), the presence of linear defects of dental enamel formed during periods of growth disruption, is frequently analyzed in physical anthropology as evidence for childhood health in the past. However, a wide variety of methods for identifying and interpreting these defects in archaeological remains exists, preventing easy cross‐comparison of results from disparate studies. This article compares a standard approach to identifying LEH using the naked eye to the evidence of growth disruption observed microscopically from the enamel surface. This comparison demonstrates that what is interpreted as evidence of growth disruption microscopically is not uniformly identified with the naked eye, and provides a reference for the level of consistency between the number and timing of defects identified using microscopic versus macroscopic approaches. This is done for different tooth types using a large sample of unworn permanent teeth drawn from several post‐medieval London burial assemblages. The resulting schematic diagrams showing where macroscopic methods achieve more or less similar results to microscopic methods are presented here and clearly demonstrate that “naked‐eye” methods of identifying growth disruptions do not identify LEH as often as microscopic methods in areas where perikymata are more densely packed. Am J Phys Anthropol 153:463–472, 2014. © 2013 Wiley Periodicals, Inc.     

The molecular structure of epoxide hydrolase B from Mycobacterium tuberculosis and its complex with a urea-based inhibitor

Mycobacterium tuberculosis (Mtb), the intracellular pathogen that infects macrophages primarily, is the causative agent of the infectious disease tuberculosis in humans. The Mtb genome encodes at least six epoxide hydrolases (EHs A to F). EHs convert epoxides to trans-dihydrodiols and have roles in drug metabolism as well as in the processing of signaling molecules. Herein, we report the crystal structures of unbound Mtb EHB and Mtb EHB bound to a potent, low-nanomolar (IC₅₀ ≈ 19 nM) urea-based inhibitor at 2.1 and 2.4 Å resolution, respectively. The enzyme is a homodimer; each monomer adopts the classical α/β hydrolase fold that composes the catalytic domain; there is a cap domain that regulates access to the active site. The catalytic triad, comprising Asp104, His333 and Asp302, protrudes from the catalytic domain into the substrate binding cavity between the two domains. The urea portion of the inhibitor is bound in the catalytic cavity, mimicking, in part, the substrate binding; the two urea nitrogen atoms donate hydrogen bonds to the nucleophilic carboxylate of Asp104, and the carbonyl oxygen of the urea moiety receives hydrogen bonds from the phenolic oxygen atoms of Tyr164 and Tyr272. The phenolic oxygen groups of these two residues provide electrophilic assistance during the epoxide hydrolytic cleavage. Upon inhibitor binding, the binding-site residues undergo subtle structural rearrangement. In particular, the side chain of Ile137 exhibits a rotation of around 120° about its C^α-C^β bond in order to accommodate the inhibitor. These findings have not only shed light on the enzyme mechanism but also have opened a path for the development of potent inhibitors with good pharmacokinetic profiles against all Mtb EHs of the α/β type.     

Molecular characterization,transcriptional regulation and association analysis with carcass traits of porcine TCAP gene

TCAP (also known as titin-cap or telethonin) is one of the titin interacting Z-disk proteins involved in the regulation and development of normal sarcomeric structure. In this study, we cloned the cDNA and promoter sequences of porcine TCAP gene, which contained a 504 bp full-length coding region. Quantitative real-time PCR (qRT-PCR) analyses showed that porcine TCAP was highly expressed in the skeletal muscle, heart, and kidney. During postnatal muscle development, TCAP expression was down-regulated from 30 days to 120 days in Large White and Meishan pigs. One single nucleotide polymorphism c.334G>A in exon 2 of the TCAP gene was identified and detected by allele-specific primer-polymerase chain reaction (ASP-PCR). Association analysis revealed that the polymorphism had significant associations (P < 0.05 and P < 0.01) with some carcass traits. Analysis of the porcine TCAP promoter in different cell lines demonstrated that it is a muscle-specific promoter. In addition, we found that the porcine TCAP promoter can be activated by MyoD, MyoG and MEF2 in myotubes, which indicated that TCAP may play a role in the regulation of porcine skeletal muscle development. These findings provide useful information for the further investigation of the function of TCAP in porcine skeletal muscle.     

Osteological and dental markers of health in the transition from the Late Antique to the Early Medieval period in Croatia

The purpose of this study is to analyze health at the transition from the Late Antique (LA) to the Early Medieval (EM) period in Croatia. Results of the analyses of skeletal remains are compared with historical and archaeological data to test the hypothesis that the transition was catastrophic. An additional objective is to determine whether the transition was a uniform process, or differentially affected the past inhabitants of Croatia because of various local considerations. To accomplish this, four markers of health: cribra orbitalia, linear enamel hypoplasia, nonspecific periostitis, and trauma were compared in 981 skeletons: 477 from nine urban LA sites, and 504 from six rural EM sites. Data were collected by sex and age for individual, and for co-occurrences of various features. Because continental and Adriatic Croatia has different ecological features, data were specifically tabulated for the two regions. Comparisons between the continental and Adriatic regions of the LA series showed no significant differences in the frequencies of the analyzed markers of stress. Comparisons between the LA and EM series showed similar frequencies in continental Croatia--suggesting no significant discontinuity of living conditions, and a significant increase of cribra orbitalia, periostitis, and trauma frequencies during the EM period in Adriatic Croatia. The deterioration of living conditions primarily affected subadults and males. These data suggest that the transition from the LA to the EM period in Croatia was not a uniform process, but differentially affected population biology most likely because of local cultural, socio-economical or political considerations.     

Brief communication: physiological stress in the Florida Archaic-enamel hypoplasia and patterns of developmental insult in early North American hunter-gatherers

We examined the prevalence and developmental timing of linear enamel hypoplasias (LEHs) in an early Archaic Floridian population from Windover (8,120-6,980 (14)C years B.P. uncorrected). Using digital images, mandibular and maxillary canines were analyzed for defect prevalence and timing of insults. Although overall prevalence was very weakly correlated with earlier defect timing, there were significant differences in defect prevalence that varied by sex and tooth type. The mean LEH count in male mandibular canines was far higher than in male maxillary canines or in female mandibular or maxillary canines. We examined defect timing as a possible predictor of the sex differences in LEH prevalence. There were no significant sex differences in the developmental timing of the earliest defects in either tooth class. Developmental timing is not responsible for the sex differences seen in defect prevalence in mandibular canines.     

Diet and health changes at the end of the Chinese neolithic: the Yangshao/Longshan transition in Shaanxi province.

In this paper we discuss diet and health changes of millet agriculturists in Northern China, Shaanxi province, during the period 7,000-4,000 BP. An episode of intensive climatic oscillations that preceded the onset of colder climate circa the fifth millennium BP divides the period (Shi et al. [1993] Global Planet. Change 7:219-233). The onset of the cooler climate marks the decline of the egalitarian society of Yangshao and the rise of the chiefdom-like society of Longshan. Skeletal materials from the two sites of Beiliu and Jiangzhai are from the earlier phases of Yangshao culture (7,000-6,000 BP), while remains from the Shijia site were excavated from the terminal phase of Yangshao culture (6,000-5,000 BP), a phase that would be expected to show adjustments to strong climatic fluctuations. Human remains from the Longshan culture (5,000-4,000, BP) were found at the Kangjia site. In order to investigate whether the trajectory of diet and health changes persisted beyond the Longshan, a skeletal sample from the Xicun site of the Western Zhao Dynastic period (3,800-2,200 BP) is included in our analyses. All Yangshao sites in our study are characterized by low frequencies of anemia and carious lesions. Some subsistence changes probably occurred during the later phase of Yangshao culture that resulted in elevated masticatory stress and occlusal macrowear among the Shijia people. However, deterioration of community health did not begin until the Longshan, when increased occurrence of porotic hyperostosis and caries is accompanied by decreased adult stature. The transition to softer, more extensively processed food during Longshan is evident in decreased rates of occlusal wear. Increased population density and diminished food values were most likely responsible for these changes. Poor health persisted into the subsequent Dynastic period of Western Zhao.