ABSTRACT
Enamel formation produces the most highly mineralized tissue in the human body. The growth of enamel crystallites is assisted by enamel proteins and proteinases. As enamel formation progresses from secretory to maturation stages, the composition of the matrix with its mineral and non-mineral components dynamically changes in an inverse fashion. We hypothesized that appropriately calibrated micro-computed tomography (µCT) technology is suitable to estimate the mineral content (weight and/or density) and volume comparable in accuracy with that for directly weighed and sectioned enamel. Different sets of mouse mandibular incisors of C57BL/6 mice were used for dissections and µCT reconstructions. Calibration phantoms corresponding to the range of enamel mineral densities were used. Secretory-stage enamel contained little mineral and was consequently too poor in contrast for enamel volumes to be accurately estimated by µCT. Maturation-stage enamel, however, showed remarkable correspondence for total mineral content per volume where comparisons were possible between and among the different analytical techniques used. The main advantages of the µCT approach are that it is non-destructive, time-efficient, and can monitor changes in mineral content of the most mature enamel, which is too physically hard to dissect away from the tooth.
Subject(s)
Dental Enamel/chemistry , Minerals/analysis , Amelogenesis/physiology , Animals , Durapatite/analysis , Hot Temperature , Image Processing, Computer-Assisted/methods , Incisor/chemistry , Mice , Mice, Inbred BALB C , Mice, Inbred Strains , Microdissection , Microscopy, Electron, Scanning , X-Ray Microtomography/methodsABSTRACT
Most studies on determinants of community-acquired pneumonia (CAP) in primary care have focused primarily on the elderly. Using a case-control study in four Dutch healthcare centres, determinants of CAP among children and young adults were identified. Cases included 156 young adults (aged 16-40 yrs) and 107 children (aged 0-15 yrs) diagnosed with CAP during 1999-2008. For each case, three controls were selected from the same age group. Separate logistic regression analyses were used to identify determinants in young adults and children. Lower age, asthma and previous upper respiratory tract infections (URTIs) were independently associated with CAP in children. Increasing age, asthma, three or more children at home, current smoking and three or more previous URTIs were independent determinants of CAP in young adults. The present study has three remarkable findings: 1) increasing age was an independent determinant of CAP in young adults; 2) having young children increased the risk of the development of CAP in young adults; and 3) the number of previous URTIs was independently associated with CAP in both children and young adults, possibly due to higher infection susceptibility. Further studies are required in order to better understand the aetiology of CAP and permit better diagnosis and treatment of this serious condition.
Subject(s)
Community-Acquired Infections/etiology , Pneumonia/etiology , Primary Health Care , Adolescent , Adult , Case-Control Studies , Child , Child, Preschool , Community-Acquired Infections/epidemiology , Comorbidity , Female , Humans , Infant , Logistic Models , Male , Netherlands/epidemiology , Pneumonia/epidemiology , Risk FactorsABSTRACT
The complete coding regions of the chromosomally encoded p83/100 protein of four Borrelia garinii strains and one Borrelia burgdorferi sensu stricto strain have been amplified by the polymerase chain reaction (PCR), cloned and sequenced. From alignment studies with the deduced amino acid sequences presented here, and five other published p83/100 sequences, the most heterologous region of the p83/100 molecule was identified to be located between amino acid position 390-540. To study the structure of this heterogeneous region, and internal fragment of the p83/100 genes from 11 additional B. burgdorferi sensu lato strains was amplified by PCR. The PCR products were analyzed by DNA sequencing and restriction enzyme analysis. These internal p83/100 fragments varied in size and sequence. Cluster analysis of internal p83/100 fragments, as well as restriction enzyme analysis, revealed three major groups in accordance with grouping into the three species causing Lyme disease. Strains within the same species (six B. burgdorferi sensu stricto and six B. afzelii strains) showed similar p83/100 partial structures. Nevertheless, nine B. garinii strains showed more sequence variations and could be further divided into two major subgroups. One group is represented by OspA serotype 4 strains, the other more heterogeneous group is represented by OspA serotypes 3, 5, 6 and 7 strains. Phenotypic analysis with four p83/100-specific monoclonal antibodies revealed four distinct reactivity patterns. Antibody L100 1B4 recognized a common epitope of B. burgdorferi sensu stricto and B. afzelii. Antibodies L100 17D3 and L100 18B4 were reactive with an epitope shared by strains of all three species. The broadest reactivity was shown by L100 18B4 which, in contrast to L100 17D3, additionally recognized the relapsing fever borreliae B. turicatae and B. hermsii. L100 8B8 detected a subgroup of the B. burgdorferi sensu stricto strains. Since comparison of the p83/100 molecule with sequences from protein databases showed similarities with characteristics of eukaryotic cell structures, the p83/100 might mimic these structures and may, therefore, be involved in the immune escape mechanism of the pathogenic agent of Lyme disease.
