Confocal scanning optical microscopy of a 3-million-year-old Australopithecus afarensis femur.

Portable confocal scanning optical microscopy (PCSOM) has been specifically developed for the noncontact and nondestructive imaging of early human fossil hard tissues, which here we describe and apply to a 3-million-year-old femur from the celebrated Ethiopian skeleton, "Lucy," referred to Australopithecus afarensis. We examine two bone tissue parameters that demonstrate the potential of this technology. First, subsurface reflection images from intact bone reveal bone cell spaces, the osteocyte lacunae, whose density is demonstrated to scale negatively with body size, reflecting aspects of metabolism and organismal life history. Second, images of a naturally fractured cross section near to Lucy's femoral mid-shaft, which match in sign those of transmitted circularly polarized light, reveal relative collagen fiber orientation patterns that are an important indicator of femoral biomechanical efficacy. Preliminary results indicate that Lucy was characterized by metabolic constraints typical for a primate her body size and that in her femur she was adapted to habitual bipedalism. Limitations imposed by the transport and invasive histology of unique or rare fossils motivated development of the PCSOM so that specimens may be examined wherever and whenever nondestructive imaging is required.

Ontogenetic patterning of cortical bone microstructure and geometry at the human mid-shaft femur.

The bone growth process has long-lasting effects on adult bone structure and mechanical adaptation, yet the tissue level dynamics of growth are poorly studied. The specific aims of this study were to (1) quantify changes in bone size and shape through ontogeny, (2) describe the distribution of tissue types and patterns of cortical drift and expansion through ontogeny, and (3) explore relationships between cortical drift and ontogenetic variation geometric size and shape. The study utilized 14 juvenile (ages 2-19) mid-shaft femur blocks removed at autopsy from individuals who died suddenly. Eighty-mum-thick sections were imaged using polarized and brightfield microscopy. For descriptive purposes the sample was divided into five age groups. Features of collagen fiber matrix orientation, vascularity (e.g., pore orientation and density), and osteocyte lacunar density and shape were used to classify primary and secondary tissue types in LM images. This information, combined with evaluation of resorptive versus depositional bone surfaces, was used to identify cortical drift direction. A pattern of posterior and medial drift was identified at the mid-shaft femur in the toddler years. The drift pattern shifts antero-laterally in late childhood, predating the appearance of a more adult-like geometry. On the basis of the presence of transitional fibrolamellar bone complex, growth is more rapid during the toddler years and peri-puberty, and slower in early to late childhood and in later adolescence. Extensive variability in histological and geometric organization typifies the sample, particularly beginning in late childhood. The potential implications of this variability for adult fracture risk warrant further study. Anat Rec, 2009. (c) 2008 Wiley-Liss, Inc.

Relationships among microstructural properties of bone at the human midshaft femur.

Mineralization density and collagen fibre orientation are two aspects of a bone's microstructural organization that influence its mechanical properties. Previous studies by our group have demonstrated a distinctly non-random, though highly variable, spatial distribution of these two variables in the human femoral cortex. In this study of 37 specimens, these variables are examined relative to one another in order to determine whether regions of bone demonstrating higher or lower mineralization density also demonstrate a prevalence of either transversely or longitudinally oriented collagen fibres. An analysis of rank-transformed collagen fibre orientation (as determined by circularly polarized light) and mineralization density (as determined by backscattered electron microscopy) data sets demonstrated that areas of low mineralization density (predominantly in the anterior-lateral cortex) tended to correspond to regions of higher proportions of longitudinally oriented collagen fibres. Conversely, areas of higher mineralization density (postero-medially) tended to correspond to regions of higher proportions of transversely oriented collagen fibres. High variability in the sample led to generally low correlations between the two data sets, however. A second analysis focused only on the orientation of collagen fibres within poorly mineralized bone (representing bone that was newly formed). This analysis demonstrated a lower proportion of transverse collagen fibres in newly formed bone with age, along with some significant regional differences in the prevalence of collagen fibres of either orientation. Again high variability characterized the sample. These results are discussed relative to the hypothesized forces experienced at the midshaft femur.

Intrapopulation variability in mineralization density at the human femoral mid-shaft.

One of several microstructural variables known to affect the mechanical properties of bone is the degree of mineralization of bone matrix. The aim of this study was to examine mineralization density, and its variability with age and sex, from a biomechanical perspective. Histological sections, prepared from mid-shaft femora obtained at autopsy from 40 individuals, were imaged using quantitative backscattered electron microscopy. Each cross-section montage was divided into 48 segments according to anatomical position. Mean grey-level values were quantified for each segment. One-way ANOVA with Tukey HSD post hoc tests were used to test for differences in mineralization between segments, age groups and sexes. Results showed a decrease in overall degree of mineralization density with adult age, but an increase in its coefficient of variation. Degree of mineralization was significantly lower in the periosteal third of the cortex, particularly in the antero-lateral aspect. This pattern was most prevalent amongst the youngest individuals in the sample. Whereas males between ages 45-64 years had a higher average degree of mineralization than females, the opposite was true of the older age group. Mineralization significantly decreased between middle and older age groups in males, but not in females. Despite limited consistencies in the location of high and low average mineralization bone through the cortex, the degree of interindividual variation, even within a single age and sex group, overwhelmed population level trends. The patterns of variability identified in this study are consistent with results of an analysis of collagen fibre orientation using the same sample material.

Correlative light and backscattered electron microscopy of bone--part II: automated image analysis.

Detailed studies of biological phenomena often involve multiple microscopy and imaging modes and media. For bone biology, various forms of light and electron microscopy are used to study the microscopic structure of bone. Integrating information from the different sources is necessary to understand how different aspects of the bone structure interact. To accomplish this, methods were developed to prepare and image thin sections for correlative light microscopy (LM) and backscattered electron imaging in the scanning electron microscope (BSE-SEM). Images of the same fields of view may then be analyzed for degrees of relationships between specimen features not observed by LM or SEM alone. These methods are applied here to study possible associations between the degree of bone mineralization and pattern of collagen fiber orientation in the mid-shaft of the human femur. The "relational images" obtained allow us to examine the relationship between these two variables, both objectively and quantitatively.

Correlative light and backscattered electron microscopy of bone--Part I: Specimen preparation methods.

A method for preparing nondecalcified bone and tooth specimens for imaging by both light microscopy (LM) and backscattered electron microscopy in the scanning electron microscope (BSE-SEM) is presented. Bone blocks are embedded in a polymethylmethacrylate (PMMA) mixture and mounted on glass slides using components of a light-cured dental adhesive system. This method of slide preparation allows correlative studies to be carried out between different microscopy modes, using the same histologic section. It also represents a large time savings relative to other mounting methods whose media require long cure times.

Rowell's syndrome: report of a case.

A 47-year-old woman presented with a long-standing history of an erythema multiforme-like eruption in association with lupus erythematosus. Unusual laboratory and immunologic findings were consistent with a diagnosis of Rowell's syndrome, which includes lupus erythematosus in association with erythema multiforme-like skin lesions, a speckled antinuclear antibody pattern, and a positive rheumatoid factor. We believe that our patient meets the criteria for this rarely reported entity.

Photodistributed hypertrophic lichen planus in association with acquired immunodeficiency syndrome: a distinct entity.

The cutaneous manifestations of human immunodeficiency virus infection include papulosquamous diseases, viral and fungal infections, and neoplastic disorders. Eczematous photosensitivity disorders have been reported in patients infected with the human immunodeficiency virus. We describe a patient with advanced acquired immunodeficiency syndrome who developed photodistributed hypertrophic lichen planus. We believe this is a distinct cutaneous manifestation of human immunodeficiency virus infection.

Regeneration of attachment apparatus lost due to disease of endodontic origin.

Osseous defects may be due to endodontic or to periodontic involvement or a combination of the two. Careful diagnosis is required to determine the correct form of treatment.

An unusual cutaneous reaction secondary to allopurinol.

A 60-year-old man presented with erythematous papules and plaques on his body as well as a violaceous indurated nodule on his face. A cutaneous drug reaction secondary to allopurinol was considered. Examination of biopsy specimens revealed a dense lymphocytic infiltrate of the skin as is seen in lymphocytoma cutis. The lesions cleared promptly after use of allopurinol was discontinued. A literature review showed that an eruption of this kind, including a nodule on the face that histologically simulated a lymphocytic infiltrate of the skin, has not yet been reported secondary to allopurinol.