[Towards a new treatment of retinoblastoma?]

Photodynamic therapy (PDT) is a recent approach for the treatment of small cancerous tumours, on-surface or accessible by endoscopy in which a dye (usually a tetrapyrrolic macrocycle) absorbs light and generates cytotoxic reactive oxygen species leading to cellular damage. Retinoblastoma (Rb) is a rare intraocular tumour of childhood. All the multifocal forms are hereditary and constitute a syndrome of genetic predisposition in the cancer. The current treatments with etoposide or carboplatine expose the patient to the late risk of second cancer. The use of PDT as cancer therapy is particularly attractive due to the use of few mutagenic and non-toxic photosensitizers (PS) prior light excitation and to the localized tumour illumination. The photoefficiency towards Rb of a glycoconjugated porphyrin is discussed and compared with the results obtained with a second-generation photosensitizer, the Foscan. Some in vivo results on an animal model of Rb are presented by a point of view of photoefficiency, biodistribution, pharmacokinetic and longitudinal follow-up of the PDT effect using a new non-invasive method of magnetic resonance imaging of real-time. Photodynamic treatments in association with non-invasive sodium imaging open ways for new treatment tailoring or treatment individualization of retinoblastoma in clinic.

Parallel Declines in Pollinators and Insect-Pollinated Plants in Britain and the Netherlands

Despite widespread concern about declines in pollination services, little is known about the patterns of change in most pollinator assemblages. By studying bee and hoverfly assemblages in Britain and the Netherlands, we found evidence of declines (pre-versus post-1980) in local bee diversity in both countries; however, divergent trends were observed in hoverflies. Depending on the assemblage and location, pollinator declines were most frequent in habitat and flower specialists, in univoltine species, and/or in nonmigrants. In conjunction with this evidence, outcrossing plant species that are reliant on the declining pollinators have themselves declined relative to other plant species. Taken together, these findings strongly suggest a causal connection between local extinctions of functionally linked plant and pollinator species.

Parallel declines in pollinators and insect-pollinated plants in Britain and the Netherlands

Despite widespread concern about declines in pollination services, little is known about the patterns of change in most pollinator assemblages. By studying bee and hoverfly assemblages in Britain and the Netherlands, we found evidence of declines (pre-versus post-1980) in local bee diversity in both countries; however, divergent trends were observed in hoverflies. Depending on the assemblage and location, pollinator declines were most frequent in habitat and flower specialists, in univoltine species, and/or in nonmigrants. In conjunction with this evidence, outcrossing plant species that are reliant on the declining pollinators have themselves declined relative to other plant species. Taken together, these findings strongly suggest a causal connection between local extinctions of functionally linked plant and pollinator species.

Spontaneous condensation in DNA-polystyrene- b-poly(l-lysine) polyelectrolyte block copolymer mixtures

We investigated the condensation of calf thymus DNA by amphiphilic polystyrene(m)-b-poly(l-lysine)(n) block copolymers ( PS(m)-b- PLys(n), m, n = degree of polymerization), using small-angle X-ray scattering, polarized optical microscopy and laser scanning confocal microscopy. Microscopy studies showed that the DNA condenses in the form of fibrillar precipitates, with an irregular structure, due to electrostatic interactions between PLys and DNA. This is not modified by the presence of hydrophobic PS block. Scattering experiments show that the structure of the polyplexes corresponds to a local order of DNA rods which becomes more compact upon increasing n. It can be concluded that for DNA/ PS(m)-b- PLys(n) polyplexes, the balance between the PLys block length and the excess charge in the system plays an essential role in the formation of a liquid crystalline phase.

Epidemic trichodinosis associated with severe epidermal hyperplasia in largemouth bass, Micropterus salmoides, from North Carolina, USA

An epidemic of trichodinosis associated with severe epidermal hyperplasia occurred in adult largemouth bass (Micropterus salmoides) from the Chowan River drainage, North Carolina (USA) in late winter to early spring 2002. Initial reports by anglers of fish with a "jelly-like slime coat" on the skin prompted an electrofishing survey in which about 10% of sampled largemouth bass had a very thick, bluish-white "mucoid layer" on the body and fins. Moderate to heavy infestations of the ciliate Trichodina were detected in wet mounts of skin from five of five fish having the mucoid layer; these fish also had significant gill infestations. An additional two fish with only mild reddening and four asymptomatic fish (no skin lesions) had mild skin infestations but no gill infestations. Two asymptomatic fish had no skin parasites. Four fish with the mucoid layer were necropsied and had extremely severe epidermal hyperplasia on the body and fins. The hyperplasic epidermis had relatively few mucus cells and typically was about 5-10 times thicker than healthy epidermis. The upper four fifths of the epidermis consisted of finely vacuolated, highly flattened, somewhat disorganized epithelial cells. No other significant clinical or histopathologic abnormalities were detected. No systemic infection by pathogenic bacteria was noted. The environmental cause of the epidemic is uncertain but the lesions suggest that some chronic stressor was involved.

The significance of at-risk factors in ultrasound surveillance of developmental dysplasia of the hip. A ten-year prospective study

Of the 34,723 infants born between 1 June 1992 and 31 May 2002, the hips of 2578 with clinical instability or at-risk factors for developmental dysplasia of the hip were imaged by ultrasound. Instability of the hip was present in 77 patients, of whom only 24 (31.2%) had an associated risk factor. From the 'at-risk' groups, the overall risk of type-III dysplasia, instability and irreducibility was 1:15 when family history, 1:27 when breech delivery and 1:33 when foot deformity were considered as risk factors. Of those hips which were ultrasonographically stable, 88 had type-III dysplasia. A national programme of selective ultrasound screening of at-risk factors for the diagnosis of hip dislocation or instability alone cannot be recommended because of its low predictive value (1:88). However, the incidence of type-III dysplasia and hip dislocation or dislocatability in the groups with clinical instability, family history, breech position and possibly postural foot deformity as risk factors could justify a programme of selective ultrasound imaging.

Relationship between tumour growth rate and carbogen-based functional MRI for a chemically induced HCC in mice

We previously performed MRI studies of HCC (hepatocellular carcinomas) in mice showing the feasibility of measuring a carbogen effect. In the present study carbogen response of the whole tumour was compared with growth characteristics during longitudinal follow-up. HCC were chemically induced. The imaging protocol at 4.7 T comprised a fast spin-echo sequence for high-resolution screening and measurement of growth curves, and a fast gradient echo sequence allowing an entire T2*w image acquisition per respiratory cycle to perform fMRI under carbogen breathing. A new parameter, T+, the fraction of tumour voxels with increased intensity under carbogen was measured on manually defined ROIs. Twenty-two HCC were followed for 3-10 weeks. Tumours were divided into two groups, "regularly" and "irregularly" growing tumours. A linear correlation between T+ and tumour growth rate was observed only for "regularly" growing HCC. These results suggest a link between tumour growth rates and tumour fractions exhibiting signal increase upon carbogen breathing. They are compatible with observations by others that rapidly growing tumours are more hypoxic than slowly growing ones. Combined measurement of T+ and tumour growth may become a useful noninvasive follow-up approach for assessment and/or management of therapies involving vasculature-targeting and anti-proliferative drugs.

Comparison of intravenous ganciclovir and cytomegalovirus hyperimmune globulin pre-emptive treatment in cytomegalovirus-positive heart transplant recipients

BACKGROUND

We compared the use of intravenous ganciclovir and cytomegalovirus hyperimmune globulin (CMVIG) as a pre-emptive treatment for cytomegalovirus (CMV)-positive heart transplant recipients.

METHODS

Of 59 CMV-seropositive adult heart transplant recipients enrolled in Group 1, 37 tested positive for pp65 antigen within 12 weeks post-transplantation. These patients were randomized to receive either intravenous ganciclovir (n = 23) or CMVIG (n = 14). Group 2 included 133 CMV-seropositive heart transplant recipients who were not tested for CMV antigenemia and who received no anti-CMV therapy.

RESULTS

CMV disease developed in 0 of 59 patients from Group 1, and in 27 of 133 patients (20%) in Group 2 (p = 0.0001). The incidence of superinfections was lower in Group 1 (0.28 +/- 0.46) than in Group 2 (1.10 +/- 1.33) (p = 0.01). The 2 groups did not differ with regard to incidence of rejection (0.7 +/- 0.9 in Group 1 vs 1.0 +/- 1.2 in Group 2; p = NS), transplant coronary artery disease at 1 year (14% in Group 1 vs 16% in Group 2; p = NS) or post-transplant lymphoproliferative disease (0% in Group 1 vs 2% in Group 2; p = NS). Ganciclovir and CMVIG therapies were associated with similar rates of rejection (0.52 +/- 0.6 with ganciclovir vs 0.50 +/- 0.60 with CMVIG; p = NS), superinfection (0.30 +/- 0.48 with ganciclovir vs 0.25 +/- 0.46 with CMVIG; p = NS), and transplant coronary artery disease at 1 year (13% with ganciclovir vs 14% with CMVIG, p = NS).

CONCLUSIONS

The pre-emptive anti-CMV approach is superior to prophylaxis in CMV-seropositive heart transplant recipients. Both ganciclovir and CMVIG are equally effective.

Premating barriers to gene exchange and their implications for the structure of a mosaic hybrid zone between Chorthippus brunneus and C. jacobsi (Orthoptera: Acrididae)

Many hybrid zones contain a deficit of hybrid genotypes relative to expectations from tension zone models. This is often associated with separation of parental genotypes into distinct habitats (mosaicism), but sometimes parentals can be found co-occuring in the same local population (bimodality). In both cases, prezygotic isolation may play an important role in determining the genotypic composition of the zone. Chorthippus brunneus and C. jacobsi (Orthoptera: Acrididae) meet and form a complex hybrid zone in northern Spain. Analysis of stridulatory peg numbers reveals partial spatial and seasonal isolation in a 25 km2 area of the zone: C. jacobsi phenotypes predominate in June and July and are present in both valley and mountain habitats; C. brunneus phenotypes predominate in August and are restricted to valley habitats, always in sympatry with C. jacobsi. Strong assortative mating was observed in laboratory mating experiments. Spatial, seasonal and behavioural isolation combine to produce strong premating isolation in the study area. These results suggest a role for premating isolation in maintaining both the mosaic structure and bimodality of this hybrid zone.

Foray search: an effective systematic dispersal strategy in fragmented landscapes

In the absence of evidence to the contrary, population models generally assume that the dispersal trajectories of animals are random, but systematic dispersal could be more efficient at detecting new habitat and may therefore constitute a more realistic assumption. Here, we investigate, by means of simulations, the properties of a potentially widespread systematic dispersal strategy termed "foray search." Foray search was more efficient in detecting suitable habitat than was random dispersal in most landscapes and was less subject to energetic constraints. However, it also resulted in considerably shorter net dispersed distances and higher mortality per net dispersed distance than did random dispersal, and it would therefore be likely to lead to lower dispersal rates toward the margins of population networks. Consequently, the use of foray search by dispersers could crucially affect the extinction-colonization balance of metapopulations and the evolution of dispersal rates. We conclude that population models need to take the dispersal trajectories of individuals into account in order to make reliable predictions.

Responses of butterflies to twentieth century climate warming: implications for future ranges

We analyse distribution records for 51 British butterfly species to investigate altitudinal and latitudinal responses to twentieth century climate warming. Species with northern and/or montane distributions have disappeared from low elevation sites and colonized sites at higher elevations during the twentieth century, consistent with a climate explanation. We found no evidence for a systematic shift northwards across all species, even though 11 out of 46 southerly distributed species have expanded in the northern part of their distributions. For a subset of 35 species, we model the role of climate in limiting current European distributions and predict potential future distributions for the period 2070-2099. Most northerly distributed species will have little opportunity to expand northwards and will disappear from areas in the south, resulting in reduced range sizes. Southerly distributed species will have the potential to shift northwards, resulting in similar or increased range sizes. However, 30 out of 35 study species have failed to track recent climate changes because of lack of suitable habitat, so we revised our estimates accordingly for these species and predicted 65% and 24% declines in range sizes for northern and southern species, respectively. These revised estimates are likely to be more realistic predictions of future butterfly range sizes.

Super-osteons (remodeling clusters) in the cortex of the femoral shaft: influence of age and gender

Previous studies of cortical remodeling in the fractured femoral neck indicated that the merging of spatially clustered remodeling osteons could result in the formation of deleteriously large cavities associated with femoral neck fracture. This study aimed to identify whether remodeling osteons in the femoral shaft were also clustered and to assess the influence of age and gender. Microradiographic images of femoral mid-shaft cross-sections from 66 subjects over 21 years of age were analyzed to determine the number, size and location of all Haversian canals. Those most recently remodeled were identified using an edge-detection algorithm highlighting the most marked differential gradients in grey levels. Cluster analysis (JMP software) of these osteons identified the proportion of recently remodeled osteons that were within 0.75 mm clusters. As in the femoral neck, remodeling osteons were significantly more clustered than could occur by chance (real, 59.4%; random, 39.4%; P < 0.0001). The density of these clusters (number/mm(2)) was not significantly associated with subject age or gender but was greatest near the periosteum and decreased toward the marrow cavity (periosteal 0.043 +/- 0.004; mid-cortex 0.028 +/- 0.003; endosteal 0.017 +/- 0.002). Cortical porosity increased with age. The presence of giant canals (diameter >385 microm) was inversely related to the presence of clusters (R(2) = 0.237, P < 0.0001). This data suggest that remodeling osteons tend to be spatially colocalized in the shaft as they are in the neck of the femur and their presence is independent of age or gender. We propose that these remodeling clusters be termed super-osteons. The negative relationship between super-osteons and giant canals raises the intriguing possibility that loss of the control of remodeling depth results in the merging of osteonal systems to form deleteriously large cortical cavities with a marked reduction in bone strength.

Rapid responses of British butterflies to opposing forces of climate and habitat change

Habitat degradation and climate change are thought to be altering the distributions and abundances of animals and plants throughout the world, but their combined impacts have not been assessed for any species assemblage. Here we evaluated changes in the distribution sizes and abundances of 46 species of butterflies that approach their northern climatic range margins in Britain-where changes in climate and habitat are opposing forces. These insects might be expected to have responded positively to climate warming over the past 30 years, yet three-quarters of them declined: negative responses to habitat loss have outweighed positive responses to climate warming. Half of the species that were mobile and habitat generalists increased their distribution sites over this period (consistent with a climate explanation), whereas the other generalists and 89% of the habitat specialists declined in distribution size (consistent with habitat limitation). Changes in population abundances closely matched changes in distributions. The dual forces of habitat modification and climate change are likely to cause specialists to decline, leaving biological communities with reduced numbers of species and dominated by mobile and widespread habitat generalists.

Ecological and evolutionary processes at expanding range margins

Many animals are regarded as relatively sedentary and specialized in marginal parts of their geographical distributions. They are expected to be slow at colonizing new habitats. Despite this, the cool margins of many species' distributions have expanded rapidly in association with recent climate warming. We examined four insect species that have expanded their geographical ranges in Britain over the past 20 years. Here we report that two butterfly species have increased the variety of habitat types that they can colonize, and that two bush cricket species show increased fractions of longer-winged (dispersive) individuals in recently founded populations. Both ecological and evolutionary processes are probably responsible for these changes. Increased habitat breadth and dispersal tendencies have resulted in about 3- to 15-fold increases in expansion rates, allowing these insects to cross habitat disjunctions that would have represented major or complete barriers to dispersal before the expansions started. The emergence of dispersive phenotypes will increase the speed at which species invade new environments, and probably underlies the responses of many species to both past and future climate change.

Fourier analysis of facial profiles of young twins

Twins studies provide a powerful approach to determining the relative contribution of genetics and environment to observed variation. Such studies assume trait differences in monozygous (MZ) twins are due to environmental factors and those in dizygous (DZ) twins are due to both genetic and environmental factors. This study quantitated facial profiles of twins using Fourier equations, determining their value in profile analysis and the assessment of the genetic contribution to facial shape. Standardized profile slide photographs of 79 pairs of 4-6 year-old twins (37 MZ pairs, 42 DZ pairs) were scanned and x and y coordinates were extracted from each profile using sellion and Camper's plane as references. The coordinates were subjected to Fourier analysis and the normalised vertex projection coefficients were studied. The means of the differences between coefficients for MZ co-twins did not differ significantly from that of DZ co-twins, although the DZ group showed higher mean differences in the higher harmonics. Subjective examination of superimposed reconstructions showed wider variation between DZ co-twins than MZ co-twins. Correct classification of twins by discriminant function analysis using Fourier coefficients was similar for both groups (MZ: 70.3%; DZ: 73.8%). Fourier analysis could quantitate facial profiles of young children and differentiate some details, but was unable to discriminate between genetic and environmental influences, and any possible interactions between these influences, on their overall facial profiles at this developmental stage.

Non-random dispersal in the butterfly Maniola jurtina: implications for metapopulation models

The dispersal patterns of animals are important in metapopulation ecology because they affect the dynamics and survival of populations. Theoretical models assume random dispersal but little is known in practice about the dispersal behaviour of individual animals or the strategy by which dispersers locate distant habitat patches. In the present study, we released individual meadow brown butterflies (Maniola jurtina) in a non-habitat and investigated their ability to return to a suitable habitat. The results provided three reasons for supposing that meadow brown butterflies do not seek habitat by means of random flight. First, when released within the range of their normal dispersal distances, the butterflies orientated towards suitable habitat at a higher rate than expected at random. Second, when released at larger distances from their habitat, they used a non-random, systematic, search strategy in which they flew in loops around the release point and returned periodically to it. Third, butterflies returned to a familiar habitat patch rather than a non-familiar one when given a choice. If dispersers actively orientate towards or search systematically for distant habitat, this may be problematic for existing metapopulation models, including models of the evolution of dispersal rates in metapopulations.

Lotka's law and productivity index of authors in a scientific journal

Lotka's law of scientific productivity is a bibliometric example: the number of authors against the number of contributions made by the authors was plotted on a logarithmic scale. The points were closely scattered around a straight line having a slope of -2. The purpose of this study was to apply information technology to real-world data and to quantify the extent of the bibliometric regularity that exists in the literature of dental science. We have analyzed the productivity index of authors (PI) in a scientific journal (Journal of American Dental Association). Details of a total of 4,088 papers published between 1966 and 1995 were extracted electronically from MEDLINE. The total number of authors was 5,589, responsible for 8,569 authorships. Only 0.8% of the authors presented a PI > = 1 (large producers), and 78.1% a PI = 0 (occasional authors). The number of authors publishing N papers was 1/N2.64 of those publishing one paper. The result suggested that repeated publications in the Journal were more difficult than those predicted by Lotka (1/N2).

Regional variations in cortical modeling in the femoral mid-shaft: sex and age differences

Modern lifestyle changes may result in site-specific alterations in the skeleton. Our aim was to determine sex and age differences in regional geometry at the mid-femur. Complete cross sections from 113 individuals aged 20-97 years from a modern Australian population were obtained. A further subsample of 24, in whom the precise orientation of specimens was known, was subsequently collected. Microradiographs were made of 100-microm sections and the bone was analyzed using image processing software (Optimas, Media Cybernetics). The periosteal boundary was extracted automatically and the centroid of the periosteal outline was calculated. Fourier shape analysis was used to delineate the endocortical surface. Radial and cortical widths in each quadrant were determined. The posterior was identified by the linea aspera, and the medial and lateral were indistinguishable and therefore grouped together. For analysis, the entire sample was divided into three groups: young (20-40 years), middle (41-60 years), and old (61+ years). Raw and height-normalized values were analyzed with SPSS using t-tests, analysis of variance, and Tukey's honestly significant difference (HSD) tests. The results show that with age the femoral mid-shaft in both sexes becomes larger and more circular, with a slight shift towards the anterior. Apposition is least on the posterior and resorption greatest on the anterior, the latter being particularly evident in postmenopausal females. The greatest sex differences are seen in the middle years, lessening again in the old. We conclude that differential circumferential modeling in response to functional and postural changes occurs in both sexes with age.

Determination of age at death using combined morphology and histology of the femur

Bone is characterised by age-related morphological and histological changes. We have previously established an automated method of recording bone morphometry and histology from entire transverse sections of cortical bone. Our aim was to determine whether data acquired using this automated system were useful in the prediction of age. Ninety-six specimens of human femoral middiaphysis were studied from subjects aged 21-92 y. Equations predicting specimen age were constructed using macroscopic data (total subperiosteal area (TSPA), periosteal perimeter (PP), endosteal perimeter (EP), cortical bone area (CA) and moments of area) and microscopic data (the number, size and diversity of pores and intracortical porosity) together with sex, height and weight. Both TSPA and PP were independent predictors of age but the number of pores was not a significant predictor of age in any equation. The age predicted by these equations was inaccurate by more than 8 y in over half the subjects. We conclude that we could not predict age at a clinically acceptable level using data from our automated system. This most likely reflects an insensitivity to regional age-related changes in bone histology because we recorded data from each entire cortex. Automated bone measurement according to cortical region might be more useful in the prediction of age. The inclusion of TSPA together with PP as independent predictors of age raises the possibility that a future measure of periosteal shape at the femoral diaphysis could also be helpful in the prediction of age. The accuracy reached with the relatively simple methods described here is sufficient to encourage the development of image-analysis systems for the automatic detection of more complex features.

A new imaging technique for measuring the surface strains applied to dentine

OBJECTIVES

To investigate possible variation in directional material properties of dentine in relationship to tubule orientation using a new optical imaging technique.

METHOD

The optical imaging technique records photometrically a grid pattern formed by using a transmission electron microscope grid as a template on the polished surface of the dentine. The grid pattern is silhouetted onto the sample surface using standard techniques. Compression (c) and diametral compression (dc) tests were undertaken using a servo hydraulic testing machine (MTS model 810) acting on rectangular blocks of dentine with dimensions 1.5 x 1.0 x 1.0 mm (for c) and cylindrical samples with dimensions 2.1 mm in diameter and 1-1.5 mm thick (for dc), respectively. The samples were cut using a diamond wheel and miniature lathe and the cut surfaces polished. Images due to a changing load profile were captured and stored as digitised files on a computer for later analysis. The precision is mainly determined by the pixel resolution of the charged-coupled device camera.

RESULTS

Preliminary results show the value of elastic modulus of dentine (10.4 +/- 2.9 GPa) to be similar to those previously reported in the literature. Very small localised strains at the surface of a sample can be observed qualitatively and measured quantitatively by reference to the line spacing (approximately 85 microns). Maximum strength varied with tubule orientation and (compressive/tensile) stress.

CONCLUSION

Very small samples of dentine may be investigated for strain in more than one direction using the imaging technique described. These results may be more appropriate for finding relative directional change rather than obtaining the elastic properties of the dentine.

Dispersal and extinction in fragmented landscapes

Evolutionary and population dynamics models suggest that the migration rate will affect the probability of survival in fragmented landscapes. Using data for butterfly species in the fragmented British landscape and in immediately adjoining areas of the European continent, this paper shows that species of intermediate mobility have declined most, followed by those of low mobility, whereas high-mobility species are generally surviving well. Compared to the more sedentary species, species of intermediate mobility require relatively large areas where they breed at slightly lower local densities. Intermediate mobility species have probably fared badly through a combination of metapopulation (extinction and colonization) dynamics and the mortality of migrating individuals which fail to find new habitats in fragmented landscapes. Habitat fragmentation is likely to result in the non-random extinction of populations and species characterized by different levels of dispersal, although the details are likely to depend on the taxa, habitats and regions considered.

Lotka's law and the pattern of scientific productivity in the dental science literature

Statistical regularities can be observed in many natural and social phenomena. From empirical data on the authorship of scientific papers, Lotka deduced an inverse-square law: the number of authors publishing n papers is 1/n2 of those publishing one paper. The general type for the relation (1/n(c)) has a wide range of applicability to a variety of phenomena. This study examined, by means of bibliometric tools, whether Lotka's law could be applied to the literature of dental science. Data came from 20 leading dental science journals, as reported in Journal Citation Reports. The search was performed with a programme developed using Visual Basic for Applications, which counted the number of authors and analysed their contributions to the literature. Authorship for all contributions, as reported in Medline, was compiled for each of these 20 journals for the last 25 years, 1971 through 1995. The total number of authors was 43,796, responsible for 124,556 authorships. The journals published in countries other than the USA exhibited higher degrees of author concentration. The dental science literature conformed very well to Lotka's model with c = 1.95.

Crystallization and preliminary X-ray crystallographic studies of RepDC, a hybrid rolling-circle plasmid replication initiator protein

The hybrid plasmid-replication initiator protein RepDC, which is a fusion of the catalytic fragment of the RepD protein and the DNA-binding fragment of the RepC protein from Staphylococcus aureus, has been successfully crystallized and X-ray data to 3.5 A have been collected on a synchrotron radiation source. Crystals belong to space group I4132 with unit-cell dimensions a = b = c = 165.1 A. The crystals are estimated to contain one protein monomer per asymmetric unit, with 55% solvent content.

Bone image segmentation

Characteristics of microscopic structures in bone cross sections carry essential clues in age determination in forensic science and in the study of age-related bone developments and bone diseases. Analysis of bone cross sections represents a major area of research in bone biology. However, traditional approaches in bone biology have relied primarily on manual processes with very limited number of bone samples. As a consequence, it is difficult to reach reliable and consistent conclusions. In this paper we present an image processing system that uses microstructural and relational knowledge present in the bone cross section for bone image segmentation. This system automates the bone image analysis process and is able to produce reliable results based on quantitative measurements from a large number of bone images. As a result, using large databases of bone images to study the correlation between bone structural features and age-related bone developments becomes feasible.

An automated analysis of intracortical porosity in human femoral bone across age

The matrix of human cortical bone is arranged around a network of vascular spaces (hereafter referred to as "pores"). Our aim was to investigate age-related differences in human cortical porosity (total pore area divided by cortical bone area), pore size and number, and surface to volume ratios, while adjusting for sex, height, and weight. Ninety-six specimens of entire transverse sections of human femoral diaphysis, from subjects aged 21-92 years, were examined. We used our established automated image acquisition and analysis system which measures pores from entire sections of multiple specimens of bone. Over 400,000 pores were recorded. Results showed a greater porosity in older bone (p < 0.01) but marked variation in porosity for any given age. The cohort median, of the specimen medians, of pore cross-sectional area was 2050 microns 2. Older specimens did not have more pores than younger specimens but had a greater proportion of larger pores (p < 0.05) and greater intraspecimen variation in pore size (p < 0.001). The pore surface to bone matrix volume ratio was a median 2.3 mm2/mm3. This varied more than 4-fold between individuals but did not relate to age. No simple relationships were found between any of the measured parameters and either sex, height, or weight, even after adjustment for age. We conclude that the greater porosity in older specimens is due to greater pore size rather than a larger number of pores. Age, however, explains little of the inter-individual variation in the parameters studied.

Plasmid replication initiator protein RepD increases the processivity of PcrA DNA helicase

The replication initiator protein RepD encoded by the Staphylococcus chloramphenicol resistance plasmid pC221 stimulates the helicase activity of the Bacillus stearothermophilus PcrA DNA helicase in vitro. This stimulatory effect seems to be specific for PcrA and differs from the stimulatory effect of the Escherichia coli ribosomal protein L3. Whereas L3 stimulates the PcrA helicase activity by promoting co-operative PcrA binding onto its DNA substrate, RepD stimulates the PcrA helicase activity by increasing the processivity of the enzyme and enables PcrA to displace DNA from a nicked substrate. The implication of these results is that PcrA is the helicase recruited into the replisome by RepD during rolling circle replication of plasmids of the pT181 family.

Bone size and mechanics at the femoral diaphysis across age and sex

The reasons for the increase in fracture rates with age are not fully understood. It is known that there is a decrease in bone mass with a presumed loss of strength. This decrease may possibly be compensated for by changes in cross-sectional geometry. Previous studies, which have been limited by lack of information on subjects' heights and weights, were not able to resolve this issue. In this study, measurements of cross-sectional geometry (area and second moments of area) from 107 specimens of human femoral diaphysis from subjects aged 21-92 years were analysed. Mathematical models of the variation in bone geometry with age were developed. These models included the effects of sex, height and weight. Values of parameters from these models were then used in a biomechanical analysis of the static stresses at the mid-shaft of the femur. Results indicate that although there was a reduction in cortical area in old age, bone tissue was redistributed so that neither bending stresses in the coronal plane nor torsional stresses were higher in old age than in young adulthood. An additional finding was that at any age women had smaller bones, less cortical bone area and higher bone stresses than men. This finding may have some bearing on the higher fracture incidence seen in older women.

Age-related changes in cortical porosity of the midshaft of the human femur

Complete cross-sections from the femoral midshaft of 180 individuals of known height and weight, aged 21-97 y, from a modern Australian population were examined using automatic video image analysis to quantify total subperiosteal porosity (TSPP). More specifically, the aim was to investigate whether age changes were similar in both sexes in (1) total subperiosteal area (TSPA), cortical area (CA) and medullary area (MA), (2) intracortical porosity (ICP), and (3) the respective contributions to TSPP made by MA and intracortical void area (ICVA). Our findings indicated that both sexes showed a significantly greater height normalised TSPA in the 70s as compared with the 20s. Males had consistently larger bones with a greater height normalised CA. In both sexes CA showed a tendency to increase till the 7th decade and then to decline, more so in females. MA approximately trebled in females and doubled in males over the age range studied. Although ICP also increased, from 4-6% in young adults to over 9% in the elderly, it showed a significant difference between the sexes only in the 3rd decade, being greater in males at this stage. By contrast, TSPP became significantly greater in females (from that recorded in the 3rd decade) by the time they reached the 50s, while in males this did not occur till the 80s. It increased from approximately 25% in young adults of both sexes to approximately 50% in females and approximately 37% in males in their 80s. However, in the elderly there was great variability in both sexes in the appearance of bones from individuals of similar chronological age. Some bones differed little from those in younger subjects, others showed greatly increased ICP, still others displayed reduced cortical widths with low ICP. The femoral midshaft resembles other skeletal sites in that age changes in TSPP are more marked in females than males.

Interlaboratory variation in oxygen tension measurement by Eppendorf "Histograph" and comparison with hypoxic marker

BACKGROUND AND OBJECTIVES

The median of pO2 values in tumor measured by Eppendorf "Histograph" with a needle-type electrode has been used as a prognostic indicator in cancer patients. However, it is not established that a pretreatment measured pO2 value can be used as a universal predictor of local control probability, because the variation in pO2 values, especially in hypoxic tissue, among institutes may not allow comparison of measured "absolute pO2 values." The purpose of this study was to examine the variation in oxygen tension measurement by Eppendorf "Histograph" among six laboratories using a single batch of mice and tumors and the same detailed protocol. These results were also compared to the immunohistochemical staining of 2-nitromidazole adducts.

METHODS

C3H mice bearing FSaII murine fibrosarcoma subcutaneously were shipped to all laboratories, and the oxygen status in tumors and in normal subcutis was examined using Eppendorf "Histograph" and immunohistochemical hypoxic marker.

RESULTS

All laboratories showed that the FSaII tumor was hypoxic with at least 77% of measured points under 10 mmHg in pO2 and with a median pO2 value less than that of normal subcutis. These results were further confirmed immunohistochemically. These findings are interpreted as evidence that the pO2 values measured by Eppendorf "Histograph" can be useful. However, the median values of tumor pO2 varied from 1.5 mmHg to 5.6 mmHg among the laboratories, and pO2 of normal subcutis also varied from 28 mmHg to 38 mmHg. There were also significant differences in hypoxic fraction, defined as the fraction under a given oxygen partial pressure (i.e., under 2.5, 5, or 10 mmHg), among institutes.

CONCLUSIONS

Caution needs to be exercised in using the absolute, median, or distribution of pO2 values measured by the Eppendorf "Histograph" to compare the data between laboratories or to predict the radiation response in an individual subject.

Evaluation of sexual misconduct complaints: the Oregon Board of Medical Examiners, 1991 to 1995

OBJECTIVE

In 1991 the Oregon Board of Medical Examiners initiated a separate category for the complaint of sexual misconduct. Investigated complaints of sexual misconduct brought to the Oregon Board of Medical Examiners were analyzed for the years 1991 to 1995 to serve as a baseline. Comparison was made to the Federation of State Medical Boards sexual misconduct data for 1991 and 1992.

STUDY DESIGN

One hundred complaints brought against 80 licensees were evaluated by practitioner's degree, age group, sex, specialty, and disposition of complaints for the years 1991 to 1995. The allegations were classified into behavior categories of sexual impropriety, sexual transgression, and sexual violations.

RESULTS

Sexual misconduct was the allegation in 5.9% of the complaints investigated for the study period. Oregon had more sexual misconduct complaints than the average reported to the Federation of State Medical Boards for the years 1991 and 1992. Most (72%) complaints came from the patients or their families. Two female physicians (2.4%) had sexual boundary complaints. Sexual misconduct complaints increased by a risk ratio of 1.44 with advancing age by decades. Allegations classified into behavior categories according to severity revealed 39% sexual impropriety, 31% sexual transgression, and 30% sexual violation. Reportable disciplinary actions occurred only with multiple allegations of sexual impropriety (6.5%) and for sexual transgression (27%) whereas sexual violation allegations often had one complainant but there were 54% reportable disciplinary actions. Family practice, obstetrics and gynecology, and psychiatry had the highest incidence of sexual misconduct complaints whereas psychiatry and obstetrics and gynecology had the highest incidence of reportable disciplinary actions. Twenty-five percent of the closed cases resulted in reportable disciplinary actions. This analysis is discussed in relationship to legal and ethical issues and the goal of zero tolerance.

CONCLUSIONS

Oregon has a higher percentage of sexual misconduct complaints than the average for 42 states reporting to the Federation of State Medical Boards for the years 1991 and 1992. Analysis of the Oregon Board's experience for the study years will provide a baseline for future evaluation and as an educational resource for the Oregon Board of Medical Examiners and professional and specialty societies. Ethical standards, the reporting and investigative processes, and the legal framework are in place and lessen the incidence of sexual misconduct and work toward zero tolerance.

Quantification of ethnic differences in facial profile

The concept of facial aesthetics is becoming increasingly important and with the expanding application of orthodontic, orthognathic, plastic and reconstructive techniques to patients from continually diversifying ethnic backgrounds, it is timely that more elaborate methods for the evaluation of facial form are adopted. The aim of the present study was to further investigate the use of Fourier shape analysis in the quantification of facial profile and to investigate differences between racial groups. One hundred and twenty-two undergraduate dental students were photographed and surveyed for information pertaining to ethnic origin. Student's t-tests revealed significant differences (p < 0.05) in higher-order (fourth- and above) Fourier harmonics between male and female profiles, as well as between intervention and non-intervention groups. A comparison of multiple means test revealed significant differences (p < 0.05) in the third-order Fourier harmonic (vertex projection) between the Asian group and three other groups--Anglo-Celtic, Eastern European and Western European. Differences correlated with convexity in the lower third of the face, which was demonstrated by Fourier reconstruction.

Age trends in remodeling of the femoral midshaft differ between the sexes

Cross-sectional area properties of the femoral midshaft from 203 individuals of known height and weight. 1-97 years of age, from a modern Australian population were quantified using automatic video image analysis. The aim of this study, taking height and weight into account, was to determine whether (a) age trends in remodeling differ between the sexes, (b) men are better able to compensate for bone loss with age, and (c) this protective mechanism is carried through into old age. Our findings indicated that during adulthood there are distinct gender differences in femoral remodeling. From around the third to the seventh decade, men showed a fairly uniform increase in subperiosteal area, polar moment of inertia, and medullary area. Women displayed two distinct phases during this period: relative stability until around the menopause and then a marked increase in all of the above variables. In old age, gender differences diminished, both sexes showing reduced periosteal apposition and increased endosteal resorption. The resultant decline in cortical area of approximately 4% in men and 15% in women from the third to the eighth decade was significant only in women. For a given height, men had larger, stiffer femoral shafts with a greater cortical width and area and maintained this advantage into old age. Diaphyseal bone was not immune from age-related changes affecting other skeletal sites: however, due to compensatory remodeling, which was particularly evident in men, this was not reflected in increased fracture rates.

Regional fat placement in physically fit males and changes with weight loss

The abdomen is the principal site of fat deposition in men, and because abdominal fat is readily mobilized during exercise, the relative proportion of fat in the abdominal site may negatively correlate with the amount of regular physical activity, and even with physical fitness. This study presents data for regional fatness in 165 fit young men (U.S. Army Ranger candidates; initial body fat = 14.7 +/- 4.7%) assessed by dual-energy x-ray absorptiometry (DEXA), and for relative changes occurring following a 13% weight loss produced by a 1000 kcal.d-1 energy deficit over 8 wk. Fat-free mass was constant across quintiles of percent body fat; only fat mass was different (16.2 +/- 2.2 kg and 6.0 +/- 1.4 kg at upper and lower quintiles, respectively). Truncal fat accounted for about 41% of total body fat in all quintiles; only the proportion of fat distributed to the arms was significantly higher in the fattest quintiles of men. Among a group of less intensely trained soldiers with the same average fatness as the highest quintile of Ranger students (20%), relative fat distribution to the trunk approached 50% of the total fat. Following weight loss, Ranger students lost half of the fat in all regions assessed (legs, arms, and trunk). The only significant association between regional losses and initial fatness was a greater proportion of fat lost from the arms in the fattest Rangers. These data suggest a "fit fat" distribution in active young men in which fat remains in the arms and legs until extreme weight loss occurs and the metabolically more active abdominal fat approaches depletion.

Transient perfusion and radiosensitizing effect after nicotinamide, carbogen, and perflubron emulsion administration

In order to improve the effect of radiation on tumour response, nicotinamide, perflubron emulsion and carbogen were administered which act on both diffusion limited hypoxia and intermittent perfusion limited hypoxia. These treatments were used in different combinations. The maximal radiosensitizing effect was found with the combination of the three treatments. The aim of this study was to use a double staining method (Hoechst 33342 and DiOC7(3) to evaluate the influence of nicotinamide, perflubron emulsion and carbogen on transient perfusion in three tumour cell lines transplanted onto nude mice: one rodent (EMT6), two human (HRT18, a rectal adenocarcinoma; and Na11+, a melanoma). For untreated groups, the percentage of closed and mismatched vessels depended on the tumour cell line. Carbogen alone or carbogen plus perflubron emulsion decreased the number of mismatched and closed vessels only for the two human cell lines. Nicotinamide was effective in decreasing the percentage of mismatched and closed vessels only for the melanoma cell line. The combination of nicotinamide, carbogen and perflubron emulsion was the most effective at decreasing both percentage of mismatched and closed vessels in all three tumours studies. This combination was also the most effective at enhancing the radiation response in all three tumours.

Influence of melanin on pO2 measurement in vitro and in vivo

In a previous study an apparent discrepancy was found between the radiobiological hypoxic fraction of tumours and the tumour oxygenation: the lowest percentage of low pO2 values was observed in the most hypoxic tumour, a heavily pigmented melanoma Na11+. This report describes a similar study with two other less pigmented melanomas. The influence of melanin on pO2 readings was also studied using synthetic melanin and L-tyrosine. Tumour oxygenation was measured using the KIMOC 6650 histograph, apparent pO2 was also measured in the calibration chamber in a buffer containing melanin or L-Tyr at three pHs (6.5, 7.0, 7.5) and bubbled with three different oxygen concentrations (0.2, 2.0, 20.9%). The proportion of hypoxic cells, measured by an in vivo/in vitro colony assay, was 58% for Na11+, 30% for Be11 and 51% for Ma11 tumours. The melanin content (microgram/10(6) cells) was 6.5 (Na11+), 2.0 (Be11), and 4.3 (Ma11). The percentages of radiobiologically hypoxic cells and low pO2 reading values (<2 mmHg) were inversely correlated, contrary to what was expected. In buffer, the pO2 values increased significantly with the melanin concentration: the lower the oxygen concentration, the greater was the increase in pO2. The pO2 readings values increased to a lesser extent with L-Tyr concentration. These results indicate that clinical determination of pO2 in melanoma tumours requires careful attention.

Bone feature analysis using image processing techniques

In order to establish the correlation between bone structure and age, and information about age-related bone changes, it is necessary to study microstructural features of human bone. Traditionally, in bone biology and forensic science, the analysis if bone cross-sections has been carried out manually. Such a process is known to be slow, inefficient and prone to human error. Consequently, the results obtained so far have been unreliable. In this paper we present a new approach to quantitative analysis of cross-sections of human bones using digital image processing techniques. We demonstrate that such a system is able to extract various bone features consistently and is capable of providing more reliable data and statistics for bones. Consequently, we will be able to correlate features of bone microstructure with age and possibly also with age related bone diseases such as osteoporosis. The development of knowledge-based computer vision-systems for automated bone image analysis can now be considered feasible.

Determination of sequence specificity between a plasmid replication initiator protein and the origin of replication

Staphylococcal plasmids of the pT181 family replicate by a rolling circle mechanism, requiring the activities of a plasmid-specified Rep protein. The initiation event involves site-specific phosphodiester bond cleavage by Rep within the replication origin, ori. In vitro the Rep proteins also display type-I topoisomerase activity specific for this plasmid family. Although the single site of bond cleavage, ICR II, is conserved among all members of the pT181 family, the plasmid-specific Rep proteins are able to discriminate between family members in vivo, initiating replication only from the cognate origin. The basis of such specificity is believed to be due to a non-covalent binding interaction between Rep and a DNA sequence adjacent to the site of phosphodiester bond cleavage. Using the RepD protein specified by plasmid pC221, we present data for the physical parameters of RepD:oriD complex formation. Quantification of the relative strengths of the non-covalent interactions for different but related ori target sequences, measured by gel mobility shift experiments, has yielded data that are in accord with the known specificity of the protein in vivo. Oligonucleotide competition experiments demonstrate that this interaction is indeed attributable to the specificity determinant, ICR III. Protein-DNA crosslinking methods show that a carboxyl-terminal proteolytic fragment of RepD makes a specific interaction with the ICR III region of its cognate replication origin. Analysis of topoisomerase rates indicates that the interaction between ICR III and the carboxyl terminus of the protein is required before a productive interaction, namely the phosphodiester bond cleavage at the ICR II, can occur.

A morphometric study of the cortex of the human femur from early childhood to advanced old age

One hundred and ninety-five mid-shaft femoral bone samples were collected at the Victorian Institute of Forensic Pathology, Melbourne, Australia. These samples came from individuals aged 1-97 years, who had dies unexpectedly and were considered healthy immediately before death. From the samples, transverse sections 100-200 micronM thick were cut on a sawing microtome. Three groups of sections [from persons aged 19-21 (n = 9), 39-41 (n = 9), and 59-61 years (n = 9) at death] were adjusted to a thickness of 100 +/- 5 microns by hand-lapping and microradiographs were taken of these sections. Automatic image analysis methods were used to measure the area and perimeter of the femoral cortex for all 195 sections. Additionally, the number and areas of all holes within the cortex were measured for those sections that were microradiographed. The results show that, even though the number of Haversian canals measured from the entire bone cortex changes with age, the spread of values at any given age makes these measurements of limited value for age determination. From this it may be inferred that all methods that rely, to any extent, upon measurements of this parameter are likely to be flawed.

Tumour oxygenation, radiosensitivity, and necrosis before and/or after nicotinamide, carbogen and perflubron emulsion administration

Hypoxia is one of the factors involved in tumour resistance to radiotherapy. One way to improve tumour oxygenation is to use oxygen carriers such as perflubron emulsion plus carbogen or vasoactive drugs such as nicotinamide. The perflubron emulsion and carbogen act mainly on hypoxia caused by limited diffusion of oxygen; nicotinamide acts mainly on acute hypoxia. The aim was to correlate radiosensitivity and pO2 measurements (computerized pO2 histograph) after nicotinamide, perflubron emulsion and carbogen administration, and to determine the role of necrosis in this correlation. Two human tumour xenografts (HRT18, Na11 +) and one rodent tumour (EMT6) were used. Clonogenic assays and pO2 measurements were performed under similar conditions. The radiosensitization and oxygenation levels increased with all treatments. The maximal effects were found with the combination of nicotinamide (1 g/kg), perflubron emulsion and carbogen. A correlation between the radiosensitization and the pO2 measurements was found for the three cell lines with a cut-off point of 10 mmHg. The presence of necrosis could explain the low pO2 (< 2 mmHg) found even when complete radiosensitization was observed.

Correlation between radiosensitivity, percentage hypoxic cells and pO2 measurements in one rodent and two human tumor xenografts

Computerized pO2 histography has been used to measure the intratumor pO2 in patients for the past few years, and there is now evidence that these tumors contain hypoxic cells. One of the major questions that remains to be answered is the relevance of such data to radiosensitivity. The present study looks for a correlation between intratumor pO2, the percentage of hypoxic cells in the tumor and the radiosensitization induced by carbogen and/or the oxygen carrier, perflubron emulsion. Two human tumor xenografts (HRT18, Na11+) and one rodent tumor (EMT6) were used. The radiosensitivity (clonogenic assay) and the oxygen tension (computerized pO2 histography) were measured. All experiments were performed under similar conditions. Carbogen increased tumor radiosensitivity; sensitization was greatest when 4 ml/kg perflubron emulsion was used in conjunction with carbogen. The pO2 distribution was shifted to higher pO2 values in the tumors whatever the treatment; the shift was greater for perflubron emulsion plus carbogen. The low pO2 values (< 0.4 kPa) were lost for the HRT18 cells. A correlation (EMT6, HRT18) or a link (Na11+) between the radiosensitization and the oxygen tension measurements was found for values below 1.07 or 1.33 kPa. A trend between the percentage of hypoxic cells and pO2 measurements was found taking into account pO2 measurements comprised between 0.27 and 0.67 kPa.

Nicotinamide and carbogen: relationship between pO2 and radiosensitivity in three tumour lines

The effects of carbogen breathing, nicotinamide injection and their combination on tumour radiosensitivity were correlated with changes in tumour O2 tension to determine the relationship between radiosensitivity and measured pO2. The radiosensitivity (in vivo-in vitro colony assay) and O2 tension (computerized pO2 histograph KIMOC 6650) of two human xenografted tumours (HRT18 and Na11+) and one murine tumour (EMT6) were measured under similar experimental conditions. A single dose of radiation was delivered (8 Gy for HRT18 and Na11+, 12 Gy for EMT6). Carbogen breathing, nicotinamide injection, and their combination all significantly increased radiosensitivity in the three cell lines (p < 0.05); the most efficient treatment was carbogen plus nicotinamide. The radiosensitization was optimum for EMT6 and Na11+. Mean and median pO2 increased with all three treatments, except for carbogen breathing in EMT6. Carbogen breathing had little effect on the proportion of low pO2 values, but induced pO2 values > 30 mmHg in all three tumour lines. Nicotinamide decreased the proportion of low pO2 values. This effect is larger with the combination carbogen plus nicotinamide. Almost all pO2 values < 2.5 mmHg were eliminated for HRT18 and EMT6. The relationship between radiosensitization and pO2 was significant when pO2 was expressed as the percentage of values below 7, 8, 9 and 10 mmHg for the three lines.

Controlled high-level expression of the lon gene of Escherichia coli allows overproduction of Lon protease

Lon protease from Escherichia coli is an ATP-dependent protease which plays important roles in regulating the levels of specific proteins and in eliminating abnormal proteins. A major problem of working with Lon protease, the inability to substantially overproduce the enzyme, has been overcome by placing the lon gene under the control of an inducible trp promoter within a copy-number-controllable plasmid. Induction resulted in higher levels of production of the protease (approximately 100 micrograms/ml of cell culture) than were previously possible. The enzyme has been purified to apparent homogeneity and shown to possess the characteristic ATP-dependent proteolytic activity. Sequence verification during DNA manipulations revealed differences from two previously published sequences for the lon gene.

Nutrient balance and energy expenditure during ad libitum feeding of high-fat and high-carbohydrate diets in humans

To study the influence of diet composition on regulation of body weight, we fed 21 weight-stable subjects (11 lean, 10 obese) high-carbohydrate (HC) and high-fat (HF) diets for 1 wk each. Although diet composition was fixed, total energy intake was unrestricted. Subjects had a higher energy intake on the HF (11,039 +/- 2700 kJ/d) than on the HC (10,672 +/- 2617 kJ/d) diet (P less than 0.05), but energy expenditure was not different between diets. On day 7 of the HC diet, carbohydrate (CHO) oxidation was significantly related to CHO intake with the slope of the regression line 0.99, suggesting that overall CHO balance was near zero. However, the slope of the regression line was greater for obese than for lean subjects. On day 7 of the HF diet, fat oxidation was significantly related to fat intake but the slope of the line was 0.50, suggesting that overall fat balance was positive. However, this relationship was due entirely to lean subjects, with obese subjects showing no relationship between fat intake and oxidation.