Predicting the external formation of callus tissues in oblique bone fractures: idealised and clinical case studies.

It is proposed that the external asymmetric formation of callus tissues that forms naturally about an oblique bone fracture can be predicted computationally. We present an analysis of callus formation for two cases of bone fracture healing: idealised and subject-specific oblique bone fractures. Plane strain finite element (FE) models of the oblique fractures were generated to calculate the compressive strain field experienced by the immature callus tissues due to interfragmentary motion. The external formations of the calluses were phenomenologically simulated using an optimisation style algorithm that iteratively removes tissue that experiences low strains from a large domain. The resultant simulated spatial formation of the healing tissues for the two bone fracture cases showed that the calluses tended to form at an angle equivalent to the angle of the oblique fracture line. The computational results qualitatively correlated with the callus formations found in vivo. Consequently, the proposed methods show potential as a means of predicting callus formation in pre-clinical testing.

Predicting the external formation of a bone fracture callus: an optimisation approach.

The formation of a fracture callus in vivo tends to form in a structurally efficient manner distributing tissues where mechanical stimulus persists. Therefore, it is proposed that the formation of a fracture callus can be modelled in silico by way of an optimisation algorithm. This was tested by generating a finite element model of a transversal bone fracture embedded in a large tissue domain which was subjected to axial, bending and torsional loads. It was found that the relative fragment motion induced a compressive strain field in the early callus tissue which could be utilised to simulate the formation of external callus structures through an iterative optimisation process of tissue maintenance and removal. The phenomenological results showed a high level of congruence with in vivo healing patterns found in the literature. Consequently, the proposed strategy shows potential as a means of predicting spatial bone healing phenomena for pre-clinical testing.

The role of interfragmentary strain on the rate of bone healing-a new interpretation and mathematical model.

It is postulated that there is a causal relationship between mechanical stimulus and the rate of bone healing post fracture. However, despite numerous experimental studies in the literature, no quantifiable relationship has been proposed. It is hypothesized in the present study that the temporal rate of bone fracture healing, measured in terms of callus stiffening per week, can be described mathematically based on the relative motions between bone fragments at the initial stage of the healing process. To test this, a comparative reanalysis of experimental data found in the literature was conducted. These individual data sets described a relationship between an initial intermittently applied peak interfragmentary strain and the change in interfragmentary motion or the increase in callus stiffness over time. The data were converted into a relative increase in stiffness, which normalised the results and reduced inter-study variability. The rates of healing for the various initial strains were compared, and based on this a mathematical phenomenological model was derived. Error analyses were then performed, which showed a high level of congruence between the in-vivo and simulated rates of healing. The results of the comparative analysis revealed that there is a positive correlation between the rate of callus stiffening and interfragmentary strain. Finally, the proposed model has shown for the first time that a quantifiable cause-and-effect relationship exists between the rate of bone healing and mechanical stimulus.

Issues in therapy with gay and lesbian couples.

Gay and lesbian couples differ from heterosexual couples in ways that may have implications for therapy. Until recently, research in homosexuality dealt only with "curing" it. Since the 1980s, however, psychotherapy with gay and lesbian couples has received more attention. The literature in this area is seldom criticized or questioned; thus, much of the most recent research in the area is founded on assumptions about gay and lesbian couples that have never been tested empirically. This article critically reviews the literature concerning differences among gay, lesbian, and heterosexual couples and presents the therapeutic implications of these differences.

Assistive devices: utilization by children.

The use of assistive devices by children has become widespread and has been supported financially by insurance carriers and governments. However, there has been little evaluation of the utilization of these devices. To determine utilization of, satisfaction with, and perceived value of the aid, an independent evaluator contacted 502 families who had used a provincial government funding program to obtain an assistive device. High levels of use, satisfaction, and perceived value were reported, indicating that a decentralized funding program can provide aids effectively.

Direct radioimmunoassay of estradiol-17 beta in defatted bovine milk.

A radioimmunoassay was developed for rapid determination of estradiol-17 beta concentrations in unextracted defatted bovine milk. The assay was dependent on the use of a highly specific anti-estradiol-17 beta antiserum. Application of a formula to correct for the interference associated with individual milk samples and use of appropriate assay blanks facilitated interpolation on a buffer standard curve. The assay offered a high degree of sensitivity (0.6pg/ml milk) and a precision (within-assay coefficient of variation: 0.196; between-assay CV:0.191) comparable with contemporary extraction methods.

A spectrofluorometric investigation, using 1-anilino-naphthalene-8-sulphonate, of the interaction between washed bovine spermatozoa and seminal plasma or egg-yolk lipoprotein.

The dye 1-anilino-naphthalene-8-sulphonate (ANS) bound at 94.5 +/- 2.7 pmol per 10(6) spermatozoa (KD = 1.83 +/- 0.13 X 10(-5) M) and 7.30 +/- 0.17 pmol per mg seminal plasma protein (KD = 2.19 +/- 0.06 X 10(-5) M). Equilibration of excess ANS with a mixture of washed spermatozoa and seminal plasma resulted in a significant increase in fluorescence over that calculated by summation of the individual levels (P less than 0.05). A less pronounced but significant increase was seen when an egg-yolk lipoprotein, previously shown to have cryoprotective properties, was similarly added to washed spermatozoa (P less than 0.05). This increase in fluorescence was not reduced by washing spermatozoa--lipoprotein mixtures, suggesting that an interaction between the lipoprotein and the cell membrane had occurred.

The relationship between ATP content and motility of bovine spermatozoa.

The ATP content of bovine semen was measured using a bioluminescent technique. No ATP was detected in seminal plasma or diluent. The mean concentration of ATP (+/- sd) in ejaculated semen was 76.5+/-38.21 n moles ATP/10(8) spermatozoa and in diluted, frozen and thawed semen 10.00+/-4.74 n moles ATP/10(8) spermatozoa. The observed motilities of ejaculated and of diluted, frozen and thawed semen were linearly related to the ATP content r=0.652; p<0.01 and r=0.466; p<0.001 respectively). The mean ATP content and motility calculated for each bull were similarly related (r=0.857; p<0.02 and r=0.607; p<0.05). The technique shows promise in providing an objective measure of spermatozoan activity.

Development and size of the teeth of Macaca mulatta.

A cross-sectional sample of 151 skulls from Macaca mulatta of known age and similar rearing in U.S. Primate Centers was analyzed to determine age-related "norms" of stages of development and size of teeth. The stages of development from the follicle of a deciduous incisor in the fetus to completion of the root with apex closed of the permanent third molar were related to age. The age range observed for eruption of each tooth was noted and related to its stage of development. The crown of each erupted tooth was found to be completely developed, but growth of its root continued for a longer, indeterminate period. When a deciduous tooth was exfoliated, the crown of the permanent successor was found to be completed and root growth had begun. Measurements of both mesiodistal and faciolingual diameters and of crown length of the teeth in situ and of total length and root length on roentgenograms were examined for sexual dimorphism. The faciolingual diameter of the deciduous mandibular second incisor and of both second molars showed the greatest sexual dimorphism among both diameters of all deciduous teeth. The mesiodistal and faciolingual diameters of the mandibular premolars were found to be the best dimensions in discriminant functions for identifying sex in the absence of permanent canines.