Reproductive aging in Japanese quail, Coturnix japonica is associated with changes in central opioid receptors

Quantitative in vitro autoradiography was used to measure specific mu and delta opioid receptor densities in regions of the Japanese quail, Coturnix japonica, brain that regulates reproductive endocrine and behavioral responses to determine the possible involvement of the opioid system in reproductive decline seen during aging. Densities were measured in selected brain regions of young sexually active (YAM), young photoregressed (YPM), old reproductively senescent (OIM) male, young active (YF), and old senescent female (OF) Japanese quail. Medial and lateral septum (SM, SL), medial preoptic area (POM), and n. intercollicularis (ICo) were of particular interest for reproductive responses. Similar to previous observations, mu and delta opioid receptors showed differential distributions in the areas measured. Some age-related changes were observed, with lower SM mu receptor densities in aged males (OIM) than females or young males (YAM). Densities of mu receptors in the POM and in other areas examined did not vary with sex or age. Similarly, OIM males had lower densities of delta receptors in the SM than young males (YAM and YPM); POM delta receptor densities were also low in OIM males compared to the YPM males, and YAM males were intermediate. Interestingly, photoregressed males (YPM) had higher SL delta receptor densities than any other group. Thus there were age-related differences detected in mu receptor densities among groups in the SM of OIM relative to other groups; and the mu and delta receptor densities did not differ in females with brain region. Additionally for delta receptors specifically, YF and OF did not differ from OIM for any brain region and similarly had lower densities of delta receptors compared to YAM males. These data provide support for regional differences in opioid receptor distribution and for age- and sex-related differences in delta opioid receptor densities. The direction of change presents an interesting dichotomy in that, compared to young active males, delta opioid receptor densities increased with loss of reproductive function in the YPM, whereas receptor densities decreased in the OIM. Plasma androgen levels were relatively low in both these groups compared to the young active males. This observation suggests that there is an age-related loss in the ability of this receptor system to respond to circulating and centrally produced steroid hormones in the POM and in some septal regions, compared to young animals that are responding to environmental cues. Furthermore, these data support an active role of the opioid peptide system in the inhibition of the reproductive axis in photoregression.

Repeatability of a model for measuring multi-segment foot kinematics in children

This study used a previously tested foot model and adapted it for use with children. A number of variations on this adapted model were implemented and tested for repeatability and accuracy on 15 healthy children on three occasions. These included redefinition of the long axes of the tibia and forefoot, assessment of the flexibility of the forefoot and evaluation of the variability of the wand marker on the heel for both static and dynamic trials. It was found that variations on the model produced only minimal changes in repeatability, the only significant change being elimination of the wand marker on the heel in the static trial, which reduced between-day variability of hindfoot motion in the transverse plane. However, some differences were evident in the mean values for all variations. Based on these results, the most accurate and appropriate version of the model is proposed, and average kinematic curves are presented based on the measurements from 14 healthy children.

Hydrogen peroxide as an irrigation solution in arthroplasty – A potential contributing factor to the development of aseptic loosening

The reason for revision of primary total hip arthroplasty is quoted as aseptic loosening in 60.6% of cases between 1979 and 2003 in the Swedish National Hip Arthroplasty Registry. Much research effort has been directed toward enhancing the bone-cement interface of total joint arthroplasties, in an attempt to reduce this complication. Haemostatic agents have been popularized as effective means of retarding the development of potentially harmful debris interposition adjacent to, and blood lamination patterns within, the methylmethacrylate. Such agents include hydrogen peroxide (H(2)O(2)), local freezing saline, saline at room temperature and adrenaline solution. One main concern with the use of hydrogen peroxide is whether it affects the material properties of bone cement such that in the long term it contributes to aseptic loosening. This would have enormous clinical consequences. Preliminary studies indicate that porosity increases and that the tensile strength and yield stresses are reduced by up to a factor of 10 by contaminating samples with increasing concentrations of hydrogen peroxide. We postulate that the current use of hydrogen peroxide as an irrigation solution in arthroplasty contributes to the development of aseptic loosening.

Assessment of sub-division of plantar pressure measurement in children

Methods for the measurement of plantar pressure are poorly defined particularly when describing sub-sections of the plantar surface of the foot in the presence of deformity. The aim of this study was to assess foot pressure measurement in healthy children, using an automatic technique of sub-area definition that has the potential for objective evaluation of treatment of foot deformity. Twelve healthy children were examined on three occasions. Plantar pressure data were collected and time synchronised with force plate and stereophotogrammetric data. The footprint was divided into five sub-sections by using the position of the markers on the foot at mid-stance projected onto the pressure footprint. Repeatability for peak pressure and peak force was assessed. Automatic sub-area definition based on marker placement was found to be reliable in healthy children. A comparison of results revealed that peak vertical force was a more consistent measure than peak pressure for each of the five sub-areas. This suggests that force may be a more appropriate measurement for outcome studies.

Consequences of endocrine disrupting chemicals on reproductive endocrine function in birds: establishing reliable end points of exposure

It has been difficult to establish reliable indices of exposure to endocrine disrupting chemicals (EDCs) appropriate for a variety of avian species because of a vast array of reproductive strategies. Data from mammals, reptiles and fish provide insight on likely mechanisms of action for EDCs. However, many of the effects of EDCs are weaker than the actions of the native hormones, making it difficult to assess adverse effects in domestic and wild birds. It is clear that differential sensitivity to EDCs exists across species, due to the timing and mode of exposure, compound toxicity and age of the individual. Our studies on EDCs are conducted in the quail model system, with focus on reproductive endocrine, neuroendocrine and behavioral responses. Studies have included EDC exposure, either by egg injection or via diet. Results from egg injection studies showed the following: (1) estradiol administered by embryonic day 12 demasculinized male sexual behavior, altered hypothalamic neurotransmitters and reduced hen day production and fertility in a dose dependent fashion, (2) methoxychlor (MXC) or vinclozolin impaired male sexual behavior in adult quail and (3) DDE exposure impaired reproductive and immune related end points. Two-generation studies were conducted on Japanese and northern bobwhite quail with dietary methoxychlor (MXC) exposure (0, 5 and 10 ppm) beginning in adults (P1), continuing in their offspring (F1), with F2 offspring raised on control diet. MXC exposure impaired male sexual behavior, hypothalamic catecholamines and plasma steroid hormones. Moreover, MXC exposure had reproductive consequences observable at both the lower and higher doses of MXC in F1 and F2 generations. These data demonstrate that embryonic EDC exposure interferes with sexual differentiation of neural systems that direct reproduction.

Primary parental preoccupation: circuits, genes, and the crucial role of the environment

Parental caregiving includes a set of highly conserved behaviors and mental states that may reflect both an individual's genetic endowment and the early experience of being cared for as a child. This review first examines the mental and behavioral elements of early parental caregiving in humans. Second, we consider what is known about the neurobiological substrates of maternal behaviors in mammalian species including some limited human data. Third, we briefly review the evidence that specific genes encode proteins that are crucial for the development of the neural substrates that underlie specific features of maternal behavior. Fourth, we review the emerging literature on the "programming" role of the intrauterine environment and postnatal caregiving environment in shaping subsequent maternal behavior. We conclude that there are critical developmental windows during which the genetically determined microcircuitry of key limbic-hypothalamic-midbrain structures are susceptible to early environmental influences and that these influences powerfully shape an individual's responsivity to psychosocial stressors and their resiliency or vulnerability to various forms of human psychopathology later in life.

Dynamic foot movement in children treated for congenital talipes equinovarus

The aim of this study was to define objectively gait function in children with treated congenital talipes equinovarus (CTEV) and a good clinical result. The study also attempted an analysis of movement within the foot during gait. We compared 20 children with treated CTEV with 15 control subjects. Clinical assessment demonstrated good results from treatment. Three-dimensional gait analysis provided kinematic and kinetic data describing movement and moments at the joints of the lower limb during gait. A new method was used to study movement within the foot during gait. The data on gait showed significantly increased internal rotation of the foot during walking which was partially compensated for by external rotation at the hip. A mild foot drop and reduced plantar flexor power were also observed. Dorsiflexion at the midfoot was significantly increased, which probably compensated for reduced mobility at the hindfoot. Patients treated for CTEV with a good clinical result should be expected to have nearly normal gait and dynamic foot movement, but there may be residual intoeing, mild foot drop, loss of plantar flexor power with compensatory increased midfoot dorsiflexion and external hip rotation.

Effects of exogenous testosterone on testicular luteinizing hormone and follicle-stimulating hormone receptors during aging

During aging, the male Japanese quail exhibits a loss of fertility, increased morphological abnormalities in the testes, and a higher incidence of Sertoli cell tumors. Although there is a coincident loss of reproductive behavior, plasma androgen levels remain high until testicular regression occurs in association with senescence. The purpose of this study was to compare mean specific binding of chicken luteinizing hormone (LH) and follicle-stimulating hormone (FSH) as a measure of testicular receptors during identified stages during aging. Males were categorized according to age (young = 9 months, middle aged = 24 months, or old = 36+ months) and sexual behavior (active or inactive). Testicular samples were collected immediately after perfusion with 4% paraformaldehyde from the following groups: young active (n = 8), young photoregressed (n = 5), young photoregressed plus testosterone implant (n = 4), middle-aged active (n = 8), middle-aged inactive (n = 4), old inactive (n = 5), and old inactive plus testosterone implant (n = 6). A crude plasma membrane fraction was prepared from the testes of each bird and an aliquot deriving from 10 mg of testicular tissue was used for binding assay. Specific binding of labeled LH or FSH was expressed as percentage of total radioactive hormone. Results showed significant (P < 0.05) age-related decreases in both FSH and LH receptor numbers. The highest FSH binding was found in young and middle-aged active males, with low binding in old inactive males. Testicular LH binding decreased during aging, with a sharp decrease in middle-aged males, which was similar to old males. Testosterone implants weakly stimulated FSH and LH binding in old males. Both LH and FSH binding decreased in photoregressed young males. However, testosterone implants stimulated increased LH binding, but did not affect FSH binding in young photoregressed males. These results provide evidence for separate regulation of testicular LH and FSH receptors, with testosterone stimulation of LH receptor, but not FSH receptor number in young males. However, during aging there appears to be a loss of this response, potentially because of the reduced efficacy of testosterone stimulation, thereby implying a diminished capacity for response with aging.

Noncontact dipole effects on channel permeation. VI. 5F- and 6F-Trp gramicidin channel currents

Fluorination of peptide side chains has been shown to perturb gramicidin channel conductance without significantly changing the average side chain structure, which, it is hoped, will allow detailed analysis of electrostatic modulation of current flow. Here we report a 1312-point potassium current-voltage-concentration data set for homodimeric channels formed from gramicidin A (gA) or any of eight fluorinated Trp analogs in both lecithin and monoglyceride bilayers. We fit the data with a three-barrier, two-site, two-ion (3B2S) kinetic model. The fluorination-induced changes in the rate constants were constrained by the same factor in both lipids. The rate constant changes were converted to transition-state free-energy differences for comparison with previous electrostatic potential energy differences based on an ab initio force field. The model allowed a reasonably good fit (chi = 8.29 with 1271 degrees of freedom). The measured changes were subtle. Nevertheless, the fitted energy perturbations agree well with electrostatic predictions for five of the eight peptides. For the other three analogs, the fitted changes suggested a reduced translocation barrier rather than the reduced exit barrier as predicted by electrostatics.