Hemodynamic response to thermal stress varies with sex and age: a murine MRI study.

PURPOSE: The cardiovascular (CV) system plays a vital role in thermoregulation because of its influence on heat transfer via forced convection and conduction by changes in blood distribution, blood velocity, and proximity of vessels to surrounding tissues. To fully understand the cardiovascular system's role in thermoregulation, blood distribution (influenced by cardiac output, vessel size, blood flow, and pressure) must be quantified, ideally across sex and age. Additionally, wall shear stress is quantified because it is an important metric in cardiovascular disease localization and progression. By investigating the effect of thermal conditions on wall shear stress at a healthy baseline, researchers can begin to study the confluence of thermal condition with pathology or exercise. The purpose of this study is to determine the influence of sex and age on the CV response to temperature. In this work, the effect of core body temperature on hemodynamics of the murine arterial and venous systems has been studied non-invasively, at multiple locations across age and sex. METHODS: Male and female, adult and aged, mice (n = 20) were anesthetized and underwent MRI at 7 T. Data were acquired from four co-localized vessel pairs (the neck [carotid/jugular], torso [suprarenal and infrarenal aorta/inferior vena cava (IVC)], periphery [femoral artery/vein]) at core temperatures of 35, 36, 37, and 38 °C. Sixteen CINE, ECG-gated, phase contrast frames with one-directional velocity encoding (through plane) were acquired perpendicular to each vessel. Each frame was analyzed to quantify blood velocity and volumetric flow using a semi-automated in-house MATLAB script. Wall shear stress (WSS) was calculated using the Hagen-Poiseulle formula. A multivariable regression for WSS in the femoral artery was fitted with temperature, sex, age, body weight, and heart rate as variables. RESULTS: Blood velocity and volumetric flow were quantified in eight vessels at four core body temperatures. Flow in the infrarenal IVC linearly increased with temperature for all groups (p = .002; adjusted means of slopes: male vs. female, 0.37 and 0.28 cm/(s × °C); adult vs. aged, 0.22 and 0.43 cm/(s × °C)). Comparing average volumetric flow response to temperature, groups differed for the suprarenal aorta (adult < aged, p < .05), femoral artery (adult < aged, p < .05), and femoral vein (adult male < aged male, p < .001). The two-way interaction terms of temperature and body weight and temperature and sex had the largest effect on wall shear stress. CONCLUSIONS: Age, in particular, had a significant impact on hemodynamic response as measured by volumetric flow (e.g., aged males > adult males) and WSS at peak-systole (e.g., aged males < adult males). The hemodynamic data can provide physiologically-relevant parameters, including sex and age difference, to computational fluid dynamics models and provide baseline data for the healthy murine vasculature to use as a benchmark for investigations of a variety of physiological (thermal stress) and pathophysiological conditions of the cardiovascular system.

Imaging-based characterization of convective tissue properties.

Convective transport is an important phenomenon for nanomedicine delivery. We present an imaging-based approach to recover tissue properties that are significant in the accumulation of nanoparticles delivered via systemic methods. The classical pharmacokinetic analysis develops governing equations for the particle transport from a first principle mass balance. Fundamentally, the governing equations for compartmental mass balance represent a spatially invariant mass transport between compartments and do not capture spatially variant convection phenomena. Further, the parameters recovered from this approach do not necessarily have direct meaning with respect to the governing equations for convective transport. In our approach, a framework is presented for directly measuring permeability in the sense of Darcy flow through porous tissue. Measurements from our approach are compared to an extended Tofts model as a control. We demonstrate that a pixel-wise iterative clustering algorithm may be applied to reduce the parameter space of the measurements. We show that measurements obtained from our approach are correlated with measurements obtained from the extended Tofts model control. These correlations demonstrate that the proposed approach contains similar information to an established compartmental model and may be useful in providing an alternative theoretical framework for parameterizing mathematical models for treatment planning and diagnostic studies involving nanomedicine where convection dominated effects are important.

In Vivo MRI Assessment of Blood Flow in Arteries and Veins from Head-to-Toe Across Age and Sex in C57BL/6 Mice.

Although widely used as a preclinical model for studying cardiovascular diseases, there is a scarcity of in vivo hemodynamic measurements of the naïve murine system in multiple arterial and venous locations, from head-to-toe, and across sex and age. The purpose of this study is to quantify cardiovascular hemodynamics in mice at different locations along the vascular tree while evaluating the effects of sex and age. Male and female, adult and aged mice were anesthetized and underwent magnetic resonance imaging. Data were acquired from four co-localized vessel pairs (carotid/jugular, suprarenal and infrarenal aorta/inferior vena cava (IVC), femoral artery/vein) at normothermia (core temperature 37 ± 0.2 °C). Influences of age and sex on average velocity differ by location in arteries. Average arterial velocities, when plotted as a function of distance from the heart, decrease nearly linearly from the suprarenal aorta to the femoral artery (adult and aged males: - 0.33 ± 0.13, R2 = 0.87; - 0.43 ± 0.10, R2 = 0.95; adult and aged females: - 0.23 ± 0.07, R2 = 0.91; - 0.23 ± 0.02, R2 = 0.99). Average velocity of aged males and average volumetric flow of aged males and females tended to be larger compared to adult comparators. With cardiovascular disease as the leading cause of death and with the implications of cardiovascular hemodynamics as important biomarkers for health and disease, this work provides a foundation for sex and age comparisons in pathophysiology by collecting and analyzing hemodynamic data for the healthy murine arterial and venous system from head-to-toe, across sex and age.

Anatomical location, sex, and age influence murine arterial circumferential cyclic strain before and during dobutamine infusion.

BACKGROUND: One of the primary biomechanical factors influencing arterial health is their deformation across the cardiac cycle, or cyclic strain, which is often associated with arterial stiffness. Deleterious changes in the cardiovascular system, e.g., increased arterial stiffness, can remain undetected until the system is challenged, such as under a cardiac stressor like dobutamine. PURPOSE: To quantify cyclic strain in mice at different locations along the arterial tree prior to and during dobutamine infusion, while evaluating the effects of sex and age. STUDY TYPE: Control/cohort study. ANIMAL MODEL: Twenty C57BL/6 mice; male, female; ∼12 and 24 weeks of age; n = 5 per group. FIELD STRENGTH/SEQUENCE: 7T; CINE MRI with 12 frames, velocity compensation, and prospective cardiac gating. ASSESSMENT: Prior to and during the infusion of dobutamine, Green-Lagrange circumferential cyclic strain was calculated from perimeter measurements derived from CINE data acquired at the carotid artery, suprarenal and infrarenal abdominal aorta, and iliac artery. STATISTICAL TESTS: Analysis of variance (ANOVA) followed by post-hoc tests was used to evaluate the influence of dobutamine, anatomical location, sex, and age. RESULTS: Heart rates did not differ between groups prior to or during dobutamine infusion (P = 0.87 and P = 0.08, respectively). Dobutamine increased cyclic strain in each group. Within a group, increases in strain were similar across arteries. At the suprarenal aorta, strain was reduced in older mice at baseline (young 27.6 > mature 19.3%, P = 0.01) and during dobutamine infusion (young 53.0 > mature 36.2%, P = 0.005). In the infrarenal aorta, the response (dobutamine - baseline) was reduced in older mice (young 21.9 > mature 13.5%, P = 0.04). DATA CONCLUSION: Dobutamine infusion increases circumferential cyclic strain throughout the arterial tree of mice. This effect is quantifiable using CINE MRI. The results demonstrate that strain prior to and during dobutamine is influenced by anatomical location, sex, and age. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:69-80.

VALIDATING FORWARD MODELING AND INVERSIONS OF HELIOSEISMIC HOLOGRAPHY MEASUREMENTS.

Here we use synthetic data to explore the performance of forward models and inverse methods for helioseismic holography. Specifically, this work presents the first comprehensive test of inverse modeling for flows using lateral-vantage (deep-focus) holography. We derive sensitivity functions in the Born approximation. We then use these sensitivity functions in a series of forward models and inversions of flows from a publicly available magnetohydrodynamic quiet-Sun simulation. The forward travel times computed using the kernels generally compare favorably with measurements obtained by applying holography, in a lateral-vantage configuration, on a 15-hour time series of artificial Dopplergrams extracted from the simulation. Inversions for the horizontal flow components are able to reproduce the flows in the upper 3Mm of the domain, but are compromised by noise at greater depths.

Cross-sectional area of the murine aorta linearly increases with increasing core body temperature.

PURPOSE: The cardiovascular (CV) system plays a vital role in thermoregulation. To date, the response of core vasculature to increasing core temperature has not been adequately studied in vivo. Our objective was to non-invasively quantify the arterial response in murine models due to increases in body temperature, with a focus on core vessels of the torso and investigate whether responses were dependent on sex or age. METHODS: Male and female, adult and aged mice were anaesthetised and underwent magnetic resonance imaging (MRI). Data were acquired from the circle of Willis (CoW), heart, infrarenal aorta and peripheral arteries at core temperatures of 35, 36, 37 and 38 °C (±0.2 °C). RESULTS: Vessels in the CoW did not change. Ejection fraction decreased and cardiac output (CO) increased with increasing temperature in adult female mice. Cross-sectional area of the aorta increased significantly and linearly with temperature for all groups, but at a diminished rate for aged animals (p < 0.01; male and female: adult, 0.019 and 0.024 mm2/°C; aged, 0.017 and 0.011 mm2/°C). Aged male mice had a diminished response in the periphery (% increase in femoral artery area from 35 to 38 °C, male and female: adult, 67 and 65%; aged, 0.1 and 57%). CONCLUSION: Previously unidentified increases in aortic area due to increasing core temperature are biologically important because they may affect conductive and convective heat transfer. Leveraging non-invasive methodology to quantify sex and age dependent vascular responses due to increasing core temperature could be combined with bioheat modelling in order to improve understanding of thermoregulation.

Dendrimer-doxorubicin conjugates exhibit improved anticancer activity and reduce doxorubicin-induced cardiotoxicity in a murine hepatocellular carcinoma model.

Hepatocellular carcinoma (HCC) is the 2nd leading cause of cancer-related deaths every year globally. The most common form of treatment, hepatic arterial infusion (HAI), involves the direct injection of doxorubicin (DOX) into the hepatic artery. It is plagued with limited therapeutic efficacy and the occurrence of severe toxicities (e.g. cardiotoxicity). We aim to improve the therapeutic index of DOX delivered via HAI by loading the drug onto generation 5 (G5) poly(amidoamine) (PAMAM) dendrimers targeted to hepatic cancer cells via N-acetylgalactosamine (NAcGal) ligands. DOX is attached to the surface of G5 molecules via two different enzyme-sensitive linkages, L3 or L4, to achieve controllable drug release inside hepatic cancer cells. We previously reported on P1 and P2 particles that resulted from the combination of NAcGal-targeting with L3- or L4-DOX linkages, respectively, and showed controllable DOX release and toxicity towards hepatic cancer cells comparable to free DOX. In this study, we demonstrate that while the intratumoral delivery of free DOX (1 mg/kg) into HCC-bearing nod scid gamma (NSG) mice achieves a 2.5-fold inhibition of tumor growth compared to the saline group over 30 days, P1 and P2 particles delivered at the same DOX dosage achieve a 5.1- and 4.4-fold inhibition, respectively. Incubation of the particles with human induced pluripotent stem cell derived cardiomyocytes (hiPSC CMs) showed no effect on monolayer viability, apoptosis induction, or CM electrophysiology, contrary to the effect of free DOX. Moreover, magnetic resonance imaging revealed that P1- and P2-treated mice maintained cardiac function after intraperitoneal administration of DOX at 1 mg/kg for 21 days, unlike the free DOX group at an equivalent dosage, confirming that P1/P2 can avoid DOX-induced cardiotoxicity. Taken together, these results highlight the ability of P1/P2 particles to improve the therapeutic index of DOX and offer a replacement therapy for clinical HCC treatment.

Hemodynamic Impact of Superior Vena Cava Placement in the Y-Graft Fontan Connection.

BACKGROUND: A Fontan Y-shaped graft using a commercially available aortoiliac graft has been used to connect the inferior vena cava (IVC) to the pulmonary arteries. This modification of the Fontan procedure seeks to improve hepatic flow distribution (HFD) to the lungs. However, patient-specific anatomical restrictions might limit the space available for graft placement. Altering the superior vena cava (SVC) positioning is hypothesized to provide more space for an optimal connection, avoiding caval flow collision. Computational modeling tools were used to retrospectively study the effect of SVC placement on Y-graft hemodynamics. METHODS: Patient-specific anatomies (N = 10 patients) and vessel flows were reconstructed from retrospective cardiac magnetic resonance (CMR) images after Fontan Y-graft completion. Alternative geometries were created using a virtual surgery environment, altering the SVC position and the offset in relation to the Y-graft branches. Geometric characterization and computational fluid dynamics simulations were performed. Hemodynamic factors (power loss and HFD) were computed. RESULTS: Patients with a higher IVC return showed less sensitivity to SVC positioning. Patients with low IVC flow showed varied HFD results, depending on SVC location. Balanced HFD values (50% to each lung) were obtained when the SVC lay completely between the Y-graft branches. The effect on power loss was patient specific. CONCLUSIONS: SVC positioning with respect to the Y-graft affects HFD, especially in patients with lower IVC flow. Careful positioning of the SVC at the time of a bidirectional Glenn (BDG) procedure based on patient-specific anatomy can optimize the hemodynamics of the eventual Fontan completion.

HELIOSEISMIC HOLOGRAPHY OF SIMULATED SUNSPOTS: MAGNETIC AND THERMAL CONTRIBUTIONS TO TRAVEL TIMES.

Wave propagation through sunspots involves conversion between waves of acoustic and magnetic character. In addition, the thermal structure of sunspots is very different than that of the quiet Sun. As a consequence, the interpretation of local helioseismic measurements of sunspots has long been a challenge. With the aim of understanding these measurements, we carry out numerical simulations of wave propagation through sunspots. Helioseismic holography measurements made from the resulting simulated wavefields show qualitative agreement with observations of real sunspots. We use additional numerical experiments to determine, separately, the influence of the thermal structure of the sunspot and the direct effect of the sunspot magnetic field. We use the ray approximation to show that the travel-time shifts in the thermal (non-magnetic) sunspot model are primarily produced by changes in the wave path due to the Wilson depression rather than variations in the wave speed. This shows that inversions for the subsurface structure of sunspots must account for local changes in the density. In some ranges of horizontal phase speed and frequency there is agreement (within the noise level in the simulations) between the travel times measured in the full magnetic sunspot model and the thermal model. If this conclusion proves to be robust for a wide range of models, it would suggest a path toward inversions for sunspot structure.

EVALUATION OF THE CAPABILITY OF LOCAL HELIOSEISMOLOGY TO DISCERN BETWEEN MONOLITHIC AND SPAGHETTI SUNSPOT MODELS.

The helioseismic properties of the wave scattering generated by monolithic and spaghetti sunspots are analyzed by means of numerical simulations. In these computations, an incident f- or p1-mode travels through the sunspot model, which produces absorption and phase shift of the waves. The scattering is studied by inspecting the wavefield, computing travel-time shifts, and performing Fourier-Hankel analysis. The comparison between the results obtained for both sunspot models reveals that the differences in the absorption coefficient can be detected above noise level. The spaghetti model produces a steep increase of the phase shift with the degree of the mode at short wavelengths, while mode mixing is more efficient for the monolithic model. These results provide a clue for what to look for in solar observations to discern the constitution of sunspots between the proposed monolithic and spaghetti models.

Determination of ethylenediaminetetraacetic acid, ethylenediaminedisuccinic acid and iminodisuccinic acid in cosmetic products by capillary electrophoresis and high performance liquid chromatography.

A capillary electrophoresis (CE) and a high performance liquid chromatography (HPLC) method are described for the simultaneous determination of ethylenediaminetetraacetic acid (EDTA), S,S'-ethylenediaminedisuccinic acid (EDDS) and R,S-iminodisuccinic acid (IDS) complexing agents as their Fe(III) complexes in cosmetics like shower cream and foam bath. The non-biodegradable EDTA is used in combination with biodegradable analogues like EDDS and IDS in many commercial products. The HPLC method involves separation by reversed-phase ion pair chromatography on a C(18) column using methanol-formate buffer (20 mM tetrabutylammonium hydrogen sulfate, 15 mM sodium formate adjusted to pH 4.0 with formic acid) (10:90, v/v) as mobile solvent at a flow rate of 0.8 mL min(-1) at 24 degrees C using UV detection at 240 nm. The CE separation was performed in a fused silica capillary of 50 microm i.d. with the total length of 50 cm with a 10 mM MES and MOPSO (pH 5.5) at an applied voltage of -25 kV. The samples were introduced by applying a 50 mbar pressure for 2s. Absorbances at 215 and 225 nm were monitored for the detection of the complexes. The methodology performance of the two methods was evaluated in terms of linearity, limit of detection (LOD), limit of quantitation (LOQ) and reproducibility. The LOD values obtained from HPLC are low when compared with CE. The applicability of both the methods was demonstrated for the analysis of cosmetic products such as shower cream and foam bath. The results obtained by both CE and HPLC were found to be comparable and in good agreement.

Field testing the influence of sperm competition based on sperm mobility in breeder turkey toms.

1. Commercial reproduction of turkeys relies on pooling of semen from multiple males for inseminations. Understanding how sperm characteristics influence paternity under commercial breeding conditions is important to improving production efficiency. 2. The objective of this study was to evaluate progeny production of individual toms following commercial practices of pooling semen to determine if sperm mobility influences progeny production in field conditions. 3. A total of 104 toms were evaluated for sperm mobility. A subset of 10 toms were housed together and semen was collected, pooled and used to inseminate hens (n = 28). Hens were inseminated at 30 weeks of age and weekly thereafter. 4. Ejaculates from each tom were evaluated on two separate days for sperm mobility. Semen from each tom was diluted and layered upon 6% (wt/vol) Accudenz solution. The sperm suspension was incubated at 41 degrees C for 5 min and absorbance was measured with a spectrophotometer. 5. Toms were ranked by absorbance and categorised as high or low if mobility score was +/- 1 SD from the flock mean (average). 6. For parentage determination, DNA was extracted from tom, hen and poult blood. Poult parentage (n = 276) was determined at one day of age or at 14 weeks by analysis of marker genotypes that were generated by polymerase chain reaction (PCR) amplification of genomic DNA with selected microsatellite markers. 7. Sperm mobility differed across males with absorbance values ranging from 0.147 to 0.366. 8. Findings demonstrate differences in poult production among individual toms when semen from multiple males was pooled and inseminated. Toms classified as high, average and low produced 55, 41 and 4% of the offspring, respectively. 9. It appears that sperm mobility is a trait that influences sperm competition among toms under field conditions where sperm numbers inseminated from individual toms are not controlled or constant and that toms with low sperm mobility produce few offspring.

Effect of physical feed restriction during rearing on large white turkey breeder hens: 2. Reproductive performance.

Large White turkey breeder hens were used to evaluate the effect of three different levels of physical feed restriction on subsequent reproductive performance. The feed treatments were: 1) fed ad libitum throughout the study (CC), 2) feed-restricted from 16 to 24 wk (CR), 3) feed-restricted from 3 to 16 wk (RC), and 4) feed-restricted from 3 to 24 wk (RR). Feed restriction was implemented so that restricted-fed hens (RC and RR) achieved a 45% reduction in BW as compared to CC hens at 16 wk. From 16 to 24 wk, feed was allotted to RR and CR hens to maintain a slight increase in BW. At the completion of the respective restriction periods, hens were gradually returned to ad libitum feeding. At 30 wk of age, hens were photostimulated for a 20-wk summer season egg production cycle. Hens receiving RC and RR treatments laid significantly more eggs than did CC and CR hens for the first 5 wk of lay. However, once the house temperature increased to 26.7 to 29.4 C during 6 to 10 wk of lay, egg production of all hens decreased, resulting in a significant decrease in cumulative egg production for RR and RC hens compared to CC and CR hens. Egg and poult weights were less for RC and RR hens compared to those from CC and CR hens. In conclusion, age of breeder, season of implementation, and length of physical feed restriction have significant effects on the reproductive performance of turkey breeder hens.

Effect of physical feed restriction during rearing on large white turkey breeder hens: 1. Growth performance.

Large White turkey breeder hens were fed ad libitum (CC), feed-restricted from 16 to 24 wk (CR), feed-restricted from 3 to 16 wk (RC), or feed-restricted from 3 to 24 wk (RR). Feed restriction was implemented so that RC and RR hens achieved a 45% reduction in BW compared to CC hens at 16 wk. From 16 to 24 wk, feed was allotted to RR and CR hens to maintain a slight increase in BW. At the completion of each restriction period, hens were gradually released back to ad libitum feeding. At 30 wk of age, hens were photostimulated for a 20-wk summer season egg production cycle. Mean BW for all treatments were different (P < or = 0.05) at 16 and 30 wk. At the end of lay, hens on treatment CR were not different in BW from treatment CC hens, and treatment RR hens were not different in BW from treatment RC hens. Hens on treatment RR had the greatest BW gain and feed consumption leading into the production cycle. All treatment hens lost BW from the time of first egg until 47 wk of age. Hens on treatment CC lost significantly (P < or = 0.05) more relative BW (%) than those in any other treatment. Coefficient of variation for flock uniformity was similar for all treatments at time of photostimulation. At the end of the study, cumulative feed consumption was significantly less for restricted treatments: 86.5, 83.1, 75.8, and 70.7 kg/hen for treatments CC, CR, RC, and RR, respectively.

Effect of physical feed restriction during rearing on Large White turkey breeder hens: 3. Body and carcass composition.

Large White turkey breeder hens were used to evaluate the effect of three different levels of physical feed restriction on subsequent body and carcass composition. The four feed treatments were 1) ad libitum fed throughout the study (CC), 2) feed restricted from 16 to 24 wk (CR), 3) feed restricted from 3 to 16 wk (RC), and 4) feed restricted from 3 to 24 wk (RR). Feed restriction was implemented so that RC and RR hens achieved a 45% reduction in BW compared to CC hens at 16 wk. From 16 to 24 wk, feed was allotted to RR and CR hens to maintain a slight increase in BW. At the completion of each restriction period, hens were gradually returned to ad libitum feeding. At 30 wk, hens were photostimulated for a 20-wk summer season egg production cycle. Restricted fed hens had increased moisture levels at 16 and 30 wk and decreased fat levels at 16, 30, 39, and 54 wk (P < or = 0.05). Absolute and relative weights of the pectoralis major muscle were greater in hens fed ad libitum through 43 wk (P < or = 0.05). There were no differences in the number of maturing yellow follicles due to treatment. However, restricted fed hens had higher peak egg production during early lay but decreased subsequent and cumulative egg production. Changes in egg production were associated with changes in breast muscle weight. Prolactin levels were greater in hens in-production compared to hens out-of-production; however, there were no differences due to feed treatment. In conclusion, further research on quantitative feed-restriction programs, which result in body weight reductions as described in this study, should address specific physiological and nutritional requirements and not be implemented as general programs.

Restriction of feed consumption and body weight in two strains of large white turkey breeder hens.

Large White female-line turkey breeder hen poults (576) of two strains (N, female line and B, male line) were brooded by strain in floor pens from day of hatch until 3 wk of age (WOA). At 3 WOA, all poults were randomly distributed by strain to 48 floor pens in a curtain-sided house. Poults were feed (calorie) restricted beginning at 3 (N3, B3) or 6 (N6, B6) WOA to obtain a 45% reduction in BW at 16 WOA compared to ad libitum controls (NC, BC). At 16 WOA, all hens were gradually returned to ad libitum feeding. At 18 to 30 WOA, all hens were subjected to 8 h light/d. At 30 WOA, all hens were photostimulated with 15.5 h/d. Hens were inseminated weekly with semen from same strain, male-line breeder males. Eggs were collected daily, and all settable eggs from weeks of lay (WOL) 5 to 6, 10 to 11, 15 to 16, 20 to 21, and 24 to 25 were incubated by pen in a common incubator for each set date. Measurements included BW, feed consumption, egg production, mortality, egg fertility, egg hatchability, and poult weight. Statistical analysis of means was performed by strain. Target BW were obtained for feed-restricted hens. Restricted hens increased their feed consumption upon re-alimentation but did not achieve the cumulative feed consumption or BW of control fed hens by 56 WOA. Egg production of N3 hens was greater than NC hens for WOL 2 and 3. Total and settable eggs per hen were greater for N3 hens than for NC for WOL 1 to 5. There were no differences observed for egg weight, egg fertility, hatch of all eggs set, hatch of fertile eggs, or offspring weight among N hen treatments. The B0 hens produced more eggs than B3 or B6 hens. The B6 hens produced lighter weight eggs than B0 hens. It was concluded that early severe feed restriction of female line breeder hens might improve subsequent reproductive performance.

Influence of female body images in printed advertising on self-ratings of physical attractiveness by adolescent girls.

In contrast to earlier studies suggesting that self-concept is stable by late adolescence and therefore resistant to change, this study found that adolescent girls' ratings of self-attractiveness were significantly higher following exposure to printed advertisements employing attractive models who were overweight compared to those exposed to models who were not overweight. Implications for further research are discussed.

Cowpox in British voles and mice.

Serosurveys indicate that bank voles, field voles and woodmice are probably reservoir hosts of cowpox virus in western Europe, although virus has not yet been isolated from these species. In this study, bank voles, field voles, woodmice and laboratory mice were shown to be susceptible to combined intradermal and subcutaneous inoculation with 3-20 plaque-forming units (pfu) of cowpox virus. Bank and field voles, but not laboratory mice, were also susceptible to combined oral and nasal inoculation with 50 pfu. Few clinical signs were seen and virus was generally recovered only from inoculation sites. Bank voles were not susceptible to injection of ectromelia virus (5000 pfu) into the skin (as described above). These results provide information on which further pathogenesis and transmission studies can be based, and support the view that the orthopoxvirus antibody detected in British wild voles and woodmice indicates infection with cowpox virus. However, further investigation of the pathogenesis of cowpox in these species is needed to understand better the epidemiology of the disease.

Serological survey for orthopoxvirus infection of wild mammals in areas where a recombinant rabies virus is used to vaccinate foxes.

Several fox vaccination campaigns against rabies have been undertaken in Belgium by using a vaccinia-rabies recombinant virus distributed in baits in the field. However, foxes and other wild animals that may ingest the baits could be infected at the same time by another orthopoxvirus, such as cowpox virus, which circulates in wildlife. Recombination between the two viruses could therefore occur. A serological survey for antibodies to orthopoxvirus, and particularly to cowpox virus, was undertaken in foxes and in several other wild species. Antibodies were detected only in two rodent species, in 16 of 25 bank voles (64 per cent) and in two of 29 woodmice (7 per cent). The risk of virus recombination in wildlife can therefore be considered to be extremely low.