bluuebunny/crossref_metadata_2025 huggingface dataset:
A new in vitro model for the study of pig‐to‐human vascular hyperacute rejection
Authors: Bennet William , Sundberg Berit , Elgue Graciela , Larsson Rolf , Korsgren Olle , Nilsson Bo
Published: January 2006

Abstract: Studies on vascular hyperacute xenograft rejection (HAR) are usually conducted in vitro on cultured endothelial cells (EC) exposed to human serum, in complex whole organ perfusion models using heparinized blood or in vivo models. Here we describe a new model allowing perfusion of pig vessels with human whole blood without anticoagulants.

Segments of the porcine iliac artery were connected to circular polyvinyl chloride (PVC) tubing, whose inner surface was conjugated with immobilized heparin. The vessels were perfused with 7 to 8 ml of fresh, non‐anticoagulated human blood by rocking of the tubing device for 5, 15 or 60 min in an incubator at 37°C. Human iliac arteries (n = 4) were perfused with fresh human ABO‐compatible blood as controls.

Perfusion of human vessels resulted in changes in the blood and plasma parameters similar to those in the PVC control loop. Overall, perfusion of the porcine vessels generated high levels of C3a, sC5b‐9 and thrombin–anti‐thrombin (TAT). Platelet consumption was near total (97.2 ± 1.2%; “high” responders) in six of 13 vessels perfused and only moderate (55.8 ± 9.9%; “low” responders) in the remaining seven vessels. The “high” responder vessel group showed a significantly higher platelet reduction, neutrophil loss and monocyte consumption and higher C3a and TAT factor at 60 min compared with the human vessels. The “low” responder porcine vessel group also generated significantly higher TAT levels at 60 min compared with the human vessels, but lower levels compared with the “high” responder porcine vessel group. Immunohistochemical examination of perfused porcine vessels revealed binding of human IgM, IgG, IgA, C1q, C3, fibrin and platelets at 5 min. The binding of these proteins was even stronger at 15 and 60 min, and at 60 min C9 could also be detected. Addition of soluble complement receptor 1 (sCR1) to the blood resulted in a significant reduction in C3a and sC5b‐9 (P = 0.046 and P = 0.046, respectively). However, sCR1 did not reduce C1q, C3c or C5 staining, but did abolish C9 binding to the endothelium.

In conclusion, in vitro perfusion of porcine vessel segments with non‐heparinized, fresh human blood triggered events characterizing HAR. The small quantity of blood and xenogenic tissue that is needed makes this model ideal for investigations of the mechanisms and treatments of rejections associated with xenogeneic pig‐to‐human xenotransplantation.
T‐cell differentiation of human and  non‐human primate CD34+ hematopoietic progenitor cells using porcine thymic stroma
Authors: Rosenzweig Michael , Yamada Kazuhiko , Harper David M. , Hempel Donna M. , Johnson R. Paul
Published: January 2006

Abstract: Transplantation of swine thymic tissue has been proposed as an approach to reconstitute the immune system of HIV‐infected individuals. This is an attractive strategy because miniature swine are readily available as donors and porcine tissue is resistant to infection with HIV‐1. Demonstration that porcine thymus tissue supports primate T‐cell differentiation is critical to the ultimate utility of this approach. Using a thymic stroma culture system we have previously described [Rosenzweig M, Marks DF, Zhu H et al. In vitro T lymphopoiesis of human and rhesus CD34+ progenitor cells. Blood 1996; 87: 4040], we demonstrate that porcine thymus tissue is able to promote the in vitro T‐lymphocyte differentiation of both human and non‐human primate hematopoietic progenitor cells. CD34+ hematopoietic progenitors differentiated into both double positive (CD4+CD8+) and single positive thymocytes expressing CD4 or CD8 alone. A polyclonal T‐cell repertoire was evident. In addition, the T cells responded appropriately to mitogen and were permissive to infection with simian immunodeficiency virus (SIV). These data demonstrate the ability of porcine thymus to support T‐cell differentiation of both human and non‐human hematopoietic progenitor cells and support in vivo studies of transplantation of swine thymic tissue as a strategy for immune reconstitution in AIDS.
Phenomenology associated with age at onset in patients with bipolar disorder at their first psychiatric hospitalization
Authors: Patel Nick C , DelBello Melissa P , Keck Paul E , Strakowski Stephen M
Published: January 2006

Objective:  To compare the clinical presentation of patients with early‐onset (age <18 years) and typical‐onset (age 20–30 years) bipolar disorder at the time of first hospitalization.

Methods:  Patients, aged 12–45 years at their first psychiatric hospitalization, with a DSM‐IV diagnosis of bipolar disorder, manic or mixed, were evaluated on measures of manic, depressive, and positive psychotic symptoms. Differences in symptom profiles between early‐ and typical‐onset groups were examined.

Results:  One hundred three early‐onset and 58 typical‐onset patients were compared. Mixed episodes were more common in the early‐onset group, while psychotic features and current substance use were more common in the typical‐onset group. There was no significant difference in manic symptom severity ratings between early‐ and typical‐onset groups (F = 1.8, df = 11, 144, p = 0.06). However, these groups differed in depressive (F = 4.2, df = 16, 139, p < 0.001) and positive psychotic (F = 2.8, df = 16, 139, p = 0.001) symptom profiles. Typical‐onset bipolar patients reported more severe weight loss and formal thought disorder compared with early‐onset patients.

Conclusions:  Depressive and positive psychotic symptoms may differ in association with age at onset among patients with bipolar disorder. Additional studies are necessary to determine whether homogeneous phenotypes of bipolar disorder can be delineated based upon age at onset.
Fronto‐temporal function may distinguish bipolar disorder from schizophrenia
Authors: Frangou S , Dakhil N , Landau S , Kumari V
Published: January 2006

Objectives:  There is evidence for differential neural alterations within the prefrontal cortex (PFC) in bipolar disorder I (BDI) and schizophrenia that may translate into different cognitive deficits. Our objective was to compare the cognitive profile of stable BDI and schizophrenic patients using neuropsychological tasks which utilize frontal systems but differ in terms of the exact neural circuits and cognitive processes involved.

Methods:  We studied 43 patients with BDI, 54 with schizophrenia and 46 matched healthy participants. All participants completed (i) the Wisconsin Card Sorting Test (WCST) which is known to recruit the dorsal and ventral PFC, (ii) the verbal fluency task (VFT), which engages frontal‐temporal regions, and (iii) the Stroop Colour Word Test (SWCT) which depends on the integrity of the cingulo‐frontal network. A series of multivariate analyses examined differences between the cognitive profiles of BD and schizophrenic patients relative to that of healthy participants controlling for general intellectual ability and gender.

Results:  Bipolar disorder I patients showed minimal verbal fluency impairment while schizophrenic patients demonstrated marked deficits on this task relative to the control and BDI groups. The two patient groups had comparable performance on the WCST. In the SWCT, schizophrenic patients showed impairment in both congruent and incongruent conditions while BD patients had deficits only in the latter.

Conclusions:  Absence of significant verbal fluency abnormalities and by inference dysfunction in the associated fronto‐temporal circuitry may distinguish BDI from schizophrenia. Both disorders may show impairment in tasks involving cingulo‐frontal networks with evidence of greater cingulate dysfunction in schizophrenia.
Neurocognitive impairment in euthymic young adults with bipolar spectrum disorder and recurrent major depressive disorder
Authors: Smith Daniel J , Muir Walter J , Blackwood Douglas HR
Published: January 2006

Objective:  Patients with remitted major depressive disorder (MDD) and bipolar disorder have persistent impairments in executive function and verbal memory that may represent endophenotypic abnormalities. In this study, we examine neurocognitive function in a sample of euthymic young adults with bipolar spectrum disorder (BSD) (Can J Psychiatry 2002; 47: 125–134) and compare this to well‐matched samples of young adults with recurrent MDD and controls.

Method:  Twenty‐one euthymic young adult patients with BSD were compared with 42 young adult patients with MDD and 33 controls on a neuropsychological battery assessing attention, executive function and verbal memory.

Results:  Patients with BSD were significantly more impaired than MDD patients and controls on tests of executive function and verbal memory. MDD patients did not differ significantly from controls on verbal memory function but performed less well on a test of executive function.

Conclusion:  Euthymic young adults with BSD had greater impairment on neurocognitive measures associated with prefrontal and hippocampal function than MDD patients and controls. This is a reflection of a strong bipolar diathesis in the BSD group rather than being a consequence of a more severe unipolar illness.
Topiramate monotherapy in the management of acute mania: results of four double‐blind placebo‐controlled trials
Authors: Kushner Stuart F , Khan Akbar , Lane Rosanne , Olson William H
Published: January 2006

Objective:  To evaluate the efficacy and tolerability of topiramate monotherapy in adults with acute manic or mixed episodes of bipolar I disorder.

Methods:  In four trials, adults hospitalized with acute mania, a diagnosis of bipolar I disorder, history of ≥1 previous manic or mixed episodes, and ≥20 Young Mania Rating Scale (YMRS) score were randomized to double‐blind treatment with topiramate (target doses: 200, 400, or 600 mg/day) or placebo; two trials included an active comparator (lithium, 1500 mg/day). The core study duration in all trials was 3 weeks; three trials also had 9‐week double‐blind extensions. The primary efficacy variable was mean change from baseline in YMRS in the core 3‐week study.

Results:  Changes in YMRS score during 3 weeks were not significantly different for topiramate versus placebo (mean YMRS reductions, −5.1 to −8.4). Mean YMRS reductions in lithium‐treated groups were significantly greater (p ≤ 0.001 versus placebo and topiramate). A similar pattern was observed after 12 weeks of double‐blind treatment in studies with double‐blind extensions. Paresthesia, appetite decrease, dry mouth, and weight loss were more frequently associated with topiramate than with placebo.

Conclusions:  These studies do not support the efficacy of topiramate as monotherapy in acute mania or mixed episodes in adults with bipolar I disorder. Topiramate was not associated with mood destabilization measured as mania exacerbation or treatment‐emergent depression. Lithium was confirmed as an effective therapy in this population.
Diagnostic subtypes of bipolar disorder in older versus younger adults
Authors: Kessing Lars Vedel
Published: January 2006

Objective:  To investigate differences in diagnostic subtypes of bipolar disorder as according to ICD‐10 between patients whose first contact with psychiatric health care occurs late in life (over 50 years of age) and patients who have first contact earlier in life (50 years of age or below).

Methods:  From 1994 to 2002 all patients who received a diagnosis of a manic episode or bipolar disorder at initial contact with the mental healthcare system, whether outpatient or inpatient, were identified in Denmark's nationwide register.

Results:  A total of 852 (49.6%) patients, who were over age 50, and 867 patients, who were 50 or below, received a diagnosis of a manic episode or bipolar disorder at the first contact ever. Older inpatients presented with psychotic symptoms (35.4%) significantly less than younger inpatients (42.6%) due specifically to a lower prevalence of manic episodes with psychotic symptoms. Conversely, older inpatients more often presented with severe depressive episodes with psychotic symptoms than younger inpatients (32.0% versus 17.0%). Among outpatients, no significant differences were found between patients older than 50 years and patients 50 years of age or younger. However, a bimodal distribution of age at first outpatient contact was found with an intermode of 65 years and outpatients older than 65 years more often presented with severe depressive episodes with psychosis.

Conclusions:  Bipolar patients who are older at first psychiatric hospitalization (>50 years) present less with psychotic manic episodes and more with severe depressive episodes with psychosis than younger patients. The distribution of age at first outpatient contact is bimodal with an intermode of 65 years and outpatients older than 65 years more often present with severe depressive episodes with psychosis.
Ethnic differences in symptom presentation of youths with bipolar disorder
Authors: Patel Nick C , DelBello Melissa P , Strakowski Stephen M
Published: January 2006

Objective:  To compare symptom profiles of African‐American and white adolescents with a diagnosis of bipolar disorder.

Method:  Adolescents, aged 12–18 years at their first psychiatric hospitalization, with a DSM‐IV diagnosis of bipolar disorder, manic or mixed, were evaluated on measures of manic, depressive, and positive symptoms of psychosis. Ethnic differences in symptom profiles were examined using multivariate analysis of covariance, and specific symptoms contributing to the difference were analyzed.

Results:  Ethnic differences existed in manic and positive symptom profiles, but not depressive symptoms. Compared with the white cohort, African‐American youths were diagnosed more frequently as having psychotic features, and had higher ratings for auditory hallucinations.

Conclusions:  Similar to adults, symptom expression in adolescent bipolar disorder may differ between ethnic groups. Future studies are needed to replicate these findings and explore possible explanations.
Neuropsychological impairment in bipolar disorder: the relationship with glucocorticoid receptor function
Authors: Watson Stuart , Thompson Jill M , Ritchie James C , Nicol Ferrier I , Young Allan H
Published: January 2006

Objective:  Basal levels of glucocorticoids, such as cortisol, are generally unaltered in bipolar disorder. However, neuroendocrine tests of glucocorticoid receptor (GR) function such as the dexamethasone suppression test (DST) are frequently abnormal. Neuropsychological impairment is well documented in healthy volunteers after administration of glucocorticoids and in patients with bipolar affective disorder. This suggests a potential link between neuropsychological and hypothalamic‐pituitary‐adrenal axis function. We examined the hypothesis that neuropsychological impairment in bipolar disorder is associated with abnormal GR function.

Methods:  Seventeen euthymic bipolar patients and 16 controls completed tests of verbal declarative and working memory (WM) tests and the DST. The correlation between neuroendocrine and neuropsychological function was examined.

Results:  Bipolar patients made significantly more errors of omission and commission on the WM paradigm and demonstrated impaired verbal recognition memory. Patients’ post‐dexamethasone cortisol correlated with WM commission errors (rs = 0.64, p = 0.0006). No such relationship was evident in controls.

Conclusion:  Deficits in declarative memory and WM are evident in patients with bipolar disorder. The deficit in retrieval accuracy from WM appears to be correlated with abnormal GR function.
Stroop performance in bipolar disorder: further evidence for abnormalities in the ventral prefrontal cortex
Authors: Kronhaus Dina M , Lawrence Natalia S , Williams Andrew M , Frangou Sophia , Brammer Michael J , Williams Steve CR , Andrew Christopher M , Phillips Mary L
Published: January 2006

Objectives:  Bipolar patients are impaired in Stroop task performance, a measure of selective attention. Structural and functional abnormalities in task‐associated regions, in particular the prefrontal cortex (PFC), have been reported in this population. We aimed to examine the relationship between functional abnormalities, impaired task performance and the severity of depressive symptoms in bipolar patients.

Methods:  Remitted bipolar patients (n = 10; all medicated), either euthymic or with subsyndromal depression, and age‐matched control subjects (n = 11) viewed 10 alternating blocks of incongruent Stroop and control stimuli, naming the colour of the ink. Neural response was measured using functional magnetic resonance imaging. We computed between‐group differences in neural response and within‐group correlations with mood and anxiety.

Results:  There were no significant between‐group differences in task performance. During the Stroop condition, controls demonstrated greater activation of visual and dorsolateral and ventrolateral prefrontal cortical areas; bipolar patients demonstrated relative deactivation within orbital and medial prefrontal cortices. Depression scores showed a trend towards a negative correlation with the magnitude of orbitofrontal cortex deactivation in bipolar patients, whereas state anxiety correlated positively with activation of dorsolateral PFC and precuneus in controls.

Conclusions:  Our findings confirm previous reports of decreased ventral prefrontal activity during Stroop task performance in bipolar patients, and suggest a possible negative correlation between this and depression severity in bipolar patients. These findings further highlight the ventromedial PFC as a potential candidate for illness related dysfunction in bipolar disorder.
Affective instability as rapid cycling: theoretical and clinical implications for borderline personality and bipolar spectrum disorders
Authors: MacKinnon Dean F , Pies Ronald
Published: January 2006

Objectives:  The Diagnostic and Statistical Manual of Mental Disorders guidelines provide only a partial solution to the nosology and treatment of bipolar disorder in that disorders with common symptoms and biological correlates may be categorized separately because of superficial differences related to behavior, life history, and temperament. The relationship is explored between extremely rapid switching forms of bipolar disorder, in which manic and depressive symptoms are either mixed or switch rapidly, and forms of borderline personality disorder in which affective lability is a prominent symptom.

Methods:  A MedLine search was conducted of articles that focused on rapid cycling in bipolar disorder, emphasizing recent publications (2001–2004).

Results:  Studies examined here suggest a number of points of phenomenological and biological overlap between the affective lability criterion of borderline personality disorder and the extremely rapid cycling bipolar disorders. We propose a model for the development of ‘borderline’ behaviors on the basis of unstable mood states that sheds light on how the psychological and somatic interventions may be aimed at ‘breaking the cycle’ of borderline personality disorder development. A review of pharmacologic studies suggests that anticonvulsants may have similar stabilizing effects in both borderline personality disorder and rapid cycling bipolar disorder.

Conclusions:  The same mechanism may drive both the rapid mood switching in some forms of bipolar disorder and the affective instability of borderline personality disorder and may even be rooted in the same genetic etiology. While continued clinical investigation of the use of anticonvulsants in borderline personality disorder is needed, anticonvulsants may be useful in the treatment of this condition, combined with appropriate psychotherapy.
Cross‐Sectional and Longitudinal Studies of the Development of Group Differences in Acoustic Features of Coo Calls in Two Groups of Japanese Macaques
Authors: Tanaka Toshiaki , Sugiura Hideki , Masataka Nobuo
Published: January 2006

Japanese macaques,Macaca fuscata, frequently utter coo calls to maintain vocal contact. Cross‐sectional and longitudinal comparisons were conducted on the acoustic features of coo vocalizations of two groups ofM. fuscata, Yakushima and Ohirayama groups, to explore the possibility of vocal plasticity. These two groups derive from the same local population but have been separated for more than 34 yr. The Yakushima group is non‐provisioned, while the Ohirayama group is provisioned. Initially, coo calls in the two groups were compared cross‐sectionally in females ranging from 0 to 18 yr. Mean values of the four variables studied (start, end, maximum, and minimum frequencies) were consistently lower in all age groups of the Ohirayama individuals compared with the Yakushima individuals. Secondly, longitudinal comparisons were conducted on individuals in the 1–4 yr after birth. Mean values of the five frequency variables studied (start, end, maximum, minimum and average frequencies) were again consistently lower in all age groups of Ohirayama compared with Yakushima individuals, although mean values of both groups gradually declined with an increase in age. Inter‐group differences were significant at all ages in minimum frequency and at the first, second and third years in start frequency. Longitudinal comparisons of individuals aged 4–11 mo were also conducted. Regarding the four variables that differed between the two groups in the cross‐sectional study, the mean values of minimum and start frequency did not differ significantly between the two groups at 4–5 mo, but were significantly lower in Ohirayama individuals aged 7–8 and 9–11 mo. Although provisioning may have had an effect on the weight difference between the groups, and consequently on vocalization frequency, these results suggest that the inter‐group differences in coo call features form approximately 6–7 mo after birth as a result of vocal plasticity.
Does Temporal Variation in Predation Risk Influence the Intensity of Antipredator Responses? A Test of the Risk Allocation Hypothesis
Authors: Mirza Reehan S. , Mathis Alicia , Chivers Douglas P.
Published: January 2006

Temporal variation in predation risk may fundamentally influence antipredator responses of prey animals. To maximize lifetime fitness, prey must be able to optimize energy gain and minimize predation risk, and responses to current levels of risk may be influenced by background levels of risk. A ‘risk allocation’ model has recently been proposed to predict the intensity of antipredator responses that should occur as predation risk varies over time. Prey animals from high‐risk environments should respond to predators with relatively low intensities of antipredator behaviour because long periods of antipredator behaviour may result in unacceptable decreases in levels of foraging activity. Moreover, animals that are under frequent risk should devote more energy to foraging during brief pulses of safety compared with animals under infrequent attack. In this study, we experimentally tested the risk allocation hypothesis. We exposed juvenile rainbow trout, Oncorhynchus mykiss, to three levels of risk (high, moderate and low) crossed with two levels of temporal variation (exposed to risk three times a day and once a day). In accordance with the model, we found that trout exposed to risky situations more frequently responded with significantly less intense antipredator behaviour than trout exposed to risk infrequently. The intensity of response of trout exposed to moderate risk three times a day decreased to levels similar to situations of no risk. However, in contrast to the second prediction of the model, animals under frequent risk were not more active during periods of safety compared with animals under infrequent risk. Although behaviour in the face of predation risk was dependent on the broader temporal context in which risk varied, the specific predictions of the risk allocation model were only partly supported.
Gender Differences in Owners Interacting with Pet Dogs: An Observational Study
Authors: Prato‐Previde Emanuela , Fallani Gaia , Valsecchi Paola
Published: January 2006

Many studies show that people form strong affectional bonds with their dogs, treating them like family members or children. The present study investigates differences between women and men owners during interactions with their dogs, in a situation designed to investigate attachment and, thus, to promote emotional and affective responses: the Ainsworth's Strange Situation. Twenty‐five dog owners, 10 men and 15 women, were observed during free interactions with their pets in an adapted version of the ‘strange situation procedure’. Their behaviour towards their pets was videorecorded. Talking to the dog was evaluated together with the occurrence of affiliative and play behaviours. The owner's level of attachment to the dog was assessed using a questionnaire. Women and men differed in the use of verbal communication. Women talked more than men and had a shorter latency in starting talking. Their utterances resembled more closely infant‐directed speech or ‘motherese’. In contrast, there were no clear gender differences in affiliative and play behaviours. Both women and men engaged in play with their dogs and provided physical comfort. No differences emerged in the level of attachment reported by women and men owners in the questionnaire. These data support the hypothesis that the behaviour of modern pet owners towards their dogs is an interspecific parental behaviour, and suggest that behaviours evolved to provide care and comfort to human infants have been co‐opted for interacting with other social partners. The difference in verbal communication between women and men is in agreement with an evolutionary scenario suggesting a greater pre‐disposition in women to use language as a relational tool.
Non‐Advertized does not Mean Concealed: Body Odour Changes across the Human Menstrual Cycle
Authors: Havlíček Jan , Dvořáková Radka , Bartoš Luděk , Flegr Jaroslav
Published: January 2006

Females of a number of primate species display their fertile period by behavioural and/or morphological changes. Traditionally, the fertile period in human females has been considered to be concealed. However, this presumption has rarely been tested. One of the possible mechanisms for assessing menstrual cycle phase is through the sense of smell. In this study possible changes in odour across the menstrual cycle were investigated. Samples of body odour were acquired from 12 women (aged 19–27 yr), none of whom were using hormonal contraceptives. Samples were collected using cotton pads worn in the armpit for 24 h, from the menstrual, follicular and luteal cycle phases. Our experimental sample of 42 males (age 19–34 yr) repeatedly rated these odour samples for their intensity, pleasantness, attractiveness and femininity. Raw subjective smell ratings from each man were transformed to z‐scores. Subsequently, these z‐scores were tested by the general linear mixed‐model analysis (PROC MIXED, SAS) with the female's ID nested within the subject's ID as a random factor to account for the repeated measures of the subjects. Significant changes across the cycle were found for ratings of pleasantness [F(2,689) = 702; p = 0.001], attractiveness [F(2,546) = 6.35; p = 0.002] and intensity [F(2,530) = 3.57; p = 0.028]. Odour from women in the follicular (i.e. fertile) phase was rated as the least intense and the most attractive. Subsequent post hoc analysis revealed significant differences in intensity, pleasantness and attractiveness between the menstrual phase and the follicular phase, and in pleasantness and attractiveness between the menstrual and luteal phases. Significant difference between the follicular and the luteal phase was found only for attractiveness. Our results suggest that men can potentially use smell as a mechanism for monitoring menstrual cycle phase in current or prospective sexual partners. Therefore, the fertile period in humans should be considered non‐advertized, rather than concealed.
A Dry Summer Diminishes Mate Search Effort by Pronghorn Females: Evidence for a Significant Cost of Mate Search
Authors: Byers John A. , Byers Anna A. , Dunn Stacey J.
Published: January 2006

In the 2 weeks before estrus, pronghorn (Antilocapra americana) females on the National Bison Range in northwestern Montana, USA usually move actively among several widely spaced, mature, site‐faithful males in a mate search process that identifies vigorous mates. Typically, at least 90% of females practice this active sampling each year; each of the remaining females moves, before the rut begins, to a peripheral, isolated location with a single male and mates there without sampling. In 2001 and 2002, 90 and 100% of females, respectively, used the sampling strategy. The summer of 2003 was unusually hot and dry in western Montana. By September, when the pronghorn rut occurs, many pronghorn females were in visibly poor condition. In the winter that followed, 38% of females and 79% of males died, and in the following spring, only 17% of the surviving females gave birth. In the rut of 2003, 19% of females practiced the active sampling strategy. In 2004, 68% of females attempted to sample, even though there were only three mature males in the population. Among females that sampled, the number of switches away from harems and the number of males visited did not vary across years, except in 2004. The proportion of samplers in 2003 that died over winter was not different from the proportion of non‐samplers that died over winter, and among the survivors, the proportion of samplers that completed gestation was not different from the proportion of non‐samplers that completed gestation. The data suggest that pronghorn females have a strong motivation to sample potential mates, that sampling is abandoned when energy stores are low, and that yearly variation in the percent of females that sample is explained by variation in female condition.
Mate Choice in Male Mandrills (Mandrillus sphinx)
Authors: Setchell Joanna M. , Jean Wickings E.
Published: January 2006

Male primates that attempt to monopolize access to receptive females by mate‐guarding expend time and energy and risk injury, making reproduction costly. Males should therefore show mate choice and preferentially allocate mating effort to females that are likely to be fertile and those that will produce high‐quality offspring. Specifically, males should preferentially mate‐guard high‐ranking females rather than low‐ranking females, as such females are more likely to be fertile and are able to invest more in offspring. Males should also prefer parous females to nullipares, for similar reasons. Finally, males should avoid mating with close relatives, to avoid the deleterious effects of inbreeding. We investigated 13 group‐years of mate‐guarding observations for two semi‐free‐ranging groups of mandrills to examine the influence of these factors on male investment in mate‐guarding. We found that males mate‐guarded higher‐ranking females more than lower‐ranking females, and parous females more than nullipares. Female age, true relatedness and maternal kinship did not influence male mate‐guarding. Our results suggest that male mandrills do exercise mate choice for higher‐quality females, in the form of higher‐ranking and parous females. As alpha males are responsible for the great majority of mate‐guarding, this can lead to assortative mating, where high‐ranking males reproduce with high‐ranking females, and has important implications for social relationships and kin selection.
Phenotypic Plasticity in the Reproductive Behavior of Female Sand Tilefish, Malacanthus plumieri
Authors: Baird Troy A. , Baird Teresa D.
Published: January 2006

Female sand tilefish (Malacanthus plumieri) inhabiting a deep channel in the fringing reef at Glover's Atoll, Belize (channel females) spawned planktonic eggs more frequently than those occupying the shallow sand‐rubble slopes adjacent to patch coral reefs inside the atoll lagoon (reef‐slope females). We tested five non‐exclusive hypotheses to explain habitat differences in female spawning frequency. We found no evidence that spawning frequency variation was a consequence of differences in food availability, variation in male fertility, or the intensity of predation on spawned eggs. On reef slopes, barracuda stalked tilefish near their benthic burrows, whereas these piscivores attacked channel tilefish by diving suddenly from higher in the water column. Differences in the hunting behavior of barracuda suggested that the behavior of tilefish females might be influenced by temporal variation in predation risk (risk allocation hypothesis). Consistent with this hypothesis, reef‐slope females had a much higher frequency of retreats to burrows in response to barracuda, spent more time burrowing and ventured less far from these refugia in response to a simulated predatory threat. As predicted by the risk allocation hypothesis, reef‐slope females also had lower and more variable frequencies of foraging bites, and shorter and more variable travel distances to forage than channel females. Estimated mortality from predation was over nine times higher in channel tilefish. Consistent with the hypothesis that investment in current vs. future reproduction is influenced by rates of adult mortality (mortality risk hypothesis), channel females invested more supplemental energy in egg production whereas reef‐slope females invested more in growth. Our results indicate that behavioral and life‐history traits of female tilefish show phenotypic plasticity depending upon the nature and intensity of localized predation risk.
The Effect of Social Environment on Male–Male Competition in Guppies (Poecilia reticulata)
Authors: Price Anna C. , Helen Rodd F.
Published: January 2006

We examined male–male competition in guppies (Poecilia reticulata) to test for evidence of hierarchy formation and any subsequent effects on male mating success by comparing the interactions of pairs of males that were siblings and life‐long tank mates with those of unrelated pairs that had never met. These pairs of males were first observed in the absence of a female; then a female was added to gauge the effects of the initial male–male interactions on male sexual behaviour. The unfamiliar/unrelated pairs engaged in significantly more aggressive interactions such as physical contacts, nipping and chasing than the familiar/related pairs. Based on several previous studies, we suggest that familiarity played a greater role than relatedness in the differences in behaviour that we observed. Our results suggest that, in some circumstances, more aggressive males may have more mating opportunities than less aggressive males. Our results also indicate that males adjust their aggressive and courtship behaviours to the perceived intensity of competition for mates, based on the number of mature males in their rearing tanks. We suggest that male–male competition for mating opportunities may play a more important role in the guppy mating system than previously thought.
Reproductive and Endocrine Characteristics of Delayed Pubertal Ewe‐Lambs after Melatonin and l‐Tyrosine Administration
Authors: El‐Battawy KA
Published: January 2006

Contents

The investigation was carried out to study the impact of melatonin and l‐tyrosine administration on the onset of cyclicity in delayed pubertal ewe‐lambs. Fifteen delayed pubertal ewe‐lambs (age >16 months) were used in this study after being assigned randomly into three groups. In the first group (melatonin treated group, n = 5), each lamb was administered 3 mg melatonin orally at 16:00 hours from 1 July to 15 September while in the second group (l‐tyrosine treated group, n = 5), each lamb was administered l‐tyrosine at the level of 100 mg/kg b.w. as a single oral dose. The third group (n = 4) served as control. Lambs were exposed to mature, fertile rams daily and blood samples were collected twice weekly. The progesterone concentrations (P4 evaluations) were significantly higher (p < 0.05) in treated groups than the control group. Ovarian activity, assessed by P4 evaluations, showed that all animals in the first group came in oestrus and from them four got pregnant (80%) while in the second group, only three lambs came in heat and from them two became pregnant (40%). On the contrary, none of the control lambs showed oestrus. In conclusion, this study confirmed that the oral administration of melatonin and l‐tyrosine played an essentially physiological roles to induce cyclicity in delayed pubertal ewe‐lambs and improved their reproduction.
Normal Values for the Scrotal Circumference in Rams of Gotlandic Breed
Authors: Söderquist L , Hultén F
Published: January 2006

Contents

Selection of fertile sires is crucial for profitable lamb production. Males with larger testes tend to sire daughters that reach puberty at an earlier age and ovulate more ova during each oestrus period. Measurement of the scrotal circumference (SC) is thus an essential part of the breeding soundness evaluation. Testicular size varies with breed, age and time of the year. No SC values or recommendations for minimal values have been established in any of the Scandinavian domestic sheep breeds. Data were recorded of the SC, age and weight in 245 ram lambs and 27 mature rams of the Gotlandic breed, which is the breed that constitutes about 50% of the Swedish sheep population. For the ram lambs, the overall mean SC was 28.9 (±1.9) cm at an average age of 170 (±9) days and mean weight of 53.5 (±7.0) kg, and the mean SC varied between 27.1 and 29.6 cm depending on age and weight. For mature rams (17–54 month old), the mean SC was 32.4(±2) cm. To provide a practical tool for exclusion of rams with sub‐optimal reproductive capacity (abnormal testes or those with small testes because of delayed puberty) a threshold value was established based on the average SC minus 2 SD. The calculated minimal SC is 26 cm for ram lambs >5.5 months of age with a body weight of >50 kg. For mature rams, minimum SC is 28 cm regardless of weight and age.
Mitochondrial Activity, Distribution and Segregation in Bovine Oocytes and in Embryos Produced in Vitro
Authors: Tarazona AM , Rodríguez JI , Restrepo LF , Olivera‐Angel M
Published: January 2006

Contents

Bovine oocytes and embryos produced in vitro were studied to determine the mitochondrial pattern of distribution, segregation and activity using DIOC 6 and Jc‐1 fluorescence. The highest fluorescence level observed in mature oocytes was taken as 100% activity and six activity levels were estimated as follows: (1) 0%, (2) 1–15%, (3) 16–30%, (4) 31–50%, (5) 51–75% and (6) 76–100%. Three patterns of mitochondrial distribution were found: (1) diffused throughout the cytoplasm in oocytes and embryos, (2) pericytoplasmic in oocytes and embryos, and (3) perinuclear only in embryos. The segregation of mitochondria in blastomeres showed two distinct patterns: (1) symmetrical with an even mitochondrial population, and (2) asymmetrical with different numbers of mitochondria in each blastomere. In immature oocytes, mitochondrial activity was very low and the distribution was diffuse or negligible, while in mature oocytes the activity was high and the distribution was diffuse or pericytoplasmic. Competent embryos up to the 16‐cell stage showed intermediate levels of activity (16–50%) but activity decreased thereafter up to the blastocyst stage. Non‐competent embryos showed low levels of activity (1–15%) at all stages. These results suggest that mitochondria might play an important role during early development and that a minimum threshold of activity regulates the potential competence for reaching the blastocyst stage.
Update on Semen Technologies for Animal Breeding*
Authors: Morrell JM
Published: January 2006

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Despite the scale of the livestock breeding industry, where many millions of insemination doses are prepared each year, sperm preparation techniques are used infrequently in animal assisted reproduction compared with its human counterpart. However, some of the techniques used for human sperm preparation, for example, density gradient centrifugation, improve the quality of sperm preparations which is, in turn, reflected by an increased conception rate. The preparation technique separates motile spermatozoa with normal morphology and intact DNA from the total sperm population, leaving behind immature or senescent spermatozoa, morphologically abnormal ones and those with damaged DNA. Furthermore, the motile spermatozoa are removed from the seminal plasma which carries cells, cellular debris and reactive oxygen species, as well as pathogens. Gradient‐prepared spermatozoa survive longer, either in liquid storage or when cryopreserved, and are free of bacteria and viral infectivity if prepared carefully. Preparation techniques such as density gradient centrifugation, or the simplified single layer centrifugation technique, have considerable potential for aiding sperm preparation from poor quality semen samples, such as may be obtained from unselected semen donors in captive breeding programmes, or from performance horses. Moreover, the removal of pathogens has important implications, both for disease control and for avoiding the use of antibiotics in semen extenders, which can be detrimental to sperm survival.
Studies on the Effect of Supplementing Boar Semen Cryopreservation Media with Different Avian Egg Yolk Types on in Vitro Post‐thaw Sperm Quality
Authors: Bathgate R , Maxwell WMC , Evans G
Published: January 2006

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Fertility after insemination of cryopreserved boar semen is currently below that of fresh semen. In an attempt to improve the post‐thaw motility and acrosome integrity of boar sperm, semen was frozen using an adapted Westendorf method in which the chicken egg yolk was replaced by either duck or quail egg yolk. The different composition of the yolk types, particularly the amount of cholesterol, fatty acids and phospholipids, were thought to potentially afford a greater level of protection to sperm against damage during freezing and thawing. Sperm frozen in medium containing chicken egg yolk displayed higher motility immediately after thawing, but there was no difference in the motility of sperm frozen with different types of egg yolk 3 or 6 h after thawing and maintenance at 37°C. Sperm frozen in media containing chicken or duck egg yolk had a higher proportion of intact acrosomes immediately after thawing than sperm frozen in medium containing quail egg yolk, but 6 h after thawing and maintenance at 37°C the sperm that had been frozen in medium containing chicken egg yolk had a higher proportion of intact acrosomes than the sperm frozen in media containing duck or quail egg yolk. Analysis of the composition of the different yolk types showed that the basic components of the yolks were similar, but the ratios of fatty acids and phospholipid classes differed. Duck egg yolk had more monounsaturated fatty acids (MUFA) than chicken egg yolk, which had more MUFA than quail egg yolk. Duck egg yolk contained more phosphotidylinositol (PI) than chicken or quail egg yolks and quail egg yolk contained more phosphotidylserine than either chicken or duck egg yolks. The differences in post‐thaw motility and acrosome integrity of boar sperm when frozen in media containing the different types of egg yolk may be due to the variation in composition.
Influence of Temperature during Glycerol Addition and Post‐thaw Dilution on the Quality of Canine Frozen Semen
Authors: Silva AR , Cardoso RCS , Silva LDM
Published: January 2006

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The aim of the present study was to compare the influence of room temperature (27°C) and 4°C during glycerol addition on canine semen cryopreservation and verify the effect of different post‐thawing dilutions on canine semen. Ten ejaculates from five stud dogs were collected by digital manipulation. Semen samples were evaluated and further divided into two aliquots. The first aliquot was extended in Tris‐egg yolk‐glycerol at 27°C and the second one received glycerol at 4°C. Samples were frozen and stored in liquid nitrogen. After 1 week, samples were thawed and submitted to evaluations of progressive sperm motility, morphology, acrosomal integrity, hypo‐osmotic swelling (HOST) and thermoresistance tests. For thermoresistance test, aliquots were divided in two portions: one portion was kept undiluted (1 : 0) and the other one was diluted in a 1 : 4 ratio (one part semen to four parts extender). No differences were observed between temperatures for glycerol addition regarding seminal parameters evaluated. Furthermore, post‐thawing dilutions demonstrated similar effect on canine semen longevity. Correlations among post‐thaw sperm motility and HOST and results from thermoresistance test were observed for both temperatures for glycerol addition. In conclusion, glycerol could be added to canine semen at room temperature (27°C) or at 4°C. Moreover, there is no need to extend canine semen after thawing for the thermoresistance test, but if we need to increase the inseminating volume for artificial inseminations, the addition of extender will not damage the semen.
Effects of β‐OH Butyrate on Bovine Granulosa and Theca Cell Function in Vitro
Authors: Vanholder T , Leroy JLMR , Van Soom A , Coryn M , de Kruif A , Opsomer G
Published: January 2006

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In this study, the effects of β‐OH butyrate (BHB) levels, associated with a negative energy balance, on bovine granulosa and theca cell function were investigated in vitro. Granulosa and theca cells of healthy large follicles (>8 mm), obtained from slaughterhouse ovaries, were cultured in serum free medium containing 0, 0.5, 1 or 1.5 mm BHB and 3 mm glucose, to mimic the situation in the early postpartum dairy cow. Hormone concentrations (progesterone, oestradiol‐17β and/or androstenedione) in spent medium and cell numbers were measured after 48 h of culture. No effects of BHB on theca cell numbers or on steroid production were observed. In granulosa cells, all BHB treatments evenly increased cell numbers (p < 0.05), while they reduced progesterone and oestradiol‐17β production per cell (p < 0.05). These effects may be attributed to the use of BHB as energy source which is however differently metabolized than glucose. Conclusively, in the presence of physiological glucose concentrations BHB can modulate granulosa but not theca cell function in vitro.