The masculinity paradox: facial masculinity and beardedness interact to determine women's ratings of men's facial attractiveness.

In many species, male secondary sexual traits have evolved via female choice as they confer indirect (i.e. genetic) benefits or direct benefits such as enhanced fertility or survival. In humans, the role of men's characteristically masculine androgen-dependent facial traits in determining men's attractiveness has presented an enduring paradox in studies of human mate preferences. Male-typical facial features such as a pronounced brow ridge and a more robust jawline may signal underlying health, whereas beards may signal men's age and masculine social dominance. However, masculine faces are judged as more attractive for short-term relationships over less masculine faces, whereas beards are judged as more attractive than clean-shaven faces for long-term relationships. Why such divergent effects occur between preferences for two sexually dimorphic traits remains unresolved. In this study, we used computer graphic manipulation to morph male faces varying in facial hair from clean-shaven, light stubble, heavy stubble and full beards to appear more (+25% and +50%) or less (-25% and -50%) masculine. Women (N = 8520) were assigned to treatments wherein they rated these stimuli for physical attractiveness in general, for a short-term liaison or a long-term relationship. Results showed a significant interaction between beardedness and masculinity on attractiveness ratings. Masculinized and, to an even greater extent, feminized faces were less attractive than unmanipulated faces when all were clean-shaven, and stubble and beards dampened the polarizing effects of extreme masculinity and femininity. Relationship context also had effects on ratings, with facial hair enhancing long-term, and not short-term, attractiveness. Effects of facial masculinization appear to have been due to small differences in the relative attractiveness of each masculinity level under the three treatment conditions and not to any change in the order of their attractiveness. Our findings suggest that beardedness may be attractive when judging long-term relationships as a signal of intrasexual formidability and the potential to provide direct benefits to females. More generally, our results hint at a divergence of signalling function, which may result in a subtle trade-off in women's preferences, for two highly sexually dimorphic androgen-dependent facial traits.

Causes of male sexual trait divergence in introduced populations of guppies.

Males from different populations of the same species often differ in their sexually selected traits. Variation in sexually selected traits can be attributed to sexual selection if phenotypic divergence matches the direction of sexual selection gradients among populations. However, phenotypic divergence of sexually selected traits may also be influenced by other factors, such as natural selection and genetic constraints. Here, we document differences in male sexual traits among six introduced Australian populations of guppies and untangle the forces driving divergence in these sexually selected traits. Using an experimental approach, we found that male size, area of orange coloration, number of sperm per ejaculate and linear sexual selection gradients for male traits differed among populations. Within populations, a large mismatch between the direction of selection and male traits suggests that constraints may be important in preventing male traits from evolving in the direction of selection. Among populations, however, variation in sexual selection explained more than half of the differences in trait variation, suggesting that, despite within-population constraints, sexual selection has contributed to population divergence of male traits. Differences in sexual traits were also associated with predation risk and neutral genetic distance. Our study highlights the importance of sexual selection in trait divergence in introduced populations, despite the presence of constraining factors such as predation risk and evolutionary history.

Correlational selection does not explain the evolution of a behavioural syndrome.

Correlated suites of behaviours, or behavioural syndromes, appear to be widespread, and yet few studies have explored how they arise and are maintained. One possibility holds that correlational selection can generate and maintain behavioural syndrome if certain behavioural combinations enjoy greater fitness than other combinations. Here we test this correlational selection hypothesis by comparing behavioural syndrome structure with a multivariate fitness surface based on reproductive success of male water striders. We measured the structure of a behavioural syndrome including dispersal ability, exploration behaviour, latency to remount and sex recognition sensitivity in males. We then measured the relationship between these behaviours and mating success in a range of sex ratio environments. Despite the presence of some significant correlational selection, behavioural syndrome structure was not associated with correlational selection on behaviours. Although we cannot conclusively reject the correlational selection hypothesis, our evidence suggests that correlational selection and resulting linkage disequilibrium might not be responsible for maintaining the strong correlations between behaviours. Instead, we suggest alternative ways in which this behavioural syndrome may have arisen and outline the need for physiological and quantitative genetic tests of these suggestions.

Exposure to a novel male during late pregnancy influences subsequent growth of offspring during lactation.

In mammals, allocation to reproduction can either be primed or suppressed in relation to cues from other individuals. Some conspecifics (e.g. potential mates) may enhance an individual's ability to reproduce but others may have a detrimental effect on reproductive success. One widely studied response to conspecific cues, the 'Bruce effect', occurs when pregnant females abort their pregnancies after exposure to a novel male. It has been suggested that this response has evolved as a counter-tactic to the threat of infanticide posed by novel males. In some species, like mice, pregnancy termination will only occur if females are exposed to the unfamiliar male during a brief critical period early in pregnancy, which is surprising considering that an unfamiliar male threatens infanticide whenever present, and in particular near to birth. We demonstrate that female mice experiencing novel males during late pregnancy also alter their investment in progeny, but in a more subtle manner than previously observed. Females exposed to an unfamiliar male during late pregnancy give birth to offspring of a comparable weight to those produced by females exposed to the paternal male, but these offspring grow more slowly over lactation. As a consequence, offspring from these females weigh less at weaning. Modification of their growth trajectory, however, allows these offspring to catch up to normal weights by adulthood. Thus, cues of unfamiliar males, and possibly their associated threat of infanticide, can produce more wide-ranging effects on maternal investment than previously recognized.

The importance of listening: juvenile allocation shifts in response to acoustic cues of the social environment.

The social environment has a strong effect on the strength and direction of sexual selection. Juveniles, however, often have social cues that signal the current competitive environment which may provide cues of future competitive challenges. Here we demonstrate that juvenile crickets (Teleogryllus commodus) use the calls of surrounding adult males as a cue of the quality and density of rivals/mates they are likely to encounter. We reared hatchling crickets in six acoustic environments that varied in the density and quality of calls and demonstrate that individuals modified their development rate, phenotype and behaviour at maturity. Males matured more rapidly at a smaller size and called more when reared in a low competition environment. In contrast, males delayed maturity to grow larger when faced with an increased density of high-quality males. Females matured more rapidly when reared in a high density of high-quality males and allocated proportionately more resources towards egg production. A second experiment limiting nutrient availability demonstrates sex-specific allocation shifts in the last stadium when cues are most reliable. Our results demonstrate that the social environment significantly affects allocation strategies and phenotypes, highlighting the importance of juvenile experience and competitive context when examining fitness and selection.

The lifetime costs of increased male reproductive effort: courtship, copulation and the Coolidge effect.

The reproductive effort that a male directs to a familiar female declines over time, suggesting decreasing marginal returns. But is this diminishing returns a function of increasing reproductive costs or decreasing benefits of sustained effort? Here, we use the restoration of male reproductive effort with unfamiliar females to differentiate the role of diminishing returns and lifetime costs of increased reproductive effort of male guppies. We kept males with familiar or unfamiliar females throughout their lives and manipulated their ability to either court or mate with females. We found that increased male reproductive effort with novel mates lead to an immediate trade-off in the form of reduced foraging effort. Further, males able to mate with a series of unfamiliar females had lower lifetime growth, indicating the primary cost of male reproductive effort in guppies arises from copulation rather than courtship. The lifetime growth trade-offs were significant only when males mated with unfamiliar mates, suggesting that male reproductive effort with familiar females declines before it is restricted by physical exhaustion. These findings provide some of the first evidence of longitudinal costs of increased male reproductive effort in a vertebrate.

The effects of familiarity and group size on mating preferences in the guppy, Poecilia reticulata.

In recent years, it has become evident that frequency dependence in the attractiveness of a particular phenotype to mates can contribute to the maintenance of polymorphism. However, these preferences for rare and unfamiliar male phenotypes have only been demonstrated in small, controlled experiments. Here, we tested the preference for unfamiliar mates in groups of six to 96 individuals over 13 days, in the guppy (Poecilia reticulata). We observed individual behaviour in situ to test whether fish discriminate two unfamiliar individuals among many familiar ones. We found that unfamiliar males and females were preferred over the familiar fishes in all groups and that this effect decayed over time. Increasing group sizes and levels of sexual activity did not hamper the preference for unfamiliar mates, providing further support for the role of frequency dependent mate choice in the maintenance of trait polymorphism in natural populations.

Experimental evidence that high levels of inbreeding depress sperm competitiveness.

The effects of inbreeding on sperm quantity and quality are among the most dramatic examples of inbreeding depression. The extent to which inbreeding depression results in decreased fertilization success of a male's sperm, however, remains largely unknown. This task is made more difficult by the fact that other factors, such as cryptic female choice, male sperm allocation and mating order, can also drive patterns of paternity. Here, we use artificial insemination to eliminate these extraneous sources of variation and to measure the effects of inbreeding on the competitiveness of a male's sperm. We simultaneously inseminated female guppies (Poecilia reticulata) with equal amounts of sperm from an outbred (f = 0) male and either a highly (f = 0.59) or a moderately inbred (f = 0.25) male. Highly inbred males sired significantly fewer offspring than outbred males, but share of paternity did not differ between moderately inbred and outbred males. These findings therefore confirm that severe inbreeding can impair the competitiveness of sperm, but suggest that in the focal population inbreeding at order of a brother-sister mating does not reduce a male's sperm competitiveness.

Diagnostic dilemmas in polymyalgia rheumatica.

Polymyalgia rheumatica is a clinical syndrome of proximal muscle pain in older patients that often presents a diagnostic challenge because of the large differential diagnosis, lack of definitive diagnostic criteria, and relatively frequent "atypical" clinical findings, such as peripheral synovitis, distal extremity pain, normal erythrocyte sedimentation rate, and mild weakness. Despite an extensive differential diagnosis that includes endocarditis and steroid-responsive malignant neoplasms, routine laboratory testing should be limited, and a low-dose corticosteroid trial is useful as the final step in the evaluation. The clinical overlap with seronegative rheumatoid arthritis is striking, suggesting that these diagnoses may represent different presentations of a similar disease process. While concurrent asymptomatic temporal arteritis is common, there are no data to support obtaining a temporal artery biopsy in patients with pure polymyalgia rheumatica symptoms.

Metal complexes of bleomycin: evaluation of [Rh-105]-bleomycin for use in targeted radiotherapy.

Bleomycin has been used as a carrier for several radioisotopes; however, its potential for clinical use has been limited either by the in vivo stability of the complexes or the half-life of the isotope used. The chemical, biological, and radiological properties of 105Rhodium appear to make it an ideal choice for targeted radiotherapy. The synthesis and purification of a hereto unreported 105Rhodium-bleomycin (105Rh-BLM) complex is described. The stability of this complex in plasma is sufficient to allow targeted delivery of the radioisotope. 57Cobalt-bleomycin was studied under identical conditions for comparative purposes. The suitability of 105Rh-BLM for targeted therapy, which appears to be limited by the renal clearance of this agent, is discussed.

Oral vaccination of dogs fed canine adenovirus in baits.

Six groups of 5 dogs each were fed dilutions of canine adenovirus-2, either as raw liquid or after insertion into cornmeal baits. By the fourth week after vaccination, 29 of the 30 dogs developed high titers of serum-neutralizing antibodies to the virus.

The price of protein: combining evolutionary and economic analysis to understand excessive energy consumption.

Excessive weight gain appears, thermodynamically at least, straightforward: growing energy intake and/or falling energy expenditure create an energetic surplus, resulting in fat accumulation. The situation is, however, far more complex, with genetic, physiological, social, psychological and economic factors all implicated. Thus the causes of excessive weight gain remain difficult to disentangle. We combine two recent developments from different areas of nutrition research: the study of food prices in relation to energy content and the hypothesis that an evolved propensity to regulate protein intake more strongly than non-protein calories exerts powerful leverage on overall energy intake. We partition the energy content of a range of common supermarket foods, and show that increasing overall energy content only modestly raises the cost of foods, largely as a result of macronutrients having very different costs. Higher food prices are associated with higher protein content and lower carbohydrate content, whereas fat content was not significantly associated with food price. We show that the differential costs of energy from protein and carbohydrates may bias consumers towards diets high in carbohydrate energy, leading them to consume excessive energy to meet their dietary protein needs. We review evidence from physiology, evolution and economics that support our suggestion.

Clinical trials of revascularization therapy in diabetics.

Diabetic patients are a high-risk group for cardiovascular morbidity and mortality, with poorer long-term outcomes, with or without revascularization, than non-diabetic patients. Results from the Bypass Angioplasty Revascularization Investigation (BARI) trial, the largest randomized study of coronary revascularization strategies, showed that diabetic patients with multivessel coronary disease who were undergoing an initial revascularization procedure had a significant long-term survival advantage with coronary artery bypass graft surgery (CABG) compared with percutaneous transluminal coronary angioplasty (PTCA). The 8-year follow-up data from the Emory Angioplasty Versus Surgery Trial (EAST) study, the other major US trial of CABG versus PTCA, and results of other clinical trials that enrolled similar patients are consistent with an advantage for CABG in diabetic patients but not for nondiabetic patients. This benefit is entirely a result of improved cardiac mortality. It is limited to patients receiving an internal mammary artery (IMA) graft and is apparent earlier in insulin-treated patients. The benefit of CABG in diabetic patients may be significantly related to a protective effect on mortality after myocardial infarction, because CABG greatly reduced the risk of death after spontaneous Q-wave myocardial infarction in BARI-eligible diabetic patients (relative risk 0.09, P<0.001), an effect not seen in non-diabetic patients.

Postoperative accumulation of bone in the middle ear: effect on hearing and surgical implications.

Two patients with conductive hearing loss caused by the intraoperative accumulation of bone particles in the middle ear are presented. This complication of otologic surgery may be prevented by an awareness of its possibility and by the temporary blockage of the aditus ad antrum in those operations involving mastoidectomy, even utilizing suction irrigation of the surgical field during the procedure. Once this condition is established, tympanotomy may confirm the presence of bone debris in the middle ear and the material may then be removed, with elimination of the conductive hearing loss.

Is warfarin really underused in patients with atrial fibrillation?

CONTEXT: There is agreement that warfarin decreases stroke risk in patients with atrial fibrillation (AF), but prior studies suggest that warfarin is markedly underused, for unclear reasons. OBJECTIVE: To determine if warfarin is underused in the treatment of patients with atrial fibrillation. DESIGN: Cross-sectional. SETTING: Tertiary care VA hospital. PATIENTS: All patients with a hospital or outpatient diagnosis of AF between 10/1/95 and 5/31/98. DATA COLLECTION: One or more physician investigators reviewed pertinent records for each patient. When any of the 3 investigators thought warfarin might be indicated, the patient's primary care provider completed a survey regarding why warfarin was not used. RESULTS: Of 1,289 AF patients, 844 (65%) had filled at least 1 warfarin prescription. Of the 445 remaining, 19 had died, 5 had inadequate medical records, and 54 received warfarin elsewhere, leaving 367 patients. Of these, 160 had no documented AF, 53 had only a history of AF, and 49 had only transient AF. Of the remaining 105 patients, 17 refused warfarin therapy and 72 had documented contraindications to warfarin use including bleeding risk or history, fall risk, alcohol abuse, or other compliance problems. The reasons for not using warfarin among the 16 patients remaining included provider oversight (n = 4) and various reasons suggesting provider knowledge deficits. CONCLUSION: In contrast to prior studies that suggested that warfarin is markedly underused, we found that few patients with AF and no contraindication to anticoagulation were not receiving warfarin. We believe that differing study methodologies, including the use of physician review and provider survey, may explain our markedly different rate of warfarin underutilization, although local institutional factors cannot be excluded. The findings suggest that primary providers may be far more compliant with the standard of care for patients with atrial fibrillation than previously believed.

Receptor-stimulated phospholipase A2 activation is coupled to influx of external calcium and not to mobilization of intracellular calcium in C62B glioma cells.

C62B rat glioma cells respond to muscarinic cholinergic stimulation with transient inositol phosphate formation and phospholipase A2-dependent arachidonic acid liberation. Since phospholipase A2 is a Ca2+-sensitive enzyme, we have examined the role of the agonist-stimulated Ca2+ response in production of the arachidonate signal. The fluorescent indicator fura-2 was used to monitor changes in cytoplasmic Ca2+ levels ([Ca2+]i) of C62B cells following acetylcholine treatment. In the presence of extracellular Ca2+, acetylcholine induces a biphasic [Ca2+]i response consisting of an initial transient peak that precedes arachidonate liberation and a sustained elevation that outlasts the phospholipase A2 response. The initial [Ca2+]i peak is not altered by the absence of external Ca2+ and therefore reflects intracellular Ca2+ mobilization. The sustained elevation phase is dependent on the influx of external Ca2+; it is lost in Ca2+-free medium and restored on the addition of Ca2+. Pretreating cells with phorbol dibutyrate substantially inhibits acetylcholine-stimulated inositol phosphate formation and the peak [Ca2+]i response without affecting the sustained elevation in [Ca2+]i. This suggests that the release of internal Ca2+ stores by inositol 1,4,5-trisphosphate can be blocked without interfering with Ca2+ influx. Pretreatment with phorbol also fails to affect acetylcholine-stimulated arachidonate liberation, demonstrating that phospholipase A2 activation does not require normal intracellular Ca2+ release. Stimulated arachidonate accumulation is totally inhibited in Ca2+-free medium and restored by the subsequent addition of Ca2+. Pretreatment with verapamil, a voltage-dependent Ca2+ channel inhibitor, also blocks both the sustained [Ca2+]i elevation and arachidonate liberation without altering peak intracellular Ca2+ release. We conclude that the influx of extracellular Ca2+ is tightly coupled to phospholipase A2 activation, whereas large changes in [Ca2+]i due to mobilization of internal Ca2+ stores are neither sufficient nor necessary for acetylcholine-stimulated phospholipase A2 activation.

Immediate countershock treatment of asystole.

While rapid intervention with basic cardiac life support and prompt delivery of prehospital care using advanced cardiac life support (ACLS) have yielded impressive results in the resuscitation of other arrest rhythms, very little improvement has been shown in the rates of resuscitation from asystole. Anecdotal reports list instances in which patients in asystole have had normal cardiac activity restored after defibrillation. Current ACLS protocols for initial evaluation recommend a single-lead "quick-look" interpretation of cardiac rhythm using portable defibrillator paddles. Under these conditions, ventricular fibrillation could masquerade as, or be misinterpreted as, asystole. We report preliminary field results in a medically controlled paramedic system using "quick-look" interpretation and immediate defibrillation of "asystole" by well-trained paramedics. Following initial countershock, standard ACLS protocols for asystole were used. For an eight-month period 119 patients were entered into the study and compared to system controls of asystolic patients presenting in the previous year. While ten patients (8.4%) showed an immediate rhythm change after initial countershock and six of ten reached the hospital with a rhythm and a pulse, no statistically significant comparison could be made regarding improved resuscitation or survival rates. The finding of no statistically significant deterioration of resuscitation or survival rates, however, justifies the continuation of the study.

Differential effects of phorbol ester and diacylglycerols on inositol phosphate formation in C62B glioma cells.

Application of acetylcholine (ACh) to C62B glioma cells results in a rapid release of inositol phosphates. Since this response is transient, we evaluated the possible role of protein kinase C (PKC) in its desensitization. Pretreatment with 100 nM phorbol 12,13-dibutyrate (PDBu) significantly inhibited ACh-induced accumulation of [3H]inositol mono-, bis-, and trisphosphates. However, interpretation of this result as proof of PKC involvement was complicated by the failure of 1,2-dioctanoylglycerol, 1,2-didecanoylglycerol, or 1-oleoyl-2-acetylglycerol pretreatments to mimic the phorbol ester effect. Further evidence against PKC involvement was obtained using the PKC inhibitor sphingosine; PDBu inhibition of inositol phosphate formation was not reversed by sphingosine pretreatments at concentrations which blocked ACh-stimulated PKC activation of inositol trisphosphate phosphatase activity. These results suggest that there may be phorbol effects not mediated by PKC.

Review of the treatment literature for encopresis, functional constipation, and stool-toileting refusal.

This review summarizes the literature on randomized, controlled, published studies involving medical, behavioral, psychological, and biofeedback treatments for encopresis/functional constipation and stool-toileting refusal in preschool-age and school-age children. Nine such studies were located in the literature involving school-age children. No randomized, controlled treatment studies involving preschool-age children have been published. This review revealed no evidence to support the routine use of psychotherapy or anal sphincter biofeedback in the treatment of pediatric fecal elimination dysfunctions, beyond those benefits derived from a comprehensive medical-behavioral intervention. Further, this review indicated that paradoxical constriction of the External Anal Sphincter does not influence the treatment outcome of either biofeedback or medical-behavioral interventions. There are remarkably few controlled treatment outcome studies in this most important clinical area. More research is needed that employs standard treatment outcome variables.