bluuebunny/crossref_metadata_2025_split huggingface dataset:
Voices of the dead: complex nonlinear vocal signals from the larynx of an ultrasonic frog
Authors: Suthers Roderick A. , Narins Peter M. , Lin Wen-Yu , Schnitzler Hans-Ulrich , Denzinger Annette , Xu Chun-He , Feng Albert S. 
Published: December 2006

SUMMARYMost anurans are highly vocal but their vocalizations are stereotyped and simple with limited repertoire sizes compared with other vocal vertebrates,presumably because of the limited mechanisms for fine vocal motor control. We recently reported that the call of the concaveeared torrent frog (Amolops tormotus Fei) is an exception in its seemingly endless variety, musical warbling quality, extension of call frequency into the ultrasonic range and the prominence of subharmonics, chaos and other nonlinear features. We now show that the major spectral features of its calls, responsible for this frog's vocal diversity, can be generated by forcing pressurized air through the larynx of euthanized males. Laryngeal specializations for ultrasound appear to include very thin portions of the medial vocal ligaments and reverse sexual size dimorphism of the larynx - being smaller in males than in females. The intricate morphology of the vocal cords, which changes along their length,suggests that nonlinear phenomena probably arise from complex nonlinear oscillatory regimes of separate elastically coupled masses. Amolopsis thus the first amphibian for which the intrinsic nonlinear dynamics of its larynx - a relatively simple and expedient mechanism - can account for the species' call complexity, without invoking sophisticated neuromuscular control.
Foraging Blainville's beaked whales (Mesoplodon densirostris)produce distinct click types matched to different phases of echolocation
Authors: Johnson M. , Madsen P. T. , Zimmer W. M. X. , de Soto N. Aguilar , Tyack P. L. 
Published: December 2006

SUMMARYBlainville's beaked whales (Mesoplodon densirostris Blainville)echolocate for prey during deep foraging dives. Here we use acoustic tags to demonstrate that these whales, in contrast to other toothed whales studied,produce two distinct types of click sounds during different phases in biosonar-based foraging. Search clicks are emitted during foraging dives with inter-click intervals typically between 0.2 and 0.4 s. They have the distinctive form of an FM upsweep (modulation rate of about 110 kHz ms-1) with a -10 dB bandwidth from 26 to 51 kHz and a pulse length of 270 μs, somewhat similar to chirp signals in bats and Cuvier's beaked whales (Ziphius cavirostris Cuvier), but quite different from clicks of other toothed whales studied. In comparison, the buzz clicks, produced in short bursts during the final stage of prey capture, are short (105 μs)transients with no FM structure and a -10 dB bandwidth from 25 to 80 kHz or higher. Buzz clicks have properties similar to clicks reported from large delphinids and hold the potential for higher temporal resolution than the FM clicks. It is suggested that the two click types are adapted to the separate problems of target detection and classification versus capture of low target strength prey in a cluttered acoustic environment.
DNA photorepair in echinoid embryos: effects of temperature on repair rate in Antarctic and non-Antarctic species
Authors: Lamare Miles D. , Barker Mike F. , Lesser Michael P. , Marshall Craig 
Published: December 2006

SUMMARY
To determine if an Antarctic species repairs DNA at rates equivalent to warmer water equivalents, we examined repair of UV-damaged DNA in echinoid embryos and larvae. DNA repair by photoreactivation was compared in three species Sterechinus neumayeri (Antarctica), Evechinus chloroticus (New Zealand) and Diadema setosum (Tropical Australia) spanning a latitudinal gradient from polar (77.86°S) to tropical (19.25°S) environments. We compared rates of photoreactivation as a function of ambient and experimental temperature in all three species, and rates of photoreactivation as a function of embryonic developmental stage in Sterechinus. DNA damage was quantified from cyclobutane pyrimidine dimer (CPD) concentrations and rates of abnormal embryonic development. This study established that in the three species and in three developmental stages of Sterechinus, photoreactivation was the primary means of removing CPDs, was effective in repairing all CPDs in less than 24 h, and promoted significantly higher rates of normal development in UV-exposed embryos. CPD photorepair rate constant (k) in echinoid embryos ranged from 0.33 to 1.25 h-1, equating to a time to 50% repair of between 0.6 and 2.1 h and time to 90%repair between 3.6 and 13.6 h. We observed that experimental temperature influenced photoreactivation rate. In Diadema plutei, the photoreactivation rate constant increased from k=0.58 h-1to 1.25 h-1, with a Q10=2.15 between 22°C and 32°C. When compared among the three species across experimental temperatures (-1.9 to 32°C), photoreactivation rates vary with a Q10=1.39. Photoreactivation rates were examined in three developmental stages of Sterechinus embryos, and while not significantly different, repair rates tended to be higher in the younger blastula and gastrula stages compared with later stage embryos. We concluded that photoreactivation is active in the Antarctic Sterechinus, but at a significantly slower (non-temperature compensated) rate. The low level of temperature compensation in photoreactivation may be one explanation for the relatively high sensitivity of Antarctic embryos to UV-R in comparison with non-Antarctic equivalents.
A sex-linked allele, autosomal modifiers and temperature-dependence appear to regulate melanism in male mosquitofish (Gambusia holbrooki)
Authors: Horth Lisa 
Published: December 2006

SUMMARYAbout 1% of male mosquitofish (Gambusia holbrooki) express melanic(mottled-black) body coloration, which differs dramatically from the wild-type, silvery-gray coloration. Here, I report on the genetic inheritance pattern of melanic coloration, which indicates Y-linkage, and at least one autosomal modifier. Phenotypic expression of melanism is also affected by temperature. Expression is constitutive (temperature insensitive) in some populations, inducible (temperature sensitive) in others. Constitutive and inducible expression occur among geographically proximal populations. However,males from any single population demonstrate the same constitutive or inducible expression pattern as one another. The F1 males from inter-population crosses demonstrate temperature-related expression patterns like their sires'. As well, the sex ratio of melanic males' progeny differs among populations. Here, inter-population crosses demonstrate a sex-ratio bias in the same direction as intra-population crosses of the sire population. About 20% of the male progeny of melanic sires express the wild-type phenotype. These silver F1 males sire only silver offspring, suggestive of loss of the melanin gene in F1 males from crossover between sex chromosomes,or control by additional modifiers, or involvement of additional factors. In nature, melanic males persist at very low frequencies. The data collected here on heritability indicate that genetic factors contribute to the rarity of melanic male mosquitofish.
Generation of extreme ultrasonics in rainforest katydids
Authors: Montealegre-Z Fernando , Morris Glenn K. , Mason Andrew C. 
Published: December 2006

SUMMARYThe calling song of an undescribed Meconematinae katydid (Tettigoniidae)from South America consists of trains of short, separated pure-tone sound pulses at 129 kHz (the highest calling note produced by an Arthropod). Paradoxically, these extremely high-frequency sound waves are produced by a low-velocity movement of the stridulatory forewings. Sound production during a wing stroke is pulsed, but the wings do not pause in their closing, requiring that the scraper, in its travel along the file, must do so to create the pulses. We hypothesize that during scraper pauses, the cuticle behind the scraper is bent by the ongoing relative displacement of the wings, storing deformation energy. When the scraper slips free it unbends while being carried along the file and its deformation energy contributes to a more powerful,higher-rate, one-tooth one-wave sound pulse, lasting no more than a few waves at 129 000 Hz. Some other katydid species make pure-tone ultrasonic pulses. Wing velocities and carriers among these pure-tone species fall into two groups: (1) species with ultrasonic carriers below 40 kHz that have higher calling frequencies correlated with higher wing-closing velocities and higher tooth densities: for these katydids the relationship between average tooth strike rate and song frequency approaches 1:1, as in cricket escapement mechanisms; (2) a group of species with ultrasonic carriers above 40 kHz (that includes the Meconematinae): for these katydids closing wing velocities are dramatically lower and they make short trains of pulses, with intervening periods of silence greater than the duration of the pulses they separate. This signal form may be the signature of scraper-stored elastic energy.
Corticosterone selectively decreases humoral immunity in female eiders during incubation
Authors: Bourgeon Sophie , Raclot Thierry 
Published: December 2006

SUMMARYImmunity is hypothesized to share limited resources with other physiological functions and this may partly account for the fitness costs of reproduction. Previous studies have shown that the acquired immunity of female common eider ducks (Somateria mollissima) is suppressed during their incubation, during which they entirely fast. Corticosterone was proposed to be an underlying physiological mechanism for such immunosuppression. Therefore,the current study aimed to assess the effects of exogenous corticosterone on acquired immunity in captive eiders. To this end, females were implanted with corticosterone pellets at different stages of their incubation fast. We measured total immunoglobulin levels, T-cell-mediated immune response, body mass and corticosterone levels in these females and compared them with those of control females prior to and after manipulation (i.e. corticosterone pellet implantation). To mimic corticosterone effects on body mass, we experimentally extended fasting duration in a group of females termed `late fasters'. Implanted females had corticosterone levels 6 times higher and lost 35% more mass than control females. Corticosterone levels in `late fasters' were similar to those in control females but body mass was 8% lower in the former. The decrease in the immunoglobulin levels of corticosterone implanted females was twice as high as in control females, while the T-cell-mediated immune response was not significantly affected by the treatment. We found a decrease in the T-cell-mediated immune response only in `late fasters' (by 60%), while the immunoglobulin level was not lower in this group than in corticosterone implanted or control females. Our study shows that in incubating eiders,exogenous corticosterone only decreased humoral immunity. We suggest that the immunosuppressive effect of corticosterone could be mediated through its effects on body reserves. Further experiments are required to determine the relationship between body condition and immune system in fasting birds.
Herpes Simplex Virus Infections in Preterm Infants
Authors: O'Riordan Declan P. , Golden W. Christopher , Aucott Susan W. 
Published: December 2006

OBJECTIVE. Neonatal herpes simplex virus infections cause significant neonatal mortality and morbidity, but the course and prognosis in preterm infants is not well documented. We performed a retrospective review of herpes simplex virus infections at out institution within the first 30 days after birth in infants who were born at &lt;37 weeks to help better define the symptoms and signs of herpes simplex virus infections in preterm infants and to assist in prognosis.METHODS. Hospital databases were reviewed to identify culture- or polymerase chain reaction–proven cases of herpes simplex virus-1 or herpes simplex virus-2 infections that occurred in preterm newborns between 1989 and 2003. Maternal and neonatal histories, clinical features, and laboratory results were reviewed systematically.RESULTS. Ten preterm singletons and a set of twins were infected with herpes simplex virus-2 during the first month after birth. No mother had herpes simplex virus lesions at delivery, but a history of genital herpes simplex or other sexually transmitted infections was prevalent among the mothers. Infants presented with either disseminated disease or encephalitis. All infants with disseminated disease (n = 9) died, whereas the 3 infants with encephalitis survived. All infants in the cohort developed respiratory distress, and consistent with the prominence of respiratory symptoms, viral cultures of the respiratory tract were consistently positive. Ten of 12 infants received acyclovir, but despite treatment within 48 hours of symptoms, infants with disseminated disease deteriorated rapidly and died. Two of 3 infants who received high-dosage (60 mg/kg per day) acyclovir survived.CONCLUSIONS. Herpes simplex virus infections in preterm infants usually present during the first 2 weeks of life with respiratory distress and a high incidence of disseminated disease. Viral respiratory cultures have a high yield for documentation of infection. The morbidity of herpes simplex virus in this population may be attributable to a relatively immature immune system in this population. Additional studies are necessary to delineate the evolution of herpes simplex virus disease in preterm infants and the role of antiviral therapy in mitigating the sequelae of herpes simplex virus infections in this population.
Brief Hospitalization and Pulse Oximetry for Predicting Amoxicillin Treatment Failure in Children with Severe Pneumonia
Authors: Fu Linda Y. , Ruthazer Robin , Wilson Ira , Patel Archana , Fox LeAnne M. , Tuan Tran Anh , Jeena Prakash , Chisaka Noel , Hassan Mumtaz , Lozano Juan , Maulen-Radovan I , Thea Donald M. , Qazi Shamim , Hibberd Patricia 
Published: December 2006

OBJECTIVE. In settings with limited assessment tools, we sought to determine whether early clinical signs and symptoms and blood oxygen saturation would predict amoxicillin treatment failure in children with severe pneumonia (as defined by the World Health Organization).
METHODS. Data were from a previously reported, multinational trial of orally administered amoxicillin versus injectable penicillin for the treatment of World Health Organization–defined severe pneumonia in children 3 to 59 months of age. We assessed all 857 participants assigned randomly to the experimental amoxicillin arm. Six multivariate logistic regression models were created and evaluated for their ability to predict failure after 48 hours of therapy. Regression models included vital signs, symptoms, and laboratory data collected at baseline and after 12 or 24 hours of observation. Oxygen saturation data were included in 3 models.
RESULTS. Clinical treatment failure occurred for 18% of children. Younger age, increased initial respiratory rate, and baseline hypoxia predicted treatment failure in all models. Data available after 24 hours improved the ability to predict failure compared with data available at baseline or 12 hours. The inclusion of oximetry data improved the predictive ability at baseline, 12 hours, and 24 hours. The ability to predict failure after 12 hours of observation with oximetry data was similar to the predictive ability after 24 hours without pulse oximetry data.
CONCLUSIONS. Assessment of clinical parameters at presentation and after 24 hours improved the ability to predict clinical failure of oral amoxicillin therapy, compared with assessment at presentation alone or at presentation and after only 12 hours, for children with World Health Organization–defined severe pneumonia.
Pervasive Developmental Disorder, Behavior Problems, and Psychotropic Drug Use in Children and Adolescents With Mental Retardation
Authors: de Bildt Annelies , Mulder Erik J. , Scheers Tom , Minderaa Ruud B. , Tobi Hilde 
Published: December 2006

OBJECTIVE. This study investigated the interrelationship between psychopharmacotherapy in general and the use of specific psychotropic drugs and pervasive developmental disorder and other behavior problems in children and adolescents with mental retardation.
METHODS. A total of 862 participants 4 to 18 years of age, including all levels of mental retardation, were recruited through facilities for children with mental retardation in Friesland, the Netherlands. Information on medication was collected through parent interviews. Behavior problems were investigated with a standardized parent questionnaire (Developmental Behavior Checklist). A pervasive developmental disorder classification was based on the Pervasive Developmental Disorder in Mental Retardation Scale, completed by psychologists or teachers. Logistic regression analysis was used to investigate the relationship between the use of psychotropic drugs and pervasive developmental disorder and other behavioral problems, in the presence of possible confounders.
RESULTS. One of 10 participants used psychotropic medication. The main factors associated with psychotropic drug use were pervasive developmental disorder and disruptive behavior. The level of functioning was also associated. Self-absorbed behavior was statistically significantly associated with clonidine use and disruptive behavior with stimulant use. Pervasive developmental disorder and communication problems were the main factors associated with the use of antipsychotic drugs. Age also played a role, whereas gender, living situation, and level of mental retardation did not.
CONCLUSIONS. Antipsychotic drugs were associated with pervasive developmental disorder, whereas clonidine and stimulants were associated with self-absorbed and disruptive behavior, respectively. Although clonidine and risperidone are not registered for the problems reported and the other nonstimulants were only sometimes used on-label, their use was associated with specific psychiatric or behavioral problems.
Earlier Apgar Score Increase in Severely Depressed Term Infants Cared for in Swedish Level III Units With 40% Oxygen Versus 100% Oxygen Resuscitation Strategies: A Population-Based Register Study
Authors: Hellström-Westas Lena , Forsblad Kristina , Sjörs Gunnar , Saugstad Ola Didrik , Björklund Lars J. , Maršál Karel , Källén Karin 
Published: December 2006

OBJECTIVES. The aim of this study was to evaluate whether a resuscitation strategy based on administration of 40% oxygen influences mortality rates and rates of improvement in 5-minute Apgar scores, compared with a strategy based on 100% oxygen administration.
METHODS. A population-based study evaluated data from 4 Swedish perinatal level III centers during the period of 1998 to 2003. During this period, the centers used either of 2 resuscitation strategies (initial oxygen administration of 40% or 100%). Live-born, singleton, term infants with 1-minute Apgar scores of &lt;4, with a birth weight appropriate for gestational age, and without major malformations were included in the study (n = 1223).
RESULTS. Infants born in hospitals using a 40% oxygen strategy had a more rapid Apgar score increase than did infants born in hospitals using a 100% oxygen strategy; however, no difference remained at 10 minutes. The mean Apgar score increased from 2.01 at 1 minute to 6.74 at 5 minutes in the 2 hospitals initiating resuscitation with 40% oxygen, compared with 2.01 to 6.38 in the 2 hospitals using 100% oxygen, with a mean difference in Apgar score increases of 0.36. At 5 minutes, 44.3% of infants born in the hospitals using 100% oxygen had an Apgar score of &lt;7, compared with 34.0% of infants at the hospitals using 40% oxygen. At 10 minutes, the mean Apgar scores were 8.16 at the hospitals using 40% oxygen and 8.07 at the hospitals using 100% oxygen. There were no significant differences in rates of neonatal death, hypoxic ischemic encephalopathy, or seizures in relation to the 2 oxygen strategies.
CONCLUSION. Severely depressed term infants born in hospitals initiating resuscitation with 40% oxygen had earlier Apgar score recovery than did infants born in hospitals using a 100% oxygen strategy.
Absence of the Wild-type Allele (192 Base Pairs) of a Polymorphism in the Promoter Region of the IGF-I Gene but Not a Polymorphism in the Insulin Gene Variable Number of Tandem Repeat Locus Is Associated With Accelerated Weight Gain in Infancy
Authors: Landmann Eva , Geller Frank , Schilling Jutta , Rudloff Silvia , Foeller-Gaudier Eleonore , Gortner Ludwig 
Published: December 2006

OBJECTIVE. Our goal was to investigate whether a polymorphism in the insulin-like growth factor I promoter gene (IGF-I, wild-type, 192 base pairs) and in the insulin gene (INS) variable number of tandem repeat locus influence birth weight and weight gain in infancy.
PATIENTS AND METHODS. We obtained genomic DNA from 768 children. Exclusion criteria were multiple births, gestational diabetes, maternal diabetes, gestational age &lt;37 weeks, &gt;42 weeks, or unclear, and any condition potentially influencing weight gain. SD scores were calculated and adjusted for gestational age and gender. A gain in SD scores for weight between birth and 1 year &gt;0.67 SD scores was defined as accelerated weight gain. Genotyping was performed by fragment length analysis (IGF-I) and by fragment length analysis after using a restriction enzyme-based assay (INS variable number tandem repeat).
RESULTS. Accelerated weight gain was present in 205 of 768 children. IGF-I and INS variable number tandem repeat genotype were not associated with birth weight. The IGF-I 192-base pair allele was less frequent in children with accelerated weight gain and was shown to reduce the risk for accelerated weight gain in a logistic regression model.
CONCLUSION. The IGF-I 192-base pair allele may reduce the risk for rapid weight gain in early infancy.
Pediatric Residency Duty Hours Before and After Limitations
Authors: Cull William L. , Mulvey Holly J. , Jewett Ethan A. , Zalneraitis Edwin L. , Allen Carl E. , Pan Richard J. 
Published: December 2006

OBJECTIVES. The goals were to examine pediatric resident and program director experiences implementing the Accreditation Council for Graduate Medical Education work hour limits and to compare duty hours, moonlighting, and fatigue before and after the limits became effective.METHODS. National random samples of 500 pediatric residents who graduated in 2002 and in 2004 were surveyed to compare resident duty hours and fatigue before and after the Accreditation Council for Graduate Medical Education limits were implemented. In addition, all US pediatric residency program directors were surveyed at the end of the 2003/2004 academic year, to provide a complementary retrospective examination of limit implementation.RESULTS. Totals of 65%, 61%, and 83% of 2002 residents, 2004 residents, and program directors, respectively, responded. The proportion of residents who reported working &gt;80 hours per week declined from 49% for NICU/PICU rotations before the limits to 18% after limit implementation. Resident well-being was the factor identified most often by both residents and program directors as being improved since the limitations. Multivariate modeling also showed reductions in the proportions of residents who reported falling asleep while driving from work or making errors in patient care because of fatigue. Overall, 89% of pediatric residents and program directors reported that the current system is effective in ensuring appropriate working hours.CONCLUSIONS. Since the Accreditation Council for Graduate Medical Education duty hour limits went into effect, pediatric residents report working fewer hours and making fewer patient care errors because of fatigue. Although room for additional improvement remains, the experiences of residents and program directors suggest that implementation of the Accreditation Council for Graduate Medical Education limits in pediatric residency programs is improving resident well-being.