Cellular mechanisms of motor control in the vibrissal system

In this article we discuss the experimental advantages that the vibrissal motor system offers for analysis of motor control and the specializations of this system related to the unique characteristics of whisker movements. Whisker movements are often rhythmic, fast, and bilateral. Movements of individual whiskers have simple characteristics, whereas, movements of the entire vibrissae array are complex and sophisticated. In the last few years, powerful methods for high precision tracking of whisker movements have become available. The whisker musculature is arranged to permit forward movements of individual whiskers and consists—depending on the species—mainly or exclusively of fast contracting, fast fatigable muscle fibers. Whisker motor neurons are located in the lateral facial nucleus and their cellular properties might contribute to the rhythmicity of whisking. Numerous structures provide input to the lateral facial nucleus, the most mysterious and important one being the putative central pattern generator (CPG). Although recent studies identified candidate structures for the CPG, the precise identity and the functional organization of this structure remains uncertain. The vibrissa motor cortex (VMC) is the largest motor representation in the rodent brain, and recent work has clarified its localization, subdivisions, cytoarchitectonics, and connectivity. Single-cell stimulation experiments in VMC allow determining the cellular basis of cortical motor control with unprecedented precision. The functional significance of whisker movements remains to be determined.     

From genome to proteome: developing expression clone resources for the human genome

Human Molecular Genetics (2006) 15,     

Bacterial Heterogeneity Is a Requirement for Host Superinfection by the Lyme Disease Spirochete

In nature, mixed Borrelia burgdorferi infections are common and possibly can be acquired by either superinfection or coinfection. Superinfection by heterologous B. burgdorferi strains has been established experimentally, although the ability of homologous B. burgdorferi clones to superinfect a host has not been studied in detail. Information regarding any potential immune barriers to secondary infection also currently is unavailable. In the present study, the ability to superinfect various mouse models by homologous wild-type clones was examined and compared to superinfection by heterologous strains. To assess the ability of homologous B. burgdorferi clones to successfully superinfect a mouse host, primary- and secondary-infecting spirochetes were recovered via in vitro cultivation of collected blood or tissue samples. This was accomplished by generating two different antibiotic-resistant versions of the wild-type B31-A3 clone in order to distinguish superinfecting B. burgdorferi from primary-infecting spirochetes. The data demonstrate an inability of homologous B. burgdorferi to superinfect immunocompetent mice as opposed to heterologous strains. Attempts to superinfect different types of immunodeficient mice with homologous B. burgdorferi indicate that the murine innate immune system represents a major barrier to intrastrain superinfection. Consequently, the possibility of innate immunity as a driving force for B. burgdorferi heterogeneity during the enzootic cycle is discussed.     

A single-session testing protocol to determine critical power and W′

Purpose

Critical power (CP), and the finite capacity to perform work above CP (W′), can be determined using a 3-min “all-out” cycling test (3MT). This protocol requires two laboratory visits: an incremental exercise test, followed by a 3MT on a separate day. The purpose of this study was to establish whether an incremental exercise test and a 3MT performed during a single laboratory visit can be used to accurately determine CP and W′.

Methods

Twelve participants completed two experimental protocols: (1) Combined protocol: an incremental exercise test followed by a 3MT, with 20 min of recovery between exercise bouts; and (2) Independent protocol: the conventional 3MT protocol, performed on a separate day.

Results

CP determined from the Combined (254 ± 117 W) and Independent (256 ± 118 W) protocols were not different (p = 0.40). Similarly, W′ was not different (p = 0.96) between the Combined (13.7 ± 3.9 kJ) and Independent (13.7 ± 4.5 kJ) protocols. Linear regression revealed a strong level of measurement agreement between the protocols for CP and W′, evidenced by high R ² values (≥0.85) and marginal standard errors of the estimates (CP = 5 W; W′ = 1.81 kJ).

Conclusion

A Combined protocol, consisting of an incremental exercise test followed by a 3MT, provides an accurate and valid method to determine an individual’s CP and, to a lesser extent, W′. Furthermore, this protocol permits the measurement of the gas-exchange threshold and peak O₂ uptake and, consequently, the moderate, heavy, and severe exercise-intensity domains may be defined within a single exercise-testing session.     

Use of Paid Child Care Health Care Consultants in Early Care and Education Settings: Results of a National Study Comparing Provision of Health Screening Services Among Head Start and Non-Head Start Centers

IntroductionChild care health consultants (CCHCs) are health professionals who provide consultation and referral services to child care programs. The use of CCHCs has been recommended as an important component of high-quality child care. The purpose of this study was to examine the potential association between the use of paid CCHCs and child care center director reports of (a) center maintenance of health records and emergency procedures and (b) center facilitation of health screenings and assessments.MethodA national, randomized telephone survey of directors of 1822 licensed child care center directors was conducted.ResultsWith a response rate of 93%, most directors (72.7%) reported that they did not employ a CCHC. However, directors employing CCHCs were more likely to report provision of health-promoting screenings and assessments for children in their center. This pattern held true for both Head Start and non-Head Start centers.DiscussionThis study suggests that CCHCs can serve as health promotion advocates in early care and education settings, helping centers establish appropriate policies and arranging for health assessments and screenings for children.     

Caspases as Therapeutic Targets in Alzheimer’s Disease: Is It Time to “Cut” to the Chase?

Mounting evidence suggests the involvement of caspases in the disease process associated with Alzheimer’s disease (AD). The activation of caspases may be responsible for the neurodegeneration associated with AD and several recent studies have suggested that caspases may also play a role in promoting pathogenic mechanisms underlying this disease. Thus, caspase activation and cleavage of the amyloid precursor protein (APP) and tau may facilitate both the production of beta-amyloid (Aβ) as well as the formation of neurofibrillary tangles (NFTs). Because the activation of caspases in AD may be a proximal event that is not just associated with neurodegeneration, caspases are potential therapeutic targets for the treatment of this disorder. In this review, studies documenting the role of caspases in the AD brain will be discussed. In this context, a discussion of the therapeutic value of targeting caspase inhibition in the treatment of AD will be evaluated including drug targets, delivery and selectivity.     

Conduct problems in adolescence: three domains of inhibition and effect of gender

Behavioral and neuropsychological evidence has often shown that children with conduct disorder drawn from clinical populations show problems with impulsivity and are impaired in motor tasks of inhibitory control. We explored the relation between conduct problems and inhibitory deficits in a community sample. Three domains of inhibition were explored in 54 adolescents with conduct problems compared to 53 age, IQ, sex, school, and ethnicity matched controls in 2 geographical areas. Motor response inhibition was assessed using the Stop task, verbal inhibition using the Hayling Sentence Completion test, and cognitive interference inhibition using the Stroop task. Adolescents with conduct problems showed deficits in executive and inhibitory processes of the motor response inhibition task, but were unimpaired in cognitive or verbal inhibitory control. No sex differences were observed and impairments were independent of IQ or geographical location. Findings suggest that motor deficits, rather than higher cognitive forms of inhibitory control, are a specific deficit in children with conduct problems, that girls are as affected as boys, and that motor impulsiveness is a dimensional trait associated with conduct problems, as it is also observed in the community.