How do infants adapt to loading of the limb during the swing phase of stepping?

Previous results from this laboratory have shown that human infants (<12 mo old) respond appropriately to transient changes in sensory input during stepping. We examined how infants adapted to a more enduring change in sensory input by applying load to one limb during stepping. A small weight (500-900 g) was strapped around the lower leg of infants aged 3-11 mo. Stepping with the weight on was recorded on the treadmill for a period of 0.5-3 min. The weight was then quickly detached during stepping, and the immediate response to unexpected loss of the weight recorded. Three-segment dynamic analysis of leg motion was used to estimate hip, knee, and ankle torques during swing in the sagittal plane. All infants adapted to the additional load on the leg by immediately increasing the generation of hip and knee flexor muscle torques. When the weight was removed, 7 of the 22 infants tested exhibited an after-effect (high stepping) in the first step after removal of the weight. The after-effect was manifested as an increase in toe trajectory height and hip flexion and coincided with higher hip flexor muscle torque in early swing. In an additional series of control experiments using seven infants, after-effects were shown to be unrelated to a sudden change in cutaneous input with removal of the weight. The presence of an after-effect indicates that some infants made an enduring adaptation to their stepping pattern that is revealed with the unexpected removal of the weight.     

How do animals actually solve the T maze?

Rats were trained on a reinforced, delayed alternation T-maze task in the presence (cue group) or absence (no-cue group) of salient extramaze landmarks. A surprising finding was that the acquisition and memory performance of the 2 groups did not differ. Manipulations of the extramaze landmarks for the cue group suggested that, although landmarks were used to guide behavior, other sources of information were also used normally. The no-cue group was able to perform the task at above-chance levels even when extramaze, intramaze, and inertial sources of orientation were manipulated. These results suggest that memory performance on the T maze does not rely exclusively on the processing of allocentric spatial relationships in the maze environment.     

Do constraints associated with the locomotor habitat drive the evolution of forelimb shape? A case study in musteloid carnivorans

Convergence in morphology can result from evolutionary adaptations in species living in environments with similar selective pressures. Here, we investigate whether the shape of the forelimb long bones has converged in environments imposing similar functional constraints, using musteloid carnivores as a model. The limbs of quadrupeds are subjected to many factors that may influence their shape. They need to support body mass without collapsing or breaking, yet at the same time resist the stresses and strains induced by locomotion. This likely imposes strong constraints on their morphology. Our geometric morphometric analyses show that locomotion, body mass and phylogeny all influence the shape of the forelimb. Furthermore, we find a remarkable convergence between: (i) aquatic and semi‐fossorial species, both displaying a robust forelimb, with a shape that improves stability and load transfer in response to the physical resistance imposed by the locomotor environment; and (ii) aquatic and arboreal/semi‐arboreal species, with both groups displaying a broad capitulum. This augments the degree of pronation/supination, an important feature for climbing as well as grasping and manipulation ability, behaviors common to aquatic and arboreal species. In summary, our results highlight how musteloids with different locomotor ecologies show differences in the anatomy of their forelimb bones. Yet, functional demands for limb movement through dense media also result in convergence in forelimb long‐bone shape between diverse groups, for example, otters and badgers.     

How do Alliaceae stabilize their chromosome ends in the absence of TTTAGGG sequences?

TheArabidopsis-type telomeric repeats (5-TTTAGGG-3) are highly conserved. In most families of different plant phyla they represent the basic sequence of telomeres that stabilize and protect the chromosome termini. The results presented here show that Alliaceae and some related liliaceous species have no tandemly repeated TTTAGGG sequences. Instead, their chromosomes reveal highly repetitive satellite and/or rDNA sequences at the very ends. These apparently substitute the original plant telomeric sequences in Alliaceae. Both sequence types are very active in homologous recombination and may contribute to the stabilization of chromosome termini via compensation of replication-mediated shortening.Accepted for publication by M. Schmid     

How do young adults perceive the risk of chlamydia infection? A qualitative study

Objectives. This study aimed to improve understanding of how young UK genito‐urinary medicine (GUM) patients perceive the risk of chlamydia, and identify implications for health education. Design. A qualitative methodology was chosen. Methods. Semi‐structured interviews with 27 respondents aged 16–22 years old were conducted. Data were subjected to thematic analysis. Results. Respondents made assessments of the perceived seriousness of, and their personal susceptibility to, chlamydia infection. Judgements about seriousness were related to beliefs about the controllability of symptoms and the long‐term health consequences of infection. Susceptibility estimates were related to beliefs about the extent to which personal exposure put them in contact with chlamydia, and about the prevalence of infection amongst their peer group. This is consistent with the content of illness risk representations proposed by Cameron (2003) . Respondents demonstrated some beliefs, which appeared to influence perceptions of seriousness and susceptibility in unhelpful ways. Conclusions. Young people may be underestimating their risk of chlamydia infection due to the presence of unhelpful beliefs. Dialogue between health professionals and patients within GUM clinics, or through consultations as part of the National Chlamydia Screening Programme (NCSP), could provide vehicles to deliver health education to target these. Suggested health education includes highlighting false reassurance provided by treatment beliefs and exposing the fallibility of using overt characteristics to judge the likelihood that a potential sexual partner poses a risk of infection.     

T-cell receptors: on the track of Tau?

Although the structure of the T cell's receptor for antigen is still a puzzle, antigen-binding material can be isolated from T cells. Now several different kinds of independently isolated ‘T-cell product’ have been found to have antigens in common. Are these determinants of a constant region on an elusive ‘IgT’?     

How do I manage nocardiosis?

BackgroundNocardiosis is a rare infection that is often difficult to treat and may be life-threatening. There is no consensus on its management.ObjectivesOur aim was to provide the current evidence for the diagnosis and management of individuals with nocardiosis, and to propose a management approach for this uncommon infection.SourcesWe systematically searched the medical literature on nocardiosis for studies published between 2010 and 2020 and describing ten or more individuals.ContentNocardiosis, a primarily opportunistic infection which may occur in immunocompetent persons, most commonly involves the lungs and frequently disseminates to other sites including the central nervous system. The reference standard for Nocardia species identification is molecular biology, and the preferred method for antibiotic susceptibility testing (AST) is broth microdilution. Monotherapy seems appropriate for patients with primary skin nocardiosis or non-severe pulmonary disease; we reserve a multidrug regimen for more severe infections. Species identification and AST results are often missing at initiation of antibiotics. Trimethoprim-sulfamethoxazole is the preferred agent for initial therapy, because Nocardia is very often susceptible to this agent, and because it has been the keystone of nocardiosis treatment for years. Linezolid, to which Nocardia is almost always susceptible, may be an alternative. When combination therapy is required, the repertoire of companion drugs includes third-generation cephalosporins, amikacin and imipenem. Therapeutic modifications should take into account clinical response to initial therapy and AST results. Treatment duration of 6 months is appropriate for most situations, but longer durations are preferred for disseminated nocardiosis and shorter durations are reasonable in low-risk situations. Secondary prophylaxis may be considered in selected individuals with permanent immunosuppression.ImplicationsWe hereby provide the clinician with an easy-to-use algorithm for the management of individuals with nocardiosis. We also illuminate gaps in evidence and suggest future research directions.     

How do inhibitory phosphatases work?

We present a hypothesis regarding the mode of induction of the inhibitory phosphatases SHP-1 and SHIP in hematopoietic cells. One mode is a general one in which the phosphatase regulates but does not abort signal transduction and biology. Regulator phosphatases are induced by directly or indirectly engaging the amino acid motifs present in the activating receptor, and act to control the biochemical and biological output. The other mode of induction is a specific one, which critically involves paired co-clustering of activating and inhibitory receptors. Phosphatases working in this way act only under conditions of paired co-clustering of activating and inhibitory receptors, and directly bind amino acid motifs present in the inhibitory receptor. However, this mode of induction is apparently more efficient, as cellular activation is completely aborted. This review presents several examples of each mode of inhibition and speculates on their mechanisms.     

How well do healthcare professionals know of the priorities of their older patients regarding treatment outcomes?

ObjectivesFor shared decision making, it is crucial to identify patients’ priorities regarding health outcomes. Our aim was to study whether healthcare professionals know these priorities.MethodsIn this cross-sectional study we included older patients who had to make a treatment decision, their general practitioners (GPs) and their medical specialists. Agreement between the patients’ main health outcome as prioritised by using the Outcome Prioritization Tool (OPT) and the perception of the same outcome by their healthcare professionals.ResultsEighty-seven patients were included. Median age was 76 years, 87.4% of patients presented with malignant disease. The majority prioritised maintaining independence (51.7%), followed by extending life (27.6%). The agreement between patients and healthcare professionals was low (GPs 41.7%, kappa 0.067, p = 0.39), medical specialists 40.3%, kappa 0.074, p = 0.33). Positively related to agreement was patient’s age > 75, and a longer relation with their patients (for GPs), and the patient having no partner (for medical specialist). Having a malignant disease, dependent living and functional deficits were negatively related to agreement.ConclusionsHealthcare professionals have poor perceptions of their patients’ priorities.Practice implicationsTo realise patient-centered care, it is crucial to discuss priorities explicitly with all patients.