The development of an isokinetic squat device: reliability and relationship to functional performance

The aims of the present study were: (1) to assess aerobic metabolism in paraplegic (P) athletes (spinal lesion level, T4–L3) by means of peak oxygen uptake (V˙O_2peak) and ventilatory threshold (VT), and (2) to determine the nature of exercise limitation in these athletes by means of cardioventilatory responses at peak exercise. Eight P athletes underwent conventional spirographic measurements and then performed an incremental wheelchair exercise on an adapted treadmill. Ventilatory data were collected every minute using an automated metabolic system: ventilation (l · min⁻¹), oxygen uptake (V˙O₂, l · min⁻¹, ml · min⁻¹ · kg⁻¹), carbon dioxide production (V˙CO₂, ml · min⁻¹), respiratory exchange ratio, breathing frequency and tidal volume. Heart rate (HR, beats · min⁻¹) was collected with the aid of a standard electrocardiogram. V˙O_2peak was determined using conventional criteria. VT was determined by the breakpoint in the V˙CO₂−V˙O₂ relationship, and is expressed as the absolute VT (V˙O₂, ml · min⁻¹ · kg⁻¹) and relative VT (percentage of V˙O_2peak). Spirometric values and cardioventilatory responses at rest and at peak exercise allowed the measurement of ventilatory reserve (VR), heart rate reserve (HRr), heart rate response (HRR), and O₂ pulse (O₂ P). Results showed a V˙O_2peak value of 40.6 (2.5) ml · min⁻¹ · kg⁻¹, an absolute VT detected at 23.1 (1.5) ml · min⁻¹ · kg⁻¹ V˙O₂ and a relative VT at 56.4 (2.2)% V˙O_2peak. HRr [15.8 (3.2) beats · min⁻¹], HRR [48.6 (4.3) beat · l⁻¹], and O₂ P [0.23 (0.02) ml · kg⁻¹ · beat⁻¹] were normal, whereas VR at peak exercise [42.7 (2.4)%] was increased. As wheelchair exercise excluded the use of an able-bodied (AB) control group, we compared our V˙O_2peak and VT results with those for other P subjects and AB controls reported in the literature, and we compared our cardioventilatory responses with those for respiratory and cardiac patients. The low V˙O_2peak values obtained compared with subject values obtained during an arm-crank exercise may be due to a reduced active muscle mass. Absolute VT was somewhat comparable to that of AB subjects, mainly due to the similar muscle mass involved in wheelchair and arm-crank exercise by P and AB subjects, respectively. The increased VR, as reported in patients with chronic heart failure, suggested that P athletes exhibited cardiac limitation at peak exercise, and this contributed to the lower V˙O_2peak measured in these subjects. Accepted: 22 April 1997     

Improved gold chloride staining method for anatomical analysis of sensory nerve endings in the shoulder capsule and labrum as examples of loose and dense fibrous tissues

Consistency in gold chloride staining is essential for anatomical analysis of sensory nerve endings. The gold chloride stain for this purpose has been modified by many investigators, but often yields inconsistent staining, which makes it difficult to differentiate structures and to determine nerve ending distribution in large tissue samples. We introduce additional steps and major changes to the modified Gairns’ protocol. We controlled the temperature and mixing rate during tissue staining to achieve consistent staining and complete solution penetration. We subjected samples to sucrose dehydration to improve cutting efficiency. We then exposed samples to a solution containing lemon juice, formic acid and paraformaldehyde to produce optimal tissue transparency with minimal tissue deformity. We extended the time for gold chloride impregnation 1.5 fold. Gold chloride was reduced in the labrum using 25% formic acid in water for 18 h and in the capsule using 25% formic acid in citrate phosphate buffer for 2 h. Citrate binds gold nanoparticles, which minimizes aggregation in the tissue. We stored samples in fresh ultrapure water at 4° C to slow reduction and to maintain color contrast in the tissue. Tissue samples were embedded in Tissue Tek and sectioned at 80 and 100 μm instead of using glycerin and teasing the tissue apart as in Gairns’ modified gold chloride method. We attached sections directly to gelatin subbed slides after sectioning with a cryostat. The slides then were processed and coverslipped with Permount. Staining consistency was demonstrated throughout the tissue sections and neural structures were clearly identifiable.     

Patterns in ritual tooth avulsion at Roonka

Tooth avulsion is the intentional removal of one or more teeth for ritual or aesthetic reasons, or to denote group affiliation. Typically the maxillary incisors are the teeth most often selected for removal. Previous authors have discussed the presence of tooth avulsions in several individuals recovered from Roonka, but those papers did not examine any patterns in those removals that might be present. Analysis of the tooth avulsions at Roonka reveals a change in the practice over time, with the older burials from phase II typically showing removal of both maxillary central incisors with a left side bias when only one tooth is removed, and the more recent phase III burials showing only one incisor avulsed and a right side bias for removal. Frequencies in the practice also changed over time, with avulsions being much more common in the older phase II burials. Historical evidence suggests that any particular regional or social group would have its own particular pattern of tooth avulsion, so these changes in tooth avulsions at Roonka suggest that the site was either used by multiple groups of people for burials, or that there was significant cultural change during the occupation of the site. Am J Phys Anthropol 154:479–485, 2014. © 2014 Wiley Periodicals, Inc.     

Rejecting strictly allopatric speciation on a continental island: prolonged postdivergence gene flow between Taiwan (Leucodioptron taewanus,Passeriformes Timaliidae) and Chinese (L. canorum canorum) hwameis

Allopatry is conventionally considered the geographical mode of speciation for continental island organisms. However, strictly allopatric speciation models that assume the lack of postdivergence gene flow seem oversimplified given the recurrence of land bridges during glacial periods since the late Pliocene. Here, to evaluate whether a continental island endemic, the Taiwan hwamei (Leucodioptron taewanus, Passeriformes Timaliidae) speciated in strict allopatry, we used weighted‐regression‐based approximate Bayesian computation (ABC) to analyse the genetic polymorphism of 18 neutral nuclear loci (total length: 8500 bp) in Taiwan hwamei and its continental sister species, the Chinese hwamei (L. canorum canorum). The nonallopatry model was found to fit better with observed genetic polymorphism of the two hwamei species (posterior possibility = 0.82). We also recovered unambiguous signals of nontrivial bidirectional postdivergence gene flow (N_em » 1) between Chinese hwamei and Taiwan hwamei until 0.5 Ma. Divergence time was estimated to be 3.5 to 2 million years earlier than that estimated from mitochondrial cytochrome b sequences. Finally, using the inferred nonallopatry model to simulate genetic variation at 24 nuclear genes examined showed that the adiponectin receptor 1 gene may be under divergent adaptation. Our findings imply that the role of geographical barrier may be less prominent for the speciation of continental island endemics, and suggest a shift in speciation studies from simply correlating geographical barrier and genetic divergence to examining factors that facilitate and maintain divergence, e.g. differential selection and sexual selection, especially in the face of interpopulation gene flow.     

White matter and cognition in adults who were born preterm

Background and Purpose

Individuals born very preterm (before 33 weeks of gestation, VPT) are at risk of damage to developing white matter, which may affect later cognition and behaviour.

Methods

We used diffusion tensor MRI (DT-MRI) to assess white matter microstructure (fractional anisotropy; FA) in 80 VPT and 41 term-born individuals (mean age 19.1 years, range 17–22, and 18.5 years, range17–22 years, respectively). VPT individuals were part of a 1982–1984 birth cohort which had been followed up since birth; term individuals were recruited by local press advertisement. General intellectual function, executive function and memory were assessed.

Results

The VPT group had reduced FA in four clusters, and increased FA in four clusters relative to the Term group, involving several association tracts of both hemispheres. Clusters of increased FA were associated with more severe neonatal brain injury in the VPT group. Clusters of reduced FA were associated with lower birth weight and perinatal hypoxia, and with reduced adult cognitive performance in the VPT group only.

Conclusions

Alterations of white matter microstructure persist into adulthood in VPT individuals and are associated with cognitive function.