Attempted symmetry affects dynamic gait stability in individuals with lower-limb amputation.

BACKGROUND: Gait in people with lower limb amputation (LLA) is typically asymmetrical. Reducing this asymmetry is often attempted to minimise the impact of secondary health issues. However, temporal-spatial asymmetry in gait of people with LLA has also been shown to underpin dynamic stability. RESEARCH QUESTION: The current study aimed to identify the effects of acute attempts to achieve temporal-spatial symmetry on the dynamic stability of people with unilateral transtibial amputation (UTA). The secondary aim of this study was to identify the corresponding biomechanical adaptations during attempted symmetrical gait. METHODS: Eleven people with UTA walked along a 15 m walkway in four different conditions: normal (NORM), attempted symmetrical step length and step frequency (SYMSL+SF) attempted symmetrical step length (SYMSL) and attempted symmetrical step frequency (SYMSF). Dynamic stability was measured using the backward (BW) and medio-lateral (ML) margins of stability (MoS). RESULTS: Results indicate that attempting SYMSF had a positive effect on gait stability in BW and ML directions, while attempting SYMSL had a potentially negative effect, although these results did not appear to be significant. The absence of clustering in principal component analysis, supported the lack of significant results, indicating no features differentiating between conditions of attempted symmetry. Conversely, there was clustering by limbs which were associated with differences in knee and ankle joint angles between the prosthetic and non-prosthetic limbs, and clustering by individuals highlighting the importance of patient-specific analysis. CONCLUSION: The data suggests that attempted symmetrical gait reduces asymmetry but also affects dynamic stability.

Perceptions of In-home Monitoring Technology for Activities of Daily Living: Semistructured Interview Study With Community-Dwelling Older Adults.

BACKGROUND: Many older adults prefer to remain in their own homes for as long as possible. However, there are still questions surrounding how best to ensure that an individual can cope with autonomous living. Technological monitoring systems are an attractive solution; however, there is disagreement regarding activities of daily living (ADL) and the optimal technologies that should be used to monitor them. OBJECTIVE: This study aimed to understand older adults' perceptions of important ADL and the types of technologies they would be willing to use within their own homes. METHODS: Semistructured interviews were conducted on the web with 32 UK adults, divided equally into a younger group (aged 55-69 years) and an older group (≥70 years). RESULTS: Both groups agreed that ADL related to personal hygiene and feeding were the most important and highlighted the value of socializing. The older group considered several activities to be more important than their younger counterparts, including stair use and foot care. The older group had less existing knowledge of monitoring technology but was more willing to accept wearable sensors than the younger group. The younger group preferred sensors placed within the home but highlighted that they would not have them until they felt that daily life was becoming a struggle. CONCLUSIONS: Overall, technological monitoring systems were perceived as an acceptable method for monitoring ADL. However, developers and carers must be aware that individuals may express differences in their willingness to engage with certain types of technology depending on their age and circumstances.

The Calculation, Thresholds and Reporting of Inter-Limb Strength Asymmetry: A Systematic Review.

The prevalence of inter-limb strength differences is well documented in the literature however, there are inconsistencies related to measurement and reporting, and the normative values and effects associated with inter-limb asymmetry. Therefore, the aims of this systematic review were to: 1) assess the appropriateness of existing indices for the calculation of asymmetry, 2) interrogate the evidence basis for literature reported thresholds used to define asymmetry and 3) summarise normative levels of inter-limb strength asymmetry and their effects on injury and performance. To conduct this systematic review, scientific databases (PubMed, Scopus, SPORTDiscus and Web of Science) were searched and a total of 3,594 articles were retrieved and assessed for eligibility and article quality. The robustness of each identified asymmetry index was assessed, and the evidence-basis of the identified asymmetry thresholds was appraised retrospectively using the references provided. Fifty-three articles were included in this review. Only four of the twelve identified indices were unaffected by the limitations associated with selecting a reference limb. Eighteen articles applied a threshold to original research to identify "abnormal" asymmetry, fifteen of which utilised a threshold between 10-15%, yet this threshold was not always supported by appropriate evidence. Asymmetry scores ranged between and within populations from approximate symmetry to asymmetries larger than 15%. When reporting the effects of strength asymmetries, increased injury risk and detriments to performance were often associated with larger asymmetry, however the evidence was inconsistent. Limitations of asymmetry indices should be recognised, particularly those that require selection of a reference limb. Failure to reference the origin of the evidence for an asymmetry threshold reinforces doubt over the use of arbitrary thresholds, such as 10-15%. Therefore, an individual approach to defining asymmetry may be necessary to refine robust calculation methods and to establish appropriate thresholds across various samples and methodologies that enable appropriate conclusions to be drawn.

The effect of visual focus on spatio-temporal and kinematic parameters of treadmill running.

The characteristics of a treadmill and the environment where it is based could influence the user's gaze and have an effect on their running kinematics and lower limb impacts. The aim of this study was to identify the effect of visual focus on spatio-temporal parameters and lower limb kinematics during treadmill running. Twenty six experienced runners ran at 3.33ms-1 on a treadmill under two visual conditions, either looking ahead at a wall or looking down at the treadmill visual display. Spatio-temporal parameters, impact accelerations of the head and tibia, and knee and ankle kinematics were measured for the final 15s of a 90s bout of running under each condition. At the end of the test, participants reported their preference for the visual conditions assessed. Participants' stride angle, flight time, knee flexion during the flight phase, and ankle eversion during contact time were increased when runners directed visual focus toward the wall compared to the treadmill display (p<0.05). Whilst head acceleration was also increased in the wall condition (p<0.05), the other acceleration parameters were unaffected (p>0.05). However, the effect size of all biomechanical alterations was small. The Treadmill condition was the preferred condition by the participants (p<0.001; ESw=1.0). The results of the current study indicate that runners had a greater mass centre vertical displacement when they ran looking ahead, probably with the aim of compensating for reduced visual feedback, which resulted in larger head accelerations. Greater knee flexion during the flight phase and ankle eversion during the contact time were suggested as compensatory mechanisms for lower limb impacts.

Optimisation of a machine learning algorithm in human locomotion using principal component and discriminant function analyses.

Assessment methods in human locomotion often involve the description of normalised graphical profiles and/or the extraction of discrete variables. Whilst useful, these approaches may not represent the full complexity of gait data. Multivariate statistical methods, such as Principal Component Analysis (PCA) and Discriminant Function Analysis (DFA), have been adopted since they have the potential to overcome these data handling issues. The aim of the current study was to develop and optimise a specific machine learning algorithm for processing human locomotion data. Twenty participants ran at a self-selected speed across a 15m runway in barefoot and shod conditions. Ground reaction forces (BW) and kinematics were measured at 1000 Hz and 100 Hz, respectively from which joint angles (°), joint moments (N.m.kg-1) and joint powers (W.kg-1) for the hip, knee and ankle joints were calculated in all three anatomical planes. Using PCA and DFA, power spectra of the kinematic and kinetic variables were used as a training database for the development of a machine learning algorithm. All possible combinations of 10 out of 20 participants were explored to find the iteration of individuals that would optimise the machine learning algorithm. The results showed that the algorithm was able to successfully predict whether a participant ran shod or barefoot in 93.5% of cases. To the authors' knowledge, this is the first study to optimise the development of a machine learning algorithm.

Are joint torque models limited by an assumption of monoarticularity?

This study determines whether maximal voluntary ankle plantar flexor torque could be more accurately represented using a torque generator that is a function of both knee and ankle kinematics. Isovelocity and isometric ankle plantar flexor torques were measured on a single participant for knee joint angles of 111° to 169° (approximately full extension) using a Contrex MJ dynamometer. Maximal voluntary torque was represented by a 19-parameter two-joint function of ankle and knee joint angles and angular velocities with the parameters determined by minimizing a weighted root mean square difference between measured torques and the two-joint function. The weighted root mean square difference between the two-joint function and the measured torques was 10 N-m or 3% of maximum torque. The two-joint function was a more accurate representation of maximal voluntary ankle plantar flexor torques than an existing single-joint function where differences of 19% of maximum torque were found. It is concluded that when the knee is flexed by more than 40°, a two-joint representation is necessary.

Reducing the variability between constant-depth film fermenter experiments when modelling oral biofilm.

AIMS: The inherent instabilities associated with the development of multispecies biofilm communities within the constant-depth film fermenter (CDFF) and other microcosm systems can yield unacceptable variability between experiments, which could limit their potential applications in oral microbiology. The extent of this variability needs to be determined and a protocol developed which minimizes it. METHODS AND RESULTS: Two custom-made CDFFs were supplied concurrently with the same inoculation culture, begat from an aliquot of a saliva pool and artificial saliva growth medium via a dual-channel pump. Transformed log(10) data of the viable counts at fixed time points were analysed using the Bland-Altman approach to test for the levels of agreement between two CDFFs running concurrently and those CDFFs run in series. The coefficients(95%) of agreement were lower (i.e. less variable) in the concurrent model than when run in series for total counts of bacteria (1.238 vs 2.124), Lactobacillus spp. (0.517 vs 1.431) and Mutans streptococci (2.817 vs 3.864). Other measures of variability showed a similar trend. CONCLUSIONS: Operating CDFFs concurrently minimizes the degree of difference and variability between them. SIGNIFICANCE AND IMPACT OF THE STUDY: Operating CDFFs concurrently will improve the sensitivity for experiments that seek to determine the effects of a variable, such as a nutritional supplement or antimicrobial agent, and a control.

An isovelocity dynamometer method to determine monoarticular and biarticular muscle parameters.

This study aimed to determine whether subject-specific individual muscle models for the ankle plantar flexors could be obtained from single joint isometric and isovelocity maximum torque measurements in combination with a model of plantar flexion. Maximum plantar flexion torque measurements were taken on one subject at six knee angles spanning full flexion to full extension. A planar three-segment (foot, shank and thigh), two-muscle (soleus and gastrocnemius) model of plantar flexion was developed. Seven parameters per muscle were determined by minimizing a weighted root mean square difference (wRMSD) between the model output and the experimental torque data. Valid individual muscle models were obtained using experimental data from only two knee angles giving a wRMSD score of 16 N m, with values ranging from 11 to 17 N m for each of the six knee angles. The robustness of the methodology was confirmed through repeating the optimization with perturbed experimental torques (± 20%) and segment lengths (± 10%) resulting in wRMSD scores of between 13 and 20 N m. Hence, good representations of maximum torque can be achieved from subject-specific individual muscle models determined from single joint maximum torque measurements. The proposed methodology could be applied to muscle-driven models of human movement with the potential to improve their validity.

A longitudinal study of the role of childhood temperament in the later development of eating concerns.

OBJECTIVE: This study examined the relationship between childhood temperament and the later development of eating and body concerns in early adolescent children. METHOD: The Australian Temperament Project has followed a cohort of children from birth, assessing temperament factors such as Negative Emotionality, Persistence, Approach/Withdrawal, and Activity. Using a longitudinal design, the study reports on the relationship between temperament measured from infancy onward and eating and body concerns at 12-13 years of age. Participants (597 girls, 631 boys) completed the Eating Disorders Inventory subscales Drive For Thinness, Body Dissatisfaction, and Bulimia, and an estimate of their current size. Parents described their child's temperament and body size. RESULTS: High Negative Emotionality and low Persistence were the factors most associated with risk status over time, particularly in girls. DISCUSSION: While it is unlikely that temperamental characteristics per se lead to disordered eating, it is argued that in combination with other risk factors, certain temperamental characteristics may increase vulnerability.

Oral leukoplakia status six weeks after cessation of smokeless tobacco use.

BACKGROUND: This study evaluated the prevalence and risk of developing oral leukoplakia in smokeless tobacco, or ST, users and the response of these leukoplakic lesions after six weeks of involuntary tobacco cessation. U.S. Air Force basic military training provided an environment of a mandatorily tobacco-free setting. METHODS: The authors designed their investigation as a case control study with a nested cohort study. The principal investigator (G.C.M.) conducted oral examinations of 3,051 male U.S. Air Force basic military trainees. Using a questionnaire, he obtained detailed information concerning subjects' ST use patterns before basic training. Clinical photos were taken of all leukoplakic lesions identified in ST users at the initial examination and again six weeks later. RESULTS: Of the 3,051 male trainees examined (mean age = 19.5 years), 9.9 percent (302/3,051) were identified as current ST users. Among current ST users, 39.4 percent (119/302) had leukoplakia vs. 1.5 percent (42/2,749) of nonusers of ST (odds ratio = 41.9, 95 percent confidence interval = 28.1-62.6). At the end of the involuntary cessation of tobacco use, 97.5 percent of these leukoplakic lesions had complete clinical resolution. The type of ST used (snuff vs. chewing tobacco), amount used (cans or pouches per day), length of use (months), number of days since last use and brand of snuff used were significantly associated with the risk of developing leukoplakic lesions among ST users. CONCLUSIONS: The important new finding from this investigation is that if a young, otherwise healthy man with leukoplakic lesions stops using tobacco for six weeks, most of his leukoplakic lesions will resolve clinically. Use of ST, specifically snuff, is strongly associated with development of oral leukoplakia in young adult men. CLINICAL IMPLICATIONS: The clinician can use these findings in deciding when to perform biopsies on leukoplakic lesions associated with ST use. This information also should be used to assist ST users in quitting this addictive behavior.

Clinical experience with psychoanalytic post-termination meetings.

The authors describe post-termination meetings in order to examine the controversial issue of the proper relationship between analyst and patient at this stage. In the first case the meetings facilitated the patient's re-entering treatment, leading to significant further growth. In the second and third cases, the meetings re-ignited mourning for the analyst and furthered analytic gains. The authors' overall impression was that the post-termination contacts were helpful for all three patients. Their limited data contradicted the long-standing assumption that all post-termination contact, unless specified as a course of further treatment, is harmful to the patient. The authors suggest that such meetings stabilise analytic gains, provide a joint assessment of analytic outcome from a useful later perspective and provide an opportunity for further analytic work. The consideration of any post-termination changes in the patient allows for a more inclusive evaluation of the analysis than was possible earlier. While acknowledging the need to consider such meetings thoughtfully in order to avoid any harmful enactment of wishes by the patient or the analyst, the authors encourage analysts to explore and report such meetings to replace unexamined assumptions and develop a body of clinical data about the effects of post-termination contacts.

Neisseria gonorrhoeae possesses two nicotinamide adenine dinucleotide-independent lactate dehydrogenases.

An important metabolic capability of Neisseria gonorrhoeae is the utilization of host-derived lactate. Two isoenzymes of the membrane-associated, pyridine dinucleotide-independent type of lactate dehydrogenase (iLDH) participate in lactate assimilation, but exhibit distinctive properties. Isoenzyme iLDH-I utilized lactate exclusively as substrate, exhibiting a preference for the D-isomer. In contrast, isoenzyme iLDH-II exhibited broad substrate specificity (lactate, phenyllactate, and 4-hydroxyphenyllactate), but was stereospecific for the L-isomers. These results explain the difficulty in isolating mutants unable to utilize lactate.

Recontact with the analyst following termination: a survey of seventy-one cases.

A questionnaire was sent to graduate members of the Denver Psychoanalytic Society asking for their experience with patients making contact with them after the analysis. They reported that within three years after termination two thirds of "successfully analyzed" patients had recontacted them. Seventy-one cases were surveyed. Most contacts were brief and did not seem to be the result of incomplete analysis. Rather, they aimed to satisfy ongoing needs for: the continuing deidealization of the analyst, the reactivation of the self-analytic function, and the restructuring of self- and object representations by reporting developmentally significant accomplishments to the former analyst. The analyst's acknowledgement appears to be an integral part of the restructuring. This is work which either cannot be done before termination or the need for which has not been recognized during the analysis.

Mass spectrometric measurement of zeatin glycoside levels in Vinca rosea L. crown gall tissue.

The range of zeatin glycosides found in crown gall tissue of Vinca rosea L. has been quantified using a mass spectrometric isotope dilution procedure. Problems in the quantitative analysis of cytokinins in plant extracts are discussed.

Ethylene Evolution following Treatment with 1-Aminocyclopropane-1-carboxylic Acid and Ethephon in an in Vitro Olive Shoot System in Relation to Leaf Abscission.

1-Aminocyclopropane-1-carboxylic acid (ACC) supplied via the cut base of detached olive shoots caused a burst of ethylene from leaves, but other cyclopropanes tested did not exhibit this effect. Ethephon (ET) and another ethylene-releasing compound caused a prolonged increase in ethylene evolution. ACC had only a very limited effect on leaf abscission regardless of concentration, whereas shoots placed with cut bases in ET for 60 to 80 minutes exhibited 100% leaf abscission within 90 hours. Shoots with inflorescences treated with ET just prior to anthesis began to wilt in vitro within 20 to 30 hours and failed to exhibit leaf abscission. At earlier stages of development, ET induced more leaf abscission on reproductive shoots than on vegetative shoots. It is suggested that the duration of ethylene evolution from the leaves governs their potential for abscission and that bursts of ethylene evolution even though large in amount may not induce abscission.

Gibberellins in mature apple seeds - contaminants?

Evidence is presented that gibberellins A4 and A7, previously identified (Sinska, I., Lewak, St., Gaskin, P., MacMillan, J., Planta 114, 359-364, 1973) in extracts of mature apple (Pyrus malus L.) seeds, were present primarily as contaminants. The facts supporting this conclusion are: a) the ratio of GA4 to GA7 was similar to that of a standard mixture; b) the concentrations were extremely high; and c) the ratio of GA4 to GA7 did not change during stratification, as had been reported when extracts were bioassayed (Sinska, I., and Lewak, St., Physiol. Vég. 8, 661-667, 1970).

Candidates' evaluation of psychoanalytic supervision.

The origins, methods, results, and discussions of a project undertaken by the advanced candidates at the Denver Institute for Psychoanalysis have been described. This project was designed to examine the supervisory process and to compile a consensual critique of individual supervisors from the candidate's point of view. We have included vignettes of supervisory experiences. It became our purpose to: (1) Develop a set of criteria by which the strengths and weaknesses of supervisors can be evaluated, (2) Involve the candidate in assessing his own learning needs, (3) Promote the objective assignment of supervisors, an assignment determined by the patient's problems, the candidate's learning needs, and the supervisor's varying capacities and abilities to effectively understand these problems and deal with these needs, (4) Expand the supervisory process to include what we felt were often unconscious or hiterto unacceptable issues, such as the function and use of countertransference, and the detection and open discussion of transference dilemmas between analyst and both patient and supervisor, (5) Stimulate dialogue at all levels of psychoanalytic education on the patient-analyst-supervisor relational system.