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Anatomical knowledge is the foundation of the educational curricula in most healthcare programs. The varying scopes of practice between healthcare professions require anatomy educators to determine what content is essential to cover in a finite time with learners. When possible, the anatomy educator bases this decision on clinical experiences; this is a more significant challenge for the non-clinician educator teaching in a health profession curriculum. Although studies have determined essential anatomy content in many healthcare professions, no study has been undertaken in physical therapist education. This study was designed to determine what anatomical concepts are considered essential in physical therapist education in one doctor of physical therapy program. Faculty (The online version contains supplementary material available at 10.1007/s40670-022-01574-1.

Background: Adverse drug reactions (ADRs) can occur due to ecstasy use, and the number of people dying due to drug-related deaths has increased in the past 10 years. Harm reduction strategies could help prevent ADRs or decrease the incidence of life-threatening health consequences due to ecstasy use. However, no reviews have explored the breadth of evidence available on ecstasy harm reduction strategies. Methods: A rapid scoping review was conducted using adapted JBI methodology to identify the prevalence and nature of harm reduction strategies that ecstasy users employ in recreational settings, with both peer-reviewed research and user-oriented drug information websites explored. Five databases (CINAHL, EMBASE, Medline, PsycINFO, CENTRAL) were searched for English language records from database inception to August 2022. User-oriented websites were identified via the project’s stakeholder group and Google searches. Results: Twenty reports representing 19 studies (one randomised control trial, nine quantitative descriptive studies and nine qualitative studies) were included. A wide variety of harm reduction strategies were reported, including drug-specific strategies (for example, limiting the amount of ecstasy consumed, buying from trusted sources, drug checking (pill testing)); behavioural strategies (for example, monitoring fluid (water) consumption, taking a rest break to regulate temperature, avoiding alcohol and mixing with other drugs; preloading and post-loading); and peer-related strategies (for example not using alone, looking out for friends). Ecstasy users obtain information on ecstasy’s effects and/or harm reduction practices from a variety of sources including friends, nightclubs, TV news, drug leaflets, music magazines and user-oriented information websites. Fourteen user-oriented websites providing ecstasy-specific harm reduction information were identified, and strategies focused on dosage and frequency of use, interaction with other substances and prevention of health consequences, such as heatstroke, or dehydration among others. However, only two webpages provided citations to the evidence used for the content. Conclusions: While numerous harm reduction strategies exist, employing them can depend on the users’ overall goal/s which might also encompass avoiding comedown or increasing their high. Moreover, users’ previous experience can influence how and when they adhere to harm reduction. More efficient ways of communicating harms and harm reduction strategies might be needed.

Summary Background In the wake of the SARS-CoV-2 pandemic and unprecedented global demand, clinicians are struggling to source adequate access to personal protective equipment. Respirators can be in short supply, though are necessary to protect workers from SARS-CoV-2 exposure. Rapid decontamination and reuse of respirators may provide relief for the strained procurement situation. Method In this study, we investigated the suitability of 70°C dry heat and microwave-generated steam (MGS) for reprocessing of FFP2/N95-type respirators, and Type-II surgical face masks. Staphylococcus aureus was used as a surrogate as it is less susceptible than enveloped viruses to chemical and physical processes. Results We observed >4 log10 reductions in the viability of dry S. aureus treated by dry heat for 90 min at 70°C and >6 log10 reductions by MGS for 90 s. After 3 reprocessing cycles, neither process was found to negatively impact the bacterial or NaCl filtration efficiency of the respirators that were tested. However, MGS was incompatible with Type-II surgical masks tested, as we confirmed that bacterial filtration capacity was completely lost following reprocessing. MGS was observed to be incompatible with some respirator types due to arcing observed around some types of metal nose clips and by loss of adhesion of clips to the mask. Conclusion Considering the advantages and disadvantages of each approach, we propose a reprocessing personal protective equipment/face mask workflow for use in medical areas.

Anatomical knowledge is requisite for effective physical therapy (PT) practice. Cadaver dissection is a popular teaching method employed in PT anatomy courses. Limited time in the laboratory requires effective dissection instructions. Several limitations of a printed, non-discipline specific dissection guide have been identified by students and instructors in anatomy curricula. The objective of this project was to evaluate the effect of using a digital, PT specific dissection guide on examination performance and student satisfaction. A digital guide was developed that incorporated improvements based on observations of student experiences using a printed guide. The digital guide covered two lower extremity regional dissections and was distributed for use during the summer 2017 course. Enhancements included clarification of dissection procedures, formative quizzes, image galleries, embedded videos, and a glossary of terms. Students used a printed guide for all other dissections in the course. The percentage of correct answers from practical examinations was calculated and compared between summer of 2015 (print) and 2017 (digital) courses. A survey consisting of nineteen five-point Likert items was distributed. The percentage of correct answers was significantly higher for the digital guide (91.7 ± 7.11%) compared with the print guide (84.2 ± 9.51%, P < 0.0001). On the survey, the median item rating was strongly agree for two, agree for fifteen, and neither agree or disagree for two. These results suggest that developing a curriculum specific, digital guide was effective in improving student knowledge and satisfaction. These results encourage development of additional content specific guides in a digital format. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s40670-020-01000-4) contains supplementary material, which is available to authorized users.

Background Preclinical medical learners are embedded in technology-rich environments, allowing them rapid access to a large volume of information. The anatomy laboratory is an environment in which faculty can assess the development of professional skills such as information literacy in preclinical medical learners. In the anatomy laboratory, many students use Google Images searches in addition to or in place of other course materials as a resource to locate and identify anatomical structures. However, the most frequent sources as well as the educational quality of these images are unknown. Objective This study was designed to assess the sources and educational value of Google Images search results for commonly searched anatomical structures. Methods The top 10 Google Images search results were collected for 39 anatomical structures. Image source websites were recorded and categorized based on the purpose and target audience of the site publishing the image. Educational value was determined through assessment of relevance (is the searched structure depicted in the image?), accuracy (does the image contain errors?), and usefulness (will the image assist a learner in locating the structure on an anatomical donor?). A reliable scoring rubric was developed to assess an image’s usefulness. Results A total of 390 images were analyzed. Most often, images were sourced from websites targeting health care professionals and health care professions students (38% of images), while Wikipedia was the most frequent single source of image results (62/390 results). Of the 390 total images, 363 (93.1%) depicted the searched structure and were therefore considered relevant. However, only 43.0% (156/363) of relevant images met the threshold to be deemed useful in identifying the searched structure in an anatomical donor. The usefulness of images did not significantly differ across source categories. Conclusions Anatomy faculty may use these results to develop interventions for gaps in information literacy in preclinical medical learners in the context of image searches in the anatomy laboratory.

Cationic biocides are widely utilized for surface disinfection. Photosensitizers such as toluidine blue O (TBO) produce reactive oxygen species following light excitation and are being investigated as novel biocides for similar applications. Aspergillus brasiliensis conidia contain melanin which protects against environmental stressors. The negative charge and antioxidant properties of melanin may confer resistance to photosensitizers and other biocides. In this study, the yeasticidal and fungicidal activity benzalkonium chloride (BZC), sodium dichloroisocyanurate (NaDCC) and TBO with red light were examined using quantitative suspension tests. All three biocides were highly effective against Candida albicans and > 5·0 log10 reductions in viability were attainable within 5 minutes. Wild‐type A. brasiliensis conidia were highly tolerant to treatment and 0·4 log10 reductions in viability were observed within the same time frame when treated with TBO or BZC. NaDCC was markedly more effective. Inhibition of melanin biosynthesis by culturing with 100 μg ml−1 kojic acid resulted in a hypopigmented phenotype with significantly increased sensitivity to all three biocides. These observations indicate that melanin is a significant contributor towards A. brasiliensis tolerance of biocides and photosensitizers and demonstrate that cationic biocides are poorly suited to applications where the control of A. brasiliensis is required.

Although numerous online resources for gross anatomy are available, most feature two-dimensional photographs generated by traditional cameras. To determine whether the incorporation of light field photographs (images with an adjustable focal point) into an online anatomy resource would result in improved learning beyond traditional photographs, two online learning modules on the gross anatomy of the orbit were created. The modules were identical in content except for the type of photography used (traditional = control; light field = experimental). Students were randomly assigned into two groups and viewed one of the two learning modules. Pre- and post-quizzes comprised of a mixture of questions involving a low and high degree (rated by experienced faculty) of spatial difficulty were administered. A survey was distributed to assess student evaluations of the module. Students (N = 49; 26 control, 23 experimental) demonstrated increased quiz scores from pre- (control = 34.6 ± 15.6%, experimental = 24.3 ± 16.5%) to post-quizzes (control = 77.3 ± 20.7%, experimental = 71.3 ± 17.9%, P

Personal computer use for educational purposes by the healthcare professions students has become ubiquitous. Although the effect of computer-based dissection instructions has been studied, there is a paucity of information regarding student browsing habits of information available on the Internet. Although current students have favorable attitudes toward accessing anatomical information online, web browsing habits have not yet been investigated specifically in the dissection laboratory setting. The purpose of this study was to describe the browsing habits of the healthcare professions students in the gross anatomy setting using a retrospective analysis. Files containing web browser history were retrieved from desktop computers in the gross anatomy laboratory and custom code was written to parse them into comma separated value files. Each web address was categorized and descriptive statistics was calculated. Browser history for 24 computers was analyzed from June 2013 to January 2015. During this period, students accumulated 100,857 webpage visits. Most often, students performed a Google search for anatomy (22.0% of all visits) and non-anatomy related (20.6% of all visits) information. Students also used the web browser to access various entertainment (16.4% of all visits) and productivity related services (15.9% of all visits). This analysis revealed a large volume of webpage visits by the healthcare professions students in the gross anatomy laboratory. A wide diversity of anatomy and non-anatomy related webpages were visited. Future analyses could be directed at examination of when in relation to class time students accessed the information, how browsing habits change over time, and what anatomical structures were most commonly searched for.

Background Despite rescheduling of cannabis to Schedule 2 and amendments to the law permitting legal availability of cannabis for the treatment of medical conditions, access to cannabis for medical use remains challenging for patients in the United Kingdom (UK). Recreational use is widespread despite laws stating users can be sentenced to prison for up to 5 years for possession. Objective The aim of the study was to develop a model for a legal cannabis market in the UK building upon the results of a preceding study in which a UK population sample determined that pharmacies are the most suitable primary legal vendor of cannabis as opposed to regulated shops or the black market. Methods An online survey was developed using Qualtrics software and advertised via the Multidisciplinary Association for Psychedelic Studies’ Facebook, Twitter and Instagram social media accounts and monthly newsletter. Results Three hundred and ninety seven individuals, a majority having used cannabis at least once, consented to participate in the study. The participants concluded that there is enough evidence for cannabis to be prescribed to treat a range of medical conditions. In addition to pharmacies providing cannabis to patients with a prescription, a majority of participants supported cannabis being sold in pharmacies for harm reduction purposes and allowing access to medicinal cannabis in cases where supporting evidence is insufficient to merit a prescription. Participants supported greater integration between dispensing pharmacies and mental health services. Overall, the participants did not oppose a consultation or screening for potential cannabis users prior to obtaining access from licensed vendors. UK participants were supportive of the concept of a cannabis card, which users can present to licensed vendors such as pharmacies, with specific recommendations (such as strains relevant to a patient’s medical condition) being coded into the card. A majority of participants supported the existence of shisha-type bars for the purchase and onsite consumption of cannabis and determined that such vendors should not be part of a pharmacy chain of stores or regulated by pharmacy regulators. The participants generally preferred that laws regarding public consumption are in line with existing smoking legislation. Participants determined that it should be legally permitted to grow cannabis at home for personal medical and non-medical purposes but not to sell for profit. Conclusion The results are suggestive of a regulatory system that medical and non-medical cannabis users can use which aims to maximise therapeutic applications, minimise harms and respect individual liberty.

Objective: The purpose of this study was to investigate the utilization and perception of live blogged sessions of a physical therapy (PT) conference. Methods: Sessions at an international PT conference were covered in real time using a live-blogging platform. Session coverage could be viewed remotely using computers and mobile devices. Viewers could interact with the content by clicking on links and using the comment feature. Sessions could also be replayed following their conclusion. An online survey of user perceptions was made available the week following the conference. Results: Twenty-four sessions were live blogged with an average session length of 67 min (range: 27–120). On average, live sessions received 27 views (range: 2–65), 18 clicks (range: 2–36), and 2 comments (range: 0–10). The average time spent viewing a live session was 28 min (32% of viewers 1 min). Following the conference, session replays totaled 7206 views and 2910 clicks. The average survey respondent (n = 17) watched five live sessions (range: 1–17) and found the updates easy to read (4.5 on a scale of 5.0). When asked if they learned something from the coverage, 94% of respondents said yes and 94% said they would view if available for an upcoming conference. Discussion: Live blogging extended the viewing audience and facilitated viewer engagement. Survey respondents found the coverage educational, of high quality, and would participate again in the future.

Hepcidin belongs to the antimicrobial peptide family but has weak activity with regards to bacterial killing. The regulatory function of hepcidin in humans serves to maintain an iron-restricted environment that limits the growth of pathogens; this study explored whether hepcidin affected bacterial iron homeostasis and oxidative stress using the model organism Escherichia coli. Using the Miller assay it was determined that under low iron availability exposure to sub-inhibitory doses of hepcidin (4-12μM) led to 2-fold and 4-fold increases in the expression of ftnA and bfd, respectively (P < 0.05), in both a wild type (WT) and Δfur (ferric uptake regulator) background. Quantitative real-time PCR analysis of oxyR and sodA, treated with 4 or 8 μM of hepcidin showed that expression of these genes was significantly (P < 0.05) increased, whereas expression of lexA was unchanged, indicating that hepcidin likely mediated oxidative stress but did not induce DNA damage.

New Findings What is the central question of this study? How long can humans sustain motor unit discharge during a voluntary contraction? What is the main finding and its importance? Human motor units can discharge action potentials for a longer time during a voluntary contraction than can be achieved by intracellular or extracellular current injection of motor neurons with in vivo and in vitro animal preparations. These recordings comprise a previously unexplored range of durations for human motor unit recordings during a continuously sustained isometric recording. The purpose of the study was to determine how long humans could sustain the discharge of single motor units during a voluntary contraction. The discharge of motor units in first dorsal interosseus of subjects (27.8 ± 8.1 years old) was recorded for as long as possible. The task was terminated when the isolated motor unit stopped discharging action potentials, despite the ability of the individual to sustain the abduction force. Twenty-three single motor units were recorded. Task duration was 21.4 ± 17.8 min. When analysed across discharge duration, mean discharge rate (10.6 ± 1.8 pulses s−1) and mean abduction force (5.5 ± 2.8% maximum) did not change significantly (discharge rate, P = 0.119; and abduction force, P = 0.235). In contrast, the coefficient of variation for interspike interval during the initial 30 s of the task was 22.2 ± 6.0% and increased to 31.9 ± 7.0% during the final 30 s (P

In brief: In a preliminary study to evaluate possible causes of exhaustion, 48 runners who collapsed during or after an ultramarathon race were questioned about their training methods. The training profiles were compared with those of matched controls who had finished the same race without collapsing. Possible contributing factors found among the collapsed runners included inadequate training, failing to carbohydrate load, not eating a prerace breakfast, prerace illness, and hypothermia (during one race, which was run in cold, wet, windy conditions). The authors suggest that regardless of athletic ability or previous racing experience, runners may be prone to collapse during or after ultramarathon races if their prerace training and preparation are inadequate.

INTRODUCTION.: Age-related differences in force steadiness have been extensively examined and used as an index of motor function. However, the functional relevance of steadiness remains unclear. PURPOSE.: The aim here was to evaluate the relations among hand strength, steadiness, and function across the adult life-span. METHODS.: Seventy-five adults (45 women; 18-89 yr) performed 3 strength, 2 steadiness, and 4 functional tests with both hands. Strength was measured during index finger abduction, precision pinch, and handgrip, and steadiness was measured during index finger abduction and precision pinch. Functional tests included the Grooved Pegboard test, the game Operation, a scissor task, and a tracing task. Results. Moderate correlations were observed between both steadiness tasks and performance on the Grooved Pegboard test (R= 0.57 and R= 0.46, respectively) and the game Operation (R2=-0.47 and R= -0.57, respectively). CONCLUSIONS.: The relation between measures of steadiness and hand function suggests that the physiological mechanisms responsible for differences in steadiness also contribute to differences in the performance of fine motor tasks with the hand. Language: en

Background:Contemporary research indicates that the legal classifications of cannabis (Schedule 2, Class B), 3,4-methylenedioxymethamphetamine (MDMA) (Schedule 1, Class A) and psilocybin (Schedule 1, Class A) in the United Kingdom are not entirely based on considerations of harm and therapeutic utility. The legal classifications of the substances discussed are typically determined by legislators such as Parliament and, therefore, may be a reflection of the views or perceived views of the general public.Objective:The aim of the study was to provide an indication of the underlying psychology regarding the legislated sale of alcohol, tobacco, cannabis, MDMA and psilocybin in pharmacies according to a UK general population sample.Methods:A sample of 105 UK nationals was selected for the survey. Participants were asked questions on perceived relative harm of the five substances. After viewing contemporary information on reported relative harm and therapeutic applications, the participants were asked questions related to using the pharmacy retail model for the sale of the substances discussed. Participants who opposed the substances being sold primarily in pharmacies were asked to explain their rationale according to a predetermined list of options for each of the five drugs. Participants were also asked whether they consider it a human right to be legally permitted to consume the substances.Results:The participants' perceptions of relative harm (tobacco > MDMA > psilocybin > alcohol > cannabis) were not in agreement with the relative harm reported in the literature (alcohol > tobacco > cannabis > MDMA > psilocybin). Principal objections to the currently illicit substances being legally available in pharmacies include it sending the wrong message; it feels wrong; it is too dangerous; disliking the smell of cannabis; disapproval of the people; and not liking the idea of people using psychoactive drugs for entertainment or to have mystical/religious experiences. Overall, the participants determined that being legally permitted to consume the substances discussed is an issue of relevance to human rights. A majority of the male participants concluded that being legally permitted to consume alcohol, tobacco, cannabis and Psilocybe mushrooms is a human right in contrast to the majority of female participants who solely considered alcohol consumption to be a human right.Conclusions:The data suggest that the legal classifications may not simply be based on considerations of harm. Misperceptions of the dangers, biases and non-health-related aversions likely contribute to the continuation of policies that do not reflect the state of scientific research.

Background: Wiki platform use has potential to improve student learning by improving engagement with course material. A student-created wiki was established to serve as a repository of study tools for students in a medical school curriculum. There is a scarcity of information describing student-led creation of wikis in medical education. Objective: The aim is to characterize website traffic of a student-created wiki and evaluate student perceptions of usage via a short anonymous online survey. Methods: Website analytics were used to track visitation statistics to the wiki and a survey was distributed to assess ease of use, interest in contributing to the wiki, and suggestions for improvement. Results: Site traffic data indicated high usage, with a mean of 315 (SD 241) pageviews per day from July 2011 to March 2013 and 74,317 total user sessions. The mean session duration was 1.94 (SD 1.39) minutes. Comparing Fall 2011 to Fall 2012 sessions revealed a large increase in returning visitors (from 12,397 to 20,544, 65.7%) and sessions via mobile devices (831 to 1560, 87.7%). The survey received 164 responses; 88.0% (162/184) were aware of the wiki at the time of the survey. On average, respondents felt that the wiki was more useful in the preclinical years (mean 2.73, SD 1.25) than in the clinical years (mean 1.88, SD 1.12; P

Background. The efficacy and safety of converting maintenance renal transplant recipients from calcineurin inhibitors (CNIs) to sirolimus (SRL) was evaluated. Methods. Eight hundred thirty renal allograft recipients, 6 to 120 months posttransplant and receiving cyclosporine or tacrolimus, were randomly assigned to continue CNI (n=275) or convert from CNI to SRL (n=555). Primary endpoints were calculated Nankivell glomerular filtration rate (GFR; stratified at baseline: 20-40 vs. >40 mL/min) and the cumulative rates of biopsy-confirmed acute rejection (BCAR), graft loss, or death at 12 months. Enrollment in the 20 to 40 mL/min stratum was halted prematurely because of a higher incidence of safety endpoints in the SRL conversion arm. Results. Intent-to-treat analyses at 12 and 24 months showed no significant treatment difference in GFR in the baseline GFR more than 40 mL/min stratum. On-therapy analysis of this cohort showed significantly higher GFR at 12 and 24 months after SRL conversion. Rates of BCAR, graft survival, and patient survival were similar between groups. Median urinary protein-to-creatinine ratios (UPr/Cr) were similar at baseline but increased significantly after SRL conversion. Malignancy rates were significantly lower at 12 and 24 months after SRL conversion. Post hoc analyses identified a subgroup with baseline GFR more than 40 mL/min and UPr/Cr less than or equal to 0.11, whose risk-benefit profile was more favorable after conversion than that for the overall SRL conversion cohort. Conclusions. At 2 years, SRL conversion among patients with baseline GFR more than 40 mL/min was associated with excellent patient and graft survival, no difference in BCAR, increased urinary protein excretion, and a lower incidence of malignancy compared with CNI continuation. Superior renal function was observed among patients who remained on SRL through 12 to 24 months, particularly in the subgroup of patients with baseline GFR more than 40 mL/min and UPr/Cr less than or equal to 0.11.

The purpose of the experiment was to compare the level of synchronization exhibited by pairs of motor units located within and between functionally distinct regions of the biceps brachii muscle. Pairs of single motor units were recorded from seven subjects using separate electrodes located in the lateral and medial aspects of the long head of biceps brachii. Participants were required to exert a combination of flexion and supination torques so that both motor units discharged at approximately 10 pps for ≥200 s and the level of motor unit synchronization could be quantified. When motor unit recordings were sufficiently stable at the completion of this synchrony task, a series of ramp contractions with multiple combinations of flexion and supination torques were performed to characterize the recruitment thresholds of the motor units. Common input strength (CIS) was significantly greater (P < 0.01) for the within-region pairs of motor units (0.28 extra sync. imps/s, n = 26) than for the between-region pairs (0.13 extra sync. imps/s, n = 18), but did not differ significantly for the 12 within-region pairs from the lateral head and 14 from the medial head (0.27 vs. 0.29 extra sync. imps/s; P = 0.83). Recruitment thresholds were measured for 33 motor units, but there was only a weak association between CIS and the respective recruitment patterns for motor unit pairs (n = 9). The present investigation provides evidence of a differential distribution of synaptic input across the biceps brachii motor neuron pool, but this appears to have minimal association with the recruitment patterns for individual motor units.

Electrical stimulation of the brachioradialis branch of the radial nerve has been shown to inhibit the discharge of voluntarily activated motor units in biceps brachii during weak contractions with the elbow flexor muscles. The purpose of the present study was to characterise the inhibitory reflex by comparing its strength in the short and long heads of the biceps brachii and examining the influence of forearm position on the strength of the reflex. Spike-triggered stimulation was used to assess the influence of radial nerve stimulation on the discharge of single motor units in the biceps brachii of 15 subjects. Stimulation of the radial nerve prolonged the interspike interval (P0.001) of motor units in the long (n = 31, 4.8 +/- 5.6 ms) and short heads (n = 26, 8.1 +/- 12.3 ms) of biceps brachii with no difference between the two heads (P = 0.11). The strength of inhibition varied with forearm position for motor units in both heads (n = 18, P0.05). The amount of inhibition was greatest in pronation (7.9 +/- 8.9 ms), intermediate in neutral (5.8 +/- 7.1 ms), and least in supination (2.8 +/- 3.4 ms). These findings indicate that the inhibition evoked by afferent feedback from brachioradialis to low-threshold motor units (mean force 3-5% MVC) in biceps brachii varied with forearm posture yet was similar for the two heads of biceps brachii. This reflex pathway provides a mechanism to adjust the activation of biceps brachii with changes in forearm position, and represents a spinal basis for a muscle synergy in humans.

The discharge of single motor units ( n = 34) in the first dorsal interosseus muscle and the fluctuations in force during steady contractions were measured across a range of index finger abduction forces in old adults (77.1 ± 6.9 yr, n = 20). These results were compared with previously reported data on 38 motor units from young adults (25.7 ± 5.7 yr). Both minimal and peak discharge rates increased with recruitment threshold, but the strength of these relations was notably weaker for the old adults. Minimal discharge rates were similar for young and old adults ( P = 0.77), whereas peak discharge rates were lower for old adults ( P < 0.01). Consequently, the range of rate coding for each motor unit was substantially less for the old adults (7.1 pps) compared with the young adults (12.1 pps, P < 0.01). However, the variability in motor-unit discharge was similar for young and old adults; the coefficient of variation of the interspike intervals was similar at recruitment (old: 25.4%, young: 27.1%, P = 0.39) and declined with an increase in discharge rate (old: 13.2%, young: 14.2%, P = 0.21). Furthermore, the fluctuations in force during steady isometric contractions (2–95% of maximal force) were similar for young and old adults, except that the relative variability at the lowest force was greater for the old adults. A computational model of motor-unit recruitment and rate coding incorporated the experimental observations and was able to match the measured and simulated values for force steadiness across the operating range of the muscle.

The purpose of this study was to compare the influence of prolonged vibration of a hand muscle on the amplitude of the stretch reflex, motor unit discharge rate, and force fluctuations during steady, submaximal contractions. Thirty-two young adults performed 10 isometric contractions at a constant force (5.0 ± 2.3% of maximal force) with the first dorsal interosseus muscle. Each contraction was held steady for 10 s, and then stretch reflexes were evoked. Subsequently, 20 subjects had vibration applied to the relaxed muscle for 30 min, and 12 subjects received no vibration. The muscle vibration induced a tonic vibration reflex. The intervention (vibration or no vibration) was followed by 2 sets of 10 constant-force contractions with applied stretches (After and Recovery trials). The mean electromyogram amplitude of the short-latency component of the stretch reflex increased by 33% during the After trials ( P < 0.01) and by 38% during the Recovery trials ( P < 0.01). The standard deviation of force during the steady contractions increased by 21% during the After trials ( P < 0.05) and by 28% during the Recovery trials ( P < 0.01). The discharge rate of motor units increased from 10.3 ± 2.7 pulses/s (pps) before vibration to 12.2 ± 3.1 pps ( P < 0.01) during the After trials and to 11.9 ± 2.6 pps during the Recovery trials ( P < 0.01). There was no change in force fluctuations or stretch reflex magnitude for the subjects in the Control group. The results indicate that prolonged vibration increased the short-latency component of the stretch reflex, the discharge rate of motor units, and the fluctuations in force during contractions by a hand muscle. These adjustments were necessary to achieve the target force due to the vibration-induced decrease in the force capacity of the muscle.

The purpose of the study was to determine how long humans could sustain the discharge of single motor units during a voluntary contraction. The discharge of motor units in first dorsal interosseus of subjects (27.8 ± 8.1 years old) was recorded for as long as possible. The task was terminated when the isolated motor unit stopped discharging action potentials, despite the ability of the individual to sustain the abduction force. Twenty-three single motor units were recorded. Task duration was 21.4 ± 17.8 min. When analysed across discharge duration, mean discharge rate (10.6 ± 1.8 pulses s(-1)) and mean abduction force (5.5 ± 2.8% maximum) did not change significantly (discharge rate, P = 0.119; and abduction force, P = 0.235). In contrast, the coefficient of variation for interspike interval during the initial 30 s of the task was 22.2 ± 6.0% and increased to 31.9 ± 7.0% during the final 30 s (P0.001). All motor units were recruited again after 60 s of rest. Although subjects were able to sustain a relatively constant discharge rate, the cessation of discharge was preceded by a gradual increase in discharge variability. The findings also showed that the maximal duration of human motor unit discharge exceeds that previously reported for the discharge elicited in motor neurons by intracellular current injection in vitro.

Background. Two major routes by which cytotoxic T lymphocytes induce apoptosis in target cells are the perforin-granzyme and the Fas ligand/Fas pathways. Intragraft expression of message for these immune activation genes has been shown to correlate very closely with clinical rejection. We have immunolabeled fine-needle aspiration biopsy samples using a panel of cytotoxic T-cell activation markers to evaluate the immunocytochemical identification of the protein products of these genes in the verification of human renal allograft rejection. Methods. In this retrospective pilot study, 140 fineneedle aspiration biopsy samples from 50 human renal allografts were labeled using alkaline phosphatase/ anti-alkaline phosphatase immunocytochemistry incorporating monoclonal antibodies to perforin, granzyme B, and Fas ligand. Levels of positive labeling for these markers were compared with the original clinical diagnosis of rejection. Results. An excellent correlation with clinical rejection was obtained when all three antibodies were positive. The false positive rate for each antibody was sufficient to make any one alone or in combination with one other unreliable for diagnosing rejection. When all three antibodies gave positive labeling, agreement with clinical rejection status was superior to using conventional morphological cytology. Conclusions. In addition to providing valuable morphological information regarding the composition of inflammatory leukocyte populations and the preservation status of renal parenchymal cells, fine-needle aspiration biopsy samples may be labeled using combined perforin, granzyme B, and Fas ligand immunocytochemistry to offer a safe and reliable method for diagnosing rejection with an excellent level of accuracy. Acute and chronic rejection are still the major causes of renal allograft loss despite major advances in immunosuppression and transplant management. Acute rejection has been shown to be the strongest predictive factor of subsequent chronic rejection (1). Furthermore, a recent study has shown that kidneys undergoing an early acute rejection episode have poorer long-term survival even if the serum creatinine returns to the preacute episode level; the likelihood of chronic rejection is even greater if the serum creatinine fails to return to the baseline (2). Thus, the early diagnosis and treatment of acute cellular rejection remains of critical importance. The current gold standard for the diagnosis of rejection is needle-core biopsy (NCB) histopathology used in conjunction with clinical findings. Fine-needle aspiration cytology (FNAC) is used as a less-invasive method than NCB for investigating causes of suboptimal graft function including rejection and acute tubular necrosis. Fine-needle aspiration biopsy may be practiced safely on a daily basis to study changes in the composition and function of intragraft cell populations before, during, and after acute rejection episodes (3).

The purpose of the study was to compare the discharge characteristics of biceps brachii motor units of young and old adults when they performed steady, submaximal contractions while the arm supported different inertial loads. Young (28 ± 4 yr; n = 16) and old (75 ± 4 yr; n = 14) adults performed steady contractions with the elbow flexors at target forces set at either small (11.7 ± 4.4% maximum) or large (17.8 ± 6.5% maximum) differences below the recruitment threshold force of the motor unit ( n = 40). The task was to maintain an elbow angle at 1.57 rad until the motor unit was recruited and discharged action potentials for ∼120 s. Time to recruitment was longer for the larger target force difference (187 ± 227 s vs. 23 ± 46 s, P < 0.001). Once recruited, motor units discharged action potentials either repetitively or intermittently, with a greater proportion of motor units exhibiting the repetitive pattern for old adults. Discharge rate at recruitment and during the steady contraction was similar for the two target force differences for old adults but was greater for the small target force difference for young adults. Discharge variability was similar at recruitment for the two age groups but less for the old adults during the steady contraction. The greatest difference between the present results and those reported previously when the arm pulled against a rigid restraint was that old adults modulated discharge rate less than young adults across the two contraction intensities for both load types.

The purpose of this study was to compare the discharge characteristics of motor units recruited during an isometric contraction that was sustained with the elbow flexor muscles by older adults at target forces that were less than the recruitment threshold force of each isolated motor unit. The discharge times of 27 single motor units were recorded from the biceps brachii in 11 old adults (78.8 ± 5.9 yr). The target force was set at either a relatively small (6.6 ± 3.7% maximum) or large (11.4 ± 4.5% maximum) difference below the recruitment threshold force and the contraction was sustained until the motor unit was recruited and discharged action potentials for about 60 s. The time to recruitment was longer for the large target-force difference ( P = 0.001). At recruitment, the motor units discharged repetitively for both target-force differences, which contrasts with data from young adults when motor units discharged intermittently at recruitment for the large difference between recruitment threshold force and target force. The coefficient of variation (CV) for the first five interspike intervals (ISIs) increased from the small (18.7 ± 7.9) to large difference (35.0 ± 10.2%, P = 0.008) for the young adults, but did not differ for the two target force differences for the old adults (26.3 ± 14.7 to 24.0 ± 13.1%, P = 0.610). When analyzed across the discharge duration, the average CV for the ISI decreased similarly for the two target-force differences ( P = 0.618) in old adults. These findings contrast with those of young adults and indicate that the integration of synaptic input during sustained contractions differs between young and old adults.

The goal of this study was to improve the ability of a motor unit model to predict experimentally measured force variability across a wide range of forces. Motor unit discharge characteristics were obtained from 38 motor units of the first dorsal interosseus muscle. Motor unit discharges were recorded in separate isometric contractions that ranged from 4 to 85% of the maximal voluntary contraction (MVC) force above recruitment threshold. High-threshold motor units exhibited both greater minimal and peak discharge rates compared with low-threshold units ( P < 0.01). Minimal discharge rate increased from 7 to 23 pps, and peak discharge rate increased from 14 to 38 pps with an increase in recruitment threshold. Relative discharge rate variability (CV) decreased exponentially for each motor unit from an average of 30 to 13% as index finger force increased above recruitment threshold. In separate experiments, force variability was assessed at eight force levels from 2 to 95% MVC. The CV for force decreased from 4.9 to 1.4% as force increased from 2 to 15% MVC ( P < 0.01) and remained constant at higher forces (1.2–1.9%; P = 0.14). When the motor unit model was revised using these experimental findings, discharge rate variability was the critical factor that resulted in no significant difference between simulated and experimental force variability ( P = 0.22) at all force levels. These results support the hypothesis that discharge rate variability is a major determinant of the trends in isometric force variability across the working range of a muscle.