A surgical technique for individual control of the muscles of the rabbit lower hindlimb.

Little is known regarding the precise muscle, bone and joint actions resulting from individual and simultaneous muscle activation(s) of the lower limb. An in situ experimental approach is described herein to control the muscles of the rabbit lower hindlimb, including the medial and lateral gastrocnemius, soleus, plantaris and tibialis anterior. The muscles were stimulated using nerve-cuff electrodes placed around the innervating nerves of each muscle. Animals were fixed in a stereotactic frame with the ankle angle set at 90 deg. To demonstrate the efficacy of the experimental technique, isometric plantarflexion torque was measured at the 90 deg ankle joint angle at a stimulation frequency of 100, 60 and 30 Hz. Individual muscle torque and the torque produced during simultaneous activation of all plantarflexor muscles are presented for four animals. These results demonstrate that the experimental approach was reliable, with insignificant variation in torque between repeated contractions. The experimental approach described herein provides the potential for measuring a diverse array of muscle properties, which is important to improve our understanding of musculoskeletal biomechanics.

Pharmacogenomics in Stroke and Cardiovascular Disease: State of the Art.

There is considerable interindividual variability in the response to antiplatelet and anticoagulant therapies, and this variation may be attributable to genetic variants. There has been an increased understanding of the genetic architecture of stroke and cardiovascular disease, which has been driven by advancements in genomic technologies and this has raised the possibility of more targeted pharmaceutical treatments. Pharmacogenetics promises to use a patient's genetic profile to treat those who are more likely to benefit from a particular intervention by selecting the best possible therapy. Although there are numerous studies indicating strong evidence for the effect of specific genotypes on the outcomes of vascular drugs, the adoption of pharmacogenetic testing in clinical practice has been slow. This resistance may stem from sometimes conflicting findings among pharmacogenetic studies, a lack of stroke-specific randomized controlled trials to test the effectiveness of genetically-guided therapies, and the practical and cost-effective implementation of genetic testing within the clinic. Thus, this review provides an overview of the genetic variants that influence the individual responses to aspirin, clopidogrel, warfarin and statins and the different methods for pharmacogenetic testing and guidelines for clinical implementation for stroke patients.

Cigarette smoking and risk of severe infectious respiratory diseases in UK adults: 12-year follow-up of UK biobank.

BACKGROUND: The relevance of tobacco smoking for infectious respiratory diseases (IRD) is uncertain. We investigated the associations of cigarette smoking with severe IRD resulting in hospitalization or death in UK adults. METHODS: We conducted a prospective study of cigarette smoking and risk of severe IRD in UK Biobank. The outcomes included pneumonia, other acute lower respiratory tract infections (OA-LRTI) and influenza. Multivariable Cox regression analyses were used to estimate hazard ratios (HRs) of severe IRD associated with smoking habits after adjusting for confounding factors. RESULTS: Among 341 352 participants with no prior history of major chronic diseases, there were 12 384 incident cases with pneumonia, 7054 with OA-LRTI and 795 with influenza during a 12-year follow-up. Compared with non-smokers, current smoking was associated with ⁓2-fold higher rates of severe IRD (HR 2.40 [2.27-2.53] for pneumonia, 1.99 [1.84-2.14] for OA-LRTI and 1.82 [95% confidence interval: 1.47-2.24] for influenza). Incidence of all severe IRDs were positively associated with amount of cigarettes smoked. The HRs for each IRD (except influenza) also declined with increasing duration since quitting. CONCLUSIONS: Current cigarette smoking was positively associated with higher rates of IRD and the findings extend indications for tobacco control measures and vaccination of current smokers for prevention of severe IRD.

Trends in prevalence, treatment and control of hypertension in 38,825 adults over 36 years in Tromsø prospective study.

AIMS/BACKGROUND: Serial blood pressure surveys in cohort studies can inform public health policies to control blood pressure for prevention of cardiovascular diseases. METHODS: Mean levels of systolic blood pressure (SBP) were collected in six sequential surveys, involving 38,825 individuals aged 30-79 years (51% female), between 1979 and 2015 in the Tromsø Study in Norway. Mean levels of SBP, prevalence of hypertension and use of blood pressure-lowering treatment were estimated by age, sex and calendar year of survey. RESULTS: Age-specific mean levels of SBP in each decade of age increased by 20-25 mmHg in men and 30-35 mmHg in women and the prevalence of hypertension increased from 25% to 75% among adults aged 30-79 years. Among successive cohorts of adults aged 40-49 years at the time of the six surveys between 1979 and 2015, the mean levels of SBP declined by about 10 mmHg and the prevalence of hypertension declined from 46% to 25% in men and from 30% to 14% in women. The proportion of individuals with hypertension who were treated increased sixfold (from 7% to 42%) between 1979 and 2015, and the proportion of adults with hypertension that were successfully controlled also increased sixfold from 10% to 60% between 1979 and 2015. CONCLUSIONS: Although this study demonstrated a halving in the age-specific prevalence of hypertension in men and women and a sixfold increase in treatment and control of hypertension, the burden of hypertension remains high among older people in Norway.

The burden of risk factors for non-communicable disease in rural Bihar, India: a comparative study with national health surveys.

BACKGROUND: The incidence of non-communicable diseases (NCDs) is increasing in rural India. The National Family Health Survey-5 (NFHS-5) provides estimates of the burden of NCDs and their risk factors in women aged 15-49 and men aged 15-54 years. The aim of this study is to estimate the prevalence of hypertension and body-mass index (BMI) in adults aged 35-70 years in rural India and to compare these estimates, where age ranges overlap, to routinely available data. METHODS: The Non-Communicable Disease in Rural India (NCDRI) Study was a cross-sectional household survey of 1005 women and 1025 men aged 35-70 conducted in Bihar in July 2019. Information was collected on personal characteristics, self-reported medical history and physical measurements (blood pressure, height and weight). Prevalence estimates for hypertension (systolic blood pressure ≥ 140 mmHg or diastolic blood pressure ≥ 90 mmHg, or diagnosed and treated for hypertension), and for underweight (body-mass index < 18.5 kg/m2), normal weight (18.5-25.0 kg/m2) and overweight (≥ 25.0 kg/m2) were calculated. Where age ranges overlapped, estimates from the NCDRI Study were compared to the NFHS-5 Survey. RESULTS: In the NCDRI Study, the estimated prevalence of hypertension was 27.3% (N = 274) in women and 27.6% (N = 283) in men aged 35-70, which was three-times higher in women and over two-times higher in men than in the NFHS-5 Survey. One-quarter (23.5%; N = 236) of women and one-fifth (20.2%; N = 207) of men in the NCDRI Study were overweight, which was approximately 1.5 times higher than in the NFHS-5 Survey. However, where age groups overlapped, similar age-standardized estimates were obtained for hypertension and weight in both the NCDRI Study and the NFHS-5 Survey. CONCLUSION: The prevalence of NCDs in rural India is higher than previously reported due to the older demographic in our survey. Future routine national health surveys must widen the age range of participants to reflect the changing disease profile of rural India, and inform the planning of health services.

Correction: Vitamin D levels and risk of type 1 diabetes: A Mendelian randomization study.

[This corrects the article DOI: 10.1371/journal.pmed.1003536.].

Vitamin D levels and risk of type 1 diabetes: A Mendelian randomization study.

BACKGROUND: Vitamin D deficiency has been associated with type 1 diabetes in observational studies, but evidence from randomized controlled trials (RCTs) is lacking. The aim of this study was to test whether genetically decreased vitamin D levels are causally associated with type 1 diabetes using Mendelian randomization (MR). METHODS AND FINDINGS: For our two-sample MR study, we selected as instruments single nucleotide polymorphisms (SNPs) that are strongly associated with 25-hydroxyvitamin D (25OHD) levels in a large vitamin D genome-wide association study (GWAS) on 443,734 Europeans and obtained their corresponding effect estimates on type 1 diabetes risk from a large meta-analysis of 12 type 1 diabetes GWAS studies (Ntot = 24,063, 9,358 cases, and 15,705 controls). In addition to the main analysis using inverse variance weighted MR, we applied 3 additional methods to control for pleiotropy (MR-Egger, weighted median, and mode-based estimate) and compared the respective MR estimates. We also undertook sensitivity analyses excluding SNPs with potential pleiotropic effects. We identified 69 lead independent common SNPs to be genome-wide significant for 25OHD, explaining 3.1% of the variance in 25OHD levels. MR analyses suggested that a 1 standard deviation (SD) decrease in standardized natural log-transformed 25OHD (corresponding to a 29-nmol/l change in 25OHD levels in vitamin D-insufficient individuals) was not associated with an increase in type 1 diabetes risk (inverse-variance weighted (IVW) MR odds ratio (OR) = 1.09, 95% CI: 0.86 to 1.40, p = 0.48). We obtained similar results using the 3 pleiotropy robust MR methods and in sensitivity analyses excluding SNPs associated with serum lipid levels, body composition, blood traits, and type 2 diabetes. Our findings indicate that decreased vitamin D levels did not have a substantial impact on risk of type 1 diabetes in the populations studied. Study limitations include an inability to exclude the existence of smaller associations and a lack of evidence from non-European populations. CONCLUSIONS: Our findings suggest that 25OHD levels are unlikely to have a large effect on risk of type 1 diabetes, but larger MR studies or RCTs are needed to investigate small effects.

The role of clinical response to treatment in determining pathogenicity of genomic variants.

PURPOSE: The 2015 American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines for the interpretation of sequence variants provide a framework to standardize terminology in the classification of variants uncovered through genetic testing. We aimed to assess the validity of utilizing clinical response to therapies specifically targeted to a suspected disease in clarifying variant pathogenicity. METHODS: Five families with disparate clinical presentations and different genetic diseases evaluated and treated in multiple diagnostic settings are summarized. RESULTS: Extended evaluations indicated possible genetic diagnoses and assigned candidate causal variants, but the cumulative clinical, biochemical, and molecular information in each instance was not completely consistent with the identified disease. Initiation of treatment specific to the suspected diagnoses in the affected individuals led to clinical improvement in all five families. CONCLUSION: We propose that the effect of therapies that are specific and targeted to treatable genetic diseases embodies an in vivo physiological response and could be considered as additional criteria within the 2015 ACMG/AMP guidelines in determining genomic variant pathogenicity.

Initiating Pharmacologic Treatment in Tobacco-Dependent Adults. An Official American Thoracic Society Clinical Practice Guideline.

Background: Current tobacco treatment guidelines have established the efficacy of available interventions, but they do not provide detailed guidance for common implementation questions frequently faced in the clinic. An evidence-based guideline was created that addresses several pharmacotherapy-initiation questions that routinely confront treatment teams.Methods: Individuals with diverse expertise related to smoking cessation were empaneled to prioritize questions and outcomes important to clinicians. An evidence-synthesis team conducted systematic reviews, which informed recommendations to answer the questions. The GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach was used to rate the certainty in the estimated effects and the strength of recommendations.Results: The guideline panel formulated five strong recommendations and two conditional recommendations regarding pharmacotherapy choices. Strong recommendations include using varenicline rather than a nicotine patch, using varenicline rather than bupropion, using varenicline rather than a nicotine patch in adults with a comorbid psychiatric condition, initiating varenicline in adults even if they are unready to quit, and using controller therapy for an extended treatment duration greater than 12 weeks. Conditional recommendations include combining a nicotine patch with varenicline rather than using varenicline alone and using varenicline rather than electronic cigarettes.Conclusions: Seven recommendations are provided, which represent simple practice changes that are likely to increase the effectiveness of tobacco-dependence pharmacotherapy.

Body-mass index, blood pressure, diabetes and cardiovascular mortality in Cuba: prospective study of 146,556 participants.

BACKGROUND: Cardiovascular disease accounts for about one-third of all premature deaths (ie, age < 70) in Cuba. Yet, the relevance of major risk factors, including systolic blood pressure (SBP), diabetes, and body-mass index (BMI), to cardiovascular mortality in this population remains unclear. METHODS: In 1996-2002, 146,556 adults were recruited from the general population in five areas of Cuba. Participants were interviewed, measured (height, weight and blood pressure) and followed up by electronic linkage to national death registries until Jan 1, 2017; in 2006-08, 24,345 participants were resurveyed. After excluding all with missing data, cardiovascular disease at recruitment, and those who died in the first 5 years, Cox regression (adjusted for age, sex, education, smoking, alcohol and, where appropriate, BMI) was used to relate cardiovascular mortality rate ratios (RRs) at ages 35-79 years to SBP, diabetes and BMI; RR were corrected for regression dilution to give associations with long-term average (ie, 'usual') levels of SBP and BMI. RESULTS: After exclusions, there were 125,939 participants (mean age 53 [SD12]; 55% women). Mean SBP was 124 mmHg (SD15), 5% had diabetes, and mean BMI was 24.2 kg/m2 (SD3.6); mean SBP and diabetes prevalence at recruitment were both strongly related to BMI. During follow-up, there were 4112 cardiovascular deaths (2032 ischaemic heart disease, 832 stroke, and 1248 other). Cardiovascular mortality was positively associated with SBP (>=120 mmHg), diabetes, and BMI (>=22.5 kg/m2): 20 mmHg higher usual SBP about doubled cardiovascular mortality (RR 2.02, 95%CI 1.88-2.18]), as did diabetes (2.15, 1.95-2.37), and 10 kg/m2 higher usual BMI (1.92, 1.64-2.25). RR were similar in men and in women. The association with BMI and cardiovascular mortality was almost completely attenuated following adjustment for the mediating effect of SBP. Elevated SBP (>=120 mmHg), diabetes and raised BMI (>=22.5 kg/m2) accounted for 27%, 14%, and 16% of cardiovascular deaths, respectively. CONCLUSIONS: This large prospective study provides direct evidence for the effects of these major risk factors on cardiovascular mortality in Cuba. Despite comparatively low levels of these risk factors by international standards, the strength of their association with cardiovascular death means they nevertheless exert a substantial impact on premature mortality in Cuba.

Management of Acute Pain From Non-Low Back, Musculoskeletal Injuries : A Systematic Review and Network Meta-analysis of Randomized Trials.

BACKGROUND: Patients and clinicians can choose from several treatment options to address acute pain from non-low back, musculoskeletal injuries. PURPOSE: To assess the comparative effectiveness of outpatient treatments for acute pain from non-low back, musculoskeletal injuries by performing a network meta-analysis of randomized clinical trials (RCTs). DATA SOURCES: MEDLINE, EMBASE, CINAHL, PEDro (Physiotherapy Evidence Database), and Cochrane Central Register of Controlled Trials to 2 January 2020. STUDY SELECTION: Pairs of reviewers independently identified interventional RCTs that enrolled patients presenting with pain of up to 4 weeks' duration from non-low back, musculoskeletal injuries. DATA EXTRACTION: Pairs of reviewers independently extracted data. Certainty of evidence was evaluated by using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach. DATA SYNTHESIS: The 207 eligible studies included 32 959 participants and evaluated 45 therapies. Ninety-nine trials (48%) enrolled populations with diverse musculoskeletal injuries, 59 (29%) included patients with sprains, 13 (6%) with whiplash, and 11 (5%) with muscle strains; the remaining trials included various injuries ranging from nonsurgical fractures to contusions. Topical nonsteroidal anti-inflammatory agents (NSAIDs) proved to have the greatest net benefit, followed by oral NSAIDs and acetaminophen with or without diclofenac. Effects of these agents on pain were modest (around 1 cm on a 10-cm visual analogue scale, approximating the minimal important difference). Regarding opioids, compared with placebo, acetaminophen plus an opioid improved intermediate pain (1 to 7 days) but not immediate pain (≤2 hours), tramadol was ineffective, and opioids increased the risk for gastrointestinal and neurologic harms (all moderate-certainty evidence). LIMITATIONS: Only English-language studies were included. The number of head-to-head comparisons was limited. CONCLUSION: Topical NSAIDs, followed by oral NSAIDs and acetaminophen with or without diclofenac, showed the most convincing and attractive benefit-harm ratio for patients with acute pain from non-low back, musculoskeletal injuries. No opioid achieved benefit greater than that of NSAIDs, and opioids caused the most harms. PRIMARY FUNDING SOURCE: National Safety Council. (PROSPERO: CRD42018094412).

Added mass in rat plantaris muscle causes a reduction in mechanical work.

Most of what we know about whole muscle behaviour comes from experiments on single fibres or small muscles that are scaled up in size without considering the effects of the additional muscle mass. Previous modelling studies have shown that tissue inertia acts to slow the rate of force development and maximum velocity of muscle during shortening contractions and decreases the work and power per cycle during cyclic contractions; however, these results have not yet been confirmed by experiments on living tissue. Therefore, in this study we conducted in situ work-loop experiments on rat plantaris muscle to determine the effects of increasing the mass of muscle on mechanical work during cyclic contractions. We additionally simulated these experimental contractions using a mass-enhanced Hill-type model to validate our previous modelling work. We found that greater added mass resulted in lower mechanical work per cycle relative to the unloaded trials in which no mass was added to the muscle (P=0.041 for both 85 and 123% increases in muscle mass). We additionally found that greater strain resulted in lower work per cycle relative to unloaded trials at the same strain to control for length change and velocity effects on the work output, possibly due to greater accelerations of the muscle mass at higher strains. These results confirm that tissue mass reduces muscle mechanical work at larger muscle sizes, and that this effect is likely amplified for lower activations.

A modelling approach for exploring muscle dynamics during cyclic contractions.

Hill-type muscle models are widely used within the field of biomechanics to predict and understand muscle behaviour, and are often essential where muscle forces cannot be directly measured. However, these models have limited accuracy, particularly during cyclic contractions at the submaximal levels of activation that typically occur during locomotion. To address this issue, recent studies have incorporated effects into Hill-type models that are oftentimes neglected, such as size-dependent, history-dependent, and activation-dependent effects. However, the contribution of these effects on muscle performance has yet to be evaluated under common contractile conditions that reflect the range of activations, strains, and strain rates that occur in vivo. The purpose of this study was to develop a modelling framework to evaluate modifications to Hill-type muscle models when they contract in cyclic loops that are typical of locomotor muscle function. Here we present a modelling framework composed of a damped harmonic oscillator in series with a Hill-type muscle actuator that consists of a contractile element and parallel elastic element. The intrinsic force-length and force-velocity properties are described using Bézier curves where we present a system to relate physiological parameters to the control points for these curves. The muscle-oscillator system can be geometrically scaled while preserving dynamic and kinematic similarity to investigate the muscle size effects while controlling for the dynamics of the harmonic oscillator. The model is driven by time-varying muscle activations that cause the muscle to cyclically contract and drive the dynamics of the harmonic oscillator. Thus, this framework provides a platform to test current and future Hill-type model formulations and explore factors affecting muscle performance in muscles of different sizes under a range of cyclic contractile conditions.

Asymmetric Direct Reciprocal Connections Between Primary Visual and Somatosensory Cortices of the Mouse.

Several studies show direct connections between primary sensory cortices involved in multisensory integration. The purpose of this study is to understand the microcircuitry of the reciprocal connections between visual and somatosensory cortices. The laminar distribution of retrogradely labeled cell bodies in V1 and in the somatosensory cortex both in (S1BF) and outside (S1) the barrel field was studied to provide layer indices in order to determine whether the connections are of feedforward, feedback or lateral type. Single axons were reconstructed and the size of their swellings was stereologically sampled. The negative layer indices in S1 and S1BF and the layer index near zero in V1 indicate that the connection from S1BF to V1 is of feedback type while the opposite is of lateral type. The greater incidence of larger axonal swellings in the projection from V1 to S1BF strongly suggests that S1BF receives a stronger driver input from V1 and that S1BF inputs to V1 have a predominant modulatory influence.

Body Mass Index and Risk of Hospitalization or Death Due to Lower or Upper Respiratory Tract Infection.

This study assesses the associations between body mass index and risk of hospitalization for or death due to COVID-19, lower respiratory tract infections, and upper respiratory tract infections.

Opioids for Chronic Noncancer Pain: A Systematic Review and Meta-analysis.

Importance: Harms and benefits of opioids for chronic noncancer pain remain unclear. Objective: To systematically review randomized clinical trials (RCTs) of opioids for chronic noncancer pain. Data Sources and Study Selection: The databases of CENTRAL, CINAHL, EMBASE, MEDLINE, AMED, and PsycINFO were searched from inception to April 2018 for RCTs of opioids for chronic noncancer pain vs any nonopioid control. Data Extraction and Synthesis: Paired reviewers independently extracted data. The analyses used random-effects models and the Grading of Recommendations Assessment, Development and Evaluation to rate the quality of the evidence. Main Outcomes and Measures: The primary outcomes were pain intensity (score range, 0-10 cm on a visual analog scale for pain; lower is better and the minimally important difference [MID] is 1 cm), physical functioning (score range, 0-100 points on the 36-item Short Form physical component score [SF-36 PCS]; higher is better and the MID is 5 points), and incidence of vomiting. Results: Ninety-six RCTs including 26 169 participants (61% female; median age, 58 years [interquartile range, 51-61 years]) were included. Of the included studies, there were 25 trials of neuropathic pain, 32 trials of nociceptive pain, 33 trials of central sensitization (pain present in the absence of tissue damage), and 6 trials of mixed types of pain. Compared with placebo, opioid use was associated with reduced pain (weighted mean difference [WMD], -0.69 cm [95% CI, -0.82 to -0.56 cm] on a 10-cm visual analog scale for pain; modeled risk difference for achieving the MID, 11.9% [95% CI, 9.7% to 14.1%]), improved physical functioning (WMD, 2.04 points [95% CI, 1.41 to 2.68 points] on the 100-point SF-36 PCS; modeled risk difference for achieving the MID, 8.5% [95% CI, 5.9% to 11.2%]), and increased vomiting (5.9% with opioids vs 2.3% with placebo for trials that excluded patients with adverse events during a run-in period). Low- to moderate-quality evidence suggested similar associations of opioids with improvements in pain and physical functioning compared with nonsteroidal anti-inflammatory drugs (pain: WMD, -0.60 cm [95% CI, -1.54 to 0.34 cm]; physical functioning: WMD, -0.90 points [95% CI, -2.69 to 0.89 points]), tricyclic antidepressants (pain: WMD, -0.13 cm [95% CI, -0.99 to 0.74 cm]; physical functioning: WMD, -5.31 points [95% CI, -13.77 to 3.14 points]), and anticonvulsants (pain: WMD, -0.90 cm [95% CI, -1.65 to -0.14 cm]; physical functioning: WMD, 0.45 points [95% CI, -5.77 to 6.66 points]). Conclusions and Relevance: In this meta-analysis of RCTs of patients with chronic noncancer pain, evidence from high-quality studies showed that opioid use was associated with statistically significant but small improvements in pain and physical functioning, and increased risk of vomiting compared with placebo. Comparisons of opioids with nonopioid alternatives suggested that the benefit for pain and functioning may be similar, although the evidence was from studies of only low to moderate quality.