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.

A methodological approach for collecting simultaneous measures of muscle, aponeurosis, and tendon behaviour during dynamic contractions.

Skeletal muscles and the tendons that attach them to bone are structurally complex and deform non-uniformly during contraction. While these tissue deformations dictate force production during movement, our understanding of this behaviour is limited due to challenges in obtaining complete measures of the constituent structures. To address these challenges, we present an approach for simultaneously measuring muscle, fascicle, aponeurosis, and tendon behaviour using sonomicrometry. To evaluate this methodology, we conducted isometric and dynamic contractions in in situ rabbit medial gastrocnemius. We found comparable patterns of strain in the muscle belly, fascicle, aponeurosis, and tendon during the isometric trials to those published in the literature. For the dynamic contractions, we found that our measures using this method were consistent across all animals and aligned well with our theoretical understanding of muscle-tendon unit behaviour. Thus, this method provides a means to fully capture the complex behaviour of muscle-tendon units across contraction types.

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.

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.

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.

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.

Educational inequalities and premature mortality: the Cuba Prospective Study.

BACKGROUND: Although socioeconomic status is a major determinant of premature mortality in many populations, the impact of social inequalities on premature mortality in Cuba, a country with universal education and health care, remains unclear. We aimed to assess the association between educational level and premature adult mortality in Cuba. METHODS: The Cuba Prospective Study (a cohort study) enrolled 146 556 adults aged 30 years and older from the general population in five provinces from Jan 1, 1996, to Nov 24, 2002. Participants were followed up until Jan 1, 2017, for cause-specific mortality. Deaths were identified through linkage to the Cuban Public Health Ministry's national mortality records. Cox regression models yielded rate ratios (RRs) for the effect of educational level (a commonly used measure for social status) on mortality at ages 35-74 years, with assessment for the mediating effects of smoking, alcohol consumption, and BMI. FINDINGS: A total of 127 273 participants aged 35-74 years were included in the analyses. There was a strong inverse association between educational level and premature mortality. Compared with a university education, men who did not complete primary education had an approximately 60% higher risk of premature mortality (RR 1·55, 95% CI 1·40-1·72), while the risk was approximately doubled in women (1·96, 1·81-2·13). Overall, 28% of premature deaths could be attributed to lower education levels. Excess mortality in women was primarily due to vascular disease, while vascular disease and cancer were equally important in men. 31% of the association with education in men and 18% in women could be explained by common modifiable risk factors, with smoking having the largest effect. INTERPRETATION: This study highlights the value of understanding the determinants of health inequalities in different populations. Although many major determinants lie outside the health system in Cuba, this study has identified the diseases and risk factors that require targeted public health interventions, particularly smoking. FUNDING: UK Medical Research Council, British Heart Foundation, Cancer Research UK, CDC Foundation (with support from Amgen).

Varenicline for Tobacco-Dependent Adults Who Are Not Ready to Discontinue Use: A Systematic Review and Meta-Analysis.

Rationale: Not all individuals with tobacco dependence are ready to give up smoking. Research reveals behavioral differences between adults ready to discontinue tobacco use and those who are not. Thus, the interventions applied to these populations might differ. However, the evidence of using varenicline in individuals who are not ready to discontinue tobacco use is uncertain. Objectives: To determine if, in tobacco-dependent adults who report not being ready to discontinue tobacco use, clinicians should begin treatment with varenicline or wait until subjects are ready to discontinue tobacco use. Methods: We conducted a systematic review to assess the effectiveness and safety of treatment with varenicline in tobacco-dependent adults who are not ready to discontinue tobacco use. We systematically searched the Cumulative Index to Nursing and Allied Health Literature, Embase, MEDLINE, and the Cochrane Central Register of Controlled Trials to identify randomized controlled trials comparing varenicline versus placebo for individuals who were not ready to discontinue tobacco use. Outcomes of interest include point prevalence abstinence during treatment or at six months or longer, smoking reduction, motivation to quit, adverse events, and withdrawal symptoms. Two authors independently extracted data and assessed eligibility and risk of bias using a standardized data collection form. We followed the Grading of Recommendations, Assessment, Development and Evaluations approach to assess the certainty of evidence. Results: Five trials met our inclusion criteria. All 2,616 participants were adults who were not ready to discontinue tobacco use at study entry. For 7-day point prevalence abstinence at six months or longer, high-certainty evidence suggested that varenicline increased abstinence compared with placebo (relative risk, 2.00 [95% confidence interval (CI), 1.70-2.35]; absolute risk reduction, 173 more per 1,000 [95% CI, 121 more to 234 more]). We identified moderate-certainty evidence suggesting that varenicline increased serious adverse events (relative risk, 1.75 [95% CI, 0.98-3.13]; absolute risk reduction, 12 more per 1,000 [95% CI, 0 fewer to 35 more]). For withdrawal, low-certainty evidence suggested that varenicline treatment was associated with a lower symptom score (mean difference, 1.54 points lower; 95% CI, 2.15-0.93 points lower; low certainty) assessed using the Brief Questionnaire of Smoking Urges. Conclusions: In tobacco-dependent adults who are not ready to discontinue tobacco use, initiating varenicline treatment results in a large increase in abstinence and likely results in a slight increase in serious adverse events.