Hamstring muscles: Architecture and innervation

Knowledge of the anatomical organization of the hamstring muscles is necessary to understand their functions, and to assist in the development of accurate clinical and biomechanical models. The hamstring muscles were examined by dissection in six embalmed human lower limbs with the purpose of clarifying their gross morphology. In addition to obtaining evidence for or against anatomical partitioning ( as based on muscle architecture and pattern of innervation), data pertaining to architectural parameters such as fascicular length, volume, physiological cross-sectional area, and tendon length were collected. For each muscle, relatively consistent patterns of innervation were identified between specimens, and each was unique with respect to anatomical organization. On the basis of muscle architecture, three regions were identified within semimembranosus. However, this was not completely congruent with the pattern of innervation, as a primary nerve branch supplied only two regions, with the third region receiving a secondary branch. Semitendinosus comprised two distinct partitions arranged in series that were divided by a tendinous inscription. A singular muscle nerve or a primary nerve branch innervated each partition. In the biceps femoris long head the two regions were supplied via a primary nerve branch which divided into two primary branches or split into a series of branches. Being the only muscle to cross a single joint, biceps femoris short head consisted of two distinct regions demarcated by fiber direction, with each innervated by a separate muscle nerve. Architecturally, each muscle differed with respect to parameters such as physiological cross-sectional area, fascicular length and volume, but generally all partitions within an individual muscle were similar in fascicular length. The long proximal and distal tendons of these muscles extended into the muscle bellies thereby forming elongated musculotendinous junctions. Copyright (C) 2005 S. Karger AG, Basel

7th Drug hypersensitivity meeting: part two

No abstract availabl

The present and future of QCD

This White Paper presents an overview of the current status and future perspective of QCD research, based on the community inputs and scientific conclusions from the 2022 Hot and Cold QCD Town Meeting. We present the progress made in the last decade toward a deep understanding of both the fundamental structure of the sub-atomic matter of nucleon and nucleus in cold QCD, and the hot QCD matter in heavy ion collisions. We identify key questions of QCD research and plausible paths to obtaining answers to those questions in the near future, hence defining priorities of our research over the coming decades

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Comparison of the sedative properties of CNS 7056, midazolam, and propofol in sheep

Background: CNS 7056 is an esterase-metabolized benzodiazepine sedative currently under development. Its short duration of action would suggest a clinical role similar to midazolam or propofol. Methods: The effect of a range of doses of CNS 7056, midazolam, and propofol on depth of sedation, the respiratory system, and the cardiovascular system was studied in chronically instrumented sheep (n¼5 or 6). The low, medium, and high doses of CNS 7056, midazolam, and propofol were 0.37, 0.74, and 1.47 mg kg21; 0.05, 0.1, and 0.2 mg kg21; and 1, 2, and 4 mg kg21, respectively. Results: CNS 7056 produced substantial sedation with rapid onset and offset for all doses, with duration rather than depth of sedation increasing with the dose. The lower doses of midazolam had minimal sedative effect; increasing the dose produced variable but longer term sedation. Sedation from propofol was comparable with that of CNS 7056 for the medium and high doses only. The high doses produced _20 min of sedation. All three drugs produced dose-dependent respiratory (e.g. reductions in arterial oxygen tension) and cardiovascular depression (e.g. reductions in mean arterial pressure). For CNS 7056, midazolam, and propofol, the magnitude of the cardiovascular and respiratory depression was proportional to the depth of sedation achieved for any given drug or dose. For all three drugs, the respiratory and cardiovascular depression was not of sufficient magnitude to endanger the animals. Conclusions: CNS 7056 is a powerful and short-acting anaesthetic in sheep with respiratory and cardiovascular effects consistent with its sedative/anaesthetic qualities.R. N. Upton, A. M. Martinez and C. Gran

Determination of the quality factor through the utilization of a balanced, tissue equivalent, ionization chamber

Accelerator dosimetry tends toward either specifying the field by way of its components or using a tissue equivalent chamber with a failsafe Quality Factor (QF). This investigation attempts a third approach, the determination of QF directly. A Lucite, three-parallel plate ionization chamber was constructed with a common center electrode and two independent outer electrodes. This configuration allows the position of the center electrode to be manually adjusted to effect first order balance; vernier balance is obtained electronically through adjustment of one of the paired electrometers. The chamber can be pressurized to at least 17 atm with a tissue equivalent gas mixture and, therefore, approximates tissue rad response. This ionization chamber is capable of detecting differences in LET of any radiation by operating on the principle of columnar recombination. The previous investigators use either a single ion chamber or operate their respective systems in the general recombination mode. This technique requires low polarizing voltages and, therefore, is useful only for low dose rates. Both the single chamber and the general recombination system are limited in accelerator dosimetry applications. Very high instantaneous dose rates and extreme variability of sources dictate a balanced ionization chamber system that utilizes columnar recombination. In the present instrument, one of the chambers is operated at low polarizing potential while the other is variable. The difference current between the two chambers is adjusted to zero for background levels and when sensing radiation this difference current is a measure of QF. In operation, the slope, with voltage, of the difference current is proportional to the QF of the radiation. This proportionality is apparently linear at 10 atm over a range of QF from one to at least 7.5. This response has been shown to be dose-rate independent. The directional dependence and pressure dependence of this chamber have been studied and will be reported

Cerebral and lung kinetics of morphine in conscious sheep after short intravenous infusions

© 2003 The Board of Management and Trustees of the British Journal of AnaesthesiaBackground. The analgesic effects of morphine are delayed relative to its concentration in blood. The rate of equilibration of morphine between blood and brain may contribute to this delay, but the kinetics of this process have not been modelled. This was determined in conscious instrumented sheep. The lung kinetics of morphine were also determined given their importance in defining systemic kinetics after i.v. bolus administration. Methods. Sheep were given short i.v. infusions of morphine (30 mg over 4 min). Cerebral kinetics were inferred from arterio–sagittal sinus concentration gradients and cerebral blood flow, and lung kinetics from the pulmonary artery–aortic gradient and cardiac output. These data were fitted to flow- and membrane-limited models of the kinetics in each organ. Results. Morphine had minimal cardiovascular effects, did not alter cerebral blood flow and caused insignificant respiratory depression. Lung kinetics were best described by a single distribution volume (2036 ml) with a first-order loss (1370 ml min–1), which was attributed to deep distribution. The cerebral kinetics of morphine were characterized by a significant permeability barrier. Permeability across the barrier (7.44 ml min–1) was estimated with good precision, and was approximately one-fifth of the nominal cerebral blood flow. The distribution volume of morphine in the brain was estimated with less precision, but was described by a brain:blood partition coefficient of approximately 1.4. The time required for 50% equilibration between brain and blood concentrations was approximately 10.3 min. Conclusion. The cerebral equilibration of morphine was relatively slow, and was characterized by significant membrane limitation.R. N. Upton, G. L. Ludbrook, A. M. Martinez, C. Grant and R. W. Miln