11 research outputs found
Extramuscular myofascial force transmission alters substantially the acute effects of surgical aponeurotomy: assessment by finite element modeling
Effects of extramuscular myofascial force transmission on the acute effects of aponeurotomy were studied using finite element
modeling and implications of such effects on surgery were discussed. Aponeurotomized EDL muscle of the rat was modeled in
two conditions: (1) fully isolated (2) with intact extramuscular connections. The specific goal was to assess the alterations
in muscle length-force characteristics in relation to sarcomere length distributions and to investigate how the mechanical
mechanism of the intervention is affected if the muscle is not isolated. Major effects of extramuscular myofascial force transmission
were shown on muscle length-force characteristics. In contrast to the identical proximal and distal forces of the aponeurotomized
isolated muscle, substantial proximo-distal force differences were shown for aponeurotomized muscle with extramuscular connections
(for all muscle lengths F
dist > F
prox after distal muscle lengthening). Proximal optimal length did not change whereas distal optimal length was lower (by 0.5 mm).
The optimal forces of the aponeurotomized muscle with extramuscular connections exerted at both proximal and distal tendons
were lower than that of isolated muscle (by 15 and 7%, respectively). The length of the gap separating the two cut ends of
the intervened aponeurosis decreases substantially due to extramuscular myofascial force transmission. The amplitude of the
difference in gap length was muscle length dependent (maximally 11.6% of the gap length of the extramuscularly connected muscle).
Extramuscular myofascial force transmission has substantial effects on distributions of lengths of sarcomeres within the muscle
fiber populations distal and proximal to the location of intervention: (a) Within the distal population, the substantial sarcomere
shortening at the proximal ends of muscle fibers due to the intervention remained unaffected however, extramuscular myofascial
force transmission caused a more pronounced serial distribution towards the distal ends of muscle fibers. (b) In contrast,
extramuscular myofascial force transmission limits the serial distribution of sarcomere lengths shown for the aponeurotomized
isolated muscle in the proximal population. Fiber stress distributions showed that extramuscular myofascial force transmission
causes most sarcomeres within the aponeurotomized muscle to attain lengths favorable for higher force exertion. It is concluded
that acute effects of aponeurotomy on muscular mechanics are affected greatly by extramuscular myofascial force transmission.
Such effects have important implications for the outcome of surgery performed to improve impeded function since muscle in
vivo is not isolated both anatomically and mechanically
Novel mechanisms and functions of complement
Progress at the beginning of the 21st century transformed the perception of complement from that of a blood-based antimicrobial system to that of a global regulator of immunity and tissue homeostasis. More recent years have witnessed remarkable advances in structure-function insights and understanding of the mechanisms and locations of complement activation, which have added new layers of complexity to the biology of complement. This complexity is readily reflected by the multifaceted and contextual involvement of complement-driven networks in a wide range of inflammatory and neurodegenerative disorders and cancer. This Review provides an updated view of new and previously unanticipated functions of complement and how these affect immunity and disease pathogenesis
Sepsis and septic shock
For more than two decades, sepsis was defined as a microbial infection that produces fever (or hypothermia), tachycardia, tachypnoea and blood leukocyte changes. Sepsis is now increasingly being considered a dysregulated systemic inflammatory and immune response to microbial invasion that produces organ injury for which mortality rates are declining to 15-25%. Septic shock remains defined as sepsis with hyperlactataemia and concurrent hypotension requiring vasopressor therapy, with in-hospital mortality rates approaching 30-50%. With earlier recognition and more compliance to best practices, sepsis has become less of an immediate life-threatening disorder and more of a long-term chronic critical illness, often associated with prolonged inflammation, immune suppression, organ injury and lean tissue wasting. Furthermore, patients who survive sepsis have continuing risk of mortality after discharge, as well as long-term cognitive and functional deficits. Earlier recognition and improved implementation of best practices have reduced in-hospital mortality, but results from the use of immunomodulatory agents to date have been disappointing. Similarly, no biomarker can definitely diagnose sepsis or predict its clinical outcome. Because of its complexity, improvements in sepsis outcomes are likely to continue to be slow and incremental.SCOPUS: re.jinfo:eu-repo/semantics/publishe