Viscoelastic properties of acid- and alkaline-treated human dermis: a correlation between total surface charge and elastic modulus

BACKGROUND: One of the major mechanical functions of collagenous tissues is the storage, transmission and dissipation of elastic energy during mechanical deformation. In skin, mechanical energy is stored during loading and then is transmitted and dissipated, which protects skin from mechanical failure. Thus energy storage (elastic properties) and dissipation (viscous properties) are important characteristics of extracellular matrices. METHODS: A uniaxial incremental stress relaxation test method has been used to characterize the time-dependent (viscous) and time-independent (elastic) properties of human dermis. Viscoelasticity was investigated in processed human dermis that was equilibrated at pHs of 3.0, 7.4 and 11.0 in an effort to study the link between electrostatic interactions within the collagen matrix and macroscopic tissue properties. RESULTS: Our results show that the solution pH and the charge on collagen significantly affected the high-strain elastic behavior of dermis; the elastic behavior of skin has previously been shown to be directly correlated with axial stretching of the collagen triple helix in crosslinked collagen fibrils. A positive linear correlation existed between the high-strain elastic modulus and both pH (R(2)=0.96) and the total number of charged residues on collagen (R(2)=0.93). These results provide in vitro/ex vivo evidence that charged groups on the surface of collagen molecules in processed human skin influence the high-strain elastic properties of dermis and are likely to be involved in elastic energy storage. CONCLUSION: It is proposed that the pH and charged residue dependency of the elastic modulus suggests that charged pair interactions and repulsions within and between collagen molecules are involved in elastic energy storage during stretching at high strains. It is hypothesized that elastic energy storage is associated with the stretching of pairs of charged amino acid residues that are found primarily in the flexible regions of collagen molecules.     

Nanocarrier-based interventions for the management of MDR/XDR-TB

Emergence of multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB over the past decade presents an unprecedented public health challenge to which countries of concern are responding far too slowly. Global Tuberculosis Report 2014 marks the 20th anniversary of the Global Project on Anti-Tuberculosis Drug Resistance Surveillance, indicating the highest global level of drug-resistance ever recorded detection of 97?000 patients with MDR-TB resulting in 170?000 deaths in 2013. Treatment of MDR-TB is expensive, complex, prolonged (18–24 months) and associated with a higher incidence of adverse events. In this context, nanocarrier delivery systems (NDSs) efficiently encapsulating considerable amounts of second-line anti tubercular drugs (^sATDs), eliciting controlled, sustained and more profound effect to trounce the need to administer ^sATDs at high and frequent doses, would assist in improving patient compliance and avoid hepatotoxicity and/or nephrotoxicity/ocular toxicity/ototoxicity associated with the prevalent ^sATDs. Besides, NDSs are also known to inhibit the P-glycoprotein efflux, reduce metabolism by gut cytochrome P-450 enzymes and circumnavigate the hepatic first-pass effect, facilitating absorption of drugs via intestinal lymphatic pathways. This review first provides a holistic account on MDR-TB and discusses the molecular basis of Mycobacterium tuberculosis resistance to anti-tubercular drugs. It also provides an updated bird’s eye view on current treatment strategies and laboratory diagnostic test for MDR-TB. Furthermore, a relatively pithy view on patent studies on second-line chemotherapy using NDSs will be discussed.     

The Diagnosis of Concussion in Pediatric Emergency Departments: A Prospective Multicenter Study

Background

The accurate identification of children with a concussion by emergency physicians is important to initiate appropriate anticipatory guidance and management.

A comparison of the epidemiology of ice hockey injuries between male and female youth in Canada

BACKGROUND:

Hockey is played by youth across Canada, and its popularity has increased dramatically among females in the past decade. Despite this, there has been little epidemiological research comparing the injury patterns of young female and male hockey players.

OBJECTIVE:

To describe and compare injuries sustained by female and male youth hockey players using the Canadian Hospitals Injury Reporting and Prevention Program database.

METHODS:

In the present cross-sectional, retrospective comparison study, the Canadian Hospitals Injury Reporting and Prevention Program database was used to identify all hockey-related injuries sustained by children seven to 17.5 years of age over a 15-year period (January 1995 to December 2009). Exclusion criteria included paid professional players and children with injuries sustained while playing road hockey.

RESULTS:

Inclusion criteria were met by 33,233 children (2637 [7.9%] females and 30,596 [92.1%] males). Compared with males, females reported proportionately more soft tissue injuries (39.8% versus 32.6%; P<0.01) and sprains/strains (21.1% versus 17.6%; P<0.01). Males experienced more fractures (27.1% versus 18.2%; P<0.01) and were most often injured through body checking (42.8% versus 25.7%; P<0.01). Females showed a trend toward increased concussion with age, and were most often injured through collisions (28.6% versus 24.6%; P<0.01).

CONCLUSION:

Compared with males, female hockey players sustained proportionately more soft tissue injures and sprains/strains, and showed a trend toward concussions in late adolecence. Males experienced more fractures, shoulder injuries and injuries due to body checking. Further research is required to identify risk factors for injury in female youth hockey players and to target injury prevention.     

Antibacterial and phytochemical screening of Anethum graveolens, Foeniculum vulgare and Trachyspermum ammi

Background  

Anethum graveolens Linn., Foeniculum vulgare Mill. and Trachyspermum ammi L. are widely used traditional medicinal plants to treat various ailments. To provide a scientific basis to traditional uses of these plants, their aqueous and organic seed extracts, as well as isolated phytoconstituents were evaluated for their antibacterial potential.     

Postdural puncture headache: The role of prophylactic epidural blood patch

Prophylactic epidural blood patch may prevent postdural puncture headache that develops after intentional or inadvertent dural puncture. However, despite earlier reports that this procedure was of value, subsequent studies have failed to show it has significant advantages over delayed blood patch. Reports that were supportive of this technique were based on nonrandomized observational studies with significant selective bias. At the present time, most centers do not routinely offer prophylactic blood patches, and those that do report a variable success rate. A recent case study of permanent neurologic deficit after prophylactic epidural blood patch has also raised some concern about the safety of this prophylactic technique.     

The reliability of the American Knee Society Score

We have investigated the reliability of the American Knee Society Score (AKS), a widely used functional outcome score for knee arthroplasty. 29 subjects were assessed in random order by 6 observers, each patient seen twice by each observer.The interobserver reference intervals were 16 points for the Knee Score (0-100 points) and 21 points for the Function Score (0-100 points). The intraobserver reference intervals were smaller, 11 points and 13 points for the Knee Score and the Function Score, respectively. The presence of arthritis in other joints and general debility did not affect the reliability of the scores. The more experienced observers had greater intraobserver reproducibility. Notably, we found moderate agreement between observers in the subjective variables, while the objective variables produced lower levels of agreement. The high inter- and intraobserver variations of the AKS makes estimation of score change questionable. Reliable use of the AKS would necessitate repeated evaluation by an experienced observer.     

A capaciflector provides continuous and accurate respiratory rate monitoring for patients at rest and during exercise

Journal of Clinical Monitoring and Computing - Respiratory rate (RR) is a marker of critical illness, but during hospital care, RR is often inaccurately measured. The capaciflector is a novel...