Folding sticky elastica: dynamics and reversibility of folds in Langmuir monolayers

Lipid monolayers at the air/water interface are often subject to large mechanical stresses when compressed laterally. For large enough compression they fold in the out-of-plane direction to relax stress. The repetitive folding and unfolding of lung surfactant monolayers during breathing plays a critical role in conserving monolayer material at the air/water interface lining the lung. Although the mechanisms behind the folding have been explored recently, relatively little information exists regarding the implications of folding dynamics on the long-term stability of the monolayer. We address this question by investigating the dynamical effect of folding rate in a lipid monolayer containing nano-particles, using a combination of analytic theory, simulation and experiment. We find that the presence of adsorbed particles are essential for monolayer rupture during unfolding. These particles act as linkers pinning the folds shut. The rate of folding affects reversibility as well. We construct a reversibility phase diagram spanned by the compression period and the size of the adsorbed particles showing the complex interaction of fold morphology, particle diffusion, and linker unbinding that results in reversible or irreversible folding.

Tissue distribution and variant characterization of human herpesvirus (HHV)-6: increased prevalence of HHV-6A in patients with multiple sclerosis

Human herpesvirus (HHV)-6 has been associated with the pathogenesis of multiple sclerosis (MS) on the basis of serologic, molecular, and histopathologic studies. This study sought to determine the distribution of HHV-6 in different MS body fluids, including serum, saliva, urine, and peripheral blood lymphocytes. The study results extend the observation of an increased frequency of HHV-6 DNA in serum of patients with MS to the unique detection of viral sequences in urine of a subset of patients with MS. Moreover, the HHV-6 identified in these cell-free compartments was predominantly the HHV-6A variant, which has been reported to be neurotropic. These results support the hypothesis that HHV-6 may contribute to the MS disease process.

Epidural analgesia following upper abdominal surgery: United Kingdom practice

BACKGROUND

Epidural Analgesia (EA) may be used to provide pain relief after upper abdominal surgery. A variety of drugs and combinations may be used. Potential side effects lead some to believe EA should be restricted to high care areas.

METHOD

The use of EA following upper abdominal surgery is surveyed in 214 hospitals in the United Kingdom by means of a postal questionnaire.

RESULTS

Sixty-seven percent use EA frequently and 3% not at all. The low thoracic site is the most commonly used, by 65%. Forty-eight percent use a combination of sites. EA is most frequently achieved using a mixture of an opioid and a local anaesthetic (97%). No other agents are used. Fentanyl and diamorphine are the opioids used most widely (61% and 52% departments, respectively) in combination with local anaesthetic. Subcutaneous heparin is regularly used in 89% of departments. In 43%, the epidural is sited shortly after administering heparin. Use of EA is restricted solely to intensive or high-care units in 46% of hospitals. In 82% of departments, EA is continued for up to 72 h. Ninety-six percent of departments use continuous epidural infusions in the post-operative period. Adjunct analgesia includes non-steroidal anti-inflammatory drugs in 50% of departments. An anaesthetist supervises EA in 89% of hospitals. EA is considered to be the best mode of analgesia available by 80% of respondents.

CONCLUSION

EA is widely used in the United Kingdom following upper abdominal surgery. A degree of consensus exists on the choice of drug types, their method of administration and duration. There is no consensus as to whether the technique should be used on a general ward, which opioid should be used or the timing of heparin.

Anaesthetic machine checking practices. A survey

Forty anaesthetists, of all grades, were interviewed without prior warning and questioned about the checks they had performed on their anaesthetic equipment before use. The results reveal that a substantial percentage (up to 41%) of anaesthetists perform inadequate checks. Furthermore, of those that do, few follow the Association of Anaesthetists of Great Britain and Ireland's recent guidelines.

Is this really a muscle cramp?

Most muscle cramps are benign, but cramps that occur on exertion or in a patient with abnormal findings on physical examination or electromyography are usually caused by significant systemic disease. The most common systemic causes are metabolic diseases; central or peripheral nervous system diseases are less often responsible. Most systemic diseases that cause muscle cramps are amenable to specific treatment. If symptomatic treatment is desired, the first choice would appear to be stretching. If that is ineffective, carisoprodol (Rela, Soma, Soprodol), vitamin E, or verapamil hydrochloride (Calan, Isoptin) may be used. Quinine sulfate (Quine, Quinamm) is potentially toxic and may not be effective.

Muscle disease--a primer

True weakness, especially in the proximal muscles, is a symptom of muscle disease. In differential diagnosis, conditions mimicking myopathy can be excluded on the basis of physical findings, various tests, and when appropriate, muscle biopsy. Once myopathy has been diagnosed, the physician needs to determine whether the cause is toxic, endocrine, inflammatory, metabolic, dystrophic, or congenital. The distinguishing features of these categories help in reaching a specific diagnosis. Because most of the common myopathies can be treated, recognition is important.