The detailed description of the influence of a chemical reaction on the dynamic behavior of a thin liquid film is of significant importance in many engineering and biological applications. In this ...paper, the dynamics of a thin liquid film on a solid substrate is followed until film rupture or formation of local contacts. A surface chemical reaction between insoluble surfactant molecules (receptors) on the free surface of the film and binding sites on the solid substrate is considered. Asymptotic expansion of the equations for fluid motion with van der Waals, capillary, and Marangoni forces leads to a model with three nonlinear evolution equations describing the dynamics of the surface deformation and the kinetics of free and bound receptors. Chemical and hydrodynamic modes are predicted and simulated numerically with different stability regimes: for a simple linear surface reaction, the concentration of receptors follows the deformation of the surface; for a nonlinear surface reaction with affinity enhanced at small distances, a clustering of receptors is observed at the local points of contact. A completely new regime is also obtained where the rupture (or contact) time is delayed by several orders of magnitude, and the concentrations and film thickness may oscillate. This study could be relevant to biological applications where adhesion between cells and substrates can be modeled by considering the dynamics of the thin film between them. The results are first compared with experiments on biological cells adhering to glass or other solid substrates where periodic patterns (wavelike morphologies) are observed with a clustering of adhesion receptors at the local contact points. A second possible application is the activation of T lymphocytes, a major immunological cell type, which requires the clustering of cell surface receptors by interaction of T-cell receptors with surface-bound ligands.
To compare the effects of predictive DNA testing on participants at risk for either Huntington disease (HD), or familial adenomatous polyposis (FAP), or hereditary breast and ovarian cancer (HBOC).
...Psychological distress was measured with the Impact of Event Scale before testing and at 1 week and 6 months after the test result, in individuals at 50% risk for either HD (N = 25), FAP (N = 23), or HBOC (N = 10).
A marginally significant trend was found indicating that carriers of the disease genes tended to show unchanged levels of distress during the study period whereas noncarriers showed the expected decrease. Men reported significantly less distress than women, and 1 week after the test result male noncarriers showed a sharp significant increase in the reported distress followed by a steady decline up to 6 months later.
The course of distress over time reported by carriers and noncarriers of the three disease genes was similar, which leads one to conclude that the previous experience with predictive testing for Huntington Disease may be a useful paradigm. However, those formerly at risk for HD reported more distress than those at risk for FAP and HBOC. From our clinical experience we learned that individuals at risk for FAP and HBOC are more inclined to ward off the emotions involved. Additional qualitative studies should be undertaken to investigate this.
To investigate the influence of the hormonal status on skin vascular reactivity, 18 males, 18 women using oral contraceptives (oc), 17 premenopausal, and 18 postmenopausal women were studied. Finger ...skin temperature (FST, in degrees C) and laser Doppler flux (LDF, in perfusion units) were measured during heating (45 degrees C water bath) and cooling (15 degrees C) followed by a subsequent recovery period. Maximal heat-induced vasodilation was significantly higher in women using oc and in premenopausal women when compared with males. During cooling, FST and LDF were significantly higher in males compared with women using oc and premenopausal women, respectively. FST was also higher in postmenopausal women than in women using oc. During recovery, FST and LDF were significantly higher in males than in women using oc, and LDF was also higher in males than in premenopausal women. These findings are consistent with a less pronounced and less prolonged cold-induced vasoconstriction in males. Other hemodynamic (blood pressure or heart rate) or biological factors (age, amount of subcutaneous fat, hand volume, or body mass index) that possibly influence peripheral blood flow were found not to influence the results. The observed differences in vascular reactivity toward temperature changes between subjects with a different hormonal status suggest that sex hormones influence finger skin perfusion.
Hysteroscopy is an endoscopic technique, allowing inspection of the intrauterine cavity. Diagnostic applications of the technique began to develop in the 1970s. Although it is often claimed that ...diagnosis under direct visualization is better than standard dilatation and curettage, it has not yet been proved that hysteroscopic diagnosis has better results than curettage. The clinical application of therapeutic hysteroscopy, mainly in the field of the treatment of abnormal uterine bleeding, started in the 1980s. Two thousand patients have been treated with either hysteroscopic myomectomy, endometrial resection, or endometrial laser ablation, according to the literature. No randomized trials have been conducted. The first clinical results of hysteroscopic treatment seem satisfactory, with average success rates of 85%. There is some evidence that the therapy is cost saving, because hysteroscopic procedures only require one or two nights in hospital. The technique is not yet widely diffused, mainly because of technical difficulties and lack of definite evidence on its effectiveness.
