Static versus dynamic predictions of protective stepping following waist-pull perturbations in young and older adults

The purposes of this study were: (1) to determine the frequency of protective stepping for balance recovery in subjects of different ages and fall-status, and (2) to compare predicted stepping based on a dynamic model (Pai and Patton, 1997. Journal of Biomechanics 30, 347 354) involving displacement and velocity combinations of the center of mass (COM) versus a static model based on displacement alone against experimentally induced stepping. Responses to three different magnitudes of forward waist pulls were recorded for 13 young, 18 older-non-fallers and 18 older-fallers. The COM phase plane trajectories derived from motion analysis were compared with the model-predicted threshold values for stepping. We found that the older fallers had the highest percentage of stepping trials (52%), followed by older-non-fallers (17.3%), and young (2.7%) at the lowest perturbation level. Younger subjects stepped less often than the elderly at the middle level. Everyone consistently stepped at the highest level of perturbation. Overall, the dynamic model showed better predictive capacity (65%) than the static model (5%) for estimating the initiation of stepping. Furthermore, the threshold for step initiation derived from the dynamic model could consistently predict when a step must occur. However, it was limited, especially among older fallers at the low perturbation level, in that it considered some steps 'unnecessary' that were presumably triggered by fear of falling or other factors.     

The Relationships Between Hope and Outcomes at the Pretreatment, Beginning, and Later Phases of Psychotherapy.

Individual differences in self-reported hope assessed before and during treatment were related to outcome markers of therapeutic improvement. Clients were assigned to either a motivational orientation group or a waiting list group. All clients thereafter received 12 weeks of individual therapy. As hypothesized, higher baseline hope was associated with greater client wellbeing, functioning and coping, and regulation of emotional distress and fewer symptoms. High- relative to low-hope clients also reported that the orientation group was significantly more helpful. As hypothesized, agency scores (tapping motivation) from baseline were associated with positive changes in outcome variables early in therapy, and pathways scores (tapping planfulness) from baseline were associated with positive changes in later therapy sessions. The implications of these findings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Estradiol concentrations in premenopausal women with coronary heart disease

BACKGROUND: Because of the beneficial effects of estrogen, premenopausal women are normally protected against coronary heart disease (CHD) and are at lower risk for myocardial infarction; consequently, CHD occurs very rarely in menstrually active women. Given this background, the aim of the present study was to test the hypothesis that decreased concentrations of estrogen are associated with CHD in premenopausal women. METHODS: Fourteen premenopausal women with CHD were investigated and compared with a healthy control group comparable for age and cardiovascular risk factors. Relevant characteristics of patients and controls were assessed: age, blood pressure, body mass index, total cholesterol and high-density lipoprotein cholesterol, triglycerides, former pregnancies, ovariectomy and related surgical interventions, smoking history and former use of oral contraceptives. To ensure the premenopausal status of the participants, the regularity of the menstrual cycle and the follicle-stimulating hormone concentrations were also assessed. Plasma estradiol and progesterone and urine estrone concentrations (24 h urine collection) were measured at day 6 after estimated ovulation to assess the relative increase in plasma estradiol and progesterone during the second half of the menstrual cycle. RESULTS: Compared with the control group, premenopausal women with CHD had significantly lower concentrations of plasma estradiol (408.9 +/- 141 pmol/l and 287.8 +/- 109 pmol/l respectively; P = 0.0228) and total estrogen (2061 +/- 693 pg/mumol creatinine and 1607 +/- 448 pg/mumol creatinine respectively; P = 0.025) in the urine. However, the progesterone concentrations were not significantly different between the groups. These findings might be explained by a partial ovarian dysfunction, as the patient group had a significantly higher number of tubal sterilizations (eight compared with one). CONCLUSION: Our data provide support for the hypothesis that decreased concentrations of estradiol might be an additional pathogenetic factor for the development of CHD in menstrually active premenopausal women.     

Photophysical investigations of Langmuir–Blodgett mono- and multilayer films of pheophorbide-a

Absorption, fluorescence and time-resolved fluorescence spectroscopy has been applied to quasi two-dimensional Langmuir–Blodgett monolayers and three-dimensional arrangements of Langmuir–Blodgett films with different numbers of layers. Pure dye films of pheophorbide-a and films in which pheophorbide-a molecules were embedded in a behenic acid matrix have been investigated. Optical spectroscopy is used in order to obtain evidence for intra- and interlayer interaction in the membrane-like environment and distinguish between these different types of interactions. Depending on how the dye molecule is embedded a broad range of π-system interactions occur. Optical band shifts as well as band shape changes and the formation of new bands are indicators for these molecular interactions [M.B. Grieve, A.J. Hudson, T. Richardson, Thin Solid Films, 1994, 243, 581.]. Among such interactions, exciton coupling and excimer formation are considered to be possible reasons for the observed major differences between spectra and kinetics of mono- and multilayer Langmuir–Blodgett films. Exciton coupling is indicated by red shifts of the Q-band of about 600 cm⁻¹ in the absorption spectra of monolayer films. The observed broad red shifted fluorescence in the near-infrared region and their short lifetimes (≤100 ps) are assigned to excimer formation. Time-resolved fluorescence spectra of bilayer films as well as polarization dependencies of the Langmuir–Blodgett film absorption are presented.     

2F1 antigen, the mouse homolog of the rat "mast cell function-associated antigen", is a lectin-like type II transmembrane receptor expressed by natural killer cells

Inhibitory lectin-like receptors expressed on the surface of hematopoietic cells are critically involved in regulation of their effector functions. Here we report that a novel mAb specific for mouse NK cells, 2F1, recognizes the mouse homolog of the mast cell function-associated antigen (MAFA), an inhibitory lectin-like transmembrane receptor expressed on rat mast cells. The 2F1 antigen (2F1-Ag) and rat MAFA are structurally highly conserved and contain a cytoplasmic motif similar to the immunoreceptor tyrosine-based inhibitory motif that is presumably utilized for inhibitory signaling. We also identified a human homolog that is closely related to the rodent MAFA/2F1-Ag proteins. Like rat MAFA, 2F1-Ag is probably encoded by a single gene, which exhibits relatively little polymorphism. Strikingly, while rat MAFA is considered a mast cell antigen, we have been unable to detect cell surface expression of 2F1-Ag by mouse mast cell lines, bone marrow-derived mast cells, or peritoneal mast cells. Furthermore, mouse bone marrow-derived mast cells were devoid of 2F1-Ag mRNA. Instead, we find that approximately 40% of mouse NK cells express 2F1-Ag. Thus, MAFA/2F1-Ag may modulate immunological responses on at least two different cell types bridging the specific and innate immune system.     

Scaffolds for Hard Tissue Engineering by Ionotropic Gelation of Alginate–Influence of Selected Preparation Parameters

Cylindrical constructs with parallel aligned pores were prepared by using ionotropic gelation of alginate/calcium phosphate hydroxyapatite (HAP) mixtures in regard to applications as scaffold for bone regeneration. The starting powder and stabilizing agents were characterized by measurement of electrosonic amplitude, particle size distribution, and specific surface. The shrinkage of the gels was investigated in dependence on the drying methods. The pore size relied on preparation conditions such as amount of HAP and concentrations of gelling agent or alginate sol. A wide field of pore sizes could be fabricated by varying the kind and concentration of additives. Micro computer tomography-investigations of freeze dried scaffolds demonstrated the pore progression over a length of 4 mm. The pore dimension and structure were adequate for cell seeding and blood capillary ingrowth. Biocompatibility was proven by in vitro experiments with human mesenchymal stem cells by fluorescence microscopy. A high stability of the wet gels was maintained under cell culture conditions for a period of 3 weeks.