The effect of radiations on supercoiled plasmid DNA has been investigated by using atomic force microscopy (AFM). The DNA molecules were deposited on a substrate and observed by AFM. Alternatively, ...DNA at different scavenger concentrations was initially exposed to different types of radiations (alpha and X rays) at various doses. After irradiation, fragments (open circular and linearised strands) were observed corresponding to single strand breaks and double strand breaks in DNA. This result indicates the capabilities of AFM for the qualitative detection of strand modifications due to irradiation. The amount of each class of topology enables a quantitative response to be determined for both types of radiation (a,X). A value of the radiosensitivity of DNA was obtained as a function of the scavenger concentration. Strong accordance was found between AFM results and those obtained by use of gel electrophoresis. The advantage of AFM in comparison with traditional techniques is the possibility of analysing the radiation effects on one molecule. Indeed, taking the examples of alpha particles, it is shown that it is easy to measure the sizes of linear strands by AFM. Such additional or even precise results are difficult to obtain with gel electrophoresis since, in such a case, data are lost through smearing.
This study examined the effects of cycling posture on subsequent running performance similar to the transition phase of a triathlon. Experienced, non-elite triathletes completed two trials of a ...cycle-run transition. During the last three minutes of a 30 minute cycling bout, at power output equal to lactate threshold, subjects either remained seated (SEAT), or alternated seated and standing cycling (30 s at a time; ALT). Heart rate, RPE, minimum and maximum knee angle, stride frequency and length, and onset and duration of quadriceps and hamstrings activity were obtained at the end of a three-minute control run and at minutes 0, 2, & 4, of running after cycling transition. Repeated Measures ANOVA (condition X minute; p = 0.05) found control was significantly different than minute 0 for stride frequency and length, but not for minimum or maximum knee angle. EMG duration at minute 4 was less than all other time points for both quadriceps and hamstrings. Onset of muscle activity was not different for hamstring or quadriceps. Heart rate and RPE both increased over 15 minutes after transition and were higher for SEAT than ALT, however, there was no interaction (minute by position) for either variable. Results indicated changes in stride rate and length following cycling occur, but disappear within two minutes after the transition to running and do not differ between postures. Changes in duration of muscle activity may be related to changes in stride. Also HR and RPE differ between the SEAT and ALT cycling positions and over time.
Nedocromil sodium and sodium cromoglycate inhibited histamine release from rat peritoneal mast cells. Tachyphylaxis was observed with both drugs. The 2 compounds were extremely selective in their ...action, being less active against peritoneal mast cells from the hamster and completely ineffective against mast cells from the mouse. Human basophil leucocytes, tissue mast cells of the guinea-pig and rat intestinal mast cells were also unresponsive. Both drugs inhibited immunological histamine release from human pulmonary mast cells obtained by bronchoalveolar lavage (BAL) and, less effectively, from lung parenchyma. Nedocromil sodium was about 1 order of magnitude more potent than sodium cromoglycate in each case. Tachyphylaxis was observed with the dispersed lung, but not with the cells obtained by BAL, and the degree of inhibition varied inversely with the magnitude of the secretory response. The possible clinical significance of these observations is discussed.
Combinations of intense non-pharmaceutical interventions ('lockdowns') were introduced in countries worldwide to reduce SARS-CoV-2 transmission. Many governments have begun to implement lockdown exit ...strategies that allow restrictions to be relaxed while attempting to control the risk of a surge in cases. Mathematical modelling has played a central role in guiding interventions, but the challenge of designing optimal exit strategies in the face of ongoing transmission is unprecedented. Here, we report discussions from the Isaac Newton Institute 'Models for an exit strategy' workshop (11-15 May 2020). A diverse community of modellers who are providing evidence to governments worldwide were asked to identify the main questions that, if answered, will allow for more accurate predictions of the effects of different exit strategies. Based on these questions, we propose a roadmap to facilitate the development of reliable models to guide exit strategies. The roadmap requires a global collaborative effort from the scientific community and policy-makers, and is made up of three parts: i) improve estimation of key epidemiological parameters; ii) understand sources of heterogeneity in populations; iii) focus on requirements for data collection, particularly in Low-to-Middle-Income countries. This will provide important information for planning exit strategies that balance socio-economic benefits with public health.
PURPOSE: The Amputee Mobility Predictor (AMP) is a reliable and valid measure of an amputee's readiness to ambulate with a prosthesis. The purposes of the study was to determine the influence of ...various prosthetic foot and knee components on functional mobility using the AMP to control for the amputee's ambulation potential. SUBJECTS: A convenience sample of 145 lower extremity amputees with a mean age of 54.84 years (sd 18.6) who had completed prosthetic training were enrolled in the study. METHODS AND MATERIALS: Demographic information was collected, subjects completed the co-morbidity scale, performed the Six-Minute Walk test while wearing their prosthesis and were tested using the AMP without prosthesis (AMPnoPRO). The nature of their prosthetic componetry also was recorded. ANALYSIS: Multiple linear regression was conducted to determine the contribution of foot and knee componetry in predicting distance walked in six minutes. Age, AMPnoPRO score and comorbidity score were included in the regression model. RESULTS: The regression model including foot and knee componentry was statistically significant, F (8, 137) = 34.072, p is less than .0001, R.sup.2 = .67 and all components were significant in the model. A regression function was generated to allow prediction of distance walked in 6 minutes. The base equation yielded Y(6 minute distance) = -12.239 - 1.226 (age) + 7.956 (AMPnoPRO) B 6.235 (comorbidity score). Since knee and foot componentry were dummy coded, the additional distance walked can be directly estimated for any component type and combination via the table below.Component Expected additional distancecadence knee 57.12 manatomical knee 115.84 mmultiaxial foot 39.63 mdynamic foot 58.55 m CONCLUSION: The use of the AMPnoPRO makes it possible to predict the benefit of adding more sophisticated components to a prosthetic prescription. The results demonstrate the benefit of the anatomical knee between a transfemoral and transtibial amputee in regards to the increased distance walked when the knee is preserved. The value of this predictor instrument is that it allows the clinician prior to prosthetic fitting to predict the base distance an amputee can walk in 6 minutes when the age, AMPnoPRO and comorbidity score is known and then to further determine the additional value of upgrading prosthetic components. PL-RR-226-S Gailey RS, Roach KE, Applegate B, Cho B, Cunniffe B, Licht S, Maguire M; University of Miami School of Medicine, Division of Physical Therapy, Coral Gables, FL, USA.
The response of screen-printed thick-films of NiO/TiO/sub 2/ to organic solvent vapours was studied. It was found that these films displayed a significant resistance change in response to the vapours ...even at room temperature. The sensors displayed an inherent selectivity, proving most sensitive to toluene and propanol vapour; with comparatively low responses exhibited towards ethanol and methanol vapours. Very fast response and recovery times of 9 s and 16 s respectively were recorded for the devices upon exposure to 4000 ppm step changes in propanol concentration.
PDF
