The development of whole cell biosensors for on-line screening of herbicide pollution of surface waters

The use of mediator assisted amperometric whole-cell biosensors, monitoring microbial photosynthetic electron transfer, to screen for herbicides in intake protection by the water industry is described. Cells harvested from axenic cultures are loaded onto bacteriological filters and held against a working carbon electrode polarised against the silver chloride reference. Redox mediators are reduced by the microorganisms and then reoxidised at the working electrode resulting in a flow of current. For on-line applications the sensors are controlled by a programmable electrochemical analyser (Artek) and housed in specially designed perspex flow cells which incorporate light emitting diodes (LEDs) for photosynthetic stimulation. A range of cyanobacteria and algae have been tested, but biosensors incorporating unicellular cyanobacteria have proven the most successful. Results obtained using the cyanobacterium Synechococcus show detection levels of less than 200 ppb with response times of less than ten minutes for selected herbicides. Sensor stability in the absence of pollutant poisoning has been found to be greatly influenced by the choice of mediator. Membrane penetrating mediators such as -benzoquinone reduce sensor life to about 24 hours, while a sensor life of up to six days has been achieved with ferricyanide.     

Sulfated glycosaminoglycans: a common constituent of all amyloids?

In the present investigation, we analyzed whether sulfated glycosaminoglycans are a common constituent in many different types of amyloid. Serial sections of amyloidotic tissue were stained for the presence of: (a) amyloid by using Congo Red, and (b) glycosaminoglycans by using both the sodium sulfate Alcian blue method and Alcian blue, pH 5.7, with varying concentrations of magnesium chloride. Our results show that sulfated glycosaminoglycans are always associated anatomically with amyloid deposits regardless of the nature of the protein deposited. Sulfated glycosaminoglycans were found in tissues containing AA, AL, inherited cutaneous amyloid, and senile cardiac amyloid (prealbumin). Additionally, we provide evidence that sulfated glycosaminoglycans are closely associated with the amyloid of medullary carcinoma of the thyroid (prothyrocalcitonin), and neuritic plaques, neurofibrillary tangles, and congophilic angiopathy in Alzheimer's disease. It is postulated that these sulfated glycosaminoglycans can influence the folding of diverse proteins such that all forms of amyloid show a significant beta-pleated sheet component.     

Die Dauererfolge der reinen Hg-Behandlung der Syphilis im Vergleich zu der kombinierten Salvarsan-Quecksilberbehandlung

Ohne Zusammenfassung     

Accelerometer-Measured Versus Self-Reported Physical Activity Levels and Sedentary Behavior in Women Before and 9 Months After Roux-en-Y Gastric Bypass

Background

Roux-en-Y gastric bypass (RYGB) patients report significant pre- to post-surgery increases in physical activity (PA). Conversely, objectively assessed PA does not increase after RYGB. The aim of the study was to compare self-reported and accelerometer-measured changes in moderate-to-vigorous PA (MVPA) and exercise from pre- to post-surgery, in women undergoing RYGB.

Methods

Forty-three women with an average pre-surgery body mass index of 39.2 kg/m2 (SD 3.1) were recruited at Swedish hospitals. PA was measured by the Actigraph GT3X+ and by a previously validated short PA questionnaire, at home visits 3 months before and 9 months after surgery, thus limiting seasonal effects.

Results

Self-reported time spent in exercise increased with 75 % and time spent in MVPA increased with 51 %, whereas accelerometer-assessed time spent in exercise increased with 0.9 % and time spent in MVPA increased with 2.1 %, from before to after surgery. Correlations comparing accelerometers with the questionnaire were 0.35 (P?=?0.02) for MVPA and 0.13 (P?=?0.4) for exercise before RYGB and 0.52 (P?≤?0.001) for MVPA and 0.12 (P?=?0.4) for exercise after RYGB.

Conclusions

Pre- to post-RYGB surgery increases in self-reported PA were not confirmed by accelerometer-measured PA. Thus, health care workers should use objective measures of PA in patients undergoing RYGB, in order to assess whether patients achieve sufficient levels of PA.

     

Meeting physical activity recommendations is associated with health-related quality of life in women before and after Roux-en-Y gastric bypass surgery

Quality of Life Research - Meeting physical activity (PA) recommendations is positively associated with health-related quality of life (HRQoL), but it is still unclear whether PA (specifically...     

Gas exchange in air sacs: contribution to respiratory gas exchange in ducks.

Air sac gas exchange was studied in ducks by measuring the rates of inert gas uptake and of O2 and CO2 equilibration in caudal thoracic air sac whose ventilation was prevented by surgival sealing of the ostia. The data were analyzed on a model incorporating three possible routes by which air sac gas could be exchanged with the surrounding tissue: (1) into the blood perfusing the air sac walls; (2) into the adjoining air sac via tissue membranes; (3) into the bronchial system of the lung via diffusion through lung tissue bordering upon the caudal thoracic air sac. Exchange rates of gases via the two latter paths were found to be small as compared with the first route. From application of model parameters to O2 and CO2 exchange in air sacs under physiological conditions the following conclusions were drawn: (1) the caudal thoracic air sac makes the major contribution to total gas exchange between air sacs and blood; (2) this exchange can account for less than 5% of total respiratory gas exchange; (3) the exchange is too small to account for the O2 and CO2 partial pressures in caudal thoracic air sacs of ducks. Other mechanisms like gas exchange in neopulmonic parabronchi, which conduct air to the caudal air sacs during inspiration or re-inspiration of dead space appear to play a more significant role in the deviation of O2 and CO2 partial pressures in the caudal air sacs from those in inspired air.