A dual glucose and oxygen sensor in a polymer format was developed. The dual sensor composed of a blue emitter as the glucose probe, a red emitter as an oxygen probe, and a yellow emitter as a built-in reference probe which does not respond to either glucose or oxygen. All the three probes were chemically immobilized in a polyacrylamide-based matrix. Therefore, the dual sensor possesses three well separated emission colors and ratiometric approach is applicable for analysis of the glucose and oxygen concentration at biological conditions. The sensor was applied for real-time monitoring of glucose and oxygen consumption of bacterial cells, Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis), and mammalian cells of mouse macrophage J774 and human cervical cancer HeLa cell lines. On the other hand, in order to achieve satisfactory sensing performance for glucose, compositions of the matrices among poly(2-hydroxyethyl methacrylate), polyacrylamide, and poly(6-aminohexyl methacrylamide) which is a linker polymer for grafting the glucose probe, were optimized. 相似文献
To measure tissue oedema, the impression technique and a new tactile sensor technique are compared and evaluated in a silicone
rubber model and in an in vivo rat testis model. The principles of the two techniques differ in that the impression technique
evaluates interstitial fluid flow FT and peak force F(0) when tissue is compressed, whereas the tactile sensor evaluates the
hardness/softness or change in resonance frequency Δf when a vibrating rod is attached to tissue. Both techniques can detect
changes in silicone hardness/softness or in hormone-induced changes of testes, interstitial fluid. Although both F(0) and
FT are significantly correlated to Δf in the experiments, it is concluded that F(0) is the most promising impression parameter
to give valuable information about the hardness of living tissue as compared with Δf. The comparison indicates that the impression
technique in the most easy, to interpret, non-invasive tool to assess tissue oedema so far developed. 相似文献
The acoustic reflection method (ARM) is based on the analysis of the reflection of acoustic waves. The aim of the study was to determine the feasibility of the ARM in healthy children, and the anthropometric parameters that were correlated with the minimum cross-sectional area (MCAv) of the upper airways. Fifty-nine children (age 2-18 years) participated to the study. The mean MCAv value were 1.47±0.15, 1.77±0.33, 1.80±0.23, 2.06±0.42, 2.19±0.37, and 2.22±0.29cm(2), in the 2-3, 4-6, 7-9, 10-12, 13-15, and 16-18 year age groups, respectively. The MCAv values correlated significantly with height, age, and weight, but in a stepwise multiple regression analysis, only height remained correlated with the MCAv (r=0.59, p<0.0001). The analysis of the upper airways by the ARM is feasible in children after 2 years of age and the MCAv values increase with height in childhood. 相似文献
To produce a long-life, stable, miniature glucose sensor for a wearable artificial endocrine pancreas (WAEP), we developed
a novel microneedle-type glucose sensor using polyimide, designated the PI sensor (outer diameter, 0.3 mm; length, 16 mm),
and investigated its characteristics in vitro and in vivo. In the in vitro study, we tested the sensor in 0.9% NaCl solution
with varying glucose concentrations and observed an excellent linear relationship between the sensor output and glucose concentration
(range: 0–500 mg/100 ml). In in vivo experiments, the PI sensor was inserted into the abdominal subcutaneous tissue of beagle
dogs (n = 5), and interstitial fluid glucose concentrations were monitored after sensor calibration. Simultaneously, blood glucose
concentrations were also monitored continuously with another PI sensor placed intravenously. The correlation and time delay
between subcutaneous tissue glucose (Y) and blood glucose concentrations (X: 30–350 mg/100 ml) were Y = 1.03X + 7.98 (r = 0.969) and 6.6 ± 1.2 min, respectively. We applied the new WAEP system/PI sensor and an intravenous insulin infusion algorithm
developed previously for glycemic control in diabetic dogs. The use of the WAEP system resulted in excellent glycemic control
after an oral glucose challenge of 1.5 g/kg (post-challenge blood glucose levels: 176 ± 18 mg/100 ml at 65 min and 93 ± 23 mg/100 ml
at 240 min), without any hypoglycemia. Thus, we confirmed that our new PI sensor has excellent sensor characteristics in vitro
and in vivo. The new WAEP using this sensor is potentially suitable for clinical application. 相似文献
In this study the osmotic barrier characteristics of the rat peritoneal membrane were investigated. Fluid movements between the peritoneal cavity and the blood were measured following instillation of isotonic saline (control) and hypertonic solutions of NaCl, glucose, sucrose, raffinose and myoglobin (test solutions). Moreover, 5 and 8% albumin in NaCl were investigated. Osmotic transients were assessed using a simple volume recovery technique. Peritoneal osmotic conductances (i.e. products of peritoneal hydraulic conductances [LPS] and solute reflection coefficients [s?]) were calculated from the differences in the rates of peritoneal fluid loss and in osmotic pressures between test solutions and the isotonic saline control solution. The osmotic conductance to glucose was estimated to be 1.63/l min-1 mmHg-1 m-2 and that for albumin to be 59.6 μl min-1 mmHg-1 m-2. Assuming an albumin s? of 0.9, the s? of glucose was estimated to be 0.025, in accordance with previous measurements for the cat peritoneal membrane. The osmotic conductances assessed here were compatible with an overal? peritoneal equivalent small pore radius of 47–48 Å, but could also be fitted to a three-pore model of peritoneal permselectivity, including a transcellular (ultra-small pore) pathway and a large pore pathway. The great discrepancy between peritoneal s? for small solutes and that for albumin obtained in this study indicates that small solute reflection coefficients are close to zero while that for albumin is not far from unity. Furthermore, the peritoneal hydraulic conductance (ultrafiltration coefficient) is large enough to allow for a substantial absorption of fluid directly into the plasma when the crystalloid osmotic pressures in blood and peritoneal dialysate are in equilibrium. 相似文献
Applanation resonance tonometry (ART) has been shown in a number of studies to be useful for measuring intraocular pressure
(IOP). Data from in vitro laboratory bench testing, where the sensor was carefully centralised onto the cornea, has been very
consistent with good precision in the determination of IOP. However, in a clinical study the unavoidable off-centre placement
of the sensor against the cornea resulted in a reduced precision. The aim of this study was to evaluate a new design of the
sensor with a symmetric sensor probe and a contact piece with a larger diameter. Two in vitro porcine eye experimental set-ups
were used. One bench-based for examining position dependence and one biomicroscope-based set-up, simulating a clinical setting,
for evaluating IOPART precision at seven different pressure levels (10–40 mmHg), set by connecting a saline column to the vitreous chamber. The
reference IOP was recorded using a pressure transducer. There was no significant difference between four positions 1 mm off
centre and the one centre position. The precision of the ART as compared with the reference pressure was ±1.03 mmHg (SD, n=42). The design improvement has enhanced the precision of the ART in the biomicroscope set-up to be in parity with bench
test results from a set-up using perfect positioning. This indicates that off-centre positioning was no longer a major contributor
to the deviations in measured IOP. The precision was well within the limits set by ISO standard for eye tonometers. Therefore,
a larger in vivo study on human eyes with the ART should be performed. 相似文献
Summary The contours of pressure and flow of a pulse wave arriving at the entrance of a collapsed segment of an elastic tube can be described by application of the basic laws of reflection. The collapsed segment acts like a valve. It is opened by the pressure of the pulse wave when the pressure within the tube becomes higher than the collapse pressure, i.e. the pressure exerted on the segment from outside. This opening of the collapsed segment suddenly changes the sign of the pulse wave reflection from positive to negative; thus a typical contour change of the pulse proximal to the segment is observed. The most obvious effect is a reduction of the pulse pressure. The extent of this reduction is a function of the collapse pressure.A typical example of this phenomenon can be observed in an artery proximal to the segment which is collapsed due to the pressure exerted by an inflated Riva-Rocci cuff. The effect is explained by the assumption that the sign of reflection changes when the pressure of the pulse wave crosses the level of the cuff pressure. This explanation is supported by the results of model experiments. 相似文献
A rapid and sensitive radioenzymatic method for analysis of choline (Ch) and acetylcholine (ACh) concentrations in rat brain regions is described. The ACh content is obtained as the difference in Ch concentration between a hydrolysed and an unhydrolysed tissue sample. The ACh content was 16 ± 1.0 nmol/g in the cortex and 76 ± 2.4 nmol/g in the striatum, and the corresponding Ch values were 23 ± 2.5 and 33 ± 1.2. 相似文献
The existence of special microwave effects in the emulsion polymerization of styrene and methyl methacrylate with two different initiators is investigated. All the experiments are conducted in either Pyrex or silicon carbide reaction vessels employing a dedicated single‐mode microwave reactor and are monitored with a dual temperature‐measurement system consisting of an external infrared sensor and an internal fiber optical probe. The goal of this study is to study the influence of the electromagnetic field on both the decomposition rate of the radical initiators and on the emulsion polymerization itself. For both types of transformation, no direct influence of the electromagnetic field can be observed, therefore ruling out the occurrence of any type of specific or nonthermal microwave effects in these reactions.
We have reported that microwave cell death is a unique cell death preserving not only cell and nuclear shapes but also immunohistochemical antigenicity. However, their enzyme activity was lost, which indicated cell dysfunction and death. This peculiar observation implies that the microwave effect is likely an 'in situ' tissue fixation and that this type of cell death is morphologically different from cell death, by either oncosis or apoptosis, as previously known. To confirm whether this peculiar cell death was observed also in human tissue samples, we examined clinical samples from patients with metastatic liver cancer, which were treated with microwave irradiation. They were examined immunohistochemically for human Ki-67 antigen and proliferating cell nuclear antigen and enzyme histochemically for alkaline phosphatase, and the same morphological changes that were observed in microwave-treated rat liver were found. In conclusion, we believe that routine hematoxylin-eosin stain alone is not a suitable method to evaluate microwave treatment for cancer because microwave coagulation therapy-treated cells preserved their nuclei and cellular architectures, even after 3 months. For microwave-treated tumors, enzyme histochemistry is helpful to determine its effectiveness. 相似文献
A method permitting rapid and frequent determination of the total ionic concentration in renal tubular fluid samples, by measuring sample electrical impedance, is described. No special electrodes or sophisticated equipment are required. Since picoliter volumes are sufficient for measurement, tubular fluid dynamics are not significantly disturbed by the sampling procedure. The sample is aspirated into the tip of the standard glass micropipette and its ionic concentration, in the range of 100–1000 mmol/l, can be determined by any sensitive impedance-measuring device. In the present studies the Wheatstone bridge of the Wiederhielm apparatus for pressure measurement in micropuncture studies was used for the purpose. The obvious limitation of the method is that the measurements do not include nonelectrolytes and cannot differentiate between individual ion species. 相似文献
The relationship among viscosity and microwave absorptivity of organic solvents/polymers, the stirring rate, and the resulting errors in temperature measurement upon microwave dielectric heating is investigated. For a set of common solvents and polymers covering a broad range of viscosities and microwave absorptivities significant variations in the temperatures simultaneously recorded by external infrared sensors and internal fiber‐optic probes are experienced. The implications of these apparent difficulties in establishing the genuine reaction temperature for microwave‐heated viscous reaction systems are evaluated for a ring‐opening polymerization and for the synthesis of a surfactant. 相似文献