scholarly journals Cultivation of Saccharomyces cerevisiae with Feedback Regulation of Glucose Concentration Controlled by Optical Fiber Glucose Sensor

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 565
Author(s):  
Lucie Koštejnová ◽  
Jakub Ondráček ◽  
Petra Majerová ◽  
Martin Koštejn ◽  
Gabriela Kuncová ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Optical Fiber ◽  
Glucose Concentration ◽  
Glucose Sensor ◽  
Ruthenium Complex ◽  
Feedback Regulation ◽  
Regulation System ◽  
Sensitive Layer ◽  
Average Deviation ◽  
Glucose Content

Glucose belongs among the most important substances in both physiology and industry. Current food and biotechnology praxis emphasizes its on-line continuous monitoring and regulation. These provoke increasing demand for systems, which enable fast detection and regulation of deviations from desired glucose concentration. We demonstrated control of glucose concentration by feedback regulation equipped with in situ optical fiber glucose sensor. The sensitive layer of the sensor comprises oxygen-dependent ruthenium complex and preimmobilized glucose oxidase both entrapped in organic–inorganic polymer ORMOCER®. The sensor was placed in the laboratory bioreactor (volume 5 L) to demonstrate both regulations: the control of low levels of glucose concentrations (0.4 and 0.1 mM) and maintenance of the glucose concentration (between 2 and 3.5 mM) during stationary phase of cultivation of Saccharomyces cerevisiae. Response times did not exceed 6 min (average 4 min) with average deviation of 4%. Due to these regulation characteristics together with durable and long-lasting (≥2 month) sensitive layer, this feedback regulation system might find applications in various biotechnological processes such as production of low glucose content beverages.

scholarly journals Simulation and Experimental Study of the Near Field Probe in the Form of a Folded Dipole for Measuring Glucose Concentration

2021 ◽  
Vol 11 (12) ◽  
pp. 5415
Author(s):  
Aleksandr Gorst ◽  
Kseniya Zavyalova ◽  
Aleksandr Mironchev ◽  
Andrey Zapasnoy ◽  
Andrey Klokov
Keyword(s):  
Experimental Measurement ◽  
Glucose Concentration ◽  
Field Experiments ◽  
Near Field ◽  
Vector Network Analyzer ◽  
Human Hand ◽  
Physical Parameters ◽  
Network Analyzer ◽  
Frequency Range ◽  
Average Deviation

The article investigates the near-field probe of a special design to account for changes in glucose concentration. The probe is designed in such a way that it emits radiation in both directions from its plane. In this paper, it was proposed to modernize this design and consider the unidirectional emission of the probe in order to maximize the signal and reduce energy loss. We have done extensive research for both bidirectional and unidirectional probe designs. Numerical simulations and field experiments were carried out to determine different concentrations of glucose (0, 4, 5.3, 7.5 mmol/L). Numerical modeling of a unidirectional probe showed that the interaction of radiation generated by such a probe with a multilayer structure simulating a human hand showed a better result and high sensitivity compared to a bidirectional probe. Further, based on the simulation results, a phantom (physical model) of a human hand was recreated from layers with dielectric properties as close as possible to the properties of materials during simulation. The probe was constructed from a copper tube and matched both the geometric and physical parameters of the model. The experimental measurement was carried out using a vector network analyzer in the frequency range 2–10 GHz. The experimental measurement was carried out using a vector network analyzer in the frequency range 2–10 GHz for the unidirectional and bidirectional probes. Further, the results of the experiment were compared with the results of numerical simulation. According to the results of multiple experiments, it was found that the average deviation between the concentrations was 2 dB for a unidirectional probe and 0.4 dB for a bidirectional probe. Thus, the sensitivity of the unidirectional probe was 1.5 dB/(mmol/L) for the bidirectional one 0.3 dB/(mmol/L). Thus, the improved design of the near-field probe can be used to record glucose concentrations.

scholarly journals Peritoneal dialysis fluid inhibition of phagocyte function: effects of osmolality and glucose concentration.

1993 ◽  
Vol 3 (8) ◽  
pp. 1508-1515
Author(s):  
T Liberek ◽  
N Topley ◽  
A Jörres ◽  
G A Coles ◽  
G M Gahl ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Lactate Dehydrogenase ◽  
Glucose Concentration ◽  
Lactate Concentration ◽  
Mononuclear Leukocytes ◽  
Dependent Manner ◽  
Dialysis Fluid ◽  
Glucose Content ◽  
Peritoneal Dialysis Fluid ◽  
Dialysis Fluids

Solutions were formulated to examine, independently, the roles of osmolality and glucose in the reduction of viability and inhibition of phagocyte function by dextrose-containing peritoneal dialysis fluids. The exposure of neutrophils (polymorphonuclear leukocytes) to test fluids containing > or = 2.7% (wt/vol) glucose resulted in significant cytotoxicity as assessed by the release of lactate dehydrogenase above control values (7.12 +/- 2.65%). At the highest concentration of glucose (4.5%), lactate dehydrogenase release was 15.83 +/- 0.49% (P < 0.05). These effects were directly related to the presence of D-glucose in the test fluids. In contrast, phagocytosis and the release of leukotriene B4 from PMN stimulated with serum-treated zymosan were significantly inhibited in an osmolality-, but not glucose-, dependent manner. The inhibition of tumor necrosis factor alpha and interleukin-6 release from mononuclear leukocytes was inhibited by a combination of osmolality and monosaccharide concentration. Under the same conditions, PMN respiratory burst activation remained unaffected irrespective of glucose concentration or fluid osmolality. These data indicate that, in addition to the low pH of peritoneal dialysis fluid and its high lactate concentration, its glucose content (either directly or as a consequence of the resulting hyperosmolality of the fluid) inhibits cell functional parameters. These findings suggest clinically significant inhibition of host defense mechanisms because, in high-glucose dialysis fluids, osmolality does not reach physiologic values, even during extended intraperitoneal dwell periods.

scholarly journals IR-Photometry Method for Measuring Glucose Concentration in Peritoneal Dialysis Fluid

2021 ◽  
Vol 24 (4) ◽  
pp. 68-78
Author(s):  
N. M. Zhilo ◽  
M. O. Mikhailov ◽  
E. L. Litinskaia ◽  
K. V. Pozhar
Keyword(s):  
Peritoneal Dialysis ◽  
Optical System ◽  
Glucose Concentration ◽  
Experimental Studies ◽  
The Body ◽  
Artificial Kidney ◽  
Dialysis Fluid ◽  
Glucose Content ◽  
Peritoneal Dialysis Fluid ◽  
Dialysate Solution

Introduction. The transition of glucose into the blood during automated peritoneal dialysis with regeneration of the dialysis fluid leads to a decreased removal of excess fluid from the body and corresponding violations of the water-salt balance.Aim. To consider a system for automatically maintaining the concentration of glucose in the dialysate solution, which provides effective ultrafiltration, as well as to propose a non-contact photometric feedback sensor.Materials and methods. The sensor is an optical system of an IR laser diode with a power of 30 mW and a wavelength of 1600 nm, a photodiode and a quartz tube, through which the test solution circulates. The sensor measures the attenuation of the radiation passing through the solution in a pulsed mode and calculates the glucose concentration. The selected combination of digital filters provides compensation for the noise of the optical system. Experimental studies of the efficiency of the sensor were carried out on peritoneal dialysis solutions with various concentrations of urea, creatinine, uric acid and glucose. At the beginning of the experiments, the sensor was calibrated in a pure solution.Results. It was shown that the developed sensor makes it possible to measure the concentration of glucose in a solution for peritoneal dialysis in the range of 42…220 mmol / l with a relative error of about 15%. The time of one measurement is about 1 minute, which makes it possible to obtain up-to-date information on the current concentration of the solution.Conclusion. This combination of characteristics will allow the sensor to be used in artificial kidney wearable devices for assessing the glucose content in the solution, calculating the time to change the solution and as a feedback sensor in a system for maintaining the concentration of the osmotic agent.

scholarly journals Development of hydrogel-based MEMS piezoresistive sensors for detection of solution pH and glucose concentration

2012 ◽  
Vol 34 (4) ◽  
pp. 281-288
Author(s):  
Trinh Quang Thong ◽  
Margarita Guenther ◽  
Gerald Gerlach
Keyword(s):  
Glucose Concentration ◽  
Glucose Sensor ◽  
Ph Sensor ◽  
Three Dimensional ◽  
Polymeric Materials ◽  
Dimensional Structure ◽  
Solution Ph ◽  
Pressure Transducers ◽  
Piezoresistive Sensors ◽  
Output Characteristics

Hydrogels are water-swollen polymeric materials that maintain a distinct three-dimensional structure. Manipulation of hydrogel structure has produced stimuli sensitive hydrogels, which change their swelling degree or undergo phase transition in response to minimal changes in environmental conditions. This paper presents the development of hydrogel-based sensors for measurement of solution pH and glucose concentration using commercial MEMS piezoresistive pressure transducers. pH-sensitive PVA/PAA and glucose-sensitive AAm/3-APB/BIS hydrogels are used in the experiments. Two types of sensor packaging, one is used as solution container and the other used to dip into solution have been performed. The measurements for different solutions having pH values between 1 to 11 and glucose concentrations between 2.5 mM and 15 mM have been carried out. The output characteristics of sensors have been demonstrated showing the long-term reproduction and relatively good sensitivity, namely approximately 20 mV/pH for pH sensor and 7 mV/1 mM of glucose concentration for glucose sensor.

Evaluation of a dipstick test for glucose in urine.

1976 ◽  
Vol 22 (2) ◽  
pp. 205-210 ◽  
Author(s):  
J Dyerberg ◽  
L Pedersen ◽  
O Aagaard
Keyword(s):  
Diabetes Mellitus ◽  
Total Variation ◽  
Urine Sample ◽  
Glucose Concentration ◽  
Dipstick Test ◽  
Glucose Content ◽  
Modifying Factors ◽  
Urinary Glucose ◽  
Different Types ◽  
Test Result

Abstract As an example of qualitative tests, a dipstick analysis for glucose in urine has been tested for the influence of modifying factors on the test result. Two different types of dipsticks were examined, "Clinistix" and "S-Gluko-test." Used according to manufacturer's instructions, the latter is more sensitive and selective. By multivariance analysis the following variables were examined: urine samples, inter- and intra-analyst, exposure to light, and dipstick batch. The first three contributed significantly to the total variation in results, inter-specimen variation being the most important. With knowledge of the frequency of testing urines with a given glucose concentration and the probability of the result at that concentration, an expression of the probability of the glucose content of a urine sample can be obtained. Even with the tests of the type examined having a sensitivity and specificity exceeding 95%, 14 of 100 patients suspected of having diabetes mellitus on the basis of a dipstick examination will be found to have a urinary glucose concentration of less than 2 mmol/liter. These figures were found when the prevalence of urines with a glucose concentration exceeding 2 mmol/liter was 17.5%.

Monitoring the Kinetics of Glucose Transfer across a Bioreactor Membrane with a Glucose Sensor

1989 ◽  
Vol 12 (8) ◽  
pp. 539-543 ◽  
Author(s):  
G. Velho ◽  
G. Reach
Keyword(s):  
Cell Culture ◽  
Flow Rate ◽  
Glucose Concentration ◽  
Culture Medium ◽  
Glucose Sensor ◽  
Hollow Fibers ◽  
Bioartificial Pancreas ◽  
Cell Compartment ◽  
Glucose Transfer ◽  
Kinetics Of

Bioreactors for cell culture, in which hollow fibers are sealed into a protective jacket, cells are seeded in the fibers’ outer surface and a culture medium circulates through the fibers, have been proposed as a bioartificial pancreas. We used a needle-type glucose sensor to study the kinetics of glucose transfer across the membrane of one such device. The glucose transfer was found to be dependent on the flow rate of the circulating medium, which suggests the involvement of an ultrafiltration flux across the membrane. The glucose concentration was heterogeneous within the cell compartment. This heterogeneity, and the delay in transmission of changes in glucose concentration from the circulating medium to the cell compartment, can be ascribed to the large volume of the compartment. The design of these bioreactors should therefore be modified, in order to meet the requirements of glucose transfer kinetics of a bioartificial pancreas.

Design of the Voltage Measurement and Feedback Regulation System of 100-kV High-Voltage Power Supply on J-TEXT Tokamak

2019 ◽  
Vol 47 (6) ◽  
pp. 2937-2942
Author(s):  
Shaoxiang Ma ◽  
Jin Jiao ◽  
Ming Zhang ◽  
Xueliang Zhang ◽  
Xiao Ma ◽  
...  
Keyword(s):  
High Voltage ◽  
Power Supply ◽  
Feedback Regulation ◽  
Regulation System ◽  
Voltage Measurement ◽  
High Voltage Power Supply

Effects of drink volume and glucose load on gastric emptying and postprandial blood pressure in healthy older subjects

2005 ◽  
Vol 289 (2) ◽  
pp. G240-G248 ◽  
Author(s):  
Karen L. Jones ◽  
Deirdre O’Donovan ◽  
Antonietta Russo ◽  
James H. Meyer ◽  
Julie E. Stevens ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Glucose ◽  
Gastric Emptying ◽  
Glucose Concentration ◽  
The Elderly ◽  
Gastric Distension ◽  
Oral Glucose ◽  
Glucose Content ◽  
Older Subjects ◽  
Hypotensive Response

Postprandial hypotension (PPH) occurs frequently in the elderly; the magnitude of the fall in blood pressure (BP) is related to the rate of glucose entry into the duodenum during intraduodenal glucose infusion and spontaneous gastric emptying (GE). It is unclear if glucose concentration affects the hypotensive response. Gastric distension may attenuate PPH; therefore, meal volume could influence the BP response. We aimed to determine the effects of 1) drink volume, 2) glucose concentration, and 3) glucose content on the BP and heart rate (HR) responses to oral glucose. Ten subjects (73.9 ± 1.2 yr) had measurements of BP, GE, and blood glucose on 4 days after 1) 25 g glucose in 200 ml (12.5%), 2) 75 g glucose in 200 ml (37.5%), 3) 25 g glucose in 600 ml (4%), and 4) 75 g glucose in 600 ml (12.5%). GE, BP, HR, and blood glucose were measured for 180 min. After all drinks, duodenal glucose loads were similar in the first 60 min. Regardless of concentration, 600-ml (but not 200-ml) drinks initially increased BP, and in the first 30 min, systolic BP correlated ( P < 0.01) with volume in both the proximal and total stomach. At the same concentration (12.5%), systolic BP fell more ( P = 0.02) at the smaller volume; at the same volumes, there were no effects of concentration on BP. There was no difference in the glycemic response to drinks of identical glucose content. We conclude that 1) ingestion of glucose at a higher volume attenuates and 2) under constant duodenal load, glucose concentration (4–37%) does not affect the fall in BP.

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