Measurement Of Blood Glucose Concentration Research Articles

Pretreatment with intraventricular basic fibroblast growth factor decreases infarct size following focal cerebral ischemia in rats

Basic fibroblast growth factor is a polypeptide with potent multipotential trophic effects on central nervous system cells, including neurons, glia, and endothelial cells. In particular, it promotes the survival of a wide variety of brain neurons in vitro, and protects these neurons against the effects of several neurotoxins, including excitatory amino acids, hypoglycemia, and calcium ionophore. Since lack of substrate delivery, excitatory amino acid toxicity, and calcium entry into cells appear to be important processes in neuronal death after ischemia, we tested the hypothesis that pretreatment with basic fibroblast growth factor limits infarct size in a model of focal cerebral ischemia in vivo. Mature male Long-Evans rats received either continuous intraventricular infusion of basic fibroblast growth factor (1.2 micrograms/day; with or without heparin, added to stabilize the growth factor) or vehicle alone for 3 days before focal ischemic infarcts were made in the right lateral cerebral cortex by permanent distal middle cerebral artery occlusion and temporary (45-minute) bilateral carotid occlusion. Intraoperative measurements of core temperature, arterial blood pressure and blood gases, blood glucose concentration, and hematocrit, and postoperative measurements of temperature revealed no differences among vehicle- versus basic fibroblast growth factor-treated animals. Twenty-four hours later, animals were killed, brains were removed and stained to visualize cortical infarcts, and infarct volume was determined by image analysis. Overall, we found a 25% reduction in infarct volume in basic fibroblast growth factor- (N = 25) versus vehicle-treated (N = 23) animals (p < 0.01). This reduction was not enhanced by the addition of heparin.(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive measurement of blood glucose concentrations by analysing Fourier transform infra-red absorbance spectra through oral mucosa.

Whether Fourier transform infra-red spectroscopy with an attenuated total reflection prism could be applied for noninvasive glucose measurement through oral mucosa was evaluated. As a result, the same absorbance peak at 1033 cm-1 as in glucose aqueous solution was found in the absorbance spectra through mucous membrane. However, these glucose specific peaks were interfered with by the baseline drifts owing to prism attachment and the background spectra from body constituents other than glucose. Therefore, to eliminate these interferences, the calibration curve between the second derivatives of the absorbance peak at 1033 cm-1 and those at 2920 cm-1 was calculated (r = 0.910). By using this calibration curve, the spectral changes due to prism attachment were first eliminated. Secondly, by obtaining the second derivative of the difference between the postprandial absorbance peak and the fasting sample as a characteristic of an individual, high correlations between the corrected second derivatives of absorbance spectra through the mucous membrane of the lip at 1033 cm-1 and the increases in blood glucose concentrations above fasting levels were observed (r = 0.910). In conclusion, it was suggested that Fourier transform infra-red spectroscopy could be useful for noninvasive monitoring of glucose through oral mucosa.

Fetal pancreatic β-cell function in pregnancies complicated by maternal diabetes mellitus: Relationship to fetal acidemia and macrosomia

Our purpose was to investigate the relationship between fetal pancreatic beta-cell function and fetal acidemia and macrosomia in pregnancies complicated by maternal diabetes mellitus. A cross-sectional study at the Harris Birthright Research Centre for Fetal Medicine, London, was performed. In 32 pregnancies complicated by maternal diabetes mellitus cordocentesis was performed at 36 to 39 weeks' gestation for the measurement of umbilical venous blood pH, PO2, PCO2, lactate, and glucose concentration; plasma insulin immunoreactivity; and insulin/glucose ratio. A reference range for plasma insulin and insulin/glucose ratio was constructed by studying fetal blood samples from 80 women who did not have diabetes mellitus. Mean umbilical venous blood pH was significantly lower and plasma insulin immunoreactivity and insulin/glucose ratio were significantly higher than the appropriate normal mean for gestation. There were significant associations between (1) maternal and fetal blood glucose concentrations (r = 0.95, p < 0.0001), (2) fetal blood glucose and plasma insulin immunoreactivity (r = 0.57, p < 0.01), (3) fetal plasma insulin immunoreactivity and blood pH (r = -0.39, p < 0.05), and (4) fetal insulin/glucose ratio and degree of macrosomia (r = 0.76, p < 0.0001). Fetal pancreatic beta-cell hyperplasia is implicated in the pathogenesis of both fetal acidemia and macrosomia.

Blood sampling through a peripheral venous infusion line.

The usefulness of a blood sampling technique for the measurement of blood glucose concentration through a peripheral venous infusion line was investigated with patients under general anesthesia. An infusion line was connected through a T-connector to a venous catheter indwelled in a forearm vein, and lactated Ringer's solution was infused at a flow rate of 100 ml/hour. At an arbitrary time, 0.5 ml of blood sample was obtained through the T-connector after discarding 1.5 ml of blood, while a vein in another arm was punctured to obtain 0.5 ml of blood. As a result, the glucose concentration in the samples from the venous infusion line was strongly correlated with that obtained by direct puncture, and the regression line passed through the origin. This suggests that blood sample from a peripheral venous line can be used in place of samples obtained by direct puncture.

Prediction of fetal acidaemia in pregnancies complicated by maternal diabetes mellitus by biophysical profile scoring and fetal heart rate monitoring.

To determine whether computer assisted fetal heart rate analysis or the biophysical profile score can provide noninvasive prediction of fetal acidaemia. Cross sectional study. Harris Birthright Research Centre for Fetal Medicine, King's College Hospital School of Medicine, London. Forty-one women with pregnancies complicated by diabetes mellitus. Fetal heart rate (FHR) monitoring with computer assisted analysis, biophysical profile score (BPS) and cordocentesis for measurement of umbilical venous blood glucose concentration and blood gases, up to 24 h before delivery at 27 to 39 weeks gestation. The mean umbilical venous blood pH was significantly lower than the normal mean for gestation, and was below the 5th centile in 18 pregnancies, including all six cases where the mother had nephropathy and hypertension. The mean pO2 was not significantly different from the normal mean for gestation. There were significant associations between fetal acidaemia and both the BPS (r = 0.46, P < 0.01) and FHR variation (r = 0.42, P < 0.01). However, of the 12 acidaemic fetuses of non-nephropathic mothers, nine had normal BPS and six had normal FHR variation. In pregnancies complicated by maternal diabetes mellitus, BPS and FHR variation are of limited value in the prediction of fetal blood pH.

A laser photoacoustic sensor for analyte detection in aqueous systems

Pulsed laser photoacoustic spectroscopy has been used as the basis for sensing analytes in aqueous systems. The spectra obtained with the photoacoustic system are significantly different from conventional transmission spectra and, in particular, the spectra of some organic solvents and alcohols show a marked enhancement in feature strength due to the dependence of physical and thermal factors in the photoacoustic generation process. The photoacoustic process has been shown to be almost immune to the effects of optical scattering, which gives this sensing technique advantages over conventional spectroscopic techniques in the potential application to water-pollution monitoring and to measuring blood-glucose concentrations.

Fetal plasma erythropoietin in pregnancies complicated by maternal diabetes mellitus

Our purpose was to investigate the relationship between fetal plasma erythropoietin concentration and measures of short-term and long-term glycemic control and fetal oxygenation in pregnancies complicated by maternal diabetes mellitus. A cross-sectional study was performed at The Harris Birthright Research Centre for Fetal Medicine, London. Cordocentesis was performed in 31 diabetic pregnancies for the measurement of umbilical venous blood pH, PO2, PCO2, lactate and glucose concentration, erythroblast count, hemoglobin, and plasma erythropoietin concentrations. The mean pH was significantly lower and the PCO2, lactate, erythropoietin, hemoglobin, and erythroblast counts were significantly higher than the appropriate normal mean for gestation. There were significant associations between (1) fetal erythropoietin and erythroblast count, (2) fetal erythroblast count and hemoglobin, (3) fetal hemoglobin and maternal glycosylated hemoglobin, and (4) maternal glucose and fetal glucose, pH, and lactate. We postulate that maternal hyperglycemia causes fetal hyperglycemia and acidemia. Increased erythropoietin may be caused by tissue hypoxia or hyperinsulinemia. The increase in fetal hemoglobin may be the consequence of increased erythropoiesis, mediated by either erythropoietin or hyperinsulinemia.

Effect of hydroxyethyl starch solutions on blood glucose concentrations in diabetic and nondiabetic rats.

The effects of iv infusions of 6% hetastarch or 10% pentastarch on blood glucose concentrations were tested in 12 nondiabetic and 12 streptozotocin-induced diabetic pentobarbital-anesthetized Sprague-Dawley rats weighing 313 to 473 g. All rats were paralyzed and mechanically ventilated. After control measurements of blood glucose concentrations were taken, rats were divided into four groups. Groups 1 (n = 6) and 2 (n = 6) comprised nondiabetic rats that received iv infusions of hetastarch or pentastarch, respectively, at a rate of 2.0 mL over 30 mins. Groups 3 (n = 6) and 4 (n = 6) comprised diabetic rats that also received iv hetastarch or pentastarch, respectively, at the same rate and duration of infusion. Neither hetastarch nor pentastarch infusions significantly altered blood glucose values over the 3-hr study period, regardless of whether the rats were diabetic or nondiabetic. Assuming these data are transferable to humans, the authors conclude that hydroxyethyl starch solutions do not produce or exacerbate hyperglycemia, and furthermore, that their use is not contraindicated in subjects having hyperglycemia from diabetes mellitus or iatrogenic causes.

Evaluation of the use of the reflectance meter by several operators in field screening for diabetes mellitus

The performance of reflectance meters for measuring blood glucose concentrations was evaluated in other studies previously and was found to be satisfactory. In the present study, we have evaluated the reliability of one brand of such meters (Glucometer II), when used by several operators, for blood glucose measurements during an epidemiological survey. We have compared the results obtained by the meter with those obtained by a standard hospital laboratory procedure for the same samples. A high and statistically significant degree of correlation ( r = 0.901) was observed between the two groups of measurements. The linear regression equation was Y = 0.9 X + 13.4. We conclude that the Glucometer II is an accurate and practical instrument even when used by several operators in epidemiological surveys provided that adequate training is given to those operators prior to using the instrument. This is important since the use of reflectance meters in epidemiological surveys is becoming increasingly widespread especially in the third world countries.

Capillary (Heelstick) versus Venous Blood Sampling for the Determination of Glucose Concentration in the Neonate

Various sites may be used to obtain blood (plasma) for the determination of the glucose concentration in the neonate. Because multiple sites may be sampled in the same neonate, it is important to determine the variability in blood glucose concentration which may result from such sampling. Since pain and mechanical forces may be different because of the method used to obtain the capillary (heelstick) blood compared to the venous specimen, the two sites were sampled, and the blood glucose concentration was determined simultaneously in 25 asymptomatic well neonates whose mean birth weight was 2,562 +/- 152 g and whose gestational age was 35.5 +/- 1.5 weeks. There was a significant (p less than 0.0001), but relatively weak correlation (r2 = 0.64) between capillary (heelstick) blood and venous blood relative to blood glucose concentration. When the capillary (heelstick)-venous glucose concentration difference was compared to the mean of the capillary (heelstick) and venous glucose concentrations, a difference of +/- 0.5 mM (9 mg/dl) was noted in 3 of 25 neonates. Appropriately obtained capillary (heelstick) blood samples provide measurement of blood glucose concentration which are variable compared to venous samples, but which are probably not significant physiologically.

A System for Peri‐operative Blood Glucose Control in Diabetes Mellitus

A pocket computer has been programmed to control the rate of administration of insulin given to diabetic patients having open heart surgery. Twelve diabetic patients were studied. Five had coronary artery bypass grafting, and seven had heart valve surgery. During operation 122 out of 162 (75%), and post-operatively 291 out of 360 (81%) blood glucose concentrations were between 4.0 and 8.0 mmol l-1. Five hundred and fifteen values out of 552 (99%) were below 12.0 mmol l-1. There was no hypoglycaemia. The lowest measured blood glucose concentration was 3.7 mmol l-1. The computer is readily available, easy to use by inexperienced personnel, and cheap.

Blood glucose measurement by multiple attenuated total reflection and infrared absorption spectroscopy

The difficulty of measuring physiological concentrations of glucose in blood by conventional infrared absorption spectroscopy is due to the intrinsic high background absorption of water. This limitation can be largely overcome by the use of a CO2 laser as an infrared source in combination with a multiple attenuated total reflection (ATR) technique. To demonstrate the applicability of this technique, we compared in vitro measurements of glucose in blood obtained from an experimental infrared laser spectrometer with independent measurements made by a standard YSI 23A laboratory glucose analyzer. The capability of continuous measurement of blood glucose concentration is of primary importance in the future development of a glucose sensor for diabetic patients.

An Evaluation of the Therapeutic Effects and Dosage Equivalence of Glyburide and Glipizide

Nineteen noninsulin-dependent diabetic patients [ten women, nine men, aged 36-80 years (mean +/- SE 56.8 +/- 2.7 years)] were randomized to receive either glyburide or glipizide for 16 weeks, in a double-blind crossover fashion. A 2-week washout period preceded each treatment period. The patients measured blood glucose concentrations 16 times weekly using Chemstrip-bG. The medication dosages were titrated to achieve fasting blood glucose concentrations of less than or equal to 6.2 mM and preprandial and postprandial concentrations of less than or equal to 9.0 mM, or to a total daily dose of 20 mg for glyburide and 40 mg for glipizide. Glyburide therapy resulted in a significant decline in fasting, preprandial, postprandial and bedtime blood glucose levels, while glipizide treatment led to a significant lowering of postprandial and bedtime blood glucose. Furthermore, fasting, preprandial and postprandial blood glucose concentrations were significantly lower during glyburide as compared to glipizide treatment phase. Glycosylated hemoglobin levels were decreased only with glyburide. Serum C-peptide and insulin concentrations were not altered over the entire study. The mean final daily dose of glyburide (15.4 +/- 1.6 mg) was markedly lower than that of glipizide (29.7 +/- 3.1 mg). Thus, in this patient population, glyburide was twice as potent on a weight basis than glipizide.

Intra-operative blood glucose and serum insulin concentrations in the surgical management of insulinoma

The surgical management of insulinoma is frequently complicated by difficulty in pre- and intra-operative localization of the tumour. An early and reliable post-operative indicator of successful surgery would therefore be useful in the management of this condition. In a prospective, controlled study serial measurements of blood glucose and serum insulin concentrations were performed in 5 patients with insulinoma during surgical removal of the tumour. Results were compared with 5 patients, matched for age and body weight, undergoing abdominal surgery for non-malignant disease. Serum insulin (mean +/- s.e.m.) was significantly elevated in the insulinoma patients at the start of surgery (32.1 +/- 3.1 vs 6.1 +/- 2.2 mU/l; P less than 0.01). A significant fall (P less than 0.01) to levels comparable with the control patients (7.5 +/- 1.8 vs 10.0 +/- 3.3 mU/l) occurred following removal of the tumour. We conclude that serial intra-operative measurements of serum insulin concentration are technically simple to perform and provide useful retrospective corroboration of successful surgery in patients with insulinoma.

Evaluation of a rapid reagent strip test for blood glucose determination in diarrheic calves.

Sixty-three blood samples from 10 diarrheic calves were tested for glucose concentration by two methods. Plasma glucose concentration was measured by the conventional glucose-6-phosphate dehydrogenase method in the clinical laboratory, and the results compared to those obtained using a rapid reagent strip test for blood glucose concentration measurement. The rapid reagent strip test result could not be used to make an accurate prediction of the actual plasma glucose concentration as determined by the conventional method, due to the wide variability in actual plasma glucose concentrations corresponding to each rapid test result.

How well do nurses perform blood glucose analyses at the diabetic clinic? An assessment using the Reflotron analyser.

The performance of nursing staff in the measurement of blood glucose concentrations of patients attending a diabetic outpatient clinic was assessed. The nurses used a Reflochek reflectance meter with BMR Reflochek glucose strips. The BCL Reflotron portable analyser was first assessed for accuracy by laboratory staff, and then used at the clinic to compare with the glucose results obtained by the nurses. The aim was to identify variables affecting their analyses

The clinical value of glycated haemoglobin and glycated plasma proteins.

The biochemical diagnosis of diabetes mellitus and assessment of the management of diabetic patients have been based on measurement of blood glucose concentration under a variety of conditions since before the introduction of insulin therapy in 1922. The first clinically applicable method for the quantitation of blood sugar! and the earliest description of the blood sugar response to the ingestion of glucose? both date back to 1913. The aim of diagnosis and management of diabetic patients is twofold-to help patients avoid acute complications such as hypoglycaemia and ketoacidosis and to prevent the long-term complications of nephropathy, retinopathy, and atherosclerosis. The commonest cause of blindness in the young and middle-aged in the developed countries is diabetes mellitus, and premature death due to atherosclerosis or renal failure is much more frequent in diabetic than non-diabetic subjects. Although there is still no conclusive evidence as to the pathogenesis of these complications, it is likely that chronic hyperglycaemia plays a part.v' In practice the assessment of chronic hyperglycaemia by blood glucose measurements is virtually impossible because of the frequency with which measurements would be required, and because of the lability of blood glucose once appropriate insulin responses have been lost. The measurement of the non-enzymatically glycated derivatives of haemoglobin and plasma proteins has provided a reliable index of longterm blood glucose control of proven value to the management of patients. Despite serious consideration, however, their measurement has not been shown to be reliable in the diagnosis of diabetes mellitus.

Office Glucose Analysis

The advent of dry chemistry techniques has made inexpensive glucose testing equipment available to physicians and their patients. The ability to measure blood glucose concentration quickly, in almost any setting, has eliminated urinary glucose monitoring as the parameter of choice for managing diabetic patients. Blood glucose monitoring has allowed improved control of diabetic patients who avail themselves of one of the techniques. The physician choosing to offer blood glucose testing in the office laboratory has a variety of test equipment from which to choose. Most physicians will want to own and operate an inexpensive, dedicated glucose reflectometer to test glucose samples in the office and to use in patient education. Machines used by both patients and physicians are about the same price. They are easy to learn to use. Office personnel must be trained to perform the procedure, teach it to patients, maintain the machine, and keep adequate quality control records.

The effect of hyperinsulinaemia on glucose utilization and oxidation and on oxygen consumption in the fetal lamb.

In order to measure the effect of hyperinsulinaemia on fetal glucose metabolism and oxygen consumption, we applied the glucose-clamp technique to experiments in fifteen late-gestation, unstressed, chronically catheterized fetal lambs. In a control period, and immediately thereafter following 2 h of hyperinsulinaemia, we measured fetal glucose utilization and oxidation rates (radioactive tracer methodology) and net fetal uptake rates of exogenous glucose and oxygen uptake rates (Fick principle). During the period of hyperinsulinaemia, fetal glucose concentration was maintained at the average control period value by a variable rate of glucose infusion into the fetus in response to serial 10 min measurements of fetal arterial blood glucose concentration. Hyperinsulinaemia in the fetus (12.12 +/- 1.92 ng X ml-1 (mean +/- S.E.M.) arterial plasma) resulted in a 13% increase in net fetal oxygen uptake rate (0.310 +/- 0.011 to 0.349 +/- 0.012 mmol. min-1 X kg-1), a 106% increase of fetal glucose uptake rate (4.54 +/- 0.43 to 9.35 +/- 0.50 mg X min-1 X kg-1) and an 83% increase of fetal glucose utilization rate (4.94 +/- 0.43 to 9.05 +/- 0.83 mg X min-1 X kg-1). Fetal glucose uptake and utilization rates were not different from each other during the control and the hyperinsulinaemia periods. The fraction of glucose that was oxidized (0.58 +/- 0.05, control; 0.54 +/- 0.05, hyperinsulinaemia) did not change significantly; thus the glucose oxidation rate, the rate of entry of glucose into non-oxidative pathways, and the amount of oxygen used for glucose oxidation all increased in proportion to glucose utilization. These results suggest that insulin promotes the entry of glucose into fetal tissues, thereby increasing fetal glucose utilization and oxidation rates and substituting glucose oxidation for that of other substrates. The insulin-enhanced glucose utilization rate also increases slightly fetal metabolic rate.

Development and testing of a simple algorithm for a glucose clamp.

The glucose clamp technique is widely used in clinical research studies to maintain a constant blood glucose (BG) level during metabolic perturbation. An algorithm is used to set the rate of an intravenous glucose infusion according to measured BG concentrations. Currently used clamp algorithms are unnecessarily complex. This paper describes the development and use of a new algorithm which is simpler to implement. The algorithm employs proportional and differential feedback control. Discrete BG sampling with a sampling period of 5 min is used. Computer simulation with a two-compartment model of glucose dynamics was used to refine the algorithm. A Monte Carlo approach was adopted to examine the effects of random variations in measured BG concentrations and the elapsed time between blood sampling and adjustment of the glucose infusion rate. A coefficient of variation in BG concentration of less than 4 per cent was predicted for a euglycemic clamp. This was confirmed when the algorithm was applied in clinical research studies. This degree of BG control compares well with other published algorithms.