More on fructosamine assay as index to glycated protein.
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Blood Proteins↗
Biomedical subjects
R N Johnson
Publications and source records attributed to R N Johnson.
Serum fructosamine concentration as measure of blood glucose control in type I (insulin dependent) diabetes mellitus.
Serum fructosamine activity was studied in 42 patients with type I (insulin dependent) diabetes mellitus and 30 non-diabetic volunteers as an index of blood glucose control. There was a significant correlation both between fructosamine and glycosylated haemoglobin values (r = 0.82) and between fructosamine and the fasting C peptide concentration (r = -0.81). Test results in 14 of the diabetics reflected the mean plasma glucose concentration calculated from 25 serial estimations in a single 24 hour period (r = 0.75; p less than 0.01) but not the mean amplitude of glycaemic excursion (r = 0.23; p greater than 0.05). Fructosamine concentrations measured in these multiple blood specimens did not change significantly throughout the day (mean coefficient of variation 4.1%) despite wide variability of the respective plasma glucose concentrations (mean coefficient of variation 36.2%). It is concluded that a single random serum sample analysed for fructosamine concentration provides a simple and reliable assessment of glucose homoeostasis in patients with type I diabetes mellitus.
Adolescent↗
Subconjunctival emphysema associated with mechanical ventilation.
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Adult↗
A nonlinear least-squares method for determining cerebrospinal fluid formation and absorption kinetics in pseudotumor cerebri.
Data from 14 patients with benign intracranial hypertension (pseudotumor cerebri) have been analyzed using a nonlinear least-squares regression model which was developed and programmed from in-hospital microcomputer use. The method of analysis permits rapid estimation of cerebrospinal fluid (CSF) formation and absorption rates as functions of pressure in individual patients using data from constant-rate infusion manometrics. The analysis predicts that prednisone therapy in pseudotumor cerebri reduces resting CSF pressure by increasing CSF absorption at all intracranial pressures studied, and decreasing CSF formation at high pressures. This result is in accordance with evidence suggesting that impaired CSF absorption plays a major role in the pathogenesis of increased intracranial pressure in pseudotumor cerebri.
Absorption↗
Epidemiological observations on cutaneous leishmaniasis in the Dominican Republic.
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Animals↗
Use of protein-based standards in automated colorimetric determinations of fructosamine in serum.
We have developed an automated colorimetric assay for glycated serum proteins (or fructosamines), measuring the reducing activity of serum in alkaline solution (pH 10.35) at 37 degrees C. The calibrants were prepared from a synthetic fructosamine (1-deoxy-1-morpholinofructose), although secondary standards of glycated bovine albumin were more robust in routine application. Interference was appreciable only with icteric specimens (bilirubin greater than 60 mumol/L), and between-batch imprecision (CV) was less than 2%. The range of fructosamine concentrations measured in 502 healthy (nondiabetic) blood donors was 1.87-2.87 mmol/L. There were no significant (p greater than 0.05) age- or sex-related differences in this population sample. Fructosamine accurately reflected blood glucose control as evidenced by the significant correlation with glucose concentrations in fasting plasma (r = 0.82, p less than 0.001) and with glycated hemoglobin (HbA1c) (r = 0.87, p less than 0.01) in 115 patients with type 2 (non-insulin-dependent) diabetes mellitus. The test is simple and rapid to perform (75 samples per hour) and provides an alternative to HbA1c determinations for monitoring blood glucose control and assessing the effects of changes in diabetes management.
Adolescent↗
Determination of degradation products and impurities of amoxicillin capsules using ternary gradient elution high-performance liquid chromatography.
A specific high-performance liquid chromatography method has been developed for the determination of amoxicillin penicilloic acids (PA), p-hydroxyphenylglycine (p-HPG), 6-aminopenicillanic acid (6-APA) and unidentified materials in amoxicillin capsules. The accuracy of the measurements was demonstrated by the standard addition technique on actual capsule samples. Within-day and between-day precision studies gave coefficients of variation of 3.15 and 1.70% for PA, 4.75 and 3.81% for p-HPG, and 5.59 and 32.23% for 6-APA, respectively. Typical calibration and expanded linearity of response curves for these components show no curvature over the range of interest. The detection limits for PA, p-HPG and 6-APA are 0.7, 0.2 and 0.6 micrograms/ml of sample extract and are considered adequate for the intended use of the method. These levels correspond to 0.35, 0.10, 0.30 mg per 500-mg Amoxil capsule, respectively.
Amoxicillin↗
Serum fructosamine concentrations in patients with type II (non-insulin-dependent) diabetes mellitus during changes in management.
The serum fructosamine concentration was examined as a new means to monitor metabolic control in non-insulin-dependent diabetes during changes in management. Weekly fructosamine estimations were compared with glycosylated haemoglobin (HbA1c), 24 hour urinary glucose, and fasting plasma glucose concentrations in a 17 week study entailing withdrawal and reinstitution of oral treatment. The serum fructosamine concentration was more sensitive than the other measurements in detecting a deterioration in diabetic control after stopping oral hypoglycaemic drugs. The response to reinstitution of treatment was not significant in the first three weeks (p = 0.266), despite a highly significant reduction in fasting plasma glucose (p = 0.001) and 24 hour urinary glucose concentrations (p = 0.012). Compared with HbA1c, concentrations of fructosamine appeared more useful in monitoring short term (three to six weeks) changes after alterations in management of diabetes. Additional advantages were lower cost and technical simplicity of measurement.
Adult↗
Clinical usefulness of estimation of serum fructosamine concentration as a screening test for diabetes mellitus.
Fructosamine, a putative measure of serum glycosylated proteins, was measured in 74 subjects referred for oral glucose tolerance tests. A normal range (mean (2 SD] of 1.6 (0.4) mmol/l (40(10) mg/100 ml) derive from results obtained in 83 healthy non-diabetic volunteers permitted the detection of 15 out of 17 (88%) subjects with proved diabetes and yielded only five (9%) false positive diagnoses. Fructosamine concentrations correlated significantly (p less than 0.001) with fasting plasma glucose concentrations (r = 0.76) and glycosylated haemoglobin concentrations (r = 0.70). A longitudinal study suggested that fructosamine concentration was an index of intermediate term (one to three weeks) blood glucose control. Fructosamine concentration was not related to uraemia and did not depend on albumin or total protein concentrations, provided that serum albumin concentrations remained above 30 g/l. Estimation of fructosamine concentrations is a fully automated procedure and may provide a simple means of screening for diabetes mellitus.
Adolescent↗
Fructosamine: a new approach to the estimation of serum glycosylprotein. An index of diabetic control.
The development of a novel manual method designed to measure serum glycosylprotein as an index of diabetic control is described. The method relies on the ability of ketoamines (fructosamines) to act as reducing agents in alkaline solution. Conditions are described for a simple colorimetric procedure which permits assay of both a synthetic fructosamine and purified albumin while severely limiting the contribution of interfering substances. Applied to whole sera, the measurement is linear with volume of serum assayed. It allows clear discrimination of normal and diabetic populations (p less than 0.001), and is significantly correlated with fasting blood glucose concentration (r = 0.72) and with a thiobarbituric acid procedure for measuring glycosylprotein-derived hydroxymethylfurfural (r = 0.58). The method is rapid (at least 12 samples per hour) and demands only simple equipment.
Blood Glucose↗
High-performance liquid chromatographic determination of pralidoxime chloride and its major decomposition products in injectable solutions.
A high-performance liquid chromatographic (HPLC) method for the simultaneous determination of pralidoxime chloride (I) and its major decomposition products in an injectable formulation is described. I and its decomposition products were detected and quantitated by their UV absorbances at 270 nm, after being separated from related compounds and formulation excipients on a reverse-phase C-18 column using a mobile phase consisting of 52% acetonitrile and 48% of an aqueous solution containing 0.005 M phosphoric acid and 0.001 M tetraethylammonium chloride. The major decomposition products of I in the injectable formulation were identified by their retention times and stop-flow spectroscopy as 2-carboxy-N-methylpyridinium chloride, N-methyl-2-pyridone, 2-carbamoyl-N-methylpyridinium chloride, 2-hydroxymethyl-N-methylpyridinium chloride, and 2-cyano-N-methylpyridinium chloride. A substance of unknown identity also was detected in degraded solutions of I. Stop-flow spectroscopy, employing the spectral discrimination technique, showed that the method is specific for I. Recovery of I from a spiked placebo formulation averaged 99.9%. The accuracy of the method was also demonstrated for the decomposition products over a range of concentrations representing 1-50% decomposition. Replicate determinations of I in degraded solutions gave coefficients of variation of 1.0 and 1.5%, while the precision of determining the decomposition products range from 1.3 to 6.5%. Regression lines with correlation coefficients greater than 0.9999 were obtained for I and its decomposition products, and solutions of these compounds were shown to be stable in the mobile phase for several days. Results for I by the HPLC and USP procedures are compared.
Chromatography, High Pressure Liquid↗
Assessment of cerebrospinal fluid compliance and outflow resistance: analysis of steady-state response to sinusoidal input.
Cerebrospinal fluid dynamics have been studied in the past by analyses of responses to bolus, constant rate or constant pressure inputs. In this study, we present a method for analyzing CSF pressure responses to sinusoidal variation in the infusion rate. Infusion of artificial CSF into the cisterna magna of adult rats was modulated sinusoidally between 0 and 30 microliter/min. The resulting sinusoidal variation in intracranial pressure was recorded on a strip chart recorder simultaneously with the infusion rate signal. The two signals were analyzed for peak-to-peak variation, mean value, and phase shift for input frequencies in the range of 0.0015 to 0.01 HZ (0.00942 to 0.0628 radians/sec). The system was analyzed at each mean infusion rate as a parallel resistance and compliance with a first order linear model. The resistance to CSF outflow was determined as the change in mean steady-state pressure divided by the change in mean infusion rate. The compliance was then obtained from the frequency dependent phase shift between input and output using the first-order linear model. Resistance values were lower for higher average infusion rates consistent with our previous work, while compliance remained constant over the measured pressure range.
Animals↗
Serum myoglobin concentration as an index of myocardial damage after cardiac surgery.
We assessed serum myoglobin concentration as an index of myocardial damage after cardiothoracic surgery in a dog model and man. Experimentally, we compared 12 dogs subject to left thoracotomy either with or without coronary artery ligation to cause an infarct. Serial blood sampling for 24 hours after surgery showed that the times taken for the myoglobin peak concentrations to appear distinguished the two groups without overlap. These times were 2.4 +/- 0.4 hours after surgery without ligation compared with 9.8 +/- 0.8 hours in the ligated group (P less than 0.001). Clinically, serial sampling was performed over 48 hours in 20 patients having undergone cardiac surgery involving cardiopulmonary bypass. A further 80 patients were investigated for 12 hours. Myoglobin was compared with the activities of creatine kinase, 2-hydroxybutyrate dehydrogenase and glutamate-oxaloacetate transaminase in relation to electrocardiographic criteria of myocardial damage. A myoglobin peak greater than 800 micrograms/1 appearing later than 6 hours after starting bypass was found in those patients suffering myocardial damage. The appearance times and activities of the enzymes tested were widely scattered and difficult to interpret. We conclude that blood samples taken at approximately 3 and 6 hours after starting bypass should suffice to characterise both peak myoglobin and its time of appearance which together form a sensitive index of myocardial damage. However, this conclusion is limited by the low incidence of myocardial damage (3%) in this group of patients.
Animals↗
Mycoplasma pneumonia complicated by bronchiectasis.
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Adult↗
Effect of hyperthermia on a thalamocortical system in the kitten and the cat: a preliminary study.
Hyperthermia produces many changes in the ongoing electrical activity of the brain. One of the responses which fever can induce is seizure activity. The thalamocortical augmenting response, a complex neurophysiological response, has been related to seizure discharges. The changes in that complex neurophysiological response induced by experimental hyperthermia were assessed in adult cats and in kittens, using analytical methodology first developed in adult cats. The effect of two anticonvulsants (phenytoin and valproate) on those hyperthermia-induced changes in the thalamocortical augmenting response were compared in kittens. The differences between the effects of the two anticonvulsants on the thalamocortical augmenting response can be related to the reported clinical differences between the two anticonvulsants in patients with febrile seizures.
Animals↗
Severity of canine myocardial infarcts in relation to indices of oxygen demand: preservation of myocardial creatine kinase activity by vagal stimulation and propranolol.
The left anterior descending coronary artery was ligated in 58 open-chest anaesthetised dogs; 23 were controls, 15 were given intravenous propranolol 1 mg . kg-1 before and at 6 h intervals after coronary ligation, nine had bilateral cervical vagal nerve stimulation (VS) before and for 4 to 6 h after coronary ligation, and 11 had both VS and propranolol. None of the 20 dogs undergoing VS developed ventricular fibrillation within the first hour after coronary ligation compared to nine of the remaining 38 (P less than 0.05). Compared to controls, myocardial creatine kinase (CK) depletion in the epicardial layer of the infarct centre measured 24 h after coronary ligation was significantly less in the groups treated separately with vagal nerve stimulation and propranolol. Myocardial blood flow (MBF) measured at 15 min after coronary ligation was reduced to the normal myocardium by the interventions, but was unchanged at the infarct centre. Severely ischaemic myocardium (MBF less than or equal to 20% of normal) was better protected by the interventions than was moderately ischaemic myocardium. At 15 min after coronary ligation, the heart rate--blood pressure product (RPP) was reduced compared with controls by propranolol (18% reduction, P less than 0.05), reduced more by vagal stimulation (by 37%, P less than 0.001) and still more by vagal stimulation with propranolol (by 43%, P less than 0.001). Preservation of CK in myocardium with MBF less than or equal to 20% of normal was improved by VS and propranolol given separately roughly in proportion to reduction in RPP, but further reduction in RPP by VS and propranolol together did not improve CK levels further. We conclude that there may be an optimum level of indices of oxygen demand for preservation of very ischaemic myocardium in experimental infarction.
Animals↗
Development of the thalamocortical augmenting response in the kitten.
Study of the developing central nervous system can lead to better understanding of the mature central nervous system. The thalamocortical augmenting response is a complex neurophysiological response considered to be related to the occurrence of some forms of epileptic activity. Using a paradigm previously developed in adult cats, we assessed the development of the thalamocortical augmenting response in kittens and found that the relative proportion of thalamocortical activity occurring at high frequencies of thalamic stimulation increased with increasing age. Anticonvulsants effective against petit mal seizures also increase the relative proportion of thalamocortical activity following high frequencies of thalamic stimulation. Developmental changes in the thalamocortical augmenting response can be related to the age-dependent decreases in the prevalence of petit mal seizures.
Animals↗
Nonaqueous reverse phase liquid chromatographic determination of vitamin D2 in multivitamin tablets, using vitamin D3 as internal standard.
The technique of nonaqueous reverse phase chromatography has been successfully applied to the separation of lipophilic vitamins D2 and D3. Separation is achieved with a Zorbax-ODS column and a mobile phase of 10% methanol in acetonitrile. A predetermined amount of vitamin D3 internal standard is added to a portion of a powered tablet sample, which is then extracted and partitioned with a mixture of dimethyl sulfoxide, water, methanol, and hexane. A portion of the hexane extract is concentrated, and purified by passing it through a disposable silica cartridge to remove interfering materials. The method should also be applicable to formulations containing vitamin D3 where vitamin D2 can then be used as the internal standard. A system suitability test is included in the method.
Cholecalciferol↗