Biomedical subjects
B Danielsson
Publications and source records attributed to B Danielsson.
Felodipine in the treatment of patients with severe hypertension and impaired renal function.
Twenty-three patients with severe hypertension and impaired renal function were included in an open study of the efficacy and tolerance of felodipine treatment over 6 months. All patients were previously treated with a diuretic, a beta blocker, and a vasodilator, and eight of them also received an ACE inhibitor. At the start of felodipine treatment the previously used vasodilator was withdrawn. In nine patients the concomitant antihypertensive treatment was reduced during the study. The glomerular filtration rate (GFR), as 51Cr EDTA clearance, was determined before and at the end of the study. The blood pressure (BP) and heart rate (HR) were recorded at all clinical visits in the morning 12 hours after the evening dose of felodipine and 2 hours after the morning dose. Plasma concentrations of felodipine were measured at every visit before the morning dose and 2 hours after dose. The BP was reduced after felodipine was substituted for the previously used vasodilator. A significant additional anti-hypertensive effect was recorded 2 hours after the dose and amounted to -37 +/- 22/-15 +/- 12 mmHg (p = 0.0001/p = 0.0002) at 6 months. The effect measured 12 hours after the dose was less pronounced and was -11 +/- 28/-6 +/- 10 mmHg (p = 0.15/p = 0.03). Mean GFR was unchanged during the study, 38 +/- 19 versus 38 +/- 19 ml/min (n = 16). There was a sixfold interindividual variation in the trough plasma concentrations at steady state at the same drug dosage. Higher plasma concentrations seemed to be required to achieve the same antihypertensive effects as in patients with less severe hypertension and normal renal function.(ABSTRACT TRUNCATED AT 250 WORDS)
Application of the enzyme thermistor to the direct estimation of intrinsic kinetics using the saccharose-immobilized invertase system.
The possibility of using the enzyme thermistor (ET) for the direct determination of kinetic parameters (Km, Ki, Vm) of immobilized enzyme (IME) was evaluated using different preparations of invertase conjugated to bead celluloses. Two different ET columns packed with IME were operated in the mode of a differential enzyme reactor (short length, low substrate conversion). Kinetic parameters of the above IME reactor were computed by a nonlinear curve-fitting procedure. The obtained kinetic parameters were superverified by means of an independent differential reactor (DR) system. This system utilized an indirect postcolumn analytical method based on determination of glucose concentration in the stirred reservoir. Best agreement between the data acquired by direct (ET) and indirect (DR) methods was obtained if the ET column was operated at flow rates within the range of 1.0-1.5 ml min-1 using invertase-cellulose chlorotriazine conjugate. Influence of heat loss and flow nonideality is discussed. The proposed ET method offers a rapid, convenient, and general approach to determination of kinetic constants of IME preparations by omitting postcolumn analytical methods.
Calorimetric biosensors.
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Use of thermal biosensors for specific monitoring and control of bioprocesses.
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The excretion of carbonic anhydrase isozymes CA I and CA II in the urine of apparently healthy subjects and in patients with kidney disease.
Carbonic anhydrase isozymes CA I and CA II were assayed by a radio-immunosorbent technique in the plasma and urine of apparently healthy subjects and of patients with renal disease. The concentrations (mean +/- SD, n = 8) of CA I and CA II in the plasma of healthy subjects were 2.3 +/- 2.3 and 0.8 +/- 0.5 mg/l, respectively. The urinary excretion values were 3.8 +/- 2.0 and 3.5 +/- 1.9 micrograms/24 h, and the apparent renal clearances were 21 +/- 17 and 52 +/- 44 microliters/min, respectively, values that are similar to those of other low molecular weight proteins. CA I and CA II have mol. wt of 28,850 and 29,300, respectively, they are globular in shape and have a Stoke-Einstein radius of 25 A. They could, therefore, be expected to be filtered at the glomeruli and thereafter reabsorbed by the proximal tubules. CA II is also present in the cytoplasm of renal proximal and distal tubular cells. A study of the pattern of urinary excretion of CA I and CA II could permit detection of damage to renal tubular cells in two ways--either from defective reabsorption of filtered CA I and CA II by the proximal tubular cells, or from leakage of CA II from the proximal or distal tubules into the urine. Some patients with hypercalcuria and renal tubular acidosis showed increased excretion of these enzyme proteins and of beta 2-microglobulin (BMG) into the urine, but the prevalence was rather low (27%). Further studies of patients with more severely damaged kidneys are required.
[Vibroacoustic treatment of infants with colic has no effect].
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Hydrogen and ammonia gas-sensitive semiconductor structures in bioanalysis.
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Analytical applications with emphasis on biosensors. Introduction.
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Use of hydrogen- and ammonia-sensitive semiconductor structures in analytical biochemistry: enzyme transistors.
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Automated TELISA procedure for process monitoring.
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Subcellular localization of angiotensin-converting enzyme in the human alveolar macrophage.
The present investigation was performed in order to elucidate the subcellular localization of angiotensin-converting enzyme (ACE) in human alveolar macrophages. A pure population of alveolar macrophages was obtained by centrifugal elutriation of bronchoalveolar lavage (BAL) fluid from seven sarcoid patients. The cells were homogenized by sonication and the postnuclear supernatant was fractionated on a discontinuous sucrose gradient. Fractions of particulate material were collected and characterized by marker enzymes. The distribution pattern of ACE closely resembled that of NADPH-cytochrome-c-reductase and sialyltransferase, markers of the endoplasmic reticulum and the Golgi complex, respectively, indicating a common localization. This localization is compatible with synthesis taking place in the alveolar macrophage.
Automated thermometric enzyme immunoassay of human proinsulin produced by Escherichia coli.
We have determined and monitored the production and release of human proinsulin by genetically engineered Escherichia coli cells. Several M9 media samples were analyzed sequentially after centrifugation with the aid of a rapid automated flow-through thermometric enzyme-linked immunosorbent assay (TELISA) system. The response time was 7 min after sample injection and a single assay was complete after 13 min. Insulin concentrations in the range of 0.1-50 micrograms/ml could be determined. The TELISA method correlated well with conventional radioimmunoassay determinations. Standard curves were reproducible over a period of several days even when the immobilized antibody column was stored at 25 degrees C in the enzyme thermistor unit. Thus, immediate assay start up was possible.
Determination of creatinine by an ammonia-sensitive semiconductor structure and immobilized enzymes.
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Dicyclomine hydrochloride in infantile colic.
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Isolation of human alveolar macrophages and lymphocytes from bronchoalveolar lavage fluid by centrifugal elutriation.
Cell populations obtained by bronchoalveolar lavage (BAL) from humans showed varying proportions of lymphocytes and macrophages, about 5% and 94%, respectively, in healthy controls (n = 12), and about 24% and 75%, respectively, in patients with sarcoidosis (n = 13). The present study was carried out to examine centrifugal elutriation as a means to obtain from human BAL fluids highly purified populations of viable cells, required for further biochemical investigations. After centrifugation of BAL fluids at 400 g for 5 min, cells were resuspended in Hank-Tris solution, loaded into a Beckman elutriator rotor (rotor speed 2800 rpm) and elutriated with Hank-Tris in approximately 10 min. Cells were collected at flow rates of 20 ml/min (fraction I), 32 ml/min (fraction II) and, after stopping the rotor, 80 ml/min (fraction III). Fraction I contained mainly lymphocytes, about 54% and 74% in controls and sarcoidosis, respectively. Fraction III consisted almost solely of macrophages, while fraction II contained mixed populations. Total cell recovery was about 74% and 55% in controls and sarcoidosis, respectively. Half of the missing cells were lost during centrifugation, the rest during elutriation. Cell viability was 85-90% after the first centrifugation. Following elutriation, the viability was found unchanged in fraction III, but decreased to about 50% in fraction I of controls. The decrease may be due to the accumulation of dead cells with decreased density in this fraction. The results showed that centrifugal elutriation is a highly suitable technique for the isolation of macrophages from human BAL fluids. Enriched lymphocyte populations may be obtained from sarcoid BAL fluids.
Treatment of infantile colic with surface active substance (simethicone).
The effect of Simethicone on "colicky" (n = 27) infants was tested in a double-blind cross-over study. Three different parameters were used to measure the efficiency of the treatment: interviews, 24-hour records and behavioral observations. No effects of Simethicone on the symptoms of infantile colic could be demonstrated. However, 67% of the infants improved during the treatment, which could be ascribed to a high-grade placebo-effect.
The interaction of proteins and cells with affinity ligands covalently coupled to silicon surfaces as monitored by ellipsometry.
Two methods for the chemical binding of biomolecules to silicon surfaces are described. The first method utilizes an alkyl silane and a nucleophilic reagent to join the biomolecule to the silicon surface; the second method involves crosslinking with glutaraldehyde in order to couple the biomolecule and albumin molecules, which have first been physically adsorbed. The course of binding to the silicon surface has been followed with the aid of ellipsometry. This optical measuring technique estimates the thicknesses of, e.g., organic layers, by measuring the polarization properties of a light beam before and after reflection at surfaces. The method by which the binding of a biomolecule to its corresponding affinity ligand on silicon wafers can be followed with this technique is reported. The systems studied are concanavalin A-Saccharomyces cerevisiae cells, immunoglobulin G-Staphylococcus aureus cells, and an NAD-analog-lactate dehydrogenase. With ellipsometry it was possible to assess how the incubation time and the concentration of the cells and the biomolecules added influenced the results. It was found that an increasing time of incubation and higher concentration resulted in a more complete coverage of the silicon wafer surfaces.