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Biomedical subjects

B Karlberg

Publications and source records attributed to B Karlberg.

At least 19 recordsLinked to original sources
PubMed1999

Direct determination of small cations in proteinaceous samples using a flow injection-capillary electrophoresis system.

A method is described for the direct determination of small inorganic cations in samples containing large amounts of proteins, such as milk or blood plasma. The method is based on electrokinetic injection in a flow injection analysis-capillary electrophoresis (CE) system. The selected CE-electrolyte, containing 5 mM 4-aminopyridine and 7 microM cetyltrimethylammonium bromide at pH 4.5, prevents detrimental protein adsorption on the capillary walls. Therefore, no sample pretreatment, except for dilution, is required. Up to 30 repeated injections in one electrophoretic run can be performed, yielding RSD values of the migration time of less than 1 and 2.5% (n=30) for milk and blood plasma samples, respectively.

Blood Proteins↗
PubMed1998

Determination of malondialdehyde in rat brain by capillary zone electrophoresis.

A method for determination of malondialdehyde with capillary electrophoresis using UV detection at 267 nm has been developed. The buffer system consisted of 10 mM borax and 0.5 mM CTAB at pH 9.3. Malondialdehyde migrated as the first peak in the electropherogram at 2.6 min. Limit of detection was 1.2 microM corresponding to 7.8 pg. Malondialdehyde was determined before and after stimulating lipid peroxidation with the addition of ferrous ammonium sulphate to homogenates of rat brain tissue. Proteins were precipitated by boiling and removed from the brain homogenates with centrifugation. No further pretreatment was made before injecting the homogenates on the CE system. Non-precipitated homogenates could also be analyzed, but this required washing of the capillary with 0.1 M NaOH before introduction of the next sample.

Animals↗
PubMed1997

Determination of heterocyclic aromatic amines by micellar electrokinetic chromatography with amperometric detection.

A micellar electrokinetic chromatographic system (MEKC) with amperometric detection was utilised to separate eight heterocyclic aromatic amines (HAA), which have been shown to be produced during heat processing of protein rich food. The electrolyte consisted of 15 mM borax adjusted to pH 9.1 with phosphoric acid and 5 mM cetyltrimethylammonium bromide (CTAB). Baseline separation was obtained within 7 min. Detection limits were at the level of 10 micrograms/l (3 fg), using a carbon fibre disc electrode at a potential of 0.6 V vs. Ag/AgCl. The method was applied to the quantitative estimation of mutagenic amines in a pan residue extract.

Amines↗
PubMed1992

Calcium antagonism in essential hypertension: effect on renal haemodynamics and microalbuminuria.

Sixteen middle-aged men with primary hypertension were treated with the calcium antagonist isradipine over a 9-week period in a randomized, placebo-controlled, double-blind cross-over manner. At the end of the intervention period the urinary albumin excretion rate, systemic and renal haemodynamics, haemorheological properties of blood and plasma concentrations of atrial natriuretic peptide, noradrenaline and peripheral renin activity were determined. Treatment with isradipine resulted in a substantial reduction in blood pressure due to a reduction in peripheral resistance. The mean albumin excretion rate was not influenced by the isradipine treatment. In a multivariate analysis, changes in the urinary albumin excretion rate were only related to changes in blood pressure.

Albuminuria↗
PubMed1991

Reflexogenic neuronal and humoral responses to selective stimulation of low-pressure cardiopulmonary receptors in man.

This study was conducted to determine the relative importance of efferent muscle sympathetic nerve activity (MSA), vasopressin (ADH) and atrial natriuretic peptide (ANP) in the short-term neurohumoral response to moderate changes in low-pressure cardiopulmonary receptor activity. The low-pressure receptors were stimulated and unloaded, respectively, by autotransfusion of blood (450 ml) and the application of lower body negative pressure (LBNP, -20 mmHg), and in 11 healthy men we measured MSA in the left peroneal nerve, indirect blood pressure, ECG, central venous pressure (CVP) and venous plasma concentrations of ANP and ADH (radioimmunoassay). Total MSA rose by 30% during LBNP and decreased during a rapid autotransfusion of blood, and the changes in MSA were significantly related to changes in CVP. The plasma concentrations of ADH and ANP were not significantly affected by either procedure. It is suggested that during moderate short-term changes in venous return, MSA responded more rapidly and/or at a lower threshold than the ADH and ANP systems.

Adult↗
PubMed1988

An improved flow injection method for determination of lactate during exercise studies.

An improved enzymatic fluorometric method for automated analysis of lactate in perchloric acid extracts of capillary blood with flow injection (FIA) is described. The concentrations of lactate can be measured in as little as 20 microliter capillary blood from an exercising person. Within-day and between-day coefficients of variation are about 2%. The recovery of lactate from whole blood is 101%. Lactate is stable in perchloric acid extracts for at least 15 days at room temperature, and at +4 degrees C at least 30 days. Blank fluorescence in perchloric acid extracts of blood is low with the improved method. The FIA system is simple to use, inexpensive to operate, and is recommended for any laboratory with a high throughput of samples.

Autoanalysis↗
PubMed1984

Increase in plasma free fatty acids and natriuresis by xanthines may reflect adenosine antagonism.

The hypothesis has been examined that adenosine is involved in the diuretic and free fatty acid (FFA) - releasing action of xanthines. The effects of theophylline (T), a potent adenosine antagonist, were compared with those of enprofylline (3-propyl xanthine, E), which exerts negligible antagonism of adenosine. Eight healthy male volunteers were given E 1.5 mg/kg, T 5.0 mg/kg or placebo 0.9% saline (P) intravenously in a double-blind, randomized, cross-over investigation. Blood samples were analyzed for E, T, catecholamines (CA: adrenaline, noradrenaline and dopamine), FFA, renin, glucose, glucagon and insulin, and urine was collected at 2-h intervals. T (plasma concentration 53 +/- 8 mumol/l) but not E (11 +/- 2 mumol/l) caused an increase in FFA from 0.42 to 0.86 mmol/l after 90 min. Without affecting the urinary excretion of potassium, T doubled natriuresis and the urine volume as compared to E and P. Neither T nor E had any effect on plasma CA, or on any other of the metabolic parameters studied. E, but not T, produced a small but statistically significant decrease in diastolic blood pressure (5 mmHg) and an increase in heart rate (3 beats/min). It is suggested that the difference between E and T in terms of stimulation of FFA-release and natriuresis may be related to their different ability to antagonize adenosine.

Adenosine↗
PubMed1984

A long-term follow-up of patients with essential hypertension treated with captopril.

Seventy-four patients from four short-term studies of captopril in mild-moderate essential hypertension continued in a cooperative long-term efficacy and tolerance program. The duration of observation is 2- greater than 4 years, the total treatment time being 2434 months. No development of resistance to therapy was observed. The total daily dose of captopril has been gradually decreased and in 20 patients changed from t.i.d. to b.i.d. regime. The drug has been well tolerated and only few and mild side-effects have been observed after the initial titration period. The drop-outs (n = 19) were mostly due to non-medical causes (n = 14). Except for one case of proteinuria, no laboratory abnormalities were detected and there were no signs of long-term toxicity.

Adult↗
PubMed1983

Semi-automatic blood lactate assay: experiences from an exercise laboratory.

A semi-automatic system based on flow injection analysis (FIA) for the transportation of small sample aliquots has been combined with fluorometric, enzymatic methods for blood lactate determination and has been described earlier. In the present study duplicate blood samples were obtained from exercising subjects to enable a comparison of lactate concentrations between neutralized and non-neutralized samples. Duplicate samples were also obtained to enable FIA lactate values to be compared to those obtained with a manual enzymatic method, and with a colorimetric method. No significant change was observed if the sample was not neutralized, enabling a more rapid sample turnover. The FIA method was reliable, with a coefficient of variation of 4.9% between duplicate blood samples. FIA lactate values were valid when compared to two other manual assays. FIA has been shown to be a rapid (60 samples x h-1) means of accurately determining blood lactate concentrations with 25 microliter blood samples and is of particular relevance to the exercise laboratory.

Automation↗
PubMed1982

Captopril and atenolol combined with hydrochlorothiazide in essential hypertension.

1 Fifty-seven patients with mild or moderate essential hypertension, mean age 50 (range 31-69) were randomised to treatment with either captopril or atenolol. Twenty-six patients in each group completed the study. 2 Captopril (25-50 mg three times daily) and atenolol (50-100 mg once daily) caused a highly significant fall in blood pressure both supine and standing. 3 When hydrochlorothiazide (25-50 mg once daily) was added a further fall in blood pressure was observed in both groups. 4 Captopril as single drug caused no significant change in heart rate, while atenolol significantly reduced heart rate both supine and standing. 5 Two patients were excluded from the captopril group, one because of a reversible loss of taste and the other because of dizziness. Three patients were excluded from the atenolol group, two because of bradyarrhythmias and one because of inadequate blood pressure response. 6 Both captopril and atenolol were found to be effective antihypertensive agents, suitable for the treatment of essential hypertension.

Adult↗
PubMed1976

Automated in vitro dissolution rate analysis of potassium in plastic matrix slow release tablets.

A fully automated system for dissolution rate analysis of potassium in slow release tablets is described. Aliquots are removed after 1, 2, and 4 hr from six samples, and potassium is analyzed in a flame photometer at 768 nm. A complete study of six samples takes 5.5 hr. The system may be run overnight. During the time intervals between the removal of aliquots, the system can be used for the determination of the total assay of tablets.

Delayed-Action Preparations↗