A rapid and sensitive catalytic method for determination of iron in blood serum

A simple, rapid and sensitive method is proposed for the determination of iron in blood serum. Because of the high sensitivity of the method (0.001 μg/ml) a serum sample of only 0.05 ml is used in the analysis. The procedure is reduced to a usual photometric measurement. The determination is carried out without previous deproteinisation. A single determination takes about 45 min but in case of serial analysis 10 samples are analysed per hour. The coefficient of variation is in the range 1.8–4.8%, depending on the serum iron content. The method is compared with the bathophenantroline, nitroso-R-salt and flame atomic absorption methods. The best correlation is found for the data of the catalytic and the bathophenantroline methods, the reasons for this being discussed in the paper.     

A simple colorimetric method for ascorbic acid determination in blood plasma

The paper describes a simple method for determination of ascorbic acid using acid phosphotungstate. The reagent has been found to be specific and sensitive to ascorbic acid and can be used for ascorbic acid determination in plasma with good reproducibility.     

Highly sensitive determination of the dehydrogenase activity in human peripheral blood lymphocytes using a bioluminescent method

A highly sensitive rapid method for measuring human blood lymphocyte NADP-dependent dehydrogenase activities has been developed, based on biofluorescent assay of NADPH in a sample with the use of fluorescent bacterial system. The enzyme activity in a suspension of destroyed lymphocytes is determined from NADPH production after addition of appropriate substrates and cofactors. The technique takes little initial material (at least 1000 lymphocytes per sample) and permits 100 measurements in 3 hours.     

A simple and informative method of diagnosing myocardial infarct, based on a determination of blood density

An increased density of blood revealed in myocardial infarction patients served the basis for a simple and highly informative method developed by the authors to early diagnose myocardial infarction when other methods are not sensitive. The high density of blood is registered upon placing a drop of blood into flakes with sodium chloride solution of different concentration.     

Effect of inhaled histamine on occlusion pressure and breathing pattern in asthmatic patients

In animals, histamine inhalation is known to increase either respiratory frequency or respiratory drive by stimulation of airway vagal sensitive endings. However, it is not well known whether these changes are concomitant in man. In order to elucidate this point, we carried out the present investigation in thirty-five asthmatic patients who underwent bronchial provocation test by progressively doubling the dose of inhaled histamine. Bronchial reactivity to histamine allowed two populations of patients to be defined: group I with moderate and group II with mild, increased reactivity. In the twenty-three group I patients, neuromuscular inspiratory drive, assessed by mouth occlusion pressure (P0.1), was found to be significantly increased while no significant changes in breathing pattern were noted. In the twelve group II patients histamine did not modify P0.1 or breathing pattern. However, we were able to separate in group I a sub-group of ten patients, as with atopic asthma, in which histamine-induced increase in P0.1 was paralleled by rapid and shallow breathing (RSB). Changes in P0.1 and breathing pattern did not depend on baseline airway calibre. In group I, after bronchoconstriction had been reversed by inhaling a beta 2-agonist bronchodilator agent (fenoterol), P0.1 decreased significantly and RSB was found to be reversed; however, these changes were not interrelated. We concluded that: in asthmatics, histamine-induced increase in P0.1 is not necessarily paralleled by, nor related with, change in breathing pattern and in atopics a 'sensitization' of vagal receptors could account for the concomitance of enhanced P0.1 with RSB.     

Quantitative determination of protein in the urine by a sensitive nephelometric method

The nephelometric method of Reiber ((1980) J. Clin. Chem. Clin. Biochem. 18, 123-127) for quantitation of proteins in cerebrospinal fluid was modified for urine. Protein concentrations between 50 and 500 mg/l (method A) or between 5 and 70 mg/l (method B) can be measured. Values greater than 150 mg/l correlate well with the Biuret- and the Coomassie method (r = 0.9804 and r = 0.9925, respectively). For lower concentrations, only albumin, determined by an enzyme-immuno-assay, gave a good correlation (r = 0.9342). The following pharmaceuticals did not influence the results: penicillin, gentamycin sulphate, dihydralazine sulphate, amoxicillin and furosemide. A reference range of 7-56 mg/24 h was established (n = 52, 90% confidence interval).     

A simple and reliable method for determination of skin perfusion pressure in patients with severe occlusive arterial disease

Summary. In an attempt to simplify the pre-operative assessment of amputation level in patients with severe occlusive arterial disease of the legs the skin perfusion pressure (SPP_i) on calf and/or thigh was determined photo-electrically in 38 patients, aged 41–85 years and compared to the pressure values (SPP_i) determined by the widely used but cumbersome isotope washout technique. SPP_i was determined as the minimal external counter pressure (applied by a blood pressure cuff) sufficient to stop the washout from an intracutaneous depot of Na¹³¹I^- mixed with histamine. SPP_P was determined as the minimal external counter pressure required to prevent skin reddening after blanching of the skin. The systolic blood pressure, determined indirectly by strain gauge technique at the same level of the leg, was used for reading the SPP_P as that counter pressure at which the photo-electric tracing moves away from a straight line placed on the tracing through the counter pressure corresponding to the systolic blood pressure. In the studied range 18–88 mmHg there was no significant difference between SPP_P and SPP_i. The total day-to-day variation of SPP_P, determined from ten double determinations in eight patients was 6-6 mmHg (range of SPP_P: 23–80 mmHg). The present results indicate that assessment of amputation level from SPPp using the standardized reading should offer a reliable alternative to the isotope washout method. The photo-electric technique is simple and fast, and gives only negligible discomfort to the patient.     

A sensitive micromethod for the determination of methemoglobin in blood

A modification of the Evelyn and Malloy method for the determination of methemoglobin in blood is presented. A higher precision of the assay is achieved, and sample stability is increased up to 24 h, thus making the procedure suitable for field surveys aimed at detecting slightly raised methemoglobin levels.     

Rapid and sensitive method for erythropoietin determination in serum.

An enzyme-linked immunosorbent assay (ELISA) method for erythropoietin determination has been established by using two kinds of monoclonal antibodies with specific affinities to erythropoietin. Besides being rapid (2.5 h) and sensitive (detection limit 0.3 int. unit/L), the present method gives accurate results and is easy to perform. The method may be clinically applicable for discriminative diagnosis of polycythemia and analyses of various anemic conditions.     

A simple method for preparing neocyte-enriched leukocyte-poor blood for transfusion-dependent patients

Recent treatment for patients with thalassemia and chronic anemia involves transfusion of young red cells (YRBCs) or "neocytes." We developed a technique enabling YRBCs to be separated based on their buoyant density in autologous plasma during centrifugation. Following this procedure, measurement of pyruvate kinase (PK), an age-dependent red cell enzyme, showed neocyte enrichment in the top one-third of the RBC layer corresponding to a mean of 47.5 percent of the total PK present in the unfractionated unit. To provide a neocyte transfusion preparation with an acceptable hemoglobin content, the top one-third fraction from each of three bags of blood was pooled. Leukocytes were removed from this "neocyte unit" by an initial sedimentation with 6 percent hydroxyethyl starch (HES) followed by filtration through a filter (IG 500, Imugard). This process resulted in removal of 99.3 +/- 0.5 percent (mean +/- SD) of the leukocytes with a mean RBC recovery of 89.5 +/- 5.5 percent and a final hemoglobin content of 53.4 +/- 2.3 g. Tests for plasma-free hemoglobin and HES in the supernatant of the final transfusion product gave acceptable mean values of 28 mg per dl and 3.0 mg per ml. Autologous mean RBC survival of Cr51-labeled YRBC fractions was 41.8 +/- 2.9 days (n = 5). This technique yields neocyte enrichment superior to that achieved using a cell processor (model 2991, IBM) and has the added advantage of being less costly to prepare ($45.00 [1984] U.S. per YRBC unit as compared to an estimated $135.00 [1984] U.S., IBM) and more economical in terms of blood use.