Biomedical subjects
Publications and source records attributed to S Ohman.
Lithofibrin, a non-protein organic component of renal calculi was found in renal papillas with the aid of stereo microscopy under UV illumination. Scanning electron microscopy revealed fibers of which one had a clump containing calcium on the top. The findings support the theory of Randall, that the origin of primary renal calculi is to be found in the kidney, not in the urine.
We analysed calcium, magnesium, oxalate, citrate, urate and creatinine in urine and calculated risk factors in patients who had formed stones composed of calcium oxalate, and calcium phosphate, alone or as a mixture. Patients producing pure calcium oxalate stones (less than 0.1% phosphate) had a higher oxalate, and lower calcium excretion than stone-free subjects and patients forming other stone types. In contrast, patients producing calcium oxalate stones containing phosphate, even in trace amounts (greater than 0.1%) had no increase in oxalate excretion, but a higher calcium excretion than stone-free subjects. We could not correlate any computed variable (e.g. AP(CaOx) index) to stone composition. We conclude that pure CaOx stones may be the result of a high oxalate excretion, and that other calcium containing stones may have another and probably more complex aetiology, including primary precipitation of calcium phosphates.
Seven different formulae and agarose isoelectrofocusing (AIF) using immunolabelling for IgG were compared for their ability to discriminate between intrathecally produced IgG and transudated IgG in cerebrospinal fluid. All reference limits were set to a specificity of 97.5% (reference group, n = 211). The probability of a positive test (p+) was evaluated for 112 patients with multiple sclerosis (MS), 42 with meningitis, 114 with noninflammatory diseases affecting the central nervous system (CNS), 23 with Guillain-Barré syndrome, and 56 with various diseases not affecting the CNS. Agarose isoelectrofocusing had the best diagnostic sensitivity (93%) for MS, combined with a low p+ (0-19%) for other diseases. Among the formulae, the IgG extended index and Reiber's hyperbolic formula were equivalent, giving high (75-79%) diagnostic sensitivity for MS combined with low p+ (4-22%) for other diseases. All other formulae, although sensitive for MS, had a higher rate of false positive results.
An Australian quality control (QC) system was tested on its ability to detect analytical errors in calcium, creatinine, oxalate, phosphate and uric acid determinations in urine. This QC system revealed that our methods for calcium and urate worked well. The oxalate values were systematically higher than the assigned values and the random error was too high. Phosphate and creatinine had a marked positive deviation in the higher range of concentration but agreed better in the medium and lower ranges. The findings emphasize the need for external QC systems in urine analysis. We also discuss specific problems with urine QC compared with conventional QC for serum, the theoretical basis of creatinine-corrected urinary analytes and criteria for rejection and warning limits. We conclude that QC of urine analysis is as important as that of serum and that such programs should be used in concordance with serum QC programs.
Sera were analyzed for calcium ion activity on the Orion 99-20 and SS-20 systems. Samples from 84 healthy subjects were analyzed on both systems and, because of a change of electrode composition, 74 of them were reanalyzed after this change. Additional 89 were analyzed on only SS-20. The distribution of serum calcium ion activity was close to Gaussian. The difference between the 99-20 and SS-20 readings was 0.048+/-0.017 mmol/liter (range -0.01 to 0.08) before the electrode change and -0.085+/-0.027 mmol/liter (range -0.14 to 0.02) after. The reference ranges were 1.02--1.23 mmol/liter for 99-20 and 0.93--1.20 mmol/liter for SS-20 before the electrode change. The following characteristics may contribute to differences in the readings: higher temperature, higher flow rate, new calcium and reference electrodes, new liquid junction construction and a new pumping procedure. For 74 subjects the determination of serum calcium ion activity (99-20 system) was performed with a five year interval and the difference between the first and second measurements was -0.0046+/-0.0168 mmol/liter (mean +/-SD), ranging from -0.04 to 0.03 mmol/liter. This corresponded to an intraindividual variation of 1.5%. The corresponding variations for serum total calcium and corrected calcium were 4.8% and 3.3% respectively.
We describe a method for rapid and specific measurement of thiocyanate in serum or urine. We separate thiocyanate from interfering compounds by adsorbing it on an anion-exchange resin that has special affinity for thiocyanate, then eluting with sodium perchlorate. The eluted thiocyanate is quantified by a modified König reaction, sodium hypochlorite being used as the chlorinating reagent. Analytical recovery of thiocyanate added to serum and urine was quantitative; the coefficient of variation was 2.3% for both within-day and between-day precision. Cyanide and certain antibiotics interfere, but may be eliminated by including additional washing steps in the usual procedure. The proposed procedure was compared with another method, based on the oxidation of thiocyanate to cyanide. Agreement was satisfactory, both for serum and urine.
A method is described for the determination of thiosulphate in urine. After removal of interfering compounds, including endogenous thiocyanate by ion exchange, thiosulphate is converted to thiocyanate in the presence of cyanide and cupric ions. The thiocyanate formed is concentrated by ion exchange, eluted with an acid solution of ferric ions and the ferric thiocyanate complex determined colorimetrically. Healthy human subjects excreted 31.7 +/- 12.8 mumol/24 h (mean +/- SD) thiosulphate.
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We studied 25 borderline-hyperparathyroidism patients whose total serum calcium concentration was within normal limits (reference range: 2.25--2.75 mmol/liter) but whose concentrations of serum ionized calcium were above normal (reference range: 1.03--1.23 mmol/liter). Their hyperparathyroidism was histopathologically verified. To compare the discriminating value of corrected serum calcium with ionized calcium, we studied the serum calcium and albumin concentrations in a reference group of 2098 patients. After patients from endocrine and dialysis departments were excluded from the reference group, we obtained the range (mean +/- 2 SD) 2.05--2.71 mmol/liter for uncorrected serum calcium and 2.11--2.63 mmol/liter for corrected serum calcium. The correction factor for calcium on albumin was 20 mumol/g. Even with this limit for corrected serum calcium, 13 of 25 borderline hyperparathyroidism patients had values that fell within the reference range. We conclude that correcting total serum calcium values for serum albumin concentration improves discrimination of borderline hyperparathyroid patients, but that measurement of ionized calcium in serum discriminates better.
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Sixtynine children with case histories of food intolerance and 30 food tolerant children with atopic dermatitis have been investigated regarding serum IgE levels and IgE-, IgG, and IgA-antibodies to some common foods. Children with food intolerance had significantly higher IgE levels and to a larger extent specific IgE antibodies to the tested allergens. IgE antibodies to cow's milk were found in 71% of the children with histories of cow's milk allergy but occurred also in similar titers in 27% of milk tolerant children with other food allergies. IgE antibodies to egg-white occurred in 88% of egg allergies, but low and moderate titers were also found in 17% of children without food intolerance. However, all children with high titers had symptoms of egg allergy. IgE antibodies to the fish allergen were only found in fish allergic children while IgE antibodies to the fish allergen were only found in fish allergic children while IgE antibodies to soy-bean and green peas were found less consistently. The level of serum IgA antibodies to milk was similar in both groups. The IgG antibody titers to all tested food antigens seemed to parallel the IgE antibody titer to the same food. It was not possible to correlate the IgG antibody titers to symptoms.
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