Pulsatile secretion of TSH in healthy subjects

The physiological variations in serum TSH concentration have been investigated using an enzyme amplified immunoassay with improved sensitivity and precision. Blood samples were collected at regular intervals from 10 healthy volunteers during the period 1800 h to 0100 h. Spectral analysis followed by periodic regression analysis demonstrated significant serum TSH pulsatility with periodicities of 60 or 85-100 min. In addition, a significant (P less than 0.001) evening rise in serum TSH concentration was demonstrated in all subjects, with levels rising at around 21.30-22.00 h.

Evaluation of a commercial immunoenzymometric assay for human prolactin

A commercially available immunoenzymometric assay for human prolactin based on two monoclonal antibodies, one bound to a solid-phase bead and the other conjugated to alkaline phosphatase, was evaluated. The assay had a lower limit of detection of 2 ng/ml and between-batch coefficients of variation of less than 10% for prolactin concentrations in the range 7-152 ng/ml. Assay accuracy as judged by comparison of patient samples analysed by a RIA, assay of quality control samples and recovery experiments, was good. No significant cross-reactivities or interferences were found. The assay is precise, accurate, fast and robust with the advantage of using a non-isotopic label.

Urine discoloration after acetaminophen overdose

Three patients with acetaminophen overdose were observed to have dark-brown urine at an early stage of their illness. Subsequently, acute anuric renal failure and hepatic dysfunction developed in all three. p-Aminophenol was identified by chromatographic and colorimetric methods in the urine of each case and is thought to be responsible for the discoloration.

Urine discoloration after acetaminophen overdose

Three patients with acetaminophen overdose were observed to have dark-brown urine at an early stage of their illness. Subsequently, acute anuric renal failure and hepatic dysfunction developed in all three. p-Aminophenol was identified by chromatographic and colorimetric methods in the urine of each case and is thought to be responsible for the discoloration.

Stressful life situations and perception of stress in black and Indian duodenal ulcer patients

The stressful life situations of 87 patients with endoscopically confirmed recent duodenal ulceration (DU) were compared with those of 75 essentially orthopaedic non-DU controls. Results indicated a statistically significant difference in the reporting of low income and dissatisfaction, including tensions related to considerable responsibility in the work situation but no authority, by both Indian and black DU patients. Indian DU patients reported significantly more family conflict and problems than controls, while black DU patients reported living in single hostels or in split families to a significantly greater degree than controls. Overall, DU patients experienced significantly greater stress in more areas of their lives than controls.

Enzyme-amplified immunoassays: a new ultrasensitive assay of thyrotropin evaluated

An enzyme-amplified immunoassay for thyrotropin has been evaluated. The lower limit of detection of the assay (mean + 3 SD of the zero standard) was 0.037 milli-int.unit/L and the precision was good, giving a working range of 0.13-24.0 milli-int.units/L. The accuracy of the assay was good, as judged from analytical-recovery experiments, analysis of external quality-assessment samples and comparison with in-house assays. No significant interferences or cross reactivities were identified. Assay of a 25-microL serum sample on the microtiter plate takes 3 h. Values for healthy subjects ranged from 0.4 to 4.0 milli-int.units/L. For 32 thyrotoxic patients thyrotropin concentrations were clearly suppressed and completely distinct from normal values. Patients taking triiodothyronine also showed lower concentrations. The enzyme-amplified immunoassay may thus be a suitable "front line" test for assessing thyroid function.

Enzyme-amplified immunoassays: a new ultrasensitive assay of thyrotropin evaluated

An enzyme-amplified immunoassay for thyrotropin has been evaluated. The lower limit of detection of the assay (mean + 3 SD of the zero standard) was 0.037 milli-int.unit/L and the precision was good, giving a working range of 0.13-24.0 milli-int.units/L. The accuracy of the assay was good, as judged from analytical-recovery experiments, analysis of external quality-assessment samples and comparison with in-house assays. No significant interferences or cross reactivities were identified. Assay of a 25-microL serum sample on the microtiter plate takes 3 h. Values for healthy subjects ranged from 0.4 to 4.0 milli-int.units/L. For 32 thyrotoxic patients thyrotropin concentrations were clearly suppressed and completely distinct from normal values. Patients taking triiodothyronine also showed lower concentrations. The enzyme-amplified immunoassay may thus be a suitable "front line" test for assessing thyroid function.

The investigation of proteinuria in pregnancy using iso-dalt analysis

Urinary protein excretion has been investigated using the iso-dalt technique in pregnant patients with hypertension and proteinuria, without hypertension but with proteinuria and without either hypertension or proteinuria. This high resolution electrophoretic technique has shown a great variation in the pattern of protein excreted by these patients, particularly those with hypertension. These showed an increased number of protein species in the urine, some of unknown identity. Two urines from this group appeared to contain no detectable albumin. Currently this technique is inappropriate for the routine analysis of urine proteins. However, further studies may determine the diagnostic value of these changes in urine excretion and allow the development of more specific assays.

Membrane ultrafiltration: concentration of interleukin-3

A pilot-plant-scale operation was used for studying membrane ultrafiltration and concentration of kiloliter quantities of the lymphokine interleukin-3 with a single set of membranes. Initial use of ammonium sulfate precipitation of interleukin-3 proved erratic in the recovery of biological activity and resulted in corrosion of the processing equipment. Membrane ultrafiltration proved to be effective in enabling control of the degree of concentration and predicting recovery of the biologically active protein.

Acetaldehyde-hemoglobin adducts: an unreliable marker of alcohol abuse

Acetaldehyde reacts with hemoglobin in vitro to produce acetaldehyde-hemoglobin adducts, but we could not detect these in the blood of 20 alcoholics, either by cation-exchange chromatography or agar gel electrophoresis. Thus, contrary to previous reports, this test is not a reliable marker of alcohol abuse. Nuclear magnetic resonance and gas chromatographic-mass spectroscopic analysis of acetaldehyde revealed the presence of aldehydic impurities. Formation of adducts in vitro may thus result from the reaction of hemoglobin with these impurities or with acetaldehyde condensation products (aldol) or from acetaldehyde condensation/dehydration products (crotonaldehyde).

Acetaldehyde-hemoglobin adducts: an unreliable marker of alcohol abuse

Acetaldehyde reacts with hemoglobin in vitro to produce acetaldehyde-hemoglobin adducts, but we could not detect these in the blood of 20 alcoholics, either by cation-exchange chromatography or agar gel electrophoresis. Thus, contrary to previous reports, this test is not a reliable marker of alcohol abuse. Nuclear magnetic resonance and gas chromatographic-mass spectroscopic analysis of acetaldehyde revealed the presence of aldehydic impurities. Formation of adducts in vitro may thus result from the reaction of hemoglobin with these impurities or with acetaldehyde condensation products (aldol) or from acetaldehyde condensation/dehydration products (crotonaldehyde).

Potential applications and pitfalls of dry reagent tests. An evaluation of the Ames Seralyzer

In recent years, the development of dry reagent tests has made it possible for many clinical laboratory tests to be performed not only in the laboratory but also elsewhere. Some of the factors influencing the applications and use of one such system, the Ames Seralyzer, have been studied. Sample volume and the timing of analysis were critical, and poor precision was obtained by an inexperienced operator. The calibrators and reagent strips were stable when stored as recommended by the manufacturer, and calibration was stable for 24 hours. The implications of these findings as well as the problems of method comparison and quality control are discussed, particularly in relation to the use of the instrument outside the laboratory. More generally, this study illustrates several problems with the use of dry reagent, thin films and associated instrumentation that must be considered during evaluations.

The effect of calf serum on human lymphoblastoid cell-derived interferon production

Substitution of low-cost calf serum for fetal bovine serum was evaluated in Namalva cell production of human alpha-lymphoblastoid interferon [HuIFN-alpha(Ly)] in 50-liter fermentors. Namalva cell growth and IFN yields were greatly reduced and protein precipitate weight increased from calf serum-supplemented cell cultures. The overall reduction in IFN production was greater than threefold, making the substitution impractical.

Ultrathinfilm immunoelectrophoresis

Immunoelectrophoresis (Laurell-rocket) in ultrathinfilm gels has been applied to the determination of human serum albumin in a model study. Agarose gels of 0.24 mm thickness were used and optimum electrophoretic conditions were determined. Precision was assessed and comparison with conventional immunoelectrophoresis and a chemical method was made. Though precision was poor (CV 4-6%) improvements in dispensing small volumes (0.2 microliter) should change this. Good correlation between methods (correlation coefficient 0.89-0.97) was obtained. The advantages of the technique are speed of analysis and low reagent costs.