Meta Damkjær Nielsen

Measurement of angiotensin II in human plasma: technical modifications and practical experience.

This paper presents our experience in measurement of plasma angiotensin II concentration according to the method described by Düsterdieck, G. and McElwee, G. (1971) Eur. J. Clin. Invest. 2, 32-38. Certain technical modifications of the procedure have been worked out. For each individual plasma sample, the recovery across extraction and elution steps is determined by addition of radio-iodinated angiotensin II. A time-saving recycling elution procedure is described. Evidence for the clinical applicability of the modified method is presented.

Solid-phase double-antibody radioimmunoassay of pepsinogen I in serum

A solid-phase radioimmunoassay for the determination of pepsinogen I in serum has been developed. The antibody was raised in rabbits with pepsinogen I isolated from urine as previously described. Radioiodination was carried out with a chloramine-T procedure resulting in a tracer with excellent shelf life. In the standard procedure with a 24-h incubation time, followed by 2-h incubation with a second antibody coupled to a solid phase, 50 microliter serum was analyzed, standard range 1.88-60 ng PG I. An eight times more sensitive method was also developed using sequential saturation techniques. Specificity studies demonstrated 0.6% crossreactivity with PG II. The immunoreactivity of PG I purified from urine was nearly identical with the immunoreactivity of PG I purified from gastric mucosa. The levels of PG I in serum from 121 control subjects were similar to those obtained with conventional phase separation methods. It is concluded that the method is simple, precise and free from non-specific serum interference.

Digoxin radioimmunoassay: Sephadex separation of free from antibody-bound digoxin

Abstract A gel centrifugation procedure for separation of free from antibody-bound material is described for the radioimmunoassay of digoxin. The separation technique is evaluated by equilibrium studies, investigation of reproducibility and precision, serial dilutions and comparison with the 86 Rb method for determination of plasma digoxin concentrations.

The renin-angiotensin system during converting enzyme inhibition with captopril in patients with severe treatment-resistant hypertension.

Abstract. The effect of captopril on blood pressure (BP) and various components of the renin‐angiotensin system was assessed in ten severely hypertensive patients. Captopril acutely reduced the BP with a maximum decrease of 23% at 90–120 min.

Double-antibody solid-phase radioimmunoassay for blood bradykinin

A solid phase radioimmunoassay for the determination of blood bradykinin has been developed. Highly specific antibodies against bradykinin were raised in rabbits after coupling the peptide to thyroglobulin. Iodination of [Tyr8]-bradykinin was carried out with a chloramine-T procedure resulting in a tracer with high specific activity. Bradykinin was isolated in the following way: blood was sampled directly into acetone, and lipids were removed by extraction with petroleum either (40-60 degrees C). The final purification was made on QAE-Sephadex A-25 at pH 7.4. The mean recovery of added [125I-Tyr8]-bradykinin was 28% with a sample volume of 6 ml whole blood. The sensitivity of the radioimmunoassay was 1.25 pg/tube or 3 pg/ml blood. The reproducibility of the method is satisfactory with a between-assay coefficient of variation below 16%. Levels found in venous blood were below 3 pg bradykinin/ml in normal persons.

Acute effects of smoking on left ventricular function and neuro-humoral responses in patients with known or suspected ischaemic heart disease

Systolic left ventricular function was examined by radionuclide ventriculography in 12 habitual smokers with known or suspected ischaemic heart disease, aged 33–69 years, before, during, and after smoking of two cigarettes in a row and was repeated on a non‐smoking control day. Plasma concentrations of adrenaline, noradrenaline, renin, and angiotensin II were determined on the smoking day, before and immediately after smoking. During smoking, there were significant increases in heart rate (+27%), rate‐pressure product (+23%), and cardiac output (+14%) in the face of a significant increase in left ventricular end‐systolic volume (+5%) and significant decreases in ejection fraction (−6%) and stroke volume (−8%). Blood pressure was virtually unchanged, and total peripheral resistance remained constant. Plasma adrenaline increased by 100%, renin decreased by 21%, and noradrenaline and angiotensin II did not change. The humoral changes were not correlated to changes in any of the haemodynamic variables. Areas of myocardial hypokinesis emerged or widened during smoking in 11 of 12 patients. Thus, in patients with known or suspected ischaemic heart disease, smoking was associated with an acute decrease in systolic ventricular function and development of widespread hypokinesis despite adrenaline stimulation.

Radioimmunoassay for saralasin by means of anti-angiotensin II sera

A radioimmunoassay for the angiotensin II-inhibitor saralasin has been developed. The assay is based upon an exploitation of the cross-reactivity of antisera raised against angiotensin II, with radioiodinated saralasin as the tracer peptide. Performance data for the assay and results obtained in clinical infusion studies are presented.

Congenital adrenal hyperplasia associated with a balanced 13–18 translocation

A newborn infant was found to have saltlosing adrenal hyperplasia, ambiguous genitalia, and a balanced translocation between 13q and 18p. The simultaneous occurrence of the two defects is probably coincidental.

INFLUENCE OF CORTICOTROPHIN ON URINARY 17-KETOSTEROID EXCRETION IN ADRENALECTOMIZED FEMALES

Urinary excretion of 17-ketosteroids was measured during dexamethasone substitution followed by ACTH (Synacthen Depot, 1 mg daily) in 10 non-virilized adrenalectomized women. No significant changes could be demonstrated indicating ovarian androgenic dependence of ACTH in non-virilized females.