Immunoreactive renin concentrations in healthy children from birth to adolescence

We establish normative data for immunoreactive renin concentration in serum of healthy children. In a retrospective study, surplus sera of 281 healthy children, aged 0-18 years, were collected from the laboratory. The determinations were performed with a commercially available two-site immunoradiometric assay. Functional sensitivity was 4.0 mU/l, inter-assay and intra-assay variance were 7.0-18.3% and 3.8-7.5%, respectively. In umbilical cord and during the first 4 days of life, renin concentrations (geometric mean) were significantly higher (P < 0.05) than in older infants and children [umbilical cord: 155.2 mU/l; newborn infants (2-4 days of life): 90.9; newborn infants (5-7 days of life): 32.5; 2 weeks-3 months: 40.8; 4 months-1 year: 54.5; 1-3 years: 46.3; 3-5 years: 48.5; 5-7 years: 51.6; 7-11 years: 38.5; 11-15 years: 37.7; 15-18 years: 31.9]. Newborn infants delivered by Caesarian section had significantly lower renin concentrations in umbilical cord than those delivered vaginally (P < 0.02). Considering the methodological advantages and disadvantages of plasma renin activity and renin concentration assays, renin measurement was at least as valuable and accurate as plasma renin activity determination.

[Azathioprine ingestion with suicidal intent by an adolescent with chronic juvenile polyarthritis]

We report on a 13 years 7 months old boy who ingested 650 mg azathioprine in a suicide attempt. His baseline medication was azathioprine and methotrexate for control of juvenile chronic polyarthritis. After the induction of vomiting by ipecacuanha sirup and administration of charcoal (1 g/kg), he was closely followed for haematological, hepatic, and renal side effects. During the following days, no serious adverse events were noted except that the thrombocyte (from 403,000 down to 199,000/microliter) and total leukocyte count decreased moderately (from 12,000 down to 7100/microliter). On the basis of this case report and the available literature, the potential acute toxicity of azathioprine and possible treatment modalities are discussed.

[Reconstruction of the frontobasal skull after tumor operations and trauma. Transplant selection and functional outcome]

Defects of the frontoorbital complex subsequent to extensive tumor surgery or severe trauma often result in aesthetic and functional disharmonies. The long-term results of rehabilitation related to different materials and techniques are the subject of this study. From 1974 to 1996 altogether 127 patients with bony defects of the orbit and/or the skull base underwent surgery. All patients' data were documented prospectively from 1984 onwards. The results following reconstruction with autologous calvarian transplants in 52 patients were compared to those of a control group which received iliac bone or PMMA implants. Eighty-one bony defects (64%) resulted from tumor resection; 37 patients (29%) suffered from the effects of trauma. In 67 cases (53%) reconstruction was performed primarily, in 51 cases (40%) secondarily. Free or pedicled soft-tissue transplants were necessary in order to separate the orbit and the neurocranium in 26% of the defects. On the other hand, small, isolated defects of the orbital roof (7%) were left without any reconstructive procedure. Contrary to the iliac bone grafts, the calvarian transplants resisted secondary resorption. Postoperative infections appeared in two cases; loss of transplants was avoided entirely in the group of calvarian reconstructions in contrast to the alloplasts. The selection of a suitable donor site area and rigid fixation with microplates led to excellent esthetic results even in cases with large defects.

Baroreflex sensitivity and heart rate variability in conscious rats with myocardial infarction

The baroreflex sensitivity (BRS) and the heart rate variability (HRV) were studied in conscious rats after myocardial infarction (MI; induced by coronary artery ligation) and after sham operation (SH). BRS was determined by linear regression of R-R interval vs. arterial pressure changes induced by nitroprusside or methoxamine (intravenous bolus). HRV was calculated from 3-min electrocardiogram recordings. Left ventricular end-diastolic pressure and plasma atrial natriuretic peptide were increased after MI; plasma norepinephrine and basal heart rate (HR) remained unchanged. At 3 and 28 days after MI, BRS was reduced as indicated by decreased reflex bradycardia (RB) (MI, 0.66 +/- 0.13 and 0.78 +/- 0.07 ms/mmHg; SH, 1.27 +/- 0.16 and 1.48 +/- 0.14 ms/mmHg, respectively; P < 0.05 MI vs. SH). At 56 days after MI, BRS was normalized. RB was unaffected by atropine 3 and 28 days after MI but reduced in all other groups. The increase of basal HR by atropine 3 and 28 days after MI was less than in all other groups. HRV (SD of mean N-N interval, coefficient of variance, low- and high-frequency power; studied at 28 and 56 days) was similar in all groups. It is concluded that BRS is transiently depressed in rats with left ventricular dysfunction after MI probably due to a reduced reflex vagal activity. Even though basal HR and HRV are unchanged after MI, a temporary attenuation of tonic vagal activity is unmasked after autonomic blockade.

Dual effect of digitalis glycosides on norepinephrine release from human atrial tissue and bovine adrenal chromaffin cells: differential dependence on [Na+]i and [Ca2+]i

It was the aim of the present study (1) to characterize the influence of Na+/K(+)-ATPase inhibition by the digitalis glycoside ouabain on both spontaneous and nicotine-evoked norepinephrine release from the human heart; and (2) to further investigate the role of glycoside-induced changes in [Na+]i and [Ca2+]i (determined by microfluorimetry) for catecholamine release. The latter experiments were performed in bovine adrenal medullary chromaffin cells (BCC), an established cell culture model for sympathetic nerves. Ouabain (1-1000 mumol/l) exerted a dual effect on norepinephrine release (determined by HPLC) from incubated human atrial tissue: (I) Ouabain induced a concentration-dependent increase in norepinephrine release, that was calcium-independent and almost completely prevented by blockade of the uptake1-carrier by desipramine (1 mumol/l). The characteristics of this release process are consistent with a non-exocytotic mechanism. (II) In addition, ouabain augmented the nicotine-evoked (1-100 mumol/l) calcium-dependent norepinephrine release, which can be considered to be exocytotic. Na+/K(+)-ATPase inhibition also reduced the threshold concentration of nicotine from 10 to 1 mumol/l and it delayed the rapid tachyphylaxis of its norepinephrine releasing effect in human atrial tissue. In BCC, ouabain increased [Na+]i, [Ca2+]i and [3H]-norepinephrine release in parallel. Under calcium-free conditions, not only the ouabain-induced increase in [Na+]i, but also [3H]-norepinephrine release were enhanced. The ouabain-induced [3H]-norepinephrine release was always closely related to changes in [Na+]i, indicating a key role of [Na+]i for this calcium-independent non-exocytotic norepinephrine release. In addition, pretreatment with ouabain (1 mmol/l) augmented the nicotine-evoked (0.1-10 mumol/l) increments in [Na+]i, [Ca2+]i and [3H]-norepinephrine release. As nicotine-induced norepinephrine release depends on an increase in both [Na+]i and [Ca2+]i, these findings are indicative of an ouabain-mediated facilitation of exocytosis. In conclusion, increasing [Na+]i and [Ca2+]i inhibition of Na+/K(+)-ATPase by ouabain triggers non-exocytotic norepinephrine release, and facilitates nicotine-evoked exocytotic norepinephrine release.

Problems with salivary 17-hydroxyprogesterone determinations using the Salivette device

After introduction of the Salivette device for saliva sampling, an increase of approximately 50 ng/l was noted normal values of salivary 17-hydroxyprogesterone in our laboratory compared with previous results obtained by collection of saliva by direct spitting. To further investigate this observation systematically, 17-hydroxyprogesterone was measured in saliva of 22 healthy adults after sampling without and with the Salivette and in 15 samples of distilled water rinsed over the cotton wool swab of the Salivette. The measurements were performed with a commercially available [125I]17-hydroxyprogesterone radioimmunoassay. All steps in assay performance were exactly the same. In both series, salivary 17-hydroxyprogesterone concentrations significantly increased by 40 ng/l (p < 0.05) with use of the Salivette. The variance of the differences covered a wide range. Our results confirmed that the use of the Salivette increased salivary 17-hydroxyprogesterone values by approximately 40 ng/l. This bias is unacceptable for the establishment of reference values, as these are in the range of 20-70 ng/l in the morning. Thus, at least with our assay, the use of the Salivette is discouraged. We speculate that the cotton wool swabs contain a material. possibly derived from the biological source of the cotton wool, which cross-reacts with the antibody in the assay or affects binding affinity.

Value of direct measurement of active renin concentrations in congenital adrenal hyperplasia due to 21-hydroxylase deficiency

In congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency, measurement of plasma renin activity (PRA) has been the method of choice in diagnosing salt loss and in monitoring adequacy of mineralocorticoid replacement therapy. Due to methodological problems in PRA determinations, direct immunoradiometric assays for the measurement of active renin concentration have been developed. We measured PRA and active renin concentrations simultaneously in 39 patients with CAH (30 salt-wasting, 9 simple virilizing) to evaluate the potential role of this new method in the management of this disease. PRA was determined with an enzymatic assay (sample volume: 2 x 1000 microliters plasma), active renin concentration with a direct immunoradiometric assay (sample volume: 2 x 200 microliters plasma or serum). We found a highly significant correlation between active renin and PRA in our patients (P < 0.001), as previously shown in healthy subjects. Active renin was as reliable as PRA to assess the quality of mineralocorticoid replacement.

CONCLUSION

In children, active renin determination is preferable to PRA determination because of methodological advantages and a smaller sample volume. It correlates well with PRA and determines the activation of the renin-angiotensin system as precisely as PRA. Active renin determination is useful in the surveillance of mineralocorticoid replacement therapy in CAH.

De novo direct duplication 3 (p25-->pter): a previously undescribed chromosomal aberration

We report on a case of de novo direct duplication for the distal part of chromosome 3p: 46,XY,dir dup (3) (p25-->pter). At the age of 4 years and 7 months, the boy presented with moderate growth and mental retardation, muscular hypotonia, hypoplasia of the left kidney, a short neck, and a square-shaped face characterized by a broad and flat nasal bridge, slight epicanthus, and full cheeks. So far, only a few cases with such a small distal 3p duplication have been described, and none of them has a de novo direct duplication for this region. In our patient, dysmorphic signs are less impressive, and developmental delay is relatively moderate.