Arne Høj Nielsen

Long-term follow-up of von Recklinghausen neurofibromatosis. Survival and malignant neoplasms.

To document the natural history of von Recklinghausen neurofibromatosis, we followed up a nationwide cohort of 212 affected patients and families identified in Denmark 42 years ago. We obtained follow-up information on 99 percent. Because all 76 probands were identified through hospitals, they may include a disproportionate number of severe cases of neurofibromatosis. To diminish this effect of selection bias, we distinguished between the probands and their affected relatives. In a comparison with the general population, survival rates were significantly impaired in relatives with neurofibromatosis, worse in probands, and worst in female probands. Malignant neoplasms or benign central nervous system tumors occurred in 45 percent of the probands, giving a relative risk of 4.0 (95 percent confidence limits, 2.8 to 5.6) as compared with expected numbers. Multiple primary neoplasms were found in 15 probands, but only 1 relative. Compared with the general population, male relatives with neurofibromatosis had the same rate of neoplasms, whereas female relatives had a nearly twofold higher rate (relative risk, 1.9; 1.1 to 3.1). Nervous system tumors were disproportionately represented. We conclude that patients with severe neurofibromatosis requiring hospitalization often have a poor prognosis, but incidentally diagnosed relatives may have a considerably better outcome.

Renin is synthesized as a 50,000 dalton single-chain polypeptide in cell-free translation systems.

A number of eukaryotic secretory proteins are synthesized as molecules with an amino-terminal extension of 16-25, mainly hydrophobic, amino acid residues, when their mRNAs are translated in cell-free systems devoid of microsomal membranes (reviewed [ 1,2]). This short extension is named the ‘pre-’ or ‘signal’ peptide and is thought to be essential for the secretion of these proteins [3]. In addition, many secretory proteins, such as some enzymes and peptide hormones, are derived by cleavage of large precursor chains (proenzymes or -hormones). Thus, in these latter cases, the initial translation products are single-chain pre-proenzymes or pre-prohormones [12,4,51. We have isolated total poly(A)-containing mRNA from renin-rich submaxillary glands of mice. These mRNAs were translated, in the presence of [35S] methionine, in two mRNA-dependent cell-free systems from wheat germ and reticulocyte lysate, respectively. The radioactive translation products were subjected to immunoprecipitation with antirenin or pure renin-specific Fab fragments, and characterized by SDS-acrylamide gel electrophoresis. Our data indicate that renin is initially synthesized as a precursor -10 000 daltons larger than the enzymatically active 40 000 dalton renin. In analogy with other enzyme precursors, this may well represent a pre-prorenin.

ANGIOTENSIN II RECEPTORS AND RENIN IN THE PORCINE UTERUS: MYOMETRIAL AT2 AND ENDOMETRIAL AT1 RECEPTORS ARE DOWN‐REGULATED DURING GESTATION

1. The aim of the present study was to characterize the angiotensin II (AngII) receptor subtypes in the porcine uterus and the variation of receptor densities and renin concentrations during gestation.

ANGIOTENSIN II RECEPTOR DENSITY IN BOVINE OVARIAN FOLLICLES RELATES TO TISSUE RENIN AND FOLLICULAR SIZE

1. The purpose of this study was to investigate angiotensin II (AII) receptors in isolated bovine ovarian follicles and the relationship of their density to follicular concentrations of prorenin, active renin, oestradiol and progesterone.

Measurement of inactive renin in rat plasma : effect of nephrectomy and sialoadenectomy on the plasma concentration

In this paper we describe a routine method of measuring inactive renin in rat plasma. The activation was performed by trypsin, at optimal concentration and incubation conditions. The trypsin treatment formed an interfering and high-performance liquid chromatography-verified tetradecapeptide-like material, which was removed before the assay by a simple batchwise use of a cation-exchange resin. The concentration of activated inactive renin was measured by an antibody-trapping method after the addition of exogenous angiotensinogen. Angiotensinogen was added in order to compensate for the trypsin destruction of angiotensinogen and in order to measure the parameter of renin concentration. The inactive renin concentration in plasma of conscious male rats was 0.48 +/- 0.13 Goldblatt units (GU) per litre (n = 38). This corresponds to 66% (range 42-92%) of the total renin concentration. Physiological experiments in conscious rats were initiated, demonstrating that nephrectomy decreased the inactive renin concentration from 0.45 +/- 0.14 to 0.27 +/- 0.05 GU/l after 24 h (n = 21; P less than 0.01). Submandibular sialoadenectomy decreased the plasma inactive renin concentration from 0.45 +/- 0.11 to 0.34 +/- 0.06 GU/l (n = 12; P less than 0.05) after 7 days. Combined sialoadenectomy and nephrectomy decreased the plasma inactive renin concentration from 0.45 +/- 0.11 to 0.24 +/- 0.06 (n = 12; P less than 0.01).

RENIN AND PRORENIN IN REPRODUCTIVE TISSUES DURING GESTATION IN PIGS AND CATTLE

1. High concentrations of prorenin and active renin were previously found in ovarian follicular fluid from cattle but not from pigs. In the present study female reproductive tissues and fluids from cattle and pigs during gestation were investigated to clarify a possible species difference in active renin and prorenin concentrations.

Prorenin and active renin concentrations in ovarian follicular fluid increase after the LH peak in superovulated heifers.

1. The aim was to analyse the in vivo variations with time of prorenin and active renin and their relationship to steroid hormones in ovarian follicular fluid during follicular growth in heifers.

Measurement of renin and prorenin in cattle, hog and horse.

1. Species specific problems complicating the measurement of prorenin and renin concentrations were studied in bovine, hog and horse plasma. 2. In contrast to horse renin, bovine and hog renin reacted with rat angiotensinogen, allowing measurement of the plasma renin concentration in cattle and hog with rat angiotensinogen as exogenous substrate. 3. Trypsin treatment of plasma in order to activate prorenin generated an interfering angiotensin I immunoreactive material in all three species, most extensively in horse plasma. 4. This material could be removed in bovine and hog plasma by a cation-exchange resin, allowing an assay of the plasma prorenin concentration to be constructed in these species. 5. Another strategy has to be followed in order to measure prorenin and renin concentrations in horse plasma.

Renin in the mouse submaxillary gland has a molecular weight of 40,000.

The availability of pure submaximillary renin, its antibody and pure specific immunoreactive Fab fragments of the antirenin molecule were used in an attempt to detect in which form renin is stored in the submaxillary gland. The proteolytic activity of serine-, metallo- and sulfhydryl enzymes during homogenisation was inhibited, but no inactive or high molecular weight form could be detected enzymatically or antigenically after gelfiltration. Nor were they demonstrable in crossed immuno-electrophoresis by using antibodies elicited against pure renin. Furthermore, pepstatin which additionally inhibits acid proteases, including a possible autoactivation of renin, and renin specific Fab fragments, were added, the latter in order to steric hinder proteolytic attack on a possible renin precursor. The renin-Fab complex was purified by precipitation with anti-Fab antibodies. No high molecular weight renin was demonstrable in SDS polyacrylamide gel electrophoresis. The only form of renin demonstrable in the submaxillary gland of mice was the fully active 40,000 dalton form. Its specific enzymatic activity was identical to that of pure submaxillary renin, being 0.4 . 10(-3) Goldblatt unit . ng-1.

EFFECT OF GONADOTROPINS AND PREGNANCY ON PRORENIN AND RENIN IN THE RAT

1. Stimulation of adult female rats with pregnant mare serum gonadotropin (PMSG) and human chorion gonadotropin (hCG) increased active plasma renin about two‐fold, but caused only a slight increase of plasma prorenin. The concentrations of active renin and prorenin in the ovaries, and active renin in the uterus all increased about two‐fold 2 days after stimulation with PMSG. The prorenin in the uterus was below detection in unstimulated rats and did not change consistently after PMSG.