Sequence of cDNA encoding human insulin-like growth factor I precursor

Somatomedins (SM) or insulin-like growth factors (IGF) constitute a heterogeneous group of peptides with important growth-promoting effects in vitro as well as in vivo. Amino acid sequences have been determined for only two of them, IGF-I and IGF-II, which are highly homologous. IGF-I, which is identical with SM-C, is composed of 70 amino acid residues and IGF-II contains 73 amino acids and may be identical with SM-A. Other peptides with different charge properties but with similar SM-like or insulin-like behaviour in biological and receptor assays, have been described but have not yet been fully characterized. The liver is known to be a major site of production of these peptides, but many other tissues--especially in the fetus--may synthesize them as well. We report here the nucleotide sequence of a human liver cDNA encoding the complete amino acid sequence of IGF-I. The IGF-I coding region is flanked by sequences encoding an amino-terminal peptide of at least 25 amino acid residues and a carboxyl-terminal peptide of 35 amino acids. This provides evidence that IGF-I is synthesized as a precursor protein and that formation of IGF-I from this precursor requires proteolytic processing at both ends.

Levels of renin, angiotensin I and II, angiotensin-converting enzyme and aldosterone in infancy and childhood

Basal plasma renin activity (PRA), angiotensin I and II (AI, AII), angiotensin-converting enzyme (ACE) activity and plasma aldosterone (PA) and sodium and potassium concentration were simultaneously measured in 55 healthy recumbent children aged between 1 week and 13 years. A significant (P less than 0.001) age-related decrease for PRA (r = -0.73), AI (r = -0.72), AII (r = -0.51) and PA (r = -0.71) was observed but not for ACE (r = 0.26, P = 0.06). After correction for age the correlation between PRA or PA and AI or AII was still significant (P less than 0.005). The strong correlation between AI and AII in the group as a whole (r = 0.82, P less than 0.001) and also in separate age groups, and an AI to AII ratio which was not different between the various age groups suggest that ACE activity in this age range is not rate-limiting for AII generation.

Influence of the stress of venepuncture on basal levels of plasma renin activity in infants and children

The influence of venepuncture on plasma renin activity (PRA), cortisol, and serum noradrenaline and adrenaline concentration in infants and children was evaluated by comparing values obtained immediately on insertion of an indwelling intravenous line (venepuncture value) and 5 and 60 minutes later. PRA values 5 min after venepuncture in the total group of infants and children were significantly higher (P less than 0.001) than venepuncture values. There was no significant difference between PRA values at 60 min compared to venepuncture or 5 min values. A well performed venepuncture does not systematically affect the PRA values obtained. A significant difference between values for noradrenaline, adrenaline and cortisol at the various points of time could not be demonstrated. The number of lower values for noradrenaline and adrenaline at 60 min, however, prevailed. The stress of a well performed venepuncture is not an explanation for the greater scatter of basal PRA levels in infants and young children.

Hyperthyroxinaemia due to decreased peripheral triiodothyronine production

Two patients, a boy of 8 and a women of 60 years of age, had higher than normal levels of serum total thyroxine (T4), free T4, (FT4), FT4 index, and reverse triiodothyronine, but normal serum triiodothyronine (T3) levels. The pituitary-thyroid axis could be normally stimulated by thyrotropin-releasing hormone, suggesting euthyroidism at the pituitary level. High levels of serum T4-binding globulin decreased during T3 treatment in the boy. Studies show that in these patients a raised serum FT4 is necessary to produce in the peripheral tissues sufficient amounts of T3 for biological action. Two possible mechanisms for a basic defect underlying this newly recognised syndrome are proposed: inhibition of T4 transport into tissue cells and reduced intracellular 5'-deiodinase activity catalysing T4 to T3 conversion.

Ring chromosome 2: clinical, chromosomal, and biochemical aspects

A new case of ring chromosome 2 is described and compared with the five cases hitherto reported. The clinical picture includes a severe pre- and postnatal growth failure, microcephaly, psychomotor retardation, and some minor dysmorphic features. Cytogenetic studies revealed a ring 2 structure and aneuploidy. Banding analysis failed to demonstrate a substantial loss of chromosomal material. Enzymologic studies revealed a decrease of red cell acid phosphatase activity suggesting the localization of its gene inthe 2p25 leads to 2 pter region.

Reinstitution of mineralocorticoid therapy in congenital adrenal hyperplasia. Effects on control and growth

The results of reintroduction of mineralocorticoid substitution therapy (9-alpha-fluorohydrocortisone) in five children with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency are described. All children had shown a salt-losing syndrome in infancy, but were off mineralocorticoids during several years; at the start of this study they all had elevated plasma renin activity (PRA). Four of them had increased and fluctuating pregnanetriol excretion during the year preceding reintroduction of mineralocorticoids, indicating poor control despite substantial substitution with hydrocortisone: 26 +/- 1.9 mg/m2/day (mean +/- S.E.M.). Reintroduction of mineralocorticoid therapy at ages 5.0-9.4 years resulted in a marked improvement of control, significant reduction in hydrocortisone requirements (to 17.6 +/- 1.4 mg/m2/day) and improvement in linear growth. The data suggest that, in all children with CAH and elevated PRA, continuation throughout childhood of mineralocorticoid therapy in addition to glucocorticoid therapy is necessary for optimal control and linear growth.

Biotransformation and spectral interaction of xenobiotics with subcellular fractions from Drosophila melanogaster

Several rapid bioassays are in use to detect, by means of mutagenicity, the formation of reactive metabolites from foreign compounds during their metabolism in the organism. Of these bioassays, the fruitfly Drosophila melanogaster was investigated with respect to its capacity to biotransform xenobiotics. By spectral analysis it was shown that in microsomal preparations of Drosophila the cytochromes P-450 and b5 are present. Microsomes appeared to possess aryl hydrocarbon hydroxylase and epoxide hydratase activities, while post-microsomal supernatants were able to conjugate appropriate compounds with glutathione and phosphate. As yet, glucosyl- and sulfotransferase activities can not be detected. The activities are compared to similar activities in rat liver.

A solid-phase radioimmunoassay for the measurement of antibody to Aspergillus in invasive aspergillosis

A solid-phase radioimmunoassay (SPRIA) to measure antibody responses to Aspergillus fumigatus and Aspergillus flavus antigens in invasive aspergillosis (IA) was developed and compared with immunodiffusion (ID) and counterimmunoelectrophoresis (CIE). SPRIA detected significant elevations in levels of aspergillus antibody in 15 (79)% of 19 patients with IA. Fewer patients with IA were positive by ID (give of 19) or CIE (four of 19). Only seven )8%) of 58 subjects with other fungal or bacterial infections were positive by SPRIA, as was one (5%) of 20 by ID and CIE. Weak cross-reactivity between aspergillus and candida antigens was demonstrated by SPRIA. IgG levels in patients with IA and control subjects were equivalent. Thus, an antibody response to Aspergillus can be detected in a greater percentage of patients with IA by SPRIA than by ID or CIE. Although a few patients without aspergillosis had elevated levels of aspergillus antibody, a rise in antibody level was specific for IA.

Xenobiotica-metabolizing enzymes in Drosophila melanogaster: activities of epoxide hydratase and glutathione S-transferase compared with similar activities in rat liver

Activities of epoxide hydratase and glutathione (GSH) S-transferase were investigated in subcellular fractions of Drosophila melanogaster, and these activities were compared with analogous enzymic activities in extracts from rat liver. Microsomes of Drosophila were active in the hydratation of styrene oxide catalyzed by epoxide hydratase. The post-microsomal supernatant of Drosophila catalyzed the conjugation of GSH with 1-chloro-2,4-dinitrobenzene. However, GSH S-transferase activity with styrene oxide as the electrophilic substrate was not measurable. The respective specific activities of epoxide hydratase (per mg microsomal protein) and GSH S-transferase (per mg cytosolic protein) were factors of 5- and 10-fold lower than the corresponding activities in rat liver. However, when expressed per gram body weight, activities of both epoxide hydratase and GSH S-transferase were 3 times higher for Drosophila enzymes. The apparent Km values for the two Drosophila enzymes were higher, whereas the apparent Km values were lower, than the values found for the rat-liver enzymes. Among 3 different Drosophila strains (a wild-type, a white eye-color carrying mutant strain and a DDT-resistant strain), preliminary experiments showed no differences as far as these two enzymic activities were concerned. It is concluded that the results obtained in genetic toxicology testing with Drosophila are probably relevant to effects to be expected in mammalian systems with compounds requiring metabolic processes involving the enzymes investigated here.

A new method for measuring antibody using radiolabeled protein A1 in a solid-phase radioimmunoassay

A micro solid-phase radioimmunoassay was developed which utilizes radiolabeled staphylococcal Protein A ([125I]Protein A) in place of radiolabeled anti-immunoglobulin ([125I]anti-IgG) for the measurement of antibody. For the assay, antigen is adsorbed to the wells of a microtiter plate followed by dilutions of serum and [125I]-Protein A in subsequent steps. We found that this assay can be used to measure antibody (Ab) against a variety of antigens in human and rabbit but not goat immune serum. Binding of [125I]Protein A and [125I]anti-IgG to human and rabbit IgG was comparable. It was possible to quantify this amount of Ab in human serum by reference to immune rabbit serum. The sensitivity of this assay for rabbit antibody was 1 ng/ml.

Antibody to Tamm-Horsfall protein in patients with urinary tract obstruction and vesicoureteral reflux

Urinary tract obstruction and vesicoureteral reflux, which are often associated with urinary tract infections, may lead to progressive renal damage. Relatively little is known about the pathophysiology of this process, and a need exists for noninvasive methods of its detection in its early stages. Because urine is refluxed into the venous and lymphatic drainage of the kidney in severe vesicoureteral reflux and urinary tract obstruction, an immune response to urinary tract components might play a role in the pathophysiology of progressive renal damage and serve as a serologic marker for its presence. A solid-phase radioimmunoassay for a protein found only in the urine (Tamm-Horsfall protein [THP]) was developed and used to measure antibody to THP in the serum of 60 subjects. Significant elevations of antibody to THP were observed in five of 15 patients with obstruction and infection of the urinary tract and in one of 10 patients with infection alone, when these patients were compared with 12 healthy control subjects. Similar elevations of antibody to THP were not seen in uninfected patients with urinary tract obstruction or in patients with low-grade vesicoureteral reflux or sepsis of nonrenal origin. These results suggest that the measurement of antibody to THP might be useful in the identification of patients with obstruction and infection of the urinary tract.