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Biomedical subjects

L Simionescu

Publications and source records attributed to L Simionescu.

At least 55 records · Page 3Linked to original sources

Immunoreactive insulin (IRI) dynamics in GH-deficient patients following intravenous glycine loading.

In hypopituitary short-statured patients glycine intravenous injection (250 mg/kg of body weight) provokes a mild and inconstant stimulation of IRI release followed by a significant fall down. Though insiginificant (P 0.064), the prevalence of IRI responsive individuals to glycine in the patients group of idiopathic etiology could be of pathophysiological importance.

Adolescent↗

The development of a radioimmunoassay system for testosterone (T) and dihydrotestosterone (DHT). Part 1. The preparation of the T-derivatives and T-protein conjugates.

Testosterone-17-hemisuceinate (T-17-HS) by esterification with succinic anhydride technique and Testosterone-3-carboxy-methyl-oxyme (T-3-CMO) derivatives were synthesized. The T-protein (BSA) conjugates were prepared by the condensation with carbodiimide technique, for the T-17-HS derivative and by the mixed anhydride technique, for the T-3-CMO. Both the derivatives and the T-BSA conjugates were characterized by melting point, ultraviolet and infrared spectra, thin layer chromatography. The physico-chemical characteristics and the hapten-protein incorporation being convenient: 28 mol T/mol BSA for T-17-HS-BSA and 38 mol T/mol BSA for T-3-CMO-BSA, the T-carrier conjugates are adequate for their use as immunogens.

Animals↗

Growth hormone (GH) release by arginin-vasotocin (AVT) given intranasally in sexually immature children.

Eighteen healthy children were given 50 micrograms synthetic AVT intranasally and samples of serum for GH, magnesium and alpha-amino-nitrogen were drawn 30, 60 and 120 minutes later. There was a significantly different mean of GH peak level (13.1 +/- 3.02 microU/ml) which occurred generally at 30 minutes. The number of GH responders (i.e. peak level greater than 15 microU/ml) was of 7/18. The means of chemical determinations elicited little though opposite changes: slight increases in magnesium and slight decrease in alpha-amino-nitrogen. In a separate day, a sleep test of 30 minutes-duration performed in the morning resulted in a significantly greater GH peak level (28.2 +/- 9.7 microU/ml) but the number of GH responders was nearly the same (6/18). The serum magnesium levels following sleep decreased slightly and unsignificantly. The involvement of serotonergic neurons in mediating GH-releasing effects of AVT is briefly discussed.

Administration, Intranasal↗

The development of a radioimmunoassay system for testosterone (T) and dihydrotestosterone (DHT). Part 2. The preparation of antisera to T.

Testosterone-3-O-carboxymethyl-oxime derivative was synthetized and coupled to bovine serum albumin (BSA). The T-3-CMO-BSA conjugate homogenized with Freund's adjuvant used as immunogen was injected multiple sites in rabbits. The antisera collected were characterized in a radioimmunological system, separation with dextran-charcoal using 125I-Testosterone as tracer. The antibody titres varied from one animal to another. The titre of anti-T serum selected for RIA was 1: 10(4)-1: 2 X 10(4) (initial dilution). All anti-T sera 100 percent crossreacted with 5 alpha-dihydrotestosterone but nonsignificant interference was observed with other C19, C21 and C18 steroids. The affinity constant of the selected anti-T serum was in the range 1.4-1.9 X 10(9) litres/mole. The data so far published on the antisera toward testosterone are reviewed. We conclude that the selected anti-T-3-CMO-BSA serum may provide assays for testosterone with potential for clinical applications.

Animals↗

The development of a radioimmunoassay system for testosterone (T) and dihydrotestosterone (DHT). Part 3. The preparation of radioiodinated testosterone.

A two step-method was applied for the preparation of a tracer adequate for a radioimmunoassay (RIA) system for testosterone. Histamine was radioiodinated by the Chloramine-T method and then coupled to testosterone-3-carboxymethyl-oxime (T-3-CMO) derivative. After purification by TLC, the steroid tracer was stable in ethanol for at least four months. Using an anti-T-3-CMO-BSA serum, a (bridge) homologous RIA system for testosterone was developed. The reagents (antiserum, tracer and standard) were incubated 2 hrs at 37 degrees C and then the free radioactivity was removed by a dextran-charcoal suspension. The testosterone RIA system, with the sensitivity of 30 pg/tube, is suitable for the measurement of the steroid hormone in biological fluids and tissues.

Animals↗

Testosterone in sera of workers exposed to acrylonitrile.

Testosterone was measured through three consecutive years in sera from young and adult male subjects working in a chemical factory exposed to some complex chemical noxae, the major exposure being acrylonitrile (vinylcyanid). In the first yr, (group A), the blood was collected on May 1975 (no 39), the II-nd yr (group B) on March (no 109) and the III-rd yr (group C) on May (no 149). The exposure time varied in each group between 6 mos and 7-10 yrs. For comparison, blood samples were collected from 145 men of comparable age grouped in nonexposed: blood donors (no 37) (group a), new workers (no 23) (group b) and exposed to other chemical noxae in the same factory: Na cyanid (group c, no 23), cyan derivatives (group d, no 22) and pyrolysis (group no 39). The seasonal testosterone variations being considered, the Student's 't' test applied to the hormonal levels in acrylonitrile groups A, B and C showed non significant differences. However, the comparison of the testosterone concentrations in sera of the groups A, B and C vs the control groups investigated during the same month of the year showed much lower levels of the hormone in the first groups (p less than 0.001). These data are suggesting that the exposure to acrylonitrile either by direct participation to the technological chain or by working in the same noxious environment may influence the testosterone synthesis and/or secretion.

Acrylonitrile↗

The measurement of the peptide hormones in saliva. 2. Chorionic gonadotropin subunits in pregnancy.

The alpha and beta subunits of the human chorionic gonadotropin (HCG) were measured during pregnancy in the saliva of a first group (no. = 23) and in the serum and saliva of a second group (no. = 25). Only ten pregnant women had normal gestation, the remaining 39 being diagnosed as miscellaneous pathologies, the threatened (or impending) abortion being the most frequent (no. = 19). The mean serum levels of alpha-HCG increase from 75.97 +/- 18.59 ng/ml (X +/- SEM) during the first trimester to 341.98 +/- 65.09 ng/ml during the third trimester of the gestation. The mean salivary concentration of the alpha HCG seems unmodified during pregnancy (approximately 10 ng/ml), but large interindividual variations were observed (limits 0.10-28.78 ng/ml) possibly due to the non-homogeneity of the investigated groups. The presence of the beta-HCG subunit in saliva could not be assessed, the great part of the values being aggregated around the sensitivity limit of the RIA technique (0.2 ng/ml). The physiological significance of the presence of the HCG and of its subunits in saliva as well as the ways to elucidate the possible selective role of the blood-saliva barrier are discussed.

Adolescent↗

Thyroglobulin autoantibodies in endocrine diseases.

A simple, rapid haemagglutination laboratory kit was developed for the measurement of the thyroglobulin autoantibodies (Tgl-AAb). The Tgl-AAb kit was applied to the measurement of the AAbs titres in the sera collected from 2861 endocrine patients either hospitalized in the Institute of Endocrinology (about 75%) or endocrine outpatients--the great part of patients (over 90%) being however diagnosed as thyroid disorders. The sex classification showed the F/M ratio 6.61/1 for the whole group and 7.4/1 for the positive cases. The prevalence of the Tgl-AAbs positive sera at low titre (under 1:200) is 11.6% about twofold higher than in a population of 700 blood donors (6.4%), previously reported. Among the significant Tgl-AAbs titres, chosen more or less arbitrarily over 1:200, 30.47% of the patients have titres in the range 1:200-1:5000. The Tgl-AAbs positive and negative sera are classified and analysed according to the endocrine pathology but especially thyroid disorders and the positive thyroid disease are grouped by low, high and very high Tgl-AAbs titres and by Tgl-precipitin positive. Our results are rather similar to those reported for endocrine collectivities in other countries. The technical and methodological sources of some discrepancies between the laboratory Tgl-AAbs results and the clinical symptoms and/or anatomo-pathologic results are commented as well as some of the future perspectives of the laboratory investigation of the thyroid autoimmune diseases. Concluding, a strategy schema for a possible immunogram is presented.

Autoantibodies↗

Study on the innocuity of the hypophyseal human growth hormone.

The hypophyseal human growth hormone (hGH), a Raben type laboratory preparation, was re-evaluated as regards its innocuity for therapeutic use. Besides the usual control tests recommended by the Romanian Pharmacopoeia, the contamination of the hGH for clinical use with acute and slow viruses, was investigated taking into account the withdrawal of this hormone in many developed countries. The contamination was absent both with acute viruses as resulted from hemadsorption on cell cultures and counterimmunoelectrophoresis, and with slow viruses as observed from a two year-follow up of guinea pigs injected intracerebrally with the hGH preparation. Further, the content of the growth hormone itself as well as the contamination degree with other pituitary hormones was examined. The hGH-RIA content was 2.23 +/- 0.13 IU/mg (means +/- SEM), range: 1.38-2.80 IU/mg (1st International Standard hGH 80/505-1982). The prolactin contamination assessed by RIA was 187.34 +/- 37.66 ng/mg hGH, range: 28.44-385.20 ng (International Standard WHO: 80/541). The LH and FSH contamination as quantified by the Isocommerz (DDR) RIA kits was with two orders of magnitude lower than 10 IU-LH/IU-hGH, the upper LH contamination limit considered as acceptable. Moreover, the proportion of the large molecular forms in the lyophilized hGH preparation was investigated by polyacrylamide gel electrophoresis. Corroborating the data obtained by these control tests with our previous experience on 149 pituitary dwarfs treated with this hGH preparation during the interval 1964-1984, resulted minor risks of some dangerous side effects of hGH administration in children with growth hormone deficiency by possible contamination with pathogenic agents or with other disturbing hormones.

Child↗

Growth deficiency with high circulating growth hormone levels: the insulin stimulation test in 39 children.

Thirty nine patients with abnormal high basal hGH levels were selected and analysed as a part of a retrospective study of the results of 1,500 insulin stimulation tests (IST), applied in children and adolescents with growth deficiency. Their height, weight, and bone age were lower than their corresponding chronological age. Both in girls and in boys groups, responders and nonresponders subgroups were detected as judging by the results of the secretagogue action of insulin on hGH. The hGH basal levels were 43.88 +/- 18.27 microU/ml (X +/- SD) in boys (no = 22) and 56.61 +/- 35.21 microU/ml in girls (no = 17). It is to be noted that the hGH nonresponder group had deeper hypoglycemia at 30 minutes post-insulin injection than the responder group: 53.6 +/- 13.0 mg/100 ml (X +/- SD) vs 66.0 +/- 11.5 mg/100 ml respectively (p less than 0.01). Two siblings, a girl and a boy, had the highest basal and stimulated hGH, either during the IST or starvation. One of them, the boy, during the starvation test, had a paradoxical fall of about two orders of magnitude of the serum hGH 4 hr after basal sample collection. These two siblings are similar to the familial Laron type dwarfism. The possible mechanisms of growth deficiency in children with constant high but variable hGH values are discussed, as well as the aspects concerning the therapeutic ways to improve their linear growth.

Adolescent↗

Immunohistochemistry of thyroid hormones as a functional parameter in thyroid pathology.

The authors study by means of immunoperoxidase method the pattern of thyroglobulin, triiodothyronine and thyroxine distribution in 58 cases of thyroid disorders: 15 euthyroid goiters, 10 Graves' disease, 7 Hashimoto's thyroiditis, 11 folliculo-papillary carcinomas (6 primary tumors and 5 lymph node metastases), 8 follicular carcinomas, 4 anaplastic carcinomas and 3 medullary carcinomas. Thyroglobulin, triiodothyronine and thyroxine were present in most of the thyroid disorders, excepting anaplastic and medullary carcinomas. Thyroglobulin and thyroxine were localized both in the follicular epithelium and in the colloid, whereas triiodothyronine was present especially in the follicular cells. The thyroid hormones distribution in benign lesions is rather similar. In carcinomas, the pattern of thyroglobulin, triiodothyronine and thyroxine is more heterogeneous, but generally the triiodothyronine distribution is similar to that of thyroglobulin. In some carcinomas, triiodothyronine and thyroxine showed a weak or negative immunostaining. The immunoperoxidase method is a valuable tool in the study of functional disturbances in the thyroid pathology and in the diagnosis of thyroid carcinoma metastases as well. Positive thyroid hormones staining clearly indicates the thyroid origin of metastases.

Histocytochemistry↗

The assessment of the dopaminergic tonus by urinary determinations of homovanillic acid (HVA) and dihydroxyphenylacetic acid (DOPAC) in normal, obese and GH-deficient short children.

In order to assess the dopaminergic tonus, urinary determinations of HVA and DOPAC and also of noradrenaline (NA), adrenaline (A), and methoxyhydroxyphenylglycol (MHPG) were performed in 86 obese children, 11 growth hormone (GH)-deficient short children and also in 40 control children. Part of the obese patients were subjected to a low carbohydrate, low calorie diet and also to short-term (9-14 days) courses of diethylpropion (DEP) 50 mg/day, meclofenoxate (MEC) 100 mg/day and thyroid extract (THE) 1-2 mg/kg/day. The GH-deficient patients received only THE in substitutive (5-10 mg/kg/day) doses. Significative correlations between DOPAC and age, weight and height were found in controls. In the obese group a significantly increased mean level of HVA was found (1.45 +/- 0.09 mg/24 h vs 1.15 +/- 0.10 in controls). The excretion of DOPAC was slightly greater but far from significance. There was also a significant decrease of HVA but not DOPAC in the DEP-treated obese. The rest of the drugs and the diet alone were not effective in any way. Normal levels in all metabolites except NA and A were found in GH-deficient short children. The therapy with thyroid extract did not alter the excretion levels. These findings indicate that in infantile obesity the dopaminergic tonus is somewhat increased but its pathophysiological significance is doubtful. In GH-deficient short children of standard appearance the dopaminergic tonus seems to be undistinguishable from normal.

3,4-Dihydroxyphenylacetic Acid↗

The serum osteocalcin levels in patients with thyroid diseases.

The mechanism of bone, calcium, phosphorus and proteins abnormalities observed in hyperthyroidism is rather complex and as yet not wholly understood. Increased serum osteocalcin was recently reported in hyperthyroid patients and its decrease after 4-8 months of treatment. Osteocalcin was measured by RIA in the sera of 211 women and 18 men with thyroid diseases. The patients were divided into 3 groups according to diagnosis: I. polynodular goitre and subacute thyroiditis (59 women, 5 men); II. Graves' disease (70 women, 3 men) and III. thyroid cancer, after treatment by surgery and 131I (82 women, 10 men). The osteocalcin levels in the sera of these patients were: 2.97 +/- 2.63 ng/ml (mean +/- SD) for the women and 3.56 +/- 2.10 ng/ml for the men in the 1st group; 16.31 +/- 11.34 ng/ml for the women and 12.75 +/- 6.09 ng/ml for the man in the IInd group and, 1.01 +/- 0.60 ng/ml for the women and 0.78 +/- 0.46 ng/ml for the men in the IIIrd group. No differences were found between the osteocalcin concentrations in the hyperthyroid female patients treated with antithyroid drugs (no = 58) and the non-treated hyperthyroid women (no = 12): 16.22 +/- 11.40 ng/ml vs 16.74 +/- +/- 11.53 ng/ml. These data suggest that bone resorption stimulated by endogenous thyroid-hormones is a rather resistant processus, persisting even after 6-8 mos of associated anti-thyroid therapy. Further are analyzed the possible causes of the subnormal osteocalcin levels observed in patients with thyroid cancer treated by surgery and radioisotope, whose suppression therapy was discontinued 2-3 weeks before blood sampling.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Methods of isolation and purification of bovine and rat osteocalcin.

Measurement of osteocalcin (a bone protein containing gamma-carboxyglutamic acid, GLA-P) in the biological liquids and tissues is of interest for studying the mechanisms of bone diseases. It is also helpful in making a diagnosis and in following up the patients with diseases in which the osseous system is affected. Methods have been worked out for isolation and purification of osteocalcin from bovine and rat femur in order to use the purified substance as a starting material for developing radioimmunoassay (RIA) systems for each of these osteocalcins. The work went through the following stages: the processing of the femur bone, preparation of the 200 microns bone powder, demineralization of the powder, and concentration of the bone extract, purification of the extract by molecular exclusion chromatography on Sephadex G-100 and repurification to the product by ion exchanger chromatography in NaCl linear gradient, on DEAE Sephadex A-25. The purity of the substance obtained was tested by disk electrophoresis in polyacrylamide gel. The bovine and rat osteocalcins obtained had the adequate purity for being used as RIA reagents.

1-Carboxyglutamic Acid↗