Inhibitory effect of plasma obtained from hypophysectomized and control women on the assay of bioactive luteinizing hormone.
(1/266)
The purpose of this study was to determine the effect of components of female plasma on the value of bioactive luteinizing hormone (LH), especially in the presence of low immunological LH value. Using both an immunoradiometric assay (IRMA) and rat Leydig cell bioassay, immunoreactive (I) and bioactive (B) LH were assessed in plasma collected from women during a gonadotrophin releasing hormone (GnRH) test performed on day 7 of a spontaneous cycle. Two modes of response to an acute administration of GnRH were defined: normal production of gonadotrophins (group I) and excessive secretion (group II) associated with a significant difference in the B/I-LH ratio between the two groups. The B/I-LH ratio did not vary with sampling time during the test in either group. The addition of LH-free plasma collected from hypophysectomized women caused a 30% decrease in testosterone production compared to control values (in the presence or absence of hLH standard). A partial restoration of testosterone production was observed if plasma was first treated with PEG 12%. The inhibitory factor(s) was also present in plasma from ovulatory women, even after treatment by an antibody against the entire LH molecule. The effect of normal (A) or low I-LH plasma (B) on testosterone production varied strongly according to the plasma volume added to the bioassay, as well as to plasma treatments. Diethylether treatment caused a 50% decrease in testosterone secretion for plasma B (but not for A) whereas a diminution of the steroidogenesis is observed after a PEG treatment of plasma A (but not for B), suggesting that different inhibitory factors are present in plasmas A and B. Therefore the LH bioactivity measured in the rat Leydig cell assay, in terms of testosterone output, seems to represent a balance between the LH molecule and the presence of inhibitory factors in the plasma. (+info)
Early pregnancy human chorionic gonadotropin (hCG) isoforms measured by an immunometric assay for choriocarcinoma-like hCG.
(2/266)
Human chorionic gonadotropin (hCG) exhibits molecular heterogeneity in both its protein and carbohydrate moieties. This communication describes changes in hCG isoforms detected directly in clinical samples. These isoforms, quantified in blood or urine specimens, show a progression of change throughout normal pregnancy. Early pregnancy produces a type of hCG that resembles, in terms of immunoreactivity, a major form of hCG excreted in choriocarcinoma. The isoforms predominate for the first 5-6 weeks of gestation and then diminish, being replaced with the hCG isoforms which predominate throughout the remainder of pregnancy. The alteration in hCG isoform content occurs in both blood and urine. The progression of isoforms is best delineated by calculating the change in the ratio of the two forms, as many hCG assays either do not detect or fail to discriminate among these isoforms. An analogous pattern of hCG isoforms was observed in patients with in vitro fertilization pregnancies. hCG isolated from the pituitary displayed binding characteristics similar to those of the hCG derived from normal pregnancy urine. The early pregnancy hCG isoforms appear to have a differential expression in normal pregnancy as opposed to pregnancies which will not carry to term, suggesting that a determination of the relative balance of hCG isoforms may have diagnostic application in predicting pregnancy outcome. (+info)
A new human chromogranin A (CgA) immunoradiometric assay involving monoclonal antibodies raised against the unprocessed central domain (145-245).
(3/266)
Chromogranin A (CgA), a major protein of chromaffin granules, has been described as a potential marker for neuroendocrine tumours. Because of an extensive proteolysis which leads to a large heterogeneity of circulating fragments, its presence in blood has been assessed in most cases either by competitive immunoassays or with polyclonal antibodies. In the present study, 24 monoclonal antibodies were raised against native or recombinant human CgA. Their mapping with proteolytic peptides showed that they defined eight distinct epitopic groups which spanned two-thirds of the C-terminal part of human CgA. All monoclonal antibodies were tested by pair and compared with a reference radioimmunoassay (RIA) involving CGS06, one of the monoclonal antibodies against the 198-245 sequence. It appears that CgA C-terminal end seems to be highly affected by proteolysis and the association of C-terminal and median-part monoclonal antibodies is inadequate for total CgA assessment. Our new immunoradiometric assay involves two monoclonal antibodies, whose contiguous epitopes lie within the median 145-245 sequence. This assay allows a sensitive detection of total human CgA and correlates well with RIA because dibasic cleavage sites present in the central domain do not seem to be affected by degradation. It has been proved to be efficient in measuring CgA levels in patients with neuroendocrine tumours. (+info)
Elevated plasma brain natriuretic peptide levels in chronic respiratory failure with cor pulmonale.
(4/266)
Elevated plasma brain natriuretic peptide (BNP) levels have been described in patients with congestive heart failure and acute myocardial infarction. We measured plasma BNP levels in patients with chronic respiratory failure to evaluate the correlation between plasma BNP levels and pulmonary haemodynamics. Plasma BNP levels were measured in 28 patients with chronic respiratory failure accompanied by three underlying diseases [14 with chronic obstructive pulmonary disease (COPD), seven with sequelae of pulmonary tuberculosis (sequelae Tbc) and seven with diffuse panbronchiolitis (DPB)] by immunoradiometric assay methods (IRMA). Twenty-one of 28 patients had already received oxygen supplementation and 16 of 21 patients were treated as outpatients with home oxygen therapy. Plasma BNP levels were significantly elevated in patients with chronic respiratory failure complicated by cor pulmonale (81.5 +/- 13.1 pg ml-1) compared to patients without cor pulmonale (13.3 +/- 2.7 pg ml-1, P < 0.001). As controls, plasma BNP levels in 10 patients with primary lung cancer were studied, and the results (3.5 +/- 1.0 pg ml-1) were not significantly different from those of patients with chronic respiratory failure without cor pulmonale. Plasma BNP levels in 12 healthy subjects were also studied, and the results (7.2 +/- 1.0 pg ml-1) were not significantly different from those of the control subjects. Plasma BNP levels showed a weak linear correlation with systolic pulmonary arterial blood pressure, estimated by Doppler echocardiography (r = 0.43; P = 0.068), but there was no significant correlation between BNP levels and the degree of hypoxaemia (r = 0.30; P = 0.138). Plasma atrial natriuretic peptide (ANP) levels in patients with chronic respiratory failure were also measured using the same samples. Plasma ANP levels were also significantly elevated in patients with chronic respiratory failure complicated by cor pulmonale (80.8 +/- 12.1 pg ml-1) compared to patients without cor pulmonale (26.1 +/- 4.4 pg ml-1, P = 0.003). A significant correlation was found between plasma BNP and ANP levels (r = 0.68; P < 0.001). Our results suggest that the plasma BNP or ANP level may be a useful indicator for detecting the presence of cor pulmonale in patients with chronic respiratory failure. (+info)
Incidental detection of familial medullary thyroid carcinoma by calcitonin screening for nodular thyroid disease.
(5/266)
Serum calcitonin screening has recently been found to be a useful supplement to fine-needle aspiration biopsy, ultrasound and radionuclide imaging in the evaluation of thyroid nodules. We describe a case where introduction of routine calcitonin screening in nodular thyroid disease led to the detection of a family with medullary thyroid carcinoma. The benefits and problems of basal and stimulated serum calcitonin testing and ret-proto-oncogene mutation studies are exemplified and we discuss the appropriate use and interpretation of these tests. We conclude that routine basal serum calcitonin measurement in nodular thyroid disease and thoughtful use of ret-mutation analysis is cost-effective in detecting medullary thyroid carcinoma and multiple endocrine neoplasia type II. (+info)
Abnormalities of hypothalamic-pituitary-adrenal and hypothalamic-somatotrophic axes in Fawn-Hooded rats.
(6/266)
Fawn-Hooded (FH) rats show central and peripheral abnormalities in serotoninergic functions and have attracted attention as an animal model of some pathologies, including depression and hypertension. In addition, these rats show a reduced growth rate. As the hypothalamic-pituitary-adrenal (HPA) axis has been implicated in both depression and hypertension, and the hypothalamic-somatotrophic (HSM) axis has a major role in growth, these two endocrine axes were characterised in FH rats as compared with outbred Sprague-Dawley (SD) rats in basal conditions. FH rats showed normal serum ACTH and corticosterone concentrations, but reduced serum corticosterone binding capacity. At a central level, normal expression of mRNA for glucocorticoid type II receptors in the hippocampal formation and mRNA for corticotrophin-releasing factor (CRF) in the paraventricular nucleus of the hypothalamus were observed in FH rats, whereas expression of mRNA for CRF in the central nucleus of the amygdala was enhanced compared with the expression in SD rats. Serum GH concentrations were normal in FH rats, IGF-I tended to be lower, and mRNA for somatostatin (SRIF) in the periventricular nucleus of the hypothalamus was significantly lower in FH rats than in SD rats. The reduced SRIF gene expression in rats with normal or slightly reduced GH and IGF-I, respectively, might be secondary to a defective central and peripheral response to IGF-I, compatible with the reduced growth of FH rats. The present results suggest that FH rats have abnormalities in both HPA and HSM axes that might be related to some of their physiopathological characteristics. (+info)
Continuous s.c. infusion rather than twice-daily injections of IGF-I more effectively increases serum IGF binding protein-3 in female monkeys.
(7/266)
OBJECTIVE: In order to better understand how the IGF-I axis is affected by exogenous IGF-I, this study compared the effects of a constant s.c. infusion of IGF-I with that of twice-daily injections of IGF-I in young adult female rhesus monkeys. Clinical studies suggest that circulating concentrations of insulin-like growth factor binding protein-3 (IGFBP-3) are decreased or unaffected by IGF-I administration, whereas acute increases in IGF-I may increase serum IGFBP-1. However, studies in monkeys indicate that acute or continuous infusion of IGF-I effectively increases serum IGFBP-3. DESIGN AND METHODS: Female monkeys were studied for 5 days with no IGF-I supplementation (baseline) and for 5 days of IGF-I treatment by either constant infusion (120 microg/kg per day s.c., n = 5) or twice-daily injections of IGF-I (60 microg/kg per injection s.c., n = 5). Serum samples were collected daily at 0800 h and at 0800, 0900, 1100, 1500, and 2000 h on days 1 and 4 for each condition. Samples were assayed for IGF-I, IGFBPs-1 and -3, insulin, and glucose. RESULTS: Serum IGF-I was consistently increased above baseline within 24 h of the initiation of constant infusion, but was delayed until the second day of treatment in the injection group. Serum IGFBP-3 followed the pattern of IGF-I, with concentrations increased by day 1 during constant infusion and by day 2 during intermittent injections. Although both treatments effectively increased serum IGFBP-3, the increase was greater during constant infusion (31% above baseline) compared with injection (17%). Immunoblotting revealed that the constant infusion of IGF-I resulted in quantitatively more lower-molecular-mass fragments of IGFBP-3 than were observed during baseline or intermittent injections. Size-exclusion chromatography and ultrafiltration indicated that most IGFBP-3 was found in the ternary complex, with a greater percentage found in the ternary complex during baseline (90%) than during constant infusion (86%) or intermittent injections of IGF-I (87%). In contrast, serum concentrations of IGFBP-1 were increased on day 1 of both treatments, but declined towards baseline values as treatment progressed. Serum concentrations of insulin and glucose were unaffected by either mode of IGF-I treatment. Serum concentrations of IGF-I and IGFBP-3 were increased within 3h of the injection, before declining towards the pre-injection level. In contrast, the daily pattern of serum hormone concentrations was similar between the baseline condition and during constant infusion of IGF-I. Although higher during the treatment phase, serum IGF-I and IGFBP-3 concentrations decreased significantly from 0800 h until the afternoon meal, reaching a nadir in the evening before increasing again the next morning. Serum insulin decreased also after the morning meal and increased significantly immediately after the afternoon meal. Although serum IGFBP-1 also decreased initially after the morning meal, concentrations reached a peak before the afternoon meal as serum insulin reached its nadir. CONCLUSION: The results of the present analysis indicate that the constant infusion of IGF-I more effectively sustains serum concentrations of IGF-I and IGFBP-3 than do twice-daily injections. Although the percentage of IGF-I and IGFBP-3 in the ternary complex was similar during both treatments, the constant infusion regimen produced lower-molecular-mass fragments of IGFBP-3. In addition, serum IGF-I and IGFBP-3 appeared to be regulated diurnally, even during IGF-I infusion, whereas IGFBP-1 and insulin were affected by the timing of food intake. Taken together, these data suggest that, in the monkey, IGFBP-3 is regulated by factors in addition to GH, and that IGF-I can affect its own bioavailability by increasing circulating concentrations of IGFBP-3. (+info)
M1/MUC5AC mucin released by human airways in vitro.
(8/266)
A series of monoclonal antibodies which bind to a mucin known as M1 (anti-M1 MAbs) have also been shown to detect the product of the human gene MUC5AC. The aim of this investigation was to determine the concentration of the M1 mucin in the surface epithelium of human bronchial preparations by means of immunohistochemistry and in the bronchial fluid derived from human airways by means of an immunoradiometric assay. Human bronchial ring preparations from the resection material of 20 patients were challenged with methacholine, leukotriene D4, or anti-immunoglobulin E. Experiments were performed in preparations with an intact epithelium as well as in tissues in which the epithelium had been mechanically removed. The anti-M1 MAbs stained the goblet cells in the epithelium intensely and there was also light and less uniform staining in the submucosa. The M1/MUC5AC mucin in the fluids secreted by the bronchial preparations was not modified during either the experimental protocol or stimulation with the different secretagogues. However, in preparations in which the epithelium had been removed, there was a significant reduction in the amount of M1/MUC5AC mucin detected. These data suggest that the M1/MUC5AC mucin detected in the biological fluids produced by human airways in vitro may be released constantly, and principally from the goblet cells in the epithelial layer. (+info)