Detection of autoantibodies against the pituitary-specific proteins in patients with lymphocytic hypophysitis.
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OBJECTIVE: Several reports have described antipituitary antibodies by immunofluorescent or immunoblotting methods in patients with lymphocytic hypophysitis. However, with the exception of the pituitary hormones, individual antigens specific for the pituitary gland have not been studied. To understand the pathogenesis of lymphocytic hypophysitis and to diagnose this disease efficiently, we studied the presence of autoantibodies against three pituitary-specific proteins, GH and two novel pituitary-specific proteins, namely, pituitary gland specific factor 1a (PGSF1a) and PGSF2. DESIGN: Seventeen patients with lymphocytic hypophysitis, all of whom had pituitary enlargement (5 with lymphocytic adenohypophysitis and 12 with lymphocytic infundibuloneurohypophysitis, including 3 of the latter group proven by biopsy), and 14 patients with hypopituitarism without pituitary enlargement (10 with isolated ACTH deficiency and 4 with idiopathic TSH deficiency) were studied, and compared with 11 patients with non-functioning pituitary macroadenoma, 31 patients with other autoimmune diseases, and 36 healthy controls. METHODS: The presence of each antibody was studied by radioligand assay using recombinant human (35)S-labeled protein. RESULTS: Three (18%) patients with lymphocytic hypophysitis having pituitary enlargement, five (36%) patients with hypopituitarism without pituitary enlargement and three (9.7%) patients with other autoimmune diseases were positive for one or more of the antibodies studied. CONCLUSIONS: Anti-human GH, anti-PGSF1a, and anti-PGSF2 antibodies were detected in patients with lymphocytic hypophysitis and other hypopituitarism, but were not detected in patients with non-functioning pituitary macroadenoma. Detection of these antibodies may be useful for the diagnosis of lymphocytic hypophysitis. (+info)
A novel dual radio- and stable-isotope method for measuring calcium absorption in humans: comparison with the whole-body radioisotope retention method.
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BACKGROUND: Dietary calcium absorption can be determined only with the use of isotope techniques. Currently used isotope techniques require exclusive equipment or are not true tracer approaches. OBJECTIVE: The objective was to compare a dual-isotope method combining radioisotopes and stable isotopes with a whole-body radioisotope retention method for measuring calcium absorption. DESIGN: Seven healthy adults aged 21-27 y consumed a test meal containing 63 +/- 14 (macro x +/- SD) mg Ca together with a water solution of (47)Ca (0.11 MBq). One hour after ingestion, 18 mg (44)Ca was administered intravenously. All feces and urine were collected for 5 and 6 d, respectively. Calcium absorption was estimated from whole-body retention of the radioisotope 12 times over 3 wk after ingestion and from the excretion of (47)Ca and (44)Ca in a 24-h urine sample collected on day 2. (44)Ca in urine was determined by inductively coupled plasma mass spectrometry. RESULTS: Mean (+/- SD) calcium absorption was 75 +/- 9% with the dual-isotope method and was 74 +/- 8% with the whole-body radioisotope retention method. There was a high degree of agreement between the methods. CONCLUSION: The dual-isotope method is a valid approach for measuring calcium absorption from a single meal. (+info)
Comparison of anthropometric equations for estimation of total body water in peritoneal dialysis patients.
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BACKGROUND: Several formulae exist for estimating total body water (TBW). We aimed to assess their validity in peritoneal dialysis patients by comparison with TBW estimated by deuterium oxide dilution (TBW(D)). METHODS: We compared the equations of Chertow (TBW(Cher)), Chumlea (TBW(Chum)), Hume and Weyers (TBW(HW)), Johansson (TBW(J)), Lee (TBW(L)), Watson (TBW(W)) and TBW as 58% of body weight (TBW(0.58Wt)) with TBW(D) in 31 peritoneal dialysis (PD) patients and 32 controls. Estimates were compared with TBW(D) using Bland and Altman comparison. Extracellular water (ECW) was also estimated by sodium bromide dilution. RESULTS: In PD patients, mean TBW(D) was 35.04 (SD 7.84) l. Estimates were greater for TBW(Cher), TBW(Chum), TBW(HW), TBW(J) and TBW(0.58Wt). Mean TBW(L) and TBW(W) did not differ from TBW(D). Ninety-five percent limits of agreement (LOA) compared with TBW(D) (as a percentage of the mean) were similar for all of the different equations in PD patients (between +/-15.4 and +/-17.3%) except TBW(0.58Wt), which was far greater (+/-26.4%). In controls, mean TBW(D) was 37.03 (SD 6.63) l. Estimates were greater for TBW(Cher), TBW(Chum), TBW(HW), TBW(J) and TBW(0.58Wt). Mean TBW(L) and TBW(W) did not differ from TBW(D). Ninety-five percent LOA compared with TBW(D) (as a percentage of the mean) were similar for all equations in the controls, and closer than in PD patients (between +/-9.1 and +/-11.5%) except TBW(0.58Wt), which was again far greater than the other equations (+/-28.1%). TBW(HW) - TBW(D) correlated with mean TBW (r=-0.412, P<0.05 in PD and r=-0.383, P<0.05 in controls). TBW(W) - TBW(D) (r=-0.539, P<0.005) correlated with mean TBW in PD. TBW(0.58Wt) - TBW(D) correlated with body mass index (BMI) (r=0.624, P<0.0001 in PD and r=0.829, P<0.0001 in controls) and ECW/TBW (r=0.406, P<0.05 in PD and r=0.411, P<0.02 in controls). CONCLUSIONS: Predictive equations were less accurate in PD than controls. TBW(0.58Wt) was most inaccurate, with systematic overestimation of TBW with increasing BMI and ECW/TBW. There were no differences in LOA with TBW(D) for the other equations within each group. (+info)
Assessment of fluid status in peritoneal dialysis patients.
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OBJECTIVES: To assess the influence of abnormalities in fluid status and body composition on agreement between multifrequency bioimpedance analysis (MF-BIA), segmental BIA (sigmaBIA), the Watson formula, and tracer dilution techniques. DESIGN: Cross-sectional. SETTING: Multicenter. PATIENTS: 40 patients (29 males, 11 females) on peritoneal dialysis (PD). MAIN OUTCOME MEASURES: Agreement between the various techniques used to assess total body water (TBW) [MF-BIA, deuterium oxide (D2O), and the Watson formula] and extracellular water (ECW) [MF-BIA, bromide dilution (NaBr), and sigmaBIA], also in relation to the relative magnitude of the body water compartments [ECW (NaBr):body weight (BW) and TBW (D2O):BW] and body composition (DEXA). Second, the relation between body water compartments with echocardiographic parameters. RESULTS: Wide limits of agreement were observed between tracer dilution techniques and MF-BIA [TBW (D2O - MF-BIA) 2.0 +/- 3.9 L; ECW (NaBr - MF-BIA) -2.8 +/- 3.9 L], which were related to the relative magnitude of the body water compartments: r = 0.70 for ECW and r = 0.40 for TBW. sigmaBIA did not improve the agreement [ECW (NaBr-sigmaBIA): 3.7 +/- 2.9 L]. Also, wide limits of agreement were observed between D2O and the Watson formula (-2.3 +/- 3.3 L). The difference between D2O and Watson was related to hydration state and to percentage of fat mass (r = 0.70 and r = -0.53, p < 0.05). Both ECW and TBW as assessed by BIA and tracer dilution were related to echocardiographic parameters. CONCLUSION: Wide limits of agreement were found between MF-BIA and sigmaBIA with dilution methods in PD patients, which were related to hydration state itself. The disagreement between the Watson formula and dilution methods was related to both hydration state and body composition. (+info)
Quantitative assessment of total body stores of vitamin A in adults with the use of a 3-d deuterated-retinol-dilution procedure.
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BACKGROUND: The conventional deuterated-retinol-dilution (DRD) technique provides a quantitative estimate of total body stores of vitamin A in humans. The procedure requires equilibration of serum deuterated retinol with nondeuterated retinol after administration of an oral dose of deuterated vitamin A. Equilibration takes approximately 3 wk to complete. OBJECTIVE: Our goal was to develop a predictive mathematical formula for quantitative assessment of total body stores of vitamin A in adults by using a procedure that takes less time to perform because serum isotope equilibration is not required, so that blood drawing can be done 3 d, instead of approximately 3 wk, after isotope dosing. DESIGN: Ratios of serum deuterated to nondeuterated retinol (D:H retinol) were determined in Filipino adults (n = 68) 3 and 20 d after an oral dose of 0.015 mmol [(2)H(4)]retinyl acetate and in Guatemalan adults (n = 15) 3 and 21 d after a 0.030-mmol dose. D:H retinol values 20 or 21 d after the isotope dose were used in a mathematical formula to obtain quantitative estimates of total body stores of vitamin A that were then correlated with serum D:H retinol values 3 d after the isotope dose. RESULTS: The relation between these variables was nonlinear and was described by the following equation: total body stores of vitamin A (in mmol retinol) = 0.00468 x 10(37(isotope dose in mmol))/D:H retinol in serum 3 d after the isotope dose. CONCLUSION: A 3-d DRD technique could be used for quantitative assessment of total body stores of vitamin A; this technique takes less time than does the conventional DRD technique. (+info)
Direct measurement of glycine-extended adrenomedullin in plasma and tissue using an ultrasensitive immune complex transfer enzyme immunoassay in rats.
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The mature form of the vasodilator peptide adrenomedullin (AM-m) is synthesized from a glycine-extended precursor (AM-Gly) by enzymatic amidation. We have developed a highly sensitive enzyme immunoassay (Immune Complex Transfer Enzyme Immunoassay; ICTEIA) that enables us to measure levels of AM-Gly in plasma and tissue directly. The detection limit of this assay is 1 amol/assay, and the intra- and inter-assay precision are 4.5-14.1% and 9.9-20.5%, respectively. Dilution curves for plasma samples showed good linearity, and the analytical recovery was 107-116.6%. Using ICTEIA, we determined that the plasma concentration of immunoreactive AM-Gly is substantially higher than that of AM-m (5.22 +/- 2.56 vs. 1.21 +/- 0.79 fmol/ml). In contrast, levels of AM-Gly were much lower than those of AM-m in the lung, heart, kidney, adrenal gland and liver. We also evaluated AM-Gly and AM-m levels in rats in a morbid state induced by intraperitoneal administration of lipopolysaccharide (LPS). In most tissues, levels of AM-m and AM-Gly were both increased by LPS; however, AM-Gly/AM-m ratios were not significantly affected, which suggests that AM-Gly is rapidly converted to AM-m in tissue. (+info)
The role of low affinity antibody in immune complex disease. The quantity of anti-DNA antibodies in NZB/W F1 hybrid mice.
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The level and avidity of anti-DNA antibody in the serum of New Zealand Black/White (NZB/W F1) hybrid mice has been determined. The results show that there is an age and sex-related variation in the avidity of this antibody. In mice of both sexes, the avidity of circulating anti-DNA antibody increases up to 5 months of age; thereafter the avidity falls with increasing age. These variations are more marked in males, but female mice consistently have lower avidity anti-DNA antibody than males. Thus the time of onset, time course and severity of the murine lupus syndrome in NZB/W F1 mice are associated with the presence of increasing levels of low avidity anti-DNA antibody in the serum. These results are discussed in the context of the possible role of low avidity antibody in immune complex disease. (+info)
Comparison of stable-isotope-tracer methods for the determination of magnesium absorption in humans.
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BACKGROUND: The double-labeling (DL) method for determining magnesium absorption is less cumbersome than is the fecal monitoring method, which has been used most often, but it has not been validated. OBJECTIVE: The aim of this study was to compare methods and several sampling protocols for determining magnesium absorption to establish a simple and reliable alternative to the fecal monitoring approach. Fecal monitoring was used as the standard against which the DL methods based on urine data (DLU), plasma data (DLP), and plasma kinetics with the use of a deconvolution analysis (DP) were compared. DESIGN: Six healthy adult men received 70 mg (26)Mg orally and 30 mg (25)Mg intravenously. Multiple blood samples and complete urine and fecal samples were collected over 12 d. Stable-isotope ratios were determined by inductively coupled plasma mass spectrometry. RESULTS: Results from DLU were not significantly different from the fecal monitoring reference value (0.48 +/- 0.05; +/- SD) when based on 3-d urine pools from 72 to 144 h (0.54 +/- 0.04) and when based on the 24-h urine pools from 48 to 72 h (0.49 +/- 0.06), 72 to 96 h (0.51 +/- 0.11), and 96 to 120 h (0.50 +/- 0.06). Results with the DLP method 72 h after isotope administration also compared well with those with the fecal monitoring method (0.54 +/- 0.09). Magnesium absorption was 0.47 +/- 0.06 with the DP method, which also agreed with the fecal monitoring value. CONCLUSIONS: The DL methods are an alternative to fecal monitoring when applied within the appropriate time intervals. Therefore, DLU-the simplest and least invasive approach-is recommended for determining magnesium absorption. (+info)