Detergent effects of kinetic properties of (Na+ +K+)-ATPase from kidney membranes.

Studies on (Na+ +K+)-ATPase generally employ detergents such as SDS and deoxycholate. Under such conditions, the purified enzyme possesses high specific activity. The (Na+ +K+)-ATPase from kidney membranes was unmasked by deoxycholate and SDS as described by Jlrgensen and its kinetic properties were studied. The results suggest that these detergents induce some irreversible alterations in the kinetic properties of the native enzyme. Another detergent, saponin, unmasked the (Na+ +K+)-ATPase as effectively as did SDS, but it seems to affect the kinetic properties of the native enzyme to a lesser extent.

Diagnosis of medullary carcinoma of the thyroid (MCT) by calcitonin assay using monoclonal antibodies: criteria for the pentagastrin stimulation test in hereditary MCT.

A new calcitonin (CT) immunoradiometric assay, using anti-11-7 and anti-24-32 CT fragment monoclonal antibodies was evaluated and compared to classical RIA. The sensitivity was 2.5 ng/L, the normal basal level (n = 83) was lower than 10 ng/L, the response to pentagastrin stimulation in control subjects was absent in nine and between 10-30 ng/L in nine others. (mean, 15.4). In patients with renal failure the basal level was increased between 10-52 ng/L. In patients with medullary thyroid carcinoma (MTC; n = 28), the basal level was between 189-28,900 ng/L. A pentagastrin test was performed as screening for familial MTC in eight patients with confirmed MTC at subsequent surgery; the calcitonin peak was equal or greater than 38 ng/L. Large differences exist between CT levels measured by RIA and immunoradiometric assay. The latter method provides a greater sensitivity to pentagastrin test and allows a better identification of microcarcinoma in hereditary cases of MTC.

Pentagastrin stimulation test and early diagnosis of medullary thyroid carcinoma using an immunoradiometric assay of calcitonin: comparison with genetic screening in hereditary medullary thyroid carcinoma.

A pentagastrin stimulation test using a calcitonin (CT) immunoradiometric assay was performed in 38 healthy subjects and in the following 50 patients: 25 subjects from families with at least 2 known cases of medullary thyroid carcinoma (MTC), 11 subjects from families with apparently sporadic MTC, 2 pheochromocytoma carriers, 1 primary hyperparathyroidism, 8 patients with thyroid nodules, and 3 others with various diseases. In healthy volunteers, basal CT values were always less than 10 ng/L; the response to pentagastrin was below 30 ng/L for 36, and for the remaining 2, the peaks reached 30 for 1 subject and 48 ng/L for the other. The pentagastrin-stimulated CT peak was above 30 ng/L in each of the patients presented here, and all were thyroidectomized. In screening the 25 relatives of patients with familial MTC, a CT peak level over 30 ng/L was constantly associated with C-cell disease (23 cases of MTC and 2 of C-cell hyperplasia). A response to pentagastrin above 100 ng/L was observed in 15 patients among the 23 with MTC. In 8 of the 10 patients with a peak CT level between 30-100 ng/L, pathological examination showed a MTC; the other 2 had C-cell hyperplasia and a negative linkage study analysis. In the 25 other patients in the study without familial MTC, the pentagastrin-stimulated CT level was over 100 ng/L in 11 of the 14 subjects with MTC. The abnormal CT response to pentagastrin, which has been used as a criterion for surgical treatment, is currently determined by an immunoradiometric assay. Our study confirms that subjects with a peak CT level above 100 ng/L should undergo surgery whatever the reason for the test. In the context of inherited MTC, our results suggest that for patients with a CT peak level between 30-100 ng/L, surgery may actually be postponed when their probability of being gene carriers is low. Recent progress with the characterization of specific mutations in affected individuals will make familial screening much easier in the next few months.

Transient hypoparathyroidism induced by synthetic human parathyroid hormone-(1-34) treatment.

Daily injections of low doses of a synthetic fragment of human PTH [hPTH-(1-34) have increased iliac trabecular bone volume when used in the treatment of osteoporosis. In approximately 50 patients no major side-effects had occurred. However, during daily sc 100-micrograms injections of the peptide, one patient repeatedly developed parathyroid hypofunction which resolved each time treatment was stopped. Specific immunoglobulin G (IgG) antibodies binding [125I]hPTH-(1-34) were identified in the patient's serum, and positive immunohistochemical reactions were obtained when bovine parathyroid sections were exposed to the patient's IgG. After adsorption with PTH, the patient's IgG, free of anti-PTH antibodies, reacted with renal cell membranes, as demonstrated by indirect immunofluorescence and blocked renal PTH-dependent adenylate-cyclase activation in vitro. These results support the hypothesis that anti-PTH receptor as well as anti-PTH antibodies were generated during hPTH-(1-34) treatment, which led to the development of hypoparathyroidism when their titers were high.

[Use of SDS and saponin detergents for the demonstration and purification of (Na+K+)ATPase in sheep kidney]. / A propos de l'utilisation des détergents SDS et saponine pour le démasquage et la purification de la (Na+K+)ATPase de rein de mouton.

Incubation of membrane fragments from sheep kidney outer medulla in detergents such as SDS or saponin revealed increased specific (NA+) ATPase activity. Measurement of enzyme phosphorylation from [gamma 32P] ATP showed irreversible alteration of EP to (Na+) ATPase activity ratio when SDS is used as unmasking agent. These results were found with unmasked and purified enzyme.

Noninvasive assessment of the infarct-related coronary artery blood flow velocity using phase-contrast magnetic resonance imaging after coronary angioplasty.

This study assesses infarct-related coronary artery blood flow velocity using phase-contrast magnetic resonance imaging (MRI) in patients with reperfused acute myocardial infarction (AMI) and compares these results with flow measurements obtained nonsimultaneously by intracoronary Doppler ultrasound. MRI examination was performed in 17 patients with AMI within 1 to 4 days (mean 2.5 days) after direct or rescue coronary angioplasty using a 0.014-in Doppler guidewire. MRI was performed on a 1.5-T clinical imager. The fast gradient echo segmented k-space phase-contrast pulse sequence was employed during breath-hold. The MRI and Doppler parameters of average peak velocity and maximum peak velocity were measured. Mean phase contrast MRI average peak velocity was 13.3+/-10.7 cm/s, and mean phase-contrast MRI maximum peak velocity was 27+/-16.6 cm/s. Mean Doppler average peak velocity was 17.1+/-5.1 cm/s, and mean Doppler maximum peak velocity was 35.5+/-10.1 cm/s. At the same anatomic levels, phase-contrast MRI average peak velocity correlated significantly to Doppler average peak velocity (r = 0.52; p<0.006) and Doppler maximum peak velocity (r = 0.42; p<0.03). Phase-contrast MRI velocity measurements were correlated with the same heterogeneity of Thrombolysis In Myocardial Infarction 3 flow velocity observed during Doppler examination. Thus, by comparing phase-contrast MRI with invasive intracoronary Doppler flow measurements, the measured MRI values showed significant correlation with Doppler data. Phase-contrast MRI has the potential to noninvasively quantify coronary flow velocity and to evaluate quality of reperfusion in patients with AMI after reperfused therapy.

MRI study of transient cerebral ischemia in the gerbil: interest of T2 mapping.

RATIONALE AND OBJECTIVES: The aim of this study was to evaluate the diagnostic use of MRI and, more precisely, the use of quantitative T2 imaging at 7 T for the early detection of neuronal cerebral alterations after transient ischemia in the gerbil. METHODS: One hundred forty-seven Mongolian gerbils were separated into four groups for which a bicarotid artery occlusion lasted for 4, 6, 8, or 10 minutes, respectively. The animals were scanned before carotid artery occlusion and at 3, 6, 10, 24, and 48 hours and 5 days after the ischemic incident. MR images were acquired on a Bruker Avance DRX300 mini-imaging system. RESULTS: Our results show that T2 mapping is able to localize brain damage induced by transient ischemia and to detect early perturbations in water content (as early as 6 hours after ischemia). CONCLUSIONS: T2 measurements in the striata are correlated with the severity of the ischemic incident, since the changes observed on the T2 images are directly proportional to the duration of occlusion.

Global left ventricular cardiac function: comparison between magnetic resonance imaging, radionuclide angiography, and contrast angiography.

RATIONALE AND OBJECTIVES: Cardiac magnetic resonance imaging (MRI) has been shown to be a robust and noninvasive method to assess left ventricular (LV) cardiac function. This study sought to assess volumes and mass calculated with MRI using fast techniques for acquisition and postprocessing, and to compare results in terms of cost-effectiveness with those of radionuclide angiography (RNA) or contrast angiography (CA). METHODS: Thirty-five patients and 15 healthy volunteers were studied. All patients underwent an MRI examination during the same period that they underwent ventriculography (26 patients) or radiography (25 patients). From 7 to 11 short-axis slices were acquired with a breath-hold fast-gradient echo-segmented sequence from apex to base. Contours were drawn with an automated border detection software. RESULTS: Ejection fraction (EF) correlated well between modalities (r = 0.77, P<0.001, for MRI and RNA; r = 0.72, P< 0.001, for MRI and CA). CONCLUSIONS: Cardiac MRI is a fast and accurate technique for estimation of LV volumes, EF, and mass.

Clinical experience with 99mTc-MIBI scintimammography in patients with breast microcalcifications.

The aim of this study was to evaluate whether 99mTc-MIBI scintimammography can improve the diagnostic value of mammography for the differentiation of benign and malignant breast microcalcifications. In 41 women presenting 45 clusters of microcalcifications, a 99mTc-MIBI scintimammography was performed before open biopsy. There were 24 malignant lesions (53%). The sensitivity (SE) and specificity (SP) of 99mTc-MIBI scintimammography were 58.3% and 81%, and the positive and negative predictive values (PPV, NPV) were 78% and 63%, respectively. SE and PPV increased for lesions over 10 mm and for the younger patients (under 50 years). No correlation was found between true positive uptake and breast cancer invasiveness: 69% (9/13) for invasive lesions and 45% (5/11) for noninvasive lesions (P = 0.48). 99mTc-MIBI scintimammography was more often positive in high grade than in low- or intermediate-grade ductal carcinoma in situ (P = 0.03). The results were analysed according to the morphologic aspect of the microcalcifications. 99mTc-MIBI scintimammography could not be used for routine evaluation of all the microcalcifications detected by mammography.

Investigation of bound water in frozen precancerous rat liver tissue by proton NMR.

The proton NMR spin lattice relaxation times of bound water (T1b) were studied on frozen rat liver samples during the precancerous step of cancer induction by diethylnitrosamine. Two components of the T1b were found, which show a different temperature dependence of their relative magnetization. Four different steps were identified during the experimental cancer induction according to 1H NMR findings, while only three were distinguished after histological examination. The results point to the influence of cross-relaxation and corroborate previous reports on differences observed between the heat capacity of normal and tumorous tissues.

Glomerular hyperfiltration in type I, type II, and secondary diabetes.

Glomerular hyperfiltration, a risk factor for diabetic nephropathy, has been reported in type I insulin-dependent diabetics, but it is not clear if it occurs in other types of diabetes. To ascertain the prevalence of glomerular hyperfiltration in various types of diabetes, we measured glomerular filtration rate (GFR) in 158 diabetics (91 type I, 36 type II without insulin treatment, 20 type II with insulin treatment, and 11 subjects with diabetes secondary to chronic pancreatitis), and classified them as hyper-, normo-, or hypofiltration according to values measured in 36 age-match controls. After elimination of subjects with overt renal disease or hypertension, glomerular hyperfiltration was detected in 35% of the type I diabetics, 32% of the type II diabetics without insulin treatment, one subject with chronic pancreatitis, and one type II diabetics with insulin treatment. Glomerular hyperfiltration was associated with high blood glucose in type I, insulin-dependent diabetics, and with a high apolipoprotein B/A1 ratio in type II, non-insulin-dependent diabetics without insulin treatment. In all subjects with glomerular hyperfiltration, GFR values and urinary albumin excretion were positively related (r = 0.33; n = 34; p = 0.05). Glomerular hyperfiltration is detectable among all types of diabetics.

New thermoluminescent dosimeters (TLD): optimization and characterization of TLD threads sterilizable by autoclave.

To improve the performance of mono-extruded TLD threads as a dosimetric thermoluminescent tool (French Patent 9903729), a new process was developed by co-extrusion methodology leading to threads of 600 microm diameter with a 50 microm homogeneous polypropylene sheath. In this optimization work, study of parameters such as LiF:Mg,Cu,P powder granulometry, load rate and proportion of components led to an increased sensitivity of around 40%. Moreover, the co-extrusion technique allowed the threads to be sterilized by humid steam (134 degrees C/18 min) without significant variation of the linearity response between 0 and 30 Gy after gamma irradiation (60Co).

Superparamagnetic iron oxide nanoparticles as a liver MRI contrast agent: contribution of microencapsulation to improved biodistribution.

We have developed a new method of synthetizing superparamagnetic iron oxide nanoparticles, consisting in the modifications of Molday's method, which ensures high relaxivity (2.4 10(5) s-1.M-1.L), good chemical stability, singular biodistribution and a considerable safety margin. The ED (Efficace Dose) to LD50 ratio is 1/2400 instead of 1/50 for Gd-DTPA. In order to develop a magnetite-delivery system to the liver we have incorporated the nanoparticles into biodegradable synthetic microcapsules. Encapsulated 59Fe oxide nanoparticles are injected into rats; in these conditions the sequestration is 9-fold greater in liver and 6 and 5 times lower in blood and carcase, respectively. This modification of the biodistribution enables the use of magnetite containing microcapsules at only 0.3 mg/kg iron to obtain an improved contrast in liver.

Iron oxide nanoparticles for use as an MRI contrast agent: pharmacokinetics and metabolism.

The pharmacokinetics and metabolism of a new preparation of superparamagnetic iron oxide nanoparticles were evaluated by 59Fe radiotracer studies and histologic examination of mice liver and spleen tissues (light and transmission electron microscopy). In the first 30 min following IV injection of the product half of the dose injected remains in the blood, the other part being sequestered mainly by the mononuclear phagocyte system (MPS). In the first five days following IV administration of the nanoparticles, early metabolization of the iron oxide cores occurs, revealed by modification of their aspect in the lysosomes of Kupffer cells and macrophages of the splenic red pulp. The incorporation of 59Fe is then observed in RBC of the mice. These results are discussed in relation with the physicochemical properties of this new preparation of nanoparticles, and compared with current pharmacokinetic data concerning injectable particle systems.

Liver-directed superparamagnetic iron oxide: quantitation of T2 relaxation effects.

A new liver-directed superparamagnetic iron oxide nanoparticle preparation, MDL, is described. MDL is derived from previously developed MD particles only by modification of the characteristics of the coating:chemical structure and charge. The biodistribution, pharmacokinetics, and intratissular localization of both 59Fe-labeled MD and MDL particles were analyzed. R2 relaxivities determined in aqueous solution are compared to measurements in liver tissue and to R2 of nanoparticles incorporated into synthetic microcapsules, which represent a simplified cell pattern. T2 relaxation effects of both preparations in liver tissue are discussed relative to physical parameters such as iron oxide core dimension, total particle size, and charge, and pharmacological properties such as biodistribution, pharmacokinetics, and extra/intracellular localization.

Three-dimensional coronary artery MR imaging using prospective real-time respiratory navigator and linear phase shift processing: comparison with conventional coronary angiography.

Respiratory gating with navigator echo is a recent technique to detect diaphragm position in 3D magnetic resonance (MR) coronary angiography. The purpose of our study was to image proximal coronary arteries and to detect significant stenoses in patients with coronary artery diseases and to compare with contrast enhanced angiography results. Twenty patients with coronary artery diseases who were referred for conventional angiography underwent magnetic resonance angiography (MRA). Three-dimensional gradient echo volumes were acquired using cardiac and respiratory gating and fat suppression. Using reformatted oblique planes and maximum intensity projection technique, visualization coronary segments and detection of significant coronary stenoses were made. Eighty-three coronary segments were analyzed. The sensitivity and specificity were 65% and 93%, respectively. The corresponding positive and negative predictive values were 69% and 91%. This study shows the ability to image correctly coronary arteries and to identify proximal stenoses, but image quality need to be improved for an efficiency detection of coronary artery stenoses in clinical practice.

99Tcm-HMPAO cerebral scintigraphy and transcranial pulsed Doppler in acute intracranial hypertension in rabbits.

The purpose of this study was to compare transcranial Doppler sonography (TCD) and 99Tcm-HMPAO cerebral scintigraphy in detecting the effects of acute intracranial hypertension by pressure transmission using a previously validated model. In 20 New Zealand rabbits, cerebral blood flow velocities of basilar artery and carotid siphon were simultaneously monitored in baseline conditions and during acute intracranial hypertension by pressure transmission. This hypertension was induced by progressive steps of 5 mmHg, for a 5 min duration by elevating a saline infusion bottle connected to the subdural space. In baseline conditions, significant correlations were found between basilar artery resistive index and 99Tcm-HMPAO uptake in brain stem, r = 0.5 (p < 0.05) and posterior cerebral areas, r = 0.78 (p < 0.001). Severe intracranial hypertension equal to the diastolic arterial pressure with a cerebral perfusion pressure of 22.8 +/- 12.7 mmHg significantly decreased the basilar artery blood flow velocities and global 99Tcm-HMPAO cerebral uptake. At this level of intracranial pressure, few correlations between the two methods were observed. TCD detected relatively high blood-flow velocities in the carotid siphon appearing to result from proximal cerebral artery vasospasm. Transcranial pulsed Doppler provides data about haemodynamic changes such as hypoperfusion, vascular resistance increase in the basilar artery territory and vasospasm of the carotid siphon. 99Tcm-HMPAO scintigraphy, which has not yet been studied during intracranial hypertension, gave immediate information on local cerebral perfusion. Cerebral scintigraphy demonstrated a significant diffuse and heterogeneous decrease in cerebral blood flow, without dissociation between supratentorial and infratentorial territories, and tissue perfusion deficit owing to arterial vasospasm. TCD provides emergency investigation in patients with severe head injuries or hydrocephalus. 99Tcm-HMPAO complements TCD in cases of vasospasm and in determining an area of perfusion tissue deficit.

Direct effect of calcitriol on the regulation of parathyroid hormone secretion in a case of pseudo-hypoparathyroidism (a 24-month follow-up study).

The diagnosis of pseudohypoparathyroidism with osteitis fibrosa was made in a 51-year-old woman on the basis of hypocalcaemia, elevated plasma PTH (1-84) and blunted cAMP response to hPTH infusion. Radiologically, widespread signs of hyperparathyroidism were observed and quantitative histomorphometry confirmed the increased bone cellular turnover. Treatment with calcitriol (1,25 dihydroxyvitamin D3) induced a dramatic improvement of bone lesions. During treatment PTH (1-84) normalized with high dosage of calcitriol in spite of low or subnormal levels of serum calcium, and subsequently increased for each reduction of calcitriol dosage despite normal calcium levels. Our observations support a major and direct effect of 1,25 dihydroxyvitamin D3 on the regulation of parathyroid secretion of parathyroids glands.

Improving the detection of low concentration metabolites in magnetic resonance spectroscopy by digital filtering.

In vivo detection and quantitation of metabolites is often limited by their low concentration. As far as magnetic resonance spectroscopy (MRS) is concerned, detection and quantitation can be significantly improved by reduction of the observed spectral width (SW). The reduction is limited to the spreading of resonances in the bandwidth unless high performance digital filters are used. Indeed, these filters avoid the folding of unwanted resonances such as water peak into the main frequency spectrum and therefore allow reduction of the spectral width to its optimal value. These filters are now available on most MRS systems but their use is not common even if, as we show in the particular case of proton MRS, a significant increase in signal-to-noise ratio (two-fold factor for SW reduction from 5000 Hz to 1351 Hz) can be achieved. This signal-to-noise improvement allows better quantitation accuracy.

[Determination of left ventricular volume by cardiac angio-scintigraphy at equilibrium. Comparison with a radiologic method]. / Détermination des volumes ventriculaires gauches par angio-scintigraphie cardiaque à l'équilibre. Confrontation à la méthode radiologique.

Cardiac angioscintigraphy at equilibrium was performed after in vitro red cell labelling in the left anterior oblique and anterior views. A syringe of 10 ml labelled blood was placed on the patient's chest over the left ventricle and in contact with the camera's collimator in the LAO incidence. This syringe plays a dual part: as a direct reference for left ventricular radio-activity and as a marker for measuring the distance between the centre of gravity of the LV and the collimator by Links' method. The correction factor for absorption varies with each individual. An algorithm integrating this data automatically calculates the EDV in millilitres (ml) and the end diastolic and systolic volumes from the ejection fraction (EF) determined by an independent method. The study group was 100 patients (91 men, 9 women; 81 coronary, 11 valvular heart and 8 other diseases) with radiological EDV ranging from 107 to 1 283 ml and radiological EF ranging from 14 to 75 p. 100. A very significant correlation was observed between the radiological and scintigraphic EDV with a regression line close to that of identity: EDVs = 1.05 . EDVR-5 ml (or -3 ml/m2); SD = 48 ml; r = 0.953; p less than or equal to 0.001. The mean deviation between the methods was 35.7 ml (median 24 ml) or 13.7 p. 100 (median 9.4 p. 100) of EDVR. A large discrepancy (over 90 ml or 30 p. 100) was observed in only 7 patients, 4 of whom had severe mitral regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)