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Biomedical subjects

D Guilloteau

Publications and source records attributed to D Guilloteau.

At least 73 records · Page 4Linked to original sources
PubMed1992

Estrogen receptor imaging with 17 alpha-[123I]iodovinyl-11 beta-methoxyestradiol (MIVE2)--Part I. Radiotracer preparation and characterization.

It is important to know the estrogen receptor rate in breast carcinoma management. Thus, an in vivo and atraumatic method would be very useful. Different ligands have been proposed for this. We present here the specific synthesis of 20E- and 20Z-17 alpha-iodovinyl-11 beta-methoxyestradiols and their biological characterization as estrogen receptor ligands. The two isomers were analysed by current chemical methods (NMR) and purified by HPLC. We carried out an in vivo study with 21-day-old Swiss mice to compare properties of the two ligands. The 20E-MIVE2 showed the best affinity for estrogen receptors, the uterus-to-blood ratio was 15-fold higher for the trans derivative. We enhanced the in vivo and in vitro properties of the 20E-MIVE2: the affinity constant was determined by Scatchard analysis, Kd = 16 x 10(-10) M, and biodistributions were performed with unlabelled estradiol pre-injection. We concluded that 20E-MIVE2 can be used for a feasibility study in patients with breast carcinoma.

Animals↗
PubMed1992

Estrogen receptor imaging with 17 alpha-[123I]iodovinyl-11 beta-methoxyestradiol (MIVE2)--Part II. Preliminary results in patients with breast carcinoma.

17 alpha-[123I]Iodovinyl-11 beta-methoxyestradiol was injected into 19 women: group 1 (n = 8), initial evaluation of breast cancer; group 2, (n = 11) postoperative follow-up including 9 patients with bone metastases. The primary tumor (size: 8-10 mm) was visualized by breast tomoscintigraphy in 2/4 patients of group 1 with high estrogen receptor concentration (162-445 fmol/mg) and was not detectable in 4 patients with low estrogen receptor concentration (6-32 fmol/mg). Axillary lymph node metastases were detected in 1 patient of group 1 and in 1 patient of group 2. In 4 patients of group 2 with previous primary tumor containing estrogen receptors, MIVE2 uptake in bone metastases was demonstrated. MIVE2 scintigraphy is an original, specific and non-invasive method for breast cancer estrogen receptor imaging in primary and in metastatic tumors.

Adult↗
PubMed1992

Synthesis and in vitro binding properties of halogenated analogues of GBR as new dopamine uptake carrier ligands.

We present the original synthesis of two halogenated analogues of the diphenyl piperazine GBR, bromo-GBR and iodo-GBR, as new dopamine uptake carrier ligands. The derivatives were purified by HPLC and chemically characterized. Bromo-GBR and iodo-GBR and iodo-GBR are potent inhibitors of [3H]GBR 12935 binding to rat striatal membrane, with Ki values of 116 and 113 nM, respectively. We prepared iodo-GBR labeled with iodide-125 from the brominated derivative and concluded that [123I]iodo-GBR could be a potential tool to explore the in vivo dopamine uptake carrier.

Animals↗
PubMed1991

Spiperone: a receptor ligand and/or a granular uptake tracer?

The accumulation of [3H]spiperone and [3H]dopamine was measured in striatum and pituitary gland slices of rat. Contrary to [3H]dopamine, [3H]spiperone storage was similar in striatum and pituitary gland. In addition, [3H]spiperone accumulation was not diminished by reserpine and tetrabenazine. These data show that spiperone is not subject to the granular uptake/storage mechanism and suggest that spiperone and its derivatives are specific ligands for dopamine receptors only.

Animals↗
PubMed1990

Iodobenzamide for in vivo exploration of central dopamine receptors: evaluation in animal models of supersensitivity.

Iodobenzamide is a promising agent to investigate D2 receptors by SPECT in living human brain. In this work, we have evaluated this radiolabeled compound in two animal models of D2 receptors supersensitivity. In the first model, rats were treated chronically with haloperidol during three weeks (S.C. injection of 0.5 mg/kg/day). One week after the last day of treatment, they were I.V. injected with 125I-IBZM. In vivo specific binding study showed a 45 percent increase of 125I-IBZM fixation in the striatum of treated rats. In a second step of experiments, animals were unilaterally lesioned by a stereotaxic injection of 6-OHDA in the substantia nigra, 23 days before receiving 125I-IBZM. Autoradiographic analysis of coronal brain sections showed a 38 percent enhancement of 125I-IBZM in vivo binding in the striatum on the lesioned side as compared to the contralateral intact side; this increase occurred in striatal lateral area. These data demonstrate that 125I-IBZM is convenient to detect alterations of dopamine D2 receptors in vivo in the rat. Thus IBZM labelled with 123I can be a very useful imaging agent for the exploration of D2 receptors in pathological situations.

Animals↗
PubMed1990

Iodoethylspiperone, a new potential agent for exploration of central dopamine D2 receptors: synthesis and preliminary in vivo study.

We synthesized a new spiperone derivative: iodoethylspiperone (IES) to perform dopamine D2 receptor exploration by SPECT. IES was prepared from a precursor: tosylethylspiperone, and characterized by i.r. and 1H-NMR analyses. [125I]IES was obtained with 80% yield. In vivo biodistribution in rats showed a high and specific uptake in the striatum. The uptake ratio between the striatum and the cerebellum reached a maximum value 4 h after injection (10.05 +/- 2.81). IES labeled with 123I should be a promising new agent to investigate D2 receptors in the living human brain.

Animals↗
PubMed1990

[125I]MIBG uptake and release in different regions of the rat brain.

Radioiodinated m-iodobenzylguanidine [( 125I]MIBG) and tritiated norepinephrine [( 3H]NE]) uptake and release were compared, in different regions of the brain of the rat. The classification of the regions according to uptake was the same for both tracers:striatum greater than hypothalamus greater than hippocampus greater than cortex greater than brainstem. Tetrabenazine (TBZ), a granular monoamine uptake inhibitor reduced the uptake in the different regions. The inhibition rate was higher for [3H]NE uptake than for [125I]MIBG. The spontaneous release was the same for [125I]MIBG and [3H]NE and was the lowest in the striatum. The K+ stimulated release of [3H]NE was more complete than the release of [125I]MIBG and was the most important in the striatum. From these results, it is inferred that MIBG enters the brain tissue via NE uptake mechanisms. It appears that MIBG is stored in the chromaffin granules, as NE, but also in the cytoplasm. A modified molecule derived from MIBG which would cross the blood-brain barrier, would then appear as a potential scintigraphic marker of monoamine uptake, storage and release.

3-Iodobenzylguanidine↗
PubMed1990

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.

Adolescent↗
PubMed1990

Monoclonal immunoradiometric assay of calcitonin improves investigation of familial medullary thyroid carcinoma.

Calcitonin (CT) assay is essential for recognizing medullary thyroid carcinoma (MTC), particularly occult familial MTC. In previous radioimmunoassays of calcitonin, polyclonal antibodies were used. Here we evaluate a new two-site immunoradiometric assay (IRMA) of calcitonin based on use of monoclonal antibodies. We assayed samples from healthy subjects, patients with renal failure, and subjects from families affected by MTC. Basal values for healthy subjects were all less than 10 ng/L. Renal failure is associated with increased basal CT. The CT peak under pentagastrin stimulation in healthy patients was less than 30 ng/L. In familial screening, basal values greater than 10 ng/L or peak values greater than 30 ng/L correspond to subjects with histologically confirmed MCT or micro-MCT. Polyclonal RIA performed in the same subjects failed to detect the moderate increase of CT that IRMA demonstrated. Preliminary results indicate that this new method may allow earlier detection of CT increase and thus improved diagnosis of MCT, particularly in familial screening. Monitoring surgical patients could also be improved by this new assay.

Adolescent↗
PubMed1989

[Pharmacokinetics of intradermally-administered drugs].

The dermis, considered as a potential route of administration for drugs, has been widely and empirically used for more than a century. The comparative intravenous and intradermal administration of radiotracers makes it possible to demonstrate that the intradermal route has its own diffusion kinetics and its own biodistribution.

3-Iodobenzylguanidine↗
PubMed1988

Comparison of MIBG and monoamines uptake mechanisms: pharmacological animal and blood platelets studies.

The uptake of MIBG, a scintigraphic agent widely used in the detection of APUD tumours, was studied with a pharmacological approach on an in vitro and an in vivo models. MIBG as well as norepinephrine (NE) was taken up by human blood platelets, a model for presynaptic nerve endings amine uptake, with a thermodependant mechanism. MIBG and NE uptake was inhibited by desimipramine and reserpine. However, MIBG but not NE uptake was inhibited by fluvoxamine, a serotonin (5HT) uptake inhibitor. This suggests that MIBG is a NE and also a 5HT uptake tracer which involves uptake one and vesicular storage mechanisms. In rats treated with 6-hydroxydopamine to induce a chemical sympathectomy, we observed an inhibition of uptake similar for MIBG and NE in the heart, the salivary glands and the spleen, but no effect was observed in the liver. Some clinical inferences to best investigate specific monoamine uptake are drawn from these results.

3-Iodobenzylguanidine↗
PubMed1988

MIBG and catecholamine storage in the brain: an in-vitro study.

The uptake and release of mIBG, a tracer of the monoamine uptake and storage function, were studied on superfused rat cerebral cortex sections. mIBG was taken up and released by a mechanism comparable to that of norepinephrine (NE), but this storage appeared to be less specific for mIBG than for NE. This implies that when mIBG is used as a scintigraphic tracer of monoaminergic synaptic vesicles, imaging should be delayed long enough to ensure release of the molecule from its nonspecific binding sites.

3-Iodobenzylguanidine↗
PubMed1988

[Chorionic gonadotrophic hormone and transitional cell carcinoma of the bladder. Immunohistochemical characterization of HCG and its alpha and beta subunits].

Investigation of cellular localization of hCG and alpha- and beta- subunits in 17 transitional cell carcinomas of urinary bladder was performed using immunohistochemical techniques. Serial sections were tested with monoclonal antibodies to hCG, free beta hCG and free alpha hCG. Transitional cell carcinomas producing hCG and/or beta hCG are easily found (6/17 cases). None of these tumors correspond morphologically to a choriocarcinoma. However, it must be mentioned that neoplastic areas exhibit some features reminiscent of a choriocarcinomatous structure. Notably, positive cells can be disposed at the periphery of neoplastic nests, mimicking the arrangement of syncytiotrophoblast. Positive neoplastic cells express hCG and/or beta hCG; alpha hCG immuno-reactivity is quite rare. The relative distribution of hCG/beta hCG is excessively variable from case to case. In contrast, normal transitional epithelium contains endocrine cells which only express the alpha-subunit of hCG.

Carcinoma, Transitional Cell↗
PubMed1988

Therapeutic effectiveness of iodine-131 MIBG metastases of a nonsecreting paraganglioma.

This case report describes the treatment of the bone metastases of a nonfunctioning sympathetic paraganglioma, with [131I]MIBG. After primary tumor excision and unsuccessful external radiotherapy, the patient received three therapeutic doses of [131I]MIBG, resulting in a reduction of the number and volume of metastases, and an improvement of the general condition. At 3 yr following [131I]MIBG therapy, the patient remained in remission. [131I]MIBG appears to be an efficient and safe agent for treating malignant sympathetic paraganglioma.

3-Iodobenzylguanidine↗
PubMed1988

[Determination of plasma progesterone. Comparison of immunochemical luminescence (LIA) and radioimmunoassay (RIA)].

The authors describe an immunoassay technique of serum progesterone using a chemiluminescent tracer (LIA): progesterone aminobutylethylisoluminol 11-a-hemisuccinate (P-ABEI). The intrinsic characteristics of this technique were studied. The progesterone concentrations of 62 serum samples were simultaneously titrated using this LIA technique and a RIA technique. This LIA technique is quite practicable. The intra and inter-series ability to reproduce this test, and the sensitivities are excellent and comparable to those obtained with RIAs. There is a good correlation between the serum concentrations of progesterone determined by LIA and RIA (y = 1.12 x + 3.2; r = 0.95). A test with paired series did not demonstrate any significant difference (t = 0.67; 0.1 less than p less than or equal to 0.375). In conclusion, with a few technical adjustments (automated light meter, "coat tube"), this method could be perfectly suitable for titrations in a Biology laboratory.

Humans↗
PubMed1987

Radioiodinated meta-iodobenzylguanidine uptake in medullary thyroid cancer. A French cooperative study.

Fifty meta-iodobenzylguanidine (MIBG) scintiscans were performed in three groups of medullary thyroid cancer (MTC) patients. Group 1 (n = 11) included treated patients with normal calcitonin levels; Group 2 (n = 24) included patients with elevated calcitonin levels due to sporadic and isolated MTC; Group 3 (n = 15) included patients with elevated calcitonin levels due to familial MTC or multiple endocrine neoplasia Type IIA syndrome (MEN). In Group 1 three pheochromocytoma were depicted by MIBG scintiscan. In Group 2 MTC was seen in a small number of patients (3 of 24). In Group 3, besides adrenal hyperplasia and pheochromocytoma four patients, MIBG scintigraphy showed where MTC had localized and spread in almost half of patients (7 of 15). MIBG uptake occurred in patients with relatively high calcitonin level (greater than 0.6 nmol/l). These data indicate that in patients with familial MTC or MEN syndrome, MIBG scintiscan can be useful not only in detecting associated pheochromocytoma, but also in showing MTC.

3-Iodobenzylguanidine↗