[en] 6-[¹⁸F] fluoro-L-dopa (¹⁸F-DOPA) is a levodopa analogue. ¹⁸F-DOPA PET/CT imaging is considered as an ideal tool in the diagnosis and evaluation of Parkinson's disease, brain tumors, pheochromocytoma/paraganglioma, neuroblastoma, gastrointestinal carcinoid, medullary thyroid cancer and congenital hyperinsulinemia. This paper reviews the synthesis, mechanism of localization, imaging procedures, clinical indications and research advances of ¹⁸F-DOPA. (authors)

No abstract available

No abstract available

[en] This presentation is about: Congenital hyperinsulinism, Pathophysiology Radiopharmaceutical, Evaluation study physiological uptake diffuse uptake

[en] A trimethylammonium veratraldehyde triflate was synthesized and used as a precursor for the asymmetric synthesis of 6-[¹⁸F]fluoro-L-dopa. Its nucleophilic fluorination with ¹⁸ F-fluoride produced by the ¹⁸O(p,n) ¹⁸F nuclear reaction on enriched ¹⁸O-water led to the corresponding no-carrier-added [¹⁸F]fluoroveratraldehyde (45 ± 5% EOB). Diiodosilane was used to prepare the corresponding [¹⁸F] fluorobenzyl iodide (36.5 ± 5.3% EOB). Alkylation of (S)-1-tert-boc-2-tert-butyl-3-methyl-4-imidazolidinone with this electrophilic agent, hydrolysis and purification by preparative high-pressure liquid chromatography made 6-[¹⁸F]fluoro-L-dopa ready for human injection, in a 23% ± 6% decay-corrected radiochemical yield. The enantiomeric purity and the specific activity were above 96% and 1 Cl/μmole respectively. Through this procedure, starting from 250 mCi of ¹⁸F-fluoride, multimillicurie amounts (32 ± 8.5 mCi) of no-carrier-added 6-[¹⁸F]fluoro-L-dopa are now available at the end of synthesis (90 min) with a good radiochemical purity (more than 98%). 28 refs., 3 figs., 1 tab

[en] Collagen was exposed to an ultraviolet (UV) lamp that emitted predominantly in the UVB range. The cross-linking of collagen type I and type IV by UV irradiation was observed. Amino acid analyses revealed that Tyr residues in both collagen types I and IV were decreased by irradiation. In collagen type IV, losses of His and Met residues were also observed. These losses of collagen type IV may be due to the degradation of Trp, which exists in collagen type IV and decreased drastically during UV irradiation. To clarify the mechanism of Tyr modification in both types of collagen, the degradation products of Tyr were analyzed. Dityrosine, which is a dimer of the Tyr residue, could not be detected in the acid hydrolysates of Uv-irradiated collagen. However, 3,4-dihydroxyphenylalanine, DOPA, was detected in the hydrolysates using HPLC with an electrochemical detector. The amounts of DOPA in the acid hydrolysates of collagen exposed to UV light for 24 h were approximately 350 pmol/mg protein (collagen type IV) and 80 pmol/mg protein (collagen type I). The DOPA formed may partially contribute to photoaging of the skin. (author)

[en] Congenital hyperinsulinism (CHI) is responsible for hyperinsulinemic hypoglycemia which needs aggressive treatment in order to prevent neurological damages. Recent advances in genetics have linked CHI to mutations in many different genes that play a key role in regulating insulin secretion from pancreatic β-cells. Furthermore, histopathological lesions, diffuse and focal, have been associated with these different genetic alterations. This short manuscript describes how the advent of fluorine-18-labeled L-dihydroxyphenylalanine-positron emission tomography/computed tomography (¹⁸F-DOPA-PET/CT) scanning has changed the management of patients with CHI. ¹⁸F-DOPA PET/CT imaging differentiates focal from diffuse disease and is 100% accurate in localizing the focal lesion. In these patients, the lesion can be surgically removed allowing complete resolution of clinical alterations. We report a case in which clinical experience together with rapid genetic analysis and imaging with ¹⁸F-DOPA-PET/CT, were able to guide the correct clinical management of this condition. We confirm that advances in molecular genetics, imaging methods (¹⁸F-DOPA PET-CT), medical therapy, and surgical approach have completely changed the management and improved the outcome of these children. (author)

No abstract available

[en] We modified the single-isotope radioenzymatic assay for catecholamines [Life Sci. 21, 625(1977)] to assay 3,4-dihydroxyphenylalanine (DOPA). DOPA decarboxylase is used to convert DOPA to dopamine, which concurrently is converted to [³H]-3-O-methyldopamine in the presence of catechol-O-methyltransferase and [methyl-³H]-S-adenosylmethionine and assayed radioenzymatically. For assay of plasma DOPA, 50 μl of untreated plasma is added directly into the incubation mixture. A duplicate mixture containing an internal standard requires a second 50-μl aliquot of plasma. Because the assay measures both DOPA and endogenous dopamine, two additional aliquots of plasma must be assayed for dopamine in the absence of the decarboxylase by the differential assay; DOPA is estimated by difference. The assay is sensitive to 25 pg (500 ng/liter of plasma). Analysis of DOPA (DOPA plus dopamine) and the concurrent differential assay of catecholamines in at least 10 samples can be done in a single working day. Plasma DOPA concentrations for 42 normotensive adults were 1430 +- 19 ng/liter (mean +- SEM). In contrast, dopamine concentrations for these same subjects averaged 23 +- 20 ng/liter. Values for the 24 women subjects (1510 +- 62 ng/liter) significantly (P = 0.04) exceeded those for the men

[en] This paper is a case presentation of a idiopathic cerebral calcification manifesting itself as a Parkinsonism. The patient, a 48-year-old female, was admitted to this hospital with a chief complaint of gait disturbance that had developed over the previous four months. On admission she was noted to have a slight dimunition of her mental capacity, a rigidity of her extremities (more pronounced in the lower limbs), and akinesia, though no tremor. CT scans revealed extensive areas of calcification in the central nervous system, encompassing the cerebral basal ganglia (corpus striatum), the cerebellum, the midbrain, and the gray and white matter of the cerebrum. There was no evidence of calcification in the spinal cord. Physical and laboratory examinations did not yield any findings suggestive of abnormalities in calcium metabolism, nor was there any indication that her condition was of a familial nature. The case was concluded, therefore, to be idiopathic. Amelioration in the symptoms occurred following the administration of L-dopa. (author)