Evaluation of skin doses for cone-beam computed tomography in dentomaxillofacial imaging: A preclinical study.

PURPOSE: Evaluation of skin organ doses in six different cone-beam computed tomography scanners (CBCT) dedicated to dentomaxillofacial imaging. Our hypothesis is that the dose varies between different devices, protocols and skin areas. MATERIALS AND METHODS: An anthropomorphic adult head and neck phantom was used to which a dosimeter (Waterproof Farmer® Chamber, PTW, Freiburg, Germany) was attached to anatomic landmarks of both parotid glands, both ocular lenses, the thyroid gland and the neurocranium. CBCT examinations were performed on six different CBCT devices dedicated to dentomaxillofacial imaging with standard settings and, if available, also in high dose settings. Measurements were repeated five times each. RESULTS: The measured mean skin doses ranged from 0.48 to 2.21 mGy. The comparison of the region based dose evaluation showed a high correlation between the single measurements. Furthermore, the distribution of doses between regions was similar in all devices, except that four devices showed side differences for the dose of the parotid region and one device showed side differences for the lens region. The directly exposed regions, such as the parotid glands, showed significant higher values than the more distant regions like the neurocranium. When comparing examination protocols, a significant difference between the standard dose and the high dose acquisitions could be detected. But also a significant dose difference between the different CBCTs could be shown. 3D Accuitomo 170 (Morita, Osaka, Japan) showed the highest absorbed mean dose value for standard settings with 2.21 mGy, especially at the directly exposed regions and their adjacent organs. The lowest mean value for standard settings was achieved with VGi evo (NewTom, Verona, Italy) with 0.48 mGy. CONCLUSION: Repeated measurements of skin organ doses in six different CBCT scanners using a surface dosimeter showed side differences in distribution of dose in five devices for the parotid and lens region. Additionally, significant dose differences between the devices could be detected. Further studies should be performed to confirm these results.

Allium species from Central and Southwest Asia are rich sources of marasmin.

Marasmin, which is especially known from the two South African species Tulbaghia alliacea and Tulbaghia violacea , but was also described for the garlic mushroom Marasmius alliaceus , is the precursor of the thiosulfinate marasmicin. Marasmicin has attracted considerable attention because of its antifungal and tuberculostatic activities. However, many Allium species of the subgenus Melanocrommyum, especially Allium suworowii , are also very rich in marasmin. A. suworowii revealed concentrations of marasmin up to 1.6%, related to the fresh weight of bulbs, and up to 3.0%, related to air-dried fruiting bodies, of the corresponding γ-glutamylmarsmin was found in M. alliaceus. Both species show much higher amounts of marasmin as Tulbaghia and could be considered as natural sources for the isolation of this compound. Further promising Allium species with considerable amounts of marasmin besides other cysteine sulfoxides are Allium stipitatum and Allium altissimum . (R(S),R(C))-Marasmin is typical for the investigated species of the subgenus Melanocrommyum, whereas γ-glutamyl-(S(S),R(C))-marasmin is the only cysteine sulfoxide for the genus Marasmius known until now. Both cysteine sulfoxides were isolated and described as o-phthaldialdehyde (OPA) derivatives. Furthermore, the cysteine sulfoxides methiin, propiin, S-(2-pyrrolyl)-cysteine sulfoxide, eventually S-(2-pyridyl)-cysteine sulfoxide and S-(2-pyridyl)-L-cysteine N-oxide were found.

Cysteine sulfoxides and volatile sulfur compounds from Allium tripedale.

Allium tripedale Trautv. belonging to the subgenus Nectaroscordum grows naturally in the mountainous areas of northwest Iran. Leaves have a very strong and somewhat unpleasant taste and are widely used by the local population as a spicy vegetable. Three new cysteine based compounds were identified in A. tripedale as the first examples of sulfur containing 1-butenyl derivatives in nature. The compounds have been described as o-phthaldialdehyde (OPA) derivatives and identified as (+)-S-(1-butenyl)-L-cysteine sulfoxide (homoisoalliin) and its gamma-glutamyl derivative as well as the gamma-glutamyl derivative of S-(1-butenyl)-L-cysteine (desoxyhomoisoalliin). These cysteine sulfoxides have been also found in Allium siculum Ucria. As volatile compounds, di-(1-butenyl)-disulfide and the cepaene-like compounds di-(1-S-sulfoxymethyl-butyl)-disulfide, 1-S-sulfoxymethyl-butyl-1'-S-sulfoxy-1-butenyl-butyl-disulfide and 1-S-sulfoxymethyl-butyl-1'-S-sulfoxybutyl-butyl-disulfide could be tentatively identified by various MS experiments. Primary products resulting from the alliinase reaction of homoisoalliin seem to be highly unstable and were rapidly converted to the volatile compounds listed above.

Isolation and identification of a new cysteine sulfoxide and volatile sulfur compounds from Allium subgenus Melanocrommyum.

A new cysteine sulfoxide containing a pyridyl residue was identified in bulbs of Allium L. species belonging to the subgenus Melanocrommyum section Megaloprason. One of these species, Allium stipitatum, is widely used as a crop plant and in folk medicine in Central Asia. The new cysteine sulfoxide was identified as L-(+)-S-(2-pyridyl)-cysteine sulfoxide. Aside from this cysteine sulfoxide, several pyridyl compounds could be identified, which were formed out of cysteine sulfoxides by the action of alliinase. Found cysteine sulfoxides and their metabolites are chemically unstable; thus, the analysis is rather difficult. By combining high-performance liquid chromatography (HPLC), HPLC tandem mass spectrometry, NMR, IR, and photometric methods, full structure elucidation of the cysteine sulfoxide was possible. Alliinase reaction products were mainly determined by various MS techniques. The achieved results give new insights in the chemistry of Allium crop plants and are probably useful for chemotaxonomical classification of the subgenus Melanocrommyum.