Nitroimidazole conjugates of bis(thiosemicarbazonato)Cu(II) - Potential combination agents for the PET imaging of hypoxia

Combination agents comprising two different pharmacophores with the same biological target have the potential to show additive or synergistic activity. Bis(thiosemicarbazonato)copper(II) complexes (e.g. ⁶⁴Cu-ATSM) and nitroimidazoles (e.g. ¹⁸F-MISO) are classes of tracer used for the delineation of tumor hypoxia by positron emission tomography (PET). Three nitroimidazole-bis(thiosemicarbazonato)copper(II) conjugates were produced in order to investigate their potential as combination hypoxia imaging agents. Two were derived from the known bifunctional bis(thiosemicarbazone) H₂ATSM/A and the third from the new precursor diacetyl-2-(4-N-methyl-3-thiosemicarbazone)-3-(4-N-ethylamino-3-thiosemicarbazone) - H₂ATSM/en. Oxygen-dependent uptake studies were performed using the ⁶⁴Cu radiolabelled complexes in EMT6 carcinoma cells. All the complexes displayed appreciable hypoxia selectivity, with the nitroimidazole conjugates displaying greater selectivity than a simple propyl derivative used as a control. Participation of the nitroimidazole group in the trapping mechanism is indicated by the increased hypoxic uptake of the 2- vs. the 4-substituted ⁶⁴Cu-ATSM/A derivatives. The 2-nitroimidazole derivative of ⁶⁴Cu-ATSM/en demonstrated superior hypoxia selectivity to ⁶⁴Cu-ATSM over the range of oxygen concentrations tested. Biodistribution of the radiolabelled 2-nitroimidazole conjugates was carried out in EMT6 tumor-bearing mice. The complexes showed significantly different uptake trends in comparison to each other and previously studied Cu-ATSM derivatives. Uptake of the Cu-ATSM/en conjugate in non-target organs was considerably lower than for derivatives based on Cu-ATSM/A.     

Gap Junctions Mediate Glucose Transport Between GLUT1-Positive and -Negative Cells in the Spiral Limbus of the Rat Cochlea

To elucidate the role of the spiral limbus in glucose transport in the cochlea, we analyzed the expression and localization of GLUT1, connexin26, connexin30, and occludin in the spiral limbus of the rat cochlea. GLUT1 and occludin were detected in blood vessels. GLUT1, connexin26, connexin30, and occludin were also expressed in fibrocytes just basal to the supralimbal lining cells. Connexin26 and connexin30 were present among not only these GLUT1-positive fibrocytes but also GLUT1-negative fibrocytes. In vivo glucose imaging using 6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-6-deoxyglucose (6-NBDG, MW 342) together with Evans Blue Albumin (EBA, MW 68,000) showed that 6-NBDG was rapidly distributed throughout the spiral limbus, whereas EBA was localized only in the vessels. Moreover, the gap junctional uncoupler heptanol inhibited the distribution of 6-NBDG. These findings suggest that gap junctions play an important role in glucose transport in the spiral limbus, i.e., that gap junctions mediate glucose transport from GLUT1-positive fibrocytes to GLUT1-negative fibrocytes in the spiral limbus.     

Evaluation of four-dimensional cone beam computed tomography ventilation images acquired with two different linear accelerators at various gantry speeds using a deformable lung phantom

We evaluated four-dimensional cone beam computed tomography (4D-CBCT) ventilation images (VI_CBCT) acquired with two different linear accelerator systems at various gantry speeds using a deformable lung phantom.The 4D-CT and 4D-CBCT scans were performed using a computed tomography (CT) scanner, an X-ray volume imaging system (Elekta XVI) mounted in Versa HD, and an On-Board Imager (OBI) system mounted in TrueBeam. Intensity-based deformable image registration (DIR) was performed between peak-exhale and peak-inhale images. VI_CBCT- and 4D-CT-based ventilation images (VI_CT) were derived by DIR using two metrics: one based on the Jacobian determinant and one on changes in the Hounsfield unit (HU). Three different DIR regularization values (λ) were used for VI_CBCT. Correlations between the VI_CBCT and VI_CT values were evaluated using voxel-wise Spearman’s rank correlation coefficient (r).In case of both metrics, the Jacobian-based VI_CBCT with a gantry speed of 0.6 deg/sec in Versa HD showed the highest correlation for all the gantry speeds (e.g., λ = 0.05 and r = 0.68). Thus, the r value of the Jacobian-based VI_CBCT was greater or equal to that of the HU-based VI_CBCT. In addition, the ventilation accuracy of VI_CBCT increased at low gantry speeds.Thus, the image quality of VI_CBCT was affected by the change in gantry speed in both the imaging systems. Additionally, DIR regularization considerably influenced VI_CBCT in both the imaging systems. Our results have the potential to assist in designing CBCT protocols, incorporating VI_CBCT imaging into the functional avoidance planning process.     

A gene (Bmn) controllingβ-mannosidase activity in the mouse is located in the distal part of chromosome 3

A gene (Bmn) with a major effect on -mannosidase activity in kidney and liver of the house mouse was revealed by assay with the synthetic substratep-nitrophenyl--d-mannoside. Activity is low in DBA/2J and CSB mice and high in C57BL/6J mice. By the use of the BXD series of recombinant inbred strains and by crosses between C57BL and CSB, it was possible to map the gene to the distal part of chromosome 3 by demonstration of linkage to a gene for cadmium resistance,cdm, as well as to theAdh-3 locus.This work was supported by Swedish Natural Science Research Council Project B-BU 2992-108.     

Morphological adaptation of shape to flow: Microcurrents around lotic macroinvertebrates with known Reynolds numbers at quasi-natural flow conditions

Summary Using Laser Doppler Anemometry we measured current velocities in the median plane around dead lotic macroinvertebrates in a flume which reproduced natural near bottom hydraulics. We investigated specimens of the gastropods Ancylus, Acroloxus, and Potamopyrgus, the amphipod Gammarus, and the larval caddisflies Anabolia, Micrasema, and Silo of various size, various alignment to the flow or which were otherwise manipulated in order to clarify certain questions of adaptation of shape or case building style to flow, or the effects of flow on field distribution patterns. The steepest velocity gradients close to the animals were found near areas of their bodies protruding furthest into the flow. In such regions the rates of potential diffusive exchange processes, the potential corrasion (abrasion through suspended solids), and, for larger specimens, the lift forces (directed towards the water surface) must be highest. Posterior of these areas growing boundary layers formed above those species whose upper contour was approximately parallel to the upstream-downstream direction of the flow. All specimens removed momentum from the flow and thus experience a drag force (directed downstream). From the complete data set we derived the following general conclusions about the physical effects of potential morphological adaptations, taking into consideration diffusion through boundary layers, corrasion, lift forces, friction and pressure drag forces: The physical significance of these five factors generally depends on the Reynolds number of an animal and is largely affected by flow separation, which was significantly related to the ratio of body length to height and the slope of the posterior contour. A simultaneous effective morphological adaptation to all five factors is physically impossible and, in addition, would have to change from life at low (e.g. a young, small specimen of a species) to life at high (e.g. a fully grown specimen of the same species) Reynolds number.     

Production of isolated somatic embryos from sunflower thin cell layers

We describe here a two step procedure which allows the easy isolation of somatic embryos from Sunflower (Helianthus annuus L.) hypocotyl tissues. Thin cell layers composed of the epidermis plus 3 to 6 parenchyma cell layers were incubated for 5 days in a basal Murashige and Skoog medium using an auxin to cytokinin weight ratio of 1/1. The epidermis layers were then transferred to a Gamborg medium containing a high level of sucrose. After one week of incubation in this medium, many somatic embryos started to be released from the parental epidermal tissue. Even though the germination of these embryos is difficult, we have been able to induce secondary embryos and regenerate fertile plants.Abbreviations NAA 1-naphthalene acetic acid - IAA indole-3-acetic acid - BAP 6-benzylamino-purine - MS Murashige and Skoog medium - B5 Gamborg medium     

A comparison of in vitro flowers to in vivo flowers of haploid and diploidNicotiana tabacum L.

Thin cell layers (TCLs) were cultured from inflorescences of diploid (2n=4x=48) and haploid (2n=2x=24)Nicotiana tabacum L. "Samsun" and the subsequent flowers formed in vitro were then compared to in vivo flowers. Plants derived from TCLs possessed flowers that were typical of their seed or androgenetically-derived counterparts, whereas de novo flowers from TCLs were abnormal when compared to their counterparts. The TCLs of haploid plants produced more flower buds than diploid TCLs, and did so in a shorter period of time. In vitro flowers and anthers at both ploidy levels were considerably smaller than the in vivo flowers; in vitro flowers also had variable numbers of anthers and pistils. The embryogenic capacity of anthers taken from in vivo diploid flowers was 5 times greater than that of in vitro diploid or haploid anthers. In vivo haploid anthers produced no embryoids, whereas in vitro haploid anthers did produce embryoids. Observations of mitotic cells in root tips of plants derived from anther cultures of in vitro haploid flowers revealed a mixoploid nature. Diploid meiosis was regular and haploid meiosis was irregular regardless of the origin (in vitro or in vivo) of the flowers.Supported by state Hatch funds.     

Feeding postures of suspension-feeding larval black flies: the conflicting demands of drag and food acquisition

Summary We tested whether larval black flies actively control the positioning of their feeding appendages (labral fans), and if so, whether their posture represents a balance between the conflicting demands of drag and feeding. We compared the postures of live larvae with the postures of larvae killed by heat-shock in three different flow regimes in a laboratory experiment; we assumed that the postures of heat-killed larvae approximated a passive response to drag. The average height of the labral fans above the bed declined significantly in faster flows, and was significantly greater in live than dead larvae. There was also a significant interaction effect, since the difference between the fan heights of live and dead larvae was greater in slower flows. Two mechanisms may contribute to this result. Larvae in slower flows have to increase their fan heights more than larvae living in faster flows to achieve comparable increases in velocity and thus particle flux. In addition, muscular strength may limit the feeding postures larvae can assume. The fan heights of live larvae also varied depending on the concentration of food particles: larvae exposed to low food concentrations held their fans higher above the bed than did larvae exposed to high food concentrations in the same flow regime. This change in posture is due neither to an uneven particle concentration in the boundary layer nor to added drag from particles trapped in the labral fans. Collectively, our results indicate that these suspension feeders actively control their feeding posture, and suggest that these varying postures represent a dynamic balance between the conflicting needs of minimizing drag and maximizing feeding.     

Hoplolaimoidea (Nematoda: Tylenchida) from the Aleutian Islands with Descriptions of Four New Species

Four new species of hoplolaimoid nematodes (Merlinius adakensis, Pratylenchoides megalobatus, Pratylenchus pratensisobrinus, and Pratylenchus ventroprojectus) are described from Adak Island in the Aleutian chain. M. adakensis n. sp. is separated from other species by body length (0.96-1.3 mm), stylet length (32-36 μm), number of tail annules (49-68), and c'' (3.1-4.1). P. megalobatus n. sp. differs from all known Pratylenchoides spp. by having a very long esophageal gland lobe (b'' = 2.4-3.3, overlap 3-6 times the body width). P. pratensisobrinus n. sp. closely resembles P. pratensis (de Man) Filipjev, but has a longer stylet (15-17 μm), a longer tail (c = 12-15; c'' = 2.8-3.7), and more tail annules (23-37). P. ventroprojectus n. sp. is distinguished by body length (392-475 μm), three lip annules, low and flattened cephalic capsule, and presence of terminal subventral projection. Pratylenchoides variabilis Sher, Helicotylenchus amplius Anderson &Eveleigh, and H. spitsbergensis Loof are also reported from Adak and Amchitka Islands.