Locally advanced verrucous carcinoma of the oral cavity: treatment using customized mold HDR brachytherapy instead of hemi-maxillectomy.

BACKGROUND: Oral verrucous carcinomas are locally invasive but rarely metastasize. Current treatment options include surgery and external beam radiotherapy (EBRT). In medical inoperable patients or irresectable tumors, high-dose-rate (HDR) brachytherapy is a valid alternative. CASE: We present an 85-year-old man with functionally irresectable cT3N0M0 verrucous carcinoma superficially spreading along the upper alveolar ridge to the retro-alveolar triangle, with infiltration of the left soft and hard palate and buccal mucosa. Using a customized intraoral mold, this patient was treated with HDR brachytherapy delivering a dose of 48 Gy in 12 fractions three times per week. Treatment was well tolerated, and after prolonged confluent mucositis the tumor is in complete remission. REVIEW OF LITERATURE AND CONCLUSION: The scarce literature on customized mold HDR brachytherapy in maxillary tumors is reviewed and recommendations for other head and neck tumors are given.

Immunological evidence for the presence of plant homologues of the actin- related protein Arp3 in tobacco and maize: subcellular localization to actin-enriched pit fields and emerging root hairs.

The actin-nucleating and -organizing Arp2/3 protein complex is well known to be conserved throughout the eukaryotic kingdom. For higher plants, however, only limited evidence is available for the presence of the Arp2/3 complex so far. Using heterologous antibodies against the Dictyostelium discoideum and Schizosaccharomyces pombe proteins and a bovine peptide, we found immunological evidence for the presence of Arp3 homologues in plants. First, proteins with a molecular mass of about 47-50 kDa were clearly recognized in extracts of both a dicotyledonous plant (tobacco) and a monocotyledonous plant (maize) in immunoblots with the anti-Arp3 antibodies. Second, immunolocalization with these Arp3 antibodies was performed on different plant cells, selected for their diverse actin organizations and functions. On isolated plasma membrane ghosts derived from tobacco leaf protoplasts, a putative Arp3 was localized along cortical actin filaments. In the inner cortex of maize roots, Arp3 was localized to actin-rich plasmodesmata and pit fields and to multivesicular bodies in the cytoplasm. During root hair formation, distinct site-specific localization was found at the protruding apical plasma membrane portions of these tip-growing cells.

Giant mitochondria are a response to low oxygen pressure in cells of tobacco (Nicotiana tabacum L.).

Low oxygen pressure induces fast and reversible formation of giant mitochondria in cells of Nicotiana tabacum. These can have unusual shapes, attain a length of 80 microm and even form a reticulum. In contrast to animal cells, there is no such response to chemically induced oxidative stress.

Plant mitochondria move on F-actin, but their positioning in the cortical cytoplasm depends on both F-actin and microtubules.

Mitochondrion movement and positioning was studied in elongating cultured cells of tobacco (Nicotiana tabacum L.), containing mitochondria-localized green fluorescent protein. In these cells mitochondria are either actively moving in strands of cytoplasm transversing or bordering the vacuole, or immobile positioned in the cortical layer of cytoplasm. Depletion of the cell's ATP stock with the uncoupling agent DNP shows that the movement is much more energy demanding than the positioning. The active movement is F-actin based. It is inhibited by the actin filament disrupting drug latrunculin B, the myosin ATPase inhibitor 2,3-butanedione 2-monoxime and the sulphydryl-modifying agent N-ethylmaleimide. The microtubule disrupting drug oryzalin did not affect the movement of mitochondria itself, but it slightly stimulated the recruitment of cytoplasmic strands, along which mitochondria travel. The immobile mitochondria are often positioned along parallel lines, transverse or oblique to the cell axis, in the cortical cytoplasm of elongated cells. This positioning is mainly microtubule based. After complete disruption of the F-actin, the mitochondria parked themselves into conspicuous parallel arrays transverse or oblique to the cell axis or clustered around chloroplasts and around patches and strands of endoplasmic reticulum. Oryzalin inhibited all positioning of the mitochondria in parallel arrays.

A comparison of F-actin labeling methods for light microscopy in different plant specimens: multiple techniques supplement each other.

Different detection methods for F-actin labeling were compared on a range of plant specimens: cultured cells, whole organ mounts and sectioned material. For cultured cells, microinjection of labeled phalloidin yielded the most detailed picture but careful permeation methods come close, while immunocytochemical methods always gave relatively poor detail, especially on the level of the fine filaments. For whole organ mounts and sectioned material, permeation methods and immunolocalization are the methods of choice, however never reaching the level of resolution of permeation methods in single cells. It is clear that there is no general and universal good method and multiple techniques are needed, especially when working with different specimens and with different aims.

From hormone signal, via the cytoskeleton, to cell growth in single cells of tobacco.

Cultured mesophyll protoplasts of Nicotiana tabacum L. can be hormonally induced into different developmental pathways. In a medium containing auxins (NAA) and cytokinins (BAP) cells divide and eventually give rise to calli. When only auxins are present cells elongate and finally differentiate into very long tubular cells. We focused on the sequence of events leading to elongation. When cultured in a high (1 mg/l) auxin concentration elongating cells seem to pass a certain threshold and increase their nuclear DNA up to about 16C. Cells cultured in a low (0.065 mg/l) auxin concentration only have C-values up to 4C, are unable to pass this threshold and finally fail to elongate. Besides the concentration dependence of the auxin signal, the efflux of auxin seems to be necessary for elongation since addition of TIBA drastically reduces the amount of elongating cells. Concomitant with the changes in nuclear physiology, auxin-induced axiality is seen as sequential rearrangements of microtubules and actin-filaments and of cell wall cellulose microfibrils from 'randomly' arranged in spherical cells to an orientation perpendicular to the long axis of elongating cells.

Dietary uptake of superlipophilic compounds by earthworms (Eisenia andrei).

The uptake and elimination of three superlipophilic compounds (hexabromobenzene, PCB153, and octachloronaphthalene) after dietary uptake was studied in earthworms (Eisenia andrei). All three compounds were taken up from the food, although they did not significantly accumulate despite their hydrophobicity. Both uptake efficiencies (E) and biomagnification factors (BMF) were low. E varied between 0.70 and 7.5%, while BMF values were all below 0.17. The elimination of the compounds was slow, with elimination rate constants k2 varying between 0.04 and 0.09 day-1.

Modelling the accumulation of hydrophobic organic chemicals in earthworms : Application of the equilibrium partitioning theory.

In this paper a method is developed which can be used to estimate the body burden of organic hydrophobic chemicals in earthworms. In contrast to the equilibrium partitioning theory, two routes of uptake are incorporated: uptake from interstitial water and dietary uptake. Although many uncertainties still remain, calculations show that for earthworms steady state body burdens are mainly determined by uptake from interstitial water. Under most circumstances, the contribution of dietary uptake is small, except for hydrophobic chemicals (log Kow > 5) in soils with a high organic matter (OM) content of ≈ 20 %. Under those conditions, estimates of the steady state body burden calculated with the equilibrium partitioning model, in which only uptake from interstitial water is taken into account, might result in a small underestimation of the real body burden of chemicals in earthworms.

The toxicokinetic behavior of chlorobenzenes in earthworms (Eisenia andrei): experiments in water.

The toxicokinetic behavior of five chlorobenzenes in earthworms (Eisenia andrei) was studied. Because exposure in soil is difficult to control, worms were kept in water. Bioconcentration factors (BCF) were studied in a static test system. The results show that a steady-state concentration in worms is reached within 5 days. BCF values increased with increasing octanol-water partition coefficient (Kow). To determine elimination rate constants (k2), worms were exposed to a mixture of chlorobenzenes for 6 days followed by a depuration period of 21 days. The data of the elimination process are described by one-compartment first order kinetics. Hexachlorobenzene was not eliminated within the observed period. Bioconcentration factors increase and elimination rate constants (k2 values) decrease with increasing log Kow. The resulting BCF and k2 values are comparable with those found in fish studies.