A prospective pilot study on early toxicity from a simultaneously integrated boost technique for canine sinonasal tumours using image-guided intensity-modulated radiation therapy.

In order to overcome the common local treatment failure of canine sinonasal tumours, integrated boost techniques were tried in the cobalt/orthovoltage era, but dismissed because of unacceptable early (acute) toxicity. Intriguingly, a recent calculation study of a simultaneously integrated boost (SIB) technique for sinonasal irradiation using intensity-modulated radiation therapy (IMRT) predicted theoretical feasibility. In this prospective pilot study we applied a commonly used protocol of 10 × 4.2 Gy to the planning target volume (PTV) with a 20%-SIB dose to the gross tumour volume (GTV). Our hypothesis expected this dose escalation to be clinically tolerable if applied with image-guided IMRT. We included 9 dogs diagnosed with sinonasal tumours without local/distant metastases. For treatment planning, organs at risk were contoured according to strict anatomical guidelines. Planning volume extensions (GTV/CTV/PTV) were standardized to minimize interplanner variability. Treatments were applied with rigid patient positioning and verified daily with image guidance. After radiation therapy, we set focus on early ophthalmologic complications as well as mucosal and cutaneous toxicity. Early toxicity was evaluated at week 1, 2, 3, 8 and 12 after radiotherapy. Only mild ophthalmologic complications were found. Three patients (33%) had self-limiting moderate to severe early toxicity (grade 3 mucositis) which was managed medically. No patient developed ulcerations/haemorrhage/necrosis of skin/mucosa. The SIB protocol applied with image-guided IMRT to treat canine sinonasal tumours led to clinically acceptable side effects. The suspected increased tumour control probability and the risk of late toxicity with the used dose escalation of 20% has to be further investigated.

The lateral root initiation index: an integrative measure of primordium formation.

BACKGROUND AND AIMS: Lateral root initiation is an essential and continuous process in the formation of root systems; therefore, its quantitative analysis is indispensable. In this study a new measure of lateral root initiation is proposed and analysed, namely the lateral root initiation index (I(LRI)), which defines how many lateral roots and/or primordia are formed along a parent-root portion corresponding to 100 cortical cells in a file. METHODS: For data collection, a commonly used root clearing procedure was employed, and a new simple root clearing procedure is also proposed. The I(LRI) was determined as 100dl, where d is the density of lateral root initiation events (number mm(-1)) and l is the average fully elongated cortical cell length (mm). KEY RESULTS: Analyses of different Arabidopsis thaliana genotypes and of a crop plant, tomato (Solanum lycopersicum), showed that I(LRI) is a more precise parameter than others commonly used as it normalizes root growth for variations in cell length. Lateral root primordium density varied in the A. thaliana accessions Col, Ler, Ws, and C24; however, in all accessions except Ws, I(LRI) was similar under the same growth conditions. The nitrogen/carbon ratio in the growth medium did not change the lateral root primordium density but did affect I(LRI). The I(LRI) was also modified in a number of auxin-related mutants, revealing new root branching phenotypes in some of these mutants. The rate of lateral root initiation increased with Arabidopsis seedling age; however, I(LRI) was not changed in plants between 8 and 14 d post-germination. CONCLUSIONS: The I(LRI) allows for a more precise comparison of lateral root initiation under different growth conditions, treatments, genotypes and plant species than other comparable methods.

Dual role of thyroid hormones in rat soleus muscle MyHC isoform expression.

We have analyzed the influence of altered thyroid hormone levels on changes of MyHC protein isoforms and their mRNA transcripts in the soleus muscle of 2-, 4- and 7-month-old euthyroid (EU), hypothyroid (HY) and hyperthyroid (TH) female inbred Lewis strain rats (methimazole and T3 treatment started 3 to 4 weeks after birth). We have found that the content of the dominant MyHC 1 isoform gradually increased in the EU rats and that this increase was more progressive in the HY rats at all three stages. On the other hand, in the TH rats the content of MyHC 1 isoform was the highest in the 2-month-old rats and it decreased with an increasing length of T3 treatment. The content of the minor 2a MyHC isoform followed the opposite pattern. In contrast to the protein isoforms, the MyHC mRNA transcripts remained at similar levels. Nevertheless, in general, the MyHC 1 mRNA level was decreased and MyHC 2a transcript increased in the TH rats, while the opposite changes occurred in the HY rats. Our results thus suggest that in the rat soleus muscle, both increased and decreased levels of thyroid hormones speed up the formation of an adult slow phenotype which is demonstrated by the precocious appearance of the slow MyHC 1 isoform, but opposite to the hypothyroid status, a longer T3 application promotes the expression of the faster MyHC 2a isoform.

Hyperthermia in the chick embryo: HSP and possible mechanisms of developmental defects.

Although hyperthermia is an established teratogen in all species studied and the cellular heat shock response is well known, the mechanisms of developmental deviation remain obscure. We have used a chick model system in which fertilized eggs containing embryos at presomite and/or early somite stages (HH 4-10) were exposed to 45 degrees C for 180 min. Six hours following treatment we did not observe any overt morphological disturbance, but at twelve hours following exposure (when controls reached HH 11-13) embryos exposed at late streak stages (HH 4-6) exhibited severe malformation of the head. Embryos exposed later (HH 6-9) manifested spina bifida at the thoracic and lumbosacral levels. Mirror image heart looping was also observed in 20% of these embryos. Paraxial mesoderm was apparently unaffected. Changes in cell proliferation and induced cell death preceded morphological changes. We used acridine orange and confocal laser microscopy to demonstrate that hyperthermia induced cell death in neural folds starting 6 h following treatment. To assess cell proliferation, we used BrdU incorporation for 4 h. Immunodetection on paraffin sections demonstrated that proliferation was inhibited 6 h after treatment. Heat-exposed embryos exhibited the heat shock response, with protein expression reaching a maximum 4-6 h following heat treatment. Malformed embryos showed an intense heat shock response for a further 6 h. The levels of induced heat shock proteins were similar in the affected neural tube and in the heart, where neither induced cell death nor malformations were observed.