Kit-positive interstitial cells in the rabbit urethra: structural relationships with nerves and smooth muscle.

OBJECTIVE: To identify interstitial cells (ICs) in the wall of the rabbit urethra using antibodies to the Kit receptor, and to examine their location, morphology and relationship with nerves and smooth muscle cells (SMCs), as studies of enzymatically isolated cells from the rabbit urethra have established that there are specialized cells that show spontaneous electrical activity and have morphological properties of ICs. MATERIALS AND METHODS: Urethral tissues from rabbits were fixed, labelled with antibodies and examined with confocal microscopy. Some specimens were embedded in paraffin wax and processed for histology. Histological sections from the most proximal third and mid-third region of rabbit urethra were stained with Masson's Trichrome to show their cellular arrangement. RESULTS: Sections from both regions had outer longitudinal and inner circular layers of SM, and a lamina propria containing connective tissue and blood vessels; the lumen was lined with urothelial cells. The mid-third region had a more developed circular SM layer than the most-proximal samples, and had extensive inner longitudinal SM bundles in the lamina propria. Labelling with anti-Kit revealed immunopositive cells within the wall of the rabbit urethra, in the circular and longitudinal layers of the muscularis. Double-labelling with an antibody to SM myosin showed Kit-positive cells on the boundary of the SM bundles, orientated parallel to the axis of the bundles. Others were in spaces between the bundles and often made contact with each other. Kit-positive cells were either elongated, with several lateral branches, or stellate with branches coming from a central soma. Similar cells could be labelled with vimentin antibodies. Their relationship with intramural nerves was examined by double immunostaining with an anti-neurofilament antibody. There were frequent points of contact between Kit-positive cells and nerves, with similar findings in specimens double-immunostained with anti-neuronal nitric oxide synthase (nNOS). CONCLUSION: Kit-positive ICs were found within the SM layers of the rabbit urethra, in association with nerves, on the edge of SM bundles and in the interbundle spaces. The contact with nNOS-containing neurones might imply participation in the nitrergic inhibitory neurotransmission of the urethra. PMID: 17212607 [PubMed - indexed for MEDLINE]

Clinical implementation of dynamic multileaf collimation for compensated bladder treatments.

BACKGROUND AND PURPOSE: To describe the clinical implementation of dynamic multileaf collimation (DMLC). Custom compensated four-field treatments of carcinoma of the bladder have been used as a simple test site for the introduction of intensity modulated radiotherapy.MATERIALS AND METHODS: Compensating intensity modulations are calculated from computed tomography (CT) data, accounting for scattered, as well as primary radiation. Modulations are converted to multileaf collimator (MLC) leaf and jaw settings for dynamic delivery on a linear accelerator. A full dose calculation is carried out, accounting for dynamic leaf and jaw motion and transmission through these components. Before treatment, a test run of the delivery is performed and an absolute dose measurement made in a water or solid water phantom. Treatments are verified by in vivo diode measurements and real-time electronic portal imaging. RESULTS: Seven patients have been treated using DMLC. The technique improves dose homogeneity within the target volume, reducing high dose areas and compensating for loss of scatter at the beam edge. A typical total treatment time is 20 min. CONCLUSIONS: Compensated bladder treatments have proven an effective test site for DMLC in an extremely busy clinic.

A comparison of conformal and intensity-modulated techniques for oesophageal radiotherapy.

Background and purpose: To investigate the potential of intensity-modulated radiotherapy (IMRT) to reduce lung irradiation in the treatment of oesophageal carcinoma with radical radiotherapy.Materials and methods: A treatment planning study was performed to compare two-phase conformal radiotherapy (CFRT) with IMRT in five patients. The CFRT plans consisted of anterior, posterior and bilateral posterior oblique fields, while the IMRT plans consisted of either nine equispaced fields (9F), or four fields (4F) with orientations equal to the CFRT plans. IMRT plans with seven, five or three equispaced fields were also investigated in one patient. Treatment plans were compared using dose-volume histograms and normal tissue complication probabilities.Results: The 9F IMRT plan was unable to improve on the homogeneity of dose to the planning target volume (PTV), compared with the CFRT plan (dose range, 16.9+/-4.5 (1 SD) vs. 12.4+/-3.9%; P=0.06). Similarly, the 9F IMRT plan was unable to reduce the mean lung dose (11.7+/-3.2 vs. 11.0+/-2.9 Gy; P=0.2). Similar results were obtained for seven, five and three equispaced fields in the single patient studied. The 4F IMRT plan provided comparable PTV dose homogeneity with the CFRT plan (11.8+/-3.3 vs. 12.4+/-3.9%; P=0.6), with reduced mean lung dose (9.5+/-2.3 vs 11.0+/-2.9 Gy; P=0.001).Conclusions: IMRT using nine equispaced fields provided no improvement over CFRT. This was because the larger number of fields in the IMRT plan distributed a low dose over the entire lung. In contrast, IMRT using four fields equal to the CFRT fields offered an improvement in lung sparing. Thus, IMRT with a few carefully chosen field directions may lead to a modest reduction in pneumonitis, or allow tumour dose escalation within the currently accepted lung toxicity.

The impact of virtual simulation in palliative radiotherapy for non-small-cell lung cancer.

Background and purpose: Radiotherapy is widely used to palliate local symptoms in non-small-cell lung cancer. Using conventional X-ray simulation, it is often difficult to accurately localize the extent of the tumour. We report a randomized, double blind trial comparing target localization with conventional and virtual simulation.Methods: Eighty-six patients underwent both conventional and virtual simulation. The conventional simulator films were compared with digitally reconstructed radiographs (DRRs) produced from the computed tomography (CT) data. The treatment fields defined by the clinicians using each modality were compared in terms of field area, position and the implications for target coverage.Results: Comparing fields defined by each study arm, there was a major mis-match in coverage between fields in 66.2% of cases, and a complete match in only 5.2% of cases. In 82.4% of cases, conventional simulator fields were larger (mean 24.5+/-5.1% (95% confidence interval)) than CT-localized fields, potentially contributing to a mean target under-coverage of 16.4+/-3.5% and normal tissue over-coverage of 25.4+/-4.2%.Conclusions: CT localization and virtual simulation allow more accurate definition of the target volume. This could enable a reduction in geographical misses, while also reducing treatment-related toxicity.

Optimisation of radiotherapy for carcinoma of the parotid gland: a comparison of conventional, three-dimensional conformal, and intensity-modulated techniques

Background and purpose: To compare external beam radiotherapy techniques for parotid gland tumours using conventional radiotherapy (RT), three-dimensional conformal radiotherapy (3DCRT), and intensity-modulated radiotherapy (IMRT). To optimise the IMRT techniques, and to produce an IMRT class solution.Materials and methods: The planning target volume (PTV), contra-lateral parotid gland, oral cavity, brain-stem, brain and cochlea were outlined on CT planning scans of six patients with parotid gland tumours. Optimised conventional RT and 3DCRT plans were created and compared with inverse-planned IMRT dose distributions using dose-volume histograms. The aim was to reduce the radiation dose to organs at risk and improve the PTV dose distribution. A beam-direction optimisation algorithm was used to improve the dose distribution of the IMRT plans, and a class solution for parotid gland IMRT was investigated.Results: 3DCRT plans produced an equivalent PTV irradiation and reduced the dose to the cochlea, oral cavity, brain, and other normal tissues compared with conventional RT. IMRT further reduced the radiation dose to the cochlea and oral cavity compared with 3DCRT. For nine- and seven-field IMRT techniques, there was an increase in low-dose radiation to non-target tissue and the contra-lateral parotid gland. IMRT plans produced using three to five optimised intensity-modulated beam directions maintained the advantages of the more complex IMRT plans, and reduced the contra-lateral parotid gland dose to acceptable levels. Three- and four-field non-coplanar beam arrangements increased the volume of brain irradiated, and increased PTV dose inhomogeneity. A four-field class solution consisting of paired ipsilateral coplanar anterior and posterior oblique beams (15, 45, 145 and 170o from the anterior plane) was developed which maintained the benefits without the complexity of individual patient optimisation.Conclusions: For patients with parotid gland tumours, reduction in the radiation dose to critical normal tissues was demonstrated with 3DCRT compared with conventional RT. IMRT produced a further reduction in the dose to the cochlea and oral cavity. With nine and seven fields, the dose to the contra-lateral parotid gland was increased, but this was avoided by optimisation of the beam directions. The benefits of IMRT were maintained with three or four fields when the beam angles were optimised, but were also achieved using a four-field class solution. Clinical trials are required to confirm the clinical benefits of these improved dose distributions.

Advanced glycation end products accumulate in the reproductive tract of men with diabetes

Light microscopic studies comparing sperm parameters show little association between diabetes and male fertility. However, with the introduction of new analytical techniques, evidence is now emerging of previously undetectable effects of diabetes on sperm function. Specifically, a recent study has found a significantly higher sperm nuclear DNA fragmentation in diabetic men. As advanced glycation end products (AGEs) are important instigators of oxidative stress and cell dysfunction in numerous diabetic complications, we hypothesized that these compounds could also be present in the male reproductive tract. The presence and localization of the most prominent AGE, carboxymethyl-lysine (CML), in the human testis, epididymis and sperm was determined by immunohistochemistry. Parallel ELISA and Western blot analyses were performed to ascertain the amount of CML in seminal plasma and sperm from 13 diabetic and nine non-diabetic subjects. CML immunoreactivity was found throughout the seminiferous epithelium, the nuclei of spermatogonia and spermatocytes, in the basal and principle cells cytoplasm and nuclei of the caput epididymis and on most sperm tails, mid pieces and all cytoplasmic droplets. The acrosomal cap, especially the equatorial band, was prominently stained in diabetic samples only. The amount of CML was significantly higher (p = 0.004) in sperm from non-diabetic men. Considering the known detrimental actions of AGEs in other organs, the presence, location and quantity of CML, particularly the increased expression found in diabetic men, suggest that these compounds may play a hitherto unrecognized role in male infertility.