Biological characterization of a novel in vitro cell irradiator

To evaluate the overall robustness of a novel cellular irradiator we performed a series of well-characterized, dose-responsive assays to assess the consequences of DNA damage. We used a previously described novel irradiation system and a traditional ¹³⁷Cs source to irradiate a cell line. The generation of reactive oxygen species was assessed using chloromethyl-H₂DCFDA dye, the induction of DNA DSBs was observed using the comet assay, and the initiation of DNA break repair was assessed through γH2AX image cytometry. A high correlation between physical absorbed dose and biologic dose was seen for the production of intracellular reactive oxygen species, physical DNA double strand breaks, and modulation of the cellular double stand break pathway. The results compared favorably to irradiation with a traditional ¹³⁷Cs source. The rapid, straightforward tests described form a reasonable approach for biologic characterization of novel irradiators. These additional testing metrics go beyond standard physics testing such as Monte Carlo simulation and thermo-luminescent dosimeter evaluation to confirm that a novel irradiator can produce the desired dose effects in vitro. Further, assessment of these biological metrics confirms that the physical handling of the cells during the irradiation process results in biologic effects that scale appropriately with dose.

Induction of macrophage migration inhibitory factor precedes the onset of acute tonsillitis

We investigated the serum macrophage migration inhibitory factor (MIF) levels of palmoplantar pustulosis patients, before and after the tonsillar provocation test. Higher serum MIF levels of palmoplantar pustulosis patients were decreased after the tonsillar provocation test (n=29). To confirm these phenomena, two patients with acute tonsillitis had their changes in body temperature, C-reactive protein (CRP) and serum MIF levels examined during the course of their illness. Surprisingly, increased MIF preceded fever and CRP elevation, and MIF subsequently decreased at the onset of fever and CRP elevation. Since MIF is an initiator of other proinflammatory cytokines, we suggest that the induction of MIF may precede other inflammatory conditions.

Dysphagia and aspiration after chemoradiotherapy for head-and-neck cancer: which anatomic structures are affected and can they be spared by IMRT?

PURPOSE

To identify the anatomic structures whose damage or malfunction cause late dysphagia and aspiration after intensive chemotherapy and radiotherapy (RT) for head-and-neck cancer, and to explore whether they can be spared by intensity-modulated RT (IMRT) without compromising target RT.

METHODS AND MATERIALS

A total of 26 patients receiving RT concurrent with gemcitabine, a regimen associated with a high rate of late dysphagia and aspiration, underwent prospective evaluation of swallowing with videofluoroscopy (VF), direct endoscopy, and CT. To assess whether the VF abnormalities were regimen specific, they were compared with the VF findings of 6 patients presenting with dysphagia after RT concurrent with high-dose intra-arterial cisplatin. The anatomic structures whose malfunction was likely to cause each of the VF abnormalities common to both regimens were determined by literature review. Pre- and posttherapy CT scans were reviewed for evidence of posttherapy damage to each of these structures, and those demonstrating posttherapy changes were deemed dysphagia/aspiration-related structures (DARS). Standard three-dimensional (3D) RT, standard IMRT (stIMRT), and dysphagia-optimized IMRT (doIMRT) plans in which sparing of the DARS was included in the optimization cost function, were produced for each of 20 consecutive patients with advanced head-and-neck cancer.

RESULTS

The posttherapy VF abnormalities common to both regimens included weakness of the posterior motion of the base of tongue, prolonged pharyngeal transit time, lack of coordination between the swallowing phases, reduced elevation of the larynx, and reduced laryngeal closure and epiglottic inversion, contributing to a high rate of aspiration. The anatomic structures whose malfunction was the likely cause of each of these abnormalities, and that also demonstrated anatomic changes after RT concurrent with gemcitabine doses associated with dysphagia and aspiration, were the pharyngeal constrictor muscles (median thickness near midline 2.5 mm before therapy vs. 7 mm after therapy; p = 0.001), the supraglottic larynx (median thickness, 2 mm before therapy vs. 4 mm after therapy; p < 0.001), and, similarly, the glottic larynx. The constrictors and the glottic and supraglottic larynx were, therefore, deemed the DARS. The lowest maximal dose delivered to a stricture volume was 50 Gy. Reducing the volumes of the DARS receiving > or =50 Gy (V(50)) was, therefore, a planning and evaluation goal. Compared with the 3D plans, stIMRT reduced the V(50) of the pharyngeal constrictors by 10% on average (range, 0-36%, p < 0.001), and doIMRT reduced these volumes further, by an additional 10% on average (range, 0-38%; p <0.001). The V(50) of the larynx (glottic + supraglottic) was reduced marginally by stIMRT compared with 3D (by 7% on average, range, 0-56%; p = 0.054), and doIMRT reduced these volumes by an additional 11%, on average (range, 0-41%; p = 0.002). doIMRT reduced laryngeal V(50) compared with 3D, by 18% on average (range 0-61%; p = 0.001). Certain target delineation rules facilitated sparing of the DARS by IMRT. The maximal DARS doses were not reduced by IMRT because of their partial overlap with the targets. stIMRT and doIMRT did not differ in target doses, parotid gland mean dose, spinal cord, or nonspecified tissue maximal dose.

CONCLUSIONS

The structures whose damage may cause dysphagia and aspiration after intensive chemotherapy and RT are the pharyngeal constrictors and the glottic and supraglottic larynx. Compared with 3D-RT, moderate sparing of these structures was achieved by stIMRT, and an additional benefit, whose extent varied among the patients, was gained by doIMRT, without compromising target doses. Clinical validation is required to determine whether the dosimetric gains are translated into clinical ones.

Involvement of tonsils in IgA nephropathy

This study was intended to clarify the involvement of tonsils in the pathogenesis of IgA nephropathy. In 62 patients with IgA nephropathy and 20 patients with other renal diseases, their tonsils were stimulated by an ultra short wave. Forty of 62 patients with IgA nephropathy (65%) showed a deterioration of urinary findings after the stimulation compared with six of 20 patients with other renal diseases (30%). Previous episodes of gross hematuria following upper respiratory tract infections existed in 17 of 40 patients (Group A) who showed a deterioration of urinary findings after tonsil stimulation (43%) as against in four of 22 (Group B) without the deterioration (18%). The level of serum secretory IgA was higher in Group A than in Group B. It is suggested that chronic tonsillitis may play an important role in the development of IgA nephropathy. Thirty-six patients received tonsillectomy from 1980-2002. The frequency of gross hematuria at upper respiratory infection decreased in 56% of the patients The amount of urinary protein decreased in 33% of the patients and RBC counts decreased in 56% of the patients Eight patients with tonsillectomy were followed up longer than 16 years Two of them went to hemodialysis and five of them showed no urinary abnormalities at present. The effect of tonsillectomy in the long term was not clarified in this study.

[Late effects of long-term exposure to low-dose ionizing radiation on lymphoid pharyngeal system in children]

The examination of 468 children and adolescents estimated frequency and structure of chronic pathology of the pharyngeal ring in long-term exposure to low-dose radiation. Chronic disease of the tonsils and adenoids was detected in 194 children (45.4%). Chronic tonsillitis was diagnosed in 142 (33.3%) examinees. 31.7 and 59.9% cases had compensated and subcompensated disease. Decompensated process took place in 8.5% cases of chronic tonsillitis. Hypertrophy of the palatine tonsils and adenoids was detected in 96 (22.5%) children. High incidence of lymphadenopathy of the neck in combination with chronic tonsillitis and tonsil and adenoid hypertrophy was found. Structure of chronic pathology of the lymphoid pharyngeal ring correlated with internal radiation dose. Comparison of postnatally and antenatally radiated children demonstrated less frequent incidence of affected lymphoid pharyngeal ring in children born before the Chernobyl accident.

A clinical feature associated with polymorphisms of the TNF region in Japanese patients with palmoplantar pustulosis

We investigated the association of polymorphisms in the tumor necrosis factor (TNF) microsatellite as well as the promoter region of the TNFA gene and the TNFB gene with palmoplantar pustulosis (PPP). In order to clarify the heterogeneity of this disease, we performed a tonsillar provocation test on 78 patients and divided them into two groups according to the results; provocation positive (PP; n = 38) and provocation negative (PN; n = 40). We found that the phenotype frequency of the TNFB2 allele of the TNFB gene in the PN group was significantly higher than in controls (p = 0.0022, corrected p = 0.0044). There was also a significant increase in the frequency of allele B of the TNFA gene (TNFApB) in the PN group when compared with controls (p = 0.0049, corrected p = 0.025). Although there are no significant differences in the frequency of TNFa microsatellites, the frequency of the TNFd7 allele increased and that of the TNFd4 allele decreased in the PN group. An extended haplotype analysis revealed that the TNFd7-TNFApA-TNFB2 haplotype was more frequent in the PN group, implying that the PN group is associated with a low level of TNF-alpha production. These results indicate that detection of polymorphisms at the TNF locus may be a marker for determination of the heterogeneity of the disease, and that the allelic variation may influence the susceptibility.

Optical-thermal simulation of tonsillar tissue irradiation

BACKGROUND AND OBJECTIVE

Despite laser applications targetted toward tonsillar tissue, there has been no characterization of underlying optical and thermal events during laser irradiation of tonsillar tissue.

STUDY DESIGN/MATERIALS AND METHODS

The optical properties of canine and human tonsils were determined at 805 nm (diode laser) and 1,064 nm (Nd:YAG laser). An optical-thermal simulation was developed to predict the temperature rise in irradiated human tonsils.

RESULTS

The optical properties of human and canine tonsillar tissue are similar at both wavelengths. The optical-thermal simulation was validated and predicts that at 10 W and 1 minute of irradiation, the heat will be contained within the human tonsil. The diode laser causes more superficial heating than the Nd:YAG laser.

CONCLUSIONS

The safety of irradiating human tonsils was shown. The diode laser is superior to the Nd:YAG laser because less heat affects collateral structures. The optical-thermal simulation detailed in this study can be used to predict the temperature rise in tissues undergoing irradiation.

Optical-thermal simulation of human tonsillar tissue irradiation: clinical implications

BACKGROUND AND OBJECTIVE

Mucosa intact laser tonsillar ablation is an alternative to conventional tonsillectomy. The efficacy of this procedure was demonstrated in canines, but establishing the safety of irradiating human tonsils is paramount.

STUDY DESIGN/MATERIALS AND METHODS

An optical-thermal simulation of tonsillar tissue irradiation was previously developed, but the effect of varying parameters was not investigated. The tissue response to irradiation at 5-25 watts for 1 minute and 10 watts for 10 seconds to 162 seconds is simulated.

RESULTS

At 15 watts and greater, the peak temperature is over 100 degrees C and the mucosal temperature is over 70 degrees C. At the depth of the tonsil, the temperature does not vary significantly. The peak temperature is at 1 mm. The radial temperature profile is not significantly altered by longer irradiation times.

CONCLUSIONS

The optimal dosimetry parameters for irradiation of human tonsillar tissue at 805 nm with the MILTA technique is under 15 watts for approximately 1 minute.

Salivary gland tumors after childhood radiation treatment for benign conditions of the head and neck: dose-response relationships

We have investigated the dose-response relationships for the incidence of salivary gland tumors in a cohort of 2945 individuals who were irradiated as children between 1939-1962. Most of the patients were treated to reduce the size of their tonsils and adenoids. The mean dose to the salivary glands (+/-SD) was 4.2 +/- 1.7 Gy. Eighty-nine patients developed 91 salivary gland neoplasms; 22 had single malignancies, 64 had single benign neoplasms, 2 developed two separate benign neoplasms, and 1 developed a single neoplasm but did not have surgery. The majority (81 of 89) of the patients developed neoplasms in the parotid glands. Mucoepidermoid carcinomas were the most common malignancy and mixed (pleomorphic) adenomas were the most common benign neoplasm. For all salivary gland tumors, the excess relative risk per gray (ERR/Gy) was 0.82; however, the 95% confidence interval was wide (0.04, upper bound indeterminate). The trend was determined principally by benign tumors, as there was no dose-response relationship for salivary gland cancer, although there were too few cases to draw definitive conclusions. Overall, our study provides support for an association between salivary gland tumors and radiation exposure. Although most salivary gland tumors are benign and are usually readily detected, they may cause morbidity, and people who have been irradiated in the area should be monitored for their occurrence.

Change induced by radiation therapy in FDG uptake in normal and malignant structures of the head and neck: quantitation with PET

PURPOSE

To quantitate the changes induced in uptake of the glucose analog 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) in normal structures in the head and neck and compare these to the change in uptake in malignant structures in patients with head and neck tumors undergoing radiation therapy.

MATERIALS AND METHODS

Eleven patients with biopsy-confirmed squamous cell carcinoma of the head and neck were studied before, during, and after a 6-week course of radiation therapy with positron emission tomography (PET)-FDG imaging. A ratio of FDG uptake in the structure compared with that in the cerebellum (termed metabolic ratio) within and outside of the field of radiation was determined in the adenoids; lingual and palatine tonsils; parotid, submandibular, and sublingual glands; and nasal turbinates, soft palate, and gingiva.

RESULTS

The average metabolic ratio in the tonsils, nasal turbinates, soft palate, and gingiva did not change significantly with treatment.

CONCLUSION

FDG uptake in normal structures does not change with radiation therapy. This fact is in marked contrast to the FDG uptake in squamous cell carcinomas in the head and neck, which decrease dramatically with treatment (P < .005).

The effect of thin K-edge filters on radiation dose in dental radiography

The use of thin K-edge filters has been found to reduce considerably the radiation dose in intra-oral radiography. The aim of this study was to investigate the effect of filtration on the skin entrance dose and several sites (representing organs or areas of interest within the head) along the central beam axis, at other points within the primary beam and at two points just outside the primary beam. The subject was a sliced head phantom (a human skull embedded in tissue-equivalent material) which was exposed to X rays from a conventional dental X-ray unit in the range of tube voltage 55-85 kVp for each of four filter systems. These were 2.7 mm of aluminium alone (the existing total filtration) or with an added 0.1 mm erbium, 0.1 mm yttrium or 0.05 mm niobium metal foils. Measurements of radiation dose were made using thermoluminescent dosemeters (TLD rods) and were adjusted to simulate the exposure resulting from a typical dental radiograph of a maxillary molar. The results suggest that the use of thin K-edge filters significantly reduces the entrance skin dose and to a certain extent reduces the total dose imparted to the head. However, the dose to the ipsilateral orbit at higher tube voltages may be increased.

Temperature response of biological materials to pulsed non-ablative CO2 laser irradiation

This paper presents surface temperature responses of various tissue phantoms and in vitro and in vivo biological materials in air to non-ablative pulsed CO2 laser irradiation, measured with a thermocamera. We studied cooling off behavior of the materials after a laser pulse, to come to an understanding of heat accumulation and related thermal damage during (super) pulsed CO2 laser irradiation. The experiments show a very slow decay of temperatures in the longer time regime. This behavior is well predicted by a simple model for one-dimensional heat flow that considers the CO2 laser radiation as producing a heat flux on the material surface. The critical pulse repetition frequency for which temperature accumulation is sufficiently low is estimated at about 5 Hz. Although we have not investigated the ablative situation, our results suggest that very low pulse frequencies in microsurgical procedures may be recommended.

[Radiotherapy of tonsillar cancer. II. Tumor repopulation and normal tissue tolerance]

Clinical data of the 72 cases of squamous cell carcinoma of the tonsil irradiated with 60Co (results of treatment presented in the I part of this paper) have been used to analyse the importance of physical and biological factors influencing local control probability and risk of late effects in normal tissues. It was noted, that overall treatment time strongly influences tumour control but is less important for late effect of pharyngeal mucosa. With extension treatment time over 50 days, local control rate decreases dramatically almost to zero. Tumour response is less sensitive to change in dose per fraction than late responding pharyngeal mucosa. This suggestion is supported by high alpha/beta value of 25.0 Gy, calculated for cancer of the tonsil and relatively low alpha/beta value of 1.0 Gy for pharyngeal mucosa. Results suggest that improvement of local control of cancer of the tonsil with no increase in late complication rate might be expected using altered fractionation scheme, eg. accelerated hiperfractionation. This radiation treatment is based on dose per fraction less than 2.0 Gy, given in two fraction per day, in overall treatment time as short as possible.

Childhood irradiation of pharyngeal lymphoid tissue: management considerations

Childhood irradiation to the head and neck increases the probability of developing regional glandular neoplasia. Life-long follow-up of these patients is warranted.

Salivary gland neoplasms as a late consequence of head and neck irradiation

An increased occurrence of salivary tumors was observed in 1922 patients who received radiation to the tonsils and nasopharynx. Twenty-seven tumors, 19 benign and eight malignant, were found in this group as compared with an expected 0.2 malignant and less than 1 benign tumor. The latent period between the initial radiation treatment and diagnosis ranged from 7 to 32 years. After the first 15 years the incidence (77 cases/10(5) subjects/year) has remained constant and shows no indication of declining. Continued observation for salivary gland tumors is therefore indicated for subjects who received childhood irradiation.

Thyroid cancer occurring as a late consequence of head-and-neck irradiation. Evaluation of 1056 patients

From January 1 to September 30, 1974, we examined 1056 of 5266 subjects (20.1%) who had received therapeutic irradiation primarily for infections and inflammatory disease of the upper respiratory tract at our institution during the 1940's and 1950's. The tonsillar and nasopharyngeal region was the treatment site in 85% of those examined. Palpable nodular thyroid disease was found in 16.5%, and nonpalpable lesions were detected by 99m Tc pertechnetate thyroid imaging in an additional 10.7%, for a prevalence of nodular disease of 27.2%. Operation on 71% with nodular disease revealed thyroid cancer in 33% (60 of 182). Preliminary analysis for potential risk factors suggests a correlation between radiation exposure and the presence of thyroid nodules (P less than 0.001). These findings indicate that nodular thyroid disease, both benign and malignant, continues as a major health problem for at least 35 years in exposed subjects.

Carcinoembryonic antigen and humoral antibody response in patients with thyroid carcinoma

Carcinoembryonic antigen and antibodies to thyroglobulin and to a microsomal fraction of thyroid were measured. Persons examined were normal volunteers, patients with thyroid cancer, and patients with a history of childhood irradiation to the thymus and/or tonsil who were otherwise normal. Elevated antigen and antibodies were most frequently found in the cancer thyroid group. Thyroid cancer patients with no previous history of childhood irradiation were more frequently positive for antigen and antibodies than all other categories studied. Thyroid cancer patients with a previous history of childhood irradiation showed normal frequencies of antigen and antibodies. The results suggest that the antigenic expression and host response to the tumor in patients with thyroid cancer depend on its pathogenesis. Mention is made of similar findings in animal model systems.