Biomedical subjects

A Vermey

Publications and source records attributed to A Vermey.

At least 37 records · Page 2Linked to original sources

PubMed1997

In vivo photo-detection of chemically induced premalignant lesions and squamous cell carcinoma of the rat palatal mucosa.

Photo-detection using in vivo fluorescence was studied for different stages of chemically induced premalignant lesions and squamous cell carcinoma (SCC) of the Wistar rat palatal mucosa. It was found that the epithelial dysplasia (numerically expressed in the epithelial atypia index (EAI) of the rat palate, induced by repeated application of the carcinogen 4-nitroquinoline 1-oxide (4NQO), showed an increase approximately proportional to the duration of the application period. Photo-detection of the lesions using Photofrin-induced fluorescence was studied with dual-wavelength excitation and the subtraction of images, in an attempt to reduce the autofluorescence. The Photofrin dose was 2.5 mg kg-1. This was based on a dose-response study for normal tissue damage by photodynamic therapy (PDT) in this animal model, because the underlying rationale was to study photo-detection as a method of locating additional (early) malignancies in patients treated by PDT. Fluorescence intensities 24 and 48 h after injection of Photofrin were shown to increase with the duration of 4NQO application and with increasing EAI. For an EAI greater than 15, there was a statistically significant difference (p < 0.01) between the fluorescence signals obtained with and without the injection of Photofrin. Fluorescence signals of these lesions without the use of Photofrin (autofluorescence) also showed an increase with increasing stages of epithelial dysplasia of the rat palate. However, the fluorescence signals obtained with Photofrin were always higher than those of the autofluorescence. From this study, we conclude that photo-detection with Photofrin has potential in distinguishing chemically induced premalignant lesions and squamous cell carcinomas from the normal rat palatal mucosa. Photofrin (2.5 mg per kg of body weight) certainly adds to the sensitivity of photo-detection, but autofluorescence alone also has promising features for detecting premalignant and malignant lesions of the oral mucosa.

4-Nitroquinoline-1-oxide↗

PubMed1996

Poly(L-lactide) bone plates and screws for internal fixation of mandibular swing osteotomies.

This study evaluated bone healing after mandibular swing osteotomies fixed with biodegradable poly(L-lactide) (PLLA) bone plates in four patients. A step osteotomy treated with two PLLA bone plates (n=3), and a straight osteotomy treated with one PLLA bone plate (n=1) were performed. Bone healing was uneventful in all patients; only in the patient with the straight osteotomy was callus observed. After 5.5 years, radiologic changes at the site of implantation were observed in the remaining patient. Histologic examination revealed a nonspecific foreign-body reaction on highly crystalline PLLA remnants which were still present. It is concluded that the PLLA bone plates provided enough strength to enable undisturbed bone healing. The long-term degradation results are comparable with those of other studies on as-polymerized PLLA implants.

Biodegradation, Environmental↗

PubMed1996

Photodynamic therapy of oral cancer. A review of basic mechanisms and clinical applications.

Photodynamic therapy (PDT) is an experimental cancer treatment modality. PDT is based on the accumulation of a photosensitive dye in premalignant and malignant lesions. A certain period of time after the dye has been administered, tumor tissue may contain more of the sensitizer then the surrounding normal tissues. When tissue containing the sensitizer is exposed to light of a proper wavelength and dose, a photochemical reaction between sensitizer and light will occur. The activated photosensitizer reacts with available oxygen which subsequently damages cells and eventually may cause necrosis of the tumor. Photosensitizers can also be used for fluorescence detection. If a tumor contains more of the photosensitizer than the surrounding normal tissue, its fluorescence can potentially be utilized to detect tumors. Analogous to PDT, this can therefore be referred to as photodynamic detection (PDD). This paper reviews the basic mechanisms and clinical applications of PDT and PDD. Emphasis is placed on PDD and PDT with the photosensitizer Photofrin for detection and treatment of premalignant epithelial lesions and squamous cell carcinomas of the oral mucosa.

Carcinoma, Squamous Cell↗

PubMed1996

Extensive mutation scanning of RET in sporadic medullary thyroid carcinoma and of RET and VHL in sporadic pheochromocytoma reveals involvement of these genes in only a minority of cases.

Sporadic medullary thyroid carcinoma (MTC) and pheochromocytoma (PC) have been reported to be associated with some specific RET gene mutations. To assess the role of RET in the development of MTC and PC, we screened 14 sporadic MTC, two MTC-derived cell lines, and 5 sporatic PC cases of RET mutations by a systematic analysis of the whole coding sequence, including all intron-exon junctions. In only 6 of the 14 sporadic MTC we were able to detect a RET mutation. Apart from the MET918-->Thr mutation in 5 of the MTC cases, we found a 3-bp deletion in exon 11, only present in the tumor, in another case. Analysis of 2 cell lines revealed the Met918-->Thr mutation in 1 and a Cys634-->Trp mutation in the other cell line. A possible somatic nature of these mutations could not be confirmed because in neither case was constitutive DNA available. We conclude that a large proportion of sporadic MTC must be due to mutations in an unidentified gene(s) other than RET. In none of the sporadic PC cases was a RET mutation found. As PC is a frequent complication in families suffering from von Hippel Lindau disease, for which mutations of the VHL gene are responsible, we also screened the 5 sporadic PC cases for VHL mutations. This revealed a Gly164-->Ser mutation in a single specimen. Thus, in PC, a large majority of tumors are due to mutations in an unidentified gene(s) other than RET and VHL.

Adrenal Gland Neoplasms↗

PubMed1996

[Treatment of mouth cancer. General principles as well as surgical aspects].

An overview is presented of the various treatment modalities in head and neck cancer, the emphasis being on oral cancer. Evaluation of the neck with regard to the possible presence of regional lymph node metastases is an integral part of the examination and treatment of patients with oral cancer. A strong plea is made for a multidisciplinary approach in the treatment and rehabilitation of this patient group.

Head and Neck Neoplasms↗

PubMed1996

Nodal spread of squamous cell carcinoma of the oral cavity detected with PET-tyrosine, MRI and CT.

UNLABELLED: The uptake of L-1-[11C]-tyrosine (TYR) in cervical lymph nodes of eleven patients with squamous-cell carcinoma (SCC) of the oral cavity was studied with PET to detect lymphogenic metastases. METHODS: The TYR-PET results were compared with clinical, MRI, CT, histopathologic findings and historical data of patients studied with FDG. Sensitivity, specificity, accuracy and the positive and negative predictive values were calculated. RESULTS: TYR-PET had sensitivity of 83% and a specificity of 95%. In contrast, the sensitivity and specificity for MRI were 33% and 96%, respectively. The sensitivity and specificity for CT were 55% and 91%, respectively. TYR-PET results compared favorably with FDG. CONCLUSION: With TYR-PET, SCC metastases of the oral cavity can be visualized with high sensitivity and specificity. TYR-PET can be an additional tool for further evaluation of neck malignancies.

Aged↗

PubMed1995

An important role for chromosome 17, band q25, in the histogenesis of alveolar soft part sarcoma.

A cytogenetic study of two cases of alveolar soft part sarcoma showed near-diploid karyotypes with multiple chromosomal rearrangements. An abnormality of the long arm of chromosome 17, involving band q25, is present in both cases and in 2 of 4 cases in the literature. This recurrent structural abnormality probably plays an important role in the histogenesis of this unusual neoplasm and therefore is important for further molecular investigation.

Adult↗

PubMed1995

Aggressive fibromatosis (non-familial desmoid tumour): therapeutic problems and the role of adjuvant radiotherapy.

Aggressive fibromatosis is a rare soft tissue tumour with a high tendency to local recurrence, even after apparently adequate resection. Wide local excision with a margin of at least 3 cm, depending on the anatomical location, should be performed to improve rates of recurrent disease. There is no consensus concerning the role of radiotherapy in the treatment of these lesions. The clinical findings of 39 cases diagnosed between 1972 and 1991 were reviewed retrospectively. Local control was effected in 19 of 32 patients treated with surgery alone after a median (range) follow-up of 72 (18-236) months. There were 40 cases of recurrent fibromatosis in 15 patients. Local control was obtained in 13 of 14 patients who received radiotherapy using a wide-field technique and doses of more than 50 Gy over a period of 5 weeks after marginal or incomplete resection of primary or recurrent lesions (P < 0.001). The results suggest that in a selected group of patients with aggressive fibromatosis radiotherapy may effectively achieve control of residual disease after surgery without marked disfigurement and loss of function.

Adult↗

PubMed1995

Total thyroidectomy in the treatment of thyroid carcinoma in childhood.

Between 1974 and 1993 ten girls and six boys aged 6-16 years underwent total thyroidectomy, with therapeutic selective neck dissection in six patients. All were treated after operation with radioactive iodine (131I) for ablation of thyroid tissue remnants. Papillary carcinoma occurred in ten patients, follicular carcinoma in two and medullary thyroid lesions in four. The patients were followed for a median of 11.5 (range 1-20) years with regular determinations of serum thyroglobulin levels and 131I whole-body scanning when indicated. Only one patient had a slight increase in thyroglobulin levels without evidence of disease on further screening. In children with medullary lesions the serum levels of basal and pentagastrin-stimulated calcitonin remained normal. Currently all patients are alive and without disease. Hypocalcaemia lasting for more than 1 year was observed in one patient. Recurrent nerves were not injured accidentally, but because of tumour invasion two of 32 recurrent nerves had to be sacrificed. This surgical approach is safe and well tolerated in children.

Adolescent↗

PubMed1995

Comparison of epithelial dysplasia--the 4NQO rat palate model and human oral mucosa.

Epithelial dysplasia in the rat palatal mucosa was induced by application three times a week of the carcinogen 4-nitroquinoline 1-oxide (4NQO). With the Epithelial Atypia Index (EAI), the successive stages of 4NQO-induced epithelial dysplasia were compared with specimens of human oral epithelial dysplasia. It appeared that there was a close similarity between the histologic features of 4NQO-induced dysplasia in the rat palatal mucosa and human oral epithelial dysplasia. Thus, the 4NQO rat palate model seems to be appropriate to study and assess new treatment modalities of premalignant epithelial lesions of the oral mucosa in man.

4-Nitroquinoline-1-oxide↗

PubMed1995

Hereditary medullary thyroid carcinoma.

The most well-known form of familial thyroid cancer is hereditary medullary thyroid carcinoma (MTC). This neoplasm is often associated with pheochromocytoma and hyperparathyroidism, a combination known as the multiple endocrine neoplasia syndrome type 2A (MEN 2A). The rare association of MTC and pheochromocytoma with multiple mucosal neuromas is called multiple endocrine neoplasia syndrome type 2B (MEN 2B). Of those who present with clinical signs and symptoms, almost half die of the disease and others may suffer significant morbidity. By contrast, early diagnosis by screening of family members allows for treatment with thyroidectomy and/or adrenalectomy, which are often curative. Measurement of serum calcitonin before and after stimulation with pentagastrin and/or calcium is mandatory for the diagnosis of MTC. Testing of first-degree relatives of patients with MTC should be started by the age of 3 to 5 years. In families with the MEN 2B syndrome, screening should be started during the first year after birth and include a search for the characteristic phenotype. The mapping of the MEN 2A gene to the centromeric region of chromosome 10 has provided an alternative approach to the diagnosis of MEN 2A gene carriers. Genetic screening using linked markers can now be done with an accuracy of 95% in informative families. Surgery is the treatment of choice for cases of MEN 2, but the extent of surgical resection of the involved endocrine organs is still a subject of debate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1995

Detection of lymph node metastases of squamous-cell cancer of the head and neck with FDG-PET and MRI.

UNLABELLED: The uptake of 2-deoxy-2-[18F]fluoro-D-glucose (FDG) in neck lymph nodes of twelve patients with a squamous-cell carcinoma of the oral cavity was studied with PET in order to detect and locate lymphogenic metastases. METHODS: The results of FDG-PET imaging were compared with clinical, MRI and histopathologic findings. Standardized uptake values (SUV) were also calculated. RESULTS: A sensitivity of 91% and a specificity of 88% were calculated for FDG-PET. In contrast, a sensitivity of 36% and a specificity of 94% were calculated for MRI. Calculated SUVs for reactive lymph nodes, metastatic lymph nodes and the primary tumor were undifferentiated. CONCLUSION: Using FDG-PET, lymph node metastases of squamous-cell carcinomas of the oral cavity can be visualized with a high sensitivity and specificity. FDG-PET can be an improvement in the evaluation of the neck.

Aged↗

PubMed1994

[Prevention of oral cancer].

Etiology control is the most important primary prevention of oral cancer. The use of tobacco and alcohol increases the risk of a squamous cell carcinoma of the oral mucosa. The dentist can play an important role in the secondary prevention or screening for premalignant lesions, asymptomatic malignancies and second primary tumours of the oral cavity. Because of their age, edentulous patients run a high risk of oral cancer. Therefore, a regular oral check-up of these patients should be recommended.

Age Factors↗

PubMed1993

Posterolateral neck dissection: technique and results.

Posterolateral neck dissection, alone or combined with a modified radical neck dissection, may be an appropriate method of treating occult and clinically manifest nodal metastases of malignant epithelial tumours of the skin of the posterior scalp. The technique and results are described in 21 patients treated between February 1981 and November 1989. Transformation of nodal status from cN0 to pN+ was seen in five of 13 patients treated electively, who may benefit from such a procedure. During a mean follow-up of 47 months the disease was controlled locally in all patients. Three patients suffered regional recurrence of whom only one had a nodal recurrence within the region previously operated on. The results of this limited retrospective study confirm the value of posterolateral neck dissection in posterior scalp lesions.

Adult↗

PubMed1992

Protocol for the prevention and treatment of oral sequelae resulting from head and neck radiation therapy.

In addition to the desired antitumor effects, head and neck radiation therapy induces damage in normal tissues that may result in oral sequelae such as mucositis, hyposalivation, radiation caries, taste loss, trismus, soft-tissue necrosis, and osteoradionecrosis. These sequelae may be dose-limiting and have a tremendous effect on the patient's quality of life. Current policies to prevent these sequelae primarily are based on clinical experience and show great diversity. A protocol for the prevention and treatment of oral sequelae resulting from head and neck radiation therapy, based on fundamental research and data derived from the literature, is presented. The protocol is particularly applicable in centers with a dental team. This team should be involved at the time of initial diagnosis so that a successful preventive regimen is an integral part of the overall cancer treatment regimen.

Clinical Protocols↗

PubMed1992

A survey of prevention and treatment regimens for oral sequelae resulting from head and neck radiotherapy used in Dutch radiotherapy institutes.

Radiation treatment plays an important role in the management of head and neck cancer. Unfortunately several radiation-induced side effects may occur including mucositis, hyposalivation, radiation caries, trismus and osteoradionecrosis. It is generally accepted that most side effects can be prevented or reduced in severity. The purpose of this investigation was to make a survey of the prevention and treatment regimens for oral sequelae resulting from head and neck radiotherapy applied in all radiotherapy institutes in the Netherlands, and to evaluate the differences in these regimens. In all Dutch centers (n = 20) in which irradiation of head and neck cancer patients is performed, members of the staff responsible for prevention and treatment of oral side effects were interviewed. Questions referred to composition of the dental team, screening and care pre-irradiation, care during irradiation, and care post-irradiation. There appeared to be a great diversity in the preventive approach of the head and neck cancer patient in Dutch radiotherapy institutes. The most comprehensive counseling was performed by those centers in which a dental team was active, particularly when an oral hygienist was a member of such a team. The diversity is among others based on lack of well-defined guidelines in many centers, the spread of a relatively small patient group over a rather large number of centers, absence of a dental team in some centers, absence of an oral hygienist in some dental teams, and the observation that a rather large number of patients were not referred, or not timely referred to the dental team. There seems to be a need for the development of a general protocol for the prevention of oral complications applicable in all centers.

Dental Caries↗

PubMed1992

Peripheral ameloblastoma. A case report and review of the literature.

Peripheral ameloblastoma is a benign odontogenic tumor with the same histological characteristics as the centrally located ameloblastoma, but appearing in the gingiva and mucosa of the tooth-bearing area of the jaws. A review is presented of 53 cases: 45 being reported as peripheral ameloblastoma and 8 as basal cell carcinoma of the gingiva, including the case presented. Based on the review it is recommended to treat this lesion by local excision including a small margin of healthy tissue. Local recurrence is unlikely, unless incomplete removal is performed.

Adult↗

PubMed1992

Malignant parotid tumors: clinical use of MR imaging and histologic correlation.

Magnetic resonance (MR) imaging was performed in 116 patients in whom a parotid mass lesion was clinically suspected. Eighty-six patients had benign disease. The 30 patients in whom a malignant tumor was found were further evaluated. To determine which features are characteristic of malignant parotid tumors, spin-echo T1- and T2-weighted images of malignant lesions in the parotid gland were compared with those of benign disease. In our series, tumor margins, homogeneity, or signal intensity were not discriminative factors to correctly predict benign or malignant disease. Infiltration into deep structures (eg, the parapharyngeal space, muscles, and bone) was observed only in malignant tumors. Infiltration into subcutaneous fat was noticed in malignant as well as in inflammatory disease. No statistically significant correlation was found between tumor grade and MR imaging features in malignant disease. MR imaging is useful in delineating malignant tumors but is unreliable in correctly predicting the histologic nature of a mass lesion in the parotid gland.

Adult↗