Search PubMed⌕ Search

Biomedical subjects

J M Nauta

Publications and source records attributed to J M Nauta.

At least 19 recordsLinked to original sources
PubMed2000

[Team approach in maxillofacial oncology].

The most frequent malignant tumour in the head and neck region this area is the squamous cell carcinoma of the upper aerodigestive tract. In the Netherlands the incidence of these tumours is low, about 2000 new cases a year. Multidisciplinary treatment of these tumours is mandatory because of the extension of the lesion in the area of other disciplines. The variety of diagnostic and therapeutic possibilities and the supportive care ask for a multidisciplinary approach. The low incidence of head and neck cancer in the Netherlands and the complexity of the treatment of these tumours were the reason to concentrate the care for these patients in multi disciplinary head and neck cancer centres.

Cancer Care Facilities↗
PubMed1999

Carbon dioxide laser evaporation of leukoplakia of the lower lip: a retrospective evaluation.

The purpose of this study was the retrospective evaluation of the treatment results of CO2 laser evaporation for 27 cases of leukoplakia of the lip. The data were derived from 23 patients who presented with leukoplakia of the lower lip during the period 1978-96. Four patients developed a second primary leukoplakia of the lip resulting in 27 cases of leukoplakia. All lesions were treated with a CO2 laser equipped with an operation microscope and micromanipulator. Short-term evaluation showed complete epithelialisation 4 weeks after CO2 laser evaporation; there was minimal scar formation and no subsequent interference with normal lip function. During long-term evaluation, four recurrences (14.8%) were diagnosed which developed between 5 and 31 months after treatment, these were retreated with CO2 laser evaporation. There was no development of squamous cell carcinoma in the CO2 laser-treated area. Selective removal of affected epithelium with minimal damage to surrounding structures is possible using CO2 laser evaporation, followed by excellent wound healing and good functional result. Treatment can be performed under local anaesthesia on an outpatient basis. The recurrence rate is low compared with the recurrence rate after surgical excision. Therefore, CO2 laser evaporation is considered a reliable and effective treatment modality for leukoplakia of the lip.

Aged↗
PubMed1998

Efficacy of a synthetic polymer saliva substitute in reducing oral complaints of patients suffering from irradiation-induced xerostomia.

OBJECTIVE: A saliva substitute based on polyglycerylmethacrylate, lactoperoxidase, and glucose oxidase (Oral Balance) has been developed. The aim of this study was to evaluate the effect of Oral Balance on the dryness-related oral complaints in patients suffering from irradiation-induced xerostomia. METHOD AND MATERIALS: The efficacy of Oral Balance on the dryness-related complaints of 28 patients was assessed by means of self-administered questionnaires. Each patient completed an initial questionnaire about dryness-related symptoms and then was given the moistening gel. The patients were instructed to apply the gel as often as desired. After 2 weeks and 3 months, the patients were asked to complete a progress questionnaire. The severity of xerostomia was measured with a saliva absorption method. RESULTS: All patients suffered from moderate-to-severe xerostomia, the severity of which did not change during the experimental period. Three patients did not complete the study. In the other 25 patients, the application of Oral Balance tend to diminish the sensation of oral dryness and improve oral functioning. Statistically significant reduction of the dryness-related complaints was observed only in the patients suffering from severe xerostomia. CONCLUSION: Use of Oral Balance is of potential benefit in patients suffering from severe xerostomia.

Aged↗
PubMed1997

Photofrin-mediated photodynamic therapy of chemically-induced premalignant lesions and squamous cell carcinoma of the palatal mucosa in rats.

Photodynamic therapy (PDT), an experimental cancer therapy, was studied in an animal model of chemically-induced epithelial dysplasia and squamous cell carcinoma. PDT was performed 24 hours after i.v. injection of 2.5 mg/kg bw Photofrin, and using 100 J/cm2 incident light at two activation wavelengths (514.5 nm or 625 nm). Two days after PDT, the majority of rats macroscopically showed a marked erythema of the entire palatal region. Microscopically all the rats showed oedema, haemorrhage, and necrosis of the epithelium of the intermolar area. The long-term results were not so favourable. No evidence of disease was found in 6 out of 20 rats in the 514.5 nm group and in 2 out of 20 rats in the 625 nm treated group. Epithelial dysplasia was found in 14 out of 20 rats in the 514.5 nm group, and in 18 out of 20 rats of the 625 nm treated group. Squamous cell carcinomas were found in 4 out of 20 rats treated with 514.5 nm and in 7 out of 20 rats in the 625 nm treated groups. Comparing both treatment wavelengths, better results were obtained in the 514.5 nm groups as this wavelength gave less normal tissue damage. Based on the results of this study the application of PDT for the treatment of field cancerization and squamous cell carcinoma of the oral cavity, is discussed.

4-Nitroquinoline-1-oxide↗
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↗
PubMed1997

Distribution of aluminum phthalocyanine disulfonate in an oral squamous cell carcinoma model. In vivo fluorescence imaging compared with ex vivo analytical methods.

Photosensitizer-induced fluorescence is studied as a technique for the detection of cancer. Therefore we investigated the ability of a photosensitizer, aluminum phthalocyanine disulfonate (AIPcS2), to localize in tumor tissue. In vivo endoscopic fluorescence imaging, fluorescence microscopy, conventional spectrofluorometry and high performance liquid chromatograpy combined with diode laser-induced fluorescence (HPLC-Dio-LIF) were used. Squamous cell carcinomas were induced with 4-nitro-quinoline-1-oxide (4NQO) in the mucosa of the palate of the rat. In vivo fluorescence images, taken after injection of 1.5 mumol/kg AIPcS2 intravenously, showed that 4NQO-treated palates had higher fluorescence signals than normal palates. Areas displaying locally high amounts of AIPcS2 fluorescence (hot spots) were present only in 4NQO-treated rats 2-8 h but had disappeared 24 h after injection. However, HPLC-Dio-LIF showed that the relative AIPcS2 content was highest at 24/48 h in biopsies taken in the areas of the hot spots. Fluorescence microscopy revealed that AIPcS2 was present only between 2 and 8 h in the epithelial layer, while in biopsies the connective tissue contained large quantities of AIPcS2 at 24/48 h. In vivo fluorescence imaging appears to show mainly fluorescence from the epithelial layer and the ex vivo analytical techniques mainly show the connective tissue fluorescence. Care should be taken when interpreting data using one technique only.

Animals↗
PubMed1996

In vivo fluorescence kinetics and localisation of aluminum phthalocyanine disulphonate in an autologous tumour model.

Sulphonated phthalocyanines are studied as photosensitizers for photodynamic therapy of cancer. Their strong fluorescence and tumour-localising properties make them also potentially useful for detection of cancer by fluorescence. For this purpose, we have studied the fluorescence kinetics and localisation of aluminum phthalocyanine disulphonate (AlPcS2) in 4-nitroquinoline 1-oxide (4NQO)-induced dysplasia and invasive cancer of the oral mucosa of the hard palate in Wistar albino rats. Twenty-two rats were divided into six groups. Five groups were subjected to a 4NQO application period of 8, 12, 16, 20 or 26 weeks and one was a control group. The dysplasia varied from slight to severe and was correlated with the duration of the application period. All animals received a dose of 1 micromol/kg AlPcS2 i.v. Fluorescence images were recorded via a specially designed 'palatoscope' with excitation at 460 +/- 20 nm for autofluorescence, 610 +/- 15 nm for AlPcS2 fluorescence and detection of emission at 675 +/- 15 nm. After subtraction of the two images the specific AlPcS2 fluorescence remained. AlPcS2-mediated fluorescence increased significantly when the severity of dysplasia increased (P<0.04). Also the phenomenon of strong fluorescent spots on the fluorescence images was observed. This always occurred within the first 10 h after injection of AlPcS2. Histological analysis showed a local alteration to a mucosa in 67% of these spots, which was either invasive cancer (29%) or inflammation (38%). These results suggest two different mechanisms of AlPcS2 uptake in tissue, one associated with the presence of generalised dysplasia and another associated with local changes of the epithelial/connective tissue, which is not necessarily specific for tumours.

4-Nitroquinoline-1-oxide↗
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↗
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↗
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

[Peripheral facial nerve palsy].

There are different etiological factors concerning the acute peripheral facial nerve palsy. In the majority of the cases, however, no etiological factor can be found. These cases are called idiopathic facial palsy or Bells palsy. Perhaps local anaesthetics could play a role as an etiological factor. By means of a case-report this form of facial nerve palsy will be discussed.

Anesthetics, Local↗
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

[Relations of human papillomavirus and lesions of the oral mucosa].

Recently there has been an increased interest in the possible role that viruses and especially the Human Papilloma virus (HPV) could play in the etiology of lesions of the oral mucosa. A distinction has to be made between the so-called low-risk types of the virus (HPV-2, 6, 11, 13 and 32) which can be found in benign oral mucosal lesions, and the high-risk type (HPV-16), which predominantly is found in malignant oral mucosal lesions.

Humans↗