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Biomedical subjects

N de Vries

Publications and source records attributed to N de Vries.

At least 19 recordsLinked to original sources
PubMed2006

[Hyoidothyroidopexy as a surgical treatment for obstructive sleep apnoea syndrome].

OBJECTIVE: To evaluate the results ofhyoidothyroidopexy (HTP) in patients with obstructive sleep apnoea syndrome (OSAS). DESIGN: Prospective, descriptive. METHOD: Data were collected on patients with moderate to severe OSAS that underwent HTP between 1 March 2000 and 30 June 2004 in the St. Lucas Andreas Hospital in Amsterdam. All patients had an obstruction at the level ofthe base ofthe tongue and, to a lesser degree, the palate and either refused the use of continuous positive airway pressure (CPAP) or were unable to tolerate this treatment. The following scores were calculated preoperatively and 3 months after the operation: the apnoeahypopnoea index (AHI), apnoea index, Epworth sleepiness scale, desaturation index and visual analogue scores for hypersomnolence, snoring and pain sensation. RESULTS: During the period under investigation, 31 patients underwent HTP: 29 men and 2 women. Of these, 14 had never been operated before at the oral or hypopharyngeal level (average age: 47 years; average BMI: 26.3) and 17 had undergone unsuccessful uvulopalatopharyngoplasty (average age: 46.3 years; average BMI: 27.7). Of the 31 patients, 16 (52%) had a significant decrease in the AHI, especially those in the primary HTP-group (10/14 or 71% vs. 6/17 or 35% in the secondary group, p > 0.05). The average AHI decreased from 32.9 to 11.9 (p = 0.006) in the primary group and from 31.5 to 26.2 (p = 0.06) in the secondary group. Most of the secondary outcome measures improved statistically significantly in both groups. In one patient, tracheotomy was performed due to postoperative bleeding that threatened to obstruct the respiratory tract. CONCLUSION The short-term results of HTP as the primary treatment in patients with moderate to severe OSAS could be characterised as favourable.

English Abstract↗
PubMed2005

[Surgical treatment of obstructive sleep-apnoea syndrome].

5 patients, 4 males aged 41, 32, 52 and 49 years and 1 female aged 57 years, suffered from socially unacceptable snoring and hypersomnolence in the daytime. They were evaluated for obstructive sleep-apnoea syndrome. After polysomnography and sleep endoscopy was performed to establish the severity of the sleep-apnoea syndrome and the level(s) of upper airway obstruction, a patient-specific treatment was performed. Conservative therapy with continuous positive airway pressure (CPAP) was refused by 4 patients, while 1 patient discontinued therapy after complaints of nose obstruction. This patient underwent radiofrequency thermotherapy (RFTT) of the inferior turbinates. The other patients underwent uvulopalatopharyngoplasty (UPPP), RFTT of the soft palate, hyoidthyroidpexia (HTP) and 'multilevel' surgery: UPPP, HTP and RFTT of the tongue base, respectively. All patients showed improvement after surgery. Although its longterm effects are not yet known, surgical treatment is an option for patients with obstructive sleep-apnoea syndrome who cannot or will not undergo CPAP.

Adult↗
PubMed2002

[A thyroglossal duct cyst with ectopic thyroid carcinoma].

An asymptomatic swelling in the neck of a 15-year-old boy, was revealed after resection to be due to a papillary thyroid carcinoma. He was treated with a near-total thyroidectomy, radiotherapy at an ablation dosage due to a scintigraphically demonstrated remnant thyroid tissue, and thyroid hormone supplement. Almost 2 years after the tumour resection, a recurrent carcinoma was found in the neck. Prior to the resection of symptomatic thyroglossal duct cysts, it should be ascertained whether nodular thyroid abnormalities are present. In about 1% of resected thyroglossal duct cysts a carcinoma is found, most often of the papillary type. In 10-40% of the patients who undergo a subsequent thyroidectomy, malignant focuses are also found in the thyroid. In view of this multifocal occurrence and the fact that in most cases the diagnosis of carcinoma is only made after the operation, which often implies uncertainty about oncological radicalness, the authors advice to perform a (near-)total thyroidectomy as the standard procedure in case of thyroglossal duct carcinoma. After this adequate treatment with 131I should be given. A more limited approach seems only warranted when radicalness is certain and indications for nodular thyroid disease are absent.

Adolescent↗
PubMed2001

Identification of environmental stress-regulated genes in Helicobacter pylori by a lacZ reporter gene fusion system.

BACKGROUND: Helicobacter pylori persists in the human stomach for decades. This requires an efficient adaptation of H. pylori to the gastric niche and involves the regulation of bacterial genes in response to environmental stress. Efficient molecular tools to identify regulated H. pylori genes are scarce, therefore we developed a genomic lacZ reporter gene fusion system in H. pylori to screen for stress-regulated genes. MATERIALS AND METHODS: The integration vector pBW was constructed and used to generate random genomic lacZ fusions in H. pylori. Two-hundred-and-fifty H. pylori transformants were selected from this library, replica-plated and screened for differential lacZ expression after exposure to two environmental stress conditions: increased temperature (42 degrees C), and iron-limitation. RESULTS: From a library of H. pylori transformants with random genomic transcriptional lacZ fusions, two stress-regulated H. pylori loci were identified. The transcription of a gene of unknown function (designated hsp12) was increased by incubation at 42 degrees C. The transcription of a locus, consisting of the three fumarate reductase subunit genes (frdCAB) and the HP0190 gene from H. pylori strain 26695, was decreased under iron-limitation. CONCLUSIONS: This is the first time that a genomic transcriptional lacZ reporter gene H. pylori library has been used as a tool for the fast and efficient identification of environmental stress-regulated H. pylori genes.

Bacterial Proteins↗
PubMed2001

Modified sharp method: factors influencing reproducibility and variability.

BACKGROUND AND OBJECTIVES: In rheumatoid arthritis, joint radiography is still the most frequently used instrument to assess the progression of joint damage. Unfortunately, the poor quality of the radiographic scoring methods available has a negative impact on the power in clinical trials. This study focuses on the influence of the following 4 factors on radiographic scores according to van der Heijde's modification of the Sharp method: intraobserver variation, interobserver variation, follow-up time, and number of measurement occasions within a patient series. METHODS: One hundred and seventy-two patients in the early stages of rheumatoid arthritis were followed up. During the first 3 years, radiographs of the hands and feet were taken twice yearly and scored by 3 observers. The scoring process was repeated after an additional 3-year period. Correlation coefficients and differences between observers were calculated to define variability. The influence of the 4 factors on variability was studied. RESULTS: One observer assigned a significantly higher score than the other 2, who had been trained together. Interobserver variability decreased as follow-up time increased. Interobserver correlation coefficients became higher, with smaller differences between observers for progression scores than for absolute scores. Increasing the number of measurements within a patient series led to higher scores. Intraobserver correlation coefficients were high, and a training effect occurred when the time between measurements was 1 year, resulting in lower scores. CONCLUSIONS: This study demonstrates that, and shows how, the investigated factors influence the variability of the modified Sharp method. It is extremely important to take interobserver variation into account when designing protocols for multicenter clinical trials. A progression scoring method is recommended for studies assessing radiographic damage or clinical trials.

Arthritis, Rheumatoid↗
PubMed2001

Nickel-responsive induction of urease expression in Helicobacter pylori is mediated at the transcriptional level.

The nickel-containing enzyme urease is an essential colonization factor of the gastric pathogen Helicobacter pylori, as it allows the bacterium to survive the acidic conditions in the gastric mucosa. Although urease can represents up to 10% of the total protein content of H. pylori, expression of urease genes is thought to be constitutive. Here it is demonstrated that H. pylori regulates the expression and activity of its urease enzyme as a function of the availability of the cofactor nickel. Supplementation of brucella growth medium with 1 or 100 microM NiCl(2) resulted in up to 3.5-fold-increased expression of the urease subunit proteins UreA and UreB and up to 12-fold-increased urease enzyme activity. The induction was specific for nickel, since the addition of cadmium, cobalt, copper, iron, manganese, or zinc did not affect the expression of urease. Both Northern hybridization studies and a transcriptional ureA::lacZ fusion demonstrated that the observed nickel-responsive regulation of urease is mediated at the transcriptional level. Mutation of the HP1027 gene, encoding the ferric uptake regulator (Fur), did not affect the expression of urease in unsupplemented medium but reduced the nickel induction of urease expression to only twofold. This indicates that Fur is involved in the modulation of urease expression in response to nickel. These data demonstrate nickel-responsive regulation of H. pylori urease, a phenomenon likely to be of importance during the colonization and persistence of H. pylori in the gastric mucosa.

Bacterial Proteins↗
PubMed2000

EUROSCAN, a randomized trial of vitamin A and N-acetylcysteine in patients with head and neck cancer or lung cancer. For the EUropean Organization for Research and Treatment of Cancer Head and Neck and Lung Cancer Cooperative Groups.

BACKGROUND: Preclinical evidence suggests that retinoids and antioxidants may prevent or delay the occurrence of cancer in the upper or lower airways, but such effects have not been reliably established in clinical studies. To assess the chemopreventive effects of vitamin A (retinyl palmitate) and N-acetylcysteine, we conducted a large randomized intervention study in patients with head and neck cancer or with lung cancer, most of whom had a history of smoking. METHODS: From June 1988 through July 1994, a total of 2592 patients (60% with head and neck cancer and 40% with lung cancer) were randomly assigned to receive 1) retinyl palmitate (300000 IU daily for 1 year followed by 150000 IU for a 2(nd) year), 2) N-acetylcysteine (600 mg daily for 2 years), 3) both compounds, or 4) no intervention. All statistical tests were two-sided. RESULTS: Of the patients, 93.5% had smoked tobacco at sometime in their lives (and 25% continued to smoke after cancer diagnosis). After a median follow-up of 49 months, 916 patients were reported with an event (recurrence, second primary tumor, or death). No statistically significant difference was observed in overall survival or event-free survival between patients who received retinyl palmitate and patients who did not. Similarly, no difference was seen in overall survival or event-free survival between patients who received N-acetylcysteine and patients who did not. There was a lower incidence of second primary tumors in the no intervention arm, but the difference was not statistically significant. CONCLUSION: A 2-year supplementation of retinyl palmitate and/or N-acetylcysteine resulted in no benefit-in terms of survival, event-free survival, or second primary tumors-for patients with head and neck cancer or with lung cancer, most of whom were previous or current smokers.

Acetylcysteine↗
PubMed1999

No support for HLA-DQ encoded susceptibility in rheumatoid arthritis.

OBJECTIVE: To test predictions based on data from immunogenetic and peptide-binding studies of collagen-induced arthritis in mice, in which it has been suggested that susceptibility to rheumatoid arthritis (RA) might be determined by the interaction between susceptibility alleles at the HLA-DQ locus and protective alleles at the HLA-DRB1 locus (including susceptibility effects for HLA-DQ7 and DQ8). METHODS: Predictions based on these models were tested in 166 healthy controls and 167 patients with RA, all of whom were typed for HLA-DRB1 and HLA-DQ alleles. RESULTS: In this population, HLA-DQ7 did not encode an increased risk for RA. This lack of susceptibility effect of HLA-DQ7 could not be attributed to competing HLA-DQ susceptibility alleles, protective HLA-DRB1 alleles, or the absence of DQA1*0301. CONCLUSION: These observations do not support the DR/DQ hypothesis in its present form.

Alleles↗
PubMed1999

Chemoprevention of head and neck and lung (pre)cancer.

Oral cancer is often preceded by precancerous lesions, the most common of which is leukoplakia. Several treatment modalities are available: elimination of the possible cause, cold knife, laser, or cryosurgery, and topical application of bleomycin and 5-fluorouracil. In research, oral leukoplakia is used as a model to study the value of chemoprevention as a strategy to prevent cancer, because its effect is directly visible and material for analysis is easily obtainable from the mouth. In several studies and chemoprevention trials the efficacy of retinoids, retinol and/or beta-carotene on oral leukoplakia has been demonstrated. Second primary tumors occur in 10-30% of head and neck cancer patients and 10% of lung cancer patients. Chemoprevention offers an attractive approach to combat this threat to such patients, which is bound to cast a shadow over their lives. In the last 10-15 years several chemoprevention studies with vitamin A, retinoids or agents working through other mechanisms (antioxidants) have been launched. The largest chemoprevention study in curatively treated early-stage oral cancer, laryngeal cancer and lung cancer (N = 2595) is EUROSCAN, an EORTC study initiated in 1988. End-points are second tumors, local/regional recurrence and distant metastases, and long-term survival rates. Preminary results will be available in 1998.

Biomarkers, Tumor↗
PubMed1998

New susceptibility locus for rheumatoid arthritis suggested by a genome-wide linkage study.

Rheumatoid arthritis (RA), the most common autoimmune disease, is associated in families with other autoimmune diseases, including insulin-dependent diabetes mellitus (IDDM). Its genetic component has been suggested by familial aggregation (lambdas = 5), twin studies, and segregation analysis. HLA, which is the only susceptibility locus known, has been estimated to account for one-third of this component. The aim of this paper was to identify new RA loci. A genome scan was performed with 114 European Caucasian RA sib pairs from 97 nuclear families. Linkage was significant only for HLA (P < 2.5.10(-5)) and nominal for 19 markers in 14 other regions (P < 0.05). Four of the loci implicated in IDDM potentially overlap with these regions: the putative IDDM6, IDDM9, IDDM13, and DXS998 loci. The first two of these candidate regions, defined in the RA genome scan by the markers D18S68-D18S61-D18S469 (18q22-23) and D3S1267 (3q13), respectively, were studied in 194 additional RA sib pairs from 164 nuclear families. Support for linkage to chromosome 3 only was extended significantly (P = 0.002). The analysis of all 261 families provided a linkage evidence of P = 0. 001 and suggested an interaction between this putative RA locus and HLA. This locus could account for 16% of the genetic component of RA. Candidate genes include those coding for CD80 and CD86, molecules involved in antigen-specific T cell recognition. In conclusion, this first genome scan in RA Caucasian families revealed 14 candidate regions, one of which was supported further by the study of a second set of families.

Arthritis, Rheumatoid↗
PubMed1998

Production of monoclonal antibodies specific for the i and 1,2 flagellar antigens of Salmonella typhimurium and characterization of their respective epitopes.

Salmonella typhimurium expresses two antigenically distinct flagellins, each containing a different H antigen (i and 1,2), the combination of which is highly specific for this serotype. In this study, overlapping recombinant flagellin fragments were constructed from the fliC (H:i) and fljB (H:1,2) flagellin genes, and the expression products were tested for binding to H antigen-specific monoclonal and polyclonal antibodies. A minimal area, 86 amino acids for H:i and 102 amino acids for H:1,2, located in the central variable domain of each flagellin was required for the binding of serotype-specific antibodies, providing further evidence for the presence of a discontinuous H epitope. Two peptides comprising these areas were shown to be highly suitable for application as antigens in an enzyme-linked immunosorbent assay detecting S. typhimurium-specific antibody.

Antibodies↗
PubMed1997

HLA-DRB1 in eight Finnish monozygotic twin pairs concordant for rheumatoid arthritis.

This study presents the results of HLA-DRB1 typing of the eight monozygotic twin pairs with both members affected by rheumatoid arthritis (RA), sampled in the nationwide Finnish twin cohort. The shared epitope, associated with RA in case-control studies, was present in all eight twin pairs, being significantly more frequent than among RA patients in a recent Dutch case-control study. Furthermore, 4 out of 8 twin pairs were homozygous for the shared epitope, while in 73 Dutch healthy controls encoding the shared epitope only 13 (18%) were homozygous: this suggests a gene dose effect in RA susceptibility. Combining these results with data from other sources may help to clarify the contribution of HLA alleles in the genetic predisposition to RA.

Arthritis, Rheumatoid↗
PubMed1996

Potential early markers of carcinogenesis in the mucosa of the head and neck using exfoliative cytology.

Patients with head and neck squamous cell carcinoma (HNSCC) who are thought to be cured are at high risk of development of a secondary primary tumour in the mucosa of the upper aerodigestive tract and the lungs. This phenomenon is in agreement with the concept of 'field cancerization', which implies that the whole mucosa is potentially condemned to the development of neoplasia. The hypothesis advanced in this study was that early markers of carcinogenesis should therefore be present in all cells of the mucosa of patients with HNSCC. The expression of cytokeratin 16, cytokeratin 19, and histo-blood group antigen H (ABH), type 2 chain was analysed by means of immunocytochemistry on exfoliated cells taken from six sites of the upper aerodigestive tract of the 'healthy' mucosa of previously untreated HNSCC patients (n = 25) and controls (n = 10). Statistically significant differences were found in the mucosal expression of these markers between patients and controls. Since no overlap in ABH type 2 chain expression existed between patients and controls and the expression between sites in a given individual was highly correlated, this marker was considered the most promising of those tested. These data suggest that cytokeratin 16, cytokeratin 19, and ABH type 2 chain are markers of field cancerization in easily available exfoliated cells, which may be applied to monitor and/or predict the occurrence of second primary tumours.

ABO Blood-Group System↗
PubMed1995

Role of genetic factors in the etiology of squamous cell carcinoma of the head and neck.

OBJECTIVE: To determine the role of genetic predisposition in the etiology of head and neck squamous cell carcinoma. DESIGN: Retrospective study. SETTING: The outpatient clinics of the departments of otorhinolaryngology and maxillofacial surgery. PATIENTS: First-degree relatives of patients with new head and neck cancer, with first-degree relatives of the patients' spouses as controls. MAIN OUTCOME MEASURE: Occurrence of cancer of the respiratory and upper digestive tract in relatives of patients with head and neck cancer and controls. RESULTS: First-degree relatives (n = 617) of 105 patients with head and neck cancer had 31 cases of cancer of the respiratory and upper digestive tract vs 10 cases in the control group (n = 618) (relative risk, 3.5; P = .0002). This higher rate of cancer was even larger in siblings (16 vs 2, relative risk, 14.6; P = .0001). CONCLUSIONS: Genetic predisposition is an important risk factor for squamous cell carcinoma of the head and neck.

Carcinoma, Squamous Cell↗
PubMed1995

A new biochemical assay in the diagnostic management of nasal cerebrospinal fluid leakage.

A new method for the detection of cerebrospinal fluid (CSF) leakage is described, and is a refinement of the method originally reported by Oberascher and Arrer in 1986. Immuno-electrophoretic measurements are performed in a two-buffer system, making the test easier to do and providing qualitatively better images. Genetic variants of transferrin (which has a general population incidence of 2-4%) can be discriminated from false-positive test results in affected families. The test described is recommended as the method of choice for initial screening of suspected CSF leakage.

Adult↗
PubMed1995

Antioxidant-related parameters in patients treated for cancer chemoprevention with N-acetylcysteine.

N-acetylcysteine (NAC) is an antioxidant, possibly effective in the early steps of carcinogenesis, and is applied to prevent second primary tumours in the upper aerodigestive tract and the lungs. In this study, we evaluated the pharmacodynamic profile of 600 mg NAC treatment, given daily for 3 months. Treatment caused a significant increase of the non-protein-SH concentration in blood plasma (38%) and erythrocytes (31%). Glutathione levels in exfoliated buccal mucosa cells appeared not to be influenced by treatment. The total radical-trapping ability parameter (TRAP) of blood plasma showed no change. In vitro, the addition of glutathione, but not of NAC did increase the TRAP value. In addition, when peroxyl radicals were generated in vitro, NAC was shown to be consumed more rapidly than glutathione. This suggests that NAC prevents early damage, while glutathione functions over a longer time period.

Aged↗