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Biomedical subjects

A Wenzel

Publications and source records attributed to A Wenzel.

At least 37 records · Page 2Linked to original sources
PubMed1990

Augmented MYCN expression advances the malignant phenotype of human neuroblastoma cells: evidence for induction of autocrine growth factor activity.

Amplification and enhanced expression of the MYCN oncogene are thought to contribute to the development and progression of human neuroblastomas. Here, we have transfected human neuroblastoma cells that harbor a single MYCN gene copy with the human MYCN gene driven by a viral enhancer/promoter, and we have compared the properties of the parental and the transfected cells. The transfected cells show an enhanced expression of the exogenous MYCN gene. Unlike the parental cells, they have acquired an increased proliferative potential, induce tumors in nude mice, grow in soft agar, and require low amounts of exogenous growth factors in order to proliferate. The MYCN-transfected, but not the parental, cells can synthesize and utilize autocrine growth factor activity. These results demonstrate that enhanced MYCN expression contributes to malignant progression of human neuroblastoma cells, conceivably by stimulating the expression of autocrine growth factor activity.

Animals↗
PubMed1990

Diagnostic value of clinical examination for the identification of children in need of orthodontic treatment compared with clinical examination and screening pantomography.

Ninety children in the 5th school grade (means age = 11.9 years) participated in this investigation. As part of the orthodontic screening examination, pantomograms of all children had been performed as a routine procedure. Prior to assessment of the pantomograms each child was assigned to one of the following treatment categories based on clinical examination: -T (no indication for orthodontic treatment), O (observation of dentition development) and +T (indication for orthodontic treatment). Children, in whom clinical symptoms gave rise to a radiographic examination, were selected and their pantomograms assessed. Finally, the pantomograms of all children were interpreted, and the clinically established treatment categories re-evaluated on basis of the findings on the pantomograms. Fifteen children were selected for pantomography, but only one changed treatment category (from O to +T) due to observation of developmentally missing premolars. Three of the children not selected for pantomography changed categories from -T; two to O and one to +T. Clinical examination with selective pantomography was thus able to correctly identify 97 per cent of children in need of immediate orthodontic treatment, while it was able to correctly exclude 94 per cent of the healthy children. On the basis of these results, routine screening pantomography may be omitted.

Anodontia↗
PubMed1990

Longitudinal study of accuracy of clinical examination for detection of permanent tooth aplasia.

It was the aim of the present investigation to evaluate the accuracy of clinical examination for the detection of permanent tooth aplasia in the 3rd/4th grade and again 1 yr later and to record the number of children initiating orthodontic treatment in the interval between the two examinations. The validating criterion for tooth aplasia was a panoramic radiograph taken in a routine procedure. 628 children participated in the study. The clinical examinations were performed without knowledge of the radiographic evidence. During the examination children exhibiting symptoms of permanent tooth aplasia were selected for radiography. At both occasions clinical examination was very sensitive for the detection of children with aplasia of permanent incisors (nosological sensitivity = 1.00). It was, however, less sensitive for the detection of children with premolar aplasia (nosological sensitivity = 0.22 at both examinations). The nosological specificity for identification of children without aplasia of incisors and premolars was more than 0.90 at both examinations. Twenty-two children had started orthodontic treatment in the timespan between the two clinical examinations, but only three on the basis of observations on their radiographs alone (aplasia of permanent teeth). The present clinical method would have selected two of these children, thus in only one child postponing panorama screening might have affected treatment prognosis. Between the two examinations all permanent teeth mesial to the permanent second molars had erupted in 181 children who might therefore totally avoid screening radiography.

Adolescent↗
PubMed1990

Oral radiographic screening in Danish children.

The aim of the present study was to ascertain frequency and type of radiographic screening in the Danish Dental Service for children. A 5-item questionnaire was sent to each department of public dentistry in the 275 communities of Denmark. A total of 269 questionnaires were returned, four unanswered. Radiographic screening examinations were done on 162 respondents. Of these, 25% had bitewing screening and 25% panoramic screening. Two types of routine radiographic examinations were performed on more than one third of the respondents. The most frequent combination for screening radiography was bitewing and panorama. Even though the risks included in the use of ionizing radiation for dental screening purposes may be considered negligible, it is still ethically correct to avoid unnecessary exposure by a careful selection of patients prior to radiography. As economic support for dental health care had been cut, the radiographic screening procedure must prove itself to be cost/effective to be kept unchanged.

Child↗
PubMed1990

Depth of occlusal caries assessed clinically, by conventional film radiographs, and by digitized, processed radiographs.

Occlusal caries depth was assessed in 47 extracted premolars and permanent molars by 4 observers on a rank scale by eye inspection, by film radiographs, and by 2 of the observers also by digitized radiographs after filtering and contrast enhancement of the image. Quantitative estimates of caries depth were obtained from the digitized radiographs. Accuracy of scorings was determined with the histologic section as validating criterion. Occlusal caries was present in a spectrum from incipient fissure decalcification to large cavity formation. Clinical as well as radiographic scorings most frequently under-estimated lesion depth. Accuracy of radiographic assessments increased substantially by digital processing of the radiographic image. Quantitative measures of caries depth on digitized radiographs were strongly correlated to the histologic measures (r = 0.91). Interobserver agreement was fair to moderate according to kappa coefficients for the clinical and the radiographic scorings. The agreement was highest for the scorings of the digitally enhanced images. The study suggests that digital processing of radiographic images constitutes a diagnostic aid that may give a more accurate estimate of occlusal caries depth.

Analog-Digital Conversion↗
PubMed1989

Antigenic differences between metastatic and nonmetastatic BSp73 rat tumor variants characterized by monoclonal antibodies.

Variants AS and ASML of the BSp73 rat tumor differ markedly with respect to morphology and to the capacity for spontaneous metastasis via the lymphatics. Monoclonal antibodies (MAbs) were raised in order to identify surface molecules associated with both phenotypes. Mice were immunized with either whole cells or isolated membranes and hybridoma supernatants were screened according to the criteria of selective binding to cultured cells of the variant used for immunization. Of two MAbs reacting with the nonmetastasizing AS variant, one showed immunostaining of AS tissue. From 11 MAbs binding to the metastatic ASML variant, 6 showed specific staining of ASML tissue, while the remaining 5 MAbs showed cross-reaction with normal rat tissues. According to Western blot data, the 6 MAbs selectively binding to ASML tissue identified at least 2 different antigens, one of them showing up as a complex of 12 bands.

Animals↗
PubMed1989

Changes in condyle position after bilateral vertical ramus osteotomy with and without osteosynthesis.

The purpose of the present study was to elucidate the importance of ramal osteosynthesis and evaluate postoperative condylar movements. The right temporomandibular joints of 53 patients with mandibular prognathism were examined by linear tomography the day before, 1 week after, and 1 year after surgery. During surgery the patients were randomly allocated to two groups: one with (n = 26) and one without (n = 27) osteosynthesis. It was found that osteosynthesis did not influence condyle position (p greater than 0.3). The two groups were thereafter pooled. Radiographic measurements of the posterior and anterior interarticular space revealed that condyle position 1 week postoperatively was forward and downward in relation to the preoperative position (posterior fossa, p less than 0.001; anterior fossa, p less than 0.01). One year later the condyle position demonstrated a tendency to approximate the preoperative position, especially with respect to the posterior part, but there was still a significant (p less than 0.01) difference when related to the original position. In conclusion, osteosynthesis after ramus osteotomy seems to be of no importance when healing and postoperative condyle position are considered. Furthermore, 1 year after surgery the condyles were not reestablished in their preoperative positions.

Adolescent↗
PubMed1989

Relationships of changes in craniofacial morphology, head posture, and nasopharyngeal airway size following mandibular osteotomy.

The aim of the present study was to illustrate a possible relationship between changes in craniofacial morphology after mandibular osteotomy and changes in head posture and nasopharyngeal airway size. The material comprised standardized profile cephalograms of 52 patients with mandibular prognathism, all of whom underwent orthodontic adjustment before mandibular osteotomy. Mean age of the patients was 24.3 years; 12 men and 40 women participated in the study. The first profile radiograph of each patient was taken 1 day before surgical treatment in the natural head (mirror) position. All patients underwent mandibular surgery with a bilateral vertical ramus osteotomy. The cephalometric investigation was repeated approximately 1 year after the surgical procedure (means = 1.12 years). Craniofacial morphology was evaluated by 12 parameters describing sagittal and vertical jaw relationship. Head posture was evaluated by the craniocervical angulation and airway as nasopharyngeal airway size. Pearson's correlation analysis was used to evaluate the relationship between morphology, posture, and airway size before surgery and changes in these parameters after surgery. Before surgical treatment statistically significant correlations were found between posture and many morphologic variables, mostly mandibular. Small correlations were observed between posture and airway size, and airway size and morphology. After the surgical procedure, changes in posture were still related to changes in mandibular morphology, while other correlations between posture and morphology had been eliminated. Changes in nasopharyngeal airway size were not correlated to any changes in morphology, apart from maxillary prognathism, nor to changes in posture. The results indicated that mandibular morphology and function play a significant role in determining head posture.

Adolescent↗
PubMed1989

Changes in head posture and nasopharyngeal airway following surgical correction of mandibular prognathism.

It was the aim of the present study to cast light on the role of the mandible in relation to head posture and airway space by evaluating patients before and after surgical correction of mandibular prognathism. The material comprised standardized profile cephalograms of 52 patients with mandibular prognathism. All patients had received orthodontic adjustments prior to mandibular osteotomy. Mean age of the patients was 24.3 years, and 12 males and 40 females participated in the study. The first profile radiograph of each patient was obtained the day before surgery in the natural head (mirror) position. All patients underwent mandibular surgery with a bilateral vertical ramus osteotomy. Approximately one year after surgery, the cephalometric investigation was repeated. Head posture was evaluated by the craniocervical angulation (NSL/CVT and NSL/OPT) and airway space as nasopharyngeal airway size (ad1 and ad2). Changes in posture and airway (ex.2-ex.1) were evaluated by paired t-tests. The results showed a mean increase in head posture of 2.7 degrees (p less than 0.001) and a mean reduction in airway space of 2.3 mm (p less than 0.001).

Adolescent↗
PubMed1989

Panoramic screening for dental anomalies assessed by professionals with identical and different backgrounds.

The aim of the present study was to evaluate how dental professionals with identical and different backgrounds assess dental anomalies viewed on panoramic radiographs. 101 panoramic radiographs performed of 9-to-10-yr-old children were examined independently by three orthodontists and two radiologists. All observers agreed on the recording of number and identification of congenitally missing permanent teeth. The observers' assessments of malpositioned teeth, teeth in infraocclusion, and primary teeth with atypical/non root resorption varied, however, to a great extent. Two of the orthodontists seemed to report only major deviations from normality (in 38 and 51 of the children respectively) while one reported several more findings (in 85 children). The radiologists reported abnormal findings in 80 and 88 children respectively. In only three children were no dental anomalies reported by any observer. The inconsistent reporting of the majority of dental anomalies (except for agenesis) in children, even among members of subgroups with a similar educational background (e.g. orthodontists), substantiates the need for an evaluation of the expedience of panoramic screening.

Anodontia↗
PubMed1989

Effect of manual compared with reference point superimposition on image quality in digital subtraction radiography.

The aim of this study was to compare a new subtraction program based on positioning of reference points (RP) in the two images with the classic manual (M) superimposition of the images during recording. The experiments were performed on 22 dry mandibles from domestic pigs. A bone chip was prepared from the cortex with seven edges: 0.26, 0.30, 0.36, 0.42, 0.49, 0.55 and 0.72 mm thick respectively. Each mandible was radiographed at 0 degrees vertical angulation without the bone chip. The bone chip was then fixed to the lingual plate for a series of radiographs during which the vertical angulation was varied from 0 degrees to 10 degrees at 1 degree intervals. After completion of this series of exposures, amalgam fillings were placed in the two molars on the right side and a second series obtained. The radiographs were digitized (512 x 512 x 8 bit resolution), stored in a personal computer and then subtracted in a random order by the two methods. The RP method was found to be superior to the M method for all the angulations evaluated; as the images were more homogeneous as shown by the smaller SD in the grey-scale histogram. The best results were obtained on images with amalgam-filled teeth. Significantly more bone edges were seen with the RP method, especially when amalgam fillings were present. The RP method may therefore be superior to the M in clinical trials using subtraction radiography.

Animals↗
PubMed1989

Sialic acid, galactose and fucose on the surface of Ehrlich ascites tumor cells grown in glucose-free medium in the presence of uridine.

1) The content and accessibility of terminal sialic acid and galactose residues as well as the incorporation of [3H]fucose into glycoconjugates were determined in 48-h cultures of Ehrlich ascites tumor cells in a glucose-free medium supplemented with uridine, a compound which can fulfil the necessary functions of glucose. 2) Sialic-acid residues accessible to sialidase cleavage were reduced from 695 +/- 80 nmol/10(9) cells (controls) to 284 +/- 22 nmol/10(9) cells (43% of controls). In situ labeling using periodate oxidation followed by sodium borotritiide reduction revealed a tritium incorporation of 47 +/- 11% that of controls (= 4.1 x 10(5) cpm/mg protein). 3) Labeling of galactose residues of 80-90% of that of controls was achieved after treatment of the cells with galactose oxidase/sodium borotritiide. A nearly six-fold enhancement of tritium incorporation into galactose of control cells was observed after sialidase/galactose oxidase treatment and sodium borotritiide reduction (1.5----8.8 x 10(5) cpm/mg protein); only a 3.6-fold increase (1.2 x 10(5)----4.3 x 10(5) cpm/mg protein) was found with glucose-free cultured cells. It is concluded that the galactose content of the cell surface is reduced to about 50% of controls. 4) The incorporation of tritium into acid-insoluble precipitate after 24 h incubation with [3H]fucose and the activity of the acid-soluble fraction were enhanced by about 85% as compared to controls. The pattern of inhibition by tunicamycin of [3H]fucose uptake and incorporation was the same in glucose-containing standard medium and in glucose-free uridine medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Effect of image enhancement for detectability of bone lesions in digitized intraoral radiographs.

Digital image enhancement is concerned with the computer-controlled manipulation of image information. The aim of this study was to evaluate whether diagnostic accuracy would improve in digitally enhanced images of radiographs with impaired density. Each of 83 dry mandibles was divided into four regions. By random assignment it was decided for each region whether or not a hole should be drilled. Three intraoral radiographs (3 x 4 cm) were performed of each region at different exposure times: 2.0 s, 0.60 s, and 0.16 s and interpreted. The radiographs were thereafter recorded by a video camera connected to an IBM-PC. The personal computer held a hardware digitization card defined at a 512 x 512 x 8 matrix resolution on the basis of which a software program with image enhancement facilities was developed. The light and dark radiographs were digitally enhanced by the use of contrast stretching and smoothing filters. The light (0.16 s) original radiographs were less accurate than the ones with optimal density (0.60 s) while no significant differences were found between dark (2.0 s) and optimal density original radiographs. No significant differences were found between original and digitized radiographs of optimal density and digitally enhanced images of light or dark radiographs. The diagnostic accuracy obtained from optimal density radiographs can thus be maintained in digitized dark radiographs and in light radiographs with a four-times dose reduction after digital image enhancement.

Animals↗