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Biomedical subjects

A Wenzel

Publications and source records attributed to A Wenzel.

At least 55 records · Page 3Linked to original sources
PubMed2001

Frequency and distribution of endodontically treated teeth and apical periodontitis in an urban Danish population.

AIM: The aim of this study was to investigate the prevalence of endodontically treated teeth and apical periodontitis (AP) in a Danish population. METHODOLOGY: From Aarhus County 614 individuals were radiographically examined, and the frequency of endodontic treatment and periapical status of all teeth were assessed. The year of birth of the subjects ranged from 1935 to 1975. The chi-squared test was used to determine the significance of differences between males and females and amongst age and tooth groups for the following parameters: AP, the number of endodontically treated teeth, and the number of endodontically treated teeth with AP. RESULTS: A total of 15 984 teeth were examined; of these 538 (3.4%) had AP and 773 (4.8%) had been endodontically treated. Of the endodontically treated teeth, 404 (52.2%) had AP. Females had more endodontically treated teeth than males; otherwise, no effect of gender was observed. Significantly more molars (P < 0.01) had been endodontically treated (8.1%) compared to premolars (5.4%) and anterior teeth (2.5%). The prevalence of AP in connection with molars was significantly (P < 0.01) higher (7.0%) than premolars (2.8%) and anterior teeth (1.5%). The prevalence of endodontically treated teeth and of teeth with AP gradually increased with age. CONCLUSIONS: The average number of teeth, the number of teeth with AP and the number of teeth with endodontic treatment in Danish adults were comparable to findings in other European countries. The frequency of endodontically treated teeth with AP was found to be high compared to that demonstrated in other epidemiological studies.

Adult↗
PubMed2001

A comparison of the quality of root canal treatment in two Danish subpopulations examined 1974-75 and 1997-98.

AIM: The aim of this study was to compare the quality of root canal treatment in two Danish subpopulations. METHODOLOGY: Group 1 (358 patients) was examined 1974-75 and group 2 (244 patients) 1997-98. All patients were more than 20 years old. All had undergone a full-mouth radiographic survey. In root-filled teeth the following parameters were assessed: the quality of the coronal restoration or crown, the lateral seal of the root filling, the length of the root filling, and the periapical status. Chi-squared tests were used for the evaluation of differences between the groups. RESULTS: In group 1 there were 975 endodontically treated teeth, in group 2 there were 753. In group 1 the majority of root-filled teeth were premolars, in group 2 the majority were molars (P < 0.001). The quality of coronal restorations (P = 0.35) and crowns (P = 0.68) did not differ significantly between the groups. In group 2 more teeth had adequately sealed root canals (P < 0.001) and adequate length of root filling (P < 0.001). More root-filled molar teeth had apical periodontitis (AP) than root-filled premolar and anterior teeth (P < 0.001). CONCLUSIONS: Whilst the technical quality of endodontic treatment had improved during the last 24 years, basic differences between the populations prevented assessment of the impact of this change on disease frequencies. The study indicates that great care should be taken when comparing different patient populations, in particular more emphasis should be placed on the selection and description of study groups.

Adult↗
PubMed2001

Evaluation of effect of 3D video glasses on perceived pain and unpleasantness induced by restorative dental treatment.

Previous studies on modulation of anxiety, pain and unpleasantness have documented a positive effect of video glasses (I-Glasses, Virtual i-O, Seattle, USA) on the perceived pain and unpleasantness under different laboratory and clinical conditions. The aim of this study was to evaluate whether distraction induced by video glasses also had an effect on the perceived intensity of pain and unpleasantness during dental treatment. Pain and unpleasantness was evoked by the preparation (drilling) of a minor dental cavity (class I). Twenty-three patients (17 female and six male, age range 20-49 years) with a need for an occlusal dental restoration in two homologous teeth participated in the study. In this split-mouth design, the patient received the dental treatment wearing 3D video glasses and without video glasses (control situation) in a randomized order. The tooth cavities were prepared in accordance with conventional techniques after mounting the video glasses. The patient rated the intensity of pain and unpleasantness on 100 mm visual analogue scales (VASs) after preparation of the first cavity; immediately after, the opposite tooth was prepared and again the volunteer rated the intensity of pain and unpleasantness. The cavities were then filled using a routine composite technique. Eventually, the patient indicated whether she would prefer video glasses or not if she were to have another filling and what the expectations of the effect had been. Differences in VAS ratings in the video and control situation were tested by Student's t-test. There was no statistically significant effect on the perceived pain (p=0.90) or unpleasantness (p=0.39), but the majority (74%) of the patients would still prefer to wear video glasses if they were to have another dental filling, and 73% had expected a positive effect of the video glasses. These findings suggest that perceived intensity of dental pain is resistant to a simple distraction technique.

Adult↗
PubMed2001

Impact of conventional tomography on prediction of the appropriate implant size.

AIM: The purpose of this study was to evaluate the efficacy of conventional cross-sectional tomography in predicting the appropriate implant size. METHODS: The implant length and width of 46 patients referred for single tooth implant treatment were determined presurgically by periapical + panoramic images (record 1) and after surgery by periapical + panoramic images + tomograms (record 2). These dimensions were compared with the dimensions of the implants actually installed (record 3), as well as the dimensions assessed to be the "appropriate" ones according to defined criteria for success (record 4). RESULTS: In 70% of the cases, the implant length or width, or both, was changed after the tomogram was available. The implant dimensions determined with tomography were maintained at surgery in 87% of the cases. In only 33% of the cases did the implant size predicted without tomography correspond with the size of the installed implants. The agreement between records 2 and 3 was significantly higher than between records 1 and 3 (P < .001). Similarly, the agreement between records 2 and 4 was significantly higher than between records 1 and 4 (P < .001). CONCLUSIONS: This study demonstrated that the use of tomograms increases the efficacy of periapical + panoramic images, with respect to the prediction of appropriate implant size, by a factor of 2.5. Therefore, conventional cross-sectional tomography is recommended for treatment planning before installation of single tooth implants.

Adult↗
PubMed2001

Protective effect of halothane anesthesia on retinal light damage: inhibition of metabolic rhodopsin regeneration.

PURPOSE: To determine whether the volatile anesthetic halothane protects against light-induced photoreceptor degeneration in the rodent retina. METHODS: Albino mice and rats were anesthetized with halothane and exposed to high levels of white or blue light. Nonanesthetized animals served as controls. Retinal morphology was assessed by light microscopy, and apoptosis of photoreceptor cells was verified by detection of fragmented genomic DNA and in situ staining of apoptotic nuclei (TUNEL assay). Rhodopsin regeneration after bleaching was determined by measuring rhodopsin levels in retinas of mice or rats at different time points in darkness. RESULTS: Halothane anesthesia reversibly inhibited metabolic rhodopsin regeneration and thus prevented rhodopsin from absorbing high numbers of photons during light exposure. Consequently, photoreceptors of mice and rats anesthetized with halothane were completely protected against degeneration induced by white light. In remarkable contrast, however, halothane anesthesia did not protect against blue-light-induced photoreceptor cell death. CONCLUSIONS: After the initial bleach, halothane impeded photon absorption by rhodopsin by inhibiting metabolic rhodopsin regeneration. Apparently, the rhodopsin-mediated uptake of the critical number of photons to initiate white light-induced retinal degeneration was prevented. In contrast, halothane did not protect the retina against blue light. Blue light can efficiently restore functional rhodopsin from bleaching intermediates through a process termed photoreversal of bleaching. This process does not depend on the visual cycle via the pigment epithelium but nevertheless enables rhodopsin molecules to absorb the critical number of photons required to induce retinal degeneration.

Anesthesia, Inhalation↗
PubMed2001

Rhodopsin-mediated blue-light damage to the rat retina: effect of photoreversal of bleaching.

PURPOSE: Acute white-light damage to rods depends on the amount of rhodopsin available for bleaching during light exposure. Bleached rhodopsin is metabolically regenerated through the visual cycle involving the pigment epithelium, or photochemically by deep blue light through photoreversal of bleaching. Because photoreversal is faster than metabolic regeneration of rhodopsin by several orders of magnitude, the photon catch capacity of the retina is significantly augmented during blue-light illumination, which may explain the greater susceptibility of the retina to blue light than to green light. However, blue light can also affect function of several blue-light-absorbing enzymes that may lead to the induction of retinal damage. Therefore, this study was conducted to test whether rhodopsin and its bleaching intermediates play a role in blue-light-induced retinal degeneration. METHODS: Eyes of anesthetized rats and mice that did or did not contain rhodopsin were exposed to green (550 +/- 10 nm) or deep blue (403 +/- 10 nm) light for up to 2 hours. Rats with nearly rhodopsinless retinas were obtained by bleaching rhodopsin in animals with inhibited metabolic rhodopsin regeneration-that is, under halothane anesthesia. In addition, Rpe65(-/-) mice that are completely without rhodopsin were used to test the susceptibility to blue-light damage of a rodent retina completely devoid of the visual pigment. Effects of illumination on photoreceptor morphology were assessed 24 hours or 10 days thereafter by morphologic and biochemical methods. RESULTS: Exposure to blue light resulted in severe retinal damage and activation of the transcription factor AP-1 in rats. In contrast, green light had no effect. When rhodopsin was almost completely bleached by short-term green-light exposure while metabolic regeneration (but not photoreversal) was prevented by halothane anesthesia, blue-light exposure induced distinct lesions in rat retinas. When both metabolic rhodopsin regeneration and photoreversal of bleaching were almost completely inhibited, blue-light exposure caused only very moderate lesions. When mice without rhodopsin were exposed to blue light, no damage occurred, in contrast to wild-type control mice. CONCLUSIONS: Short time exposure to blue light has deleterious effects on retinal morphology. Because damage was observed only in the presence of the visual pigment, blue-light-induced retinal degeneration is rhodopsin mediated. Absorption of blue light by other proteins is not sufficient to induce light damage. Photoreversal of bleaching, which occurs only in blue but not in green light, increases the photon-catch capacity of the retina and may thus account for the difference in the damage potential between blue and green light.

Animals↗
PubMed2001

Prevention of photoreceptor apoptosis by activation of the glucocorticoid receptor.

PURPOSE: Evidence has accumulated that excessive light exposure may promote age-related and inherited retinal degeneration, in which photoreceptor death by apoptosis leads to loss of vision. In the current study, the effect of elevated corticosteroid levels on light-induced apoptosis of photoreceptors was determined. METHODS: Photoreceptor apoptosis was induced in retinas of BALB/c mice by exposure to diffuse white light. High levels of corticosteroids were induced, either endogenously (fasting-mediated stress) or by a single intraperitoneal injection of dexamethasone (DEX). Photoreceptor damage was assessed morphologically and by electroretinography. Glucocorticoid receptor (GR) and activator protein (AP)-1 activities were shown by Western blot analysis and electrophoretic mobility shift assay (EMSA) of retinal nuclear extracts. RESULTS: Fasting and injection of DEX led to an activation of GR in the retina, as judged by its translocation to the nucleus of retinal cells. On induction of GR activity before light exposure, AP-1 activity, normally induced by damaging doses of light, remained at basal levels. Both treatments completely prevented photoreceptor apoptosis and preserved retinal function. CONCLUSIONS: Activity of the transcription factor AP-1 is associated with light-induced apoptosis. In the current study, pharmacologic suppression of AP-1 activity protected against light damage. Inhibition of AP-1 activity may have occurred by the protein-protein interaction of GR and AP-1.

Animals↗
PubMed2000

Age-related macular degeneration. The lipofusion component N-retinyl-N-retinylidene ethanolamine detaches proapoptotic proteins from mitochondria and induces apoptosis in mammalian retinal pigment epithelial cells.

10-20% of individuals over the age of 65 suffer from age-related macular degeneration (AMD), the leading cause of severe visual impairment in humans living in developed countries. The pathogenesis of this complex disease is poorly understood, and no efficient therapy or prevention exists to date. A precondition for AMD appears to be the accumulation of the age pigment lipofuscin in lysosomes of retinal pigment epithelial (RPE) cells. In AMD, these cells seem to die by apoptosis with subsequent death of photoreceptor cells, and light may accelerate the disease process. Intracellular factors leading to cell death are not known. Here we show that the lipophilic cation N-retinyl-N-retinylidene ethanolamine (A2E), a lipofuscin component, induces apoptosis in RPE and other cells at concentrations found in human retina. Apoptosis is accompanied by the appearance of the proapoptotic proteins cytochrome c and apoptosis-inducing factor in the cytoplasm and the nucleus. Biochemical examinations show that A2E specifically targets cytochrome oxidase (COX). With both isolated mitochondria and purified COX, A2E inhibits oxygen consumption synergistically with light. Inhibition is reversed by the addition of cytochrome c or cardiolipin, a negatively charged phospholipid that facilitates the binding of cytochrome c to membranes. Succinate dehydrogenase activity is not altered by A2E. We suggest that A2E can act as a proapoptotic molecule via a mitochondria-related mechanism, possibly through site-specific targeting of this cation to COX. Loss of RPE cell viability through inhibition of mitochondrial function might constitute a pivotal step toward the progressive degeneration of the central retina.

Aging↗
PubMed2000

Gene expression in the mouse retina: the effect of damaging light.

PURPOSE: High levels of visible light induce apoptotic cell death of photoreceptors, a process depending on the activation of the transcription factor AP-1. This suggests that regulation of gene expression might be important for light-induced photoreceptor cell death. We measured expression of AP-1 family members and of several apoptosis-related genes to test their potential involvement in photoreceptor apoptosis. METHODS: Wildtype and c-fos-/- mice were exposed to low (roomlight) or high levels of visible light for up to two hours. Total RNA was prepared from isolated retinas during and after light exposure. Relative mRNA levels were determined semiquantitatively using either competitive or exponential RT-PCR. RESULTS: Expression of c-fos-/- was upregulated by intense light as early as 15 min after lights on. Highest levels (6-fold induction) were detected at 2 h after lights off declining thereafter to basal levels 20 h after the end of exposure. c-jun mRNA was induced at 30 min after lights on and high expression levels (fourfold induction) persisted at least for 8 h. Similarly, expression of caspase-1 was six to 9-fold increased at 6 to 8 h after light exposure in wildtype but not in c-fos knockout mice. The latter mice are protected against light-induced photoreceptor apoptosis. Expression of other apoptosis-related genes (bcl-2, bcl-XL, bax, bad, caspase-3) was not affected by light exposure or the lack of c-Fos in knockout mice. CONCLUSIONS: Expression of c-fos and c-jun mRNA is transiently induced by exposure to damaging light. Induced expression of c-jun persists longer than expression of c-fos. Among the apoptosis-related genes, only caspase-1 expression was upregulated by light exposure and Caspase-1 might therefore be involved in light-induced retinal degeneration.

Animals↗
PubMed2000

c-fos controls the "private pathway" of light-induced apoptosis of retinal photoreceptors.

White light (5 klux for 2 hr) induces apoptosis of rod photoreceptors in wild-type mice (c-fos(+/+)) within 24 hr, whereas rods of c-fos knock-out mice (c-fos(-/-)) are protected (). The range of this protection was tested by analyzing retinas of c-fos(+/+) and c-fos(-/-) mice up to 10 d after exposure to threefold increased light intensities (15 klux for 2 hr). In c-fos(-/-) mice, rods were unaffected, whereas they were destroyed in c-fos(+/+) mice. After light exposure, mitochondrial damage in rods was observed exclusively in c-fos(+/+) mice. Electroretinograms recorded 48 hr after exposure revealed a decrease of all components in c-fos(+/+) mice but indicated no light-induced loss of function in c-fos(-/-) mice. Thus, in c-fos(-/-) mice, light-induced apoptosis is blocked or its threshold is elevated more than threefold. Increased activity of the transcription factor activator protein-1 (AP-1) in retinas of light-exposed c-fos(+/+) mice indicated an acute contribution of AP-1 to apoptosis induction. AP-1 activity increased already during exposure and peaked approximately 6 hr thereafter, coinciding with the appearance of major morphological signs of apoptosis. Activated AP-1 mainly consisted of c-Fos/Jun heterodimers. In c-fos(-/-) mice, AP-1 activity remained unchanged, indicating that no other Jun- or Fos-family member could substitute for c-Fos. Like damaging light, N-methyl-N-nitrosourea (MNU) induced AP-1 containing c-Fos in c-fos(+/+) mice and did not induce AP-1 in c-fos(-/-) mice. In contrast to light, however, MNU induced apoptosis in rods of c-fos(-/-) mice. Thus, c-Fos is essential for a specific premitochondrial "private apoptotic pathway" induced by light but not for the execution of apoptosis induced by other stimuli.

Alkylating Agents↗
PubMed2000

Efficacy of interpersonal psychotherapy for postpartum depression.

BACKGROUND: Postpartum depression causes women great suffering and has negative consequences for their social relationships and for the development of their infants. Research is needed to evaluate the efficacy of psychotherapy for postpartum depression. METHODS: A total of 120 postpartum women meeting DSM-IV criteria for major depression were recruited from the community and randomly assigned to 12 weeks of interpersonal psychotherapy (IPT) or to a waiting list condition (WLC) control group. Subjects completed interview and self-report assessments of depressive symptoms and social adjustment every 4 weeks. RESULTS: Ninety-nine of the 120 patients completed the protocol. Hamilton Rating Scale for Depression (HRSD) scores of women receiving IPT declined from 19.4 to 8.3, a significantly greater decrease than occurred in the WLC group (19.8 to 16.8). The Beck Depression Inventory (BDI) scores of women who received IPT declined from 23.6 to 10.6 over 12 weeks, a significantly greater decrease than occurred in the WLC group (23.0 to 19.2). A significantly greater proportion of women who received IPT recovered from their depressive episode based on HRSD scores of 6 or lower (37. 5%) and BDI scores of 9 or lower (43.8%) compared with women in the WLC group (13.7% and 13.7%, respectively). Women receiving IPT also had significant improvement on the Postpartum Adjustment Questionnaire and the Social Adjustment Scale-Self-Report relative to women in the WLC group. CONCLUSIONS: These findings suggest that IPT is an efficacious treatment for postpartum depression. Interpersonal psychotherapy reduced depressive symptoms and improved social adjustment, and represents an alternative to pharmacotherapy, particularly for women who are breastfeeding.

Depression, Postpartum↗
PubMed2000

Development of methods for evaluating toxicity to freshwater ecosystems.

This article presents a summary of a collaborative research program involving five European research groups, that was partly funded by the European Commission under its Environmental Research Program. The objective of the program was to develop aquatic toxicity tests that could be used to obtain data for inclusion at Level 2 of the Risk Evaluation Scheme for the Notification of Substances as required by the 7th Amendment to EC Directive 79/831/EEC. Currently only a very limited number of test methods have been described that can be used for this purpose and these are based on an even smaller number of test species. Tests based upon algae (Chlamydomonas reinhardi, Scenedesmus subspicatus, and Euglena gracilis), protozoa (Tetrahymena pyriformis), rotifera (Brachionus calyciflorus), crustacea (Gammarus pulex), and diptera (Chironomus riparius) were developed. The tests encompassed a range of end points and were evaluated against four reference chemicals: lindane, 3, 4-dichloroaniline (DCA), atrazine, and copper. The capacity of the tests to identify concentrations that are chronically toxic in the field was addressed by comparing the effects threshold concentrations determined in the laboratory tests with those determined for similar and/or related species and end points in stream and pond mesocosm studies. The lowest no-observed-effect concentrations (NOEC), EC(x), or LC(x) values obtained for lindane, atrazine, and copper were comparable with the lowest values obtained in the mesocosms. The lowest chronic NOEC determined for DCA using the laboratory tests was approximately 200 times higher than the lowest NOEC in the mesocosms.

Aniline Compounds↗
PubMed2000

Derivation of predicted No-effect concentrations for lindane, 3, 4-dichloroaniline, atrazine, and copper.

Environmental risk assessment is a key feature of regulations controlling the placing of new, and the maintenance of existing, chemicals products in the market place. For example, European Commission Directive 93/67/EC on Risk Assessment for New Notified Substances and Commission Regulation (EC) No. 1488/94 on Risk Assessment for Existing Substances requires that risk assessments be carried out for new and existing substances in the European Community. The process of environmental risk assessment seeks to determine the balance of probability of species and communities being damaged by chemical releases. The process relies upon a valid estimation of a predicted environmental concentration (PEC) in relevant environmental compartments and a predicted no effect concentration (PNEC) below which the organisms present in that compartment are unlikely to be significantly affected. If the PEC exceeds the PNEC there is a potential for damaging effects to occur. This article focuses on the determination of PNECs for risk assessment. Methods for determining a PNEC described in OECD Monograph 26 (1989, Report of the OECD Workshop on Ecological Effect Assessment, Paris, France, have been applied to data derived for the four chemicals lindane, 3,4-dichloroaniline, atrazine, and copper in a series of collaborative research projects funded by the European Commission.

Aniline Compounds↗
PubMed2000

Protection of Rpe65-deficient mice identifies rhodopsin as a mediator of light-induced retinal degeneration.

Light-induced apoptosis of photoreceptors represents an animal model for retinal degeneration. Major human diseases that affect vision, such as age-related macular degeneration (AMD) and some forms of retinitis pigmentosa (RP), may be promoted by light. The receptor mediating light damage, however, has not yet been conclusively identified; candidate molecules include prostaglandin synthase, cytochrome oxidase, rhodopsin, and opsins of the cones and the retinal pigment epithelium (PE). We exposed to bright light two groups of genetically altered mice that lack the visual pigment rhodopsin (Rpe65-/- and Rho-/-). The gene Rpe65 is specifically expressed in the PE and essential for the re-isomerization of all-trans retinol in the visual cycle and thus for the regeneration of rhodopsin after bleaching. Rho-/- mice do not express the apoprotein opsin in photoreceptors, which, consequently, do not contain rhodopsin. We show that photoreceptors lacking rhodopsin in these mice are completely protected against light-induced apoptosis. The transcription factor AP-1, a central element in the apoptotic response to light, is not activated in the absence of rhodopsin, indicating that rhodopsin is essential for the generation or transduction of the intracellular death signal induced by light.

Animals↗
PubMed2000

Periapical status and quality of root fillings and coronal restorations in a Danish population.

AIM: The aim of this study was to investigate the quality of endodontic and coronal restorations and the association with periapical status in a Danish population. METHODOLOGY: A total of 614 randomly selected individuals (20-60+ years of age) from Aarhus County had a full-mouth radiographic examination. The quality of endodontic and coronal restorations and the periapical status of endodontically treated teeth were assessed by radiographic criteria. Root fillings were categorized as 'adequate' or 'inadequate' with regard to root filling length and lateral seal. Coronal restorations were categorized into 'adequate' and 'inadequate', defined by the absence or presence of radiographic signs of overhangs or open margins. Results were analysed statistically using the chi-squared test. RESULTS: The total number of endodontically treated teeth was 773, and 52.3% had apical periodontitis (AP). Root-filled teeth with an adequate lateral seal had a lower incidence of AP than teeth with an inadequate seal (44.3% vs. 57.8%), and teeth with an adequate root filling length were associated with a better periapical status than teeth with inadequate length of the root filling (42.0% vs. 67.6%). Similarly, adequate coronal restorations were associated with better periapical status than inadequate restorations (48.0% vs. 63.9%). When both root filling and coronal restoration quality were assessed, the incidence of AP ranged from 31.2% (optimal quality) to 78.3% (all parameters scored as inadequate). CONCLUSIONS: Inadequate root canal and coronal restorations were associated with an increased incidence of AP.

Adult↗
PubMed2000

[Therapeutic strategies in RP (retinitis pigmentosa): light at the end of the tunnel?].

Retinitis pigmentosa (RP) is a hereditary retinal dystrophy which leads to severe visual impairment or blindness and affects about 3.5/1000 of individuals in the industrial world. During the past decades, numerous animal models carrying mutations analogous to mutations in human RP have been studied to elucidate the molecular mechanisms leading to apoptotic photoreceptor cell death in this disease. Up to date, there is no effective treatment to influence the fatal outcome of RP. Recent progress in basic research promotes the development of new therapeutic strategies. In order to restore visual function in blind individuals, the development of electronic photoreceptor prosthesis is being investigated by several researchgroups. Other promising approaches are somatic gene therapy, the application of growth factors and/or pharmacological agents and the inhibition of photoreceptor cell death by interfering with the apoptotic pathway. However, a better understanding of the molecular events leading to cell loss due to photoreceptor apoptosis will be essential for the development of effective treatment.

Animals↗