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Biomedical subjects

Jochen Fanghänel

Publications and source records attributed to Jochen Fanghänel.

5 recordsLinked to original sources
PubMed2004

Biomechanics of the dental arch and incisal crowding.

During horizontal contact, the dental arch represents a link chain in which two convex articular surfaces are in contact and are tensioned by the dentogingival and dentoalveolar fibrous tissue. Joints composed of convex-convex surfaces are equivalent to stretched dimeric link chains whose links are in a mechanically unstable position under compression. Experiments on plaster models show that the dimensional stability of an articulated (dental) arch is considerably increased when a concave and a convex articular surface are in contact, as these joints are equivalent to an overlapping dimeric link chain whose links are in a mechanically stable position when under compression. In the abraded denture of Stone Age man, horizontal interdental contacts of transversally concave-convex dental surfaces may be found extending even into the incisal region. Increased stability of the dental arch and reduced problems of incisal crowding are to be expected if an overlapping dimeric chain is produced morphologically in each horizontal contact by means of slight interproximal enamel reduction.

Alveolar Process↗
PubMed2004

Reduction of procarbazine-induced cleft palates by prenatal folic acid supplementation in rats.

We investigated the effects of prenatal folic acid supplementation on procarbazine (PCZ)-induced intra-uterine growth retardation (IUGR), cleft palates, and microgenia. Three groups of gravid rats were treated with 200 mg/kg body weight (BW) PCZ on day 13.5 of gestation (GD13.5). Two groups of them were additionally supplemented with 1 and 2.5 mg/kg folic acid, respectively, from GD13.5 through GD16.5. On GD19.5, all fetuses were delivered by caesarian sections and sexed subsequently. Numbers of live and dead fetuses as well as resorptions were counted. Data on fetal BW, crown-rump length, tail length, placental weight, and diameter were collected. Fetal heads were histologically scrutinized for the occurrence of cleft palates and microgenia. Folic acid at 2.5 mg/kg diminished PCZ-induced IUGR. In male fetuses, both folic acid doses significantly reduced the incidence of cleft palates and microgenia, while in females, only the high folic acid dose was capable of lowering the occurrence frequency of cleft palates. We conclude that folic acid supplementation at the used doses confers a substantial protection against PCZ-induced IUGR and incidence of cleft palates and microgenia. However, these effects are gender-related and dose-dependent.

Animals↗
PubMed2004

Effects of a single inhalative exposure to formaldehyde on the open field behavior of mice.

The effects of formaldehyde on the explorative behavior and locomotor activity of mice after a single inhalative exposure were examined in an open field. Adult male mice were exposed to approximately 1.1 ppm, 2.3 ppm, or 5.2 ppm formaldehyde vapour for 2 hours and the open field test was carried out two hours after the end of exposure (trial 1) and repeated 24 hours thereafter (trial 2). The following behavioral parameters were quantitatively examined: numbers of crossed floor squares (inner, peripheral, total), sniffing, grooming, rearing, climbing, and incidence of fecal boli. The results of the first trial revealed that the motion activity was significantly reduced in all exposed groups. In the 1.1 ppm group, the frequency of rearing was reduced and that of floor sniffing increased. The exposure to the two higher formaldehyde concentrations caused a significant decrease in total numbers of floor squares crossed by the subjects, air sniffing, and rearing. The open field test on the next day (trial 2) showed that the frequencies of floor sniffing, grooming, and rearing in all formaldehyde groups were significantly altered. In the 2.5 ppm group, an increased incidence of fecal boli was observed. From the results obtained, we conclude that the exposure of male mice to formaldehyde vapour affects their locomotor and explorative activity in the open field, and that some open field parameters are still altered in the exposed animals even after 24 hours.

Animals↗
PubMed2003

Increased epidermal functioning wild-type p53 expression in vitiligo.

Despite the lack of protective melanin and increased oxidative stress due to mM concentrations of epidermal H2O2 in vitiligo, there is no significantly increased risk for chronic actinic damage and non-melanoma skin cancer. Therefore the question arises, which protective mechanisms could be involved in the skin of these patients preventing the initiation of these cancers. Recently an overexpression of p53 has been shown in vitiligo. Unfortunately there was no further characterization of this elevated p53. Employing a functional colour yeast assay, the study presented herein demonstrates for the first time the overexpression of a functioning wild-type p53 protein in both depigmented and 'normal' pigmented epidermis of patients with vitiligo compared with healthy controls. Surprisingly long-term narrowband UVB (311 nm) treatment does not alter this expression. Moreover, MDM-2, PCNA and p21 protein expression remain unchanged compared with healthy controls. This increased epidermal p53 in vitiligo coincides with decreased thioredoxin reductase (TR) protein levels in both depigmented and pigmented skin whereas mRNA expression is unaffected. Because TR is one transcriptional target of p53, these results support a wild-type functionality, which was further supported by the specific p53 FASAY yeast test. To our knowledge this is the first example of persistent elevated functioning wild-type p53 in humans. Based on our results we hypothesize that the low incidence for actinic damage, basal cell and squamous cell carcinoma as documented in vitiligo could well reside in a protective function of up-regulated wild-type p53.

Adolescent↗