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Biomedical subjects

A Spahr

Publications and source records attributed to A Spahr.

At least 19 recordsLinked to original sources
PubMed2006

Ameloblastin fusion protein enhances pulpal healing and dentin formation in porcine teeth.

Ameloblastin (Ambn, also named "amelin" or "sheathlin") is a protein participating in enamel formation and mesenchymal-ectodermal interaction during early dentin formation in developing teeth. Experiments have demonstrated an association between Ambn expression and healing of acute pulp wounds. The purpose of this study was to investigate if local application of recombinant fusion Ambn (rAmbn) could influence reparative dentin formation in pulpotomized teeth. In this randomized, double-blinded study, pulpotomy was performed in 28 lower central incisors in 17 adult miniature pigs. Following the surgical procedure, the exposed pulp tissue was covered either with rAmbn or with calcium hydroxide. After 2, 4, or 8 weeks, the teeth were extracted and examined by histomorphometry and immunohistochemistry using antibodies against porcine ameloblastin, collagen type I, and dentin sialoprotein (DSP). In rAmbn-treated teeth, a substantial amount of newly formed reparative dentin was observed at the application site, completely bridging the pulpal wound. Dentin formation was also observed in calcium hydroxide-treated teeth; however, the amount of reparative dentin was significantly smaller (P < 0.001) than after rAmbn treatment. Immunohistochemistry confirmed that the new hard tissue formed was similar to dentin. This is the first time a direct link between ameloblastin and dentin formation has been made in vivo. The results suggest potential for rAmbn as a biologically active pulp-dressing agent for enhanced pulpal wound healing and reparative dentin formation after pulpotomy procedures.

Animals↗
PubMed2002

Expression of amelin and trauma-induced dentin formation.

According to recent studies, amelin (ameloblastin, sheathlin) is expressed in young odontoblasts at the initiation of dentin formation during odontogenesis. The purpose of the present investigation was to study whether amelin is also expressed at the onset of trauma-induced reparative dentin formation. The mandibular developing first molars of 5-day-old rats were surgically taken out, and their pulp tissue briefly separated from the inner dentin surface and immediately repositioned. Then the teeth were re-implanted in their alveoli. At 0, 2, 4, 6, 8, 12 or 14 days after surgery, the animals were sacrificed and the experimental teeth evaluated by histology and immunohistochemistry for amelin. At 2, 4, 6 and 8 days after surgery, the detached and traumatized odontoblasts in the experimental teeth exhibited increasing signs of degeneration and loss of intracellular structures. At days 6 and 8 after surgery, immunohistochemistry revealed a strong staining for amelin in the traumatized odontoblastic layer. Twelve and 14 days after replantation, only necrotic cell remnants of the traumatized odontoblasts were discernible. At this stage, no amelin could be detected by immunostaining. A wide zone of an unorganized mineralized tissue surrounded the odontoblastic cell remnants. On the pulpal side of the unorganized tissue, a new, highly organized tubular reparative dentin layer was observed, bordered by columnar odontoblast-like cells abutting on newly formed predentin. The results indicate that the initiation of trauma-induced reparative dentin formation mimics that of primary dentin formation and that amelin seems to be involved in both processes, possibly as a signaling molecule.

Animals↗
PubMed2000

Helicobacter pylori in the oral cavity: high prevalence and great DNA diversity.

To test the hypothesis that Helicobacter pylori may be transmitted by the oral-oral route, we applied nested PCR and DNA sequencing to detect and analyze H. pylori DNA in the oral cavity of 20 adult patients undergoing endoscopy. Dental plaques of molars, premolars, and incisors and saliva were collected. Additional paraffin-embedded gastric biopsies were analyzed in four patients. Two sets of highly sensitive and specific primers, EHC-U/EHC-L and ET5-U/ET-5L directed to a 860-bp fragment of H. pylori DNA, were used in the nested PCR. Eight patients had an active infection in the stomach determined with the [13C]urea breath test and the other 12 were negative. Nested PCR showed that all 20 subjects (100%) were positive for H. pylori in the oral cavity. DNA sequencing demonstrated that all tested PCR products of the expected size from the oral samples have more than 97% identity with that from H. pylori type strain ATCC 43629. However, sequences differed in oral samples from different subjects as well as between different oral locations and gastric biopsies within the same individuals. In conclusion, the oral cavity may be a permanent reservoir for H. pylori and can harbor multiple H. pylori strains at the same time.

Adult↗
PubMed2000

Characteristic distribution pattern of Helicobacter pylori in dental plaque and saliva detected with nested PCR.

The precise mode of transmission and the natural reservoir for Helicobacter pylori are unknown. PCR assays have proved to be highly sensitive and specific and are regarded as the method of choice for detecting H. pylori DNA in the oral cavity. The aim of this study was to investigate the prevalence and distribution of H. pylori in the oral cavity. Forty-two patients undergoing gastroscopy were investigated for the presence of H. pylori in dental plaque and saliva by nested PCR, and in the stomach by the 13C-urea breath test. Samples tested comprised dental plaque from molars, premolars and incisors and saliva. Two sets of primers homologous to the 860-bp fragment of H. pylori DNA, which have been shown previously to be highly sensitive and specific, were used for nested PCR. Eleven patients (26.2%) were infected with H. pylori in the stomach. H. pylori DNA was identified in dental plaque samples from 41 patients (97%) and in 23 saliva samples (55%). The prevalence in dental plaque from molars, premolars and incisors was 82%, 64% and 59%, with an odds ratio of 3.18, 1.24 and 1 (reference), respectively. In conclusion, H. pylori was present in the oral cavity of 97% of tested patients, with a characteristic distribution that was independent of the infection status of the stomach. Thus H. pylori may belong to the normal oral microflora.

Adult↗
PubMed2000

Effect of gingival fluid on marginal adaptation of Class II resin-based composite restorations.

PURPOSE: To evaluate in vitro the marginal quality of Class II composite restorations at the gingival enamel margins as affected by contamination of the cavities with gingival fluid (GF) during different steps of resin bonding procedures. MATERIALS AND METHODS: 70 Class II cavities were prepared in extracted human molars and restored with composite using a multi-component bonding system (OptiBond FL/Herculite XRV; OPTI) or a single-bottle adhesive (Syntac Sprint/Tetric Ceram; SYN). The cavities were contaminated with human GF: C1 after acid etching, C2 after application of the primer (OPTI) or light-curing of the primer-adhesive (SYN), and C3 after light-curing of the resin adhesive (OPTI). Uncontaminated cavities were used as the control (C0). The restored teeth were subjected to thermocycling (TC) and replicated for SEM analysis of marginal gap formation. Microleakage at the gingival margins was determined by dye penetration with basic fuchsin. STATISTICS: non-parametric tests (Kruskal-Wallis test, Mann-Whitney test with Bonferroni correction). RESULTS: In both bonding systems, contamination with GF after acid etching (C1) did not impair the marginal quality; the mean percentages of continuous margin/mean depths of dye penetration were: OPTI: C0: 88.5%/0.10 mm, C1: 95.6%/0.04 mm; SYN: C0: 90.9%/0.08 mm, C1: 97.0%/0.05 mm. Marginal adaptation was adversely affected when GF contamination was performed after

Acid Etching, Dental↗
PubMed1999

Response of dental follicular cells to the exposure of denuded enamel matrix in rat molars.

Recent studies have indicated that cementum formation can be induced when dental follicular cells are exposed to enamel matrix. The purpose of the present investigation was to study this cementum formation and the appearance of the cells involved, including their expression of collagen types alpha1(I), alpha1(II) and alpha1(III) mRNAs, during this process by means of light microscopy and in situ hybridisation. The mandibular first molars of 5-d-old rats were surgically taken out, their enamel epithelium was removed, and then the crowns were re-inserted with the occlusal surface downwards in their crypts to allow the follicular cells to come in contact with the denuded enamel matrix. After observation periods of 2-14 d, the teeth were prepared for light microscopic examination and in situ hybridisation. A monolayer of follicular cells in contact with the exposed enamel matrix changed their morphology and increased their expression of collagen type I mRNA as early as 2-4 d after exposure to the enamel matrix. A cementum-like tissue was formed at the surface of the enamel matrix. Collagen type II mRNA was never expressed in the tissues studied, whereas collagen type III mRNA was weakly expressed in the follicular cells throughout the experiment.

Amelogenesis↗
PubMed1994

Chondrodysplasia punctata with a mild clinical course.

We report a 7-year-old patient with chondrodysplasia punctata but without rhizomelia. He was born with typical clinical and radiological symptoms of this disease. He developed slowly with considerable psychomotor retardation but improved later, gaining some speech and psychosocial contacts. Joint contractures and bilateral cataracts are still major problems. De novo plasmalogen synthesis in fibroblasts was greatly reduced and DHAP-AT activity was at the lower limit of controls. Peroxisomal thiolase was present in its precursor form only. Membrane fluidity (measured by TMA-DPH fluorescence anisotropy) was increased in erythrocyte ghosts and in lymphocytes. Plasma phytanic acid concentration was elevated 5-fold. The patient represents a mild clinical course of chondrodysplasia punctata, resembling Conradi-Hünermann syndrome, but biochemically he has the typical peroxisomal dysfunction of rhizomelic chondrodysplasia punctata except for a high residual activity of DHAP-AT.

Acetyl-CoA C-Acetyltransferase↗
PubMed1980

[Familial distribution of cholesterolemia, arterial blood pressure and relative weight].

The "Sion" study, a part of the Swiss National Research Program on Cardiovascular diseases, investigated the relationships between parents' and children's cholesterolemia, blood pressure and relative weight. After a health control at school 101 fathers and 108 mothers of ten year old children have been examined. The representativeness of these parents was studied using twice as many adults of the same age from Nyon and from Aarau. Direct significant statistical associations are then demonstrated between fathers' and children's blood pressure, cholesterolemia and relative weight. Analogous associations were found out for the last two variables only between mothers and children. Available data suggest that environmental determinants of risk factor exposure are more likely to explain these relationships. It then appears that the family represents a proper setting for primary prevention.

Adult↗
PubMed1978

Prepubertal XX male with profound physical and mental deficiency, retinitis pigmentosa and multiple congenital anomalies.

A unique case of a prepubertal XX male with profound mental and physical retardation, retinitis pigmentosa, ambiguous genitalia and multiple congenital anomalies is reported. His clinical, genetic, dermatoglyphic and histological findings are presented. This case could represent a new multiple congenital malformation syndrome. Theories on XX male aetiology are briefly discussed.

Abnormalities, Multiple↗