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At least 289 records · Page 16Linked to original sources
PubMed2000

Root surface caries: a complication of the jejunoileal bypass.

BACKGROUND: A patient developed root surface caries and loss of teeth following the jejunoileal (JI) bypass. We attempted to confirm the association of root surface caries with the JI bypass and explore the mechanisms by which it occurs. METHODS: The number of root surface caries per year after, and an equal period of time before, a JI bypass was determined in 18 patients. These 18 patients and 5 normal controls gave stimulated saliva samples for measurement of chloride, bicarbonate and pH. 4 JI bypass patients and 4 normal controls gave timed stimulated saliva samples for measurements of volume. RESULTS: 7 of 18 JI bypass patients had >0.5 root surface caries per year after the operation but none before (p<.01). Salivary chloride was > 12 meq/l in 3 of the 18 JI bypass patients but in none of 5 controls (p<.05). The salivary pH and bicarbonate were 6.38+/-0.48 vs 6.92+/-0.21 and 2.81+/-2.1 meq/l vs 5.8+/-1.2 meq/l in the JI bypass group and the control group respectively (p<.05). The stimulated saliva was 2.3+/-1.2 vs 4.5+/-1.4 cc/min in the JI bypass group and control group, respectively (p<.02). CONCLUSIONS: Root surface caries are more frequent after JI bypass. This may be due to decreased saliva flow and a reduced salivary buffering capacity.

Adult↗
PubMed1996

A complement of ten essential and pleiotropic arabidopsis COP/DET/FUS genes is necessary for repression of photomorphogenesis in darkness.

Two genetic screens, one for mutations resulting in photomorphogenic development in darkness and the other for mutants with fusca phenotype, have thus far identified six pleiotropic Arabidopsis COP/DET/FUS genes. Here, we characterized representative mutants that define four additional pleiotropic photomorphogenic loci and a null mutant allele of the previously defined DET1 locus. Dark-grown seedlings homozygous for these recessive mutations exhibit short hypocotyls and expanded cotyledons and are lethal before reaching reproductive development. Dark-grown mutant seedlings also display characteristic photomorphogenic cellular differentiation and elevated expression of light-inducible genes. In addition, analyses of plastids from dark-grown mutants reveal partial chloroplast differentiation and absence of etioplast development. Root vascular bundle cells of light-grown mutant seedlings develop chloroplasts, suggesting that these FUS gene products are important for suppression of chloroplast differentiation in light-grown roots. Double-mutant analyses indicate that these pleiotropic cop/det/fus mutations are epistatic to mutations in phytochromes, a blue-light photoreceptor, and a downstream regulatory component, HY5. Therefore, there is a complement of at least 10 essential and pleiotropic Arabidopsis genes that are necessary for repression of photomorphogenic development.

Arabidopsis↗
PubMed1993

Molecular characterization of the gene for carrot cell wall beta-fructosidase.

Carrot cell wall beta-fructosidase, previously purified and cloned, is encoded by a single, wound- and pathogen-inducible gene. The developmental regulation of the gene was studied by determining the steady-state mRNA levels in different organs during carrot development: cell wall beta-fructosidase mRNA was detected in roots and leaves of young plants but not during tap root development. A genomic clone was isolated and characterized. The transcription start site was determined by primer extension analysis. Inspection of the promoter sequence (1488 bp) revealed the presence of sequences with high homology to cis-acting elements for the regulation of plant genes by wounding and infection. The 5'-regulatory sequence was fused to the reporter gene beta-glucuronidase (GUS) and tested in a transient expression assay with carrot suspension cells and wounded carrot root tissue (aged disks of carrot roots). The expression of the GUS gene in the transfected cells proved that the isolated promoter was functional. In transgenic tobacco plants containing the cell wall beta-fructosidase promoter fused to GUS, the reporter gene was predominantly expressed in the shoot and root meristems of young seedlings. No GUS expression was detected in mature tobacco plants, showing that the development-specific regulation of the cell wall beta-fructosidase promoter seen in carrot was maintained in tobacco plants. In contrast, expression of the GUS reporter gene in transgenic tobacco was not wound inducible. To analyze the functional organization of the cell wall beta-fructosidase promoter, a 5'-deletion series was generated and tested in a transient expression assay in protoplasts of Nicotiana plumbaginifolia. Two regions containing putative silencer elements were identified. A comparison of these regions with known silencer elements identified in both regions one copy of the negative dominant cis-acting element found in a chalcone synthase promoter of petunia.

Amino Acid Sequence↗
PubMed2002

Lateral root formation is blocked by a gain-of-function mutation in the SOLITARY-ROOT/IAA14 gene of Arabidopsis.

Lateral root development is a post-embryonic organogenesis event that gives rise to most of the underground parts of higher plants. Auxin promotes lateral root formation, but the molecular mechanisms involved are still unknown. We have isolated a novel Arabidopsis mutant, solitary-root (slr), which has reduced sensitivity to auxin. This dominant slr-1 mutant completely lacks lateral roots, and this phenotype cannot be rescued by the application of exogenous auxin. Analysis with cell-cycle and cell-differentiation markers revealed that the slr-1 mutation blocks cell divisions of pericycle cells in lateral root initiation. The slr-1 mutant is also defective in root hair formation and in the gravitropic responses of its roots and hypocotyls. Map-based positional cloning and isolation of an intragenic suppressor mutant revealed that SLR encodes IAA14, a member of the Aux/IAA protein family. Green fluorescent protein-tagged mutant IAA14 protein was localized in the nucleus, and the gain-of-function slr-1/iaa14 mutation decreased auxin-inducible BA-GUS gene expression in the root, suggesting that SLR/IAA14 acts as a transcriptional repressor. These observations indicate that SLR/IAA14 is a key regulator in auxin-regulated growth and development, particularly in lateral root formation.

Amino Acid Sequence↗
PubMed1992

Bundle formation of principal fibers in rat molars.

The bundling of principal fibers was investigated in tangential sections through the tooth-related portion in developing rat molars by light and electron microscopy. When root dentin calcification began, cross sections of principal fibers emerged as fibril aggregates in the narrow intercellular spaces in a densely packed population of periodontal ligament cells. Subsequently, these cells changed shape and location to widen the intercellular spaces. The fibril aggregates became thicker in these spaces. With root development, the collagen fibrils formed loosely aggregated bundles and the periodontal ligament cells extended cell processes between the bundles. The cell processes usually contained microfilaments suggestive of actin filaments, and as the cell processes extended and came in close apposition, they formed delimited compartments. These compartments appeared to be a sheath-like structure, and the loose fibril bundles developed into tight fibril bundles in the compartments. Finally the principal fibers consisted of many tight fibril bundles, which were partially or entirely surrounded by cell processes and cell bodies. The findings suggest that the sheath-like, cellular compartments cause the tight bundling of the principal fibers.

Actin Cytoskeleton↗
PubMed1987

The long-term effects of treatment on the dental condition of children surviving malignant disease.

Fifty-two long-term survivors of childhood leukemia or solid tumors had a clinical dental examination along with 49 of their sibling. The 52, with an additional 30 examined in a previous study, were studied radiologically with a panoramic tomogram. All children with leukemia had received chemotherapy for 2 or 3 years and irradiation on standard protocols and the solid tumor group had received chemotherapy for 6 to 24 months. There was no difference between siblings and patients for dental caries, gingivitis, and oral hygiene, mouth opening, overjet, and overbite. More solid-tumor patients had abnormal occlusion (P less than 0.02) and those with abnormalities tended to have been treated at an earlier age. Enamel opacities and hypoplasia were more common in patients than siblings and in the leukemia than in the solid tumor group. Sixty-five percent of the children had abnormalities on radiologic examination including failure of the tooth to develop, small crown, hypoplasia of the crown, and abnormal root development. In most cases the radiologic abnormality could be correlated in time with the patient's treatment and a knowledge of the normal time of tooth development. Three teeth extracted during the course of the study were examined histologically and these showed prominent incremental lines which could be correlated in time with vincristine treatment.

Adolescent↗
PubMedDate not supplied

Root caries in the elderly: an update for the next century.

Root caries is an emerging challenge to the dental professions because of the growing number of increasingly aging adults who have retained many or all of their teeth. Risk factors for developing root caries point to both intraoral and environmental factors, making the management of root caries complex and multidisciplinary. Prevention is the most desirable approach for management, but patients who have developed caries of the roots can be treated with remineralization strategies or a variety of restorative approaches. Dental professionals need to keep abreast of new approaches emerging for the management of root caries.

Aged↗
PubMed1997

Root caries in the older patient: significance, prevention, and treatment.

Root caries is an emerging challenge to the dental professions because of the growing number of increasingly aging adults who have retained many or all of their teeth. Risk factors for developing root caries point to both intraoral and environmental factors, making the management of root caries complex and multidisciplinary. Prevention based on a composite of risk factors is the most desirable approach for management. Patients who have developed caries of the roots can be treated with remineralization strategies, recontouring techniques, intracoronal restorations of a variety of established and recently introduced materials, or extracoronal restoration. Dental professionals need to keep abreast of new approaches that are emerging for the management of root caries.

Adult↗
PubMed2000

Parathyroid hormone-related protein regulates extracellular matrix gene expression in cementoblasts and inhibits cementoblast-mediated mineralization in vitro.

Parathyroid hormone-related protein (PTHrP) has been implicated in regulating tooth eruption and/or development. Formation of cementum, a mineralized tissue covering the tooth root surface, is a critical biological event for tooth root development. To test the hypothesis that PTHrP targets cementoblasts (CMs) and acts to regulate cementogenesis, CM cell lines were established and their responsiveness to PTHrP stimulation was determined, in vitro. First, subclones were derived from two immortalized murine cell populations that contained CMs; SV-CM/periodontal ligament (PDL) cells were obtained from the root surface of first mandibular molars of CD-1 mice and immortalized with SV40 T-antigen (TAg), and OC-CM cell population was established from OC-TAg transgenic mice in which their cells harbor an osteocalcin (OC and/or OCN) promoter-driving immortal gene SV40 TAg. Based on our previous in situ studies, CM subclones were identified as cells expressing bone sialoprotein (BSP) and OCN transcripts, while PDL cell lines were designated as cells lacking BSP and OCN messenger RNA (mRNA). CMs exhibited a cuboidal appearance and promoted biomineralization, both in vitro and in vivo. In contrast, PDL cells (PDL subclones) displayed a spindle-shaped morphology and lacked the ability to promote mineralized nodule formation, both in vitro and in vivo. Next, using these subclones, the effect of PTHrP on cementogenesis was studied. CMs, not PDL cells, expressed PTH/PTHrP receptor mRNA and exhibited PTHrP-mediated elevation in cyclic adenosine monophosphate (cAMP) levels and c-fos gene induction. PTHrP stimulation repressed mRNA expression of BSP and OCN in CMs and blocked CM-mediated mineralization, in vitro. Collectively, these data suggest that CMs possess PTH/PTHrP receptors and, thus, are direct targets for PTHrP action during cementogenesis and that PTHrP may serve as an important regulator of cementogenesis.

Animals↗
PubMed1997

Asymmetric cell division and cell fate in plants.

A variety of approaches has recently been employed to investigate how sister cells adopt distinct fates following asymmetric divisions during plant development. Surgical and drug studies have been used to analyze asymmetric divisions during both early embryogenesis in brown algae and pollen development in tobacco. Genetic screens have been used to identify genes in Arabidopsis thaliana that are required for specific asymmetric cell divisions during pollen and root development. These studies indicate that cell polarity and division orientation are closely tied to the process of cell fate specification, and suggest that differential inheritance of determinants and positional information may both be involved in the specification of cell fates following asymmetric cell division.

Cell Division↗
PubMed2026

Benzoic acid inhibits peach root growth and lateral root emergence by disrupting auxin homeostasis through salicylic acid accumulation.

We established a non-sterile root transformation system in peach seedlings. Using this system, we demonstrated that BA treatment inhibits plant growth and lateral root emergence by SA-mediated disruption of auxin distribution. Allelopathic autotoxins, particularly benzoic acid (BA), are recognized as primary contributors to peach (Prunus persica) replant disease; however, the molecular mechanisms by which BA disrupts root development remain poorly understood. BA treatment significantly reduced stem and root length and inhibited lateral root emergence without affecting lateral root initiation. To investigate the underlying mechanism at cellular resolution, we established a non-sterile Agrobacterium rhizogenes-based root transformation system achieving 27.11% transformation efficiency. Auxin biosynthesis (PpYUC10), influx transport (PpAUX1), and response (PpARF19) genes were markedly downregulated following BA treatment. Transgenic roots expressing the DR5::GUS auxin reporter exhibited reduced DR5 activity in root tips and suppressed expression in tissues surrounding lateral root primordia, indicating impaired auxin signaling at both developmental sites. Hormone profiling revealed a non-significant trend toward reduced auxin metabolites alongside significant accumulation of salicylic acid (SA), an auxin-antagonistic hormone, and its storage conjugate SA 2-O-&#x3b2;-glucoside. Supporting a causal role for SA, exogenous SA phenocopied BA-induced root growth inhibition, whereas co-treatment with IAA or the SA-biosynthesis inhibitor aminoindan-1-phosphonic acid (AIP) significantly rescued lateral root number and root fresh weight. Multi-treatment RNA-seq identified "response to auxin" and "response to salicylic acid" as the most enriched GO terms in BA-treated roots, and AIP treatment restored the expression of key auxin-related genes while reversing BA-induced SA-pathway changes. Together, these findings suggest that BA-induced SA accumulation suppresses auxin biosynthesis, transport, and signaling, thereby inhibiting peach root growth and lateral root emergence. This study elucidates the molecular basis of BA autotoxicity and establishes a transformation platform for functional genomic studies in Prunus.

Indoleacetic Acids↗
PubMed2001

A newly recognized syndrome of skeletal dysplasia with opalescent and rootless teeth.

A Thai girl with skeletal dysplasia and dental anomalies was seen. Her anomalies consisted of disproportionately short stature, short neck, broad and depressed nasal bridge, broad chest in the anteroposterior dimension, kyphosis, widely spaced nipples, and protruded abdomen. Radiographic testing indicated that she had a large sella turcica, platyspondyly, hypoplastic acetabulum, and a small body of mandible. Both her deciduous and permanent teeth were equally opalescent, and most were rootless, with root development of the mandibular teeth more severely affected. Some maxillary roots were extremely short and tapered. Hypodontia was also observed. These findings represent a unique and hitherto undescribed syndrome of skeletal dysplasia with concomitant dental anomalies.

Acetabulum↗
PubMedDate not supplied

[Study of the possibility of utilizing the transpired mositure condensate from sweet potato for growing plants in biological life support systems].

The effect of nonpurified condensate obtained during prolonged cultivation of batata in a sealed chamber upon batata cuttings and seedlings of garden cress, radish and Chinese cabbage was studied. It was shown that nonpurified condensate produced an inhibitory effect on the formation of roots in batata cuttings and on the growth of previously developed roots of batata cuttings and seedlings. The studies which used a chemical model of 3,4-dihydroxy phenylalanine indicated that the condensate contained biologically active substance of organic origin. However, only experiments with the real continuous culture of batata, using real dilutions of the condensate that depend on the size of the greenhouse and the amount of the nutrient solution would clarify wheather condensate of transpiration water of batata plants can be repeatedly utilized in life support systems.

Ecological Systems, Closed↗
PubMed1995

[Clinical and roentgenologic evaluation of the outcome of therapeutic tooth movement for occlusal adjustment].

The indication of therapeutic tooth luxation in partly impacted teeth as the only method of occlusal adjustment has up to the present been rare. It was therefore the aim of this retrospective, long-term study to include clinical and X-ray results following therapeutic molar luxation (OK 6, UK 7). After an average observation period of 5.3 years, all teeth (7) with incomplete root formation at the time of luxation were rated "successful" following molar luxation. On the other hand, only 2 out of 4 teeth were hand, only classified as "successful" following molar luxation with complete root formation. The results have shown that therapeutic tooth luxation for occlusal adjustment of partly retained molars has a high rate of success when the indication is correctly handled. Because the prognosis is determined according to the stage of root formation, the surgical approach of tooth luxation should be used solely in teeth whose root development has the 1/2 to 3/4 of the expected definitive root length and whose Foramen apicale is open at the time of operation. When an atraumatic operation technique is used, further root formation and a maintained sensibility of the pulp can be reckoned with.

Adolescent↗
PubMed1999

The auxin-insensitive bodenlos mutation affects primary root formation and apical-basal patterning in the Arabidopsis embryo.

In Arabidopsis embryogenesis, the primary root meristem originates from descendants of both the apical and the basal daughter cell of the zygote. We have isolated a mutant of a new gene named BODENLOS (BDL) in which the primary root meristem is not formed whereas post-embryonic roots develop and bdl seedlings give rise to fertile adult plants. Some bdl seedlings lacked not only the root but also the hypocotyl, thus resembling monopteros (mp) seedlings. In addition, bdl seedlings were insensitive to the auxin analogue 2,4-D, as determined by comparison with auxin resistant1 (axr1) seedlings. bdl embryos deviated from normal development as early as the two-cell stage at which the apical daughter cell of the zygote had divided horizontally instead of vertically. Subsequently, the uppermost derivative of the basal daughter cell, which is normally destined to become the hypophysis, divided abnormally and failed to generate the quiescent centre of the root meristem and the central root cap. We also analysed double mutants. bdl mp embryos closely resembled the two single mutants, bdl and mp, at early stages, while bdl mp seedlings essentially consisted of hypocotyl but did form primary leaves. bdl axr1 embryos approached the mp phenotype at later stages, and bdl axr1 seedlings resembled mp seedlings. Our results suggest that BDL is involved in auxin-mediated processes of apical-basal patterning in the Arabidopsis embryo.

Animals↗
PubMedDate not supplied

Aflatoxin B1--its effects on an in vitro plant system.

The phytotoxic effects of aflatoxin B1 (AFB1) on in vitro cultures of differentiating calli and regenerating plantlets of Nicotiana tabacum were assessed. Callus appeared more sensitive to the effects of AFB1, with fresh mass accumulation and callus chlorophyll levels affected at low (approximately 0.5 micrograms/ml) aflatoxin concentrations. Transmission electron microscopy revealed early deteriorative alterations in chloroplast morphology. Inhibitory effects of the toxin (up to and including 10 micrograms/ml) on callus fresh mass accumulation were reversed following a 3 week toxin-free recovery period. In tobacco plantlets, root and leaf development, and root and leaf mass were significantly inhibited in a dose-dependent fashion with increasing AFB1 concentration above 0.5 micrograms/ml. Inhibitory effects on plantlet root development were more pronounced that on leaf development.

Aflatoxin B1↗
PubMed1998

Control of cell division in the root epidermis of Arabidopsis thaliana.

The formation of the root epidermis in Arabidopsis thaliana provides a simple model to study mechanisms underlying patterning in plants. In this paper we have analyzed the relationships between cell fate specification and the pattern of cell division that occur in the root epidermis. Using clonal analysis, the two cell types of the developing root epidermis, trichoblasts and atrichoblasts, were distinguished by different rates of cell division, highest in trichoblasts. This character appears to be dependent on TTG which controls epidermal cell fate specification. The ability of epidermal cells to undergo longitudinal divisions which are involved in the control of the radial symmetry was shown to be controlled in a cell-specific manner by TTG. The control of the rate and the orientation of cell division in the root meristem epidermal layer thus appear to be under the control of cell fate specification mechanisms.

Arabidopsis↗
PubMed2000

Variations in the presenting and treatment features in reimplanted permanent incisors in children and their effect on the prevalence of root resorption.

OBJECTIVE: To examine variations in the presentation and treatment of reimplanted incisors in children and to determine the effect of these on the prevalence of external root resorption. SETTING: Departments of Paediatric Dentistry, Belfast and Newcastle upon Tyne. DESIGN: Recording of the timing of the injury and the storage mediums (including air) and of reimplantation, the stage of root development, the degree of contamination and the time of commencement of root treatment. Cases were reviewed clinically and radiographically at intervals of 3 months. Root resorption was classified as present or absent. Logistic regression and cross-tabulations were produced with the presence of resorption set as the outcome. RESULTS: 128 reimplanted permanent incisor teeth, their median dry time prior to reimplantation being 15 minutes (range 4-52 mins), the median time in a liquid medium being 45 minutes (range 0-650 mins), with a median splinting time of 15 days (range 4-52 days) and a median pulp extirpation time of 15 days (range 0-612 days). There was a lower prevalence of resorption when the period of dryness was less than or equal to 5 minutes (p = 0.025). The prevalence of resorption in teeth with no visible contamination was 57.1%, for those with contamination which were washed clean it was 75%, in those rubbed clean it was 87.5%, and it was 100% for those reimplanted with visible contamination still present (p = 0.014). The corrected odds ratio for contamination was 2.99 and for an extension of 10 minutes of dryness it was 1.29. CONCLUSION: The degree of contamination and the period of dryness were the major risk factors for resorption in this study of reimplanted teeth in children.

Adolescent↗