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At least 667 records · Page 37Linked to original sources
PubMed2003

Root surface areas in long-term survivors of childhood cancer.

Treatment regimes for childhood cancer are known to affect the root development in the long-term survivors (LTS) but the available the data is subjective in nature with very few quantitative data in the literature. This study aimed to quantify the root surface area (RSA) of mandibular teeth in LTS compared with controls and relate this to the treatment regime and also to the age at which the cancer was diagnosed. Panoramic radiographs were obtained from 69 LTS and an equal number of appropriately matched healthy controls. RSA were calculated using Computer Linked Image Analysis. RSA in the LTS were found to be significantly smaller as compared with controls. Also, RSA were the least in those LTS who had Total Body Irradiation followed by Bone Marrow Transplantation (TBI/BMT) compared with other treatment regimes, the difference being statistically significant for all teeth studied. There was no relationship between the RSA and the age at which the cancer was diagnosed. Smaller root areas have implications for the oral health of LTS, as bone loss around such teeth will compromise further their periodontal support thus jeopardising the long-term survival of the tooth.

Adolescent↗
PubMed2003

[Expression of basic fibroblast growth factor in dental pulp of immature permanent teeth].

OBJECTIVE: To investigate the expression of basic fibroblast growth factor (bFGF) in normal human dental pulp of immature permanent teeth. METHODS: The teeth root development has been completed 1/3-3/4. Their pulps were immunohisto-chemically examined by use of bFGF antibody and image analysis techniques were used for evaluation. RESULTS: Staining was strongly positive in immature permanent teeth pulp. Image analysis indicated that in the coronal pulp, the gray value of the pulp core was higher than that of the outer pulp, while in the root pulp was the opposite (P < 0.05). CONCLUSION: bFGF may play a role in dental pulp development and maturation.

Adolescent↗
PubMed2004

Autotransplantation of premolars to premolar sites. A long-term follow-up study of 40 consecutive patients.

This article describes the long-term outcome of 40 consecutive patients having transplanted premolars. The objective of this ongoing study is to investigate survival rate, pulp survival rate, periodontal condition, and root development of autotransplanted premolars in orthodontic patients. This report covers 17 years; 32 orthodontic patients had 40 premolars transplanted into contralateral or opposing jaw quadrants where a premolar was missing. The teeth were examined systematically with clinical and radiographic measures at 1, 2, 6, 12, and 60 months or more after autotransplantation. The observation time varied from 2 years 5 months to 22 years 3 months, with a mean of 10 years 4 months. Bonded.018-in edgewise appliances were used, subjecting 87.5% of the transplanted teeth to normal orthodontic forces. One tooth was removed because of root fracture during the observation period, and 2 more had complications possibly related to the transplantation. The remaining 37 teeth and their supporting structures were all healthy at the last examination--a 92.5% success rate. Transplants with closed apices received endodontic therapy, but, in those with open or half-open apices, a 66% pulp survival rate was observed. No teeth in the sample had signs of replacement resorption or developed periodontal attachment loss. Inflammatory resorption in 2 teeth was arrested after endodontic treatment. Root formation, when not complete, continued on transplanted teeth, giving normal root form and adequate root length for normal function. It is concluded that autotransplantation of premolars combined with orthodontic treatment should be the first treatment alternative in cases of missing premolars, when a suitable donor tooth is available.

Adolescent↗
PubMedDate not supplied

[Auxin production by bacteria associated with orchid roots].

Bacteria associated with the roots of greenhouse tropical orchids were shown to produce indole-3-acetic acid (IAA) and to excrete it into the culture liquid. The presence and activity of IAA were demonstrated colorimetrically, by thin-layer chromatography, and by biotests. The associated bacteria varied in their ability to excrete indole compounds (1-28 microg/ml nutrient broth). Addition of tryptophan to the growth medium enhanced phytohormone production. Upon addition of 200 microg/ml tryptophan, the bacteria isolated from Dendrobium moschatum roots (Sphingomonas sp. 18, Microbacterium sp. 23, Mycobacterium sp. 1, Bacillus sp. 3, and Rhizobium sp. 5) produced 50.2, 53.1, 92.9, 37.6, and 60.4 microg IAA/ml respectively, while the bacteria isolated from Acampe papillosa roots (Sphingomonas sp. 42, Rhodococcus sp. 37, Cellulomonas sp. 23, Pseudomonas sp. 24, and Micrococcus luteus) produced 69.4, 49.6, 53.9, 31.0, and 39.2 microg IAA/ml. Auxin production depended on cultivation conditions and on the growth phase of the bacterial cultures. Treatment of kidney bean cuttings with bacterial culture liquid promoted formation of a "root brush" with location height 7.4- to 13.4-fold greater than the one in the control samples. The ability of IAA-producing associated bacteria to act as stimulants of the host plant root development is discussed.

Bacteria↗
PubMed2001

Cell-specific patterns of Cbfa1 mRNA and protein expression in postnatal murine dental tissues.

Cbfa1 (core binding factor alpha 1) is a transcription factor that is a key determinant of the osteoblastic lineage. Recent data showed that Cbfa1 is also highly expressed in early stages of tooth development and is involved in crown morphogenesis and cytodifferentiation of odontoblasts. Here we report the mRNA expression and protein localization of Cbfa1 in the mouse dentition in (later) stages of crown and root development. In addition to osteoblasts, osteocytes, chondrocytes, odontoblasts, dental follicle cells, cementoblasts and periodontal ligament cells, we report also Cbfa1 expression in dental epithelial cells (secretory and maturation ameloblasts) and several non-mineralizing cell types (hair follicles, ducts of salivary glands, and junctional epithelium of the gingiva).

Age Factors↗
PubMed2003

A novel high efficiency, low maintenance, hydroponic system for synchronous growth and flowering of Arabidopsis thaliana.

BACKGROUND: Arabidopsis thaliana is now the model organism for genetic and molecular plant studies, but growing conditions may still impair the significance and reproducibility of the experimental strategies developed. Besides the use of phytotronic cabinets, controlling plant nutrition may be critical and could be achieved in hydroponics. The availability of such a system would also greatly facilitate studies dealing with root development. However, because of its small size and rosette growth habit, Arabidopsis is hardly grown in standard hydroponic devices and the systems described in the last years are still difficult to transpose at a large scale. Our aim was to design and optimize an up-scalable device that would be adaptable to any experimental conditions. RESULTS: An hydroponic system was designed for Arabidopsis, which is based on two units: a seed-holder and a 1-L tank with its cover. The original agar-containing seed-holder allows the plants to grow from sowing to seed set, without transplanting step and with minimal waste. The optimum nitrate supply was determined for vegetative growth, and the flowering response to photoperiod and vernalization was characterized to show the feasibility and reproducibility of experiments extending over the whole life cycle. How this equipment allowed to overcome experimental problems is illustrated by the analysis of developmental effects of nitrate reductase deficiency in nia1nia2 mutants. CONCLUSION: The hydroponic device described in this paper allows to drive small and large scale cultures of homogeneously growing Arabidopsis plants. Its major advantages are its flexibility, easy handling, fast maintenance and low cost. It should be suitable for many experimental purposes.

Arabidopsis↗
PubMed2001

Different pathways are involved in phosphate and iron stress-induced alterations of root epidermal cell development.

Low bioavailability of phosphorus (P) and iron (Fe) induces morphogenetic changes in roots that lead to a higher surface-to-volume ratio. In Arabidopsis, an enlargement in the absorptive surface area is achieved by an increase in the length and frequency of hairs in roots of Fe- and P-deficient plants. The extra root hairs are often located in positions that are occupied with non-hair cells under normal conditions, i.e. over a tangential wall of underlying cortical cells. An involvement of auxin and ethylene in root epidermis cell development of Fe- and P-deficient plants was inferred from phenotypical analysis of hormone-related Arabidopsis mutants and from the application of substances that interfere with either synthesis, transport, or perception of the hormones. Application of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid or the auxin analog 2,4-D caused a marked increase in root hair density in plants of all growth types and confers a phenotype characteristic of ethylene-overproducing mutants. Hormone insensitivity and application of hormone antagonists inhibited the initiation of extranumerary root hairs induced by Fe deficiency, but did not counteract the formation of extra hairs in response to P deprivation. A model is presented summarizing putative pathways for alterations in root epidermal cell patterning induced by environmental stress.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2000

An ancestral MADS-box gene duplication occurred before the divergence of plants and animals.

Changes in genes encoding transcriptional regulators can alter development and are important components of the molecular mechanisms of morphological evolution. MADS-box genes encode transcriptional regulators of diverse and important biological functions. In plants, MADS-box genes regulate flower, fruit, leaf, and root development. Recent sequencing efforts in Arabidopsis have allowed a nearly complete sampling of the MADS-box gene family from a single plant, something that was lacking in previous phylogenetic studies. To test the long-suspected parallel between the evolution of the MADS-box gene family and the evolution of plant form, a polarized gene phylogeny is necessary. Here we suggest that a gene duplication ancestral to the divergence of plants and animals gave rise to two main lineages of MADS-box genes: TypeI and TypeII. We locate the root of the eukaryotic MADS-box gene family between these two lineages. A novel monophyletic group of plant MADS domains (AGL34 like) seems to be more closely related to previously identified animal SRF-like MADS domains to form TypeI lineage. Most other plant sequences form a clear monophyletic group with animal MEF2-like domains to form TypeII lineage. Only plant TypeII members have a K domain that is downstream of the MADS domain in most plant members previously identified. This suggests that the K domain evolved after the duplication that gave rise to the two lineages. Finally, a group of intermediate plant sequences could be the result of recombination events. These analyses may guide the search for MADS-box sequences in basal eukaryotes and the phylogenetic placement of new genes from other plant species.

Amino Acid Sequence↗
PubMed1984

Autotransplantation and replantation of tooth germs in monkeys. Effect of damage to the dental follicle and position of transplant in the alveolus.

The effect of damage to the follicle and of superficial positioning of tooth germs after replantation or autotransplantation was studied in green Vervet monkeys. Radiographs were taken immediately after surgery and 3, 6 and 9 months postoperatively, whereafter the animals were sacrificed. The tissue blocks were sectioned in step serial sections along a frontal plane and histologic and radiographic evaluation was made. Tooth germs whose follicle was either damaged or removed showed no sign of eruption, while tooth germs which were replanted with an intact follicle were fully erupted within 3 months. Non-operated control teeth were fully erupted within 6 months. Histologic examination revealed that roots of replanted teeth were only slightly shorter than the non-operated control teeth. Transplantation of tooth germs in different positions in relation to the alveolar crest showed that teeth placed in their original position attained an average tooth length of 12.5 mm, whereas teeth placed in a semi-erupted position achieved an average length of only 9.7 mm. A control group of non-operated incisors demonstrated an average tooth length of 13.7 mm. This study indicates that damage to the follicle at the time of replantation of tooth germs is of major importance for tooth eruption and that placing tooth germs in a semi-erupted position adversely influences later root development.

Alveolar Process↗
PubMed1994

Repression of the L-asparaginase gene during nodule development in Lupinus angustifolius.

Upon the establishment of an effective nitrogen-fixing symbiosis in amide-transporting plants the enzymatic activity and transcript levels of L-asparaginase are dramatically decreased. This decrease in L-asparaginase activity is essential for the correct functioning of the Rhizobium-legume symbiosis in lupin in which asparagine, synthesized from recently fixed nitrogen, is exported to aerial parts of the plant for use in growth and development. Concomitant with this decrease in L-asparaginase transcript a DNA-binding protein was detected in the nodules. This binding protein was not detectable in ineffective nodules, in nodules treated with nitrate, or in root tips, mature roots, developing flowers or developing seeds. The DNA-binding activity was shown to interact with a 59 bp sequence proximal to the transcription start site. Within this sequence a CTAAAAT direct repeat and a ACTGT/TGTCA incomplete inverted repeat were implicated in the binding of protein to the DNA by DNase I protection experiments. Competitive binding studies with synthesized binding sites were consistent with the CTAAAAT/TGTCA sequence pair proximal to the transcription start site having the highest affinity for the DNA-binding protein. We postulate that this DNA-binding protein is associated with repression of L-asparaginase gene expression in mature lupin root nodules.

Asparaginase↗
PubMed2001

Orthodontic treatment in long-term survivors after pediatric bone marrow transplantation.

Children treated for childhood cancers with both radiation and chemotherapy often exhibit disturbances in dental development. A retrospective analysis of treatment outcome in 10 orthodontically treated children was performed. A questionnaire was sent to each child's orthodontist, and 5 orthodontists reported that the patient's medical condition influenced their choice of treatment plan. Three orthodontists, all treating patients with severely disturbed root development, reported using lighter forces than they used with the average patient. With regard to complications related to orthodontic treatment, 1 of the 10 patients showed evidence of root resorption. In 4 of the 10 patients, the treatment result was judged to be unsatisfactory. This study showed that, although ideal treatment results were not always achieved, orthodontic treatment did not produce any harmful side effects in children who are long-term survivors of childhood cancer.

Adolescent↗
PubMed1994

Relations among motor unit types, generated forces and muscle length in single motor units of anaesthetized cat peroneus longus muscle.

The active length-tension curves of identified single motor units (MUs) belonging to peroneus longus muscle (PL) of anaesthetized adult cats were obtained by eliciting isometric single twitches and tetani. The recorded responses were evaluated by measuring the peak tension amplitude and the tension-time area at muscle lengths extending throughout the physiological length range of the muscle (mean 5.5 mm, standard deviation +/- 0.8). The muscle lengths at which each tested MU developed its maximal twitch (Ltw) and tetanic (Lte) tensions were determined and compared with the muscle length (Lo) at which the stimulation of all the alpha-axons, innervating PL and contained in L7 ventral root, developed their maximal twitch tension. The mean of single MU Ltw values was at Lo +1.08 +/- 1.1 mm. Slow MUs showed the longest values of Ltw (Lo +1.6 +/- 1.0 mm). Single MUs stimulated at tetanic frequencies presented their Lte at values shorter than Lo (Lo - 2.8 +/- 1.7 mm). Slow MUs had the shortest Lte (Lo - 3.4 +/- 1.5 mm). For all the units Lte was shorter than Ltw. Ltw and Lte were, respectively, negatively and positively correlated with the developed tension. Optimal length values also appeared to be related to the MU types. The possibility is discussed that the muscle and tendon compliances and the high non-linearities to the applied forces are the main factors which can determine the differences among Lo, Ltw and Lte values. The relationships between MU type and optimal length values are suggested to be, at least partly, an epiphenomenon due to the different contraction strengths of the various MU types.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗
PubMed1997

Multiple isoforms of neuregulin are expressed in developing rat dorsal root ganglia.

Accumulating evidence suggests that neuregulin (NRG) plays special roles in the development of the mammalian nervous system. We have already identified NRG as a survival factor for Schwann cells during development. In this report, we have studied all possible NRG isoforms and expression of NRG in the developing rat dorsal root ganglia (DRG) and compared them with those of brain and spinal cord. Neural NRG isoforms comprise common immunoglobulin and epidermal growth factor domains. Various different transcripts were characterized, which arose by alternative splicing in several regions: N-terminal (exon 1 or 2), spacer (exon 5), juxtamembrane (exon 9 or 10), and cytoplasmic (exon 12, 13, or 14) domains. At least 13 novel isoforms among 16 splice variants were identified. The transmembrane isoforms of NRG are dominant forms in developing rat DRG. The mRNA expression of NRG isoforms in DRG is similar to that in spinal cord, while in brain the expression is much less. The mRNA in DRG was found at similar levels from birth to postnatal day 7 of the premyelinating stage, and it decreased afterward. Our results suggest that several NRGs, including isoforms not reported before, play a role as survival factors for Schwann cells in the premyelinating stage.

Aging↗
PubMed1987

Effect of localized nitrogen availability to soybean half-root systems on photosynthate partitioning to roots and nodules.

Soybean (Glycine max [L.] Merr. cv Davis) was grown in a split-root growth system designed to maintain control of the root atmosphere. Two experiments were conducted to examine how 80% Ar:20% O(2) (Ar:O(2)) and air (Air) atmospheres affected N assimilation (NH(4)NO(3) and N(2) fixation) and the partitioning of photosynthate to roots and nodules. Application of NH(4)NO(3) to nonnodulated half-root systems enhanced root growth and root respiration at the site of application. A second experiment applied Ar:O(2) or air to the two sides of nodulated soybean half-root systems for 11 days in the following combinations: (a) Air to both sides (Air/Air); (b) Air to one side, Ar:O(2) to the other (Air/Ar:O(2)), and (c) Ar:O(2) to both sides (Ar:O(2)/Ar:O(2)). Results indicated that dry matter and current photosynthate ((14)C) were selectively partitioned to nodules and roots where N(2) was available. Both root and nodule growth on the Air side of Air/Ar:O(2) plants was significantly greater than the Ar:O(2) side. The relative partitioning of carbon and current photosynthate between roots and nodules on a half-root system was also affected by N(2) availability. The Ar:O(2) sides partitioned relatively more current photosynthate to roots (57%) than nodules (43%), while N(2)-fixing root systems partitioned 36 and 64% of the carbon to roots and nodules, respectively. The Ar:O(2) atmosphere decreased root and nodule respiration by 80% and nitrogenase activity by 85% compared to half-root systems in Air while specific nitrogenase activity of nodules in Ar:O(2) was 50% of nodules supplied Air. Results indicated that nitrogen assimilation, whether from N(2) fixation or inorganic sources, had a localized effect on root development. Nodule development accounted for the major decrease in total photosynthate partitioning to non-N(2)-fixing nodules. Soybean compensates for ineffective nodulation by controlling the flux of carbon to ineffective nodules and their associated roots.

Journal Article↗
PubMed1997

Effects of dental trauma on the pulp.

Infection of the root canal system following dental trauma induces pulp and periapical disease and prevents healing of previously healthy pulp. A clinical goal in treating trauma is the maintenance of pulp vitality, and clinicians should be aware of factors that influence pulp healing. The learning objective of this article is to review the factors and techniques that influence pulp vitality and examine the influence pulp has on the healing of adjacent tissues. The potential routes for bacterial infection of the root canal system are discussed, with the clinical crown as the primary portal of entry. Uncomplicated and complicated crown fractures, as well as the crown-root and root fractures, are reviewed. Complications in pulp healing include canal obliteration, disturbed root development, apexogenesis, apexification, and the various forms of resorption.

Alveolar Process↗
PubMed2005

Up-regulation of a H+-pyrophosphatase (H+-PPase) as a strategy to engineer drought-resistant crop plants.

Engineering drought -resistant crop plants is a critically important objective. Overexpression of the vacuolar H(+)-pyrophosphatase (H(+)-PPase) AVP1 in the model plant Arabidopsis thaliana results in enhanced performance under soil water deficits. Recent work demonstrates that AVP1 plays an important role in root development through the facilitation of auxin fluxes. With the objective of improving crop performance, we expressed AVP1 in a commercial cultivar of tomato. This approach resulted in (i) greater pyrophosphate-driven cation transport into root vacuolar fractions, (ii) increased root biomass, and (iii) enhanced recovery of plants from an episode of soil water deficit stress. More robust root systems allowed transgenic tomato plants to take up greater amounts of water during the imposed water deficit stress, resulting in a more favorable plant water status and less injury. This study documents a general strategy for improving drought resistance of crops.

Arabidopsis↗
PubMedDate not supplied

Comparative evaluation of endodontic management of teeth with unformed apices with mineral trioxide aggregate and calcium hydroxide.

PURPOSE: The purpose of this study was to compare mineral trioxide aggregate (MTA) and calcium hydroxide (Ca(OH)2) for their efficacies and time taken for formation of apical biological calcific barriers and resolution of periapical radiolucencies, if present at baseline, in teeth with unformed apices. METHODS: Twenty nonvital permanent maxillary incisors with unformed apices, stratified according to the size of periapical radiolucencies and stage of root development, were equally allocated to MTA and Ca(OH)2 groups. In group 1 (MTA group), after 7 days of disinfection with Ca(OH)2, MTA was packed into the apical one third of the root canals and obturation with gutta percha (GP) was performed in 90% (9/10) of cases within 15 to 30 days. In group 2 (Ca(OH)2 group), obturation was performed following clinical and radiographic depiction of the apical stop. RESULTS: The mean time taken for apical biological barrier formation was 3 +/- 2.9 months for group 1 and 7 +/- 2.5 months for group 2 (P=.008). The periapical radiolucencies were resolved in 4.6 +/- 1.5 months for group 1 and 4.4 +/- 1.3 months for group 2 (P=.83). The total treatment was completed in 0.75 +/- 0.4859 months and 7 +/- 2.5 months for groups 1 and 2, respectively. CONCLUSION: The 2 materials were found to be equally efficacious in the management of nonvital teeth with unformed apices. Time taken to complete the treatment and the biological barrier formation in group 1 was significantly less than that for group 2. The healing time for periapical radiolucencies was almost identical.

Adolescent↗
PubMed1995

Root formation.

This paper provides an overview of recent studies that have enhanced our understanding of the biological mechanisms that operate during root development. For the most part, these studies have been performed on rodents. As significant species differences have been shown to exist, this data cannot necessarily be extrapolated to the human model. The events associated with root odontoblast differentiation are reviewed in comparison to similar events in coronal odontoblast differentiation. Morphological as well as phenotypic differences are outlined and the inductive role of the epithelial root sheath is discussed. Both acellular and cellular cementum formation are reviewed highlighting morphological and phenotypic differences. The potential influence of the epithelial root sheath in the formation of both tissues is compared and contrasted. Finally, a discussion of the fate of the epithelial root sheath is presented with emphasis placed upon the possible roles of apoptosis and epithelium-mesenchymal transition.

Animals↗