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PubMed2004

Effect of orthodontic forces on root resorption in molars submitted to experimental periodontitis.

The present experimental study addresses the issue of the development and size of root resorption areas in molars of rats submitted to orthodontic forces of 51 or 75 g and the induction of periodontal disease by placing a cotton ligature around the cervix of the first upper molars for 48 hours. Immediately on removal of the ligature or 48 hs later we put an orthodontic device in place. The device comprised two steel bands. The arms of a helicoidal spring that exerted force towards palatine passed through the palatine tubes welded to the bands. The number of odontoclasts and the percentage of root resorption areas were determined histomorphometrically on bucco-palatine sections obtained at the level of the central roots. The data showed an increase in root resorption areas when the orthodontic forces were applied to molars of rats following the induction of periodontitis. The magnitude of the force was proportional to the size of the resorption areas and to the number of odontoclasts. Both these end-points exhibited smaller values when the forces were applied once the inflammatory reaction had subsided. The present study shows that the risk of development of root resorption areas in patients with periodontal disease submitted to orthodontic treatment would be lower if lighter forces were applied and treatment were delayed until the inflammatory signs have subsided.

Animals↗
PubMedDate not supplied

[Analysis of possible mechanisms of regulation of root branching].

The formation of lateral roots under the influence of growth inhibitors and phytohormons were studied with germs of corn and flax. All corn primordiums develop into the lateral roots without dormancy period, while some flax primordiums are delayed in development. Removal of root apical meristem (decapitation) does not result in the increase in number of lateral roots of corn germs. Decapitation of flax germs induces the development of some dormant primordiums, that leads to the considerable increase in number of lateral roots. Formation of additional primordium under decapitation does not take place. Auxin stimulates the formation of additional primordiums in flax, but does not effect the number of mature lateral roots. In corn germs synthetic auxin stimulates the development of additional primordiums in root zone, where primordiums are forming after the disturbance. It is shown that the time of primordium development does not change under inhibitor influence, if they do not selectively effect mitoses. It seems that auxins regulate initiation of pericycle division and formation of primordiums of lateral roots on the stage of development of meristematic protuberance. Cytokinins influence the development of already existed primordiums of lateral roots but do not effect the formation of new ones. Constancy of time of primordium formation and independence of their development on the state of the main root need future investigations. The authors suppose that regulation of these processes is non-hormonal.

Cytokinins↗
PubMed1995

Models for the study of cementogenesis.

Cementum is a mineralized tissue that acts to connect the periodontal ligament to the tooth root surface. Its composition is very much like bone, being comprised mainly of type I collagen, inorganic mineral and noncollagenous proteins, however the origin of the cells and factors necessary for cementum formation have yet to be elucidated. Our laboratory has focused on the role that adhesion molecules, and their cell surface receptors, play in the formation of cementum and tooth root. In order to study this, we used a mouse molar as a model system. This system enabled us to study the formation of four distinct mineralized tissues; bone, cementum, dentin and enamel at various stages of their development. For these studies, we initiated experiments to examine potential cementoblast progenitor cells, in vitro. As a first step, we show that dental papilla and dental follicle cells, n vitro, obtained from molar tissues at day 21 of development, induce mineralized nodules, in vitro. In addition, we obtained tissues from mice where defects in root development may exist and determined bone sialoprotein (BSP) protein expression, a mineralized tissue specific adhesion molecule, in such tissues. As discussed here, we found that osteopetrotic (op/op) mice have delayed and/or defective root development and BSP does not localize in the dental tissues, at day 33 of development. In addition, dentin formation was defective and odontoblasts appeared immature, based on morphological examination. In contrast, the day 33 control molars demonstrated positive staining for BSP localized to root cementum, with normal formation of dentin.

Amelogenesis↗
PubMed2000

Arabinogalactan-proteins in Cichorium somatic embryogenesis: effect of beta-glucosyl Yariv reagent and epitope localisation during embryo development.

Direct somatic embryogenesis was induced in root tissues of the Cichorium hybrid '474' (C. intybus L. var. sativum x C. endivia L. var. latifolia). Addition of beta-D-glucosyl Yariv reagent (betaGlcY), a synthetic phenylglycoside that specifically binds arabinogalactan-proteins (AGPs), to the culture medium blocked somatic embryogenesis in a concentration-dependent manner with complete inhibition of induction occurring at 250 microM betaGlcY. The AGP-unreactive alpha-D-galactosyl Yariv reagent had no biological activity in this system. Upon transfer of 250 microM betaGlcY-treated roots to control conditions, somatic embryogenesis was recovered with a time course similar to that of control roots. The betaGlcY penetrated roots and bound abundantly to developing somatic embryos, to the root epidermis and the stele. Immunofluorescence and immunogold labelling using monoclonal antibodies (JIM13, JIM16 and LM2) revealed that AGPs were localised in the outer cell walls peripheral cells of the globular embryo. A spatio-temporal expression of AGPs appeared to be associated with differentiation events in the somatic embryo during the transition from the globular stage to the torpedo stage. To verify betaGlcY specificity, molecules that bound betaGlcY were extracted from treated conditioned medium and identified as AGPs by using the same monoclonal antibodies. In addition, AGPs were found to be abundantly present in the medium during embryogenic culture. All of these results establish the implication of AGPs in embryo development, and their putative role in somatic embryogenesis is discussed.

Asteraceae↗
PubMed2005

Advanced microscopic imaging methods to investigate cortical development and the etiology of mental retardation.

Studies on human patients and animal models of disease have shown that disruptions in prenatal and early postnatal brain development are a root cause of mental retardation. Since proper brain development is achieved by a strict spatiotemporal control of neurogenesis, cell migration, and patterning of synapses, abnormalities in one or more of these events during prenatal development can lead to cognitive dysfunction after birth. Many of underlying causes of mental retardation must therefore be studied in developing brains. To aid in this research, live imaging using laser scanning microscopy (LSM) has recently allowed neuroscientists to delve deeply into the complex three-dimensional environment of the living brain to record dynamic cellular events over time. This review will highlight recent examples of how LSM is being applied to elucidate both normal and abnormal cortical development.

Absorptiometry, Photon↗
PubMed2004

Trichoderma species--opportunistic, avirulent plant symbionts.

Trichoderma spp. are free-living fungi that are common in soil and root ecosystems. Recent discoveries show that they are opportunistic, avirulent plant symbionts, as well as being parasites of other fungi. At least some strains establish robust and long-lasting colonizations of root surfaces and penetrate into the epidermis and a few cells below this level. They produce or release a variety of compounds that induce localized or systemic resistance responses, and this explains their lack of pathogenicity to plants. These root-microorganism associations cause substantial changes to the plant proteome and metabolism. Plants are protected from numerous classes of plant pathogen by responses that are similar to systemic acquired resistance and rhizobacteria-induced systemic resistance. Root colonization by Trichoderma spp. also frequently enhances root growth and development, crop productivity, resistance to abiotic stresses and the uptake and use of nutrients.

Fungi↗
PubMed1996

The effects of neonatal dorsal root section on the survival and dendritic development of lumbar motoneurons in the rat.

Peripheral nerve crush during the early neonatal period results in the death of a large proportion of affected motoneurons and abnormal dendritic development in those which survive. The present study reports the effects of neonatal dorsal root section on motoneurons supplying the extensor digitorum longus muscle of the rat. This lesion did not result in motoneuron death, but did disrupt subsequent dendritic development. In cells retrogradely labelled with cholera toxin subunit B conjugated to horseradish peroxidase, there was little change in adult dendritic morphology in the transverse plane, where abnormalities associated with loss of efferent contact and cell death have been found. However, there was a caudal expansion of the dendritic field, an effect seen following nerve crush but not after blockade of neuromuscular transmission alone. The results show that disruption of dorsal root sensory inputs alone can affect the dendritic development of motoneurons but does not cause their death. In conjunction with our earlier findings, it is clear that both afferent and efferent connections are required for normal dendritic development, and disruption of either has a characteristic effect on survival and dendritic morphology.

Animals↗
PubMed2004

[Biomechanical characteristics of spinal cord tissue--basis for the development of modifications of the DREZ (dorsal root entry zone) operation].

Mechanical properties of the spinal cord tissue--biological basis for the development of the modality of the DREZ surgery lesioning technique Succesful treatment of the chronic neurogenic pain of spinal cord and cauda equina injury origin remains a significant management problem. The mechanism of this pain phenomenon has been shown to be related to neurochemical changes that lead to the state of hypereactivity of the second order dorsal horn neurons. The DREZ surgery (Dorsal Root Entry Zone lesion), designed to destroy anatomy structures involved in pain generating thus interrupting the neurogenic pain mechanism, as a causative procedure in treating this chronic pain, has been performed by using different technical modalities: Radiofrequency (RF) coagulation technic, Laser, Ultrasound and Microsurgical DREZotomy technic. The purpose of the study was to assess the possibility for the establishment of the lesioning technic based on the natural difference in the mechanical properties between the white and gray cord substance. We experimentally deteminated mechanical properties of the human cadaveric cord white versus gray tissue for the purpose of testing possibility of selective suction of the dorsal horn gray substance as a DREZ lesioning procedure. Based on the fact of the difference in tissue elasticity between white and gray cord substance we established a new and simple DREZ surgical lesioning technique that was tested on cadaver cord. For the purpose of testing and comparing the size and shape of the DREZ lesion axchieved the DREZ surgery has been performed on cadaver cord by employing selective dorsal horn suction as a lesioning method. After the procedure cadaver cord underwent histological fixation and analysis of the DREZ lesions achieved. Our result revealed that the white cord substance with longitudinal fiber structure had four time higher dynamical viscosity than gray substance of local neuronal network structure (150 PaS versus 37.5 PaS) that provided possibility for the safe and selective suction of the gray substance of the dorsal horn. Technic includes incision of the dorsolateral sulcus according to Sindous Microsurgical DREZotomy technic than suction under visual control of the dorsal horn gray matter using succer adopted from the lumbar puncture nidle. Operative experimental testing and hystological analysis confirmed expected size and shape of the DREZ lesion performed by dorsal horn suction as DREZ lesioning technique. The utility, selectivity and safety of this technic has been provided by the natural mechanical properties of the cord tissue itself. Application of the Dorsal horn suction as a DREZ lesioning in humans confirmed this technic as a safe and reliable DREZ lesioning method.

Biomechanical Phenomena↗
PubMed2005

Effects of enamel matrix proteins on tissue formation along the roots of human teeth.

OBJECTIVE: Enamel matrix-derived proteins (EMD) are thought to trigger the formation of acellular extrinsic fibre cementum (AEFC), while other reports indicate that EMD may have osteogenic potential. The aim of the present study was to characterize the tissues developing on the root surface following application of EMD. METHODS: Twelve human periodontitis-affected teeth, scheduled for extraction, were treated with EMD. Two to 6 weeks later, the teeth were extracted, demineralized and processed for embedding in acrylic and epoxy resins. New tissue formation was analysed by light and transmission electron microscopy. RESULTS: New tissue formation on the root was observed in the notch and on both scaled and unscaled root surfaces distant of the notch area in six defects. The newly formed tissues on the root were thick, collagenous, devoid of extrinsic fibres, and had an irregular surface contour. The presence of electron-dense, organic material in the collagenous matrix indicated at least partial mineralization. Embedded cells were numerous and the cells on the matrix surface were very large in size. Abundant rough endoplasmic reticulum and a prominent Golgi complex were evident. The presence of a split between the treated root surfaces and the newly formed tissue was a common observation, as was the presence of bacteria and host cells in the interfacial gap. CONCLUSION: Following treatment with EMD, a bone-like tissue resembling cellular intrinsic fibre cementum may develop on the root surfaces, instead of AEFC. Furthermore, EMD may both induce de novo formation of a mineralized connective tissue on scaled root surfaces and stimulate matrix deposition on old native cementum. Interfacial bonding appeared to be weak after 6 weeks of healing.

Cementogenesis↗
PubMed1983

Restrictions of developmental capacities in the dorsal root ganglia during the course of development.

By grafting ganglia from embryonic quails into the neural crest migration pathway of 2-day chick embryos, it was previously demonstrated that all type of ganglia possess more developmental potentialities than those normally expressed in the normal course of development. Namely autonomic neurones with catecholamine and adrenomedullary cells can be obtained from grafted spinal ganglia. The latter also yield sensory neurons to the host dorsal root ganglia (DRG) but only if they are taken from the donor before 8 days of incubation. In the present article we show that the capacity to differentiate sensory neurons in back-transplantation experiments can be correlated with the presence in the donor DRG of cycling neuronal precursors. Once all the neurons have been withdrawn from the cell cycle - an event which occurs first in the mediodorsal and then in the lateroventral area of the ganglion - the DRG cell population gives rise exclusively to autonomic ganglion cells in the host. It is concluded that in the conditions of the back-transplantation experiments, the postmitotic neurons contained in the donor ganglion do not survive. Therefore, the neurons and paraganglion cells which differentiate in the host arise from still undifferentiated precursor cells. This indicates that besides sensory neuron precursors the embryonic DRG cell population also contains precursor cells for the autonomic differentiation pathway.

Adrenal Medulla↗
PubMed2003

[Effects of extracts of root of kudzu vine on mammary gland and uterus development in rats].

OBJECTIVE: To study the effects of extracts of root of kudzu vine on mammary gland and uterus development in rats. METHOD: 40 Wistar rats weighting 65-85 g were randomly divided into 4 groups: control group, estrogen group, extracts of root of kudzu vine group of high dose, extracts of root of kudzu vine group of low dose. (10 rats in each group). After having been treated for 7 days, the rats were killed; mammary glands and uterus were removed and weighed. Serum was isolated and kept at 4 degrees C for determination of hormones. RESULT: 1. Administration of the root of kudzu vine significantly increased the weigh of mammary gland and uterus in rats. 2. Administration of the root of kudzu vine increased serum FSH, LH, E2 and decreased PRL. CONCLUSION: Extracts of root of kudzu vine could enhance the weight of mammary gland and uterus growth in rats, which may provide experimental evidence for the development of new drug used for promoting mammary gland and uterus.

Animals↗
PubMed1988

Lectin-enhanced accumulation of manganese-limited Rhizobium leguminosarum cells on pea root hair tips.

The ability of Rhizobium leguminosarum 248 to attach to developing Pisum sativum root hairs was investigated during various phases of bacterial growth in yeast extract-mannitol medium. Direct cell counting revealed that growth of the rhizobia transiently stopped three successive times during batch culture in yeast extract-mannitol medium. These interruptions of growth, as well as the simultaneous autoagglutination of the bacteria, appeared to be caused by manganese limitation. Rhizobia harvested during the transient phases of growth inhibition appeared to have a better attachment ability than did exponentially growing rhizobia. The attachment characteristics of these manganese-limited rhizobia were compared with those of carbon-limited rhizobia (G. Smit, J. W. Kijne, and B. J. J. Lugtenberg, J. Bacteriol. 168:821-827, 1986, and J. Bacteriol. 169:4294-4301, 1987). In contrast to the attachment of carbon-limited cells, accumulation of manganese-limited rhizobia (cap formation) was already in full progress after 10 min of incubation; significantly delayed by 3-O-methyl-D-glucose, a pea lectin haptenic monosaccharide; partially resistant to sodium chloride; and partially resistant to pretreatment of the bacteria with cellulase. Binding of single bacteria to the root hair tips was not inhibited by 3-O-methyl-D-glucose. Whereas attachment of single R. leguminosarum cells to the surface of pea root hair tips seemed to be similar for both carbon- and manganese-limited cells, the subsequent accumulation of manganese-limited rhizobia at the root hair tips is apparently accelerated by pea lectin molecules. Moreover, spot inoculation tests with rhizobia grown under various culture conditions indicated that differences in attachment between manganese- and carbon-limited R. leguminosarum cells are correlated with a significant difference in infectivity in that manganese-limited rhizobia, in contrast to carbon-limited rhizobia, are infective. This growth-medium-dependent behavior offers and explanation for the seemingly conflicting data on the involvement of host plant lectins in attachment of rhizobia to root hairs of leguminous plants. Sym plasmid-borne genes do not play a role in manganese-limitation-induced attachment of R. leguminosarum.

Carbon↗
PubMed2006

Identification of drought tolerance determinants by genetic analysis of root response to drought stress and abscisic Acid.

Drought stress is a common adverse environmental condition that seriously affects crop productivity worldwide. Due to the complexity of drought as a stress signal, deciphering drought tolerance mechanisms has remained a major challenge to plant biologists. To develop new approaches to study plant drought tolerance, we searched for phenotypes conferred by drought stress and identified the inhibition of lateral root development by drought stress as an adaptive response to the stress. This drought response is partly mediated by the phytohormone abscisic acid. Genetic screens using Arabidopsis (Arabidopsis thaliana) were devised, and drought inhibition of lateral root growth (dig) mutants with altered responses to drought or abscisic acid in lateral root development were isolated. Characterization of these dig mutants revealed that they also exhibit altered drought stress tolerance, indicating that this root response to drought stress is intimately linked to drought adaptation of the entire plant and can be used as a trait to access the elusive drought tolerance machinery. Our study also revealed that multiple mechanisms coexist and together contribute to whole-plant drought tolerance.

Abscisic Acid↗
PubMed2003

CGRP1 and NK1 receptors in postnatal, developing rat dental tissues.

There is little evidence that neuropeptides such as substance P (SP) and calcitonin gene-related peptide (CGRP) participate in the regulation of tooth development. The aim of this study was to analyse the expression of their respective receptors, neurokinin (NK) 1 and CGRP1 receptor, in postnatal developing rat molars and supporting tissues, thereby localizing the target areas for neuropeptide activity. Mol:WIST rats were killed at 7, 14 and 21 d after birth and upper and lower jaws were processed for immunohistochemistry. At early crown stage (P7), only a few individual cells in the dental follicle were receptor positive. At the onset of root formation (P14), post-secretory ameloblasts, cells in the stratum intermedium, the reduced enamel epithelium and the developing alveolar bone demonstrated both NK1 and CGRP1 receptor immunoreactivity. The CGRP1 receptor sites were occasionally evident on cells in the odontoblast layer. At advanced root development (P21), neuropeptide receptor expression was evident on cells close to the developing dentin, cementum and alveolar bone. These data demonstrate dynamic changes in the localization of NK1 and CGRP1 receptors in developing rat dental tissues and indicate an active role for their ligands in the regulation of crown and root development.

Animals↗
PubMed2006

Comparative postnatal development of spinal, trigeminal and vagal sensory root entry zones.

Somatic and visceral sensory information enters the central nervous system (CNS) via root entry zones where sensory axons span an environment consisting of Schwann cells in the peripheral nervous system (PNS) and astrocytes and oligodendrocytes in the CNS. While the embryonic extension of these sensory axons into the CNS has been well-characterized, little is known about the subsequent, largely postnatal development of the glial elements of the root entry zones. Here we sought to establish a comparative developmental timecourse of the glial elements in the postnatal (P0, P3, P7, P14) and adult rat of three root entry zones: the spinal nerve dorsal root entry zone, the trigeminal root entry zone, and the vagal dorsal root entry zone. We compared entry zone development based on the expression of antigens known to be expressed in astrocytes, oligodendrocytes, oligodendrocyte precursor cells, Schwann cells, radial glial fibres and the PNS extracellular matrix. These studies revealed an unexpected distribution among glial cells of several antigens. In particular, antibodies used to label mature oligodendrocytes (RIP) transiently labelled immature Schwann cell cytoplasm, and a radial glial antigen (recognized by the 3CB2 antibody) initially decreased, and then increased in postnatal astrocytes. While all three root entry zones had reached morphological and antigenic maturity by P14, the glial elements comprising the PNS-CNS interface of cranial root entry zones (the trigeminal root entry zone and the vagal dorsal root entry zone) matured earlier than those of the spinal nerve dorsal root entry zone.

Animals↗
PubMed2000

Root hair elongation is inhibited by hypaphorine, the indole alkaloid from the ectomycorrhizal fungus Pisolithus tinctorius, and restored by indole-3-acetic acid.

Hypaphorine, the major indolic compound isolated from the ectomycorrhizal fungus Pisolithus tinctorius, controls the elongation rate of root hairs. At inhibitory concentrations (100 microM), hypaphorine induced a transitory swelling of root hair tips of Eucalyptus globulus Labill. ssp. bicostata. When the polar tip growth resumed, a characteristic deformation was still visible on elongating hairs. At higher hypaphorine concentrations (500 microM and greater), root hair elongation stopped, only 15 min after application. However, root hair initiation from trichoblasts was not affected by hypaphorine. Hypaphorine activity could not be mimicked by related molecules such as indole-3-acetic acid (IAA) or tryptophan. While IAA had no activity on root hair elongation, IAA was able to restore the tip growth of root hairs following inhibition by hypaphorine. These results suggest that hypaphorine and endogenous IAA counteract in controlling root hair elongation. During ectomycorrhiza development, the absence of root hairs might be due in part to fungal release of molecules, such as hypaphorine, that inhibit the elongation of root hairs.

Basidiomycota↗
PubMed1996

Expression of a unique globo-series glycolipid in cultured rat dorsal root ganglion neurons: relationship with neuronal development.

Previous studied from the laboratory demonstrated the presence of a UDP-galactose:Gb3Cer alpha 1-3galactosyltansferase activity responsible for the synthesis of a unique glycosphingolipid (GSL), Gal alpha 1-3Gb3Cer, in cultured PC12 pheochromocytoma cells (21). In this investigation, we examined the presence of this enzyme activity in isolated rat embryonic dorsal root ganglion neurons (DRGN), which, like pheochromocytoma cells, originate from the neural crest cells. DRGN exhibited the alpha-galactosyltransferase activity and the activity was comparable to that of the PC12 cells while several other rat tissues, with the exception of kidney, showed minimal activity. In order to define the spatial and temporal expression of Gal alpha 1-3Gb3Cer in DRGN, we examined the expression of Gal alpha 1-3Gb3Cer in cultured DRGN derived from embryonic day 16 rat embryos. Using a polyclonal antibody raised against Gal alpha 1-3Gb3Cer, we examined the localization of this glycolipid in DRGN cells after 5, 8, 12, and 15 days in culture. Immunostaining was restricted to the neurons while Schwann cells were negative. At day 5, the immunostaining was weak and confined to the cell body of the DRGN, though neurites were present at this stage. The period between days 5 and 15 represented a period of rapid neuritic growth and continued enlargement of the cell bodies. Immunoreactivity in the cell bodies increased dramatically by day 8. By day 12, immunoreactivity was present in neurites, and by day 15, was strong in both cells bodies and neurites. The expression of Gal alpha 1-3Gb3Cer in vivo was confirmed by immunostaining of frozen sections of dorsal root ganglia. Our present studies which demonstrate neuron-specific expression of Gal alpha 1-3Gb3Cer during neurotigenesis combined with previous observations for its expression in PC12 cells, strongly implicates this GSL in neuronal development.

Animals↗