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PubMed1976

[Comparative action of chronic injection of alpha toxin from Naja nigricolis and of botulinum toxin A on the development of chick embryo dorsal and ventral spinal roots].

The chronic injection of high doses of alpha toxin from Naja nigricollis or botulinum toxin type A in the yolk sack of developing Chick embryos causes a selective decrease of the number of fibers in the ventral roots of the spinal nerves; at the concentrations needed this reduction is more important with the alpha toxin than with the botulinum toxin.

Animals↗
PubMed1996

Changing expression of intermediate filaments in fibroblasts and cementoblasts of the developing periodontal ligament of the rat molar tooth.

The distributing of vimentin and cytokeratin intermediate filaments within the cells of the dental follicle and developing periodontal ligament is described during eruption of the rat 1st molar tooth. Alcohol-fixed tissues from animals ranging from neonates to 12 wk old were cryosectioned, immunolabelled with monoclonal antibodies against vimentin and a range of cytokeratins and examined by indirect immunofluorescence. Vimentin was observed in follicular and periodontal ligament fibroblasts in all animals and at all stages of eruption. It was also observed in cementoblasts after disruption of the epithelial root sheath (of Hertwig) which is responsible for determining the shape of the developing root. Prior to eruption, cytokeratins were restricted to epithelial components of the developing tooth, including the root sheath. However, they were seen in cementoblasts on disruption of the root sheath at 2 wk and in periodontal ligament fibroblasts at 3 wk after birth, when the tooth was erupting but had not reached occlusion. On occlusion (at 4 wk), fibroblasts no longer labelled for cytokeratins but cementoblasts associated with acellular cementum formation continued to express them. These results demonstrate temporal and spatial changes within the cells of the developing periodontal connective tissues and suggest that the appearance of cytokeratins in periodontal fibroblasts and cementoblasts may be related to mechanical changes during tooth eruption. Further, the results suggest different origins for cementoblasts associated with cellular and acellular cementum formation.

Animals↗
PubMed2006

Constitutive arginine-dependent nitric oxide synthase activity in different organs of pea seedlings during plant development.

Nitric oxide (NO) is an important signalling molecule in different animal and plant physiological processes. Little is known about its biological function in plants and on the enzymatic source or site of NO production during plant development. The endogenous NO production from L-arginine (NO synthase activity) was analyzed in leaves, stems and roots during plant development, using pea seedlings as a model. NOS activity was analyzed using a novel chemiluminescence-based assay which is more sensitive and specific than previous methods used in plant tissues. In parallel, NO accumulation was analyzed by confocal laser scanning microscopy using as fluorescent probes either DAF-2 DA or DAF-FM DA. A strong increase in NOS activity was detected in stems after 11 days growth, coinciding with the maximum stem elongation. The arginine-dependent NOS activity was constitutive and sensitive to aminoguanidine, a well-known irreversible inhibitor of animal NOS, and this NOS activity was differentially modulated depending on the plant organ and seedling developmental stage. In all tissues studied, NO was localized mainly in the vascular tissue (xylem) and epidermal cells and in root hairs. These loci of NO generation and accumulation suggest novel functions for NO in these cell types.

Arginine↗
PubMed2005

The influence of growth regulators on shoot proliferation and rooting of in vitro propagated caper.

The objectives of this study were to examine the effect of TDZ and BAP on shoot proliferation and to develop a satisfactory rooting procedure for in vitro propagation of caper (Capparis spinosa L). TDZ was found to be more effective than BAP in shoot production. The highest shoot number per explant (45.7) was achieved on the media that contained 4.54 microM TDZ in the absence of IAA. TDZ at 4.54 microM alone or in combination with 0.57 microM IAA did not inhibit shoot elongation, although they produced the most shoots. Dipping the caper shoots in the solution of IBA at 24.6 microM for 10 minutes before planting on MS media, improved the rooting percentage up to 80.5% under a 16 hr photoperiod.

Agriculture↗
PubMed1984

Suppression of nodule development of one side of a split-root system of soybeans caused by prior inoculation of the other side.

In a split-root system of soybeans (Glycine max L. Merr), inoculation of one half-side suppressed subsequent development of nodules on the opposite side. At zero time, the first side of the split-root system of soybeans received Rhizobium japonicum strain USDA 138 as the primary inoculum. At selected time intervals, the second side was inoculated with the secondary inoculum, a mixture of R. japonicum strain USDA 138 and strain USDA 110. In a short-day season, nodulation by the secondary inoculum was inhibited 100% when inoculation was delayed 10 days. Nodulation on the second side was significantly suppressed when the secondary inoculum was delayed for only 96 hours. In a long-day season, nodule suppression on the second side was highly significant, but not always 100%. Nodule suppression on the second side was not related to the appearance of nodules or nitrogenase activity on the side of split-roots which were inoculated at zero time. When the experiments were done under different light intensities, nodule suppression was significantly more pronounced in the shaded treatments.

Journal Article↗
PubMed1996

Nitrogen dynamics in plant growth systems.

The predominant nitrogen source for the plants in closed environmental systems is the mineral nitrogen (i.e., nitrate and/or ammonium) in the nutrient medium. The following focuses on the processes through which plants obtain nitrate and ammonium from the rhizosphere and on the influences that each form has upon plant performance. Most plant species can sustain full growth at nitrate or ammonium concentrations that are over two orders of magnitude lower than those provided in most plant growth systems. Under the high concentrations (mM) normally used, root nitrogen absorption is downregulated: a) both the affinity and capacity of the transport systems for ammonium or nitrate are diminished, b) efflux of either ion becomes a significant percentage of influx, and c) root growth is inhibited. High concentrations also promote accumulation of ammonium or borate in plant tissues to potentially deleterious levels and foster microbial outbreaks. Several lines of evidence argue that roots in natural soils are normally exposed to lower concentrations (micromoles) of nitrate or ammonium: models of root nutrient absorption indicate that roots deplete rhizosphere nitrate and ammonium to such levels; the high-affinity transport systems for nitrate and ammonium have optimal control in this range; and root growth and development is maximized under such conditions. The high-affinity transport systems are distinct for nitrate and ammonium. In general, the affinity of the nitrate system for nitrate is less than the ammonium system for ammonium. Nitrate absorption is induced by the presence of ammonium or nitrate. Roots most rapidly absorb nitrate in the zone where root hairs emerge and ammonium in the zone of division near the apex. Nitrate absorption tends to alkalinize the rhizosphere, whereas ammonium absorption acidifies the rhizosphere. The energy requirements for absorption and assimilation of nitrate are several fold higher than those of ammonium. Root growth and elongation are more extensive when ammonium is provided as the sole nitrogen source, perhaps as a consequence of the lower energy requirements or the increased rhizosphere acidity.

Absorption↗
PubMed2000

Development of peripheral hindlimb and central spinal cord innervation by subpopulations of dorsal root ganglion cells in the embryonic rat.

The development of rat peripheral hindlimb and lumbar dorsal horn innervation by different subpopulations of dorsal root ganglion cells was investigated from embryonic day (E)13 to birth by using immunostaining. Antibodies to protein gene product (PGP) 9.5, growth associated protein (GAP) 43, and peripherin were used as pan-neuronal markers, RT97 for A fibres; calcitonin gene-related peptide (CGRP), trkA, and the lectin IB4 for small A and C fibres. Size frequency analysis showed that RT97 is a selective marker for large A cells at E18. Although both A and C fibres enter the hindlimb at E13-14, A fibres are the first to innervate the skin and dominate over small fibre innervation until later fetal life. CGRP expression in sensory axons appears at E19 and in all regions simultaneously, suggesting expression in existing fibres. All sensory terminals grow transiently to the skin surface before retracting subepidermally at late embryonic stages. The development of peripheral and central innervation by the same subpopulations of sensory neurons was compared. The entry of A fibre terminals into the lumbar dorsal horn at E14 coincided with hindlimb skin innervation. In contrast, C fibres were not detected in the dorsal horn until E18, 4 days after peripheral innervation. CGRP expression appears in both spinal cord and hindlimb targets at E19. IB4 binding in the central terminals began at E18 but was never observed in embryonic peripheral axons. These results demonstrate that in fetal skin, A fibre innervation dominates over C fibres. In addition, alathough peripheral and central innervation by A fibres coincide, this is not true for C fibres, suggesting that central target factors may control C fibre terminal growth within the dorsal horn.

Animals↗
PubMed1986

Comparison of tryptophan-labeled constituents of developing rodent molar enamel matrix, non-enamel occlusal cusp, Hertwig's epithelial root sheath, and presumptive root furcation regions: light microscopic autoradiography.

During the process of organogenesis involving the developing rodent molar and incisor tooth organs, novel gene products termed enamel proteins are expressed by ectodermally-derived enamel organ epithelia at precise times and positions within the course of morphogenesis. The present studies were designed to identify the relative distribution of tryptophan-labeled, non-collagenous, epithelial-derived proteins associated with rat maxillary first molar crown (M') and initial root formation. Our experimental strategy was to utilize semi-quantitative autoradiography methods to compare and contrast the distribution of silver grains resulting from tryptophan incorporation into developing postnatal pups associated with enamel matrix, non-enamel occlusal cusp, Hertwig's Epithelial Root Sheath (HERS), and presumptive root furcation regions of M'. Five-day-old Wistar rats were injected with 14C-labeled tryptophan. Four animals were sacrificed at 15 minutes and then at 1, 2, 4, and 24 hour intervals following the administration of this essential aromatic amino acid. Following fixation and subsequent processing for autoradiography, semiquantitative analyses were performed of the silver grain distribution localized within selected regions of the developing M' tooth organs. All enamel organ epithelia were found to incorporate tryptophan and silver grains were identified (above background) in the extracellular matrices (ECM) of the enamel matrix, non-enamel occlusal cusp adjacent to the inner enamel epithelia, and the ECM (2-4, micron) adjacent to presumptive root furcation and HERS regions. Tryptophan incorporation was not significant in the odontoblasts or dentine ECM of the crown or forming presumptive root regions. These results support the hypothesis that inner enamel epithelia associated with rat molar crown formation, as well as HERS, synthesize tryptophan-labeled, non-collagenous, ECM molecules. We speculate that HERS participates in root development by possibly producing non-collagenous proteins for intermediate cementum formation.

Amelogenesis↗
PubMed2004

Rapid and reliable DNA extraction techniques from trypan-blue-stained mycorrhizal roots: comparison of two methods.

Two improved DNA extraction techniques from trypan-blue-stained root fragments were developed and compared for rapid and reliable analyses. In Method A, 1 cm trypan-blue-stained mycorrhizal root fragments were individually isolated, crushed by bead beating, and purified with Chelex-100 (Bio-Rad). In Method B, DNA extraction was carried out using an UltraClean microbial DNA isolation kit (MoBio Laboratories). DNA was extracted from the mycorrhizal roots of four plant species, quantified by UV absorbance, and PCR-amplified with primers specific to arbuscular mycorrhizal fungi. Although PCR inhibitors might still exist when using Method A, appropriate dilution and employment of nested-PCR overcame this problem. Method B removed PCR inhibitors, but sometimes, depending on the mycorrhizal colonization within the root fragments, it also required nested PCR. In conclusion, both methods enabled us to handle many samples in a short time. Method B provided greater reliability and Method A provided better cost performance. Both techniques can be useful for PCR-based applications to identify species and estimate species composition after measuring mycorrhizal colonization rate with trypan blue staining.

DNA Primers↗
PubMed1999

Chewing tobacco use and dental caries among U.S. men.

BACKGROUND: Chewing tobacco has high levels of sugars and may be cariogenic, but few studies have investigated such an association. This study examined the relationship between chewing tobacco use and dental caries among U.S. adult men. METHODS: Participants in the Third National Health and Nutrition Examination Survey conducted from 1988 to 1994 were interviewed about tobacco use and examined by dentists. The authors included in their analysis dentate men 18 years of age or older. They calculated the mean number of decayed or filled permanent teeth, or DFT, and decayed or filled coronal tooth surfaces, or DFS, as well as the mean number and percentage of decayed or filled root surfaces, or RDFS, and decayed root surfaces, or RDS, by tobacco-use status. They used multiple logistic regression to examine the association between chewing tobacco use and root-surface caries. RESULTS: Men who currently used only chewing tobacco had a higher adjusted mean number of DFT than did those who currently used only snuff, only cigarettes or more than one form of tobacco or who never used tobacco. Mean DFS also was higher among chewing tobacco users than among those who used only snuff, only cigarettes or more than one form of tobacco. Chewing tobacco users had a higher mean RDFS and RDS than did the users of other forms of tobacco or nonusers. Current users of chewing tobacco were more than four times as likely as those who never used tobacco to have one or more RDFS or RDS, with a dose-response relationship between number of packages used per week and odds of having root-surface caries. CONCLUSIONS: In addition to its established role as a carcinogen, chewing tobacco may be a risk factor in the development of root-surface caries and, to a lesser extent, coronal caries. This may be due to high sugar content, increased gingival recession and enhanced collagenase activity. CLINICAL IMPLICATIONS: Interventions by dentists and other members of the oral health care team to prevent tobacco use and help users quit can reduce the risk of developing oral and systemic disease.

Adolescent↗
PubMed1997

Long-term dental development in children after treatment for malignant disease.

A radiographic dental examination was performed in 16 children conditioned with total body irradiation (TBI) and cyclophosphamide (CY) prior to bone marrow transplantation (BMT), and in 52 children treated with multiagent chemotherapy. For each child, three age- and sex-matched healthy controls were selected. Evaluation of disturbances in dental development and tooth size was based on planimetric measurements of mandibular teeth on panoramic radiographs. Short V-shaped roots were diagnosed in 94 per cent of the children treated with TBI/CY compared with 19 per cent in the chemotherapy group (P < 0.001). Children receiving TBI/CY also exhibited a pronounced reduction in tooth size compared with the controls. Reductions varied from 19 per cent in incisors to 39 per cent in the second molars. In the chemotherapy group the corresponding values were 7 and 15 per cent respectively. When comparing crown/root ratios, the indices for incisors, canines (P < 0.05) and molars (P < 0.01) in the BMT group were significantly higher than the corresponding values in the control group. This indicates that the reduction in root size was more pronounced than the reduction in crown size. The premolars in the BMT group exhibited a similar reduction in crown and root size. All developing teeth were affected by multiagent chemotherapy and radiation therapy. The most severe disturbances were found in children treated with TBI/CY at a young age.

Age Factors↗
PubMed1993

Development of the murine periodontium. II. Role of the epithelial root sheath in formation of the periodontal attachment.

Experimental manipulation of the developing murine tooth germ has provided evidence that basement membrane components on the forming root surface are involved in early periodontal attachment formation. The purpose of this investigation was to determine the role of epithelial root sheath (ERS) cells in murine cementogenesis and periodontal ligament formation using tissue separation and recombination techniques. Root dentin specimens, with and without root-associated basement membrane components (D + RBM or D - RBM), were recombined with dental sac in the presence or absence of ERS. Recombinations were cultured for 2 weeks, harvested, and examined by light, electron, and immunofluorescence microscopy. Mineralized tissue formed in all tissue recombinations. However, when ERS was included in recombinations between D + RBM and dental sac, 25% of recombinations formed a periodontal ligament with fibrous attachment of the root specimen to adjacent bone. These results support the hypothesis that root and periodontal ligament formation is influenced by epithelio-mesenchymal interactions and further support a key role for ERS in these processes.

Alveolar Process↗
PubMed2003

Novel hydrotropism mutants of Arabidopsis thaliana and their altered waving response and phototropism.

Roots display positive hydrotropism in response to a moisture gradient, which is important for plants to escape from water stress and regulate the directional growth by interacting with other growth movements such as gravitropism, phototropism and waving response. On Earth, hydrotropism is interfered by gravitropism in particular, so that microgravity conditions or agravitropic mutants have been used for the study of hydrotropism. However, we have recently established an experimental system for the study of hydrotropism in Arabidopsis roots that easily develop hydrotropism in response to moisture gradient by overcoming gravitropism. Using the Arabidopsis system, we isolated hydrotropism mutants named root hydrotropism (rhy). In the present study, we examined the hydrotropism, gravitropism, phototropism, waving response and elongation growth of rhy4 and rhy5 roots that were defective in positive hydrotropism. Interestingly, rhy4 roots curved away from the water source and showed a reduced waving response. Both rhy4 and rhy5 showed normal gravitropism and a slight reduction in phototropism. These results suggest that there is a mutual molecular mechanism underlying hydrotropism, waving response and/or phototropism. Thus, we have obtained novel hydrotropic mutants that will be used for revealing molecular mechanism of root hydrotropism and its interaction with waving response and/or phototropism.

Arabidopsis↗
PubMed1998

The effect on immunocytes of anodic oxide titanium after hydrothermal treatment.

All dental root implants come in contact with the oral epithelium, and many complex factors are found to arise in this region. In order to perform a successful dental root implantation, it is necessary to clarify the interaction of the dental root implant material with the host defense mechanisms involved in the specific and nonspecific immune responses to many antigens in oral bacteria and their components. Recently, focusing on developing the dental root implant, the Nikon Corporation improved the surface characteristics of pure titanium even further by developing a hydroxyapatite (HA) layer formed on an anodic titanium oxide film containing Ca and P via hydrothermal treatment (SA treatment). However, since little is known about the effect of SA-treated pure titanium (HA/Ti) on the defense mechanisms of the oral membrane epithelium, we investigated (1) the in vitro proliferation of murine splenic B lymphocytes on the surface of HA/Ti in the presence of three lipopolysaccharide (LPS) concentrations and (2) interleukin-1alpha (IL-1alpha) production by the reaction of human peripheral blood mononuclear cells (PBM cells) on the surface of HA/Ti under the same concentrations. After culture, murine splenic lymphocytes were measured by uptake of 3H-thymidine, and cytokine release (IL-1alpha) from PBM cells was measured by ELISA. Results showed that HA/Ti had hardly any effect on the LPS-induced proliferation of B lymphocytes and IL-1alpha production. In vitro investigations of the effects of HA/Ti on the LPS-induced proliferation of murine splenic B lymphocytes and IL-1alpha from PBM cells might be a useful way of elucidating the defense mechanism between implants and the oral epithelium.

Animals↗
PubMed1972

Induction and development of increased ion absorption in corn root tissue.

Washing excised or intact primary roots of corn (Zea mays L., WF9 x M14) in aerated distilled water or dilute salt solutions for 2 hours induced doubling of the rate of accumulation of various nutrient ions and solutes. This response to washing depended upon aerobic metabolism, but involved no increase in aerobic respiration. Excision of root tissue was not required as the effect could be obtained with intact root systems. Increased phosphate absorption followed after a lag period of 30 to 40 minutes and continued for 6 hours before leveling off at about 3.5 times the initial rate. Chloramphenicol was not inhibitory to the development of increased absorption, while inhibitors of RNA and protein synthesis were. Auxins and kinetin were also inhibitory, but so was the antiauxin, 2,4,6-trichlorophenoxyacetic acid.Kinetic analyses of phosphate and potassium ((86)Rb) absorption showed no change in apparent Michaelis constant. Electron microscopic examination and analysis for membrane protein and lipid-phosphate content after washing showed no proliferation of membrane or other changes in cell structure and composition. It appears that washing augments or activates existing membrane transport mechanisms by processes involving protein synthesis.

Journal Article↗
PubMed1991

The nuclear bomb: a concretization and erotization of power.

This article contends that the nuclear bomb is the concrete representation of an archaic idealizing system. It uses concepts published by Atwood and Stolorow (1984) to demonstrate how the bomb is no protection at all to our national defense; rather it compensates for empty or poorly developed psychological structure and function of individual and group. The continued proliferation of the bomb--some 70,000 at last count--despite the knowledge that just a few can obliterate our world is testimonial to the need for a concrete and visible mound of weapons. Since this need can never be satisfied by these means, there can never be enough bombs to be sufficient. The article extends the concept of this faulty or absent development of psychological structure to the weakening or loss of primary affiliative bonding between individuals and groups, which has psychohistorical roots. Three historical developments intertwine and reinforce one another: (1) the isolation of national defense to weapons and war; (2) the evolution of a modern science based on a duality between body (affects) and mind (cognition) and contributing to sexual polarization, in which masculinity has been identified with valued objectivity and femininity has been identified with devalued affiliative affects; (3) the equation of sex and aggression with power and their use as substitutes for derailed development of affiliative needs and functions.

Erotica↗