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Internal root resorption is classically described as resulting from long standing chronic inflammation in the pulp. The resorption may be transient, where lacunae present within the canal walls, or progressive, where the odontoblasts are destroyed and no predentine can be laid down. The diagnosis of this process and its subsequent treatment is described in this series of eight patients with internal root resorption.
Recurrent inhibition of the dorsal root (DR) evoked responses of frog motoneurons was studied by intracellular recording. Monosynaptic and early polysynaptic action potentials, as well as compound EPSPs initiated by a DR volley in motoneurons were depressed by an antidromic volley in motor axons. The depression had about 10 msec latency, reached maximum at 20-30 msec, and was maintained for 80 msec. The depression was associated with a slow, negative dorsal root potential (VR-DRP) of similar time course. No sign of recurrent postsynaptic inhibition of the motoneuron somata was found. Decrease in excitability of the motoneurons was also observed during the afterhyperpolarization (AHP) associated with either antidromic or direct spikes in the motoneurons. This excitability decrease was detectable at the time of recurrent depression of the DR-evoked responses. The data are explained by the assumption that two mechanisms are involved in the recurrent depression of the DR-evoked responses: the excitability decrease during the AHP in the motoneurons themselves, and the inhibition transmitted by a recurrent pathway which may depress the DR inputs to motoneurons presynaptically.
1. The effect of tetanus toxin injected into one gastrocnemius muscle on the steady state concentration of several amino acids was investigated in spinal cord half segments, spinal roots and dorsal root ganglia of rats. Care was taken to ensure a symmetrical afferent input to the spinal cord and to localize the segment with the highest concentration of tetanus toxin. 2. In the spinal cord segments containing the highest concentration of tetanus toxin the steady state concentration of glycine was higher on the side of the tetanus than on the contralateral control side. Results obtained after intravenous injection of 14C-glycine do not indicate that the higher concentration of glycine on the side of the tetanus was due to a higher uptake of glycine. 3. The results obtained in the spinal cord contradict previous findings of other authors but lend support to the prevailing concept about the action of tetanus toxin in local and general tetanus.
The behavior of epithelial cells during tooth root formation in porcine molars was investigated using TUNEL, immunohistochemical and transmission electron microscopic methods. Cells of Hertwig's epithelial root sheath (HERS) expressed bcl-2, but were TUNEL-negative. Epithelial cells of HERS were tightly connected and surrounded by a continuous basement membrane. When dental papilla cells were attached to the inner HERS, they became positive for osteopontin (OPN). The inner basement membrane was intermittent immediately after those cells started to synthesize dentin matrix, and the intercellular spaces of the HERS became wider. Dental sac cells then migrated between the fragmented HERS and were directly connected to epithelial cells by desmosome-like structures. After the cementum was synthesized by these mesenchymal cells, epithelial cells aggregated to form cell clusters, which were again surrounded by a continuous basement membrane. These results suggest that fragmentation of the HERS is due to the invasion of dental sac cells, but is not related to cell death. Furthermore, the differentiation of dental papilla cells into odontoblasts occurred following their connection to the HERS through the basement membrane. Moreover, it is suggested that the differentiation of dental sac cells into cementoblasts occurred upon their direct connection to epithelial cells of the HERS.
An analysis of the mechanics required for distal movement of canine roots is presented and, on the basis of this analysis, a specific clinical approach is outlined. Three different root spring designs were tested for their ability to meet the previously determined requirements. The only spring that approached the established requirements was spring A-2. Spring types B and C did not meet the established requirements. Angular activations in excess of 20 degrees in 0.018 by 0.025 inch stainless steel wire without benefit of a loop resulted in permanent deformation of the appliance.
A case of unusual dental findings associated with mild growth and mental retardation is presented. The patient, a 15-year-old girl, manifests small teeth with peculiar short bulbous roots and roundly widened root canals, congenital absence of permanent teeth, strabismus, short stature, and borderline mentality.
We investigated the localization of GalNAc-GD1a biochemically in the human and bovine peripheral nervous system (PNS). The high-performance thin-layer chromatography (HPTLC)-overlay method with rabbit IgG polyclonal antibody against GalNAc-GD1a (anti-GalNAc-GD1a antibody) revealed expression of GalNAc-GD1a in the ventral spinal nerve roots (VRs) but not in the dorsal spinal nerve roots (DRs) of both species. The amount of GalNAc-GD1a in the human and bovine VRs was 2.22 +/- 0.35 microg/g wet tissue and 7.71 +/- 0.49 microg/g wet tissue, respectively. These results suggest that IgG anti-GalNAc-GD1a antibody may be involved in disturbance of peripheral motor nerves and in the pathogenesis of pure motor neuropathy.
The detailed status of the transcription of genes on pRil724 T-DNA in two independent hairy root lines of the plant Ajuga reptans, Ar-4 and Ar-24, which have several different characteristics, was obtained by Northern blotting and a reverse transcription-polymerase chain reaction (RT-PCR) analysis. In the Northern blotting analysis DNA fragments corresponding to the putative open reading frames (ORFs) as probes, transcripts from putative ORFs 10 (1724rolA), 11 (1724rolB), 12 (1724rolC), 13a and 14, which are homologs to each ORF on pRiA4, were detected in both hairy root lines, whereas no transcripts derived from ORF 13 were detected. The transcription of ORF 13 was, however, detected in the RT-PCR analysis, suggesting a minor expression of ORF 13. All of the putative ORFs were transcribed with their expected directions, since DNA fragments were amplified when the antisense primers were employed in the reverse transcription. We also found that different transcripts with a reverse direction were present at the locations of 1724rolA, 1724rolC and ORF 13a, because the DNA fragments were amplified from the templates when their sense primers were used in the reverse transcription.
We previously reported that slow depolarization of substantia gelatinosa neurons is evoked by repetitive stimulation of C-fibers of dorsal root in adult rat spinal cord transverse slices with the dorsal root attached, which was considered to be an event relevant to spinal nociception. In the present study, we investigated the effects of adenosine 5'-triphosphate (ATP) and its analogs on the slow depolarization. ATP (10-100 microM) significantly inhibited the amplitude of slow depolarization in a concentration-dependent manner. The inhibitory effect of ATP was not reversed by suramin, an antagonist for some P2-purinoceptors, and was mimicked by a P2Y selective agonist uridine 5'-triphosphate, but not a P2X selective agonist alpha,beta-methylene ATP. These results suggest that ATP inhibits the slow depolarization of substantia gelatinosa neurons relevant to nociceptive transmission in the spinal dorsal horn, via suramin-insensitive P2Y purinoceptors.
In previous studies, 15 putative allelopathic compounds detected in rice root exudates were quantified by GC/MS/MS. In this study, multiple regression analysis on these compounds determined that five selected phenolics, namely caffeic, p-hydroxybenzoic, vanillic, syringic, and p-coumaric acids, from rice exudates were best correlated with the observed allelopathic effect on arrowhead (Sagittaria montevidensis) root growth. Despite this positive association, determination of the phenolic acid dose-response curve established that the amount quantified in the exudates was much lower than the required threshold concentration for arrowhead inhibition. A similar dose-response curve resulted from a combination of all 15 quantified compounds. Significant differences between the amounts of trans-ferulic acid, abietic acid, and an indole also existed between allelopathic and non-allelopathic rice cultivars. The potential roles of these three compounds in rice allelopathy were examined by chemoassay. Overall, neither the addition of trans-ferulic acid nor 5-hydroxyindole-3-acetic acid to the phenolic mix significantly contributed to phytotoxicity, although at higher concentrations, trans-ferulic acid appeared to act antagonistically to the phytotoxic effects of the phenolic mix. The addition of abietic acid also decreased the inhibitory effect of the phenolic mix. These studies indicate that the compounds quantified are not directly responsible for the observed allelopathic response. It is possible that the amount of phenolic acids may be indirectly related to the chemicals finally responsible for the observed allelopathic effect.
The present study examines the dental root after Er:YAG laser irradiation, compared with CO2 lased and non-treated surfaces, using Fourier Transformed Infrared (FTIR) spectroscopy. Freshly extracted human teeth were irradiated by Er:YAG laser at an energy output of 40 mJ/pulse, 10 Hz (0.4 watts), with or without water coolant, and by CO2 laser at an energy output of 0.5 watts in continuous wave mode without coolant. The surfaces were chalky and smooth after irradiation by Er:YAG laser with water coolant, were charred and irregular after irradiation by Er:YAG laser without water coolant, and were completely carbonized after CO2 laser irradiation. The FTIR profiles from samples of the surfaces that were irradiated by Er:YAG laser with water coolant were similar to those from non-treated samples, except for a slight decrease on the OH and amide bands, which are mainly related to organic components. This decrease was observed to be extreme after CO2 laser irradiation and moderate after Er:YAG laser irradiation without coolant. The formation of new bands showing toxic substances was observed to a large extent after CO2 laser irradiation and to a smaller extent after Er:YAG laser irradiation without water coolant. In contrast, no such bands were detected after Er:YAG laser irradiation with water coolant. The present results show that these laser treatments selectively ablated more organic components than inorganic components and that Er:YAG laser irradiation with water coolant did not cause major compositional changes or chemically deleterious changes in either root cementum or dentin.
Implants and fixed and removable prostheses are very successful in replacing missing units but their cost can be inhibitory to a number of patients. In addition fixed and removable prostheses can be destructive to sound abutment teeth and can result in damage to dental and soft tissue. This report describes the restoration of a tooth with a complicated incisor crown-root fracture that extended below both the gingival cuff and the alveolar crest, by using remaining tooth tissue. The restoration was completed after root extrusion with a cast post, diaphragm and core, and porcelain crown.
The mechanisms involved in regulating high-affinity ammonium (NH4+) uptake and the expression of the AtAMT1 gene encoding a putative high-affinity NH4+ transporter were investigated in the roots of Arabidopsis thaliana. Under conditions of steady-state nitrogen (N) supply, transcript levels of the AtAMT1 gene and Vmax values for high-affinity 13NH4+ influx were inversely correlated with levels of N provision. Following re-supply of NH4NO3 to N-starved plants, AtAMT1 mRNA levels and 13NH4+ influx declined rapidly but remained high when the conversion of NH4+ to glutamine (Gln) was blocked with methionine sulfoximine (MSX). This result demonstrates that end products of NH4+ assimilation, rather than NH4+ itself, are responsible for regulating AtAMT1 gene expression. Consistent with this hypothesis, AtAMT1 gene expression and NH4+ influx were suppressed by provision of Gln alone, or together with NH4NO3 plus MSX. Furthermore, AtAMT1 transcript levels and 13NH4+ influx were negatively correlated with root Gln concentrations, following re-supply of N to N-starved plants. In addition to this level of control, the data suggest that high cytoplasmic [NH4+] may inhibit NH4+ influx.
Arabinogalactan-proteins (AGPs) are extracellular proteoglycans that are implicated in many plant growth and developmental processes, but in no case has a biological function been assigned to a particular AGP. AtAGP30 is a non-classical AGP core protein from Arabidopsis that is expressed only in roots. Analysis of the corresponding mutant, agp30, has revealed that the wild-type gene product is required in vitro for root regeneration and in planta for the timing of seed germination. The mutant shows a suppression of the abscisic acid (ABA)-induced delay in germination and altered expression of some ABA-regulated genes. This suggests that AtAGP30 functions in the ABA response. By analogy to proteoglycan-mediated regulation of growth-factor-signalling pathways in animals, our data indicate that phytohormone activity in plants can be modulated by AGPs.
Secreted parasitism proteins encoded by parasitism genes expressed in esophageal gland cells mediate infection and parasitism of plants by root-knot nematodes (RKN). Parasitism gene 16D10 encodes a conserved RKN secretory peptide that stimulates root growth and functions as a ligand for a putative plant transcription factor. We used in vitro and in vivo RNA interference approaches to silence this parasitism gene in RKN and validate that the parasitism gene has an essential function in RKN parasitism of plants. Ingestion of 16D10 dsRNA in vitro silenced the target parasitism gene in RKN and resulted in reduced nematode infectivity. In vivo expression of 16D10 dsRNA in Arabidopsis resulted in resistance effective against the four major RKN species. Because no known natural resistance gene has this wide effective range of RKN resistance, bioengineering crops expressing dsRNA that silence target RKN parasitism genes to disrupt the parasitic process represents a viable and flexible means of developing novel durable RKN-resistant crops and could provide crops with unprecedented broad resistance to RKN.
Lateral root (LR) formation in Arabidopsis is regulated by auxin signaling through AUXIN RESPONSE FACTOR transcriptional activators, ARF7 and ARF19, and auxin/indole-3-acetic acid (Aux/IAA) repressors, including SOLITARY-ROOT (SLR)/IAA14. Previous studies have strongly suggested that, in the gain-of-function slr-1 mutant, stabilized mutant IAA14 (mIAA14) protein inactivates ARF7/19 functions, thereby completely blocking LR initiation. However, the mechanism of inactivation is still unknown. We have now identified an extragenic suppressor mutation of slr-1, suppressor of slr2 (ssl2), which specifically restores LR formation in the slr-1 mutant, and have found that SSL2 negatively regulates the auxin-induced pericycle cell divisions required for LR initiation. The SSL2 gene encodes PICKLE (PKL), a homologue of the animal chromatin-remodeling factor CHD3/Mi-2, and LR formation restored in pkl/ssl2 slr-1 mutants depends on ARF7/19 functions, suggesting that ARF7/19-dependent transcription takes place if there is a pkl/ssl2 mutation in slr-1. In animals, Mi-2 represses transcription as a subunit of the NuRD/Mi-2 complex containing histone deacetylases (HDACs). Inhibition of HDAC activity by trichostatin A also results in LR formation in the slr-1 mutant, but not in the slr-1 arf7 arf19 triple mutant, suggesting that normal HDAC activity is required for the mIAA14-mediated inactivation of ARF7/19 functions in LR initiation. Taken together, our data suggest that PKL/SSL2-mediated chromatin remodeling negatively regulates auxin-mediated LR formation in Arabidopsis.
The present study aimed to investigate the effects of root surface iron plaque on the uptake kinetics of arsenite and arsenate by excised roots of rice (Oryza sativa) seedlings. The results demonstrated that the presence of iron plaque enhanced arsenite and decreased arsenate uptake. Arsenite and arsenate uptake kinetics were adequately fitted by the Michaelis-Menten function in the absence of plaque, but produced poor fits to this function in the presence of plaque. Phosphate in the uptake solution did not have a significant effect on arsenite uptake irrespective of the presence of iron plaque; however phosphate had a significant effect on arsenate uptake. Without iron plaque, phosphate inhibited arsenate uptake. The presence of iron plaque diminished the effect of phosphate on arsenate uptake, possibly through a combined effect of arsenate desorption from iron plaque.
Qualitative polarized light microscopy and cross-sectional microhardness testing profiles were used to compare artificial root caries lesions with those naturally present in extracted human teeth. The artificial lesions were produced by immersion of roots with exposed windows in chemical buffers of acetate and lactate with no added enzymes or bacteria. The three buffer systems used produced lesions with the range of histological characteristics of natural lesions. These included a 'body' or 'surface' zone of the lesion when viewed in water, and a 'frontal' zone of reverse birefringence when viewed in quinoline. The 'frontal' zone was noted to first develop after three days of immersion in acetate buffer. Advanced natural lesions exhibited a wide, diffuse, advancing front, which was similar to that produced by 28-60 day lesions in acetate. Microhardness profiles of natural lesions could all be matched by one or more of the artificial lesions. The demineralizing process was seen to reduce mineral content across the lesion from 45 per cent in normal dentine to between 15 and 25 per cent.