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PubMedDate not supplied

Root growth and physiology of potted and field-grown trembling aspen exposed to tropospheric ozone.

We studied root growth and respiration of potted plants and field-grown aspen trees (Populus tremuloides Michx.) exposed to ambient or twice-ambient ozone. Root dry weight of potted plants decreased up to 45% after 12 weeks of ozone treatment, and root system respiration decreased by 27%. The ozone-induced decrease in root system respiration of potted plants was more closely correlated with decreased root dry weight than with specific root respiration, suggesting that aspen root metabolism was less affected by ozone than root growth. We used minirhizotrons to study the appearance and disappearance of roots in the field. Length of live roots of field-grown trees increased rapidly early in the season and peaked by midseason in association with a decrease in root production and an increase in root disappearance. In the twice-ambient ozone treatment, live root lengths were 17% less than those of controls, but the effect was not statistically significant. Seasonal soil CO(2) efflux of field-grown trees decreased significantly in the ozone treatments, but because differences in live root length were not significant and root dry weights were not available, the effect on CO(2) efflux could not be attributed directly to decreased root growth.

Journal Article↗
PubMedDate not supplied

Responses of loblolly pine, sweetgum and crab grass roots to localized increases in nitrogen in two watering regimes.

Root responses to differences in availability of nitrogen and soil water were studied in loblolly pine (Pinus taeda L.) seedlings grown in monoculture and in competition with sweetgum (Liquidambar styraciflua L.) or crab grass (Digitaria spp.). Rhizotron cells were maintained at high soil water availability (approximately -0.1 MPa) or subjected to three dry-down cycles to low soil water availability (approximately -1.0 MPa), over two growing seasons. Localized increases in nitrogen availability were created by adding nitrogen in solution to root ingress cores placed in each rhizotron cell. Presence of competitors reduced loblolly pine root growth regardless of the nitrogen or soil water treatment. On average, both total root length density and root surface area were reduced 60% when loblolly pine seedlings were grown with crab grass and 31% when grown with sweetgum. Low water availability reduced loblolly pine root length density and root surface area by 25 and 28%, respectively, compared with well-watered seedlings. Sweetgum root surface area was reduced 18% by the low water availability treatment, whereas crab grass root surface area was unaffected by this treatment. At all soil depths, loblolly pine root surface area and root length density were increased in localized areas of increased nitrogen availability. Sweetgum and crab grass root surface areas were also greater in areas of increased nitrogen availability. In the high soil water availability treatment, loblolly pine root surface area increased 128% in localized areas of increased nitrogen in all competition treatments. In the low soil water availability treatment, loblolly pine roots responded to increased nitrogen only in the absence of competitors. In general, loblolly pine and sweetgum roots responded to increases in resource availability similarly, whereas crab grass roots were relatively less affected.

Journal Article↗
PubMed1992

Alteration of thiol pools in roots and shoots of maize seedlings exposed to cadmium : adaptation and developmental cost.

Roots of intact 5-day-old maize (Zea mays L.) seedlings were exposed to 3 micromolar Cd during a 7-day period. Cysteine, gamma-glutamylcysteine, glutathione (GSH), and Cd-induced acid-soluble thiols (ASTs), including phytochelatins, were quantified in roots and shoots. Adaptation to Cd and its cost to seedling development were evaluated by measuring Cd content, tissue fresh weight, and rate of root elongation. Roots contained 60 to 67% of the Cd in the seedlings between 4 and 7 days of exposure. Exposure to Cd decreased the fresh weight gain in roots from day 4 onward without affecting the shoots. Between days 1.5 and 3.5 of Cd treatment, roots elongated more slowly than controls; however, their growth rate recovered thereafter and exceeded that of controls. Exposure to Cd did not appreciably affect the concentration of cysteine in the seedlings. However, the initial low concentration of gamma-glutamylcysteine increased (after a lag of 6 hours in roots and 2 days in shoots), reaching a plateau by day 6 at 28.5 nanomoles per gram of fresh weight in roots and by day 5 at 19.1 nanomoles per gram of fresh weight in shoots. During the first 9 hours of Cd exposure, the concentration of GSH in roots decreased dramatically (at 31.6 nanomoles per gram of fresh weight per hour) and thereafter decreased more slowly than in controls. The depletion of GSH in the roots (366 nanomoles per gram of fresh weight) matched the synthesis of ASTs (349 nanomoles per gram of fresh weight) during the first 48 hours. The concentration of ASTs in roots increased steadily thereafter to reach 662.2 nanomoles per gram of fresh weight by 6 days of Cd exposure. In shoots, Cd had little influence on the concentration of GSH, but ASTs still accumulated to 173.3 nanomoles per gram fresh weight after 5 days. The molar ratio of thiols in ASTs to Cd increased to a maximum of 10.24 in roots after 4 hours and of 4.25 in shoots after 2 days of Cd exposure. After 4 days, the ratio reached a plateau of approximately 2 in roots and between 2 and 3 in shoots, as if a steady state of Cd chelation had been achieved in both organs. The plateau coincided with recovered root elongation or an adaptation to Cd. The reduced fresh weight gain of the roots during this time, however, indicated that the synthesis of Cd-induced thiols was at a cost to root development.

Journal Article↗
PubMedDate not supplied

Characteristics of nerve root compression caused by degenerative lumbar spinal stenosis with scoliosis.

BACKGROUND CONTEXT: In degenerative lumbar spinal stenosis with scoliosis (DLS), many authors stated that nerve root compression is almost always seen on the concave side of the scoliosis, and L4 and L5 nerve roots are the most often involved. However, there are few reports on the relationship between nerve root compression and the pattern of scoliosis. PURPOSE: To investigate the factors that may contribute to radiculopathy in DLS and their association with the pattern of the scoliosis. STUDY DESIGN: Retrospective analysis. METHODS: Twenty-two consecutive patients with DLS with radiculopathy were examined. The symptomatic nerve roots were determined by pain distribution, neurological findings and nerve root infiltration using lidocaine. The compressive factors were diagnosed by magnetic resonance imaging or myelography, discography, computed tomography after myelography or discography and radiculography. The pattern of scoliosis was determined in plain radiographs. We evaluated the correlation between the affected nerve root and the compressive factors or the pattern of the scoliosis. RESULTS: The L3 root was affected in 23% of patients; L4 root in 68%, L5 root in 55% and S1 root in 18%. L3 and L4 roots were more compressed by foraminal or extraforaminal stenosis on the concave side of the curve, whereas L5 and S1 roots were commonly affected by lateral recess stenosis on the convex side. The Cobb angle and the lateral slip of the cases in which L3 or L4 root was affected were significantly larger than in cases in which L5 or S1 root was compressed. CONCLUSIONS: In the treatment of radiculopathy caused by DLS, it is important to bear in mind that L3 or L4 roots were more strongly compressed by foraminal or extraforaminal stenosis at the concave side of the curve, whereas L5 or S1 nerve roots were affected more by lateral recess stenosis at the convex side of the curve.

Aged↗
PubMed1985

Calcium movement, graviresponsiveness and the structure of columella cells and columella tissues in roots of Allium cepa L.

Roots of Allium cepa L. cv. Yellow are differentially responsive to gravity. Long (e.g. 40 mm) roots are strongly graviresponsive, while short (c.g. 4 mm) roots are minimally responsive to gravity. Although columella cells of graviresponsive roots are larger than those of nongraviresponsive roots, they partition their volumes to cellular organelles similarly. The movement of amyloplasts and nuclei in columella cells of horizontally-oriented roots correlates positively with the onset of gravicurvature. Furthermore, there is no significant difference in the rates of organellar redistribution when graviresponsive and nongraviresponsive roots are oriented horizontally. The more pronounced graviresponsiveness of longer roots correlates positively with (1) their caps being 9-6 times more voluminous, (2) their columella tissues being 42 times more voluminous, (3) their caps having 15 times more columella cells, and (4) their columella tissues having relative volumes 4.4 times larger than those of shorter, nongraviresponsive roots. Graviresponsive roots that are oriented horizontally are characterized by a strongly polar movement of 45Ca2+ across the root tip from the upper to the lower side, while similarly oriented nongraviresponsive roots exhibit only a minimal polar transport of 45Ca2+. These results indicate that the differential graviresponsiveness of roots of A. cepa is probably not due to either (1) ultrastructural differences in their columella cells, (2) differences in the rates of organellar redistribution when roots are oriented horizontally. Rather, these results indicate the graviresponsiveness may require an extensive columella tissue, which, in turn, may be necessary for polar movement of 45Ca2+ across the root tip.

Biological Transport↗
PubMed1992

Stimulation of root elongation and curvature by calcium.

Ca2+ has been proposed to mediate inhibition of root elongation. However, exogenous Ca2+ at 10 or 20 millimolar, applied directly to the root cap, significantly stimulated root elongation in pea (Pisum sativum L.) and corn (Zea mays L.) seedlings. Furthermore, Ca2+ at 1 to 20 millimolar, applied unilaterally to the caps of Alaska pea roots, caused root curvature away from the Ca2+ source, which was caused by an acceleration of elongation growth on the convex side (Ca2+ side) of the roots. Roots of an agravitropic pea mutant, ageotropum, responded to a greater extent. Roots of Merit and Silver Queen corn also responded to Ca2+ in similar ways but required a higher Ca2+ concentration than that of pea roots. Roots of all other cultivars tested (additional four cultivars of pea and one of corn) curved away from the unilateral Ca2+ source as well. The Ca(2+)-stimulated curvature was substantially enhanced by light. A Ca2+ ionophore, A23187, at 20 micromolar or abscisic acid at 0.1 to 100 micromolar partially substituted for the light effect and enhanced the Ca(2+)-stimulated curvature in the dark. Unilateral application of Ca2+ to the elongation zone of intact roots or to the cut end of detipped roots caused either no curvature or very slight curvature toward the Ca2+. Thus, Ca2+ action on root elongation differs depending on its site of application. The stimulatory action of Ca2+ may involve an elevation of cytoplasmic Ca2+ in root cap cells and may partipate in root tropisms.

Abscisic Acid↗
PubMed2005

Effect of customization of master gutta-percha cone on apical control of root filling using different techniques: an ex vivo study.

AIMS: (i) To compare the prevalence of extrusion of root filling material when placed using different root filling techniques, with or without customization of the master gutta-percha (GP) cone; and (ii) to investigate the effects of some factors influencing root filling extrusion and presence of voids. METHODOLOGY: A total of 180 roots were selected, prepared and randomly allocated to three groups. Five general dental practitioners performed the root fillings; each filled one group of roots (n = 60) using each of three techniques; 'cold lateral compaction' (n = 20), 'warm vertical compaction' (n = 20) and 'continuous-wave' (n = 20) techniques. For each obturation technique, the master GP cone was customized using chloroform in 10 samples. Two groups of the roots were recycled to allow all five operators to fulfill their remit. Two observers, blind to operator and obturation technique, examined the radiographs (master apical file, post-obturation) to determine the presence of root filling extrusion and voids within the apical 5 mm, independently. Root filling extrusion was also confirmed by direct inspection of the root apex after obturation. The data were analysed using logistic regression models. RESULTS: A total of 300 root fillings were performed; nine were excluded from the analysis. Most of the root fillings (80%, n = 233) were placed within 0.5 mm of the working length; only 20% (n = 58) were placed >0.5 mm beyond the working length. The odds of prevalence of extrusion (>0.5 mm) were significantly reduced by about 50% when cold lateral compaction or customization of GP were used. One operator produced 2.5 times more extruded root fillings than others. Curvature & length of root canal, apical size of prepared canal, as well as operator's preferred obturation technique had no significant influence on the prevalence of extrusion. Customization of GP was the sole factor to significantly reduce the prevalence of voids within the apical 5 mm of working length. CONCLUSIONS: Root filling extrusion was significantly influenced by 'operator' and was reduced by cold lateral compaction and customization of the master cone. Customization of master cone was the only factor that reduced voids apically.

Clinical Competence↗
PubMed2000

[Studies comparing the efficacy of root canal filling with gutta-percha lateral condensation and Thermafil obturators].

A comparative analysis of the efficacy of root canal filling with laterally condensed gutta-percha and Thermafil obturators with titanium carrier was performed on the basis of experimental and clinical findings. Experimental part. Twenty-four extracted human teeth with root canals filled with laterally condensed gutta-percha (12 teeth) or Thermafil obturators (12 teeth) were studied in order to evaluate the quality of root filling. The Apexit sealer was used in both groups. Radiographs were obtained and the linear dye penetration test was done. Placement, homogeneity and adaptation of root canal filling were evaluated on the radiographs. Twenty teeth with root canals filled with laterally condensed gutta-percha (10 teeth) or Thermafil obturators (10 teeth) were studied using SEM. Clinical part. Eighty-seven patients were enrolled. One hundred and sixty-two single canal teeth with irreversible pulp disease with vitale (70 cases) or necrotic (54 cases) pulp and chronic apical parodontitis (38 cases) comprised the study material. Group I consisted of 84 teeth with root canals filled with laterally condensed gutta-percha, while group II had 78 teeth with Thermafil obturators. The Apexit sealer was applied in both groups. In vitro radiological examination revealed a better quality of placement of root canal fillings in group I (11 correctly filled root canals, 1 underfilling) when compared to group II (1 correctly filled root canal, 11 overfillings). No differences were observed between groups as to homogeneity or adaptation of root canal filling. The seal evaluated using the linear dye penetration test revealed no differences between both types of root canal filling. SEM confirmed the presence of interfaces between the filling material and root canal wall in both groups. The width of interface in group I was 1-5 microns, seldom exceeding 10 microns, and uniform throughout the whole root canal. In group II the width varied from 1-5 microns in the apical part to 10-25 microns in the middle and coronal parts. SEM revealed no major differences regarding homogeneity between both groups. Radiographs performed in the clinical part showed a higher frequency of overfillings of root canal filling into the apical parodontium in group I (30.8%) than II (9.5%). Thermafil turned out to be less satisfactory with regard to adaptation of root canal filling to the canal walls. Evaluation of immediate results of treatment demonstrated no differences between both techniques. A positive result after one year was found in 94.2% of laterally condensed gutta-percha fillings and in 90.2% of Thermafil fillings. After two years, the respective figures were 93.7% and 90.0%. The use of Thermafil obturators seems to be less tedious and time-consuming when compared to laterally condensed gutta-percha.

Adolescent↗
PubMed2005

[Curve analysis and geometric measurement of root canal curvatures].

PURPOSE: To study the anatomical features of curved root canals. METHODS: According to Nagy's classification,the root canals were divided into 4 types:type I (straight), type C (continuously curved), type J (apically curved) and type S (multicurved). Each type had a sample selected from extracted permanent teeth. Digital radiographs were taken at buccolingual and mesiodistal directions with a K-file inserted into the root canal. The images were treated by Photoshop7.0 and CorelTRACE10 softwares, after that a CAD/CAM software UG NX V1.0 was applied to extract the 2D curves of the root canal axis from the images,then the 3D curves of the root canal axis were built up accordingly. The curvature of the curves was analysed and the geometric parameters were measured by UG. RESULTS: The curvature values of type I root canal were very low; the curvature of type C root canal reached a peak on the middle part,it decreased slowly towards the two ends; type J root canal had a curvature peak near the root apex, and the middle 1/3 and neck 1/3 parts of the root canal were "curvature flat zones". Type S root canal had a curvature inflection,and beside it were 2 curvature peaks at opposite directions. The geometric parameter values of the same root canal's 2D and 3D axis were different. CONCLUSION: Each point on the root canal axis had a curvature value and a vector of tangent, different root canal forms had different rules of curvature distribution, just 1 or 2 parameters couldn't describe a curved root canal completely.

Dental Pulp Cavity↗
PubMed2000

Hyperaccumulation of cadmium by hairy roots of Thlaspi caerulescens.

Hairy roots were used to investigate cadmium uptake by Thlaspi caerulescens, a metal hyperaccumulator plant with potential applications in phytoremediation and phytomining. Experiments were carried out in nutrient media under conditions supporting root growth. Accumulation of Cd in short-term (9-h) experiments varied with initial medium pH and increased after treating the roots with H(+)-ATPase inhibitor. The highest equilibrium Cd content measured in T. caerulescens roots was 62,800 microg g(-1) dry weight, or 6.3% dry weight, at a liquid Cd concentration of 3710 ppm. Cd levels in live T. caerulescens roots were 1.5- to 1.7-fold those in hairy roots of nonhyperaccumulator species exposed to the same Cd concentration, but similar to the Cd content of autoclaved T. caerulescens roots. The ability to grow at Cd concentrations of up to 100 ppm clearly distinguished T. caerulescens hairy roots from the nonhyperaccumulators. The specific growth rate of T. caerulescens roots was essentially unaffected by 20 to 50 ppm Cd in the culture medium; in contrast, N. tabacum roots turned dark brown at 20 ppm and growth was negligible. Up to 10,600 microg g(-1) dry weight Cd was accumulated by growing T. caerulescens hairy roots. Measurement of Cd levels in whole roots and in the cell wall fraction revealed significant differences in the responses of T. caerulescens and N. tabacum roots to 20 ppm Cd. Most metal was transported directly into the symplasm of N. tabacum roots within 3 days of exposure; in contrast, T. caerulescens roots stored virtually all of their Cd in the wall fraction for the first 7 to 10 days. This delay in transmembrane uptake may represent an important defensive strategy against Cd poisoning in T. caerulescens, allowing time for activation of intracellular mechanisms for heavy metal detoxification.

Cadmium↗
PubMed1992

Effect of calmodulin antagonists on the growth and graviresponsiveness of primary roots of maize.

We examined the effect of calmodulin (CaM) antagonists applied at the root tip on root growth, gravity-induced root curvature, and the movement of calcium across the root tip and auxin (IAA) across the elongation zone of gravistimulated roots. All of the CaM antagonists used in these studies delayed gravity-induced curvature at a concentration (1 micromole) that did not affect root growth. Calmodulin antagonists (> or = 1 micromole) inhibited downward transport of label from 45Ca2+ across the caps of gravistimulated roots relative to the downward transport of 45Ca2+ in gravistimulated roots which were not treated with CaM antagonists. Application of CaM antagonists at the root tip (> or = 1 micromole) also decreased the relative downward movement of label from 3H-IAA applied to the upper side of the elongation zone of gravistimulated roots. In general, tip application of antagonists inhibited neither the upward transport of 45Ca2+ in the root tip nor the upward movement of label from 3H-IAA in the elongation zone of gravistimulated roots. Thus, roots treated with CaM antagonists > or = 1 micromole become less graviresponsive and exhibit reduced or even a reversal of downward polarity of calcium transport across the root tip and IAA transport across the elongation zone. The results indicate that calmodulin-regulated events play a role in root gravitropism.

Biological Transport↗
PubMed2004

Role of cytokinin in the regulation of root gravitropism.

The models explaining root gravitropism propose that the growth response of plants to gravity is regulated by asymmetric distribution of auxin (indole-3-acetic acid, IAA). Since cytokinin has a negative regulatory role in root growth, we suspected that it might function as an inhibitor of tropic root elongation during gravity response. Therefore, we examined the free-bioactive-cytokinin-dependent ARR5::GUS expression pattern in root tips of transformants of Arabidopsis thaliana (L.) Heynh., visualized high cytokinin concentrations in the root cap with specific monoclonal antibodies, and complemented the analyses by external application of cytokinin. Our findings show that mainly the statocytes of the cap produce cytokinin, which may contribute to the regulation of root gravitropism. The homogenous symmetric expression of the cytokinin-responsive promoter in vertical root caps rapidly changed within less than 30 min of gravistimulation into an asymmetrical activation pattern, visualized as a lateral, distinctly stained, concentrated spot on the new lower root side of the cap cells. This asymmetric cytokinin distribution obviously caused initiation of a downward curvature near the root apex during the early rapid phase of gravity response, by inhibiting elongation at the lower side and promoting growth at the upper side of the distal elongation zone closely behind the root cap. Exogenous cytokinin applied to vertical roots induced root bending towards the application site, confirming the suspected inhibitory effect of cytokinin in root gravitropism. Our results suggest that the early root graviresponse is controlled by cytokinin. We conclude that both cytokinin and auxin are key hormones that regulate root gravitropism.

Arabidopsis↗
PubMed2002

Controls of fine root dynamics across a gradient of gap sizes in a pine woodland.

Controls of fine dynamics were investigated in a Pinus palustris Mill. (longleaf pine) woodland subjected to two understory vegetation treatments (control versus removed) and four overstory treatments (no gap control, and canopy gaps of three sizes with constant total gap area per stand). Fine root (<2 mm diameter) dynamics were measured over 11 months using ingrowth cores (all treatments) and minirhizotrons (understory removed in no gap control and large gap treatments only). At the fine (microsite) spatial scale, pine and non-pine root mass production responded negatively to each other (P=0.033). Each life form was significantly (P< or =0.028) related to nearby overstory density, and pine root production compensated for reductions in non-pine roots if understory vegetation was removed. Soil moisture and NO(3) mineralization rate were negatively related to pine root mass production (ingrowth cores; P<0.001 and P=0.052) and positively related to pine root length production, mortality and turnover (minirhizotrons; P from <0.001 to 0.078). Temperature variance was negatively related to pine root lifespan P<0.001) and positively related to pine root turnover (P=0.003). At the ecosystem scale, pattern of overstory disturbance (gap size and number) had no significant effect on non-pine, pine, or total root production. However, the presence of gaps (versus the no-gap control) increased non-pine root mass production (ANOVA, P=0.055) in natural understory conditions, and reduced pine root mass production (P=0.035) where the understory was removed. Ecosystem-wide pine root length production, mortality and turnover were positively related to weekly soil temperature (P< or =0.02). In natural systems, fine root dynamics are highly variable and strongly affected by biotic factors. Roots quickly close belowground gaps because one life form (pine or non-pine) compensates for the absence of the other. When understory vegetation is removed, however, pine roots respond to the local abiotic environment, particularly moisture and NO(3).

Biomass↗
PubMed2005

Characterization of fructose-bisphosphate aldolase regulated by gibberellin in roots of rice seedling.

Fructose-bisphosphate aldolase is a glycolytic enzyme whose activity increases in rice roots treated with gibberellin (GA). To investigate the relationship between aldolase and root growth, GA-induced root aldolase was characterized. GA3 promoted an increase in aldolase accumulation when 0.1 microM GA3 was added exogenously to rice roots. Aldolase accumulated abundantly in roots, especially in the apical region. To examine the effect of aldolase function on root growth, transgenic rice plants expressing antisense aldolase were constructed. Root growth of aldolase-antisense transgenic rice was repressed compared with that of the vector control transgenic rice. Although aldolase activity increased by 25% in vector control rice roots treated with 0.1 microM GA3, FBPA activity increased very little by 0.1 microM GA3 treatment in the root of aldolase-antisense transgenic rice. Furthermore, aldolase co-immunoprecipitated with antibodies against vacuolar H+ -ATPase in rice roots. In the root of OsCDPK13-antisense transgenic rice, aldolase did not accumulate even after treatment with GA3. These results suggest that the activation of glycolytic pathway function accelerates root growth and that GA3-induced root aldolase may be modulated through OsCDPK13. Aldolase physically associates with vacuolar H-ATPase in roots and may regulate the vacuolar H-ATPase mediated control of cell elongation that determines root length.

Blotting, Western↗
PubMed1989

Effects of some centrally acting muscle relaxants on spinal root potentials: a comparative study.

The effects of intravenously administered mephenesin, tolperisone, baclofen, diazepam and midazolam on reflex activity were studied in unanesthetized spinal cats. Monosynaptic, as well as polysynaptic ventral root reflexes, the dorsal root potential and the dorsal root reflex were recorded simultaneously from L6-S1 segments. An analogue integrating method was developed for quantitative monitoring and recording ipsilateral spinal root potentials evoked by stimulation of the tibial nerve. Mephenesin (12.5-50 mg/kg) caused a significant and dose-dependent reduction in the polysynaptic and the dorsal root reflexes, slightly decreased the dorsal root potential but minimally affected the monosynaptic ventral root reflex. Tolperisone (2.5-10 mg/kg) dose-dependently inhibited both ventral root reflexes and the dorsal root reflex. It slightly prolonged the dorsal root potential without affecting the amplitude. Baclofen (0.5 mg/kg) abolished the monosynaptic reflex, partially inhibited the polysynaptic reflex, while dorsal root responses were less attenuated. Both benzodiazepines exerted similar actions, both qualitatively as well as quantitatively: the polysynaptic reflex was partially reduced while the monosynaptic reflex was not modified by diazepam or midazolam. Dorsal root responses were enhanced and the half-time of decay of the dorsal root potential was prolonged. Different patterns of action of muscle relaxants studied here are discussed in terms of their possible mechanisms of action. Profound depressant effects of mephenesin and tolperisone on the dorsal root reflex are in contrast to the small effect of both drugs on the dorsal root potential and might reflect their inhibition of spike-generating mechanisms. For a yet unknown reason, various spinal pathways are affected differentially by baclofen. In spinal cats, the reduction by benzodiazepines of the polysynaptic reflex may be related to the potentiation of some unidentified GABA-ergic inhibitory processes. The use of water-soluble midazolam, as a model compound instead of diazepam, is suggested because the usual organic solvents for diazepam may affect its action.

Animals↗
PubMed2001

Ginsenoside production in different phenotypes of Panax ginseng transformed roots.

Transformed roots were obtained after the inoculation of sterile root discs of Panax ginseng C.A. Meyer with Agrobacterium rhizogenes A4. The established hairy root lines displayed three morphological phenotypes when cultured on hormone-free liquid Schenk and Hildebrandt medium. Most of the cultures showed the characteristic traits of hairy roots (HR-M), while others were either callus-like (C-M) or thin (T-M) without branching. The growth rate of the transformed root lines was always higher than that of untransformed roots, showing that the genetic changes caused by the A. rhizogenes transformation conditioned a higher biomass formation. When considering the different transformed root phenotypes, we can observe that the highest ginsenoside production was achieved by HR-M root lines, closely followed by C-M ones, whereas the lowest yield was reached by T-M root phenotype. The study of the integration of the TL-DNA and TR-DNA fragments of the pRiA4 in the root genome showed that the aux1 gene was always detected in HR-M and C-M root phenotypes which presented the highest biomass and ginsenoside productions. This fact suggests a significant role of aux genes in the morphology of Panax ginseng transformed roots. The ginsenoside pattern of transformed roots varied according to their morphology, although the ginsenoside contents of the Rg group was always higher than that of the Rb group. From our results, we can infer the potential of some root phenotypes of Panax ginseng hairy root cultures for an improved ginsenoside production.

Ginsenosides↗
PubMed2002

Occlusal loading of EBA and MTA root-end fillings in a computer-controlled masticator: a scanning electron microscopic study.

AIM: The aim of this investigation was to assess the marginal adaptation of Super-EBA (EBA) and Pro Root MTA (MTA) root-end fillings and the occurrence of microcracks in resected root-ends of extracted teeth before and after occlusal loading for a five-year equivalent period in a computer-controlled masticator. METHODOLOGY: Twenty-four molar teeth were root-filled using lateral condensation and their root-ends resected. Root-end cavities were prepared and either EBA or MTA root-end fillings were placed. All surgical procedures were completed in vitro under an operating microscope. Replicas taken of the root-end fillings and resected root-ends were examined using an SEM before and after they were subjected to in vitro chewing cycles in a computer-controlled chewing simulator for the equivalent of 5 years. Marginal adaptation and integrity of the two root-end filling materials were evaluated and the presence of microcracks recorded. RESULTS: Before loading, a continuous margin was observed with 99.4 +/- 2.4% of EBA and 99.2 +/- 1.6% of MTA root-end fillings. After loading, the percentage of continuous margin decreased to 93.1 +/- 6.6% and 98.9 +/- 3.2% for EBA and MTA, respectively. After occlusal loading, 39.5% of the EBA root-end fillings were overfilled, whilst 52.6% of the MTA root-end fillings were underfilled. In total, 12.5% of the resected root-end surfaces showed microcracking before loading and 25% after occlusal loading. CONCLUSIONS: Both EBA and MTA displayed excellent marginal adaptation before masticatory loading. After loading, the amount of continuous margin for both root-end filling materials decreased slightly but was still high.

Aluminum Compounds↗
PubMed2002

Root and canal morphology of Thai mandibular molars.

AIM: To investigate the root and canal morphology of 351 mandibular permanent molars collected from an indigenous Thai population. METHODOLOGY: The cleaned teeth were accessed, the pulp dissolved by sodium hypochlorite under ultrasonication and the pulp system injected with Indian ink. The teeth were rendered clear by demineralization and immersion in methyl salicylate. The following observations were made: (i) number of roots and their morphology; (ii) number of root canals per tooth; (iii) number of root canals per root; (iv) root canal configuration in each root using Vertucci's classification, with additional modifications; and (v) presence and location of lateral canals and intercanal communications. RESULTS: Of 118 mandibular first molars, 13% had a third disto-lingual root. In three-rooted teeth, 80% of the main distal roots and 100% of the disto-lingual roots had type 1 canal systems. Of 60 mandibular second molars, 10% had C-shaped roots, the majority of which had type 1 (33%) or type IV (33%) canal systems. Of 173 third molars, 68% had two separate roots, 20% had fused roots and 11% had a single C-shaped root; the majority had two canals (61%). CONCLUSIONS: This study suggests that Thai molars exhibit features of both Caucasian and Chinese teeth.

Asian People↗