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PubMed2005

Defects in root development and gravity response in the aem1 mutant of rice are associated with reduced auxin efflux.

The phytohormone auxin is involved in the regulation of a variety of developmental processes. In this report, we describe how the processes of lateral root and root hair formations and root gravity response in rice are controlled by auxin. We use a rice mutant aem1 (auxin efflux mutant) because the mutant is defective in these characters. The aem1 line was originally isolated as a short lateral root mutant, but we found that the mutant has a defect in auxin efflux in roots. The acropetal and basipetal indole-3-acetic acid (IAA) transports were reduced in aem1 roots compared to wild type (WT). Furthermore, gravitropic bending as well as efflux of radioactive IAA was impaired in the mutant roots. We also propose a unique distribution of endogenous IAA in aem1 roots. An immunoassay revealed a 4-fold-endogenous IAA content in the aem1 roots compared to WT, and the application of IAA to the shoot of WT seedlings mimicked the short lateral root phenotype of aem1, suggesting that the high content of IAA in aem1 roots impaired the elongation of lateral roots. However, the high level of IAA in aem1 roots contradicts the auxin requirement for root hair formation in the epidermis of mutant roots. Since the reduced development in root hairs of aem1 roots was rescued by exogenous auxin, the auxin level in the epidermis is likely to be sub-optimum in aem1 roots. This discrepancy can be solved by the ideas that IAA level is higher in the stele and lower in the epidermis of aem1 roots compared to WT and that the unique distribution of IAA in aem1 roots is induced by the defect in auxin efflux. All these results suggest that AEM1 may encode a component of auxin efflux carrier in rice and that the defects in lateral roots, root hair formation and root gravity response in aem1 mutant are due to the altered auxin efflux in roots.

Biological Transport↗

PubMed1990

Defective secretion of mucilage is the cellular basis for agravitropism in primary roots of Zea mays cv. Ageotropic.

Root caps of primary, secondary, and seminal roots of Z. mays cv. Kys secrete large amounts of mucilage and are in close contact with the root all along the root apex. These roots are strongly graviresponsive. Secondary and seminal roots of Z. mays cv. Ageotropic are also strongly graviresponsive. Similarly, their caps secrete mucilage and closely appress the root all along the root apex. However, primary roots of Z. mays cv. Ageotropic are non-responsive to gravity. Their caps secrete negligible amounts of mucilage and contact the root only at the extreme apex of the root along the calyptrogen. These roots become graviresponsive when their tips are coated with mucilage or mucilage-like materials. Peripheral cells of root caps of roots of Z. mays cv. Kys contain many dictyosomes associated with vesicles that migrate to and fuse with the plasmalemma. Root-cap cells of secondary and seminal (i.e. graviresponsive) roots of Z. mays cv. Ageotropic are similar to those of primary roots of Z. mays cv. Kys. However, root-cap cells of primary (i.e. non-graviresponsive) roots of Z. mays cv. Ageotropic have distended dictyosomal cisternae filled with an electron-dense, granular material. Large vesicles full of this material populate the cells and apparently do not fuse with the plasmalemma. Taken together, these results suggest that non-graviresponsiveness of primary roots of Z. mays cv. Ageotropic results from the lack of apoplastic continuity between the root and the periphery of the root cap. This is a result of negligible secretion of mucilage by cells along the edge of the root cap which, in turn, appears to be due to the malfunctioning of dictyosomes in these cells.

Cell Membrane↗

PubMed1997

Gravitropic reaction in the growth of tea roots.

In Japan, tea (Camellia sinenis (L.) Kuntze) seedlings are propagated by cutting. A root system of clonal plants by cutting consists of adventitious roots and lateral roots. Most of the roots grow horizontally, which results in a shallow distribution of the root system. Such a shallow root system could be one of the factors contributing to the deterioration of nutrient uptake and resistance to water stress. Gravitropism of the roots is considered to be a decisive factor that controls the depth of a root system. The authors have investigated changes in the growth direction of roots to gravitative stimulus, using several kinds of roots (seminal roots, lateral roots and adventitious roots). Furthermore, amyloplasts in the root-cap cells, which are considered to be an equipment sensing gravistimulus, were observed. Seminal roots prominently showed orthogravitropism and contained many amyloplast particles in their root cap cells. Most lateral and adventitious roots showed plagiogravitropism, growing in an angle to gravistimulus, and lacked observable amyloplast particles in their root cap cells. The results suggest that the shallowing of root systems of elonal tea plants could be attributed to a gravitropic reaction of the adventitious and lateral roots composing the root system. There could also be a close relationship between the growth direction of roots and the presence of amyloplasts in root-cap cells.

Gravitropism↗

PubMed2002

Sugar exudation by roots of kallar grass [Leptochloa fusca (L.) Kunth] is strongly affected by the nitrogen source.

Exudation of sugars (glucose, fructose and sucrose) and that of cations and anions from intact roots of kallar grass [Leptochloa fusca (L.) Kunth] grown hydroponically with ammonium or nitrate (3 mM) as N source was investigated. In different experiments, plants grown on ammonium had slightly higher sugar contents than nitrate-grown plants, but their total sugar exudation during a 2-h period was up to 79-fold higher than under nitrate nutrition. Relative root exudation of inorganic anions and cations and that of amino acids (as a percentage of the internal contents exuded per time) was either similar or slightly higher from ammonium-grown than from nitrate-grown plants. Analysis of root architectural parameters revealed that ammonium-grown plants had a higher number of root tips/side roots per gram root fresh weight than nitrate-grown plants, whereas other root parameters, viz. length, diameter, volume and surface area were similar under the two N sources. A majority of the fine roots having diameter up to 0.4 mm represented up to 86% of the total root length, 64% of the total root surface area, and 35% of the total root volume; the root length and surface area per root system of that major root population were similar in ammonium- and nitrate-grown plants. Apparently, root architecture was not responsible for the different exudation rates. Within 12-24 h after shifting ammonium-grown plants to nitrate nutrition, root sugar levels and visible root architecture remained unchanged, yet the sugar exudation rate was reduced 30-fold. Short-term uptake of [14C]glucose (10 microM) from the rooting medium was similar for ammonium- and nitrate-grown plants. Thus, the very different sugar exudation rates were neither related to internal root sugar concentration, nor to the different root architecture, nor to differential resorption of sugars by ammonium- versus nitrate-grown plants. Increased external Ca2+ did not alter sugar exudation, and decreased external pH (4.5) only slightly increased sugar exudation from roots of nitrate-grown plants kept at pH 6.5. It is suggested that the much higher sugar exudation in response to ammonium may facilitate the ecologically and economically important association of diazotrophs with kallar grass roots.

Amino Acids↗

PubMed1999

Genetic ablation of root cap cells in Arabidopsis.

The root cap is increasingly appreciated as a complex and dynamic plant organ. Root caps sense and transmit environmental signals, synthesize and secrete small molecules and macromolecules, and in some species shed metabolically active cells. However, it is not known whether root caps are essential for normal shoot and root development. We report the identification of a root cap-specific promoter and describe its use to genetically ablate root caps by directing root cap-specific expression of a diphtheria toxin A-chain gene. Transgenic toxin-expressing plants are viable and have normal aerial parts but agravitropic roots, implying loss of root cap function. Several cell layers are missing from the transgenic root caps, and the remaining cells are abnormal. Although the radial organization of the roots is normal in toxin-expressing plants, the root tips have fewer cytoplasmically dense cells than do wild-type root tips, suggesting that root meristematic activity is lower in transgenic than in wild-type plants. The roots of transgenic plants have more lateral roots and these are, in turn, more highly branched than those of wild-type plants. Thus, root cap ablation alters root architecture both by inhibiting root meristematic activity and by stimulating lateral root initiation. These observations imply that the root caps contain essential components of the signaling system that determines root architecture.

Arabidopsis↗

PubMed2001

Distinct effects of auxin and light on adventitious root development in Eucalyptus saligna and Eucalyptus globulus.

Adventitious rooting is essential for vegetative propagation of woody species. We studied the effects of auxin and light on the development of adventitious roots in cuttings obtained from seedlings of Eucalyptus saligna Smith and E. globulus Labill in an attempt to characterize the adventitious rooting process and identify factors controlling rhizogenesis. Root development was scored as rooting percentage, root density (roots per rooted cutting), mean rooting time and root length. In both species, rooting time was reduced in the presence of auxin. Cuttings from 2-month-old E. saligna seedlings were responsive to lower auxin concentrations than comparable cuttings from E. globulus seedlings. Cuttings from 3-month-old E. saligna seedlings rooted promptly and rooting was not significantly affected by light conditions. In contrast, rooting of cuttings from 3-month-old E. globulus seedlings exhibited recalcitrant behavior and no roots were formed if illuminated during the root formation phase. Effective root regeneration of E. globulus cuttings was obtained by a 4-day exposure to 10 mg l(-1) IBA and culture in darkness during the root formation step. Loss of rooting capacity with seedling age was more pronounced in E. globulus than in E. saligna. The possibility of switching adventitious rooting off and on by manipulating light regime and exogenous auxin supply in E. globulus, and the constitutive nature of rooting in E. saligna may provide useful models for examining the rooting process at the biochemical and molecular levels in Eucalyptus.

Eucalyptus↗

PubMed1990

A quantitative analysis of the migration, attachment, and orientation of human gingival fibroblasts to human dental root surfaces in vitro.

The purpose of this study was to assess the migration, attachment, and orientation of human gingival fibroblasts to human dental roots over a period of 21 days in vitro. The fibroblasts were incubated with a total of 120 periodontally diseased and non-diseased root slices (200 microns thickness) which had been treated in the following manner: 1) Root planed diseased root (DT); 2) Root planed and citric acid demineralized diseased root (DTD); 3) Non-treated diseased root (DNT); 4) Citric acid demineralized diseased root (DNTD); 5) Non-diseased control (ND); 6) Citric acid demineralized non-diseased root (CA); 7) Citric acid and collagenase digested non-diseased root (CAC); 8) EDTA demineralized non-diseased root (E); and 9) EDTA-demineralized and collagenase-digested non-diseased root (EC). The results showed that that most active phase of cell attachment and orientation occurred during the first 10 days of the experiment. Statistical differences were observed between the variables, and, in terms of cell attachment and orientation to the root slices, it was concluded that: 1) Root planing improves diseased roots; 2) Acid demineralization subsequent to root planing improved diseased roots to such an extent as to render them comparable to non-diseased roots; 3) Citric acid demineralization alone improved diseased roots to the same extent as root planed diseased roots; 4) The exposure of collagen fibrils resulting from acid demineralization of the tools is not the sole reason for the improvement of the root surface, but rather a combination of the exposed collagen fibrils with the creation of a more hospitable environment was found to be responsible.

Cell Adhesion↗

PubMed1990

[Morphological studies on the roots of maxillary premolars in Japanese].

Visual observations were made of 3,202 maxillary first premolars and 3,365 maxillary second premolars from subjects of known sex, age, and side attributes. The material belongs to the Okamoto Research Laboratory of Dentistry. Items observed for each donor included number of dental roots, shapes of root apexes, root grooves, root orientation and curvature, and conditions of the maxillary first and second premolars. Results 1) In 65.7% of all materials (55.4% in males and 76.1% in females), maxillary first premolars had primary single roots. Complete branched roots accounted for 25.5% of the male and 17.6% of the female materials. In both cases, there was significant distinction between the sexes. Triple root teeth were extremely rare in both male- and female-donor teeth, as were double rooted maxillary second premolars. 2) Protruding, circular, and flat root apex types occurred in both maxillary first and second premolars. Circular and flat types were common among males. Branched and double-root maxillary first and second premolars were of either the complete or the incomplete type, both of which were more common in males. 3) About half of the mesial surface grooves in single-root maxillary first premolars were deeper than distal surface grooves in the same teeth: In 1/4-branch double teeth, 28.8% of the mesial surface grooves were deeper than the distal-surface grooves. The corresponding percentage for 1/3-branch double teeth was 38.8%. In 7.6% of 1/4-branch and 17.4% of 1/3-branch double teeth, distal-surface grooves were deeper than mesial-surface grooves. In 36.4% of 1/4-branch double teeth and 28.9% of 1/3-branch double teeth, the lower portion of the root was web shaped. In maxillary first premolars, lingual roots of 1/3-branch double-root teeth were cylindrical, as were 28.9% of buccal roots. Root grooves occurred on the lingual sides of 61.7% of all specimens. For 1/2-branch double root teeth, 18.4% were cylindrical: and 62.7% had grooves on the lingual side. Results are essentially the same in both cases. 4) Straight dental roots occurred in 37.4% of maxillary first and 35.4% of maxillary second premolars. Roots inclined distally in 36.7% of maxillary first premolars and in 18.8% of maxillary second premolars. A variety of inclinations and curvatures was observed. Booth roots were straight in 47.5% of 2-branch maxillary first premolars, whereas 35.1% had 1 straight and 1 inclined root and 84.4% had 2 distally inclined roots.(ABSTRACT TRUNCATED AT 400 WORDS)

Bicuspid↗

PubMed2001

Dorsal root ganglia morphologic features in patients with herniation of the nucleus pulposus: assessment using magnetic resonance myelography and clinical correlation.

STUDY DESIGN: Morphologic features of the dorsal root ganglia were investigated in patients with herniation of the nucleus pulposus by means of magnetic resonance myelography. OBJECTIVES: This study was undertaken to assess morphologic changes of the dorsal root ganglia in patients with herniation of the nucleus pulposus and to determine the relations between the morphologic features of the dorsal root ganglia and clinical features. SUMMARY OF BACKGROUND DATA: It has recently been reported that application of the nucleus pulposus to a nerve root induces edema in the rat dorsal root ganglion. Edema in the human dorsal root ganglion resulting from lumbar disc herniation has not been discussed in the literature, to the authors' knowledge. METHODS: Eighty-three consecutive patients (average age 42.1 years; range 17 to 77 years) with monoradicular symptoms were examined. Dorsal root ganglion morphologic features, i.e., indentations and swelling, were evaluated by magnetic resonance myelography. The dorsal root ganglion swelling at each level was quantitatively expressed as a ratio of the dorsal root ganglion width on the involved side to that of the contralateral side and was termed dorsal root ganglion ratio. Eighty-three uninvolved levels were chosen as controls in a randomized manner. Factors possibly contributing to the morphologic changes in the dorsal root ganglion were investigated. Neurologic symptoms, evaluated by the Japan Orthopaedic Association scoring system, were correlated to the morphologic changes. The morphologic features were followed up for 1 year after treatment in a small group of patients. RESULTS: Dorsal root ganglion indentations were always found in the narrowed intervertebral foramens. The incidence of indentations was significantly higher at the involved nerve roots (10.8%) than at the uninvolved nerve roots (4.0%) (P = 0.026). Patients with dorsal root ganglion indentations were significantly older (P = 0.0008). Leg pain scores in patients with indentations were significantly poor (P = 0.007). The dorsal root ganglion ratios were significantly higher at the involved levels than at the uninvolved levels (P = 0.001); the means +/- SD were 1.19 +/- 0.25 and 1.08 +/- 0.13, respectively. Patients with lateral herniated nucleus pulposus had significantly higher dorsal root ganglion ratios than those with central herniated nucleus pulposus (P = 0.0001); the mean ratios +/- SD were 1.48 +/- 0.32 and 1.10 +/- 0.12, respectively. A moderate positive correlation was found between dorsal root ganglion ratio and age (Pearson's correlation coefficient = 0.313). There was moderate negative correlation between the dorsal root ganglion ratio and leg pain, gait, motor, and total Japan Orthopaedic Association score (correlation coefficients were = -0.385, -0.350, -0.422, and -0.358, respectively). The dorsal root ganglion ratios were significantly diminished at 1-year follow-up (P = 0.001); the means +/- SD were 1.22 +/- 0.22 and 1.09 +/- 0.07, respectively. Indentations observed before treatment disappeared after treatment. CONCLUSIONS: Swelling and impingement in the involved dorsal root ganglion were clearly visualized by magnetic resonance myelography. The swelling and indentations were well correlated with severity of leg pain. These findings have important value in understanding the pathophysiology of the nerve roots in herniated nucleus pulposus.

Adolescent↗

PubMed2005

Growth dynamics of mechanically impeded lupin roots: does altered morphology induce hypoxia?

BACKGROUND AND AIMS: Root axes elongate slowly and swell radially under mechanical impedance. However, temporal and spatial changes to impeded root apices have only been described qualitatively. This paper aims (a) to quantify morphological changes to root apices and (b) assess whether these changes pre-dispose young root tissues to hypoxia. METHODS: Lupin (Lupinus angustifolius) seedlings were grown into coarse sand that was pressurized through a diaphragm to generate mechanical impedance on growing root axes. In situ observations yielded growth rates and root response to hypoxia. Roots were then removed to assess morphology, cell lengths and local growth velocities. Oxygen uptake into excised segments was measured. KEY RESULTS: An applied pressure of 15 kPa slowed root extension by 75% after 10-20 h while the same axes thickened by about 50%. The most terminal 2-3 mm of axes did not respond morphologically to impedance, in spite of the slower flux of cells out of this region. The basal boundary of root extension encroached to within 4 mm of the apex (cf. 10 mm in unimpeded roots), while radial swelling extended 10 mm behind the apex in impeded roots. Oxygen demand by segments of these short, thick, impeded roots was significantly different from segments of unimpeded roots when the zones of elongation in each treatment were compared. Specifically, impeded roots consumed O2 faster and O2 consumption was more likely to be O2-limited over a substantial proportion of the elongation zone, making these roots more susceptible to O2 deficit. Impeded roots used more O2 per unit growth (measured as either unit of elongation or unit of volumetric expansion) than unimpeded roots. Extension of impeded roots in situ was O2-limited at sub-atmospheric O2 levels (21% O2), while unimpeded roots were only limited below 11% O2. CONCLUSIONS: The shift in the zone of extension towards the apex in impeded roots coincided with greater vulnerability to hypoxia even after soil was removed. Roots still encased in impeded soil are likely to suffer from marked O2 deficits.

Cell Hypoxia↗

PubMed2000

Water uptake by roots: effects of water deficit.

The variable hydraulic conductivity of roots (Lp(r)) is explained in terms of a composite transport model. It is shown how the complex, composite anatomical structure of roots results in a composite transport of both water and solutes. In the model, the parallel apoplastic and cell-to-cell (symplastic and transcellular) pathways play an important role as well as the different tissues and structures arranged in series within the root cylinder (epidermis, exodermis, cortex, endodermis, stelar parenchyma). The roles of Casparian bands and suberin lamellae in the root's endo- and exodermis are discussed. Depending on the developmental state of these apoplastic barriers, the overall hydraulic resistance of roots is either more evenly distributed across the root cylinder (young unstressed roots) or is concentrated in certain layers (exo- and endodermis in older stressed roots). The reason for the variability of root Lp(r), is that hydraulic forces cause a dominating apoplastic flow of water around protoplasts, even in the endodermis and exodermis. In the absence of transpiration, water flow is osmotic in nature which causes a high resistance as water passes across many membranes on its passage across the root cylinder. The model allows for a high capability of roots to take up water in the presence of high rates of transpiration (high demands for water from the shoot). By contrast, the hydraulic conductance is low, when transpiration is switched off. Overall, this results in a non-linear relationship between water flow and forces (gradients of hydrostatic and osmotic pressure) which is otherwise hard to explain. The model allows for special root characteristics such as a high hydraulic conductivity (water permeability) in the presence of a low permeability of nutrient ions once taken up into the stele by active processes. Low root reflection coefficients are in line with the idea of some apoplastic bypasses for water within the root cylinder. According to the composite transport model, the switch from the hydraulic to the osmotic mode is purely physical. In the presence of heavily suberized roots, the apoplastic component of water flow may be too small. Under these conditions, a regulation of radial water flow by water channels dominates. Since water channels are under metabolic control, this component represents an 'active' element of regulation. Composite transport allows for an optimization of the water balance of the shoot in addition to the well-known phenomena involved in the regulation of water flow (gas exchange) across stomata. The model is employed to explain the responses of plants to water deficit and other stresses. During water deficit, the cohesion-tension mechanism of the ascent of sap in the xylem plays an important role. Results are summarized which prove the validity of the coehesion/tension theory. Effects of the stress hormone abscisic acid (ABA) are presented. They show that there is an apoplastic component of the flow of ABA in the root which contributes to the ABA signal in the xylem. On the other hand, (+)-cis-trans-ABA specifically affects both the cell level (water channel activity) and water flow driven by gradients in osmotic pressure at the root level which is in agreement with the composite transport model. Hydraulic water flow in the presence of gradients in hydrostatic pressure remains unchanged. The results agree with the composite transport model and resemble earlier findings of high salinity obtained for the cell (Lp) and root (Lp(r)) level. They are in line with known effects of nutrient deprivation on root Lp(r )and the diurnal rhythm of root Lp(r )recently found in roots of LOTUS.

Abscisic Acid↗

PubMed1996

Positions of dorsal root ganglia in the cervical spine. An anatomic and clinical study.

STUDY DESIGN: The authors investigated the positions of dorsal root ganglia and the relation of the location to symptoms and to the effects of nerve root infiltration in the cervical spine anatomically and clinically. OBJECTIVES: To clarify normal variation of positions of dorsal root ganglia and the relation of the location of dorsal root ganglia to symptoms and to the effects of nerve root infiltration. SUMMARY OF BACKGROUND DATA: The dorsal root ganglia of the spinal nerve has attracted much attention as an important structure in the mechanisms of radicular symptoms in the lumbar spine. Although the position of the dorsal root ganglia in the lumbar spine has been classified recently, there are few reports regarding the dorsal root ganglia in the cervical spine. METHODS: The positions of dorsal root ganglia were divided into two types: proximally situated and distally situated. The positions of dorsal root ganglia in the anatomic and clinical cases were compared. The relation of the positions of dorsal root ganglia to symptoms and to the clinical effects of nerve root infiltration were analyzed. RESULTS: There was no statistically significant difference in positions of dorsal root ganglia in C6 nerve roots between anatomic and clinical cases. In addition, there was no relation between symptoms and the positions of dorsal root ganglia in clinical cases. However, there was a significant difference in positions of dorsal root ganglia in C7 nerve roots between anatomic and clinical cases. Nerve root infiltration was significantly more effective in the distally situated type of dorsal root ganglia. CONCLUSIONS: This study defined the normal variation of the positions of dorsal root ganglia. The results strongly suggest that some attention should be paid to the position of dorsal root ganglia in the diagnosis and treatment of cervical radiculopathy.

Adult↗

PubMed1988

Analysis of the dental morphology of Plio-Pleistocene hominids. IV. Mandibular postcanine root morphology.

The subocclusal morphology of 168 permanent mandibular premolars (N = 77) and molars (N = 91) of Plio-Pleistocene hominids has been investigated. The taxonomic allocation of the teeth, which represent at least 46 individuals, was based on nondental evidence. Specimens were allocated to one of two major taxonomic categories, (EAFROB or EAFHOM), East African Homo erectus (EAFHER), or their taxonomic affinity was regarded as 'unknown' (N = 17). Information about the root system was derived from radiography and direct observation. Morphometric data were in the form of nine linear and two angular measurements based on eighteen reference points. Root form was also assessed using a scheme which recognised four classes of root morphology. Data were compared using both univariate and multivariate techniques, including Principal Component and Canonical Variate analysis. Posterior probabilities derived from the latter were used (in a two-taxon design model) to assess the affinities of the 'unknown' specimens. The variation in hominid mandibular premolar root form was interpreted as two morphoclines, based on the presumed primitive condition of the P3 (with mesiobuccal and distal roots, 2R: MB and D) and P4 (with mesial and distal root, 2R: M and D) root systems. One trend apparently leads towards root reduction (i.e. P3 = 1 R; P4 = 1 R), and the other to root elaboration (i.e. P3 and P4 = 2R: M and D). The extreme form of the latter is the 'molarisation' of the premolar roots seen in EAFROB. Despite major differences in root form there was relatively little taxonomic variation in root metrics, except for a more robust distal root system in EAFROB. Molar root form showed little interspecific variation except for M2 in which the roots in EAFROB were larger and more robust, with differences in root height being greater for the distal than for the mesial roots. Root form and metrics enable four of the 'unknown' specimens (KMN-ER 819, 1482, 1483 and 1801) to be tentatively allocated to EAFHOM, and a single specimen, KMN-ER 3731, to EAFROB. Published assessments of the root morphology of the 'robust' australopithecines from Swartkrans suggest that the premolar root form of Australopithecus (Paranthropus) robustus is not obviously intermediate between the presumed ancestral condition, and the 'molarised' mandibular premolar root systems of Australopithecus (Paranthropus) boisei.

Africa, Eastern↗

PubMed1998

Acute effects of nucleus pulposus on blood flow and endoneurial fluid pressure in rat dorsal root ganglia.

STUDY DESIGN: An experimental study to elucidate the initial factors in the pathogenesis of lumbar pain caused by disc herniation. OBJECTIVE: To evaluate the effects of autologous nucleus pulposus on blood flow and endoneurial fluid pressure in dorsal root ganglia. SUMMARY OF BACKGROUND DATA: Human sciatica is known to be associated with compression of lumbar nerve roots and dorsal root ganglia by herniated intervertebral discs. Recently, it has been shown that application of nucleus pulposus to nerve roots induces injury and pain-related behavior in experimental animals. In this study, the authors hypothesized that nucleus pulposus applied to a nerve root would cause increased intraneural edema and reduced blood flow in the corresponding dorsal root ganglia. Studies in peripheral nerves have shown that these initial pathophysiologic disturbances initiate complex events that exacerbate nerve injury and cause pain. METHODS: A total of 29 adult female Sprague-Dawley rats weighing 200 to 250 g had their left L5 nerve roots and associated dorsal root ganglia exposed. Autologous nucleus pulposus was harvested from the tail and applied to the L5 nerve root just proximally to the dorsal root ganglia (nucleus pulposus group). For control, the same volume of muscle was harvested from the surgical area in the back and applied similarly to the neural tissue (control group). Blood flow was continuously monitored using a laser Doppler flow probe for 3 hours (n = 10) or 4 hours (n = 8) in animals with indwelling cannulas for measurement of systemic arterial pressure. Endoneurial fluid pressures were recorded with a servonull micropipette system using glass micropipettes with tip diameters of 4 microns. Endoneurial fluid pressure in the dorsal root ganglia was measured before and 3 hours after application of nucleus pulposus (n = 7) or muscle (n = 4). After measurement of blood flow and endoneurial fluid pressure, the nerve root and dorsal root ganglia were processed for histology and evaluated by light microscope. RESULTS: Blood flow in the nucleus pulposus group was reduced by 10% to 20% from the initial value after 3 to 4 hours. This reduction was statistically significant compared with that of the control group (P < 0.01). Endoneurial fluid pressure was initially 2.6 +/- 1.2 cm H2O in the nucleus pulposus group, and 2.1 +/- 0.6 cm H2O in the control group. Three hours after application, endoneurial fluid pressure was 7.5 +/- 4.6 in the nucleus pulposus group (P > 0.05), and 2.0 +/- 0.8 in the control group (P > 0.05). Edema was the principal pathologic finding seen consistently in the nerve roots and in many of the associated dorsal root ganglia from animals treated with nucleus pulposus. CONCLUSION: Application of nucleus pulposus to nerve root increased endoneurial fluid pressure and decreased blood flow in the dorsal root ganglia. This study's acute observations in the dorsal root ganglia may thus help to explain why disc herniations without compression of neural tissue are sometimes painful because similar pathologic findings are observed after only nucleus pulposus application to the nerve root. The authors further suggest that exposure of nerve roots to nucleus pulposus may establish a "compartment syndrome" in the dorsal root ganglia.

Animals↗

PubMed2005

Peroxidases, lignin and anatomy during in vitro and ex vitro rooting of gardenia (Gardenia jasminoides Ellis) microshoots.

In vitro and ex vitro rooting of gardenia (Gardenia jasminoides Ellis) microshoots with or without indolic-3-butyric acid (IBA) was studied in order to improve acclimatization of microplants after root formation and transplantation. Peroxidase (POD) activity and isoforms, lignin content and anatomical observations were evaluated in the course of the three interdependent phases (induction, initiation and expression) of microshoot rooting. Microshoots treated or not treated with IBA achieved high rooting percentages both in vitro and ex vitro. At the end of the 2-week acclimatization period, the percentage of surviving microplants ranged from 80% to 100%, for in vitro and ex vitro rooted microshoots, respectively. Microshoots rooted in vitro and ex vitro showed a relationship between rooting and POD activity but in a different time course. It appeared that root formation occurred after the microshoots had reached and passed a peak of maximum enzyme activity. In all treatments, electrophoretic analysis (native PAGE) of PODs revealed the appearance of one anionic and three cationic POD isoforms (C(1), C(3) and C(4)). An additional cationic POD isoform (C(2)) appeared only in the ex vitro rooting. The lignin content was similar in microshoots rooted both in vitro and ex vitro. The sequential anatomical changes during the rooting process were similar in both in vitro and ex vitro rooting treatments. In the case of in vitro rooting, pith cells had vacuoles entirely filled with a dark substance, while in the case of ex vitro rooting, pith cells contained many amyloplasts. The origin of the adventitious roots, in both rooting conditions, was located in the cambial ring. Roots with organized tissue systems emerged from the microshoot stem 10-14 days after the root induction treatments; on day 10 for rooting in vitro, while a 4-day delay was noted in microshoots rooted ex vitro.

Acclimatization↗

PubMed1986

Quantitative comparisons of potentially cariogenic microorganisms cultured from noncarious and carious root and coronal tooth surfaces.

Potentially cariogenic microorganisms cultured from noncarious and carious root and coronal (enamel) surfaces were quantitatively compared in patients 22 to 84 years of age (mean, 52 years). We collected 150 plaque specimens from 26 in situ teeth with initial root lesions and from 25 extracted teeth with advanced root lesions. The frequencies of isolation of Streptococcus mutans, Actinomyces viscosus, and Lactobacillus spp. were, respectively, 94, 72, and 51% at the noncarious root site; 98, 71, and 54% at the root lesion; 84, 61, and 44% at the noncarious enamel site; and 100, 66, and 90% at the enamel lesion. The streptococci made up the largest mean proportion of the total anaerobic cultivable microflora, ranging from 31.2% at the noncarious enamel site to 37.6% at the root lesion, while S. mutans varied between 18% at the noncarious enamel and root surfaces and approximately 24% at both the enamel and root lesions. The proportion of actinomyces ranged from 12.3% at the root lesion to 23.6% at the noncarious root site, while A. viscosus varied from 7.8% at the root lesion to 15.1% at the noncarious root site. The largest mean proportion of lactobacilli (4.2%) was recovered at the enamel lesion site. Proportions of Candida spp. made up less than 0.1% at all sites. Proportions of microorganisms did not differ significantly between noncarious enamel and root sites, but the noncarious coronal and root sites had higher (P less than 0.05) proportions of actinomyces than did the root lesion. Also, enamel lesions had a greater (P less than 0.05) percentage of Lactobacillus spp. than did root lesions. The number of streptococci recovered from the root lesion was greater (P less than 0.01) than the number of actinomyces at the same site. S. mutans was recovered from initial root lesions in greater numbers (P less than 0.001) than were actinomyces and lactobacilli. The number of S. mutans recovered at the initial root lesions was greater (P less than 0.01) than that recovered from the advanced root lesions.

Actinomyces↗

PubMed1990

[Myelography for nerve root avulsion in birth palsy].

Myelography and CT myelography (CTM) were reviewed in 18 cases of birth palsy with clinically suspected avulsion injury. Root-somatosensory evoked potential (root-SEP) was also reviewed for myelographic evaluation of the nerve root avulsion in birth palsy. Root-SEP is not induced in case of avulsed nerve roots, but is induced in case of both normal and incompletely avulsed roots. Myelography demonstrated 58 abnormal nerve roots in 18 cases (19 limbs); 45 (78%) complete and 13 (22%) incomplete nerve root avulsions. Each of complete and incomplete avulsions was defined as total absence and partial presence of rootlets on myelography, respectively. Traumatic meningoceles were detected at 46 roots (79%) on myelography and/or CTM; 35 roots on myelography and 45 roots on CTM. CTM could not detect only a very small meningocele at one root. At 11 roots CTM was superior to myelography in delineating a meningocele because CTM is sensitive to a poorly enhanced meningocele. CTM, however, could not diagnose nerve root avulsions so accurately as myelography, since myelography detected 12 (7 completely and 5 incompletely) avulsed roots without meningocele, whereas CTM could not delineate the nerve roots clearly. Thus, myelography is indispensable to evaluate nerve root avulsions without meningocele. Root-SEP was examined in 9 patients who underwent brachial plexus exploration. SEP was negative at 22/25 roots with complete avulsion and was positive at 7/7 roots with myelographically incomplete avulsion, regardless of presence or absence of any traumatic meningocele.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗

PubMed1997

The influence of free hand suturing technique and zero pressure fixation on the hydrodynamic function of aortic root and aortic valve leaflets.

OBJECTIVE: There is increasing interest in the use of stentless porcine bioprostheses implanted by the free hand suturing technique. However, preservation of the normal valve geometry and function is a matter of concern. This study has been conducted to investigate the influence of free hand insertion on the hydrodynamic function of the aortic valve. In particular, free sewn valves have been compared to whole root replacements for both fresh valves and zero pressure fixed bioprostheses. METHODS: Four sets of porcine aortic roots with six aortic roots in each set consisting of (A) fresh aortic roots, (B) fresh aortic valve inserted by free hand suturing technique in fresh aortic valve fixed in glutaraldehyde under zero pressure, inserted by free hand suturing technique in fresh aortic roots, and (D) aortic roots fixed in glutaraldehyde under zero pressure, were studied. Hydrodynamic function and leaflet bending deformations were analysed in a modified pulsatile flow simulator which incorporates the elastic aortic roots. RESULTS: The glutaraldehyde-treated roots were found to be less distensible than the fresh aortic roots, with a mean dilatation of only 8% compared with 43% for the fresh roots at 120 mmHg pressure. The other two groups of free sewn valves showed reasonably good dilatation of 38%. There was no significant difference between the two sets. The hydraulic effective orifice area (EOA) of the valve, which was derived from the flow and pressure measurements, was divided by the actual orifice area for the annulus to arrive at the performance index. The performance index for glutaraldehyde-fixed aortic root was the lowest, with an index of 0.47 compared with 0.91 for that of fresh roots, 0.61 for the fresh valve in fresh root and 0.50 for the glutaraldehyde-treated valve in fresh root. The mean pressure difference during the peak flow also associated the same order with 12 mmHg for the glutaraldehyde-fixed roots, 1.8 mmHg for the fresh roots, 5.3 mmHg for the fresh valve in fresh root and 7.7 mmHg for the glutaraldehyde-treated valve in fresh root. The free hand suturing technique altered the leaflet geometry and caused increased open leaflet bending deformations compared to the fresh root. Both groups of free sewn valves behaved better than the zero pressure fixed root. CONCLUSIONS: Alteration in leaflet biomechanics is likely to influence long-term valve durability.

Animals↗