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At least 469 records · Page 26Linked to original sources
PubMed2006

At-level neuropathic pain is induced by lumbosacral ventral root avulsion injury and ameliorated by root reimplantation into the spinal cord.

Neuropathic pain is common after traumatic injuries to the cauda equina/conus medullaris and brachial plexus. Clinically, this pain is difficult to treat and its mechanisms are not well understood. Lesions to the ventral roots are common in these injuries, but are rarely considered as potential contributors to pain. We examined whether a unilateral L6-S1 ventral root avulsion (VRA) injury in adult female rats might elicit pain within the dermatome projecting to the adjacent, uninjured L5 spinal segment. Additionally, a subset of subjects had the avulsed L6-S1 ventral roots reimplanted (VRA+Imp) into the lateral funiculus post-avulsion to determine whether this neural repair strategy elicits or ameliorates pain. Behavioral tests for mechanical allodynia and hyperalgesia were performed weekly over 7 weeks post-injury at the hindpaw plantar surface. Allodynia developed early and persisted post-VRA, whereas VRA+Imp rats exhibited allodynia only at 1 week post-operatively. Hyperalgesia was not observed at any time in any experimental group. Quantitative immunohistochemistry showed increased levels of inflammatory markers in laminae III-V and in the dorsal funiculus of the L5 spinal cord of VRA, but not VRA+Imp rats, specific to areas that receive projections from mechanoreceptive, but not nociceptive, primary afferents. These data suggest that sustained at-level neuropathic pain can develop following a pure motor lesion, whereas the pain may be ameliorated by acute root reimplantation. We believe that our findings are of translational research interest, as root implantation surgery is emerging as a potentially useful strategy for the repair of cauda equina/conus medullaris injuries.

Animals↗
PubMed2002

Eight-year results of aortic root replacement with the freestyle stentless porcine aortic root bioprosthesis.

BACKGROUND: Stentless porcine aortic valves offer several advantages over traditional valves. Among these are superior hemodynamics, laminar flow patterns, lack of need for anticoagulation, and perhaps improved durability. METHODS: One hundred four patients were operated on from September 17, 1992, to October 31, 1997, as part of a multicenter worldwide investigation of the Medtronic Freestyle stentless porcine bioprosthesis. All patients received a total aortic root replacement. The patients were evaluated postoperatively at discharge, at 3 to 6 months, and yearly by clinical examination and color flow Doppler echocardiography. RESULTS: Operative mortality was 3.9%. No patient experienced structural valve deterioration, nonstructural deterioration, perivalvular leak, or unacceptable hemodynamic performance. At 8 years, survival was 59.8%. Freedom from thromboembolic complications was 83.3%. Freedom from postoperative endocarditis was 96.9%. Freedom from reoperation was 100%. Mean systolic gradients did not change over the time period studied. They were 6.4 +/- 3.8 mm Hg at 1 year and 6.7 +/- 2.6 mm Hg at 8 years. Correspondingly, effective orifice area was 1.9 +/- 0.7 cm2 at 1 year and 1.8 +/- 0.8 cm2 at 8 years. The incidence of any aortic insufficiency also did not change over the length of follow-up. At 1 year, 98% of patients had no or trivial aortic insufficiency and 2% had mild aortic insufficiency. At 8 years, 100% of patients evaluated were free of any aortic insufficiency. CONCLUSIONS: The Medtronic Freestyle aortic root bioprosthesis can be used safely to replace the aortic root or aortic valve for aortic valve and aortic root pathology. Total root replacement allows optimal hemodynamic performance with no significant aortic regurgitation. Results up to 8 years show excellent survival and no signs of degeneration. Further follow-up is still needed to determine valve durability.

Aged↗
PubMed1999

Aortic root replacement with the freestyle stentless porcine aortic root bioprosthesis.

BACKGROUND: Stentless porcine prosthetic valves offer several advantages over traditional valves. Among these are superior hemodynamics, laminar flow patterns, lack of need for anticoagulation and perhaps improved durability. METHODS: One hundred and twelve patients were operated on from September 17, 1992 to April 13, 1998 as part of a multi-center worldwide investigation. All patients received a total aortic root replacement. Patients were evaluated postoperatively at discharge, 3 to 6 months, and yearly by clinical exam and color flow Doppler echocardiography. RESULTS: There were 4 deaths either in the hospital or within 30 days after surgery for an operative mortality of 3.6%. No patients experienced structural valve deterioration, non-structural valve deterioration, paravalvular leak, unacceptable hemodynamic performance, or postoperative endocarditis. The linearized rates for survival and thromboembolic complications at 5 years were 82.8% and 90.5% respectively. Excellent hemodynamic function is demonstrated by very low gradients, large EOA, and an exceedingly low incidence of any aortic regurgitation. CONCLUSIONS: The Medtronic Freestyle aortic root bioprosthesis can be used safely to replace the aortic root for aortic valve and aortic root pathology. Root replacement allows optimal hemodynamic performance with no significant aortic regurgitation. Early and intermediate results are encouraging, but further follow-up is needed to determine valve durability.

Adult↗
PubMed1988

Hairy roots are more sensitive to auxin than normal roots.

Responses to auxin of Lotus corniculatus root tips or protoplasts transformed by Agrobacterium rhizogenes strains 15834 and 8196 were compared to those of their normal counterparts. Three different types of experiments were performed, involving long-term, medium-term, or short-term responses to a synthetic auxin, 1-naphthaleneacetic acid. Root tip elongation, proton excretion by root tips, and transmembrane electrical potential difference of root protoplasts were measured as a function of exogenous auxin concentration. The sensitivity of hairy root tips or protoplasts to exogenous auxin was found to be 100-1000 times higher than that of untransformed material.

Journal Article↗
PubMed1990

Late-season changes in allocation of starch and sugar to shoots, coarse roots, and fine roots in two hybrid poplar clones.

Two hybrid Populus clones, Tristis and Eugenei, which had been grown from cuttings in 114-liter pots sunk in the ground, were sequentially harvested during the latter part of the first growing season. Pots were supplied with water and nitrogen at two different rates. Starch and sugar concentrations were determined in samples taken from stems, branches, cuttings, and five diameter classes of roots. Concentrations of starch and sugar in all components of the trees were significantly affected by time of harvest and clone. Water and nitrogen treatments, however, did not significantly affect carbohydrate concentrations. From August to November, as plants developed cold hardiness, starch concentrations declined and sugar concentrations increased in stems and branches, especially in Tristis. In both clones, the large roots (> 1 mm diameter) were major repositories of starch and sugar late in the season. By the end of September, 80% of total-tree nonstructural carbohydrates in Eugenei were located in the roots. Even the fine-root fraction (< 0.5 mm diameter) showed substantial carbohydrate loading in late season, contradicting the hypothesis that starch deposition in fine roots occurs only when they are being formed.

Journal Article↗
PubMedDate not supplied

Mechanical stimulation of dorsal root ganglia induces increased production of substance P: a mechanism for pain following nerve root compromise?

The undecapeptide, substance P, is known to be synthesized in cell bodies of dorsal root ganglia. This neuropeptide is also known to modulate sensory, nociceptive transmission postsynaptically on dorsal horn interneurons. In the animal model used in the current study, experimental mechanical stimulation of dorsal root ganglia and nerve roots increased the amounts of substance P, as well as substance P immunoreactivity in cell bodies of the dorsal root ganglia and in the substantia gelatinosa of the spinal dorsal horn that the cell bodies innervated. These results were determined by using both immunohistochemistry and radioimmunoassay. This study suggests that substance P may modulate nociception when lumbar nerve roots are stimulated mechanically.

Animals↗
PubMed2002

Visualization of thermally fluctuating surface structure in noncontact atomic-force microscopy and tip effects on fluctuation: theoretical study of Si(111)-(square root[3] x square root[3])-Ag surface.

We investigated noncontact atomic-force microscopy (NC-AFM) images of a thermally fluctuating surface structure together with tip effects based on the first-principles electronic state calculation. As an example the Si(111)-(square root[3] x square root[3])-Ag (square root[3]-Ag) surface is studied. We have succeeded in theoretically visualizing the thermal fluctuation of the square root[3]-Ag surface at room temperature, and in reproducing the observed NC-AFM image for the first time. Further, the pinning effect of the thermal fluctuation of the square root[3]-Ag surface by the tip is clarified, which shows a novel ability of NC-AFM to modify the surface structure.

Journal Article↗
PubMed1994

Novel Methods of Measuring Hydraulic Conductivity of Tree Root Systems and Interpretation Using AMAIZED (A Maize-Root Dynamic Model for Water and Solute Transport).

Steady-state and dynamic methods were used to measure the conductivity to water flow in large woody root systems. The methods were destructive in that the root must be excised from the shoot but do not require removal of the root from the soil. The methods involve pushing water from the excised base of the root to the apex, causing flow in a direction opposite to that during normal transpiration. Sample data are given for two tropical (Cecropia obtusifolia and Lacistema aggregatum) and two temperate species (Acer saccharum and Juglans regia cv Lara). A hysteresis was observed in the relationship between applied pressure and resulting flow during dynamic measurements. A mathematical model (AMAIZED) was derived for the dynamics of solute and water flow in roots. The model was used to interpret results obtained from steady-state and dynamic measurements. AMAIZED is mathematically identical with the equations that describe Munch pressure flow of solute and water in the phloem of leaves. Results are discussed in terms of the predictions of AMAIZED, and suggestions for the improvement of methods are made.

Journal Article↗
PubMed1998

Adaptation of active proton pumping and plasmalemma ATPase activity of corn roots to low root medium pH

Corn (Zea mays L.) root adaptation to pH 3.5 in comparison with pH 6. 0 (control) was investigated in long-term nutrient solution experiments. When pH was gradually reduced, comparable root growth was observed irrespective of whether the pH was 3.5 or 6.0. After low-pH adaptation, H+ release of corn roots in vivo at pH 5.6 was about 3 times higher than that of control. Plasmalemma of corn roots was isolated for investigation in vitro. At optimum assay pH, in comparison with control, the following increases of the various parameters were caused by low-pH treatment: (a) hydrolytic ATPase activity, (b) maximum initial velocity and Michaelis constant (c) activation energy of H+-ATPase, (d) H+-pumping activity, (e) H+ permeability of plasmalemma, and (f) pH gradient across the membranes of plasmalemma vesicles. In addition, vanadate sensitivity remained unchanged. It is concluded that plasmalemma H+-ATPase contributes significantly to the adaptation of corn roots to low pH. A restricted net H+ release at low pH in vivo may be attributed to the steeper pH gradient and enhanced H+ permeability of plasmalemma but not to deactivation of H+-ATPase. Possible mechanisms responsible for adaptation of plasmalemma H+-ATPase to low solution pH during plant cultivation are discussed.

Journal Article↗
PubMed1976

A New Sensitive Root Auxanometer: Preliminary Studies of the Interaction of Auxin and Acid pH in the Regulation of Intact Root Elongation.

A new sensitive root auxanometer is described. The auxanometer represents an adaption of the position-sensor transducer method to measurement of intact root elongation and has the advantages of simplicity and high sensitivity. Experiments with the auxanometer show that auxin begins to inhibit intact pea root elongation within 10 minutes and continues to inhibit elongation for at least 1 hour following a 1-hour treatment with the hormone. Exposure of pea roots to pH 4 results in a 2- to 3-fold increase in elongation rate beginning about 1 minute after acid treatment. Acid-induced elongation continues at a steady rate for at least 160 minutes and can be reinitiated repeatedly by shifting between pH 4 and 6.5. Auxin inhibits acid-induced elongation whether given before or after acidification, and a transient exposure to auxin renders intact roots relatively insensitive to acid for at least 1 hour after withdrawal of the hormone.

Journal Article↗
PubMed1978

Quantitative Assessment of Ultrastructural Changes in Primary Roots of Corn (Zea mays L.) after Geotropic Stimulation: II. Curving and Noncurving Zones of the Root Proper.

In outer cortical cells of corn (Zea mays L.) roots we made ultrastructural comparisons between the geotropically responding (661 nm irradiated) and nonresponding (dark control) roots in both the curving and noncurving regions of the root. In the control treatment, Golgi apparatus (dictyosomes) and mitochondria exhibited centrifugal distribution (taking the stele as the center) in both regions of the roots (the organelles localized in the top of the cells in the upper tissues, and in the bottom of the cells in the lower tissues). In the geotropically responding roots, the distribution patterns were the same as those of the controls. However, in the zone of curvature the dictyosomes (but not the mitochondria) were randomly distributed in the cells of the upper tissues. This change in pattern of dictyosome distribution could be related to the change in cell elongation of upper cells.

Journal Article↗
PubMed1989

Characterization and Rooting Ability of Indole-3-Butyric Acid Conjugates Formed during Rooting of Mung Bean Cuttings.

Indole-3-butyric acid (IBA) is rapidly metabolized by mung bean cuttings during rooting. Twenty-four hours after application, less than 20% of the applied IBA remained in the free form and its level decreased continuously in the later stages of rooting. Indole-3-butyrylaspartic acid (IBAsp) and at least two high molecular weight conjugates were the major metabolites in IBA-treated cuttings. In the latter conjugates, at least part of the IBA moiety is attached to a high molecular weight constituent in an amide linkage. IBAsp level peaked 24 hours after application of IBA to the cuttings and then declined. The level of the high molecular weight conjugates increased continuously throughout the rooting process. The conjugates were active in inducing rooting of cuttings, with IBAsp being superior to free IBA. It is suggested that IBA conjugates, and particularly IBAsp, serve as the source of auxin during the later stages of rooting.

Journal Article↗
PubMed1992

Measurement of Net Fluxes of Ammonium and Nitrate at the Surface of Barley Roots Using Ion-Selective Microelectrodes : II. Patterns of Uptake Along the Root Axis and Evaluation of the Microelectrode Flux Estimation Technique.

Net fluxes of NH(4) (+) and NO(3) (-) into roots of 7-day-old barley (Hordeum vulgare L. cv Prato) seedlings varied both with position along the root axis and with time. These variations were not consistent between replicate plants; different roots showed unique temporal and spatial patterns of uptake. Axial scans of NH(4) (+) and NO(3) (-) net fluxes were conducted along the apical 7 centimeters of seminal roots of intact barley seedlings in solution culture using ion-selective microelectrodes in the unstirred layer immediately external to the root surface. Theoretically derived relationships between uptake and concentration gradients, combined with experimental observations of the conditions existing in our experimental system, permitted evaluation of the contribution of bulk water flow to ion movement in the unstirred layer, as well as a measure of the spatial resolution of the microelectrode flux estimation technique. Finally, a method was adopted to assess the accuracy of this technique.

Journal Article↗
PubMed2005

Continued root formation of a pulpless permanent incisor following root canal treatment: a case report.

AIM: To present a case of a pulpless permanent incisor that continued root formation following root canal treatment. SUMMARY: A healthy 8-year-old girl with a history of dental trauma resulting in a coronal fracture involving enamel, dentine and pulp was referred by her general dental practitioner for treatment and evaluation of tooth 21. The tooth had a necrotic pulp and periapical rarefaction was evident radiographically. The canal was prepared, dressed with Ca(OH)2 and then filled with a rolled gutta percha cone and Roth's root canal sealer. A radiograph exposed eight years post-treatment, showed evidence of continued apical formation. KEY LEARNING POINTS: *Teeth with necrotic pulps and periapical rarefaction may show evidence of continued apical formation after root canal treatment. *Hertwig's epithelial root sheath may be more resistant than expected to trauma and infection.

Child↗
PubMedDate not supplied

Does aortic root enlargement impair the outcome of patients with small aortic root?

BACKGROUND: Posterior root enlargement procedures provide the implantation of suitable-sized prosthetic valves in patients with a small aortic root to prevent a high postoperative transvalvular gradient. The aim of this study was to evaluate long-term results of the posterior root enlargement. METHODS: Between 1985 and 2002, 124 patients underwent aortic valve replacement with a posterior root enlargement. The main indication was a small aortic valve orifice area to patient body surface area (indexed valve area < 0.85 cm2/m2). Fifty-four (44%) patients were male, and 70 (56%) were female with a mean age 39.1 +/- 14.3 years. Indications for operation were severe calcified aortic valve stenosis (37.1%), severe aortic insufficiency (25.8%), or combination (37.1%). Seventy-five (60%) patients received double-valve replacement. A pericardial patch was used in 100 patients (80.6%) and a Dacron patch was used in 24 patients. RESULTS: Operative mortality was 6.4% (8 patients). The causes of hospital mortality were low cardiac output syndrome (LCOS) (in 6 patients), cerebrovascular events (in 1 patient) and multiple organ failure (in 1 patient). Multivariate analysis demonstrated concomitant coronary revascularization to be a significant (p = 0.03) predictor for early mortality. There were six (5.4%) late deaths. Cox proportional hazards regression analysis demonstrated LCOS (p = 0.013) and infective endocarditis (p = 0.003) to be significant predictors for late mortality. Atrioventricular block required a permanent pacemaker was observed in 4 patients (3.2%). CONCLUSIONS: Posterior aortic root enlargement techniques can be easily applied without additional risks. Long-term survival and freedoms from valve-related complications are satisfactory.

Adolescent↗
PubMed1968

Dorsal root potentials and ventral root reflexes evoked by nonmyelinated fibers.

Electrical stimulation of C-fibers in the cat superficial peroneal nerve, with the A-fibers either conducting or blocked by cold, evoked dorsal root potentials having the same polarity as those evoked by A-fibers. Ventral root reflexes evoked by A-fibers were facilitated by a pure C-volley in the same or another nerve, but dorsal root potentials evoked by A-fibers were reduced by isolated dorsal root potentials from C-fibers. In the absence of anesthetics, single C-volleys produced brisk and prolonged reflex discharges in ventral roots.

Animals↗
PubMed2005

Root canals and apical foramina of the buccal root of maxillary first premolars with longitudinal sulcus.

In the present study, periapical radiographs were analyzed to investigate the number of canals of the buccal root of maxillary 1st premolars with longitudinal sulcus, and compare the number of apical foramina observed on the radiographs to that revealed by scanning electron microscopy (SEM). Thirty-nine human maxillary 1st premolars had their crowns and palatal roots removed and the root canals (C) were explored with endodontic files until the tip of the instrument was visualized exiting the apical foramen/foramina (AF). Radiographs were taken with files inside the root canals and the specimens were classified as follows: 1C/1AF; 2C/2AF; 1C/2AF; 2C/1AF. Apices were examined under SEM and the number of apical foramina (considering those measuring >80 microm in diameter) was recorded. Only 17.1% (n=6) of the specimens had 1C/1AF; 77.2% (n=27) had 2AF in which 42.9% (n=15) had 2C and 34.3% (n=12) had 1C; 5.7% (n=2) had 2C/1AF. SEM examinations showed that 46.1% (n=18) of the specimens had 2AF; 23.1% (n=9) had 1AF; 23.1% (n=9) had 3AF; 7.7% (n=3) had 4AF. Radiographic and SEM findings for the number of AF coincided in 62.8% of the cases. A buccal longitudinal sulcus in the maxillary 1st premolar is usually accompanied by total bifurcation (42.9%) or apical bifurcation (34.3%) of the root canal. SEM identified a statistically higher number of apical foramina than radiographs (p<0.01).

Bicuspid↗
PubMed2003

[c-jun expression in spared dorsal root ganglion following partial dorsal root rhizotomy and acupuncture].

OBJECTIVE: To investigate the change of c-jun expression in spared dorsal root ganglion (DRG) following partial dorsal root rhizotomy and acupuncture. METHODS: Fifteen adult cats were divided into three groups with five cats in every group--sham operation, operation, and acupuncture following operation respectively. Animals of operation group were subjected to unilateral root rhizotomy (L1-L5, L7-S2 DRGs were sectioned, L6 DRG was spared). Electro-needling was performed alternatively at two sets of acupoints, including Zusanli and Xuanzhong, Futu and Sanyinjiao, located in the distribution area of spinal nerve L6 on the operated side, 30 min everyday for 7 days following unilateral root rhizotomy. The animals of sham operation group experienced only skin and muscle incisions. On the 7th day after operation, all animals were sacrificed. The L6 DRG on the disposal side of each animal was taken and made into frozen sections 20 micrograms in thickness. The sections were stained under the same condition using specific c-jun antibody (1:1000, Santa Cruz) by immunohistochemistry ABC method. The distribution and number as well as immunoreactive level of c-jun positive neurons in DRG were observed and measured. RESULTS: In the L6 DRG of sham operation group, only parts of neurons were stained. In contrast, the number of positive neurons and immunoreactive level for c-jun increased significantly in operation group (P < 0.05). Compared with the operation group, the operation plus acupuncture group had higher c-jun immunoreactive level of neurouns, but its number of c-jun positive neurons didn't change markedly. CONCLUSION: Partial dorsal root rhizotomy leads to the up-regulation of c-jun expression in neurons of spared DRG, and acupuncture enhances the up-regulation.

Animals↗