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PubMed2003

[Comparison of roots distribution in different maize plant type cultivars in the Songnen Plain].

By soil column culture and field experiment, the comparison of roots distribution of spreading-leaf and upright-leaf maize cultivars in the Songnen Plain was studied. The results showed that there were differences in the roots distribution of different maize cultivars. The maximum of root dry weight appeared on the 15th day and 30th day after silking for spreading-leaf and upright-leaf maize cultivar, respectively. Compared to spreading-leaf maize cultivar, the root dry weight of upright-leaf maize cultivar was higher by 12.2%. The vertical distribution of different maize cultivar roots was different. The root dry weight rate below 20 cm depth of spreading-leaf maize cultivar was less than 19%, whereas that of upright-leaf maize cultivar was more than 23%. Compared with spreading-leaf maize cultivar, the root dry weight rate at 40-100 cm depth was higher by 43.3%. There were differences between the different maize cultivars in the horizontal roots distribution. The roots of upright-leaf maize cultivar distributed tightly in horizon. The percentage of root dry weight of upright-leaf maize cultivar in a horizontal area 0-10 cm from the plant center was higher than that of spreading-leaf maize cultivar by 9.6%. Upright-leaf maize cultivar had more roots in deeper soil depth and it distributed tightly in horizon. Therefore, it was suitable for compact-planting. It was easier to acquire high yield for upright-leaf maize cultivar because it had good roots distribution characteristics.

Plant Roots↗
PubMed2003

[Gradient distribution of soil N, P, and K along the distance from Picea mongolica seedlings root surface].

Six years old seedlings of Picea mongolica were planted in pots with horizontal and vertical root treatments. Soil samples were stratified collected, and their available nitrogen (N), phosphorus (P), and potassium (K) contents were determined. The results showed that the available contents of N, P and K in soils along the distance from Picea mongolica seedlings root surface had a special gradient distribution. Near root surface, there was a depletion zone of soil available N, P, and K, and along the distance from it, the nutrient element contents increased gradually and reached their background values in the bulk soil. In the horizontal root treatment, the depletion zone of soil available N, P, and K existed in different distance from root surface, owing to the absorption and the use intensity of the seedlings to these nutrient elements. The depletion zone of soil available N and K appeared from 1 cm from root surface, and that of available P existed in 0.5 cm from root surface. In the vertical root treatment the depletion zone of available N and K also appeared from 1 cm from root surface as in the horizontal root treatment, but the available P content near root surface was lower than that far away from root surface. It is proved that the absorption and the utilize intensity of soil available P by Picea mongolica seedlings was intense, which might become a limiting factor to its growth and development. Therefore, Picea mongolica should be planted on soils rich in phosphorus, or P and N fertilizers should be applied to improve the absorption and the use efficiency of available P by Picea mongolica.

Nitrogen↗
PubMed2003

[Induction of hairy roots of Pueraria phaseoloides and its culture in liquid and solid medium].

An efficient transformation system for genetic transformation of medicinal plant, Pueraria phaseoloides, which contains puerarin and daidzein with hypothermic, spasmolytic, hypotensive and anti-arrhythmic activities, by using agropine-type Agrobacterium rhizogenes ATCC 15834 was developed. Hairy roots could be obtained directly from the cut edges of petioles of leaf explants of P. phaseoloides or via callus 20 days after inoculation with agrobacterium. The percentage of rooted leaf explants 35 days after infection was about 85%. Hairy roots could have a rapid growth on solid or liquid growth regulator-free MS medium. The transformation of hairy roots was confirmed by PCR amplification of rol B and rol C genes of Ri plasmid from A. rhizogenes. To investigate the physiological difference between solid and liquid culture, the biomass (fresh weight and dry weight), the reactive oxygen species (ROS) and the total content of soluble sugar in hairy roots cultured for 15 days in solid and liquid medium were detected, respectively, by the method of fluorescence labeling of 2',7'-dichlorofluorescein diacetate (2',7'-DCFH-DA) and by the anthrone colourimetry. Compared to hairy roots in solid medium, hairy roots grew more rapidly in liquid medium but formed no callus and appeared to become brown earlier during culture. The fresh weight, the dry weight, the total content of soluble sugar and the levels of reactive oxygen species of hairy roots cultured into liquid medium MS without plant growth regulators for 15 days were 1.59 times, 1.18 times, 5.25 times and 1.16 times, respectively as much as that of hairy roots cultured onto solid medium. Our results firstly indicate that P. phaseoloides hairy roots in solid medium can utilize or metabolize more soluble sugar but produce less reactive oxygen species than that in liquid medium. This may be related to the fact that hairy roots are easier to turn brown in liquid medium than that onto solid medium. Our results have laid a foundation for defining optimum culture manner for large-scale cultivation and large-scale production of secondary metabolites of P. phaseoloides hairy roots.

Culture Media↗
PubMed2005

[Identification of drought tolerant germplasm and inheritance and QTL mapping of related root traits in soybean (Glycine max (L.) Merr.)].

Fifty nine accessions of soybean (Glycine max (L.) Merr.) selected from 301 ones in Huang-Huai-Hai and Middle-Lower Changjiang Valleys were tested in two years for their tolerance to drought by using the mean membership index value averaged over those of plant height,leave number,dry root weight and dry stem and leaf weight. Four most tolerant accessions (Rank 1) and two most sensitive ones (Rank 5) were identified. There existed very significant correlations between drought tolerance and relative values of dry root weight,total root length, and root volume (per plant dry weight basis), respectively,which could be used as root indicators of drought tolerance. The RIL population derived from Kefeng 1 x Nannong 1138-2 was used to analyze the inheritance of the three related root traits by using the segregation analysis of quantitative traits under the major gene plus polygene mixed inheritance model. The results showed that between the two parents (Rank 1 x Rank 4), the relative values of dry root weight,total root length and root volume were respectively controlled by two major genes (linked together for the latter two traits, recombination value being 4.30% and 1.93%, respectively) plus polygenes with their major gene heritability values of 62.26%-91.81% and polygene heritability values 2.99%-24.75%, indicating that the major genes,especially the one with larger effect,accounted for a major part of the genetic variation between the two parents. It was identified that five, three, and five QTLs located on N6-C2, N8-D1b + W, N11-E, and N18-K linkage groups for relative dry root weight, total root length and root volume, respectively. Each of the traits appeared to have one locus (Dw1, R/1, and Rv1) with relatively large effect in comparison with their other loci, and those major ones were located near the same site of the same linkage group N6-C2. The results of segregation analysis and QTL mapping appeared pretty consistent with each other, which could be used as a demonstration of each other.

Adaptation, Physiological↗
PubMed2006

[Mathematical simulation of stomatal regulation involving root-sourced signaling ABA under soil drought condition].

A stomatal conduction model consisting of root water uptake model and stomatal control model under the participation of root-sourced signal ABA was developed in this paper, which considered the root water uptake effect function and root length density distribution function during root-sourced signal production. This model was used to simulate the course of maize stomatal conduction controlled by the root-sourced signal in field. The results showed that owing to the considering of the influence of root water uptake effect function and root length density distribution in soil profile, this model could more accurately depict the intensity of root water uptake, the ABA concentration produced in root system, the root ABA concentration in different soil layers and in xylem, and the controlling process of plant stomatal regulation by root-sourced ABA.

Abscisic Acid↗
PubMedDate not supplied

Characteristics of Atropa belladonna hairy roots cryopreserved by vitrification method.

Atropa belladonna hairy roots (clone M8) were successfully cryopreserved by using the vitrification method. A. belladonna hairy root tips were precultured on a half strength of Murashige and Skoog (MS) solid medium with 0.1 mg per L 2,4-D or without phytohormone for 1 day, and then dehydrated with PVS2 solution for 15 minutes prior to immersion into liquid nitrogen for 1 day, 1 week, 1 month and 3 months. Hairy root tips kept in liquid nitrogen were rapidly thawed at 36 degree C in a water bath. The root tips were recultured on half strength MS medium. The hairy root tips, precultured with 2,4-D before cryopreservation, showed a higher survival rate than those precultured without phytohormone. The hairy root tips, precultured with 2,4-D, showed an average survival rate of 83 percent. There was no significant difference in the viability of the hairy roots cryopreserved for different periods. The regrowth of cryopreserved hairy roots was similar to that of untreated hairy roots and tropane alkaloid productivity became stable after 4th subculture. PCR analysis of hairy roots demonstrated the conservation of the T-DNA in cryopreserved hairy roots. These results indicate that cryopreservation by vitrification method is useful to preserve A.belladonna hairy root clone M8.

Atropa belladonna↗
PubMed1989

[Clinical evaluation of the voltage gradient method for root canal measurement].

The voltage gradient method for root canal measurement was evaluated in vivo and in vitro. For the evaluation in vivo, 25 single root teeth, were employed. The working length was measured by bipolor or monopolor electrode. After measurement, the electrode was fixed on the tooth, and the tooth was extracted. Radiograph was taken from 12 directions perpendicular to longer axis of tooth, and the relation between anatomical foramen, physiological foramen and the attained position of electrode tip was assessed. In the evaluation in vitro, 7 extracted teeth were used, for which the positions of anatomical foramen and physiological foramen had been determined in advance from radiograph, in order to determine the influence of the root canal irrigants and medicaments. The electrode was fixed on electronic calipers and direct reading of the movement. Root canal irrigants and medicaments were injected into root canal, and the measurements were evaluated. The results were as follows: (1) In the cases of 22 teeth measured by monopolar electrode in vivo, the electrode tip was within 0.5mm from physiological foramen except one tooth. (2) In the cases of 3 teeth measured by monopolar electrode in vivo, the electrode tip was within 0.4mm from anatomical foramen. (3) In the cases, where electrolyte solution was filled in root canal and measurement was made by bipolar in the evaluation in vitro, the results of measurement were stable, and the electrode tip tended to be slightly closer to coronal direction from physiological foramen. (4) In the cases where non-electrolyte solution was filled in root canal and measurement was made by bipolar electrode in the evaluation in vitro, the results of measurement were not stable, and the electrode tip tended to be closer to the apex from physiological foramen. (5) In the case of the evaluation in vitro, where electrolyte solution was filled in root canal and measurement was made by monopolar electrode, the electrode tip tended to be a little closer to the front than the anatomical foramen. (6) In the evaluation in vitro, where non-electrolyte solution was filled in root canal and measurement was made by monopolar, the measurement was not achievable. (7) 10% NaOCl solution was found to be very useful as electrolyte solution filled in root canal to search physiological foramen by this measurement method. The above results suggest that the voltage gradient method for root canal measurement is highly reliable because root canal morphology at the apex can be directly in identified.

Dental Pulp Cavity↗
PubMed1982

Lumbosacral nerve-root anomalies.

Forty-six cases of anomalous lumbosacral nerve roots were found in a series of 2123 patients who underwent myelography with water-soluble contrast medium. The anomalies were classified into five types. In Types I and II, one or more nerve roots emerged from the theca at a more cranial (Type I) or caudal (Type II) level than normal. In Type III, two or more roots emerged through closely adjacent openings in the dura, whereas in Type IV two nerve roots emerged from the dural sac combined as one nerve trunk. In Type V, two roots were connected by an anastomotic branch shortly after their emergence from the dura. The anomalies were usually unilateral and the fifth lumbar and first sacral-nerve roots were the most frequently involved. Type-III and Type-IV anomalies were the most common (69 per cent). Twenty-one per cent of the patients had lumbosacral anomalies and one had congenital absence of the articular facets of the lumbosacral joint on the side of the nerve-root anomaly. In seven patients the anomalous root or roots were compressed by a herniated disc, and the roots were entrapped in a lateral recess or intervertebral foramen in two. Symptoms and signs of nerve-root compression were usually severe, even in the patients with a small disc protrusion. The severity of the clinical findings appeared to be due to the reduced mobility of the anomalous roots. Adequate surgical decompression led to satisfactory final results in all nine patients.

Adult↗
PubMed1995

Nerve root infiltration and sympathetic block. An experimental study of intraradicular blood flow.

STUDY DESIGN: The nerve root of L7 was exposed, and a clamp was applied to simulate radiculopathy. Intraradicular blood flow was measured at the takeoff point of the nerve root and at the distal to the dorsal root ganglion before and after nerve root infiltration with 2% lidocaine or physiological saline solution (control group), or sympathetic ganglion block with 2% lidocaine. OBJECTIVES: To investigate one of the mechanisms of the therapeutic effect of nerve root infiltration by assessing changes in intraradicular blood flow. SUMMARY OF BACKGROUND DATA: Increased intraradicular blood flow was noted both proximal and distal to the clamp after nerve root infiltration or sympathetic ganglion block with 2% lidocaine. No increase was seen after nerve root infiltration with saline solution. Macroscopic and microscopic examination showed that dye after nerve root infiltration did not spread beyond the clamped region to the proximal site. METHODS: Intraradicular blood flow was measured with a tissue blood flowmeter using the electrolytic hydrogen clearance method before and after nerve root infiltration with 2% lidocaine or physiologic saline solution (control group), or sympathetic ganglion block with 2% lidocaine. RESULTS: Increased intraradicular blood flow was noted both proximal and distal to the clamp after nerve root infiltration or sympathetic ganglion block with 2% lidocaine. No increase was seen after nerve root infiltration with saline solution. CONCLUSIONS: An increase in intraradicular blood flow is related to one of the mechanisms of the therapeutic effect of nerve root infiltration. This effect may be mediated by the sympathetic nervous system.

Animals↗
PubMed1992

Factors determining the outcome of scaling and root planing.

Scaling and root planing are the predominant and recognized forms of periodontal therapy. They have been known for centuries, and have been investigated with increasing intensity since the turn of the century. Scaling and root planing aim at therapeutic changes of the "hard tissue lesion" at the root surface, in order to render it biologically acceptable to cells capable of attaching to it. Two major components of these root surface alterations are calculus and cementum alterations. Numerous studies have shown that scaling and root planing effectively removes subgingival deposits, and that this removal is seldom complete in deeper pockets. Even though beneficial clinical effects of scaling and root planing have been shown, it is unlikely that the full potential of healing is utilized today due to technical shortcomings. Several studies have shown that the design and dimensions of curets as used today are not optimal. These instruments are for many situations too big, subject to rapid dulling, and produce a smear layer. Chemical agents have been used to remove this layer with limited success. The therapist is a virtually unknown factor in the system of delivering scaling and root planing. A recent study showed that scaling and root planing forces used by different therapists on similar root surfaces varied by factors greater than 10. In addition, higher forces were shown to remove significantly more root substance. Apparently there is a large subjective component included in the delivery of scaling and root planing therapy. Even though scaling and root planing have been shown to be effective therapeutic procedures, many aspects require more research.

Clinical Competence↗
PubMed1995

Morphologic criteria for root canal treatment of primary molars undergoing resorption.

The endodontic anatomy of primary molars is difficult to predict because of the balance of resorption and hard tissue deposition. In particular, the resorption causes perforating lacunae across the wall of the root, even at the furcation level, and modifies shape, dimension and position of endodontic apex. The phenomenon can be so deep as to compromise endodontic therapy. The first aim of the study was to verify if reliable criteria can be found for treatability in primary molars undergoing resorption, i.e. if it is possible to predict if perforating lacunae are present or not. The second aim of the study was to verify if other informations needed for endodontic treatment, as shape, dimension and location of the apex, and curvature of the root canal can be predicted. For the study, 80 extracted primary molars, 75 of which pulpally involved by caries, were selected. The treatability was evaluated in term of root length, root shape, dimension and shape of endodontic apex, age of the patient and X-ray index of resorption. The association between variables was performed by multiple correspondence analysis. The results suggested that root length was the most reliable criterion of the integrity of the root. The borderline of treatability was at the length of 4 mm. The position of endodontic apex related to anatomical apex, and the lingual related to the buccal root length were analyzed by linear regression analysis. The canal length was often similar to the root length (i.e. the endo and anatomical apices were very close) in lower and upper molars. However, in lower molars, if two or more canals were present in the same root, a discrepancy was observed between buccal and lingual root length. This finding was constant in first lower molars. In addition regression analysis provided a linear function between the lengths of the buccal and lingual side of the same root in lower molars. Its coefficient b was 0.73.

Analysis of Variance↗
PubMed2026

Uncovering the early and conserved molecular mechanisms of root nitrogen foraging in model and crops.

BACKGROUND: Nitrogen (N) foraging, the ability of plants to promote preferential root growth in N-rich patches of soil, is fundamental to the competitiveness and wellbeing of plants. A unique “split-root” system, where a heterogenous N environment stimulates root foraging, provides a powerful experimental model to study the mechanisms underlying root foraging in model (Arabidopsis) and/or crop plants. RESULTS: We used the split-root set up to capture early molecular events involved in systemic N-signaling after exposure to a heterogeneous N signal, through time-course transcriptomic analysis across shoots and roots of Arabidopsis. We found that a histone methyltransferase, SET DOMAIN GROUP 8 (SDG8), is necessary for root N-foraging, suggesting a previously unknown role for chromatin regulation in mediating the preferential root growth response to colonize N-rich patches. To determine if the underlying molecular mechanism is conserved in evolution, we compared the root foraging behavior from model-to-crop (Arabidopsis, tomato and maize). Our analysis showed the model and crop species shared a root N-foraging growth response, with some variation among specific genotypes. Interestingly, we observed both shared and distinct transcriptional responses to heterogenous N environments among these three species. CONCLUSIONS: Our study has generated insights into the molecular basis of root N-foraging, with the potential to improve nutrient use efficiency in crop plants in a heterogeneous field environment.

Crops, Agricultural↗
PubMed1985

Variation in the developing root cone angle of the permanent mandibular teeth of modern man and certain fossil hominids.

The radiographic appearance of the developing root apex of 461 mandibular teeth was studied using ellipsopantomographs of 77 individuals. The angle formed by the mesial and distal aspects of the developing root cone was measured for each quarter of root development in the permanent mandibular teeth of each subject. Large values for this angle in the more coronal part of the root gradually decreased towards the root apex where values were small in all teeth studied. This gradual decrease in the angle of the developing root cone is concordant with the faster increase in root length but slower rates of dentinogenesis reported for the apical region of human teeth in the literature, as the decrease is likely to reflect the increasing numbers of odontoblasts that become involved in root formation as it proceeds apically. The developing root cone angles of one of the five fossil hominid specimens studied (KMN-ER 820) fall outside the range for the developing root cone angle of the developing premolar and permanent second molar roots in modern Homo sapiens and is evidence of a faster rate of root elongation than is typical for modern man.

Animals↗
PubMed1992

Focal conduction block in the dorsal root ganglion in experimental allergic neuritis.

Acute experimental allergic neuritis was induced in Lewis rats by inoculation with bovine intradural root myelin and adjuvants. In terminal experiments, sensory conduction was assessed in rats with hindlimb ataxia and weakness by stimulating the exposed sciatic nerve and recording directly from the exposed L-4 spinal nerve, dorsal root ganglion, dorsal root, and dorsal root entry zone. Focal conduction block was present in a high proportion of large-diameter fibers in the dorsal root ganglion. In contrast, nerve conduction in the peripheral nerve and spinal nerve was essentially normal apart from probable conduction block in some fibers in the proximal spinal nerve in a minority of rats. The afferent volley arriving at the dorsal root entry zone of the spinal cord was greatly reduced, as a consequence of the conduction block in the dorsal root ganglion and probable conduction block in the dorsal root. The M wave recorded from the fourth dorsal interosseus muscle of the hindfoot was normal in amplitude but slightly prolonged in latency and the H reflex was absent. These electrophysiological findings correlated well with the histological findings of inflammation and prominent demyelination in the dorsal root ganglia and dorsal roots with minimal involvement of the proximal spinal nerve and no involvement of the sciatic nerve. It is concluded that the hindlimb ataxia in rats with this form of acute experimental allergic neuritis is due to demyelination-induced nerve conduction block in the dorsal root ganglia and probably in the dorsal roots.

Afferent Pathways↗
PubMed1990

Plasticity of dorsal root and descending serotoninergic projections after partial deafferentation of the adult rat spinal cord.

Plasticity of dorsal root (DR) and descending serotoninergic (5-HT) projections following dorsal rhizotomy from L2 to S1 sparing L5 was studied by means of an intra-animal comparison in the adult rat spinal cord. Projections of the chronically and acutely spared root were compared by cholera-toxin conjugated horseradish peroxidase (CT-HRP) injected into the sciatic nerves as the transganglionic tracer. Projections in unoperated controls, operated controls (acute bilateral spared root), and in experimental animals (chronic spared root on one side and acute spared root on the other) were mapped and the density was measured with an image analysis system. Labeled DRG cells and motor neurons were counted to determine if there were differences in the delivery of the label between the two sides. Measurements of the area of the dorsal horn and, separately, of the superficial laminae were made to control for shrinkage. DR projections were symmetrical in operated and unoperated controls, but a significant increase in DR projection density was found from L6 to L3 in the dorsal horn and Clarke's nucleus at L1 on the chronic spared root side in animals in which an equal number of DRG cells was labeled on the two sides. Density of 5-HT immunoreactivity was symmetrical in controls. Ipsilateral to chronic spared root rhizotomy, the area fraction occupied by 5-HT projections increased in Clarke's nucleus and in the superficial dorsal horn of all partially deafferented segments except L5, the spared root segment. Partial deafferentation of the adult rat lumbosacral spinal cord may therefore elicit sprouting from the spared dorsal root and, outside of the dorsal root projection zone, sprouting from the spared descending 5-HT system. Plasticity of dorsal root projections and of 5-HT projections occur in different regions; in regions of the increased spared root projection, no increase in seen in 5-HT projections, suggesting that sprouting in the adult rat spinal cord is regulated, perhaps by competitive or hierarchical mechanisms.

Animals↗
PubMed2000

Mechanical compression of the lumbar nerve root alters pain-related behaviors induced by the nucleus pulposus in the rat.

The purpose of this study was to refine a method of nerve-root injury in the rat to produce hyperalgesia, a pain-related behavior, and to determine if there were any relationships between the histological extent of nerve-root injury and the magnitude of hyperalgesia. Three methods were used to produce hyperalgesia: irritation of a nerve root by ectopic nucleus pulposus, silk loop alone, or both silk loop and ectopic nucleus pulposus. Autologous nucleus pulposus obtained from coccygeal intervertebral discs was relocated on the lumbar nerve roots after laminectomy. Two loops of 4-0 silk were placed around the exposed nerve roots. Hyperalgesia was measured preoperatively and postoperatively. The distribution of myelinated axons in the dorsal nerve roots was evaluated histologically. Mechanical hyperalgesia was detected in rats in which autologous nucleus pulposus was applied to the nerve root but not in those in which silk loops were used. Silk loops around the nerve root resulted in thermal hyperalgesia only in rats in which autologous nucleus pulposus was applied to the nerve root. Fewer large myelinated fibers were seen in the rats in which silk loops were used. Although a silk loop around the nerve root was not sufficient to produce hyperalgesia, supplemental application of autologous nucleus pulposus to the nerve root produced thermal hyperalgesia. It is possible that mechanical constriction of the nerve root alters the pain-related behavior elicited by chemical factors from the nucleus pulposus.

Animals↗
PubMedDate not supplied

Risk factors for neo-aortic root enlargement and aortic regurgitation following arterial switch operation.

The objectives of this study were to evaluate changes in dimension of the neo-aortic annulus, aortic root, and aortic anastomosis following arterial switch operation (ASO) and to identify risk factors for developing abnormal neo-aortic root enlargement and aortic regurgitation (AR). Prior studies report development of neo-aortic root dilatation and AR in a small subset of patients after ASO. Predisposing factors for neo-aortic root dilatation and development of moderate/severe AR are poorly understood. We performed a retrospective review of all patients with d-transposition of the great arteries (d-TGA) or double-outlet right ventricle with subpulmonary ventricular septal defect (VSD) who underwent ASO from May 1986 to January 2001. Serial echocardiograms were reviewed to measure neo-aortic annulus, root, and anastomosis diameter (z scores) and to determine progression of AR. Potential risk factors were assessed for developing neo-aortic root enlargement and AR. There were 119 patients (44 female and 75 male): 73 patients had simple d-TGA, 36 had d-TGA with ventricular septal defect, and 10 had a Taussig-Bing heart. The median duration of follow-up was 65 months (range, 12-180). The median neo-aortic root (z = 0.55+/-2.2; p < 0.01) and aortic annulus dimensions (z = 1.57+/-1.75; p < 0.01) were significantly increased over the study period. Aortic anastomosis diameter correlated with growth of the ascending aorta (z = 0.55+/-1.24). Development of severe neo-aortic root enlargement was associated with prior pulmonary artery (PA) banding (p < 0.01), the presence of a VSD (p = 0.03), and Taussig-Bing anatomy (p < 0.01) but was independent of coronary arterial anatomy, coronary arterial transfer technique, or associated lesions (p > 0.05). At latest follow-up, there was no or trivial AR in 88 patients, mild AR in 29 patients, and moderate to severe AR in 3 patients. Risk factors for developing mild or worse AR included severe or rapid neo-aortic root dilatation (p < 0.01). Only 3 patients required surgical intervention for AR. Despite the significant prevalence of neo-aortic root enlargement at intermediate follow-up after ASO, there is a low incidence of significant AR. Prior PA banding, the presence of VSD, and Taussig-Bing anatomy are risk factors for severe root enlargement. Surgical intervention for AR was rare (2%), however, serial surveillance of such patients is vital to monitor for neo-aortic root enlargement and potential aortic valve dysfunction.

Anastomosis, Surgical↗
PubMed2000

Durability of aortic valve preservation and root reconstruction in acute type A aortic dissection.

BACKGROUND: The aim of this study was to determine the durability of aortic valve preservation and root reconstruction in type A aortic dissection with involvement of the aortic root. METHODS: From November 1976 to February 1999, 246 patients underwent surgical treatment for acute type A aortic dissection at our institution. In 121 patients (49%), all with acute type A dissection and aortic root involvement, the aortic valve was preserved and one or more of the sinuses of Valsalva were reconstructed. The mean age of this group was 59 +/- 11 years and 70 (58%) were men. Thirty patients (25%) were operated in cardiogenic shock. Criteria for aortic root reconstruction were technical feasibility and surgeon preference. Techniques used for reconstruction were valve resuspension in all patients and additional reinforcement of the aortic root with Teflon (L.R. Bard, Tempe, AZ) felt (n = 21), gelatin-resorcinol-formaldehyde-glue (GRF-glue, Fii, Saint-Just-Malmont, France) (n = 103), or fibrinous glue (Tissu-col, Immuno AG, Vienna, Austria) (n = 5). Mean follow-up was 43.5 +/- 46 months. RESULTS: The operative mortality was 21.5% (n = 26). Actuarial survival was 72% +/- 4%, 64% +/- 5%, and 53% +/- 6% at 1, 5, and 10 years, respectively. Median aortic regurgitation in patients with retained native aortic valve at follow-up was 1+. All root reoperations included aortic valve replacement (n = 12). Freedom from aortic root reoperation was 95% +/- 2% at 1 year, 89% +/- 4% at 5 years, and 69% +/- 9% at 10 years. The incidence of aortic root reoperation was 23%, 11%, and 40%, respectively, when Teflon felt, GRF-glue, and fibrinous glue were used for root reconstruction. Multivariate Cox proportional hazard analysis revealed the use of fibrinous glue (RR = 8.7; p = 0.03) as well as the presence of an aortic valve annulus more than 27 mm (RR = 4.2; p = 0.04) as independent risk factors for aortic root reoperation. CONCLUSIONS: Aortic valve preservation in acute type A dissection provides relatively durable results. The use of fibrinous glue for root reconstruction seems to compromise the long-term durability of the repair compared with Teflon felt and GRF-glue. A dilated aortic annulus requires a more extensive root procedure.

Actuarial Analysis↗