External Root Research Articles

Bulb and inflorescence development in Leucocoryne ixioides (Hook.) Lind.

SummaryLeucocoryne (Alliaceae) is a genus of bulbous plants with cut-flower potential. They are native to central Chile, which experiences a Mediterranean climate. The plants are ‘dormant’ during the heat of Summer (as bulbs, with no external leaf or root development). Leucocoryne plants ‘resume’ growth in Autumn, with the arrival of the rains and falling temperatures, and flower towards the end of their growth cycle, as temperatures rise again in Spring. Leaf and inflorescence initiation began during the Summer ‘dormant’ period and ended the following Spring. They emerged from the bulbs during the same growth cycle as they initiated. Leucocoryne bulbs consist of a series of sympodial units, each containing two leaves and a terminal inflorescence. The renewal meristem for each unit was initiated at the base of the inflorescence, in the axil of the younger leaf primordium. Leucocoryne bulbs were replaced each growing season. Secondary bulbs were initiated in the axils of the oldest, recently-initiated, leaves during late Spring.

Evaluation of External Apical Root Resorption in Subjects Treated with Pre-adjusted Edgewise and Begg's Mechano - Therapy - A Comparative Radiographic Study

Evaluation of External Apical Root Resorption in Subjects Treated with Pre-adjusted Edgewise and Begg's Mechano - Therapy - A Comparative Radiographic Study

Longer Orthodontic Treatment May Result in Greater External Apical Root Resorption: What Are the Treatment-Related Aetiological Factors of External Apical Root Resorption of the Maxillary Incisor

Longer Orthodontic Treatment May Result in Greater External Apical Root Resorption: What Are the Treatment-Related Aetiological Factors of External Apical Root Resorption of the Maxillary Incisor

Detection and evaluation of specimen-mass changes with a 16-bit intraoral imaging charge-coupled device

tive diagnostic tool for the early detection of external apical root resorption (EARR). Methods and Materials. Mandibular incisors (n = 36) with and without simulated EARR lesions were used. Eighteen teeth with facial and proximal windows, each with a range of 2 sizes, were placed in 15 ml test tubes containing 5 ml of 6 N HCL for 10 minutes. A sample of the acid solution was analyzed for calcium concentration by atomic absorption spectrophotometry. Incisors were imaged at 808, 908 and 1008 under three test conditions: 1. with an orthodontic bracket bonded on the labial surface, 2. without a bracket, and 3. with an orthodontic bracket, fitted with additional fiducial markers (SRT). The images were reconstructed and subtracted to determine the accuracy and sensitivity of the method. Quantified histograms for each subtracted image were constructed. Results. At either an angle of 80 or 100 degrees, the bracketed group had the largest mean standard deviation of the subtraction histograms while the SRT group had the smallest. Density values as a function of total calcium removed was plotted indicating a linear relationship between subtraction density units and calcium loss. Conclusion. The use of the SRTwas significantly more accurate than the use of brackets alone for DSR reconstructions. This model shows promise for detecting EARR prior to a noticeable decrease in root length. It may be useful for early detection of resorptive lesions during routine orthodontic treatment. The present study, using a current method for digital subtraction and image reconstruction, focused on the reliability of early lesion detection in vitro, before testing it clinically.

Digital subtraction evaluation for external apical root resorption in orthodontic case simulations

Digital subtraction evaluation for external apical root resorption in orthodontic case simulations

Critical evaluation of electro-stimulation for management of female urinary incontinence.

Electro-stimulation has been reported to be effective in the relief of stress and urge urinary incontinence. The rates of cure and improvement brought about by pelvic floor electro-stimulation in patients with urinary incontinence are 30-50% and 60-90%, respectively. In clinical practice, vaginal, anal and surface electrodes are used for external, short-term stimulation, and sacral root stimulation for internal, chronic (long-term) stimulation. The effectiveness of electro-stimulation has been verified in a randomized, placebo-controlled study. However, its superiority over other conservative treatments, such as pelvic floor exercise, has not been confirmed. A long-term effect has also been reported. In conclusion, pelvic floor exercise together with electro-stimulation is the mainstay of conservative management for the treatment of stress incontinence. For urge and mixed stress plus urge incontinence, electro-stimulation may be the first choice alternative treatment to drug therapy.

Recovery of a rhizosphere-colonizing GEM from inside wheat roots

Pseudomonas chloroaphis 3732 RN-L11 is a genetically modified bacterial strain that contains the lacZY marker genes in its chromosome. This strain is known to be a vigorous colonizer of plant roots and rhizosphere soil, and has been used as a model to evaluate survival and persistence of field-released genetically engineered microorganisms (GEMs). However, the possibility that strain 3732 RN-L11 may also colonize internal plant tissues has not previously been investigated. Using spring wheat as a model system, we studied the ability of strain 3732 RN-L11 to colonize external and internal root tissues after seed inoculation. Strain 3732 RN-L11 was recovered from rhizosphere soil of 28-, 42-, and 56-day-old seedlings with mean population sizes of 3.3 × 105, 7.5 × 104, and 2.2 × 105CFU·g-1fresh root tissue, respectively. In addition, this strain was consistently recovered from surface-sterilized root tissues of 28- to 56-day-old seedlings with mean population sizes of 1.0 × 102to 6.2 × 103CFU·g-1fresh root tissue. Our results indicate that evaluation of plant-associated GEM populations after field release should include all possible colonization niches, including internal plant tissues.Key words: genetically engineered microorganism, rhizosphere, endophyte.

Fusarium moniliforme and F. proliferatum Isolated from Crown and Root Rot of Asparagus and Their Association with Asparagus Decline in Argentina.

During the summer of 1995-1996, an 80-ha field of 6-year-old asparagus plants (cv. UC 72) in Saladillo (Province of Buenos Aires) was affected by a decline syndrome (1). The plants showed a decline in vigor and approximately 60 to 70% of the plants died. The symptomatic plants were chlorotic, stunted, with stem lesions and crown and root rot. Fusarium moniliforme and F. proliferatum were isolated from vascular and epidermal tissues of roots, crowns, and stems. Identification of Fusarium to species was made by examining conidiogenous cells from colonies cultured on KCl medium (2). Microconidia were born in long and short chains and false heads. The isolates were identified based on the the presence of polyphialides in F. proliferatum and their absence in F. moniliforme, which produces monophialides only (2). In two separate trials, asparagus seeds (cv. UC 72) were surface sterilized and placed in steamed soil infested with a conidial suspension of each species. The viable propagules in the soil (CFU per g) were estimated by soil plate dilutions on Nash & Snyder-PCNB (pentachloronitrobenzene) medium. The F. moniliforme and F. proliferatum soil densities were 19.2 × 103 and 23 × 103 CFU per g of soil, respectively. The pots were placed in the greenhouse on different benches to avoid cross-contamination. After 4 months, inoculated plants showed root and crown discoloration. F. moniliforme and F. proliferatum were reisolated (64 and 75%, respectively) from discolored portions of internal and external root and crown tissues. Although the stems did not show symptoms, F. moniliforme and F. proliferatum were also recovered (27 and 38%, respectively) from asymptomatic tissues. Six months after inoculation the plants developed chlorotic symptoms with crown and root rot, and then wilted. F. moniliforme and F. proliferatum were reisolated from root systems, crowns, and stems of all inoculated plants. F. moniliforme and F. proliferatum are involved in corn stalk and ear rot in Argentina. Corn and asparagus are frequently grown in close proximity and often follow one another at a particular site. Airborne and soil debris carrying F. moniliforme and F proliferatum from corn may be an additional source of inoculum for asparagus in Argentina. The results indicate that the presence of F. moniliforme and F. proliferatum is a factor that contributes to asparagus decline in Argentina.

Residual stress analysis of an external grooved thick-walled pressure vessel

Residual stress analysis of an autofrettaged thick-walled pressure vessel containing an external groove was described in order to calculate the stress concentration at the external groove. The autofrettage residual stress distributions of the external grooved thick-walled pressure vessel were simulated using an equivalent thermal loading from the analogy of thermal and autofrettage residual stress fields. Thermal stresses due to the simulated thermal loadings for various degrees of autofrettage overstrain level were computed using finite element methods. Very high stress concentration factors due to autofrettage loadings were obtained at the external groove root that contained a sharp root radius. Experimental measurement of residual stresses for a fully autofrettaged smooth thick-walled pressure vessel using an equivalent saw cut method resulted in very close agreement with the theoretical autofrettage residual stress distributions. The stress analysis results implied that the autofrettage residual stress concentration might cause a cracking problem at the external groove root of the thick-walled pressure vessel, indicating that lower autofrettage overstrain and a groove geometry change were desirable for enhanced durability.

MAIN VERSUS EXTERNAL ROOTS AND PHOSPHORUS EFFICIENCY IN COMMON BEAN: ARE ALL ROOTS CREATED EQUAL?

Separate evaluation of main and external roots was critical to understanding results from a study on phosphorus (P) efficiency in common bean. A subsection of the root system, including both main roots and external roots, was compartmentalized and subjected to low P conditions. The rest of the root system was maintained at either low or high P-nutritional status. P distribution at the mid-pod fill stage was determined for root components (main and external roots) and shoot components (leaves, stems, pods). A 50% inhibition in main root growth and moderate reductions in diameters of both root types were found in low P plants compared to high P plants. Marked reduction in main root growth, coupled with a limited reduction in external root growth and thinner roots, allowed low P plants to reduce biomass and P investment in compartments by 54 and 42%. Yet root exploration of the compartment, in terms of root length per soil volume, was similar for both low and high P plants. Further, P removal from compartments was similar for roots of low P plants and high P plants. Taken together, the data suggest efficiency of P acquisition in P-stressed common bean is enhanced by selective inhibition of main root growth and continued growth of external roots.

Soil disturbance and infection of Trifolium repens roots by vesicular-arbuscular mycorrhizal fungi

Removal and storage of the surface layers of soil is known to decrease the infectivity of vesicular-arbuscular mycorrhizal (VAM) fungi. Previous studies have mostly examined the effects of profound soil disturbance on the infectivity of VAM fungi. This study examined the effects of increasing degrees of topsoil disturbance on the infectivity of VAM fungi in two sites on sandstone soils in southeastern Australia. Intact soil blocks (20×20×15 cm) were taken from each of the two sites. Increasing degrees of topsoil disturbance were achieved by cutting the blocks longitudinally into four (dist. 1), nine (dist. 2), and 25 (dist. 3) equal portions. Seeds of Trifolium repens L. were sown into the blocks and harvested 14, 21, 28, 35 and 42 days after sowing. At each sampling date, total root length, root length colonised by VAM fungi and shoot dry mass were measured. VAM colonisation had commenced by 14 days in the roots of seedlings grown in intact, dist. 1, and dist. 2 soil blocks. The initiation of VAM colonisation was delayed by up to 6 weeks for seedlings grown in the dist. 3 soil blocks. The low (i.e. dist. 1) and intermediate (i.e. dist. 2) degrees of soil disturbance did not cause a delay in the initiation of VAM, bud did significantly reduce the proportion of root length colonised by VAM fungi after 21 days. After 21 days, shoot dry mass was significantly less in the seedlings grown in the dist. 3 soil blocks though not in the low and intermediate disturbance treatments. It is concluded that the most severe experimental disturbance probably disturbed the external hyphal network and root fragments (containing hyphae and vesicles), which in turn temporarily reduced the infective potential of the fungus to zero. The observed delay in the initiation of VAM in the most disturbed blocks can, therefore, be explained by the time required for hyphae to grow from other propagules in the soil which survived the disturbance event.

Effect of trichloracetic acid on the microhardness and surface morphology of human dentin and enamel.

Trichloracetic acid is recommended for the treatment of external cervical root resorption. The present study examined the effect of 90% trichloracetic acid on the microhardness and surface morphology of human dentin and enamel. Intact extracted human teeth were sectioned and embedded in acrylic resin. Each tooth was grinded and highly polished exposing a flat surface of dentin and enamel. The teeth were treated with 90% trichloracetic acid for 30, 60 and 90 s. Vicker's microhardness of the dentin and enamel was assessed for each tooth before and after each treatment. In addition the surface morphology of a trichloracetic acid treated tooth was examined via SEM. The results showed that 90% trichloracetic acid caused a second order type reduction of the microhardness, as well as structural changes in both dentin and enamel.

PH variation among materials used for intracoronal bleaching

Intracoronal bleaching of pulpless teeth with 30% hydrogen peroxide may result in external cervical root resorption. One of several suggested etiological factors associated with this complication is the pH of the bleaching materials. Because the available data on the pH values of bleaching materials were conflicting, it was the purpose of this study to measure the pH of the materials commonly used for bleaching pulpless teeth. The pH of different concentrations of sodium perborate and 30% hydrogen peroxide, alone or in combination, were measured for a period of 14 days. Sodium perborate was confirmed to be alkaline, whereas 30% hydrogen peroxide was acidic. The pH of the materials when mixed together gradually changed from acidic to alkaline as the concentration of sodium perborate was increased. A thick clinical consistency mixture of both materials was alkaline, and its alkalinity increased with time. These results do not support the theory relating bleaching-induced root resorption to an acidic pH of the bleaching pastes.

INFLUENCE OF BORON NUTRITION ON GLUCOSINOLATES AND REDUCING SUGARS OF TURNIP

The influence of six boron treatments (0, 0.1, 0.5, 2.5, 5.0 and 10.0 ppm) on glucosinolates and reducing sugars was studied in tops and roots of hydroponically grown Snow Ball turnip (Brassica rapa L.). The glucosinolates were determined by quantifying their hydrolytic products, 5-vinyl-oxazolidine-2-thione (goitrin), volatile isothiocyanates, and thiocyanate ion. While growth of plants receiving no boron (0 ppm) was drastically impaired, that of plants receiving 0.1–5.0 ppm boron was equally vigorous; growth was slightly inhibited with 10.0 ppm boron. Mild boron deficiency was manifested as brown-heart in roots of fully-sized turnips from the 0.1 ppm boron treatment although there was no apparent effect on external root appearance or on foliage and plant growth. In roots of boron-deficient turnips, elevated yields of goitrin were found, accompanied by relatively high yields of thiocyanate ion and low contents of reducing sugars.

A comparative analysis of intrusion of incisor teeth achieved in adults and children according to facial type

A comparison was made of incisor intrusion achieved in adults and children with deep bite. Facial type was also examined for effect upon intrusion achieved. Fifty-five cases treated with bioprogressive mechanics were studied cephalometrically; subjects included twenty-four adults and thirty-one children. Neither age nor facial type was found to be statistically related to the amount of incisor intrusion achieved in this sample. A method of measuring intrusion at the root apices was devised and was thought to give a more accurate indication of actual bodily intrusion. More external root changes during treatment were observed for adults than for growing children. There was a wide latitude in the amount of intrusion observed in both groups and in all three facial types. Considerable overbite reduction was noted for the sample, and intrusion was found to be but one factor in this.

Pilonidal disease

Abstract 1. 1. Pilonidal inflammatory disease is common in the Navy. At our Naval Hospital, 7.5 per cent of operations in a recent period were performed for the eradication of this condition. The definitive surgical treatment of a series of 319 patients was reviewed. Of these 241 (75 per cent) were primary admissions and seventy-eight (25 per cent) had previously had one or more unsuccessful definitive surgical operations. 2. 2. Pilonidal cysts and sinuses can originate in embryo from the neurogenic medullary canal, from infolding of the dorsal epidermis or from both. Three clinical types result: subcutaneous cyst alone, (neurogenic); sinuses or dimple alone, (epidermal); subcutaneous cyst communicating with sinuses (neurogenic and epidermal). 3. 3. We find no convincing evidence to prove that hair grows from the epithelium of pilonidal cysts. We believe that external hair grows into the sinus, extends into the cyst, breaks off from the external root and in time is moulded into “nests.” 4. 4. Pilonidal inflammatory disease in our clinical cases occurred in four main types: (1) sinuses, (2) acute abscesses, (3) infected subcutaneous cyst and sinuses, and (4) infected subcutaneous cyst alone. Treatment of these types varies for each type as well as for individual variations in type. 5. 5. Recurrent pilonidal disease following previous definitive operation is common; seventy-eight cases in this series. In two-thirds of these, recurrence resulted from unsuccessful primary suture. With characteristic uniformity the lesion in most of these consisted of a deep sinus under a well healed scar. That fundamental surgical principles were disregarded by the original surgeon is indicated by the uniformity of the recurrent lesion. Relationship of surgical repair to the basic anatomy of the sacrococcygeal area is emphasized as a requirement for success in primary closure of these wounds. 6. 6. It was demonstrated that haphazard technics of operation and postoperative management resulted in prolonged hospitalization of many of our patients. In the second half of the series, operation and management of these cases was standardized under the care of three surgeons with resultant reduction in healing time in each type of case. 7. 7. Patients amenable to primary closure were operated upon under procaine-epinephrine local anesthesia. The infected cyst and sinus was carefully excised and the wound was closed with fine alloy steel approximating sutures reinforced by through-and-through tension sutures of heavier wire tied over gauze rolls. Only five of fifty patients so treated required more than three weeks for complete epithelialization. The average healing time for all fifty patients was two and one-half weeks. 8. 8. Cases necessitating wide excisions were partially closed by undermining the skin at the wound margins and suturing these to the post-sacral fascia, thereby minimizing the wound which is then allowed to heal by granulation. 9. 9. Acute abscesses were drained on admission. Revision operation three days later consisted of marsupialization of the wound by saucerizing the margins thereof. Granulations in the base of the wound were curetted and healing allowed to proceed by granulation. 10. 10. Recurrent lesions were explored after exposure, granulations were curetted and wound edges saucerized. As a rule, these healed poorly for two reasons: (1) depth of the lesion especially in the upright position prevented adequate drainage; (2) chronicity of the lesion resulted in marked fibrosis in the wound bed with consequent embarrassment of adequate vascularity. In recent sluggish cases, the wound was excised providing a fresh clean wound. A split thickness skin graft was removed from the lumbar back and sutured onto the fresh wound. A pressure dressing maintained the graft. This procedure has afforded gratifying results in several recalcitrant cases. 11. 11. In postoperative granulating wounds, meticulous and daily wound toilet is necessary to attain healthy granulations and early epithelialization.