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At least 91 records · Page 5Linked to original sources
PubMed2004

Effects of Photosystem II inhibiting herbicides on mangroves--preliminary toxicology trials.

Mangroves are sensitive to the root application of Photosystem II inhibiting herbicides and Avicennia marina is more sensitive than other mangroves tested. Seedlings of four mangrove species, including two salt-excreting species (A. marina and Aegiceras corniculatum) and two salt-excluding species (Rhizophora stylosa and Ceriops australis) were treated with a range of concentrations of the herbicides diuron, ametryn and atrazine. Assessment of responses required the separation of seedlings into two groups: those that had only their roots exposed to the herbicides through the water (A. marina and R. stylosa) and those that had both roots and leaves exposed to herbicides through the water (A. corniculatum and C. australis). Salt-excreting species in each group were more susceptible to all herbicide treatments than salt-excluding species, indicating that root physiology was a major factor in the uptake of toxic pollutants in mangroves. Submergence of leaves appeared to facilitate herbicide uptake, having serious implications for seedling recruitment in the field. Each herbicide was ranked by its toxicity to mangrove seedlings from most damaging to least effective, with diuron>ametryn>atrazine. The relative sensitivity of A. marina found in these pot trials was consistent with the observed sensitivity of this species in the field, notably where severe dieback had specifically affected A. marina in the Mackay region, north eastern Australia.

Adaptation, Physiological↗
PubMed1982

The LDL receptor defect in familial hypercholesterolemia. Implications for pathogenesis and therapy.

Familial hypercholesterolemia results from one of several genetic defects in a cell surface receptor that normally controls the degradation of low density lipoprotein. The clinical and genetic features and the pathophysiology of these defects are discussed. Knowledge of the regulation of LDL receptors in the liver can be exploited in the design of a physiologically rooted therapy for familial hypercholesterolemia.

Cells, Cultured↗
PubMed1996

Review on tropical root and tuber crops. II. Physiological disorders in freshly stored roots and tubers.

Tropical root and tubers, including cassava, sweet potato, yams and aroids, have been reported to show an increase in respiratory activity after harvest and injury and subsequent storage in association with their deterioration. This leads to loss of water and carbohydrate. Cassava roots often show discoloration of the tissue with development of pigments in the xylem vessels (vascular streaking or primary/physiological deterioration). This has been established to be enzymatic in nature. Pruning the cassava stem, leaving about a 20- to 30-cm stub prior to harvest, could delay the onset of primary deterioration. Sweet potato roots and yam tubers show a peak respiratory activity immediately or 1 d after harvest. The respiratory rate, however, declines during the subsequent storage period. Yam tubers show a further increase in respiratory activity at the breakage of dormancy occurring at the time of sprouting. Dormancy in yam tubers has been studied in some detail. Different species of yams vary in their dormancy period, a major factor that accounts for the variation in their storage life. Little information is available on the dormancy of sweet potato and aroids. Tropical roots and tubers exhibit "chilling injury" when stored at temperatures below a critical level. The critical cold-storage temperatures range between 10 and 15 degrees C for different tropical root and tuber crops.

Carbohydrates↗
PubMed1996

Effects of the argon laser on primary tooth pulpotomies in swine.

This study evaluated the clinical, radiographic, and histologic effects of the HGM PC Oralase argon laser on vital pulps of swine teeth. Pulpotomies were performed in vivo on 42 primary teeth from three young pigs and observed for 7 or 60 days. For each time period nine experimental teeth received an argon laser dose of 1 W, 2 sec (24.88 J/cm2), and nine experimental teeth received a dose of 2 W, 2 sec (49.74 J/cm2). Controls consisted of three teeth for each time period and did not receive exposure from the argon laser. There were no significant differences noted between the two energy densities with respect to clinical, radiographic, or histological parameters for either time period. All soft tissues remained normal and all teeth exhibited normal mobility at weekly assessments. Other than physiologic root resorption, there were no differences in pre- and postoperative radiographs in the 7 day sample; calcifications coinciding to dentinal bridges were visible radiographically in 8 of the 60-day samples. Reparative dentin formation was noted histologically in a total of 9 roots in the 7-day group and in 13 roots in the 60-day group. With the exception of teeth which had early restoration loss with resultant bacterial contamination, all other pulps appeared to retain their vitality and capability of normal pulpal healing. Use of the argon laser at the parameters described in this study did not appear to be detrimental to pulpal tissues.

Animals↗
PubMed1992

Immunocytochemical localization of cathepsins B and G in odontoclasts of human deciduous teeth.

For clarification of the mechanisms by which odontoclasts resorb deciduous teeth during physiological root resorption, cysteine-proteinases such as cathepsins B and G were immunocytochemically localized in odontoclasts at the ultrastructural level. Extracted human deciduous teeth undergoing root resorption were fixed with a mixture of formaldehyde and glutaraldehyde and processed for immunocytochemical detection of these enzymes. Sheep antisera, raised against either human cathepsin B or G, were used as primary antibodies. In odontoclasts, specific immunogold labeling of both anti-cathepsin B and G was clearly localized in lysosomes and pale vacuoles of various sizes, and in a portion of the extracellular canals of odontoclastic ruffled borders. In the presence of either antibody, the cytoplasmic matrix, mitochondria, and nuclei were minimally labeled by immunogold particles. The presence of these proteolytic enzymes in odontoclasts suggests that, during odontoclastic root resorption, these enzymes are involved in the formation of resorption lacunae by means of intra/extracellular degradation of collagen and other non-collagenous matrix proteins of deciduous teeth.

Cathepsin B↗
PubMed1998

Class II MHC antigen-expressing cells in the pulp tissue of human deciduous teeth prior to shedding.

The distribution and ultrastructure of the class II major histocompatibility complex (MHC) antigen-expressing cells in the pulp tissue of human deciduous teeth during the process of physiological root resorption was surveyed by histochemical and immunocytochemical methods using an anti-human leukocyte antigen (HLA)-DR-monoclonal antibody. Dental pulp was found to contain numerous HLA-DR-positive cells of various shapes; those showing a dendritic appearance were located mainly in the periphery of the pulp tissue, associated closely with the odontoblasts. The immunopositive cells sometimes extended their cytoplasmic processes into the dentinal tubules and increased in number in the areas affected by dental caries, attrition or restorative procedures, implicating their role in immunosurveillance. The immunopositive cells were located consistently at the pulp-dentin border during the stage of active resorption, adjacent to the preodontoclasts or odontoclasts, and covered the exposed dentin surface after the detachment of the odontoclasts until the onset of cementum formation. These data suggest that the HLA-DR-immunopositive cells in the coronal pulp of human deciduous teeth play an inductive role in the differentiation, migration and/or activation of the odontoclasts and cementoblast-like cells during the stages of tooth resorption.

Dental Pulp↗
PubMed1978

Traumatized primary anterior teeth. Prognosis related to calcific reactions in the pulp cavity.

The frequency of a complicating pulp necrosis and the process of the physiologic root resorption were studied in traumatized primary teeth exhibiting partial or total pulp obliteration. The material comprised 88 incisors in 72 children aged 0.7--5.7 years (mean 2.9 years) at the time of injury. Trauma had resulted either in subluxation (25 teeth), or luxation (13 teeth), whereas the type of injury was unknown in 50 teeth. All cases were observed until eruption of the permanent incisors. Forty-four teeth initially displayed a reversible greyish color. The ultimate finding observed in all teeth was, however, varying degrees of yellow discoloration. Periapical pathologic findings indicative of pulp necrosis were observed in 9 teeth, from 1.6--4 years (mean 3 years) after the time of injury. Extraction was performed immediately, and none of the successional teeth showed developmental disturbances. The process of root resorption was classified as normal in all primary teeth. Subsequent eruption of the permanent successors occurred without any registered complications.

Child, Preschool↗
PubMed1989

[Studies on factors causing tooth resorption. 1. Role of prostaglandins as a chemical mediator on resorption of deciduous teeth in rabbits].

The aim of this study was to investigate the effects in the administration of indomethacin which is a specific inhibitor of prostaglandins (PGs) in order to understand the role of PGs in physiologic root resorption. For this study, 24 young rabbits aged 7 days which had been in utero for 31-32 days were used. The experimental group (N = 12) was injected with 5.0 mg/kg indomethacin every 12 h, and the control group (N = 12) was injected with normal saline solution every 12 h. 4 animals of each group were sacrificed at the 9th, 11th and 13th day, respectively. Their maxillary deciduous incisors embedded in paraffin were sectioned serially 7 mus in thickness. From each sample was counted the number of odontoclasts appearing on the root surface and measured the volume of the root in the maxillary deciduous incisor. The results were as follows: 1. The appearance of odontoclasts increased in a day-related manner from 9 days to 13 days on the resorption of maxillary deciduous teeth in the control and experimental rabbits. 2. The number of odontoclasts was significantly decreased by the administration of indomethacin (9 days P less than 0.05, 11 and 13 days P less than 0.01). 3. The amount of the root resorption was significantly inhibited by the administration of indomethacin at 9 days which was the initial stage of root resorption in the maxillary deciduous incisors, and then the effect of inhibition rapidly disappeared. These results strongly suggest that PGs can possibly act as a chemical mediator of odontoclastic root resorption occurred during tooth exchange.

Animals↗
PubMed1989

[Studies on factors causing tooth resorption. 2. Dose-response effects of indomethacin on resorption of deciduous teeth in rabbits].

The aim of the present study was to confirm whether prostaglandin (PGs) had any connection with physiological root resorption. 16 young rabbits aged 7 days which had been in utero for 32 days were used and were divided into 4 groups. The control group was injected with normal saline solution, and the experimental groups were injected with indomethacin, a specific inhibitor of PGs synthetase, in doses of 0.1 mg/kg, 1.0 mg/kg, 10.0 mg/kg every 12 hours for 5 days, respectively. All animals were sacricfied at 11 days postnatal. Their maxillary deciduous incisors were embedded in paraffin and sectioned serially in 7 mus thickness. The number of odontoclasts appearing on the root surface were counted, and the volume of the maxillary deciduous incisor was measured. The results were as follows: 1. The readings of the odontoclasts appearing in the control group was 260.3 +/- 60.1, and those of the experimental groups injected with 0.1 mg/kg, 1.0 mg/kg, 10.0 mg/kg indomethacin were 249.0 +/- 32.2, 199.5 +/- 15.1 (P less than 0.05 one sided test) and 163.8 +/- 40.0 (P less than 0.01), respectively. The number of odontoclasts was reduced linearly as the logarithmic dose of indomethacin increased. 2. As far as the volumes of the maxillary deciduous incisors were concerned, that of the group with 10.0 mg/kg was significantly greater than that of the group with 0.1 mg/kg (P less than 0.05). In comparison with the control and the experimental group, the volume of the 10.0 mg/kg group was greater than the others, but statistical differences were not found.

Animals↗
PubMed1995

A novel root gravitropism mutant of Arabidopsis thaliana exhibiting altered auxin physiology.

A root gravitropism mutant was isolated from the DuPont Arabidopsis thaliana T-DNA insertional mutagenesis collection. This mutant has reduced root gravitropism, hence the name rgr1. Roots of rgr1 are shorter than those of wild-type, and they have reduced lateral root formation. In addition, roots of rgr1 coil clockwise on inclined agar plates, unlike wild-type roots which grow in a wavy pattern. The rgr1 mutant has increased resistance, as measured by root elongation, to exogenously applied auxins (6-fold to indole-3-acetic acid, 3-fold to 2,4-dichlorophenoxyacetic acid, and 2-fold to napthyleneacetic acid). It is also resistant to polar auxin transport inhibitors (2-fold to triiodobenzoic acid and 3- to 5-fold to napthylphthalamic acid). The rgr1 mutant does not appear to be resistant to other plant hormone classes. When grown in the presence of 10(-7) M 2,4-dichlorophenoxyacetic acid, rgr1 roots have fewer root hairs than wild type. All these rgr1 phenotypes are Mendelian recessives. Complementation tests indicate that rgr1 is not allelic to previously characterized agravitropic or auxin-resistant mutants. The rgr1 locus was mapped using visible markers to 1.4 +/- 0.6 map units from the CH1 locus at 1-65.4. The rgr1 mutation and the T-DNA cosegregate, suggesting that rgr1 was caused by insertional gene inactivation.

Alleles↗
PubMed1999

Deformational dynamics of the aortic root: modes and physiologic determinants.

BACKGROUND: Current surgical methods for treating aortic valve and aortic root pathology vary widely, and the basis for selecting one repair or replacement alternative over another continues to evolve. More precise knowledge of the interaction between normal aortic root dynamics and aortic valve mechanics may clarify the implications of various surgical procedures on long-term valve function and durability. METHODS AND RESULTS: To investigate the role of aortic root dynamics on valve function, we studied the deformation modes of the left, right, and noncoronary aortic root regions during isovolumic contraction, ejection, isovolumic relaxation, and diastole. Radiopaque markers were implanted at the top of the 3 commissures (sinotubular ridge) and at the annular base of the 3 sinuses in 6 adult sheep. After a 1-week recovery, ECG and left ventricular and aortic pressures were recorded in conscious, sedated animals, and the 3D marker coordinates were computed from biplane videofluorograms (60 Hz). Left ventricular preload, contractility, and afterload were independently manipulated to assess the effects of changing hemodynamics on aortic root 3D dynamic deformation. The ovine aortic root undergoes complex, asymmetric deformations during the various phases of the cardiac cycle, including aortoventricular and sinotubular junction strain and aortic root elongation, compression, shear, and torsional deformation. These deformations were not homogeneous among the left, right, and noncoronary regions. Furthermore, changes in left ventricular volume, pressure, and contractility affected the degree of deformation in a nonuniform manner in the 3 regions studied, and these effects varied during isovolumic contraction, ejection, isovolumic relaxation, and diastole. CONCLUSIONS: These complex 3D aortic root deformations probably minimize aortic cusp stresses by creating optimal cusp loading conditions and minimizing transvalvular turbulence. Aortic valve repair techniques or methods of replacement using unstented autograft, allograft, or xenograft tissue valves that best preserve this normal pattern of aortic root dynamics should translate into a lower risk of long-term cusp deterioration.

Animals↗
PubMed1992

The effects of compression on the physiology of nerve roots.

The spinal roots connect the central and peripheral nervous systems. In doing so, the nerve roots pass through the spinal column, where they are located in narrow spaces, close to vertebrae and intervertebral discs. At these locations, nerve roots can be subjected to mechanical compression in association with, for example, disc herniation, spinal stenosis and spine trauma. In this article, basic aspects of the anatomy and physiology of nerve roots are reviewed. Nerve fiber arrangements, connective tissue layers and blood supply are described. The effects of compression on nerve root structure and function are summarized, based on experimental studies involving analyses of nerve function, nutrition, including blood flow, and edema formation in the nerve root. Pain mechanisms in nerve root compression are reviewed in relation to various clinical conditions.

Humans↗
PubMed2003

Colonization of flax roots and early physiological responses of flax cells inoculated with pathogenic and nonpathogenic strains of Fusarium oxysporum.

Fusarium oxysporum includes nonpathogenic strains and pathogenic strains that can induce necrosis or tracheomycosis in plants. The objective of this study was to compare the abilities of a pathogenic strain (Foln3) and a nonpathogenic strain (Fo47) to colonize flax roots and to induce early physiological responses in flax cell culture suspensions. Both strains colonized the outer cortex of the root; however, plant defense reactions, i.e., the presence of wall appositions, osmiophilic material, and collapsed cells, were less frequent and less intense in a root colonized by Foln3 than by Fo47. Early physiological responses were measured in flax cell suspensions confronted with germinated microconidia of both strains. Both pathogenic (Foln3) and nonpathogenic strains (Fo47) triggered transient H(2)O(2) production in the first few minutes of the interaction, but the nonpathogenic strain also induced a second burst 3 h postinoculation. Ca(2+) influx was more intense in cells inoculated with Fo47 than in cells inoculated with Foln3. Similarly, alkalinization of the extracellular medium was higher with Fo47 than with Foln3. Inoculation of the fungi into flax cell suspensions induced cell death 10 to 20 h postinoculation, with a higher percentage of dead cells observed with Fo47 than with Foln3 beginning at 14 h. This is the first report showing that early physiological responses of flax cells can be used to distinguish pathogenic and nonpathogenic strains of the soil-borne fungus F. oxysporum.

Calcium↗
PubMedDate not supplied

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

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

Journal Article↗
PubMed1982

Physiological significance of Root effect hemoglobins in trout.

Root effect hemoglobins are found in trout and salmon. These functionally unique hemoglobins are believed to be intricately involved in oxygen secretion to the swimbladders of many fishes. This has also been proposed as their primary physiological role in trout; however, such an oxygen secretory function is unlikely in these fish. Trout swimbladders characteristically contain very high concentrations of nitrogen and the anatomical structures associated with swimbladder gas secretion are absent from trout. Also, trout appear to fill their swimbladders by physical deposition of gas, with the following of surface air, rather than by chemical secretion, thus obviating a role of Root effect hemoglobins at the swimbladder. A chemical secretion of gas is likely involved in oxygen secretion to the eye. The eyes of trout, as those of many fishes, contain very high concentrations of oxygen which exceed those found in the blood or ambient water. Data are consistent with a physiological role of trout Root effect hemoglobins in oxygen secretion to the eye; they are not consistent with a role in any gaseous secretion to the swimbladder.

Air Sacs↗
PubMedDate not supplied

Seminal, adventitious and lateral root growth and physiological responses in rice to upland conditions.

Understanding the growth and physiological responses of rice to upland conditions would be helpful for designing treatments to improve the tolerance of rice under a rainfed system. The objective of this study was to investigate the initiation,elongation and membrane stability of seminal, lateral and adventitious roots of upland rice after 9-d upland condition treatment. Compared with control roots under waterlogged conditions, upland water deficiency conditions favor seminal and lateral root growth over adventitious root growth by accelerating seminal root elongation, promoting lateral root initiation and elongation, and reducing the elongation and number of adventitious roots. Enhanced total root number and length resulted in increase of total root dry weight and thereby increasing the root-to-shoot ratio. Organic compound leakage from seminal root tips and adventitious roots increased progressively to some extent with upland culture duration, while significant increases in seminal root tips were the consequence of loss of membrane integrity caused by the upland-condition enhanced growth.

Adaptation, Physiological↗