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PubMed2004

Microbiological examination of infected dental root canals.

OBJECTIVES: The aim of this study was to investigate the root canal microbiota of primary and secondary root-infected canals and the association of constituent species with specific endodontic signs and symptoms. METHODS: Microbial samples were taken from 60 root canals, 41 with necrotic pulp tissues (primary infection) and 19 with failed endodontic treatment (secondary infection). Strict anaerobic techniques were used for serial dilution, plating, incubation and identification. RESULTS: A total of 224 cultivable isolates were recovered belonging to 56 different bacterial species. Individual root canals yielded a maximum of 10 bacterial species. Of the bacterial isolates, 70% were either strict anaerobes or microphilic. The anaerobes most frequently isolated were: Peptostreptococcus micros (35%), Fusobacterium necrophorum (23.3%), Fusobacterium nucleatum (11.7%), Prevotella intermedia/nigrescens (16.7%), Porphyromonas gingivalis (6.7%) and Porphyromonas endodontalis (5%). The root canal microflora of untreated teeth with apical periodontitis was found to be mixed, comprising gram-negative and gram-positive and mostly anaerobic microorganisms and usually containing more than 3 species per canal. On the other hand, facultative anaerobic and gram-positive bacteria predominated in canals with failed endodontic treatment, which harbored 1-2 species per canal. Suggested relationships were found between anaerobes, especially gram-negatives, and the presence or history of pain, tenderness to percussion and swelling (P<0.05). In particular, associations were found between: a) pain (n=29) and P. micros (P<0.01), P. intermedia/nigrescens and Eubacterium spp. (both P<0.05); b) history of pain (n=31) and P. micros (P<0.01) Porphyromonas and Fusobacterium spp. (P<0.05); c) tenderness to percussion (n=29) and Porphyromonas spp. (P<0.01), Peptostreptococcus and Fusobacterium spp. (P<0.001); d) swelling (n=20) and Peptostreptococcus spp. (P<0.01), Porphyromonas and Enterococcus spp. (P<0.05); e) wet canals (n=33) and Porphyromonas and Fusobacterium spp. (P<0.05); f) purulent exudate (n=20) and Porphyromonas, Peptostreptococcus and Fusobacterium spp. (P<0.05); previous endodontic treatment and Enterococcus faecalis, Streptococcus spp., P. micros, F. necrophorum (P<0.05). CONCLUSIONS: Our findings indicate potential complex interactions of species resulting in characteristic clinical pictures which cannot be achieved by individual species alone. They also indicate that the microbiota of primary infected canals with apical periodontitis differs in number and in species from the secondary infected canals by using the culture technique.

Bacteria, Anaerobic↗

PubMed1979

Estimation of potassium recirculation in tomato plants by comparison of the rates of potassium and calcium accumulation in the tops with their fluxes in the xylem stream.

A procedure to estimate the extent of K recirculation in plants is proposed. This is based on the ratio of the upward fluxes of K to Ca in the xylem sap from root to shoot with the ratio of K to Ca accumulation in plant tops.In a preliminary investigation the factors influencing the K to Ca ratio in the xylem sap were considered. Tomato plants were grown at three levels of K nutrition and harvested at different times during the 24-hour day period. It was shown that the K to Ca ratio in xylem sap changed dramatically depending on the time of sap collection after decapitation, the values falling from over 2 to less than unity over the 4-hour period of collection. Diurnal effects on exudation were less marked but also of significance. The level of K nutrition was of little importance. It is suggested that a representative xylem sap from tomato plants can best be obtained from samples taken between 15 and 60 minutes after decapitation.In a second experiment K recirculation was estimated. At nine harvesting stages over a 24-hour period the K to Ca ratio in the xylem sap was invariably higher than the K to Ca ratio of accumulation in the tops over the same period. From this information it was calculated that about 20% of the upward flux of K in the xylem stream resulted from recirculated K.

Journal Article↗

PubMed2002

Hydraulic lift in Acacia tortilis trees on an East African savanna.

Recent studies suggest that savanna trees in semi-arid areas can increase understorey plant production. We hypothesized that one of the mechanisms that explains the facilitation between trees and grasses in East African savannas is hydraulic lift (HL). HL in large Acacia tortilis trees was studied during the first 3 months of the dry season during a relatively wet year (1998) and a very dry year (2000). In 1998, we found distinct diel fluctuation in soil water potential (psi(s)), with increasing values during the night and decreasing again the following day. These fluctuations in psi(s )are consistent with other observations of HL and in A. tortilis were found up to 10 m from the tree. In 2000, during a severe drought, psi(s) measurements indicated that HL was largely absent. The finding that HL occurred in wetter years and not in drier years was supported by data obtained on the delta(18)O values in soil, rain and groundwater. The delta(18)O of water extracted from the xylem water of grasses indicated that when they grew near trees they had values similar to those of groundwater. This could be because they either (1) use water from deeper soil layers or (2) use hydraulically lifted water provided by the tree; this was not seen in the same grass species growing outside tree canopies. While our data indicate that HL indeed occurs under Acacia trees, it is also true that psi(s) was consistently lower under trees when compared to outside tree canopies. We believe that this is because tree-grass mixtures take up more water from the upper soil layers than is exuded by the tree each night. This limits the beneficial effect of HL for understorey grasses and suggests that in savannas both facilitation via HL and competition are active processes. The importance of each process may depend upon how wet or dry that particular site or year is.

Acacia↗

PubMed1988

Acute pulpal-alveolar cellulitis syndrome. IV. Exacerbations during endodontic treatment. Part 3. A case report.

An asymptomatic abscessed maxillary premolar, which had undergone previous endodontic treatment, was retreated. The initial attempt to remove the silver cone seal was unsuccessful. Early the next morning, the patient appeared with a severe cellulitis exacerbation. The silver cone was now loose: a lateral "blowout." Specific cultures of the silver cone and exudate revealed three aerobic microbes: a Streptococcus sp and two obligate Pseudomonas spp. Anaerobes were shown to be absent with anaerobic subcultures. This case would appear to substantiate the alteration of the tissue oxidation-reduction potential as the major factor in endodontic cellulitis exacerbations, as previously reported.

Abscess↗

PubMed1997

A species-specific recognition system directs haustorium development in the parasitic plant Triphysaria (Scrophulariaceae).

Parasitic plants use host molecules to trigger development programs essential for parasitism. One such program governs the initiation, development, and function of haustoria, parasite-specific organs responsible for attachment and invasion of host tissues. Haustoria development can be initiated by several different molecules produced by appropriate host species. We are interested in understanding how these signals are interpreted by two related facultative parasites, Triphysaria eriantha (Benth). Chuang and Heckard, and T. versicolor Fischer and C. Meyer, to distinguish their own roots from those of potential hosts. We used an in vitro bioassay to determine what proportion of different Triphysaria populations formed haustoria in the presence and absence of closely related and unrelated host species. We found that the proportion of plants with haustoria was the same whether the plants were grown in isolation or with a conspecific host. In contrast, a significantly higher proportion of plants made haustoria when the host was a congeneric Triphysaria. Plants with haustoria neither enhanced nor inhibited other plants' propensity to form haustoria. Together these results indicate that qualitative differences exist in haustorium-inducing factors exuded by closely related species. The highest proportion of Triphysaria had haustoria when growth with Arabidopsis thaliana (L.) Heynh. Even in this case, however, some Triphysaria failed to develop haustoria. Interestingly, the percentage of haustoria that had vessel elements was higher when connections were made with Arabidopsis than with another Triphysaria. These results demonstrate that host recognition can be manifested at multiple points in haustorium development.

Arabidopsis↗

PubMed1981

Synthesis, Storage, and Utilization of Amino Compounds in White Lupin (Lupinus albus L.).

Changes in total N and in free amino compounds were followed during growth of nodulated white lupin. Leaflets contained the greatest fraction of plant N but had lower proportions (1 to 4%) of their N in soluble amino form than stem + petioles (10 to 27%) and reproductive parts (15 to 33%). Mobilization of free amino compounds from plant parts to fruits contributed at most only 7% of the total N intake of fruits, compared with 50% in mobilization of other forms of N and 43% from fixation during fruiting. Asparagine was usually the most abundant free amino compound in plant parts, followed by glutamine and alanine. Valine, glycine, isoleucine, aspartic acid and gamma-aminobutyric acid comprised the bulk of the remaining soluble amino N. Composition of tissue pools of amino-N closely resembled that of xylem and phloem exudates. Data on N flow and utilization were combined with information on composition of transport fluids to quantify syntheses, exchanges, and consumptions of asparagine, glutamine, aspartic acid, and valine by organs of the 51- to 58-day plant. These amino compounds carried 56, 29, 5, and 2%, respectively, of the N exported from nodules and contributed in roughly commensurate proportions to transport exchanges and N increments of plant parts. There were, however, more than expected involvements of glutamine and valine in mobilization of N from lower leaves, of asparagine in xylem to phloem transfer, and of aspartic acid in cycling of N through the root, and there was a less than expected participation of aspartic acid in xylem to phloem transfer and in phloem translocation to the shoot apex. The significance of these differences is discussed.

Journal Article↗

PubMed1999

Seed germination patterns in green dragon (Arisaema dracontium, Araceae).

Arisaema dracontium (green dragon) is a perennial herb that is widely distributed in eastern North America. However, in Canada, at the northern edge of its distribution, the species is designated as "vulnerable" with respect to conservation status. In natural populations, seedlings are uncommon; the present study was undertaken in order to characterize seed and seedling properties in green dragon. Seeds were sampled from five sites, ranging from Ontario at the northern limit of the distribution range, to Louisiana in the south. Seed germinability ranged from 25 to 55%, depending upon source. Experiments indicated that neither the hard seed coat nor a water-soluble exudate from the seed was responsible for inducing or maintaining dormancy. Patterns of seed germination appear to reflect general climatic conditions at the sites where seeds had originated. Cold stratification at 3°C produced significantly greater relative germinability in all seed collections except the most southerly one, from Baton Rouge. These seeds also had a slower overall speed of germination. In contrast, germination of seeds from the most northerly site was promoted by cold stratification and occurred over a relatively brief period. Germination in alternating light and dark conditions decreased the speed of germination compared to germination in the dark, however exposure to light changed the phenology of germination by promoting development of adventitious roots and primary leaves in these seedlings.

Journal Article↗

PubMed2000

Zinc deficiency-induced phytosiderophore release by the Triticaceae is not consistently expressed in solution culture.

The effects of zinc (Zn) and iron (Fe) deficiencies on phytosiderophore (PS) exudation by three barley (Hordeum vulgare L.) cultivars differing in Zn efficiency were assessed using chelator-buffered nutrient solutions. A similar study was carried out with four wheat (Triticum aestivum L. and T. durum Desf.) cultivars, including the Zn-efficient Aroona and Zn-inefficient Durati. Despite severe Zn deficiency, none of the barley or wheat cultivars studied exhibited significantly elevated PS release rates, although there was significantly enhanced PS exudation under Fe deficiency. Aroona and Durati wheats were grown in a further study of the effects of phosphate (P) supply on PS release, using 100 microM KH2PO4 as high P, or solid hydroxyapatite as a supply of low-release P. Phytosiderophore exudation was not increased due to P treatment under control or Zn-deficient conditions, but was increased by Fe deficiency. Accumulation of P in shoots of Zn- and Fe-deficient plants was seen in both P treatments, somewhat more so under the KH2PO4 treatment. Zinc-efficient wheats and grasses have been previously shown to exude more PS under Zn deficiency than Zn-inefficient genotypes. We did not observe Zn-deficiency-induced PS release and were unable to replicate the results of previous researchers. The tendency for Zn deficiency to induce PS release seems to be method dependent, and we suggest that all reported instances may be explained by an induced physiological deficiency of Fe.

Cells, Cultured↗

PubMed1976

Electrochemical gradients and k and cl fluxes in excised corn roots.

The compartmental analysis method was used to estimate the K(+) and Cl(-) fluxes for cells of excised roots of Zea mays L. cv. Golden Bantam. When the measured fluxes are compared to those calculated with the Ussing-Teorell flux-ratio equation, an active inward transport of Cl(-) across the plasmalemma is indicated; the plasmalemma K(+) fluxes are not far different from those predicted for passive diffusion, although an active inward transport cannot be precluded. Whether fluxes across the tonoplast are active or passive depends upon the vacuolar potential which is unknown. Assuming no electropotential gradient, the tracer flux ratios are fairly close to those predicted for passive movement. However, if the vacuole is positive by about 10 millivolts relative to the cytoplasm, the data suggest active inward transport for K(+) and outward transport for Cl(-).Fluxes to the xylem exudate were found to be more accurately estimated from the specific radioactivity of the cytoplasm (symplasm) than from the external solution specific radioactivity. The electrochemical gradients for K(+) and Cl(-) between the xylem vessels and the surrounding stelar parenchyma indicate active K(+) and passive Cl(-) movement into the vessels. The data are interpreted as being in accord with radial transport through the symplast into living vessels.

Journal Article↗

PubMed1982

Neutrophil response and function during acute cytomegalovirus infection in guinea pigs.

The mobilization and functional characteristics of polymorphonuclear leukocytes (PMNs) at the site of an inflammatory stimulus were studied during acute cytomegalovirus infection in guinea pigs. Weanling Hartley strain guinea pigs were inoculated subcutaneously with approximately 10(6) 50% tissue culture infective doses of virulent salivary gland-passaged guinea pig cytomegalovirus. The virus was uniformly present in bone marrow, buffy coat, and casein-elicited peritoneal exudate cells 5 to 7 days after the inoculation. The mean numbers of circulating PMNs in the animals were 2,862/microliters in uninfected controls and 880/microliters in infected animals. The total peritoneal PMNs recovered 14 h after casein injection were 491 X 10(6) and 237 X 10(6) in control and infected animals, respectively. The number of 50% tissue culture infective doses of guinea pig cytomegalovirus per 10(6) purified peritoneal PMNs was 10(2.17). Neutrophil O2 consumption was similar in infected and control animals in response to either stimulation by a neutrophil activator, phorbol myristate acetate, or phagocytosis of Staphylococcus aureus. However, the maximal rate of H2O2 release and the percent killing of S. aureus by peritoneal exudate cells from infected animals were significantly reduced compared with uninfected controls during acute infection. Granulocytopenia, a decreased mobilization of PMNs to the site of the inflammatory stimulus, a diminished cellular release of H2O2 in response to a bacterial stimulus, and a modest reduction in bacterial killing were demonstrated during experimental acute cytomegalovirus infection. Such reductions in granulocyte number and function at inflammatory sites during this type of infection could alter antimicrobial defenses.

Animals↗

PubMed2003

In situ localization associates biologically active plant natriuretic peptide immuno-analogues with conductive tissue and stomata.

Plant natriuretic peptide immuno-analogues (irPNP) have previously been shown to affect a number of biological processes including stomatal guard cell movements, ion fluxes and osmoticum-dependent water transport. Tissue printing and immunofluorescent labelling techniques have been used here to study the tissue and cellular localization of irPNP in ivy (Hedera helix L.) and potato (Solanum tuberosum L.). Polyclonal antibodies active against human atrial natriuretic peptide (anti-hANP) and antibodies against irPNP from potato (anti-StPNP) were used for immunolabelling. Tissue prints revealed that immunoreactants are concentrated in vascular tissues of leaves, petioles and stems. Phloem-associated cells, xylem cells and parenchymatic xylem cells showed the strongest immunoreaction. Immunofluorescent microscopy with fluorescein isothiocyanate (FITC)-conjugated goat anti-rabbit IgG supported this finding and, furthermore, revealed strong labelling to stomatal guard cells and the adjacent apoplastic space as well. Biologically active immunoreactants were also detected in xylem exudates of a soft South African perennial forest sage (Plectranthus ciliatus E. Mey ex Benth.) thus strengthening the evidence for a systemic role of the protein. In summary, in situ cellular localization is consistent with physiological responses elicited by irPNPs reported previously and is indicative of a systemic role in plant homeostasis.

Amino Acid Sequence↗

PubMed1980

Evaluation of the Relative Ureide Content of Xylem Sap as an Indicator of N(2) Fixation in Soybeans: GREENHOUSE STUDIES.

The use of the relative ureide content of xylem sap [(ureide-N/total N) x 100] as an indicator of N(2) fixation in soybeans (Merr.) was examined under greenhouse conditions. Acetylene treatments to inhibit N(2) fixation were imposed upon the root systems of plants totally dependent upon N(2) fixation as their source of N and of plants dependent upon both N(2) fixation and uptake of exogenous nitrate. Significant decreases in the total N concentration of xylem sap from plants of the former type were observed, but no significant decrease was observed in the total N concentration of sap from the latter type of plants. In both types of plants, acetylene treatment caused significant decreases in the relative ureide content of xylem sap. The results provided further support for a link between the presence of ureides in the xylem and the occurrence of N(2) fixation in soybeans. The relative ureide content of xylem sap from plants totally dependent upon N(2) fixation was shown to be insensitive to changes in the exudation rate and total N concentration of xylem sap brought about by diurnal changes in environmental factors. There was little evidence of soybean cultivars or nodulating strains affecting the relative ureide content of xylem sap. ;Ransom' soybeans nodulated with Rhizobium japonicum strain USDA 110 were grown under conditions to obtain plants exhibiting a wide range of dependency upon N(2) fixation. The relative ureide content of xylem sap was shown to indicate reliably the N(2) fixation of these plants during vegetative growth using a (15)N method to measure N(2) fixation activity. The use of the relative ureide content of xylem sap for quantification of N(2) fixation in soybeans should be evaluated further.

Journal Article↗

PubMed2002

Cellular mechanisms for heavy metal detoxification and tolerance.

Heavy metals such as Cu and Zn are essential for normal plant growth, although elevated concentrations of both essential and non-essential metals can result in growth inhibition and toxicity symptoms. Plants possess a range of potential cellular mechanisms that may be involved in the detoxification of heavy metals and thus tolerance to metal stress. These include roles for the following: for mycorrhiza and for binding to cell wall and extracellular exudates; for reduced uptake or efflux pumping of metals at the plasma membrane; for chelation of metals in the cytosol by peptides such as phytochelatins; for the repair of stress-damaged proteins; and for the compartmentation of metals in the vacuole by tonoplast-located transporters. This review provides a broad overview of the evidence for an involvement of each mechanism in heavy metal detoxification and tolerance.

Adaptation, Physiological↗

PubMed2004

Tetracycline conditioning augments the in vivo inflammatory response induced by cementum extracts.

BACKGROUND: Studies have shown that extracts of cementum from periodontally involved teeth stimulated cytokine secretion from cultured human monocytes and that this stimulatory effect is inhibited by conditioning of the cementum with tetracycline. Using the subcutaneous chamber model in mice, the present study was designed to test the ability of cementum extracts from periodontally diseased teeth to induce an inflammatory response in vivo and to evaluate the effect of cementum conditioning with tetracycline. METHODS: Subcutaneous chambers were implanted in 24 mice. Two weeks later, the animals received intrachamber injection of one of the following: diseased-cementum extract, healthy-cementum extract, diseased-cementum extract preconditioned with tetracycline, or medium alone. Chamber exudates were harvested and analyzed for leukocyte levels, tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, and interleukin-10 (IL-10). RESULTS: Injection of healthy- or diseased-cementum extracts increased the intrachamber levels of leukocytes. Extracts of diseased cementum were found to significantly increase the levels of TNF-alpha, IFN-gamma, and IL-10, compared with extracts of healthy cementum or media alone. Peak cytokine levels were observed 2 hours postinjection. Conditioning of diseased cementum with tetracycline before extraction resulted in augmented levels of TNF-alpha and IFN-gamma, and reduced levels of IL-10, compared with untreated diseased cementum. CONCLUSIONS: The present results demonstrate that conditioning of diseased cementum with tetracycline may induce an intense inflammatory response in a mouse model, and they suggest that local application of tetracycline for root conditioning should be carefully reinvestigated.

Analysis of Variance↗

PubMed1980

Pathologic study of periapical lesions 1. Periapical granulomas: clinical, histopathologic and immunohistopathologic studies.

Seventy periapical granulomas were histopathologically examined. They were divided into four types: exudative, granulomatous, granulo-fibrous, and fibrous types. Clinicopathologically, those having marked lymphocytic infiltration were found more frequently in cases having had endodontic treatment; further, the size of a radiolucent area did not exceed that of the involved tooth crown. In contrast, a predominant plasma cell infiltrate was more frequent in cases with open pulp chambers (no treatment). In those cases, the radiolucent area was larger than the crown. Foci with very large radiolucent areas were often of the exudative type. Epithelial proliferation was more frequent in cases without treatment. These findings indicate that endodontic treatment not only stops invasion of injurious factors but also proliferation of epithelium. Furthermore, in frozen sections of 26 granulomas, IgE-containing cells and IgG and C3 fluorescence in the connective tissue were often observed. It appears that IgE-mediated reaction and antigen-antibody complexes may play a role in periapical pathosis.

Adolescent↗

PubMed2002

The rolB-like part of the Agrobacterium rhizogenes orf8 gene inhibits sucrose export in tobacco.

Many Agrobacterium T-DNA genes belong to the highly diverse rolB family. The mode of action of most of these genes is still unknown. rolB-like sequences also are present at the 5' ends of the T-DNA-located iaaM genes and the iaaM homolog orf8, whereas iaaM genes from Pseudomonas and Erwinia spp. lack such sequences. iaaM genes encode tryptophan monooxygenases; these enzymes convert tryptophan into indole-3-acetamide, a precursor of indole-3-acetic acid. Tobacco plants expressing the rolB-like part of the A4 orf8 gene (2x35S-A4-Norf8 plants) accumulate glucose, fructose, sucrose, and starch and resemble sucrose transporter (NtSUT1) antisense plants. Different lines of evidence indicate that 2x35S-A4-Norf8 plants export less sucrose from source leaves. Glucose, fructose, sucrose, and starch accumulate in source leaves during sink-source transition, whereas sink tissues like petioles and midveins contain lower levels than normal. Petiole exudation experiments demonstrate a significant decrease in export of label after 14C-sucrose infiltration and after 14CO2 labeling. Grafting of stunted homozygous 2x35S-A4-Norf8 plants onto wild-type rootstocks restores growth, indicating that unloading is not affected. Growth of 2x35S-A4-Norf8 seedlings is inhibited on naphthalene acetic acid-containing media, suggesting a link between sucrose transport and auxin sensitivity.

Bacterial Proteins↗

PubMed2003

Repair of perforating internal resorption with mineral trioxide aggregate: a case report.

A case of internal resorption with buccal perforation was found in a maxillary central incisor. Because of the extensive lesion and continuous exudation, surgical intervention was used. The apical third was obturated with gutta-percha, and the perforated lesion was repaired with mineral trioxide aggregate. The residual canal space was filled by thermoplasticized gutta-percha technique, and the coronal cavity was restored with composite resin. The symptoms and signs ceased, and the results were satisfactory at 1-year follow-up.

Adult↗

PubMedDate not supplied

Study of the inducer effect of molasses and soybean cake on synthesis and excretion of nodulation factors in different strains of Bradyrhizobium japonicum.

It is known that the synthesis of nodulation factors by the bacteria within the genera Rhizobium is induced by different compounds, mainly of flavonoid nature exudated by the legume plants. The capacity of different compounds to act as inducers of nod genes on three Bradyrhizobium japonicum strains was studied in this paper and this effect was compared using two concentrations of the inducer. Induced Nod factors were observed among the strains exposed to the inducers. The profiles and amount of induced Nod factors depend on the type and concentration of the inducer, and the strains.

Bacterial Proteins↗