The interpretation of trace element analysis in body fluids.

The clinical interpretation of trace element analysis has lagged behind the technology available to measure the elements in body fluids. Reports can be difficult to interpret and requires knowledge of toxicokinetics, the dynamics of how the trace metals accumulate and pass through the body. Trace element analysis is best used for specific applications, such as establishing levels of exposure, biological exposure indices, biomonitoring of populations, and to confirm an association following a compatible diagnosis. It is not well suited for screening individual patients. Chelation treatment may follow inappropriate trace element determinations and may carry a risk of side effects, some life-threatening. Trace element analysis should be used sparingly and with full understanding of what the results are likely to mean. The physician should only order the test with a clear idea of why he or she is doing so and what he or she will do with the result.

Cherubism: case reports and literature review.

Two new cherubism cases have been documented and reported. Both were relatively mild clinically, being a Grade I within Motamedi's I to V clinical grading system. Each presented with bilateral posterior mandibular lesions having a multiloculated radiolucent appearance. In each case, detection with eventual diagnosis evolved from a mandibular molar failing to erupt (tooth No. 19). The partial literature review documented the wide spectrum of clinical expression of this disease and the consequent wide variation in its treatment.

Macromolecular leakage beneath full cast crowns: A two-year in vitro investigation.

STATEMENT OF PROBLEM: Most microleakage studies have used low molecular weight dyes or isotopes rather than clinically relevant materials such as lipopolysaccharides (LPSs) or cell wall materials that have been shown to provoke inflammatory reactions in the dental pulp. PURPOSE: This investigation evaluated the leakage (diffusion) of fluorescently labeled LPS and dextran beneath cast-gold crowns luted with 3 cements. MATERIAL AND METHODS: Thirty extracted molars were prepared for crowns. Ten crowns with access ports (facial or lingual) were cast in gold and luted with zinc phosphate, glass ionomer, and an adhesive resin cement onto their preparations. Teeth and crowns with filters inserted into the ports were immersed in a solution of labeled macromolecules (TRITC-LPS, FITC-dextran) and evaluated for leakage every month for 24 months. Filters were retrieved and analyzed with fluorescent microscopy. RESULTS: All filters retrieved from crowns luted with zinc phosphate, glass ionomer, and adhesive resin cements demonstrated no detectable leakage and were negative for both FITC-dextran and TRITC-LPS for all evaluation periods. CONCLUSION: For the 24 months of this investigation, zinc phosphate, Ketac-Cem, and C&B-Metabond were equally effective at preventing leakage of detectable molecular concentrations of LPS and dextran to the level of the access ports.

Implant failures associated with asymptomatic endodontically treated teeth.

BACKGROUND: Endosseous root-formed implants occasionally fail to osseointegrate. Causes of failure include infection, overheating of the bone, habitual smoking, systemic disease, transmucosal overloading, excessive surgical trauma and implant placement adjacent to teeth demonstrating periapical pathology. CASE DESCRIPTION: In this article, the authors present another possible cause of implant failure. The cases of four patients who received endosseous root-formed implants are discussed. Each patient demonstrated signs of infection after initial implant placement. The common factor in each failing implant was its placement adjacent to an asymptomatic endodontically treated tooth with no clinical or radiographic evidence of pathology. CLINICAL IMPLICATIONS: These patients demonstrate the importance of evaluating and possibly retreating or extracting adjacent endodontically treated teeth before placing implants.

The need for policy and risk analysis--the Department of Energy experience.

Reduction of major risks to the public and workers is a top priority of all federal agencies. Given current and future budget realities, agencies cannot attempt to address all risks simultaneously nor to address certain relatively lower risk activities as rapidly as some would like. The assumptions and judgments inherent in using risk analysis in the absence of data, however, have to be clearly stated. What is needed is an integrated risk assessment and management process that meets the current and future needs of the government, as well as of stakeholders. Yet there have been many questions raised regarding risk assessment: our ability to define the risks on a specific substance or site basis and in a systematic way; methodology questions about identifying and assessing diverse hazards and risks as well as uncertainties in the estimates, data gaps, and concern over the quality of information; and the fact that "who" performs the risk assessment matters. Knowing these controversies surrounding risk and the use of risk-based approach, the Department of Energy (DOE) requested the National Academy of Sciences-National Research Council to determine whether and how risk and risk-based decisions could be incorporated into a major federal program, the DOE's Office of Environmental Management. The report identified the major obstacles, issues, and barriers to implementing a risk-based management approach. The report concluded that the use of risk-based approach could help compare outcomes, build consensus, and gain early public involvement to include cultural, socioeconomic, historical, and religious values, if its purposes and limitations are well defined. A status of the DOE's ability to implement the recommendations presented in the report on the use of risk assessment in a major federal program and the adoption of principles for using risk analysis will be given.

Organ-Specific and Environmentally Regulated Expression of Two Abscisic Acid-Induced Genes of Tomato : Nucleotide Sequence and Analysis of the Corresponding cDNAs.

The cDNAs, pLE4 and pLE25, represent mRNAs that accumulate in response to water deficit and elevated levels of endogenous abscisic acid in detached leaves of drought-stressed tomato (Lycopersicon esculentum Mill., cv Ailsa Craig) (A Cohen, EA Bray [1990] Planta 182: 27-33). DNA sequence analysis of pLE4 and pLE25 showed that the deduced polypeptides were 13.9 and 9.3 kilodaltons, respectively. Each polypeptide was hydrophilic, cysteine- and tryptophan-free, and found to be similar to previously identified proteins that accumulate during the late stages of embryogenesis. pLE4 and pLE25 mRNA accumulated in a similar organ-specific pattern in response to specific abiotic stresses. Yet, expression patterns of the corresponding genes in response to developmental cues were not similar. pLE25 mRNA accumulated to much higher levels in developing seeds than in drought-stressed vegetative organs. pLE4 mRNA accumulated predominantly in drought-stressed leaves. The similarities and differences in the accumulation characteristics of these two mRNAs indicates that more than one mechanism exists for the regulation of their corresponding genes.

Nucleotide sequence and spatial expression pattern of a drought- and abscisic Acid-induced gene of tomato.

The nucleotide sequence of le16, a tomato (Lycopersicon esculentum Mill.) gene induced by drought stress and regulated by abscisic acid specifically in aerial vegetative tissue, is presented. The single open reading frame contained within the gene has the capacity to encode a polypeptide of 12.7 kilodaltons and is interrupted by a small intron. The predicted polypeptide is rich in leucine, glycine, and alanine and has an isoelectric point of 8.7. The amino terminus is hydrophobic and characteristic of signal sequences that target polypeptides for export from the cytoplasm. There is homology (47.2% identity) between the amino terminus of the LE 16 polypeptide and the corresponding amino terminal domain of the maize phospholipid transfer protein. le16 was expressed in drought-stressed leaf, petiole, and stem tissue and to a much lower extent in the pericarp of mature green tomato fruit and developing seeds. No expression was detected in the pericarp of red fruit or in drought-stressed roots. Expression of le16 was also induced in leaf tissue by a variety of other abiotic stresses including polyethylene glycol-mediated water deficit, salinity, cold stress, and heat stress. None of these stresses or direct applications of abscisic acid induced the expression of le16 in the roots of the same plants. The unique expression characteristics of this gene indicates that novel regulatory mechanisms, in addition to endogenous abscisic acid, are involved in controlling gene expression.