Medico-legal aspects of dental treatment of the ageing and aged patient.

The medico-legal aspects of the dental management of ageing and aged patients relate mainly to the assessment of the patient's competence and the role of substitute decision makers. Dentists will assess whether or not a patient is competent to give informed consent to treatment. Lawyers use the word 'capacity' when deciding whether a person can make an important decision about their life. Competence and capacity mean the same thing. Assessment of competence and the role of substitute decision makers rests firmly on a sound understanding of the ethical basis of dental practice. This article will discuss the ethical basis of dental practice; the assessment of competence and the gaining of informed consent; the role of substitute decision makers and the nature of the decisions that are made at the end of life.

Allergen-specific IgE as a biomarker of exposure plus sensitization in inner-city adolescents with asthma.

BACKGROUND: Relationships among allergen-specific IgE levels, allergen exposure and asthma severity are poorly understood since sensitization has previously been evaluated as a dichotomous, rather than continuous characteristic. METHODS: Five hundred and forty-six inner-city adolescents enrolled in the Asthma Control Evaluation study underwent exhaled nitric oxide (FE(NO)) measurement, lung function testing, and completion of a questionnaire. Allergen-specific IgE levels and blood eosinophils were quantified. Dust samples were collected from the participants' bedrooms for quantification of allergen concentrations. Participants were followed for 12 months and clinical outcomes were tracked. RESULTS: Among sensitized participants, allergen-specific IgE levels were correlated with the corresponding settled dust allergen levels for cockroach, dust mite, and mouse (r = 0.38, 0.34, 0.19, respectively; P < 0.0001 for cockroach and dust mite and P = 0.03 for mouse), but not cat (r = -0.02, P = 0.71). Higher cockroach-, mite-, mouse-, and cat-specific IgE levels were associated with higher FE(NO) concentrations, poorer lung function, and higher blood eosinophils. Higher cat, dust mite, and mouse allergen-specific IgE levels were also associated with an increasing risk of exacerbations or hospitalization. CONCLUSIONS: Allergen-specific IgE levels were correlated with allergen exposure among sensitized participants, except for cat. Allergen-specific IgE levels were also associated with more severe asthma across a range of clinical and biologic markers. Adjusting for exposure did not provide additional predictive value, suggesting that higher allergen-specific IgE levels may be indicative of both higher exposure and a greater degree of sensitization, which in turn may result in greater asthma severity.

Microbial, instrumental color and sensory characteristics of inoculated ground beef produced using potassium lactate, sodium metasilicate or peroxyacetic acid as multiple antimicrobial interventions.

Effectiveness of multiple antimicrobial interventions on ground beef microbial, instrumental color and sensory attributes through display was evaluated. Beef trimmings were inoculated with Escherichia coli (EC) and Salmonella typhimurium (ST) then treated with either: (1) 3% potassium lactate followed by 4% sodium metasilicate (KN); (2) 4% sodium metasilicate followed by 3% potassium lactate (NK); (3) 200-ppm peroxyacetic acid followed by 3% potassium lactate (PK); (4) 200-ppm peroxyacetic acid followed by 4% sodium metasilicate (PN); or control (CON). Trimmings were ground, packaged and sampled on days 0-7 of display for EC, ST, coliforms, aerobic plate count, instrumental color and sensory characteristics. Only PK reduced (P<0.05) all bacterial types evaluated. The PN treatment remained (P<0.05) redder (a*), contained more (P<0.05) oxymyoglobin and had less (P<0.05) discoloration than CON by days 3-7 of display. All treatments maintained or improved odor attributes.

Ciprofloxacin-sensitive and ciprofloxacin-resistant Campylobacter jejuni are equally susceptible to natural orange oil-based antimicrobials.

A total of 10 ciprofloxacin-sensitive (ciprofloxacin minimum inhibitory concentration, MIC < 0.5 micro g/ml) and 10 ciprofloxacin-resistant (MIC 16 to 32 micro g/ml) presumptive C. jejuni were further characterized and evaluated for their inhibition by natural orange oil fractions. Partial species identification was performed by using a hippuricase gene-based polymerase chain reaction (PCR) assay. One of the isolates appeared to be atypical and failed to hydrolyze hippurate. Of the ciprofloxacin-resistant C. jejuni isolates tested, six were found to have their quinolone resistance determined by a C --> T mutation in codon 86 of gyrA. Both groups of ciprofloxacin-sensitive and -resistant C. jejuni isolates were most susceptible to cold-pressed terpeneless Valencia orange oil (C4) which yielded inhibition zones from 44.0 +/- 1.4 to 80 +/- 0.0 mm. Less inhibitory responses were recorded for 5-fold concentrated Valencia orange oil (C3) and distilled d-limonene (C7) which exerted similar effects on both ciprofloxacin-sensitive and -resistant C. jejuni isolates. In general, ciprofloxacin-resistant and -sensitive C. jejuni isolates were equally susceptible to the respective orange oil fractions.

Familial aggregation of food allergy and sensitization to food allergens: a family-based study.

BACKGROUND: The increasing prevalence of food allergy (FA) is a growing clinical and public health problem. The contribution of genetic factors to FA remains largely unknown. OBJECTIVE: This study examined the pattern of familial aggregation and the degree to which genetic factors contribute to FA and sensitization to food allergens. METHODS: This study included 581 nuclear families (2,004 subjects) as part of an ongoing FA study in Chicago, IL, USA. FA was defined by a set of criteria including timing, clinical symptoms obtained via standardized questionnaire interview and corroborative specific IgE cut-offs for > or =95% positive predictive value (PPV) for food allergens measured by Phadia ImmunoCAP. Familial aggregation of FA as well as sensitization to food allergens was examined using generalized estimating equation (GEE) models, with adjustment for important covariates including age, gender, ethnicity and birth order. Heritability was estimated for food-specific IgE measurements. RESULTS: FA in the index child was a significant and independent predictor of FA in other siblings (OR=2.6, 95% CI: 1.2-5.6, P=0.01). There were significant and positive associations among family members (father-offspring, mother-offspring, index-other siblings) for total IgE and specific IgE to all the nine major food allergens tested in this sample (sesame, peanut, wheat, milk, egg white, soy, walnut, shrimp and cod fish). The estimated heritability of food-specific IgE ranged from 0.15 to 0.35 and was statistically significant for all the nine tested food allergens. CONCLUSION: This family-based study demonstrates strong familial aggregation of FA and sensitization to food allergens, especially, among siblings. The heritability estimates indicate that food-specific IgE is likely influenced by both genetic and environmental factors. Together, this study provides strong evidence that both host genetic susceptibility and environmental factors determine the complex trait of IgE-mediated FA.

Monitoring cucumber beetles in sweetpotato and cucurbits with kairomone-baited traps.

Seven kairomone formulations (Trécé, Inc., Salinas, CA) were evaluated for their effectiveness as attractants for luring three species of cucumber beetles into Pherocon CRW traps (Trécé, Inc.) in cucurbit and sweetpotato fields. The spotted cucumber beetle, Diabrotica undecimpunctata howardi Barber; the banded cucumber beetle, Diabrotica balteata LeConte; and the striped cucumber beetle, Acalymma vittatum (F.), were captured in this study. TRE8276 (TIC mixture: 500 mg of 1,2,4-trimethoxybenzene, 500 mg of indole, and 500 mg of trans-cinnamaldeyde) and TRE8336 (500 mg of 1,2,4-trimethoxybenzene, 500 mg of trans-cinnamaldeyde, 500 mg of 4-methoxyphenethanol) were the most effective lures for spotted and striped cucumber beetles. None of the kairomone lures was very effective for attracting banded cucumber beetles. Three population peaks of spotted cucumber beetles were observed in cucurbit and sweetpotato fields at the U.S. Vegetable Laboratory (Charleston, SC). The efficacy of TRE8276 declined rapidly after 2 wk in the field. An improved design of the Pherocon CRW trap, with a yellow bottom and more-tapered top section, was more effective for capturing cucumber beetles than the original trap design made entirely of clear plastic. Banded cucumber beetles were not captured in sweetpotato fields at inland locations in North Carolina or South Carolina.

Moderate exercise training slows mammary tumour growth in adolescent rats.

Adolescence and young adulthood may be critical windows in establishing risk for breast cancer development in humans. Epidemiological data suggest that exercise during this life stage is associated with decreased breast cancer risk yet few experimental studies to elucidate the mechanism have been performed. The purpose of these studies was to evaluate the effects of moderate exercise training on mammary tumour development in adolescent rats using the 1-methyl 1-nitrosourea (MNU) chemical carcinogen model. Exercise (EX) consisted of moderate-intensity treadmill running 30 min/day, 5 days a week. A total of 274 animals were used: 94 in study 1 and 180 in study 2. Animals were injected with MNU (50 and 25 mg/kg body weight in studies 1 and 2, respectively) at 21 days of age and began training at 28 days of age. Groups of animals (n=10-30 depending on the study and time point) were sacrificed every 2 weeks for 8 weeks to evaluate tumour development. No difference in median tumour-free survival time was observed in the EX versus sham-exercise (SHAM), nor were there any differences in multiplicity at either a high or moderate dose of MNU. Latency to first tumour palpated was increased in both studies by 3-4 days. Consistent across both studies, tumour weights were less and the growth rates of the tumours, defined as tumour weight divided by the number of days elapsed since the tumour was first palpated, were reduced in the EX group. The data suggest that latency is increased and tumour growth is retarded in response to moderate exercise training.

Effect of nitrogen on resistance of sweet potato to sweetpotato weevil (Coleoptera: Curculionidae) and on storage root chemistry.

The effects of nitrogen fertilizer on sweet potato, Ipomoea batatas (L.) Poir., resistance to the sweetpotato weevil, Cylas formicarius elegantulus (Summers), was studied. Adult weevil feeding and oviposition preference, larval survival, and pupal weight were used as measures of sweet potato resistance. Sweet potato resin glycosides and caffeic acid concentrations in the periderm tissue of storage roots also were measured. Sweet potato genotypes (Beauregard, Excel, W-244, W-250, and Sumor) with varying levels of resistance to sweetpotato weevil were grown in the field under three nitrogen regimes (0, 45, and 135 kg N/ha). Harvested storage roots were evaluated in the laboratory for feeding and oviposition activity of sweetpotato weevil female adults under no-choice and choice test conditions. Larval survival rate and pupal weight were determined by rearing the insects individually on storage root sections. Nitrogen level had a significant effect on the number of eggs deposited, but not on the number of feeding punctures. Sweetpotato weevils laid fewer eggs on plants with the highest level of nitrogen. Nitrogen levels did not significantly affect larval survival and pupal weight. Genotype had a significant effect on feeding, oviposition, and larval survival. Beauregard had higher levels of feeding, oviposition, and larval survival compared with the other genotypes. No interaction effects between nitrogen and genotype were significant. Resin glycosides and caffeic acid concentrations were significantly different among genotypes and between years. Nitrogen levels significantly affected the concentrations of caffeic acid in 1997.

Crystal structure of a DEAD box protein from the hyperthermophile Methanococcus jannaschii.

We have determined the structure of a DEAD box putative RNA helicase from the hyperthermophile Methanococcus jannaschii. Like other helicases, the protein contains two alpha/beta domains, each with a recA-like topology. Unlike other helicases, the protein exists as a dimer in the crystal. Through an interaction that resembles the dimer interface of insulin, the amino-terminal domain's 7-strand beta-sheet is extended to 14 strands across the two molecules. Motifs conserved in the DEAD box family cluster in the cleft between domains, and many of their functions can be deduced by mutational data and by comparison with other helicase structures. Several lines of evidence suggest that motif III Ser-Ala-Thr may be involved in binding RNA.

Reactivities of genus-specific monoclonal antibody EM-6E11 against Listeria species and serotypes of Listeria monocytogenes grown in nonselective and selective enrichment broth media.

Depending on the growth medium used for enrichment of bacterial cells prior to assay, the monoclonal antibody (MAb) EM-6E11 recognizing Listeria genus-specific epitope on 43 and 94 to 97 kDa cell-surface antigens (A. K. Bhunia and M. G. Johnson, Appl. Environ. Microbiol. 58:1924-1929, 1992) exhibited extensive variability in the detection of Listeria species. MAb EM-6E11 strongly detected live cells of all Listeria species and all serotypes of L. monocytogenes by ELISA when cells were grown in nonselective brain heart infusion (BHI) broth, in selective Listeria enrichment broth (LEB), or in Listeria repair broth (LRB). In contrast, EM-6E11 detected only four of the thirteen serotypes of L. monocytogenes (serotypes 1/2c, 3b, 4ab, and 7) when cells were grown in the UVM1 formulation of Listeria enrichment broth (UVM1) or Fraser broth (FRB). This MAb failed to react with live cells of four other Listeria species, including L. ivanovii, L. welshimeri, L. grayi, and L. murrayi cells grown in UVM1 or FRB. Heating of Listeria cells at 100 degrees C for 20 min, irrespective of the enrichment media used, led to large losses of MAb EM-6E11 reactivity in ELISA, suggesting that the specific cell-surface epitopes involved may not be heat stable. Our results confirm that MAb EM-6E11 is suitable for detection of live cells but not heat-killed cells of Listeria spp. and can be used in conjunction with an enrichment step in BHI, LEB, or LRB but not in UVM1 or FRB.

Unstable expression and thermal instability of a species-specific cell surface epitope associated with a 66-kilodalton antigen recognized by monoclonal antibody EM-7G1 within serotypes of Listeria monocytogenes grown in nonselective and selective broths.

Conditions that resulted in unstable expression and heat instability of a cell surface epitope associated with a 66-kDa antigen in Listeria monocytogenes serotypes were identified with the probe monoclonal antibody (MAb) EM-7G1 in an enzyme-linked immunosorbent assay. This epitope appeared to be absent in three serotypes (serotypes 3b, 4a, and 4c), which did not react with MAb EM-7G1 irrespective of the enrichment broth tested. The remaining 10 serotypes were detected by MAb EM-7G1 only when cells were grown in nonselective brain heart infusion broth (BHI) or selective Listeria enrichment broth (LEB). When cells were grown in Listeria repair broth (LRB), only 6 of the 13 serotypes were detected by MAb EM-7G1, and recognition of serogroup 4 was completely lost. None of the 13 serotypes was detected by MAb EM-7G1 when cells were grown in two other commonly used Listeria-selective media, UVM1 broth and Fraser broth (FRB), indicating that possible loss of epitope expression occurred under these conditions. MAb EM-7G1 maintained species specificity without cross-reacting with live or heat-killed cells of six other Listeria spp. (Listeria ivanovii, Listeria innocua, Listeria seeligeri, Listeria welshimeri, Listeria grayi, and Listeria murrayi) irrespective of the enrichment conditions tested. Due to heat instability of the cell surface epitope when it was exposed to 80 or 100 degrees C for 20 min, MAb EM-7G1 is suitable for detection of live cells of L. monocytogenes in BHI or LEB but not in LRB, UVM1, or FRB enrichment medium.

Pre- and posttreatment comparison of the kinematics of the fluent speech of persons who stutter.

This study reports changes in acoustic, respiratory, laryngeal, and articulatory kinematics of 3 males who stutter, following participation in a version of the Hollins Precision Fluency Shaping Program. Two nonstuttering controls received no treatment. Subjects repeated phrases of the form "He see CVC again" at self-selected slow, normal, and fast speaking rates. For experimental subjects, acoustic duration of the phrases increased significantly in 7 out of 9 comparisons of before- and after-treatment conditions, whereas controls decreased the duration of the phrases in 4 out of 6 comparisons of measurements made over approximately the time interval during which the experimental group received treatment. The experimental group increased inspiratory volume for 7 out of 9 conditions and average expiratory flow significantly for all conditions, whereas the controls decreased both. The experimental group prolonged laryngeal opening in 6 of 7 comparisons, but only 3 of the increases were significant. Lip and jaw movements for consonants were significantly reduced in amplitude for the experimental group for 30 of 36 measures. The direction of change for laryngeal and upper articulator measures was mixed for controls. These results show that behavioral treatment can produce significant changes in the fluent speech of persons who stutter with respect to respiration, laryngeal valving, and articulation. Possible relationships between the observed changes in speech production and the increased fluency of the subjects are discussed.

Frozen stored murine hybridoma cells can be used to determine the virulence of Listeria monocytogenes.

Murine hybridoma cells, designated Ped-2E9, when stored up to 60 days at -196 degrees C or up to 48 days at -80 degrees C, gave results equivalent to those for freshly grown murine hybridoma cells in an in vitro pathogenicity assay of Listeria species. Thus, laboratories do not need to have their own tissue culture facilities to maintain the hybridoma cells for the assay described.

Interactions of three strands in joints made by RecA protein.

RecA protein from Escherichia coli has been used to form a triple-stranded DNA structure from either single-stranded M13 DNA or a single-stranded oligonucleotide plus a duplex oligonucleotide with a hairpin loop. The secondary structure of purified deproteinized triplex was examined by probing with DNase I, P1 nuclease, potassium permanganate, and diethyl pyrocarbonate. The two strands destined to form heteroduplex DNA showed the same patterns of chemical modification and enzymatic digestion as control duplex DNA, indicating that they formed a normal duplex substructure. However, the nascent outgoing strand showed properties consistent with a novel triplex structure: most of its purine residues, especially adenines, were hyperreactive to all probes. The patterns of digestion by DNase I and P1 nuclease indicated that the nascent outgoing strand was not a freely mobile or single-stranded branch but rather was still interacting with the newly formed heteroduplex DNA. On the basis of the planar base triads proposed previously (Rao et al., 1993) and energy minimization of a third strand in the major groove of B-form DNA, we derived a model that helps to rationalize the properties revealed by chemical and enzymatic probing.

Structural relationship of bacterial RecA proteins to recombination proteins from bacteriophage T4 and yeast.

RecA protein is essential in eubacteria for homologous recombination and promotes the homologous pairing and strand exchange of DNA molecules in vitro. Recombination proteins with weak sequence similarity to bacterial RecA proteins have been identified in bacteriophage T4, yeast, and other higher organisms. Analysis of the primary sequence relationships of DMC1 from Saccharomyces cerevisiae and UvsX of T4 relative to the three-dimensional structure of RecA from Escherichia coli suggests that both proteins are structural homologs of bacterial RecA proteins. This analysis argues that proteins in this group are members of a single family that diverged from a common ancestor that existed prior to the divergence of prokaryotes and eukaryotes.

The structure of the E. coli recA protein monomer and polymer.

The crystal structure of the recA protein from Escherichia coli at 2.3-A resolution reveals a major domain that binds ADP and probably single- and double-stranded DNA. Two smaller subdomains at the N and C termini protrude from the protein and respectively stabilize a 6(1) helical polymer of protein subunits and interpolymer bundles. This polymer structure closely resembles that of recA/DNA filaments determined by electron microscopy. Mutations in recA protein that enhance coprotease, DNA-binding and/or strand-exchange activity can be explained if the interpolymer interactions in the crystal reflect a regulatory mechanism in vivo.

Structure of the recA protein-ADP complex.

The recA protein catalyses the ATP-driven homologous pairing and strand exchange of DNA molecules. It is an allosteric enzyme: the ATPase activity is DNA-dependent, and ATP-bound recA protein has a high affinity for DNA, whereas the ADP-bound form has a low affinity. In the absence of ATP hydrolysis, recA protein can still promote homologous pairing, apparently through the formation of a triple-stranded intermediate. The exact role of ATP hydrolysis is not clear, but it presumably drives the triplex intermediate towards products. Here we determine the position of bound ADP diffused into the recA crystal. We show that only the phosphates are bound in the same way as in other NTPases containing the G/AXXXXGKT/S motif. We propose that recA protein may change its conformation upon ATP hydrolysis in a manner analogous to one such protein, the p21 protein from the ras oncogene. A model is presented to account for the allosteric stimulation of DNA binding by ATP. The mechanism by which nucleoside triphosphate hydrolysis is coupled to the binding of another ligand in recA protein and p21 may be typical of the large class of NTPases containing this conserved motif.