Public health surveillance of dental pain via Twitter.

On Twitter, people answer the question, "What are you doing right now?" in no more than 140 characters. We investigated the content of Twitter posts meeting search criteria relating to dental pain. A set of 1000 tweets was randomly selected from 4859 tweets over 7 non-consecutive days. The content was coded using pre-established, non-mutually-exclusive categories, including the experience of dental pain, actions taken or contemplated in response to a toothache, impact on daily life, and advice sought from the Twitter community. After excluding ambiguous tweets, spam, and repeat users, we analyzed 772 tweets and calculated frequencies. Of the sample of 772 tweets, 83% (n = 640) were primarily categorized as a general statement of dental pain, 22% (n = 170) as an action taken or contemplated, and 15% (n = 112) as describing an impact on daily activities. Among the actions taken or contemplated, 44% (n = 74) reported seeing a dentist, 43% (n = 73) took an analgesic or antibiotic medication, and 14% (n = 24) actively sought advice from the Twitter community. Twitter users extensively share health information relating to dental pain, including actions taken to relieve pain and the impact of pain. This new medium may provide an opportunity for dental professionals to disseminate health information.

A radiation hybrid mapping panel for the rhesus macaque.

The genomes of nonhuman primates have recently become highly visible candidates for full genome analysis, as they provide powerful models of human disease and a better understanding of the evolution of the human genome. We describe the creation of a 5000 rad radiation hybrid (RH) mapping panel for the rhesus macaque. Duplicate genotypes of 84 microsatellite and coding gene sequence tagged sites from six macaque chromosomes produced an estimated whole genome retention frequency of 0.33. To test the mapping ability of the panel, we constructed RH maps for macaque chromosomes 7 and 9 and compared them to orthologous locus orders in existing human and baboon maps derived from different methodologies. Concordant marker order between all three species maps suggests that the current panel represents a powerful mapping resource for generating high-density comparative maps of the rhesus macaque and other species genomes.

Mutational spectra for polycyclic aromatic hydrocarbons in the supF target gene.

An SV40-based shuttle vector system was used to identify the types of mutational changes and the sites of mutation within the supF DNA sequence generated by the four stereoisomers of benzo[c]phenanthrene 3,4-dihydrodiol 1,2-epoxide (B[c]PhDE), by racemic mixtures of bay or fjord region dihydrodiol epoxides (DE) of 5-methylchrysene, of 5, 6-dimethylchrysene, of benzo[g]chrysene and of 7-methylbenz[a]anthracene and by two direct acting polycyclic aromatic hydrocarbon carcinogens, 7-bromomethylbenz[a]anthracene (7-BrMeBA) and 7-bromomethyl-12-methylbenz[a]anthracene (7-BrMe-12-MeBA). The results of these studies demonstrated that the predominant type of mutation induced by these compounds is the base substitution. The chemical preference for reaction at deoxyadenosine (dAdo) or deoxyguanosine (dGuo) residues in DNA, which is in general correlated with the spatial structure (planar or non-planar) of the reactive polycyclic aromatic hydrocarbon, is reflected in the preference for mutation at A&z.ccirf;T or G&z.ccirf;C pairs. In addition, if the ability to react with DNA in vivo is taken into account, the relative mutagenic potencies of the B[c]PhDE stereoisomers are consistent with the higher tumorigenic activity associated with non-planar polycyclic aromatic hydrocarbons and their extensive reaction with dAdo residues in DNA. Comparison of the types of mutations generated by polycyclic aromatic hydrocarbons and other bulky carcinogens in this shuttle vector system suggests that all bulky lesions may be processed by a similar mechanism related to that involved in replication past apurinic sites. However, inspection of the distribution of mutations over the target gene induced by the different compounds demonstrated that individual polycyclic aromatic hydrocarbons induce unique patterns of mutational hotspots within the target gene. A polymerase arrest assay was used to determine the sequence specificity of the interaction of reactive polycyclic aromatic hydrocarbons with the shuttle vector DNA. The results of these assays revealed a divergence between mutational hotspots and polymerase arrest sites for all compounds investigated, i.e., sites of mutational hotspots do not correspond to sites where high levels of adduct formation occur, and suggested that some association between specific adducts and sequence context may be required to constitute a premutagenic lesion. A site-specific mutagenesis system employing a single-stranded vector (M13mp7L2) was used to investigate the mutational events a single benzo[a]pyrene or benzo[c]phenanthrene dihydrodiol epoxide-DNA adduct elicits within specific sequence contexts. These studies showed that sequence context can cause striking differences in mutagenic frequencies for given adducts. In addition, these sequence context effects do not originate only from nucleotides immediately adjacent to the adduct, but are also modulated by more distal nucleotides. The implications of these results for mechanisms of polycyclic aromatic hydrocarbon-induced mutagenesis and carcinogenesis are discussed.

Mutational consequences of replication of M13mp7L2 constructs containing cis-opened benzo[a]pyrene 7,8-diol 9, 10-epoxide-deoxyadenosine adducts.

The four adducts that arise by cis ring opening of the four optically active benzo[a]pyrene diol epoxides by the exocyclic N6-amino group of deoxyadenosine were incorporated synthetically into each of two different oligonucleotide 16-mers, 5'-TTTXGAGTCTGCTCCC-3' [context I(A)] and 5'-CAGXTTTAGAGTCTGC-3' [context II(A)], at the X position. The eight resultant oligonucleotides were separately ligated into bacteriophage M13mp7L2 and replicated in Escherichia coli that had been SOS-induced, and the progeny were analyzed to evaluate the consequences of replication past these adducts. The presence of these adducts reduced plaque yields substantially. However, the progeny obtained exhibited high frequencies of base substitution mutation ranging from 9 to 68%, depending upon the individual adduct and the sequence context in which it was placed. For most of the adducts, A --> T transversion was the mutation found most frequently in either sequence context, and mutation frequencies in context I(A) were always substantially greater than those in context II(A). In context I(A), adducts with an R configuration at the site of nucleoside attachment were more mutagenic than those with an S configuration. In both sequence contexts that were studied, the cis adduct arising from the (7S,8R)-diol (9S,10R)-epoxide was the most mutagenic adduct. These findings clearly show that individual mutation frequencies are determined by the combined effects of both adduct structure and sequence context.

DNA reactions, mutagenic action and stealth properties of polycyclic aromatic hydrocarbon carcinogens (review).

A brief summary of recent research, primarily from the authors' laboratory, on polycyclic aromatic hydrocarbon carcinogens with respect to their DNA adduct formation, the mutational properties of these adducts and the effects of hydrocarbon dihydrodiol epoxide metabolites on the passage of cells through the cell cycle is presented. The concept of stealth properties of potent carcinogens, i.e. their ability to damage DNA without inducing a G1 arrest, is discussed. Also, mutation studies with dihydrodiol epoxide metabolites, the sequence-dependence of site-specific mutation, as well as the selectivity of hydrocarbon-DNA adduct formation are summarized.

Sequence context profoundly influences the mutagenic potency of trans-opened benzo[a]pyrene 7,8-diol 9,10-epoxide-purine nucleoside adducts in site-specific mutation studies.

The postoligomerization method was used to prepare oligonucleotide 16-mers that contained dAdo or dGuo adducts, derived from trans opening of each enantiomer of the two diastereomeric benzo[a]pyrene 7,8-diol 9,10-epoxides, in two sequence contexts. These 16 oligonucleotides, along with the four corresponding oligonucleotides containing unsubstituted purines, were ligated into single-stranded DNA from bacteriophage M13mp7L2 and transfected into Escherichia coli SMH77. The mutagenic effects of replication past these adducts were then evaluated. The various adduct isomers induced point mutations at different frequencies and with different distributions of mutation types, as was anticipated. However, sequence context had the most substantial effects on mutation frequency. A high frequency of deletions of a single guanine was found in a context where the dGuo adduct was at the 3'-end of a run of five guanines, whereas no single base deletion was found in the other context studied, 5'-CGA-3'. Mutation frequencies in constructs containing dAdo adducts were much higher in a 5'-TAG-3' context (37-58%, depending on the individual isomer) than in a 5'-GAT-3' context (5-20%), and for a given adduct, mutation frequency was up to 10-fold higher in the former sequence than in the latter. These findings indicate that sequence context effects need more thorough evaluation if the goal of understanding the mechanism through which DNA adducts lead to mutation is to be achieved.

Effect of cadmium exposure on background and anti-5 methylchrysene-1,2-dihydrodiol 3,4-epoxide-induced mutagenesis in the supF gene of pS189 in human Ad293 cells.

Cadmium is a toxic environmental contaminant that is carcinogenic in humans and rodents. Although cadmium has proven to be mutagenic in a variety of assay systems, exactly how cadmium achieves gentoxicity is poorly understood. To define the mechanism(s) underlying the mutagenicity and comutagenicity of cadmium, human Ad293 cells were exposed to subtoxic doses of the metal and transfected with untreated or anti-5-methylchrysene-3,4-dihydrodiol 1,2-epoxide (5-MCDE)-treated pS189 shuttle vector. Alterations in the frequency, types, and distribution of mutations were subsequently assessed in the supF gene of pS189 that was replicated in Ad293 cells and screened in indicator bacteria. Doses of 0.5 and 1 microM CdCl2 increased the mutation frequency of untreated pS189 by approximately 4- and 8-fold, respectively, with no apparent effect on the types of mutations generated. In contrast, host-cell exposure to cadmium had little or no effect on the frequency, types, or distribution of mutations generated with 5-MCDE-treated pS189. These results indicate that cadmium increases mutagenesis of untreated pS189 by affecting a process that is not involved in mutagenesis of the 5-MCDE-treated vector. Although it is not clear exactly how host-cell exposure to cadmium increases background mutagenesis, presumably, the mutagenic effect does not involve cadmium interaction with the cellular machinery used to replicate past bulky DNA lesions.

Mutational specificity of the syn 1,2-dihydrodiol 3,4-epoxide of 5-methylchrysene.

The mutational specificity of the syn dihydrodiol epoxide of 5-methylchrysene in the supF gene of the pSP189 vector was examined. Transversion mutations at GC pairs predominated with G --> T and G --> C changes accounting for 42 and 21% of total base change mutations. The types of mutations found reflect the previously determined chemical preference of this reactive species for reaction with deoxyguanosine residues in DNA.

Mutagenic specificities and adduct distributions for 7-bromomethylbenz[a]anthracenes.

Mutation induction in the supF gene of the plasmid pS189 by 7-bromomethylbenz[a]anthracene and 7-bromomethyl-12-methylbenz[a]anthracene was examined. The former compound was substantially more mutagenic than the latter but a much greater proportion of the total mutations were located at mutation hotspots for the 12-methyl derivative. The overall correlation between sites of mutation and sites of polymerase arrest (an indicator of adduct formation) through the supF gene was poor. Although these bromocompounds should form only a single guanine adduct (unlike dihydrodiol epoxides that form both cis and trans adducts) more than one mutational change was found at a given site, although the predominant base substitution was G-->T for either compound.

Characterization of DNA adducts formed by anti-benzo[g]chrysene 11,12-dihydrodiol 13,14-epoxide.

The anti-11,12-dihydrodiol 13,14-epoxide of benzo[g]chrysene, a fjord-region-containing hydrocarbon, was found to react with DNA in vitro to yield, as the major product, an adduct in which the epoxide of the 11R, 12S, 13S, 14R enantiomer was opened trans by the amino group of deoxyadenosine. The structures of this adduct and other deoxyadenosine and deoxyguanosine adducts were established by spectroscopic methods. In reactions with deoxyguanylic acid, a product tentatively identified as a 7-substituted guanine was also detected. The mutagenic properties of this dihydrodiol epoxide in shuttle vector pSP189 showed that mutation at AT pairs accounted for 39% of base change mutations whereas chemical findings indicated that about 60% of adducts formed in calf thymus DNA involved adenines. Since calf thymus DNA is 56% AT and the target supF gene is 41% AT, the findings represent a fairly close relationship between adduct formation and mutagenic response. Overall, the chemical and mutagenic selectivities for the two purine bases in DNA were similar, though not identical, to those for the only other fjord-region-containing hydrocarbon studied in depth, i.e., benzo[c]phenanthrene. A major difference for these two hydrocarbon derivatives, however, is that benzo[c]phenanthrene dihydrodiol epoxides react to much higher extents (approximately 4-fold) with DNA than did the benzo[g]chrysene derivative.

Non-invasive assessment of reperfusion of the infarct-related artery during coronary thrombolysis and its relation with left ventricular function.

We monitored ST segment continuously for at least 3 h after the beginning of lytic treatment in 103 patients undergoing early coronary thrombolysis for acute myocardial infarction in order to ascertain whether this technique, which has been shown to be useful to assess recanalization of the infarct-related artery, is also able to identify the improvement in left ventricular function associated with successful reperfusion. Global left ventricular function (assessed in the 30 degrees right anterior oblique projection with the area/length method) and infarct zone wall motion (studied with the centerline method) were evaluated at least 4 weeks after the event. Reperfusion was thought to be achieved when ST segment elevation dropped > 50% relative to the most abnormal peak documented at any time in the study. Eighty patients (78%) met the criterium for successful reperfusion (group 1), and 23 (22%) did not (group 2). Both groups had similar clinical and angiographic characteristics. All indexes of global left ventricular function were significantly better in group 1 than in group 2 patients (end-diastolic volume: 176 +/- 51 vs. 209 +/- 76 ml, end-systolic volume: 66 +/- 40 vs. 97 +/- 55 ml, ejection fraction: 65 +/- 13 vs. 57 +/- 11%, respectively, all P < 0.02). Also the severity (-1.6 +/- 1.3 vs. -2.6 +/- 1.01 S.D./chord, respectively, P < 0.001) and the extension of hypokinesia in the infarct zone (number of chords with > 2 S.D.: 13 +/- 16 vs. 28 +/- 17, respectively, P < 0.0001) were less in group 1 than in group 2 patients. Furthermore, in reperfused patients, both global left ventricular function and regional wall motion were better in those admitted < 60 min from onset of pain. In conclusion, patients with rapid ( > 50%) decrease of ST segment elevation have smaller infarct size and better global left ventricular function than patients without electrocardiographic signs of reperfusion as assessed by continuous ST segment monitoring. This suggests that this non-invasive technique is a powerful tool able to identify patients most benefiting from thrombolytic therapy.

Mutational spectra for 5,6-dimethylchrysene 1,2-dihydrodiol 3,4-epoxides in the supF gene of pSP189.

Dihydrodiol epoxides from 5,6-dimethylchrysene exhibit properties similar to those of fjord region-containing hydrocarbon derivatives in that they react extensively with deoxyadenosine residues in DNA and consequently generate substantial numbers of mutations at AT pairs as well as GC pairs. The syn-dihydrodiol epoxide favors reaction with deoxyadenosine (68% of adducts) to a greater extent than does the anti-dihydrodiol epoxide (52% of adducts), and point mutations at AT pairs (72% for syn- and 45% for anti-dihydrodiol epoxide) follow the same trend. A novel feature of the mutagenicity of the 5,6-dimethylchrysene derivatives is that they exhibit a higher fraction of AT-->GC transitions (28% and 26% for syn and anti, respectively) than has been seen for other hydrocarbon derivatives to date.

Exercise-induced hypoxaemia in master athletes: effects of a polyunsaturated fatty acid diet.

Exercise-induced hypoxaemia (EIH) has been associated with an oxygen diffusion limitation. Because polyunsaturated fatty acids (PUFA) administration can modify cell membrane fluidity, we hypothesized that the importance of EIH could be reduced after a 6-week PUFA diet. Resting pulmonary functions and a maximal cycling test were performed before and after the diet, in eight master athletes -48 (SD 6 years)-. The partial pressure of O2 in arterial blood (PaO2), alveolar ventilation (VA) and ideal alveolar-arterial oxygen partial pressure difference (P(Ai-a) O2) were obtained at each exercise intensity. The extent of EIH at maximal exercise was significantly lower after PUFA [PaO2-17.2 (SEM 1.9) vs -12.9 (SEM 2.2)]. Before PUFA, VA accounted for 50% of the variance in the fall in P (Ai-a) for intensities below 80% maximal oxygen uptake (VO2max) and P(Ai-a)O2 for 60% between 70% and 100% VO2max. After PUFA, the reduction in EIH was highly correlated (r2 = 0.85; P < 0.001) to resulting changes in P(Ai-a)O2 and resting pulmonary diffusing capacity (DLCO)/VA but not with changes in ideal alveolar partial pressure of oxygen. The improvement in EIH following PUFA could be related to an increase in alveolar-arterial oxygen conductance following improved pulmonary diffusion.

Ultrasound findings in renal parenchymal disease: comparison with histological appearances.

Ultrasound examination was carried out in 55 patients undergoing renal biopsy for suspected renal parenchymal disease. Analysis of sonographic and histological findings showed statistically significant positive correlations between renal size and the extent of glomerular hyper-cellularity and crescent formation and between cortical echogenicity and severity of glomerular sclerosis, crescent formation, interstitial inflammatory cell infiltration, tubular atrophy and interstitial fibrosis. Positive correlation was also observed between prominence of the medullary pyramids and glomerular sclerosis. The most marked sonographic abnormalities were seen in proliferative (including crescentic) glomerulonephritis, diabetic glomerulosclerosis and tubulo-interstitial nephritis. IgA, membranous and minimal change nephropathy were less likely to be associated with sonographic abnormalities. We conclude that certain sonographic appearances in renal parenchymal disease reflect the presence and severity of light microscopical abnormalities but, although ultrasound assessment provides a high positive predictive value for renal parenchymal disease, specific conditions cannot be distinguished.

Reaction with DNA and mutagenic specificity of syn-benzo[g]chrysene 11,12-dihydrodiol 13,14-epoxide.

The spectroscopic characterization of purine deoxyribonucleoside adducts derived from the fjord-region syn-benzo[g]chrysene 11,12-dihydrodiol 13,14-epoxide and the mutagenic specificity of the latter compound for the supF gene in the pSP189 shuttle vector are described. This dihydrodiol epoxide preferentially forms adducts with deoxyadenosine residues in DNA and is preferentially opened trans in reactions with DNA or with deoxyribonucleotides. In common with other fjord-region syn-dihydrodiol epoxides, the most frequently observed mutational changes were A-->T and G-->T changes. This hydrocarbon dihydrodiol epoxide is structurally similar to syn-benzo[c]phenanthrene 3,4-dihydrodiol 1,2-epoxide but has an additional benzene ring annelated distant from the reaction center. As anticipated, there were some common features in the chemistry and mutagenicities of these two compounds, but there were also substantive differences which indicate factors of importance in controlling reactions of these kinds of compounds with DNA.

Biologically active diterpenes from Aspilia mossambicensis, a chimpanzee medicinal plant.

Two potent stimulators of uterine contraction, the diterpenes kaurenoic and grandiflorenic acids, were isolated from leaves of Aspilia mossambicensis. Their presence supports a hypothesis that wild chimpanzees consume Aspilia species for their pharmacological properties and may explain why female chimpanzees consume Aspilia leaves more frequently than do males. Thiarubrines were not present in any of the leaf samples collected in Mahale or Gombe National Parks, Tanzania, although these antifungal and nematocidal dithianes were found in significant amounts in roots.

Accelerated thrombolysis facilitated by direct puncture of occluded prosthetic femoral grafts.

Inability to access occluded grafts is a major limitation to successful thrombolysis and may even preclude it. This paper addresses the problem and offers a new technique of direct puncture of prosthetic grafts through which thrombolysis and angioplasty can be performed. These techniques resulted in accelerated thrombolysis in all 15 patients studied with no failures due to inability to attain graft access.

Complications attributable to the formation of the track in patients undergoing percutaneous nephrolithotomy.

Reported complication rates of percutaneous nephrolithotomy vary considerably. In our own experience of 110 percutaneous nephrolithotomies performed by an experienced interventional radiologist, the complication rate for the entire procedure was 3.6%, and for the formation of the nephrostomy track 0.9%. This compares favourably with the reports from the major centres. Radiation dose to the operator was monitored and our results confirm that with meticulous attention to technique, dosages may be kept very low. We conclude that prior training in interventional techniques is a major factor in reducing both the morbidity associated with percutaneous nephrolithotomy and the radiation dose to the operator.