Modeling Social Network Influences on Oral Health Outcomes among Women Living in Public Housing.

OBJECTIVE: Research into the influence and role of social networks on oral health outcomes has been limited. This study aims to demonstrate via explanatory modeling the influence of social networks on oral health outcomes among women in who live in public housing in Boston, Massachusetts. METHODS: Individual- and network-level data were obtained from a cross-sectional survey of adult female residents of 2 public housing developments in Boston, Massachusetts. Participants responded to close-ended questions about sociodemographic characteristics, oral and general health status, and health-related behaviors for themselves as well as their named social contacts. Based on this information, network-level variables were calculated for each participant, including the proportion of the social network with certain characteristics or attributes. To assess the salience of network measures in explaining the variability in self-reported oral health status, overall health status, use of dental services within the last year, and current dental treatment needs, logistic regression models with individual-level covariates were compared with corresponding models that additionally included network-level variables with McFadden R2 for comparison purposes. RESULTS: Model comparisons for each outcome of interest demonstrated that adding network-level covariates significantly improved model fit. Additionally, network-level covariates displayed strong independent associations with the outcomes of interest. The network proportion needing dental treatment was positively associated with participants' odds of reporting current dental treatment needs (odds ratio, 4.71; 95% CI, 1.47 to 15.05). An individual's odds of reporting no dental visit within the past year decreased with increasing exposure to social contacts with reported dental visits within the past year (odds ratio, 0.26; 95% CI, 0.07 to 0.89). CONCLUSION: The salience of specific network attributes depended on the outcome under study. Interventions aimed at reducing the poor oral health burden in this and similar population groups may benefit from integrating information on social networks, including tailoring intervention delivery and/or messaging to account for the potential influence of social networks. KNOWLEDGE TRANSFER STATEMENT: This work may be beneficial to those developing policy solutions and interventions aimed at reducing the burden of poor oral health outcomes in socioeconomically disadvantaged populations, such as women who reside in public housing developments. The potential for leveraging social networks to seed messaging about oral health, for example, may enhance efforts to reduce oral health disparities.

Quantitative Assessment of Systematic Bias: A Guide for Researchers.

Observational research provides valuable opportunities to advance oral health science but is limited by vulnerabilities to systematic bias, including unmeasured confounding, errors in variable measurement, or bias in the creation of study populations and/or analytic samples. The potential influence of systematic biases on observed results is often only briefly mentioned among the discussion of limitations of a given study, despite existing methods that support detailed assessments of their potential effects. Quantitative bias analysis is a set of methodological techniques that, when applied to observational data, can provide important context to aid in the interpretation and integration of observational research findings into the broader body of oral health research. Specifically, these methods were developed to provide quantitative estimates of the potential magnitude and direction of the influence of systematic biases on observed results. We aim to encourage and facilitate the broad adoption of quantitative bias analyses into observational oral health research. To this end, we provide an overview of quantitative bias analysis techniques, including a step-by-step implementation guide. We also provide a detailed appendix that guides readers through an applied example using real data obtained from a prospective observational cohort study of preconception periodontitis in relation to time to pregnancy. Quantitative bias analysis methods are available to all investigators. When appropriately applied to observational studies, findings from such studies can have a greater impact in the broader research context.

Simulation of Random Differential Periodontitis Outcome Misclassification with Perfect Specificity.

INTRODUCTION: Misclassification of clinical periodontitis can occur by partial-mouth protocols, particularly when tooth-based case definitions are applied. In these cases, the true prevalence of periodontal disease is underestimated, but specificity is perfect. In association studies of periodontal disease etiology, misclassification by this mechanism is independent of exposure status (i.e., nondifferential). Despite nondifferential mechanisms, differential misclassification may be realized by virtue of random errors. OBJECTIVES: To gauge the amount of uncertainty around the expectation of differential periodontitis outcome misclassification due to random error only, we estimated the probability of differential outcome misclassification, its magnitude, and expected impacts via simulation methods using values from the periodontitis literature. METHODS: We simulated data sets with a binary exposure and outcome that varied according to sample size (200, 1,000, 5,000, 10,000), exposure effect (risk ratio; 1.5, 2), exposure prevalence (0.1, 0.3), outcome incidence (0.1, 0.4), and outcome sensitivity (0.6, 0.8). Using a Bernoulli trial, we introduced misclassification by randomly sampling individuals with the outcome in each exposure group and repeated each scenario 10,000 times. RESULTS: The probability of differential misclassification decreased as the simulation parameter values increased and occurred at least 37% of the time across the 10,000 repetitions. Across all scenarios, the risk ratio was biased, on average, toward the null when the sensitivity was higher among the unexposed and away from the null when it was higher among the exposed. The extent of bias for absolute sensitivity differences ≥0.04 ranged from 0.05 to 0.19 regardless of simulation parameters. However, similar trends were not observed for the odds ratio where the extent and direction of bias were dependent on the outcome incidence, sensitivity of classification, and effect size. CONCLUSIONS: The results of this simulation provide helpful quantitative information to guide interpretation of findings in which nondifferential outcome misclassification mechanisms are known to be operational with perfect specificity. KNOWLEDGE TRANSFER STATEMENT: Measurement of periodontitis can suffer from classification errors, such as when partial-mouth protocols are applied. In this case, specificity is perfect and sensitivity is expected to be nondifferential, leading to an expectation for no bias when studying periodontitis etiologies. Despite expectation, differential misclassification could occur from sources of random error, the effects of which are unknown. Proper scrutiny of research findings can occur when the probability and impact of random classification errors are known.

Self-reported periodontitis and fecundability in a population of pregnancy planners.

STUDY QUESTION: Is a history of periodontitis among women associated with reduced fecundability? SUMMARY ANSWER: A history of periodontitis, as assessed by three different self-reported measures, may be associated with reduced fecundability. WHAT IS KNOWN ALREADY: Periodontitis is a chronic inflammatory condition affecting the hard and soft tissues surrounding the teeth. Few studies have evaluated the association between periodontitis and time to pregnancy, and findings are mixed. It is hypothesized that periodontitis may adversely affect time to pregnancy. STUDY DESIGN, SIZE, DURATION: We conducted a prospective cohort study of 2764 female pregnancy planners residing in North America (March 2015-June 2020). PARTICIPANTS/MATERIALS, SETTING, METHODS: Eligible participants had been attempting pregnancy for six or fewer menstrual cycles at enrollment and were not using fertility treatment. Women answered questions about their oral health. Pregnancy was ascertained via bi-monthly follow-up questionnaires. We used proportional probabilities regression models to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs) for three different measures indicative of a history of periodontitis: ever diagnosed with periodontitis (N = 265), ever received treatment for periodontitis (N = 299), and ever had an adult tooth become loose on its own (N = 83). We adjusted for potential confounders and precision variables. Women at risk of misclassification of periodontitis diagnosis due to pregnancy-related gingivitis were reclassified in a sensitivity analysis. MAIN RESULTS AND THE ROLE OF CHANCE: All three indices of periodontitis may be associated with reduced fecundability. FRs were 0.89 (95% CI 0.75-1.06) comparing women with and without a previous periodontitis diagnosis, 0.79 (95% CI 0.67-0.94) comparing women with and without previous periodontitis treatment, and 0.71 (95% CI 0.44-1.16) comparing women with and without a tooth that became loose. After reclassification of pregnancy-related gingivitis in the sensitivity analysis, the FR for periodontitis diagnosis was 0.83 (95% CI 0.68-1.00). Weaker FRs were observed among parous women as compared with nulliparous women for periodontitis diagnosis and tooth becoming loose, but not for periodontitis treatment. LIMITATIONS, REASONS FOR CAUTION: Though we used validated self-report measures of periodontitis, clinical confirmation is the gold standard. These questions may be functioning as markers of different levels of periodontitis severity, but we were unable to measure disease severity in this population. Finally, we cannot eliminate the possibility of unmeasured confounding. WIDER IMPLICATIONS OF THE FINDINGS: This is the first preconception prospective cohort study to evaluate the association between self-reported periodontitis and fecundability. Our results indicate that periodontitis may be associated with lower fecundability. STUDY FUNDING/COMPETING INTEREST(S): This work was partially funded by R01HD086742/Eunice Kennedy Shriver National Institute of Child Health and Human Development and R21HD072326/Eunice Kennedy Shriver National Institute of Child Health and Human Development. PRESTO has received in-kind donations from Swiss Precision Diagnostics, Sandstone Diagnostics, FertilityFriend.com, and Kindara.com for primary data collection. L.A.W. is a fibroid consultant for AbbVie, Inc. J.C.B., S.W., J.Y., K.J.R., E.E.H., and B.H. have no conflicts of interest to disclose. TRIAL REGISTRATION NUMBER: N/A.

Third-Molar Status and Risk of Loss of Adjacent Second Molars.

The prophylactic removal of asymptomatic third molars is a common but controversial procedure often rationalized as necessary to prevent future disease on adjacent teeth. Our objective in this retrospective cohort study of adult men was to examine whether second-molar loss differed by baseline status of the adjacent third molar, taking into account the individual's overall state of oral hygiene, caries, and periodontitis. We analyzed data from participants of the VA Dental Longitudinal Study who had at least 1 second molar present at baseline and 2 or more triennial dental examinations between 1969 and 2007. We classified second molars by third-molar status in the same quadrant: unerupted, erupted, or absent. Tooth loss and alveolar bone loss were confirmed radiographically. Caries and restorations, calculus, and probing depth were assessed on each tooth. We estimated the hazards of second-molar loss with proportional hazards regression models for correlated data, controlling for age, smoking, education, absence of the first molar, and whole-mouth indices of calculus, caries, and periodontitis. The analysis included 966 men and 3024 second molar/first molar pairs. Follow-up was 22 ± 11 y (median 24, range 3-38 y). At baseline, 163 third molars were unerupted, 990 were erupted, and 1871 were absent. The prevalence of periodontitis on the second molars did not differ by third-molar status. The prevalence of distal caries was highest on the second molars adjacent to the erupted third molars and lowest on the second molars adjacent to the unerupted third molars. Relative to the absent third molars, adjusted hazards of loss of second molars were not significantly increased for those adjacent to erupted (hazard ratio [HR] = 0.96, 95% confidence interval [CI] = 0.79-1.16) or unerupted (HR = 1.25, 95% CI = 0.91-1.73) third molars. We found similar results when using alveolar bone loss as the periodontitis indicator. Our findings suggest that retained third molars are not associated with an increased risk of second-molar loss in adult men.

Complex Systems Model of Dynamic Mechanisms of Early Childhood Caries Development.

Early childhood caries (ECC) is a largely preventable condition that occurs when children develop caries in their primary teeth before the age of six. National trends of ECC indicate that prevalence is decreasing, but disparities between various sociodemographic groups may be increasing, despite intervention efforts. Dynamic mechanisms in caries development are hypothesized to be responsible for the observed population distributions of disease. Agent-based models (ABMs) have been utilized to explore similar hypotheses in many areas of health research. Therefore, we developed an ABM of ECC development mechanisms and examined population outcomes of hypothetical preventive intervention scenarios. We found that risk-based targeting had minimal impact on population averages or disparities and was largely due to the strength of the dynamic mechanisms among those considered to be at high caries risk. Universally increasing intervention access reduced population caries prevalence, but increased disparities between different groups of caries risk profiles. We show that population distributions of ECC can emerge as a result of dynamic mechanisms that have been shown to drive disease development. Understanding the effectiveness of a proposed intervention in relation to the hypothesized mechanism(s) that contributes to the outcome of interest is critical to future efforts to address population disparities in ECC.

Survey of Dental Researchers' Perceptions of Sexual Harassment at AADR Conferences: 2015 to 2018.

The American Association for Dental Research (AADR) is committed to providing a collegial, safe, and welcoming environment for all. As part of this effort, we assessed perceptions and experiences related to sexual, gender-based, and non-gender-based harassment among registrants at AADR annual meetings from 2015 to 2018 (n = 10,495); examined demographic factors associated with reported experiences; and identified facilitators and potential solutions concerning these types of harassment. Registrants were emailed an invitation to an anonymous online survey. Demographics were assessed categorically, and response distributions to close-ended survey items were evaluated by these variables. Bivariate analyses of participant demographics were conducted with 8 types of perceived harassment. To determine the demographic distribution of reporters, along with bivariate associations among them, restricted analyses were performed among individuals reporting any type of harassment. Qualitative data analysts conducted content analysis of the open-ended responses to questions asking participants to reflect on the topic. Peer debriefing was used to refine the coding schema. A total of 824 responses were received, of which 172 individuals reported experiencing ≥1 of the 8 types of harassment surveyed. Among those, reports of condescending remarks occurred most frequently (70%). Reported harassment of a more sexual nature was less common by comparison. Reporters of harassment were more likely to be women, members of the AADR/CADR (Canadian Association for Dental Research) divisions, and/or frequent meeting attendees. A total of 229 respondents answered at least 1 of the open-ended questions. While the majority of survey respondents reported no personal experience with harassment at AADR meetings, the fact that 1 in 5 did should be cause for concern. In 2018, AADR introduced a "Professional Conduct at Meetings Policy" delineating unacceptable behaviors, including intimidating or harassing speech and actions. Results of this survey form an important baseline from which its impact may be monitored to ensure that future AADR meetings are respectful, supportive, and safe environments for all.

Randomized Trial of Motivational Interviewing to Prevent Early Childhood Caries in Public Housing.

INTRODUCTION: Caries experience among preschool-age children has remained relatively unchanged for the past 2 decades, despite recently documented decreases in untreated decay. OBJECTIVES: In a community-based cluster-randomized controlled trial, a motivational interviewing (MI) intervention administered to primary caregivers was hypothesized to reduce caries increment over 2 y as compared with controls, among children aged 0 to 5 y at baseline living in public housing. METHODS: Public housing residents, who served as interventionists, were trained in MI with a focus on early childhood caries prevention. All 26 eligible public housing developments were randomized to either control (quarterly clinical examinations, fluoride varnish applications, toothbrush/toothpaste, and educational brochures) or intervention (same procedures as control plus MI counseling). Quarterly MI sessions were delivered in English or Spanish over 2 y, audio recorded, and assessed for treatment fidelity. The primary outcome was the increment in dmfs (decayed, missing, and filled tooth surfaces) as assessed by clinical examination at baseline, 12 mo, and 24 mo. Secondary outcomes included caregiver oral health knowledge and child oral health behaviors (child toothbrushing and sugar-sweetened beverage intake). Baseline characteristics were compared between groups and adjusted for housing-site clusters. Longitudinal outcomes were analyzed with mixed models. RESULTS: A total of 1,065 children (49% female, 55% non-White, 61% Hispanic, 89% below poverty level, n = 686 control) and their caregivers were enrolled. During 2 y of follow-up, the mean dmfs increment increased in both groups; however, there were no statistically significant group differences at 24 mo or group × time interactions. The mean increase in intervention caregivers' knowledge was significantly greater than that of control, F(2, 1,593) = 3.48, P = 0.0310, but there were no significant intervention effects on caregiver-reported child sugar-sweetened beverage intake or child toothbrushing. CONCLUSION: MI counseling plus intensive caries prevention activities resulted in knowledge increases but did not improve oral health behaviors or caries increment (ClinicalTrials.gov NCT01205971). KNOWLEDGE TRANSFER STATEMENT: When viewed in light of the findings from the companion Pine Ridge study and other recent MI studies, the results of this study suggest that when the complex disease of early childhood caries is addressed in high-risk populations, MI is not effective, and alternative approaches are warranted.

The inter-conversions of platinum carbonyl dianionic clusters, [Pt3(CO)6](n)2- (n = 2-5), in THF and acetonitrile. A combined in situ FTIR spectroscopic and BTEM study leading to the characterization of the new [H(4-x)Pt15(CO)19]x- (x = 2-4) clusters.

The inter-conversions of platinum carbonyl dianionic clusters, ([Pt(3)(CO)(6)](n)(2-), n = 2-5), have been studied in THF and acetonitrile using in situ FTIR spectroscopy. These inter-conversions were facilitated by the addition (or removal) of molecular hydrogen. The individual reactions, namely reductions and oxidations of [Pt(3)(CO)(6)](n)(2-) were fast and reversible. BTEM analysis of the data provided the pure component spectra of the individual species without the need for physical separation. It is shown, for the first time, that the species [Pt(3)(CO)(6)](n)(2-) (n = 2) can be formed from the reduction of [Pt(3)(CO)(6)](n)(2-) (n = 3-5) by hydrogen alone in acetonitrile. Also, detection of dissolved CO(2) in solution suggests that a room-temperature water gas shift reaction occurs. This has been shown to arise from nucleophilic attack of water on a coordinated CO of [Pt(3)(CO)(6)](n)(2-) which leads to the formation of [HPt(15)(CO)(19)](3-) and [H(2)Pt(15)(CO)(19)](2-). The parent tetraanion, [Pt(15)(CO)(19)](4-), has been isolated in high yields by reaction of [Pt(3)(CO)(6)](n)(2-) (n = 2, 3) with NaOH at 60 °C and has been structurally characterized by X-ray analysis.

Clay as thermoluminescence dosemeter in diagnostic radiology applications.

BACKGROUND: As part of efforts to isolate and utilize local and naturally occurring materials for development of thermoluminescece dosemeters and other technologies, an earlier report had shown that Nigerian clay showed prospects of utility as a thermoluminescence dosemeter (TLD). This paper reports the investigation of the basic thermoluminescence properties of clay at x-rays in the diagnostic radiology range, including dose monitoring in abdominal radiography. METHODOLOGY: Clay sourced from Calabar, Nigeria, was tested for thermoluminescence response after irradiation at diagnostic radiology doses, including application in abdominal radiography dose monitoring in a clinical setting. RESULTS: Results show that thermoluminescence (TL) output in natural clay is very low, but demonstrates enhanced performance with the addition of common salt. Specific TL characteristics of good repeatability for individual and batched pellets (variability index of 3.08%) and a high degree of trap emptying were observed. It had a glow curve peak at 275 degrees C; with traces of spurious thermoluminescence emission at the reader anneal temperature. There was evidence of good batch homogeneity (< 30%) and a similar pattern of dose absorption in abdominal radiography with commercial Lithium Fluoride (LiF TLD-100). A high fading rate (over 30% in twelve hours) and low sensitivity (12 times less than LiF TLD-100) however, signal the unacceptability of clay as a TLD in diagnostic radiology in the forms studied. CONCLUSION: Clay demonstrates poor TL response at diagnostic radiology doses. However, it's water absorbing property offers a means of overcoming the hygroscopic nature of common salt. This could be explored to improve the use of sodium chloride as a radiation detector.

Clay as Thermoluminescence Dosemeter in Diagnostic Radiology Applications

As part of efforts to isolate and utilize local and naturally occurring materials for development of thermoluminescece dosemeters and other technologies; an earlier report had shown that Nigerian clay showed prospects of utility as a thermoluminescence dosemeter (TLD). This paper reports the investigation of the basic thermoluminescence properties of clay at x-rays in the diagnostic radiology range; including dose monitoring in abdominal radiography. Clay sourced from Calabar; Nigeria; was tested for thermoluminescence response after irradiation at diagnostic radiology doses; including application in abdominal radiography dose monitoring in a clinical setting. Results show that thermoluminescence (TL) output in natural clay is very low; but demonstrates enhanced performance with the addition of common salt. Specific TL characteristics of good repeatability for individual and batched pellets (variability index of 3.08) and a high degree of trap emptying were observed. It had a glow curve peak at 275 C; with traces of spurious thermoluminescence emission at the reader anneal temperature. There was evidence of good batch homogeneity ( 30) and a similar pattern of dose absorption in abdominal radiography with commercial Lithium Fluoride (LiF TLD-100). A high fading rate (over 30in twelve hours) and low sensitivity (12 times less than LiF TLD-100) however; signal the unacceptability of clay as aTLD in diagnostic radiology in the forms studied. Clay demonstrates poor TL response at diagnostic radiology doses. However; it's water absorbing property offers a means of overcoming the hygroscopic nature of common salt. This could be explored to improve the use of sodium chloride as a radiation detector

Application of HMQC spectroscopy to the observation of the metal resonance in polymetallic compounds: the effect of multiple-metal spin transitions.

Multiple-metal spin transitions which distort the HMQC spectra of rhodium carbonyl clusters are discussed. These effects are seen whenever the detector nucleus, e.g. 13C or 31P, couples to more than one metal spin and are not restricted to detector ligands occupying edge- or face-bridging sites. These effects are illustrated in, but not limited to, the 13C-{103Rh} and 31P-{103Rh} HMQC spectra of [Rh6(CO)15L], (where L = P(4-F-C6H4)3), [Rh4(CO)11{P(OPh)3}], [Rh6C(CO)15]2- and [Rh2(carboxylate)2PPh3]. The effect is to modulate the intensity and position of the correlations in the metal dimension; cross peaks are displaced from the true chemical shift, additional cross peaks are seen and the intensity of the coherences varies as a function of the preparation delay, d2, and coupling constant, and may go to zero at the conventional value of 1/(2J). Analyses of the relevant spin systems are given together with experimental strategies to overcome these effects.

Field survey instrumentation and radioanalytical procedures for NORM.

The comprehensive monitoring and analysis of NORM is extremely difficult and involves a wide range of equipment and techniques. The instruments to be used can depend on both the national legislation of the country in which the measurements are being undertaken and the operational conditions under which they are carried out. These can dictate whether dose rate, alpha/beta contamination or gamma contamination measurements are taken. In some circumstances the total activity of the samples can be estimated using the gamma activities of the radionuclides present, while in others only full gamma and alpha spectral analysis will suffice.

Solid-state NMR studies of interstitial phosphorus atoms in rhodium carbonyl clusters.

Pure samples and as-prepared mixtures of Rh9 and Rh10 carbonyl clusters with interstitial P atoms have been studied quantitatively by 31P MAS and 1H-31P CP/MAS NMR. Information on the 31P chemical shift tensor of the Rh9 and Rh10 clusters has been derived from spinning sideband simulations. The chemical shift anisotropy is slightly larger in the Rh10 clusters (340-400 ppm) than in the Rh9 clusters (230-300 ppm), while the asymmetry parameters are similar (eta = 0.1-0.4). The results contribute to the understanding of the relationship between the shielding anisotropy and the structure of the cluster cavity.

Occupational x-ray exposure of anaesthetists.

Lithium fluoride thermoluminescent dosimeter chips were used to measure the radiation dose received by anaesthetists caused by the use of image intensification during a typical 4-week period in an orthopaedic theatre. These were used to estimate an annual dose, for comparison with dose limits, to ascertain if anaesthetists should be included in personnel monitoring services. Doses proved to be below detectable limits; hence anaesthetists are at minimal risk from occupational exposure to radiation. The orthopaedic theatre is believed to use more x-rays than other theatres, so exposure elsewhere should also be undetectable.

Repair of urethral diverticulum by plication.

OBJECTIVES: To develop a new technique to repair congenital and acquired megaurethra without opening the enlarged urethra. METHODS: A urethral plication similar to the Starr ureteral plication was developed, which allows the urethra to be plicated without opening into the lumen. This technique also allows the operation to be done in conjunction with hypospadias repairs. RESULTS: Eight of 10 patients had uneventful recoveries. One had obstruction and infection that resolved with drainage and antibiotics. A coronal margin fistula developed in a patient who had urethral plication as well as urethral advancement. CONCLUSIONS: This new urethral plication eliminates the need for opening the urethra and its associated complications while preserving urethral blood supply and allowing associated hypospadias repairs to be simultaneously performed.

Large iliac artery aneurysm masquerading as prostate cancer.

Vascular aneurysms can present with signs and symptoms of urological disease. We report on a 74-year-old man who underwent urological referral because of an abnormal prostate on rectal examination. Diagnostic evaluation revealed large, abdominal aortic and iliac artery aneurysms with prostate and bladder displacement.

Renal cell cancer tumor thrombi causing a massive pulmonary embolus in a 34-year-old man.

We describe a 34-year-old man who survived a massive pulmonary embolus caused by renal cell cancer tumor emboli. The literature and clinical presentation are discussed.

Analysis of chimeric mRNAs derived from the STE3 mRNA identifies multiple regions within yeast mRNAs that modulate mRNA decay.

In the yeast Saccharomyces cerevisiae unstable mRNAs decay 10-20 fold more rapidly than stable mRNAs. In order to examine the basis for the differences in decay rate of the unstable STE3 mRNA and the stable PGK1 and ACT1 mRNAs we have constructed and measured the decay rates of numerous chimeric mRNAs. These experiments indicate that multiple regions within yeast mRNAs are involved in modulating mRNA decay rates. Our results suggest that at least two regions within the STE3 mRNA are involved in stimulating rapid decay. One region is located within the coding region and requires sequences between codons 13 and 179. In addition, the STE3 3' UT can also function to stimulate decay. Surprisingly, the STE3 3' UT is not sufficient to accelerate the turnover of the stable PGK1 transcript unless portions of the PGK1 coding region are first deleted. These results not only identify sequences that function within yeast to stimulate mRNA turnover but also have important implications for an understanding of the basis of differences in eukaryotic mRNA decay rates.

Radiation: how real are the risks?

The risk from ionising radiations has recently been identified as being greater than it was previously thought to be. The data from which these new risk figures are drawn are outlined and their possible impact on the legislation controlling the use of ionising radiations is suggested. The likely new radiation dose limits are compared to the radiation doses which may be received in laboratories during normal operations using radionuclides, and the probable risk to arise from these doses is put into perspective.