Pregnancy and neonatal outcomes of COVID-19: coreporting of common outcomes from PAN-COVID and AAP-SONPM registries.

OBJECTIVE: Few large cohort studies have reported data on maternal, fetal, perinatal and neonatal outcomes associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in pregnancy. We report the outcome of infected pregnancies from a collaboration formed early during the pandemic between the investigators of two registries, the UK and Global Pregnancy and Neonatal outcomes in COVID-19 (PAN-COVID) study and the American Academy of Pediatrics (AAP) Section on Neonatal-Perinatal Medicine (SONPM) National Perinatal COVID-19 Registry. METHODS: This was an analysis of data from the PAN-COVID registry (1 January to 25 July 2020), which includes pregnancies with suspected or confirmed maternal SARS-CoV-2 infection at any stage in pregnancy, and the AAP-SONPM National Perinatal COVID-19 registry (4 April to 8 August 2020), which includes pregnancies with positive maternal testing for SARS-CoV-2 from 14 days before delivery to 3 days after delivery. The registries collected data on maternal, fetal, perinatal and neonatal outcomes. The PAN-COVID results are presented overall for pregnancies with suspected or confirmed SARS-CoV-2 infection and separately in those with confirmed infection. RESULTS: We report on 4005 pregnant women with suspected or confirmed SARS-CoV-2 infection (1606 from PAN-COVID and 2399 from AAP-SONPM). For obstetric outcomes, in PAN-COVID overall and in those with confirmed infection in PAN-COVID and AAP-SONPM, respectively, maternal death occurred in 0.5%, 0.5% and 0.2% of cases, early neonatal death in 0.2%, 0.3% and 0.3% of cases and stillbirth in 0.5%, 0.6% and 0.4% of cases. Delivery was preterm (< 37 weeks' gestation) in 12.0% of all women in PAN-COVID, in 16.1% of those women with confirmed infection in PAN-COVID and in 15.7% of women in AAP-SONPM. Extreme preterm delivery (< 27 weeks' gestation) occurred in 0.5% of cases in PAN-COVID and 0.3% in AAP-SONPM. Neonatal SARS-CoV-2 infection was reported in 0.9% of all deliveries in PAN-COVID overall, in 2.0% in those with confirmed infection in PAN-COVID and in 1.8% in AAP-SONPM; the proportions of neonates tested were 9.5%, 20.7% and 87.2%, respectively. The rates of a small-for-gestational-age (SGA) neonate were 8.2% in PAN-COVID overall, 9.7% in those with confirmed infection and 9.6% in AAP-SONPM. Mean gestational-age-adjusted birth-weight Z-scores were -0.03 in PAN-COVID and -0.18 in AAP-SONPM. CONCLUSIONS: The findings from the UK and USA registries of pregnancies with SARS-CoV-2 infection were remarkably concordant. Preterm delivery affected a higher proportion of women than expected based on historical and contemporaneous national data. The proportions of pregnancies affected by stillbirth, a SGA infant or early neonatal death were comparable to those in historical and contemporaneous UK and USA data. Although maternal death was uncommon, the rate was higher than expected based on UK and USA population data, which is likely explained by underascertainment of women affected by milder or asymptomatic infection in pregnancy in the PAN-COVID study, although not in the AAP-SONPM study. The data presented support strong guidance for enhanced precautions to prevent SARS-CoV-2 infection in pregnancy, particularly in the context of increased risks of preterm delivery and maternal mortality, and for priority vaccination of pregnant women and women planning pregnancy. Copyright © 2021 ISUOG. Published by John Wiley & Sons Ltd.

Measuring oral health impact among care home residents in Wales.

OBJECTIVE: To explore inequalities in oral health impact among care home residents using OHIP-14 and ADHS criteria. BASIC RESEARCH DESIGN: Cross-sectional survey with structured interview and clinical examination using 2009 ADHS criteria including OHIP-14. Comparisons were made between groups of residents and with findings from the ADHS 2009. PARTICIPANTS: Care homes and residents were randomly selected. Those without capacity and non-English/Welsh speakers were excluded. 447 residents answered all OHIP-14 questions and had full oral examination. MAIN OUTCOME MEASURE: OHIP-14. RESULTS: Reporting of OHIP problems was more common among care home residents compared with older people examined in the ADHS 2009 (50% vs 40%). There was no difference in the mean number of impacts between residents who were: dentate/edentate; denture wearing/non-denture wearing; with/without caries. Residents reporting 'problems and pain in your mouth at the moment', or 'occasional or more frequent dry mouth', more often experienced OHIP-14 impacts. CONCLUSION: Compared with peers living in the community, both dentate and edentate care home residents are more likely to live with one or more impacts. Two simple questions related to 'Any problems and pain in your mouth?' and 'Do you have frequent dry mouth?' may help to target care home residents more likely to experience oral health impacts.

Exercise testing and training in people with Huntington's disease.

OBJECTIVE: To explore exercise response in people with Huntington's disease (HD). DESIGN: Experimental observational study with a randomly allocated subgroup before/after interventional study. SETTING: Community. SUBJECTS: People with HD (n=30) and a healthy comparator group (n=20). Thirteen people from the HD group were randomly allocated to an exercise training program. MAIN MEASURES: Heart rate (HR) and perceived exertion on the Borg-CR10 scale (RPE) during a submaximal cycle ergometer exercise test (three minute unloaded and nine minute 65%-75%HRmaximum phase). Expired air and lactate measures were available for 8 people with HD during the exercise. INTERVENTION: A 12 week gym and home walking exercise programme (n=13). RESULTS: People with HD achieved a lower work rate at nine minutes (82±42(0-195) v 107±35(50 -185) Watts (p<0.05)), but higher RPE at both three (3±2(0-7) v 1±1(0-4)) and nine minutes (7±3(1-10) v 5± 2(2-9)) both p<0.01, compared to the healthy group and did not achieve a steady state HR during unloaded cycling. People with HD also demonstrated higher than expected lactate at three 2.5±2.5(1.1-8)mmo.L-1 and nine 3.8±1.9(1.2-6.6)mmo.L-1 minutes and respiratory exchange ratio at three 0.78±0.03 (0.74-0.81) and nine minutes 0.94±0.11(0.81-1.15). After exercise training there were no changes observed in HR or RPE responses during the exercise test. CONCLUSIONS: There was a large variability in the observed metabolic and physiological responses to exercise in people with HD. The observed exercise responses suggest that altered exercise prescription parameters may be required for people with HD and that exercise response and factors' affecting this requires further investigation.

A comparison of computer- and hand-generated clinical dental notes with statutory regulations in record keeping.

INTRODUCTION: Dental patient records should be of high quality, contain information to allow for good continuity of care and clinical defence (should the need ever arise) and, ideally, facilitate clinical audit. Handwritten dental records have been assessed for their compliance to statutory regulations, but the same cannot be levelled at computer-generated notes. This study aimed to compare and analyse the compliance of both methods of data recording with statutory regulations. METHOD: Fifty consecutive sets of handwritten notes and 50 sets of computer-generated notes were audited for compliance with a number of legal requirements and desirable characteristics for dental records and the results compared. The standard set for compliance with all characteristics was 100%. RESULTS: The computer-generated notes satisfied the set standard for 8 of the 11 legal requirements and three of six desirable characteristics. The handwritten notes satisfied the set standard for 1 of 11 legal requirements and none of the desirable characteristics. A statistical difference (using a 95% confidence interval) between the two methods was observed in 5 of 11 legal characteristics and three of six desirable characteristics, all of which were in favour of computer-generated notes. CONCLUSIONS: Within the limitations of this study, computer-generated notes achieved a much higher compliance rate with the set parameters, making defence in cases of litigation, continuity of care and clinical audit easier and more efficient.

Pregnancy and neonatal outcomes of COVID-19: The PAN-COVID study.

OBJECTIVE: To assess perinatal outcomes for pregnancies affected by suspected or confirmed SARS-CoV-2 infection. METHODS: Prospective, web-based registry. Pregnant women were invited to participate if they had suspected or confirmed SARS-CoV-2 infection between 1st January 2020 and 31st March 2021 to assess the impact of infection on maternal and perinatal outcomes including miscarriage, stillbirth, fetal growth restriction, pre-term birth and transmission to the infant. RESULTS: Between April 2020 and March 2021, the study recruited 8239 participants who had suspected or confirmed SARs-CoV-2 infection episodes in pregnancy between January 2020 and March 2021. Maternal death affected 14/8197 (0.2%) participants, 176/8187 (2.2%) of participants required ventilatory support. Pre-eclampsia affected 389/8189 (4.8%) participants, eclampsia was reported in 40/ 8024 (0.5%) of all participants. Stillbirth affected 35/8187 (0.4 %) participants. In participants delivering within 2 weeks of delivery 21/2686 (0.8 %) were affected by stillbirth compared with 8/4596 (0.2 %) delivering ≥ 2 weeks after infection (95 % CI 0.3-1.0). SGA affected 744/7696 (9.3 %) of livebirths, FGR affected 360/8175 (4.4 %) of all pregnancies. Pre-term birth occurred in 922/8066 (11.5%), the majority of these were indicated pre-term births, 220/7987 (2.8%) participants experienced spontaneous pre-term births. Early neonatal deaths affected 11/8050 livebirths. Of all neonates, 80/7993 (1.0%) tested positive for SARS-CoV-2. CONCLUSIONS: Infection was associated with indicated pre-term birth, most commonly for fetal compromise. The overall proportions of women affected by SGA and FGR were not higher than expected, however there was the proportion affected by stillbirth in participants delivering within 2 weeks of infection was significantly higher than those delivering ≥ 2 weeks after infection. We suggest that clinicians' threshold for delivery should be low if there are concerns with fetal movements or fetal heart rate monitoring in the time around infection. The proportion affected by pre-eclampsia amongst participants was not higher than would be expected, although we report a higher than expected proportion affected by eclampsia. There appears to be no effect on birthweight or congenital malformations in women affected by SARS-CoV-2 infection in pregnancy and neonatal infection is uncommon. This study reflects a population with a range of infection severity for SARS-COV-2 in pregnancy, generalisable to whole obstetric populations.

In vitro interaction of chronic wound bacteria in biofilms.

OBJECTIVE: To use in vitro biofilm models of wound bacterial isolates and compare the biofilms produced for different combinations of wound bacterial species. METHOD: In vitro biofilms, generated by Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus oralis and Micrococcus luteus in microtitre plates and a constant depth film fermentor (CDFF), were studied. The tested isolates all originated from chronic venous leg ulcers. Biofilms of individual and dual combinations of these species were generated in microtitre plate wells at 37°C for 24-96 hours and also in the CDFF for 7 days. The extent of biofilm formation from these systems was then measured using crystal violet staining and/or total viable counts. RESULTS: All the chronic wound bacteria formed biofilms (both individually and in mixed culture) in these models. In mixed species microtitre plate biofilms, both P. aeruginosa and S. aureus appeared to antagonise biofilm formation by S. oralis and M. luteus, with P. aeruginosa completely inhibiting the growth of these organisms. Similar effects were evident in the CDFF model, when all four bacterial species were added simultaneously, with M. luteus being 'out-competed' by the other organisms present and occurring at numbers at the limits of detection; however, there was an apparent increase in the numbers of S. oralis compared with its single culture equivalent. CONCLUSION: The study highlighted differences in biofilm formation ability for the tested species in both closed and open model systems. Using dual species biofilms, distinct species antagonism was observed with apparent antagonism of pathogenic species over 'commensal' ones. Such a finding provides insight into possible bacterial interactions during development of 'non-healing' wound biofilms.

A competing risk survival analysis model to assess the efficacy of filling carious primary teeth.

In recent years a strategy of selective, symptom-based intervention of carious primary teeth has been developed amongst some British general dental practitioners. Practice-based studies appear to provide evidence that policies of restoration of symptomless carious primary teeth do not confer any significant benefits above those associated with non-restorative care. However, results from these studies contrast with those of many clinical trials and prospective studies of primary molar restorations. In the current investigation, cohort study data from 5,168 carious primary molar teeth from 2,654 British children aged 4-5 years at baseline, augmented with Dental Practice Board treatment data, was utilised to assess the effect of restorative treatment on the likelihood of carious teeth subsequently progressing to either exfoliation or extraction. The effect of demographic and tooth level covariates on the fate of these teeth was also assessed. Multivariate multilevel parametric survival models were applied to the analysis of the carious-exfoliation and carious-extraction transitions to which the teeth were subject, assuming an underlying data hierarchy with teeth nested within individuals. Time of occurrence of caries affected survival experience, with teeth in which caries occurred later in life being associated with higher survival rates to extraction. Amongst filled teeth, later fillings were also associated with higher survival rates to extraction. Demographic and tooth level variables had a limited effect on survival experience. Treatment was found to be significantly associated with survival with respect to extraction, with survival rates of over 80% at 14 years, double those of untreated teeth.

Modelling childhood caries using parametric competing risks survival analysis methods for clustered data.

Caries in primary teeth is an ongoing issue in children's dental health. Its quantification is affected by clustering of data within children and the concurrent risk of exfoliation of primary teeth. This analysis of caries data of 103,776 primary molar tooth surfaces from a cohort study of 2,654 British children aged 4-5 years at baseline applied multilevel competing risks survival analysis methodology to identify factors significantly associated with caries occurrence in primary tooth surfaces in the presence of the concurrent risk of exfoliation, and assessed the effect of exfoliation on caries development. Multivariate multilevel parametric survival models were applied at surface level to the analysis of the sound-carious and sound-exfoliation transitions to which primary tooth surfaces are subject. Socio-economic class, fluoridation status and surface type were found to be the strongest predictors of primary caries, with the highest rates of occurrence and lowest median survival times associated with occlusal surfaces of children from poor socio-economic class living in non-fluoridated areas. The concurrent risk of exfoliation was shown to reduce the distinction in survival experience between different types of surfaces, and between surfaces of teeth from children of different socio-economic class or fluoridation status. Clustering of data had little effect on inferences of parameter significance.

Effects of soft-water acclimation on the physiology, swimming performance, and cardiac parameters of the rainbow trout, Oncorhynchus mykiss.

Rainbow trout acclimated to soft water were submitted to an incremental velocity trial, and exhibited a 14% decrease in critical swimming speed (U(crit) * 1.37 +/- 0.055 vs. 1.54 +/- 0.044 m s(-1)) compared to fish kept in hard water. After a standardized swimming protocol, soft-water-acclimated fish had higher blood lactate concentrations (6.5 +/- 0.66 and 6.0 +/- 0.64 mmol L(-1) (soft water) vs. 5.0 +/- 0.46 and 3.9 +/- 0.32 mmol L(-1) (hard water)), revealing a greater use of anaerobic metabolism for the same exercise. Cardiovascular parameters were investigated while fish were swimming at increasing water velocities, revealing that soft-water-acclimated fish had lower increases in heart rate (105% vs. 118% of pre-exercise values), due to higher heart rates observed during acclimation and during the first 10 min of the swimming trial. This was also reflected by the plateau in heart rate and stroke volume observed during the swimming protocol, which can be attributed to increased cardiovascular function in response to soft-water acclimation. These results are in accord with previously reported increases in blood-to-water diffusion distance, due to proliferation of chloride cells at the gills in response to soft-water conditions, and underscore the costs and limitations of soft-water acclimation.

Does the gender of the subject affect perceived smile aesthetics when varying the dimensions of maxillary lateral incisors?

Objective: To assess whether subject gender influences aesthetic opinion when altering the width of maxillary lateral incisors. Method: Photographs of a male and a female smile, displaying only the lips and teeth, were digitally altered to produce images where the maxillary lateral incisor was proportioned 52%, 57%, 62%, 67%, 72% and 77% in relation to the width of the maxillary central incisor. The image was then made symmetrical. One hundred participants (50 male and 50 female) were asked to rank each set of photographs from 'most' to 'least attractive'. Result: The 57% lateral incisor was considered the 'most attractive' with the 77% lateral incisor the 'least attractive' however no statistically significant difference existed with relation to subject or rater gender. Conclusion: Neither the 'golden proportion' nor the 'Recurrent Aesthetic Dental' ('RED') proportion was deemed the most attractive. As subject gender did not have a significant effect, dentists should work to create aesthetic results on an individual basis, operating within a so-called 'golden range'.

Fissure Seal or Fluoride Varnish? A Randomized Trial of Relative Effectiveness.

Fissure sealant (FS) and fluoride varnish (FV) are effective in preventing dental caries when compared with a no-treatment control. However, the relative clinical effectiveness of these interventions is uncertain. The objective of the study was to compare the clinical effectiveness of FS and FV in preventing dental caries in first permanent molars (FPMs) in 6- to 7-y-olds. The study design was a randomized clinical trial, with 2 parallel arms. The setting was a targeted-population program that used mobile dental clinics in schools located within areas of high social and economic deprivation in South Wales. A total of 1,016 children were randomized 1:1 to receive either FS or FV. Resin-based FS was applied to caries-free FPMs and maintained at 6-mo intervals. FV was applied at baseline and at 6-mo intervals for 3 y. The main outcome measures were the proportion of children developing caries into dentine (D4-6MFT) on any 1 of up to 4 treated FPMs after 36 mo. At 36 mo, 835 (82%) children remained: 417 in the FS arm and 418 in the FV arm. A smaller proportion of children who received FV ( n = 73, 17.5%) versus FS ( n = 82, 19.6%) developed caries into dentine on at least 1 FPM (odds ratio [OR] = 0.84; 95% CI, 0.59 to 1.21; P = 0.35), a nonstatistically significant difference between FS and FV treatments. The results were similar when the number of newly decayed teeth (OR = 0.86; 95% CI, 0.60 to 1.22) and tooth surfaces (OR = 0.85; 95% CI, 0.59 to 1.21) were examined. In a community oral health program, semiannual application of FV resulted in caries prevention that was not significantly different from that obtained by applying and maintaining FS after 36 mo (EudraCT: 2010-023476-23; ISRCTN: ISRCTN17029222).

Day-to-day variability of fasting plasma glucose in newly diagnosed type 2 diabetic subjects.

OBJECTIVE: To determine the day-to-day intraindividual variability of fasting plasma glucose (FPG) in newly diagnosed Caucasian type 2 diabetic subjects. RESEARCH DESIGN AND METHODS: A total of 193 newly diagnosed, previously untreated, Caucasian type 2 diabetic subjects (135 men, 58 women) had FPG measured on two consecutive days (FPG1, FPG2). Ethical approval and subjects' full informed consent were obtained. Subjects fasted for 12 h before each study day and rested for at least 30 min before blood was taken. Plasma glucose was analyzed by a glucose oxidase method with intra- and interassay coefficients of variation (CVs) < 2%. Variability of FPG was assessed by comparison of percentage differences (PDs): PD = 100 (FPG2 - FPG1)/FPG1, with averaged FPG (FPGaver = [FPG1 + FPG2]/2). Biological and analytical variability were determined by use of SD2total = SD2biological + SD2analytical, where SD2analytical approximately equal to 2 x (CVglucose measurement)2. Given normally distributed data with zero mean, 95% of daily percentage differences will be expected to fall within a range of +/- 2 SDtotal. RESULTS: Subjects were age 54 +/- 10 years (mean +/- SD) and had BMI of 29.3 +/- 5.3 kg/m2. FPG values for both days were 12.2 +/- 3.4 mmol/l (FPG1) and 12.1 +/- 3.3 mmol/l (FPG2), with a mean paired difference (95% CI) of 0.1 (0.0 to 0.3) mmol/l. The variance of these differences increased with increasing FPGaver. The PDs did not exhibit this effect and were normally distributed (mean -0.6% [-1.7 to 0.4]; SD 7.4% [6.8 to 8.3]), giving a 95% variability (2 SD) of 14.8%. Biological variability (2 SDbiological) was 13.7%. No significant difference in PD was found between men and women (mean difference 1.3% [-1.0 to 3.6]; SDmale 7.4%, SDfemale 7.3%; P = 0.62). CONCLUSIONS: A total of 95% of the FPG values for this group of newly diagnosed type 2 diabetic subjects varied within approximately +/- 15% on a daily basis, with approximately 14% caused by biological variability. As these results are expressed in percentage terms, subjects in the group with higher FPG values are likely to experience larger changes in FPG values measured from day to day. This variability should be considered when using FPG for the diagnosis and/or monitoring of response to treatment in patients with type 2 diabetes.

Determining true glomerular filtration status in newly presenting type 2 diabetic subjects using age and sex adjustment.

OBJECTIVE: To determine age- and sex-adjusted reference ranges (ASARRs) for glomerular filtration status using data from nondiabetic subjects and to apply these to newly presenting type 2 diabetic subjects. RESEARCH DESIGN AND METHODS: Glomerular filtration rate corrected for body surface area (cGFR) was determined using a radionuclide (51Cr-EDTA) method in 75 non-diabetic subjects (37 men, 38 women) and 219 type 2 diabetic subjects (157 men, 62 women). The 95% constant reference ranges (CRRs) were calculated as mean nondiabetic cGFR+/-1.96 SD. The 95% ASARRs were calculated by Altman's method from the nondiabetic cGFR versus age regression residuals for both male and female subjects. RESULTS: Using Altman's method, the intercepts, but not the gradients, of the cGFR versus age regressions were significantly different between male and female subjects (intercept difference [95% CI] 8.2 [1.3-15.1], gradient difference -0.4 [-1.1 to 0.3]). Fitting a common gradient, 95% ASARRs for normofiltration were found to be from 123.9 - (0.89 X age) to 181.7 - (0.89 x age) for male subjects, and from 116.0 - (0.89 X age) to 173.2 - (0.89 X age) for female subjects. The 95% CRR for normofiltration was 70.2-138.1 ml x min(-1) x (1.73 m)(-2). When applied to the diabetic cGFRs, the CRRs and ASARRs gave, respectively, 17% (37/219) versus 21% (46/219) hyperfiltrators and 83% (181/219) versus 79% (172/219) normofiltrators. Using the ASARRs, 14 normofiltrators (6 men, 8 women) were reclassified as hyperfiltrators (change [n/total n] [95% CI] 8% [14/181] [4-12]), and 5 hyperfiltrators (5 men, 0 women) were reclassified as normofiltrators (change 14% [5/37] [5-30]). CONCLUSIONS: We conclude that age and sex adjustment are essential to assess glomerular filtration status.

Pancreatic beta-cell responsiveness during meal tolerance test: model assessment in normal subjects and subjects with newly diagnosed noninsulin-dependent diabetes mellitus.

A model-based method was developed to quantify pancreatic beta-cell responsiveness during a meal tolerance test (MTT). C peptide secretion was related in a linear fashion to glucose concentration, whereas the standard population model was used to derive transfer rate constants of the two compartmental model of C peptide kinetics. Two indexes of pancreatic beta-cell responsiveness were defined: 1) postprandial sensitivity M(I) (ability of postprandial glucose to stimulate beta-cell), and 2) basal sensitivity M0 (ability of fasting glucose to stimulate beta-cell). The method was evaluated using plasma glucose and C peptide measured over 180 min with a 10- to 30-min sampling interval during a MTT (75 g carbohydrates; 500 Cal) performed in 16 normal subjects (7 men and 9 women; age, 50 +/- 10 yr; body mass index, 29.2 +/- 3.6 kg/m2; fasting plasma glucose, 5.1 +/- 0.5 mmol/L; mean +/- SD) and 16 body mass index-matched subjects with newly diagnosed noninsulin-dependent diabetes mellitus (NIDDM; 15 men and 1 woman; age, 50 +/- 9 yr; body mass index, 29.3 +/- 3.7 kg/m2; fasting plasma glucose, 12.6 +/- 3.2 mmol/L). M(I) and M0 indexes were estimated with very good precision (coefficient of variation, < 15%). Subjects with NIDDM demonstrated lower postprandial sensitivity M(I) (17.7 +/- 11.4 vs. 90.0 +/- 43.3 x 10(-9)/min; NIDDM vs. normal, P < 0.001) and basal sensitivity M0 (5.4 +/- 2.2 vs. 10.3 +/- 4.9 x 10(-9)/min; P < 0.005). Deconvolution analysis documented that the relationship between C peptide secretion and glucose concentration is approximately linear during MTT in both normal subjects (plasma glucose range, 5-8 mmol/L) and subjects with NIDDM (12-17 mmol/L). We conclude that pancreatic responsiveness during glucose stimulation (M(I)) and under basal conditions (M0) can be obtained from this novel method during MTT in healthy and disease states.

Protection by two complexing agents, thiosulphate and dissolved organic matter, against the physiological effects of silver nitrate to rainbow trout (Oncorhynchus mykiss) in ion-poor water.

Adult rainbow trout (Oncorhynchus mykiss) were exposed in ion-poor water ( approximately 50 microM Ca) to silver added as AgNO(3) or to AgNO(3) plus either thiosulphate (Na(2)S(2)O(3)) or dissolved organic matter (DOM). The effects of these exposures were assessed through repetitive blood sampling over 4 days. Trout exposed to 0.1 microM AgNO(3) alone accumulated large amounts of Ag on their gills and in their plasma, showed progressive losses of plasma Na and Cl, and had elevated concentrations of plasma glucose. In one set of exposures trout exposed to AgNO(3) alone also had increased cough rates, slightly higher ventilation rates, somewhat lower arterial oxygen tensions, and increased blood lactate concentrations. In contrast, trout exposed to 0.1 microM AgNO(3) plus 5 microM thiosulphate or 35 mg C l(-1) DOM accumulated less Ag on their gills and in their plasma, and showed no adverse ionoregulatory or respiratory effects due to Ag. These results demonstrate ionoregulatory and sometimes respiratory effects in fish exposed to ionic Ag(+) in ion-poor water, depending on water chemistry, and demonstrate the protective effects of synthetic and natural complexing agents through a reduction in the amount of ionic Ag(+) available to bind at the gills.

Interaction of cadmium toxicity in embryos and larvae of zebrafish (Danio rerio) with calcium and humic substances.

The influence of humic substances (HS) and calcium (Ca) on cadmium (Cd) toxicity was determined using zebrafish (Danio rerio). Embryo and larvae of the zebrafish were exposed to various Cd concentrations (1.8; 2.8; 4.2; 6.2; 9.3 mg/l Cd) for 144 h. Combinations of low (0.2 mmol/l) and high (2 mmol/l) Ca, +HS (5 mg/l C) or -HS were used during Cd exposure. The toxicity of Cd was affected by (1) exposure concentration; (2) exposure time; (3) presence of HS; and (4) the Ca concentration. The results show that Ca and HS protect against Cd toxicity in zebrafish embryos. The best protection was in the high Ca-HS group, followed by high Ca+HS group and low Ca+HS group. The survival in the low Ca-HS group was the worse. Survival in the high Ca-HS group and the high Ca+HS group was similar with the exception of the highest Cd concentration (9.3 mg/l) where the survival of the high Ca+HS group was less than in the high Ca-HS group. The exposure system was modelled using a chemical equilibrium program (MINEQL+) to determine if the likely mechanism causing the anomalous result in the highest Cd concentration. The equilibrium model cannot explain these results, which suggests that this effect has a kinetic basis, such as time needed for Cd to displace Ca already bound by HS.

Cobalt binding to gills of rainbow trout (Oncorhynchus mykiss): an equilibrium model.

Rainbow trout (Oncorhynchus mykiss, 1-5 g) were exposed to approximately 7.5 microM Co in soft water for 2-3 hr at pH approximately 6.5. The water contained either complexing ligands such as nitrilotriacetic acid and natural dissolved organic matter (DOM) or competing cations such as Ca, Na, or H. After exposure, gills were excised and analyzed for total bound Co using a graphite furnace atomic absorption spectrophotometer. A Langmuir isotherm was used to calculate the conditional equilibrium binding constant (K) for Co binding to trout gills plus the concentrations of gill Co binding sites. The calculated binding constant for Co to trout gills was log KCo-gillCo = 5.1, with 88 nmol Co binding sites per g of wet gill tissue. Conditional equilibrium binding constants were also calculated for Ca, Na, and H binding to the gill Co sites and for Co binding to DOM. The experimentally determined binding constants were entered into an aquatic equilibrium chemistry program, MINEQL+, to predict Co binding by fish gills. Predicted and observed results indicate that Co would not accumulate on or in gills of trout held in a series of natural and 1:1 diluted natural waters supplemented with approximately 8.7 microM Co. Model analysis of the reasons for Co being kept off gills of trout held in natural waters indicated that Ca competition and DOM complexation were the most important factors in preventing Co binding by trout gills.

Adding magnesium to the silver-gill binding model for rainbow trout (Oncorhynchus mykiss).

Rainbow trout (Oncorhynchus mykiss; 2-17 g) were exposed to approximately 0.1 microM silver as AgNO3 for 3 to 4 h in synthetic, ion-poor water (20 microM Ca, 100 microM Na, 150 microM Cl, pH 7) to which was added Mg, Ca, or thiosulfate (S2O3). Gills were extracted and assayed for Ag using graphite furnace atomic absorption spectrophotometry. Up to 210 mM Mg (fourfold the concentration of Mg in seawater) did not reduce accumulation of Ag by trout gills. The conditional equilibrium stability constant (K) for Mg at silver-binding sites on the gills was calculated to be log K(Mg-gillAg) = 3.0, or approximately half-as-strong binding as for Ca at these sites. The inclusion of the Mg-gill stability constant into the original Ag-gill binding model increases the flexibility of the model, although the competitive effects of Mg are only important in sodium-poor systems.

Effects of natural organic matter source on reducing metal toxicity to rainbow trout (Oncorhynchus mykiss) and on metal binding to their gills.

Juvenile rainbow trout (Oncorhynchus mykiss, 3 g) were exposed for 74 h in ion-poor (soft) water to a mixed-metal solution in the presence of 4, 6, and 10 mg C/L natural organic matter (NOM). The metals were 0.2 microM Pb, 0.1 microM Hg, 0.1 microM Cd, 1.3 microM Cu, 0.05 microM Ag, and 3.5 microM Co, and the natural organic matter was isolated by reverse osmosis from three sources in southern Ontario, Canada. The six-metal solution alone was extremely toxic to the fish. Increasing concentrations of each NOM increased trout survival, but the NOM having the most allochthonous properties (from Luther Marsh) increased fish survival most, while the NOM having the most autochthonous properties (from Sanctuary Pond, Point Pelee) increased fish survival least. This pattern was reflected in the degree of reduction of Pb and Cu accumulation by the gills. Relatively simple chemical characterization of NOM, such as protein-to-carbohydrate ratios, or optical characterization, such as absorbance-to-fluorescence ratios (e.g., representing aromaticity), may adequately reflect these biologically relevant differences in organic matter quality.

Preparing for practice - calibration of dental undergraduate students in the Index of Orthodontic Treatment Need.

OBJECTIVES: The aim of this study was to establish the success in calibrating dental students in the use of the Index of Orthodontic Treatment Need (IOTN). DESIGN: Single-centre, evaluation of teaching study. SETTING: University department, UK, 2013. SUBJECTS AND METHOD: Third-year dental students were divided into four groups and received IOTN instruction via clinical and non-clinical teaching over a three-month period. This was followed by a calibration exercise where the whole year assessed 30 study models for orthodontic treatment need using the dental health component (DHC) and modified aesthetic component (AC) of the IOTN. MAIN OUTCOME MEASURES: Student IOTN scores were compared to a gold standard using kappa statistics (κ). RESULTS: Results showed that although substantial agreement was achieved in both the DHC (κ = 0.65) and a modified AC (unweighted κ = 0.63), the year only calibrated successfully in the DHC. CONCLUSION: Third year dental students taught at Cardiff University applied the DHC of IOTN better than the AC.