Investigation and monitoring of heavy metal poisoning.

Historically, heavy metal measurement and interpretation has been a highly specialised area performed only in a handful of centres within the UK. However, recent years have seen a move to more local testing due to the repatriation of referred work into pathology networks and the increased availability of inductively coupled plasma mass spectrometry technology. While management of significant poisoning is still overseen by tertiary care poisoning specialists, management of milder cases may be undertaken locally.Non-specialist clinical scientists and clinicians need to know when heavy metal testing is appropriate, which samples are required (and any specific requirements around collection) and how to interpret and act on the results.This Best Practice article provides guidance on the investigation and monitoring of the toxic elements most frequently encountered in general medical practice; lead, mercury and arsenic. It is intended as a reference guide for the non-specialist and as a comprehensive summary for clinical toxicologists and clinical scientists.

Effect of a test-and-treat approach to vitamin D supplementation on risk of all cause acute respiratory tract infection and covid-19: phase 3 randomised controlled trial (CORONAVIT).

OBJECTIVE: To determine the effect of population level implementation of a test-and-treat approach to correction of suboptimal vitamin D status (25-hydroxyvitamin D (25(OH)D) <75 nmol/L) on risk of all cause acute respiratory tract infection and covid 19. DESIGN: Phase 3 open label randomised controlled trial. SETTING: United Kingdom. PARTICIPANTS: 6200 people aged ≥16 years who were not taking vitamin D supplements at baseline. INTERVENTIONS: Offer of a postal finger prick test of blood 25(OH)D concentration with provision of a six month supply of lower dose vitamin D (800 IU/day, n=1550) or higher dose vitamin D (3200 IU/day, n=1550) to those with blood 25(OH)D concentration <75 nmol/L, compared with no offer of testing or supplementation (n=3100). Follow-up was for six months. MAIN OUTCOME MEASURES: The primary outcome was the proportion of participants with at least one swab test or doctor confirmed acute respiratory tract infection of any cause. A secondary outcome was the proportion of participants with swab test confirmed covid-19. Logistic regression was used to calculate odds ratios and associated 95% confidence intervals. The primary analysis was conducted by intention to treat. RESULTS: Of 3100 participants offered a vitamin D test, 2958 (95.4%) accepted and 2674 (86.3%) had 25(OH)D concentrations <75 nmol/L and received vitamin D supplements (n=1328 lower dose, n=1346 higher dose). Compared with 136/2949 (4.6%) participants in the no offer group, at least one acute respiratory tract infection of any cause occurred in 87/1515 (5.7%) in the lower dose group (odds ratio 1.26, 95% confidence interval 0.96 to 1.66) and 76/1515 (5.0%) in the higher dose group (1.09, 0.82 to 1.46). Compared with 78/2949 (2.6%) participants in the no offer group, 55/1515 (3.6%) developed covid-19 in the lower dose group (1.39, 0.98 to 1.97) and 45/1515 (3.0%) in the higher dose group (1.13, 0.78 to 1.63). CONCLUSIONS: Among people aged 16 years and older with a high baseline prevalence of suboptimal vitamin D status, implementation of a population level test-and-treat approach to vitamin D supplementation was not associated with a reduction in risk of all cause acute respiratory tract infection or covid-19. TRIAL REGISTRATION: ClinicalTrials.gov NCT04579640.

Level of adherence to vitamin D supplementation guidelines in an antenatal centre in Birmingham, UK, and its effect on biochemical and obstetrical outcomes: a single-centre cross-sectional study.

OBJECTIVES: A third of pregnant women in the UK are vitamin D deficient, which may confer deleterious consequences, including an increased risk of pre-eclampsia, gestational diabetes mellitus and intrauterine growth restriction. This study aims to determine the proportion of women that met National Institute for Health and Care Excellence (NICE) standards for vitamin D supplementation in pregnancy and compare biochemical and obstetrical outcomes according to supplementation status. DESIGN AND SETTING: This is a single-centre cross-sectional study in an antenatal centre in Birmingham, UK. Participants received a questionnaire regarding their experiences with vitamin D supplementation during their pregnancy with their general practitioner. Serum 25-hydroxyvitamin D and bone profile results were obtained during the same appointment and obstetrical outcomes were collected retrospectively once participants had delivered. RESULTS: 41.8% of participants (n=61) received written and/or verbal advice about supplementation, (NICE standards=100%). 72.6% (n=106) had one or more risk factors for vitamin D deficiency, of which 38.7% (n=41, NICE standards=100%) were asked about supplementation. Among those asked, 85.4% (n=41, NICE standards=100%) received the correct dosage. Compared with the supplementation group, the non-supplementation group had offspring that were 1.40 cm (95% CI 0.01 to 2.80, p=0.04) longer at birth; which was significant after adjusting for confounding factors. No significant differences in any biochemical parameters were observed between supplementation categories (p>0.05). CONCLUSIONS: Adherence to NICE standards was suboptimal. This may be attributed to insufficient training for general practitioners on the importance of supplementation, causing them to underestimate the consequences of gestational vitamin D deficiency. Recommendations include implementing a mandatory screening tool to identify 'at-risk' women and providing more clinician training to ensure that supplementation during pregnancy is standard of care.

Hypertension is the major predictor of poor outcomes among inpatients with COVID-19 infection in the UK: a retrospective cohort study.

OBJECTIVE: To assess the impact of diabetes, hypertension and cardiovascular diseases on inpatient mortality from COVID-19, and its relationship to ethnicity and social deprivation. DESIGN: Retrospective, single-centre observational study SETTING: Birmingham, UK. PARTICIPANTS: 907 hospitalised patients with laboratory-confirmed COVID-19 from a multi-ethnic community, admitted between 1 March 2020 and 31 May 2020. MAIN OUTCOME MEASURES: The primary analysis was an evaluation of cardiovascular conditions and diabetes in relation to ethnicity and social deprivation, with the end-point of inpatient death or death within 30 days of discharge. A multivariable logistic regression model was used to calculate HRs while adjusting for confounders. RESULTS: 361/907 (39.8%) died in hospital or within 30 days of discharge. The presence of diabetes and hypertension together appears to confer the greatest mortality risk (OR 2.75; 95% CI 1.80 to 4.21; p<0.001) compared with either condition alone. Age >65 years (OR 3.32; 95% CI 2.15 to 5.11), male sex (OR 2.04; 95% CI 1.47 to 2.82), hypertension (OR 1.69; 95% CI 1.10 to 2.61) and cerebrovascular disease (OR 1.87; 95% CI 1.31 to 2.68) were independently associated with increased risk of death. The mortality risk did not differ between the quintiles of deprivation. High-sensitivity troponin I was the best predictor of mortality among biomarkers (OR 4.43; 95% CI 3.10 to 7.10). Angiotensin-receptor blockers (OR 0.57; 95% CI 0.33 to 0.96) and ACE inhibitors (OR 0.65; 95% CI 0.43 to 0.97) were not associated with adverse outcome. The Charlson Index of Comorbidity scores were significantly higher in non-survivors. CONCLUSIONS: The combined prevalence of hypertension and diabetes appears to confer the greatest risk, where diabetes may have a modulating effect. Hypertension and cerebrovascular disease had a significant impact on inpatient mortality. Social deprivation and ethnicity did not have any effect once the patient was in hospital.

Comparison of 25-hydroxyvitamin D concentration in chimpanzee dried blood spots and serum.

BACKGROUND: Dried blood spots (DBS) are used in human medicine to measure total 25-hydroxyvitamin D (25-OHD) in the blood. However, this easy and affordable sampling technique has not been evaluated in primates to measure vitamin D concentrations. OBJECTIVES: We aimed to compare 25-OHD measurements in chimpanzee serum at two different laboratories and determine the precision and accuracy of the DBS method by comparing DBS and serum results. METHODS: Blood samples from 17 captive chimpanzees were collected, and 25-OHD3 and 25-OHD2 were measured in serum at two accredited laboratories using liquid chromatography-tandem mass spectrometry. The same analytes were measured on DBS cards, and results were compared with that of serum. Data were assessed using the Spearman correlation, Deming regression, and Bland-Altman analyses. RESULTS: The correlation coefficient between the two measurements in serum was rs  = .51 (P = .04), and the mean bias was -1.25 ± 14.83. When comparing 25-OHD concentrations measured in DBS and serum at the same laboratory, the rs was 0.7 (P = .002), and the mean bias was 1.42 ± 14.58. Estimated intra-assay and inter-assay coefficients of variation for DBS results were 6% and 12.6%, respectively. CONCLUSIONS: Although substantial analytical variability was found in 25-OHD measurements regardless of the sample type, the identification of both constant and proportional error and wider limits of agreement with the DBS technique makes the interpretation of DBS results challenging, especially for values close to clinical cut-off points. The DBS and serum methods were not interchangeable, and further studies are needed to validate DBS samples for vitamin D measurements in chimpanzees.

Serum trough infliximab and anti-infliximab antibodies in a cohort of gastroenterology and rheumatology patients' infliximab therapeutic drug monitoring.

BACKGROUND: Infliximab, a monoclonal antibody directed against tumour necrosis factor, is widely used in the treatment of chronic inflammatory conditions including Crohn's disease and rheumatoid arthritis. Its use is limited by development of anti-infliximab antibodies, which can lead to loss of therapeutic efficacy. Serum infliximab and anti-infliximab antibody measurements have recently become routinely available in the UK. The study aimed to assess the clinical utility of antibodies as an adjunct to trough infliximab. METHODS: Serum trough infliximab was measured in 201 samples from 108 gastroenterology and rheumatology patients on maintenance infliximab therapy. Results were correlated with C-reactive protein concentrations. Total anti-infliximab antibodies were measured in 164 samples. RESULTS: The median (25th-75th percentile) trough infliximab was 3.7 µg/mL (1.2-5.2 µg/mL) and 23% of samples had a concentration ≤1 µg/mL. A notable proportion had positive anti-infliximab antibodies: 84/164 (51%), which subdivided to 85% and 28% with infliximab ≤1 and >1 µg/mL, respectively.Serum C-reactive protein was found to be significantly higher where infliximab was ≤1 compared to >1 µg/mL (10 mg/L [<5-24 mg/L] vs. <5 mg/L [<5-8 mg/L], P < 0.01), although a strict correlation was not observed. The relationship between trough infliximab and C-reactive protein differed depending on antibody status and there was no association between C-reactive protein and the presence or absence of antibodies. CONCLUSION: Our findings support measurement of anti-infliximab antibodies only in the context of low infliximab concentrations <1 µg/mL. A higher therapeutic cut-off may be relevant in patients with negative antibodies. Further work is indicated to investigate the clinical significance of positive antibodies with therapeutic infliximab concentrations.

An evaluation of measured and calculated serum free cortisol in a group of patients with known adrenal suppression.

BACKGROUND: Since more than 90% of cortisol is bound to protein, serum free cortisol (SFC) may be a more appropriate marker of adrenal status than total cortisol. However, measurement of SFC is technically difficult and calculated SFC may offer a more practical alternative. METHODS: SFC, measured by equilibrium dialysis coupled with immunoassay, and calculated using Coolens' equation from total cortisol and corticosteroid binding globulin (CBG) concentrations, was compared in short Synacthen test (SST) serum from 42 patients, of whom 20 demonstrated a suppressed adrenal response. RESULTS: Considering the patient group as a whole, calculated SFC was found to be significantly lower than measured SFC, pre- and post-Synacthen (P < 0.05 and <0.001, respectively). Upon classifying the patients as pass or fail based on total cortisol response to Synacthen, the difference in calculated and measured SFC only reached statistical significance for post-Synacthen concentrations in the pass group (P < 0.01), suggesting a greater discrepancy at higher cortisol concentrations. There was no difference in CBG levels between the pass and fail groups and both measured and calculated SFC gave a diminished 30 min response in subjects deemed to have failed the SST. CONCLUSION: Coolens' equation was found to underestimate measured SFC in this cohort of outpatients, as has been previously demonstrated, particularly in patients with a pronounced acute phase response. Although calculated SFC gave a diminished response in individuals deemed to have failed the SST, the concentration-dependent nature of the discrepancy may limit the usefulness of this method for assessing adrenal status.

A study to examine patient adherence to wearing 24-hour forearm thermoplastic splints after tendon repairs.

Adherence is believed to be essential in ensuring a successful clinical outcome. There is a paucity of research available investigating adherence and the effect of nonadherence in hand therapy. This study was conducted to investigate adherence relating to acute hand flexor and extensor tendon injuries. This exploratory descriptive study used a self-report questionnaire. Eighty subjects were recruited four weeks after flexor or extensor tendon repair to complete the anonymous questionnaire. Descriptive statistics were used to analyze the patient group profile. Chi-square test was used to determine any associations between patient profile and adherence. Seventy-six questionnaires were completed and this constitutes a return rate of 95%. Sixty-seven percent of patients reportedly removed their splints, commonly to wash and dress. No significant correlation (p < or = 0.0001) was found between patient profile and nonadherence. Two thirds (67%) of patients report to being nonadherent to their splinting regime, removing their splint after flexor and extensor tendon repairs.

Application of power spectra patterns in Fourier transform square wave voltammetry to evaluate electrode kinetics of surface-confined proteins.

This paper describes an application of Fourier transform (FT) voltammetry that provides a quantitative evaluation of the electron-transfer kinetics of protein molecules attached to electrode surfaces. The potential waveform applied in these experiments consists of a large-amplitude square wave of frequency f superimposed onto the traditional triangular voltage used in dc cyclic voltammetry. The resultant current-time response, when Fourier transformed into the frequency domain, provides patterns of data at the even harmonic frequencies that arise from nonlinearity in the Faradaic response. These even harmonic contributions are ideally suited for kinetic evaluation of electron-transfer processes because they are highly selective to quasi-reversible behavior (insensitive to reversible or irreversible processes) and almost devoid of background charging current. Inverse FT methods can then be used to provide the wave shapes of the dc as well as the ac voltammetric components and other characteristics employed to detect the level of nonideality present relative to theoretical models based upon noninteracting surface-confined molecules. The new form of data evaluation has been applied to the electron-transfer properties of a typical biological electron carrier, the blue copper protein azurin, immobilized on polycrystalline gold electrodes modified with self-assembled monolayers of different length alkanethiols. Details of the electrode kinetics (rates of electron transfer, dispersion, and charge-transfer coefficients) as a function of alkanethiol, apparent surface coverage, and capacitance are all deduced from the square wave (FT-inverse FT) protocol, and the implications of these findings are considered.

Fast, long-range electron-transfer reactions of a "blue" copper protein coupled non-covalently to an electrode through a stilbenyl thiolate monolayer.

A self-assembled monolayer (SAM), formed by the insitu saponification of a stilbenyl thioacetate on a gold electrode, yields fast electron transfer (ET)(the exchange rate at zero driving force exceeds 1600 s-1) with adsorbed molecules of the blue copper protein, azurin, over a distance exceeding 15 angstroms .

Voltammetry of a "protein on a rope".

A periplasmic electron-transfer protein, cytochrome c(555)(m) from Aquifex aeolicus contains a 62-residue N-terminal extension by which it is anchored to the membrane--most probably via a thioester bond to its N-terminal cysteine. This linker can act as a "rope" to tether the protein close to its reaction partners. Mimicking this principle, a recombinant cytochrome c(555)(m), expressed in Escherichia coli, has been attached covalently to a gold electrode modified with 6-mercaptohexan-1-ol. The "tethered" cytochrome c(555)(m) displays remarkably fast electron-transfer kinetics, with an electrochemical exchange rate constant k(0) of 1.4 x 10(4) s(-1). The results show that fast electron transfer is associated with weak interactions: importantly, the tethered cytochrome can explore many different orientations without escaping into solution.