Quantitative susceptibility mapping of the normal-appearing white matter as a potential new marker of disability progression in multiple sclerosis

OBJECTIVES

To investigate the normal-appearing white matter (NAWM) susceptibility in a cohort of newly diagnosed multiple sclerosis (MS) patients and to evaluate possible correlations between NAWM susceptibility and disability progression.

METHODS

Fifty-nine patients with a diagnosis of MS (n = 53) or clinically isolated syndrome (CIS) (n = 6) were recruited and followed up. All participants underwent neurological examination, blood sampling for serum neurofilament light chain (sNfL) level assessment, lumbar puncture for the quantification of cerebrospinal fluid (CSF) β-amyloid1-42 (Aβ) levels, and brain MRI. T2-weighted scans were used to quantify white matter (WM) lesion loads. For each scan, we derived the NAWM volume fraction and the WM lesion volume fraction. Quantitative susceptibility mapping (QSM) of the NAWM was calculated using the susceptibility tensor imaging (STI) suite. Susceptibility maps were computed with the STAR algorithm.

RESULTS

Primary progressive patients (n = 9) showed a higher mean susceptibility value in the NAWM than relapsing-remitting (n = 44) and CIS (n = 6) (p = 0.01 and p = 0.02). Patients with a higher susceptibility in the NAWM showed increased sNfL concentration (ρ = 0.38, p = 0.004) and lower CSF Aβ levels (ρ = -0.34, p = 0.009). Mean NAWM susceptibility turned out to be a predictor of the expanded disability status scale (EDSS) worsening at follow-up (β = 0.41, t = 2.66, p = 0.01) and of the MS severity scale (MSSS) (β = 0.38, t = 2.43, p = 0.019).

CONCLUSIONS

QSM in the NAWM seems to predict the EDSS increment over time. This finding might provide evidence on the role of QSM in identifying patients with an increased risk of early disability progression.

KEY POINTS

• NAWM-QSM is higher in PPMS patients than in RRMS. • NAWM-QSM seems to be a predictor of EDSS worsening over time. • Patients with higher NAWM-QSM show increased sNfL concentration and lower CSF Aβ levels.

Cortical lesions at diagnosis predict long-term cognitive impairment in multiple sclerosis: A 20-year study

BACKGROUND AND PURPOSE

Although cognitive impairment (CI) is frequent in multiple sclerosis (MS) patients, few studies (and with conflicting results) have evaluated early predictors of CI in the long term. We aimed at determining associations between early clinical/neuroradiological variables with reference to CI after 20 years of MS.

METHODS

We investigated in 170 MS patients the relationship between clinical/magnetic resonance imaging (MRI) data at diagnosis and cognitive status almost 20 years after MS onset. Among others, number and volume of both white matter lesions (WMLs) and cortical lesions (CLs) were evaluated at diagnosis and after 2 years. All MS patients were followed over time and underwent a comprehensive neuropsychological assessment at the end of study. Advanced statistical methods (unsupervised cluster analysis and random forest model) were conducted.

RESULTS

CI patients showed higher focal cortical pathology at diagnosis compared to cognitively normal subjects (p < 0.001). Volumes of both WMLs and CLs emerged as the MRI metrics most associated with long-term CI. Moreover, number of CLs (especially ≥3) was also strongly associated with long-term CI (≥3 CLs: odds ratio [OR] = 3.7, 95% confidence interval = 1.8-7.5, p < 0.001), more than number of WMLs; the optimal cutoff of three CLs (area under the curve = 0.67, specificity = 75%, sensitivity = 55%) was estimated according to the risk of developing CI.

CONCLUSIONS

These results highlight the impact of considering both white and gray matter focal damage from early MS stages. Given the low predictive value of WML number and the poor clinical applicability of lesion volume estimation in the daily clinical context, the evaluation of number of CLs could represent a reliable prognostic marker of CI.

Immune Response after COVID-19 mRNA Vaccination in Multiple Sclerosis Patients Treated with DMTs

The impact of disease-modifying therapies (DMTs) on the immune response to coronavirus disease-2019 (COVID-19) vaccines in persons with multiple sclerosis (pwMS) needs further elucidation. We investigated BNT162b2 mRNA COVID-19 vaccine effects concerning antibody seroconversion, inflammatory mediators' level and immunophenotype assessment in pwMS treated with cladribine (c-pwMS, n = 29), fingolimod (f-pwMS, n = 15) and ocrelizumab (o-pwMS, n = 54). Anti-spike immunoglobulin (Ig)-G detection was performed by an enzyme immunoassay; molecular mediators (GrB, IFN-γ and TNF-α) were quantified using the ELLA platform, and immunophenotype was assessed by flow cytometry. ANCOVA, Student's t-test and Pearson correlation analyses were applied. Only one o-pwMS showed a mild COVID-19 infection despite most o-pwMS lacking seroconversion and showing lower anti-spike IgG titers than c-pwMS and f-pwMS. No significant difference in cytokine production and lymphocyte count was observed in c-pwMS and f-pwMS. In contrast, in o-pwMS, a significant increase in GrB levels was detected after vaccination. Considering non-seroconverted o-pwMS, a significant increase in GrB serum levels and CD4+ T lymphocyte count was found after vaccination, and a negative correlation was observed between anti-spike IgG production and CD4+ T cells count. Differences in inflammatory mediators' production after BNT162b2 vaccination in o-pwMS, specifically in those lacking anti-spike IgG, suggest a protective cellular immune response.

Imaging Characteristics of Choroid Plexuses in Presymptomatic Multiple Sclerosis: A Retrospective Study

Background and Objectives

Recent imaging studies have suggested a possible involvement of the choroid plexus (CP) in multiple sclerosis (MS). Here, we investigated whether CP changes are already detectable at the earliest stage of MS, preceding symptom onset.

Methods

This study is a retrospective analysis of 27 patients with presymptomatic MS, 97 patients with clinically definite MS (CDMS), and 53 healthy controls (HCs) who underwent a cross-sectional 3T-MRI acquisition; of which, 22 MS, 19 HCs, and 1 presymptomatic MS (evaluated 8 months before conversion to CDMS) also underwent translocator protein (TSPO) ¹⁸F-DPA-714 PET and were included in the analysis. CPs were manually segmented on 3D T1-weighted images for volumetric analysis. CP ¹⁸F-DPA-714 uptake, reflecting inflammation, was calculated as the average standardized uptake value (SUV). Multivariable regressions adjusted for age, sex, and ventricular and brain volume were fitted to test CP volume differences between presymptomatic patients and MS or HCs. For the presymptomatic case who also had ¹⁸F-DPA-714 PET, CP SUV differences with MS and HCs were assessed through Crawford-Howell tests. To provide further insight into the interpretation of ¹⁸F-DPA-714-PET uptake at the CP level, a postmortem analysis of CPs in MS vs HCs was performed to characterize the cellular localization of TSPO expression.

Results

Compared with HCs, patients with presymptomatic MS had 32% larger CPs (β = 0.38, p = 0.001), which were not dissimilar to MS CPs (p = 0.69). Moreover, in the baseline scan of the presymptomatic case who later on developed MS, TSPO PET showed 33% greater CP inflammation vs HCs (p = 0.04), although no differences in ¹⁸F-DPA-714 uptake were found in parenchymal regions vs controls. CP postmortem analysis identified a population of CD163⁺ mononuclear phagocytes expressing TSPO in MS, possibly contributing to the increased ¹⁸F-DPA-714 uptake.

Discussion

We identified an imaging signature in CPs at the presymptomatic MS stage using MRI; in addition, we found an increased CP inflammation with PET in a single presymptomatic patient. These findings suggest a role of CP imaging as an early biomarker and argue for the involvement of the blood-CSF barrier dysfunction in disease development.

Trial Registration Information

APHP-20210727144630, EudraCT-Number: 2008-004174-40; ClinicalTrials.gov: NCT02305264, NCT01651520, and NCT02319382.

Amyloid PET imaging and dementias: potential applications in detecting and quantifying early white matter damage

Purpose

Positron emission tomography (PET) with amyloid tracers (amy-PET) allows the quantification of pathological amyloid deposition in the brain tissues, including the white matter (WM). Here, we evaluate amy-PET uptake in WM lesions (WML) and in the normal-appearing WM (NAWM) of patients with Alzheimer’s disease (AD) and non-AD type of dementia.

Methods

Thirty-three cognitively impaired subjects underwent brain magnetic resonance imaging (MRI), Aβ_1-42 (Aβ) determination in the cerebrospinal fluid (CSF) and amy-PET. Twenty-three patients exhibiting concordant results in both CSF analysis and amy-PET for cortical amyloid deposition were recruited and divided into two groups, amyloid positive (A+) and negative (A−). WML quantification and brain volumes’ segmentation were performed. Standardized uptake values ratios (SUVR) were calculated in the grey matter (GM), NAWM and WML on amy-PET coregistered to MRI images.

Results

A+ compared to A− showed a higher WML load (p = 0.049) alongside higher SUVR in all brain tissues (p < 0.01). No correlations between CSF Aβ levels and WML and NAWM SUVR were found in A+, while, in A−, CSF Aβ levels were directly correlated to NAWM SUVR (p = 0.04). CSF Aβ concentration was the only predictor of NAWM SUVR (adj R² = 0.91; p = 0.04) in A−. In A+ but not in A− direct correlations were identified between WM and GM SUVR (p < 0.01).

Conclusions

Our data provide evidence on the role of amy-PET in the assessment of microstructural WM injury in non-AD dementia, whereas amy-PET seems less suitable to assess WM damage in AD patients due to a plausible amyloid accrual therein.

Choroid Plexus Enlargement in Inflammatory Multiple Sclerosis: 3.0-T MRI and Translocator Protein PET Evaluation

Background Choroid plexuses (CPs) have been suggested as a key gateway for inflammation in experimental autoimmune encephalitis, but in vivo evidence of their involvement in multiple sclerosis (MS) is lacking. Purpose To assess CP volumetric and inflammatory changes in patients with MS versus healthy control participants. Materials and Methods This was a secondary analysis of 97 patients (61 with relapsing-remitting MS [RRMS] and 36 with progressive MS) and 44 healthy control participants who participated in three prospective 3.0-T brain MRI studies between May 2009 and September 2017. A subgroup of 37 patients and 19 healthy control participants also underwent translocator protein fluorine 18 (¹⁸F)-DPA-714 PET for neuroinflammation. Relapses and disability scores were collected at baseline and over 2 years. CPs were manually segmented on three-dimensional T1-weighted images; other brain volumes were additionally segmented. Volumes were expressed as a ratio of intracranial volume. The ¹⁸F-DPA-714 distribution volume ratio was quantified in parenchymal regions, whereas standardized uptake value was used for CP inflammation. Multivariable linear regression analyses were performed to assess CP volumetric and inflammatory differences between patients with MS and healthy control participants and correlations between CP volume and lesion load, brain volumes, ¹⁸F-DPA-714 uptake, and annualized relapse rate. Results Ninety-seven patients with MS (mean age, 42 years ± 12 [standard deviation]; 49 women) and 44 healthy control participants (mean age, 39 years ± 14; 23 women) underwent MRI. Thirty-seven patients with MS and 19 healthy control participants underwent PET. CPs were 35% larger in patients with MS (mean value, 15.9 × 10^-4 ± 4.5) than in healthy control participants (mean value, 11.8 × 10^-4 ± 3.8; P = .004). Subgroup analysis confirmed greater CP volume in patients with RRMS (mean value, 15.5 × 10^-4 ± 4.6; P = .008) than in healthy control participants. CP enlargement was greater in patients with active lesions at MRI (mean volume, 18.2 × 10^-4 ± 4.9 in patients with lesions that enhanced with gadolinium vs 14.9 × 10^-4 ± 4 in patients with lesions that did not enhance with gadolinium; P < .001) and correlated with white matter lesion load (r = 0.39; 95% CI: 0.20, 0.55; P < .001) and ¹⁸F-DPA-714 binding in the thalami (r = 0.44; 95% CI: 0.22, 0.72; P = .04) and normal-appearing white matter (r = 0.5; 95% CI: 0.20, 0.71; P = .005). Moreover, it correlated with annualized relapse rate in patients with RRMS (r = 0.37; 95% CI: 0.1, 0.55; P = .005). Finally, patients with MS showed 18.5% higher CP ¹⁸F-DPA-714 uptake than control participants (mean value, 0.778 ± 0.23 vs 0.635 ± 0.15, respectively; P = .01). CP volume in patients with RRMS (r = 0.57; 95% CI: 0.37, 0.73; P = .009) correlated with higher ¹⁸F-DPA-714 uptake. Conclusion Choroid plexuses (CPs) are enlarged and inflamed in patients with multiple sclerosis (MS), particularly in those with relapsing-remitting MS with inflammatory profiles; CP volumetric analysis could represent an MS imaging marker. © RSNA, 2021 EudraCT no. 2008-004174-40; clinical trial registration nos. NCT02305264 and NCT01651520 Online supplemental material is available for this article.

The Prognostic Value of White-Matter Selective Double Inversion Recovery MRI Sequence in Multiple Sclerosis: An Exploratory Study

Using a white-matter selective double inversion recovery sequence (WM-DIR) that suppresses both grey matter (GM) and cerebrospinal fluid (CSF) signals, some white matter (WM) lesions appear surrounded by a dark rim. These dark rim lesions (DRLs) seem to be specific for multiple sclerosis (MS). They could be of great usefulness in clinical practice, proving to increase the MRI diagnostic criteria specificity. The aims of this study are the identification of DRLs on 1.5 T MRI, the exploration of the relationship between DRLs and disease course, the characterization of DRLs with respect to perilesional normal-appearing WM using magnetization transfer imaging, and the investigation of possible differences in the underlying tissue properties by assessing WM-DIR images obtained at 3.0 T MRI. DRLs are frequent in primary progressive MS (PPMS) patients. Amongst relapsing-remitting MS (RRMS) patients, DRLs are associated with a high risk of the disease worsening and secondary progressive MS (SPMS) conversion after 15 years. The mean magnetization transfer ratio (MTR) of DRLs is significantly different from the lesion without the dark rim, suggesting that DRLs correspond to more destructive lesions.

The Role of Amyloid-β in White Matter Damage: Possible Common Pathogenetic Mechanisms in Neurodegenerative and Demyelinating Diseases

Just as multiple sclerosis (MS) has long been primarily considered a white matter (WM) disease, Alzheimer's disease (AD) has for decades been regarded only as a grey matter disorder. However, convergent evidences have suggested that WM abnormalities are also important components of AD, at the same extent as axonal and neuronal loss is critically involved in MS pathophysiology since early clinical stages. These observations have motivated a more thorough investigation about the possible mechanisms that could link neuroinflammation and neurodegeneration, focusing on amyloid-β (Aβ). Neuroimaging studies have found that patients with AD have widespread WM abnormalities already at the earliest disease stages and prior to the presence of Aβ plaques. Moreover, a correlation between cerebrospinal fluid (CSF) Aβ levels and WM lesion load was found. On the other hand, recent studies suggest a predictive role for CSF Aβ levels in MS, possibly due in the first instance to the reduced capacity for remyelination, consequently to a higher risk of WM damage progression, and ultimately to neuronal loss. We undertook a review of the recent findings concerning the involvement of CSF Aβ levels in the MS disease course and of the latest evidence of AD related WM abnormalities, with the aim to discuss the potential causes that may connect WM damage and amyloid pathology.

Parieto-occipital sulcus widening differentiates posterior cortical atrophy from typical Alzheimer disease

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Parieto-occipital sulcus visual rating scale can distinguish PCA from typical AD.

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Visual rating scales have been validated using VBM and Brainvisa Morphologist.

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Visual rating score reflects sulcal widening rather than grey matter reduction.

Objectives

Posterior Cortical Atrophy (PCA) is an atypical presentation of Alzheimer disease (AD) characterized by atrophy of posterior brain regions. This pattern of atrophy is usually evaluated with Koedam visual rating scale, a score developed to enable visual assessment of parietal atrophy on magnetic resonance imaging (MRI). However, Koedam scale is complex to assess and its utility in the differential diagnosis between PCA and typical AD has not been demonstrated yet. The aim of this study is therefore to spot a simple and reliable MRI element able to differentiate between PCA and typical AD using visual rating scales.

Methods

15 patients who presented with progressive complex visual disorders and predominant occipitoparietal hypometabolism on PET-FDG were selected from our centre and compared with 30 typical AD patients and 15 healthy subjects. We used previously validated visual rating scales including Koedam scale, which we divided into three major components: posterior cingulate, precuneus and parieto-occipital. Subsequently we validated the results using the automated software Brainvisa Morphologist and Voxel Based Morphometry (VBM).

Results

Patients with PCA, compared to typical AD, showed higher widening of the parieto-occipital sulcus, assessed both with visual rating scales and Brainvisa. In the corresponding areas, the VBM analysis showed an inverse correlation between the results obtained from the visual evaluation scales with the volume of the grey matter and a direct correlation between the same results with the cerebrospinal fluid volume.

Conclusions

A visually based rating scale for parieto-occipital sulcus can distinguish Posterior Cortical Atrophy from typical Alzheimer disease.

Hereditary hemorrhagic telangiectasia associated with cortical development malformation due to a start loss mutation in ENG

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT), also known as Rendu-Osler-Weber syndrome, is a rare disorder characterized by recurrent epistaxis, telangiectasias and systemic arteriovenous malformations (AVMs). HHT is associated with mutations in genes encoding for proteins involved in endothelial homeostasis such as ENG (endoglin) and ACVRL1 (activin receptor-like kinase-1).

CASE PRESENTATION

Here we describe a 22-year-old male presenting with a transient episode of slurred speech and left arm paresis. Brain MRI displayed polymicrogyria. A right-to-left shunt in absence of an atrial septum defect was noted. Chest CT revealed multiple pulmonary AVMs, likely causing paradoxical embolism manifesting as a transient ischemic attack. The heterozygous ENG variant, c.3G > A (p.Met1lle), was detected in the patient. This variant was also found in patient's mother and in his younger brother who displayed cortical dysplasia type 2.

CONCLUSIONS

The detection of cortical development malformations in multiple subjects from the same pedigree may expand the phenotypic features of ENG-related HHT patients. We suggest considering HHT in young patients presenting with acute cerebral ischemic events of unknown origin.

Long Term Dialysis with Low-Calcium Solution (1.0 Mmol/L) in Capd: Effects on Bone Mineral Metabolism

Objective

Peritoneal dialysate solutions with conventionally high-calcium (Ca) concentrations (1.75 mmol/L) are now widely replaced by solutions with a lower, more physiological calcium content to prevent hypercalcemia in patients treated with oral calcium-containing phosphate binders and/or calcitriol. While there is still debate on how far the dialysate calcium should be lowered (1.25 mmol/L or less), little information is available concerning the effects of a long-term treatment with low-calcium solutions on secondary hyperparathyroidism and bone mineral metabolism in general.

Design

A prospective, randomized, controlled multicenter study to compare the effects of low-calcium (LCa, dialysate calcium 1.0 mmol/L) versus standard calcium dialysate solution (SCa, dialysate calcium 1.75 mmol/L)on bone mineral metabolism in continuous ambulatory peritoneal dialysis (CAPD) patients over 2 years of treatment.

Setting

Nephrology and dialysis units of primary and tertiary hospitals in Germany and Switzerland.

Patients

All CAPD patients in the participating centers between 18 and 80 years of age, stable on CAPD for at least 1 month, free of aluminum bone disease or prior parathyroidectomy were invited to enter the study. Sixty-four patients could be randomly allotted to LCa (n = 35) or SCa (n = 29) treatment in a 2-year protocol; 34 finished the study as planned.

Interventions

Calcium carbonate (CaCO3) was given as oral phosphate binder to maintain serum phosphate <2.0 mmol/L. If hypercalcemia supervened, CaCO3 was exchanged stepwise for aluminium hydroxide (AI(OH)3)’ until normocalcemia was obtained. Patients received calcitriol (0.25 μg/day per os) if parathyroid hormone (PTH) exceeded the upper limit of normal by a factor of 2 or more.

Main Outcome Measures

We assessed total and ionized serum calcium, phosphate, serum aluminum, alkaline phosphatase, osteocalcin, PTH (intact molecule), and phosphate binder intake at regular intervals. Measurements of bone mineral density and hand skeleton x-rays were obtained at the start and after 6 months and 2 years, respectively.

Results

With LCa, mean total and ionized serum calcium levels were within the normal range (total Ca: 2.0 2.6 mmol/L; ionized Ca: 1.19–1.32 mmol/L), but throughout the treatment period were significantly lower than with SCa. The incidence of hypercalcemia (>2.8 mmol/L) was three times higher in patients on SCa, despite the significantly higher amount of AI(OH)3 and less CaCO3 given in this group. In parallel, serum aluminum increased with SCa throughout the study, whereas it was slowly decreasing with LCa. Median PTH levels remained stable at about two times the upper limit of normal over the 2 years of study with LCa. However, 23% of the patients on LCa developed severe hyperparathyroidism, with PTH levels exceeding ten times the upper limit of normal compared to only 10.3% of the patients on SCa. With SCa, median PTH decreased towards near normal levels. Alkaline phosphatase and serum osteocalcin correlated positively with PTH levels. Bone mineral density was in the lower normal range in both groups a n d remained unchanged at the end of the study. Skeletal x-ray films showed only minor alterations in very few patients in both groups with no correlation to serum PTH or treatment modality.

Conclusion

In CAPD patients low-calcium dialysate solutions can be used successfully over prolonged periods of time with stable control of serum calcium. The risk of hypercalcemia resulting from calcium-containing phosphate binders and the need to use aluminum-containing phosphate binders is markedly diminished. However, there is a certain risk that severe secondary hyperparathyroidism with long-term LCa therapy will develop, even if normocalcemia is maintained. Thus, LCa dialysis requires closeand continuous monitoring of PTH and bone metabolism.

Beta-2 Microglobulin Amyloidosis in a Patient on LongTerm Continuous Ambulatory Peritoneal Dialysis (CAPD)

A 61-year-old female patient with ESRD due to analge sic nephropathy and treated solely with CAPD for 81 months is described. During this period she developed peritonitis 4 times. She eventually died of acute pulmonary edema due to coronary heart disease. The autopsy showed an analgesic nephropathy with contracted kidneys, diffuse peritoneal fibrosis, and articular and periarticular amyloidosis of AB2m-type. This form of amyloidosis is well known after hemodialysis; it was, however, not observed heretofore after sole long-term CAPD.

Transperitoneal Calcium Mass Transfer using Dialv Sate with a Low Calcium Concentration (1.0 mM)

Lower dialysate calcium concentrations were recently proposed to overcome the risk of hypercalcemia In continuous ambulatory peritoneal dialysis (CAPD) patients on calcium containing phosphate binders and/or vitamin D metabolites using the standard dialysate calcium concentration (sCa) of 1.75 mM.

To assess transperitoneal calcium mass transfer (CaMT) in CAPD patients using a dialysate with a low calcium concentration (LCa, 1.00 mM), 18 stable patients were randomly allocated to receive either LCa or SCa. CaMT was assessed over 4 hours using 2L dialysate bags with three different dialysate glucose concentrations (1.5%, 2.3%, 4.25%). Total serum calcium (tCa), Ionized calcium (iCa), and the exact dialysate volume were measured before and after the 4-hour dwell. A sample of the drained dialysate was obtained to measure the dialysate calcium concentration.

The tCa and iCa levels were not significantly different In both groups prior to and did not change throughout the test. CaMT (median/range) was .0.64 mmol/exchange (0.35 –1.29 mmol/exchange) using LCa with 1.5% glucose compared to 0.23 mmol (.0.18 -0.87 mmol) with SCa (p<0.0001). CaMT was negatively correlated to ICa and ultrafiltration volume [4.25%: LCa -1.22 (.0.84 -1.9); SCa .0.43 (-1.35 -0.13); p<0.001].

In summary, LCa results in a loss of calcium into the dialysate even at low ultrafiltration volumes and serum ICa levels. This might facilitate the prevention and therapy of renal osteodystrophy with calclum-containing phosphate binders and calcitriol. However, patients using LCa must be carefully monitored for calcium homeostasis and bone turnover.

Low CSF β-amyloid levels predict early regional grey matter atrophy in multiple sclerosis

BACKGROUND AND PURPOSE

Grey matter (GM) atrophy is present from the earliest stages of multiple sclerosis (MS) and occurs largely in a nonrandom manner. However, the biological mechanisms underlying the progression of regional atrophy are still unclear. Aim of this study is to investigate whether amyloid pathology might be involved in determining the pattern of GM atrophy over time.

METHODS

Forty-six subjects were recruited: 31 newly diagnosed relapsing-remitting (RR-) MS patients and 15 age- and sex-matched healthy controls (HC). Aβ levels were determined in CSF samples from all subjects. All participants underwent brain magnetic resonance imaging (MRI) at baseline, and 23 out of 31 patients at one year follow-up. T1-weighted scans were segmented using the Geodesic Information Flows software. Non-parametric statistical tests were used for between-group comparisons and multiple regression analyses.

RESULTS

CSF Aβ concentration was the best predictor of global GM loss over time after age (β = 0.403; p = 0.024), in particular in the left precuneus (p = 0.045), in the left middle cingulate gyrus (p = 0.009), in the left precentral gyrus (p = 0.021) and in the right angular gyrus (p = 0.029).

CONCLUSIONS

CSF Aβ levels seem to be crucial in MS early brain volume loss as GM atrophy manifests in regions particularly vulnerable to early Aβ deposition.

Testing the 2018 NIA-AA research framework in a retrospective large cohort of patients with cognitive impairment: from biological biomarkers to clinical syndromes

Background

According to the 2018 NIA-AA research framework, Alzheimer’s disease (AD) is not defined by the clinical consequences of the disease, but by its underlying pathology, measured by biomarkers. Evidence of both amyloid-β (Aβ) and phosphorylated tau protein (p-tau) deposition—assessed interchangeably with amyloid-positron emission tomography (PET) and/or cerebrospinal fluid (CSF) analysis—is needed to diagnose AD in a living person. Our aim was to test the new NIA-AA research framework in a large cohort of cognitively impaired patients to evaluate correspondence between the clinical syndromes and the underlying pathologic process testified by biomarkers.

Methods

We retrospectively analysed 628 subjects referred to our centre in suspicion of dementia, who underwent CSF analysis, together with neuropsychological assessment and neuroimaging, and were diagnosed with different neurodegenerative dementias according to current criteria, or as cognitively unimpaired. Subjects were classified considering CSF biomarkers, and the prevalence of normal, AD-continuum and non-AD profiles in each clinical syndrome was calculated. The positivity threshold of each CSF biomarker was first assessed by receiver operating characteristic analysis, using Aβ-positive/negative status as determined by amyloid-PET visual reads. The agreement between CSF and amyloid-PET data was also evaluated.

Results

Among patients with a clinical diagnosis of AD, 94.1% were in the AD-continuum, whereas 5.5% were classified as non-AD and 0.4% were normal. The AD-continuum profile was found also in 26.2% of frontotemporal dementia, 48.6% of Lewy body dementia, 25% of atypical parkinsonism and 44.7% of vascular dementia. Biomarkers’ profile did not differ in amnestic and not amnestic mild cognitive impairment. CSF Aβ levels and amyloid-PET tracer binding negatively correlated, and the concordance between the two Aβ biomarkers was 89%.

Conclusions

The examination of the 2018 NIA-AA research framework in our clinical setting revealed a good, but incomplete, correspondence between the clinical syndromes and the underlying pathologic process measured by CSF biomarkers. The AD-continuum profile resulted to be a sensitive, but non-specific biomarker with regard to the clinical AD diagnosis. CSF and PET Aβ biomarkers were found to be not perfectly interchangeable to quantify the Aβ burden, possibly because they measure different aspects of AD pathology.

Modelling chase-and-run migration in heterogeneous populations

Cell migration is crucial for many physiological and pathological processes. During embryogenesis, neural crest cells undergo coordinated epithelial to mesenchymal transformations and migrate towards various forming organs. Here we develop a computational model to understand how mutual interactions between migrating neural crest cells (NCs) and the surrounding population of placode cells (PCs) generate coordinated migration. According to experimental findings, we implement a minimal set of hypotheses, based on a coupling between chemotactic movement of NCs in response to a placode-secreted chemoattractant (Sdf1) and repulsion induced from contact inhibition of locomotion (CIL), triggered by heterotypic NC–PC contacts. This basic set of assumptions is able to semi-quantitatively recapitulate experimental observations of the characteristic multispecies phenomenon of “chase-and-run”, where the colony of NCs chases an evasive PC aggregate. The model further reproduces a number of in vitro manipulations, including full or partial disruption of NC chemotactic migration and selected mechanisms coordinating the CIL phenomenon. Finally, we provide various predictions based on altering other key components of the model mechanisms.

Amyloid PET as a marker of normal-appearing white matter early damage in multiple sclerosis: correlation with CSF β-amyloid levels and brain volumes

PURPOSE

The disease course of multiple sclerosis (MS) is unpredictable, and reliable prognostic biomarkers are needed. Positron emission tomography (PET) with β-amyloid tracers is a promising tool for evaluating white matter (WM) damage and repair. Our aim was to investigate amyloid uptake in damaged (DWM) and normal-appearing WM (NAWM) of MS patients, and to evaluate possible correlations between cerebrospinal fluid (CSF) β-amyloid_1-42 (Aβ) levels, amyloid tracer uptake, and brain volumes.

METHODS

Twelve MS patients were recruited and divided according to their disease activity into active and non-active groups. All participants underwent neurological examination, neuropsychological testing, lumbar puncture, brain magnetic resonance (MRI) imaging, and ¹⁸F-florbetapir PET. Aβ levels were determined in CSF samples from all patients. MRI and PET images were co-registered, and mean standardized uptake values (SUV) were calculated for each patient in the NAWM and in the DWM. To calculate brain volumes, brain segmentation was performed using statistical parametric mapping software. Nonparametric statistical analyses for between-group comparisons and regression analyses were conducted.

RESULTS

We found a lower SUV in DWM compared to NAWM (p < 0.001) in all patients. Decreased NAWM-SUV was observed in the active compared to non-active group (p < 0.05). Considering only active patients, NAWM volume correlated with NAWM-SUV (p = 0.01). Interestingly, CSF Aβ concentration was a predictor of both NAWM-SUV (r = 0.79; p = 0.01) and NAWM volume (r = 0.81, p = 0.01).

CONCLUSIONS

The correlation between CSF Aβ levels and NAWM-SUV suggests that the predictive role of β-amyloid may be linked to early myelin damage and may reflect disease activity and clinical progression.

CSF β-amyloid predicts prognosis in patients with multiple sclerosis

BACKGROUND

The importance of predicting disease progression in multiple sclerosis (MS) has increasingly been recognized, and hence reliable biomarkers are needed.

OBJECTIVES

To investigate the prognostic role of cerebrospinal fluid (CSF) amyloid beta_1-42 (Aβ) levels by the determination of a cut-off value to classify patients in slow and fast progressors. To evaluate possible association with white matter (WM) and grey matter (GM) damage at early disease stages.

METHODS

Sixty patients were recruited and followed up for 3-5 years. Patients underwent clinical assessment, brain magnetic resonance imaging (MRI; at baseline and after 1 year), and CSF analysis to determine Aβ levels. T1-weighted volumes were calculated. T2-weighted scans were used to quantify WM lesion loads.

RESULTS

Lower CSF Aβ levels were observed in patients with a worse follow-up Expanded Disability Status Scale (EDSS; r = -0.65, p < 0.001). The multiple regression analysis confirmed CSF Aβ concentration as a predictor of patients' EDSS increase (r = -0.59, p < 0.0001). Generating a receiver operating characteristic curve, a cut-off value of 813 pg/mL was determined as the threshold able to identify patients with worse prognosis (95% confidence interval (CI): 0.690-0.933, p = 0.0001). No differences in CSF tau and neurofilament light chain (NfL) levels were observed (p > 0.05).

CONCLUSION

Low CSF Aβ levels may represent a predictive biomarker of disease progression in MS.

The loss of macular ganglion cells begins from the early stages of disease and correlates with brain atrophy in multiple sclerosis patients

BACKGROUND

The importance of neurodegeneration in multiple sclerosis (MS) is increasingly well recognized.

OBJECTIVES

To evaluate retinal pathology using optical coherence tomography (OCT) and to investigate possible associations between retinal layers' thickness and specific patterns of gray matter volume in patients with a new diagnosis of MS.

METHODS

A total of 31 patients underwent OCT scans and brain magnetic resonance imaging. In total, 30 controls underwent the same OCT procedure. The association between focal cortical volume and OCT measurements was investigated with voxel-based morphometry (VBM).

RESULTS

Compared to controls, patients' macular retinal nerve fiber layer (mRNFL), macular ganglion cell layer (mGCL), macular inner plexiform layer (mIPL), and macular ganglion cell-inner plexiform layer (mGCIPL) thickness were significantly reduced ( p = 0.0009, p = 0.0003, p = 0.0049, and p = 0.0007, respectively). Peripapillary RNFL (pRNFL) and temporal sector pRNFL (T-pRNFL) did not show any significant changes, although there was a trend toward T-pRNFL thinning ( p = 0.0254). VBM analysis showed that mGCIPL and pRNFL were significantly correlated with the volume reduction of occipital-parietal cortex ( p < 0.005).

CONCLUSION

mRNFL, mGCL, and mIPL are significantly reduced in MS patients without concomitant pRNFL thinning. These retinal changes show a significant association with cortical regions that are known to be important for visuospatial performance.

Modelling human perception processes in pedestrian dynamics: a hybrid approach

In this paper, we present a hybrid mathematical model describing crowd dynamics. More specifically, our approach is based on the well-established Helbing-like discrete model, where each pedestrian is individually represented as a dimensionless point and set to move in order to reach a target destination, with deviations deriving from both physical and social forces. In particular, physical forces account for interpersonal collisions, whereas social components include the individual desire to remain sufficiently far from other walkers (the so-called territorial effect). In this respect, the repulsive behaviour of pedestrians is here set to be different from traditional Helbing-like methods, as it is assumed to be largely determined by how they perceive the presence and the position of neighbouring individuals, i.e. either objectively as pointwise/localized entities or subjectively as spatially distributed masses. The resulting modelling environment is then applied to specific scenarios, that first reproduce a real-world experiment, specifically designed to derive our model hypothesis. Sets of numerical realizations are also run to analyse in more details the pedestrian paths resulting from different types of perception of small groups of static individuals. Finally, analytical investigations formalize and validate from a mathematical point of view selected simulation outcomes.

Coherent modelling switch between pointwise and distributed representations of cell aggregates

Biological systems are typically formed by different cell phenotypes, characterized by specific biophysical properties and behaviors. Moreover, cells are able to undergo differentiation or phenotypic transitions upon internal or external stimuli. In order to take these phenomena into account, we here propose a modelling framework in which cells can be described either as pointwise/concentrated particles or as distributed masses, according to their biological determinants. A set of suitable rules then defines a coherent procedure to switch between the two mathematical representations. The theoretical environment describing cell transition is then enriched by including cell migratory dynamics and duplication/apoptotic processes, as well as the kinetics of selected diffusing chemicals influencing the system evolution. Finally, biologically relevant numerical realizations are presented: in particular, they deal with the growth of a tumor spheroid and with the initial differentiation stages of the formation of the zebrafish posterior lateral line. Both phenomena mainly rely on cell phenotypic transition and differentiated behaviour, thereby constituting biological systems particularly suitable to assess the advantages of the proposed model.

[Biological risk prevention in agriculture and animal breeding: immunization strategies]

Vaccine preventable diseases are, so far, a main focus of Public Health programmes all over the world since people still die in consequence of Dyphteria or Tetanus. Biological risk is widely represented in agriculture and animal breeding, due to environmental characteristics and to injury typology. Moreover, aged people and migrants represent a significant part of the workforce. These two groups are, for instance, more exposed to Clostridium tetani infection because not fully immunized. Among infectious diseases that can affect agricultural workers, just tetanus can be well controlled by immunization programmes. Teaching and training activities are the most important tools to get protection against Leptospira interrogans, Salmonella spp and hepatitis E Virus infection. As for every training activity, linguistic and cultural barriers have to be taken into account.

[The occupational health physician and the health surveillance in agriculture]

Despite the underreporting of occupational diseases in agriculture, available data clearly show a significant health risk, and therefore the need of health surveillance at the workplace. The implementation of health surveillance programs for agricultural workers relies on the possibility of creating a system able to reach the workers at their workplaces, with the collaboration of employers' associations, able to support enterprises in several issues, including risk assessment and management. The health surveillance program can be organized in a component common for all workers, based on physical examination, chemistry, electrocardiography, hearing and lung functions examinations, and on tests addressing specific risks, if present: vibration, physical overload, chemicals, biological agents, allergens. The frequency of examinations must be decided based on risk assessment and health surveillance outcomes.

Neurobehavioural effects of pesticides with special focus on organophosphorus compounds: which is the real size of the problem?

The risk of neurobehavioural impairment as a consequence of a prolonged, low dose exposure to neurotoxic pesticides is not clearly demonstrated despite numerous publications addressing the topic. We reviewed the 24 papers published on human neurobehavioural effects of organophosphorus and/or carbamates pesticides up to May 1st 2008. Variables evaluated were compound/s addressed, number of subjects, approach to measure or estimate exposure, characteristics of control groups and presence of confounders, methodological approach, and type of alteration, taking into account cognitive, sensory-motor, psychological, and psychomotor measures. A total of 6 papers considered the whole spectrum of functions, the studies yielding positive or uncertain results were 13 (68%) for cognitive function, 11 (69%) for psychomotor function, 11 (65%) for sensory-motor function, and 11 (65%) for psychological function impairment. In 46% of the positive studies a previous severe acute poisoning was reported. Exposure levels were measured only in 5 studies, and very often there were problems in the selection of controls, and firm conclusions on the risk of neurobehavioural effects cannot be reached yet. The main limits of the available data are: limited number of studies and compounds addressed, significant differences in the approach among studies, poor concordance of the results of different studies, and difficulties in controlling confounding factors. Nevertheless, there are sufficient data to conclude that neurobehavioural impairment might be the consequence of an acute poisoning, and possibly the consequence of relatively high and prolonged exposures.

An integrated approach to biomonitoring exposure to styrene and styrene-(7,8)-oxide using a repeated measurements sampling design

The aim of this work was to investigate urinary analytes and haemoglobin and albumin adducts as biomarkers of exposure to airborne styrene (Sty) and styrene-(7,8)-oxide (StyOX) and to evaluate the influence of smoking habit and genetic polymorphism of metabolic enzymes GSTM1 and GSTT1 on these biomarkers. We obtained three or four air and urine samples from each exposed worker (eight reinforced plastics workers and 13 varnish workers), one air and urine samples from 22 control workers (automobile mechanics) and one blood sample from all subjects. Median levels of exposure to Sty and StyOX, respectively, were 18.2 mg m(-3) and 133 microg m(-3) for reinforced plastics workers, 3.4 mg m(-3) and 12 microg m(-3) for varnish workers, and <0.3 mg m(-3) and <5 microg m(-3) for controls. Urinary levels of styrene, mandelic acid, phenylglyoxylic acid, phenylglycine (PHG), 4-vinylphenol (VP) and mercapturic acids (M1+M2), as well as cysteinyl adducts of serum albumin (but not those of haemoglobin) were significantly associated with exposure status (controls<exposed workers). Also, levels of VP and M1+M2 were significantly affected by smoking, and levels of M1+M2 were significantly affected by GSTM1 polymorphisms. Multiple linear regression analyses of the subject-specific (logged) metabolite levels across exposed workers showed that Sty was a significant predictor for all urinary analytes while StyOX was a significant predictor of PHG only. Interestingly, the log scale regression coefficients for Sty in these models were significantly less than one for all metabolites except M1+M2. This suggests that the natural scale relationships between levels of all Sty metabolites, except M1+M2, displayed downward concavity with increasing Sty exposure, suggestive of saturable metabolism. Levels of the protein adducts were not associated with exposure to either Sty or StyOX among exposed subjects.

[Workers with alcohol and drug addiction problems. Consensus Document of the Study Group on Hazardous Workers]

BACKGROUND

Italian Law 81/08 (so-called "Unified Text of Laws on Health and Safety at Work"), came into force on 15 May 2008 and incorporates provisions related to medical surveillance of drug and alcohol dependency at the workplace.

OBJECTIVES

Occupational health traditionally addresses the issue of protection of worker from occupational hazards. The issue of protection of third parties from behaviour of workers resulting from drug and alcohol dependency implies an original methodological approach, involving full cooperation of employer, employees, and health and safety consultants.

METHODS

A consensus development meeting was organized under the leadership of the Italian Study Group on Hazardous Workers (La.R.A. group). The meeting brought together physicians of different specialties, legal experts and bioethicists, labour and management policy-makers, to discuss the issue and define the research data available, the standards that were appropriate, and which policies were fair.

RESULTS

The efficacy of medical surveillance, including workplace drug-testing, relies on a comprehensive policy, including written and verbal information on the use of alcohol and drugs on the job, training for supervisors and management, employee education, and employee assistance structures. Sample collection and testing should be carried out in accordance with standardized and tested procedures. Small businesses will need assistance, including development of model policies, setting up consortia for testing services and if necessary request for National Insurance benefits to reduce costs.

CONCLUSIONS

The recently introduced Italian legislation on occupational safety and health closely resembles Finnish law since it consists of a "double channel" for workplace drug testing. At recruitment, the employer is entitled to ask a job applicant for a certificate of "Job fitness", including drug tests, that can be issued only by a public health institution, where the job applicant works on a well-defined set of tasks which require accuracy, trustworthiness, independent judgement or a very good reaction capacity. The employer may also refer the employee to the public health institution to obtain a certificate in the course of an employment contract when there is a legitimate suspicion that the employee is working while under the effects of drugs or alcohol or that the employee is a drug addict. After recruitment, the physician responsible for medical surveillance of workers (the so-called "Competent Physician") is entitled to perform drug tests on employees. The need for a test is decided by the health care professional, not by the employer, and only a general report on the health of the employee ("fit", fit with restrictions" or "unfit") may be given to the employer. Workers positive for drug tests will be referred to a public health institution for re-testing and treatment.

[The impact of personal protective equipment in reducing risk for operators exposed to pesticides: from theory to practice]

In Europe, the use of plant protection products is authorized provided the operator risk assessment carried out does not show exposure levels above the health-based triggers. Two models are currently available (German and UK models) to estimate exposure levels of agricultural operators. They consider, among different variables, the use of Personal Protective Equipment (PPE), based on their capacity to reduce exposure through the application of specific "reduction factors", derived from laboratory or field studies. Such factors, which date back to '90s, could be obsolete, as indicated by recent literature, posing problems on the reliability of current estimates. Therefore, the exposure estimates produced in Europe from 2005 to 2007, for 52 active ingredients in 395 scenarios, have been collected and analysed to check whether the application of recent exposure reduction factors might have an impact on the final outcomes. In some case the exposure levels resulted underestimated, highlighting the problem of operator safety with regard to the use of specific PPE and to an adequate training programme.

[Occupational and environmental exposure to anilide and dicarboximide pesticides]

Dicarboximide fungicides (DF) such as vinclozolin, iprodione, procymidone are widely used on vines, fruit and vegetables, and anilide herbicides (AH) such as diuron, linuron, propanil are used to control weeds on hard surfaces, such as, roads, railway tracks, paths, and in crops, forestry. Italian reports on food safety found many samples contaminated by pesticides belonging to these categories, even though only few exceeding L.M.R. Since adverse effects on human health, such as endocrine disruption, have been reported, biological monitoring is essential for exposure assessment both of occupationally exposed subjects and of the general population. Common metabolites of DF and AH are dichloroanilinines such as 3,4-DCA and 3,5-DCA, urine samples from 153 subjects living in Novafeltria, central Italy, were collected for analysis of 3,4- and 3,5-DCAs, each participant was invited to complete a very detailed questionnaire. A total of 151 out of 153 samples were found to be positive for 3,5-DCA, and 81.7% were positive for 3,4-DCA. Also 33 workers, engaged in application of propanil on rice in northern Italy, were involved in the study and 3,4-DCA was determined as marker of exposure. 3,4 and 3,5 dichloroaniline are useful and promising biological indicators for monitoring occupational and environmental exposure to these classes of pesticides.

[Occupational risk and prevention in the biotechnology industry: a review]

BACKGROUND

The biotechnology industry has expanded greatly in the last 20-30 years and has led to a number of applications in different sectors of work, i.e., medical and pharmaceutical, agricultural, chemical, energetic and others. Nowadays hundreds of thousands of workers worldwide are employed in biotechnology plants. Health and safety issues related to such working activities are considered as relevant to workers as well as to the general public. In particular, when compared to traditional biotechnology, modern methods of processing microrganisms have given rise to public concern that they might generate hazards to human beings and to the environment.

OBJECTIVES AND METHODS

After summarizing the most important products and fields of application, the paper sets out to detail potential adverse effects for the health of biotechnology workers; in addition, an analysis of the literature highlights the various concepts of primary and secondary prevention.

RESULTS AND CONCLUSION

Along with occupational risk factors common to other working activities (i.e. the well-known physical and chemical hazards), the peculiarity of handling microrganisms and/or different biologic systems may induce infections, immunological alterations or non-infective and non-immunologic toxic reactions in the workers involved The need is emphasized for an accurate risk assessment, careful control by means of the current monitoring strategies and implementation of the confinement measures, taking into account the criteria set by Italian legislation for occupational biological risk. Lastly, attention is focussed on examinations for the medical surveillance of workers at risk.

Aluminum determination in biological fluids and dialysis concentrates via chelation with 8-hydroxyquinoline and solvent extraction/fluorimetry

We describe a simple, rapid, and sensitive fluorescence method for measurement of aluminum (Al) in human biological fluids, in dialysis solutions, and in tap water, which uses 8-hydroxyquinoline for ion chelation. The fluorescence intensity of the toluene-extracted metal chelate (excitation wavelength, 380 nm; emission wavelength, 504 nm) remains unchanged for over 48 h at room temperature. Fluorescence intensity is a linear function of the concentration of Al in the 2-1000 microg/L range with detection limits of 0.7-2 microg/L. A large excess of other ions normally found in biological fluids does not interfere in Al determination. The method developed was successfully used in assaying Al in serum and urine of reference subjects, in serum samples from patients undergoing long-term dialysis, and in dialysis solutions. Al concentrations, measured by this fluorimetric procedure, were compared with those obtained by Zeeman graphite-furnace atomic absorption spectrometry. A correlation coefficient of 0.98 was obtained. The proposed method could be used for routine analysis in clinical laboratories for accurate determination of aluminum in aqueous or biological fluids.

[New biomarkers of exposure]

In this paper we have defined the new biomarkers of exposure (NBE) as those biomarkers discovered in the last five years and, among previously validated biomarkers, also those applied in different ranges of doses or those determined in biological matrices which differ from matrices originally considered. We examined the results from the surveys carried out by the main Italian research units involved in biological monitoring, i.e. those from the Universities of Brescia, Milan, Naples, Padua, Parma, Pavia, Turin and Verona. The data were collected using a standardized model and included the following: type of element or organic compound, type of biomarker, analytical technique and method, their relationship with environmental monitoring data, their relationship with effect indicators or effects in general, improvement with respect to old biomarkers, reference values. Twenty two NBEs were identified: 14 elements and chemical compounds as such or as metabolites, 4 examples of mixtures, 3 of new matrices, one of speciation. Among the others, aspects such as interest in requiring NBE, quality assurance, availability, cost-benefit ratio were discussed. We conclude that development of this specific field of research appears to be a crucial point for future improvement in risk assessment and health surveillance procedures.

[European multicenter cross-sectional study on exposure to low doses of benzene]

A cross-sectional multicenter european study has been carried out to evacuate the relations between exposure to low level of benzene and biological markers of internal dose (t,t-MA, S-PMA) and early biological effect (DNA-SSB). The research has shown significantly increased levels (adjusted for smoking habits) of the urinary excretion of t,t-MA, S-PMA and DNA-SSB in petrochemical workers (mean benzene level = 5,694 micrograms/m3) but not in filling station attendants, traffic police officers, and bus drivers compared to referent workers. Dose-response relations were detected between benzene air levels, t,t-MA, S-PMA and DNA-SSB in petrochemical workers, with significantly increased levels of DNA-SSB detected for benzene exposure levels in the range 391-1,800 micrograms/m3 (0.12-0.58 ppm).

[Evolution of industrial toxicology toward vanishing doses and the human genome]

BACKGROUND

This article aims to discuss the influence that the application of the recent discoveries in genomics will have on the theory and practice of industrial toxicology in developed post-industrial countries. It is stressed that the recent advances in toxicogenomics can be integrated into the existing wealth of knowledge on the toxic properties of industrial chemicals to improve the efficacy of prevention of toxicological risk.

METHODS AND RESULTS

The understanding of the biochemical and physiological mechanisms underlying susceptibility or resistance to the toxic effects of industrial xenobiotics, and in particular to carcinogens, allows us to split the epidemiologically derived relationship linking the frequency of disease in the exposed population to the level of workplace contamination into a set of sequential sub-relationships linking: a) the exposure level to that of workplace contamination; b) the internal dose to the exposure level; c) the biological effect (e.g., measured through biochemical markers of early effect) to the internal dose; d) the frequency of disease to that of observation of early biochemical effects. Each of the cited relationships is affected by a degree of uncertainty due to the variability of biological response among the examined individuals, which in turn requires a definition of the statistical limits for the association functions between the variables. As a consequence, the possibility of investigating the individual biochemical and physiological steps in the causal mechanism that links toxic exposure to disease does not necessarily lead to an increase in the information potential of biological monitoring, since the uncertainty due to inter-individual variability is amplified through the sequence of causal relationships to the point that the data from biological monitoring become valueless with regard to the prediction of the frequency or probability of disease. This is particularly true when exposure to 'low doses' is investigated, as is now increasingly frequent in post-industrial developed countries, where workplace contamination is now greatly reduced to levels which may be borderline with those in the general environment. Thus at the low-dose end of the range of contamination and exposure values there is an area where, for statistical reasons consequent to the heterogeneity of examined populations, a quantitative prediction of internal exposure due to environmental contamination, of biological adverse effects due to exposure levels and of frequency of disease due to the extent or frequency of biological effects is no longer reliably possible. This in turn impairs the preventive efficacy of biological monitoring.

CONCLUSIONS

A closer integration between industrial toxicology and state-of-the-art molecular genetics derived from the recent sequencing of the human genome is the way to overcome the limitations described. In particular, the individual subjects in the examined populations can be classified with regard to some genetically controlled characters relevant to the biotransformation of xenobiotics and to DNA repair and the statistical analysis of data can be performed on more homogeneous subpopulations, in order to decrease inter-individual variability of biochemical and physiological response. This in turn increases the predictive power of the biological markers, both of dose and effect, and improves the efficacy of prevention, e.g., by highlighting oversensitive subpopulations or lifestyles which can increase the risk of occupational and environmental disease.

Determination of hexafluoroisopropanol, a sevoflurane urinary metabolite, by 9-fluorenylmethyl chloroformate derivatization

A reversed-phase HPLC method with fluorescence detection for the quantification of hexafluoroisopropanol (HFIP) in urine is presented. HFIP, a metabolite of the inhalation anesthetic sevoflurane, is excreted mainly in urine as glucuronic acid conjugate. After enzymatic hydrolysis of the glucuronate, primary amino groups of interferent urinary compounds are blocked by reaction with o-phthalic dicarboxaldehyde and 3-mercaptopropionic acid, followed by labeling of HFIP with 9-fluorenylmethyl chloroformate. The derivatization reaction proceeds in a water-acetonitrile (1:1) solution at room temperature with a borate buffer of pH 12.5 as a catalyst. A stable fluorescent derivative of HFIP is formed within 5 min. The HFIP-FMOC derivative is separated by reversed-phase chromatography with isocratic elution on an octadecyl silyl column (33x4.6 mm, 3 microm) and guard column (20x4.0 mm, 40 microm), at 35 degrees C, and detected by fluorescence detection at an excitation wavelength of 265 nm and an emission wavelength of 311 nm. The method detection limit is 40 pg, per 10-microl injection volume, corresponding to 16 microg/l of HFIP in urine. The among-series relative standard deviation is <6% at 200 microg/l (n=6). As a preliminary application, the method was used to detect HFIP concentration in the urine of two volunteers exposed for 3 h to an airborne concentration of sevoflurane in the order of 2 ppm.

[Immunologic effects of exposure to low levels of inorganic mercury]

OBJECTIVE

The immune system is a target for the toxic effects of inorganic mercury, both in humans and animals. In humans it has been observed that occupational and environmental exposure to inorganic mercury may cause both clinical (autoimmunity, hypersensitivity) and subclinical effects (cellular and humoral immunologic variable modifications). To obtain a better definition of these effects with respect to the exposure levels, a multicentre study was performed on 117 workers exposed to very low doses of inorganic mercury and 172 subjects from the general population of the same geographical area with environmental exposure to mercury from dental amalgams and dietary fish intake.

RESULTS

The white blood cell count was included in the normality range for all subjects and there was no difference between exposed and non exposed subjects. The immunologic variables studied showed an increase of the CD4+ and CD8+ number in exposed workers compared to non-exposed subjects, with a statistically significance only for CD4+, while no difference was observed regarding CD4+, CD8+, NK+ percentage and CD4+/CD8+ ratio. A significative decrease of serum IL-8 and an inverse correlation between serum levels of this cytokine and HgU were observed in exposed workers compared to non exposed subjects. No association between immunologic variables and both dental amalgams and dietary fish intake was found in subjects not occupationally exposed to inorganic mercury.

DISCUSSION

The decrease in IL-8 serum levels observed in exposed workers might suggest an immunosuppressive effect of occupational exposure to very low doses of inorganic mercury. This result suggests the need to revise of current HgU BEI after further definition of its prognostic significance.

[Evaluation of the neurotoxic and nephrotoxic effects following long-term exposure to metallic mercury in employed at a chlorine/sodium-hydroxide plant]

OBJECTIVES

Within the frame work of a wide multicentre study, a sub-study was developed in order to explore the occurrence of early effects on the central nervous system, on the kidney and on the neuro-immune system in the workers of a chloro-alkali production plant exposed to metallic mercury at airborne concentration levels lower than 0.025 mg/m3 (TLV-TWA). They were compared to a control population of employees of the same huge petrochemical plant with different job that did not implicate exposure to mercury vapors. Specifically, the study aimed at revealing the occurrence of early effects on the central nervous system related with mercury exposure, as can be assessed through neurophysiological and neurobehavioral tests.

METHODS

The excretion of urinary mercury was measured by atomic absorption spectrometry. The study of renal function was assessed by measurement of the urinary excretion of some high and low molecular weight protein markers (albumin, beta 2-microglobulin, retinol-binding protein, fibronectin, specific proximal tubule brush border antigens, N-acetyl-beta-D-glucosaminidase). The neurobehavioral status of the study subjects was assessed by means of several test parameters (Simple Reaction Time, Color Word Vigilance Test, Symbol Digit, Finger Tapping, Mood Scale of Kjellberg and Iwanowski, Subjective symptoms questionnaire (QSS), Luria Nebraska Motor Scale, Branches Alternate Movement Task and Tremometry).

RESULTS

The values of urinary excretion averaged 12 +/- 8 micrograms Hg/g of creatinine for the exposed workers group (n = 38), while for the reference group (n = 34 cases) urinary excretion was statistically lower, averaging 4 +/- 6 micrograms Hg/g of creatinine. Neither the parameters selected for the assessment of renal functions, nor those chosen to probe the neurobehavioral status of the probands revealed statistically reliable differences between the group of exposed workers (length of exposure: range 1-34 years) and the control group. Nevertheless, some minor but still statistically reliable correlations were found between some neurobehavioral parameters and some demographic variables describing the whole group of tested workers, but not to the level of occupational exposure to mercury.

CONCLUSIONS

The results of the study confirm the lack of toxic effects of clinical importance on the central nervous system and on the kidney for values of mercury urinary excretion lower than the suggested index of biological exposure (IBE) of 35 micrograms Hg/gram of creatinine.

[Adaptation of the TriTEST TM for the investigation of blood samples for a multicenter study taken to a single laboratory]

BACKGROUND

Immunotoxicological studies in humans are usually carried out via the determination of some selected immune parameters in subjects occupationally and/or environmentally exposed to immunotoxic substance. One of the most often measured parameters is the determination of lymphocyte subsets, which needs to be carried out in a very short time (a few hours) after blood collection. This is the major problem limiting the determination of lymphocyte subpopulations in field studies, where samples are usually collected directly at the workplace, and very often at the end of the workshift. Unfortunately, these collection modalities significantly prolong the time between collection and analysis. The problem is more evident in multicentric studies, where a further problem is represented by the time needed to send samples to the laboratory.

OBJECTIVE

Since an immune evaluation was planned, including the determination of lymphocyte subpopulations CD4 (T-helper), CD8 (T-suppressor cytotoxic) and CD16/CD56 (natural killer) in the project "Assessing health effects in man from exposure to low doses of inorganic mercury in environmental and occupational settings", a method was developed for performing cytofluorimetric analysis in "field studies".

METHODS

The method is based on commercially-available kits, and involves in loco treatment. Whole blood is labeled with monoclonal antibodies, and fixed samples immediately after collection. After the treatment, the samples are ready for flow cytometric analysis, which may be performed after a two-day period from sample collection.

RESULTS AND CONCLUSION

The method described is adequate for immunotoxicity testing in field studies because it prolongs the maximum latency time from collection and cytofluorimetric analysis up to 48 hours. A second interesting characteristic of the method is the possibility of using whole blood, without any need of either complex manipulations or particular equipment.

[Evaluation of the dose of mercury in exposed and control subjects]

OBJECTIVES

The aim of this paper was to analyse the concentrations of HgU and HgB in three different groups: 122 workers exposed, 18 workers formerly exposed and 196 subjects not occupationally or environmentally exposed to mercury.

METHODS

All the subjects filled out a questionnaire concerning personal data, lifestyle, occupational or non-occupational exposure to Hg and medical history. The amalgam fillings area was measured by a standardised method.

RESULTS

Urinary mercury excretion was significantly greater in the group of the exposed workers respect to the group of subjects not occupationally exposed (Median value of 8.3 micrograms/g creatinine and the 5 degrees and 95 degrees percentile respectively of 2.66 e 23.50 micrograms/g creatinine against Median value of 1.2 micrograms/g creatinine and the 5 degrees and 95 degrees percentile respectively of 0.18 and 5.42 micrograms/g creatinine). U-Hg in formerly exposed workers were comparable to U-Hg in non-occupationally exposed subjects, with a median value of 1.6 micrograms/g creatinine. B-Hg values were similar in the three groups: the median value was 3.1 micrograms/l in the non-occupationally exposed, 4.0 micrograms/l in the exposed workers and 3.9 micrograms/l in the past exposed. These value were not significantly different. Among the considered variables (amalgam fillings, fish consumption, age, sex, alcohol intake, chewing-gum and smoking) dental amalgam and fish consumption were significantly related with the Hg urinary excretion and the B-Hg levels. This is particularly true considering the subjects altogether: for the exposed workers, indeed, the occupational exposure was the most relevant variable.

CONCLUSIONS

The results of the present research confirmed that the U-Hg excretion in non-occupationally exposed subjects is influenced by amalgam dental fillings. Furthermore, in our study Hg urinary excretion was significantly related with fish consumption. This fact can be explained, according to several recent experimental human and animal trials, considering that methylmercury contained in fish is partially converted, through breakage of the carbon-Hg bond, into Hg inorganic forms, which accumulate in the kidney and have a urinary excretion pathway.