Biological monitoring of low-level exposure to benzene

INTRODUCTION

Conflicting opinions exist about the reliability of biomarkers of low-level exposure to benzene. We compared the ability of the urinary excretion of trans,trans-muconic acid (t,t-MA), s-phenilmercapturic acid (s-PAMA) and urinary benzene (U-Benz) to detect low level occupational and environmental exposure to benzene.

METHODS

We monitored airborne benzene by personal air sampling, and U-Benz, s-PMAI, t,t-MA and cotinine (U-Cotinine) in spot urine samples, collected at 8 am and 8 pm, in 32 oil refinery workers and 65 subjects, randomly selected among the general population of urban and suburban Cagliari, Italy. Information on personal characteristics, diet and events during the sampling day was acquired through in person interviews.

RESULTS

The median concentration of airborne benzene was 25.2 microg/m3 in oil refinery workers, and 8.5 microg/m3 in the general population subgroup. U-Benz in morning and evening samples was significantly more elevated among oil refinery workers than the general population subgroup (p = 0.012, and p = 7.4 x 10(-7), respectively) and among current smokers compared to non-smokers (p = 5.2 x 10(-8), and p = 5.2 x 10(-5) respectively). Benzene biomarkers and their readings in the two sampling phases were well correlated to each other. The Spearman's correlation coefficient with airborne benzene was significant for U-Benz in the evening sample, while no correlation was seen with t,t-MA and s-PMA readings in either samplings. The two benzene metabolites were frequently below limit of detection (LOD), particularly among the general population study subjects (17-9% and 39%, for t,t-MA and s-PMA respectively). Morning U-Cotinine excretion showed a good correlation with U-Benz in the morning and in the evening sampling (p < 0.001), and with s-PMA in the evening sample (p < 0.001), but not with t,t-MA in either samplings. t,t-MA in the evening sample was the only biomarker showing a moderate inverse correlation with BMI (p < 0.05). The multiple regression analysis adjusting by BMI and number of cigarettes smoked during the day confirmed the results of the univariate analysis.

DISCUSSION

Our results suggest that unmetabolized U-Benz would allow a more reliable biomonitoring of low-level exposure to benzene than s-PMA and t,t-MA.

[Cancer risk among shift workers: a review]

INTRODUCTION

According to IARC, shift work resulting in disruption of circadian rhythm is a probable human carcinogen (Group 2A).

METHODS

We examined the scientific literature on the carcinogenic risk among shift workers for risk assessment purposes.

RESULTS

Clock genes polymorphisms might contribute with suppression of melatonin synthesis, immuno-suppression from sleep deprivation, individual habits associated with shift work, and low vitamin D levels, in increasing risk of breast cancer, prostate cancer and lymphoma among shift workers.

CONCLUSION

Although the epidemiological evidence seems scanty, the hypothesis that shift work-related sleep deprivation would contribute to increasing cancer risk seems based on solid ground.

[Results of a health surveillance program for health care workers exposed to a patient affected by tuberculosis]

A health surveillance program was implemented in 71 health care workers (HCW) exposed to a patient with active TB infection. A two-step tuberculin skin test (TST) was performed in all the exposed, and a QuantiFERON-TB Gold (QTF) test was scheduled for positive TST subjects. Clinical-radiological surveillance (CRS) was scheduled for subjects positive to TST and QTF or symptomatic. Thirty eight percent HCW were TST positive; 19% of them were also QTF positive and were referred to CRS. No clinical TB was observed among the exposed HCW. Comprehensive health surveillance allows to increase risk perception, compliance to HS and to reduce cost in respect to less cost-effective practices.

[Electrocardiogram changes in shift workers]

BACKGROUND

Besides a significant deterioration in their family and personal life, shift workers also suffer health problems ranging from chronic fatigue to gastro-intestinal disorders, changes in sleep rhythm and cardiovascular disease, including arrhythmia and ischaemic heart disease.

OBJECTIVES

The aim of the study was to assess the prevalence of electrocardiographic changes, such as conduction disorders, alterations in the repolarization phase and frequency-adjusted QT interval (QTc) in relation to shift work.

METHODS

We conducted a cross sectional survey of 125 male subjects, 60 of whom worked fixed hours, and 65 were shift workers on two different schedules: 32 were on duty for 24 hours followed by 96 hours rest, and 33 worked 8-hour shifts (3 x 8). During periodical health assessment we examined their electrocardiograms (ECG), classified the morphology and measured the QTc interval.

RESULTS

The QTc interval did not differ by type of work shift or by the presence of morphological changes in the ECG, including concurrent conduction disorders, or alterations in the repolarization phase. However, unlike day workers and 24-h shift workers, the QTc interval tended to increase with age among 8-h shift workers (r = 0.338; p = 0.05). Also, risk of conduction disorders was moderately, but not significantly, elevated among 8-h shift workers compared with subjects working fixed hours (OR = 1.9; I.E 95% 0.6, 5.7).

CONCLUSIONS

Our study did not reveal significant changes in the ECG morphology in relation to the type of work shift.

An extract of Lannea microcarpa: composition, activity and evaluation of cutaneous irritation in cell cultures and reconstituted human epidermis

Lannea microcarpa (Anacardiaceae) is a tropical tree used in African folk medicine and commercial dermopharmaceutical formulations. Fractionation and analysis of its polar extract allowed the identification of 4′-methoxy-myricetin 3-O-α-l-rhamnopyranoside, myricetin 3-O-α-l-rhamnopyranoside, myricetin 3-O-β-d-glucopyranoside, vitexin, isovitexin, gallic acid and epi-catechin, as the major constituents. In-vivo assay (the croton oil ear test in mice) showed that the extract had significant anti-inflammatory effect (ID50 = 900 μg cm2) but ten times lower than that of indometacin (ID50 = 93 μg cm2), the non-steroidal anti-inflammatory drug used as reference. Cytotoxicity and cutaneous irritation of the extract and its constituents were investigated. The crude extract and its major components did not affect cell viability in-vitro either in three different cultures (J774.A1, WEHI-164 and HEK-293) of cells grown in monolayers or in the reconstituted human epidermis (RHE, 3D model), nor did they cause release of pro-inflammatory mediators (IL-1α) or histomorphological modification of RHE.

A sensitive FRET probe assay for the selective detection of Mycobacterium marinum in fish

Mycobacterium marinum is the causative agent of mycobacteriosis in wild and cultured fish and of atypical infection in humans. For the diagnosis of M. marinum, cultural and traditional polymerase chain reaction (PCR) methods are currently used. However, these protocols, although able to discriminate within Mycobacterium spp., have proved to be time-consuming or difficult to carry out. For this reason, the aim of this study was to obtain a rapid and specific diagnostic tool to quantify fish Mycobacterium spp. or to discriminate M. marinum from other mycobacteria. A primary PCR amplification with SYBR Green had a detection limit (dl) of 10(2)Mycobacterium DNA copies with a log-linear quantification range up to 10(4) (R(2) = 0.99). The second PCR using FRET probes, flanking a region containing species specific nucleotide variations, was designed and validated with synthetic erp gene fragments corresponding to different mycobacterial species, different whole mycobacteria suspensions, experimentally infected fish tissues, tissues from experimentally infected fish, and samples of cultured fish. The results show that the FRET probes demonstrate a high specificity as the melting curve analysis allowed efficient discrimination of M. marinum from Mycobacterium chelonae, Mycobacterium fortuitum, Mycobacterium pseudoshottsii, Mycobacterium shottsii and Mycobacterium ulcerans. The kidney is the organ with the strongest detection signal and using fish tissues the method has a mean sensitivity of 50 DNA copies/PCR.

The transformation sequence of cement-asbestos slates up to 1200 degrees C and safe recycling of the reaction product in stoneware tile mixtures

Cement-asbestos is the main asbestos containing material still found in most of the European countries such as Italy. Man- and weathering-induced degradation of the cement-asbestos slates makes them a source of dispersion of asbestos fibres and represents a priority cause of concern. This concern is the main prompt for the actual policy of abatement and disposal of asbestos containing materials in controlled wastes. An alternative solution to the disposal in dumping sites is the direct temperature-induced transformation of the cement-asbestos slates into non-hazardous mineral phases. This patented process avoids the stage of mechanical milling of the material before the treatment, which improves the reactivity of the materials but may be critical for the dispersion of asbestos fibres in working and life environment. For the first time, this paper reports the description of the reaction path taking place during the firing of cement-asbestos slates up to the complete transformation temperature, 1200 degrees C. The reaction sequence was investigated using different experimental techniques such as optical and electron microscopy, in situ and ex situ quali-quantitative X-ray powder diffraction. The understanding of the complex reaction path is of basic importance for the optimization of industrial heating processes leading to a safe recycling of the transformed product. For the recycling of asbestos containing materials, the Italian laws require that the product of the crystal chemical transformation of asbestos containing materials must be entirely asbestos-free, and should not contain more than 0.1 wt% fraction of the carcinogenic substances such as cristobalite. Moreover, if fibrous phases other than asbestos (with length to diameter ratio >3) are found, they must have a geometrical diameter larger than 3 microm. We have demonstrated that using an interplay of different experimental techniques, it is possible to safely verify the complete transformation of asbestos minerals in this temperature-induced process. The product of transformation of cement-asbestos (CATP) has a phase composition similar to that of a natural or a low temperature clinker with the exception of having a larger content of aluminium, iron and magnesium. This product can be safely recycled for the production of stoneware tile mixtures. The addition of 3-5 mass% of CATP does not bear significant variations to the standard parameters of white porcelain tile mixtures.

Nitropravastatin stimulates reparative neovascularisation and improves recovery from limb Ischaemia in type-1 diabetic mice

BACKGROUND AND PURPOSE

Mature endothelial cells and their progenitors are dysfunctional in diabetes, resulting in deficient neovascularisation following arterial occlusion. This study aimed to evaluate the therapeutic activity of a nitric oxide (NO) releasing statin in the setting of experimental diabetes and peripheral ischaemia.

EXPERIMENTAL APPROACH

The effects of NCX 6550, an NO-releasing pravastatin derivative, on angiogenesis in ischaemic limbs was studied in normoglycaemic mice or mice made diabetic by treatment with streptozotocin (STZ). Control mice received an equimolar dosage of the parent statin compound, pravastatin. The therapeutic action of NCX 6550 was also tested in mice lacking the gene for endothelial nitric oxide synthase (eNOS).

KEY RESULTS

In normoglycaemic or STZ-diabetic CD1 mice, only NCX 6550 stimulated skeletal muscle revascularisation. In addition, NCX 6550 induced greater improvement in limb reperfusion and salvage, than pravastatin. The number of circulating endothelial progenitor cells was decreased in STZ-diabetic mice, this defect being prevented by NCX 6550 and, to a lesser extent by pravastatin. In vitro, high glucose concentrations reduced the migratory capacity of endothelial progenitor EPCs, which was partly reversed by preincubation with pravastatin and completely reversed by NCX 6550. The postischaemic recovery of eNOS knockout mice was severely impaired as a consequence of depressed angiogenesis and this recovery was improved by treatment with NCX 6550, but not with pravastatin.

CONCLUSIONS AND IMPLICATIONS

These findings indicate that incorporation of a bioactive NO moiety improves the therapeutic profile of statins for the treatment of peripheral vascular disease.

Murine models of myocardial and limb ischemia: Diagnostic end-points and relevance to clinical problems

Ischemic disease represents the new epidemic worldwide. Animal models of ischemic disease are useful because they can help us to understand the underlying pathogenetic mechanisms and develop new therapies. The present review article summarizes the results of a consensus conference on the status and future development of experimentation in the field of cardiovascular medicine using murine models of peripheral and myocardial ischemia. The starting point was to recognize the limits of the approach, which mainly derive from species- and disease-related differences in cardiovascular physiology. For instance, the mouse heart beats at a rate 10 times faster than the human heart. Furthermore, healing processes are more rapid in animals, as they rely on mechanisms that may have lost relevance in man. The main objective of the authors was to propose general guidelines, diagnostic end points and relevance to clinical problems.

Benfotiamine accelerates the healing of ischaemic diabetic limbs in mice through protein kinase B/Akt-mediated potentiation of angiogenesis and inhibition of apoptosis

AIMS/HYPOTHESIS

Benfotiamine, a vitamin B1 analogue, reportedly prevents diabetic microangiopathy. The aim of this study was to evaluate whether benfotiamine is of benefit in reparative neovascularisation using a type I diabetes model of hindlimb ischaemia. We also investigated the involvement of protein kinase B (PKB)/Akt in the therapeutic effects of benfotiamine.

METHODS

Streptozotocin-induced diabetic mice, given oral benfotiamine or vehicle, were subjected to unilateral limb ischaemia. Reparative neovascularisation was analysed by histology. The expression of Nos3 and Casp3 was evaluated by real-time PCR, and the activation state of PKB/Akt was assessed by western blot analysis and immunohistochemistry. The functional importance of PKB/Akt in benfotiamine-induced effects was investigated using a dominant-negative construct.

RESULTS

Diabetic muscles showed reduced transketolase activity, which was corrected by benfotiamine. Importantly, benfotiamine prevented ischaemia-induced toe necrosis, improved hindlimb perfusion and oxygenation, and restored endothelium-dependent vasodilation. Histological studies revealed the improvement of reparative neovascularisation and the inhibition of endothelial and skeletal muscle cell apoptosis. In addition, benfotiamine prevented the vascular accumulation of advanced glycation end products and the induction of pro-apoptotic caspase-3, while restoring proper expression of Nos3 and Akt in ischaemic muscles. The benefits of benfotiamine were nullified by dominant-negative PKB/Akt. In vitro, benfotiamine stimulated the proliferation of human EPCs, while inhibiting apoptosis induced by high glucose. In diabetic mice, the number of circulating EPCs was reduced, with the deficit being corrected by benfotiamine.

CONCLUSIONS/INTERPRETATION

We have demonstrated, for the first time, that benfotiamine aids the post-ischaemic healing of diabetic animals via PKB/Akt-mediated potentiation of angiogenesis and inhibition of apoptosis. In addition, benfotiamine combats the diabetes-induced deficit in endothelial progenitor cells.

[Shift-work and cardiovascular diseases among chemical industry workers]

In order to assess the prevalence of cardiovascular abnormalities among shift workers, who were free from such abnormalities at the time of hiring, compared to day workers and ex-shift workers, we studied the QTc interval and several cardiovascular risk factors in 61 chemical workers, including 40 shift workers, 11 day workers, and 10 ex-shift workers. We found a high prevalence rate of ischemic heart disease and conduction abnormalities among ex-shift workers (5/10, 50%). We did not observe variations in the QTc interval among the three groups. The occurrence of cardiovascular disease is a reason for moving workers to day work. Therefore, the shift workers group in our study might have been selected among subjects with a healthier lifestyle preventing side effects on their cardiovascular system.

The impact of COLIPA guidelines for assessment of skin compatibility on the development of cosmetic products

After the VI Amendment to the Cosmetic Directive (93/35/EEC), the COLIPA, the European Cosmetic Toiletries and Perfumery Association, published the 'Cosmetic Product Test Guidelines for the Assessment of Human Skin Compatibility'. The document represents a reference for the European cosmetic industry. The global nature of the VI Amendment outlines a new way of evaluating the safety of cosmetic products. It includes a marketing ban for cosmetic products that have been tested on animals and consequently implies a potential ban on the use of animals in evaluating the safety of cosmetic products. The value of the COLIPA guidelines resides in the need to set up a product information package, referred to as the dossier. The guidelines also stress the need for the protection of consumer health. These new requirements have significantly influenced the approach to product development. At the same time, scientific progress demands a more complex definition of skin compatibility.

[Spontaneous dissection of the left main coronary artery: a case report and review of the literature]

Primary spontaneous coronary artery dissection occurs rarely. Compared to usual acute coronary syndromes, it occurs in relatively young people, particularly in women in the peripartum or early post-partum period. The etiology of spontaneous coronary artery dissection remains unclear; there have been less than 150 cases reported in the literature, and only 28 cases documented in the left main coronary artery. This article reports the clinical course of a patient with primary spontaneous left main coronary artery dissection who was treated with coronary artery bypass grafting after clinical steadiness.

rpoB mutations in multidrug-resistant strains of Mycobacterium tuberculosis isolated in Italy

Mutations of rpoB associated with rifampin resistance were studied in 37 multidrug-resistant (MDR) clinical strains of Mycobacterium tuberculosis isolated in Italy. At least one mutated codon was found in each MDR strain. It was always a single-base substitution leading to an amino acid change. Nine different rpoB alleles, three of which had not been reported before, were found. The relative frequencies of specific mutations in this sample were different from those previously reported from different geographical areas, since 22 strains (59.5%) carried the mutated codon TTG in position 531 (Ser-->Leu) and 11 (29.7%) had GAC in position 526 (His-->Asp).

In vitro efficacy evaluation of cosmetic products: a pool of tests on cultured cells

The efficacy of cosmetic products and active substances have been investigated on human keratinocytes cell line on a pool of tests. The work aimed to study the possible modifications of the biological parameters tested (cytotoxicity and cytoskeleton morphology) related to the cellular adhesion function. The results have permitted to define different activities, for the different products, compared to the untreated culture and to their placebo.

Blockade of delta-opioid receptors in the nucleus accumbens prevents ethanol-induced stimulation of dopamine release

Naltrindole, a specific delta-opioid antagonist, infused by reverse dialysis in the nucleus accumbens of freely moving rats completely prevented the increase in extracellular dopamine concentrations elicited in the nucleus accumbens by ethanol (1.0 g/kg i.p.) as well as by the delta-opioid receptor agonist [D-Ala2]deltorphin II (50 microM), also perfused by reverse dialysis, but not by cocaine (15 mg/kg s.c.). The results provide in vivo evidence for a critical role of delta-opioid receptors in the dopamine-releasing properties of ethanol in vivo.