Chemical Speciation of Selenium and Mercury as Determinant of Their Neurotoxicity.

The antagonism of mercury toxicity by selenium has been well documented. Mercury is a toxic metal, widespread in the environment. The main target organs (kidneys, lungs, or brain) of mercury vary depending on its chemical forms (inorganic or organic). Selenium is a semimetal essential to mammalian life as part of the amino acid selenocysteine, which is required to the synthesis of the selenoproteins. This chapter has the aim of disclosing the role of selenide or hydrogen selenide (Se-2 or HSe-) as central metabolite of selenium and as an important antidote of the electrophilic mercury forms (particularly, Hg2+ and MeHg). Emphasis will be centered on the neurotoxicity of electrophile forms of mercury and selenium. The controversial participation of electrophile mercury and selenium forms in the development of some neurodegenerative disease will be briefly presented. The potential pharmacological use of organoseleno compounds (Ebselen and diphenyl diselenide) in the treatment of mercury poisoning will be considered. The central role of thiol (-SH) and selenol (-SeH) groups as the generic targets of electrophile mercury forms and the need of new in silico tools to guide the future biological researches will be commented.

Modeling birds on wires.

In this paper we introduce a mathematical model to study the group dynamics of birds resting on wires. The model is agent-based and postulates attraction-repulsion forces between the interacting birds: the interactions are "topological", in the sense that they involve a given number of neighbors irrespective of their distance. The model is first mathematically analyzed and then simulated to study its main properties: we observe that the model predicts birds to be more widely spaced near the borders of each group. We compare the results from the model with experimental data, derived from the analysis of pictures of pigeons and starlings taken in New Jersey: two different image elaboration protocols allow us to establish a good agreement with the model and to quantify its main parameters. We also discuss the potential handedness of the birds, by analyzing the group organization features and the group dynamics at the arrival of new birds. Finally, we propose a more refined mathematical model that describes landing and departing birds by suitable stochastic processes.

Capillary zone electrophoresis for determination of vildagliptin (a DPP-4 inhibitor) in pharmaceutical formulation and comparative study with HPLC.

A stability-indicating capillary zone electrophoresis (CZE) method was validated for the determination of vildagliptin (VLG) in pharmaceutical dosage forms using ranitidine hydrochloride (RH) as internal standard. The CZE method was carried out in a fused silica capillary (64.5 cm total length and 56.0 cm effective length, 50 microm i.d.) by applying a potential of 25 kV (positive polarity), hydrodynamic injection by 50 mbar for 5 s and the temperature of the capillary cartridge was 25 degreesC. The selected background electrolyte (BGE) consisted of 25 mM potassium phosphate (pH 8.0) with UV/PDA detection at 207 nm. The electrophoretic separation was obtained within 6 min and was linear in the range of 50-200 microg/mL (r= 0.9994). The specificity and the stability-indicating capability were demonstrated through degradation studies, which also showed that there was no interference of the formulation excipients. The method was validated in accordance to ICH guidelines acceptance criteria for specificity, linearity, precision, accuracy, robustness and system suitability. The proposed method was compared with HPLC method previously validated for this drug, and statistical analysis showed no significant difference between the methods.

[Occupational diseases caused by artificial optical radiation (AOR)]. / Le malattie professionali da radiazioni ottiche artificiali (ROA).

BACKGROUND: Italian national legislation guarantees safety and health for workers exposed to artificial optical radiations (AOR) by Legislative Decree 81/2008. OBJECTIVES AND METHODS: Effects and damages to health resulting from AOR exposure were analyzed from literature data. RESULTS: Ultraviolet radiations (UV), particularly those in the wavelength range between 220 and 310 nm, causes chronic conjunctivitis and kerato-conjunctivitis. Skin cancer caused by UV exposure included basal cell carcinoma, squamous cell carcinoma and melanoma. As regards Infrared Radiations (portion of the spectrum between 780 nm and 1 mm), the biological effect is essentially of thermal nature. Exposure to blue light (portion ofthe spectrum of visible light radiation in a wavelength range between 380 and 550 nm) causes exclusively retinal damage and is considered to be responsible for the development of situations of age-related macular degeneration (AMD). Even if experimental data are available, at the present time there is still no epidemiological evidence of retinal damage caused by blue light. CONCLUSIONS: The forensic criteria for investigating the causality link between occupational exposure to AOR and damage, and the methodology necessary for the assessment process, are reported. Two lists of occupational diseases which were included in the Italian Ministerial Decrees, issued respectively on April 2008 and 11 December 2009, are also considered. Lastly, on the basis of the current existing guidelines and scientific evidence, the authors propose occupational health surveillance protocols for workers exposed to AOR risk.

Optimization versus randomness for car traffic regulation.

We focus on the differences among the analytical optimization of traffic flow on a road network, modeled by a fluid-dynamic approach, and a dynamic random one. In particular, two real urban networks are analyzed: Re di Roma Square, in Rome, and Via Parmenide crossing, in Salerno. With such two examples, it is possible to show that dynamic random algorithms are not the right choice for the improvement of traffic conditions.

Cancer immunotherapy, mathematical modeling and optimal control.

Clinical immunologists, among other problems, routinely face a question: what is the best time and dose for a certain therapeutic agent to be administered to the patient in order to decrease/eradicate the pathological condition? In cancer immunotherapies the therapeutic agent is something able to elicit an immune response against cancer. The immune response has its own dynamics that depends on the immunogenicity of the therapeutic agent and on the duration of the immune response. The question then is "how can we decide when and how much of the drug to inject so to have a prolonged and effective immune response to the cancer?". This question can be addressed in mathematical terms in two stages: first one construct a mathematical model describing the cancer-immune interaction and secondly one applies the theory of optimal control to determine when and to which extent to stimulate the immune system by means of an immunotherapeutic agent administered in discrete variable doses within the therapeutic period. The solution of this mathematical problem is described and discussed in this article. We show that the method employed can be applied to find the optimal protocol in a variety of clinical problems where the kinetics of the drug or treatment and its influence on the physiologic/pathologic functions have been described by a system of ordinary differential equations.

[The preventive ergophthalmic evaluation of work places in call centers: a useful instrument for the prevention of work related asthenopic symptoms]. / La valutazione ergoftalmica preventiva dei posti di lavoro nei call center: un valido strumento di prevenzione dei disturbi astenopici occupazionali.

The study of a correct lay-out of work places equipped with VDT/PC in call centres, if carried out before the beginning of work activities needs an interdisciplinary cooperation among OH&S operators. However, such a preventive evaluation can relevantly reduce onset and severity of asthenopic symptoms frequently reported by this kind of operators. Consequently, such preventive evaluation can avoid the necessity of carrying out those complex and expensive structural lay-out modifications, which are frequently needed to reduce VDT/PC workers' asthenopic symptoms.

[Adequacy and reliability of orthoanalyzer Ergovision for job-fitness evaluation]. / Adeguatezza e affidabilità dell'ortoanalizzatore Ergovision nel giudizio di idoneità specifica.

The aim of this research was to evaluate the Ergovision Screener (ES) accuracy e validity by a confrontation with the conventional ophthalmic check (OC), for the medical evaluation of job fitness. A population of 100 VDU operators was considered. Each subject underwent randomly both the ES and the ophthalmic check visit. Several test carried out by the Ergovision Screener were not consistent with the conventional ophthalmic check. In a number of cases, high false positive ratio have been found, which could lead to unnecessary further examinations. For all these reasons we believe that the ES is not an appropriate instrument for the medical evaluation of job fitness.

[Analysis and evaluation of the visual effort in remote-control public traffic operators working with computer-based equipments]. / Analisi e valutazione dell'impegno visivo in operatori addetti al telecontrollo del traffico pubblico mediante sistemi informatizzati.

The aim of this study is the objective evaluation of the visual effort in 6 public traffic controllers (4 male, 2 female, mean age 29,6), by means of electronic equipment. The electronic equipment quantify the observation distance and the observation time for each controller's occupational visual field. The quantification of these parameters is obtained by the emission of ultrasound at 40 KHz from an emission sensor (placed by the VDT screen) and the ultrasound reception by means of a receiving sensor (placed on the operator's head). The travelling time of the ultrasound (US), as the air speed is known and costant (about 340 m/s), it is used to calculate the distance between the emitting and the receiving sensor. The results show that the visual acuity required is of average level, while accommodation's and convergence's effort vary from average to intense (depending on the visual characteristics of the operator considered), ranging from 26,41 and 43,92% of accommodation and convergence available in each operator. The time actually spent in "near observation within the c.v.p." (Tscr) was maintained in a range from 2h 54' and 4h 05'.

[Work efficiency and lighting conditions: an experimental study]. / Efficienza lavorativa e condizioni illuminotecniche: studio sperimentale.

Thirty-two voluntary subjects were selected, not suffering either from any degenerative ophthalmic diseases or refraction and ocular motility alterations. Each subject underwent close visual task experimental sessions (e.g. PC usage), under monitored experimental conditions. Aim of the study is the assessment of working efficiency effects caused by lighting conditions characterized by "according to law" illuminations, yet in presence of high or low luminance ratios in the occupational visual field". An analysis of the data showed that high luminance ratios conditions show a decrease of the performance (decrease overall efficiency, increase in the number of errors and time of execution), which where not detected with low luminance ratios conditions. Asthenopia did not show clear differences, possibly due to the effects of the intense near work which was present in both the experimental sessions.

[Dermatitis and VDU work]. / Dermatiti e lavoro con VDT/PC.

Skin disorders like rosacea, seborrhoeic dermatitis, non-specific erythema and acne can be VDU work linked. At present, many environmental and individual causes are involved in the development of these disorders, but the former appear to be the issue to investigate more in depth.

Eye complaints in the office environment: precorneal tear film integrity influenced by eye blinking efficiency.

To achieve a common base for understanding work related eye complaints in the office environment, it is necessary to merge approaches from indoor air science, occupational health, and ophthalmology. Based on database searches, it is concluded that precorneal tear film (PTF) alteration leads to eye complaints that may be caused by: (1) thermal factors (low relative humidity; high room temperature); (2) demanding task content (attention decreases blinking and widens the exposed ocular surface area); and (3) individual characteristics (for example, tear film alterations, blinking anomalies, gland dysfunctions, and use of contact lenses). These factors and conditions are able to progressively increase water evaporation and faster thinning of the PTF, which causes dryness and dry spot formation on the cornea, possibly followed by corneal and conjunctiva epithelial alterations and eye complaints. Another possible cause of eye complaints is certain irritating chemical compounds, in addition to oxidation mixtures that are formed in reactions between ozone and unsaturated organic compounds (alkenes). The effect may be exacerbated by low relative humidity.

[Lighting condition analysis at work]. / Analisi delle condizioni illuminotecniche nei luoghi di lavoro.

Following a wide review of the national and international technical standards which make up the principal reference points when designing illumination systems for work areas, the most commonly used methods of photometric analysis are examined from both a medical and technical point of view. It can be observed that photometric analysis of the work place, which currently is almost exclusively based on the measurements of illuminance, does not appear to adequately reach the targets set by Occupational Health and Occupational Hygiene, for reasons pertaining to the anatomy and physiopathology of the visual function. Moreover, the procedures applied to evaluate the workers' subjectivity and/or symptomatology, that both in research and during on-site investigations makes use predominantly of self-administered questionnaires, shows some shortcomings in terms of reliability and validity. In conclusion, it is proposed, especially in studies regarding office environments (i) to carry out photometric analysis where primary and secondary luminance is always measured and, if light-linked subjectivity is required (ii) to make available valid and precise questionnaires whose administration be followed by a multivariate data analysis.

Photometry in the workplace: the rationale for a new method.

OBJECTIVES: The assessment of lighting conditions in workplaces has traditionally focused on the measurement of illuminance. The rationale for a new method for the detailed evaluation of natural and artificial light in 'near work' situations, involving the assessment of luminance, is described. METHODS: The procedure comprises four successive phases: (1) identify object/images observed during work tasks; (2) outline the area of the operator's visual field where gaze is predominantly directed; (3) measure luminances in the visual field, pin-pointing all sources of primary and secondary luminance, and constructing iso-luminance maps; and (4) compare luminance ratios. RESULTS: The procedure was illustrated using the common example of near work in an office environment. Illuminance was found to be inadequate to evaluate the effects of natural and artificial environmental light in the workplace. This is due to the fact that the luxmeter is designed to integrate the light detected over a large angle, whereas in near work the operator's retina is mainly stimulated by light originating from objects/images placed in the occupational visual field. CONCLUSIONS: A detailed measurement of luminance within the occupational visual field is consistent with ocular anatomy and physiology, and can be used as part of a risk assessment for visual disturbances and to rationalize lighting at workstations.

[Occupational ophthalmology and ergoophthalmology: a developing field]. / Oftalmologia occupazionale ed ergoftalmologia: un percorso in evoluzione.

In 1979 it was decided to activate, within the Institute of Occupational Health of the Milan "Università degli Studi", a new Unit of Ergophthalmology. This decision was taken owing to the progressive diffusion of "optical instruments", particularly computer-based equipment, in the world of work and to the relevance that this topic assumed among Italian occupational physicians. Since its beginning, one of the main characteristics of the Ergophthalmology Unit was an interdisciplinary approach, where occupational physicians, ophthalmologists, occupational hygienists and lighting engineers were collaborating on a daily basis. Research activities, which developed over many years and in several phases, were concerned with four main topics: 1. analysis and quantification of "near work load"; initially the investigations were mainly aimed at the evaluation of the observation distance in different tasks, followed by the development of a method which, by means of specifically designed electronic equipment, allows quantification of the accommodation and convergence required by the task; 2. development of a new method aimed at evaluating, by a photometric procedure, the luminance ratios in the "occupational visual field"; this research was carried out, both in the laboratory and during on-site investigations, in collaboration with the Dept. of Electrotechnics of Milan Polytechnic; 3. studies on the relationships between indoor microbial pollution and Computer Assisted Design work, considering that ocular conjunctiva and cornea, due to their external position, can be easily inoculated by micro-organisms present on periocular tissue and hands; this research showed that bacteria and fungi pathogenic for the eye (Staphylococcus aureus, Candida sp., Aspergillus sp.) are present on desk, keyboard and mouse, as well as in the conjunctival sac of the exposed operators; 4. studies on "blue light" and its effects on the Pigmented Retinal Epithelium (PRE) in workers exposed to halide lamps, like electricians, installers, maintenance staff, polymerization operators, etc.; the laboratory and on-site investigation that was carried out in cooperation with the Health Physics Dept. of the Milan ICP Hospital, showed that long-term exposure to low levels of irradiation could constitute an eye risk for these working populations.

Transthoracic and transesophageal echocardiographic indices predictive of sinus rhythm maintenance after cardioversion of atrial fibrillation: an echocardiographic study during direct current shock.

BACKGROUND: Up to 57% of atrial fibrillation (AF) recurrences after cardioversion take place during the first 30 days following direct current shock (DCS) delivery. Previous echocardiographic studies on sinus rhythm (SR) maintenance after cardioversion have focused mainly on parameters recorded before DCS, while other studies have reported on the indices recorded soon after delivery of the shock. METHODS: Therefore, we investigated 18 patients with nonrheumatic AF, selected to undergo DCS, by both transthoracic (TTE) and transesophageal (TEE) echocardiography performed within 10 minutes before and after the electrical shock delivery. TTE was utilized for the evaluation of left atrium and left ventricle shape as well as for mitral Doppler flow sampling, while TEE was used to evaluate left atrial appendage (LAA) morphology and function, to score the LAA spontaneous echo contrast, and to evaluate the flow of left superior pulmonary vein; the transesophageal probe was left in situ during the electrical procedure. Thirty days after cardioversion, 10 (55%) patients maintained SR (Group 1) while 8 (45%) reverted to AF (Group 2). We compared the mean values of the parameters recorded in the two groups both before and after DCS. RESULTS: Although many parameters of pre- and postcardioversion analysis proved to be significantly different between the two groups, the most marked differences were exhibited by the following postcardioversion indices: Peak Doppler flow velocity of the end-diastolic mitral flow (30.10 +/- 5.24 vs. 20.50 +/- 6.32 cm/sec, P = 0.003); sum of peak velocities of the end-diastolic contraction (A) and relaxation (A(1)) of LAA (A + A(1) = 58.20 +/- 17.02 vs. 31.25 +/- 9.27 cm/sec, P = 0.001); duration of A + A(1) (162.70 +/- 27.01 vs. 133.75 +/- 5.31 msec, P = 0.002); and sum of durations of the early diastolic forward (E) and reverse (E(1)) flow of LAA (101.90 +/- 35.15 vs. 53.33 +/- 16.33 msec, P = 0.006). CONCLUSIONS: Using a single echocardiographic examination during DCS and after induction of anesthesia, without further discomfort to patients, we were able to identify useful parameters for the prediction of future electrical activity of the heart before as well as soon after DCS. Postcardioversion indices, derived by both TTE and TEE, were even more predictive of SR maintenance after 1 month than precardioversion parameters.