Assessment of SARS-CoV-2 airborne infection transmission risk in public buses.

Public transport environments are thought to play a key role in the spread of SARS-CoV-2 worldwide. Indeed, high crowding indexes (i.e. high numbers of people relative to the vehicle size), inadequate clean air supply, and frequent extended exposure durations make transport environments potential hotspots for transmission of respiratory infections. During the COVID-19 pandemic, generic mitigation measures (e.g. physical distancing) have been applied without also considering the airborne transmission route. This is due to the lack of quantified data about airborne contagion risk in transport environments. In this study, we apply a novel combination of close proximity and room-scale risk assessment approaches for people sharing public transport environments to predict their contagion risk due to SARS-CoV-2 respiratory infection. In particular, the individual infection risk of susceptible subjects and the transmissibility of SARS-CoV-2 (expressed through the reproduction number) are evaluated for two types of buses, differing in terms of exposure time and crowding index: urban and long-distance buses. Infection risk and reproduction number are calculated for different scenarios as a function of the ventilation rates (both measured and estimated according to standards), crowding indexes, and travel times. The results show that for urban buses, the close proximity contribution significantly affects the maximum occupancy to maintain a reproductive number of <1. In particular, full occupancy of the bus would be permitted only for an infected subject breathing, whereas for an infected subject speaking, masking would be required. For long-distance buses, full occupancy of the bus can be maintained only if specific mitigation solutions are simultaneously applied. For example, for an infected person speaking for 1 h, appropriate filtration of the recirculated air and simultaneous use of FFP2 masks would permit full occupancy of the bus for a period of almost 8 h. Otherwise, a high percentage of immunized persons (>80%) would be needed.

Epidemiological and clinical features of prosthetic joint infections caused by gram-negative bacteria.

OBJECTIVE: To review the clinical literature focusing on epidemiology, clinical presentation and outcomes of prosthetic joint infections (PJIs) due to gram-negative bacteria (GNB) and to report the experience of a multicentric cohort. PATIENTS AND METHODS: A retrospective, observational, cohort study was performed in three Italian hospitals. All consecutive PJIs caused by GNB over a 12-year period (from May 2007 to March 2018) were enrolled. Epidemiological, clinical, microbiological and therapeutic features were described. Factors related to treatment failure (defined as the occurrence of death, amputation or starting long-term antimicrobial suppression therapy) were analysed with a Cox regression model. RESULTS: A total of 82 PJIs due to GNB (42.7% men; median age 73 years) were studied. The implants included 65 (79.3%) hip, 16 (19.5%) knee and one (1.2%) shoulder. An early PJI was diagnosed in 16.2% of patients, a delayed PJI in 29.4% and a late PJI in 54.4%. The most common isolated organisms were Escherichia coli (21.7%) and Pseudomonas spp. (20.9%). 13.4% of the isolates were carbapenem-resistant bacteria (CRB). In 53.8% of cases a two-stage exchange arthroplasty was performed and in 32.5% a Girdlestone excision arthroplasty. The average therapeutic failure occurred in 17.7% of cases. The therapeutic failure rate of the two-stage was 10%. PJI due to CRB was identified as a potential risk factor for failure (aHR 4.90; IC 95%, 0.96-25.08; p=0.05). The therapeutic failure rate in the CRB group was 50%. CONCLUSIONS: The treatment with the two-stage procedure for PJIs caused by GNB seems to be associated with a low rate of failure, while PJI due to CRB seems to be related to the worst outcome.

Daptomycin for the treatment of osteomyelitis and orthopaedic device infections: real-world clinical experience from a European registry.

Osteomyelitis is a serious infection predominantly caused by Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). Orthopaedic device-related infections are complex and require a careful combination of surgical intervention and antimicrobial therapy. Daptomycin, a cyclic lipopeptide, effectively penetrates soft tissue and bone and demonstrates rapid concentration-dependent bactericidal activity against Gram-positive pathogens. This retrospective, non-interventional study evaluated clinical outcomes in patients with osteomyelitis or orthopaedic device infections treated with daptomycin from the European Cubicin® Outcomes Registry and Experience (EU-CORE(SM)) study. Patients were treated between January 2006 and April 2012, with follow-up to 2014. Clinical outcomes were assessed as success (cured or improved), failure or non-evaluable. Of 6,075 patients enrolled, 638 (median age, 63.5 years) had primary infections of osteomyelitis or orthopaedic device infections, 224 had non-prosthetic osteomyelitis, 208 had osteomyelitis related to a permanent or temporary prosthetic device, and 206 had orthopaedic device infections. The most commonly isolated pathogen was S. aureus (214 [49.1 %]; 24.8 % were MRSA). Overall, 455 (71.3 %) patients had received previous antibiotic therapy. Patients underwent surgical interventions, including tissue (225 [35.3 %]) and bone (196 [30.7 %]) debridement, as part of their treatment. Clinical success rates were 82.7 % and 81.7 % in S. aureus and coagulase-negative staphylococcal infections. Adverse events (AEs) and serious AEs assessed as possibly related to daptomycin were observed in 6.7 % and 1.9 % of patients, respectively. Daptomycin was discontinued by 5.5 % of patients due to AEs and 10 (1.6 %) deaths were reported. In conclusion, daptomycin was effective and safe in patients with osteomyelitis or orthopaedic device infections.

TD-UAPO diffracted field evaluation for penetrable wedges with acute apex angle.

This study deals with the time domain (TD) diffraction phenomenon related to a penetrable acute-angled dielectric wedge. The transient diffracted field originated by an arbitrary function plane wave is evaluated via a convolution integral involving the TD diffraction coefficients, which are determined here in closed form, starting from the knowledge of the frequency domain counterparts. In particular, the inverse Laplace transform is applied to the uniform Asymptotic physical optics diffraction coefficients valid for the internal region of the wedge and the surrounding space. Diffraction by penetrable wedges in the TD framework is a challenging problem from the analytical point of view, and no other expressions are available in closed form for the diffraction coefficients associated with the considered problem.

Diffraction by 90° penetrable wedges with finite conductivity.

This study concerns the diffraction problem relevant to a plane wave normally incident with respect to a 90° wedge. A penetrable material with finite conductivity forms the structure. A high-frequency solution is here obtained by adopting a physical optics approximation for the equivalent electric and magnetic surface currents involved in the radiation integrals used to represent the fields scattered in the inner region of the wedge and the surrounding space. Uniform asymptotic evaluations of such integrals lead to closed form expressions for the diffraction coefficient in terms of the transition function of the uniform theory of diffraction and the Fresnel coefficients for the reflection and transmission mechanisms. No limitation exists on the loss tangent of the medium. Comparisons with numerical tools assess the effectiveness of the proposed solutions for the field diffracted in the inner and outer regions.

Plane-wave diffraction by an obtuse-angled dielectric wedge.

Uniform high-frequency solutions in closed form are derived for the diffraction of a plane wave normally impacting on a penetrable wedge having an obtuse apex angle and arbitrary dielectric permittivity. The approach used here takes advantage of a physical optics approximation for the electric and magnetic equivalent surface currents in the scattering integrals related to the inner region of the wedge and the surrounding space. Numerical tests and comparisons with finite-difference time-domain results demonstrate the accuracy and effectiveness of the proposed solutions.

[Chronic osteomyelitis due to Pseudomonas aeruginosa: treatment with elastomeric infusor in an outpatient setting]. / Osteomielite cronica daPseudomonas aeruginosa:trattamento antibioticodomiciliare con impiegodi elastomero.

Chronic bacterial osteomyelitis requires long-term antibiotic treatment (at least 6-8 weeks). After in-hospital management, patients are usually discharged and treated in outpatient settings. However, when the aetiology is represented by Gram-negative microorganisms, outpatient treatment could be difficult. Beta-lactam administration by means of an elastomeric infusor may represent an attractive approach. We report two cases of osteomyelitis due to Pseudomonas aeruginosa successfully treated with continuous ceftazidime administration via an elastomeric infusor in outpatient settings. In both cases the patients were free from clinical and laboratory signs of osteomyelitis at the end of treatment and after 12 months follow-up.

Increased sympathetic activity in normotensive offspring of malignant hypertensive parents compared to offspring of normotensive parents.

Malignant hypertension seems to be the consequence of very high blood pressure. Furthermore, an increase in sympathetic and renin-angiotensin system activity is considered to be the main mechanisms producing malignant hypertension. In the present study, 10 offspring of malignant hypertensive (OMH) parents (age 28 +/- 5 years, 7 males, 3 females, 2 white and 8 non-white) and 10 offspring of normotensive (ONT) parents (age 28 +/- 6 years, 2 males, 8 females, 3 white and 7 non-white) were evaluated. The OMH group had significantly higher (P < 0.05) casual blood pressure (125 +/- 10/81 +/- 5 mmHg) compared with ONT (99 +/- 13/67 +/- 5 mmHg). The increase in blood pressure was greater in OMH (Delta SBP = 17 +/- 2 vs Delta SBP = 9 +/- 1 mmHg in ONT) during cold pressor testing, but they had a lower increase in heart rate (Delta HR = 13 +/- 2 vs Delta HR = 20 +/- 3 bpm in ONT) during isometric exercise(handgrip test). Sympathetic activity, measured by microneurography, was significantly higher (P < 0.05) before exercise in OMH (17 +/- 6 vs 11 +/- 4 burst/min in ONT) and exhibited a greater increase (Delta = 18 +/- 10 vs Delta = 8 +/- 3 burst/min in ONT) during isometric exercise. This study showed increased sympathetic activity in OMH before exercise and a greater response during isometric exercise, suggesting an autonomic abnormality before exercise and a greater sympathetic response to physical stress in OMH compared to ONT.

Increased sympathetic activity in normotensive offspring of malignant hypertensive parents compared to offspring of normotensive parents

Malignant hypertension seems to be the consequence of very high blood pressure. Furthermore, an increase in sympathetic and renin-angiotensin system activity is considered to be the main mechanisms producing malignant hypertension. In the present study, 10 offspring of malignant hypertensive (OMH) parents (age 28 ± 5 years, 7 males, 3 females, 2 white and 8 non-white) and 10 offspring of normotensive (ONT) parents (age 28 ± 6 years, 2 males, 8 females, 3 white and 7 non-white) were evaluated. The OMH group had significantly higher (P < 0.05) casual blood pressure (125 ± 10/81 ± 5 mmHg) compared with ONT (99 ± 13/67 ± 5 mmHg). The increase in blood pressure was greater in OMH (Ä SBP = 17 ± 2 vs Ä SBP = 9 ± 1 mmHg in ONT) during cold pressor testing, but they had a lower increase in heart rate (Ä HR = 13 ± 2 vs Ä HR = 20 ± 3 bpm in ONT) during isometric exercise (handgrip test). Sympathetic activity, measured by microneurography, was significantly higher (P < 0.05) before exercise in OMH (17 ± 6 vs 11 ± 4 burst/min in ONT) and exhibited a greater increase (Ä = 18 ± 10 vs Ä = 8 ± 3 burst/min in ONT) during isometric exercise. This study showed increased sympathetic activity in OMH before exercise and a greater response during isometric exercise, suggesting an autonomic abnormality before exercise and a greater sympathetic response to physical stress in OMH compared to ONT.

Etiology of prosthetic joint infections in a tertiary care centre in Italy.

Prosthetic joint infections (PJIs) represent a severe complication in orthopaedics. Coagulase-negative staphylococci (CoNS) and Staphylococcus aureus represent the most frequent cause, but Gram-negatives have also been reported. With a view to describing the aetiology of PJIs diagnosed from January 2005 to September 2007 at S. Corona Hospital in Pietra Ligure, Italy, we conducted retrospective analysis of pathogens isolated from PJIs by means of surgical specimens, needle aspirates or swabs of fistula (3 samples). During the study period 228 PJIs were described and 141 (62%) were microbiologically documented and evaluated. Early and delayed infections represented 45% of episodes, while late infections were observed in 55%. The aetiology was mono-microbial in 84% of cases, and polymicrobial in 16%. CoNS and S. aureus were the most frequently isolated pathogens. In early and delayed infections methicillin resistant CoNS were 30% and 24%, respectively, while in late infections they were 17%. Methicillin-resistant S. aureus was isolated in 13% of early, 22% of delayed and 15% of late infections. Gram-negatives were described in 16% of episodes without differences being found in the three groups. In our report staphylococci represented the most frequent cause of PJIs. Methicillin-resistant strains were more frequently isolated in early and delayed infections, but their frequency in late episodes was not negligible. Polymicrobial infections and Gram-negative infections were also frequent.

[Air quality control systems: heating, ventilating, and air conditioning (HVAC)]. / Sistemi di controllo della qualità dell'aria: gli impianti di condizionamento.

After a brief illustration of the principal layout schemes of Heating, Ventilating, and Air Conditioning (HVAC), the first part of this paper summarizes the standards, both voluntary and compulsory, regulating HVAC facilities design and installation with regard to the question of Indoor Air Quality (IAQ). The paper then examines the problem of ventilation systems maintenance and the essential hygienistic requirements in whose absence HVAC facilities may become a risk factor for people working or living in the building. Lastly, the paper deals with HVAC design strategies and methods, which aim not only to satisfy comfort and air quality requirements, but also to ensure easy and effective maintenance procedures.

[Criteria for assessing severely hot environments: from the WBGT index to the PHS (predicted heat strain) model]. / Criteri di valutazione degli ambienti severi caldi: dall'indice WBGT al modello PHS (predicted heat strain).

BACKGROUND: The present study deals with the main methods for assessment of hot environments: i.e., WBGT, SWreq and PHS. It is stressed how the WBGT index, which is strictly empirical, although a very practical tool for the assessment of the hot environments, can only be used for a rough evaluation of heat stress, and especially for a not very high metabolic rate (M<175 W/m2). On the contrary, the SWreq method, which is based on both subject-environment heat exchange and the effect of clothing, allows a better assessment of the work situation with a general reduction of the exposure limits with respect to WBGT, especially in non-uniform environments (ta not equal to tr). However, it should be noted that application of SWreq is required by the ISO standard 7243 when the WBGT limit values are exceeded. METHODS: In this study interest was extensively focused on the "Predicted Heat Strain" method, highlighting via a special software the differences in heat stress assessment related to this new approach, which will be adopted by the ISO in the next revision of standard 7933. RESULTS: The PHS method, unlike SWreq, allows the prediction of the time-response of the main physiological variables of interest (i.e., skin temperature, core temperature and sweat rate). Moreover thanks to better modelling of heat exchanges, the PHS method allows account to be taken of both movement and clothing effects, resulting in even more reduced exposure.

[Treatment of surface water]. / La potabilizzazione delle acque superficiali.

The present paper describes the most important treatment processes to be used for water for human consumption. Advantages and disadvantages of alternative disinfectants are discussed and a critical assessment of the problem associated to disinfection byproducts is included.

Postural orientation: age-related changes in variability and time-to-boundary.

The relation between age-specific postural instability and the detection of stability boundaries was examined. Balance control was investigated under different visual conditions (eyes open/closed) and postural orientations (forward/backward lean) while standing on a force platform. Dependent variables included center of pressure variability and the time-to-contact of the center of pressure with the stability boundaries around the feet (i.e., time-to-boundary). While leaning maximally, older individuals (ages 55-69) showed increased center of pressure variability compared to no lean, while younger subjects (ages 24-38) showed a decrease. These significant differences were found only in anterior-posterior direction. No significant age-specific differences were found between eyes open and eyes closed conditions. Time-to-boundary analysis revealed reduced spatio-temporal stability margins in older individuals in both anterior-posterior and medio-lateral directions. Time-to-boundary variability, however, was not significantly different between the groups in both medio-lateral and anterior-posterior direction. These results show the importance of boundary relevant center of pressure measures in the study of postural control, especially concerning the lateral instability often observed in older adults.

Dysregulation of peripheral and central chemoreflex responses in Chagas' heart disease patients without heart failure.

BACKGROUND: The peripheral and central chemoreflexes are important autonomic mechanisms for regulating breathing and cardiovascular function. Although pathological inflammatory infiltration of the peripheral chemoreceptors and central nervous system has been reported in Chagas' disease, functional evaluation of chemoreflexes has not yet been performed. METHODS AND RESULTS: The hypothesis that chemoreflex function is altered in patients with Chagas' heart disease (CH) but normal left ventricle function was tested in 12 CH patients and 13 matched control subjects. The ventilatory rate, minute ventilation, heart rate, mean arterial pressure, forearm blood flow, forearm vascular resistance, and venous norepi-nephrine responses to hypoxia and hypercapnia were determined. During hypoxia, the decrease in oxygen saturation was smaller in CH patients, despite a similar ventilatory response between groups. Both groups showed an increase in heart rate during hypoxia, but this response was blunted in CH patients. Although the mean arterial pressure response to hypoxia was similar in both groups, forearm vascular resistance significantly decreased in control subjects while remaining unchanged in CH patients. Moreover, a significant increase in plasma norepinephrine levels elicited by stimulation of peripheral chemoreceptors was observed only in the CH group. During hypercapnia, the increase in minute ventilation was smaller in CH patients, who did not exhibit the increase in norepinephrine observed in control subjects. CONCLUSIONS: These data suggest that CH potentiates respiratory, cardiovascular, and autonomic responses to peripheral chemoreceptor activation by hypoxia in patients with normal left ventricular function. The ventilatory and sympathetic responses to central chemoreceptor activation by hypercapnia, however, are significantly blunted.

The effects of a diode laser (810 nm) on pigmented guinea-pig skin.

Various types of lasers, such as the Q-switched ruby laser and the Alexandrite laser, cause selective damage to cutaneous pigmented cells and are currently used in the therapy of pigmented lesions. The aim of this study was to evaluate the effects of a diode laser at a wavelength of 810 nm on pigmented guinea-pig skin. The diode laser was supplied by OcuLight Iris Medical Instruments, Inc. and was used to deliver 0.15, 0.2, 0.3, 0.4, 0.5, 1 and 1.5 J/cm2 laser beams in micropulses of 100 micros. The study was carried out on albino and black-spotted guinea pigs (GP). After irradiation, punch biopsies were taken and analysed by light and electron microscopy. Albino animals developed just a few signs of cutaneous injury. This mostly consisted of spongiotic disarray, after the highest doses were administered (>1 J/cm2). In the black skin of spotted GPs alterations appeared at 0.15 J/cm2 and included melanosome damage and, at doses higher than 0.3 J/cm2, also melanocyte damage. These observations demonstrate that the diode laser at 810 nm selectively affects pigmented structures and that the cellular targets of diode laser radiation are the melanosomes. The diode laser specificity for melanin may provide a biological basis for the treatment of pigmented superficial cutaneous lesions.

Decreased cardiopulmonary baroreflex sensitivity in Chagas' heart disease.

No study has been performed on reflexes originating from receptors in the heart that might be involved in the pathological lesions of Chagas' heart disease. Our study was undertaken to analyze the role of cardiopulmonary reflex on cardiovascular control in Chagas' disease. We studied 14 patients with Chagas' disease without heart failure and 12 healthy matched volunteers. Central venous pressure, arterial blood pressure, heart rate, forearm blood flow, and forearm vascular resistance were recorded during deactivation of cardiopulmonary receptors. By reducing central venous pressure by applying -10 and -15 mm Hg of negative pressure to the lower body, we observed (a) a similar decrease of central venous pressure in both groups; (b) a marked increase in forearm vascular resistance in the control group but a blunted increase in the Chagas' group; and (c) no significant changes in blood pressure and heart rate. To analyze cardiopulmonary and arterial receptors, we applied -40 mm Hg of lower-body negative pressure. As a consequence, (a) central venous pressure decreased similarly in both groups; (b) blood pressure was maintained in the control group, whereas in patients with Chagas' disease, a decrease in systolic and mean arterial pressure occurred; (c) heart rate increased in both groups; and (d) forearm vascular resistance increased significantly and similarly in both groups. Unloading of receptors with low levels of lower-body negative pressure did not increase forearm vascular resistance in patients with Chagas' disease, which suggests that the reflex mediated by cardiopulmonary receptors is impaired in patients with Chagas' disease without heart failure. Overall control of circulation appears to be compromised because patients did not maintain blood pressure under high levels of lower-body negative pressure.