Ultrafine particles: A review about their health effects, presence, generation, and measurement in indoor environments

Human exposure to aerosols has been associated with diseases and death, reducing the population's life expectancy up to a few years. Indoor particulate matter is predominant in determining human exposure to PM because people spend most of their time indoors. Ultrafine particles (UFP) impact the human body differently from PM2.5 or PM10 fractions. Therefore, scientists cannot apply the same approach to assess the effects of UFP and PM on human health. This work summarizes the health effects, generation, and measurement of ultrafine particles in indoor environments through a literature review. When indoor particle generation is low, particle concentration indoors depends strongly on outdoor aerosols, with an indoor-to-outdoor ratio below 1. In buildings with a high indoor particle generation, the average indoor-to-outdoor UFP concentration ratio can reach 14. Combustion, electric heating, and house cleaning are the main generators of UFP indoors. Current standards for UFP assessments do not provide a solid ground for accurate and reliable measurements. Moreover, the lowest detection limit of instruments used to measure UFP concentration can be significantly different while also showing poor repeatability even among instruments with the same manufacturer and model. Consequently, data supplied by studies on UFP health effects are insufficient and inconclusive. Using ultrafine portable monitors would allow determining properly human exposure to PM0.1, but such instruments are expensive for wide use. Since there is a good correlation between UFP and NOX data, low-cost NOX sensors are good candidates to create a dense and accurate monitoring network of UFP, including indoor environments

Pneumatic wound compression after hip fracture surgery did not reduce postoperative blood transfusion: A randomized controlled trial involving 292 fractures

Background and purpose Patients with fracture of the proximal femur often undergo blood transfusion. A pneumatic compression bandage has been shown to reduce transfusion after primary hip arthroplasty for osteoarthritis. In this randomized trial, we evaluated the efficacy of this bandage following surgery for hip fracture

A Mitosis Block Links Active Cell Cycle with Human Epidermal Differentiation and Results in Endoreplication

How human self-renewal tissues co-ordinate proliferation with differentiation is unclear. Human epidermis undergoes continuous cell growth and differentiation and is permanently exposed to mutagenic hazard. Keratinocytes are thought to arrest cell growth and cell cycle prior to terminal differentiation. However, a growing body of evidence does not satisfy this model. For instance, it does not explain how skin maintains tissue structure in hyperproliferative benign lesions. We have developed and applied novel cell cycle techniques to human skin in situ and determined the dynamics of key cell cycle regulators of DNA replication or mitosis, such as cyclins E, A and B, or members of the anaphase promoting complex pathway: cdc14A, Ndc80/Hec1 and Aurora kinase B. The results show that actively cycling keratinocytes initiate terminal differentiation, arrest in mitosis, continue DNA replication in a special G2/M state, and become polyploid by mitotic slippage. They unambiguously demonstrate that cell cycle progression coexists with terminal differentiation, thus explaining how differentiating cells increase in size. Epidermal differentiating cells arrest in mitosis and a genotoxic-induced mitosis block rapidly pushes epidermal basal cells into differentiation and polyploidy. These observations unravel a novel mitosis-differentiation link that provides new insight into skin homeostasis and cancer. It might constitute a self-defence mechanism against oncogenic alterations such as Myc deregulation

Global Regulation of Nucleotide Biosynthetic Genes by c-Myc

The c-Myc transcription factor is a master regulator and integrates cell proliferation, cell growth and metabolism through activating thousands of target genes. Our identification of direct c-Myc target genes by chromatin immunoprecipitation (ChIP) coupled with pair-end ditag sequencing analysis (ChIP-PET) revealed that nucleotide metabolic genes are enriched among c-Myc targets, but the role of Myc in regulating nucleotide metabolic genes has not been comprehensively delineated.Here, we report that the majority of genes in human purine and pyrimidine biosynthesis pathway were induced and directly bound by c-Myc in the P493-6 human Burkitt's lymphoma model cell line. The majority of these genes were also responsive to the ligand-activated Myc-estrogen receptor fusion protein, Myc-ER, in a Myc null rat fibroblast cell line, HO.15 MYC-ER. Furthermore, these targets are also responsive to Myc activation in transgenic mouse livers in vivo. To determine the functional significance of c-Myc regulation of nucleotide metabolism, we sought to determine the effect of loss of function of direct Myc targets inosine monophosphate dehydrogenases (IMPDH1 and IMPDH2) on c-Myc-induced cell growth and proliferation. In this regard, we used a specific IMPDH inhibitor mycophenolic acid (MPA) and found that MPA dramatically inhibits c-Myc-induced P493-6 cell proliferation through S-phase arrest and apoptosis.Taken together, these results demonstrate the direct induction of nucleotide metabolic genes by c-Myc in multiple systems. Our finding of an S-phase arrest in cells with diminished IMPDH activity suggests that nucleotide pool balance is essential for c-Myc's orchestration of DNA replication, such that uncoupling of these two processes create DNA replication stress and apoptosis

NEW SYNTHETIC NANO-AEROSOL FOR ACCELERATED REALISTIC AGEING OF AIR FILTERS

To assess reliably the energy impact of air filters, it is essential to ascertain changes of their airflow resistance during their whole service life and not just when they are clean. Current laboratory standards simulate the ageing of air filters by dispersing and loading synthetic dusts with particle size distribution (PSD) completely different from the particulate matter (PM) found in urban atmospheres. Since the size (diameter) of aerosol particles is especially important in determining the kinetics of the clogging process of an air filter, this technique does not replicate the real behavior of the filters in operation. The current methods used for artificial filter ageing are considered acceptable for rating and comparing the performance of air filters, but do not provide an accurate prediction of their airflow resistance increase in a real environment. Therefore, the duration and energy-use assessment of HVAC filters cannot be reliably estimated by means of current laboratory test dusts. We describe various methods for generating nanoparticles having approximately the same particle size distribution of a typical urban aerosol, but at higher mass concentrations. The purpose is to allow accelerated ageing in a similar way to what happens in actual service conditions. The paper describes the thermal aerosol generator chosen to produce the desired particle size distribution of the synthetic aerosol in an existing test rig according to ISO 16890:2016 specifications. This generator produces a high number of nanoparticles by burning a salt stick (e.g. made with KCl) with an oxy-propane flame. The salt vapor condenses in the air stream to form a cloud of ultrafine particles. We present some preliminary data characterizing this thermal generator and we discuss some critical aspects to standardize the new ageing procedure with a synthetic aerosol closely representing a typical urban atmosphere

New synthetic nano-aerosol for accelerated realistic ageing of air filters

To assess reliably the energy impact of air filters, it is essential to ascertain changes of their airflow resistance during their whole service life and not just when they are clean. Current laboratory standards simulate the ageing of air filters by dispersing and loading synthetic dusts with particle size distribution (PSD) completely different from the particulate matter (PM) found in urban atmospheres. Since the size (diameter) of aerosol particles is especially important in determining the kinetics of the clogging process of an air filter, this technique does not replicate the real behavior of the filters in operation. The current methods used for artificial filter ageing are considered acceptable for rating and comparing the performance of air filters, but do not provide an accurate prediction of their airflow resistance increase in a real environment. Therefore, the duration and energy-use assessment of HVAC filters cannot be reliably estimated by means of current laboratory test dusts. We describe various methods for generating nanoparticles having approximately the same particle size distribution of a typical urban aerosol, but at higher mass concentrations. The purpose is to allow accelerated ageing in a similar way to what happens in actual service conditions. The paper describes the thermal aerosol generator chosen to produce the desired particle size distribution of the synthetic aerosol in an existing test rig according to ISO 16890:2016 specifications. This generator produces a high number of nanoparticles by burning a salt stick (e.g. made with KCl) with an oxy-propane flame. The salt vapor condenses in the air stream to form a cloud of ultrafine particles. We present some preliminary data characterizing this thermal generator and we discuss some critical aspects to standardize the new ageing procedure with a synthetic aerosol closely representing a typical urban atmosphere

Future trends in laboratory methods to predict HVAC in service filter performance

Air filters installed in ventilation systems face various types of aerosols during their service life, both in residential and in commercial buildings. Their particle size is the most important characteristic and ranges from a few nanometers to a few micrometers. Different physicochemical properties, such as phase state, hygroscopicity, and morphology are also important to determine the impact of particulate matter on the behavior of air filters during their service life. Therefore, the performance of air filters installed in a Heating, Ventilation and Air-Conditioning (HVAC) system is strongly dependent on the properties of the particles captured during their service life and not only on the characteristics of the materials and technologies used to manufacture the air cleaning equipment. Current laboratory test methods for evaluating HVAC filter performance include the determination of their fractional particle removal efficiency on a limited size range, typically between 300 nm and 10000 nm. Such information is useful and meaningful for clean filters. However, air filters performance (i.e. airflow resistance and removal efficiency) changes during their service life because of particle loading. For this reason, air filters are artificially clogged in laboratory with the intent to compare one product to another and to predict their behavior while they age in HVAC systems. Current standardized air filter loading procedures use synthetic dusts with particle size distributions very different from typical urban atmospheric aerosols. Consequently, the results obtained in this way differ from the air filter performance measured in real HVAC installations and the designers cannot use them to predict quantitatively the in-situ air filter performance. Standards writers are aware of the problem and this limitation is stated explicitly in EN ISO 16890 and ANSI/ASHRAE 52.2 standards. However, there is a need to perform the test in a short time. Moreover, the filtration industry consolidated this approach during the past decades and a lot of data is available with those dusts. To improve the prediction of the size-resolved efficiency and the loading kinetics of HVAC filters we need improved test methodologies. ASHRAE is promoting the development of a new method to age air filters as part of ASHRAE Guideline Project 35 “Method for Determining the Energy Consumption Caused by Air- Cleaning and Filtration Devices”. Research teams in USA and Italy are attempting to improve the loading procedure to age HVAC filters using aerosols with more realistic particle size distributions. If successful, the new ageing procedure could provide a reliable prediction tool for evaluating the airflow resistance during the filter service life. In this way, we could optimize the performance of air cleaning equipment in realistic conditions. In this paper, we summarize current laboratory ageing procedures. We compare the airflow resistance trend in an HVAC system monitored for more than one year, with the results from an ISO 16890 laboratory test on the same air filter. We discuss the difference between the mass increase values causing the same airflow resistance increase. To reduce the difference between actual data and laboratory simulation results, we present an emerging technique with a preliminary evaluation of a new thermal flame generator for challenging HVAC filters with sub-micron potassium chloride aerosol at high mass concentrations. The thermal aerosol generator is able to reproduce the sub-micron urban atmospheric aerosol mass size distribution and it is a promising technique to solve some of the problems stated above

Histopathological changes in albino mouse testis induced by the administration of Tityus n. sp. venom

  La cosiddetta Raccolta Merlani è composta da oltre 75.000 pezzi fra bandi, leggi e decreti pubblicati a Bologna dal 1560 al 1869. Si tratta di un insieme omogeneo proveniente dalla Stamperia Camerale di Bologna, la tipografia che aveva la privativa per la stampa delle pubblicazioni ufficiali che rendevano note ai bolognesi i provvedimenti adottati dal governo cittadino e dal rappresentante locale del pontefice, il cardinale legato. Fino a questo momento sono stati digitalizzati e indicizzat..