Mind the gap between non-activated (non-aggressive) and activated (aggressive) indoor fungal testing: impact of pre-sampling environmental settings on indoor air readings.

Indoor fungal testing has been within the researchers' scope of interest for more than a century. Various sampling and analysis techniques have been developed over the years, but no testing protocol has been yet standardised and widely accepted by the research and practitioner communities. The diversity in fungal taxa within buildings with varied biological properties and implications on the health and wellbeing of the occupants and the building fabric complicates the decision-making process for selecting an appropriate testing protocol. This study aims to present a critical review of non-activated and activated approaches to indoor testing, with an emphasis on the preparation of the indoor environment prior to sampling. The study demonstrates the differences in the outcomes of non-activated and activated testing through a set of laboratory experiments in idealised conditions and a case study. The findings suggest that larger particles are particularly sensitive to the sampling height and activation, and that non-activated protocols, despite dominating the current literature, can significantly underestimate the fungal biomass and species richness. Therefore, this paper calls for better-defined and activated protocols that can enhance robustness and reproducibility across the research domain focused on indoor fungal testing.

Normal background levels of air and surface mould reserve in English residential building stock: a preliminary study towards benchmarks based on NAHA measurements.

This paper reports results obtained from a surface (both visually clean and dirty/dusty surfaces) and active (aggressive or activated) air testing scheme on 140 residential rooms in England, without visible water damage or mould growth, along with a few rooms with visible mould growth/water damage tested for comparison purposes. The aim was to establish normal background levels of mould in non-water-damaged interiors to benchmark a 'normal' indoor environment, and in turn when there is a need for further investigation, and, possibly, remediation. Air and surface mould was quantified based on the activity of ß-N-acetylhexosaminidase (EC 3.2.1.52; NAHA). The obtained readings showed a log-normal distribution. Ninety-eight percent of the samples obtained from visually clean surfaces were equal to or less than 25 relative fluorescence units (RFU), which is suggested to be the higher bound for the range which can be used as a success criterion for surface cleaning/remediation. Of samples obtained from visually dirty/dusty surfaces, around 98% were below 450 RFU, which is suggested to define the lower-bound for abnormally high levels of mould, rare even on dirty/dusty surfaces. Similarly, around 98% of the air samples were found to have 1700 RFU or below. Values above 1700 RFU are therefore deemed unlikely in a non-problem indoor environment and can be indicative of a possible problem inducing mould growth. The samples with values below 1700 were further divided into three proposed sub-categories. Finally, the obtained RFU values and the suggested benchmarks were compared to those obtained from 17 non-residential indoor environments tested previously in Copenhagen, and the benchmarks that are currently used in Danish national standards, and they were both found to be highly congruent, suggesting that local climate regimes and room functions might not be as influential on indoor mould levels as commonly thought, or that the nuances between England and Denmark in terms of these factors are not strong enough to lead to sizable changes in the typical indoor mould levels in these countries' building stocks.

Surface and passive/active air mould sampling: A testing exercise in a North London housing estate.

Despite indoor mould being one of the most common problems in residential properties in the UK, there are not any widely accepted methodologies for its measurement. This paper focusses on this problem of measurement and reports on the findings from a rigorous testing scheme carried out to quantify air and surface mould concentrations and particle counts within 71 rooms from 64 properties in North London, some with and some without visible mould. The aim was to investigate the potential of passive and active air sampling strategies (sampling from still and actively mixed air, respectively) to explain visible mould, and understand how home/room characteristics correlate with the obtained readings. Airborne mould levels were quantified using an Andersen sampler (passively and actively), as well as by a chemical method based on the quantification of the N-acetylhexosaminidase (NAHA) activity (actively), which was also used to quantify surface mould. The mould levels were then correlated against physical characteristics of the tested homes/rooms, collected by means of survey sheets developed as part of this study. The findings did not reveal any independent variable governing all or most of the response variables, but a complex analysis suggested that whether it is a house or a flat could depict mould levels in the air and on the surfaces. It was also shown that a robust testing protocol should combine air and surface based methods, and an active air sampling strategy leads to a more accurate appraisal of airborne mould levels. Finally, the results showed that while there is some correlation between visible mould (and other moisture induced problems such as condensation) and measured air mould concentrations, lack of visible mould within a room does not necessarily mean low air mould concentrations, and thus one should not rely solely on visual inspection.

Indoor mould testing in a historic building: Blickling Hall.

Indoor mould growth is a growing concern for all stakeholders of built environment, including residents, builders, insurance and building remediation industry as well as custodians of heritage buildings. The National Trust has reported this problem in a number of buildings under their ownership, and developed solutions and fine-tuned their maintenance programme so as to minimise indoor and surface mould growth risk. This paper reports findings from an extensive mould-testing scheme in Blickling Hall, a National Trust property in Norfolk, England, for an appraisal of airborne and surface mould levels within a total of eight rooms, including the famous Long Gallery. The testing protocol used combines active (aggressive) air sampling and surface sampling, analysis of the ß-N-acetylhexosaminidase (NAHA) activity to quantify mould levels and particle counting. The results show that the airborne mould levels are quite low in all spaces, due to satisfactory maintenance of indoor hygrothermal conditions by conservation heating. On the other hand, while the National Trust's developed solutions and maintenance programme have proved effective to avoid surface mould growth in those locations that historically suffered from microbial activity (such as behind book presses, picture frames and tapestries), the results show that the surface cleaning around windows should be improved to tackle surface water due to condensation, which is considered to be the main driver behind high surface NAHA activity obtained in these areas.

The effectiveness of intracytoplasmic sperm injection combined with piezoelectric stimulation in infertile couples with total fertilization failure.

OBJECTIVE: To assess the effectiveness of intracytoplasmic sperm injection (ICSI) combined with piezoelectric stimulation in infertile couples with a history of total fertilization failure (TFF). DESIGN: Prospective controlled trial. SETTING: Clinical IVF laboratory. PATIENT(S): Seventy-one couples undergoing ICSI on sibling oocytes having at least one previous ICSI attempt with TFF. INTERVENTION(S): ICSI or ICSI with piezoelectric activation. MAIN OUTCOME MEASURE(S): Fertilization rate. RESULT(S): The patients were allocated to two groups: group I included 21 patients with only one previous TFF and group II included 50 patients with more than one previous TFF. Collectively, a total of 823 metaphase II (MII) oocytes were retrieved in 78 oocyte retrievals. In Group I, combined ICSI with piezoelectric stimulation was applied to 123/211 (58.2%) of MII oocytes (group IA), whereas standard ICSI procedure was applied to 88/211 (41.8%) of MII oocytes (group IB). The fertilization rate was 62% and 12% in group IA and group IB respectively. In group II, piezoelectric activation was applied in all 612 MII oocytes, of which 296 (48.3%) were fertilized. The rates for implantation and pregnancy/embryo transfer were obtained as 30.6% and 44.1%, respectively. CONCLUSION(S): Piezoelectric activation seems to improve IVF outcome in patients with previous TFF history.

Successful application of preimplantation genetic diagnosis for Leigh syndrome.

OBJECTIVE: To perform preimplantation genetic diagnosis (PGD) for a SURF1 gene mutation of the Leigh syndrome to transfer unaffected or carrier embryo/embryos. DESIGN: Case report. SETTING: Clinical IVF laboratory. PATIENT(S): A couple carrying an nt769 G/A mutation that is associated with Leigh syndrome. INTERVENTION(S): Oocytes were fertilized by means of intracytoplasmic sperm injection. The resulting embryos were biopsied 3 days after fertilization. One blastomere was taken and whole-genome amplification was performed. Amplification of the mutation site was achieved by polymerase chain reaction (PCR) and restriction digestion was completed. Gel Imager was used to measure the digests of normal and mutant load. MAIN OUTCOME MEASURE(S): Embryo testing by means of PGD-PCR and pregnancy. Successful preimplantation genetic diagnosis for a SURF1 gene mutation and transfer of healthy or carrier embryos. RESULT(S): Successful singleton pregnancy resulting in the delivery of healthy baby girl. CONCLUSION(S): We report the first case of successful PGD for Leigh syndrome resulting in delivery of a healthy newborn.