Are there medium to short-term multifaceted effects of the airborne pollutant PM2.5 determining the emergence of SARS-CoV-2 variants?

The COVID-19 pandemic has been characterised by successiveoutbreaks effecting large swathes of the world's populations. These waves of infection have been mainly driven by a number of more transmissiblevariants which appear to evade the populations' immunity gained from previous outbreaks. There appears to be a link between COVID-19 and a ubiquitous airborne pollutant calledparticulate matter, PM2.5. Particulate matter through a number of mechanisms, including its anthropogenic effect, appears to be associated with the incidence and the mortality related to the COVID-19 pandemic. This paper poses a number of hypotheses on the short to medium-term mechanisms whereby PM2.5 may be party to the natural selection of SARS-CoV-2 virus, with the consequent emergence of variants.

Could changes in the airborne pollutant particulate matter acting as a viral vector have exerted selective pressure to cause COVID-19 evolution?

Air pollution with particulate matter has been implicated in the incidence and the mortality due to COVID-19 infection. The levels of particulate matter have been shown to have decreased after regional and national lockdowns in a number of countries. COVID-19 possesses an elevated reproduction number (R0) due to its high transmission rate. COVID-19 genes have been found adherent to particulate matter which has been suggested as a vector for this virus' transmission. Following lockdown in China, the original viral Clade D steadily decreased mirroring the decline in particulate matter. Two months after the COVID-19 index case was reported in Wuhan early December 2019, a persistent mutation was noted at the D614 gene position of the viral spike protein establishing the Clade G variant. Clade G started to appear early in February and steadily attained predominance after lockdown in late February. It may be postulated that the changes in the source of airborne particulate matter, possibly derived from tobacco smoking (66% of Chinese males are smokers), may have contributed to the appearance of Clade G. Once the pandemic spread beyond China, in all countries affected except for Iceland, a consistent pattern arose whereby the initial viral Clade D outbreak was rapidly displaced by Clade G. It is hypothesized that changes in the source of COVID-19's vector in the form of particulate matter may have contributed to natural selection favouring Clade G. The "open orientation" of Clade G spike protein's three peptides as opposed to the "closed orientation" of the Clade D may have allowed easier adherence of the viral mutant to cells and as a corollary also to particulate matter. There may also have been differences between both viral Clades in the spike protein's hydrophobic properties. Experimental research on the hypothesis that particulate matter may potentially act as a COVID-19 vector needs to be undertaken. Besides the potential vector effect, the deleterious effects of particulate matter on respiratory immunity and cardiovascular health are well known and consequently airborne pollution in all its forms should be addressed on a global scale.

Principal Component Analysis of Dynamic Thermography Data from Pregnant and Non-Pregnant Women.

In this work we propose a novel approach for the analysis ofdynamic thermography data based on the application of principal component analysis to thermal video data. The proposed approach is applied to thermal video recordings of the abdominal region of pregnant and non-pregnant female participants, and reveals consistent temperature trends across participants that to date have not been reported. Both for the pregnant and non-pregnant participants, the first principal component was found to describe approximately 80% of the total variance, and when combined, the first three principal components explained more than 90% of the total variance. The presence of consistent temporal components across participants is indicative of common passive as well as active underlying mechanisms thatgive rise to the observed temperature patterns. The outcome of this investigation supports further development and application of the proposedmethod in obstetrics and other medical fields.

Registration of Dynamic Thermography Data of the Abdomen of Pregnant and Non-Pregnant Women.

To date the use of thermography in the context of obstetrics has been primarily limited to the acquisition and analysis of static thermal images. In contrast, dynamic thermography involves the acquisition of a sequence of thermal images, taking into account temporal variations that would otherise be overlooked. However, dynamic recordings of regions of interest in human participants are likely to be affected by unavoidable participant movement due to breathing and other involuntary movements. In this work, a triangulation-based video registration technique using local affine transformations is proposed to register the abdominal region in dynamic thermal sequences. The proposed method is tested on one hour recordings of thermal data obtained from 10 pregnant and 10 non-pregnant female participants. The results obtained show that the proposed approach can compensate for movements and significantly improve region alignment throughout the thermal image sequence, thereby facilitating subsequent analysis of spatiotemporal temperature data in the considered image sequence.

Synergistic effect on the treatment of menorrhagia by endometrial biopsy followed by contemporaneous insertion of the levonorgestrel intrauterine system.

OBJECTIVE: To evaluate the efficacy of endometrial biopsy followed by intrauterine system-releasing levonorgestrel (LNG-IUS) insertion in the treatment of women with menorrhagia. METHOD: This was a retrospective, non-comparative study. Ninety-two patients who had menorrhagia due to non-malignant causes were sequentially recruited into the study over a 3-year period (age range 29-51 years). Patients with a uterine size more than 12 weeks were not included. A LNG-releasing intrauterine system was inserted during the mid-cycle immediately after an endometrial biopsy was taken. One year after the closure of the study period, the women recruited were then contacted by telephone or by direct questioning at the outpatient clinic as to the outcome of the above treatment. RESULTS: The most common (15%) complaint regarding bleeding patterns at 3-6 months after insertion was spotting and intermenstrual bleeding. Following the introduction of the LNG-IUS, six women required a hysterectomy for various reasons. The remaining 86 women (93.5%) continued the use of LNG-IUS. CONCLUSION: LNG-IUS following an endometrial biopsy is an effective treatment for menorrhagia due to benign causes and could be an alternative to other forms of medical and surgical treatments.

Iliac vessel wall thickness in menstrual and hormone treated and untreated postmenopausal women.

OBJECTIVE: To assess iliac vessel wall thickness in different groups of women. METHOD: Three groups of women were menopausal and were classified by hormone replacement therapy (HRT) (n = 32), atherosclerotic risk factors (n = 14) and an untreated group of postmenopausal women (n = 29), two groups of menstrual women, above 35 years (N = 35) and below 35 years (n = 16). In these groups of women, a 3.5 MHz ultrasound was used to assess the combined vessel wall thickness of the right iliac artery inner wall and vein outer wall. RESULTS: The iliac vessel wall thickness was found significantly high in the menopausal group of women possessing high risk factors for atherosclerosis (4.3 ± 0.08 mm) and the untreated menopausal group of women (3.9 ± 0.08 mm) compared to the other three groups (p < 0.0001) (Mann-Whitney U test). The vessel wall thickness of the HRT group was 2.96 ± 0.09 mm, the older menstrual group 2.61 ± 0.07 mm, and 2.0 ± 0.06 mm in the young menstrual group. The HRT group had a significantly thicker iliac vessel wall compared to the young menstrual group (p < 0.001). CONCLUSION: These results confirm the significant impact of high risk factors, such as smoking, hyperlipidaemia and diabetes, on the vessel wall thickness due to accelerated atherosclerosis. This study also suggests that the oestrogenaemic state of a woman may affect the health of the vessel wall.

Intervertebral disc height correlates with vertebral body T-scores in premenopausal and postmenopausal women.

OBJECTIVE: To assess the correlation between vertebral body T-score and intervertebral disc height in premenopausal and postmenopausal women. METHODS: A total of 203 women were recruited from a large bone densitometer directory. The disc heights measured were those between the 12th thoracic and third lumbar vertebra. The discs were assigned the symbols D, whereby D1 applies for the disc between the 12th thoracic and first lumbar vertebra. The disc height of the group of women (n=38) with osteoporotic vertebral fractures was compared with the disc heights of hormone-treated women (n=47), untreated postmenopausal women (n=77) and another group of premenopausal women (n=41). Bone density measurements were taken by a Norland Bone Densitometer (DEXA 586). RESULTS: The lowest disc heights were found in the fracture group. The total disc height in the fracture group was 1.42+/-0.25 cm, significantly lower (P<0.0001) than the untreated group (1.82+/-0.3 cm), which in turn was significantly (P<0.0001) lower than the hormone-treated group (2.2+/-0.26 cm) and the premenopausal group (2.11+/-0.21 cm). The lowest T-scores were also noted in the vertebral fracture group (T-score=-3.1+/-0.3) (P<0.0001). The highest T-score recorded for the premenopausal group was -0.38+/-45, higher than that of the untreated menopausal -1.4+/-0.32 and hormone treated women -0.65+/-0.3, all three significantly higher than the fracture group (P<0.0001). The lowest T-scores were also noted in the vertebral fracture group (T-score=-3.1+/-0.3) (P<0.0001). The highest T-score recorded for the premenopausal group was -0.38+/-45, higher than that of the untreated menopausal -1.4+/-0.32 and hormone treated women -0.65+/-0.3, all three significantly higher than the fracture group (P<0.0001). Bone density across all groups revealed a correlation with disc height (R=0.29) (P<0.05). The group with vertebral osteoporotic fractures was the only group to show a negative correlation (-0.21) between disc height and vertebral bone density. Conversely, a significant correlation (R=0.47) (P<0.001) between the T-score and the total lumbar intervertebral disc height was noted in the premenopausal group of women. The menopausal group of untreated women also showed a significant correlation between the T-score and disc height (R=0.25 P<0.05); however, an insignificant positive correlation was found in the hormone-treated group. CONCLUSION: The fracture group was noted to have the lowest intervertebral disc height and lowest T-scores compared with the other three groups. The hormone-treated and the premenopausal women had the highest disc heights and T-scores recorded. Positive correlations between T-score and disc height were noted for all the groups except for the fracture group. These results suggest a coupling between the vertebral body and intervertebral disc, which if disrupted may lead to increased risk for fracture. The combination of both T-score and disc height may improve the screening sensitivity for vertebral body fracture risk.

Intervertebral disc height in treated and untreated overweight post-menopausal women.

BACKGROUND: The effect of the menopause and HRT on the intervertebral discs has not been investigated. METHODS: One hundred women were recruited, comprising of 44 post-menopausal women on HRT, 33 untreated post-menopausal women and 23 pre-menopausal women. The height of the intervertebral discs between the 12th thoracic vertebra and the 3rd lumbar vertebra was measured by utilizing the bone densitometer height cursors. RESULTS: The untreated menopausal group of women had the lowest total disc height (D1-D3: 1.95 0.31 cm). This was significantly lower than the pre-menopausal group D1-D3: 2.16 0.24 cm) and the hormone-treated group (2.2 0.26 cm) (P > 0.02). The 2nd intervertebral disc consistently maintained a significant difference between the untreated menopausal group (D2: 0.63 0.13) and the other two groups (pre-menopausal group (D2: 0.72 0.09 cm) and treated menopausal group (D2: 0.73 0.12 cm) (P > 0.02). CONCLUSIONS: Estrogen-replete women appear to maintain higher intervertebral discs compared to untreated post-menopausal women. The estrogenic milieu may be relevant because of the significant impact it has on the hydrophilic glycosaminoglycans, the water content, collagen and elastin of the intervertebral discs. The maintenance of adequate disc height may allow the intervertebral discs to retain their discoid shape and viscoelastic function, containing vertical forces which may threaten spinal architecture leading to vertebral body compression fractures.