Detection of microplastics in human saphenous vein tissue using µFTIR: A pilot study.

Microplastics (MPs) are ubiquitous in the environment, in the human food chain, and have been recently detected in blood and lung tissues. To undertake a pilot analysis of MP contamination in human vein tissue samples with respect to their presence (if any), levels, and characteristics of any particles identified. This study analysed digested human saphenous vein tissue samples (n = 5) using µFTIR spectroscopy (size limitation of 5 µm) to detect and characterise any MPs present. In total, 20 MP particles consisting of five MP polymer types were identified within 4 of the 5 vein tissue samples with an unadjusted average of 29.28 ± 34.88 MP/g of tissue (expressed as 14.99 ± 17.18 MP/g after background subtraction adjustments). Of the MPs detected in vein samples, five polymer types were identified, of irregular shape (90%), with alkyd resin (45%), poly (vinyl propionate/acetate, PVAc (20%) and nylon-ethylene-vinyl acetate, nylon-EVA, tie layer (20%) the most abundant. While the MP levels within tissue samples were not significantly different than those identified within procedural blanks (which represent airborne contamination at time of sampling), they were comprised of different plastic polymer types. The blanks comprised n = 13 MP particles of four MP polymer types with the most abundant being polytetrafluoroethylene (PTFE), then polypropylene (PP), polyethylene terephthalate (PET) and polyfumaronitrile:styrene (FNS), with a mean ± SD of 10.4 ± 9.21, p = 0.293. This study reports the highest level of contamination control and reports unadjusted values alongside different contamination adjustment techniques. This is the first evidence of MP contamination of human vascular tissues. These results support the phenomenon of transport of MPs within human tissues, specifically blood vessels, and this characterisation of types and levels can now inform realistic conditions for laboratory exposure experiments, with the aim of determining vascular health impacts.

Detection of microplastics in human lung tissue using µFTIR spectroscopy.

Airborne microplastics (MPs) have been sampled globally, and their concentration is known to increase in areas of high human population and activity, especially indoors. Respiratory symptoms and disease following exposure to occupational levels of MPs within industry settings have also been reported. It remains to be seen whether MPs from the environment can be inhaled, deposited and accumulated within the human lungs. This study analysed digested human lung tissue samples (n = 13) using µFTIR spectroscopy (size limitation of 3 µm) to detect and characterise any MPs present. In total, 39 MPs were identified within 11 of the 13 lung tissue samples with an average of 1.42 ± 1.50 MP/g of tissue (expressed as 0.69 ± 0.84 MP/g after background subtraction adjustments). The MP levels within tissue samples were significantly higher than those identified within combined procedural/laboratory blanks (n = 9 MPs, with a mean ± SD of 0.53 ± 1.07, p = 0.001). Of the MPs detected, 12 polymer types were identified with polypropylene, PP (23%), polyethylene terephthalate, PET (18%) and resin (15%) the most abundant. MPs (unadjusted) were identified within all regions of the lung categorised as upper (0.80 ± 0.96 MP/g), middle/lingular (0.41 ± 0.37 MP/g), and with significantly higher levels detected in the lower (3.12 ± 1.30 MP/g) region compared with the upper (p = 0.026) and mid (p = 0.038) lung regions. After subtracting blanks, these levels became 0.23 ± 0.28, 0.33 ± 0.37 and 1.65 ± 0.88 MP/g respectively. The study demonstrates the highest level of contamination control and reports unadjusted values alongside different contamination adjustment techniques. These results support inhalation as a route of exposure for environmental MPs, and this characterisation of types and levels can now inform realistic conditions for laboratory exposure experiments, with the aim of determining health impacts.

Differential effects of atrial and brain natriuretic peptides on human pulmonary artery: An in vitro study.

BACKGROUND: The prevalence of cardiovascular diseases, especially heart failure, continues to rise worldwide. In heart failure, increasing levels of circulating atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are associated with a worsening of heart failure and a poor prognosis. AIM: To test whether a high concentration of BNP would inhibit relaxation to ANP. METHODS: Pulmonary arteries were dissected from disease-free areas of lung resection, as well as pulmonary artery rings of internal diameter 2.5-3.5 mm and 2 mm long, were prepared. Pulmonary artery rings were mounted in a multiwire myograph, and a basal tension of 1.61gf was applied. After equilibration for 60 min, rings were pre-constricted with 11.21 µmol/L PGF2α (EC80), and concentration response curves were constructed to vasodilators by cumulative addition to the myograph chambers. RESULTS: Although both ANP and BNP were found to vasodilate the pulmonary vessels, ANP is more potent than BNP. pEC50 of ANP and BNP were 8.96 ± 0.21 and 7.54 ± 0.18, respectively, and the maximum efficacy (Emax) for ANP and BNP was -2.03 gf and -0.24 gf, respectively. After addition of BNP, the Emax of ANP reduced from -0.96gf to -0.675gf (P = 0.28). CONCLUSION: BNP could be acting as a partial agonist in small human pulmonary arteries, and inhibits relaxation to ANP. Elevated levels of circulating BNP could be responsible for the worsening of decompensated heart failure. This finding could also explain the disappointing results seen in clinical trials of ANP and BNP analogues for the treatment of heart failure.

Characterization of optimal resting tension in human pulmonary arteries.

AIM: To determine the optimum resting tension (ORT) for in vitro human pulmonary artery (PA) ring preparations. METHODS: Pulmonary arteries were dissected from disease free sections of the resected lung in the operating theatre and tissue samples were directly sent to the laboratory in Krebs-Henseleit solution (Krebs). The pulmonary arteries were then cut into 2 mm long rings. PA rings were mounted in 25 mL organ baths or 8 mL myograph chambers containing Krebs compound (37 °C, bubbled with 21% O2: 5% CO2) to measure changes in isometric tension. The resting tension was set at 1-gram force (gf) with vessels being left static to equilibrate for duration of one hour. Baseline contractile reactions to 40 mmol/L KCl were obtained from a resting tension of 1 gf. Contractile reactions to 40 mmol/L KCl were then obtained from stepwise increases in resting tension (1.2, 1.4, 1.6, 1.8 and 2.0 gf). RESULTS: Twenty PA rings of internal diameter between 2-4 mm were prepared from 4 patients. In human PA rings incrementing the tension during rest stance by 0.6 gf, up to 1.6 gf significantly augmented the 40 mmol/L KCl stimulated tension. Further enhancement of active tension by 0.4 gf, up to 2.0 gf mitigate the 40 mmol/L KCl stimulated reaction. Both Myograph and the organ bath demonstrated identical conclusions, supporting that the radial optimal resting tension for human PA ring was 1.61 g. CONCLUSION: The radial optimal resting tension in our experiment is 1.61 gf (15.78 mN) for human PA rings.

Antegrade rapid prime displacement in elective coronary artery surgery is associated with lower perioperative blood transfusions and a shorter hospital stay.

OBJECTIVES: Haemodilution during cardiopulmonary bypass is associated with increased perioperative blood transfusions and is thought to reduce intraoperative oxygen delivery to the brain. We sought to evaluate our method of rapid antegrade prime displacement in the context of the perioperative blood transfusion rate, intraoperative cerebral saturations and postoperative hospital stay. METHODS: Retrospective analysis of 160 propensity-matched patients undergoing elective coronary artery bypass grafting was performed comparing different perfusion strategies on perioperative blood transfusion and length of postoperative stay. Eighty patients who had rapid antegrade prime displacement and vacuum-assisted venous drainage (RAD-VAD) were compared with 80 patients who had conventional cardiopulmonary bypass with gravity drainage (CB). RAD-VAD involved displacing all or most of the prime in the circuit with the patient's own blood prior to the initiation of cardiopulmonary bypass within a 15-20 s window. Within each group, 10 patients had intraoperative cerebral saturation measurements. RESULTS: There were no differences in the baseline characteristics between the groups. Both groups had a significant fall (P < 0.05) in haematocrit during cardiopulmonary bypass from preoperative values, however, the fall in haematocrit was significantly less in the RAD-VAD group (P < 0.05). There was significantly (P < 0.05) less intraoperative and postoperative homologous blood transfusions in the RAD-VAD group (47.892 ml ± 8.14 and 76.58 ml ± 21.58) compared with the CB group (229.06 ml ± 105.03 and 199.91 ml ± 47.13). There was a significant fall in cerebral saturations within both groups (P < 0.05) but it was not significant between the groups. The postoperative stay was significantly (P < 0.05) shorter in the RAD-VAD group compared with the conventional group (7.74 days ± 0.51 vs 10.13 days ± 0.95). CONCLUSIONS: RAD-VAD is associated with a significantly lower blood transfusion rate perioperatively and shorter hospital stays compared with CB.

Characterization of the vasodilatory action of testosterone in the human pulmonary circulation.

AIM: To assess for the first time the vasodilatory effect of testosterone in the human pulmonary circulation utilizing both isolated human pulmonary arteries and isolated perfused human lungs. In addition, a secondary aim was to determine whether there was any difference in the response to testosterone dependent upon gender. METHODS: Isolated human pulmonary arteries were studied by wire myography. Vessels were preconstricted with U46619 (1 nM-1 microM) prior to exposing them to either testosterone (1 nM-100 microM) or ethanol vehicle (<0.1%). Isolated lungs were studied in a ventilated and perfused model. They were exposed to KCl (100 mM), prior to the addition of either testosterone (1 nM-100 microM) or ethanol vehicle (<0.1%). RESULTS: Testosterone caused significant vasodilatation in all preparations, but a greater response to testosterone was observed in the isolated perfused lungs, 24.9 +/- 2.2% at the 100 microM dose of testosterone in the isolated pulmonary arteries compared to 100 +/- 13.6% at the 100 microM dose in the isolated perfused lungs. No significant differences in the response to testosterone were observed between sexes. CONCLUSION: Testosterone is an efficacious vasodilator in the human pulmonary vasculature and this is not modulated by patient sex. This vasodilator action suggests that testosterone therapy may be beneficial to male patients with pulmonary arterial hypertension.