Advances in Enzyme Induced Carbonate Precipitation and Application to Soil Improvement: A Review

Climate change and global warming have prompted a notable shift towards sustainable geotechnics and construction materials within the geotechnical engineer’s community. Earthen construction materials, in particular, are considered sustainable due to their inherent characteristics of having low embodied and operational energies, fire resistance, and ease of recyclability. Despite these attributes, they have not been part of the mainstream construction due to their susceptibility to water-induced deterioration. Conventional soil improvement techniques are generally expensive, energy-intensive, and environmentally harmful. Recently, biostabilization has emerged as a sustainable alternative that can overcome some of the limitations of existing soil improvement methods. Enzyme-induced carbonate precipitation (EICP) is a particularly promising technique due to its ease of application and compatibility with different soil types. EICP exploits the urease enzyme as a catalyst to promote the hydrolysis of urea inside the pore water, which, in the presence of calcium ions, results in the precipitation of calcium carbonate. The purpose of this paper is to provide a state-of-the-art review of EICP stabilization, highlighting the potential application of this technique to field problems and identifying current research gaps. The paper discusses recent progress, focusing on the most important factors that govern the efficiency of the chemical reactions and the precipitation of a spatially homogenous carbonate phase. The paper also discusses other aspects of EICP stabilization, including the degree of ground improvement, the prediction of the pore structure of the treated soil by numerical simulations, and the remediation of potentially toxic EICP by-products.

Clinical outcomes following use of sirolimus coated balloon in side-branches during provisional stent technique in true bifurcations

Introduction

Provisional stenting is the preferred strategy even in true bifurcations, however, to minimise the need for repeat revascularization of side-branches, the use of drug coated balloons has been suggested. Most of the data available in the literature are on Paclitaxel coated balloons, a drug which is almost obsolete in stents due to its cytotoxic properties. There is limited data on Limus coated balloons (SCB), a drug which is the default for all the currently available drug eluting stents. In this study, we explore the clinical outcomes following use of SCB in side-branches during provisional stent technique in true bifurcations.

Methods and results

We evaluated all de novo lesions treated with DCB for true bifurcations between March 2018 and October 2020 at our centre. The results are reported as cardiac death, target vessel myocardial infarction (TVMI), target lesion revascularisation (TLR) and MACE (combination of cardiac death, target vessel MI and TLR).

During the study period 110 patients with de novo lesions were treated with SCB for bifurcation lesions. Of them; 66 were in true bifurcations. The mean age of patients were 66.3±10.7 years, 75% (n=50) were male, 40 (61%) were in the setting of acute coronary syndrome, 52% (n=34) had diabetes and 32% (n=21) had CKD. Pre-dilatation was performed in all cases and none of them needed bailout stenting. Small vessels (<3.0 mm) accounted for 72% (n=48) of cases. Non-compliant balloons and scoring balloons to prepare the lesion was used in 51% (n=34) and 13% (n=9) of cases respectively. The mean diameter and length of SCBs were 2.6±0.4 mm and 23.2±7.3 mm respectively.

During a median follow-up of 729 days (2-years); there were no cardiac deaths, TVMI occurred in one case (2%), TLR in 3% (n=2) and the overall MACE rate was 3% (n=2). There were no documented cases of acute vessel closure

Conclusion

The results from long term follow-up with this relatively new technology of DCB in treatment of side-branch in true bifurcation is encouraging. We have demonstrated low rates of hard endpoints, TLR and MACE rates despite complex group of patients (61% ACS, 52% diabetics and 32% CKD). These results are encouraging, but going forward, we need more data from larger patient trials. In the meanwhile our data should instil confidence to adopt this technology in clinical practice.

Funding Acknowledgement

Type of funding sources: None.

Use of sirolimus-coated balloon in de novo small vessel coronary lesions; Long-term follow-up from a single centre registry

Background

Drug coated balloons (DCBs) in Europe are mainly used in restenotic lesions as endorsed by the European Society of Cardiology, with a class IA recommendation. However, some of the recent data suggest, it can also be considered in a subset of denovo lesions, especially in small vessels. Most DCBs used, are coated with Paclitaxcel. There is no data on the efficacy of Sirolimus in DCBs, the drug of choice in drug eluting stents. In this study, we report outcomes from the use of a Sirolimus coated balloon (SCB) in de novo small-vessel coronary lesions, from a single high yield centre.

Methods

A retrospective analysis was conducted on all patients treated with an SCB between March 2018 and October 2020. Follow-up was achieved with clinic visits, telephone calls and admission records. The outcomes measured include cardiac death, target-vessel myocardial-infarction (TVMI), target lesion revascularisation (TLR) and MACE (combination of cardiac death, target-vessel MI and TLR).

Results

During the study period, 279-patients (with 332-lesions) with de novo lesions were treated with an SCB. The mean age of patients was 65±12 years, 219 (79%) were male, 36% (n=100) had diabetes, 16% (n=45) had chronic kidney disease and 61% were in the setting of acute coronary syndrome (n=169). Predilatation was performed in 96% (320-lesions). Bailout stenting (with DES) was required in 5% of lesions (n=18) of which 16 were due to dissections and 2 were due to recoil >30% following DCB use. The mean diameter and length of DCBs were 2.35 mm and 26 mm respectively.

During a median follow-up of 584-days (19-months) cardiac death was reported in 8 patients (3%). Target vessel MI was in 3% (n=9), TLR per lesion was 8% (n=26) and the MACE rate was 11% (n=31). There were no documented cases of acute vessel closure.

Conclusion

The long-term outcome from the first ever study on sirolimus eluting balloons in de novo small vessel lesions appears promising with low rates of hard endpoints, and acceptable repeat rates of TLR despite a complex group of patients (50% ACS, 36% diabetics and 19% CKD) and lesion subsets (small vessel and diffuse disease). Implanting stents in these subsets renders them vulnerable to restenosis, making treatment challenging and resulting in high rates of recurrence.

Funding Acknowledgement

Type of funding sources: None.

Long term clinical outcomes from use of Sirolimus coated balloon in coronary intervention; data from a real-world population

Background

The use of drug coated balloons (DCBs) in coronary intervention is escalating. There are two drugs of choice for coating either DCBs or drug eluting stents: Paclitaxel or Sirolimus. Most available DCBs are coated with Paclitaxcel, due to pre-existing, extensive data that support good clinical outcomes. With drug eluting stents both the literature and hence clinical practice favour Sirolimus over Paclitaxcel. This is due the cytostatic properties and wide therapeutic window of Sirolimus. However, there is very limited data on Sirolimus coated balloons (SCBs). We report a long-term follow-up with this relatively new technology from our centre.

Methods

A retrospective analysis was conducted on all patients treated with an SCB between March 2018 and October 2020. Follow-up was achieved with clinic visits, telephone calls and admission records. The outcomes measured include cardiac death, target-vessel myocardial-infarction (TVMI), target lesion revascularisation (TLR) and MACE (combination of cardiac death, target-vessel MI and TLR).

Results

533 patients (690-lesions) with a mean age of 65.4 (range; 37–90) were treated with an SCB. 79% (n=419) were male, 314 (59%) were in the setting of acute coronary syndrome, 40% (n=211) had diabetes and 60% (n=414) had DCB in de-novo lesions. Small vessels accounted for 59% of cases (n=406). Pre-dilatation was performed in 97% (n=670) of cases. Bailout stenting (with a drug eluting stent) was required in 6.5% lesions (n=45), of which 11 were due to dissections and 34 were due to >50% recoil following DCB use. The mean diameter and length of DCBs were 2.8 mm and 26.3 mm respectively.

During a median follow-up of 572 days (IQR: 381 - 868); cardiac death occurred in 15 patients (3%). Target vessel MI was in 4%; n=21, TLR per lesion and per patient were 10% (n=72 and n=55 respectively). The overall MACE rate was 12%. There were no documented cases of acute vessel closure.

Conclusions

The results from long term follow-up with this relatively new technology DCB are encouraging with low rates of hard endpoints and acceptable rates of TLR and MACE despite complex group of patients (59% ACS and 40% diabetics) and lesion subsets (40% restenotic lesions and 59% small vessels). However, in order to further inform clinical practice, more longer-term data on SCBs compared with Paclitaxel coated balloons is needed.

Funding Acknowledgement

Type of funding sources: None.

Use of sirolimus-coated balloon in de novo lesions; Mid-term follow-up from a single-centre registry

Introduction

Use of drug coated balloons (DCBs) in coronary intervention is escalating and the guidelines recommend its use in restenotic lesions. However, recent data suggest it can also be considered in a subset of denovo lesions especially; small vessels, ostium of an important side-branch and in patients unable to tolerate dual antiplatelet therapy for a prolonged period. Most DCBs used elute Paclitaxcel, but there is no data on Sirolimus eluting DCB, which is the drug of choice in currently available drug eluting stents. In this study, we report outcomes from the use of a Sirolimus coated balloon (SCB) in de novo coronary lesions.

Methods

We retrospectively analysed all patients treated with an SCB between April and December 2018. Results are reported as cardiac death, target vessel myocardial infarction (TVMI), target lesion revascularisation (TLR), target vessel revascularisation (TVR) and MACE (combination of cardiac death, target vessel MI and TLR).

Results

During the study period, 351 patients (with 414 lesions) with de novo lesions were treated with an SCB. The mean age of patients was 65.6±11.5 years, 275 (78%) were male and 39% (n=212) had diabetes. Most lesions treated were in the LAD/diagonal system (n=173, 42%). Predilatation was performed in 98% (405 lesions). Bailout stenting (with a drug eluting stent) was required in 7% lesions (n=30), of which 11 were due to dissections and 19 were due to recoil >50% following DCB use. The mean diameter and length of DCBs were 2.47 mm and 26 mm respectively.

During a median follow-up of 322-days (11-months) cardiac death was reported in 8 patients (2.3%). Target vessel MI was in 3%; n=10, TLR and TVR per lesion were 8% (n=34) and 9% (n=37) respectively. The MACE rate was 11%. There were no documented cases of acute vessel closure.

Conclusion

The mid-term outcome from the first ever study on sirolimus coated balloons in de novo lesions appears promising with low rates of hard endpoints with no documented cases of acute vessel closure. The MACE rates appear promising, although we need longer follow-up which is ongoing and we will be able to report outcomes from even longer follow-up during the presentation.

Funding Acknowledgement

Type of funding sources: None.

Comparison of sprint training and high intensity interval training on oxidative stress and aerobic capacity in male soccer players

The study compared the two popular modes of training: repeated sprint and interval, in terms of oxidative load and aerobic capacity. 20 male collegiate soccer players were assigned into either a repeated sprint training (RST) or high intensity interval training (HIIT) group. Training protocols were for a period of 4 weeks (3 times/week). Serum levels of superoxide dismutase, catalase and glutathione, in addition to maximal oxygen uptake and maximum voluntary isometric contraction for quadriceps and hamstrings were measured before training and within 24 h after the completion of training. Significant improvement (P≤0.05) in antioxidant defence response and leg strength was seen in both groups. However, improvement in aerobic capacity was non-significant in RST as compared to HIIT. These findings indicate that both RST and HIIT can be used as a conditioning exercise to alleviate exercise-induced oxidative stress in the competition phase in addition to improvement in aerobic capacity.

Blood pressure is a risk factor for progression of diabetic retinopathy in normotensive patients with type 2 diabetes: correlation with carotid intima-media thickness

OBJECTIVE

Carotid atherosclerotic lesions have been described more frequently in patients with diabetes and microvascular disease than in those with uncomplicated diabetes. In this study, we investigated the role of blood pressure as a risk factor of diabetic retinopathy in normotensive patients with type 2 diabetes. We also assessed the correlation of carotid intima-media thickness with both blood pressure and diabetic retinopathy.

METHODS

The study group consisted of 140 normotensive patients (68 males and 72 females) with type 2 diabetes and diabetic retinopathy. Carotid intima-media thickness was evaluated using high-resolution B-mode ultrasonography. Diabetic retinopathy was assessed and graded, using colored fundus photography and fundus fluorescein angiography, as either non-proliferative or proliferative.

RESULTS

Patients with proliferative diabetic retinopathy showed a higher systolic and diastolic blood pressure (p<0.01). Carotid intima-media thickness was higher in patients with proliferative than non-proliferative diabetic retinopathy ones (1.094 ± 0.142 vs. 0.842 ± 0.134 mm, respectively; p<0.001) Carotid intima-media thickness showed positive correlation with both systolic (p<0.001) and diastolic blood pressures (p<0.01). No significant differences were found between males and females in any of the studied parameters.

CONCLUSION

Our study proves that both systolic and diastolic blood pressures are important risk factors for the progression of retinopathy in normotensive patients with type 2 diabetes. We also demonstrate that carotid intima-media thickness, as a marker of atherosclerosis, is strongly correlated with both blood pressure and diabetic retinopathy in those patients.