Long-term outcomes following transcatheter aortic valve implantation with the Portico self-expanding valve

AIM

Transcatheter aortic valve implantation (TAVI) is a mainstay in the management of severe aortic valve stenosis in elderly patients, but there is uncertainty on their long-term effectiveness. We aimed to assess the long-term outcome of patients undergoing TAVI with the Portico valve.

METHODS

We retrospectively collected the data on patients in whom TAVI with Portico was attempted from 7 high-volume centres. Only patients theoretically eligible for 3 or more years of follow-up were included. Clinical outcomes, including death, stroke, myocardial infarction, reintervention for valve degeneration and hemodynamic valve performance were systematically assessed.

RESULTS

A total of 803 patients were included, with 504 (62.8%) women, mean age of 82 years, median EuroSCORE II of 3.1%, and 386 (48.1%) subjects at low/moderate risk. The median follow-up was 3.0 years (3.0; 4.0). The composite of death, stroke, myocardial infarction, and reintervention for valve degeneration occurred in 37.5% (95% confidence interval: 34.1-40.9%), with all-cause death in 35.1% (31.8-38.4%), stroke in 3.4% (1.3-3.4%), myocardial infarction in 1.0% (0.3-1.5%), and reintervention for valve degeneration in 1.1% (0.6-2.1%). The mean aortic valve gradient at follow-up was 8.1 ± 4.6 mmHg, and at least moderate aortic regurgitation was present in 9.1% (6.7-12.3%). Independent predictors of major adverse events or death were: peripheral artery disease, chronic obstructive pulmonary disease, estimated glomerular filtration rate, atrial fibrillation, prior pacemaker implantation, EuroSCORE II, and reduced left ventricular ejection fraction (all p < 0.05).

CONCLUSIONS

Portico use is associated with favorable long-term clinical outcomes. Clinical outcomes were largely impacted by baseline risk factors and surgical risk.

Normalization of ascending aorta dimension for body size influences pathophysiologic correlation in hypertensive patients: the Campania Salute Network

AIMS

In the present study, we assessed correlates and their consistency of ascending aorta (AscAo) measurement in treated hypertensive patients.

METHODS AND RESULTS

A total of 1634 patients ≥ 18 years old with available AscAo ultrasound were included. Ascending aorta was measured at end-diastole with leading edge to leading edge method, perpendicular to the long axis of the aorta in parasternal long-axis view at its maximal identifiable dimension. Correlations of AscAo and AscAo normalized for height (AscAo/HT) or body surface area (AscAo/BSA) with demographics and metabolic profile were explored. Multi-variable regression was also used to identify potential confounders influencing univariate correlations. Sensitivity analysis was performed using cardiovascular (CV) outcome. Correlations with age, estimated glomerular filtration rate, systolic blood pressure (BP), and heart rate (HR) were similar among the three aortic measures. Women exhibited smaller AscAo but larger AscAo/BSA than men with AscAo/HT offsetting the sex difference. Obesity and diabetes were associated with greater AscAo and AscAo/HT but with smaller AscAo/BSA (all P < 0.001). In multi-variable regression model, all aortic measure confirmed the sign of their relations with sex and metabolic profile independently of age, BP, and HR. In Kaplan-Mayer analysis, only dilated AscAo and AscAo/HT were significantly associated with increased risk of CV events (both P < 0.008).

CONCLUSIONS

Among patients with long-standing controlled systemic hypertension, magnitude of aortic remodelling is influenced by the type of the measure adopted, with physiological consistency only for AscAo and AscAo/HT, but not for AscAo/BSA.

Hypertension-mediated organ damage involving multiple sites is an independent risk factor for cardiovascular events

Aims

Chronic pressure overload determines functional and structural alterations, leading to hypertension-mediated organ damage (HMOD), affecting multiple districts. We aim at evaluating the prognostic impact of the absence vs. presence of HMOD in one or more sites and of blood pressure (BP) and metabolic control in hypertensive patients.

Methods and results

The study included 7237 hypertensive patients from the Campania Salute Network Registry, followed up for 5.3 ± 4.5 years. As HMOD, we analysed the presence of left ventricular hypertrophy, carotid plaques, and chronic kidney disease (CKD-EPI ≥3 stage) and evaluated the impact of zero vs. one vs. two vs. three sites of HMOD on the occurrence of major adverse cardiovascular events (MACEs). Blood pressure control and Metabolic Score for Insulin Resistance (METS-IR) were also considered. Optimal BP control was achieved in 57.3% patients. Major adverse cardiovascular events occurred in 351 (4.8%) patients. The MACE rate in patients without HMOD was 2.7%, whereas it was 4.7, 7.9, and 9.8% in patients with one, two, and three sites with HMOD, respectively. By using Cox multivariate models, adjusted for age, BP control, mean heart rate, mean METS-IR, number of HMOD sites, and drugs, MACE was found to be significantly associated with ageing, mean METS-IR, anti-platelet therapy, and multiple sites with HMOD, whereas a negative association was found with renin-angiotensin system inhibitor drugs.

Conclusion

In hypertensive patients, the risk of MACE increases with the incremental number of districts involved by HMOD, independent of BP control and despite the significant impact of metabolic dysregulation. Hypertension-mediated organ damage involving multiple sites is the deleterious consequence of hypertension and dysmetabolism but, when established, it represents an independent cardiovascular risk factor for MACE occurrence.

Renin-angiotensin system inhibitors reduce cardiovascular mortality in hypertensive patients with severe aortic stenosis undergoing transcatheter aortic valve implantation: insights from the EffecTAVI registry

Objectives

Arterial hypertension is associated with the triggering of the renin-angiotensin system, leading to left ventricle fibrosis and worse cardiovascular outcomes. In this study, patients with comorbid arterial hypertension and severe aortic stenosis (AS) undergoing transcatheter aortic valve implantation (TAVI) were selected from the EffecTAVI registry to evaluate the impact of angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) on cardiovascular mortality.

Methods

We enrolled 327 patients undergoing TAVI from the EffecTAVI registry. Using Kaplan-Meier event rates and study-stratified multivariable Cox proportional hazards regression models, we evaluated 2-year clinical outcomes according to the ACEI/ARB therapy status at enrollment.

Results

Among the included patients, 222 (67.9%) were on ACEIs/ARBs at baseline, whereas 105 (32.1%) were not. Treatment with ACEIs/ARBs was significantly associated with a 2-year decrease in the rate of cardiovascular mortality (HR = 0.44, 95% CI: 0.23-0.81, p = 0.009). This association remained stable after both multivariable adjustment and propensity score matching.

Conclusion

In a cohort of hypertensive patients with severe AS who were selected from the EffecTAVI registry, ACEI/ARB treatment at baseline was found to be independently associated with a lower risk of 2-year cardiovascular mortality, suggesting a potential benefit of this treatment. More trials are needed to validate this finding and to understand the full benefit of this treatment.

Comparing Cardiovascular Adverse Events in Cancer Patients: A Meta-analysis of Combination Therapy with Angiogenesis Inhibitors and Immune Checkpoint Inhibitors versus Angiogenesis Inhibitors Alone

Anti-VEGF (vascular endothelial growth factor) agents were associated with increased risk of several cardiovascular events, while one meta-analysis did not show any significantly increased risk of cardiotoxicity associated with the use of immune checkpoint inhibitors (ICIs). This meta-analysis of randomized-controlled trials (RCTs) was designed to compare cardiovascular toxicity of anti-VEGF agents plus ICI vs anti-VEGF agents without ICIs. A systematic search of the literature was conducted to include all full papers reporting about phase II and III randomized controlled trials (RCTs) conducted in patients with solid malignancies randomized to an anti-VEGF agent plus an ICI vs. an anti-VEGF agent without an ICI. Overall incidences of cardiovascular events were compared between these two treatment groups estimating the corresponding odds ratios. This analysis suggests that ICIs may increase the risk of cardiovascular toxicities associated with anti-VEGF therapies. Further research, including real world studies, is warranted.

The hemodynamic performance of balloon-expandable aortic bioprostheses in the elderly: a comparison between rapid deployment and transcatheter implantation

BACKGROUND

Surgical aortic valve replacement with a rapid deployment valve (RDV) is a relatively recent treatment option. Aim of this study was to compare the hemodynamic performance of balloon-expandable (BE)-RDVs and BE-transcatheter heart valves (THVs) in a high surgical risk and frail-elderly population.

METHODS

BE-THVs and BE-RDVs were respectively implanted in 138 and 47 patients, all older than 75 years and with a Canadian Study of Health and Aging category of 5 or above. Echocardiographic assessment was performed at discharge and at six months.

RESULTS

At discharge, transprosthetic pressure gradients and indexed effective orifice area (iEOA) were similar in both cohorts. At six-month follow-up, BE-RDV showed lower peak (14.69 vs 20.86 mmHg; p <0.001) and mean (7.82 vs 11.83 mmHg; p <0.001) gradients, as well as larger iEOA (1.05 vs 0.84 cm²/m²; p <0.001). Similar findings were also shown considering only small sized valves. Moderate-to-severe paravalvular leakage was more prevalent in BE-THVs at discharge (14.49 vs 0.00%; p=0.032) and, considering exclusively small prostheses, at six months too (57.69 vs 15.00%; p=0.014). Nevertheless, BE-THVs determined amelioration in left ventricular ejection fraction (53.79 vs 60.14%; p <0.001), pulmonary artery systolic pressure (35.81 vs 33.15 mmHg; p=0.042) and tricuspid regurgitation severity (40.58 vs 19.57%; p=0.031) from discharge to mid-term follow-up.

CONCLUSIONS

BE-RDVs showed better hemodynamic performance, especially when implanted in small annulus. Despite their worse baseline conditions, transcatheter patients still exhibited a greater improvement of their echocardiographic profile at mid-term follow-up.

Transcatheter aortic valve implantation with the novel-generation Navitor device: Procedural and early outcomes

Transcatheter aortic valve implantation (TAVI) has proved beneficial in patients with severe aortic stenosis, especially when second‐generation devices are used. We aimed at reporting our experience with Navitor, a third‐generation device characterized by intrannular, large cell, and cuffed design, as well as high deliverability and minimization of paravalvular leak. Between June and December 2021, a total of 39 patients underwent TAVI with Navitor, representing 20% of all TAVI cases. Mean age was 80.0 ± 6.7 years, and 14 (36.8%) women were included. Severe aortic stenosis was the most common indication to TAVI (37 [97.4%] cases), whereas 2 (5.3%) individuals were at low surgical risk. Device and procedural success was obtained in all patients, with a total hospital stay of 6.6 ± 4.5 days. One (2.9%) patient required permanent pacemaker implantation, but no other hospital events occurred. At 1‐month follow‐up, a cardiac death was adjudicated in an 87‐year‐old man who had been at high surgical risk. Echocardiographic follow‐up showed no case of moderate or severe aortic regurgitation, with mild regurgitation in 18 (47%), and none or trace regurgitation in 20 (53%). The Navitor device, thanks to its unique features, is a very promising technology suitable to further expand indications and risk‐benefit profile of TAVI.

Transcatheter aortic valve implantation in patients with age ≤70 years: experience from two leading structural heart disease centers

BACKGROUND

Transcatheter aortic valve implantation (TAVI) is emerging a an appealing management strategy for patients with severe aortic stenosis at intermediate, high or exceedingly high risk, but its risk-benefit profile in younger patients is less certain. We aimed at exploring the outlook of patients aged 70 years or less and undergoing TAVI at 2 high-volume Italian institituions.

METHODS

We retrospectively collected baseline, imaging, procedural and outcome features of patients with age ≤70 years in whom TAVI was attempted at participating centers between 2012 and 2021. Non-parametric tests and bootstrap resampling were used for inferential purposes.

RESULTS

A total of 39 patients were included, out of >3,000 screened with heart team involvement and >1,500 receiving TAVI. Most common or relevant indications for TAVI were reduced life expectancy (eg cardiogenic shock or severe left ventricular systolic dysfunction), chronic obstructive pulmonary disease, morbid obesity, active or recent extra-cardiac cancer, porcelain aorta, neurologic disability, cirrhosis, or prior surgical aortic valve replacement, as well as extreme cachexia, and Hutchinson-Gilford progeria. At least two contemporary high-risk features were present in most cases. Transapical access was used in 5 (12.8%) cases, and a sheathless approach in 15 (38.5%). A variety of devices were used, including both balloon- and selfexpandable devices. Clinical outcomes were satisfactory, despite the high risk profile, at both shortand mid-term, with no in-hospital death, and 5.1% (95% confidence interval 0-12.8%) mortality at a median follow-up of 15 months (minimum 1; maximum 85). Notably, no case of significant valve deterioration requiring reintervention occurred.

CONCLUSIONS

In carefully selected patients with 70 years or less of age and prohibitive risk for surgery or reduced life expectancy, TAVI represents a safe option with a favorable mid-term survival and low rate of adverse events.

58 Effects of sodium–glucose co-transporter 2 (SGLT2) inhibitors on major cardiovascular events in Type 2 diabetic patients: a meta-analysis of randomized controlled trials

Aims

Sodium–glucose co-transporter-2 inhibitors (SGLT2i) reduce cardiovascular (CV) events in diabetic patients, with a consistent effect on heart failure (HF) related outcomes. However, the effects on ischaemic CV events appear less certain, in particular in patients with history of HF. The aim of this meta-analysis is to investigate CV benefit of SGLT2i and to assess the effects in patients with and without established atherosclerotic cardiovascular disease (ASCVD), with and without HF, and with estimated glomerular filtration rate &lt; or ≥ 60 mL/min.

Methods

We searched PubMed, Embase, Cochrane, ISI Web of Science, SCOPUS, and clinicaltrial.gov databases. We performed a systematic review and meta-analysis of randomized, placebo-controlled, cardiovascular outcome trials (CVOT) of SGLT2i in diabetic patients, assessing the effects of SGLT2i on 3-point MACE [CV death, non-fatal myocardial infarction (MI), non-fatal stroke] and composite of HF hospitalization or CV death.

Results

Of 205 articles, 7 CVOTs were included in the meta-analysis. Compared to placebo, SGLT2i significantly reduced by 10% the risk of 3-point MACE (HR 0.90; P = 0.025) (Figure panel A) and the risk of CV death or HF hospitalization by 24% (HR 0.76; P &lt; 0.001) (Figure panel B). SGLT2i significantly reduced HF hospitalization by 30% (HR 0.70; P &lt; 0.001), with consistent effects in all subgroups analysed, CV death by 17% (HR 0.83; P = 0.035) and all-cause mortality by 18% (HR 0.82; P = 0.024). No significant effects were observed on MI and stroke.

Conclusions

SGLT2i significantly reduce CV outcome in diabetic patients. SGLT2i remarkably and consistently reduce HF hospitalization, in patients with and without HF at baseline and independently on the presence of ASCVD.

Non-cardiac surgery in patients with valvular heart disease

In patients with significant valvular heart disease (VHD) undergoing non-cardiac surgery (NCS), perioperative adverse cardiac events are a relevant issue. Although postoperative outcomes can be adversely affected by valve-related haemodynamic instability, recommended perioperative risk scores prioritise the risk of the surgical procedure and the presence of cardiovascular risk factors, neglecting the presence or extent of VHD. Perioperative management and anaesthetic approach should focus on the underlying type and severity of VHD, the compensatory mechanisms deployed by left ventricle and right ventricle and the type and risk of NCS. Due to the lack of randomised trials investigating different therapeutic approaches of valvular intervention prior to NCS, recommendations mainly rely on consensus opinion and inference based on large observational registries. As a general rule, valvular intervention is recommended prior to NCS in symptomatic patients or in those who meet standard criteria for cardiac intervention. In the absence of such conditions, it is reasonable to perform NCS with tailored anaesthetic management and close invasive perioperative haemodynamic monitoring. However, patient-specific management strategies should be discussed with the heart team preoperatively. Symptomatic patients with severe VHD or those undergoing high-risk NCS should ideally be treated at a high-volume medical centre that is equipped to manage haemodynamically complex patients during the perioperative period.

Renal function and cardiac adrenergic impairment in patients affected by heart failure

Although in heart failure (HF) there is a strict correlation between heart and kidney, no data are available on the potential relationship in HF between renal dysfunction (RD) and the impaired sympathetic innervation. Aim of the present study was to assess the relationship between RD and cardiac sympathetic innervation in HF patients with reduced ejection fraction. Two hundred and sixty-three patients with mild-to-severe HF underwent iodine-123 meta-iodobenzylguanidine myocardial scintigraphy to assess sympathetic innervation, evaluating early and late heart-to-mediastinum (H/M) ratios and washout rate. In all patients, glomerular filtration rate (eGFR) by Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula was assessed. A direct association was found between EPI-eGFR and late H/M (r = .215; P < .001). Dividing the population into moderate-to-severe eGFR reduction and normal-to-mildly reduced eGFR (cutoff ≤ 60 mL·min-1·1.73 m-2), a statistically significant reduction of late H/M value was found in patients with RD compared to patients with preserved eGFR (P = .030). By multivariable linear regression analysis, eGFR resulted in the prediction of impaired late H/M in patients with RD (P = .005). Patients with RD and HF show more impaired cardiac sympathetic activity than HF patients with preserved renal function, and reduced eGFR is a predictor of reduced late H/M.

Cervical spine trauma: impact of different imaging classification systems in the clinical decision-making

Background and aim:

Considering the high rate of mortality and permanent disability related to vertebral traumas, an early and detailed diagnosis of the trauma and subsequently an immediate and effective intervention are crucial. Cervical vertebral injury classifications guide treatment choice through a severity grade based on radiological information. The purpose of the present study was to define which imaging classification system could provide the best morphological and clinical-surgical correlations for cervical spine traumas.

Methods:

We retrospectively analyzed patients evaluated for cervical spine trauma at our Institution in the period 2015-2020. Information regarding the morphological examination (using CT and MRI), the neurological evaluation, and the therapeutic management were collected. C3-C7 fractures were classified according to the SLIC and AOSpine criteria; axial lesions were classified according to the modified AOSpine for the C1-C2 compartment and through the Roy-Camille and the Anderson D’Alonzo system for the odontoid process of the axis.

Results:

29 patients were included in the final study population. Nine patients with axial spine trauma and 21 with subaxial cervical spine trauma. A conservative approach was applied in 16 patients while nine patients underwent neurosurgery. Considering the therapeutical indications provided by the SLIC system, a 76.9% accordance was found for patients with a <4 score, while a 100% concordance was calculated for patients with a >4 score undergoing neurosurgery. Regarding the AOSspine classification, a 28.6% concordance was observed for patients classified group B being treated with a posterior neurosurgical approach, while for patients belonging to subgroup C, considered for anterior neurosurgical approach, a 66.7% accordance was calculated.

Conclusions:

The study demonstrated a better morphological correlation for the AOSpine classification in subaxial trauma and the AOSpine and Anderson D’Alonzo in axial trauma. The therapeutic indication found a better correlation in the SLIC classification for subaxial trauma and the Anderson D’Alonzo for axial ones. (www.actabiomedica.it)

The role of interventional radiology in hepatic and renal hemorrhage embolization: single center experience and literature review

Background and aim:

Intraabdominal hemorrhage secondary to liver and kidney injury is a major cause of morbidity and mortality. Endovascular arterial embolization is an established interventional radiology technique used to treat active bleeding, and its role in managing abdominal hemorrhages is growing, given the increasing trend for conservative treatment. Our study aims to retrospectively evaluate the technical and clinical results and the possible complications of arterial embolization procedures performed in emergency, in post-traumatic, iatrogenic, and pathological hepatic and renal bleedings.

Methods:

We performed a ten-year, single-center retrospective survey (from January 2010 to December 2019) of all patients treated in emergency by intra-arterial embolization of liver and kidney bleeding. Preliminary CT angiography studies were evaluated, as well as the angiographic findings. Materials used, procedural data, and clinical outcomes, including complications, were recorded.

Results:

The diagnostic angiography showed a single source of bleeding in 20 cases (66.7%), two bleeding vessels in 4 cases (13.3%), and multiple hemorrhagic sources in 6 cases (20%). All bleeding sources were successfully embolized; in 12 patients (40%), complete embolization was achieved with coils and 18 patients (60%) with hemostatic sponges. In one case, a second embolization procedure was performed for the persistence of hemodynamic instability. No major post-procedural complications were recorded. The mean procedure duration was 65.1 minutes.

Conclusions:

Based on our experience and literature data, the treatment of endovascular embolization in acute abdominal bleeding of hepatic and renal origin represents the treatment of choice, as it can provide complete therapeutic success in hemodynamically stable patients. (www.actabiomedica.it)

Prognostic Value of Hormonal Abnormalities in Heart Failure Patients

The model used to explain the pathophysiologic substrate and progressive worsening in chronic heart failure (CHF) is based on the hyperactivity of renin-angiotensin-aldosterone system and adrenergic pathway. Although the neurohormonal medical approach has many advantages, it has several pitfalls, as demonstrated by high rates of CHF mortality and hospitalization. A growing body of evidence has led to the hypothesis that CHF is a multiple hormone deficiency syndrome, characterized by a reduced anabolic drive that has relevant functional and prognostic implications. The aim of this review is to summarize the evidence of reduced drive of main anabolic axes in CHF.

Environmental analysis of sunflower production with different forms of mineral nitrogen fertilizers

Environmental profiles of mineral nitrogen fertilizers were used to evaluate the environmental disturbances related to their use in cultivation systems in Europe. Since the production of mineral fertilizers requires a large amount of energy, the present study of bioenergy systems is relevant in order to achieve crop yields less dependent on fossil fuels and to reduce the environmental impact due to fertilization. In this study, the suitability of the LCA methodology to analyze the environmental impact of sunflower cultivation systems with different forms of mineral nitrogen fertilizers urea and ammonium nitrate was investigated. Effects on climate change were estimated by the use of Ecoinvent 2.2 database default value for soil N2O emission factor (1%) and local emission data (0.8%) of mineral nitrogen applied to soils. LCA analysis showed a higher impact on environmental categories (human health and ecosystem quality) for the system in which urea was used as a nitrogen source. Use of urea fertilizer showed a higher impact on resource consumption due to fossil fuel consumption. Use of mineral nitrogen fertilizers showed a higher environmental burden than other inputs required for sunflower cultivation systems under study. Urea and ammonium nitrate showed, respectively, a 7.8% and 4.9% reduced impact of N2O as greenhouse gas by using direct field data of soil N2O emission factor compared to the default soil emission factor of 2006 IPCC Guidelines. Use of ammonium nitrate as mineral nitrogen fertilizer in sunflower cultivation would have a lower impact on environmental categories considered. Further environmental analysis of available technologies for fertilizer production might be also evaluated in order to reduce the environmental impacts of each fertilizer.

Use of biolog methodology for optimizing the degradation of hydrocarbons by bacterial consortia

Biolog methodology was used for the preliminary screening of different cultural conditions in order to detect the best combination/s of factors influencing the metabolic performance of bacterial consortia active in the degradation of hydrocarbons. Two microbial consortia were tested for their activity on 2 hydrocarbons (nonadecane and eicosane) in presence of the following cultural coadjuvants: vegetal oil, beta-cyclodextrine, sodium acetate, mineral solution. Tests were conducted in Biolog MT plates, where only the redox indicator of microbial growth (tetrazolium violet) and no carbon sources are provided. The microwells were filled with various combinations of hydrocarbons, microbial inoculum and coadjuvants. Blanks were prepared with the same combinations but without hydrocarbons. The results obtained show the suitability of the methodology developed to identify the most active consortium and the conditions for its best degradation performance. The efficacy of Biolog methodology (Biolog Inc., USA) for the characterization of microbial communities on the basis of the metabolic profiles obtained on specific carbon sources in the microwells of Elisa-type plates, is widely acknowledged (Garland, 1997; Pietikäinen et al., 2000; Dauber and Wolters, 2000). Due to its aptitude to simultaneously evaluate multiple microbial responses and directly organize the results, it can be adapted to meet specific study purposes (Gamo and Shji, 1999). In the present research Biolog methodology was fitted for the preliminary screening of different cultural conditions, in order to detect the best combination/s of factors influencing the metabolic performance of bacterial consortia active in the degradation of aliphatic hydrocarbons, in view of their utilization for the bioremediation of polluted sites.

Hydrocarbon degradation by a soil microbial population with beta-cyclodextrin as surfactant to enhance bioavailability

In general the biodegradation of nonchlorinated aliphatic and aromatic hydrocarbons is influenced by their bioavailability. Hydrocarbons are very poorly soluble in water. They are easily adsorbed to clay or humus fractions in the soil, and pass very slowly to the aqueous phase, where they are metabolised by microorganisms. Surfactants that increase their solubility and improve their bioavailability can thereby accelerate degradation. Cyclodextrins are natural compounds that form soluble complexes with hydrophobic molecules. They are widely used in medicine and harmless to microorganisms and enzymes. This paper describes their in vitro effect on the biodegradative activity of a microbial population isolated from a petroleum-polluted soil, as shown by the decrease of dodecane (C12), tetracosane (C24) anthracene and naphthalene added individually as the sole carbon source to mineral medium liquid cultures. beta-cyclodextrin accelerated the degradation of all four hydrocarbons, particularly naphthalene, and influenced the growth kinetics as shown by a higher biomass yield and better utilization of hydrocarbon as a carbon and energy source. Its low cost, biocompatibility and effective acceleration of degradation make beta-cyclodextrin an attractive option for bioremediation.

Saccharomyces cerevisiae cell fatty acid composition and release during fermentation without aeration and in absence of exogenous lipids

Medium-chain fatty-acids (MCFA) are among the main aroma compounds of fermented beverages. High concentrations of MCFA have been found in sluggish and stuck fermentations. It has been suggested that they arrest cell growth, as they may be toxic, but the causes of sluggish and stuck fermentations are still unclear. The aim of this work was to see whether the production of MCFA is related to fatty acid synthesis in the absence of exogenous lipids and aeration, and whether their increase can be regarded as a consequence, instead of the cause, of sluggish and stuck fermentations. Two possibilities were considered: (i) MCFA are produced to replace unsaturated fatty acids (UFA) for cell membrane fluidity when the lack of oxygen makes desaturation of saturated fatty acids (SFA) impossible; or (ii) MCFA are produced following the release of medium-chain acyl-CoA from the fatty acid synthetase complex (FAS) due to the accumulation of SFA, and their hydrolysis to recycle CoA-SH. In the first hypothesis, MCFA should be active in cell metabolism and be found in cell structures; in the second, MCFA should be a discard and prevalently found outside the cell. We carried out a Saccharomyces cerevisiae fermentation experiment in a synthetic, lipid-free medium without aeration. We measured the fatty acid composition of yeast cells and the amounts of MCFA and their ethyl esters in the medium throughout the fermentation. Cell growth and the oxygen content of the medium were also monitored. We found that MCFA are not immobilized in cell structures, but mainly released into the medium. Cell growth is arrested because fatty acid biosynthesis is prevented by the lack of oxygen. The higher MCFA concentrations found in sluggish and stuck fermentations can be thus regarded as an effect, and not the cause, of this arrest. Some suggestions for the prevention of these events are proposed.

Esterase activity and release of ethyl esters of medium-chain fatty acids by Saccharomyces cerevisiae during anaerobic growth

During anaerobic fermentation, Saccharomyces cerevisiae releases large amounts of medium-chain fatty acids (MCFAs) and related ethyl esters which are very important for aromatic quality of fermented beverages. The physiological function of ester synthesis is not yet understood. As MCFAs are toxic, their conversion to esters has been proposed to be a detoxification mechanism. Esterases possess ester synthesizing ability. Throughout an anaerobic fermentation of a lipid-free synthetic medium carried out with a S. cerevisiae strain selected for wine making, we have monitored MCFA and ethyl ester production and, at the same time, measured growth and esterasic activity of intact cells. Because no correlation was found between the concentration of each fatty acid and its ethyl ester, there is no evidence that ester synthesis reduces the toxicity of MCFAs. Esterasic activity did not show any correlation with ester synthesis, but it was related to the release of MCFAs. A model is proposed in which ester synthesis is a consequence of the arrest of lipid biosynthesis resulting from a lack of oxygen. Under these conditions, an excess of acyl coenzyme A is produced, and acyl esters are formed as secondary products of reactions aimed at recovering free coenzyme A.