A new echocardiographic index to select patients for PFO suture-mediated percutaneous closure

OBJECTIVES

To identify a simple echocardiographic predictor of procedural success to select patient for percutaneous suture-mediated patent fossa ovalis (PFO) closure.

BACKGROUND

Percutaneous suture-mediated PFO closure has been shown as a safe and advantageous alternative to device-based PFO closure, yet its overall success is slightly lower in unselected patients.

METHODS

Preprocedural transesophageal echocardiogram (TEE) of 302 patients (113 men, 45 ± 12 years) who underwent percutaneous suture-mediated PFO closure were reviewed.

RESULTS

At echocardiographic follow-up (3-6 months), residual right-to-left shunt (RLS) ≥2 was found in 60 (19.9%) patients. At multivariable analysis, only two anatomical variables measured at preprocedural TEE were found as independent predictors of residual RLS ≥ 2 at follow-up: PFO maximum width (odds ratio [OR] 1.89, 95% confidence interval [CI] 1.16-3.40, p = 0.02) and PFO minimal septa overlapping (OR 0.58, 95% CI 0.35-0.88, p = 0.02). An index based on the ratio of PFO maximum width to PFO minimum septal overlapping (W/SO) proved to be the most powerful predictor of RLS ≥ 2 at follow-up (OR 48.1, 95% CI 9.3-352.2, p < 0.01). The ROC curve for the W/SO ratio was found to have an AUC of 0.84 (95% CI 0.75-0.93) and a cut-off value of 0.61 yielding a sensitivity of 80% and specificity of 78% with a negative predictive value of 94%. A decision tree methodology's AUC was 0.75 (95% CI 0.67-0.83).

CONCLUSIONS

The results of this study indicate that the ratio between the maximum amplitude of the PFO and the minimum overlap of the septa is the best predictive index of a favorable result by using one stitch only.

Atrial function analysis after percutaneous umbrella device and suture-mediated patent fossa ovalis closure

BACKGROUND

Atrial fibrillation is an undesirable event following percutaneous patent fossa ovalis (PFO) closure with metallic occluders, suggesting that implanting a rigid closure device could alter atrial function. Suture-mediated PFO closure is a new technique, achieving closure of the PFO by means of a simple suture. Aim of this study was to evaluate left atrial function after closure of PFO by direct suture and traditional occluders.

METHODS

We studied 40 age and sex homogeneous patients, 20 undergoing PFO closure by device (OCL) and 20 by suturing (NS). Twenty healthy sex-age matched subjects made up the control group (CT). Left atrial function was evaluated by using volumetric and speckle-tracking analysis assessing the following parameters: total emptying fraction (EF), Expansion Index (EI), active emptying fraction (AEF), strain values of the reservoir (r-ED), conduit (cd-ED) and contraction phase (ct-ED).

RESULTS

Compared to CT and NS, OCL patients had significantly worst indices of left atrial reservoir function (EF P=0.001, EI P=0.003, r-ED P<0.001), conduit function (cd-ED P=0.018) and contraction function (AEF P=0.010; ct-ED P<0.001). No significant differences were observed in left atrial function indices between CT and NS patients.

CONCLUSIONS

Suture-mediated PFO closure does not alter left atrial function. Conversely, metallic occluder is associated with worse left atrium function. This detrimental effect on atrial function could favor the development of atrial arrhythmias.

Atrial function analysis after percutaneous umbrella device and suture-mediated patent fossa ovalis closure: a prospective study

Background

Suture-mediated patent fossa ovalis (PFO) closure is a new technique, achieving closure of the PFO by means of a simple suture. The difference between traditional occluders and a simple suture might have different impact on atrial structure, geometry and function.

Purpose

Aim of this study was to evaluate bi-atrial function after closure of PFO by direct suture and traditional occluders.

Methods

We studied 40 age and sex matched patients, 20 undergoing PFO closure by device and 20 by suturing. Only patients with no residual right-to-left shunt, assessed by contrast-enhanced echocardiography, were included. Left and right atrial function was evaluated by using speckle-tracking analysis assessing the following parameters: strain values of the reservoir (r-ED), conduit (cd-ED) and contraction phase (ct-ED). All patients underwent transthoracic echocardiographic examination the day before and 1 year after the procedure. All exams and measurements were conducted by two echocardiographers and validated with common consent by two other expert operators.

Results

Compared with values baseline PFO closure, at one year follow-up, patients underwent occluder implantation had significantly worst indices of left (LA) and right (RA) atrial reservoir function (LA r-ED p&lt;0.001; RA r-ED p&lt;0.001), conduit function (LA cd-ED p&lt;0.001; RA cd-ED p&lt;0.001) and contraction function (LA ct-ED p&lt;0.05; RA ct-ED p&lt;0.05).

In patients underwent suture-mediated PFO closure, no significant differences were observed in the same indices of reservoir (LA r-ED p=0.848; RA r-ED p=0.183), conduit (LA cd-ED p=0.156; RA cd-ED p=0.419) and contraction function (LA ct-ED p=0.193; RA ct-ED p=0.375).

Conclusions

Suture-mediated PFO closure does not alter atrial function. Conversely, PFO closure by metallic occluders is associated with worse atrial function. This detrimental effect on atrial function could favor the development of atrial arrhythmias.

Funding Acknowledgement

Type of funding sources: None.

Single predictor of residual right-to-left shunt to optimally select patients for suture-mediated percutaneous patent fossa ovalis closure

Background

In patients with patent fossa ovalis (PFO) and paradoxical embolism, percutaneous closure of the interatrial communication has been proven more effective than medical treatment only to reduce recurrent thromboembolic events. Percutaneous suture-mediated PFO closure has been proved to be a safe and advantageous alternative to device-based PFO closure, yet its overall success rate is slightly lower in unselected patients. Hence, it is extremely important to define baseline features associated with unsatisfactory results to appropriately select patients suitable for this technique.

Purpose

Systematic assessment of PFO anatomy in the largest series of consecutive patients undergoing suture-mediated percutaneous PFO closure to identify a single baseline predictor of significant residual right-to-left shunt (procedural failure) for optimal selection of patient to be submitted to this procedure.

Methods

Pre-procedural transesophageal echocardiogram (TEE) of 302 consecutive patients (113 men, 45±12 years) who underwent percutaneous suture-mediated PFO closure at a single institution were accurately reviewed to assess a series of parameters: presence and grade of spontaneous right-to-left shunt (RLS), PFO length and width, presence of atrial septal aneurysm and its maximal bulge, and presence of an embryonic or fetal remnant (Chiari network or Eustachian valve).

Results

At echocardiographic follow-up (3–6 months from the closure procedure), a residual RLS ≥2 was found in 60 (19.9%) patients. At multivariable analysis, only two anatomical variables measured at pre-procedural TEE were found as independent predictors of residual RLS ≥2 at follow-up: PFO maximum width (OR 1.89, 95% CI 1.16–3.40, p=0.019) and PFO minimum length (OR 0.58, 95% CI 0.35–0.88, p=0.018). An index based on the ratio of PFO maximum width to PFO minimum septal overlapping (W/SO) was found to be the most powerful predictor of RLS ≥2 at follow-up (OR 48.1, 95% CI 9.3–352.2, p&lt;0.001). The ROC curve for the W/SO ratio was found to have an AUC of 0.84 (95% CI 0.75–0.93) and a cut-off value of 0.61 yielding a sensitivity of 80% and specificity of 78% with a negative predictive value of 94%.

Conclusions

Baseline pre-procedural TEE assessment provides essential information for the selection of patients most suitable to undergo suture-mediated PFO closure. Our results indicate that the ratio between the maximum amplitude of the PFO and the minimum overlap of the septa is the optimal single baseline index to optimally select patient for an effective percutaneous PFO closure.

Funding Acknowledgement

Type of funding sources: None.

Predictors of Residual Right-to-Left Shunt After Percutaneous Suture-Mediated Patent Fossa Ovalis Closure

OBJECTIVES

This study sought to assess patent fossa ovalis (PFO) anatomy by transesophageal echocardiography (TEE) in patients undergoing percutaneous suture-mediated PFO closure to identify predictors of post-procedural residual atrial right-to-left shunt (RLS).

BACKGROUND

Percutaneous suture-mediated PFO closure has been proven to be a safe and effective technique in most PFO patients.

METHODS

From June 2016 to October 2019, 247 consecutive patients underwent percutaneous suture-mediated PFO closure at our institution. Of them, 230 (46 ± 13 years of age, 146 women) had complete and technically evaluable pre-procedural TEE. The following parameters in short-axis view were assessed: presence and grade of spontaneous RLS, PFO length and width, presence of atrial septal aneurysm and its maximal bulge, and presence of an embryonic or fetal remnant (Chiari network or Eustachian valve).

RESULTS

At the first follow-up transthoracic echocardiography performed between 3 and 6 months from the closure procedure, a residual RLS ≥2 grade was found in 37 (16%) patients. Grade of pre-procedural spontaneous RLS (hazard ratio: 1.99; 95% confidence interval: 1.14 to 3.48; p = 0.016) shunt and PFO width (hazard ratio: 2.52; 95% confidence interval: 1.85 to 3.43; p < 0.001) were both found to be significantly associated with significant residual RLS at multivariable analysis. The presence of atrial septal aneurysm and its maximal bulge and of congenital remnants was not associated with significant residual RLS.

CONCLUSIONS

Percutaneous suture-mediated PFO closure is feasible in the majority of septal anatomies; however, PFO >5 mm in width and spontaneous large RLS are less likely to be closed with 1 stitch only.

Percutaneous suture-mediated Patent Fossa Ovalis (PFO) closure: two-year clinical follow-up

BACKGROUND

Percutaneous suture-mediated patent fossa ovalis (PFO) closure has been recently introduced in clinical practice showing a favorable efficacy and safety profile in most PFO cases. The aim of this study was to assess the long-term outcomes of PFO closure by direct suture in a large consecutive series of patients.

METHODS

We extracted all consecutive patients who underwent percutaneous closure of the PFO by suture technique (HeartStitch, Fountain Valley, CA, USA) from June 2016 with a follow up of at least 2 years. After PFO closure, patients were followed-up clinically at 1, 6 and up to 12 months and microbubble transthoracic echocardiography (TTE) scheduled between 3 and 6 months, and at 12-month followup. After 12 months, patients were clinically checked every 6 months.

RESULTS

As of September 1, 2020, 187 patients had undergone PFO closure with suture for at least two years and, of these, 181 (121 women and 60 men, mean age 45±13 years, range 15-75 years) had complete clinical and instrumental follow-up (97%). There were no peri-procedural complications. Mean follow up was 1076±251 days (range 727-1574). At 12-month TTE, a significant residual atrial shunt was found in 39 patients (21%). At follow-up no recurrent thromboembolic or cerebral event occurred, no instrumental evidence of suture dehiscence detected and, 18 months after the procedure, one patient had an episode of transient atrial fibrillation lasting less than 24 hours and resolved spontaneously.

CONCLUSIONS

Long-term follow-up data indicate that PFO closure by direct suturing is safe and effective. Two years after the procedure, there were no significant complications, no permanent arrhythmic complications and evidence of suture dehiscence.

Anatomical predictors of residual left-to-right shunt after percutaneous suture-mediated patent fossa ovale closure

Background

Percutaneous suture-mediated patent fossa ovale (PFO) closure has recently been introduced in clinical practice to overcome most of the limitations of metallic PFO occluders with early results showing a favourable efficacy and safety profile in most PFO cases.

Purpose

To assess PFO anatomy in a large series of patients undergoing percutaneous suture-mediated PFO closure in order to identify anatomical predictors of significant residual right-to-left shunt (RLS) and thus appropriately select patients to be submitted to this technique.

Methods

Pre-procedural transesophageal echocardiogram of 230 patients undergoing suture-mediated PFO closure at our Institution were carefully reviewed both qualitatively and quantitatively. The following parameters were systematically assessed in all reviewed cases: presence and grade of baseline atrial RLS, presence of bidirectional shunt, PFO length and width, presence of atrial septal aneurysm and its maximal bulge, presence and size of an embryonic or foetal remnant.

Results

In 37 patients a residual atrial RLS ≥2 grade was found at a mean follow-up of 248±147 days. The following variable were found to be significantly associated with significant residual atrial RLS at follow-up: grade of baseline spontaneous and Valsalva manoeuvre RLS shunt (odds ratio 2.39, 95% confidence interval 1.48–3.89, p=0.001 and odds ratio 3.07, 95% confidence interval 1.22–7.23, p=0.017), baseline bidirectional shunt across the PFO (odds ratio 3.59, 95% confidence interval 1.47–8.77, p=0.005) and PFO width (odds ratio 2.61, 95% confidence interval 1.92–3.55, p=0.001).

At multivariable analysis, only PFO width ≥5 mm (odds ratio 10.97, 95% confidence interval 4.22–28.56, p=0.001) and grade of baseline RLS shunt (odds ratio 1.84, 95% confidence interval 1.05–3.21, p=0.032) were independent predictors of a significant atrial RLS at follow-up.

Conclusions

Suture-mediated PFO closure represents a valid alternative to traditional devices with an excellent safety and efficacy profile at follow-up. As for any new technique, it is extremely important to select the right anatomical and functional features predictive of a successful closure. The results of this study indicate that the suture-mediated closure of PFO is feasible in the majority of septal anatomies however wide PFO ≥5 mm are less likely to be closed with only one stitch.

Funding Acknowledgement

Type of funding source: None

Concept and practice of transradial 5 French percutaneous treatment of coronary bifurcation lesions

OBJECTIVES

To assess the efficacy and safety of transradial 5 French percutaneous treatment of coronary bifurcations using conventional devices.

BACKGROUND

Radial artery is smaller than femoral artery, and its size may potentially limit transradial intervention, especially when coronary anatomy is not known.

METHODS

Patients with bifurcations lesions undergoing transradial 5 French ad hoc revascularization were treated according to provisional side branch (SB) stenting followed by the POT-SB dilation-final POT sequence. Only conventional devices were used.

RESULTS

Overall, 80 patients (58 men, 65 ± 10 years) were enrolled. True bifurcations accounted for 64% of cases, with the left anterior descending artery/diagonal branch being the most frequent bifurcation site (n = 37, 46%) and left main coronary artery bifurcation being treated in 6 (8%) patients. Angiographic success was achieved in 78 (97.5%) patients through a 5 French guiding catheter whereas in two cases, a 5-6 French guiding catheter upgrade was required to optimize SB treatment after the main bifurcation vessel have been secured. Overall, procedural success was achieved in all but one patient who had periprocedural necrosis following multivessel PCI. Another patient underwent target bifurcation revascularization because of a critical restenosis in a significant SB yielding an acute coronary syndrome five months after the index procedure.

CONCLUSIONS

This study demonstrates the feasibility of transradial 5 French bifurcation intervention with nondedicated devices and preliminary supports its efficacy and safety over a wide range of bifurcation anatomy and complexity.

Angiographic and clinical performance of polymer-free biolimus-eluting stent in patients with ST-segment elevation acute myocardial infarction in a metropolitan public hospital: The BESAMI MUCHO study

OBJECTIVES

This study aimed at assessing the performance of a new generation polymer-free biolimus-eluting stent (BES) in real-world patients with ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

Polymers components of early-generation drug-eluting stents have been implicated in the pathogenesis of delayed arterial healing, vessel remodeling, and delayed stent thrombosis. Recently, a novel polymer-free BES has shown excellent clinical performance in clinical trial setting.

METHODS

Overall, 175 consecutive patients (64 ± 14 years, 141 men) treated with the BioFreedom (Biosensors Europe, Morges, Switzerland) polymer-free BES because of STEMI were included in this study. The primary endpoint was the rate of major adverse cardiac events (MACE), a composite of cardiac death, recurrent myocardial infarction, and ischemia-driven target vessel revascularization at 1 year follow-up. A subgroup of patients underwent 6-month angiographic follow-up. Dual antiplatelet therapy was prescribed for 12 months after STEMI.

RESULTS

At 1 year, the cumulative rate of MACE was 4.6%. One patient (0.6%) had an arrhythmic cardiac death and five (2.9%) had ischemia-driven target vessel revascularization, although only three (1.7%) had target lesion revascularization. Two (1.1%) patients had acute stent thrombosis yielding nonfatal myocardial infarction. In 70 patients (63 ± 14 years, 61 men), quantitative coronary angiography at 6-month follow-up revealed diameter stenosis of 24.1 ± 13.7% and minimal lumen diameter of 2.29 ± 0.56 mm, yielding a late lumen loss of 0.13 ± 0.14 mm.

CONCLUSIONS

In real-world setting, implantation of a new-generation polymer-free BES during STEMI is associated with favorable clinical and angiographic results, pointing toward the overall efficacy and safety of the device in complex clinical scenarios.

Abstract P3-03-08: A large-scale functional screen to identify resistance mechanisms to selective estrogen receptor degraders fulvestrant and GDC-810 in ER+ breast cancer

Therapies that target the estrogen receptor provide clinical benefit and improved survival for patients with estrogen receptor-positive (ER+) breast cancer, yet drug resistance remains a challenging problem, leading to disease relapse and mortality. In recent years, the selective estrogen receptor degrader (SERD) fulvestrant has become an important therapeutic option for patients with resistant ER+ metastatic breast cancer, and newer oral SERDs such as GDC-810 are currently being tested in clinical trials. The mechanisms of intrinsic and acquired resistance to SERDs remain to be fully elucidated.

We conducted a large-scale lentiviral open reading frame (ORF) screen to identify genes whose overexpression confers drug resistance to either fulvestrant or GDC-810 in the ER+ breast cancer cell line T47D. The lentivral ORF expression library used in this study consists of 16,544 barcoded ORFs, including 2,767 ORFs with mutations. The initial screen yielded 72 genes resulting in resistance to fulvestrant and 85 genes resulting in resistance to GDC-0810, with 44 genes overlapping. The top ranked-genes included multiple genes belonging to the PI3K/Akt, ERbB/HER, and FGF/FGFR pathways as well as genes involved in cell cycle progression.

Fibroblast growth factor receptor 1 (FGFR1) amplifications are frequently observed in patients with ER+ breast cancer, and have previously been implicated in resistance to endocrine therapies. Several FGFs (FGF3, FGF6, FGF10, and FGF22) were among the top-ranked resistance genes for both fulvestrant and GDC-0810, suggesting that activation of the FGFR signaling pathway may render cells resistant to fulvestrant and GDC-810. In the presence of FGF2, overexpression of FGFR1 in ER+ breast cancer cells resulted in resistance to both fulvestrant and GDC-0810. The ability of an FGFR inhibitor to overcome FGFR-mediated resistance to SERDs is being tested. Additional potential resistance genes identified in the ORF screen are also being validated.

In summary, a whole-genome functional resistance screen has identified several candidate genes and pathways that may cause resistance to fulvestrant and GDC-810. Several of these candidates, such as FGFR1, are also found in patients who develop resistance to SERDs, suggesting rational combination therapies to overcome or preempt SERD resistance.

Citation Format: Mao P, Quartey Q, Cohen O, Piccioni F, Wagle N. A large-scale functional screen to identify resistance mechanisms to selective estrogen receptor degraders fulvestrant and GDC-810 in ER+ breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-03-08.

SPARC (secreted protein acidic and rich in cysteine) knockdown protects mice from acute liver injury by reducing vascular endothelial cell damage

Secreted protein, acidic and rich in cysteine (SPARC) is involved in many biological process including liver fibrogenesis, but its role in acute liver damage is unknown. To examine the role of SPARC in acute liver injury, we used SPARC knock-out (SPARC(-/-)) mice. Two models of acute liver damage were used: concanavalin A (Con A) and the agonistic anti-CD95 antibody Jo2. SPARC expression levels were analyzed in liver samples from patients with acute-on-chronic alcoholic hepatitis (AH). SPARC expression is increased on acute-on-chronic AH patients. Knockdown of SPARC decreased hepatic damage in the two models of liver injury. SPARC(-/-) mice showed a marked reduction in Con A-induced necroinflammation. Infiltration by CD4+ T cells, expression of tumor necrosis factor-α and interleukin-6 and apoptosis were attenuated in SPARC(-/-) mice. Sinusoidal endothelial cell monolayer was preserved and was less activated in Con A-treated SPARC(-/-) mice. SPARC knockdown reduced Con A-induced autophagy of cultured human microvascular endothelial cells (HMEC-1). Hepatic transcriptome analysis revealed several gene networks that may have a role in the attenuated liver damaged found in Con A-treated SPARC(-/-) mice. SPARC has a significant role in the development of Con A-induced severe liver injury. These results suggest that SPARC could represent a therapeutic target in acute liver injury.

NMR metabolic profiling of transgenic maize with the Cry1Ab gene

The metabolic profiles of seeds from the transgenic maize variety 33P67 and of the corresponding traditional variety were investigated using one- and two-dimensional NMR techniques. The transgenic variety carries a functional Cry1A(b) gene, which confers to the plant the ability to produce Bt insect toxin. About 40 water-soluble metabolites in the maize seed extracts were identified, providing a more complete (1)H and (13)C NMR assignment with respect to the assignment reported in the literature. In particular ethanol, lactic acid, citric acid, lysine, arginine, glycine-betaine, raffinose, trehalose, alpha-galactose, and adenine were identified for the first time in the (1)H NMR spectrum of maize seeds extracts. The (1)H spectra of transgenic and nontransgenic seed maize samples turned out to be conservative, showing the same signals and therefore the same metabolites. However, a higher concentration of ethanol, citric acid, glycine-betaine, trehalose, as well as of another compound not yet completely identified, was observed in the transgenic extracts than in nontransgenic samples. So, it was possible to discriminate between transgenic and nontransgenic metabolic profilings through the use of an appropriate statistical analysis.

Management of anesthesia in awake craniotomy

The awake craniotomy technique was originally introduced for the surgical treatment of epilepsy and has subsequently been used in patients undergoing surgical management of supratentorial tumors, arteriovenous malformation, deep brain stimulation, and mycotic aneurysms near critical brain regions. This surgical approach aims to maximize lesion resection while sparing important areas of the brain (motor, somatosensory, and language areas). Awake craniotomy offers great advantages with respect to patient outcome. In this type of procedure, the anesthetist's goal is to make the operation safe and effective and reduce the psychophysical distress of the patient. Many authors have described different anesthetic care protocols for awake craniotomy based on monitored or general anesthesia; however, there is still no consensus as to the best anesthetic technique. The most commonly used drugs for awake craniotomies are propofol and remifentanil, but dexmedetomidine is beginning to be used more commonly outside of Europe. Personal experience, careful planning, and attention to detail are the basis for obtaining good awake craniotomy

RESULTS

Additional studies are necessary in order to optimize the procedure, reduce complications, and improve patient tolerance. The aim of this review is to present a thorough report of the literature, with particular attention to neuro-oncology surgery.

Metabolic alterations in cultured mouse fibroblasts induced by an inhibitor of the tyrosine kinase receptor Fibroblast Growth Factor Receptor 1

Proton nuclear magnetic resonance (NMR) spectroscopy was used to identify and quantify the metabolites present in cultured mouse fibroblast cells 3T6 in their native state and after treatment with PD166866, an inhibitor of the fibroblast growth factor receptor. Cell extracts were prepared according to the Bligh-Dyer protocol which prevents artifacts deriving from the chemical demolition of macromolecules. Also the growth medium was subjected to the same extraction procedure. The NMR approach made possible the identification and quantification of about 40 different metabolites at nanomoles/mg of protein level: the biological relevance of the variation of some metabolite levels is discussed. Our experimental procedure offers a prospective method for the evaluation of variations of the metabolic profile deriving from different biochemical treatments of these cells.

Tacrine derivatives-acetylcholinesterase interaction: 1H NMR relaxation study

Two acetylcholinesterase (AChE) inhibitors structurally related to Tacrine, 6-methoxytacrine (1a) and 9-heptylamino-6-methoxytacrine (1b), and their interaction with Electrophorus Electricus AChE were investigated. The complete assignment of the 1H and 13C NMR spectra of 1a and 1b was performed by mono-dimensional and homo- and hetero-correlated two-dimensional NMR experiments. This study was undertaken to elucidate the interaction modes between AChE and 1a and 1b in solution, using NMR. The interaction between the two inhibitors and AChE was studied by the analysis of the motional parameters non-selective and selective spin-lattice relaxation times, thereby allowing the motional state of 1a and 1b, both free and bound with AChE, to be defined. The relaxation data pointed out the ligands molecular moiety most involved in the binding with AChE. The relevant ligand/enzyme interaction constants were also evaluated for both compounds and resulted to be 859 and 5412M(-1) for 1a and1b, respectively.

Metabolic response to exercise

At the beginning, the survival of humans was strictly related to their physical capacity. There was the need to resist predators and to provide food and water for life. Achieving these goals required a prompt and efficient energy system capable of sustaining either high intensity or maintaining prolonged physical activity. Energy for skeletal muscle contraction is supplied by anaerobic and aerobic metabolic pathways. The former can allow short bursts of intense physical activity (60-90 sec) and utilizes as energetic source the phosphocreatine shuttle and anaerobic glycolysis. The aerobic system is the most efficient ATP source for skeletal muscle. The oxidative phosporylation of carbohydrates, fats and, to a minor extent, proteins, can sustain physical activity for many hours. Carbohydrates are the most efficient fuel for working muscle and their contribution to total fuel oxidation is positively related to the intensity of exercise. The first metabolic pathways of carbohydrate metabolism to be involved are skeletal muscle glycogenolysis and glycolysis. Later circulating glucose, formed through activated gluconeogenesis, becomes an important energetic source. Among glucose metabolites, lactate plays a primary role as either direct or indirect (gluconeogenesis) energy source for contracting skeletal muscle. Fat oxidation plays a primary role during either low-moderate intensity exercise or protracted physical activity (over 90-120 min). Severe muscle glycogen depletion results in increased rates of muscle proteolysis and branched chain amino acid oxidation. Endurance training ameliorates physical performance by improving cardiopulmonary efficiency and optimizing skeletal muscle supply and oxidation of substrates.

Diabetes and exercise

Physical activity has acute and chronic effects on glucose, lipid and protein metabolism. Long-term effects of regular exercise are particularly advantageous for Type 2 diabetic patients. Regular aerobic exercise reduces visceral fat mass and body weight without decreasing lean body mass, ameliorates insulin sensitivity, glucose and BP control, lipid profile and reduces the cardiovascular risk. For these reasons, regular aerobic physical activity must be considered as an essential component of the cure of Type 2 diabetes mellitus. In this regard, individual behavioral strategies have been documented to be effective in motivating sedentary Type 2 diabetic subjects to the adoption and the maintenance of regular physical activity. In Type 1 diabetic subjects, the lack of the physiological inhibition of insulin secretion during exercise results in a potential risk of hypoglycemia. On the other hand, exercise-induced activation of counter-regulatory hormones might trigger an acute metabolic derangement in severe insulin-deficient subjects. Thus, diabetic patients, before starting exercise sessions, must be carefully educated about the consequences of physical activity on their blood glucose and the appropriate modifications of diet and insulin therapy.

Androgen 5-alpha-reductase type 2 is highly expressed and active in rat spinal cord motor neurones

Spinal cord motoneurones express high levels of androgen receptor. However, in responsive tissue, the effects of testosterone is often mediated by the more potent androgenic derivative 5-alpha-dihydrotestosterone (DHT). This compound is formed in androgen target cells by the enzyme 5-alpha-reductase. Two isoforms of the 5-alpha-reductase, with limited degree of homology, have been cloned, type 1 and type 2. The low affinity-constitutive type 1 isoenzyme is widely distributed in the body; the high affinity-androgen regulated 5-alpha-reductase type 2 is confined to androgen-dependent structures and shows a peculiar pH optimum at acidic values. We have previously shown that high levels of 5-alpha-reductase activity are detectable in rat spinal cord. Here, using reverse transcriptase-polymerase chain reaction, we show that both isoforms are expressed in the whole spinal cord of the rat. The enzymatic pH optimum measured in immortalized spinal cord motoneurones (NSC34) is typical of the type 2 isoenzyme. Using in situ hybridization technique, we found that 5-alpha-reductase type 2 is confined to the motoneuronal cells of the anterior horns of the rat spinal cord, the cells that also are known to express high levels of androgen receptor. Because of the close association of androgen receptor and 5-alpha alpha-reductase type 2, motoneuronal cells should be considered as target cells for androgens.

Enhanced TNF alpha and oxidative stress in patients with heart failure: effect of TNF alpha on platelet O2- production

Experimental studies have suggested that TNF alpha, a pro-inflammatory cytokine, may contribute to the deterioration of cardiovascular function through various mechanisms, including the generation of reactive oxygen species. It has not yet been demonstrated whether TNF alpha has prooxidant activity in patients with heart failure, and what the mechanism eventually resulting in this effect are. We analyzed 42 patients (38 men and 4 women, aged 26 to 74 years) with heart failure, secondary to idiopathic dilated cardiomyopathy (n=21), coronary artery disease (n=15), and valve disease (n=6), and 20 controls (18 men and 2 women, aged 49 to 67 years). Ten patients were in class I, 9 in class II, 15 in class III and 8 in class IV according to NYHA Classification. Blood samples were obtained from each patient to evaluate basal and collagen-induced platelet O(2)(-) production, and plasma TNF alpha. In vivo results showed increased platelet O(2)(-) production and plasma TNF alpha levels in NYHA class III-IV compared with that in controls or in NYHA I-II (p<0,001); platelet O(2)(-) production correlated significantly (R=0,6; p<0,01) with TNF alpha plasma levels. In vitro studies showed TNF alpha dose-dependently (5-40 pg/ml) induced platelet O(2)(-) production, and that this effect was significantly inhibited by its specific inhibitor, WP9QY (1 microM); aspirin (100 microM), AACOCF(3), a specific PLA(2) inhibitor (14 microM), and DPI, an inhibitor of NADPH oxidase, significantly inhibited TNF alpha-mediated platelet O(2)(-) production. This study suggests that in patients with heart failure, enhanced platelet O(2)(-) production is mediated by TNF alpha via activation of arachidonic acid and NADPH oxidase pathways.

Polyglutamine tract expansion of the androgen receptor in a motoneuronal model of spinal and bulbar muscular atrophy

Spinobulbar muscular atrophy (SBMA) is a late-onset disorder characterized by progressive muscle loss, degeneration of motoneurons in the spinal cord and brainstem, and partial androgen insensitivity. SBMA is directly correlated with the expansion of CAG repeats encoding a polyglutamine tract (polyQ) of extended length. The identification of polyQ expansion in SBMA led to the discovery of an entire class of neurodegenerative disorders. In fact, at least eight different diseases, including Huntington's disease, share a common molecular mechanism involving an expansion of a polyQ tract within different proteins. The elongated polyQ tract causes a toxic gain of function in the mutant protein and is associated with the formation of intracellular aggregates, whose pathogenetic role has not been fully established yet. Our observations in a motoneuron cell line (NSC34), indicate that the expression of the androgen receptor (AR) carrying the elongated polyQ tract (AR-Q48) has a toxic effect in aggregate-independent manner. In fact, in basal condition, AR-Q48 shows a cytoplasmic diffuse distribution, yet it reduces the viability of transfected NSC34. In contrast, testosterone treatment, while inducing aggregation of the mutant AR, also increases cell viability. Aggregates in NSC34 are localized mainly in the perinuclear region and occasionally in the neuropil, whereas no nuclear aggregate has ever been found. Further observations of the minor subset of cells showing neuropil aggregates, reveal an alteration of the neurite morphology, suggesting a different role of the two types of cytoplasmic aggregates.

5Alpha-reductase type 2 and androgen receptor expression in gonadotropin releasing hormone GT1-1 cells

Gonadal steroids are potent modulators of gonadotropin releasing hormone (GnRH) secretion, and androgen binding sites and 5alpha-reductase activity have been found in the immortalized GnRH secreting cell line GT1-1, suggesting the existence of a direct androgenic control of GnRH dynamics. Two isoforms of the 5alpha-reductase have been cloned with very different biochemical/functional properties: 5alpha-reductase type 1 (widely distributed in the body) and 5alpha-reductase type 2 (confined in androgen target structures). We have analysed whether, in GT1-1, androgen binding sites are linked to "classical" androgen receptor, and which 5alpha-reductase isoform is active. Reverse transcriptase-polymerase chain reaction analysis showed that the mRNAs coding for androgen receptor and for the two 5alpha-reductase isoforms are all expressed in GT1-1 cells. However, the 5alpha-reductase enzymatic reaction showed a peak of activity at a narrow pH around 5.5, the optimum for the 5alpha-reductase type 2. The affinity for testosterone, of the enzyme present in GT1-1 cells, was very similar to that observed for the recombinant type 2 isozyme expressed in yeasts. The data indicate that GT1-1 cells (i) express a "classical" androgen receptor and (ii) contain the 5alpha-reductase type 2 isoform, a specific marker of androgen-responsiveness.