Impact of Aromatic Stacking on Glycoside Reactivity: Balancing CH/π and Cation/π Interactions for the Stabilization of Glycosyl-Oxocarbenium Ions

Carbohydrate/aromatic stacking represents a recurring key motif for the molecular recognition of glycosides, either by protein binding domains, enzymes, or synthetic receptors. Interestingly, it has been proposed that aromatic residues might also assist in the formation/cleavage of glycosidic bonds by stabilizing positively charged oxocarbenium-like intermediates/transition states through cation/π interactions. While the significance of aromatic stacking on glycoside recognition is well stablished, its impact on the reactivity of glycosyl donors is yet to be explored. Herein, we report the first experimental study on this relevant topic. Our strategy is based on the design, synthesis, and reactivity evaluation of a large number of model systems, comprising a wide range of glycosidic donor/aromatic complexes. Different stacking geometries and dynamic features, anomeric leaving groups, sugar configurations, and reaction conditions have been explicitly considered. The obtained results underline the opposing influence exerted by van der Waals and Coulombic forces on the reactivity of the carbohydrate/aromatic complex: depending on the outcome of this balance, aromatic platforms can indeed exert a variety of effects, stretching from reaction inhibition all the way to rate enhancements. Although aromatic/glycosyl cation contacts are highly dynamic, the conclusions of our study suggest that aromatic assistance to glycosylation processes must indeed be feasible, with far reaching implications for enzyme engineering and organocatalysis.

Impact of sensor-augmented pump therapy with predictive low-glucose management on hypoglycemia and glycemic control in patients with type 1 diabetes mellitus: 1-year follow-up

AIMS

To describe real-life experience with sensor-augmented pump therapy with predictive low-glucose management (SAPT-PLGM), in terms of hypoglycemia and glycemic control after one year of follow-up in T1D patients with hypoglycemia as the main indication of therapy.

METHODS

Retrospective cohort study under real life conditions. Baseline and one-year follow-up variables of glycemic control, hypoglycemia and glycemic variability were compared.

RESULTS

Fifty patients were included, 31 on prior treatment with SAPT with low-glucose suspend (LGS) feature and 19 on multiple dose insulin injections (MDI). Mean HbA1c decreased in the MDI group (8.24%-7.08%; p = 0.0001). HbA1c change was not significant in the SAPT-LGS group. Area under the curve (AUC) below 70 mg/dl improved in both SAPT-LGS and MDI groups while AUC, %time and events below 54 mg/dl decreased in SAPT-LGS group. Glycemic variability improved in the MDI group. Less patients presented severe hypoglycemia with SAPT-PLGM in both groups, however the change was non-significant.

CONCLUSIONS

Under real life conditions, SAPT-PLGM reduced metrics of hypoglycemia in patients previously treaded with MDI and SAPT-LGS without deteriorating glycemic control in SAPT-LGS patients, while improving it in patients treated with MDI.

Progression of excitation-contraction coupling defects in doxorubicin cardiotoxicity

Cardiac failure is a common complication in cancer survivors treated with anthracyclines. Here we followed up cardiac function and excitation-contraction (EC) coupling in an in vivo doxorubicin (Dox) treated mice model (iv, total dose of 10 mg/Kg divided once every three days). Cardiac function was evaluated by echocardiography at 2, 6 and 15 weeks after the last injection. While normal at 2 and 6 weeks, ejection fraction was significantly reduced at 15 weeks. In order to evaluate the underlying mechanisms, we measured [Ca²⁺]_i transients by confocal microscopy and action potentials (AP) by patch-clamp technique in cardiomyocytes isolated at these times. Three phases were observed: 1/depression and slowing of the [Ca²⁺]_i transients at 2 weeks after treatment, with occurrence of proarrhythmogenic Ca²⁺ waves, 2/compensatory state at 6 weeks, and 3/depression on [Ca²⁺]_i transients and cell contraction at 15 weeks, concomitant with in-vivo defects. These [Ca²⁺]_i transient alterations were observed without cellular hypertrophy or AP prolongation and mirrored the sarcoplasmic reticulum (SR) Ca²⁺ load variations. At the molecular level, this was associated with a decrease in the sarcoplasmic reticulum Ca²⁺ ATPase (SERCA2a) expression and enhanced RyR2 phosphorylation at the protein kinase A (PKA, pS2808) site (2 and 15 weeks). RyR2 phosphorylation at the Ca²⁺/calmodulin dependent protein kinase II (CaMKII, pS2814) site was enhanced only at 2 weeks, coinciding with the higher incidence of proarrhythmogenic Ca²⁺ waves. Our study highlighted, for the first time, the progression of Dox treatment-induced alterations in Ca²⁺ handling and identified key components of the underlying Dox cardiotoxicity. These findings should be helpful to understand the early-, intermediate-, and late- cardiotoxicity already recorded in clinic in order to prevent or treat at the subclinical level.

Different Indexes of Glycemic Variability as Identifiers of Patients with Risk of Hypoglycemia in Type 2 Diabetes Mellitus

INTRODUCTION

Recent publications frequently introduce new indexes to measure glycemic variability (GV), quality of glycemic control, or glycemic risk; however, there is a lack of evidence supporting the use of one particular parameter, especially in clinical practice.

METHODS

A cohort of type 2 diabetes mellitus (T2DM) patients in ambulatory care were followed using continuous glucose monitoring sensors (CGM). Mean glucose (MG), standard deviation, coefficient of variation (CV), interquartile range, CONGA1, 2, and 4, MAGE, M value, J index, high blood glucose index, and low blood glucose index (LBGI) were estimated. Hypoglycemia incidence (<54 mg/dl) was calculated. Area under the curve (AUC) was determined for different indexes as identifiers of patients with risk of hypoglycemia (IRH). Optimal cutoff thresholds were determined from analysis of the receiver operating characteristic curves.

RESULTS

CGM data for 657 days from 140 T2DM patients (4.69 average days per patient) were analyzed. Hypoglycemia was present in 50 patients with 144 hypoglycemic events in total (incidence rate of 0.22 events per patient/day). In the multivariate analysis, both CV (OR 1.20, 95% CI 1.12-1.28, P < .001) and LBGI (OR 4.83, 95% CI 2.41-9.71, P < .001) were shown to have a statistically significant association with hypoglycemia. The highest AUC were for CV (0.84; 95% CI 0.77-0.91) and LBGI (0.95; 95% CI 0.92-0.98). The optimal cutoff threshold for CV as IRH was 34%, and 3.4 for LBGI.

CONCLUSION

This analysis shows that CV can be recommended as the preferred parameter of GV to be used in clinical practice for T2DM patients. LBGI is the preferred IRH between glycemic risk indexes.

Reduction of glycemic variability with Degludec insulin in patients with unstable diabetes

Introduction

Degludec (IDeg) is an ultralong-acting insulin, with stable pharmacodynamic profile which leads to lower fluctuations in glucose levels. The effect of IDeg has not been specifically assessed in patients with unstable diabetes, defined as increased glycemic variability (GV).

Methods

A prospective before-after pilot study was conducted, including patients managed at Hospital Universitario San Ignacio in Bogotá, Colombia. The impact of the switch from a Glargine or Detemir insulin to a basal insulin regimen with IDeg for 12 weeks on GV measured by continuous glucose monitoring, on A1c levels, and on the incidence of episodes of global and nocturnal hypoglycemia was assessed in a group of patients with (coefficient of variation >34%) or without increased basal GV using a Generalised Estimating Equation (GEE) analysis.

Results

60 patients with basal bolus therapy and history of hypoglycemia were included. 18 patients had High GV (HGV). In this group a significant reduction of 11.1% of CV (95% CI: 6.3, 15.9, p = 0.01) was found. GEE analysis confirmed a higher impact over time on patients with HGV (p < 0.001). The percentage of patients with at least 1 episode of hypoglycemia decreased from 66.6% to 22.2% (p = 0.02) and from 37.14% to 5.71% (p < 0.01) for global and nocturnal hypoglycemia, respectively. Changes were not significant in patients with low GV. A reduction of A1c was observed in both groups (p < 0.001).

Conclusions

The results suggest that treatment with IDeg reduces GV, A1c levels and the incidence of global and nocturnal hypoglycemia events in patients with HGV, but not in patients with low GV.

Sorcin ablation plus β-adrenergic stimulation generate an arrhythmogenic substrate in mouse ventricular myocytes

Sorcin, a penta-EF hand Ca²⁺-binding protein expressed in cardiomyocytes, is known to interact with ryanodine receptors and other Ca²⁺ regulatory proteins. To investigate sorcin's influence on cardiac excitation-contraction coupling and its role in the development of cardiac malfunctions, we generated a sorcin knockout (KO) mouse model. Sorcin KO mice presented ventricular arrhythmia and sudden death when challenged by acute stress induced by isoproterenol plus caffeine. Chronic stress, which was induced by transverse aortic constriction, significantly decreased the survival rate of sorcin KO mice. Under isoproterenol stimulation, spontaneous Ca²⁺ release events were frequently observed in sorcin KO cardiomyocytes. Sorcin KO hearts of adult, but not young mice developed overexpression of L-type Ca²⁺ channel and Na⁺-Ca²⁺ exchanger, which enhanced I_Ca and I_NCX. Consequently, spontaneous Ca²⁺ release events in sorcin KO cardiomyocytes were more likely to induce arrhythmogenic delayed afterdepolarizations. Our study demonstrates sorcin deficiency may trigger cardiac ventricular arrhythmias due to Ca²⁺ disturbances, and evidences the critical role of sorcin in maintaining Ca²⁺ homeostasis, especially during the adrenergic response of the heart.

Solvent-Sensitive Emitting Urea-Bridged bis-BODIPYs: Ready Access by a One-Pot Tandem Staudinger/Aza-Wittig Ureation

Herein we describe the synthesis, and computationally aided photophysical characterization of a new set of urea-bridged bis-BODIPY derivatives. These new dyads are efficiently obtained by a one-pot tandem Staudinger/aza-Wittig ureation protocol, from easily accessible meso-phenyl ortho-azidomethyl BODIPYs. These symmetric bis-BODIPYs outstand by a high absorption probability and excellent fluorescence and laser emission in less polar media. Nevertheless, this emission ability decreases in more polar media, which is ascribed to a light-induced charge-transfer from the urea spacer to the dipyrrin core, a process that can be modulated by appropriate changes in the substitution pattern of the BODIPY core. Furthermore, this ureation protocol can also be employed for the direct conjugation of our BODIPY-azides to amine-containing compounds, thus providing access to fluorescent non-symmetric ureas.

Mosaic trisomy 8 detected by fibroblasts cultured of skin

INTRODUCTION

Mosaic trisomy 8 or "Warkany's Syndrome" is a chromosomopathy with an estimated prevalance of 1:25,000 to 1:50,000, whose clinical presentation has a wide phenotypic variability.

CASE DESCRIPTION

Patient aged 14 years old with antecedents of global retardation of development, moderate cognitive deficit and hypothyroidism of possible congenital origin.

CLINICAL FINDINGS

Physical examination revealed palpebral ptosis, small corneas and corectopia, hypoplasia of the upper maxilla and prognathism, dental crowding, high-arched palate, anomalies of the extremities such as digitalization of the thumbs, clinodactyly and bilateral shortening of the fifth finger, shortening of the right femur, columnar deviation and linear brown blotches that followed Blaschko's lines. Cerebral nuclear magnetic resonance revealed type 1 Chiari's malformation and ventriculomegaly. Although the karyotype was normal in peripheral blood (46,XY), based on the finding of cutaneous mosaicism the lesions were biopsied and cytogenetic analysis demonstrated mosaic trisomy 8: mos 47,XY,+8[7]/46,XY[93].

CLINICAL RELEVANCE

Trisomy 8 is clinically presented as a mosaic, universal cases being unfailingly lethal. In this particular case, cutaneous lesions identified the mosaic in tissue, although the karyotype was normal in peripheral blood. The cutaneous mosaicism represented by brown linear blotches which follow Blaschko's lines is a clinical finding that has not previously been described in Warkany's syndrome.

3.0Tesla magnetic resonance angiography (MRA) for comprehensive renal evaluation of living renal donors: pilot study with computerized tomography angiography (CTA) comparison

PURPOSE

Most living related donor (LRD) kidneys are harvested laparoscopically. Renal vascular anatomy helps determine donor suitability for laparoscopic nephrectomy. Computed tomography angiography (CTA) is the current gold standard for preoperative imaging; magnetic resonance angiography (MRA) offers advantages including lack of ionizing radiation and lower incidence of contrast reactions. We evaluated 3.0T MRA for assessing renal anatomy of LRDs.

MATERIALS AND METHODS

Thirty consecutive LRDs underwent CTA followed by 3.0T MRA. Data points included number and branching of vessels, incidental findings, and urothelial opacification. Studies were individually evaluated by three readers blinded to patient data. Studies were reevaluated in consensus with discrepancies revealed, and final consensus results were labeled "truth".

RESULTS

Compared with consensus "truth", both computed tomography (CT) and magnetic resonance imaging were highly accurate for assessment of arterial and venous anatomy, although CT was superior for detection of late venous confluence as well as detection of renal stones. Both modalities were comparable in opacification of lower ureters and bladder; MRA underperformed CTA for opacification of upper urinary tracts.

CONCLUSIONS

3.0T MRA enabled excellent detection of comprehensive renal anatomy compared to CTA in LRDs.

Numerical and clinical precision of continuous glucose monitoring in Colombian patients treated with insulin infusion pump with automated suspension in hypoglycemia

OBJECTIVE

Insulin pump therapy associated with continuous glucose monitoring has shown a positive clinical impact on diabetes control and reduction of hypoglycemia episodes. There are descriptions of the performance of this device in other populations, but its precision and accuracy in Colombia and Latin America are unknown, especially in the routine outpatient setting.

METHODS

Data from 33 type 1 and type 2 diabetes patients with sensor-augmented pump therapy with threshold suspend automation, MiniMed Paradigm® Veo™ (Medtronic, Northridge, California), managed at Hospital Universitario San Ignacio (Bogotá, Colombia) and receiving outpatient treatment, were analyzed. Simultaneous data from continuous glucose monitoring and capillary blood glucose were compared, and their precision and accuracy were calculating with different methods, including Clarke error grid.

RESULTS

Analyses included 2,262 continuous glucose monitoring -reference paired glucose values. A mean absolute relative difference of 20.1% was found for all measurements, with a value higher than 23% for glucose levels ≤75mg/dL. Global compliance with the ISO criteria was 64.9%. It was higher for values >75mg/dl (68.3%, 1,308 of 1,916 readings), than for those ≤ 75mg/dl (49.4%, 171 of 346 readings). Clinical accuracy, as assessed by the Clarke error grid, showed that 91.77% of data were within the A and B zones (75.6% in hypoglycemia).

CONCLUSIONS

A good numerical accuracy was found for continuous glucose monitoring in normo and hyperglycemia situations, with low precision in hypoglycemia. The clinical accuracy of the device was adequate, with no significant safety concerns for patients.

A thorough experimental study of CH/π interactions in water: quantitative structure-stability relationships for carbohydrate/aromatic complexes

CH/π interactions play a key role in a large variety of molecular recognition processes of biological relevance. However, their origins and structural determinants in water remain poorly understood. In order to improve our comprehension of these important interaction modes, we have performed a quantitative experimental analysis of a large data set comprising 117 chemically diverse carbohydrate/aromatic stacking complexes, prepared through a dynamic combinatorial approach recently developed by our group. The obtained free energies provide a detailed picture of the structure-stability relationships that govern the association process, opening the door to the rational design of improved carbohydrate-based ligands or carbohydrate receptors. Moreover, this experimental data set, supported by quantum mechanical calculations, has contributed to the understanding of the main driving forces that promote complex formation, underlining the key role played by coulombic and solvophobic forces on the stabilization of these complexes. This represents the most quantitative and extensive experimental study reported so far for CH/π complexes in water.

Continuous Glucose Monitoring Versus Capillary Point-of-Care Testing for Inpatient Glycemic Control in Type 2 Diabetes Patients Hospitalized in the General Ward and Treated With a Basal Bolus Insulin Regimen

BACKGROUND

Continuous glucose monitoring (CGM) may improve the management of patients with type 2 diabetes hospitalized in the general ward by facilitating the detection of hyper- and hypoglycemic episodes. However, the lack of data on the accuracy and safety of CGM have limited its application.

METHODS

A prospective pilot study was conducted including 38 patients hospitalized in the general ward with a known diagnosis of type 2 diabetes mellitus (DM) and hyperglycemic individuals without a history of DM with a blood sugar of 140-400 mg on admission treated with a basal bolus insulin regimen. Inpatient glycemic control and the incidence of hypoglycemic episodes were compared between detection by CGM of interstitial fluid for up to 6 days and point-of-care (POC) capillary blood glucose monitoring performed pre- and postprandially, before bedtime and at 3 am.

RESULTS

No differences in average daily glucose levels were observed between CGM and POC (176.2 ± 33.9 vs 176.6 ± 33.7 mg/dl, P = .828). However, CGM detected a higher number of hypoglycemic episodes than POC (55 vs 12, P < .01). Glucose measurements were clinically valid, with 91.9% of patients falling within the Clarke error grid A and B zones.

CONCLUSIONS

Our preliminary results indicate that the use of CGM in type 2 patients hospitalized in the general ward provides accurate estimation of blood sugar levels and is more effective than POC for the detection of hypoglycemic episodes and asymptomatic hypoglycemia.

Chemokines and relapses in childhood acute lymphoblastic leukemia: A role in migration and in resistance to antileukemic drugs

We studied whether chemokines may have a role in relapses in childhood acute lymphoblastic leukemia (ALL). We compared the levels of chemokine receptors in marrow samples from 82 children with ALL at diagnosis versus 15 at relapses, and quantified the levels of chemokines in central system fluid (CSF) samples. The functional role of specific chemokines was studied in vitro and in vivo. The expression of some chemokine receptors was upregulated upon leukemic relapse, both in B- and in T-ALL, and in cases of medullary and extramedullary involvement. CXCL10 induced chemotaxis in leukemic cell lines and in primary leukemic cells, depending upon the levels of CXCR3 expression. CXCL10 specifically diminished chemotherapy-induced apoptosis on ALL cells expressing CXCR3, partially inhibiting caspase activation and maintaining the levels of the antiapoptotic protein Bcl-2. Finally, immunodeficient mice engrafted with CXCR3-expressing human leukemic cells showed decreased infiltration of marrow, spleen, and CNS after receiving a CXCR3-antagonist molecule. CXCR3 signaling in ALL may have a dual function: chemotactic for the localisation of leukemic blasts in specific niches, and it may also confer resistance to chemotherapy, enhancing the chances for relapses.