Electronic and structural properties of Möbius boron-nitride and carbon nanobelts

For the development of nanofilters and nanosensors, we wish to know the impact of size on their geometric, electronic, and thermal stabilities. Using the semiempirical tight binding method as implemented in the xTB program, we characterized Möbius boron-nitride and carbon-based nanobelts with different sizes and compared them to each other and to normal nanobelts. The calculated properties include the infrared spectra, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), the energy gap, the chemical potential, and the molecular hardness. The agreement between the peak positions from theoretical infrared spectra compared with experimental ones for all systems validates the methodology that we used. Our findings show that for the boron-nitride-based nanobelts, the calculated properties have an opposite monotonic relationship with the size of the systems, whereas for the carbon-based nanobelts, the properties show the same monotonic relationship for both types of nanobelts. Also, the torsion presented on the Möbius nanobelts, in the case of boron-nitride, induced an inhomogeneous surface distribution for the HOMO orbitals. High-temperature molecular dynamics also allowed us to contrast carbon-based systems with boron-nitride systems at various temperatures. In all cases, the properties vary with the increase in size of the nanobelts, indicating that it is possible to choose the desired values by changing the size and type of the systems. This work has many implications for future studies, for example our results show that carbon-based nanobelts did not break as we increased the temperature, whereas boron-nitride nanobelts had a rupture temperature that varied with their size; this is a meaningful result that can be tested when the use of more accurate simulation methods become practical for such systems in the future.

Cellular assays combined with metabolomics highlight the dual face of phenolics: From high permeability to morphological cell damage

The Caco-2 cellular permeability of phenolic aqueous extracts from blackcurrant press cake (BC), Norway spruce bark (NS), scots pine bark (SP), and sea buckthorn leaves (SB) was evaluated by combining high-resolution mass spectrometry and atomic force microscopy. Besides, Caco-2 and HepG2 cells allowed the study of intracellular oxidative stress assessed in both apical and basolateral domains. Overall, BC and NS showed the highest total phenolic contents, 4.38 and 3.76 µg/mL, respectively. Multivariate statistics discriminated NS and BC from SP and SB extracts because of their phenolic profile. Polyphenols were classified as highly permeable, thus suggesting their potentially high bioavailability through the gastrointestinal tract. All the phenolic subclasses showed efflux ratio values < 1, except for BC flavonols, flavan-3-ols, and stilbenes. Regarding cellular damage, NS and BC extracts, when acting on the basolateral cellular side, caused epithelial leakage and morphological shape cell damage on Caco-2 cells associated with ROS production.

Targeting notch signaling pathway in breast cancer stem cells through drug repurposing approach

Breast cancer is recognized globally as one of the leading causes of malignant morbidity. It is a heterogeneous disease that accounts for 30 percent of all women diagnosed with cancer. To bring an anti-cancer drug from the bench to the bedside is an expensive and time-consuming process. The drug repurposing approach targets new enemies (new diseases) with old weapons (known drugs). The present study identified an FDA-approved drug targeting the γ-secretase complex involved in the Notch signaling pathway in breast cancer stem cells (BCSCs). A literature survey and in-silico study identified Venetoclax as a γ-secretase inhibitor (GSI) from 1615 FDA-approved drug compounds. In-silico docking potential of Venetoclax was better than the standard γ-secretase inhibitor RO4929097. Also, the molecular dynamics simulations of 200 ns confirmed the stability of the Venetoclax-γ-secretase complex. These findings suggest that the use of Venetoclax represents a potential γ-secretase inhibitor in breast cancer stem cells. Eventually, the in vitro and clinical evaluation will be needed to confirm the potential chemopreventive and treatment effects of Venetoclax against breast cancer and breast cancer stem cells. Venetoclax appeared as the most promising drug of the 1615 FDA-approved drugs. Our in-silico findings suggest that Venetoclax may act as a γ-secretase inhibitor against the Notch signaling pathway in breast cancer stem cells.

Subtractive sequence analysis aided druggable targets mining in Burkholderia cepacia complex and finding inhibitors through bioinformatics approach

Burkholderia cepacia complex (BCC) is a group of gram-negative bacteria composed of at least 20 different species that cause diseases in plants, animals as well as humans (cystic fibrosis and airway infection). Here, we analyzed the proteomic data of 47 BCC strains by classifying them in three groups. Phylogenetic analyses were performed followed by individual core region identification for each group. Comparative analysis of the three individual core protein fractions resulted in 1766 ortholog/proteins. Non-human homologous proteins from the core region gave 1680 proteins. Essential protein analyses reduced the target list to 37 proteins, which were further compared to a closely related out-group, Burkholderia gladioli ATCC 10,248 strain, resulting in 21 proteins. 3D structure modeling, validation, and druggability step gave six targets that were subjected to further target prioritization parameters which ultimately resulted in two BCC targets. A library of 12,000 ZINC drug-like compounds was screened, where only the top hits were selected for docking orientations. These included ZINC01405842 (against Chorismate synthase aroC) and ZINC06055530 (against Bifunctional N-acetylglucosamine-1-phosphate uridyltransferase/Glucosamine-1-phosphate acetyltransferase glmU). Finally, dynamics simulation (200 ns) was performed for each ligand-receptor complex, followed by ADMET profiling. Of these targets, details of their applicability as drug targets have not yet been elucidated experimentally, hence making our predictions novel and it is suggested that further wet-lab experimentations should be conducted to test the identified BCC targets and ZINC scaffolds to inhibit them.

Möbius carbon nanobelts interacting with heavy metal nanoclusters

CONTEXT

The interaction between carbon nanostructures and heavy metal clusters is of great interest due to their potential applications as sensors and filters to remove the former from environment. In this work, we investigated the interaction between two types of carbon nanobelts (Möbius-type nanobelt and simple nanobelt) and nickel, cadmium, and lead nanoclusters. Our aim was to determine how both systems interact which would shed light on the potential applications of the carbon nanostructures as pollutant removal and detecting devices.

METHODS

To investigate the interaction between carbon nanostructures and heavy metal nanoclusters, we utilized the semiempirical tight binding framework provided by xTB software with the GFN2-xTB Hamiltonian. We performed calculations to determine the best interaction site, lowest energy geometries, complexes stability (using molecular dynamics at 298K), binding energy, and electronic properties. We also carried out a topological study to investigate the nature and intensity of the bonds formed between the metal nanoclusters and the nanobelts. Our results demonstrate that heavy metal nanoclusters have a favorable binding affinity towards both nanobelts, with the Möbius-type nanobelt having a stronger interaction. Additionally, our calculations reveal that the nickel nanocluster has the lowest binding energy, displaying the greatest charge transfer with the nanobelts, which was nearly twice that of the cadmium and lead nanoclusters. Our combined results lead to the conclusion that the nickel nanoclusters are chemisorbed, whereas cadmium and lead nanoclusters are physisorbed in both nanobelts. These findings have significant implications for the development of sensor and filtering devices based on carbon and heavy metal nanoclusters.

Genomic landscape of the emerging XDR Salmonella Typhi for mining druggable targets clpP, hisH, folP and gpmI and screening of novel TCM inhibitors, molecular docking and simulation analyses

Typhoid fever is transmitted by ingestion of polluted water, contaminated food, and stool of typhoid-infected individuals, mostly in developing countries with poor hygienic environments. To find novel therapeutic targets and inhibitors, We employed a subtractive genomics strategy towards Salmonella Typhi and the complete genomes of eight strains were primarily subjected to the EDGAR tool to predict the core genome (n = 3207). Human non-homology (n = 2450) was followed by essential genes identification (n = 37). The STRING database predicted maximum protein-protein interactions, followed by cellular localization. The virulent/immunogenic ability of predicted genes were checked to differentiate drug and vaccine targets. Furthermore, the 3D models of the identified putative proteins encoded by the respective genes were constructed and subjected to druggability analyses where only "highly druggable" proteins were selected for molecular docking and simulation analyses. The putative targets ATP-dependent CLP protease proteolytic subunit, Imidazole glycerol phosphate synthase hisH, 7,8-dihydropteroate synthase folP and 2,3-bisphosphoglycerate-independent phosphoglycerate mutase gpmI were screened against a drug-like library (n = 12,000) and top hits were selected based on H-bonds, RMSD and energy scores. Finally, the ADMET properties for novel inhibitors ZINC19340748, ZINC09319798, ZINC00494142, ZINC32918650 were optimized followed by binding free energy (MM/PBSA) calculation for ligand-receptor complexes. The findings of this work are expected to aid in expediting the identification of novel protein targets and inhibitors in combating typhoid Salmonellosis, in addition to the already existing therapies.

Attacking the SARS-CoV-2 replication machinery with the Pathogen Box’s molecules

Introduction:

The world is currently facing a pandemic caused by the new coronavirus disease 2019 (COVID-19), caused by the SARS-CoV-2 virus. Viral transcription and replication are within the fundamental processes of any virus. They allow the synthesis of genetic material and the consequent multiplication of the virus to infect other cells or organisms.

Methods:

The most important protein in SARS-CoV-2 is the RNA polymerase (RdRp or nsp12), responsible for both processes. The structure of this protein (PDB ID: 6M71) was used as a target in the application of computational strategies for drug search, like virtual screening and molecular docking. Here, Pathogen Box database of chemical compounds was used together with Remdesivir, Beclabuvir, and Sofosbuvir drugs as potential inhibitors of nsp12.

Results:

The results showed a Top10 potential target inhibitor, with binding energy (∆G) higher than those of the positive controls, of which TCMDC-134153 and TCMDC-135052, both with ∆G = −7.53 kcal/mol, present interactions with three important residues of the nsp12 catalytic site.

Conclusion:

These proposed ligands would be used for subsequent validation by molecular dynamics, where they can be considered as drugs for the development of effective treatments against this new pandemic.

Impedance Spectroscopy as a Tool for the Detection of Occlusal Noncavitated Carious Lesions

A total 302 teeth (148 molars and 154 premolars) corresponding to 152 patients aged ≥18 years were evaluated for caries using the ICDAS (International Caries Detection and Assessment System), fluorescence (DD, DIAGNOdent) and electrical impedance (IMS, CarieScan PRO) systems. Fissurotomy and intraoral radiographs were used as the gold standard. Accordingly, 27.5% (n=84) of the teeth were classified as sound, while 26.9% (n=81) had enamel involvement and 45.6% (n=138) presented carious lesions reaching the dentin. Sensitivity (Se), specificity (Sp), and the area under the curve (AUC) were, respectively, 90.7%, 87.8%, and 0.954 (IMS); 92.4%, 92.7%, and 0.954 (DD); and 79.0%, 72.3%, and 0.756 (ICDAS). With regard to Se and Sp, there were significant differences between ICDAS and DD (p<0.001) and between ICDAS and IMS (p=0.01), but not between IMS and DD (p=0.07). In relation to AUC, there were significant differences between ICDAS and DD (p<0.001), and between ICDAS and IMS (p<0.001), but not between IMS and DD (p>0.05). The correlations between fissurotomy and each method were 88.7% (IMS), 89.7% (DD), and 77.1% (ICDAS). Within the limitations of this study, clinically, the electrical system is not useful for differentiating between sound teeth and truly incipient caries lesions by itself. The fluorescence or electrical systems are recommended with the ICDAS to detect carious lesions in their early stages.

Triamcinolone as a potential inhibitor of SARS-CoV-2 main protease and cytokine storm: An in-silico study

Background:

An ongoing global public health concern is the emerging COVID-19 pandemic triggered by acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Mpro, a main protease of SARS-CoV-2, has been established as a potential drug target because of its direct role in viral replication and ability to infiltrate multiple host pathways. COVID-19, Cytokine storm, Main protease, Molecular docking, MD simulation, Protease inhibitor, Triamcinolone

Objective:

This research aims to classify new therapeutic drug candidates who may be repositioned for COVID-19 therapeutics.

Methods:

We have taken similar drug compounds of Dexamethasone and targeted the main protease of SARS-CoV-2 (Mpro) along with the key molecules involved in the 'cytokine storm.' Further, we did MD simulations and calculated molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA) on the active site of the main protease of SARS-CoV-2 (Mpro) and TNF-α, IL-6, & IL-1β to explore the binding affinity and stability.

Result:

Based on our study outcome, Triamcinolone emerged as the most promising inhibitor of the main protease of SARS-CoV-2 (Mpro) and the cytokine storm molecules, i.e., TNF-α, IL-6, and IL-1β.

Conclusion:

This research investigates the repositioning of COVID-19 drugs as a new therapeutic application.

Glycosylation is key for enhancing drug recognition into spike glycoprotein of SARS-CoV-2

The emergence of COVID-19 caused by SARS-CoV-2 and its spread since 2019 represents the major public health problem worldwide nowadays, which has generated a high number of infections and deaths. The spike protein (S protein) is the most studied protein of SARS-CoV-2, and key to host-cell entry through ACE2 receptor. This protein presents a large pattern of glycosylations with important roles in immunity and infection mechanisms. Therefore, understanding key aspects of the molecular mechanisms of these structures, during drug recognition in SARS-CoV-2, may contribute to therapeutic alternatives. In this work, we explored the impact of glycosylations on the drug recognition on two domains of the S protein, the receptor-binding domain (RBD) and the N-terminal domain (NTD) through molecular dynamics simulations and computational biophysics analysis. Our results show that glycosylations in the S protein induce structural stability and changes in rigidity/flexibility related to the number of glycosylations in the structure. These structural changes are important for its biological activity as well as the correct interaction of ligands in the RBD and NTD regions. Additionally, we evidenced a roto-translation phenomenon in the interaction of the ligand with RBD in the absence of glycosylation, which disappears due to the influence of glycosylation and the convergence of metastable states in RBM. Similarly, glycosylations in NTD promote an induced fit phenomenon, which is not observed in the absence of glycosylations; this process is decisive for the activity of the ligand at the cryptic site. Altogether, these results provide an explanation of glycosylation relevance in biophysical properties and drug recognition to S protein of SARS-CoV-2, which must be considered in the rational drug development and virtual screening targeting S protein.

Repurposing potential of Ayurvedic medicinal plants derived active principles against SARS-CoV-2 associated target proteins revealed by molecular docking, molecular dynamics and MM-PBSA studies

All the plants and their secondary metabolites used in the present study were obtained from Ayurveda, with historical roots in the Indian subcontinent. The selected secondary metabolites have been experimentally validated and reported as potent antiviral agents against genetically-close human viruses. The plants have also been used as a folk medicine to treat cold, cough, asthma, bronchitis, and severe acute respiratory syndrome in India and across the globe since time immemorial. The present study aimed to assess the repurposing possibility of potent antiviral compounds with SARS-CoV-2 target proteins and also with host-specific receptor and activator protease that facilitates the viral entry into the host body. Molecular docking (MDc) was performed to study molecular affinities of antiviral compounds with aforesaid target proteins. The top-scoring conformations identified through docking analysis were further validated by 100 ns molecular dynamic (MD) simulation run. The stability of the conformation was studied in detail by investigating the binding free energy using MM-PBSA method. Finally, the binding affinities of all the compounds were also compared with a reference ligand, remdesivir, against the target protein RdRp. Additionally, pharmacophore features, 3D structure alignment of potent compounds and Bayesian machine learning model were also used to support the MDc and MD simulation. Overall, the study emphasized that curcumin possesses a strong binding ability with host-specific receptors, furin and ACE2. In contrast, gingerol has shown strong interactions with spike protein, and RdRp and quercetin with main protease (M^pro) of SARS-CoV-2. In fact, all these target proteins play an essential role in mediating viral replication, and therefore, compounds targeting aforesaid target proteins are expected to block the viral replication and transcription. Overall, gingerol, curcumin and quercetin own multitarget binding ability that can be used alone or in combination to enhance therapeutic efficacy against COVID-19. The obtained results encourage further in vitro and in vivo investigations and also support the traditional use of antiviral plants preventively.

Novel multi-epitope protein containing conserved epitopes from different Leishmania species as potential vaccine candidate: Integrated immunoinformatics and molecular dynamics approach

Leishmaniosis, caused by intracellular parasites of the genus Leishmania, has become a serious public health problem around the world, and for which there are currently extensive limitations. In this work, a theoretical model was proposed for the development of a multi-epitope vaccine. The protein GP63 of the parasite was selected for epitopes prediction, due to its important biological role for the infection process and abundance. IEDB tools were used to determine epitopes B and T in Leishmania braziliensis; besides, other conserved epitopes in three species were selected. To improve immunogenicity, 50S ribosomal protein L7 / L12 (ID: P9WHE3) was used as a domain of adjuvant in the assembly process. The folding arrangement of the vaccine was obtained through homologous modeling multi-template with MODELLER v9.21, and a Ramachandran plot analysis was done. Furthermore, physicochemical properties were described with the ProtParam tool and secondary structure prediction combining GOR-IV and SOPMA tools. Finally, a molecular dynamics simulation (50 ns) was performed to establish flexibility and conformational changes. The analysis of the results indicates high conservancy in the epitopes predicted among the four species. Moreover, Ramachandran plot, physicochemical parameters, and secondary structure prediction suggest a stable conformation of the vaccine, after a minimum conformational change that was evaluated with the free energy landscape. The conformational change does not drive any substantial change for epitope exposition on the surface. The vaccine proposed could be tested experimentally to guide new approaches in the development of pan-vaccines; vaccines with regions conserved in multiple species.

PQM130, a Novel Feruloyl-Donepezil Hybrid Compound, Effectively Ameliorates the Cognitive Impairments and Pathology in a Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) is the most frequent type of dementia in older people. The complex nature of AD calls for the development of multitarget agents addressing key pathogenic processes. Donepezil, an acetylcholinesterase inhibitor, is a first-line acetylcholinesterase inhibitor used for the treatment of AD. Although several studies have demonstrated the symptomatic efficacy of donepezil treatment in AD patients, the possible effects of donepezil on the AD process are not yet known. In this study, a novel feruloyl-donepezil hybrid compound (PQM130) was synthesized and evaluated as a multitarget drug candidate against the neurotoxicity induced by Aβ_1-42 oligomer (AβO) injection in mice. Interestingly, PQM130 had already shown anti-inflammatory activity in different in vivo models and neuroprotective activity in human neuronal cells. The intracerebroventricular (i.c.v.) injection of AβO in mice caused the increase of memory impairment, oxidative stress, neurodegeneration, and neuroinflammation. Instead, PQM130 (0.5-1 mg/kg) treatment after the i.c.v. AβO injection reduced oxidative damage and neuroinflammation and induced cell survival and protein synthesis through the modulation of glycogen synthase kinase 3β (GSK3β) and extracellular signal-regulated kinases (ERK1/2). Moreover, PQM130 increased brain plasticity and protected mice against the decline in spatial cognition. Even more interesting is that PQM130 modulated different pathways compared to donepezil, and it is much more effective in counteracting AβO damage. Therefore, our findings highlighted that PQM130 is a potent multi-functional agent against AD and could act as a promising neuroprotective compound for anti-AD drug development.

Cylindrical hot refractory anode vacuum arc (CHRAVA)

We present a study of a novel vacuum arc deposition system composed of a water-cooled aluminum cathode and a hot refractory anode. The plasma of the arc system was diagnosed using a cylindrical electrostatic probe. It was found that the mean electron temperature was ∼2 eV, the plasma density could be varied in the range of 0.5-6 × 10¹⁶ m^-3, and the ion flux was between 0.06 and 0.35 A m^-2. Optical emission spectroscopy measurements showed the presence of emission lines corresponding to Al i and Al ii. The characterization of the coatings showed that the deposition rate varied from 0.8 to 4 nm/s and the surface roughness (Ra) of the films was as low as 25 nm. We demonstrated that it was possible to deposit films with low macroparticle densities, overcoming the principal disadvantage of the vacuum arc process. Measurements of the arc voltage and current were performed as a function of time and the applied magnetic field. The anode temperature was measured using a pyrometer through a ZnS window as a function of time and arc current, and the maximum value was 1800 °C with heating rates of up to 110 °C/s.

Memristive behaviour of Si-Al oxynitride thin films: the role of oxygen and nitrogen vacancies in the electroforming process

The resistive switching properties of silicon-aluminium oxynitride (SiAlON) based devices have been studied. Electrical transport mechanisms in both resistance states were determined, exhibiting an ohmic behaviour at low resistance and a defect-related Poole-Frenkel mechanism at high resistance. Nevertheless, some features of the Al top-electrode are generated during the initial electroforming, suggesting some material modifications. An in-depth microscopic study at the nanoscale has been performed after the electroforming process, by acquiring scanning electron microscopy and transmission electron microscopy images. The direct observation of the devices confirmed features on the top electrode with bubble-like appearance, as well as some precipitates within the SiAlON. Chemical analysis by electron energy loss spectroscopy has demonstrated that there is an out-diffusion of oxygen and nitrogen ions from the SiAlON layer towards the electrode, thus forming silicon-rich paths within the dielectric layer and indicating vacancy change to be the main mechanism in the resistive switching.

Design, synthesis and pharmacological evaluation of N-benzyl-piperidinyl-aryl-acylhydrazone derivatives as donepezil hybrids: Discovery of novel multi-target anti-alzheimer prototype drug candidates

A new series of sixteen multifunctional N-benzyl-piperidine-aryl-acylhydrazones hybrid derivatives was synthesized and evaluated for multi-target activities related to Alzheimer's disease (AD). The molecular hybridization approach was based on the combination, in a single molecule, of the pharmacophoric N-benzyl-piperidine subunit of donepezil, the substituted hydroxy-piperidine fragment of the AChE inhibitor LASSBio-767, and an acylhydrazone linker, a privileged structure present in a number of synthetic aryl- and aryl-acylhydrazone derivatives with significant AChE and anti-inflammatory activities. Among them, compounds 4c, 4d, 4g and 4j presented the best AChE inhibitory activities, but only compounds 4c and 4g exhibited concurrent anti-inflammatory activity in vitro and in vivo, against amyloid beta oligomer (AβO) induced neuroinflammation. Compound 4c also showed the best in vitro and in vivo neuroprotective effects against AβO-induced neurodegeneration. In addition, compound 4c showed a similar binding mode to donepezil in both acetylated and free forms of AChE enzyme in molecular docking studies and did not show relevant toxic effects on in vitro and in vivo assays, with good predicted ADME parameters in silico. Overall, all these results highlighted compound 4c as a promising and innovative multi-target drug prototype candidate for AD treatment.

De Novo Design of New Inhibitor of Mutated Tyrosine-Kinase for the Myeloid Leukemia Treatment

BACKGROUND

Chronic myelogenous leukemia is associated with hematopoietic stem cells that are manifested primarily with expansion myelopoiesis. It is the first cancer directly associated with a genetic abnormality. Specifically, it is associated to a particular cytogenetic abnormality, known as Philadelphia chromosome (Ph), which results from a fusion between part of the BCR ("breakpoint cluster region") gene from chromosome 22 and the Abelson (ABL) gene on chromosome 9 and leads to the formation a new gene leukemia-specific, the BCR-ABL. Since 2011, there are several tyrosine-kinase inhibitors in the market. Due to mutations in the tyrosine-kinase domain, these inhibitors are becoming less effective in the leukemia treatment, and then there is a need for new more effective inhibitors.

METHODS

The aim of this work is to obtain new tyrosine-kinase inhibitors using in silico tools like de novo drug design, docking and absorption, distribution, metabolism and excretion studies.

RESULTS

Using the proposed methodology, an initial library of more than 6000 molecules was obtained. This library was then filtered out using the Tanimoto metric to compute the similarity between the molecules using as parameter the 2D linear hashed fingerprint with a 64-bit address space. The resulting library was then used to run docking studies together with the reference market drugs and their ADME (absorption, distribution, metabolism and excretion) properties were determined. Three compounds with better inhibition capacity and better ADME properties that the commercially available not only for the wild form of enzymes under study but also to its mutated forms were obtained.

CONCLUSION

The fragment based drug design method used in this work turns to be a good alternative to create new drugs that can control this neoplasm. Based on the calculated GScore, the de novo designed molecules have better inhibitor capacity than the tyrosine-kinase inhibitors most used in the market. These molecules shown strong potential to become drugs capable to inhibit all mutations, mainly the T315I mutation, now the leading cause of deaths due to the difficulty of inhibitors to control it.

Order–disorder phase transition induced by proton transfer in a co-crystal of 2,4-dichlorobenzoic acid and trimethylamine N-oxide

A crystalline binary adduct between trimethylamine N-oxide and 2,4-dichlorobenzoic acid was obtained. The molecular system was thermally characterized, subsequently demonstrating an order–disorder transition.

Structure-property relationships for Eu doped TiO2 thin films grown by a laser assisted technique from colloidal sols

Highly photoluminescent Eu doped TiO₂ layers prepared by laser-based technique from colloidal sols.

First-principles calculations of nickel, cadmium, and lead adsorption on a single-walled (10,0) carbon nanotube

The adsorption of Ni, Cd, and Pb on a zigzag (10, 0) carbon nanotube (CNT) surface was investigated using density functional theory. Binding energy calculations were performed, and the results indicated that the three metals are stably adsorbed on the nanotube surface. Moreover, the results showed that Cd is physisorbed whereas Ni and Pb are chemisorbed. Our studies show that the electronic properties of the CNT are modified by the chemisorption mechanism (Ni and Pb). After Ni and Pb adsorption, the nanotube changes from being a semiconductor to a metallic conductor. The nanotube remains semiconductive upon Cd physisorption, although a decrease in the band gap is observed. Also, Ni or Pb adsorption triggers a change in the magnetism of the nanotube through the induction of spin polarization. Not only can these results of our calculations be used to explain the adsorption mechanisms of these heavy metals on the CNT, but they are also useful for evaluating the potential of carbon nanotubes (CNTs) to act as filters and sensors of such metals.

Structural Bioinformatics Approach of Cyclin-Dependent Kinases 1 and 3 Complexed with Inhibitors

The cyclin-dependent kinases or CDKs participate in the regulation of both the cell progression cycle and the RNA polymerase-II transcription cycle. In several human tumours deregulation of CDK-related mechanisms have been detected, e.g., overexpression of cyclins or deletion of genes encoding for CKIs. Regarding these observations, CDKs came up to be interesting targets for elaboration of novel antitumour drugs. Based on the importance of the CDKs, this research aimed to describe, to characterize and to compare the molecular models of CDK1 and CDK3. Since the structures of human CDK1 and CDK3 are unavailable in the Protein Data Bank -PDB, homology models were created based on the CDK2 as the template, once they share a substantial identity. The structural studies of the CDK1 and CDK3 biding sites were conducted by molecular docking with 15 different CDK inhibitors previously identified to CDK2. This study allowed the understanding of the structure of the complexes between CDK1/ CDK3 with inhibitors. The knowledge of their structural features mainly the biding sites might be useful to discovery and rationalization of drug design process.

[Insulin resistance and metabolic syndrome in first-degree relatives of patients with NIDDM]

BACKGROUND

Relatives of type 2 diabetes mellitus (DM2) patients present or can develop the plurimetabolic syndrome (MS). Insulin sensitivity determination could be useful to detect relatives with higher risk.

PATIENTS AND METHODS

Insulin sensitivity (IS) and MS in 106 first degree relatives of DM2 and 52 control subjects, matched for age, sex and body mass index (BMI). Insulin sensitivity was evaluated by the HOMA method. Insulin sensitivity was classified as high, middle or low according to the percentiles 33 and 66 observed in the control group. MS was diagnosed if hyperglycemia, hypertension, hypertriglyceridemia and overweight (two or more) were present.

RESULTS

Insulin sensitivity was lower in relatives (36.3 vs 51.8%; p = 0.0001). Relatives with lower insulin sensitivity (n = 56) have higher BMI (29.2 vs 25.6 kg/m2), higher systolic (128 vs 116 mmHg) and diastolic (80 vs 74) blood pressure, hyperglycemia (5.7 vs 5.1 mmol/l), hyperinsulinemia (116 vs 59 pmol/l) and hypertriglyceridemia (1.4 vs 1.0 mmol/l) when compared with the remainder relatives (n = 50). Age, sex, waist/hip ratio and cholesterol level were similar in both groups. 23 relatives have MS (20 of them with low insulin sensitivity, relative risk = 8.7; 95% confidence interval 2.4-31.6). In multiple logistic regression analysis, only age and IS have a significant value to predict the presence of MS.

CONCLUSIONS

Relatives of DM2 are insulin-resistant and present a high prevalence of MS. Both insulin sensitivity and MS are highly correlated. Insulin sensitivity evaluation using a simple methodology like HOMA can be useful in the selection of relatives at higher risk of MS.

Beta-cell dysfunction in first-degree relatives of patients with non-insulin-dependent diabetes mellitus

To analyse the relationship between age, glucose tolerance, beta-cell function, and insulin sensitivity in preclinical states of non-insulin-dependent (Type 2) diabetes mellitus (NIDDM), we have done a cross-sectional, age-stratified analysis of 86 non-diabetic first-degree relatives of NIDDM patients and 49 controls with similar age, sex, and BMI. A 5 mg kg ideal body weight-1 min-1 for 60 min of continuous infusion of glucose with model assessment (CIGMA) of serum glucose and C-peptide values at the end of the infusion was used to determine glucose tolerance and beta-cell function. Insulin sensitivity was estimated by modelling basal serum glucose and insulin values. Relatives and controls were divided into tertiles on the basis of age. Relatives had higher basal (5.3 vs 5 mmol l-1, p = 0.02) and achieved serum glucose (9.1 vs 8.4 mmol l-1, p = 0.01), lower beta-cell function (128 vs 145%, p = 0.007), and lower insulin sensitivity (37 vs 43%, p = 0.002). Beta-cell function declined with age in relatives (from 139% in young subjects to 134% in intermediate subjects and to 111% in older subjects, p = 0.002) and this decline was associated with an increase in basal serum glucose (from 5.1 to 5.3 and to 5.7 mmol l-1, p = 0.000) and achieved glucose (from 8.3 to 9.1 and to 9.3 mmol l-1, p = 0.038), without significant changes in insulin sensitivity. These trends were observed even after the exclusion of subjects with mild glucose intolerance. We conclude that both beta-cell dysfunction and insulin resistance are present in first-degree relatives of NIDDM. The progression of beta-cell dysfunction and glucose intolerance with age suggests that beta-cell dysfunction is the key factor in the apparition and progression of the disease.

Ketoacidosis at diagnosis is predictive of lower residual beta-cell function and poor metabolic control in type 1 diabetes

To determine the factors at diagnosis predictive of changes in residual beta-cell function and metabolic control in Type 1 diabetes, 125 patients older than 7 years of age consecutively diagnosed between March 1986 and June 1991 were followed prospectively for two years. The effect of age, gender and the presence of ketoacidosis (DKA) and islet-cell antibodies (ICA) on beta-cell function, metabolic control and insulin requirements were studied by multivariate analysis of variance (repeated measurements over time) in 90 patients who completed follow-up. DKA had an independent negative effect on residual beta-cell function over time (p = 0.001). ICA-positive patients had lower residual beta-cell function at the end of follow-up (p < 0.05), but overall differences were not significant. DKA and younger age had an independent negative influence on metabolic control (p < 0.05) and insulin requirements (p < 0.001) over time. It is concluded that residual beta-cell function in Type 1 diabetic patients two years after diagnosis was independently influenced by DKA and ICA at diagnosis. Moreover, DKA and age influenced metabolic control and could thus be used to predict those patients with rapidly deteriorating metabolic control who might benefit from a more intensive therapeutic approach.

Increased prothrombin fragment 1 + 2 and D-dimer in first-degree relatives of type 2 diabetic patients. Prethrombotic state in relatives of type 2 diabetic patients

To evaluate whether or not activated coagulation is present in the preclinical phases of type 2 diabetes mellitus, we studied 46 non-diabetic first-degree relatives of type 2 diabetic patients and 21 matched controls with no family history of diabetes. We determined the plasma levels of prothrombin fragment 1 + 2, D-dimer, fibrinogen, plasminogen activator inhibitor type 1, tissue plasminogen activator, von Willebrand factor and coagulation factors VII and VIII. Glucose tolerance, beta-cell function and insulin sensitivity were assessed in all subjects by a continuous glucose infusion of 5 mg.kg ideal body weight-1.min-1 for 60 min with model assessment of glucose, insulin and C-peptide values. Plasma levels of prothrombin fragment 1 + 2 (median 1.24 vs 0.68 nmol.l-1; P = 0.0001) and D-dimer (331 vs 254 micrograms.l-1 UEF; P = 0.018) were higher in relatives, without significant differences in the other haemostatic variables. Relatives showed higher fasting (5.5 vs 4.9 mmol.l-1, P = 0.004) and post-infusion (9.3 vs 8.3 mmol.l-1, P = 0.02) serum glucose, no differences in insulin or C-peptide levels, lower beta-cell function (122% vs 147%; P = 0.02) and no significant differences in insulin sensitivity. Fifteen relatives were glucose-intolerant and had lower beta-cell function and insulin sensitivity than glucose-tolerant relatives. Both subsets of relatives exhibited higher levels of prothrombin fragment 1 + 2 and D-dimer than control subjects. Thus, first-degree relatives of type 2 diabetic patients present an activated coagulation, even in the absence of minor degrees of glucose intolerance. These abnormalities can play a role in the pathogenesis of cardiovascular diseases frequently seen at diagnosis of type 2 diabetes.

[Basal cortisol and ACTH in the immediate postoperative period in ACTH-producing hypophyseal adenomas]

BACKGROUND

Evaluate the usefulness of basal cortisol and ACTH during the immediate postoperative period following hypophyseal surgery, as early indicators of remission in patients with Cushing's disease.

METHODS

Nine patients with Cushing's disease and on whom selective transphenoidal adenomectomy was performed were included in the study. Basal cortisol and ACTH levels were compared the first week after surgery, with definitive results being obtained after a month's time during which basal cortisol levels below 165 nmol/l indicated patients cured of Cushing's disease.

RESULTS

Cortisol levels determined post-op, in five patients in remission, were found to be lower than those in patients who were not cured (63 +/- 55.8 versus 606 +/- 267 nmol/l, p < 0.01). However, ACTH levels were not lower. All the patients in remission had initial cortisol levels lower than 182 nmol/l, whereas the uncured patients had levels higher than 404 nmol/l. There was a correlation between cortisol measured in the first week and the definitive value (r = 0.81, p < 0.01).

CONCLUSION

Cortisol in the immediate postoperative period following hypophyseal surgery is a good indicator of definitive adrenocorticotropic function and permits the identification of those patients in remission.

[Value of basal cortisol and ACTH in the immediate postoperative period of hypophyseal surgery in non-ACTH secretory adenomas]

BACKGROUND

The aim of this study was to evaluate the usefulness of basal cortisol and ACTH in the immediate postoperative period of pituitary surgery as indicators of definitive adrenocorticotropin function.

METHODS

Twenty-one patients with pituitary, non producers of ACTH, adenomas, three microadenomas and 18 macroadenomas treated by adenomectomy by a trans-sphenoidal route were respectively studied. The basal cortisol and ACTH were compared in the first week following surgery with the definitive results obtained after one month by dynamic tests (stimulation with ACTH or insulin hypoglycemia).

RESULTS

The six patients with secondary adrenal failure (AF) in the definitive evaluation had lower basal cortisol in the immediate postoperative period than the patients with AF (135.3 +/- 225.3 nmol/l versus 473.6 +/- 147.2 nmol/l; p < 0.05). The values of ACTH were also lower (2.3 +/- 1.6 nmol/l versus 4.8 +/- 3.4; p < 0.05). In all the patients with definitive AF except one, the basal cortisol in the first week was lower than 130 nmol/l and in those who did not present AF it was greater than 220 nmol/l.

CONCLUSIONS

In the immediate postoperative period after pituitary surgery cortisol is a good indicator of definitive adrenocorticotropin function. This parameter may identify the patients requiring posterior substitutive treatment.

Nonoperative management of splenic injuries

The traditional management of splenic trauma has undergone major revision in recent years. Given the physiological importance of the spleen, certain controversy has arisen regarding the most appropriate method of managing this type of trauma. Nonoperative therapy in children has proven to be successful not only in the case of kidney lesions but also for splenic lesions. Nonoperative management carried out in the authors' hospital on a group of 56 patients (49 adults and seven children over the age of 7 years) has proved successful in 37 cases. The success of this technique requires a well-formulated protocol, diagnostic methods (ultrasound and computed tomography), rigorous patient control in the emergency room during the initial phase (first 48 hours), the availability of a medical team if surgical intervention becomes necessary (persistent or recurrent hemorrhage), and complementary measures which facilitate the cicatrization of the splenic injury (bed rest, antibiotic therapy).