Antibacterial effects of nanopillar surfaces are mediated by cell impedance, penetration and induction of oxidative stress

Some insects, such as dragonflies, have evolved nanoprotrusions on their wings that rupture bacteria on contact. This has inspired the design of antibacterial implant surfaces with insect-wing mimetic nanopillars made of synthetic materials. Here, we characterise the physiological and morphological effects of mimetic titanium nanopillars on bacteria. The nanopillars induce deformation and penetration of the Gram-positive and Gram-negative bacterial cell envelope, but do not rupture or lyse bacteria. They can also inhibit bacterial cell division, and trigger production of reactive oxygen species and increased abundance of oxidative stress proteins. Our results indicate that nanopillars' antibacterial activities may be mediated by oxidative stress, and do not necessarily require bacterial lysis.

P962 The Remodeling Index risk stratifies patients with hypertensive left ventricular hypertrophy

Funding Acknowledgements

National Medical Research Council

BACKGROUND

Hypertensive left ventricular hypertrophy (LVH) is associated with increased cardiovascular events. The authors previously developed the Remodeling Index (RI) that incorporated LV volume and wall-thickness in a single measure of advanced hypertrophy in hypertensive patients.

PURPOSE

This study examined the mechanisms and prognostic potential of the RI in reference with current LVH classifications.

METHODS

Cardiovascular magnetic resonance (CMR) was performed in 400 asymptomatic hypertensive patients. The newly derived RI ([(EDV)^1/3]/t; where EDV is LV end-diastolic volume and t is the maximal wall thickness across 16 myocardial segments) stratified hypertensive patients into 3 groups: without LVH, LVH with normal RI (LVH_Normal-RI) and LVH with low RI (LVH_Low-RI). The primary outcome was a composite of all-cause mortality, acute coronary syndromes, strokes and decompensated heart failure.

RESULTS

LVH_Low-RI was associated with increased LV mass index, fibrosis burden, impaired myocardial function and elevated biochemical markers of myocardial injury and wall stress. Over 18.3 ± 7.0 months (601.3 patient-years), patients with LVH_Low-RI had more than a 5-fold increase in adverse events compared to those with LVH_Normal-RI (11.6 events/100patient-years versus 2.0 events/100 patient-years, respectively; log-rank P < 0.001; Figure A). The RI provided incremental prognostic value over and above a model consisting of clinical variables and LVH (P = 0.02). Conversely concentric and eccentric LVH were associated with adverse prognosis (4.5 events/100patient-years versus 6.0 events/100patient-years, respectively; log-rank P = 0.62) that was similar as the natural history of hypertensive LVH (5.1 events/100patient-years).

CONCLUSIONS

The RI provides mechanistic insights and prognostic value that improves risk-stratification of hypertensive LVH.

Abstract P962 Figure.

P1419 Sex-related differences in cardiac remodeling in health and hypertension

Funding Acknowledgements

National Medical Research Council

OnBehalf

National Heart Centre Singapore

BACKGROUND

Adverse cardiac remodelling is associated with worse cardiovascular outcomes. Development of left ventricular hypertrophy (defined as increased myocardial mass) is a complex process mediated by myocardial wall thickening and/or ventricular dilatation. Sex-related differences in the relationship between myocardial mass and wall thickening/ventricular dilatation have not been well-described.

PURPOSE

We examine differences in determinants and patterns of cardiac remodeling between males and females.

METHODS

Comprehensive cardiovascular magnetic resonance imaging was performed in 1006 participants: 316 healthy volunteers (50% males, 46 ± 14 years) and 690 asymptomatic hypertensive patients (60% males, 57 ± 11 years). Myocardial mass, ventricular volumes and maximal myocardial wall thickness (across 16 myocardial segments) were measured using standardized contouring techniques. Clinically relevant variables (age, weight, height, and adiposity) that demonstrated significant univariate association with myocardial mass (P < 0.05) were selected in the multivariable linear regression model using the forward approach.

RESULTS

Increased body weight, lower body fat composition and higher systolic blood pressures were independently associated with increased myocardial mass in healthy volunteers (males and females) and hypertensive females. In hypertensive males, only increased body weight and elevated systolic blood pressure were independently associated with increased myocardial mass.

The association between myocardial mass and ventricular volumes was almost identical between males and females (P = 0.65 for interaction; Figure). Conversely, there was a significant gender-related difference in the association between wall thickness and myocardial mass after adjusting for potential confounders (P < 0.001 for interaction). Concentric remodeling was initially more evident in males; but further with increase, myocardial mass was associated with greater concentric remodeling in females (Figure). Similar results were observed when analyses were performed separately in healthy volunteers and hypertensive patients.

CONCLUSION

There were sex-related differences in concentric remodeling at progressive stages of myocardial hypertrophy that may explain the higher prevalence of heart failure with preserved ejection fraction reported in females.

Abstract P1419 Figure

Features and clinical significance of the ossification centres in the odontoid process based on micro-computed tomography

BACKGROUND

Microscopic structures of the ossification centres of the odontoid process were studied from the micro-computed tomography (CT) images of the axis, and the potential influence of the ossification centres with different microscopic structures on odontoid process fractures was analysed.

MATERIALS AND METHODS

Eighteen odontoid process specimens were randomly collected and scanned by micro-CT. The obtained images were then input into the software for further observation and measurement. Incomplete absorption of the ossification centres in the base was observed, along with the anatomic structure of the regions with incomplete ossification and structural parameters of the trabecular bones.

RESULTS

The microscopic structures of the trabecular bones in the ossification centres in the base of the odontoid process could be clearly visualised from the micro-CT images. Among the 18 odontoid process specimens, 11 specimens were found with incomplete absorption of the ossification centres in the axis, the prevalence reaching up to 61%. Regions with incomplete ossification varied in size and morphology, and their three-dimensional morphology was predominantly oval. Of all structural parameters examined for the trabecular bones, there were only significant differences in the degree of anisotropy between the regions with incomplete absorption of ossification centres and the average vertebral trabecular bones (p < 0.05).

CONCLUSIONS

Incomplete absorption of the ossification centres in the base of the odontoid process is a relatively prevalent condition. The cavitation effect of the trabecular bones may be the primary cause for odontoid process fractures.

Studies of Black Diamond as an antibacterial surface for Gram Negative bacteria: the interplay between chemical and mechanical bactericidal activity

'Black silicon' (bSi) samples with surfaces covered in nanoneedles of length ~5 µm were fabricated using a plasma etching process and then coated with a conformal uniform layer of diamond using hot filament chemical vapour deposition to produce 'black diamond' (bD) nanostructures. The diamond needles were then chemically terminated with H, O, NH2 or F using plasma treatment, and the hydrophilicity of the resulting surfaces were assessed using water droplet contact-angle measurements, and scaled in the order O > H ≈NH2 >F, with the F-terminated surface being superhydrophobic. The effectiveness of these differently terminated bD needles in killing the Gram-negative bacterium E. coli was semi-quantified by Live/Dead staining and fluorescence microscopy, and visualised by environmental scanning electron microscopy. The total number of adhered bacteria was consistent for all the nanostructured bD surfaces at around 50% of the value for the flat diamond control. This, combined with a chemical bactericidal effect of 20-30%, shows that the nanostructured bD surfaces supported significantly fewer viable E. coli than flat surfaces. Moreover, the bD surfaces were particularly effective at preventing the establishment of bacterial aggregates - a precursor to biofilm formation. The percentage of dead bacteria also decreased as a function of hydrophilicity. These results are consistent with a predominantly mechanical mechanism for bacteria death based on the stretching and disruption of the cell membrane, combined with an additional effect from the chemical nature of the surface.

Ion-Pair Selection Method for Pseudotargeted Metabolomics Based on SWATH MS Acquisition and Its Application in Differential Metabolite Discovery of Type 2 Diabetes

The pseudotargeted metabolomics method integrates advantages of nontargeted and targeted analysis because it can acquire data of metabolites in the multireaction monitoring (MRM) mode of mass spectrometry (MS) without needing standards. The key is the ion-pair information collection from samples to be analyzed. It is well-known that sequential windowed acquisition of all theoretical Fragment ion (SWATH) MS mode can acquire MS2 information to a maximum extent. To expediently acquire as many ion-pairs as possible with optimal collision energy (CE), an ion-pair selection approach based on SWATH MS acquisition with variable isolation windows was developed in this study. Initially, nontargeted acquisition of all metabolites information in plasma Standard Reference Material (SRM 1950) was performed by ultra high-performance liquid chromatography (UHPLC)-quadrupole time-of-flight (Q-TOF) MS platform with three CEs. With the help of software tool, the ion-pairs of unique metabolites were gained. Then they were validated in scheduled MRM coupled with UHPLC. After removing false positive, the ion-pairs with an optimal CE was integrated. A total of 1373 unique metabolite ion-pairs were obtained at positive ion mode. And repeatability of the established pseudotargeted approach was evaluated by intraday and interday precision. The results demonstrated the method was stable, reliable, and suitable for metabolomics study. As an application example, alterations of serum metabolites in Type 2 diabetes were investigated by using the established method. This work provides a pseudotargeted ion-pair selection method based on SWATH MS acquisition with the characters of increased metabolite coverage, suitable CE, and convenient processing.

[Analysis of the influential factors of late diagnosis among newly identified HIV/AIDS cases in Anhui Province, 2011-2015]

Objective: To analyze the base situation and influential factors of late diagnosis among newly identified HIV/AIDS cases in Anhui Province from 2011 to 2015. Methods: Database information of the newly identified HIV/AIDS cases in Anhui Province from 2011 to 2015 were downloaded from the National HIV/AIDS Comprehensive Information System of China's disease prevention and control information system. To analyze the data including basic information, sample source, route of HIV transmission, population mobility, venereal disease, death and first CD4 count; and the number of 7 073 cases were classified according to late diagnosis and non-late diagnosis criteria. The Chi-square test and logistic regression analysis were used to analyze the influential factors of HIV late diagnosis. Results: A total of 7 073 newly identified HIV/AIDS cases were analyzed, and the mean age was (38.5±15.0) years. The proportion of late diagnosis in all counted cases was 41.7% (2 949/7 073); from 2011 to 2015, the proportions of late diagnosis were 59.7% (485/812), 46.5% (531/1 141), 42.7% (587/1 376), 36.1% (609/1 686), and 35.8% (737/2 058), respectively. Compared with the 0 to 19 years group, the 40 to 59 years group and over 60 years old group have higher risk of late diagnosis (OR=2.68, 95%CI: 1.94-3.71; OR=2.18, 95%CI: 1.53-3.10, respectively). Compared with the high education group, the illiterate and primary school education group have higher risk of late diagnosis (OR=1.74, 95%CI: 1.36-2.22; OR=1.64, 95%CI: 1.34-2.01, respectively). Compared with other sample sources, medical institutions have higher risk of late diagnosis (OR=2.64, 95%CI: 2.28-3.05). Compared with migrant population, the resident population have higher risk of late diagnosis (OR=1.80, 95%CI: 1.53-2.11). Conclusion: The proportion of late diagnosis among newly identified HIV/AIDS cases in Anhui province was relatively high from 2011 to 2015. The main risk factors of late diagnosis included cases reported by medical institutions, resident population, over 40 years old age group and low education level.

Studies of black silicon and black diamond as materials for antibacterial surfaces

'Black silicon' (bSi) samples with surfaces covered in nanoneedles of varying length, areal density and sharpness, have been fabricated using a plasma etching process. These nanostructures were then coated with a conformal uniform layer of diamond using hot filament chemical vapour deposition to produce 'black diamond' (bD) surfaces. The effectiveness of these bSi and bD surfaces in killing Gram-negative (E. coli) and Gram-positive (S. gordonii) bacteria was investigated by culturing the bacteria on the surfaces for a set time and then measuring the live-to-dead ratio. All the nanostructured surfaces killed E. coli at a significantly higher rate than the respective flat Si or diamond control samples. The length of the needles was found to be less important than their separation, i.e. areal density. This is consistent with a model for mechanical bacteria death based on the stretching and disruption of the cell membrane, enhanced by the cells motility on the surfaces. In contrast, S. gordonii were unaffected by the nanostructured surfaces, possibly due to their smaller size, thicker cell membrane and/or their lack of motility.

Diamond-coated 'black silicon' as a promising material for high-surface-area electrochemical electrodes and antibacterial surfaces

This report describes a method to fabricate high-surface-area boron-doped diamond (BDD) electrodes using so-called 'black silicon' (bSi) as a substrate. This is a synthetic nanostructured material that contains high-aspect-ratio nano-protrusions, such as spikes or needles, on the Si surface produced via plasma etching. We now show that coating a bSi surface composed of 15 μm-high needles conformably with BDD produces a robust electrochemical electrode with high sensitivity and high electroactive area. A clinically relevant demonstration of the efficacy of these electrodes is shown by measuring their sensitivity for detection of dopamine (DA) in the presence of an excess of uric acid (UA). Finally, the nanostructured surface of bSi has recently been found to generate a mechanical bactericidal effect, killing both Gram-negative and Gram-positive bacteria at high rates. We will show that BDD-coated bSi also acts as an effective antibacterial surface, with the added advantage that being diamond-coated it is far more robust and less likely to become damaged than Si.

MicroRNA-338-3p inhibits glucocorticoid-induced osteoclast formation through RANKL targeting

The differentiation deficiencies of osteoclast precursors (pre-OCs) may contribute to osteoporosis. Research on osteoporosis has recently focused on microRNAs (miRNAs) that play crucial roles in pre-OC differentiation. In the current study, we aimed to analyze the expression and function of the glucocorticoid (GC)-associated miRNA-338-3p (miR-338-3p) in osteoclast formation. We found that dexamethasone induced osteoclast differentiation and inhibited miR-338-3p expression. Overexpression of an miR-338-3p mimic in osteoclast precursor cells attenuated GC-induced osteoclast formation and bone resorption, whereas inhibition of miR-338-3p reversed these effects. The expression of the nuclear factor κB ligand RANKL, a potential target gene of miR-338-3p, was inversely correlated with miR-338-3p expression in pre-OCs. Furthermore, we demonstrated that RANKL was directly regulated by miR-338-3p and re-introduction of RANKL reversed the inhibitory effects of miR-338-3p on osteoclast formation and bone resorption. Taken together, these findings demonstrate that miR-338-3p may play a significant role in GC-induced osteoclast differentiation and function by targeting RANKL in osteoclasts.

A genome-wide association study of heat stress-associated SNPs in catfish

Heat tolerance is a complex and economically important trait for catfish genetic breeding programs. With global climate change, it is becoming an increasingly important trait. To better understand the molecular basis of heat stress, a genome-wide association study (GWAS) was carried out using the 250 K catfish SNP array with interspecific backcross progenies, which derived from crossing female channel catfish with male F1 hybrid catfish (female channel catfish × male blue catfish). Three significant associated SNPs were detected by performing an EMMAX approach for GWAS. The SNP located on linkage group 14 explained 12.1% of phenotypical variation. The other two SNPs, located on linkage group 16, explained 11.3 and 11.5% of phenotypical variation respectively. A total of 14 genes with heat stress related functions were detected within the significant associated regions. Among them, five genes-TRAF2, FBXW5, ANAPC2, UBR1 and KLHL29- have known functions in the protein degradation process through the ubiquitination pathway. Other genes related to heat stress include genes involved in protein biosynthesis (PRPF4 and SYNCRIP), protein folding (DNAJC25), molecule and iron transport (SLC25A46 and CLIC5), cytoskeletal reorganization (COL12A1) and energy metabolism (COX7A2, PLCB1 and PLCB4) processes. The results provide fundamental information about genes and pathways that is useful for further investigation into the molecular mechanisms of heat stress. The associated SNPs could be promising candidates for selecting heat-tolerant catfish lines after validating their effects on larger and various catfish populations.

Gankyrin drives malignant transformation of chronic liver damage-mediated fibrosis via the Rac1/JNK pathway

Hepatocarcinogenesis is a complex process involving chronic liver injury, inflammation, unregulated wound healing, subsequent fibrosis and carcinogenesis. To decipher the molecular mechanism underlying transition from chronic liver injury to dysplasia, we investigated the oncogenic role of gankyrin (PSMD10 or p28^GANK) during malignant transformation in a transgenic mouse model. Here, we find that gankyrin increased in patients with cirrhosis. In addition to more severe liver fibrosis and tumorigenesis after DEN plus CCl₄ treatment, hepatocyte-specific gankyrin-overexpressing mice (gankyrin^hep) exhibited malignant transformation from liver fibrosis to tumors even under single CCl₄ administration, whereas wild-type mice merely experienced fibrosis. Consistently, enhanced hepatic injury, severe inflammation and strengthened compensatory proliferation occurred in gankyrin^hep mice during CCl₄ performance. This correlated with augmented expressions of cell cycle-related genes and abnormal activation of Rac1/c-jun N-terminal kinase (JNK). Pharmacological inhibition of the Rac1/JNK pathway attenuated hepatic fibrosis and prevented CCl₄-induced carcinogenesis in gankyrin^hep mice. Together, these findings suggest that gankyrin promotes liver fibrosis/cirrhosis progression into hepatocarcinoma relying on a persistent liver injury and inflammatory microenvironment. Blockade of Rac1/JNK activation impeded gankyrin-mediated hepatocytic malignant transformation, indicating the combined inhibition of gankyrin and Rac1/JNK as a potential prevention mechanism for cirrhosis transition.

Influence of alumina particles in the production of biomimetic composites

AIM

The aim of the work was to evaluate the influence of the filler size and shape in the final architecture of biomimetic composite produced through the freeze casting technique.

METHODS

Different samples of ceramic infiltrated with resin, composed by a different ratio between RonaFlair White Sapphire aluminium oxide powder - EMD Chemicals/Rona Gibbstown, USA (platelet-like morphology and average particle size <16 µm) and Almatis alumina filler ‑ CT3000SG, Almatis, USA (average particle size of 0.8 µm) have been produced. The samples have been then characterized through thermal analysis and calorimetry (Model TG/DT A 6300, Seiko Instruments USA Inc. Torrance, CA, USA), scanning electron microscopy (Phenom-World BV, Eindhoven, The Netherlands), and optical microscope (Nikon Eclipse E600 microscope). Moreover the percentage of shrinkage after the ceramic sintering have been measured through a digital calibre (Mitutoyo USA, Aurora, IL, USA). Four different groups have been considered: Group 1 (10R): 10% RonaFlair- 90% Almitas; Group 2 (20R): 20% RonaFlair- 80% Almitas; Group 3 (40R): 40% RonaFlair- 60% Almitas; Group 4 (60R): 60% RonaFlair- 40% Almitas.

RESULTS

Optical microscope and SEM observations have confirmed that all samples were characterized by a biomimetic hierarchic structure. For what concerning the average thickness of lamellae measured at 4 and 8 mm from the cooling plate, samples 10R were characterized by higher thickness at both levels. The measured parameter indeed decreases with the increment of the percentage of RonaFlair in the slurry composition. On the contrary the distance between lamellae (wavelength), was characterized by an opposite trend. The measurement of the diameters of the samples after the sintering process through a digital calibre has shown that 10R and 20R samples were characterized by a constant shrinkage in all the samples. On the contrary, groups 40R and 60R were distorted and were characterized by a higher diameter at the bottom respect the upper portion of the samples. Indeed these samples were characterized in the bottom by a greater amount of particles, both Almatis than RonaFlair ones. We have supposed that gravity force, during the freeze casting process, tended to push down in the lower layers all heaviest particles and then the lightest ones have occupied the spaces they have left. Consequently in upper layers there were only few particles so during the sintering process were characterized by the higher shrinkage. This phenomenon was limited in samples 10R and 20R because the percentage of greatest particle was so much inferior that their position was not influential.

CONCLUSION

The present study has shown that samples composed by a higher percentage of RonaFlair, were characterized by a higher distortion after sintherization; the cause of this phenomenon could be the different sedimentation process that characterizes particles of different weight and size.

Allelic differences between Europeans and Chinese for CREB1 SNPs and their implications in gene expression regulation, hippocampal structure and function, and bipolar disorder susceptibility

Bipolar disorder (BD) is a polygenic disorder that shares substantial genetic risk factors with major depressive disorder (MDD). Genetic analyses have reported numerous BD susceptibility genes, while some variants, such as single-nucleotide polymorphisms (SNPs) in CACNA1C have been successfully replicated, many others have not and subsequently their effects on the intermediate phenotypes cannot be verified. Here, we studied the MDD-related gene CREB1 in a set of independent BD sample groups of European ancestry (a total of 64,888 subjects) and identified multiple SNPs significantly associated with BD (the most significant being SNP rs6785[A], P=6.32 × 10(-5), odds ratio (OR)=1.090). Risk SNPs were then subjected to further analyses in healthy Europeans for intermediate phenotypes of BD, including hippocampal volume, hippocampal function and cognitive performance. Our results showed that the risk SNPs were significantly associated with hippocampal volume and hippocampal function, with the risk alleles showing a decreased hippocampal volume and diminished activation of the left hippocampus, adding further evidence for their involvement in BD susceptibility. We also found the risk SNPs were strongly associated with CREB1 expression in lymphoblastoid cells (P<0.005) and the prefrontal cortex (P<1.0 × 10(-6)). Remarkably, population genetic analysis indicated that CREB1 displayed striking differences in allele frequencies between continental populations, and the risk alleles were completely absent in East Asian populations. We demonstrated that the regional prevalence of the CREB1 risk alleles in Europeans is likely caused by genetic hitchhiking due to natural selection acting on a nearby gene. Our results suggest that differential population histories due to natural selection on regional populations may lead to genetic heterogeneity of susceptibility to complex diseases, such as BD, and explain inconsistencies in detecting the genetic markers of these diseases among different ethnic populations.

Dipeptidyl peptidase-4 inhibitors as a third-line oral antihyperglycaemic agent in patients with type 2 diabetes mellitus: the impact of ethnicity

Aims. The aim of this study is to examine the efficacy of adding a dipeptidyl peptidase-4 (DPP-4) inhibitor to patients with type 2 diabetes inadequately controlled by metformin and sulphonylurea combination treatment. The response of Asian and non-Asian patients to this regimen was also examined. Methods. The medical and computerized records of 80 patients were examined. These patients had baseline HbA1c levels ranging from 7.0 to 12.5% and had a DPP-4 inhibitor add-on therapy for a minimum period of 12 weeks. The primary endpoint was the change in HbA1c level before and after DPP-4 inhibitor treatment. Results. During oral triple therapy, there was a reduction of HbA1c from 8.3% (7.7-8.9) to 7.2% (6.8-7.6) and 26 patients (32.5%) achieved an HbA1c <7%. Poor baseline glycaemic control, lower BMI, and younger age were associated with a better response, but duration of diabetes and gender did not affect outcome. The HbA1c reduction was not different between Asians and non-Asians group [-1.00% (0.6-1.3) vs -0.90% (0.4-1.6)]. Conclusions. DPP-4 inhibitor as a third-line add-on therapy can achieve significant glycaemic improvement in patients with type 2 diabetes inadequately controlled on the combination of metformin and sulphonylurea. The improvement in HbA1c was similar between Asian and non-Asian patients.

Hyperthyroidism caused by acquired immune deficiency syndrome

BACKGROUND

Acquired immune deficiency syndrome (AIDS) is an immune deficiency disease. The etiology of hyperthyroidism, which can also be immune-related, is usually divided into six classical categories, including hypophyseal, hypothalamic, thyroid, neoplastic, autoimmune and inflammatory hyperthyroidism. Hyperthyroidism is a rare complication of highly active antimicrobial therapy (HAART) for human immunodeficiency virus (HIV). Hyperthyroidism caused directly by AIDS has not been previously reported.

PATIENT FINDINGS

A 29-year-old man who complained of dyspnea and asthenia for 1 month, recurrent fever for more than 20 days, and breathlessness for 1 week was admitted to our hospital. The thyroid function test showed that the level of free thyroxine (FT4) was higher than normal and that the level of thyroid-stimulating hormone (TSH) was below normal. He was diagnosed with hyperthyroidism. Additional investigations revealed a low serum albumin level and chest infection, along with diffuse lung fibrosis. Within 1 month, he experienced significant weight loss, no hand tremors, intolerance of heat, and perspiration proneness. We recommended an HIV examination; subsequently, AIDS was diagnosed based on the laboratory parameters.

SUMMARY

This is the first reported case of hyperthyroidism caused by AIDS.

CONCLUSIONS

AIDS may cause hyperthyroidism by immunization regulation with complex, atypical, and easily ignored symptoms. Although hyperthyroidism is rare in patients with AIDS, clinicians should be aware of this potential interaction and should carefully monitor thyroid function in HIV-positive patients.