Square Membrane Resonators Supporting Degenerate Modes of Vibration for High-Throughput Mass Spectrometry of Single Bacterial Cells

In nanomechanical mass spectrometry, sensing devices are commonly placed in the vacuum environment and a stream of analytes is directed toward the sensor surface for measurement. Beam structures, such as double-clamped nanobeams and nanocantilevers, are commonly used due to their low inertial mass and the simplicity of the analytical models for mass extraction. The drawback of such structures is their low capture areas, compromising the capture efficiency and throughput of this technique. Bi-axisymmetric resonators, such as ultrathin square or circular membranes, arise as an optimal geometry to maximize capture efficiency while minimizing the device inertial mass. However, these structures present degenerate mechanical modes, whose frequency perturbations upon analyte adsorption are not well described by commonly used models. Furthermore, prior knowledge of the vibration mode shapes of the sensor is crucial for the correct calculation of the analyte's mass, and the mode shape of degenerate modes may change significantly after every adsorption event. In this work, we present an accurate analytical theory to describe the effect of mass adsorption on the degenerate modes of square membrane resonators and propose two different methods based on the new theory to update the vibration mode shapes after every adsorption event. Finally, we illustrate the problem experimentally obtaining the mass and adsorption position of individual Escherichia coli K-12 bacterial cells on commercial square silicon nitride membranes fabricated with very small tolerances.

UAV-borne LiDAR revolutionizing groundwater level mapping

In hydrogeological research, the systematic and periodic measurement of the piezometric level is fundamental to assess aquifer storage, identify recharge and discharge areas, define flow directions and to infer the balance between inputs and withdrawals. Furthermore, knowledge of this variable and its fluctuations is essential for the efficient management and protection of groundwater resources. In this work, a novel methodology is proposed for the remote acquisition of piezometric information from traditional large-diameter wells, using drone-borne LiDAR observations. The workflow developed consists of different stages, from flight planning and parameter setting, to point cloud generation, data processing and validation and its statistical treatment to extract piezometric information. This methodology has been applied in a small coastal aquifer with numerous wells that have served as monitoring points. The UAV-LiDAR has enabled the straightforward obtention of measurements of the piezometric level with very high vertical accuracies (RMSE of 5 cm) with minimum and maximum residuals of -8.7 and 7.9 cm respectively. Likewise, the method has shown vertical accuracies 3 times better than those inferred from the official DTM of best resolution available in Spain, which is usually used in hydrogeological works. Since the technique provides absolute values of the piezometric level, it eliminates the need for laborious levelling work prior to hydrogeological campaigns. This method has proved to be an effective alternative/complementary technique to traditional measurements of the piezometric level, allowing to monitor extensive or inaccessible areas over short periods of time and to potentially reduce gaps in hydrogeological databases.

Hydrodynamic assisted multiparametric particle spectrometry

The real-time analysis of single analytes in flow is becoming increasingly relevant in cell biology. In this work, we theoretically predict and experimentally demonstrate hydrodynamic focusing with hollow nanomechanical resonators by using an interferometric system which allows the optical probing of flowing particles and tracking of the fundamental mechanical mode of the resonator. We have characterized the hydrodynamic forces acting on the particles, which will determine their velocity depending on their diameter. By using the parameters simultaneously acquired: frequency shift, velocity and reflectivity, we can unambiguously classify flowing particles in real-time, allowing the measurement of the mass density: 1.35 ± 0.07 g·mL^-1 for PMMA and 1.7 ± 0.2 g·mL^-1 for silica particles, which perfectly agrees with the nominal values. Once we have tested our technique, MCF-7 human breast adenocarcinoma cells are characterized (1.11 ± 0.08 g·mL^-1) with high throughput (300 cells/minute) observing a dependency with their size, opening the door for individual cell cycle studies.

Publisher Correction: Optomechanical detection of vibration modes of a single bacterium

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Optomechanical detection of vibration modes of a single bacterium

Low-frequency vibration modes of biological particles, such as proteins, viruses and bacteria, involve coherent collective vibrations at frequencies in the terahertz and gigahertz domains. These vibration modes carry information on their structure and mechanical properties, which are good indicators of their biological state. In this work, we harnessed a particular regime in the physics of coupled mechanical resonators to directly measure these low-frequency mechanical resonances of a single bacterium. We deposit the bacterium on the surface of an ultrahigh frequency optomechanical disk resonator in ambient conditions. The vibration modes of the disk and bacterium hybridize when their associated frequencies are similar. We developed a general theoretical framework to describe this coupling, which allows us to retrieve the eigenfrequencies and mechanical loss of the bacterium low-frequency vibration modes (quality factor). Additionally, we analysed the effect of hydration on these vibrational modes. This work demonstrates that ultrahigh frequency optomechanical resonators can be used for vibrational spectrometry with the unique capability to obtain information on single biological entities.

Mechano-Optical Analysis of Single Cells with Transparent Microcapillary Resonators

The study of biophysical properties of single cells is becoming increasingly relevant in cell biology and pathology. The measurement and tracking of magnitudes such as cell stiffness, morphology, and mass or refractive index have brought otherwise inaccessible knowledge about cell physiology, as well as innovative methods for high-throughput label-free cell classification. In this work, we present hollow resonator devices based on suspended glass microcapillaries for the simultaneous measurement of single-cell buoyant mass and reflectivity with a throughput of 300 cells/minute. In the experimental methodology presented here, both magnitudes are extracted from the devices' response to a single probe, a focused laser beam that enables simultaneous readout of changes in resonance frequency and reflected optical power of the devices as cells flow within them. Through its application to MCF-7 human breast adenocarcinoma cells and MCF-10A nontumorigenic cells, we demonstrate that this mechano-optical technique can successfully discriminate pathological from healthy cells of the same tissue type.

Prevalence and Factors Associated With Fatigue in Patients With Inflammatory Bowel Disease: A Multicentre Study

BACKGROUND AND AIMS

The aims of this study were to determine the prevalence of fatigue in patients with inflammatory bowel disease [IBD], to identify the factors associated with fatigue and its severity, to assess the impact of fatigue on quality of life [QoL], and to evaluate the relationship between fatigue and sleep disorders.

METHODS

This was a prospective multicentre study conducted at 22 Spanish centres. Consecutive patients followed at IBD Units were included. Fatigue was evaluated with the Fatigue Severity Scale [FSS] and the Fatigue Impact Scale [FIS]. Quality of life and sleep quality were assessed using the IBD Questionnaire-Short Form [IBDQ-9] and the Pittsburgh Sleep Quality Index [PSQI], respectively.

RESULTS

A total of 544 consecutive adult IBD patients were included [50% women, mean age 44 years, 61% Crohn's disease]. The prevalence of fatigue was 41% (95% confidence interval [CI] = 37-45%). The variables associated with an increased risk of fatigue were: anxiety [OR = 2.5, 95% CI = 1.6-3.7], depression [OR = 2.4, 95% CI = 1.4-3.8], presence of extraintestinal manifestations [EIMs] [OR = 1.7, 95% CI = 1.1-2.6], and treatment with systemic steroids [OR = 2.8, 95% CI = 1.4-5.7]. The presence of EIMs [regression coefficient, RC = 8.2, 95% CI = 2.3-14.2], anxiety [RC = 25.8, 95% CI = 20.0-31.5], depression [RC = 30.6, 95% CI = 24.3-37.0], and sleep disturbances [RC = 15.0, 95% CI = 9.3-20.8] were associated with severity of fatigue. Patients with fatigue had a significantly decreased IBDQ-9 score [p < 0.001].

CONCLUSIONS

The prevalence of fatigue in IBD patients is remarkably high and has a negative impact on QoL. Therapy with systemic steroids is associated with an increased risk of fatigue. The severity of fatigue is associated with anxiety, depression, sleep disorders, and the presence of EIMs. Fatigue was not associated with anaemia, disease activity or anti-TNF therapy.

Real-world short-term effectiveness of ustekinumab in 305 patients with Crohn's disease: results from the ENEIDA registry

BACKGROUND

There are limited data of ustekinumab administered according to the doses recommended in the UNITI studies.

AIM

To assess the real-world, short-term effectiveness of ustekinumab in refractory Crohn's disease (CD) METHODS: Multicentre study of CD patients starting ustekinumab after June 2017 at the recommend dose (260, 390 or 520 mg based on weight ~6 mg/kg IV week 0 and 90 mg subcutaneously week 8). Values for Harvey-Bradshaw Index (HBI), C-reactive protein (CRP) and faecal calprotectin (FC) were recorded at baseline and at weeks 8 and 14. Demographic and clinical data, previous treatments, AEs and hospitalisations were documented. Possible predictors of clinical remission were examined.

RESULTS

Three hundred and five patients were analysed (≥2 previous anti-TNFα therapies 64% and vedolizumab 29%). At baseline, 217 (72%) had an HBI >4 points. Of these, 101 (47%) and 126 (58%) achieved clinical remission at weeks 8 and 14, respectively. FC levels returned to normal (<250 µg/g) in 46% and 54% of the patients at weeks 8 and 14 respectively. CRP returned to normal (<3 mg/L) in the 35% and 41% of the patients at week 8 and 14 respectively. AEs were recorded in 38, and 40 patients were hospitalised. Intolerance to the most recent anti-TNF agent and fewer previous anti-TNF agents were associated with clinical remission at week 14. Endoscopic severity was associated with poor response.

CONCLUSION

This is the first study to show the real-world effectiveness and safety of ustekinumab administered according to the recommended induction regimen in a cohort of highly refractory CD patients.

Combination of melatonin and rapamycin for head and neck cancer therapy: Suppression of AKT/mTOR pathway activation, and activation of mitophagy and apoptosis via mitochondrial function regulation

Head and neck squamous cell carcinoma (HNSCC) clearly involves activation of the Akt mammalian target of rapamycin (mTOR) signalling pathway. However, the effectiveness of treatment with the mTOR inhibitor rapamycin is often limited by chemoresistance. Melatonin suppresses neoplastic growth via different mechanisms in a variety of tumours. In this study, we aimed to elucidate the effects of melatonin on rapamycin-induced HNSCC cell death and to identify potential cross-talk pathways. We analysed the dose-dependent effects of melatonin in rapamycin-treated HNSCC cell lines (Cal-27 and SCC-9). These cells were treated with 0.1, 0.5 or 1 mmol/L melatonin combined with 20 nM rapamycin. We further examined the potential synergistic effects of melatonin with rapamycin in Cal-27 xenograft mice. Relationships between inhibition of the mTOR pathway, reactive oxygen species (ROS), and apoptosis and mitophagy reportedly increased the cytotoxic effects of rapamycin in HNSCC. Our results demonstrated that combined treatment with rapamycin and melatonin blocked the negative feedback loop from the specific downstream effector of mTOR activation S6K1 to Akt signalling, which decreased cell viability, proliferation and clonogenic capacity. Interestingly, combined treatment with rapamycin and melatonin-induced changes in mitochondrial function, which were associated with increased ROS production, increasing apoptosis and mitophagy. This led to increase cell death and cellular differentiation. Our data further indicated that melatonin administration reduced rapamycin-associated toxicity to healthy cells. Overall, our findings suggested that melatonin could be used as an adjuvant agent with rapamycin, improving effectiveness while minimizing its side effects.

Safety of thiopurines and anti-TNF-α drugs during pregnancy in patients with inflammatory bowel disease

OBJECTIVES

The safety of thiopurines and anti-tumor necrosis factor-α (TNF-α) drugs during pregnancy remains controversial, as the experience with these drugs in this situation is limited. Our aim is to assess the safety of thiopurines and anti-TNF-α drugs for the treatment of inflammatory bowel disease (IBD) during pregnancy.

METHODS

Retrospective, multicenter study in IBD patients. Pregnancies were classified according to the therapeutic regimens during pregnancy or during the 3 months before the conception: non-exposed group, pregnancies exposed to thiopurines alone (group A), and pregnancies exposed to anti-TNF-α drugs (group B). An unfavorable Global Pregnancy Outcome (GPO) was considered if pregnancy developed with obstetric complications in the mother and in the newborn.

RESULTS

A total of 187 pregnancies in the group A, 66 pregnancies in the group B, and 318 pregnancies in the non-exposed group were included. The rate of unfavorable GPO was different among the three groups (31.8% in non-exposed group, 21.9% in group A, and 34.8% in group B), being lower in pregnancies under thiopurines than among non-exposed (P = 0.01). The rate of pregnancy complications was similar among the three groups (27.7% in non-exposed, 20.9% in group A, and 30.3% in group B). The rate of neonatal complications was different among the three groups (23.3% in non-exposed group, 13.9% in group A, and 21.2% in group B), being lower in pregnancies under thiopurines than among non-exposed (P = 0.01). In the multivariate analysis, the treatment with thiopurines (odds ratio = 0.6; 95% confidence interval = 0.4-0.9, P = 0.02) was the only predictor of favorable GPO, whereas maternal age >35 years at conception was the only predictor of unfavorable GPO. The treatment with anti-TNF-α drugs was not associated with an unfavorable GPO.

CONCLUSION

The treatment with thiopurines and anti-TNF-α drugs does not seem to increase the risk of complications during pregnancy and does seem to be safe for the newborn.

Cyclosporine in the treatment of severe attack of ulcerative colitis: a systematic review

INTRODUCTION

Intravenous steroid therapy is the standard treatment in severe attacks of ulcerative colitis (UC), but 20% to 60% of patients fail to respond and require colectomy. Cyclosporine (CyA) has shown efficacy in steroid failures and could avoid surgery, but controversy remains.

AIM

The objective of this study was to conduct a systematic review to evaluate the effectiveness and safety of CyA in inducing remission in patients with a severe attack of UC.

METHODS

We did a systematic review using Cochrane methodology, including data from published (in English, French, Spanish or German) clinical trials done in adults using intravenous or oral CyA in UC. Data on efficacy are obtained from controlled and observational clinical trials, and for safety issues case reports are also considered.

RESULTS

31 studies were identified which met the inclusion criteria, 22 (18 uncontrolled, 4 controlled) with intravenous CyA, and 9 (all uncontrolled) using oral CyA. Only 4 controlled trials (one in abstract form) are available, and only one compares CyA to placebo. However, efficacy results are very consistent in these 4 trials, and very similar to those in observational studies. CyA achieves remission in 91,4% and 71.4% of patients in controlled and uncontrolled studies using intravenous route, and in 71,2% using oral route. Two mg/kg/day seems so efficacious and safer as previous standard 4 mg/kg/day dose. Minor side effects are rather common but do not seriously limit therapy. Severe side effects, specially infections, are uncommon but clinically relevant with several deaths reported.

CONCLUSION

CyA (intravenous, 2 mg/kg/day) constitutes an efficacious and relatively safe alternative in the treatment of severe, steroid-refractory, attack of UC. To optimize treatment, the correct selection of patients, a standardized protocol and clinical surveillance are recommended.

Mechanical deformation inhibits IL-10 and stimulates IL-12 production by mouse calvarial osteoblasts in vitro

The skeleton is continuously remodelled throughout life, a process that is orchestrated by cells of the osteoblast lineage. Remodelling involves a complex network of cell-cell signalling involving systemic hormones, locally produced cytokines, growth factors and the mechanical environment of the cells. Here, we report on the effect of mechanically-induced strain on the synthesis by mouse calvarial osteoblasts in monolayer culture of IL-10 and IL-12, two cytokines that inhibit osteoclast formation in bone marrow cultures; IL-10 also suppresses osteoblast differentiation suggesting a role for both cytokines in bone physiology. A tensile strain was applied to the cells intermittently for 6s, every 90s, for 2-96h. After 2-h culture, supernatants from deformed cells contained significantly less IL-10 than control cultures. In contrast, mechanical deformation had a stimulatory effect on IL-12 synthesis; however, by 48h both had returned to control levels. These data suggest that IL-10 and IL-12 can be added to the growing list of mechanical stress-responsive genes. The down-regulation of IL-10 and stimulation of IL-12 further suggests that the initial response of the cells to mechanical deformation was an osteogenic one.

[Changes in dental caries indexes in school children in an area of Xochimilco, Mexico: 1984-1992]

OBJECTIVE

To describe the changes in dental caries prevalence and severity, in a group of primary schoolchildren. Two dental caries surveys were carried out, one in 1984 and the other in 1992.

MATERIAL AND METHODS

The dental caries indices were registered using the World Health Organization's criteria. A group of 6-7 years old schoolchildren living in the East Region of Xochimilco were included in the study. A total of 279 children participated in this study; 153 in 1984 and 126 in 1992.

RESULTS

The mean value of the deft index was 5.65 (SD 3.35) in 1984, and the mean value of the deft index was 4.89 (SD 3.7) in 1992. For the permanent dentition the DMFT was 0.51 (SD 1.0) in 1984 and 0.48 (SD 0.82) in 1992. Differences in dental caries indices, between the first and second survey, were significant only for the primary dentition in the six years old group (95% CI 0.36, 2.15). An increase in the proportion of filled teeth was found. However, the treatment needs are still very high (69% for primary teeth and 86% for permanent teeth).

CONCLUSIONS

The findings from this study seem to indicate little change in the prevalence and severity of dental caries in the population in the period of study.