Microbiota-derived inosine programs protective CD8+ T cell responses against influenza in newborns

The immunological defects causing susceptibility to severe viral respiratory infections due to early-life dysbiosis remain ill-defined. Here, we show that influenza virus susceptibility in dysbiotic infant mice is caused by CD8+ T cell hyporesponsiveness and diminished persistence as tissue-resident memory cells. We describe a previously unknown role for nuclear factor interleukin 3 (NFIL3) in repression of memory differentiation of CD8+ T cells in dysbiotic mice involving epigenetic regulation of T cell factor 1 (TCF 1) expression. Pulmonary CD8+ T cells from dysbiotic human infants share these transcriptional signatures and functional phenotypes. Mechanistically, intestinal inosine was reduced in dysbiotic human infants and newborn mice, and inosine replacement reversed epigenetic dysregulation of Tcf7 and increased memory differentiation and responsiveness of pulmonary CD8+ T cells. Our data unveils new developmental layers controlling immune cell activation and identifies microbial metabolites that may be used therapeutically in the future to protect at-risk newborns.

Medical graphics to improve patient understanding and anxiety in elderly and cognitively impaired patients scheduled for transcatheter aortic valve implantation (TAVI)

BACKGROUND

Anxiety and limited patient comprehension may pose significant barriers when informing elderly patients about complex procedures such as transcatheter aortic valve implantation (TAVI).

OBJECTIVES

We aimed to evaluate the utility of medical graphics to improve the patient informed consent (IC) before TAVI.

METHODS

In this prospective, randomized dual center study, 301 patients were assigned to a patient brochure containing medical graphics (Comic group, n = 153) or sham information (Control group, n = 148) on top of usual IC. Primary outcomes were patient understanding of central IC-related aspects and periprocedural anxiety assessed by the validated Spielberger State Trait Anxiety Inventory (STAI), both analyzed by cognitive status according to the Montreal Cognitive Assessment (MoCA).

RESULTS

Patient understanding was significantly higher in the Comic group [mean number of correct answers 12.8 (SD 1.2) vs. 11.3 (1.8); mean difference 1.5 (95% CI 1.2-1.8); p < 0.001]. This effect was more pronounced in the presence of cognitive dysfunction (MoCA < 26) [12.6 (1.2) in the Comic vs. 10.9 (1.6) in the Control group; mean difference 1.8 (1.4-2.2), p < 0.001]. Mean STAI score declined by 5.7 (95% CI 5.1-6.3; p < 0.001) in the Comic and 0.8 points (0.2-1.4; p = 0.015) in the Control group. Finally, mean STAI score decreased in the Comic group by 4.7 (3.8-5.6) in cognitively impaired patients and by 6.6 (95% CI 5.8 to 7.5) in patients with normal cognitive function (p < 0.001 each).

CONCLUSIONS

Our results prove beneficial effects for using medical graphics to inform elderly patients about TAVI by improving patient understanding and reducing periprocedural anxiety (DRKS00021661; 23/Oct/2020). Medical graphics entailed significant beneficial effects on the primary endpoints, patient understanding and periprocedural anxiety, compared to the usual patient informed consent (IC) procedure. Patient understanding of IC-related aspects was significantly higher in the Comic group, with a more pronounced benefit in patients with cognitive impairment (p for IC method and cognitive status < 0.001, respectively; p for IC method x MoCA category interaction = 0.017). There further was a significant decline of periprocedural anxiety in patients with and without cognitive impairment (p for IC method x measuring time point < 0.001; p for IC method x MoCA category x measuring time point interaction = 0.018).

Circadian regulation of lung repair and regeneration

Optimal lung repair and regeneration are essential for recovery from viral infections, including influenza A virus (IAV). We have previously demonstrated that acute inflammation and mortality induced by IAV is under circadian control. However, it is not known whether the influence of the circadian clock persists beyond the acute outcomes. Here, we utilize the UK Biobank to demonstrate an association between poor circadian rhythms and morbidity from lower respiratory tract infections, including the need for hospitalization and mortality after discharge; this persists even after adjusting for common confounding factors. Furthermore, we use a combination of lung organoid assays, single-cell RNA sequencing, and IAV infection in different models of clock disruption to investigate the role of the circadian clock in lung repair and regeneration. We show that lung organoids have a functional circadian clock and the disruption of this clock impairs regenerative capacity. Finally, we find that the circadian clock acts through distinct pathways in mediating lung regeneration - in tracheal cells via the Wnt/β-catenin pathway and through IL-1β in alveolar epithelial cells. We speculate that adding a circadian dimension to the critical process of lung repair and regeneration will lead to novel therapies and improve outcomes.

Pulmonary Endothelial Activation with COVID‐19: Possible Role of Reactive Oxygen Species

Introduction

Recent research suggests that endothelial activation plays a role in COVID‐19 pathogenesis by promoting a pro‐coagulative and pro‐inflammatory state. However, the mechanism by which the endothelium is activated in COVID‐19 is unclear.

Objective

To investigate the mechanism by which COVID‐19 activates the pulmonary endothelium.

Hypothesis

The pulmonary endothelium generates reactive oxygen species (ROS) upon exposure to the “inflammatory load” of the systemic circulation.

Methods

COVID‐19 was recreated in vitro and ex vivo, by exposing human lung endothelial cells (EC) or donor human lung slices (human precision‐cut lung slices or huPCLS) to medium supplemented with serum from COVID‐19 affected subjects. Sera were acquired from patients with COVID‐19 infection admitted to the Intensive Care Unit of the Hospital at the University of Pennsylvania. ROS (fluorescent dye, CellROX) and intercellular adhesion molecule (ICAM‐1) levels were assessed by fluorescence labeling and imaging.

Results

Both EC activation (as monitored by ROS production) and pro‐inflammatory phenotype (as assessed by ICAM‐1), were significantly higher with COVID‐19 as compared to normal subjects.

Conclusions

The endothelium is activated with COVID‐19 via ROS production; thus, the ROS produced drive a pro‐inflammatory phenotype by inducing the expression of ICAM‐1, a pivotal marker of endothelium inflammation. As ROS mediates EC activation and inflammation during COVID‐19, ROS blockade could be a therapeutic target in maintaining vascular health.

Pulmonary vascular inflammation with fatal coronavirus disease 2019 (COVID-19): possible role for the NLRP3 inflammasome

Background

Pulmonary hyperinflammation is a key event with SARS-CoV-2 infection. Acute respiratory distress syndrome (ARDS) that often accompanies COVID-19 appears to have worse outcomes than ARDS from other causes. To date, numerous lung histological studies in cases of COVID-19 have shown extensive inflammation and injury, but the extent to which these are a COVID-19 specific, or are an ARDS and/or mechanical ventilation (MV) related phenomenon is not clear. Furthermore, while lung hyperinflammation with ARDS (COVID-19 or from other causes) has been well studied, there is scarce documentation of vascular inflammation in COVID-19 lungs.

Methods

Lung sections from 8 COVID-19 affected and 11 non-COVID-19 subjects, of which 8 were acute respiratory disease syndrome (ARDS) affected (non-COVID-19 ARDS) and 3 were from subjects with non-respiratory diseases (non-COVID-19 non-ARDS) were H&E stained to ascertain histopathological features. Inflammation along the vessel wall was also monitored by expression of NLRP3 and caspase 1.

Results

In lungs from COVID-19 affected subjects, vascular changes in the form of microthrombi in small vessels, arterial thrombosis, and organization were extensive as compared to lungs from non-COVID-19 (i.e., non-COVID-19 ARDS and non-COVID-19 non-ARDS) affected subjects. The expression of NLRP3 pathway components was higher in lungs from COVID-19 ARDS subjects as compared to non-COVID-19 non-ARDS cases. No differences were observed between COVID-19 ARDS and non-COVID-19 ARDS lungs.

Conclusion

Vascular changes as well as NLRP3 inflammasome pathway activation were not different between COVID-19 and non-COVID-19 ARDS suggesting that these responses are not a COVID-19 specific phenomenon and are possibly more related to respiratory distress and associated strategies (such as MV) for treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-01944-8.

The diagnostic accuracy of truncated cardiovascular MR protocols for detecting non-ischemic cardiomyopathies

Cardiovascular magnetic resonance imaging is one of the most important diagnostic modalities in the evaluation of cardiomyopathies. However, significant limitations are the complex and time-consuming workflows and the need of contrast agents. The aim of this multi-center retrospective study was to assess workflows and diagnostic value of a short, contrast agent-free cardiac magnetic resonance protocol. 160 patients from Heidelberg, Germany and 119 patients from Montreal, Canada with suspected cardiomyopathy and 20 healthy volunteers have been enrolled. Scans were performed at a 1.5Tesla or 3Tesla scanner in Heidelberg and at a 3Tesla scanner in Montreal. We used single-slice T1 map only. A stepwise analysis of images has been performed. The possible differential diagnosis after each step has been defined. T1-values and color-encoded T1 maps significantly contributed to the differential diagnosis in 54% of the cases (161/299); the final diagnosis has been done without late gadolinium enhancement images in 83% of healthy individuals, in 99% of patients with dilated cardiomyopathy, in 93% of amyloidosis patients, in 94% of patients with hypertrophic cardiomyopathy and in 85% of patients with hypertensive heart disease, respectively. Comparing the scan time with (48 ± 7 min) vs. without contrast agent (23 ± 5 min), significant time saving could be reached by the short protocol. Subgroup analysis showed the most additional diagnostic value of T1 maps in amyloidosis and hypertrophic cardiomyopathy or in confirmation of normal findings. In patients with unclear left ventricular hypertrophy, a short, non-contrast protocol can be used for diagnostic decision-making, if the quality of the T1 map is diagnostic, even if only one slice is available.

Vascular Inflammation in Lungs of Patients with Fatal Coronavirus Disease 2019 (COVID-19): Possible Role for the NLRP3 Inflammasome.. [PMID: 34494018 PMCID: PMC8423225 DOI: 10.21203/rs.3.rs-842167/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Background:

Hyperinflammation is a key event that occurs with SARS-CoV-2 infection. In the lung, hyperinflammation leads to structural damage to tissue. To date, numerous lung histological studies have shown extensive alveolar damage, but there is scarce documentation of vascular inflammation in postmortem lung tissue.

Methods:

Lung sections from 8 COVID-19 affected and 11 non-COVID-19 subjects [of which 8 were acute respiratory disease syndrome (ARDS) affected and 3 were from subjects with non-respiratory diseases] were stained for H & E to ascertain histopathological features including presence of thrombi/microthrombi. Inflammation along the vessel wall was also monitored by quantification of the expression of moieties of the NLRP3 inflammasome pathway (NLRP3 and caspase-1).

Results:

In lungs from “fatal COVID-19”, vascular changes in the form of microthrombi in small vessels, arterial thrombosis, and organization were extensive as compared to lungs from “non-COVID-19 non respiratory disease” affected subjects. The NLRP3 pathway components were significantly higher in lungs from COVID-19 subjects as compared to non-COVID-19 fatal cases without respiratory disease. No significant differences were observed between COVID-19 lungs and non-COVID-19 ARDS lungs.

Conclusion:

We posit that inflammasome formation along the vessel wall is a characteristic of lung inflammation that accompanies COVID-19. Thus, the NLRP3 inflammasome pathway seems to be probable candidate that drives amplification of inflammation post SARS-CoV-2 infection.

Vascular Inflammation in Lungs of Patients with Fatal Coronavirus Disease 2019 (COVID-19) Infection: Possible role for the NLRP3 inflammasome

Hyperinflammation is a key event that occurs with SARS-CoV-2 infection. In the lung, hyperinflammation leads to structural damage to tissue. To date, numerous lung histological studies have shown extensive alveolar damage, but there is scarce documentation of vascular inflammation in postmortem lung tissue. Here we document histopathological features and monitor the NLRP3 inflammasome in fatal cases of disease caused by SARS Cov2 (COVID-19). We posit that inflammasome formation along the vessel wall is a characteristic of lung inflammation that accompanies COVID-19 and that it is a probable candidate that drives amplification of inflammation post infection.

Inflammation in Periodontal Disease: Possible Link to Vascular Disease

Inflammation is a well-organized protective response to pathogens and consists of immune cell recruitment into areas of infection. Inflammation either clears pathogens and gets resolved leading to tissue healing or remains predominantly unresolved triggering pathological processes in organs. Periodontal disease (PD) that is initiated by specific bacteria also triggers production of inflammatory mediators. These processes lead to loss of tissue structure and function. Reactive oxygen species and oxidative stress play a role in susceptibility to periodontal pathogenic bacterial infections. Periodontal inflammation is a risk factor for systemic inflammation and eventually cardiovascular disease (CVD). This review discusses the role of inflammation in PD and its two way association with other health conditions such as diabetes and CVD. Some of the mechanisms underpinning the links between inflammation, diabetes, CVD and PD are also discussed. Finally, we review available epidemiological data and other reports to assess possible links between oral health and CVD.

Contrast-agent free evaluation of cardiomyopathies with T1 mapping and the new fast strain-encoded (fSENC) magnetic resonance imaging

Background

Cardiomyopathies (CMP) may cause impairment of cardiac function and structure. Cardiac Magnetic Resonance Imaging (CMR) is used for analysis and risk stratification of CMP by Late Gadolinium Enhancement (LGE). However, T1 mapping (T1) and fast strain encoded (f-SENC) sequences allow contrast-free and faster exams. The aim of this study was to characterize CMP by T1 and f-SENC to develop a faster and safer CMR protocol (fast-CMR).

Methods

CMP scans from our CMR database were retrospectively analyzed. All patients were scanned at 1.5T/3T scanner. Study groups were divided as follows: Patients with normal findings, dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), hypertensive heart disease (HHD) and cardiac amyloidosis. Global T1 times, longitudinal (GLS) and circumferential (GCS) strain using f-SENC of study groups were compared to healthy individuals (controls). Scan time and amount of gadolinium-based contrast agent (CA) in CMR-protocol with LGE were compared to fast-CMR.

Results

174 patients and 31 controls were recruited. T1 times, GLS and GCS were similar between controls and normal individuals. T1 times were significantly increased (p&lt;0.05), while GLS and GCS were significantly reduced (p&lt;0.05) in all CMR study groups compared to controls (Table 1). Using fast-CMR 21 (±6) min of scan time were saved, about 47%, and 9 (±2) ml of CA were saved per patient.

Conclusion

Normal findings could be identified by fast-CMR without contrast agent. Fast CMR might also be a useful tool to identify different forms of CMP.

Funding Acknowledgement

Type of funding source: None

Cardiac pacing using transmural multi-LED probes in channelrhodopsin-expressing mouse hearts

Optogenetics enables cell-type specific monitoring and actuation via light-activated proteins. In cardiac research, expressing light-activated depolarising ion channels in cardiomyocytes allows optical pacing and defibrillation. Previous studies largely relied on epicardial illumination. Light penetration through the myocardium is however problematic when moving to larger animals and humans. To overcome this limitation, we assessed the utility of an implantable multi light-emitting diode (LED) optical probe (IMLOP) for intramural pacing of mouse hearts expressing cardiac-specific channelrhodopsin-2 (ChR2).

Here we demonstrated that IMLOP insertion needs approximately 20 mN of force, limiting possible damage from excessive loads applied during implantation. Histological sections confirmed the confined nature of tissue damage during acute use. The temperature change of the surrounding tissue was below 1 K during LED operation, rendering the probe safe for use in situ. This was confirmed in control experiments where no effect on cardiac action potential conduction was observed even when using stimulation parameters twenty-fold greater than required for pacing.

In situ experiments on ChR2-expressing mouse hearts demonstrated that optical stimulation is possible with light intensities as low as 700 μW/mm²; although stable pacing requires higher intensities. When pacing with a single LED, rheobase and chronaxie values were 13.3 mW/mm2 ± 0.9 mW/mm² and 3 ms ± 0.6 ms, respectively. When doubling the stimulated volume the rheobase decreased significantly (6.5 mW/mm2 ± 0.9 mW/mm²).

We have demonstrated IMLOP-based intramural optical pacing of the heart. Probes cause locally constrained tissue damage in the acute setting and require low light intensities for pacing. Further development is necessary to assess effects of chronic implantation.

Transposon Mutagenesis of Listeria monocytogenes

Listeria monocytogenes is a Gram-positive, facultative intracellular foodborne pathogen that enters the human digestive tract after the consumption of contaminated food. Much research has been done to understand the virulence factors of Listeria monocytogenes. One useful tool to study these virulence factors has been transposon mutagenesis. Many mutants can be generated at a time by performing high-throughput mutagenesis using transposons and later screening these mutants to identify features related to particular functions in the bacteria. Many transposon delivery systems are not ideal for transposon studies in Listeria monocytogenes, as the transposon system is too large, has lower transposition efficiency, and a high rate of plasmid retention. Therefore, a new mariner-based transposition system has been developed for Listeria monocytogenes. This system is an ideal high-throughput transposon mutagenesis as the rate of transposition is high and random, along with very low plasmid retention capacity.

Oxygen deprivation influences the survival of Listeria monocytogenes in gerbils

Listeria monocytogenes is a facultative anaerobic foodborne pathogen capable of surviving harsh environments. Recent work has indicated that anaerobic conditions increase the resistance capability of certain strains to environmental stressors. The goal of the study was to conduct a preliminary study to determine whether exposure to anaerobic conditions prior to infection increases the ability to survive in vivo. Gerbils were inoculated with one of five doses of the L. monocytogenes strain F2365 by oral gavage: phosphate-buffered saline (control), 5 × 10⁶ colony forming units aerobic culture (low aerobic), 5 × 10⁸ aerobic culture (high aerobic), 5 × 10⁶ anaerobic culture (low anaerobic), or 5 × 10⁸ anaerobic culture (high anaerobic) dose of F2365. Gerbils inoculated with a high aerobic or anaerobic dose exhibited significant weight loss. Gerbils administered either the low or high anaerobic dose had at least 3 log₁₀ of L. monocytogenes present in fecal samples, which contrasted with gerbils that received the low aerobic dose. Animals that received the high anaerobic dose had a significant increase in bacterial loads within the liver. Histologic examination of the L. monocytogenes positive livers exhibited locally extensive areas of hepatocellular necrosis, though the extent of this damage differed between treatment groups. Microbial community analysis of the cecum from gerbils infected with L. monocytogenes indicated that the abundance of Bacteroidales and Clostridiales increased and there was a decrease in the abundance of Spirochaetales. This study suggests that anaerobic conditions alter the localization pattern of L. monocytogenes within the gastrointestinal tract. These findings could relate to how different populations are more susceptible to listeriosis, as oxygen availability may differ within the gastrointestinal tract.

Smart Bracket for Multi-dimensional Force and Moment Measurement

Atraumatic, well-directed, and efficient tooth movement is interrelated with the therapeutic application of adequately dimensioned forces and moments in all three dimensions. The lack of appropriate monitoring tools inspired the development of an orthodontic bracket with an integrated microelectronic chip equipped with multiple piezoresistive stress sensors. Such a ‘smart bracket’ was constructed (scale of 2.5:1) and calibrated. To evaluate how accurately the integrated sensor system allowed for the quantitative determination of three-dimensional force-moment systems externally applied to the bracket, we exerted 396 different force-moment combinations with dimensions within usual therapeutic ranges (± 1.5 N and ± 15 Nmm). Comparison between the externally applied force-moment components and those reconstructed on the basis of the stress sensor signals revealed very good agreement, with standard deviations in the differences of 0.037 N and 0.985 Nmm, respectively. We conclude that our methodological approach is generally suitable for monitoring the relatively low forces and moments exerted on individual teeth with fixed orthodontic appliances.

Fabrication and characterization of a high-resolution neural probe for stereoelectroencephalography and single neuron recording

This paper reports on the design, fabrication, and characterization of neural probes for stereoelectroencephalography (SEEG). The probe specifically targets focal epilepsy as key application. However, probes of this type can also be used for the diagnosis and treatment of other neural dysfunctions such as Parkinson's disease or tremor, typically requiring deep brain probes. The probe fabrication, of which most processes are parallel batch processes, relies on a novel fabrication concept for rolling and gluing thin film polyimide sheets with integrated electrodes into permanent cylindrical shapes with diameters down to 800 μm. The SEEG probes, comprise several macro-electrodes designed to record local field potentials, and micro-electrodes positioned in-between, dedicated to monitoring single unit activity, with a total channel count of 32, despite the small diameter. While platinum micro-electrodes with a diameter of 35 μm have impedances of about 255 kΩ at 1 kHz, impedance values down to about 1.5 kΩ have been measured for the macro-electrodes. The devices have shown good compatibility with magnetic resonance imaging in a 9.4 T magnet, enabling the precise post-operative probe localization within the brain.

The Effect of Oxygen on Bile Resistance in Listeria monocytogenes

Listeria monocytogenes is a Gram-positive facultative anaerobe that is the causative agent of the disease listeriosis. The infectious ability of this bacterium is dependent upon resistance to stressors encountered within the gastrointestinal tract, including bile. Previous studies have indicated bile salt hydrolase activity increases under anaerobic conditions, suggesting anaerobic conditions influence stress responses. Therefore, the goal of this study was to determine if reduced oxygen availability increased bile resistance of L. monocytogenes. Four strains representing three serovars were evaluated for changes in viability and proteome expression following exposure to bile in aerobic or anaerobic conditions. Viability for F2365 (serovar 4b), EGD-e (serovar 1/2a), and 10403S (serovar 1/2a) increased following exposure to 10% porcine bile under anaerobic conditions (P < 0.05). However, HCC23 (serovar 4a) exhibited no difference (P > 0.05) in bile resistance between aerobic and anaerobic conditions, indicating that oxygen availability does not influence resistance in this strain. The proteomic analysis indicated F2365 and EGD-e had an increased expression of proteins associated with cell envelope and membrane bioenergetics under anaerobic conditions, including thioredoxin-disulfide reductase and cell division proteins. Interestingly, HCC23 had an increase in several dehydrogenases following exposure to bile under aerobic conditions, suggesting that the NADH:NAD+ is altered and may impact bile resistance. Variations were observed in the expression of the cell shape proteins between strains, which corresponded to morphological differences observed by scanning electron microscopy. These data indicate that oxygen availability influences bile resistance. Further research is needed to decipher how these changes in metabolism impact pathogenicity in vivo and also the impact that this has on susceptibility of a host to listeriosis.

Modular assembly concept for 3D neural probe prototypes offering high freedom of design and alignment precision

The new assembly technology developed in this research provides a means to extend planar intracortical neural probes with one-dimensional (1D) and two-dimensional (2D) electrode arrangements into complex three-dimensional (3D) neural probes. The approach is based on novel silicon stacking modules realized using microsystems technologies. With these microcomponents, 3D probes can be assembled flexibly and tailored to the demands of neuroscientific experiments. The manufacturing process of the stacking modules provides the possibility to adjust the electrode spacing in the stacking direction with micrometer precision. The assembly method is demonstrated with 32-channel systems comprising 7-mm-long and 50-μm-thin neural probes. The angular alignment between the neural probes and their stacking modules after assembly as well as the vertical electrode pitch were determined to be about 1° and 353±15 μm, respectively.

[Epidemiology, etiology and psychosocial impact of urogenital fistulas in a cohort of 170 consecutive patients managed in three treatment centers in Burkina Faso from 2010 to 2012]

OBJECTIVE

To describe the socio-demographical aspects, etiologies and psychosocial consequences of urogenital fistula patients (UGF) in Burkina Faso (BF).

PATIENTS AND METHODS

Descriptive study of a cohort of consecutive patients during a period of 18 months (December 1st 2010 to August 31st 2012) in three centers of treatment in BF. Each patient has had a standardized complete medical observation focused on sociodemographics, clinical finding, past medical history and etiologies of UGF. Some patients had an interview with a psychologist.

RESULTS

One hundred and seventy patients with mean age 35 years (minimum: 16, maximum: 70) were enrolled during the study period. The majority of patients were housewives (90.5%, n=152) and illiterates (92.9%, n=158). Among the patients, 62.4% (n=106) lived in rural zones. Obstetrical fistula was the most common cause of UGF (87.6%, n=149) in our study and prolonged labor occurred in 93.3% (n=139) of cases with 17.5% (n=26) who delivered at home. The majority of our cases were vesico-vaginal fistula (70.6%, n=120). Fifty-five patients (32.4%) were divorced after the fistula. The sensation of humiliation and sadness were noted at all the patients who had a psychological evaluation and 87.5% (n=14) of them have had suicidal ideas.

CONCLUSION

The UGF are frequent in Burkina Faso and obstetrical etiology is dominant. The physical and psychosocial repercussions are important for the women victims of this pathology.

LEVEL OF EVIDENCE

4.

Miniaturized tool for optogenetics based on an LED and an optical fiber interfaced by a silicon housing

This paper reports on the design, simulation, fabrication and characterization of a tool for optogenetic experiments based on a light emitting diode (LED). A minimized silicon (Si) interface houses the LED and aligns it to an optical fiber. With a Si housing size of 550×500×380 μm(3) and an electrical interconnection of the LED by a highly flexible polyimide (PI) ribbon cable is the system very variable. PI cables and Si housings are fabricated using established microsystem technologies. A 270×220×50 μm(3) bare LED chip is flip-chip-bonded onto the PI cable. The Si housing is adhesively attached to the PI cable, thereby hosting the LED in a recess. An opposite recess guides the optical fiber with a diameter of 125 μm. An aperture in-between restricts the emitted LED light to the fiber core. The optical fiber is adhesively fixed into the Si housing recess. An optical output intensity at the fiber end facet of 1.71 mW/mm(2) was achieved at a duty cycle of 10 % and a driving current of 30 mA.

FIB preparation and SEM investigations for three-dimensional analysis of cell cultures on microneedle arrays

We report the investigation of the interfaces between microneedle arrays and cell cultures in patch-on-chip systems by using Focused Ion Beam (FIB) preparation and Scanning Electron Microscopy (SEM). First, FIB preparations of micro chips are made to determine the size and shape of the designed microneedles. In this essay, we investigate the cell-substrate interaction, especially the cell adhesion, and the microneedle's potential cell penetration. For this purpose, cross-sectional preparation of these hard/soft hybrid structures is performed by the FIB technology. By applying the FIB technology followed by high-resolution imaging with SEM, new insights into the cell-substrate interface can be received. One can clearly distinguish between cells that are only in contact with microneedles and cells that are penetrated by microneedles. A stack of slice images is collected by the application of the slice-and-view setup during FIB preparation and is used for three-dimensional reconstruction of cells and micro-needles.

Torsional bridge setup for the characterization of integrated circuits and microsensors under mechanical shear stress

We present a torsional bridge setup for the electro-mechanical characterization of devices integrated in the surface of silicon beams under mechanical in-plane shear stress. It is based on the application of a torsional moment to the longitudinal axis of the silicon beams, which results in a homogeneous in-plane shear stress in the beam surface. The safely applicable shear stresses span the range of ±50 MPa. Thanks to a specially designed clamping mechanism, the unintended normal stress typically stays below 2.5% of the applied shear stress. An analytical model is presented to compute the induced shear stress. Numerical computations verify the analytical results and show that the homogeneity of the shear stress is very high on the beam surface in the region of interest. Measurements with piezoresistive microsensors fabricated using a complementary metal-oxide-semiconductor process show an excellent agreement with both the computational results and comparative measurements performed on a four-point bending bridge. The electrical connection to the silicon beam is performed with standard bond wires. This ensures that minimal forces are applied to the beam by the electrical interconnection to the external instrumentation and that devices with arbitrary bond pad layout can be inserted into the setup.

Two-dimensional multi-channel neural probes with electronic depth control

This paper presents multi-electrode arrays for in vivo neural recording applications incorporating the principle of electronic depth control (EDC), i.e., the electronic selection of recording sites along slender probe shafts independently for multiple channels. Two-dimensional (2D) arrays were realized using a commercial 0.5- μm complementary-metal-oxide-semiconductor (CMOS) process for the EDC circuits combined with post-CMOS micromachining to pattern the comb-like probes and the corresponding electrode metallization. A dedicated CMOS integrated front-end circuit was developed for pre-amplification and multiplexing of the neural signals recorded using these probes.

A Novel Method to Measure Poisson's Ratio of Thin Films

We report a novel method to measure Poisson's ratio v of compressively prestressed thin films. The method exploits a v-dependent mechanical instability transition of buckled long rectangular membranes under differential pressure. This allows to determine v with high accuracy, using a physical model of the plate instability. The method was used to extract v = 0.253±0.017 from 0.704±0.003 μim thick PECVD silicon nitride films.

Extraction of the Coefficient of Thermal Expansion of Thin Films from Buckled Membranes

We report a new method to measure the temperature-dependent coefficient of thermal expansion α(T) of thin films. The method exploits the temperature dependent buckling of clamped square plates. This buckling was investigated numerically using an energy minimization method and finite element simulations. Both approaches show excellent agreement even far away from simple critical buckling. The numerical results were used to extract Cα(T) = α0+α1(T−T0 ) of PECVD silicon nitride between 20° and 140°C with α0 = (1.803±0.006)×10−6°C−1, α1 = (7.5±0.5)×10−9 °C−2, and T0 = 25°C.

Metamaterial-based gradient index lens with strong focusing in the THz frequency range

The development of innovative terahertz (THz) imaging systems has recently moved in the focus of scientific efforts due to the ability to screen substances through textiles or plastics. The invention of THz imaging systems with high spatial resolution is of increasing interest for applications in the realms of quality control, spectroscopy in dusty environment and security inspections. To realize compact THz imaging systems with high spatial resolution it is necessary to develop lenses of minimized thickness that still allow one to focus THz radiation to small spot diameters with low optical aberrations. In addition, it would be desirable if the lenses offered adaptive control of their optical properties to optimize the performance of the imaging systems in the context of different applications. Here we present the design, fabrication and the measurement of the optical properties of spectrally broadband metamaterial-based gradient index (GRIN) lenses that allow one to focus THz radiation to a spot diameter of approximately one wavelength. Due to the subwavelength thickness and the high focusing strength the presented GRIN lenses are an important step towards compact THz imaging systems with high spatial resolution. Furthermore, the results open the path to a new class of adaptive THz optics by extension of the concept to tunable metamaterials.

Discrete cortical responses from multi-site supra-choroidal electrical stimulation in the feline retina

Exploration into electrical stimulation of the retina has thus far focussed primarily upon the development of prostheses targeted at one of two sites of intervention - the epi- and sub-retinal surfaces. These two approaches have sound, logical merit owing to their proximity to retinal neurons and their potential to deliver stimuli via the surviving retinal neural networks respectively. There is increasing evidence, however, that electric field effects, electrode engineering limitations, and electrode-tissue interactions limit the spatial resolution that once was hoped could be elicited from electrical stimulation at epi- and sub-retinal sites. An alternative approach has been proposed that places a stimulating electrode array within the supra-choroidal space - that is, between the sclera and the choroid. Here we investigate whether discrete, cortical activity patterns can be elicited via electrical stimulation of a feline retina using a custom, 14 channel, silicone rubber and Pt electrode array arranged in two hexagons comprising seven electrodes each. Cortical responses from Areas 17/18 were acquired using a silicon-based, multi-channel, penetrating probe developed at IMTEK, University of Freiburg, within the European research project NeuroProbes. Multi-unit spike activity was recorded in synchrony with the presentation of electrical stimuli. Results show that distinct cortical response patterns could be elicited from each hexagon separated by 1.8 mm (center-to-center) with a center-to-center electrode spacing within each hexagon of 0.55 mm. This lends support that higher spatial resolution may also be discerned.

Hybrid microprobes for chronic implantation in the cerebral cortex

This paper reports on a neural device for chronic implantation into the cerebral cortex. Silicon microprobes with 36 electrodes arranged on four shafts are fabricated using MEMS technology. The hybrid integration of a ribbon cable with high flexibility provides the connection of the electrodes to external instrumentation. Crosstalk between the channels is investigated, as well as the electrode stability for a time period of one month in vitro. Due to the geometry and the mechanical stability of these microprobes, insertions are possible without the need for prior opening of the dura mater. A dedicated insertion tool has been fabricated to achieve a precise insertion of the microprobes and their subsequent mechanical decoupling. Additionally, a protection chamber allowing the secure attachment of two connector units on the skull is introduced. The short-time chronic implantation of microprobes showed that neural activity can be recorded, including single unit activity, which was present after four days.

A 3D slim-base probe array for in vivo recorded neuron activity

This paper introduces the first experimental results of a new implantable slim-base three-dimensional (3D) probe array for cerebral applications. The probes are assembled perpendicularly into the slim-base readout platform where electrical and mechanical connections are achieved simultaneously. A new type of micromachined interconnect has been developed to establish electrical connection using extreme planarization techniques. Due to the modular approach of the platform, probe arrays of different dimensions and functionality can be assembled. The platform is only several hundred microns thick which is highly relevant for chronic experiments in which the probe array should be able to float on top of the brain. Preliminary tests were carried out with the implantation of a probe array into the auditory cortex of a rat.

[Results of the large intestine resection in elderly patients]

The colorectal carcinoma incidence increases with age. The radical resection procedure significantly extends the survival period, when compared with other therapeutic approaches. The tissue damage may exceed the organ reserve capacity in cases of the elderly patients and may result in higher postoperative morbidity and mortality rates. The aim of this study was to compare the results and the surgical risks of the large intestine carcinoma resection procedure in elderly patients, compared to younger patients with the same diagnosis.

THE PATIENT GROUP AND METHODOLOGY

The retrospective study summons up the clinical results of 3778 patients from all over the Czech Republic, who underwent primeoperations for the following diagnoses: C18--a malignant neoplasm of the large intestine, and C19--a malignant neoplasm of the rectosigmoideal junction, in 2001. The results are compared with our own patient group in the same time-period. The results were assessed according to the following age-group criteria: 21-59 yrs., 60-69 yrs. and over 70 yrs. of age. We assessed the following factors: age, diagnosis, incidence of early postoperative complications and duration of patients hospitalization.

RESULTS

The patients in the 21-59 year-group and in the group over 70 years of age, had significantly different rates of early postoperative complications (12.3% vs 17.6%, p < 0.001). The rate of complications was twice as high in urgent procedures compared to planned procedures in all age groups (p < 0.001). The average hospitalization lasted 14.8 +/- 10.9 days. We discovered statistically significant differences in the duration of hospitalization among all three age groups respectively (p < 0.01).

CONCLUSION

Based on our results, we believe the age itself not be an indication-limiting factor for the radical resection procedure for the large intestine carcinoma. The elderly patients benefit from its oncological radicality with acceptable rates of the postoperative complications risks. We believe even extensive surgical procedures to be feasible in cases of appropriately indicated elderly patients, and their surgical risks to be acceptable considering the expected benefits for the respective patient.

[Results of rectal resection procedures at the First Surgical Clinic of the First Medical Faculty of Charles University]

Conventional surgical techniques play an important role in rectal cancer. Dehiscence of the anastomosis after low anterior resection of the rectum is a serious complication. The incidence of dehiscences can be reduced when known principles of preoperative care are respected but in particular by correct surgical technique. In 92 patients operated for rectal cancer at First Surgical Clinic of Charles University we had six patients (6.5%) with dehiscences of anastomosis. The serious character of this surgical complication can be reduced by a primary derivative stomy. Authors recommend implementing a preventive ileostomy in low resection of the rectum in high-risk patients.

[Local staging of rectal carcinoma--comparison of endorectal ultrasonography and CT]

Correct staging of adenocarcinoma of the rectum is mandatory before any therapeutic choice is made. Important features are infiltration of the perirectal fatty tissue (T3 and T4) and the presence of locoregional lymphatic spread. Computed tomography with rectal air insufflation (CT) was compared with transrectal ultrasonography (TRUS) in 212 patients. Results of the preoperative examinations were compared with histological findings. The CT examination in evaluation of perirectal spread had an accuracy rate of 76%, sensitivity of 86% and specificity of 62%, the corresponding figures for TRUS were 83%, 91% and 66%. The accuracy, sensitivity and specificity of CT for nodal involvement were 51%, 57% and 50% and of TRUS 60%, 68% and 59%. These findings confirm that TRUS is more accurate than CT in local tumour staging (T) and in detecting nodal spread (A).

[Videothoracoscopy and video-assisted surgical procedures in penetrating injuries of the thorax]

Diagnosis and treatment of the penetrating injury of the chest is quite difficult. In all types/sizes of hospitals/these injuries has to be immediately treated in surgery departments. Often decision about the optimal treatment of these injuries is quite difficult. In this paper experience with 37 cases of penetrated trauma is presented. Authors defined adequate criteria for selection of the chest tube, videothoracoscopy, video-assisted thoracic surgery (VATS), emergency thoracotomy and thoracophrenolaparotomy.

[Vesico-colonic fistulae in patients with chronic urinary tract infections]

The authors present their experience with diagnosis and treatment of colovesical fistula, which had been diagnosed due to chronic recurrent urinary tract infection. The underlying cause of the fistula was previously unrecognized diverticulosis with diverticulitis (3 out of 4 cases). The fistula was diagnosed primarily by a urologist, who performed cystoscopy, which proved to be the most contributing useful examination of all. On the other hand, coloscopy did not reveal the true diagnosis any time and its value is doubtful since insufflation of the inflamed bowel may be followed by intestinal rupture into the peritoneal cavity. Treatment of the fistulae was always surgical, during resection of the involved bowel and resection of the neighboring bladder was accomplished. In all cases one-staged procedure was done with restoration of bowel continuity and suturing of the bladder. Three patients were cured, one died on the 5th day due to complicated ischaemic heart disease.

The last twenty-five years of the American Epidemiological Society: 1972-1996

The American Epidemiological Society (AES) was founded in 1927. A history of the first 45 years of the Society was written in the early 1970s by Dr. John Rodman Paul (Yale J Biol Med 1973;46:1-84). The past 25 years have seen the AES continue as a small, relatively elite organization characterized by a membership of senior leaders in the field of epidemiology. The Society has continued to hold an annual meeting at which free, informed, and uninhibited discussion is encouraged. In this paper, the author presents an account of the affairs of the AES during the past quarter century.

[Use of collagen and gentamycin in the treatment of chronic soft tissue lesions]

The authors describe two case-histories where Garamycin-schwamm was used in the treatment of a chronic fistula and cavities in the subphrenium resulting from treatment of a subphrenic abscess, and in the pelvis minor as a result of a fistula which developed after establishment of an ileoanal intestinal pouch. They confirm the experience of authors abroad with the treatment of chronic cavities in soft tissues as a result of operations, which so far had to be treated by other methods.

[Complications of arterial ports]

The authors present an account on an unusual complication of an arterial port inserted via the a. gastroduodenalis after four doses of cytostatics thus administered after a non-anatomical resection of the right liver lobe on account of a metastasis of carcinoma of the colon. The latter caused necrosis of the hepatoduodenal ligament and formation of a fistula into the biliary tree, fistula into the venous portal circulation and thrombosis of the hepatic artery.

[Surgical and technical aspects of regional chemotherapy by means of an arterial catheter port]

Metastases of colorectal carcinoma seem the most common liver tumors in our patients. Up to date clinical studies reveal in these the best results with intraarterial chemotherapy employing continuous or intermittent infusions of fluoropyrimidins. These require permanent vascular access. Techniques of implantation in normal an abnormal vascular anatomy, methodology of catheter patency maintenance, port maintenance and salvage of malfunction catheter feature as a group of new, technical and surgical problems. Together with the simultaneously solved problems as effective anticancer agents option and way of their administration they jointly condition a favourable effect of regional chemotherapy. The technical and surgical aspects result in further indication criteria for intraarterial chemotherapy, which is then conducted in a close cooperation of a surgeon and clinical oncologist.

Foveal vision function before and after fluorescein angiography

PURPOSE

Fluorescein angiography is routinely used in ophthalmologic practice with minimal changes in vision reported by the patient after the procedure. Recent animal work has suggested that fluorescein may be cytotoxic in the presence of light and may cause retinal damage. The authors examined whether any changes occur in foveal vision function after fluorescein angiography.

METHODS

A battery of tests of vision function--including visual acuity, contrast sensitivity, color vision, and two-color increment thresholds designed to isolate individual cone pathways--was administered before and 48 hours after fluorescein angiography to a group of 10 patients with good visual acuity.

RESULTS

Most of the patients showed significant abnormalities with the nonstandard tests; however, no significant changes in central vision function were found 48 hours after fluorescein angiography.

CONCLUSION

Even sensitive vision tests show no measurable effect of fluorescein angiography on foveal vision function in eyes with significant disease.