Efficacy of the BNT162b2 mRNA COVID-19 vaccine in patients with B-cell non-Hodgkin lymphoma.

Patients diagnosed with B-cell non-Hodgkin lymphoma (B-NHL), particularly if recently treated with anti-CD20 antibodies, are at risk of severe COVID-19 disease. Because studies evaluating humoral response to COVID-19 vaccine in these patients are lacking, recommendations regarding vaccination strategy remain unclear. The humoral immune response to BNT162b2 messenger RNA (mRNA) COVID-19 vaccine was evaluated in patients with B-NHL who received 2 vaccine doses 21 days apart and compared with the response in healthy controls. Antibody titer, measured by the Elecsys Anti-SARS-CoV-2S assay, was evaluated 2 to 3 weeks after the second vaccine dose. Patients with B-NHL (n = 149), aggressive B-NHL (a-B-NHL; 47%), or indolent B-NHL (i-B-NHL; 53%) were evaluated. Twenty-eight (19%) were treatment naïve, 37% were actively treated with a rituximab/obinutuzumab (R/Obi)-based induction regimen or R/Obi maintenance, and 44% had last been treated with R/Obi >6 months before vaccination. A seropositive response was achieved in 89%, 7.3%, and 66.7%, respectively, with response rates of 49% in patients with B-NHL vs 98.5% in 65 healthy controls (P < .001). Multivariate analysis revealed that longer time since exposure to R/Obi and absolute lymphocyte count ≥0.9 × 103/µL predicted a positive serological response. Median time to achieve positive serology among anti-CD20 antibody-treated patients was longer in i-B-NHL vs a-B-NHL. The humoral response to BNT162b2 mRNA COVID-19 vaccine is impaired in patients with B-NHL who are undergoing R/Obi treatment. Longer time since exposure to R/Obi is associated with improved response rates to the COVID-19 vaccine. This study is registered at www.clinicaltrials.gov as #NCT04746092.

Parallel transmit excitation at 1.5 T based on the minimization of a driving function for device heating.

PURPOSE: To provide a rapid method to reduce the radiofrequency (RF) E-field coupling and consequent heating in long conductors in an interventional MRI (iMRI) setup. METHODS: A driving function for device heating (W) was defined as the integration of the E-field along the direction of the wire and calculated through a quasistatic approximation. Based on this function, the phases of four independently controlled transmit channels were dynamically changed in a 1.5 T MRI scanner. During the different excitation configurations, the RF induced heating in a nitinol wire immersed in a saline phantom was measured by fiber-optic temperature sensing. Additionally, a minimization of W as a function of phase and amplitude values of the different channels and constrained by the homogeneity of the RF excitation field (B1) over a region of interest was proposed and its results tested on the benchtop. To analyze the validity of the proposed method, using a model of the array and phantom setup tested in the scanner, RF fields and SAR maps were calculated through finite-difference time-domain (FDTD) simulations. In addition to phantom experiments, RF induced heating of an active guidewire inserted in a swine was also evaluated. RESULTS: In the phantom experiment, heating at the tip of the device was reduced by 92% when replacing the body coil by an optimized parallel transmit excitation with same nominal flip angle. In the benchtop, up to 90% heating reduction was measured when implementing the constrained minimization algorithm with the additional degree of freedom given by independent amplitude control. The computation of the optimum phase and amplitude values was executed in just 12 s using a standard CPU. The results of the FDTD simulations showed similar trend of the local SAR at the tip of the wire and measured temperature as well as to a quadratic function of W, confirming the validity of the quasistatic approach for the presented problem at 64 MHz. Imaging and heating reduction of the guidewire were successfully performed in vivo with the proposed hardware and phase control. CONCLUSIONS: Phantom and in vivo data demonstrated that additional degrees of freedom in a parallel transmission system can be used to control RF induced heating in long conductors. A novel constrained optimization approach to reduce device heating was also presented that can be run in just few seconds and therefore could be added to an iMRI protocol to improve RF safety.

Use of independent component analysis to improve signal-to-noise ratio in multi-probe fluorescence microscopy.

In conventional multi-probe fluorescence microscopy, narrow bandwidth filters on detectors are used to avoid bleed-through artefacts between probes. The limited bandwidth reduces the signal-to-noise ratio of the detection, often severely compromising one or more channels. Herein, we describe a process of using independent component analysis to discriminate the position of different probes using only a dichroic mirror to differentiate the signals directed to the detectors. Independent component analysis was particularly effective in samples where the spatial overlap between the probes is minimal, a very common case in cellular microscopy. This imaging scheme collects nearly all of the emitted light, significantly improving the image signal-to-noise ratio. In this study, we focused on the detection of two fluorescence probes used in vivo, NAD(P)H and ANEPPS. The optimal dichroic mirror cutoff frequency was determined with simulations using the probes spectral emissions. A quality factor, defined as the cross-channel contrast-to-noise ratio, was optimized to maximize signals while maintaining spatial discrimination between the probes after independent component analysis post-processing. Simulations indicate that a ∼3 fold increase in signal-to-noise ratio using the independent component analysis approach can be achieved over the conventional narrow-band filtering approach without loss of spatial discrimination. We confirmed this predicted performance from experimental imaging of NAD(P)H and ANEPPS in mouse skeletal muscle, in vivo. For many multi-probe studies, the increased sensitivity of this 'full bandwidth' approach will lead to improved image quality and/or reduced excitation power requirements.

Motion compensation for in vivo subcellular optical microscopy.

In this review, we focus on the impact of tissue motion on attempting to conduct subcellular resolution optical microscopy, in vivo. Our position is that tissue motion is one of the major barriers in conducting these studies along with light induced damage, optical probe loading as well as absorbing and scattering effects on the excitation point spread function and collection of emitted light. Recent developments in the speed of image acquisition have reached the limit, in most cases, where the signal from a subcellular voxel limits the speed and not the scanning rate of the microscope. Different schemes for compensating for tissue displacements due to rigid body and deformation are presented from tissue restriction, gating, adaptive gating and active tissue tracking. We argue that methods that minimally impact the natural physiological motion of the tissue are desirable because the major reason to perform in vivo studies is to evaluate normal physiological functions. Towards this goal, active tracking using the optical imaging data itself to monitor tissue displacement and either prospectively or retrospectively correct for the motion without affecting physiological processes is desirable. Critical for this development was the implementation of near real time image processing in conjunction with the control of the microscope imaging parameters. Clearly, the continuing development of methods of motion compensation as well as significant technological solutions to the other barriers to tissue subcellular optical imaging in vivo, including optical aberrations and overall signal-to-noise ratio, will make major contributions to the understanding of cell biology within the body.

Rapid overlapping-volume acquisition and reconstruction (ROVAR): automated 3D tiling for high-resolution, large field-of-view optical microscopy.

Micrometer-scale three-dimensional data from fluorescence microscopes offer unique insight into cellular morphology and function by resolving subcellular locations of fluorescent dyes and proteins. To increase field-of-view size while using a high-resolution multiphoton microscope, we have created an automated system of rapidly acquiring overlapping image stacks from multiple fields-of-view along a nonplanar tissue surface. Each image stack is acquired only between the surface and the maximal penetrating depth, as determined by the image signal-to-background ratio. This results in the acquisition of the volume containing visible tissue along the tissue surface, excluding the empty volume above the tissue and the volume beyond the maximum imaging depth within the tissue. The automated collection of overlapping volumes is followed by reconstruction that can efficiently generate a single three-dimensional volume of the tissue surface. This approach yields data spanning multiple millimetres at micrometre resolution that is faster while requiring less work from the microscope operator. The advantages of the system are demonstrated by acquisition of data from intact, unfixed organs without a coverglass both in vivo and in situ.

Optimizing multiphoton fluorescence microscopy light collection from living tissue by noncontact total emission detection (epiTED).

A benefit of multiphoton fluorescence microscopy is the inherent optical sectioning that occurs during excitation at the diffraction-limited spot. The scanned collection of fluorescence emission is incoherent; that is, no real image needs to be formed on the detector plane. The nearly isotropic emission of fluorescence excited at the focal spot allows for new detection schemes that efficiently funnel all attainable photons to detector(s). We previously showed [Combs, C.A., et al. (2007) Optimization of multiphoton excitation microscopy by total emission detection using a parabolic light reflector. J. Microsc. 228, 330-337] that parabolic mirrors and condensers could be combined to collect the totality of solid angle around the excitation spot for tissue blocks, leading to ∼8-fold signal gain. Using a similar approach, we have developed an in vivo total emission detection (epiTED) instrument modified to make noncontact images from outside of living tissue. Simulations suggest that a ∼4-fold enhancement may be possible (much larger with lower NA objectives than the 0.95 NA used here) with this approach, depending on objective characteristics, imaging depth and the characteristics of the sample being imaged. In our initial prototype, 2-fold improvements were demonstrated in the mouse brain and skeletal muscle as well as the rat kidney, using a variety of fluorophores and no compromise of spatial resolution. These results show this epiTED prototype effectively doubles emission signal in vivo; thus, it will maintain the image signal-to-noise ratio at two times the scan rate or enable full scan rate at approximately 30% reduced laser power (to minimize photo-damage).

Two-photon excitation fluorescence pH detection using 2,3-dicyanohydroquinone: a spectral ratiometric approach.

The use of 2,3-dicyanohydroquinone (DCHQ) as an emission ratiometric probe of pH in vitro and in fibroblast cells was evaluated using two-photon excitation fluorescence microscopy (TPEFM). In addition, methods for spectrally calibrating the Zeiss LSM510 META spectroscopy system for TPEFM were also developed. The emissions of both the acid and base forms of DCHQ were detectable when using an 800-nm excitation in TPEFM, thereby allowing ratiometric determination of pH. These data suggest that, in contrast to most other emission ratiometric probes, both acid and base forms of DCHQ have similar two-photon cross-sectional areas at 800 nm. Acid (maximum at approximately 457 nm) and base (maximum at approximately 489 nm) DCHQ TPEFM emission spectra were similar to previously reported one-photon excitation emission spectra. Calibration curves for pH were successfully constructed using the ratio of DCHQ emission difference maxima at 460 nm and 512 nm in vitro and in cells. To our knowledge, DCHQ is currently the only effective emission ratiometric pH indicator for two-photon microscopy and may serve as a useful starting point for the development of other TPEFM ratiometric dyes for quantitative measurement of other cell parameters such as Ca2+, Mg2+ or Na+.

Fluctuation analysis of mitochondrial NADH fluorescence signals in confocal and two-photon microscopy images of living cardiac myocytes.

A fluctuation analysis was performed on the reduced nicotine adenine dinucleotide (NADH) fluorescence signal from resting rabbit myocytes using confocal and two-photon microscopy. The purpose of this study was to establish whether any co-ordinated biochemical processes, such as binding, metabolism and inner mitochondrial membrane potential, were contributing to NADH signal fluctuations above background instrument noise. After a basic characterization of the instrument noise, time series of cellular NADH fluorescence images were collected and compared with an internal standard composed of NADH in the bathing medium. The coefficient of variation as a function of mean signal amplitude of cellular NADH fluorescence and bathing media NADH was identical even as a function of temperature. These data suggest that the fluctuations in cellular NADH fluorescence in resting myocytes are dominated by sampling noise of these instruments and not significantly modified by biological processes. Further analysis revealed no significant spatial correlations within the cell, and Fourier analysis revealed no coherent frequency information. These data suggest that the impact of biochemical processes, which might affect cellular NADH fluorescence emission, are either too small in magnitude, occurring in the wrong temporal scale or too highly spatially localized for detection using these standard optical microscopy approaches.

Arterial wall MRI characteristics are associated with elevated serum markers of inflammation in humans.

Inflammation contributes to atherosclerosis, but assessment in humans is largely restricted to measurement of markers in blood. We determined whether MRI properties of large arteries were associated with markers of inflammation in serum. Double inversion recovery, fast spin-echo images of the common carotid arteries and infrarenal aorta were obtained at 1.5 T both before and after gadolinium-DTPA (0.1 mmol/kg) in 52 subjects > or =40 years of age, 17 of whom had no risk factors for atherosclerosis and thus served as controls. Twenty-two study participants had increases in wall thickness (14), T2-weighted signal intensity (11), and/or contrast enhancement values (7) that were >2 standard deviations (SDs) from control group mean values. Ten subjects in this group had evidence of focal plaques in the carotids (5) and/or aorta (6). Compared with the remaining 30 subjects, these 22 had significantly higher levels of interleukin-6 (3.53 +/- 2.46 vs. 1.97 +/- 1.37 pg/mL, P = 0.004), C-reactive protein (0.56 +/- 0.98 vs. 0.30 +/- 0.52 mg/dL, P = 0.019), vascular cell adhesion molecule-1 (572 +/- 153 vs. 471 +/- 130 ng/mL, P = 0.012), and intercellular adhesion molecule-1 (244 +/- 80 vs. 202 +/- 45 ng/mL, P = 0.015), and nonsignificant differences in levels of E-selectin (46.1 +/- 18.9 vs. 42.3 +/- 11.3 ng/mL, P = 0.369). Thus, MRI characteristics of the aorta and carotid arteries were associated with elevated serum markers of inflammation, frequently in the absence of definite atheroma. MRI of large arteries may provide a new approach to investigate the contribution of inflammation to atherogenesis.

Challenges in small animal noninvasive imaging.

The current status and challenges of small animal non-invasive imaging is briefly reviewed. The advantages of non-invasive studies on living animals versus post-mortem studies are evaluated. An argument is advanced that even in post-mortem situations, non-invasive imaging may play an important role in efficiently characterizing small animal phenotypes as well as pathology. Issues of data interpretation under anesthetized conditions in live animal studies are also reviewed. The five imaging technologies covered include CT, PET, ultrasound, MRI and optical imaging. The structural and physiological information content of these different modalities is reviewed along with the ability of these techniques to scale down for use in small mammals such as mice and rats. In general, it was found that most of these technologies scale favorably to the study of small mammals, generally providing more physiological information than when used on the larger human scale. This suggests that these types of small mammal imaging capabilities will play a very significant role in the full utilization of these important animal models in biomedical research.

Simulation of cardiac work transitions, in vitro: effects of simultaneous Ca2+ and ATPase additions on isolated porcine heart mitochondria.

During increases in cardiac work there are net increases in cytosolic [Ca(2+)] and ATP hydrolysis by myofiliments and ion transport ATPases. However, it is still unclear what role Ca(2+)or the ATP hydrolysis products, ADP and Pi, have on the regulation of mitochondrial ATP production. In this study, work jumps were simulated by simultaneous additions of Ca(2+) and ATPase to porcine heart mitochondria. The net effects on the mitochondrial ATP production were monitored by simultaneously monitoring respiration (mVo2), [NADH], [ADP] and membrane potential (deltapsi) at 37 degrees C. Addition of exogenous ATPase (300 mlU.ml(-1))]ATP (3.4 mM) was used to generate a 'resting' background production of ADP. This resting metabolic rate was 200% higher than the quiescent rate while [NADH] and deltapsi were reduced. Subsequent ATPase additions (1.3IU.ml(-)) were made with varying amounts of Ca(2+)(0 to 535 nM) to simulate step increases in cardiac work. Ca(2+) additions increased mVo2 and depolarized deltapsi, and were consistent with an activation of Fo/F1)ATPase. In contrast, Ca(2+) reduced the [NADH] response to the ATPase addition, consistent with Ca(2+)-sensitive dehydrogenase activity (CaDH). The calculated free ADP response to ATPase decreased \2-fold in the presence of Ca(2+). The addition of 172nM free Ca(2+)] ATPase increased mVo2 by 300% (P<0.05, n=8) while deltapsi decreased by 14.9+/-0.1 mV without changes in [NADH] (P > or =0.05, n=8), consistent with working heart preparations. The addition of Ca(2+) and ATPase combined increased the mitochondrial ATP production rate with changes in deltapsi, NADH and [ADP], consistent with an activation of CaDH and F o /F(1)ATPase activity. These balancing effects of ATPase activity and [Ca(2+)] may explain several aspects of metabolic regulation in the heart during work transitions in vivo.

Nitric oxide synthase in porcine heart mitochondria: evidence for low physiological activity.

The capacity of isolated porcine heart mitochondria to produce nitric oxide (NO) via mitochondrial NO synthase (NOS) was evaluated. The mitochondrial NOS content and activity (0.2 nmol NO x mg mitochondrial protein(-1) x min(-1)) were approximately 10 times lower than previously reported for the rat liver. No evidence for mitochondrial NOS-generated NO was found in mitochondrial suspensions based on the lack of NO production and the lack of effect of either L-arginine or NOS inhibitors on the rate of respiration. The reason that even the low mitochondrial NOS activity did not result in net NO production and metabolic effects is because the mitochondrial metabolic breakdown of NO (1-4 nmol NO x mg mitochondrial protein(-1) x min(-1)) was greater than the maximum rate of NO production measured in homogenates. These data suggest that NO production at the mitochondria via NOS is not a significant source of NO in the intact heart and does not regulate cardiac oxidative phosphorylation.

Direct imaging of dehydrogenase activity within living cells using enzyme-dependent fluorescence recovery after photobleaching (ED-FRAP).

Reduced nicotine adenine dinucleotide (NADH) is a key metabolite involved in cellular energy conversion and many redox reactions. We describe the use of confocal microscopy in conjunction with enzyme-dependent fluorescence recovery after photobleaching (ED-FRAP) of NADH as a topological assay of NADH generation capacity within living cardiac myocytes. Quantitative validation of this approach was performed using a dehydrogenase system, in vitro. In intact cells the NADH ED-FRAP was sensitive to temperature (Q(10) of 2.5) and to dehydrogenase activation by dichloroacetate or cAMP (twofold increase for each). In addition, NADH ED-FRAP was correlated with flavin adenine dinucleotide (FAD(+)) fluorescence. These data, coupled with the cellular patterns of NADH ED-FRAP changes with dehydrogenase stimulation, suggest that NADH ED-FRAP is localized to the mitochondria. These results suggest that ED-FRAP enables measurement of regional dynamics of mitochondrial NADH production in intact cells, thus providing information regarding region-specific intracellular redox reactions and energy metabolism.

Device-dependent activity estimation and decay correction of radionuclide mixtures with application to Tc-94m PET studies.

Multi-instrument activity estimation and decay correction techniques were developed for radionuclide mixtures, motivated by the desire for accurate quantitation of Tc-94m positron emission tomography (PET) studies. Tc-94m and byproduct Tc isotopes were produced by proton irradiation of enriched Mo-94 and natural Mo targets. Mixture activities at the end of bombardment were determined with a calibrated high purity germanium detector. The activity fractions of the greatest mixture impurities relative to 100% for Tc-94m averaged 10.0% (Tc-94g) and 3.3% (Tc-93) for enriched targets and 10.1% (Tc-94g), 11.0% (Tc-95), 255.8% (Tc-96m), and 7.2% (Tc-99m) for natural targets. These radioisotopes have different half-lives (e.g., 52.5 min for Tc-94m, 293 min for Tc-94g), positron branching ratios (e.g., 0.72 for Tc-94m, 0.11 for Tc-94g) and gamma ray emissions for themselves and their short-lived, excited Mo daughters. This complicates estimation of injected activity with a dose calibrator, in vivo activity with PET and blood sample activity with a gamma counter. Decay correction using only the Tc-94m half-life overestimates activity and is inadequate. For this reason analytic formulas for activity estimation and decay correction of radionuclide mixtures were developed. Isotope-dependent sensitivity factors for a PET scanner, dose calibrator, and gamma counter were determined using theoretical sensitivity models and fits of experimental decay curves to sums of exponentials with fixed decay rates. For up to 8 h after the end of bombardment with activity from enriched and natural Mo targets, decay-corrected activities were within 3% of the mean for three PET studies of a uniform cylinder, within 3% of the mean for six dose calibrator decay studies, and within 6% of the mean for four gamma counter decay studies. Activity estimation and decay correction for Tc-94m mixtures enable routine use of Tc-94m in quantitative PET, as illustrated by application to a canine Tc-94m sestamibi study.

Calcium activation of heart mitochondrial oxidative phosphorylation: rapid kinetics of mVO2, NADH, AND light scattering.

Parallel activation of heart mitochondria NADH and ATP production by Ca(2+) has been shown to involve the Ca(2+)-sensitive dehydrogenases and the F(0)F(1)-ATPase. In the current study we hypothesize that the response time of Ca(2+)-activated ATP production is rapid enough to support step changes in myocardial workload ( approximately 100 ms). To test this hypothesis, the rapid kinetics of Ca(2+) activation of mV(O(2)), [NADH], and light scattering were evaluated in isolated porcine heart mitochondria at 37 degrees C using a variety of optical techniques. The addition of Ca(2+) was associated with an initial response time (IRT) of mV(O(2)) that was dose-dependent with a minimum IRT of 0.27 +/- 0.02 s (n = 41) at 535 nm Ca(2+). The IRTs for NADH fluorescence and light scattering in response to Ca(2+) additions were similar to mV(O(2)). The Ca(2+) IRT for mV(O(2)) was significantly shorter than 1.6 mm ADP (2.36 +/- 0.47 s; p < or = 0.001, n = 13), 2.2 mm P(i) (2.32 +/- 0.29, p < or = 0.001, n = 13), or 10 mm creatine (15.6.+/-1.18 s, p < or = 0.001, n = 18) under similar experimental conditions. Calcium effects were inhibited with 8 microm ruthenium red (2.4 +/- 0.31 s; p < or = 0.001, n = 16) and reversed with EGTA (1.6 +/- 0.44; p < or = 0.01, n = 6). Estimates of Ca(2+) uptake into mitochondria using optical Ca(2+) indicators trapped in the matrix revealed a sufficiently rapid uptake to cause the metabolic effects observed. These data are consistent with the notion that extramitochondrial Ca(2+) can modify ATP production, via an increase in matrix Ca(2+) content, rapidly enough to support cardiac work transitions in vivo.

Determination of pH using water protons and chemical exchange dependent saturation transfer (CEST).

Solution pH was measured using water proton NMR via chemical exchange dependent saturation transfer (CEST) with selected chemical exchange sites. Several useful pH-sensitive proton chemical exchange agents were found: 5,6-dihydrouracil, 5-hydroxytryptophan, and a combination of 5-hydroxytryptophan and 2-imidazolidinethione. A ratiometric approach was developed that permitted pH determinations that were independent of water T(1) or exchange site concentration.

Imaging of urea using chemical exchange-dependent saturation transfer at 1.5T.

The purpose of this study was to screen for slow proton chemical exchange between water and kidney metabolites using a standard clinical 1.5-T scanner. Imaging was performed using a fast spin-echo sequence with a magnetization transfer (MT) preparation pulse train. Off-resonance saturation ranging from +/-50 to +/-1000 Hz was used on urea and urine phantoms and normal human subjects imaged through the kidneys. The positive frequency was used as the control for each frequency pair. Results of frequency sweeps show an asymmetric MT effect peaking at approximately 100 Hz ( thick similar1 ppm) for urea, urine, and renal parenchyma. Varying differences (5%-25%) occurred with different human subjects. Few differences were observed from phantom water or subject muscle tissue. Chemical exchange is detectable in the kidney near 1 ppm at 1.5 T, attributable to urea. This technique was used to produce in vivo distribution maps of this metabolite in vivo.

Rapid spectrophotometric determination of oxygen consumption using hemoglobin, in vitro: light scatter correction and expanded dynamic range.

The method of using absorbance in conjunction with hemoglobin (Hb) to monitor rapid changes in oxygen consumption in vitro was improved by using a non-linear calibration technique and multiwavelength spectroscopy. The O(2) dependence of Hb absorbance was effectively linearized using the current technique (R(2) = 0.990+/-0.002, n = 3), and extended the dynamic range of [O(2)] determinations by 1.6-fold over previous approaches. The association/dissociation rates of O(2) and Hb were evaluated using the current approach and were not significant on the 100-ms time domain. A method was also developed for compensating for large amplitude light scattering changes in turbid media using multiwavelength analysis. Both the nonlinear calibration curve and light scattering corrections were validated in isolated porcine heart mitochondrial preparations.