NIH Workshop 2018: Towards Minimally-invasive or Non-invasive Approaches to Assess Tissue Oxygenation Pre- and Post-Transfusion

Because blood transfusion is one of the most common therapeutic interventions in hospitalized patients, much recent research has focused on improving the storage quality in vitro of donor red blood cells (RBCs) that are then used for transfusion. However, there is a significant need for enhancing our understanding of the efficacy of the transfused RBCs in vivo. To this end, the NIH sponsored a one-and-a-half-day workshop that brought together experts in multiple disciplines relevant to tissue oxygenation (e.g., transfusion medicine, critical care medicine, cardiology, neurology, neonatology and pediatrics, bioengineering, biochemistry, and imaging). These individuals presented their latest findings, discussed key challenges, and aimed to construct recommendations for facilitating development of new technologies and/or biomarker panels to assess tissue oxygenation in a minimally-invasive to non-invasive fashion, before and after RBC transfusion. The workshop was structured into four sessions: (1) Global Perspective; (2) Organ Systems; (3) Neonatology; and (4) Emerging Technologies. The first day provided an overview of current approaches in the clinical setting, both from a global perspective, including the use of metabolomics for studying RBCs and tissue perfusion, and from a more focused perspective, including tissue oxygenation assessments in neonates and in specific adult organ systems. The second day focused on emerging technologies, which could be applied pre- and post-RBC transfusion, to assess tissue oxygenation in minimally-invasive or non-invasive ways. Each day concluded with an open-microphone discussion among the speakers and workshop participants. The workshop presentations and ensuing interdisciplinary discussions highlighted the potential of technologies to combine global “omics” signatures with additional measures (e.g., thenar eminence measurements or various imaging methods) to predict which patients could potentially benefit from a RBC transfusion and whether the ensuing RBC transfusion was effective. The discussions highlighted the need for collaborations across the various disciplines represented at the meeting to leverage existing technologies and to develop novel approaches for assessing RBC transfusion efficacy in various clinical settings. Although the Workshop took place in April, 2018, the concepts described and the ensuing discussions were, perhaps, even more relevant in April, 2020, at the time of writing this manuscript, during the explosive growth of the COVID-19 pandemic in the United States. Thus, issues relating to maintaining and improving tissue oxygenation and perfusion are especially pertinent because of the extensive pulmonary damage resulting from SARS-CoV-2 infection [1], compromises in perfusion caused by thrombotic-embolic phenomena [2], and damage to circulating RBCs, potentially compromising their oxygen-carrying capacity [3]. The severe end organ effects of SARS-CoV-2 infection mandate even more urgency for improving our understanding of tissue perfusion and oxygenation, improve methods for measuring and monitoring them, and develop novel ways of enhancing them

NIH Workshop 2018: Towards Minimally Invasive or Noninvasive Approaches to Assess Tissue Oxygenation Pre- and Post-transfusion

Because blood transfusion is one of the most common therapeutic interventions in hospitalized patients, much recent research has focused on improving the storage quality in vitro of donor red blood cells (RBCs) that are then used for transfusion. However, there is a significant need for enhancing our understanding of the efficacy of the transfused RBCs in vivo. To this end, the NIH sponsored a one-and-a-half-day workshop that brought together experts in multiple disciplines relevant to tissue oxygenation (eg, transfusion medicine, critical care medicine, cardiology, neurology, neonatology and pediatrics, bioengineering, biochemistry, and imaging). These individuals presented their latest findings, discussed key challenges, and aimed to identify opportunities for facilitating development of new technologies and/or biomarker panels to assess tissue oxygenation in a minimally-invasive to non-invasive fashion, before and after RBC transfusion

Symptomatic Early Congenital Syphilis: A Common but Forgotten Disease

Congenital syphilis is a severe, disabling infection often with grave consequences seen in infants. It occurs due to the transmission of the disease from an infected mother to the unborn infant through the placenta. This long forgotten disease continues to affect pregnant women resulting in perinatal morbidity and mortality. The continuing prevalence of this disease reveals the failure of control measures established for its prevention. We put forth a case of symptomatic congenital syphilis presenting with skeletal manifestations at birth, a rare finding in literature. The report stresses upon the importance of implementing the World Health Organization's recommendation that all pregnant women should be screened for syphilis in the first antenatal visit in the first trimester and again in the late pregnancy

Comparison of Sample Tubes for the X-band EPR Measurement of an Aqueous Sample: Effects on Reproducibility of Signal Intensities

Reproducibility of the X-band EPR measurement of an aqueous solution sample was compared using three different types of sample tubes, and accuracy of quantitative performance was assessed. A PTEE tubing, a glass capillary and a quartz flat cuvette were compared to get a suitable condition for quantitative measurement. An accurate 0.1 mM water solution of TEMPOL was used as a standard sample. The TEMPOL solution was loaded into one of sample tube, and the sample tube was set in the TE-mode cavity of X-band EPR spectrometer. Two procedures below were tested for reproducibility of repeated measurements. 1) The sample tube in the cavity was washed or renewed every measurement, and measurements were repeated several times with fixed EPR parameters. 2) The sample tubes in the cavity were stayed and repeatedly measured several times. Next, EPR parameters such as sweep speed, time constant, modulation width, and/or microwave power were varied to seek optimum signal intensity. The PTFE tubing showed the best reproducibility when the measurements were repeated with staying the sample tube (the ratio of standard deviation to the averaged signal intensity; SD/AV = 0.0058). When the sample and sample tube was renewed every measurement, variation of signal intensity became larger (SD/AV = 0.0333). The glass capillary had the best reproducibility in both procedures 1 and 2 (SD/AV = 0.0104 and 0.0036, respectively). The signal reproducibility of the flat cuvette was relatively low (SD/AV = 0.0400 and 0.0690 for procedures 1 and 2, respectively). However, the flat cuvette gave the largest signal intensity when the loaded volume of the sample was the identical. In conclusion, the best quantitative performance of the X-band EPR spectroscopy for a liquid sample was obtained when the measurements are carried out with the capillary

Pulsed electron paramagnetic resonance imaging: Applications in the studies of tumor physiology

Significance:Electron Paramagnetic Resonance imaging (EPRI) is a powerful technique capable of generating images of tissue oxygenation using exogenous paramagnetic probes such as trityl radicals and nitroxyl radicals. Using principles similar to Magnetic Resonance Imaging (MRI) with field gradients, the spatial distribution of the paramagnetic probecan be generated and from its spectral features, spatial maps of oxygen can be obtained from live objects. In this review, the two methods of signal acquisition, image formation/reconstruction will be described. The probes used and its application to study tumor physiology and monitor treatment response with chemotherapy drugs in mouse models of human cancer will be summarized.Recent Advances: By implementing phase encoding/Fourier reconstruction in EPRI in time-domain mode, the frequency contribution to the spatial resolution was avoided and improved images can be obtained. The highresolution EPRI revealed the pO2 change in tumor, which was useful to detect and evaluate the effects of various antitumor therapies. The coregistration with other imaging modalities provided a better understanding of hypoxia related alteration in physiology.Critical Issues: The high power of EPR irradiation and toxicity profile of radical probes are the main obstacles for clinical application. The improvement of pulse sequence may lower the risk.Future Directions:Pulsed EPR oximetry will be a powerfultool to research various disease involving hypoxia such as cancer, ischemic heart diseases, stroke, and diabetes. By optimizing radical probes, it can also be applied for various other purposes such as detecting local acid-base balance or oxidative stress

Monitoring response to a clinically relevant IDH inhibitor in glioma—Hyperpolarized 13C magnetic resonance spectroscopy approaches

BackgroundMutant isocitrate dehydrogenase (IDHmut) catalyzes 2-hydroxyglutarate (2HG) production and is considered a therapeutic target for IDHmut tumors. However, response is mostly associated with inhibition of tumor growth. Response assessment via anatomic imaging is therefore challenging. Our goal was to directly detect IDHmut inhibition using a new hyperpolarized (HP) 13C magnetic resonance spectroscopy-based approach to noninvasively assess α-ketoglutarate (αKG) metabolism to 2HG and glutamate.MethodsWe studied IDHmut-expressing normal human astrocyte (NHAIDH1mut) cells and rats with BT257 tumors, and assessed response to the IDHmut inhibitor BAY-1436032 (n ≥ 4). We developed a new 13C Echo Planar Spectroscopic Imaging sequence with an optimized RF pulse to monitor the fate of HP [1-13C]αKG and [5-12C,1-13C]αKG with a 2.5 × 2.5 × 8 mm3 spatial resolution.ResultsCell studies confirmed that BAY-1436032-treatment leads to a drop in HP 2HG and an increase in HP glutamate detectable with both HP substrates. Data using HP [5-12C,1-13C]αKG also demonstrated that its conversion to 2HG is detectable without the proximal 1.1% natural abundance [5-13C]αKG signal. In vivo studies showed that glutamate is produced in normal brains but no 2HG is detectable. In tumor-bearing rats, we detected the production of both 2HG and glutamate, and BAY-1436032-treatment led to a drop in 2HG and an increase in glutamate. Using HP [5-12C,1-13C]αKG we detected metabolism with an signal-to-noise ratio of 23 for 2HG and 17 for glutamate.ConclusionsOur findings point to the clinical potential of HP αKG, which recently received FDA investigational new drug approval for research, for noninvasive localized imaging of IDHmut status

Metabolic Landscape of a Genetically Engineered Mouse Model of IDH1 Mutant Glioma

Understanding the metabolic reprogramming of aggressive brain tumors has potential applications for therapeutics as well as imaging biomarkers. However, little is known about the nutrient requirements of isocitrate dehydrogenase 1 (IDH1) mutant gliomas. The IDH1 mutation involves the acquisition of a neomorphic enzymatic activity which generates D-2-hydroxyglutarate from α-ketoglutarate. In order to gain insight into the metabolism of these malignant brain tumors, we conducted metabolic profiling of the orthotopic tumor and the contralateral regions for the mouse model of IDH1 mutant glioma; as well as to examine the utilization of glucose and glutamine in supplying major metabolic pathways such as glycolysis and tricarboxylic acid (TCA). We also revealed that the main substrate of 2-hydroxyglutarate is glutamine in this model, and how this re-routing impairs its utilization in the TCA. Our 13C tracing analysis, along with hyperpolarized magnetic resonance experiments, revealed an active glycolytic pathway similar in both regions (tumor and contralateral) of the brain. Therefore, we describe the reprogramming of the central carbon metabolism associated with the IDH1 mutation in a genetically engineered mouse model which reflects the tumor biology encountered in glioma patients

Mitoribosome sensitivity to HSP70 inhibition uncovers metabolic liabilities of castration-resistant prostate cancer.

The androgen receptor is a key regulator of prostate cancer and the principal target of current prostate cancer therapies collectively termed androgen deprivation therapies. Insensitivity to these drugs is a hallmark of progression to a terminal disease state termed castration-resistant prostate cancer. Therefore, novel therapeutic options that slow progression of castration-resistant prostate cancer and combine effectively with existing agents are in urgent need. We show that JG-98, an allosteric inhibitor of HSP70, re-sensitizes castration-resistant prostate cancer to androgen deprivation drugs by targeting mitochondrial HSP70 (HSPA9) to suppress aerobic respiration. Rather than impacting androgen receptor stability as previously described, JG-98's primary effect is inhibition of mitochondrial translation, leading to disruption of electron transport chain activity. Although functionally distinct from HSPA9 inhibition, direct inhibition of the electron transport chain with a complex I or II inhibitor creates a similar physiological state capable of re-sensitizing castration-resistant prostate cancer to androgen deprivation therapies. These data identify a significant role for HspA9 in mitochondrial ribosome function and highlight an actionable metabolic vulnerability of castration-resistant prostate cancer