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Doppler imaging detects bacterial infection of living tissue.

ABSTRACT: Living 3D in vitro tissue cultures, grown from immortalized cell lines, act as living sentinels as pathogenic bacteria invade the tissue. The infection is reported through changes in the intracellular dynamics of the sentinel cells caused by the disruption of normal cellular function by the infecting bacteria. Here, the Doppler imaging of infected sentinels shows the dynamic characteristics of infections. Invasive Salmonella enterica serovar Enteritidis and Listeria monocytogenes penetrate through multicellular tumor spheroids, while non-invasive strains of Escherichia coli and Listeria innocua remain isolated outside the cells, generating different Doppler signatures. Phase distributions caused by intracellular transport display Lévy statistics, introducing a Lévy-alpha spectroscopy of bacterial invasion. Antibiotic treatment of infected spheroids, monitored through time-dependent Doppler shifts, can distinguish drug-resistant relative to non-resistant strains. This use of intracellular Doppler spectroscopy of living tissue sentinels opens a new class of microbial assay with potential importance for studying the emergence of antibiotic resistance.

SUBMITTER: Choi H

PROVIDER: S-EPMC7876006 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Doppler imaging detects bacterial infection of living tissue.

Choi Honggu H Li Zhe Z Hua Zhen Z Zuponcic Jessica J Ximenes Eduardo E Turek John J JJ Ladisch Michael R MR Nolte David D DD

Communications biology 20210210 1

Living 3D in vitro tissue cultures, grown from immortalized cell lines, act as living sentinels as pathogenic bacteria invade the tissue. The infection is reported through changes in the intracellular dynamics of the sentinel cells caused by the disruption of normal cellular function by the infecting bacteria. Here, the Doppler imaging of infected sentinels shows the dynamic characteristics of infections. Invasive Salmonella enterica serovar Enteritidis and Listeria monocytogenes penetrate throu ...[more]

PMID: 33568744

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Project description:BackgroundCardiotoxic effects of anthracycline therapy are a major cause of morbidity for childhood cancer survivors. The aim of this retrospective evaluation is to assess the efficacy of Tissue Doppler Imaging in the early detection of myocardial alterations in these patients.MethodsA population of 50 childhood cancer survivors (32 males and 18 females) who have been treated with anthracyclines was evaluated by standard and TDI echocardiographic examination of the basal and median region of the interventricular septum (IVSb, IVSm), of the left ventricular posterior wall (LVPWb, LVPWm), and of the mitral annulus; the results were compared with those obtained from a population of 50 healthy age-matched and sex-matched controls by using the Student test. The clinical and echocardiographic data of the two groups were compared also with the independent samples t-test. All data were expressed as mean ± standard deviation. A two-tailed P-value < 0.05 was considered statistically significant. Statistical analysis was performed using STATA 7.0.ResultsThe case-control analysis showed statistically significant differences (p < 0,05) between the patients and the controls values. The systolic performance of the patients was normal (LVEF (p = 0,0029) and LVFS (p = 0,0002)). Statistically significant differences between patients and controls were found for diastolic function measurements obtained with PW Doppler such as IVRT (p = 0,0000), DT (p = 0,0041), E (p = 0,0000), A (p = 0,0458), even if E/A ratio was not altered. TDI analysis also show significant differences between patients and controls in both LVPW and IVS (basal and middle segments); E/E' ratio and E'/A' ratio did not vary significantly. Linear Regression and multivariate analysis showed that Hematopoietic Stem Cell Transplantation had the highest impact on our measurements.ConclusionsThe results showed a myocardial diastolic impairment with preserved ejection fraction. Since the median follow-up time of our cohort was 2 years, further evaluation is needed to better define the diastolic alterations. TDI analysis showed high sensitivity for the detection of mild myocardial dysfunction; the implementation of this novel method as standard practice in the follow-up of selected childhood cancer survivors might help to achieve a better management of long-term complications of cardiotoxic chemotherapy.

Project description:Two structurally related fluorescent imaging probes allow optical imaging of bacterial leg infection models in living athymic and immunocompetent mice. Structurally, the probes are comprised of a deep-red fluorescent squaraine rotaxane scaffold with two appended bis(zinc(II)-dicolylamine) (bis(Zn-DPA)) targeting ligands. The bis(Zn-DPA) ligands have high affinity for the anionic phospholipids and related biomolecules that reside within the bacterial envelope, and they are known to selectively target bacterial cells over the nearly uncharged membrane surfaces of healthy mammalian cells. Planar, whole-animal optical imaging studies showed that intravenous dosing of either probe (10 nmol) allowed imaging of localized infections of Gram-positive Staphylococcus aureus and Gram-negative Salmonella enterica serovar typhimurium. High selectivity for the infected target leg (T) over the contralateral nontarget leg (NT) was reflected by T/NT ratios up to six. The infection imaging signal was independent of mouse humoral immune status, and there was essentially no targeting at a site of sterile inflammation induced by injection of lambda-carrageenan. Furthermore, the fluorescent probe imaging signal colocalized with the bioluminescence signal from a genetically engineered strain of S. enterica serovar typhimurium. Although not highly sensitive (the localized infection must contain at least approximately 10(6) colony forming units for fluorescence visualization), the probes are remarkably selective for bacterial cells considering their low molecular weight (<1.5 kDa) and simple structural design. The more hydrophilic of the two probes produced a higher T/NT ratio in the early stages of the imaging experiment and washed out more rapidly from the blood clearance organs (liver, kidney). Therefore, it is best suited for longitudinal studies that require repeated dosing and imaging of the same animal. The results indicate that fluorescent probes based on squaraine rotaxanes should be broadly useful for in vivo animal imaging studies, and they further validate the ability of imaging probes with bis(Zn-DPA) ligands to selectively target bacterial infections in living animals.

Project description:Rationale: Tissue Doppler imaging (TDI) is an echocardiographic method that measures the velocity of moving tissue.Objectives: We applied this technique to the diaphragm to assess the velocity of diaphragmatic muscle motion during contraction and relaxation.Methods: In 20 healthy volunteers, diaphragmatic TDI was performed to assess the pattern of diaphragmatic motion velocity, measure its normal values, and determine the intra- and interobserver variability of measurements. In 116 consecutive ICU patients, diaphragmatic excursion, thickening, and TDI parameters of peak contraction velocity, peak relaxation velocity, velocity-time integral, and TDI-derived maximal relaxation rate were assessed during weaning. In a subgroup of 18 patients, transdiaphragmatic pressure (Pdi)-derived parameters (peak Pdi, pressure-time product, and diaphragmatic maximal relaxation rate) were recorded simultaneously with TDI.Measurements and Main Results: In terms of reproducibility, the intercorrelation coefficients were >0.89 for all TDI parameters (P < 0.001). Healthy volunteers and weaning success patients exhibited lower values for all TDI parameters compared with weaning failure patients, except for velocity-time integral, as follows: peak contraction velocity, 1.35 ± 0.34 versus 1.50 ± 0.59 versus 2.66 ± 2.14 cm/s (P < 0.001); peak relaxation velocity, 1.19 ± 0.39 versus 1.53 ± 0.73 versus 3.36 ± 2.40 cm/s (P < 0.001); and TDI-maximal relaxation rate, 3.64 ± 2.02 versus 10.25 ± 5.88 versus 29.47 ± 23.95 cm/s2 (P < 0.001), respectively. Peak contraction velocity was strongly correlated with peak transdiaphragmatic pressure and pressure-time product, whereas Pdi-maximal relaxation rate was significantly correlated with TDI-maximal relaxation rate.Conclusions: Diaphragmatic tissue Doppler allows real-time assessment of the diaphragmatic tissue motion velocity. Diaphragmatic TDI-derived parameters differentiate patients who fail a weaning trial from those who succeed and correlate well with Pdi-derived parameters.

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Doppler imaging detects bacterial infection of living tissue.

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Doppler imaging detects bacterial infection of living tissue.

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