Acute exposure to space flight results in evidence of reduced lymph Transport, tissue fluid Shifts, and immune alterations in the rat gastrointestinal system.

Space flight causes a number of alterations in physiological systems, changes in the immunological status of subjects, and altered interactions of the host to environmental stimuli. We studied the effect of space flight on the lymphatic system of the gastrointestinal tract which is responsible for lipid transport and immune surveillance which includes the host interaction with the gut microbiome. We found that there were signs of tissue damage present in the space flown animals that was lacking in ground controls (epithelial damage, crypt morphological changes, etc.). Additionally, morphology of the lymphatic vessels in the tissue suggested a collapsed state at time of harvest and there was a profound change in the retention of lipid in the villi of the ileum. Contrary to our assumptions there was a reduction in tissue fluid volume likely associated with other fluid shifts described. The reduction of tissue fluid volume in the colon and ileum is a likely contributing factor to the state of the lymphatic vessels and lipid transport issues observed. There were also associated changes in the number of MHC-II+ immune cells in the colon tissue, which along with reduced lymphatic competence would favor immune dysfunction in the tissue. These findings help expand our understanding of the effects of space flight on various organ systems. It also points out potential issues that have not been closely examined and have to potential for the need of countermeasure development.

Effect of Electroacupuncture on 99mTc-Sodium Pertechnetate Uptake and Extracellular Fluid Free Molecules in the Stomach in Acupoint ST36 and ST39.

Electroacupuncture (EA) is a therapeutic modality in which the electrical stimulation is integrated with concepts of acupuncture to treat diseases. This study was designed to evaluate the connection between the electro-acupuncture induced increase in Na99mTcO4 uptake in the stomach wall, and the ionic molecule levels in the extracellular fluid in the acupoints. Wistar rats were treated by 2 or 100 Hz EA at Zusanli (ST 36) and Xiajuxu (ST 39) bilaterally for 60 minutes. The accumulation of Na99mTcO4 in the gastric wall and the free ions, including Ca2+, K+, Na+, and Cl-, in the acupoints were measured every 60 minutes. The radioactivity uptake in the stomach was significantly increased during EA, reaching peak at 180 minutes after the EA. The concentration of extracellular ions was also significantly increased during EA. The Ca2+ level continued to rise until 60 minutes after EA, then started to decrease at 120 minutes post-EA. The results suggest this up-regulatory effect of EA on gastric activity might be triggered by the increase of the extracellular ion levels, this effect lasts longer than stimulating the release of transmembrane Ca2+ flow alone. This might aid in providing a better understanding of the long-lasting effect claimed in acupuncture treatment.

Enhanced radiation dose and DNA damage associated with iodinated contrast media in diagnostic X-ray imaging.

A review was undertaken of studies reporting increased DNA damage in circulating blood cells and increased organ doses, for X-ray exposures enhanced by iodinated contrast media (ICM), compared to unenhanced imaging. This effect may be due to ICM molecules acting as a source of secondary radiation (Auger/photoelectrons, fluorescence X-rays) following absorption of primary X-ray photons. It is unclear if the reported increase in DNA damage to blood cells necessarily implies an increased risk of developing cancer. Upon ICM-enhancement, the attenuation properties of blood differ substantially from surrounding tissues. Increased energy deposition is likely to occur within very close proximity to ICM molecules (within a few tens of micrometres). Consequently, in many situations, damage and dose enhancement may be restricted to the blood and vessel wall only. Increased cancer risks may be possible, in cases where ICM molecules are given sufficient time to reach the capillary network and interstitial fluid at the time of exposure. In all situations, the extrapolation of blood cell damage to other tissues requires caution where contrast media are involved. Future research is needed to determine the impact of ICM on dose to cells outside the blood itself and vessel walls, and to determine the concentration of ICM in blood vessels and interstitial fluid at the time of exposure.

Biphasic modeling of brain tumor biomechanics and response to radiation treatment.

Biomechanical forces are central in tumor progression and response to treatment. This becomes more important in brain cancers where tumors are surrounded by tissues with different mechanical properties. Existing mathematical models ignore direct mechanical interactions of the tumor with the normal brain. Here, we developed a clinically relevant model, which predicts tumor growth accounting directly for mechanical interactions. A three-dimensional model of the gray and white matter and the cerebrospinal fluid was constructed from magnetic resonance images of a normal brain. Subsequently, a biphasic tissue growth theory for an initial tumor seed was employed, incorporating the effects of radiotherapy. Additionally, three different sets of brain tissue properties taken from the literature were used to investigate their effect on tumor growth. Results show the evolution of solid stress and interstitial fluid pressure within the tumor and the normal brain. Heterogeneous distribution of the solid stress exerted on the tumor resulted in a 35% spatial variation in cancer cell proliferation. Interestingly, the model predicted that distant from the tumor, normal tissues still undergo significant deformations while it was found that intratumoral fluid pressure is elevated. Our predictions relate to clinical symptoms of brain cancers and present useful tools for therapy planning.

Combination of Gold Nanoparticle-Conjugated Tumor Necrosis Factor-α and Radiation Therapy Results in a Synergistic Antitumor Response in Murine Carcinoma Models.

PURPOSE: Although remarkable preclinical antitumor effects have been shown for tumor necrosis factor-α (TNF) alone and combined with radiation, its clinical use has been hindered by systemic dose-limiting toxicities. We investigated the physiological and antitumor effects of radiation therapy combined with the novel nanomedicine CYT-6091, a 27-nm average-diameter polyethylene glycol-TNF-coated gold nanoparticle, which recently passed through phase 1 trials. METHODS AND MATERIALS: The physiologic and antitumor effects of single and fractionated radiation combined with CYT-6091 were studied in the murine 4T1 breast carcinoma and SCCVII head and neck tumor squamous cell carcinoma models. RESULTS: In the 4T1 murine breast tumor model, we observed a significant reduction in the tumor interstitial fluid pressure (IFP) 24 hours after CYT-6091 alone and combined with a radiation dose of 12 Gy (P<.05 vs control). In contrast, radiation alone (12 Gy) had a negligible effect on the IFP. In the SCCVII head and neck tumor model, the baseline IFP was not markedly elevated, and little additional change occurred in the IFP after single-dose radiation or combined therapy (P>.05 vs control) despite extensive vascular damage observed. The IFP reduction in the 4T1 model was also associated with marked vascular damage and extravasation of red blood cells into the tumor interstitium. A sustained reduction in tumor cell density was observed in the combined therapy group compared with all other groups (P<.05). Finally, we observed a more than twofold delay in tumor growth when CYT-6091 was combined with a single 20-Gy radiation dose-notably, irrespective of the treatment sequence. Moreover, when hypofractionated radiation (12 Gy × 3) was applied with CYT-6091 treatment, a more than five-fold growth delay was observed in the combined treatment group of both tumor models and determined to be synergistic. CONCLUSIONS: Our results have demonstrated that TNF-labeled gold nanoparticles combined with single or fractionated high-dose radiation therapy is effective in reducing IFP and tumor growth and shows promise for clinical translation.

Identification of the biologically active liquid chemistry induced by a nonthermal atmospheric pressure plasma jet.

The mechanism of interaction of cold nonequilibrium plasma jets with mammalian cells in physiologic liquid is reported. The major biological active species produced by an argon RF plasma jet responsible for cell viability reduction are analyzed by experimental results obtained through physical, biological, and chemical diagnostics. This is complemented with chemical kinetics modeling of the plasma source to assess the dominant reactive gas phase species. Different plasma chemistries are obtained by changing the feed gas composition of the cold argon based RF plasma jet from argon, humidified argon (0.27%), to argon/oxygen (1%) and argon/air (1%) at constant power. A minimal consensus physiologic liquid was used, providing isotonic and isohydric conditions and nutrients but is devoid of scavengers or serum constituents. While argon and humidified argon plasma led to the creation of hydrogen peroxide dominated action on the mammalian cells, argon-oxygen and argon-air plasma created a very different biological action and was characterized by trace amounts of hydrogen peroxide only. In particular, for the argon-oxygen (1%), the authors observed a strong negative effect on mammalian cell proliferation and metabolism. This effect was distance dependent and showed a half life time of 30 min in a scavenger free physiologic buffer. Neither catalase and mannitol nor superoxide dismutase could rescue the cell proliferation rate. The strong distance dependency of the effect as well as the low water solubility rules out a major role for ozone and singlet oxygen but suggests a dominant role of atomic oxygen. Experimental results suggest that O reacts with chloride, yielding Cl2(-) or ClO(-). These chlorine species have a limited lifetime under physiologic conditions and therefore show a strong time dependent biological activity. The outcomes are compared with an argon MHz plasma jet (kinpen) to assess the differences between these (at least seemingly) similar plasma sources.

Modulation of the interstitial fluid pressure by high intensity focused ultrasound as a way to alter local fluid and solute movement: insights from a mathematical model.

High intensity focused ultrasound (HIFU) operated in thermal mode has been reported to reduce interstitial fluid pressure and improve the penetration of large macromolecules and nanoparticles in tumor and normal tissue. Little is understood about how the interstitial fluid pressure and velocity as well as the interstitial macromolecule transport are affected by HIFU exposure. A mathematical model is presented here which sheds light on the initial biophysical changes brought about HIFU. Our continuum model treats tissue as an effective poro-elastic material that reacts to elevated temperatures with a rapid drop in interstitial elastic modulus. Using parameters from the literature, the model is extrapolated to derive information on the effect in tumors, and to predict its impact on the convective and diffusive transport of macromolecular drugs. The model is first solved using an analytical approximation with step-wise changes at each boundary, and then solved numerically starting from a Gaussian beam approximation of the ultrasound treatment. Our results indicate that HIFU causes a rapid drop in interstitial fluid pressure that may be exploited to facilitate convection of macromolecules from vasculature to the exposed region. However, following a short recovery period in which the interstitial fluid pressure is normalized, transport returns to normal and the advantages disappear over time. The results indicate that this effect is strongest for the delivery of large molecules and nanoparticles that are in the circulation at the time of treatment. The model may be easily applied to more complex situations involving effects on vascular permeability and diffusion.

Extra cellular pH influences uptake and photodynamic action of pyropheophorbide-a entrapped in folate receptor targeted organically modified silica nanoparticle.

BACKGROUND: Photodynamic efficacy of pyropheophorbide-a (PPa) is limited due to poor aqueous solubility. In the present study, organically modified silica nanoparticles (ORMOSIL) entrapping PPa and its folate receptor targeted conjugate (FR-Np-PPa) were prepared and the effect of pH on uptake and photodynamic action of plain and FR-Np-PPa in squamous cell carcinoma (Nt-8e) cells and adenocarcinoma of breast (MCF-7) cells were studied. METHODS: Nanoformulations of PPa were characterized by absorption and fluorescence spectroscopy. Dynamic light scattering was used for size measurements. The uptake of the two nanoformulations by cells incubated in media of pH 6.5 and 7.4 was studied by confocal fluorescence microscopy and spectrofluoremetrically. Phototoxicity of PPa was studied by MTT assay. RESULTS: In MCF-7 and Nt-8e cells, while the uptake of PPa was observed to increase with a decrease in pH of the incubation media for folate receptor targeted Np, uptake of Np-PPa was not influenced by a change in the pH of the media. Inhibition in the uptake of PPa in presence of free folic acid for cells incubated in a medium of pH 6.5 with targeted nanoparticles was higher compared to physiological pH. Consistent with uptake studies in both the cell lines phototoxicity of PPa delivered through FR-Np-PPa was higher in medium of pH 6.5 as compared to physiological pH and phototoxicity induced by NP-PPa was independent of the pH of medium. CONCLUSION: Acidic pH enhances the photodynamic efficacy of FR-targeted nanoformulated PPa.

High tumor interstitial fluid pressure identifies cervical cancer patients with improved survival from radiotherapy plus cisplatin versus radiotherapy alone.

Radiotherapy (RT) with concurrent cisplatin (CRT) is standard treatment for locally advanced cervical cancer. However, not all patients benefit from the addition of cisplatin to RT alone. This study explored the value of pretreatment tumor interstitial fluid pressure (IFP) and hypoxia measurements as predictors of cisplatin response in 291 patients who were treated with RT (1994-1998) or RT plus concurrent cisplatin (1999-2009). Clinical characteristics were similar between the two groups, apart from a greater proportion of patients with pelvic lymph node metastases and hypoxic tumors in the CRT cohort. Patients were followed for a median duration of 5.6 years. Information about recurrence and survival was recorded prospectively. The addition of cisplatin to RT improved survival compared to treatment with RT alone (HR 0.61, p = 0.0097). This improvement was confined to patients with high-IFP tumors at diagnosis (HR 0.40, p = 0.00091). There was no benefit of adding cisplatin in those with low-IFP tumors (HR 1.05, p = 0.87). There was no difference in the effectiveness of cisplatin in patients with more or less hypoxic tumors. In conclusion, patients with locally advanced cervical cancer and high tumor IFP at diagnosis have greater benefit from the addition of cisplatin to RT than those with low IFP. This may reflect high tumor cell proliferation, which is known to influence IFP, local tumor control and patient survival.

Metabolomic patterns in glioblastoma and changes during radiotherapy: a clinical microdialysis study.

We employed stereotactic microdialysis to sample extracellular fluid intracranially from glioblastoma patients, before and during the first five days of conventional radiotherapy treatment. Microdialysis catheters were implanted in the contrast enhancing tumor as well as in the brain adjacent to tumor (BAT). Reference samples were collected subcutaneously from the patients' abdomen. The samples were analyzed by gas chromatography-time-of-flight mass spectrometry (GC-TOF MS), and the acquired data was processed by hierarchical multivariate curve resolution (H-MCR) and analyzed with orthogonal partial least-squares (OPLS). To enable detection of treatment-induced alterations, the data was processed by individual treatment over time (ITOT) normalization. One-hundred fifty-one metabolites were reliably detected, of which 67 were identified. We found distinct metabolic differences between the intracranially collected samples from tumor and the BAT region. There was also a marked difference between the intracranially and the subcutaneously collected samples. Furthermore, we observed systematic metabolic changes induced by radiotherapy treatment among both tumor and BAT samples. The metabolite patterns affected by treatment were different between tumor and BAT, both containing highly discriminating information, ROC values of 0.896 and 0.821, respectively. Our findings contribute to increased molecular knowledge of basic glioblastoma pathophysiology and point to the possibility of detecting metabolic marker patterns associated to early treatment response.

Dynamics of light particles in oscillating cellular flows.

The dynamics of light particles in chaotic oscillating cellular flows is investigated both analytically and numerically by means of Monte Carlo simulations. At level of linear analysis (in the oscillation amplitude) we determined how the known fixed points relative to the stationary cellular flow deform into closed stable trajectories. Once the latter have been analytically determined, we numerically show that they possess the dynamical role of attracting all asymptotic trajectories for a wide range of parameters values. The robustness of the attracting trajectories is tested by adding a white-noise contribution to the particle equation of motion. As a result, attracting trajectories persist up to a critical Péclet number above which an average rising velocity sets in. Possible implications of our results on the long-standing problem related to the explanation of the observed oceanic plankton patchiness will be also discussed.

Interstitial fluid pressure as a prognostic factor in cervical cancer following radiation therapy.

PURPOSE: To investigate tumor interstitial fluid pressure as a prognostic factor for recurrence-free survival in patients with cervical cancer following radiation therapy. EXPERIMENTAL DESIGN: Tumor interstitial fluid pressure was measured in 55 cervical cancer patients who received radiation therapy between August 1998 and September 2002. Interstitial fluid pressure measurements were made before radiation therapy (pre-radiation therapy interstitial fluid pressure) and after a median of 28.8 Gy in 16 fractions (range, 25.2-30.6 Gy in 14-17 fractions) of radiation therapy (mid-radiation therapy interstitial fluid pressure), using a modified wick-in-needle technique. Median follow-up was 74 months (range, 2-118 months). The Kaplan-Meier method with the log-rank test and Cox's proportional hazard model were used in univariate and multivariate analyses, respectively, of prognostic factors for recurrence-free survival. RESULTS: Median pre-radiation therapy and mid-radiation therapy interstitial fluid pressure were 29.0 mm Hg (range, 4.0-93.9 mm Hg) and 20.0 mm Hg (range, -1.2 to 29.6 mm Hg), respectively (P = 0.001). Pre-radiation therapy interstitial fluid pressure was significantly higher in adenocarcinomas than squamous cell carcinomas (P = 0.028). Significant reduction of interstitial fluid pressure was noted only in patients with complete responses (P = 0.002), and mid-radiation therapy interstitial fluid pressure was significantly lower in patients with complete responses (P = 0.036). In the multivariate analysis including interstitial fluid pressures and clinical variables, pre-radiation therapy interstitial fluid pressure was an independent prognostic factor for local and distant recurrence-free survival (P = 0.001 and 0.027, respectively). CONCLUSIONS: Mid-radiation therapy interstitial fluid pressure measurement may be useful in predicting radiation therapy responses, and pre-radiation therapy interstitial fluid pressure was a significant prognostic factor for local and distant relapse-free survival in patients with cervical cancer after radiation therapy.

Extracellular stimulation of mammalian neurons through repetitive activation of Na+ channels by weak capacitive currents on a silicon chip.

Reliable extracellular stimulation of neuronal activity is the prerequisite for electrical interfacing of cultured networks and brain slices, as well as for neural implants. Safe stimulation must be achieved without damage to the cells. With respect to a future application of highly integrated semiconductor chips, we present an electrophysiological study of capacitive stimulation of mammalian cells in the geometry of adhesion on an insulated titanium dioxide/silicon electrode. We used HEK293 cells with overexpressed Na(V)1.4 channels and neurons from rat hippocampus. Weak biphasic stimuli of falling and rising voltage ramps were applied in the absence of Faradaic current and electroporation. We recorded the response of the intra- and extracellular voltage and evaluated the concomitant polarization of the attached and free cell membranes. Falling ramps efficiently depolarized the central area of the attached membrane. A transient sodium inward current was activated that gave rise to a weak depolarization of the cell on the order of 1 mV. The depolarization could be enhanced step by step by a train of biphasic stimuli until self-excitation of sodium channels set in. We applied the same protocol to cultured rat neurons and found that pulse trains of weak capacitive stimuli were able to elicit action potentials. Our results provide a basis for safe extracellular stimulation not only for cultured neurons on insulated semiconductor electrodes, but also more generally for metal electrodes in cell culture and brain tissue.

Aspartame decreases evoked extracellular dopamine levels in the rat brain: an in vivo voltammetry study.

Conflicting reports exist concerning the effect aspartame (APM, l-aspartyl-l-phenylalanine methyl ester) has upon brain biogenic amines. In the following study, in vivo voltammetry was utilized to measure evoked extracellular dopamine (DA) levels in the striatum of rats in order to assess APM's effect. Time-course experiments revealed a significant decline in evoked extracellular DA levels within 1h of a single systemic dose (500mg/kg i.p.) when compared to vehicle-injected controls. The effect was frequency dependent and showed a significant decrease utilizing high frequency stimulation parameters (50 and 60Hz). In order to further determine APM's potential to alter evoked extracellular DA levels, extended stimulation periods were employed to deplete releasable stores both before and after APM administration in intact and 6-OHDA partially lesioned animals. The extended stimulation periods were applied at 60Hz for 2,5,10 and 20s durations. APM decreased DA levels under these conditions in both intact and 6-OHDA partially lesioned animals by an average of 34% and 51%, respectively. Kinetic analysis performed on frequency series indicated that the diminished DA levels corresponded to a significant reduction in DA release. These findings suggest that APM has a relatively potent effect of decreasing evoked extracellular DA levels when administered systemically under the conditions specified.

The efficacy of frequency-specific acupuncture stimulation on extracellular dopamine concentration in striatum--a rat model study.

Acupuncture is a practice that has existed in Chinese society for thousands of years. Today, it is gaining greater acceptance and integration into medical practices of the western world. Its mechanism, however, remains elusive. Our study shows that only specific stimulation frequencies at specific acupoints will induce dopamine release in the corpus striatum, as demonstrated by in vivo microdialysis performed on Sprague-Dawley rats. In the first trial, electroacupuncture (EA) stimulation at 15 Hz and 15 mA was conducted at six different points on the upper limbs of the experimental rats. These points mimic acupoints along six different meridians in the human body. Only Point 2 (corresponding to Pericardium 7) induced a response. In the second trial, EA stimulation at varying frequencies of 3, 6, 9, 12, 15, 18, 21, 24, 27 and 30 Hz, and 15 mA were conducted through Point 2. Stimulation at 6 and 15 Hz induced an immediate response; 21 Hz induced a response only after the ceasing of stimulation. All other frequencies failed to induce a response. The data point to the importance of frequency-specific stimulation at specific acupoints for the release of neurotransmitters in the brain. We speculate that each meridian entails a stimulus of a specific frequency and intensity, which induces the release of its associated neurotransmitters or cytokines. This is a concept with far-reaching clinical implications for acupuncture therapy, including the treatment of dopamine-related disorders.

In situ visualization of DSBs to assess the extranuclear/extracellular effects induced by low-dose alpha-particle irradiation.

Extranuclear/extracellular effects may have a significant effect on low-dose radiation risk assessment as well as on the shape of the dose-response relationship. Numerous studies using different end points such as sister chromatid exchanges, micronuclei and mutation have shown that this phenomenon exists in many cell types. However, these end points mostly reflect the late events after radiation damage, and little is known about the early response in this phenomenon. DNA double-strand breaks (DSBs) induced by ionizing radiation or carcinogenic chemicals can be visualized in situ using gamma-H2AX immunofluorescence staining, and there is evidence that the number of gamma-H2AX foci can be closely correlated with DSBs induced. Here we used gamma-H2AX as a biomarker to assess the extranuclear/extracellular effects induced by low-dose alpha particles in situ. The results show that a greater fraction of positive cells with DSBs (48.6%) was observed than the number of cells whose nuclei were actually traversed by the 1-cGy dose of alpha particles (9.2%). The fraction of DSB-positive cells was greatly reduced after treatment with either lindane or DMSO. These results suggest that in situ visualization of DSBs can be used to assess radiation-induced extranuclear/extracellular effects soon after irradiation. Moreover, the in situ DSB assay may provide a means to evaluate the spatial effect on unirradiated cells that are located in the neighboring region of cells irradiated by alpha particles.

Irradiation reduces interstitial fluid transport and increases the collagen content in tumors.

PURPOSE: We have shown that the interstitial diffusion of large molecules is significantly hindered in tumors with high collagen levels. Because large therapeutic agents (e.g., monoclonal antibodies and viral vectors) will be combined with radiation or chemotherapy, it is significant to determine how cytotoxic therapies modify the transport and composition of the interstitial space in tumors. To test the hypothesis that radiation alters tumor interstitial transport, we measured tumor hydraulic conductivity (K) and hyaluronan and collagen type I levels after irradiation. EXPERIMENTAL DESIGN: K and the quantification of interstitial matrix components were determined in sections of s.c. implants of the human colon adenocarcinoma LS174T. K was measured on days 1 and 5 after 10 Gy of irradiation or on day 5 after 30 Gy of irradiation. RESULTS: Compared with control tumors, K decreased by approximately 12-fold after 10 or 30 Gy of irradiation on day 5. At 24 h after irradiation with 10 Gy, the decrease in K was not significant. Five days after 10 and 30 Gy of irradiation, the decrease in K was associated with significantly higher levels of collagen type I. The collagen type I content was not changed 24 h after irradiation with 10 Gy. Irradiation did not significantly increase hyaluronan levels in LS174T tumors. CONCLUSIONS: After irradiation, the decrease in K and increase in collagen type I levels could significantly hinder the convective movement and diffusion of large therapeutic agents in tumors.