Comparison of Hemodynamic Energy between Expanded Polytetrafluoroethylene and Dacron Artificial Vessels.

BACKGROUND: Artificial grafts such as polyethylene terephthalate (Dacron) and expanded polytetrafluoroethylene (ePTFE) are used for various cardiovascular surgical procedures. The compliance properties of prosthetic grafts could affect hemodynamic energy, which can be measured using the energy-equivalent pressure (EEP) and surplus hemodynamic energy (SHE). We investigated changes in the hemodynamic energy of prosthetic grafts. METHODS: In a simulation test, the changes in EEP for these grafts were estimated using COMSOL MULTIPHYSICS. The Young modulus, Poisson ratio, and density were used to analyze the grafts' material properties, and pre- and post-graft EEP values were obtained by computing the product of the pressure and velocity. In an in vivo study, Dacron and ePTFE grafts were anastomosed in an end-to-side fashion on the descending thoracic aorta of swine. The pulsatile pump flow was fixed at 2 L/min. Real-time flow and pressure were measured at the distal part of each graft, while clamping the other graft and the descending thoracic aorta. EEP and SHE were calculated and compared. RESULTS: In the simulation test, the mean arterial pressure decreased by 39% for all simulations. EEP decreased by 42% for both grafts, and by around 55% for the native blood vessels after grafting. The in vivo test showed no significant difference between both grafts in terms of EEP and SHE. CONCLUSION: The post-graft hemodynamic energy was not different between the Dacron and ePTFE grafts. Artificial grafts are less compliant than native blood vessels; however, they can deliver pulsatile blood flow and hemodynamic energy without any significant energy loss.

Effects of lipopolysaccharide on changes in red blood cells in a mice endotoxemia model.

The aim of this study was to evaluate changes in RBC aggregation and deformability over 24 hr and suggest specific shear stress values for detecting RBC deformability in a mouse endotoxemia model using lipopolysaccharide (LPS).Six-week-old male BALB/c mice received LPS (20 mg/kg) intraperitoneally. Aggregation indices (AIs) and T1/2 were measured to assess RBC aggregation, and elongation indices (EIs) were used to assess RBC deformability at shear stress values of 0.3, 0.5, 1, 3, 7, 10, 15 and 20 Pascals (Pa) 0, 30 min, 1, 2, 4, 6, 9, 12, 18 and 24 hours after the LPS injection.No significant differences were detected in the AIs during the study period, however, T1/2 shortened significantly 2, 6, 12, 18, and 24 hr after the LPS injection. The EIs increased significantly 24 hr after LPS injection at 0.5 and 1 Pa shear stress, whereas it decreased significantly at 10 Pa of shear stress 24 hr after the LPS injection.Altered RBC deformability was detectable 24 hr after the LPS injection and T1/2 may be a sensitive marker for detecting changes in RBC aggregation. The EIs should be measured at 1 Pa to detect changes in RBC deformability in LPS-induced septic mice.

Micromachined tethered silicon oscillator for an endomicroscopic Lissajous fiber scanner.

This work reports micromachined tethered silicon oscillators (MTSOs) for endoscopic Lissajous fiber scanners. An MTSO comprises an offset silicon spring for stiffness modulation of a scanning fiber and additional mass for modulation of resonant scanning frequency in one body. MTSOs were assembled with a resonant fiber scanner and enhanced scanning reliability of the scanner by eliminating mechanical cross coupling. The fiber scanner with MTSOs was fully packaged as an endomicroscopic catheter and coupled with a conventional laparoscope and spectral domain OCT system. The endomicroscope was maneuvered with the integrated laparoscope and in vivo swine tissue OCT imaging was successfully demonstrated during open surgery. This new component serves as an important element inside an endoscopic Lissajous fiber scanner for early cancer detection or on-demand minimum lesional margin decision during noninvasive endoscopic biopsy.

Discovery of a novel fibrous tissue in the spinal pia mater by polarized light microscopy.

Abstract It is very well known that spinal meninges are composed of three layers, dura, arachnoid and pia mater, and that the main components of pia mater are collagen and reticular fibers. However, the distribution of those fibers has not been extensively investigated but just described as a mesh of fibers. In this study, we detected novel structures, which are composed of unidirectionally arranged fibers, in a rat spinal pia mater by using a polarized light microscope. They were seen as three parallel lines, one of which ran along a posterior spinal vein and the rest two of which ran along a pair of posterior spinal arteries. Histological analysis including Masson's trichrome, picrosirius-red staining, Gordon & Sweet's staining and immunohistochemistry with anti-collagen type 1 and 3 antibodies uncovered that they are mainly composed of collagen fibers and some reticular fibers. In addition, a putative primo vessel was detected in the novel fibrous tissue, which was proven out to be different from a blood vessel. In conclusion, we report a newly detected fibrous structure in the spinal pia mater, which may contribute to provide tensile force to the spinal meninges and to harbor the primo vascular system inside.

The characteristics of action potentials in primo vessels and the effects of acetylcholine injection to the action potentials.

In a previous study, we found that Primo vessels generate different action potentials in smooth muscles, but this study compared the pulse shape to distinguish the two tissues. Thus, a more sophisticated extracellular experiment was performed in this study using an acetylcholine injection; we then observed changes in the amplitude, FWHM (full width at half maximum), and period to explore Primo vessel function. A third type of pulse was recorded for Primo vessels. We observed fast depolarizing and repolarizing phases for this pulse. Further, its FWHM was 30 ms between smooth muscles and neurons. Acetylcholine affected only the period. The amplitude and FWHM were consistent after injection. Primo-vessels generated action potentials at twice the frequency after injection. From the results, we speculate that Primo-vessels perform a role in transferring signals in a different manner, which may be relevant for acupuncture treatment.

Primo vascular system in the subarachnoid space of a mouse brain.

Objective. Recently, a novel circulatory system, the primo vascular system (PVS), was found in the brain ventricles and in the central canal of the spinal cord of a rat. The aim of the current work is to detect the PVS along the transverse sinuses between the cerebrum and the cerebellum of a mouse brain. Materials and Methods. The PVS in the subarachnoid space was analyzed after staining with 4',6-diamidino-2-phenylindole (DAPI) and phalloidin in order to identify the PVS. With confocal microscopy and polarization microscopy, the primo vessel underneath the sagittal sinus was examined. The primo nodes under the transversal sinuses were observed after peeling off the dura and pia maters of the brain. Results. The primo vessel underneath the superior sagittal sinus was observed and showed linear optical polarization, similarly to the rabbit and the rat cases. The primo nodes were observed under the left and the right transverse sinuses at distances of 3,763 µ m and 5,967 µ m. The average size was 155 µ m × 248 µ m. Conclusion. The observation of primo vessels was consistent with previous observations in rabbits and rats, and primo nodes under the transverse sinuses were observed for the first time in this work.

Primo vascular system accompanying a blood vessel from tumor tissue and a method to distinguish it from the blood or the lymph system.

A primo vessel was observed in the abdominal cavity in the lung cancer mouse model, and its function as an extra metastatic path was observed. In this work, we found a primo vessel accompanying a blood vessel emanating from a tumor in the skin. We also presented simple and efficient criteria to distinguish a primo vessel from a blood or a lymph vessel and from a nerve. The criteria for using DAPI and Phalloidin will be useful in clinical situations to find and identify the primo vessels among the blood vessels, lymph vessels, or nerves in the tissue surrounding a tumor such as a melanoma or breast cancer.

A solid state nanopore device for investigating the magnetic properties of magnetic nanoparticles.

In this study, we explored magnetic nanoparticles translocating through a nanopore in the presence of an inhomogeneous magnetic field. By detecting the ionic current blockade signals with a silicon nitride nanopore, we found that the translocation velocity that is driven by magnetic and hydrodynamic forces on a single magnetic nanoparticle can be accurately determined and is linearly proportional to the magnetization of the magnetic nanoparticle. Thus, we obtained the magneto-susceptibility of an individual nanoparticle and the average susceptibility over one hundred particles within a few minutes.

Differentiating blood, lymph, and primo vessels by residual time characteristic of fluorescent nanoparticles in a tumor model.

Fluorescent nanoparticles (FNPs) which were injected into a tumor tissue flowed out through the blood and lymph vessels. The FNPs in blood vessels remained only in the order for few minutes while those in lymph vessels remained for a long time disappearing completely in 25 hours. We found a primo vessel inside a lymph vessel near a blood vessel, and FNPs remained in the primo vessel for longer than 25 hours. In addition, we examined in detail the residual time characteristics of lymph vessels because it could be useful in a future study of fluid dynamical comparison of the three conduits. These residual time characteristics of FNPs in the three kinds of vessels may have implications for the dynamics of nanoparticle drugs for cancer chemotherapy.

Primo vessel inside a lymph vessel emerging from a cancer tissue.

Primo vessels were observed inside the lymph vessels near the caudal vena cava of a rabbit and a rat and in the thoracic lymph duct of a mouse. In the current work we found a primo vessel inside the lymph vessel that came out from the tumor tissue of a mouse. A cancer model of a nude mouse was made with human lung cancer cell line NCI-H460. We injected fluorescent nanoparticles into the xenografted tumor tissue and studied their flow in blood, lymph, and primo vessels. Fluorescent nanoparticles flowed through the blood vessels quickly in few minutes, and but slowly in the lymph vessels. The bright fluorescent signals of nanoparticles disappeared within one hour in the blood vessels but remained much longer up to several hours in the case of lymph vessels. We found an exceptional case of lymph vessels that remained bright with fluorescence up to 24 hours. After detailed examination we found that the bright fluorescence was due to a putative primo vessel inside the lymph vessel. This rare observation is consistent with Bong-Han Kim's claim on the presence of a primo vascular system in lymph vessels. It provides a significant suggestion on the cancer metastasis through primo vessels and lymph vessels.

A primo vascular system underneath the superior sagittal sinus in the brain of a rabbit.

The primo vascular systems (PVS) observed in the central nervous system have been limited to the ones floating in the cerebrospinal fluid. In those experiments, it was difficult to obtain the same results because the PVS was not fixed in a given anatomical position. In the current work, we report a finding of a PVS in a well-defined location, namely, underneath the superior sagittal sinus in the sagittal fissure, so that repetition of the experiments is possible. This provides a cornerstone for PVS research because the lack of reproducible sample-taking hindered a deeper study of the PVS, such as RNA sequencing or RNA microarray. This obstacle can be overcome through the discovery in the current work. This PVS showed characteristics of the PVS observed in other organs. It showed the bundle structure of subvessels, the parallel distributions of F-actins, and the rod-shaped nuclei. Furthermore, it had a primo node in front of the confluence of sinuses above the pineal body. It had branches shooting off from the main primo vessel in the subarachnoid space toward the cerebral hemispheres. The results indicate that this PVS underneath superior sagittal sinus has proper features to function as a flowing channel.

Estimating the density of fluorescent nanoparticles in the primo vessels in the fourth ventricle and the spinal cord of a rat.

The primo vascular system is a novel circulatory system forming a network throughout an animal's body. Primo vessels were recently observed in the fourth ventricle of the brain and in the spinal cord of a rat by using fluorescent nanoparticles. In order to quantify the nanoparticles in the primo vessels, we measured the florescence of the nanoparticles and calibrated the measurements by using a reference suspension. We removed the noise due to autofluorescence with the technique of multispectral imaging. The line densities of nanoparticles and the contrast values of their images were, respectively, 0.5 ± 0.5 ng/mm and 0.7 ± 0.5 for primo vessels in the fourth ventricle, and 1.3 ± 0.6 ng/mm and 1.4 ± 0.2 for primo vessels in the spinal cord. The data obtained from and the procedures used in this work could be useful in evaluating the feasibility of using nanoparticles as a contrast agent during MRI or CT imaging of primo vessels in the brain or the spinal cord.

Development of a laparoscopic system for in vivo observation of the Bonghan structure.

Bonghan structures composed of corpuscles and ducts have been observed in numerous animal experiments. The structure has been suggested to be the physical substrate for acupuncture points and meridians used in traditional Chinese medicine. The corpuscle-duct structure on the organ surface has been extensively studied. However, it was only observed after the abdomen of a rat was fully exposed. It may be desirable to observe these structures under minimally invasive conditions. Our laparoscope is specifically designed for in situ, in vivo observation of the Bonghan structure on the surface of internal organs in rats. We made a laparoscope consisting of a borescope combined with an illumination module and an imaging data acquisition part. The Bonghan structure is transparent and is hard to see, even with the borescope. Spraying a specific dye, trypan blue and washing with saline is a necessary process to visualize the structure. For this reason, we devised a staining and washing system attached in parallel with the borescope in the laparoscopic system. The system operated successfully to reveal a Bonghan structure without surgery. This tool opens a host of possible applications such as observation of flow of stained liquid or drug in the Bonghan duct flowing from the skin to internal organs, and long-term observation of the physiological changes in Bonghan corpuscles.

Scanning spontaneous photon emission from transplanted ovarian tumor of mice using a photomultiplier tube.

A scanning system for the detection of spontaneous ultraweak photon emission from nude mice with transplanted tumors is presented. A photomultiplier tube (PMT) with an effective area of 15 mm diameter was used for measuring photon emission in a wavelength range from 300 to 650 nm. Tumors were induced in nude mice by transplantation of an ovarian cancer cell line into the back of mice. The PMT was moved for scanning over the whole body of a mouse placed in a dark box. The profiles of the intensities of photon emissions from the tumor mice are presented and compared with those obtained from the control mice.

Measurements of spontaneous ultraweak photon emission and delayed luminescence from human cancer tissues.

OBJECTIVE: The aim of this study was to measure spontaneous photon emission (SPE) and delayed luminescence (DL) from various human cancer tissues. MATERIALS AND METHODS: A photomultiplier tube attached to a dark chamber was used for the detection of ultraweak photon emission from cancer tissues in the chamber. The samples were illuminated with a 150 W metal halide lamp for the measurement of delayed luminescence. Frozen tissues were provided by the hospitals and preserved in saline solution in a CO2 incubator for 1 hour before starting the measurement of spontaneous photon emission. We successively measured the afterglows from the samples after 30-second irradiation of the lamp. The samples were divided into two groups: tumor tissues and normal tissues around tumor tissues. We presented experimental data and interpreted their characteristic patterns of spontaneous photon emission and delayed luminescence. RESULTS: Mean values of spontaneous photon emissions from the normal tissues and the tumor tissues were measured with the standard errors of the mean as 625 +/- 419 counts/minute/cm2 (n = 6) and 982 +/- 513 counts/minute/cm2 (n = 14), respectively. Peak values of the intensity of delayed luminescence from normal and cancerous tissues were 63 +/- 20 counts/ms (n = 6) and 48 +/- 12 counts/ms (n = 14). CONCLUSIONS: The intensity of spontaneous photon emissions from cancer tissues were mostly discriminated from those of normal tissues, and their delayed luminescent properties were investigated.

Effects of extremely low frequency magnetic field on the antioxidant defense system in mouse brain: a chemiluminescence study.

Among the putative mechanisms, by which extremely low frequency (ELF) magnetic field (MF) may affect biological systems is that of increasing free radical life span in organisms. To test this hypothesis, we investigated whether ELF (60 Hz) MF can modulate antioxidant system in mouse brain by detecting chemiluminescence and measuring superoxide dismutase (SOD) activity in homogenates of the organ. Compared to sham exposed control group, lucigenin-initiated chemiluminescence in exposed group was not significantly increased. However, lucigenin-amplified t-butyl hydroperoxide (TBHP)-initiated brain homogenates chemiluminescence, was significantly increased in mouse exposed to 60 Hz, MF, 12 G for 3 h compared to sham exposed group. We also measured SOD activity, that plays a critical role of the antioxidant defensive system in brain. In the group exposed to 60 Hz, MF, 12 G for 3 h, brain SOD activity was significantly increased. These results suggest that 60 Hz, MF could deteriorate antioxidant defensive system by reactive oxygen species (ROS), other than superoxide radicals. Further studies are needed to identify the kind of ROS generated by the exposure to 60 Hz, MF and elucidate how MF can affect biological system in connection with oxidative stress.