Terumasa Higashi

Diamagnetic Orientation of Polymerized Molecules under High Magnetic Field

Diamagnetic alignment of polymerized organic molecules is discussed both from the theoretical and experimental points of view. When a number of molecules aggregate with their diamagnetic principal axes along the same direction, the resultant diamagnetic anisotropy energy becomes comparable to the thermal energy and the aggregated molecule can align under a conventional magnetic field, even at room temperatures. Polymerization of fibrin molecules is observed under magnetic fields up to 8 Tesla and considerable alignment is found. Partial alignment is seen even at 1 Tesla which means that blood clotting is influenced by use of the conventional superconducting magnet.

Effects of static magnetic fields of erythrocyte rheology

Abstract The orientation of normal erythrocytes in a uniform static magnetic field (8 T maximum) has been investigated microscopically and photometrically. 1. (1) The intact erythrocytes were oriented with their disk planes parallel to the magnetic field because of the diamagnetism of the cell membrane components, particularly the transmembrane proteins (e.g., Band III, glycopholin) and the lipid bilayer. 2. (2) In contrast, the glutaraldehyde-fixed erythrocytes were oriented perpendicular to the field, perhaps because of the paramagnetism of the membrane-bound methemoglobin. 3. (3) The orientation was established within 5 s in a dilute suspension (5 × 103cells μl−1) as estimated from the change in light scattering after exposure to the magnetic field.

Magnetic field effect on the polymerization of fibrin fibers

Abstract The alignment of organic molecules polymerized in magnetic fields is investigated theoretically and experimentally. Aggregation of a number of molecules with their axes along the same direction makes it possible to orient them along the applied magnetic field even at room temperature. Polymerization of fibrin fibers with considerable alignment is observed in magnetic fields up to 8 T. Partial alignment is seen even at 1 T.

Orientation of blood cells in static magnetic field

Abstract Orientation of normal blood cells in uniform static magnetic fields (8 T maximum) has been investigated microscopically and photometrically. Intact erythrocytes and platelets (intact and fixed) were oriented with their disc planes parallel to the magnetic field because of the diamagnetism of cell membrane components (lipid bilayer and transmembrane proteins), and additionally of microtubule in the case of platelets. In contrast, glutaraldehyde-fixed erythrocytes were oriented perpendicular to the field because of paramagnetism of membrane-bound methemoglobin.

Orientation of bull sperms in static magnetic fields.

The orientation of bull sperm cells in static magnetic fields was investigated by microscopic observation. The bull sperm, which has a very flat head, was fixed and its motion was stopped by glutaraldehyde. It was oriented with the whole body and the flat head perpendicular to the direction of the magnetic field. The diamagnetic cell components, such as the cell membrane, the DNA in the head, and the microtubule in the tail, were thought to contribute to this orientation, because bull sperm does not have paramagnetic components. For quantitative measurement of the orientation, the intensity of transmitted light through glutaraldehyde-fixed bull sperm suspension in a photometric cell was determined. The intensity changed slightly in proportion to the mean degree of orientation of the sperms. It increased sigmoidally depending on the intensity of the magnetic field and reached 100% at just below 1 T. The magnetic orientation is very strong in comparison to that of erythrocytes or platelets. By studying the response of the bull sperm to the magnetic field, it will be possible to understand its microstructure in more detail.

Orientation of red blood cells in high magnetic field

Abstract The orientation of red blood cells (RBCs) has been investigated in static high magnetic field. Normal RBCs are oriented with their disk plane parallel to the field. However, solidified RBCs are oriented with their disk plane perpendicular to the field direction. This change of orientation probably arises from the magnetic anisotropy of partially aligned hemoglobin molecules in a cell.

Orientation of glutaraldehyde-fixed erythrocytes in strong static magnetic fields

In a uniform static magnetic field up to 8 Telsa, glutaraldehyde-fixed erythrocytes showed an orientation in which their disk plane was perpendicular to the magnetic field. The paramagnetism of membrane-bound hemoglobin was through to contribute significantly to this orientation. The observation of magnetic orientation is directed toward understanding the fundamental microstructural aspects of the erythrocyte.

Effects of a Strong Static Magnetic Field on Blood Platelets

Sickle cells, which are produced as a result of abnormal hemoglobin, become oriented with their major axis perpendicular to a magnetic field of only 0.35 T (tesla= lo4 gauss).’ This may exert a negative influence to blood circulation in some cases. In the ‘guidelines on acceptable limits of exposure to magnetic fields’ established unofficially in the USA in the 1970s, the limit of a short-period exposure of the whole body or the head to a uniform magnetic field is specified at 0.2T.’ The above study result served as reference data for the guidelines. Meanwhile, in recent years, the opportunity for more people to be exposed to stronger magnetic fields has been increasing accompanying the rapid advancement of scientific techniques, such as imagediagnostic techniques by nuclear magnetic resonance (MRI) and passenger transport systems based on the principle of magnetic levitation. Therefore, the necessity has arisen to establish more strict guidelines on acceptable limits of exposure to magnetic fields by systematically elucidating the effects of magnetic fields on living bodies. In this paper, we describe the orientation of blood platelets of healthy people due to the influence of a static magnetic field. Fresh blood of a healthy donor was mixed with 1/10 volume of 3.1% sodium citrate solution. After 15-min centrifugation at 150 g, a platelet rich plasma

Polymerization of biological molecules under high magnetic fields

Abstract The polymerization process of fibrin, one of the diamagnetic molecules in blood plasma, is carried out in a static high magnetic field up to 8 T. SEM images of the polymerized samples show a clear magnetic field effect, i.e. alignment of fibers along the field. Magnetic birefringence using pulsed high magnetic fields is also investigated.

Changes in regional cerebral blood volume in frontal cortex during mental work with and without caffeine intake: functional monitoring using near-infrared spectroscopy

Near-infrared spectroscopy (NIRS) was used to measure frontal regional cerebral blood volume (rCBV) in a person whose brain was under the influence of pharmacological agents while the person was performing a complex task. Fourteen healthy participants were administered Uchida-Kraepelin psychodiagnostic (UKP) tests before and after caffeine intake, and the concentration of caffeine in the urine was measured. The average number of answers and the average number of correct answers given by the participants improved significantly following caffeine intake. During the UKP testing, changes in the rCBV in the inferior frontal cortex were continuously measured using NIRS. The volume during the rest periods decreased as a result of caffeine-induced constriction of the cerebral arteriola. The volume increased during the mental work, but the degree of the increase was the same before and after caffeine intake. Although the performance of the mental work improved following caffeine intake, the improvement was not reflected in the rCBV in the inferior frontal cerebral cortex. These results suggest that caffeine helps to protect the brain from excessive hyperemia in addition to activating the neurons in the prefrontal cortex.