Effect of pulsed ultrasound on human erythrocytes in vitro

The effect of pulsed ultrasound exposure on the oxygen dissociation curve of human erythrocytes in in vitro conditions

The P(50) value, a marker for the behavior of the oxygen dissociation curve (ODC) and values of 2,3-diphosphoglyceric acid (2,3-DPG), blood gases and acid base parameters (pH, PCO(2), actual HCO(3)(-), base excess, PO(2), SO(2)) and erythrocyte parameters (the number of erythrocyte, hematocrit and hemoglobin values) that are known to effect P(50), were measured before and after ultrasound (US) exposure to examine the effect of pulsed US beams on the ODC of human erythrocytes. Venous blood samples taken from healthy subjects were sonicated at 0 degrees C for 30 min by pulsed US beams with a constant frequency of 5 MHz. Experiments showed that the values of pH, actual HCO(3)(-), standard HCO(3)(-), base excess, 2,3-DPG and P(50) were changed considerably by pulsed US. Furthermore, correlation calculations were made to find out the relation between the P(50) values and the other parameters. As a result, a significant relation was found between P(50) values and the values of pH, actual HCO(3)(-), PO(2), SO(2) and 2,3-DPG. In conclusion, we can express that a highly significant increase occurs in P(50) value of venous blood after a pulsed US exposure at a constant frequency of 5 MHz for 30 min under in vitro conditions at 0(0)C. That is hemoglobin becomes suitable for deoxy (tense structure) conformation when blood affinity of O(2) is low. It means that hemoglobin becomes convenient for proton (H(+)) and CO(2) binding.

Transient poration and cell surface receptor removal from human lymphocytes in vitro by 1 MHz ultrasound

The study objective was to gain insight into ultrasound-induced, sub-lytic cell surface modifications. Two primary hypotheses were tested by flow cytometric methods; viz., sonication will: 1. remove all or part of a specific cell surface marker in lymphocytes surviving insonation, and 2. induce transient pores in the cell membranes of some surviving cells. RPMI 1788 human lymphocytes were exposed in vitro to 1-MHz, continuous-wave ultrasound (approximately 8 W/cm2 ISP) for 30 s, which lysed approximately 50% of the cells. Insonation: 1. altered cell morphology, increasing the population of cells of reduced size but high structure (designated as population R2), many of which were nonviable, and diminishing the population of cells of large size and high structure (designated as population R1), most of which were viable, 2. diminished the fluorescence signal from the pan B lymphocyte marker CD19 in populations R1 and R2 to equivalent extents, and 3. increased by approximately 7-fold the number of transiently permeabilized cells in R1, as evidenced by simultaneous uptake of propidium iodide and fluorescein diacetate. The results indicate that ultrasound-induced CD19 removal from R1 cells can occur without accompanying gross membrane loss. The cell morphology/mortality shifts indicate that the ultrasound-induced morphological change is associated with lethal membrane poration, suggesting that the diminished CD19 fluorescence signal from insonated R2 cells arises partly by simultaneous loss of membrane fragments, CD19 and cytoplasm.

Effects of ultrasound on agglutination and aggregation of human erythrocytes in vitro

A new experimental approach has shown that human erythrocytes of different blood groups were induced to form more agglutinates at a sound pressure of 70-240 kPa in vitro than the control erythrocytes. Similar effects were observed for alcian blue and dextran stimulated aggregation and for spontaneous aggregation. The increase of agglutination or aggregation was reversible. Heating and acoustic cavitation were shown not to be responsible for this effect. Bulk fluid movement produced by ultrasound irradiation appeared to cause the described phenomenon. Possible underlying mechanisms connecting the acoustic streaming and agglutination or aggregation behaviour of the cells are proposed.

Evaluation of the bioeffects of prenatal ultrasound exposure in the cynomolgus macaque (Macaca fascicularis): I. Neonatal/infant observations

The frequency of use of ultrasonography for evaluating the developing embryo/fetus has continued to rise although the possible risks from exposure still remain uncertain. The cynomolgus macaque (Macaca fascicularis) is currently being used in our laboratory as a model to assess these risks. In utero exposure was performed utilizing a commercial real-time mechanical sector scanner with a 7.5 MHz scanhead (ATL, MK 600). Maximum acoustic power output for this unit is as follows: I(SPTA) = 12.0 mW/cm2, I(SPPA) = 98 W/cm2, and Im = 137 W/cm2. Animals exposed to ultrasound (N = 16) were scanned five times weekly on gestational days (GD) 21-35 +/- 2 for 10 minutes/exam (m/e), three times weekly on GD 36-60 +/- 2 for 10 m/e, and once weekly on GD 61-150 +/- 2 for 20 m/e. Controls (N = 14) were "scanned" with the unit placed on standby. Assessment of simian Apgar scores at 1, 5, and 10 minutes of life revealed higher scores for treated animals at 10 minutes (P less than or equal to 0.045); greater scores in muscle tone (P less than or equal to 0.013) and color (P less than or equal to 0.016) were observed. Evaluation of morphometrics at birth including weight, biparietal diameter, occipitofrontal diameter, head circumference, hand and foot lengths, humerus and femur lengths, arm circumference, chest circumference, tail length, skinfold thickness, and crown-rump length (CRL) indicated a significant reduction in only two parameters, birth weight (P less than or equal to 0.027) and CRL (P less than or equal to 0.033). Hematologic analysis at 2 +/- 1, 9 +/- 1, and 16 +/- 1 days of life revealed a significant difference in white blood cell counts (WBCs). Treated animals displayed lower WBCs with reductions in numbers of segmented neutrophils and monocytes at all ages observed. Hematologic differences were not significant by 5-6 months of age. No abortions, gross malformations, or stillbirths were observed in the exposed animals.

The effect of combined heat and ultrasound on multicellular tumour spheroids

The effect of combined ultrasound and heat treatments on Chinese hamster multicellular spheroids of varying size was investigated using growth rate, single cell survival and ultrastructural damage as endpoints. Ultrasonic irradiation at 37 degrees C had no effect on the growth rate of 200-730 microns spheroids. Similarly there was no effect on the growth rate of 350 microns spheroids when irradiated during a 60 min exposure to 41.5 degrees C. However, spheroids of 200-700 mm diameter showed growth delay when held at 43 degrees C for 1 h. The effect was enhanced with concomitant ultrasound irradiation but was not dependent on spheroid size. When 200 and 400 microns spheroids held at 43 degrees C for 60 min were irradiated with different ultrasonic intensities a dose-dependent decrease in surviving fraction and a dose-dependent increase in growth delay was obtained. When surviving fraction was plotted as a function of growth delay a good correlation was obtained, suggesting that the combination of heat and ultrasound irradiation does not produce cytostasis in the surviving cells of either 200 or 400 microns spheroids. At the ultrastructural level increased cytoplasmic vacuolation was the only result of ultrasonic irradiation at 37 degrees C. Exposure to 43 degrees C for 60 min was required to elicit thermal damage. This took the form of membrane evagination at the spheroid surface, vacuolation of the cytoplasm, grouping of organelles around the periphery of the nucleus, and fragmentation of the nucleolus. These effects were enhanced with concomitant ultrasonic irradiation but other features were also noted, viz. disaggregation of polyribosomes, dilation of the rough endoplasmic reticulum and blebbing of the nuclear membrane. Damage was independent of spheroid size. These results are in agreement with previous data obtained from single-cell studies. Indicating that there is a non-thermal, non-cavitational component to the cell killing in multicellular spheroids resulting from combined heat and ultrasound treatment.

Development of health risk evaluation data for diagnostic ultrasound: a historical perspective

The growth of ultrasound applications in diagnostic medicine has helped stimulate related biological effects investigations. Current data related to effects associated with diagnostic ultrasound indicate the need for additional research on cell surface structures, motility and developmental effects. Research on biological effects, especially for evaluating in vivo end points analogous to those employed by investigators using in vitro systems and simple organisms, are needed. Particular emphasis relative to potential effects on fetal and embroyonic development is indicated. Limited data also suggest the need to investigate possible effects on the immune response. There is a growing realization of the potential importance of nonthermal effects and increasing evidence that the temporal peak intensity is potentially related to the production of some effects. A number of recent comprehensive reviews have helped identify, analyze and evaluate some of the relevant data.