SEARCH · PubMed Health

Results for “Biophysics”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed1990

Fetal assessment based on fetal biophysical profile scoring. III. Positive predictive accuracy of the very abnormal test (biophysical profile score = 0).

The relationship between complete absence of all components of the fetal biophysical profile score (biophysical profile score = 0) and adverse perinatal outcome was examined. Twenty-nine of 28,655 fetuses studied (0.092%) had a last biophysical profile score of 0; 48.3% of these perinates died (14 of 29 fetuses), the majority of whom (11 of 14) were stillborn, with death occurring as early as 30 minutes to as long as 11 days after the last test. Three asphyxia-related neonatal deaths occurred despite aggressive and immediate intervention. All survivors exhibited at least one of the five discrete markers used to assess perinatal morbidity. The positive predictive accuracy of a biophysical profile score of 0, with mortality and morbidity used as end points, was 100%. These data indicate the very abnormal fetal biophysical profile score to be a perinatal emergency.

Acidosis↗

PubMed1998

Comparison of the modified biophysical profile to a "new" biophysical profile incorporating the middle cerebral artery to umbilical artery velocity flow systolic/diastolic ratio.

OBJECTIVES: The objective of this study was to determine whether the addition of the middle cerebral to umbilical artery systolic/diastolic velocity waveform ratio to the modified biophysical profile would improve perinatal outcome in patients at high risk. STUDY DESIGN: A prospective, randomized outcome study of patients referred to the perinatal laboratory for antenatal surveillance was undertaken. Six hundred sixty-five patients were randomized to two antenatal surveillance protocols: group 1, modified biophysical profile; and group 2, modified biophysical profile plus evaluation of the middle cerebral artery to umbilical artery systolic/diastolic ratio. Patients were followed up serially and neonatal outcome data including gestational age at delivery, birth weight, incidence of cesarean section delivery for fetal distress, admission to the neonatal intensive care unit, days in the neonatal intensive care unit, and the presence of significant neonatal morbidity were tabulated. RESULTS: The total population showed no statistical difference in outcome parameters between groups 1 and 2. However, a subgroup of patients evaluated for suspected uteroplacental insufficiency did show a significant reduction in caesarean section for fetal distress in group 2 patients. CONCLUSIONS: In a subgroup of patients at risk for uteroplacental insufficiency, the addition of the middle cerebral/umbilical artery ratio to an antenatal surveillance protocol should be expected to improve perinatal outcome.

Adult↗

PubMed1979

Intracellular hyperthermia. A biophysical approach to cancer treatment via intracellular temperature and biophysical alterations.

This paper introduces a new multi-disciplinary "intracellular" biophysical treatment of cancer. The basic concept uses locally induced heat energy after tumor phagocytosis of submicron particles whose composition permits magnetic excitation. The key to this process is the utilization of the cancer cell membrane to contain the energy within the cancer cell. Any magnetic or electric dipole contained within or introduced into the cell, or that is capable of being produced by an external field, can be used. Submicron particles are colloidally suspended, injected intravenously and are phagocytized by cancer cells. Application of an external high frequency or pulsed electromagnetic field then raises the particles' temperature thus generating intracellular heat in precise increments. This results in selective thermal destruction of cancer cells with little effect on normal cells. Experimental evidence is presented showing tumor cell destruction in spontaneous mammary tumors in Sprague Dawley rats. In addition, we suggest that certain biophysical properties are altered within the cancer cells and could be used to enhance this effect. Specific radioisotopes or tumor specific antibodies bound to particles or chemotherapeutic microspheres increase cancer cell sensitivity and affinity for these particles. This "intracellular" treatment of cancer has a wide potential range of applications.

Animals↗

PubMed1993

Teaching biophysics. Strategies for recruiting and retaining minorities in physics and biophysics.

Several strategies directed toward increasing the participation of minority students in physics and biophysics are presented. Since the number of minority students entering college with an interest in science and mathematics must be increased if we expect to see more students graduating in science, several programs aimed at increasing the level of instruction of physics and biology in urban middle schools and high schools are outlined. We also describe approaches designed to increase the retention of science major during the freshman core physics course where many potential science majors are lost. Increasing the number of minority students at the PhD level will rely increasingly on partnerships between research universities and historically black colleges and universities (HBCUs) and several programs already in effect are given as examples of such linkages.

Biophysics↗

PubMed2004

Biophysical characterization of fibrinogen Caracas I with an Aalpha-chain truncation at Aalpha-466 Ser: identification of the mutation and biophysical characterization of properties of clots from plasma and purified fibrinogen.

Fibrinogen Caracas I is a dysfibrinogenemia with a mild bleeding tendency; a novel nonsense mutation, in the gene coding the Aalpha-chain, identified in this study as G4731T, giving rise to a new stop codon at Aalpha-Glu 467. Fibrinogen from two family members, the mother and sister of the propositus, both heterozygous for the mutation were studied, analyzing clots made from both plasma and purified fibrinogen. Clot structure and properties were characterized by turbidity, permeation, scanning electron microscopy and rheological studies. Permeation through Caracas I plasma clots was decreased, consistent with the decreased final turbidity. As shown by scanning electron microscopy, plasma clots from the patients were composed of very thin fibers, with increased fibrin density and reduced pore size. Viscoelastic measurements revealed that fibrinogen Caracas I plasma clots were much stiffer and less subject to compaction. These results demonstrate a key role of the carboxyl-terminal alpha chains of fibrin in lateral aggregation during polymerization and reinforce the utility of studying plasma clots. It is important to point out that the biophysical studies with fibrinogen purified by two different methods yielded contradictory results, which can be accounted for by selective purification of certain molecular species as seen by two-dimensional electrophoresis.

Biomechanical Phenomena↗

PubMed1999

The track structures of ionizing particles and their application to radiation biophysics. I. A new analytical method for investigating two biophysical models.

A new approach to the interpretation of the effects of radiation on cells is described, in which sample particle tracks are constructed using a Monte Carlo computer program and the exposure of cellular targets to these tracks is simulated using a second program known as BIOPHYS. Data on the shapes and DNA contents of the cell nuclei are obtained from the literature. It is assumed that the sensitive material is DNA, and that the target is divided into cubes of approximately 2 nm (the diameter of the DNA helix) per side; the numbers of these cubes containing different numbers of ionizations are derived. Two different methods of analysing the output of BIOPHYS are described. In the first, it is assumed that lethality is caused by the occurrence of a number of ionizations equal to or greater than a certain threshold in one cube; in the second method, it is assumed that only two ionizations are required, in different parts of the cube, but that only some fraction of the cube is sensitive. These models have been applied to the interpretation of the variation of radiosensitivity with a linear energy transfer (LET) of spores of Bacillus subtilis exposed wet and dry, and good fits to the published experimental data were obtained using both models. Fits to experimental data for a range of other cell lines will be presented in a second paper.

Bacillus subtilis↗

PubMed1968