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PubMed1988

Comparative studies on the biophysical activities of the low-molecular-weight hydrophobic proteins purified from bovine pulmonary surfactant.

Two low-molecular-weight hydrophobic proteins with nominal molecular weights Mr = 15,000 and Mr = 3,500 have been isolated from the lipid extracts of bovine pulmonary surfactant by several methods, including (a) dialysis plus silicic acid chromatography, (b) elution from Waters SEP-PAK silica cartridges with a variety of solvent mixtures, and (c) ultrafiltration. As detailed in the text, these proteins have been designated surfactant-associated protein-BC (SP-BC) (15 kDa: nonreduced), and SP-C (3.5 kDa). The biophysical activities of reconstituted surfactant containing these proteins and the phospholipids present in lung surfactant have been compared with the biophysical activities of bovine lipid extract surfactant on a pulsating bubble surfactometer using a phospholipid concentration of 10 mg/ml. At this concentration, unmodified lipid extract surfactant reduces the surface tension of the pulsating bubble to near 0 within 10 pulsations at 20 cycles per min. Similar biophysical properties were observed with modified lipid extract surfactant in which the relative concentration of hydrophobic protein had been reduced from 1 to 0.4% (W/W) of the phospholipids by addition of dipalmitoylphosphatidylcholine (DPPC) or DPPC plus phosphatidylglycerol. Reconstituted surfactants, which contained partially delipidated SP-BC (15 kDa: nonreduced) obtained by method (a) at a relative concentration of 0.1%, were also capable of reducing the surface tension to near 0 mN/m. Preparations of SP-BC (15 kDa: nonreduced) obtained by method (b), which had been subjected to very low pH levels during isolation and were extensively delipidated, exhibited full biophysical activity only at higher protein concentrations and with prolonged pulsation. Extensively delipidated samples of SP-BC obtained by method (c) exhibited impaired biophysical activities, even when prepared with neutral organic solvents. Reconstituted surfactant samples containing SP-C (3.5 kDa) obtained by any of the methods listed above were only able to reduce the surface tension at minimum bubble radius to approx. 20 mN/m. The biophysical activity of SP-C (3.5 kDa) was not significantly affected by low pH or extensive delipidation. Reconstituted samples containing mixtures of SP-BC (15 kDa: nonreduced) and SP-C (3.5 kDa) were more effective than samples containing either protein alone. Furthermore, with samples containing both hydrophobic proteins the final surface tensions at maximum bubble radius were attained within a few bubble pulsations.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Biophysical inhibition of synthetic lung surfactants.

The biophysical activity and inhibition of a series of synthetic surfactant mixtures was studied and correlated with physiological effectiveness in restoring pressure-volume (P-V) mechanics of excised lungs. Results showed that several simple mixtures of dipalmitoyl phosphatidylcholine (DPPC) with fatty acids or diacylglycerols could be formulated to give good adsorption facility and dynamic surface tension lowering to less than 1 mN/m in pulsating bubble measurements at 37 degrees C. However, although biophysical activity approached that of natural lung surfactant (LS) and a related surfactant extract (CLSE) under normal conditions, surface properties were sharply inhibited by relatively small amounts of the plasma protein albumin (2 mg/ml) with minimum surface tensions greater than 30 nM/m even at high surfactant concentrations (5-20 mg lipids/ml). This sensitivity to biophysical inhibition was markedly increased compared to LS and CLSE, and had direct consequences for physiological efficacy: in spite of initially high activity, synthetic surfactants did not exert beneficial effects on P-V mechanics when instilled into surfactant-deficient excised rat lungs. Endogenous protein material was shown to be present upon surfactant recovery by lavage, and bubble measurements confirmed surface activity well below pre-instillation levels. Moreover, full biophysical activity was restored when lavage fluid was extracted to separate the synthetic surfactants from endogenous inhibitors. These results show that it is important to define relative sensitivity to biophysical inhibition in the development of effective lung surfactant substitutes. In addition, the existence of inhibition effects can generate an apparent lack of correspondence between initial biophysical activity and ultimate physiological actions of exogenous surfactant mixtures.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2001

Modified fetal biophysical profile in the assessment of perinatal outcome.

The aim of the study is the evaluation of variables of the biophysical profile in the assessment of perinatal outcome. The prospective study included 87 pregnant women with singleton pregnancy in the 28th to 42nd week of gestation with clinically and ultrasonically verified fetal growth retardation, where the fetal biophysical profile was assessed antenatally. Through the factor analysis of biophysical profile variables we obtained values indicating the contribution of individual variables to the predictability of perinatal outcome. 70% of the patients were examined in 15 minutes according to the principles of modified biophysical profile. The most sensitive variable of the biophysical profile in the prediction of perinatal outcome was the amniotic fluid volume, followed by fetal breathing movements, non-stress test and fetal movements, while the lowest prediction value was assigned to the fetal tone. The modified biophysical profiles need to be perfected on a larger number of pregnant women, which would advance the predictability of this method in detection of hypoxically endangered fetuses.

Female↗
PubMed1983

The fetal biophysical profile and its predictive value.

Six fetal biophysical variables--the nonstress test, fetal movements, fetal breathing movements, fetal tone, amniotic fluid volume, and placental grading (biophysical profile)--were assessed in 150 high-risk pregnancies during a 30-minute observation period. The predictive value of the nonstress test alone, biophysical scoring, and contraction stress test alone in the identification of the healthy fetus as well as the fetus in jeopardy are discussed. The relationships between individual variables and combinations of variables to the outcome of pregnancy, as reflected by abnormal intrapartum fetal heart rate patterns, meconium during labor, fetal distress, and perinatal mortality rate were determined. The biophysical profile of all hypoxic fetuses was analyzed. These data suggest that the biophysical profile is more accurate in the identification of the hypoxic fetus than any other single method; therefore, a new protocol including the biophysical profile for antepartum fetal evaluation is presented.

Amniotic Fluid↗
PubMed2003

Biophysical stimulation of bone fracture repair, regeneration and remodelling.

Biophysical stimulation to enhance bone fracture repair and bone regenerate maturation to restore its structural strength must rely on both the biological and biomechanical principle according to the local tissue environment and the type of mechanical stress to be born by the skeletal joint system. This paper reviews the possible interactions between biophysical stimuli and cellular responses in healing bone fractures and proceeds to speculate the prospects and limitations of different experimental models in evaluating and optimising such non-invasive interventions. It is important to realize that bone fracture repair has several pathways with various combinations of bone formation mechanisms, but there may only be one bone remodeling principle regulated by the hypothesis proposed by Wolff. There are different mechanical and biophysical stimuli that could provide effective augmentation of fracture healing and bone regenerate maturation. The key requirements of establishing these positive interactions are to define the precise cellular response to the stimulation signal in an in vitro environment and to use well-established animal models to quantify and optimise the therapeutic regimen in a time-dependent manner. This can only be achieved through research collaboration among different disciplines using scientific methodologies. In addition, the specific forms of biophysical stimulation and its dose effect and application timing must be carefully determined and validated. Technological advances in achieving focalized stimulus delivery with adjustable signal type and intensity, in the ability to monitor healing callus mechanical property non-invasively, and in the establishment of a robust knowledge base to develop effective and reliable treatment protocols are the essential pre-requisites to make biophysical stimulation acceptable in the main arena of health care. Finally, it is important to bear in mind that successful fracture repair or bone regeneration through callus distraction without adequate remodeling process through physiological loading would seriously undermine the value of biophysical stimulation in meeting the biomechanical demand of a long bone.

Animals↗
PubMed1987

Fetal biophysical profile and perinatal death.

Antepartum assessment of 5034 high-risk pregnancies to predict perinatal death included five biophysical variables (nonstress test, fetal breathing movements, fetal movements, fetal tone, and amniotic fluid volume) which combined to form a biophysical profile score. We assessed 4148 fetuses within seven days of delivery. The ability of each variable to predict perinatal death was expressed as the likelihood ratio, which incorporates sensitivity and specificity into one number. The predictive ability was most accurate with fetal movement (likelihood ratio 48.1) and the combined biophysical profile score (likelihood ratio 51.0). The biophysical profile score was more likely to predict perinatal death due to asphyxia (seven of eight) than lethal anomaly (six of 19). The overall perinatal mortality was 7.6 per 1000 total births. The perinatal mortality rate was 1.0 for a normal biophysical profile score, 31.3 for an equivocal score, and 200.0 for an abnormal score. The false-negative rate for the biophysical profile score was 0.7 per 1000.

Amniotic Fluid↗
PubMed1994

The value of a negative antepartum test: contraction stress test and modified biophysical profile.

OBJECTIVE: To examine the outcome of pregnancies in high-risk patients whose last antepartum fetal assessment was a negative contraction stress test (CST) or a negative modified biophysical profile. METHODS: Twenty-nine hundred ninety-four women who received modified biophysical profiles were compared with 2450 who had CSTs during the preceding 3 years. Pregnancy outcomes were evaluated in patients whose last test was negative. RESULTS: Seventeen hundred fifty-three patients had negative modified biophysical profiles as the last test before delivery, and 1337 had negative CSTs as the last test before delivery. Adverse perinatal outcomes included perinatal death or death before nursery discharge, cesarean delivery for fetal distress within the first 2 hours of labor, 5-minute Apgar score less than 7, neonatal seizures, or grade III or grade IV central nervous system hemorrhage. Adverse outcomes occurred in 90 patients (5.1%) whose last test before delivery was a negative modified biophysical profile and in 93 patients (7.0%) whose last test was a negative CST (P = .04, odds ratio 1.38, 95% confidence interval 1.01-1.88). Overall, there were 11 perinatal deaths, nine of which resulted from lethal congenital abnormalities. CONCLUSIONS: In this population, the frequency of adverse perinatal outcome following a negative modified biophysical profile was no greater than that following a negative CST. Further, the incidence of potentially preventable perinatal death following a negative modified biophysical profile or CST was less than one per 1000 tested high-risk pregnancies.

Adult↗
PubMed1993

The use of vibroacoustic stimulation during the abnormal or equivocal biophysical profile.

OBJECTIVE: To determine whether vibroacoustic stimulation during the biophysical profile can change the fetal behavioral state and thus improve the score without increasing the false-negative rate of the test. METHODS: Eighty-one patients whose biophysical profile scores were 6 or lower after 15 minutes of observation had an electronic artificial larynx applied to the maternal abdomen in the region of the fetal head for 3 seconds, followed by continued observation for fetal movement, tone, and breathing for 15 minutes. We compared the obstetric and neonatal outcomes of 41 patients whose biophysical profile scores improved to normal after vibroacoustic stimulation with those of 283 patients whose scores were normal without vibroacoustic stimulation. RESULTS: Vibroacoustic stimulation did improve an abnormal or equivocal biophysical profile score to normal in 67 of 81 cases (82%). No antepartum stillbirths or perinatal deaths occurred. There was no increase in the obstetric and neonatal complication rates of cesarean delivery for fetal distress, meconium staining of the amniotic fluid, and the incidence of small for gestational age infants. CONCLUSION: Vibroacoustic stimulation improved the biophysical profile scores in most cases, an effect seen throughout the third trimester. Vibroacoustic stimulation did not appear to increase the false-negative rate of the biophysical profile and may reduce the incidence of unnecessary obstetric intervention.

Acoustic Stimulation↗
PubMed1996

Effect of methadone on the biophysical profile.

OBJECTIVE: To determine the effect of methadone on the biophysical profile. STUDY DESIGN: Sixteen narcotics-dependent gravidas on methadone maintenance were selected for the study. Biophysical profiles and nonstress tests (NSTs) were performed on women between 28 and 40 weeks' estimated gestational age before and two hours after methadone was given. The reactivity of the nonstress tests, biophysical profile scores and time needed to complete the biophysical profiled before and after methadone dosing were compared. RESULTS: Significantly more NSTs were nonreactive after methadone (P < .001), and it took more time for the NST to become reactive (P < .01). Although it took longer for the modified biophysical profile to be completed after methadone dosing, with the mean time going from 3.8 to 19.8 minutes (P < .01), the scores were the same before and after methadone in 75% of the women, with the mean score not significantly different before or after methadone. CONCLUSION: Our results suggest that the modified biophysical profile is a clinically useful test in the methadone-maintained gravida.

Adult↗
PubMed1990

Two-tier approach to biophysical assessment of the fetus.

The biophysical profile score is widely accepted as a superior predictor of acute-on-chronic fetal asphyxia over the nonstress test. Nevertheless, in the United Kingdom facilities for assessment of high-risk pregnancies by nonstress test are more widely available than with the biophysical profile score. After a retrospective review of 2038 biophysical assessments in 500 high-risk pregnancies, it is suggested that biophysical evaluation of the fetus can be rationalized on the basis of the clinical problem and fetal growth. Terminal acute-on-chronic fetal asphyxia can be excluded by a two-tier method of fetal assessment by initial nonstress test backed up by the biophysical profile score when the nonstress test is suboptimal.

Asphyxia Neonatorum↗
PubMed1987

Antepartum fetal risk assessment: the role of the fetal biophysical profile score.

In the art of medicine we have always known that establishing an accurate diagnosis of health or disease is essential. An active search for the physical signs, both the time honoured and newly discovered, are a crucial step in achieving diagnostic accuracy, in monitoring disease progression, and in assigning prognosis. In extrauterine medicine it is common practice to gather together sets of biophysical data in order to determine immediate health, to monitor condition, and to estimate prognosis: witness the use of vital signs, and, in the newborn, the Apgar score. The providers of perinatal care have known since biblical days that fetal biophysical activities were a reflection of fetal condition (Luke: Chapter 1, Verses 44-45), yet lacked the ability to categorize these activities in an objective and complete manner. The introduction of dynamic ultrasound imaging methods to perinatal medicine at last create the window through which the principles of extrauterine medicine may now be applied to the intrauterine patient--the fetus. Fetal biophysical profile scoring is a method that utilizes this new wealth of information to differentiate the normal fetus from the fetus at risk for death or damage in utero. The method is based on the concept that the discrimination of fetal health and disease improves as more variables are considered. The now extensive clinical experience with the method, in which both overall (gross) and selected (corrected) perinatal death are reduced, while maintaining a remarkably low false negative predictive error, indicate the validity of the concept. Comparative studies lead us to believe that reliance upon single biophysical variables, such as fetal movement counts, or antepartum fetal heart rate monitoring, is no longer of sufficient accuracy to support its use as a sole measure of fetal condition. Looking forward, we anticipate that while the concept on which fetal biophysical profile scoring is based will remain unchanged, inclusion of additional variables is likely to occur. It seems likely that addition of new variables, as may be now measured using high-resolution dynamic ultrasound methods, both B-mode and Doppler, will improve diagnostic accuracy even more. We believe that the application of the current and future modified methods of composite fetal risk assessment will render the occurrence of the tragedy of perinatal loss even more infrequent. While the goal of complete elimination of perinatal deaths remain elusive, this method may be one step towards this goal.

Biophysical Phenomena↗
PubMed2000

Biophysical body-brain-mind unity: theory and practice.

A novel substance-attributed biophysical theory of brain-mind unity is presented. We separate spiritualism and matters of the soul from the medical sphere. Biophysical principles are responsible for the body's operational regimen (BOR) in the homeostatic state which allows for materialization and emergence of the mind; Excitation and/or inhibition modulate 8 BOR stages. There is automatic (somatic) and non-automatic (biophysical and psychological) Circadian cycle control. Computer-analog input and output occurs in wired neuronal electric pathways. Biotechnological devices located in emotional neurons positively signal homeostatic and negatively signal deranged BOR and biophysical mind operations. Macro and/or micro cerebral lesions which affect homeostasis may cause psychopathology, which can be treated with 'instrumental psychotherapy' (IPT) which enables recovery from homeostatic disorder in Phase 1, refining EGO in Phase 2, and social competence in Phase 3. The theory of brain-mind unity and practice of IPT is geared to medical workers and biophysical psychologists.

Biophysical Phenomena↗
PubMed1992

The biophysical profile and the nonstress test: poor predictors of chorioamnionitis and fetal infection in prolonged preterm premature rupture of membranes.

Sixty-eight women admitted with the diagnosis of preterm premature rupture of membranes (PROM) and a latency period of at least 48 hours were followed expectantly. Fetal surveillance consisted of daily kick counts, daily nonstress test (NST), and fetal biophysical profile every 48-72 hours. Patients were delivered as a result of spontaneous labor, clinical chorioamnionitis, fetal distress, or attainment of 37 weeks' gestation. No corticosteroids, tocolytics, or prophylactic antibiotics were used. The last biophysical profile and the last NST before delivery were evaluated for each patient. There was no statistically significant association between chorioamnionitis or fetal infection and the following: 1) a low biophysical profile (score of 6 or lower), 2) a low biophysical profile that included a nonreactive NST and absent fetal breathing movements, or 3) a nonreactive NST. We conclude that the biophysical profile and the NST are poor predictors of perinatal infectious complications.

Adolescent↗
PubMed1990

The biophysical profile in labor.

To determine whether the biophysical profile would be a valuable intrapartum addition to fetal heart rate monitoring in predicting umbilical arterial acid-base status at delivery, 95 patients at term had serial studies during labor and umbilical artery blood gas analysis. There was no significant association between biophysical profile score and cord blood pH, nor was there a difference in scores between the acidemic and nonacidemic groups. Of the five components of the initial biophysical profile, only a nonreactive nonstress test (NST) was associated with both pH 7.20 or less (P = .019) and metabolic acidemia (P = .016). None of the individual variables of the final examination correlated with a pH of 7.20 or less. However, a nonreactive NST was associated with metabolic acidemia (P = .03), as was the presence of breathing (P = .03). Of the ten infants with pH 7.20 or less, eight had an initial and five had a final biophysical profile score of 8 or higher. Of the five whose pH was less than 7.15, four had an initial and three a final score of 8 or more. Finally, of the five with metabolic acidemia, four had an initial and two a final score of 8 or higher. Half of the acidemic fetuses had final biophysical profile scores of 8 or higher, suggesting that this score in labor is not reliable to rule out acidemia at delivery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1973

Trends in biophysical research and their implications for medical libraries.

This is a statistical survey of the trends in biophysical research as reflected by papers presented at four Biophysical Society (BPS) annual meetings between 1958 and 1972 and by the funding sources of the reported projects. The study reveals that biophysical research has grown quite substantially, particularly since 1968. Although biophysics is truly interdisciplinary, since 1968 there has been more pronounced emphasis on biomedically oriented problems and a tendency toward more specific and more highly specialized problems. Between 1958 and 1972, most biophysicists were academic researchers, 50% of whom were biomedical scientists. Over three quarters of the ongoing biophysical research projects during this period were supported by governmental agencies, and among them, the National Institutes of Health was the largest single funding source.

Biology↗
PubMed1990

The fetal biophysical profile score: current status.

The cumulative experience with fetal biophysical profile scoring as a method for antepartum fetal risk assessment is now extensive. The cumulative data indicate that the method is sensitive for recognizing both the normal and compromised fetus. Moreover, the method appears to offer the advantage of grading various degrees of fetal compromise. The additional information gained by real-time ultrasound scanning (gestational age determination, fetal morphometrics, and fetal anomaly screening), while not an integral part of fetal biophysical profile scoring, nevertheless remains a critical aspect of antepartum fetal assessment. These data are collected simultaneously with the fetal biophysical profile score. It is impossible to separate cleanly the advantages of fetal biophysical profile scoring in isolation of this additional information collected. It would seem that such an attempt at separation is artificial since these data in combination provide more key information to the physician to guide fetal management. It seems reasonable to effect continued modification and improvement of the existing fetal biophysical profile score as a means of antepartum fetal risk assessment.

Biophysics↗
PubMed2000

Biophysical profile for fetal assessment in high risk pregnancies.

BACKGROUND: Biophysical profile usually includes ultrasound monitoring of fetal movements, fetal tone and fetal breathing, ultrasound assessment of amniotic fluid volume and assessment of fetal heart rate by electronic monitoring. OBJECTIVES: The objective of this review was to assess the effects of biophysical profile tests on pregnancy outcome in high risk pregnancies. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth trials register. Date of last search: October 1998. SELECTION CRITERIA: Randomised trials comparing fetal biophysical profile with other forms of fetal assessment in women with high risk pregnancies. DATA COLLECTION AND ANALYSIS: Trial quality was assessed. MAIN RESULTS: Four studies were included. Most trials were not of high quality. No difference was found between biophysical profile and other forms of fetal assessment over a range of fetal and neonatal measures. REVIEWER'S CONCLUSIONS: At present, there is not enough evidence from randomised trials to evaluate the use of biophysical profile as a test of fetal well-being in high risk pregnancies.

Embryonic and Fetal Development↗
PubMed2005

Break on through to the other side-biophysics and cell biology shed light on cell-penetrating peptides.

Cell-penetrating peptides (CPPs) have become widely used vectors for the cellular import of molecules in basic and applied biomedical research. Despite the broad acceptance of these molecules as molecular carriers, the details of the mode of cellular internalization and membrane permeation remain elusive. Within the last two years endocytosis has been demonstrated to be a route of uptake shared by several CPPs. These findings had a significant impact on CPP research. State-of-the-art cell biology is now required to advance the understanding of the intracellular fate of the CPP and cargo molecules. Owing to their presumed ability to cross lipid bilayers, CPPs also represent highly interesting objects of biophysical research. Numerous studies have investigated structure-activity relationships of CPPs with respect to their ability to bind to a lipid bilayer or to cross this barrier. Endocytosis route only relocates the membrane permeation from the cell surface to endocytic compartments. Therefore, biophysical experiments are key to a mechanistic molecular understanding of the cellular uptake of CPPs. However, biophysical investigations have to consider the molecular environment encountered by a peptide inside and outside a cell. In this contribution we will review biophysical and cell-biology data obtained for several prominent CPPs. Furthermore, we will summarize recent findings on the cell-penetrating characteristics of antimicrobial peptides and the antimicrobial properties of CPPs. Peptides of both groups have overlapping characteristics. Therefore, both fields may greatly benefit from each other. The review will conclude with a perspective of how biophysics and cell biology may synergize even more efficiently in the future.

Amino Acid Sequence↗