Metabolomic changes following GenX and PFBS exposure in developing zebrafish

Short chain per- and polyfluoroalkyl substances (PFAS), including hexafluoropropylene oxide dimer acid (GenX) and perfluorobutane sulfonate (PFBS), are replacement chemicals for environmentally persistent, long-chain PFAS. Although GenX and PFBS have been detected in surface and ground water worldwide, few studies provide information on the metabolic alterations or risks associated with their exposures. In this study, larval zebrafish were used to investigate the toxicity of early-life exposure to GenX or PFBS. Zebrafish were chronically exposed from 4 h post-fertilization (hpf) to 6 days post-fertilization (dpf) to 150 µM GenX or 95.0 µM PFBS. Ultra-high-performance liquid chromatography paired with high-resolution mass spectrometry was used to quantify uptake of GenX and PFBS into zebrafish larvae and perform targeted and untargeted metabolomics. Our results indicate that PFBS was 20.4 % more readily absorbed into the zebrafish larvae compared to GenX. Additionally, PFBS exposure significantly altered 13 targeted metabolites and 21 metabolic pathways, while GenX exposure significantly altered 1 targeted metabolite and 17 metabolic pathways. Exposure to GenX, and to an even greater extent PFBS, resulted in a number of altered metabolic pathways in the amino acid metabolism, with other significant alterations in the carbohydrate, lipid, cofactors and vitamins, nucleotide, and xenobiotics metabolisms. Our results indicate that GenX and PFBS impact the zebrafish metabolome, with implications of global metabolic dysregulation, particularly in metabolic pathways relating to growth and development.

Effects of Corsi-Rosenthal boxes on indoor air contaminants: non-targeted analysis using high resolution mass spectrometry

BACKGROUND

In response to COVID-19, attention was drawn to indoor air quality and interventions to mitigate airborne COVID-19 transmission. Of developed interventions, Corsi-Rosenthal (CR) boxes, a do-it-yourself indoor air filter, may have potential co-benefits of reducing indoor air contaminant levels.

OBJECTIVE

We employed non-targeted and suspect screening analysis (NTA and SSA) to detect and identify volatile and semi-volatile organic contaminants (VOCs and SVOCs) that decreased in indoor air following installation of CR boxes.

METHODS

Using a natural experiment, we sampled indoor air before and during installation of CR boxes in 17 rooms inside an occupied office building. We measured VOCs and SVOCs using gas chromatography (GC) high resolution mass spectrometry (HRMS) with electron ionization (EI) and liquid chromatography (LC) HRMS in negative and positive electrospray ionization (ESI). We examined area count changes during vs. before operation of the CR boxes using linear mixed models.

RESULTS

Transformed (log2) area counts of 71 features significantly decreased by 50-100% after CR boxes were installed (False Discovery Rate (FDR) p-value < 0.2). Of the significantly decreased features, four chemicals were identified with Level 1 confidence, 45 were putatively identified with Level 2-4 confidence, and 22 could not be identified (Level 5). Identified and putatively identified features (Level ≥4) that declined included disinfectants (n = 1), fragrance and/or food chemicals (n = 9), nitrogen-containing heterocyclic compounds (n = 4), organophosphate esters (n = 1), polycyclic aromatic hydrocarbons (n = 8), polychlorinated biphenyls (n = 1), pesticides/herbicides/insecticides (n = 18), per- and polyfluorinated alkyl substances (n = 2), phthalates (n = 3), and plasticizers (n = 2).

IMPACT STATEMENT

We used SSA and NTA to demonstrate that do-it-yourself Corsi-Rosenthal boxes are an effective means for improving indoor air quality by reducing a wide range of volatile and semi-volatile organic contaminants.

Applying transformational leadership in nursing practice

The updated Nursing and Midwifery Council (NMC) standards of proficiency for nurses emphasise the importance of nurse leadership, while the NHS has also developed models to support leadership development. There are several approaches to leadership that are applicable in nursing practice. Transformational leadership is an approach that focuses on the attributes and behaviours of the leader required to empower and motivate team members. This article outlines the four elements of transformational leadership - idealised influence, inspirational motivation, intellectual stimulation and individualised consideration - and discusses these in relation to the NMC standards. It also describes the advantages and disadvantages of transformational leadership, and suggests ways that this approach can be applied in nursing practice.

The Amidolytic Activity of the SK-Plasminogen Complex Is Enhanced by a Potentiator which Is Generated in the Presence of Vascular Plasminogen Activator - Role of Fibrin Degradation Products

In the presence of an excess of streptokinase (SK) the amidolytic activity of the plasminogen-SK complex on chromogenic substrates is 12% lower in serum than in the corresponding plasma. However, in subjects in whom venous stasis lead to a shortening of the euglobulin lysis time to less than 60 min (high responders), the amidolytic activity of the plasminogen-SK complex in serum was 60% higher than in the corresponding plasma. Attempts to find alterations of the plasminogen molecule itself which would account for the enhanced activity in high responder serum were negative. No free plasmin was present and the plasminogens isolated from plasma and serum before and after venous stasis had the same amidolytic activity as glu-plasminogen in the presence of an excess of SK. N-terminal analysis of these four plasminogens revealed in each instance glutamic acid.

The enhancement of the amidolytic activity of the SK-plasminogen complex in serum of high responders (potentiator activity) could be reproduced by adding purified tissue plasminogen activator (TA) to native blood before clotting, but not if TA was added to plasma or to prestasis serum. Removal of fibrin degradation products from poststasis serum resulted in the disappearance of potentiator activity. These experiments suggest that fibrin degradation products, generated during clotting in the presence of vascular or tissular plasminogen activator act as a potentiator of the amidolytic activity of the plasminogen SK-complex.

Secondhand smoke exposure and survival following acute coronary syndrome: prospective cohort study of 1261 consecutive admissions among never-smokers

OBJECTIVE

To determine whether exposure to secondhand smoke is associated with early prognosis following acute coronary syndrome.

DESIGN, SETTING AND PARTICIPANTS

We interviewed consecutive patients admitted to nine Scottish hospitals over 23 months. Information was obtained, via questionnaire, on age, sex, smoking status, postcode of residence and admission serum cotinine concentration was measured. Follow-up data were obtained from routine hospital admission and death databases.

RESULTS

Of the 5815 participants, 1261 were never-smokers. Within 30 days, 50 (4%) had died and 35 (3%) had a non-fatal myocardial infarction. All-cause deaths increased from 10 (2.1%) in those with cotinine < or =0.1 ng/ml to 22 (7.5%) in those with cotinine >0.9 ng/ml (chi(2) test for trend p<0.001). This persisted after adjustment for potential confounders (cotinine >0.9 ng/ml: adjusted OR 4.80, 95% CI 1.95 to 11.83, p = 0.003). The same dose response was observed for cardiovascular deaths and death or myocardial infarction.

CONCLUSIONS

Secondhand smoke exposure is associated with worse early prognosis following acute coronary syndrome. Non-smokers need to be protected from the harmful effects of secondhand smoke.

Wireless Recharging of Implanted Batteries via Ultrasound

In order to expand the applications for implanted rechargeable batteries, and to reduce the frequency of battery replacement procedures, we are investigating a recharging technique complimentary to and improving on the current RF recharging technique. Although the first applications deal with batteries that could be implanted in human bodies to power neurostimulators, sensors, and drug pumps, non-medical applications may exist. Using a transmitter-receiver arrangement, we have recharged batteries wirelessly using ultrasound at several frequencies between 0.75 and 3.0 MHz. Rechargeable implantable batteries of 35, 200 and 600 mA-hr were charged at rates of up to 0.75 C, where C is the charging rate (charging current/maximum battery charging current). Typically the intervening medium was one centimeter of a tissue mimicking liquid (TML), however some in vitro experiments have also been performed. Charging was accomplished at distances of up to 20 centimeters in water, and even through millimeters of plastic and centimeters of aluminum. Temperature measurements were made on both transmitting and receiving transducers, and in the TML. As expected there were significant increases in temperature at the higher charging currents. Experimentally we determined that the “overall efficiency” of the charging process, viz. E=(Ibatt*Vbatt)/(net electrical power)input, was closely correlated with the observed heating. That is, the lower the efficiency, the higher the input electrical power required, the more transducer heat was produced and conducted into and through the medium. The critical issues were the coupling of the transmitter and receiver to the medium, and the efficiency of conversion of the receiver output to charging power by the charging circuitry. These depend on the mechanical and electrical impedances, and we improved the efficiency considerable by appropriate impedance matching. Active and passive methods of cooling the transducers and intervening medium have been constructed and successfully tested. With our system, recharging times will be limited not by heating considerations, but only by the optimum rate at which a given battery can accept charge.

Plastic baton round injuries

OBJECTIVES

To review the injuries resulting from a new plastic baton round.

METHODS

Review of case notes of patients presenting with injuries caused by plastic baton rounds over a four month period in Northern Ireland.

RESULTS

Twenty nine patients were identified, 28 with 30 injuries were included in the study. Eighty nine per cent were male; the average age was 24.3 years. Seven patients required admission. There were no fatalities. Five injuries were to the upper limbs and 16 to the lower limbs. Three patients sustained pulmonary contusions. There were no head injuries.

CONCLUSIONS

Although the numbers in this study are small it should be noted that no patient suffered a face, neck, or head injury. This is in contrast with previous studies in which up to 41.4% of attendances were for face, neck, or head injuries. In this study there were seven injuries to the trunk. Of the 14 deaths attributable to plastic baton rounds in Northern Ireland, all have been the result of head or chest trauma. The use of plastic baton rounds has decreased and, while a reduction in head injuries is noted, potentially serious chest injuries are still occurring. It is vital that guidelines on firing are adhered to. A large proportion of people who have been struck by plastic baton rounds do not attend an accident and emergency department and therefore doctors must be aware of patients with potentially serious injuries presenting late.

Team triage improves emergency department efficiency

OBJECTIVE

To see whether three hours of combined doctor and nurse triage would lead to earlier medical assessment and treatment and whether this benefit would carry on for the rest of the day when normal triage had resumed.

METHOD

Eight days were randomly selected; four for team triage and four for the normal nurse led triage. Team triage was coordinated by a middle grade or consultant from 9 am to 12 noon. Times to triage, to see a doctor, radiology, admission, and discharge were recorded. No additional medical or nursing staff were used and staffing levels were similar each day. All patients including blue light emergencies and minor injuries were included.

RESULTS

Median times were significantly reduced (p<0.05) during the intervention to triage (2 min v 7 min, p = 0. 029), to see a doctor (2 min v 32 min, p = 0.029), and to radiology (11.5 min v 44.5 min, p = 0.029). Waiting times at midday were longer for patients in the non-intervention group. More patients were seen and discharged within 20 minutes in the intervention group (18 of 95 (19%) v 2 of 69 (3%) p = 0.0043). No significant knock on effect was demonstrable for the remaining 21 hours after the intervention ceased.

CONCLUSION

Three hours of combined doctor and nurse triage significantly reduces the time to medical assessment, radiology, and to discharge during the intervention period. Waiting times at midday were shorter in the triage group. There was no significant knock on effect the rest of the day.

Two cases of biceps injury in bodybuilders with initially misleading presentation

Two cases are reported of biceps injuries in body builders. In both cases the mechanism of injury is either unclear or initially misleading. One case went on to develop necrotising fasciitis, requiring extensive debridement after an initial diagnosis of a biceps haematoma. This report emphasises the difficulties inherent in differentiating necrotising and non-necrotising infections in the emergency department setting and highlights a subgroup of patients who may be at particular risk of delayed diagnosis.

Measurements of acoustic properties of aqueous dextran solutions in the VHF/UHF range

The acoustic properties of aqueous solutions of dextran are characterized in the frequency range of 70-400 MHz by the bio-ultrasonic spectroscopy system using an ultrasonic transmission comparison method. The attenuation, velocity, impedance, and density of aqueous dextran solutions, for six molecular weights in the range of 10,400-2,000,000 Da in the concentration range 520% by weight, are reported. All four parameters increase with increasing concentration. As the molecular weight increases, the attenuation coefficient increases and the velocity decreases. The precise frequency and molecular weight dependences of the acoustic properties of the solutions are readily determined by the system.

Biological effects of long-duration, high-field (4 T) MRI on growth and development in the mouse

The effects of long-duration, high-field magnetic resonance imaging (MRI) on fetal growth and postnatal development in mice were studied. Seven experimental groups of pregnant ICR mice were exposed for 9 hours on day 9 and/or day 12 post coitus (pc) to magnetic fields (4 T static, 5 T/sec switched gradient, and 0.2 W/kg radiofrequency at 170 MHz) associated with MRI conditions. Two experimental groups (sham and exposure groups) were exposed to a combination of ultrasound (day 9 pc, 3.25 MHz, focused) and MRI-associated fields (day 12 pc). No statistically significant changes in fetal growth were observed in the animals exposed to only MRI or ultrasound fields. However, in the combined ultrasound and MRI-exposed group, the fetal weight and crown-rump length were reduced compared with the sham and cage controls. These results suggest that MRI and ultrasound exposure well in excess of current clinical conditions can exert biological effects if applied at sensitive stages of fetal development.

Ultrasound interaction with large unilamellar vesicles at the phospholipid phase transition: perturbation by phospholipid side chain substitution with deuterium

The ultrasonic absorption, alpha lambda, as a function of temperature and frequency was determined in large unilamellar vesicles (LUVs) in which specific phospholipid side chains were deuterated. Deuteration significantly altered the temperature and frequency dependence of alpha lambda. The frequency change was especially marked, with decreased frequency and broadening of the ultrasound relaxation, even with only minor changes in the phase transition temperature. Deuteration decreased the Tm and enthalpy of the lipid phase transition, as shown by differential scanning calorimetry, whereas electron spin resonance showed that at and above the lipid phase transition, no differences in the mobility as a function of temperature were observed. These results show that the observed increase in ultrasonic absorption in LUVs at the phospholipid phase transition arises from the interaction of ultrasound with the hydrophobic side chains, probably coupling with structural reorganization of small domains of molecules, a process which is maximized at the phase transition temperature.

Acoustic properties of egg yolk and albumen in the frequency range 20-400 MHz

The acoustic propagation properties of egg yolk and albumen are characterized in the frequency range 20-400 MHz by the bioultrasonic spectroscopy system using an ultrasonic transmission comparison method. Significant differences in the attenuation, velocity, impedance, and density among yolk and thick and outer thin albumen are observed. The acoustic properties of 10% aqueous solutions of ovalbumin and bovine hemoglobin are also measured in order to investigate the contribution of proteins to the acoustic properties of albumen. The differences obtained between thick and outer thin albumen may be mainly due to their macromolecular level structural differences, as their constituents are nearly the same.

Selective clinical ultrasound signals mediate differential gene transfer and expression in two human prostate cancer cell lines: LnCap and PC-3

Low intensity ultrasound signals, similar to that employed in clinical therapy, are found to mediate differential gene transfer and expression of the Green Fluorescence Protein (GFP) reporter in two human prostate cancer cell lines, LnCap and PC-3. Cell suspensions in the presence or in the absence of GFP (44.5nM) were treated at 37 degrees C under a standing wave condition. Cells were exposed to either continuous wave, 932.7kHz ultrasound, or to several independent bursts, each burst comprising a 20% duty cycle (932.7kHz) sine wave. The burst "repetition" frequency was varied from 10Hz to 10kHz in several different experiments and each treatment received a net identical ultrasound energy exposure. Transient GFP expression levels in viable cells were monitored by flow cytometry. The findings revealed a strong ultrasound tone-burst frequency dependence on the transfection efficiencies. Interestingly, the ultrasound signal parameters which are routinely employed in clinical therapy did not yield any statistically significant enhancement in transfection efficiency relative to their sham counterparts.

Ultrasonic tissue characterization of infarcted myocardium by scanning acoustic microscopy

The purpose of this study was to ultrasonically characterize infarcted human myocardial tissue at the microscopic level by scanning acoustic microscopy. Infarcted myocardial specimens from ten cases with acute myocardial infarction were studied. Specimens were formalin fixed, paraffin embedded and sectioned to 10-micron thickness. A specially developed scanning acoustic microscope system, operating in the 100- to 200-MHz ultrasound frequency range, was used for the measurements. The values of the attenuation constant were 0.94 +/- 0.04 dB/mm/MHz in normal myocardium, 0.71 +/- 0.12 dB/mm/MHz in degenerated myocardium, 0.88 +/- 0.47 dB/mm/MHz in granulation tissue and 1.75 +/- 0.11 dB/mm/MHz in fibrosis. The values of sound speed were 1620.2 +/- 8.2 m/s in normal myocardium, 1572.4 +/- 10.6 m/s in degenerated myocardium, 1590.2 +/- 32.5 m/s in granulation tissue and 1690.3 +/- 9.1 m/s in fibrosis. The ultrasonic properties of the diseased myocardium at the microscopic level will provide important information for ultrasonic tissue characterization at the macroscopic level.

Mediators of fibrinolysis in orthotopic liver transplantation

Activation of fibrinolysis remains a clinical problem in orthotopic liver transplantation. We have measured tissue plasminogen activator (t-PA), plasmin and alpha-2-anti-plasmin (alpha 2AP) activities in plasma from 10 patients undergoing elective transplantation. t-PA activity increased during the anhepatic phase and immediately after graft reperfusion (p > 0.001). This increase could not be attributed to t-PA released by the donor liver. Overall transfusion requirements did not relate with either t-PA or alpha 2AP activities individually, but were strongly correlated with the ratio t-PA/ alpha 2AP (p > 0.02). These results suggest that routine prophylactic use of antifibrinolytic agents may be beneficial.

Acoustic properties of selected bovine tissues in the frequency range 20-200 MHz

The acoustic properties of freshly excised bovine liver, heart muscle, and fat are characterized in the frequency range 20-200 MHz by the bioultrasonic spectroscopy system using an ultrasonic transmission comparison method. Significant differences are obtained in the attenuation coefficient, velocity, impedance, and density among these tissues. Measurements of aqueous solutions of bovine hemoglobin are also reported in order to compare the contribution of the protein content to the acoustic properties. The differences among the acoustic properties of liver and heart muscle can be described in terms of their protein contents and other molecular constituents.

A simulation algorithm for ultrasound liver backscattered signals

In this study, we present a simulation algorithm for the backscattered ultrasound signal from liver tissue. The algorithm simulates backscattered signals from normal liver and three different liver abnormalities. The performance of the algorithm has been tested by statistically comparing the simulated signals with corresponding signals obtained from a previous in vivo study. To verify that the simulated signals can be classified correctly we have applied a classification technique based on an artificial neural network. The acoustic features extracted from the spectrum over a 2.5 MHz bandwidth are the attenuation coefficient and the change of speed of sound with frequency (dispersion). Our results show that the algorithm performs satisfactorily. Further testing of the algorithm is conducted by the use of a data acquisition and analysis system designed by the authors, where several simulated signals are stored in memory chips and classified according to their abnormalities.

The effect of ultrasound exposure in utero on the development of the fetal mouse testis: adult consequences

The effects of exposure in utero to 1 MHz, continuous-wave ultrasound on adult growth and testicular development in the mouse was investigated. The spatial peak temporal average intensity (ISPTA) employed ranged from 1 to 10 W/cm2, with exposure durations (t) of 200 s to 20 s. Exposures were made on days 9, 12 or 15 of gestation. Results showed an increase in postpartum deaths, an increase in the number of stillbirths, and a decrease in litter size when I2 t > or = 1125 W2 s/cm4, such that there was significant loss of pups. Birthweights of pups from nearly all dosage groups was significantly lower than that of the sham or cage control groups. Results also showed that males exposed to ultrasound in utero had decreased testis size and decreased daily sperm production ranging from 9% to 30%. This study showed that ultrasound exposure in utero is capable of disrupting fetal development and having potential subsequent effects on fertility in the adult male.

In vivo liver differentiation by ultrasound using an artificial neural network

A pattern recognition algorithm and instrumentation for in vivo ultrasound human liver differentiation are presented. An available 16-MHz microprocessor-based data acquisition and analysis system with 6-bit resolution is used to capture, digitize, and store the backscattered ultrasound signal. The algorithm is based on a multilayer perception neural network using the backpropagation training procedure. The network is implemented to differentiate between normal and abnormal liver. Data earlier obtained from 18 volunteers with normal liver history and from 12 volunteers with liver abnormalities are used to test the algorithm. The power spectra of the backscattered signal from depths of 5, 6.5, and 8 cm in the liver are calculated. The acoustic attenuation coefficient is calculated by the log spectral difference technique over the frequency range from 1.5 to 4.5 MHz. The change of speed of sound with frequency (dispersion) is estimated over the 3-MHz bandwidth. The attenuation and velocity dispersion are used as differentiation features. The results show that of the 22 tested cases, the system differentiated correctly 19 and 20 cases when using the attenuation and the velocity dispersion, respectively. The average magnitude of dispersion of liver is estimated to be 1.67 +/- 0.1 m/s/MHz and about 2.3 +/- 0.18 m/s/MHz in the normal and abnormal cases, respectively. The overall performance of the system for liver differentiation is 91% for normal cases, and 86% for abnormal cases. The data files are also differentiated using the nearest neighbor statistical classifier. The results show that of the 30 tested cases, 23 files are differentiated correctly using the attenuation coefficient.

Acoustic non-linearity method for estimating the ratio of bound to free water of biological media

The acoustic non-linear properties of bound and free water in biological media are treated based on their structural differences. A model describing the different effects of bound and free water in protein-water solutions and in biological media is proposed. The ratio of bound to free water can be estimated from this model from measurements of the acoustic non-linearity parameter B/A, the sound speed, and the density of the specimens.

Ultrasonic absorption frequency dependence of two widely used anti-cancer drugs: doxorubicin and daunorubicin

Low intensity ultrasound (approximately 10(-6) W cm-2) in the frequency range 0.5-6.0 MHz was employed to investigate the ultrasound absorption properties of doxorubicin (DOX) at several temperatures. At physiological temperatures, we found enhanced ultrasound absorption from DOX, and its closely related analogue daunorubicin (DNR), in the upper kilohertz frequency range. The findings do not conform to classical theory of ultrasound absorption, thus suggesting an ultrasound coupling with the drug molecules via structural and/or chemical relaxation processes. The absorption spectra are analysed from the point of view of the non-classical theory of sound absorption due to physical and/or chemical relaxations. Only one spectral difference between the two anti-cancer agents is observed, around 2 MHz, and may be attributed to the sole difference in the chemical make-up of the side chain of the two antibiotics.

Effects of in utero ultrasound exposure on the development of the fetal mouse testis

The effect on the developing fetal testis of in utero exposure to 1-MHz, continuous-wave ultrasound in the spatial peak, temporal average intensity range 0.5-10 W/cm2 for durations of 400-30 sec on Day 9, 12, or 15 of gestation was determined. Results show that two subtle, yet potentially deleterious, effects occurred: a reduction in the Sertoli cell population and an apparent delay in the cessation of gonocyte mitosis. An increase was also seen in the number of fetal resorptions and stillborn pups per number of implantation sites in the exposed specimens as compared to the sham and cage controls. Because the reduction in testis weight was proportional to decreased body weight and because there was no difference in Sertoli cell numbers due to day of treatment, the testicular effects may reflect a generalized delay in growth. Whether this effect of ultrasound on fetal testis will be translated into an equal reduction in germ cell numbers in the adult testis remains to be determined.

The effects of A23187 on the phospholipid phase transition of large unilamellar vesicles (LUVs) as detected by ultrasound spectroscopy

The effect of the hydrophobic Ca2+ ionophore, A23187, on the phospholipid dynamics of large unilamellar vesicle (LUVs: 4: 1 (w/w) mixture of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG] membranes, as a function of A23187 content, was investigated using techniques sensitive to the phospholipid phase transition. The ultrasonic absorption per wavelength, alpha lambda, was determined with a double crystal acoustic interferometer, as a function of temperature and frequency for LUVs in the vicinity of their phospholipid phase transition. Differential scanning calorimetry (DSC) and electron spin resonance (ESR) were also employed to probe the thermodynamics and molecular environment of the hydrocarbon side chains. With increasing A23187 content, the phase transition temperature (Tm) of the LUV suspensions remained near 42.0 degrees C, while the amplitude of alpha lambda at the phase transition increased dramatically. At Tm the relaxation frequency, where alpha lambda max occurs, decreased with A23187 content, suggesting that the relaxation rate of the event responsible for the absorption of ultrasound decreased. The ESR studies showed no change in the fluidity of the bilayer with the inclusion of 2 and 5 mol% A23187 in the C-12 region of the bilayer. Therefore, A23187 in LUV membranes slows the structural relaxation of the hydrocarbon side chains of the phospholipid bilayer at the phase transition.

The effects of 2H2O on the phase transition of large unilamellar vesicle (LUV) suspensions as detected by ultrasound spectroscopy and electron spin resonance

The importance of water in the molecular dynamics of large unilamellar vesicle (LUV) suspensions, in which increasing portions of the water were replaced by 2H2O, was investigated. Determinations of the ultrasonic absorption coefficient per wavelength, alpha lambda, were performed as a function of temperature and frequency for LUVs (LUVs: 4:1 (w/w) mixture of dipalmitoylphosphatidylcholine, DPPC, and dipalmitoylphosphatidylglycerol, DPPG) in the vicinity of their phospholipid phase transition, using a double crystal acoustic interferometer. Electron spin resonance (ESR) and differential scanning calorimetry (DSC) were also employed to probe this system. When increasing portions of the aqueous content of the LUV suspensions were replaced by 2H2O the phase transition temperature increased from 42.0 degrees C to 42.9 degrees C (indicating an increase in the activation energy of the transition), and the amplitude of alpha lambda at the phase transition increased. However, alpha lambda max as a function of frequency at the phase transition did not change with the addition of 2H2O, indicating that the relaxation time of the event responsible for the absorption of ultrasound was unaffected. The increase in the activation energy of the transition with the addition of 2H2O suggested that the mobility of phospholipids near the membrane/aqueous interface was changed. Electron spin resonance (ESR) experiments on LUVs with nitroxide spin probes positioned at the membrane/aqueous interface (5-doxyl stearate and CAT16) showed that LUVs in 2H2O have a broader splitting, Amax, at the membrane/aqueous interface than do LUVs in H2O. These results suggest that 2H2O changes the mobility and/or structure of the phospholipids in the region of the membrane/aqueous interface. This difference in Amax was not seen for the probe PC-12-doxyl stearate, which resides at the C-12 position of the bilayer.

Effects of divalent cations on the ultrasonic absorption coefficient of negatively charged liposomes (LUV) near their phase transition temperature

The ultrasonic absorption coefficient per wavelength (alpha lambda), as a function of temperature and frequency, was determined for large unilamellar vesicles (LUV) in the vicinity of their phospholipid phase transition temperature, using a double crystal acoustic interferometer. (The vesicles were composed of a 4:1 (w/w) mixture of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG). It has been found that alpha lambda reaches a maximum (alpha lambda)max at the phase transition temperature (tm) of the phospholipids in the bilayer, at an ultrasonic relaxation frequency of 2.1 MHz. Divalent cations (Ca2+ and Mg2+), added to LUV suspensions, shifted (alpha lambda)max to higher temperatures, dependent upon the concentration of divalent cation. It was also found that the shape of the alpha lambda versus t curve was significantly changed, representing changes in the Van't Hoff enthalpy of the transition, and therefore, the cooperative unit of the transition. This suggests that divalent cations interact individually with the negatively charged phospholipid headgroups of DPPG and with DPPC headgroups, thus decreasing the cooperative unit of the transition. The observed upward shift in tm suggests an interaction that increases the activation energy and, therefore, the temperature of the phase transition. However, alpha lambda as a function of frequency did not change with the addition of divalent cations and, thus, the relaxation time of the event responsible for the absorption of ultrasound is not changed by the addition of divalent cations.

Attenuation and speed of ultrasound in lung: dependence upon frequency and inflation

The dependence of the speed of sound and the attenuation coefficient upon exposure frequency, in the range of 1-5 MHz, and upon level of inflation, in the range of mass density 0.35-0.7 g/cm3, are reported. The speed of sound decreases linearly and the attenuation coefficient increases exponentially, for all levels of inflation studied.

The potentiating effect of platelet on plasminogen activation by tissue plasminogen activator

A new role for platelets in fibrinolysis is proposed. Platelets (euglobulin from platelet rich plasma and from human platelet extract) may potentiate plasminogen activation by tissue plasminogen activator (tPA). The potentiating activity was detected by both chromogenic substrate and fibrin plate analysis. The fibrinolysis-potentiating substance in the platelets required the presence of both tPA and plasminogen, suggesting that it potentiates the activation of plasminogen by tPA. This substance was not related to fibrinogen degradation products because it was also present in platelets from two afibrinogenemic patients and did not lose its activity when separated from fibrinogen-related antigen by Sepharose 2B gel filtration. Since platelets contain both activator(s) and inhibitor(s) of plasminogen activation by tPA, a balance between activator(s) and inhibitor(s) in platelets may also be required for control of the fibrinolytic pathway.

Aggregation of chymotrypsin-treated thrombasthenic platelets is mediated by fibrinogen binding to glycoproteins IIb and IIIa

Previous experiments demonstrated that chymotrypsin, but not adenosine diphosphate (ADP), exposed fibrinogen binding sites on platelets from patients with Glanzmann's thrombasthenia. Three of these patients have been reexamined, and previous observations were confirmed. The quantity of iodine 125-labeled glycoprotein IIb (GPIIb) and glycoprotein IIIa (GPIIIa) on the platelets of these patients was considerably less than normal but was detectable by immunoprecipitation, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and autoradiography. The amount of residual GPIIb and GPIIIa as measured by binding studies with radiolabeled monoclonal antibodies was between 3% and 12% of the normal value. Platelet suspensions from these patients did not aggregate with fibrinogen and did not bind 125I-fibrinogen on stimulation with ADP. However, incubation of these platelets with chymotrypsin or pronase resulted in fibrinogen binding and platelet aggregation. Monoclonal antibodies specific for the GPIIb-GPIIIa complex blocked both the fibrinogen binding and the aggregation of enzyme-treated platelets. The treatment of washed platelets of a fourth thrombasthenic patient with ADP or with chymotrypsin failed to result in fibrinogen binding and aggregation. However, the level of GPIIb and GPIIIa on these platelets as measured by a Western blot technique and by monoclonal antibody binding amounted to less than 0.35% to 0.5% of normal values. In conclusion, fibrinogen binding sites exposed on thrombasthenic platelets by chymotrypsin are derived from GPIIb-GPIIIa molecules. Aggregation of chymotrypsin-treated thrombasthenic platelets by fibrinogen appears to represent a sensitive test for detection of functionally active GPIIb-GPIIIa complex on the platelet surface.

Ultrasonic absorption and permeability for liposomes near phase transition

The specific ultrasonic absorption coefficient per wavelength as a function of temperature in the vicinity of the phase transition of liposomes, composed of a 4:1 mixture of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG), of different sizes was determined using an acoustic interferometer. Small unilamellar vesicles (SUV) and multilamellar vesicles (MLV) yielded results similar to those in the literature, viz., an absorption maximum at the transition temperature. Seven intermediate sizes including several size distributions of large unilamellar vesicles (LUV) were studied, yielding information on size dependencies of the temperatures at which the peaks occur, the widths at half peak amplitude, and the peak amplitudes. All liposome sizes except the SUV exhibited approximately the same transition temperature as did the largest MLV. The widths of the peaks were inversely related to liposome size, with a strong dependence for the smallest vesicles and an approach to independence for the largest vesicles. The amplitudes of the peaks exhibited a general increase with size with two exceptions, viz., the SUV and the vesicles with average diameters of 90-100 nm. It was also found that the membrane permeability increased near the transition temperature. The temperature dependencies of ultrasonic absorption and membrane permeability are compared.

Ultrasonically induced temperature elevation in mouse ovary

Temperature increases, resulting from exposure to 1 MHz ultrasound, were measured in in situ and in exteriorized mouse ovaries. It is concluded that temperature increases from exposure to 10 W/cm2 and less are probably not significant for producing ovarian tissue damage, but that 25 W/cm2 exposures, and greater, are of such magnitude that damaging thermal levels ensue. The significance of blood flow in removing ultrasonically generated heat has been observed quantitatively.

Ultrasonic evidence for structural relaxation in large unilamellar liposomes

The ultrasonic absorption of large unilamellar vesicles (average diameter 0.2 micron) was determined in the frequency range 0.5-5 MHz. The liposomes were composed of a 4:1 mixture by weight of dipalmitoyl phosphatidylcholine and dipalmitoyl phosphatidylglycerol. They were studied with and without cholesterol or gramicidin incorporated into the bilayer. A large increase in absorption occurs at the solid to liquid-crystalline phase transition temperature (42 degrees C) of the pure lipid vesicles. This increase in absorption is interpreted as a structural relaxation of the 'melting' fatty acid chains occurring with an average relaxation time of 76 ns. The liposomes were also found to be extremely permeable near the transition temperature. Essentially complete release of cytosine arabinoside, a small water-soluble molecule, occurred at 42 degrees C. Addition of cholesterol or gramicidin to the bilayer of the liposomes broadened the ultrasonic absorption and reduced the efflux of cytosine arabinoside at the phase transition. No increase in absorption was observed at the transition temperature in the presence of 50 mol% of cholesterol. Gramicidin, in addition to broadening the transition, slows the isomerization of bonds in the hydrocarbon chains of the lipids. A concentration of 5 mol% gramicidin increased the average relaxation time to 211 ns.

Plasminogen Paris I: congenital abnormal plasminogen and its incidence in thrombosis

An abnormal plasminogen was discovered because of a decreased level of plasminogen activity in plasma contrasting with a normal level of plasminogen antigen concentration. The same discrepancy was found in the purified plasminogen. The molecular abnormality seems to be inherited. The patient is a heterozygote. The experimental findings can be explained by assuming that half of the plasminogen is normal, while the other half is an inactive mutant protein, without catalytic activity after SK or UK addition. There was no binding of labeled DFP and a decreased binding of TLCK to the abnormal plasminogen. The role of the abnormal plasminogen in thrombotic tendency is uncertain since the patient is the only one who has suffered a thrombotic accident, while her relatives who present the same defective plasminogen have not had thrombotic problems.

Fibrinogen binding on human platelets. Influence of different heparins and of pentosane polysulfate

Unfractionated heparin increased the binding of fibrinogen on ADP-treated platelets. The results varied according to both, the platelets of the donor and the kind of heparin preparation used. Beef lung heparin was more active than porcine intestinal mucosa heparin (p less than 0.02). A fraction of low molecular weight low sulfated heparin, did not significantly increase the binding of fibrinogen, except in one case for which the binding of fibrinogen to platelets was largely increased by standard heparin. On the contrary, pentosane polysulfate, a sulfated polysaccharide (of low molecular weight) significantly increased the binding of fibrinogen (p less than 0.01).

Ultrasonically induced morphological damage to mouse ovaries

Mouse ovaries were exposed in vivo to 1 MHz continuous wave ultrasonic energy at spatial peak intensities ranging from 5 to 100 W/cm2 for times varying from 300 to 15 s depending on the intensity. Following exposure the ovaries were surgically removed at times ranging from immediately (within 60 s) to 7 days and prepared histologically for light microscopic analysis. The observed tissue alterations varied from severe, at the higher intensities to subtle, at the lower intensities. Lesions were manifested by pyknosis of cells, vacuolization of cells and tissue, eosinophilic cytoplasm, and general cellular disruption. Subtle alterations showed large numbers of polyovular follicles and increases in the amount of PAS positive material in the interstitial tissue. Various ovarian structures showed differing sensitivities to the insult with luteinized structures being preferentially altered.

Ultrasound biologic effects: a suggestion of strain specificity

Pregnant hybrid LAF1/J mice were exposed to continuous-wave ultrasonic energy at a frequency of 1 MHz at a spatial peak intensity of either 2.5 W/cm2 or O W/cm2 (sham) for 20 seconds on the eighth day of gestation. Fetal weight (day 18 of gestation) and postpartum pup weight (21, 29 and 42 days post conception) were determined. No significant differences in weight were observed. This result differs from findings in others studies using outbred mouse strains. It is suggested that hybrid mice exposed to ultrasonic energy in utero may be more resistant to alterations in fetal and pup weight progression as compared with outbred strains.

The amidolytic activity of the SK-plasminogen complex is enhanced by a potentiator which is generated in the presence of vascular plasminogen activator--role of fibrin degradation products

In the presence of an excess of streptokinase (SK) the amidolytic activity of the plasminogen-SK complex on chromogenic substrates is 12% lower in serum than in the corresponding plasma. However, in subjects in whom venous stasis lead to a shortening of the euglobulin lysis time to less than 60 min (high responders), the amidolytic activity of the plasminogen-SK complex in serum was 60% higher than in the corresponding plasma. Attempts to find alterations of the plasminogen molecule itself which would account for the enhanced activity in high responder serum were negative. No free plasmin was present and the plasminogens isolated from plasma and serum before and after venous stasis had the same amidolytic activity as gluplasminogen in the presence of an excess of SK. N-terminal analysis of these four plasminogens revealed in each instance glutamic acid. The enhancement of the amidolytic activity of the SK-plasminogen complex in serum of high responders (potentiator activity) could be reproduced by adding purified tissue plasminogen activator (TA) to native blood before clotting, but not if TA was added to plasma or to prestasis serum. Removal of fibrin degradation products from poststasis serum resulted in the disappearance of potentiator activity. These experiments suggest that fibrin degradation products, generated during clotting in the presence of vascular or tissular plasminogen activator act as a potentiator of the amidolytic activity of the plasminogen SK-complex.

Nonlinear ultrasonic propagation in biological media

The nonlinearity parameter B/A for several biological materials was determined by measuring the amplitude of the second harmonic pressure as a function of distance from the source and the amplitude of the fundamental at the source. The B/A values for bovine serum albumin and haemoglobin solutions were found to increase approximately linearly with solution concentration. Blood and homogenized liver exhibit a B/A value similar to a haemoglobin solution of the same dry weight, but whole liver has a greater B/A value.