Electrohydrodynamic jet processing: an advanced electric-field-driven jetting phenomenon for processing living cells.
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Cell Culture Techniques↗
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[Enhancement of Doppler signals in aortic and mitral valve diseases].
Ultrasound contrast media increase backscatter from blood, thus improving the signal-to-noise ratio. Potential clinical applications of intravenous ultrasound contrast are reviewed. Contrast enhancement of continuous wave Doppler is indicated when the native recordings are noisy and no complete envelope of the Doppler spectrum is obtained. In aortic stenosis several investigations showed good agreement between the gradient calculated from Doppler measurements and the results of cardiac catheterization. In mitral insufficiency maximum area of the regurgitant jet is a widely used parameter for estimation of the severity of the regurgitation. However, assessment of the maximum jet area may not be possible because of poor acoustic windows. Contrast enhancement provides complete display of the regurgitant jet in most of the patients. The diagnostic confidence of the Doppler investigation is further improved by the recording of the pulmonary venous flow, which can be recorded in most of the patients following contrast injection. Therefore contrast enhanced transthoracic Doppler is an alternative to transesophageal Doppler investigation in patients with poor transthoracic windows.
Aortic Valve Stenosis↗
Effects of high-frequency jet ventilation on arterial baroreflex regulation of heart rate.
Fifteen anesthetized mechanically ventilated patients recovering from multiple trauma were studied to compare the effects of high-frequency jet ventilation (HFJV) and continuous positive-pressure ventilation (CPPV) on arterial baroreflex regulation of heart rate. Systolic arterial pressure and right atrial pressure were measured using indwelling catheters. Electrocardiogram (ECG) and mean airway pressure were continuously monitored. Lung volumes were measured using two linear differential transformers mounted on thoracic and abdominal belts. Baroreflex testing was performed by sequential intravenous bolus injections of phenylephrine (200 micrograms) and nitroglycerin (200 micrograms) to raise or lower systolic arterial pressure by 20-30 Torr. Baroreflex regulation of heart rate was expressed as the slope of the regression line between R-R interval of the ECG and systolic arterial pressure. In each mode of ventilation the ventilatory settings were chosen to control mean airway pressure and arterial PCO2 (PaCO2). In HFJV a tidal volume of 159 +/- 61 ml was administered at a frequency of 320 +/- 104 breaths/min, whereas in CPPV a tidal volume of 702 +/- 201 ml was administered at a frequency of 13 +/- 2 breaths/min. Control values of systolic arterial pressure, R-R interval, mean pulmonary volume above apneic functional residual capacity, end-expiratory pulmonary volume, right atrial pressure, mean airway pressure, PaCO2, pH, PaO2, and temperature before injection of phenylephrine or nitroglycerin were comparable in HFJV and CPPV. Baroreflex regulation of heart rate after nitroglycerin injection was significantly higher in HFJV (4.1 +/- 2.8 ms/Torr) than in CPPV (1.96 +/- 1.23 ms/Torr).(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Methohexital vs midazolam/flumazenil anaesthesia during laryngoscopy under jet ventilation.
In a randomised clinical study, two total intravenous anaesthesia techniques for microlaryngoscopic laser surgery were compared. After an induction dose of 100 mg methohexital, Group I received a maintenance infusion of 10 mg.min-1. In Group II anaesthesia was obtained by 15 mg midazolam followed by 0.1 mg.min-1 continuously and terminated by the injection of flumazenil. For analgesia 5 mg alfentanil were administered. Opiate-induced respiratory depression was antagonised by 0.08 to 0.12 mg naloxone. Prior to, during, and after surgery, adrenergic response was assessed by HPLC-analysis of blood taken from a peripheral vein. Haemodynamic responses to the operation and during the post-operative period were almost identical in both groups. In Group I, the mean recovery period of 14 min was significantly longer than in Group II (9 min), where patients received a mean dose of 0.53 mg (+/- 0.15) flumazenil. Resedation could be observed in all patients receiving flumazenil within 60 min after antagonisation, which was associated with a mean decrease in O2-saturation from 95% to 88%. There was no difference in epinephrine and norepinephrine blood levels between the two groups prior to and during anaesthesia. In all patients, arousal was associated with a significant increase in the epinephrine plasma concentration. While blood levels in Group I decreased during the post-operative period to levels prior to surgery, the concentrations in Group II remained elevated. In one patient who received no naloxone, the reversal of midazolam action induced a 16-fold increase in catecholamine levels (from 50 to 800 ng.l-1) associated with a tachycardia of 170 b.min-1 and hypertension of 160 mmHg.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Hydrodynamic effects in interacting Fermi electron jets.
We theoretically study hydrodynamic phenomena originating from electron-electron collisions in a two-dimensional Fermi system. We demonstrate that an electron beam sweeping past an aperture creates a pumping effect, attracting carriers from this aperture. This pumping effect originates from the specific electric potential distribution induced by the injected electrons. In the regions near the main stream of injected electrons, a positive potential is induced by the injected electrons. Thus, the normally repulsive Coulomb interaction leads to an attractive force in the Fermi system. This quantum pumping mechanism in a Fermi system differs qualitatively from the Bernoulli pumping effect in classical liquids. We also discuss possible experimental realizations.
Journal Article↗
[High frequency jet ventilation].
High frequency jet ventilation (HFJV) is a new ventilation technique which ensures satisfactory gas exchanges with tidal volumes of about 2 ml . kg-1. A gas mixture under high pressure is "chopped up" by an electrically-controlled solenoid valve and delivered to the patient by an injection system. A specific heater-humidifier is required for optimal humidity and warmth of the gas mixture. HFJV creates a positive end-expiratory pressure effect in the alveoles, and the increase of mean intratracheal pressure observed accurately reflects the increase of mean alveolar pressure. Convection by direct alveolar ventilation plays a determinant role in CO2 clearance under HFJV, the other gas transport mechanisms being accessory. In respiratory failure with shock HFJV is better tolerated haemodynamically than conventional ventilation. The main indications of the new technique are ENT surgery, thoracic and tracheal surgery, lithotripsy, broncho-pleural and oesophago-tracheal fistulae and circulatory shock.
Anesthesia↗
A stopped-flow/rapid-freezing machine with millisecond time resolution to prepare intermediates in biochemical reactions for electron microscopy.
We have developed an instrument capable of freezing transient intermediates in rapid biochemical reactions for subsequent freeze-fracturing, replication, and viewing by transmission electron microscopy. The machine combines a rapid mixing unit similar to one widely used in chemical kinetics (Johnson, 1986) with a propane jet freezing unit previously used to prepare static samples for freeze-fracturing (Gilkey and Staehelin, 1986). The key element in the system is a unique thin-walled flow cell of copper that allows for injection and aging of the sample, followed by rapid freezing. During freeze-fracturing, a tangential cut is made along the wall of the flow cell to expose the sample for etching and replication. The dead time required for mixing and injection of the reactants into the flow cell is less than 5 ms. Electronic controls allow one to specify, on a millisecond time scale, any time above 5 ms between initiation of the reaction and quenching by rapid freezing.
Actins↗
[The flow of contrast media in coronary catheters: study of the structural quality in interventional cardiology].
In the present study we investigated the contrast medium flow in 8 different types of left heart catheter having two different diameters (each n = 5). Using a 10 ml syringe and the contrast medium Ultravist 370, we calculated a mean value of 94.24 N + 16.01 for the maximum manual injection force in 18 test subjects. For the sake of simplicity, the figure of 100 N was defined as standardized manual force (which is within the standard deviation). If the maximally admissible static pressure of 82.5 bar is not to be exceeded, flow rates of not more than 16-17 ml/s are possible with 5.2 Fr. catheters, and 21-23 ml/s and 1.46 ml/s for 5.2 Fr. catheters, and between 1.99 ml/s and 2.17 ml/s for 6 Fr. catheters. Thus, a 50% higher flow can be achieved with 6 Fr. catheters as compared with 5.2 Fr. catheters at the same injection force. The iodine delivery rates are between 506 mg iodine/s and 539 mg iodine/s for 5.2 Fr. catheters, and between 738 mg iodine/s and 804 mg iodine/s for 6 Fr. catheters. The figures for the jet stream.
Cardiac Catheterization↗
[Results of studying a live mumps vaccine from strain L-3 manufactured by the Moscow Research Institute of Viral Preparations. The reactogenic and antigenic properties of the vaccine].
The reactogenic and antigenic properties of live mumps vaccine from the L-3 strain were studied in 1507 children of 1 to 12 years of age. A single injection was given, one immunizing dose containing 10(4)HAdU50 of mumps virus. The live mumps vaccine from the L-3 strain irrespective of the lot of preparation, kind (live or lyophilized), method of application (jet-injector or needle/syringe), age of the vaccinees and the amount of virus in the immunizing dose received by a vaccinee, was demonstrated to be practically areactogenic and markedly antigenic. Serological examinations by neutralization tests of 346 paired serum specimens established variation in seroconversion between individual lots to be within 62.5--82.3% (average 69.9%) of cases. Comparative studies on the postvaccination and postinfection immunitiy in mumps showed the level of antibody in the vaccinees to vary within 4.2--5.1 log2 in different years, and in convalescents within 5.1--5.9 log2 in the same years. The results indicate a sufficiently high and intensive immunity for 5 years (the observation period).
Antigens, Viral↗
Virus transfer from surf to wind.
Bubbles in the sea surf adsorb and carry viruses to the surface where they are propelled into the air on tiny jets of seawater when the bubble bursts. The ejected jets become tiny drops of aerosol. The buble adsorption and virus concentration in the surf is analagous to industrial bubble levitation processes that concentrate metallic ores, enzymes, and finely divided organic crystals. Bubble levitation of viruses delibrately injected into the surf produced 200 times more virus per milliliter in the aerosol than were present in samples from the surf. Some aerosol drops created by the surf and carried by the wind fall out on the beach. The frequency of virus-bearing drops, that is, the number of plaques on seeded plates exposed on the beach, decreased exponentially with the distance downwind from the surf.
Aerosols↗
[Pulsed Doppler echography in the quantification of aortic insufficiency in adults].
Since several methods based on doppler-echocardiography have been suggested to quantify aortic valve regurgitation, we compared two of these methods--left ventricular diastolic jet mapping and evaluation of blood flow in the descending aorta--with the results of left heart catheterization in 82 patients with aortic regurgitation. The invasive quantification rested on the degree of left ventricular opacification after contrast injection into the supra-sigmoid aorta, the results being classified into 3 grades. Left ventricular mapping was carried out using pulsed doppler ultrasound by the apical route; results were expressed as 3 grades of increasing severity. Blood flow in the aorta was recorded using pulsed doppler velocimetry by the suprasternal route at the level of the aortic isthmus where we measured the diastolic to systolic velocity integrals ratio (D/S). Apical mapping could be performed in 81 of the 82 patients, whereas suprasternal planimetry could be performed in only 56 patients (68 p. 100). Mapping provided good correlations with catheterization in 65 patients (80 p. 100); discordances were observed mainly in patients with aortic leakage due to prosthetic valve dysfunction (4/8 prosthetic valves) or with major left ventricular dilatation (found in 7 out of 9 cases of underestimation of leakage by the doppler system). The D/S ratio values obtained by the suprasternal route ranged from 16 to 28 p. 100 for mild angiographic leakage, from 34 to 66 p. 100 for moderate leakage, and from 52 to 155 p. 100 for severe leakage. "Borderline" values of 30 and 60 p. 100 respectively enabled the various degrees of aortic regurgitation to be separated. Despite their limitations, the non-invasive methods used in combination are effective in quantifying aortic regurgitation in most cases; mapping offers the advantage of simplicity: the suprasternal study is more accurate but cannot be performed in all patients.
Adult↗
[Morphologic changes in the skin and underlying tissues after the administration of biopreparations into the body by a needle-less (jet) method].
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Animals↗
Contribution of the autonomic nervous system to blood pressure and heart rate variability changes in early experimental hyperthyroidism.
A great deal of uncertainty persists regarding the exact nature of the interaction between autonomic nervous system activity and thyroid hormones in the control of heart rate and blood pressure. We now report on thyrotoxicosis produced by daily intraperitoneal (i.p.) injection of L-thyroxine (0.5 mg/kg body wt. in 1 ml of 5 mM NaOH for 5 days). Control rats received i.p. daily injections of the thyroxine solvent. In order to estimate the degree of autonomic activation in hyperthyroidism, specific blockers were administered intravenously: atropine (0.5 mg/kg), prazosin (1 mg/kg), atenolol (1 mg/kg) or the combination of atenolol and atropine. A jet of air was administered in other animals to induce sympathoactivation. Eight animals were studied in each group. The dose and duration of L-thyroxine treatment was sufficient to induce a significant degree of hyperthyroidism with accompanying tachycardia, systolic blood pressure elevation, increased pulse pressure, cardiac hypertrophy, weight loss, tachypnea and hyperthermia. In addition, the intrinsic heart period observed after double blockade (atenolol + atropine) was markedly decreased after treatment with L-thyroxine (121.5+/-3.6 ms vs. 141.2+/-3.7 ms, P < 0.01). Of the autonomic indices, vagal tone (difference between heart period obtained after atenolol and intrinsic heart period) was negatively linearly related to intrinsic heart period (r = 0.71, P < 0.05). Atenolol modified neither the heart period nor blood pressure variability in rats with hyperthyroidism and in these rats the jet of air did not significantly affect the heart period level. The thyrotoxicosis was associated with a reduction of the 0.4 Hz component of blood pressure variability (analyses on 102.4 s segments, modulus 1.10+/-0.07 vs. 1.41+/-0.06 mm Hg, P < 0.01) and prazosin was without effect on this 0.4 Hz component in these animals. These data show a functional diminution of the vascular and cardiac sympathetic tone in early experimental hyperthyroidism. The marked rise in the intrinsic heart rate could be the main determinant of tachycardia. The blood pressure elevation may reflexly induce vagal activation and sympathetic (vascular and cardiac) inhibition.
Adrenergic alpha-Antagonists↗
Synchronization of mammalian circadian rhythms by melatonin.
While pinealectomy (Px) has little effect on mammalian circadian rhythms, daily injections of the pineal hormone melatonin in rats have profound effects. These can be classified according to their effects under three categories of desynchronization: external desynchronization, internal desynchronization and phase-shift of the zeitgeber (Aschoff, 1969). Externally desynchronized rats, free-running in constant darkness (DD), can be entrained to a 24-hour regime of melatonin injection. Entrainment depends upon the suprachiasmatic nuclei (SCN) since lesions to the SCN prevent it. Although no animal model for internal desynchronization exists, rats whose circadian rhythms are disrupted or arrhythmic in constant light (LL) are synchronized by daily melatonin injection, and the rate and direction of responses to phase-shift of the zeitgeber can be altered with daily melatonin administration. These and other results suggest melatonin may be useful therapeutically for such human desynchronizations as jet-lag and shiftwork, and preliminary data using human subjects are presented.
Adult↗
Transplantation of cultured rabbit retinal epithelium to rabbit retina using a closed-eye method.
We have developed a closed-eye technique for transplanting cultured rabbit retinal epithelial cells to Bruch's membrane of the rabbit. A glass micropipette containing a suspension of 3H-thymidine-labeled, cultured retinal pigment epithelial (RPE) cells is inserted through a pars plana incision and positioned adjacent to the neural retina. A jet stream from the pipette is used to make a small retinal hole and bleb detachment. Patches of host retinal epithelium lift off with the neural retina, creating areas of bare Bruch's membrane. The cell suspension is injected into the subretinal space, and labeled cells can be seen attached to Bruch's membrane as early as 1 hr later. The neural retina spontaneously reattaches within 24 to 48 hr, bringing photoreceptor outer segments in direct contact with the transplanted cells. Phagocytosis of outer segment material by transplanted cells can be seen as early as 24 hr after surgery. This closed-eye technique offers an advantage over the open-sky method used previously in that it allows for reattachment of the neural retina and at least a partial return of function in the transplanted retinal epithelium.
Animals↗
Jet ventilation for laser laryngeal surgery in children. Modification of the Saunders jet ventilation technique.
In our clinical series, 40-50% O2 and 50-60% N2O (regulated by a blender and delivered by manual jet ventilation (MJV] and residual halothane from induction provided satisfactory supralaryngeal anesthesia. Fentanyl, N2O, atracurium, and lidocaine administered i.v. effectively blunted laryngeal stimulation, allowed control of respiration, and minimized vocal cord motion. Wide unobstructed surgical access to the entire endolarynx is provided. Atracurium (an intermediate-acting non-depolarizing muscle relaxant administered in a single bolus or by constant infusion) achieves the needed level of blockade and permits the anesthesiologist to focus on the pattern of respiration rather than the degree of neuromuscular blockade. Its duration of action seems to be well matched to the average duration of this surgical procedure. Because its reversal is prompt (35-45 min from i.v. injection to 25% recovery by neuromuscular transmission monitor) (Brandom et al., Clinical pharmacology of atracurium in paediatric patients, Br. J. Anaesth., 55 (1983) 117S-121S) children can be discharged safely from the recovery room to home after an appropriate period of observation in the short-stay unit. Our report confirms and extends another recent report supporting supraglottic jet ventilation (Scamman, F.L. and McCabe, B.F., Supraglottic jet ventilation for laser surgery of the larynx in children, Ann. Otol. Rhinol. Laryngol., 95 (1986) 142-145). We believe that the MJV technique is advantageous in children, particularly for outpatient surgery. Attention to detail and careful communication between a skilled anesthesiologist and surgeon are essential. Dangerous barotrauma can occur and skill and monitoring are essential.
Adolescent↗
[Use of jet injectors for smallpox immunization. 2. Immunologic response to experimental intradermal jet injector administration of smallpox vaccine].
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Adolescent↗
Ventilation with rigid bronchoscopes. Evaluation of resistance by pressure drop by a proposed international standard.
UNLABELLED: The ISO 8600-2-1 draft standard concerns measuring methods for ventilation properties in rigid bronchoscopes. Two lung models were designed in accordance with this draft, one for conventional ventilation, and the other for jet-ventilation (venturi ventilation). Lung model I: An air supply was connected to a 4 liter container. The test object (bronchoscope) was exposed to air flowing out of the container through the bronchoscope, and the pressure in the container was recorded. The flow velocities were 20-60 l.min-1. Lung model II: A pressure gauge was connected to a 2 liter container. The test object was introduced into the container through an gastight opening. A pressure gas injector was connected to either the instrument port or the ventilation port of the bronchoscope. The injected pressures were 100-500 kPa. RESULTS: Study I. The pressure drop increased exponentially with increasing air flow. It also increased rapidly with decreasing diameter of the bronchoscope. Study II. The pressure in small bronchoscopes increased very fast with increasing injection pressure. Dangerous pressures (above 50 cmH2O) were reached already at 2 kg.cm-2 with the smallest bronchoscopes. We suggest that the results should be given as "pressure drop" and not as "resistance".
Airway Resistance↗