Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Injections, Jet”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 919 records · Page 51Linked to original sources
PubMed2004

Vibrational dynamics of medium strength hydrogen bonds: Fourier transform infrared spectra and band contour analysis of the DF stretching region of (CH2)2S-DF.

Fourier transform infrared spectra of the nu(s) band of the (CH2)(2)S-DF complex have been recorded at 0.1-0.5 cm(-1) resolution in a cooled cell and in a supersonic jet expansion seeded with argon. A sufficient density of (CH(2))(2)S-DF heterodimers is produced by a double injection nozzle device, which limits the possibility of reaction between thiirane and DF before the expansion. The observation of partially resolved PQR branch structures at cell temperatures as high as 252 K indicates relatively small effective line widths, which allow a detailed analysis of the underlying vibrational couplings and of the structural properties of the complex. The analysis of cell and free jet spectra in the temperature range 50-250 K is performed with a software package for the simulation and fitting of multiple hot band progressions in asymmetric rotors. The analysis reveals that the three low frequency hydrogen-bond modes are strongly coupled to the DF stretch with anharmonic coupling constants, which indicates a strengthening of the hydrogen bond upon vibrational excitation of DF. Rovibrational parameters and a reliable upper bound for the homogeneous line width have been extracted.

Computer Simulation↗
PubMed1990

In vitro analysis of jets by Doppler colour flow imaging: the importance of time to maximum jet area.

Regurgitant jets were simulated in vitro and analysed using Doppler colour flow imaging. The regurgitant volumes were estimated using total jet area (JA), variance area (VA), and the maximum area of variance x time to maximum area of variance (MAVT). Both flow rate and injected volume were significantly correlated to area of variance (r = 0.89 and r = 0.98, respectively) for a given orifice size. When MAVT was analysed, it correlated better to injected volume (r = 0.97) at a fixed flow rate, than varying flow rate (r = 0.69) at a fixed injected volume. The relationship between MAVT and injected volume was also examined with varying flow rate. There was a highly significant correlation between MAVT and injected volume under these circumstances (r = 0.99). A similar relationship between MAVT and injected volume was found when the orifice size was altered. Using multivariate regression analysis the injected volume was best defined by MAVT (R2 = 0.88). The addition of orifice size only improved the fit to the model marginally (R2 = 0.90). These data document the importance of analysing the time to maximum area of variance when applying Doppler colour flow imaging to regurgitant jets. MAVT is a better predictor of regurgitant volumes in vitro compared with jet sizes alone and may have potential use in man to quantify the severity of regurgitant valve lesions.

Aortic Valve Insufficiency↗
PubMed1985

Volatile carboxylic acid profiling in physiological fluids: direct injection into a gas chromatograph/mass spectrometer.

We present a procedure for the profiling of the volatile carboxylic acids and neutral compounds in blood or urine using the direct injection of the acidified sample into a gas chromatograph interfaced with a mass spectrometer by a jet separator. The non-volatile components remain at the head of the SP-1000 column while the volatile components move through the column. Up to sixty physiological samples can be analyzed before any degradation in mass spectrometer operating parameters is observed.

Carboxylic Acids↗
PubMed2005

Sympathetic hyperreactivity to air-jet stress in the chromosome 1 blood pressure quantitative trait locus congenic rats.

A chromosome 1 blood pressure quantitative trait locus (QTL) was introgressed from the stroke-prone spontaneously hypertensive rats (SHRSP) to Wistar-Kyoto (WKY) rats. This congenic strain (WKYpch1.0) showed an exaggerated pressor response to both restraint and cold stress. In this study, we evaluated cardiovascular and sympathetic response to an air-jet stress and also examined the role of the brain renin-angiotensin system (RAS) in the stress response of WKYpch1.0. We measured mean arterial pressure (MAP), heart rate (HR), and renal sympathetic nerve activity (RSNA) responses to air-jet stress in WKYpch1.0, WKY, and SHRSP. We also examined effects of intracerebroventricular administration of candesartan, an ANG II type 1 receptor blocker, on MAP and HR responses to air-jet stress. Baseline MAP in the WKYpch1.0 and WKY rats were comparable, while it was lower than that in SHRSP rats. Baseline HR did not differ among the strains. In WKYpch1.0, air-jet stress caused greater increase in MAP and RSNA than in WKY. The increase in RSNA was as large as that in SHRSP, whereas the increase in MAP was smaller than in SHRSP. Intracerebroventricular injection of a nondepressor dose of candesartan inhibited the stress-induced pressor response to a greater extent in WKYpch1.0 than in WKY. Intravenous injection of phenylephrine caused a presser effect comparable between WKYpch1.0 and WKY. These results suggest that the chromosome 1 blood pressure QTL congenic rat has a sympathetic hyperreactivity to an air-jet stress, which causes exaggerated pressor responses. The exaggerated response is at least partly mediated by the brain RAS.

Animals↗
PubMedDate not supplied

Teflon injection of vocal cords under general anesthesia: a new method.

Use of general anesthesia permits the injection of Teflon paste into immobile vocal cords in an accurate and predictable manner, with the help of a special endotracheal tube and jetted O2 or O2/n2O mixture. The authors position a nonfunctioning vocal cord so that when the functioning cord is fully adducted , the two cords are in perfect approximation for phonation. This has allowed marked improvement in effective expulsive postoperative coughing and vocalization. Debris is blown away from the operating side and not into the patient's trachea. If excessive injection of Teflon is avoided, an uneventful postoperative course can be expected.

Anesthesia, Endotracheal↗
PubMed2004

Disposable twin gold electrodes for amperometric detection in capillary electrophoresis.

We describe a simple and easy way to construct gold microelectrodes for amperometric detection in capillary electrophoresis (CE). The gold microelectrodes, in single or twin sets, were obtained from recordable compact discs (gold-sputtered type), which present highly reproducible surface characteristics. The performance of these electrodes was evaluated by using a home-made CE equipment. The basic steps for the electrode construction are: drawing on a microcomputer; laser printing of the design on wax paper; heat-transfer of the toner onto the gold surface of a peeled recordable compact disc (CD-R); etching of the gold layer from unprinted regions; removal of the toner with a solvent; sealing of unused electrode areas with varnish. One electrode at a time was connected to a potentiostat (or two, to a bipotentiostat) and operated in a wall jet configuration relative to the CE capillary outlet. The amperometric signals were integrated for quantification purposes. Repetitive injections (n = 10) of a mixture containing iodide, ascorbic acid, dipyrone, and acetaminophen (20, 200, 500, and 100 microM), presented relative standard deviations of 2.9, 4.5, 6.1, and 4.0%, respectively. For these analytes, the detection limits (S/N = 3, 30 s of 100 mm hydrodynamic injection) were 0.1, 0.5, 3.1, and 1.1 microM, respectively.

Disposable Equipment↗
PubMed2006

A near real-time system for continuously monitoring airborne subtilisin-type enzymes in the industrial atmosphere.

We describe the development and validation of a portable system comprising an air sampler coupled to an automated flow injection analysis device. The system is able to monitor airborne concentrations of subtilisin-type enzymes in the workplace atmosphere on a continuous basis. Sampling is in two stages: using a sampling head that is designed to mimic human respiration at approx. 1 m s(-1) at a sampling rate of 600 l min(-1). In the second stage, the captured particles are deposited by impaction from the air stream onto the inner surface of a cyclone that is continuously washed with a jet of buffer solution. Deposited particles are then washed into a reservoir from which samples are taken every 5-6 min and injected automatically into a continuous flow injection analysis system. Proteolytic enzyme in the sample passes through a bioreactor maintained at about 40 degrees C. This contains a cellulose solid phase matrix on which is covalently immobilised Texas Red-labelled gelatin as substrate. The passing enzyme partially digests the substrate releasing fluorophore that is detected down stream in a flow cell coupled to a fluorimeter. The system is calibrated using enzyme standards and the intensity of the resulting peaks from the ex-air samples is converted to airborne concentrations using a mathematical model programmed into a PC. The system has a limit of detection of 4.8 ng m(-3) and a dynamic range of 5-60 ng m(-3). The within assay precision (RSD) is 6.3-9.6% over this range. The within batch precision is 20.3% at 20 ng m(-3) and the corresponding between batch value is 19.5%. The system has been run for periods up to 8 h in the laboratory and for up to 4 h at a factory site and the values obtained compared with time-averaged values obtained from a conventional Galley sampler and in-house analysis when reasonable agreement of the results was observed. The stability of the system over 21 days of continuous use with standards injected periodically was studied. Linearity was observed for all the standard plots throughout. At the end of 21 days, after a total exposure equivalent to 2395 ng ml(-1) of Savinase, the signal due to the 5.0 ng ml(-1) standard was still easily detectable.

Air Pollutants, Occupational↗
PubMed1982

Experimental central serous chorioretinopathy in monkey eyes: fluorescein angiographic findings.

In an adult Japanese monkey (Macaca fuscatus), intravenous injections of adrenalin were repeated daily: 0.125 mg/kg for 7 days and 0.375 mg/kg from the 11th day on. In a cynomolgus monkey (Macaca irus), daily injections were carried out with intravenous adrenalin (0.11 mg/kg for 12 days and a double dose from the 13th day on) and also with intramuscular prednisolone. After the 39th injection in the former and after the 32nd injection in the latter monkey, disciform serous retinal detachment was seen to occur in the posterior pole region, and fluorescein angiography revealed multiple dye leakage spots at the level of the retinal pigment epithelium. Sometimes these changes subsided, but on continuing injections, these changes recurred on new locations. Two types of fluorescein leakage spots were recognized, i.e. ink blot type with progressive simple enlargement with time and the mushroom or jet type showing these patterns during enlargement. No abnormality was found in the optic disc, retinal vessels or in the choroidal circulation. The fluorescein angiographic findings were in close resemblance with those seen in the human central serous chorioretinopathy. It was discussed that these fundus changes of the monkey eye produced by repeated adrenalin injections would serve as a good animal model of the human disease.

Animals↗
PubMed2005

Turbulent flow evaluation of the venous needle during hemodialysis.

Arteriovenous (AV) grafts and fistulas used for hemodialysis frequently develop intimal hyperplasia (IH) at the venous anastomosis of the graft, leading to flow-limiting stenosis, and ultimately to graft failure due to thrombosis. Although the high AV access blood flow has been implicated in the pathogenesis of graft stenosis, the potential role of needle turbulence during hemodialysis is relatively unexplored. High turbulent stresses from the needle jet that reach the venous anastomosis may contribute to endothelial denudation and vessel wall injury. This may trigger the molecular and cellular cascade involving platelet activation and IH, leading to eventual graft failure. In an in-vitro graft/needle model dye injection flow visualization was used for qualitative study of flow patterns, whereas laser Doppler velocimetry was used to compare the levels of turbulence at the venous anastomosis in the presence and absence of a venous needle jet. Considerably higher turbulence was observed downstream of the venous needle, in comparison to graft flow alone without the needle. While turbulent RMS remained around 0.1 m/s for the graft flow alone, turbulent RMS fluctuations downstream of the needle soared to 0.4-0.7 m/s at 2 cm from the tip of the needle and maintained values higher than 0.1 m/s up to 7-8 cm downstream. Turbulent intensities were 5-6 times greater in the presence of the needle, in comparison with graft flow alone. Since hemodialysis patients are exposed to needle turbulence for four hours three times a week, the role of post-venous needle turbulence may be important in the pathogenesis of AV graft complications. A better understanding of the role of needle turbulence in the mechanisms of AV graft failure may lead to improved design of AV grafts and venous needles associated with reduced turbulence, and to pharmacological interventions that attenuate IH and graft failure resulting from turbulence.

Arteriovenous Anastomosis↗