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At least 865 records · Page 48Linked to original sources
PubMed1989

High frequency jet ventilation in horses: an experimental study.

High frequency jet ventilation (HFJV) is a recently developed mode of ventilation that delivers small tidal volumes at frequencies greater than 60 cycles per min via an injection catheter to the animal's airway. The construction of a high frequency jet ventilator suitable for use in adult horses is described. The effectiveness of this ventilator in maintaining normal arterial blood-gas tension was evaluated in five healthy adult horses. The horses were anaesthetised with intravenous acetylpromazine, guaifenesin, and thiamylal, positioned in lateral recumbency and baseline measurements were made during spontaneous ventilation. The horses were then paralysed with succinylcholine and ventilated for at least 20 mins with HFJV. Air was delivered from the ventilator to the animal by a polyethylene tube. The tip of this tube remained within and approximately 30 cm from the cuffed end of a standard 30 mm internal diameter large animal orotracheal tube. Frequency of flow interruption was 3 Hz with a constant source pressure of 275 kPa and an inspiratory to expiratory ratio of approximately 1:2.6. Gas delivery to the horse, as estimated with a resonator system was approximately 2 litres/breath. During HFJV, arterial carbon dioxide tension was significantly reduced and arterial oxygen tension significantly increased above measurements made when the horses were spontaneously breathing air.

Animals↗
PubMed2002

A novel method of drug delivery for fibrinolysis with Ho:YAG laser-induced liquid jet.

Two of the problems inherent in the treatment of cerebral emboli are the narrow therapeutic time window and the severe side effects of fibrinolytic drugs. Thus, it is necessary to develop a new method of removing a cerebral thrombus more rapidly and with smaller quantities of fibrinolytics. The behaviour of a bubble formed by holmium (Ho):YAG laser irradiation in a capillary tube filled with pure water was observed at various stand-off distances (L; distance between the end of optical fibre and the capillary exit). Subsequently, a liquid-jet generator was created by insertion of an optical fibre (core diameter: 0.6 mm) into a catheter (6 Fr) filled with pure water, and a pulsed Ho:YAG laser (pulse duration time=350 micros, laser energy=230 mJ/pulse) was used to irradiate the optical fibre. The maximum penetration depth, into a gelatin artificial thrombus, of a liquid jet generated with this device was measured for various stand-off distances. Additionally, the phenomenon and the pressure around the catheter exit were captured via shadowgraph and PVDF needle hydrophone, respectively. The laser-induced bubble in the capillary tube grew rapidly in the direction of propagation and generated a liquid jet. The maximum penetration depth of this liquid jet into an artificial thrombus increased in proportion to L and reached a maximum value (9 mm) when L was around 13 mm. A shock wave whose overpressure at a point 4 mm away from the catheter exit exceeded 12 MPa was captured by shadowgraph. It was concluded that Ho:YAG laser irradiation within a water-filled catheter caused liquid jet formation, which could penetrate straight into an artificial thrombus. Hence, this jet is expected to promote fibrinolysis by means of injecting fibrinolytics deeply into the thrombus. After resolving some problems, this system will be applied to an endovascular therapy for cerebral embolisms in the near future.

Catheterization↗
PubMed2002

Determination of glucose oxidase immobilised as monolayer onto a flat surface.

An assay to estimate the amount of glucose oxidase immobilised as a monolayer onto a flat surface is reported. This method is based on the electrochemical detection of the flavin adenine dinucleotide (FAD) cofactor released by the immobilised enzyme in acid solutions. FAD concentration in the acid solution was measured by amperometry, using a flow injection analysis (FIA) system equipped with a wall-jet electrode, and with a sensitivity of (9.2+/-2.0)x10(-2) nA/nM. By this method, the amount of glucose oxidase molecules present in a monolayer deposited on a silanised glass slide was easily detected, in which the detection limit is more than one order of magnitude lower than the maximum loading of the surface with an ordered monolayer of glucose oxidase.

Aspergillus niger↗
PubMed2003

Use of tracer tests to evaluate the impact of enhanced-solubilization flushing on in-situ biodegradation.

Tracer tests were conducted to evaluate the effect of a complexing sugar flush (CSF) on in-situ biodegradation potential at a site contaminated by jet fuel, solvents, and other organic compounds. Technical-grade hydroxypropyl-beta-cyclodextrin was used during the CSF study, which was conducted in a hydraulically isolated cell emplaced in a surficial aquifer. In-situ biodegradation potential was assessed with the use of tracer tests, which were conducted prior to and immediately following the CSF study. Ethanol, hexanol, and benzoate were used as the biodegradable tracers, while bromide was used as a nonreactive tracer. The results indicate that the biodegradation of benzoate was similar for both tracer tests. Conversely, the biodegradation of ethanol (23% increase) and hexanol (41% increase) was greater for the post-CSF tracer test. In addition, analysis of core samples collected from within the test cell indicates that the population density of aerobic jet-fuel degraders increased in the vicinity of the injection wells during the CSF. These results indicate that the cyclodextrin flush did not deleteriously affect the indigenous microbial community. This study illustrates that tracer tests can be used to evaluate the impact of remediation activities on in-situ biodegradation potential.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed1990

Clinical evaluation of amperometric enzyme electrodes in continuous-flow analysis for glucose in undiluted whole blood.

We have evaluated the carbon-paste enzyme/wall-jet electrode in continuous-flow analysis for glucose in undiluted whole blood. Responses of the electrode to protein-based and aqueous samples under wall-jet configuration are described. Imprecision in the flow-injection mode was less than 2% for glucose values in the usual analytical range (1-25 mmol/L). The dynamic range for glucose was from 0.03 to 45 mmol/L, with about 100% recovery of added substrate. The performance of the electrode (y) in flow-injection and steady-state modes was compared with a colorimetric method (x; Kodak Ektachem XR700), yielding linear-regression equations of y = 1.152x + 0.295 and y = 0.979x + 0.500, respectively. Among the anticoagulants, blood preservatives, and interfering substances investigated, only ascorbic acid gave a significant positive bias. The electrode exhibited good stability for analyses of undiluted whole-blood samples.

Autoanalysis↗
PubMed1994

Is proximal airway pressure a good reflection of peripheral airspace pressure in infants and children models under HFJV?

This experimental study was carried out to determine if an alveolar positive end-expiratory pressure (PEEP) could occur during high frequency jet ventilation (HFJV) in infants, and if tracheal pressure is a good estimation of alveolar pressure. We used physical models simulating a 1.5 kg premature (P), a 3 kg newborn (N) and a 6 kg child (C) with normal compliance and normal resistance. Moreover, in the N model, we used two different resistances and lung compliance heterogeneity was studied in the P model. Pressure was measured simultaneously in the tube simulating trachea (Paw) and in the bottle simulating the lung (Palv). HFJV was performed either via an endotracheal tube (ETT) or via a long catheter as in laryngoscopy. The ratio of injection time upon cycle duration (Ti/Ttot) was 20% or 30%, jet frequency was altered from 150 to 300 min-1 and the driving pressure was set as in clinical practice (0.5 and 0.6 bar). PEEP occurred mainly in N (1.1 to 3.2 cm H2O) and C models (0 to 3.5 cm H2O). It was inversely related to expiratory time (Te). The end-expiratory pressure drop between Palv and Paw (delta EEP) was higher in N and increased from 0.5 to 2 cm H2O with the shortening of Te and with airway resistances, i.e. the presence of ETT. In the heterogeneous model, PEEP and delta EEP were greater in the higher compliance alveolus. This study shows that the end-expiratory Palv is underestimated by end-expiratory Paw.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pressure↗
PubMed1990

Copper determination in urine by flow injection analysis with electrochemical detection at platinum disk microelectrodes of various radii.

The incorporation of platinum disk microelectrodes of various radii (2.5-50 microns) in a well-jet flow cell offers reduced limits of detection for the determination of copper in urine by flow injection analysis compared with standard methods based on a conventional sized glassy carbon disk macroelectrode (radius 1.5 mm), in a thin-layer cell. The radius of the platinum disk microelectrode was found to be critical with respect to both the limit of detection and flow rate dependence. An optimal radius value of 28 microns was found with detection limits increasing with both larger and smaller electrode radii. In contrast, as theoretically expected, a diminished flow rate dependence was observed the smaller the radii of the platinum disk microelectrodes. Sample cleanup and preparation is conveniently achieved by the use of Sep-Pak cartridges and formation of a copper dithiocarbamate complex. The metal complex is easily oxidized at platinum disk microelectrodes in acetonitrile, which was the solvent used in the flow injection method of analysis.

Copper↗
PubMed2002

Nociceptin/orphanin FQ modulates the cardiovascular, but not renal, responses to stress in spontaneously hypertensive rats.

1. The central administration of the endogenous opioid-like peptide nociceptin/orphanin FQ (N/OFQ) produces marked cardiovascular depressor and renal sympathoinhibitory responses in conscious animals. These findings are evidence that central N/OFQ may modulate the cardiovascular and renal responses to acute environmental stress. 2. The changes in cardiovascular and renal function produced by intracerebroventricular (i.c.v.) N/OFQ were measured in conscious spontaneously hypertensive rats (SHR) under basal conditions and during the acute environmental stimulus of air jet stress. 3. In SHR, central N/OFQ produced profound hypotensive, bradycardic, renal sympathoinhibitory (delayed) and water-diuretic effects by a pathway that does not involve activation of central alpha2-adrenoceptors or classical opioid receptors. 4. Intracerebroventricular injection of N/OFQ prevented the pressor response and blunted the tachycardia to air jet stress. A similar renal sympathoexcitatory and antinatriuretic response was observed in conscious SHR during air stress, before and after i.c.v. N/OFQ. 5. These findings are evidence that, in conscious SHR, i.c.v. N/OFQ selectively inhibited the neural responses to air jet stress by attenuating sympathetic outflow to the heart and, potentially, vasculature, but not to the kidneys. Central endogenous N/OFQ systems may be activated and contribute to regional changes in sympathetic outflow during acute stress.

Adrenergic Fibers↗
PubMed1987

[Results of a study of new preparations of inactivated whole-virion influenza vaccines for the protection of children in the USSR].

The safety, reactogenic properties and antigenic potency of inactivated whole-virion influenza vaccines produced in the USSR were studied on 1,117 schoolchildren in limited coded clinico-immunological observations. Inactivated chromatographic influenza vaccine obtained from strain A/Texas/1/77 (H3N2) and a variant of this vaccine, developed specially for children and obtained from strains A/Texas/1/77 and B/Leningrad/76, were used for immunization. Both preparations were introduced intradermally in a single injection in a volume of 0.1-0.2 ml by means of bi-3 jet injector. The content of hemagglutinin in this volume varied from 3.0 to 8.0 micrograms. Clinico-laboratory investigations demonstrated the safety of mono- and bivalent inactivated whole-virion influenza vaccine administered intradermally in a single injection to children of school age. The vaccines showed low reactogenicity and high antigenic potency in children aged 7-10 and 11-14 years, and the optimal doses of the preparations were selected for children of different age groups. The distinct prophylactic effectiveness of inactivated chemical chromatographic influenza vaccines in children aged 11-14 years was revealed 11 months after immunization, the index of immunological effectiveness being 1.7.

Adolescent↗
PubMed2000

High-pressure water jet injuries: a surgical emergency.

Injuries from high-pressure jet devices are surgical emergencies characterised by small entry wounds with extensive internal damage. Three factors are involved in these injuries. Physical injury can include local soft tissue disruption and vascular and nerve damage; chemical properties of the injectate can exacerbate compressive vascular injuries with increased oedema and inflammation; water-jet injuries can be contaminated by virulent organisms and foreign matter which can lead to unusual infections. Management is usually similar to that for injuries caused by high-velocity missiles, and involves aggressive debridement, irrigation and decompression followed by careful monitoring, and appropriate antibiotic therapy.

Adult↗
PubMed2001

High-energy neutrinos from photomeson processes in blazars.

An important radiation field for photomeson neutrino production in blazars is shown to be the radiation field external to the jet. Assuming that protons are accelerated with the same power as electrons and injected with a -2 number spectrum, we predict that km(2) neutrino telescopes will > or similar to 1 neutrinos per year from flat spectrum radio quasars such as 3C 279. The escaping high-energy neutron and photon beams transport inner jet energy far from the black-hole engine, and could power synchrotron x-ray jets and FR II hot spots and lobes.

Journal Article↗
PubMed1981

Intralesional corticosteroids.

Intralesional corticosteroids are commonly used in clinical dermatology. They are an adjunct to topicals and a possible substitution for systemic corticosteroids. Intralesional corticosteroids can be injected via a syringe and needle or with a Dermo-Jet. Although multiple preparations are available, the triamcinolones have more acceptable physical characteristics. Systemic absorption and consequent adverse effects are rarely a problem because of low dosage administered. Local adverse effects (the most prominent of which is atrophy) depend on the strength of the preparation, the quantity used, the area of the body, and the skin condition being treated.

Absorption↗
PubMed2006

Third-generation biosensor for lactose based on newly discovered cellobiose dehydrogenase.

The present paper describes the principle and characteristics of a biosensor for lactose based on a third-generation design involving cellobiose dehydrogenase. As resulted from a previous comparative study (submitted manuscript), the novelty of this lactose biosensor is based on highly efficient direct electron transfer between two newly discovered cellobiose dehydrogenases (CDH), from the white rot fungi Trametes villosa and Phanerochaete sordida, and a solid spectrographic graphite electrode. CDH was immobilized on the electrode surface (0.073 cm2) by simple physical adsorption, and the CDH-modified electrode was next inserted into a wall-jet amperometric cell connected on-line to a flow injection setup (0.5 mL x min(-1)). The P. sordida CDH-based lactose biosensor, proved to be the better one, has a detection limit for lactose of 1 microM, a sensitivity of 1100 microA x mM(-1) x cm(-2), a response time of 4 s (the time required to obtain the maximum peak current), and a linear range from 1 to 100 microM lactose (correlation coefficient 0.998). The simplicity of construction and analytical characteristics make this CDH-based lactose biosensor an excellent alternative to previous lactose biosensors reported in the literature or commercially available. The CDH-lactose sensor was used to quantify the content of lactose in pasteurized milk, buttermilk, and low-lactose milk, using the standard addition method. No effects of the samples matrixes were observed. The operational stability of the sensor was tested for 11 h by continuous injection of 100 microM lactose (290 injections). The final signal of the sensor was maintained at 98% of its initial signal, with a low standard deviation of 1.72 (RSD 2.41%).

Animals↗
PubMed1997

Cardiovascular response to stress: baroreflex resetting and hemodynamics.

Borderline hypertensive rats (BHR) were used to test the hypothesis that baroreflex resetting prevents a fall in blood pressure (BP) when cardiac output (CO) is reduced during air-jet stress. Eight-week-old BHR were instrumented with flow probes around the ascending aorta for measuring CO, femoral and jugular catheters were inserted for measurement of arterial pressure and infusion of drugs, and sinoaortic baroreceptors were either denervated (SAD) or left intact. Alternating bolus injections of phenylephrine and sodium nitroprusside were given at baseline and during air-jet stress to assess the baroreflex. Air-jet stress immediately shifted the midpoint of the baroreflex curve for heart rate (HR) to a higher BP levels. When metoprolol was administered during air-jet stress, HR was reduced and CO reverted to prestress levels, but the stress-induced pressor response was not changed. In SAD BHR, air-jet stress caused an elevation of BP that was not different from intact rats. Administration of metoprolol to SAD rats during air-jet stress resulted in a further elevation rather than a reduction in BP. We conclude that the sinoaortic cardiac baroreflex is reset during air-jet stress and that it integrates reflex changes in BP during stress. The arterial baroreflex is not, however, necessary for the initiation or maintenance of the pressor response during stress, nor does it prevent a fall in BP when CO is compromised during stress.

Animals↗
PubMed1997

Color Doppler ultrasound for evaluation of collagen implants after endoscopic injection treatment of refluxing ureters in children.

To determine whether color Doppler ultrasonography (CDUS) would add to the understanding of the bladder wall after endoscopic subureteral collagen injection (SCIN), 25 patients were studied with CDUS. The kidney length and echogenicity, the volume of the collagen, the mean length of the urinary jet, the longitudinal and transverse angles, and the distance between the origin of the jet and the midline of the bladder were measured 1 day, 1 month, and 3 months after SCIN and compared to the results of micturating cystourethrograms (MCUs) performed 3 months after SCIN. The collagen was hyperechogenic compared to the bladder wall at the time of injection, and was isoechogenic 1 and 3 months after SCIN. CDUS showed the relationship between the injected collagen and the position of the ureteral orifice. The measurements of jet length, angle, and distance of the ureteral orifice from the midline did not correlate with vesicoureteral reflux assessed by MCU. Although CDUS may demonstrate the location, the size of the injected collagen implant, and its relationship to the ureteral orifice, it is as yet unable to predict vesicoureteral reflux after SCIN.

Adolescent↗