PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Injections, Jet”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 505 records · Page 28Linked to original sources
PubMed1986

Responses of morphologically identified cortical neurons to intracellularly injected cyclic AMP.

Intracellular injections of cyclic adenosine monophosphate (cAMP) and horseradish peroxidase (HRP) were made in neurons of the motor cortex of awake cats. Eighty-six percent of injected cells responded to cAMP and HRP with a rapid decrease in input resistance. The decreases in input resistance occurred immediately after injection and began to return toward baseline 2 to 3 min later. The decreases were significantly greater than the small decreases in input resistance normally seen in uninjected cells held for 2 min or more after penetration and exceeded comparably small decreases in input resistance seen after control injections of 5'-AMP plus HRP. Pyramidal cells of layer V were identified as responding to cAMP with a decreased input resistance. A spiny stellate cell of layer III and a pyramidal cell of layer VI were also identified that showed similar responses. Increased rates of discharge were also observed after penetration with electrodes containing cAMP, but significant changes in input resistance were not found in association with the increased rates of discharge. After pressure injection of cAMP, the rates of discharge decreased toward more normative values. Our findings indicate that cAMP has an effect on cortical neurons similar to that found in some types of invertebrate (molluscan) neurons and dissimilar to the effect of cyclic guanosine monophosphate.

Animals↗
PubMed1983

Rapid and simple determination of delivery after iontophoretic and pressure injections of radiolabeled tracer substances.

A fluorographic method is described using X-ray film analysis for the determination of delivery of radiolabeled tracer substances both in Agar plates and in tissue sections. This method is most useful in neuroanatomical autoradiographic studies for providing rapid identification of delivery, placement, and extent of an injection site after iontophoresis or pressure injections of radiolabeled axonal tracer substances.

Animals↗
PubMed1984

Pressure injections of fluid in the nanoliter range via micropipettes.

The relationship between pressure, ejection duration and volume ejected was experimentally determined in vitro for micropipettes with different external tip diameters. The relationship between ejection duration and ejected volume is linear in the steady state (i.e. with ejection durations of 1 s or longer) and at sufficiently high pressures (above about 100 kPa) and for pipettes with a sufficiently high hydrodynamic conductance (larger than 1 pl s-1 kPa-1 at 230 kPa). In this range, flows were found with low Reynolds numbers (smaller than 10), which is consistent with laminar flows. For all but the largest micropipettes, the relationship between pressure and ejected volume is alinear: the pipettes' apparent hydrodynamic conductances increase with increasing pressure. Micropipettes with apparent hydrodynamic conductances between 0.04 and 1400 pl s-1 kPa-1 (at 230 kPa) were tested. Duration-pressure combinations could be defined where the duration-volume relationship was either linear or monotonic. such duration-pressure combinations were different for pipettes with different apparent hydrodynamic conductances. A quick method is described to measure the pipette's apparent hydrodynamic conductance at the pressure used, corrected for the fluid's viscosity. Measurement of this conductance permits predictable injections of known volumes of fluid in the range of 100 pl to 1 microliter with a precision of 10-20%.

Injections, Jet↗
PubMed1987

Characterization of the techniques of pressure ejection and microiontophoresis using in vivo electrochemistry.

Catecholamine levels in frontal cortex were determined in vivo by electrochemical detection after the local application of dopamine (DA) from multibarrel micropipettes by pressure ejection or microiontophoresis. Tissue DA levels were linearly related to microapplication doses with either technique and reached steady state with longer application times. Furthermore, the plateau DA tissue concentrations were clearly related to ejection pressure or iontophoretic current. Using either microapplication technique, the tissue DA levels decreased as distance between the recording electrode and the tip of the drug pipette increased. However, pressure ejected and iontophoretically applied drug differed in their concentration versus time dynamics. Thus, although similar tissue concentrations of drug can be generated by the two techniques, the time dynamics of the drug effects may not be comparable. The quantitative use of these drug application techniques requires a minimal amount of variance in release between pipettes in order to effectively measure small sensitivity differences. Although the 10-fold variance with microiontophoresis does not appear resolvable at present, improved pipette construction techniques permit the variability in dosage to be limited to a maximum of 3-fold with pressure ejection. In addition, the present data also suggest that this variance can be further minimized by holding either ejection duration or ejection pressure constant when establishing dose-response relationships.

Animals↗
PubMed1990

HRP-filling of neurons and axonal arbors in fixed brain slabs.

Visually-guided introduction of HRP into perfusion-fixed hamster brain slabs was carried out by three procedures: pressure or extracellular iontophoretic injections, introduction of a small HRP-crystal on the closed tip of a micropipette, and by dropping a very small drop of HRP solution on the ventricular surface. The prefixation was made with a solution of 1% paraformaldehyde and 1% glutaraldehyde in 0.1 M phosphate buffer in time periods ranging from 4 to 26 days. The introduction of HRP-crystals into brain slabs did not produce HRP-filling of cells and processes, but only a granular background of HRP diffusion. Injections into adjacent brain slabs of an HRP-containing solution did produce, in every case, some degree of labelling of neuronal somata, dendrites, individual axons, and fibre bundles. Several cells showed dense HRP-filling of the soma and processes, including dendritic spines and axonal varicosities. Dense HRP-filled axonal terminal arbors were seen in the dorsal lateral geniculate nucleus (dLGN) and superior colliculus (SC) after iontophoretic injections in the optic tract. The good ultrastructural preservation achieved by perfusion of the fixative solution was not affected by the subsequent injection procedures, and the pre- and post-synaptic specializations of HRP-filled axons were recognizable. This approach may prove to be useful in correlative light and electron microscope studies of the synaptic relationships between HRP-filled neurons and axons.

Animals↗
PubMed1993

Simultaneous local pressure microejection of excitatory amino acids and field potential recording with a single micropipette in the hippocampal slice.

The ability to use the same micropipette for simultaneous pressure microejection and field potential recording ('spot pressure electrode') is described. This approach allows the use of a single electrode to record both field responses to pressure microejection of drugs (fPR) and synaptically evoked field excitatory postsynaptic potentials (fEPSP). To demonstrate this, the glutamate receptor agonists alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA, 100-300 microM) and N-methyl-D-aspartate (NMDA, 1 mM) were used. Both AMPA- and NMDA-evoked fPRs exhibited properties of postsynaptic responses. Thus, they were not significantly altered by tetrodotoxin (TTX, 0.5-1 microM), but were completely and reversibly blocked by an antagonist of AMPA/kainate receptors, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 20 microM) and D-2-amino-5-phosphonopentanoic acid (AP5, 20 microM), respectively. The responses to micropressure-ejected AMPA were more stable and probably restricted to a smaller locus than responses to iontophoretic AMPA ejection. Additionally, the AMPA and NMDA contained in the pipette (up to 500 microM) did not influence the fEPSP recorded with this pipette. Our results suggest that this method might be a useful experimental tool for studying the local effects of excitatory amino acids and other compounds.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1983

Actions of GABA in developing rabbit hippocampus: an in vitro study.

The development of neuronal responses to gamma-aminobutyric acid (GABA) was examined using intracellular recording techniques in area CA1 of rabbit hippocampal slices maintained in vitro. Microapplication of GABA (via pressure ejection) in stratum pyramidale in slices from mature rabbits (age 1 month) evoked a hyperpolarization of CA1 pyramidal neurons. The reversal potential (Erev) for this response was approximately -70 mV. In contrast, local application of GABA into stratum pyramidale in slices from immature rabbits (age 7-10 days) produced a depolarizing response with an Erev of approximately -54 mV. The relationship between these findings and the development of inhibitory synaptic activity in rabbit hippocampus is discussed.

Action Potentials↗
PubMed1989

Superiority of perfusion over bolus administration in cancer chemotherapy: proposition of a compartmental model.

Recent studies indicate that, for cancer chemotherapy, prolongation of drug injection time yields lower toxicity and better efficacy. We propose a compartmental pharmacological model to explain these observations. The model has been simulated on an analog computer. The curves obtained give a credible explanation for the clinical data. The superiority of perfusion over bolus injection may be attributed to plasma peak suppression.

Antineoplastic Agents↗
PubMed1991

Anterograde neuroanatomical tract tracing with central nervous system injections of immunoglobulin G: a light and electron microscopic evaluation.

Normal rabbit serum (NRS) was pressure injected into the forebrain of rats to be tested as an anterograde neuroanatomical tracing substance. Undiluted NRS was stereotaxically injected into the bed nucleus of the stria terminalis (BST) with a 1-microliter Hamilton syringe. Postinjection survival times ranged from 24 h to 14 days. An immunohistochemical method utilizing goat anti-rabbit IgG antibody was used to detect the rabbit IgG within vibratome sections. Visualization of the final reaction product (diaminobenzidine, DAB) was enhanced by a silver/gold postintensification (SGI) method. Rabbit IgG-containing neural structures were examined at both light and electron microscopic (EM) levels. At the injection site neuronal soma, dendrites and axons were filled homogeneously with the SGI-DAB at 24 h, 48 h, 7 days and 14 days indicating local neuronal uptake, storage and transport of rabbit IgG. In the hypothalamus many anterogradely filled axons were present and displayed short collateral branches and terminals. EM examination revealed synaptic terminals containing IgG, without signs of transsynaptic transport after 14 days. Signs of retrograde transport of IgG were never observed. A propensity of neurons to take up, sequester and anterogradely transport immunoglobulin G is indicated.

Animals↗
PubMed1989

High-pressure water injection injury to the hand.

An 84-year-old man presented with a high-pressure injection injury of the left thumb. The hand-held water gun involved generates less pressure than the grease and paint sprayers usually involved in these injuries. The patient was managed conservatively in the hospital with elevation, observation, and dressing changes. Surgical debridement was not required. This case points out a previously unrecognized hazard of these devices, particularly to older individuals with atrophic skin.

Aged↗
PubMed2005

Induction of immune responses and partial protection in mice after skin immunization with rotavirus VP6 protein and the adjuvant LT(R192G).

Oral or intranasal administration of mice with rotavirus VP6/LT(R192G) vaccine induces between 95 and 99% protection against fecal shedding of rotavirus after challenge. However, mucosal administration of LT(R192G) is controversial. Subcutaneous, intradermal or Biojector injection induced high titers of serum VP6-specific IgG, eliciting only partial to no protection (73, 0 and 26%, respectively), while transcutaneous delivery using gauze pad induced both poor immune responses and no protection (13%). A mixture of VP6-derived synthetic peptides induced >97, 48 and 33% protection after intranasal, gauze pad or Biojector administration, respectively. For needle-free delivery methods to be viable, improvements to these methods must be made to enhance the efficacy of the VP6 vaccine.

Adjuvants, Immunologic↗
PubMed2005

Clinical safety and efficacy of a powdered Hepatitis B nucleic acid vaccine delivered to the epidermis by a commercial prototype device.

This clinical delivery system bridging study evaluated the performance of a single-use disposable, commercial prototype device (designated ND 5.5) for particle-mediated epidermal delivery (PMED) of a nucleic acid vaccine against Hepatitis B virus (HBV). Healthy adults, previously immunized with licensed HBV vaccine, received a single boost vaccination of HBV nucleic acid vaccine administered by ND 5.5 or XR-1, the clinical research device used in previous clinical trials. Similar increases in anti-HBV surface antigen serum antibody titers and cell-mediated immune responses were produced by ND 5.5 and XR-1 when delivering comparable effective doses of the vaccine. The overall intensity of the immune response was lower in those subjects vaccinated with two, rather than 4 administrations of vaccine delivered by ND 5.5. Skin reactions at sites of vaccine administration were equivalent with both devices. This is the first clinical demonstration of the safe and effective PMED of a nucleic acid vaccine with the ND 5.5 device.

Adolescent↗
PubMed2005

Comparative evaluation of three different intramuscular delivery methods for DNA immunization in a nonhuman primate animal model.

Although plasmid DNA vaccines induce potent cell-mediated immune responses and prime for antibody responses in experimental laboratory animals, their immunogenicity in humans has been less remarkable. A number of strategies have been proposed to improve the immunogenicity of these vaccines, including using novel means of vaccine delivery. In the present study, the immunogenicity of three different methods of intramuscular plasmid DNA administration was compared in cynomolgus monkeys: needle and syringe, Biojector 2000, and Mini-Ject. The elicited cellular and humoral immune responses were comparable in monkeys immunized using these different delivery techniques, suggesting that the needle-free approaches to vaccine administration do not significantly improve the immunogenicity of the plasmid DNA vaccine used in the study.

Animals↗
PubMed2002

Local anesthesia: advances in agents and techniques.

The improvements in agents and techniques for local anesthesia are possibly the most important advances in dental science to have occurred in the past 100 years. The agents currently available in dentistry have most of the characteristics of an ideal local anesthetic. Today's anesthetics can be administered with minimal irritation and little concern for stimulating allergic reactions. A variety of agents are available that provide rapid onset of surgical anesthesia with adequate duration. This article provides a brief review of the local anesthetic agents, formulations, and techniques used in dentistry with special emphasis on newly introduced agents and procedures.

Anesthesia, Dental↗