Comparison of three DCV techniques with "benchmark" performance of the same nerve.
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Action Potentials↗
Biomedical subjects
A T Barker
Publications and source records attributed to A T Barker.
Clinical evaluation of Dinamap 845 automated blood pressure recorder.
The Dinamap 845 blood pressure recorder has been evaluated over a wide range of blood pressure by comparison with the Hawksley random zero sphygmomanometer in 32 subjects, six of whom had a cardiac arrhythmia. Group mean radings for systolic and phase 5 diastolic pressure were almost identical but Dinamap diastolic values were on average significantly lower (mean difference 3.4 mmHg) than phase 4 diastolic readings obtained with the Hawksley machine. Correlations between readings with the two instruments were high but the slopes and intercepts of the regression for systolic but not diastolic pressure were significantly different from unity and zero, respectively. The Dinamap is easy to use, portable, and capable of rejecting some motion artefact. Its major disadvantage is that the systolic blood pressure measurement is limited to a maximum of 210 mmHg, a point not made clear in the manufacturer's literature. Nevertheless, the Dinamap 845 is acceptable for blood pressure determinations in subjects who are normotensive or who have mild hypertension.
Blood Pressure↗
Modeling of an active nerve fiber in finite volume conductor and its application to the calculation of surface action potentials.
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Action Potentials↗
Determination of the distribution of conduction velocities in human nerve trunks.
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Action Potentials↗
Recombinant human CD40 ligand inhibits simian immunodeficiency virus replication: a role for interleukin- 16.
CD40 ligand (CD40L), expressed on activated T cells, binds its receptor, CD40, on dendritic cells, B cells, and monocytes/ macrophages. Human immunodeficiency virus (HIV)-infected individuals exhibit normal B-cell CD40 expression but diminished expression of CD40L on CD4 + T cells. Thus, we studied recombinant human CD40L (huCD40L) in an in vitro rhesus macaque model of acquired immunodeficiency syndrome (AIDS). huCD40L induced peripheral blood mononuclear cell (PBMC) proliferation independent of mitogenic cytokines and led to a 70% reduction in p27 production by simian immunodeficiency virus (SIV) mac239 infected PBMCs (P < 0.05). Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis showed reduced expression of SIV gag and increased expression of interleukin (IL)-16 mRNA. Supernatants from huCD40L-stimulated PBMC and control cultures contained similar amounts of IL-16, suggesting an intracellular antiviral effect by IL-16. Phytohemagglutinin (PHA)-stimulated PBMCs similarly cultured with huCD40L showed only slight increases in chemokine production (P > 0.05). These results suggest that huCD40L inhibits replication (antigen and mRNA production) of SIVmac239. This response involves huCD40L induction of IL16 mRNA expression and appears to be independent of beta-chemokines.
Animals↗
Measurement of the activating function of magnetic stimulation using combined electrical and magnetic stimuli.
The technique of combined magnetic and electrical stimulation of a peripheral nerve was used to determine the effectiveness of the combined stimulus and its dependence on the relative positioning of electrodes and stimulator coil along the axis of the nerve. The results were used to determine the magnetic stimulation-activating function of a long, straight nerve in the arm, and are shown to be consistent with published theoretical models constructed under conditions of simplified tissue geometry. With appropriate positioning of the two stimulators and similar tissue current waveforms, both enhancement and inhibition of an electrical stimulus were demonstrated and the maximum amplitude of the combined stimulus approached the arithmetic sum of that produced by each stimulator individually.
Arm↗