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Biomedical subjects

J A Maxwell

Publications and source records attributed to J A Maxwell.

46 records · Page 3Linked to original sources
PubMed1968

The dissipation and dispersion of small waves in arteries and veins with viscoelastic wall properties.

Theoretical and experimental evidence suggests that the dissipation of high frequency pressure waves in blood vessels is caused primarily by the viscoelastic behavior of the vessel wall. In this theoretical analysis the vessels are considered as fluid-filled circular cylindrical shells whose walls have isotropic and homogeneous viscoelastic properties and are subjected to an initial axial stretch and a transmural pressure. If the wall material is incompressible and behaves as a Voigt solid in shear, the results predict a decrease in wave amplitude per wavelength which is essentially independent of frequency over a wide range. This finding is in qualitative agreement with recent experiments on anesthetized dogs. A parametric study also shows a great sensitivity of the dissipation to changes in transmural pressure and axial stretch. Axisymmetric waves are only mildly dispersive, while all nonaxisymmetric waves are highly dispersive and exhibit much stronger damping per wavelength at low frequencies than do axisymmetric waves.

Arteries↗
PubMedDate not supplied

Effect of dopamine receptor antagonists on cocaine subjective effects: a naturalistic case study.

Schizophrenic patients on neuroleptic medications abuse cocaine and report cocaine-induced euphoria. This study was undertaken to provide better clinical characterization of these phenomena by administering the POMS and a custom-designed questionnaire. A group of heavy cocaine users who were not mentally ill served as the control group. The results clearly suggest that schizophrenic patients report cocaine-induced euphoria and post-use craving despite being treated with therapeutic doses of haloperidol or fluphenazine. The responses of the control group were similar to that of the schizophrenic group except that the latter subjects reported a greater degree of anxiety. These results suggest that blockade of D2 receptors is not sufficient to block cocaine-induced subjective effects in humans.

Adult↗
PubMedDate not supplied

Ganglia of the nerve. Presentation of two unusual cases, a review of the literature, and a discussion of pathogenesis.

Two cases of intraneural ganglia are reported: the first reported involvement of the sciatic nerve and the first reported involvement of the tibial nerve in the tarsal tunnel. Both were successfully treated by excision with sparing the neural elements leading to neurological recovery. A review of the literature fails to reveal any consensus that lesions arise from normal synovial cavities. Incision, evacuation, and complete excision under magnification sparing neural elements gives satisfactory results. Excision of the nerve is not indicated. Pathologic examination suggests that the lesion arises by multicentric metaplasia of connective tissue elements of the nerve rather than by invasion.

Adult↗