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Biomedical subjects

P F Turner

Publications and source records attributed to P F Turner.

16 recordsLinked to original sources
PubMed1994

Interleukin-6 and tumor necrosis factor in the pathogenesis of adverse reactions after treatment of lymphatic filariasis and onchocerciasis.

Adverse reactions following treatment of onchocerciasis and bancroftian filariasis are common and frequently severe. They are generally caused not by direct drug toxicity but by host inflammatory responses to dying microfilariae. To define the responsible mechanism, serial blood levels of interleukin-6 (IL-6) and tumor necrosis factor (TNF) were studied in 15 microfilaria-positive patients (10 with bancroftian filariasis, 5 with onchocerciasis) and 4 microfilaria-negative persons after diethylcarbamazine treatment. Elevations in IL-6 correlated with the occurrence and severity of clinical symptoms after treatment; for the onchocerciasis patients IL-6 levels directly reflected pretreatment intensity of infection. Serum TNF levels also rose but did not correlate directly with infection intensity or reaction severity. Microfilaria-negative controls remained asymptomatic with no significant rise in either cytokine. These findings suggest an etiologic role for systemically elevated cytokines in the inflammatory reactions developing after treatment of filarial infections in humans.

Adult↗
PubMed1993

A study of the CD4: CD8 ratio in peripheral T lymphocytes of rural Papua New Guineans: a reduced ratio assessed with regard to infectious agents.

The CD4:CD8 ratio in peripheral T lymphocytes was determined in 123 Papua New Guineans aged over 5 years from Rumginae, a rural area of the Western Province. 18 people had a ratio less than 1.0. No antibody response to human immunodeficiency virus 1 (HIV 1) was found within the group. Hepatitis B surface antigen was more commonly associated with a CD4:CD8 ratio less than 1.0 than were microfilaraemia or a positive Mantoux test. Hepatitis B infection may be one of the causes of the CD4:CD8 ratio reduction within the community. Irrespective of the cause, other studies in Papua New Guinea have shown that a CD4:CD8 ratio less than 1.0 may result more from an increase in the CD8 cell count than a reduction in the CD4 cell count.

Adolescent↗
PubMed1988

Future trends in heating technology of deep-seated tumors.

Hyperthermia techniques and equipment have developed into a level of sophistication requiring special training and operator skills. Recent advances electromagnetic and ultrasound heating techniques are multi-applicator arrays, both external and invasive. These arrays are most effective when individual channel power control can be utilized to improve the heating pattern control during treatment. A preview of future capabilities shows that more selective tumor heating is possible with the advanced equipment. The role of computer pretreatment planning is a valuable aid in operator training as well as optimization of parameters. The current development of regional heating is in the deep focal heating by external focused arrays. The SIGMA 60 cylindrical dipole array deep steerable focal zone is described and test data presented showing the selective focusing obtained. A small invasive targeting E-field sensor is used to optimize phase and amplitude of the array to improve the selective heating in the target zone. These patented techniques and devices are expected to reduce systemic toxicity and increase tumor temperatures with lower power input. Future equipment development is predicted to include many types of hyperthermia devices and techniques. This trend suggests that systems must be designed to simplify the operator's tasks and improve the heating pattern controls. The computer power and control will become much more important in these future systems.

Electromagnetic Phenomena↗
PubMed1984

Taxol-induced bundling of brain-derived microtubules.

Taxol has two obvious effects in cells. It stabilizes microtubules and it induces microtubule bundling. We have duplicated the microtubule-bundling effect of taxol in vitro and report preliminary characterization of this bundling using electron microscopy, sedimentation, and electrophoretic analyses. Taxol-bundled microtubules from rat brain crude extracts were seen as massive bundles by electron microscopy. Bundled microtubules sedimented through sucrose five times faster than control microtubules. Electrophoretic analysis of control and taxol-bundled microtubules pelleted through sucrose revealed no striking differences between the two samples except for a protein doublet of approximately 100,000 daltons. Taxol-induced microtubule bundling was not produced by using pure tubulin or recycled microtubule protein; this suggested that taxol-induced microtubule bundling was mediated by a factor present in rat brain crude extracts. Taxol cross-linked rat brain crude extract microtubules were entirely labile to ATP in the millimolar range. This ATP-dependent relaxation was also demonstrated in a more purified system, using taxol-bundled microtubules pelleted through sucrose and gently resuspended. Although the bundling factor did not recycle with microtubule protein, it was apparently retained on isolated taxol-stabilized microtubules. The bundling factor was salt extracted from taxol-stabilized microtubules and its retained activity was demonstrated in an add-back experiment with assembled phosphocellulose-purified tubulin.

Adenosine Triphosphate↗
PubMed1982

Two-dimensional technique to calculate the EM power deposition pattern in the human body.

A numerical procedure to calculate the electromagnetic (EM) power deposition in two-dimensional models of cross sections in the human body is described. The procedure involves obtaining X-ray images of cross sections of specific areas with computer axial tomographic scans and then solving the EM boundary value problem by using the method of moments. The formulation thus takes into account not only the spatial distribution of the different tissue types, but also the radiation characteristics of the typical EM source. Numerical results are given to illustrate the accuracy of the developed procedure. Special emphasis is placed on characterizing and analyzing the EM power deposition patterns obtained using the annular phased array system recently developed by BSD Medical Corporation for hyperthermia treatments.

Computers↗