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Biomedical subjects

C Wakefield

Publications and source records attributed to C Wakefield.

16 recordsLinked to original sources
PubMed2002

Anti-D (WinRho SD) treatment of children with chronic autoimmune thrombocytopenic purpura stimulates transient cytokine/chemokine production.

Intravenous anti-D is often used in the treatment of autoimmune thrombocytopenic purpura (AITP), but little is known about its mechanisms of action. To investigate anti-D's potential in vivo mechanism(s) of action, a small group (N = 7) of children with chronic AITP was studied. The children initially received either 25 or 50 microg/kg of WinRho-SD in a four-cycle cross-over trial, and peripheral blood samples from the first and third cycles were assessed for cytokine levels at pre-treatment, 3 hr, 1 day, and 8 days post-treatment. Results showed that platelet counts significantly increased in all the children by day 8 post-treatment. Analysis of serum by ELISA showed that there was a significant but transient rise in both pro- and anti-inflammatory cytokine/chemokine levels (e.g., IL1RA, IL6, GM-CSF, MCP-1 alpha, TNF-alpha and MCP-1) by 3 hr post-treatment in both cycles which returned to baseline levels by 8 days post-treatment. These results suggest that anti-D administration may initially activate the RES in the form of cytokine/chemokine secretion, which is subsequently followed by an increase in platelet counts. It is possible that the induced cytokine/chemokine storm may have an effect on several physiological processes such as those mediating either adverse effects or potentially RES phagocytic activity.

Chemokines↗
PubMed1992

The cardiovascular, endocrine and renal response of tetraplegic and paraplegic subjects to dietary sodium restriction.

1. The effects of change from a high to low sodium diet upon renal sodium and water excretion and hormone responses were studied in patients with dissociated sympathetic control (DS, tetraplegic) and controls with sympathetic control largely intact (IS, paraplegic). 2. Total and fractional urinary sodium excretion fell in response to sodium restriction in both groups, but the fall in fractional sodium excretion was greater in the DS group compared with the IS group (DS, 1.34 +/- 0.12 to 0.42 +/- 0.05%; IS, 0.96 +/- 0.08 to 0.52 +/- 0.06%). 3. Supine mean arterial pressure fell during the low salt period in the DS group (80.2 +/- 2.7 to 74.4 +/- 2.3 mmHg) but was unaffected by salt restriction in the IS group (101 +/- 2.3 to 98.8 +/- 2.7 mmHg). In the DS group, creatinine clearance remained constant throughout the low salt period (103.7 +/- 7.9 to 98.3 +/- 9.7 ml min-1), but fell during salt restriction in the IS group (101.4 +/- 8.5 to 83.2 +/- 5 ml min-1). 4. Plasma renin activity was lower during salt loading in DS subjects but increased more rapidly and to higher levels in response to salt restriction (DS, 1021 +/- 142 to 4439 +/- 355; IS, 1765 +/- 269 to 3683 +/- 465 pg angiotensin I ml-1 h-1). Plasma atrial natriuretic peptide concentration was higher in the DS group during salt loading and salt restriction (DS, 37.6 +/- 5.6 to 22 +/- 3.8; IS, 20.2 +/- 2.3 to 11 +/- 1.6 pg ml-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Scanning electron microscopic observations of normal and regenerating nerve roots in the cat.

The surface morphology of normal and regenerated nerve roots was studied using correlated scanning and transmission electron microscopic methods. Nerve roots of the cauda equina were either cut and rejoined or crossed from a segment above to a segment below. Good regeneration was observed in both experimental procedures. The regenerated nerve root sheath had alterations in surface structure created by extensive growth of collagen. Despite this collagen formation, regenerated axons crossed the anastomotic site with relative ease. Surface features of the regenerated axons were similar in appearance to those of the normal axon. Schwann cells were easily recognized, as were the collagen fibers of the endoneurium, although the endoneurium was more prominent and occupied more of the interaxonal space. Macrophages were identified as round structures with a laminated surface or as a honeycomb structure. Internal features of the regenerating axons were more difficult to identify, but mitochondria and a fibrous network were observed. These studies have demonstrated the application of scanning electron microscopic methods to visualize surface structures and cells in regenerated nerve roots.

Animals↗
PubMed1983

Reinnervation of the gastrocnemius muscle by the contralateral S1 nerve root.

Functional regeneration after transposition of a ventral nerve root was established in the adult cat. Reconstruction of the ventral root, using microsurgical methods, directed the right S1 ventral nerve root to innervate the left gastrocnemius muscle. Stimulus-induced unit responses were recorded from the left gastrocnemius muscle 5 to 8 months after the root cross, demonstrating the reestablishment of neuromuscular connections. The innervation of the left gastrocnemius muscle by neurons in the right ventral horn of the spinal cord was verified by injecting horseradish peroxidase into the muscle. Horseradish peroxidase reaction product was located in alpha and gamma motor neurons in the right S1 segment of the spinal cord. Computer-assisted determination of the soma area of the labeled neurons was compared with a normal S1 innervation of the gastrocnemius muscle. Analysis of the percentage of cells of a given soma area demonstrated an overall decrease in soma area in the operated animals. Because ventral root reconstruction can result in innervation of a foreign muscle, studies such as this may encourage repair or reconstruction of nerve roots to gain some functional recovery after spinal cord or nerve root injuries.

Animals↗
PubMed1983

Phaeochromocytoma in pregnancy. Caesarean section under epidural analgesia.

Two cases are reported in which Caesarean section was successfully performed under epidural analgesia in patients whose pregnancy was complicated by a phaeochromcytoma. Pre-operative phenoxybenzamine therapy together with careful peri-operative monitoring produced cardiovascular stability and led in both cases to the delivery of a healthy infant.

Adolescent↗
PubMed1980

The topographical organization and laminar origin of some cortico-amygdaloid connections.

Injections of horseradish peroxidase were made into the basolateral nuclei of the amygdaloid complex in cats. It was shown that the periamygdaloid cortex immediately below the rhinal sulcus and extending medially to the amygdaloid fissure projects to the lateral nucleus. The rest of the periamygdaloid cortex medial to the amygdaloid fissure and including the cortical nucleus of the amygdala projects primarily to the basomedial nucleus. These cortico-amygdaloid projections originate in the deeper one-third of the cortex. No projections from the neocortex could be demonstrated.

Afferent Pathways↗
PubMed1979

Observations of HRP labeling following injection through a chronically implanted cannula--a method to avoid diffusion of HRP into injured fibers.

One of the limitations of the horseradish peroxidase (HRP) tracer method is the diffusion of HRP into injured axons resulting in unintended labeling of neurons not terminating in the injection area. To overcome this limitation, an experiment was designed to inject the HRP through an implanted cannula after degeneration and healing had taken place. It was shown that implantation of a cannula into the internal capsule significantly decreased the number of labeled axons in the injection site, thus limiting the unintended labeling of neurons from that injection. When injections followed implantation of the cannula by 24 h or more, fibers damaged by the cannula had healed or degenerated sufficiently that intraaxonal diffusion of HRP into those injured fibers did not occur. A significant difference between control (without the cannula) and experimental (with the cannula) injections was observed. Extensive axonal and neuronal labeling following the control injections was seen at the injection site and caudate nucleus, and in the thalamus and parietal cortex, respectively. Experimental injections resulted in sparse axonal and neuronal labeling evident mostly with the larger injections of HRP.

Amygdala↗