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Biomedical subjects

E Hoffer

Publications and source records attributed to E Hoffer.

At least 73 records · Page 4Linked to original sources
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Evaluation of silicone as an endovascular stent membrane: in vivo canine studies.

PURPOSE: Comparative evaluation of the biological effects of a silicone-covered stent versus a bare-metal stent, in an animal model. METHODS: Twelve stent implants were placed in the iliac arteries of six adult dogs. Each animal received one 8-mm x 20-mm silicone-covered stent (Permalume; Boston Scientific Vascular, Watertown, MA, USA), in the right iliac artery and one Wallstent (Boston Scientific Vascular) of the same diameter and length in the left iliac artery, during systemic anticoagulation. Angiography was performed before and after implantations. Animals were then allowed to recover and no platelet suppression was given during a 6-week interval, after which the animals were euthanized. The stented arteries were isolated and pressure-fixed in situ with 10% buffered formalin at a pressure of approximately 100 mmHg for a period of 1 hr. Two of 12 stented specimens were opened lengthwise and the luminal surfaces were photographed. Ten of 12 stented arterial segments were encased in methacrylate, then stained with hematoxylin and eosin. Neointimal thickness was quantified on histologic cross-section, for both bare and covered stents. The mean neointimal thicknesses were compared for significant difference using a student t-test. RESULTS: All implants were widely patent at 6-week follow-up angiography. Histologic analysis showed bare metal stents covered by a thin uniform lining of neointima composed of smooth muscle cells in a hyaline matrix (mean thickness of 189 +/- 47 microm). Silicone covered stents were devoid of neointima. There was no chronic thrombus or mature endothelium noted anywhere upon the internal silicone surfaces of any of the specimens. There was no foreign body reaction to the silicone cover. CONCLUSION: Short-term implantation of a silicone-lined Wallstent in canine iliac arteries is well tolerated. Silicone appears to be inert at 6 weeks in this experimental application.

Animals↗
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CT-guided transfemoral portocaval shunt creation.

A patient with superior vena cava (SVC) occlusion presented with severe ascites and urgent transjugular intrahepatic portosystemic shunt (TIPS) was requested. The patient had a chronically occluded SVC. An alternative to classic TIPS was employed using CT guidance to traverse the left portal vein to the inferior vena cava with a small gauge needle. Fluoroscopic guidance was then used to snare a wire placed through the needle and then work from the femoral vein to create a portocaval shunt that passed through the caudate lobe. This procedure was a technical success and improved the patient's ascites.

Ascites↗
PubMedDate not supplied

Therapeutic monitoring of busulfan in pediatric bone marrow transplantation.

The aim of this study was to describe busulfan disposition in a pediatric population who underwent bone marrow transplantation (BMT). Busulfan administered dose was 1 mg/kg every 6 h for 4 days. Plasma determinations were performed after the first dosing at 0, 15, 30, 60, 90, 120, 180, 240, 300, and 360 min. A noncompartment analysis model for extravascular absorption was used for the pharmacokinetic analysis. To obtain the area under the concentration-time curve (AUC) within the "therapeutic window" of 1,000-1,200 microM x minutes a busulfan dose adjustment Was performed at the fourth dose. Forty-five busulfan pharmacokinetic analyses were performed in 34 children. Eleven children had their dose adjusted [1.19 +/- 0.14) mg/kg] at the fourth dose and the AUC was monitored at the fifth one. The mean AUC +/- SD after the fifth dose (998.1 +/- 189.2 microM x min) was different (p = .006)from that after the first dose (1 mg/kg) (687.63 +/- 166.43 microM x min). Six children had their first AUC into the "therapeutic window," 17 children had their dose adjusted [1.2 (+/- 0.22) mg/kg], but the "adjusted" AUC was not available. These data suggest that it may be reasonable to recommend a busulfan dose of 1.2 mg/kg to achieve the accepted therapeutic target in children undergoing BMT.

Animals↗
PubMedDate not supplied

Modification of neutrophil function by plasma of rheumatoid arthritis patients treated with infliximab.

OBJECTIVE: To examine whether the release of superoxide anions from neutrophils of healthy donors was affected when incubated with plasma from infliximab-treated rheumatoid arthritis (RA) patients. METHODS: Fifteen consecutive seropositive RA patients were treated with 3mg/kg infliximab on weeks 0, 2, 6, and 14. Disease activity was assessed by DAS28 score and by IL-6 level. Neutrophils from healthy donors were incubated with plasma drawn before each infliximab treatment. PMA-stimulated superoxide release was measured by the ferricytochrome C reduction method. RESULTS: 53% of the patients had a favorable clinical response. IL-6 levels showed a significant decline at week two, with a gradual increase thereafter. Treatment with infliximab did not change the superoxide production. However, when the group was divided retrospectively to responders (DeltaDAS28 > -1.2) and non-responders (DeltaDAS28 < -1.2), two different patterns were seen, although the pre-treatment levels were similar: Among the responders IL-6 remained low at its 2 weeks level till week 14, while in the non responders IL-6 increased 3 times (P < 0.03) from week 2 to 14. The responders showed mild, but continuous, reduction of superoxide release, while in the non-responders it increased significantly from week 2 on. CONCLUSION: The reduction in IL-6 in RA sera following anti-TNFalpha therapy has little influence on the capacity of these sera to stimulate healthy neutrophils to produce superoxide, suggesting the existence of non-TNFalpha non-IL-6 dependent neutrophil-stimulating mediators in RA sera. The increasing level of IL-6 among the non-responders after initial dramatic decline might represent an escape phenomenon, possibly caused by alternative mediator(s). Clinically, this IL-6 "escape" might be used as a tool for early identification of responders from non-responders.

Aged↗
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Removal of excess inorganic phosphate by haemoperfusion with composite beads.

New composite beads, made by encapsulating hydrous zirconium oxide powder in agarose, are evaluated in vitro and in vivo for the removal of inorganic phosphate from the blood. Phosphate adsorption is rather good and calcium removal can be controlled. Thus, a 250 to 300 ml column is capable of reducing phosphate plasma level by some 5 mg per cent, thus making it attractive for the treatment of acute renal failure. Biocompatibility tests showed that supplementing the standard heparinization procedure by adding some citrate, as ACD, to the extracorporeal circuit greatly improves platelet and leucocyte count. No adverse haemodynamic effects were noted in repeated haemoperfusions of five dogs.

Acute Kidney Injury↗