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Biomedical subjects

N Jensen

Publications and source records attributed to N Jensen.

At least 37 records · Page 2Linked to original sources
PubMed1994

Endothelial cell seeded dacron aortobifurcated grafts: platelet deposition and long-term follow-up.

OBJECTIVE: The prospect of seeding endothelial cells to a prosthetic graft has been successful in the experimental setting, but less convincing in clinical studies in humans. This study was performed with the objective of evaluating endothelial cell seeding of aorto-bi-iliofemoral reconstructions with cells harvested at the same procedure. EXPERIMENTAL DESIGN: Randomized study with one graft limb seeded and with at least 5 year follow-up. SETTING: University Hospital. PATIENTS: 15 patients undergoing aorto-bi-ilio-femoral reconstruction. INTERVENTIONS: One graft limb (randomly determined) was seeded with autologous endothelial cells (median 5.2 x 10(5)) enzymatically (Dispase II) harvested from the saphenous vein (length 8-15 cm, diameter 4-8 mm). The other graft limb served as a control. MEASURES: Two months after surgery platelets were labelled with 111In and platelet activity registered over the graft. Long-term outcome were followed (median 5 years and 10 months). RESULTS: No difference in platelet activity was noted between the seeded and non-seeded graft limb. Different techniques of calculating graft wall activity showed large interindividual variations in the results. Long-term outcome showed that three patients died, two from myocardial infarction on postoperative day three and 60, and one patient died four years after surgery from a lung cancer. Grafts functioned well. In one non-seeded graft limb the patient had severe microembolisation postoperatively that required amputation 10 days after surgery. Of seeded graft limbs one occluded 42 months after surgery, intimal hyperplasia at the distal anastomosis was seen and in one patient progress of arteriosclerosis required additional surgery 12 months after initial operation with profundaplasty (partly due to intimal hyperplasia) and later two additional femoro-distal reconstructions were needed. CONCLUSION: In summary with our single-staged technique for seeding of endothelial cells to a graft limb in a high flow situation no effect on platelet activity at two months was found and long-term outcome was not obviously influenced.

Aged↗
PubMed1992

Prostacyclin is produced from endothelial cell-seeded grafts: an experimental study in sheep.

Endothelial cell seeding might be of value in reducing the thrombogenicity of small-diameter vascular grafts. We investigated the capacity of endothelial cell-seeded grafts to produce prostacyclin and compared this with that of the unseeded graft as well as the native artery. Twelve sheep were operated on with carotid interposition of externally supported knitted dacron grafts. On one side of the neck the graft was seeded with endothelial cells, enzymatically harvested from the left jugular vein. After 3 weeks, three out of 12 seeded grafts, and one out of 12 unseeded grafts were occluded (N.S.). After excision, the grafts were mounted and perfused ex vivo for five 15-min periods. During the last period, arachidonic acid (4 micrograms/ml) was added to the perfusate. The resected carotid artery was used as a control. Prostacyclin was determined as the stable degradation product 6-keto-PGF1 alpha using radio-immunoassay, and expressed as pg mm-2 luminal surface. The native artery had a significantly higher release of prostacyclin than the seeded graft, which in turn had a significantly higher release than the unseeded graft. Histological examination showed weakly positive staining for factor VIII-related antigen on the luminal surface of seeded grafts. Scanning electron microscopy showed endothelial cells with typical endothelial tufts and was evaluated blindly from 10 areas of each graft. The extent of endothelial cell coverage was evaluated and scored from 0 to 2.5. The median score for the unseeded grafts was 0.3 and for the seeded grafts 1.5 (p = 0.008). Prostacyclin production was higher in seeded than unseeded grafts, but did not influence patency in this model.

Animals↗
PubMed1992

Collagen and gelatin-impregnated vascular grafts--is their thrombogenicity enhanced? An experimental study.

The early thrombogenicity of dacron vascular grafts with and without impregnation with collagen (n = 7) or gelatin (n = 7) was evaluated in a sheep carotid artery interposition model. Autologous platelets were labelled with 32P and reinjected. Flow was reduced to 25 ml/min to mimic a situation with poor run-off and the graft thrombogenicity was studied for 4 hours. The results showed no difference as regards patency, thrombus-free surface, or uptake of 32P-labelled platelets between collagen- or gelatin-impregnated grafts and their parent dacron grafts. Thus, no difference in early graft thrombogenicity could be documented.

Animals↗
PubMed1990

Analysis of the regulatory region of the Escherichia coli nupG gene, encoding a nucleoside-transport protein.

The S1-mapping procedure, when applied to an 800-bp fragment upstream of the nupG structural gene of Escherichia coli revealed one transcription-initiation site. The corresponding promoter is negatively regulated by the cytR and the deoR repressors. The expression of the gene is activated by the complex between cAMP and its receptor protein. In strains lacking cAMP the promoter expression is reduced and it is no longer regulated by the cytR repressor, whereas the deoR regulation is retained.

Bacterial Proteins↗
PubMed1990

Does dextran 40 reduce early graft thrombogenicity? An experimental investigation on patency and platelet deposition on prosthetic graft materials in sheep.

The mechanism by which dextran 40 reduces early graft thrombogenicity has not been fully elucidated. Dextran improves haemaodynamics, reduces platelet aggregation, alters fibrin formation and enhances thrombus lysis. In this experimental investigation on sheep using a low flow model, the thrombogenicity of various grafts was studied when either a dextran or saline infusion was given. Bilateral carotid interposition grafts with expanded polytetrafluorethylene (ePTFE) on one side and dacron on the other (random allocation) were inserted in 12 sheep. The sheep were randomly divided into two groups, one given a dextran infusion and the other saline. A tendency for improved graft patency was seen in the dextran 40 treated animals (P less than 0.05 at 3 h). However, platelet accumulation did not differ markedly between the dextran 40 and saline treated groups. On the other hand there was a clear reduction of platelet accumulation on ePTFE grafts compared to dacron grafts (P less than 0.01). A large part of the radioactivity measured from the dacron graft was located within the graft wall. Further studies to clarify the mechanism of action of dextran are needed.

Animals↗
PubMed1990

Treatment of superficial thrombophlebitis. A comparative trial between placebo, Hirudoid cream and piroxicam gel.

A prospective randomized trial on the treatment of superficial thrombophlebitis has been performed in 68 patients randomized to either Hirudoid cream, piroxicam gel or placebo. Both spontaneous and infusion thrombophlebitis were included. Treatment effect was evaluated using the status of thrombophlebitis, the thrombophlebitic area, pain intensity with a visual analogue scale, and side effects were registered. Both in the treatment groups and the placebo group there was a significant decrease of signs and symptoms during the treatment period. There was no statistical difference between the treatment groups and no difference between spontaneous and infusion thrombophlebitis.

Administration, Topical↗
PubMed1987

Biochemical and biological activities of 2,3-dihydro-6-[3-(2-hydroxymethyl)phenyl-2-propenyl]-5-benzofuranol (L-651,896), a novel topical anti-inflammatory agent.

The biochemical and biological profile of a topical anti-inflammatory agent, 2,3-dihydro-6-[3-(2-hydroxymethyl)phenyl-2-propenyl]-5-benzofuranol (L-651,896 inhibited the 5-lipoxygenase of rat basophilic leukemia cells with an IC50 of 0.1 microM and leukotriene synthesis by human PMN and mouse macrophages with IC50 values of 0.4 and 0.1 microM respectively. L-651,896 also inhibited prostaglandin E2 synthesis by mouse peritoneal macrophages (IC50 = 1.1 microM). This compound inhibited ram seminal vesicle cyclooxygenase activity at considerably higher concentrations, and this effect was directly related to substrate concentration. When applied topically to the mouse ear, L-651,896 lowered elevated levels of leukotrienes associated with arachidonic acid-induced skin inflammation and delayed hypersensitivity induced by oxazolone. However, while L-651,896 inhibited the increased vascular permeability induced by arachidonic acid, it had no effect on the edema associated with the immune-based response to oxazolone in the same tissue. Thus, it is possible that leukotrienes may play a role in some but not all inflammatory responses.

Administration, Topical↗
PubMed1987

Studies on the sequence and structure of the Escherichia coli K-12 nupG gene, encoding a nucleoside-transport system.

The nupG gene, encoding one of the two active nucleoside-transport systems in Escherichia coli K-12, has been cloned on the multicopy plasmid pBR322 and derivatives thereof. The recombinant plasmids complemented a chromosomal nupG mutation. A genetic map was determined by digestion with restriction endonucleases and the nucleotide sequence of a 3-kb stretch of DNA has been determined on fragments cloned into M13 phages. An open reading frame of 1254 bp, encoding a protein with a calculated molecular mass of 45.333 kDa, was deduced to be the coding region of nupG. Minicell-forming strains carrying plasmids containing this gene were shown to produce a hydrophobic, membrane-bound polypeptide with an apparent molecular mass of approximately 43 kDa.

Base Sequence↗
PubMed1983

Inhibition of the release of prostaglandins, leukotrienes and lysosomal acid hydrolases from macrophages by selective inhibitors of lecithin biosynthesis.

The release of the inflammatory mediators, prostaglandins (PGs), leukotrienes (LT) and lysosomal acid hydrolases (LAH), by macrophages is stimulated by endocytic stimuli such as zymosan. This process can be interfered with by specific inhibitors of phosphatidylcholine (PC) biosynthesis. The diphenylsulfone dapsone and three analogs selectively inhibited [14C]choline incorporation into PC but had varied effects on inhibition of mediator release by macrophages. Dapsone inhibited the release of PGs, LT and LAH, whereas the three closely related structural analogs inhibited LAH release only, with little or no effect on PG production.

Animals↗
PubMed1981

Yersinia enterocolitica in raw goat's milk.

Biochemical and serological data are presented for 35 isolates of Yersinia enterocolitica from raw goat's milk produced in New South Wales, Australia. Strains resembled biotype I or 2, but the majority (25 of 35) fermented rhamnose and some showed other atypical reactions.

Animals↗
PubMed1980

Adverse reactions to urographic contrast medium. Rapid versus slow injection rate.

Adverse reactions following very rapid (ten seconds) and slow (two minutes) i.v. bolus injection of meglumine ioxitalamate (380 mg I/ml, 1.5 ml/kg bodyweight) for urography were compared. Except for warmth and a mild transient headache, rapid injection caused no higher incidence of adverse reactions. The rapid injection provides a high quality nephrogram. It may be hazardous in patients with pre-existing heart disease.

Adolescent↗
PubMed1978

Displaced renal lobe simulating tumour.

Three cases of renal pseudotumour are presented, with the radiographic appearances. At urography, a mass is demonstrated. Angiography reveals slight displacement of the interlobar arteries, a normal venous phase, but no tumor vessels. The nephrographic effect is similar in the mass and in the renal parenchyma. The nephroscintigraphy is likely to be normal. The main differential diagnoses are mentioned.

Diagnosis, Differential↗