Radioactive dextran particles for studying circulation in animals.

Two types of dextran particles, (density 1.12 g X cm-3), ie chelating dextran particles (diameters 15.0 and 52.0 microns) and Sephadex (diameter 49.5 microns) were prepared for use as radioactive microspheres after labelling with 57Co, 58Co or 131I. The labelling efficiency was 96.4% with 57Co or 58Co and 7.8% with 131I. The specific activities were in the range 1 to 60 microCi X mg-1. The dissociation of cobalt label was found to be negligible in vitro, and in vivo 0.4 to 0.7% per h. Most of this activity was rapidly excreted in the urine. 35 days after injection of 15 microns particles they were still entrapped in the lungs and had undergone no microscopic changes and caused no tissue reaction. The findings validate the use of cobalt labelled particles for animal experiments of several hours duration. The dissociation of the iodine label was considerable both in vitro and in vivo limiting the use of the iodine labelled particles to experiments where a single determination of blood flow distribution is sufficient.

Decreased acute thrombogenicity of human umbilical veins after heparin and alcohol treatment.

Nine glutaraldehyde-tanned human umbilical veins (GAUV) were incubated in heparin followed by storage in ethyl alcohol 50% (HAUV). These grafts were compared to five GAUV flushed with a heparinized solution without subsequent treatment in alcohol (HsAUV) and four nonheparinized GAUV (NHUV) placed in the contralateral carotid arteries of dogs for approximately 3 h. The thrombogenicity was evaluated by measuring the platelet adhesion and aggregation (51Cr), fibrinogen accumulation (125I-fibrinogen), the thrombus-free surface and the thrombus weight. The HAUV had the lowest 51Cr radioactivity. The means of thrombus-free surface and thrombus weight for the grafts were as follows: HAUV, 82% and 0.3 g (n = 9); HsAUV, 53% and 0.6 g (n = 5); NHUV, 13% and 1.2 g (n = 4). The HAUV showed a lower thrombogenicity than both the NHUV and the HsAUV grafts.

A novel semi-synthetic sulphated polysaccharide with potent antithrombin activity.

A mucopolysaccharide was isolated from mussel broth. After sulphation, an electrophoretically homogenous product was obtained with a molecular weight of approximately 40 000 daltons and a sulphur content of about 12%. The sulphated polysaccharide (S-Lim) displayed an anticoagulant activity in a thrombin test system with human plasma. Unlike heparin, the anticoagulant effect of S-Lim was observed also in a thrombin-fibrinogen clotting system in the absence of AT III. Complete inhibition of the effect of 1.0 mg S-Lim was achieved with 1.5 mg protamine. In an activated partial thromboplastin time test system the anticoagulant activity of 1.0 mg S-Lim corresponded to about 40 iu of heparin. S-Lim was also found to inhibit thrombin-induced platelet aggregation. Furthermore, S-Lim inhibited the thrombin-dependent activation of factor XIII in human plasma. S-Lim did not affect various tests systems measuring factor Xa activity. It is concluded that this new sulphated mucopolysaccharide acts as a pure antithrombin with a potency corresponding to 40--50 iu heparin/mg S-Lim. In contrast to heparin and other heparinoids it does not require the presence of AT III.

Controlled blocking of hepatic artery flow with enzymatically degradable microspheres combined with oncolytic drugs.

A new method for intermittent hepatic arterial flow arrest has been used in combination with intraarterial 5-fluorouracil (5-Fu) for the treatment of secondary liver neoplasms in 12 patients. Polysaccharide microspheres with a half-life of 1 h were infused together with 5-Fu via a percutaneously introduced catheter into the hepatic artery. There were no significant side effects to the treatment. Clinical effects and overall survival were comparable to those of hepatic artery ligation.

Studies in pharmacokinetics and tolerance of substances temporarily retained in the liver by microsphere embolization.

Earlier investigation has shown that a temporary arrest of arterial blood flow can be achieved by embolization with degradable microspheres. This study was made to investigate the change in pharmacokinetics, and drug tolerance which takes place when a substance is retained in the liver by a microsphere embolization. 14C-labelled inulin and 5-fluorouracil were studied. The administration of these substances with microspheres led to a delay in their systemic distribution. Furthermore there was an increased tolerance to 5-fluoro-uracil, probably due to a prolonged first pass effect when the substance was temporarily retained in the liver by a microsphere embolization.

The circulation in liver tissue and experimental liver metastases before and after embolization of the liver artery.

Simultaneous measurement of cardiac output distribution with 86Rubidium and 57Cobalt-tagged microspheres in rats implanted with liver tumors by intraportal injection of sarcoma cells enables quantitation of arterial and portal tumor circulation. The portal circulation was found to be increased in small tumors as compared to the liver, but as the tumor grew there was a decrease in the portal tumor circulation. When the tumor growth became massive even the total liver circulation was reduced, as measured with 133Xenon wash-out. All the tumors had increased arterial circulation. This arterial hyperperfusion was changed into ischemia when the liver artery was occluded through embolization with degradable microspheres.

Repeated arterial embolization of rat livers by degradable microspheres.

A transient arrest of arterial blood flow can be accomplished by intra-arterial injection of a new type of degradable microsphere. The effects of single and multiple injections of these microspheres into rat hepatic arteries were studied by measurements of fractional cardiac output distribution and 133Xe washout from the liver before and after embolization. Injection of these microspheres into the hepatic artery caused a significant but transient reduction of the arterial blood flow to the liver. Repetition of the injection several times over several days produced identical effects on each embolization. No signs of hepatic cell damage were detected after repeated embolization, as suggested by assay of the serum enzymes or the Bromsulphalein retention test.

Fibrinolytic activity in wound secretions.

Debrisan, a highly hydrophilic dextran polymer, was previously shown to be effective in cleaning infected wounds. The dry beads remove wound secretions from the wound surface under gel formation. The gel can then be analysed. A high fibrinolycic activity on fibrin plates and high levels of fibrin/fibrinogen degradation products were found in the secretions from 12 wounds. Low of plasminogen, antithrombin III and the absence of coagulable fribinogen also indicated a high fibrinolytic activity. A higher fibrinolytic activity on heated than on unheated fibrin plates, and the insignificant effect of local application of EACA suggest the presence of other proteolytic enzymes than plasmin.

Studies on healing of Debrisan-treated wounds.

Debrisan (Pharmacia AB, Sweden) is a highly hydrophilic dextran polymer in the form of dry, spheric beads. When dry Debrisan beads are placed on a wound, the wound secretions are sucked up into and between the beads. No crust is formed on the wound. Bacteria granular substances are removed with the secretions. Treatment with Debrisan was found to be very effective in cleansing discharging wounds. Since Debrisan treatment removes substances from the wound area, e.g. prostaglandins, this might affect the process of repair. The morphology of wounds was studied with the aid of histological and histochemical methods. In 15 patients, donor sites on one thigh, treated with Debrisan, were compared with donor sites on the contralateral thigh, subjected to open treatment. In pigs, comparison was made between Debrisan-treated with Vaseline-gauze-covered dermal burns. In man, the inflammatory reaction was less pronounced in the Debrisan-treated wound and located more superficially then in the wound left open, where perivascular inflammatory cell infiltrates were found even deep in the dermis. In pigs the burns exhibited similar differences. Thus the inflammatory reaction in the Debrisan-treated wounds was less pronounced than in the control wounds. Debrisan beads were never seen below the wound surface. No unfavourable influence of Debrisan treatment was observed on the process of repair.

A new principle for the cleansing of infected wounds.

When dry porous hydrophilic beads, formed by a three dimensional network of dextran polymers, are placed on a discharging wound, they absorb the exudate and swell to form of a gelatinous layer. Within this gelatinous layer a separation of substances occurs according to their molecular weights, with the smaller (MW less than 1000) freely penetrating the pores of the beads and the larger (MW greater than 5 000) remaining in the interspaces. Since proteins are removed from the wound surface with the fluid, crustformation on the wound is prevented. Clotting within the gel layer does not occur, since, as shown in another study (Aberg, Hedner, Jacobsson & Rothman 1976), wound exudate contains a high amount of fibrin-fibrinogen split products and no coagulable fibrinogen. Therefore as long as dry beads are available, exudate can be sucked up. With the wound exudate bacteria, degradation products and toxins are removed from the wound surface. A substance with the above described properties Debrisan (Pharmacia AB, Sweden) was used to treat various types of wounds. The treatment was most effective for profusely discharging infected wounds. Within a few days inflammation subsided, exudate decreased and granulation tissue appeared. So far no side effects are observed and even patients, who during years of treatment of leg ulcers had become sensitized to most dressings and local antibiotics could be treated. The new technique for sampling of wound fluid also offers a model for studies on inflammatory mediators and protein loss.

A method for determining plasma proteins in inflammatory exudate absorbed by Sephadex.

Dry cross-linked dextran (Sephadex pharmaceutical grade, Debrisan) was applied to weeping sores. After some exudate had been absorbed the gels were removed. The amount of exudate was determined by isotope dilution techniques. The accuracy of the method was tested by determination of plasma proteins in samples of diluted serum containing known concentrations of some plasma proteins. The method seems suitable for determining various high and low molecular weight constituents of exudates.

Subcutaneous mastectomy in 80 patients with breast tumours. Indications, surgical results and pathological findings.

Eighty patients were operated upon with subcutaneous mastectomy and reconstruction with prosthesis. Seventy operations were performed on both breasts. The indications used were carcinoma in situ in a previous biopsy, pronounced epithelial proliferations on at least two previous occasions or recurring fibrocystic disease after at least two previous biopsies. Since the autumn of 1971, the operation has been performed as a one-stage procedure and we have had few complications. The appearance of the breasts was evaluated at review 3-60 months after operation. Most patients found the results acceptable or good. The mamilla always lost its sensibility, but the sensibility of the remaining skin of the breast sometimes returned with time. Most of the patients were well satisfied with the procedure and thought it better than any other sort of treatment. The tissues removed were thoroughly studied. Changes in the breasts were often bilateral and pronounced epithelial proliferation and carcinoma in situ were fairly common. Invasive carcinoma was found in 2 instances. The importance of the histologic examination of removed tissues is stressed. A regular follow-up of these patients is important for assessing the value and the risks of subcutaneous mastectomy.