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Biomedical subjects

P Olsson

Publications and source records attributed to P Olsson.

At least 19 recordsLinked to original sources
PubMed1992

Intravenous nicotine retards transdermal absorption of nicotine: evidence of blood flow--limited percutaneous absorption.

For most drugs delivered by the transdermal route, percutaneous absorption is limited by the rate of release of the drug from the device or by diffusion across the stratum corneum. However, systemic absorption also requires that the drug be taken up by dermal blood vessels. As part of a bioavailability study of a transdermal delivery system, we observed that a concomitant intravenous infusion of nicotine had a marked effect on the absorption kinetics of transdermal nicotine. Plasma concentrations of nicotine rose less rapidly, reached a lower peak, and peaked at a later time, indicating delayed absorption of transdermal nicotine after intravenous nicotine versus after transdermal nicotine administered alone. Nicotine is known to produce cutaneous vasoconstriction. The likely explanation for our observation is that intravenous nicotine constricts dermal blood vessels, thereby limiting percutaneous absorption. Other vasoconstrictor drugs would be expected to retard the absorption of transdermal nicotine and perhaps other transdermal drugs as well.

Administration, Cutaneous↗
PubMed1992

Injection of xenogeneic endocrine pancreatic tissue into the portal vein--effects on coagulation, liver function, and hepatic hemodynamics. A study in the pig-to-dog model.

The safety of injecting discordant xenogeneic fetal endocrine pancreatic tissue into the portal vein was studied in a pig-to-dog system. It was found that minced fetal porcine pancreas and fetal porcine isletlike cell clusters prepared by collagenase digestion and culture could be injected with only minor or no hepatic hemodynamic disturbances. Coagulation studies revealed a small increase in plasma fibrinopeptide A, but this increase could be prevented by heparinization of the recipient. There was no consumption of fibrinogen or platelets. In contrast, injection of minced adult porcine pancreas caused pronounced hepatic hemodynamic changes and marked coagulation abnormalities, indicating consumption coagulopathy. The present finding that fetal porcine pancreas can be injected intraportally without deleterious effects in dogs provides a foundation for the eventual clinical use of such material as treatment for insulin-dependent diabetes mellitus.

Animals↗
PubMed1992

Efficacy of a topical nasal decongestant in different formulations: the effect of viscosity.

Factors affecting the absorption of drugs through the nasal mucosa are increasingly being studied. Dosage form factors, i.e. the viscosity of the excipients, have been claimed to be of importance for enhanced nasal absorption due to prolongation of contact time between drug and mucosa. In the present study, a comparison was made of the effect of a local nasal sympathomimetic when administered intranasally in formulations with different viscosities. Volunteers received the test drugs as nasal sprays in a randomized cross-over design by a rhinomanometric technique, the effect of the drug being recorded for up to 5 h after administration. No significant differences in effects were observed when the test formulations were compared.

Absorption↗
PubMed1992

Treatment of snoring--with and without carbon dioxide laser.

Thirty patients with bedpartners complaining of their heavy snoring which had resulted in separate bedrooms were treated surgically. Three different methods were used, each group consisted of 10 patients. In group A conventional scalpel excision was used for uvulopalatopharyngoplasty including tonsillectomy. In groups B and C, patients with small tonsils were selected and therefore the tonsils were saved. Group B was operated with carbon dioxide laser under a microscope and using micromanipulator. The same kind of excision was used as in group A but the tonsils were saved. Group C was operated as group B but using conventional scalpel excision technique. With a starting-point of snoring score 3 preoperatively in all groups, the mean postoperative snoring score in Group A was 1.0, in Group B 0.2 and in Group C 1.1. Patients with postoperative snoring scores of 0 and 1 were regarded as successful responders to surgery. No serious side effects were noted due to treatment.

Airway Obstruction↗
PubMed1991

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Community Health Services↗
PubMed1991

Heparin cofactor II significance for the inhibition of thrombin at the injured vessel wall.

The thrombin inhibitory role of antithrombin III (ATIII) and heparin cofactor II (HCII) was studied in vitro using intact and injured rabbit aortae. When intact vessels were loaded with thrombin and then exposed to either heat defibrinogenated human plasma (HDHP) or ATIII the same degree of thrombin inhibition was achieved demonstrating that ATIII was the only plasma component involved in thrombin inhibition on the intact vessel wall. When the media of the vessel wall was loaded with thrombin and then exposed to ATIII or HCII a significantly higher thrombin activity remained on the surface than when it was exposed to defibrinogenated plasma. A mixture of ATIII and HCII resulted in a greater inhibition of thrombin than ATIII or HCII alone. It is concluded that, contrary to what happens on the endothelium, HCII and ATIII inhibit additively thrombin on the injured vessel wall. HCII thus plays an essential role for the inhibition of thrombin at the injured vessel wall. It is also concluded that an additional plasma component participates in thrombin inhibition on the media but its contribution is negligible as compared with ATIII or HCII.

Animals↗
PubMed1991

Thrombin-inhibitory capacity of the injured vessel wall.

The present study examined the appearance of thrombin activity in vitro after single and repeated in vivo balloon injury of the rabbit aorta. The in vitro ability of the injured vessel wall to bind and subsequently inhibit thrombin in the presence of defibrinogenated plasma was also assessed. Thrombin activity was assayed by measuring the levels of fibrinopeptide A generated in the presence of fibrinogen. These findings were correlated with the changes observed in light and electron microscopy. Thrombin activity on the vessel wall was increased five minutes and three hours after the initial and the repeated injury, and returned to control values one week after the initial injury. When the inhibition of thrombin was assayed in the presence of defibrinogenated plasma, a diminished inhibition capacity was observed after the repeated injury, which correlated with deposition of fibrin and an enhanced inflammatory reaction as measured by the density of granulocytes covering the injured neointima. Decreased thrombin inhibitory capacity of the injured neointima appears to be linked with its increased thrombogenicity.

Angioplasty, Balloon↗
PubMed1991

Absolute bioavailability of nicotine applied to different nasal regions.

The absolute bioavailability of nicotine administered nasally, as drops to the nasal conchae and nasal septum, and as a nasal spray, has been studied in eight healthy volunteers. Single nasal doses of 1 mg nicotine were given and plasma concentrations of nicotine were followed for 6 h. Compared to an intravenous infusion of nicotine, the bioavailability of the nasal administrations was 60 to 75%. The rate of absorption was fast, the maximum concentration being reached after about 10 min. In the present study, there was no significant difference in the rate or extent of absorption between the different nasal treatments.

Absorption↗
PubMed1991

Dermal blood flow after local challenges with allergen, histamine, bradykinin and compound 48/80.

Blood flow was determined in weal and flare reactions and in late dermal reactions after skin-prick tests with allergen, histamine, bradykinin and compound 48/80 in pollen-allergic subjects. Local blood flow was measured with laser Doppler flowmetry intermittently for up to 48 hr at three distances from the prick centre (2 mm; weal, 15 mm; flare and 30 mm). Continuous recordings were also made in the weal area after challenge with bradykinn and compound 48/80. The size of the induced weal and flare area of all the substances and the late phase after allergen was determined using digitized planimetry. Furthermore, simultaneous determinations of local dermal temperature and blood flow in the weal and flare site were performed intermittently for 6 hr after allergen and histamine challenges. There was a dose-dependent and distance-related increase in blood flow for all the substances tested. The blood flow in the 2-mm registrations had normalized 20 min after bradykinin, 1.5-2 hr after histamine and 3 hr after compound 48/80, while allergen induced a continuous increase in blood flow for more than 24 hr. The area of the weal and flare reaction was dose related for all substances, and a similar dose-dependent increase was noted for the observed dermal late-phase reactions present after allergen. The local temperature after challenge with allergen and histamine was also increased in a distance-dependent manner. These studies suggest that laser Doppler flowmetry is a sensitive and reproducible method to quantify blood flow changes occurring after skin-prick tests. Different putative mediators or mast cell stimulating substances produce various response profiles, all of which differ from those observed after allergen. Temperature measurements after skin-prick tests seem to follow the observed changes in blood flow as measured with laser Doppler flowmetry, which may be why both techniques might reflect changes in capillary blood flow.

Adult↗
PubMed1991

Extracorporeal carbon dioxide removal performed with surface-heparinized equipment in patients with ARDS.

To avoid the drawbacks of systemic anticoagulation during prolonged extracorporeal circulation in patients with adult respiratory distress syndrome (ARDS) a heparinization technique has been developed by which partially degraded heparin can be covalently end-point attached to the surface of the equipment constituting the extracorporeal circuit (Carmeda Bio-Active Surface, CBAS) thereby localizing the anticoagulatory effect. Since 1986 we have used extracorporeal circuits and membrane lungs coated with the CBAS for extracorporeal lung assistance (ECLA) in 14 patients suffering from ARDS. The patients were on ECLA for 3 to 55 days with a survival rate of 43%. Our experience so far is that by using equipment coated with CBAS it is possible to perform long-term extracorporeal circulation with a minimum of intravenously administered heparin, thus avoiding the risk of major coagulation defects.

Adult↗
PubMed1991

Increased erythrocyte volume in car repair painters and car mechanics.

The biological effect of occupational long term low level exposure to organic solvents was studied in 17 car repair painters and 28 car mechanics, and compared with a control group consisting of 46 healthy men not exposed to organic solvents. The erythrocyte count (RBC) was significantly decreased for both the painters and the mechanics compared with the control group, and a significant increase in the mean erythrocyte volume (MCV) was seen in painters. The mode in size distribution of the erythrocytes (MAXRBC) was shifted towards larger cell volumes for both painters and mechanics. When data from painters and mechanics were combined, the exposed group showed a significantly reduced erythrocyte count (RBC), an increased mean erythrocyte volume (MVC), and an increased mean platelet volume (MPV) compared with the controls. Exposure measurements in combination with analysis of haematological parameters may be a tool for early detection of cellular changes in the blood caused by exposure to solvents, before the appearance of clinical symptoms.

Adult↗
PubMed1991

Veno-venous extracorporeal membrane oxygenation with a heparin-coated system in adult respiratory distress syndrome.

Three patients with adult respiratory distress syndrome were treated with veno-venous extracorporeal membrane oxygenation, ECMO, using a heparin-coated system for 8, 12 and 34 days, respectively. Despite extracorporeal blood flow of 4-5 l/min, the patients were ventilator-dependent in the initial period of ECMO. Two of the three patients showed bleeding diatheses despite only slightly elevated activated partial thromboplastin time (APTT). Blood platelet count followed a variable course and serum fibrinogen was normal. Acute pulmonary hypertensive crises, fatal systemic infection, recurrent pneumothorax and plasma leakage from the oxygenators were other main complications during ECMO. Two of the three patients survived, and follow-up showed that severely damaged lungs, if supported in the acute phase, can recover sufficiently to permit normal living.

Adult↗