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P Aarnio

Publications and source records attributed to P Aarnio.

At least 37 records · Page 2Linked to original sources
PubMed1999

End-user point of view to establish real-time broadband ATM connection over Europe.

There have so far been few discussions about how the international broadband services will be created in practice. In this paper we concentrate on two separate international telemedicine trials in which Satakunta Central Hospital took part in the HIM project. In these trials we tested real-time video consultation over the international point-to-point ATM network connection between hospitals in Finland, Portugal and Germany. The quality of the consultations were clinically first-rate in both trials. The technological lesson learned from these trials was valuable for the operators in establishing broadband connections in Europe. The network connection was analysed based on transmission capabilities of the network connection.

Computer Communication Networks↗
PubMed1998

Comparison of tissue reactions in the tracheal mucosa surrounding a bioabsorbable and silicone airway stents.

BACKGROUND: Treatment of tracheobronchial stenosis is problematic. Conservative methods include stenting the stenotic area, but an ideal stent has not yet been developed. Bioabsorbable airway stents offer benefits; the extraction of the device is unnecessary, and the airway preserves its normal function after stent resorption. The aim of this study was to examine the suitability of self-reinforced poly-L-lactide as a material for an airway stent. METHODS: A spiral airway stent made of 0.7-mm wire of self-reinforced poly-L-lactide was implanted operatively in 9 rabbits intratracheally; silicone stents served as controls. RESULTS: Silicone stents had a tendency to become stenosed with encrustation material and to develop a hyperplastic polyp at both ends. Self-reinforced poly-L-lactide stents were well tolerated and caused no foreign body reaction, and they had a tendency to penetrate into the tracheal wall. They had disappeared at the end of the follow-up of 10 months. CONCLUSIONS: This experimental study showed that bioabsorbable self-reinforced poly-L-lactide is a promising material for an airway stent for treatment of airway stenosis.

Absorbable Implants↗
PubMed1998

Raised endothelin content in bronchoalveolar lavage fluid during lung allograft rejection in pigs.

Various pathophysiologic mechanisms are implicated in the rejection of transplanted lungs, for example production of vasoactive substances such as endothelin. In this study the measured endothelin content of bronchoalveolar lavage (BAL) fluid was correlated to the grade of lung allograft rejection. Left lung allotransplantation was performed in seven piglets (weight 16-24 kg). Triple-drug immunosuppression (cyclosporin, azathioprine, methylprednisolone) was given, and episodes of acute rejection were induced by withdrawing the medication. The development of acute rejection was monitored with computed tomography and bronchoscopy with BAL and transbronchial biopsy. In 46 BAL samples the endothelin content was radioimmunologically assayed. Transbronchial biopsies taken simultaneously showed grade 0 rejection in 17 tissue samples, grade 1 in 21 and grade 2 in eight. The endothelin content of BAL (pg/ml) increased from 34.3 +/- 6.1 in grade 0 rejection to 54.6 +/- 6.8 in grade 1 and to 98.5 +/- 35.6 in grade 2. The increase from grade 0 was statistically significant to grade 1 (p < 0.05) and to grade 2 (p < 0.02). The increased endothelin content of BAL may have harmful effects on the lung, as endothelin is a potent vaso- and bronchoconstrictive peptide with mitogenic properties.

Animals↗
PubMed1997

In vitro pulmonary arterial relaxation after experimental lung transplantation with extracorporeal circulation.

OBJECTIVE: In search of an agent to attenuate the increased pulmonary vascular resistance after lung transplantation with extracorporeal circulation, we investigated contractions and relaxations of isolated porcine pulmonary arterial rings in organ chambers. METHODS: Rings of arteries from three groups were studied. Rings from the heart-lung block were studied immediately after Euro-Collins flush (n = 6). Rings from the recipient's native (n = 5) and transplanted (n = 5) lung were studied after 3 h of right heart bypass following transplantation. The duration of cold ischemia of the transplanted lung was 3-4 h. Contractions to potassium chloride and phenylephrine were measured. In order to study relaxations, the rings were preconstricted with phenylephrine. Relaxations to acetylcholine, adenosine diphosphate and isoproterenol were determined in rings with endothelium, and relaxations to sodium nitroprusside in rings without endothelium. RESULTS: Sodium nitroprusside induced complete relaxations (100%) in rings of arteries from all three groups. Relaxations to acetylcholine and adenosine diphosphate were comparable among the three groups, but relaxations to isoproterenol were significantly depressed in pulmonary artery rings from the transplanted lung, compared with those from the native lung. CONCLUSIONS: Lung transplantation with extracorporeal circulation is associated with depressed beta-receptor-mediated vasodilation, but the pulmonary vascular smooth muscle cell's ability to relax is not affected.

Animals↗
PubMed1997

Experimental piglet lung transplantation: histological bioptic changes and autopsy findings.

To investigate difficulties in diagnosing pulmonary rejection and to create a new model to observe long-term histological consequences, 21 piglets were subjected to left single lung transplantation. Five of these transplants served as targets for unmodified rejection in piglets without immunosuppression (Group I), 13 recipients were treated with cyclosporin A, azathioprine and methylprednisolone (Group II), and in 3 cases reimplantation of an autograft was performed (Group III). In the course of postoperative graft monitoring, transthoracic/bronchial biopsies were obtained on days 3, 5, 7, 10, 14, and 20, and thereafter less frequently up to 134 days. In the unmodified rejection group, grafts consolidated in one week and histologically presented perivascular mononuclear cell infiltrates, except for one case which showed vasculitis. Lymphocytic bronchiolitis and or peribronchiolar infiltrate was present in three of the four autopsied grafts. In Group II acute rejection was detected six times in three piglets, and all except one of these specimens had a peribronchiolar component. Although no incontestable bronchiolitis obliterans developed, mild to moderate chronic obliterative vascular lesions were detected in all immunosuppressed piglets (n = 3) surviving more than 80 days. Contralateral lungs and Group III autografts showed mild changes related to the operation itself and interstitial swine endemic pneumonia (SEP). Chronic changes related to rejection were limited to the vascular wall. The mainly inflammatory bronchiolar changes are thought to present an incipient phase leading to obliterative lesions.

Anastomosis, Surgical↗
PubMed1997

Detection of acute rejection by 133Xe radiospirometry after single lung transplantation in an experimental porcine model.

Aim of this experimental study was to evaluate acute rejection in a porcine single-lung transplantation model by using 133Xe radiospirometry. Left lung allotransplantation was performed on 11 and autotransplantation on 5 piglets. Postoperative monitoring consisted of 77 radiospirometric examinations with assessments of regional perfusion (Qtx), ventilation (V) and ventilation/perfusion ratio (V/Qtx). Results were compared with transbronchial biopsy. A significant decrease in Qtx (p < 0.01) and an increase in V/Qtx (p < 0.01) were observed during acute rejection, whereas V remained unaltered. These changes were significant already at minimal rejection (grade A1), and further increased at moderate rejection (grade A3). Sensitivity and specificity of Qtx were 82 and 74%, and those of V/Qtx, 87 and 65%. 133Xe radiospirometry detects even minimal acute rejection after single lung transplantation.

Acute Disease↗
PubMed1997

Acute rejection diagnosed with computed tomography in a porcine experimental lung transplantation model.

The role of computed tomography (CT) in the diagnosis of acute rejection was studied in an experimental lung transplantation model, with 15 left lung allotransplantations and six autotransplantations performed on piglets weighing 16-24 kg. There were 31 episodes of acute rejection. In the allotransplantation group the development of acute rejection was monitored 115 times with CT, transbronchial biopsy (TBB) and bronchoalveolar lavage (BAL). The stages of acute rejection were 1) ill-defined centrilobular micronodules or minimal patchy ground-glass opacities. 2) dense, small-nodular infiltration or extensive ground-glass opacities, and bronchial wall thickening. 3) lung volume loss and dense, patchy ground-glass opacities and 4) consolidation of the lung. In the autotransplantation group monitoring was done 42 times. After allotransplantation, TBB and BAL suggested rejection 60 times and infection 23 times. CT had 86.7% sensitivity and 85.6% specificity. During the first month these figures were, respectively, 71.4% and 84.2%. Rising histologic grade was associated with increasing stage of acute rejection on CT, which thus proved to be a sensitive and specific method for diagnosing acute rejection of lung transplant.

Acute Disease↗
PubMed1996

Effects of acute rejection and antirejection therapy on arteries and veins from canine single lung allografts.

Experiments were designed to compare the function of the endothelium and smooth muscle in intralobar pulmonary arteries and veins of transplanted lungs during acute rejection and after treatment of rejection. Single lung allografts were performed in dogs. Dogs were monitored for 5 days to allow good recovery from the operation and resolution of early chest radiographic changes. In group I, immunosuppression (cyclosporine A, azathioprine, and methylprednisone) was withdrawn to allow rejection, which typically occurred after 3 days. In group II, immunosuppression was reinstituted at this time during acute rejection until the chest roentgenograms again cleared (approximately after 6 days). The blood vessels were studied at this time. Rings were cut from intralobar pulmonary arteries and veins of the allotransplanted lungs and suspended for the measurement of isometric force in organ chambers. Contractions of arteries and veins to phenylephrine but not endothelin-1 were significantly reduced during acute rejection. In arteries and veins, endothelium-dependent relaxations to bradykinin but not the calcium ionophore A23187 were reduced with rejection. Relaxations of the smooth muscle to histamine increased with rejection in both blood vessels. Relaxations to nitric oxide were reduced with rejection in veins but not arteries. Treatment of rejection reversed all responses toward those observed in arteries and veins in lungs from dogs not undergoing transplantation. These results suggest that responses of the endothelium and smooth muscle of pulmonary arteries and veins of transplanted lungs are altered similarly during rejection. Further, treatment of rejection restores function of the pulmonary blood vessels of lung allografts toward that observed in unoperated lungs.

Animals↗
PubMed1996

Endothelin in bronchoalveolar lavage fluid is increased in lung-transplanted patients.

Animal studies have shown increased endothelin in bronchoalveolar lavage (BAL) fluid during unmodified rejection. We performed radioimmunoassay of endothelin in 59 BAL fluid samples from ten patients at different times after lung transplantation. All patients received immunosuppressive therapy (cyclosporin, azathioprine and methylprednisolone). Reference BAL samples were obtained from six controls. Of the 59 test samples, five were collected during rejection episodes, confirmed by clinical outcome, BAL cytology and radiology (rejection group), and 19 were taken during bacterial, viral or fungal infection (infection group). The endothelin content of BAL (pg/ml) was significantly greater in the rejection group than in the infection group (61.1 +/- 3.8 vs 40.6 +/- 2.0) or in the 35 samples taken in uncomplicated course after lung transplantation (40.9 +/- 5.4), p < 0.01. The endothelin level in BAL fluid from the controls was only 3.0 +/- 1.4 pg/ml, significantly less (p < 0.005) than in all the lung-transplanted groups. Endothelin in BAL fluid thus was increased after lung transplantation, and still further during rejection.

Bronchoalveolar Lavage Fluid↗
PubMed1994

Endothelin content of bronchoalveolar lavage fluid from allotransplanted pigs is increased during unmodified rejection.

To find a new method for detection of rejection of allotransplanted lungs, we studied the endothelin content of bronchoalveolar lavage fluid by radioimmunoassay. Left-sided lung allotransplantation was performed in pigs. One group of animals received no treatment with immunosuppressive drugs (rejection group), the other group of animals (treated group) was treated with a triple-drug immunosuppressive regimen (cyclosporine, azathioprine, and methylprednisone), and nontransplanted lungs were controls. The endothelin content in bronchoalveolar lavage fluid was significantly elevated in the group of pigs with unmodified rejection (29.20 +/- 1.96 pg/ml) compared with that in the immunosuppressed group (15.3 +/- 2.4 pg/ml) and control group (4.27 +/- 1.23 pg/ml). The measurements were made from 5, 33, and 11 samples of bronchoalveolar lavage fluid from the rejection, treated, and control groups, respectively. These results suggest that endothelin content of bronchoalveolar lavage fluid could be a marker of lung allograft rejection.

Animals↗
PubMed1993

Autonomic modulation of contractions to endothelin-1 in canine coronary arteries.

Endothelin-1 contracts vascular smooth muscle and inhibits release of neurotransmitter from adrenergic and cholinergic neurons. Experiments were designed to investigate the interaction of these mechanisms in a blood vessel that receives both adrenergic and cholinergic innervation. Rings cut from canine left anterior descending coronary arteries were suspended in organ chambers for the measurement of isometric force. In some rings, the endothelium was removed. Endothelin-1 caused concentration-dependent increases in tension in all rings. During electrical stimulation (1 Hz, 9 V, 2 msec), the contractions to endothelin-1 were reduced significantly. In rings without endothelium, this decrease was greater in the presence of atropine (10(-6) M) and was eliminated by a combination of phentolamine (10(-5) M) and propranolol (5 x 10(-6) M). Contractions to endothelin-1 during electrical stimulation in rings with endothelium were significantly less than those without endothelium. This difference was eliminated by atropine and NG-monomethyl L-arginine (10(-4) M). The presynaptic effects of endothelin-1 were studied by measurement of tritium-labeled norepinephrine. Phasic electrical stimulation induced release of norepinephrine; this was inhibited by endothelin-1 at high concentrations (4 x 10(-7) M) in the presence of atropine. These results suggest that the major effect of endothelin-1 is postsynaptic in canine coronary arteries. However, contractions to endothelin-1 may be modulated by the level of sympathetic and parasympathetic tone. In situations in which innervation to the coronary arteries is altered, for example, in hearts used for transplantation, the contractile effects of endothelin-1 would prevail.

Animals↗
PubMed1992

Long-term blood flow potentials in sequential internal mammary artery grafts. Exercise thallium scan for myocardial perfusion study.

In two groups of patients, coronary artery bypass surgery for angina pectoris included internal mammary artery (IMA) sequential grafts (group I) or single grafts (group II). At postoperative angiography all grafts were patent. In addition, the patients received on average 1.8 vein grafts into other coronary arteries. The mean interval to postoperative follow-up was 9.5 years in group I and 9.7 years in group II. The preoperative incidence of acute myocardial infarction was 44% and 45% in groups I and II. Exercise thallium scan at follow-up showed IMA graft-related ischemia in 33% of the patients with sequential graft and in 64% of those with single graft (ns). Our results indicated that sequential IMA grafts functioned at least as well as single grafts and maintained adequate myocardial supply even 10 years postoperatively. Internal mammary arteries are superior graft material and can be recommended both as single and as sequential graft in coronary artery bypass surgery.

Aged↗