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Biomedical subjects

S Wikström

Publications and source records attributed to S Wikström.

At least 37 records · Page 2Linked to original sources
PubMed1993

A new rat model of arterial thrombosis with a platelet-rich head and an erythrocyte-rich tail: thrombolysis experiments with specific thrombin inhibition.

A model for thrombolysis in rats was developed. Repeated, focal external heating was applied to the carotid artery which leads to the development of a cyclic blood flow with slow, steady decreases followed by abrupt increases. When this cyclic blood flow stops spontaneously, the entire arterial segment (approximately 10 mm) can be demarcated with snares to create an arterial thrombus of fixed size, with a platelet-rich head and an erythrocyte-rich tail. The usefulness of the model was tested by evaluating the thrombolysis induced by a low dose of recombinant tissue-type plasminogen activator (rt-PA) alone and rt-PA in combination with standard heparin and recombinant hirudin. Re-canalization of the artery was measured as blood flow and as the residual 125I-radioactivity in the artery at the end of the experiment, resulting from 125I-fibrinogen incorporated during the formation of the thrombus. Both blood flow and 125I-activity measurements show that hirudin, but not heparin in combination with rt-PA, significantly improves thrombolysis, which is in accordance with previous experimental findings. It is concluded that the model, with a thrombus resembling the thrombus found in man after coronary occlusion, enables complicated experiments with thrombolysis frequently performed only in large animals to be performed in rats.

Animals↗
PubMed1992

Surgical results in the International Reflux Study in Children (Europe).

In the European part of the International Reflux Study in Children (7 participating centers) 151 infants and children were randomly allocated to surgical treatment of primary grades III and IV vesicoureteral reflux. Reimplantation was performed unilaterally in 65 patients and bilaterally in 86, for a total of 237 ureters reimplanted. The patients were followed at regular intervals for 5 years. Reflux was absent in 231 of the reimplanted ureters (97.5%) at the end of 5 years. No patient underwent reoperation for reflux. In 10 ureters (4.2%, 10 patients) obstruction developed postoperatively and 7 needed reoperation. All reoperations were performed on the left side. Of the obstructed kidneys new scars developed in 6 during the 5-year followup. Including these cases, the number of new renal scars was equal in the surgical and medical groups (20 each). The number of pyelonephritic episodes during followup was significantly less in the surgical group (without chemoprophylaxis) than in the medical group (on chemoprophylaxis). No kidneys were lost and no child became hypertensive. If voiding cystourethrography and excretory urography were normal 6 months postoperatively, the reflux had been permanently eradicated and postoperative obstruction could be ruled out. In this study the patients who underwent reimplantation had a 74% (112 of 151) chance of an uncomplicated postoperative course (no persisting reflux, obstruction, pyelonephritis or severe renal damage).

Child↗
PubMed1992

[Hypospadias].

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Child, Preschool↗
PubMed1991

Localized amyloidosis of the urinary bladder.

Localized amyloidosis of the urinary bladder is a rare condition. Five patients, 1 with localized secondary amyloidosis, are described. The symptoms, macroscopic hematuria and tumor-like appearance in cystoscopy, may mimic bladder cancer. Diagnosis is based on histopathological examinations with Congo red staining. In most instances, the treatment of choice is transurethral resection and electrocoagulation. Because of the risk of recurrences, a close follow-up is recommended.

Aged↗
PubMed1991

Percutaneous needle biopsy preceding preoperative chemotherapy in the management of massive renal tumors in children.

While the National Wilms' Tumor Study (NWTS) Group in the United States puts an emphasis on accurate staging and histology before any therapy is given for Wilms' tumor, the International Society of Pediatric Oncology (SIOP) in Europe focuses on preoperative therapy and safer surgery. Our current approach combines the benefits of both policies in the management of massive renal tumors in children. In seven consecutive patients we first obtained a percutaneous posterior needle biopsy to obtain adequate tissue for histology, and proceeded with preoperative chemotherapy with vincristine and dactinomycin until tumor shrinkage was sufficient. Tumor removals were feasible and uneventful. At the time of operation, two tumors were found to be totally or almost totally necrotic. In the others, which still included viable tumor, the histology corresponded well to the needle biopsy findings. One case with unfavorable histology and one with rhabdoid sarcoma would have been missed and given suboptimal therapy without the primary needle biopsy. As possible biopsy-related complications, subcapsular intratumoral bleeding was recognized in two patients. We conclude that percutaneous posterior needle biopsy is safe and yields definite, detailed histology in massive renal tumors in children. Preoperative chemotherapy facilitates surgery in these patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1988

Improved prognosis for children with stage IV neuroblastoma: high-dose melphalan and autologous unpurged marrow transplantation after aggressive surgery and short chemotherapy with cisplatinum and etoposide.

A new therapeutic approach was adopted for 13 consecutive patients with stage IV neuroblastoma over 1 year of age admitted to the Children's Hospital, University of Helsinki, between October 1981 and August 1985. Treatment was based on induction, with aggressive, repeated early surgery and a relatively short course of chemotherapy with cisplatinum and etoposide, and on consolidation, with 140-180 mg/m2 of melphalan followed by autologous unpurged bone marrow. Induction therapy failed in only 2 of the 13 patients. One of the two was never autografted. So a total of 12 children underwent autologous marrow transplantations, 10 in primary and 1 in secondary remission, and one with residual disease. One patient died in septicemia during postmelphalan pancytopenia, and four patients relapsed 0.3-2.9 years after transplantation. Seven of the original 13 patients (54%) are well and living in continuous remission 2.3-4.1 (median 2.8) years after diagnosis.

Antineoplastic Agents↗
PubMed1984

Delayed dopamine treatment of segmental small intestinal ischaemia in the rat.

Two groups of rats were subjected to segmental ischaemia of the small intestine for 2 h. According to our previous findings such ischaemia causes impairment of the central circulation as well as of the splanchnic blood flow. Dopamine treatment was initiated 30 or 90 min after the establishment of ischaemia. In the 30-min group cardiac output increased and the blood flow was normalized in those parts of the small intestine where the arteries were not ligated (the non-occluded parts). This result corresponds well to our previous observations when dopamine treatment was started immediately after the establishment of ischaemia. In the 90-min group cardiac output was not affected. Again the intestinal blood flow was normalized in the non-occluded parts. In both groups the pancreatic circulation was impaired.

Animals↗
PubMed1984

Haemodynamic effects of phenoxybenzamine and dopamine in segmental ischaemia of the rat small intestine.

Two groups of rats were subjected to a segmental intestinal ischaemia of a degree which, according to earlier investigations with this experimental model, causes secondary impairment of the splanchnic blood flow. Both groups were given plasma and an alpha-adrenergic blocking agent (phenoxybenzamine). They were also given dopamine but in different doses, 12 and 50 micrograms X min-1 X kg-1 b.w., respectively. It was found previously that a normal blood flow in the non-occluded parts of the small intestine could be maintained by phenoxybenzamine or the lower dose of dopamine alone in combination with plasma, but the higher dopamine dose caused vasoconstriction, probably because of an alpha-stimulating effect. The combined treatment with penoxybenzamine and dopamine in the present experiments normalized the intestinal blood flow in the non-occluded parts in both groups, i.e. also in the group treated with the higher dose of dopamine. Moreover, the pancreatic circulation was normalized in both groups. Hence alpha-adrenergic blockade combined with dopamine and plasma administration seems to have a positive effect on the splanchnic circulation during segmental intestinal ischaemia in the rat.

Animals↗
PubMed1982

Bilateral Wilms' tumor and secondary malignancies.

A series of six patients with bilateral Wilms' tumor (nephroblastoma) is presented. Multimodal therapy yielded a survival rate of 83% at 2 yr of follow-up. However, at the end of a later follow-up period only two patients (33%) were alive. of the 4 patients who died. Only 1 died of Wilms' tumor. One died of complications of aggressive chemotherapy and two patients died after 12 and 16 yr following treatment of secondary malignant tumors arising in the irradiated region. Patients with bilateral tumor should be followed at regular intervals for the duration of life for the occurrence of secondary malignant tumors.

Child, Preschool↗
PubMed1978

Regional and central hemodyanamics during segmental ischemia of the small intestine in the rat.

The influence of segmental small intestinal ischemia on the central circulation and on the regional blood flow to consecutive segments of the small intestine in the rat was investigated with the microscphere method. Ischemia was established by ligating 11 arterial mesenteric end arcades, corresponding to one quarter of the total length of the small intestine. The blood supply to different organs and central circulatory variables were determined before, and 10 min, 30 min, 2 h and 14 days after the establishment of the ischemia. After 10 min of ischemia, there was an increase of the blood flow to the segments distal to the ischemic region but after 30 min, this blood flow was the same as the control flow. The central circulatory variables weere not affected. After 2 h of ischemia, the blood supply to both the ischemic and the non-ischemic part of the small intestine had deteriorated considerably. Thus, the vascular resistance in the ischemic segments and the segments surrounding it was increased. Cardiac output was reduced by about 50%. In the experimental group investigated 14 days after establishment of the ischemia, the mortality rate was about 50%. In the survivors, the intestinal blood supply had returned to normal.

Animals↗
PubMed1978

Microsphere measurement of regional intestinal blood supply and cardiac output in the rat.

The regional blood supply to consecutive segments of the small intestine in the anaesthetized rat was investigated with a radioactive microsphere technique. A blood flow gradient with the lowest flow in the distal segments (0.85--0.89 ml/min.g) and the highest in the proximal segments (1.13--1.15 ml/min.g) was observed. Very few microspheres were found in the portal vein blood, indicating negligible arteriovenous shunting in the splanchnic area. The mean cardiac outputs in two consecutive measurements were 27.9 and 28.7 ml/min . 100 g, respectively. The cardiac output and regional blood flow values were in accordance with those obtained with other techniques.

Animals↗
PubMed1978

Hemodynamic effects of phenoxybenzamine and volume replacement in segmental ischemia of the rat small intestine.

Segmental ischemia of the small intestine in the rat was established by ligating the mesenteric arterial end arcades of 1/4 of the length of the small intestine. Regional and central blood flow was measured with the microsphere technique before and 2 h after induction of the ischemia. In one series of rats an i.v. infusion of 16 ml plasma per kg body weight (b.w.) was given during the experimental period, which maintained the central circulation. However, the impairment of blood supply to the whole small intestine caused by the segmental ischemia was not normalized. Two other series of rats were treated with either phenoxybenzamine alone, 3 mg.kg-1 b.w., or the same dosage of phenoxybenzamine plus plasma infusion (16 ml.kg-1 b.w.). The central circulation was deteriorated and the blood flow to the small intestine reduced in the rats receiving phenoxybenzamine alone. Both the central circulation and the blood supply to the non-ischemic parts of the intestine were maintained in rats treated with both phenoxybenzamine and plasma. Combined treatment with phenoxybenzamine and volume replacement thus seems to be valuable for limiting the secondary hemodynamic changes caused by segmental intestinal ischemia.

Acid-Base Equilibrium↗