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Biomedical subjects

J Ahonen

Publications and source records attributed to J Ahonen.

At least 199 records · Page 11Linked to original sources
PubMed1981

Do well-to-do and repeatedly rejecting renal allografts express the transplantation antigens similarly on their surface?

We have performed fine-needle aspiration biopsies to well-to-do and repeatedly rejecting renal allografts. After biopsy the aspirated cells were treated either (a) with monospecific rabbit antisera to HLA-ABC, -DR or beta 2m, or (b) with ordinary anti-HLA-A and B alloantisera. After wash, the cell-bound antibody was chased with Staphylococcus aureus Cowan I bacteria and the antibody-binding cell type(s) was analyzed from stained cytocentrifuged cell smears. In normal, non-transplanted human kidneys the passenger leukocytes and (part of) the endothelial cells bound strongly both anti-HLA-ABC and -DR, the tubular cells weakly anti-ABC but not anti-DR while the glomerular cells did not bind either type of antiserum or bound them only very weakly. In 7 or 8 transplants with an excellent postoperative course we were unable to demonstrate the HLA-ABC and DR antigens on the graft endothelial component. Instead, in 7 of 8 transplants with repeated late rejection episodes, both the HLA-ABC and DR antigens were distinctly expressed on the endothelial cells of the graft.

Animals↗
PubMed1981

Comparison of two different immunosuppressive dosages of methylprednisolone in clinical renal transplantation.

In order to study the immunosuppressive effect of methylprednisolone, thirty cadaver kidney recipients where randomly allocated into two groups: the low dose control group and the high dose experimental group. In 12 patients in the control group a clinical rejection episode occurred within two weeks of the transplantation, 3 rejections were irreversible, whereas 7 patients rejected in the experimental group, there were no irreversible rejections. In the low dose group the clinical rejection occurred significantly earlier. Fine needle aspiration biopsies of the grafts showed that the number of macrophages infiltrating the graft was significantly lower in the experimental group. Increasing the dose of methylprednisolone given prophylactically can modify the number and severity of rejection episodes early after renal transplantation.

Adult↗
PubMed1981

Bursting strength of syngeneic aortic vein grafts in the rat.

Mechanical strength of the supradiaphragmatic part of the vena cava transplanted from one rat into the abdominal aorta of another rat of the same inbred strain was studied before transplantation, as well as 3 days and 1, 2, 3 and 4 weeks after transplantation. Bursting pressure was determined by distending the specimens with water at a constant infusion rate. The diameter of the specimens was measured at the moment of burst by a shadow technique, and the wall thickness by a micrometer on formalin-fixed and paraffin-embedded transverse sections, thus enabling calculation of bursting wall tangential and circular tension. No significant changes in bursting pressure were observed within 2 weeks after transplantation. Three and 4 weeks after transplantation a significant increase in bursting strength was observed. This increase coincided with the increase in collagen concentration previously reported. The previously reported initial decrease in collagen concentration did not, however, result in significant changes in the bursting strength. It is suggested that the increase in the thickness of the vein wall due to the increase of components other than collagen compensates for the loss of collagen.

Animals↗
PubMed1981

Connective tissue changes in autogenous vein graft used as a mesocaval shunt.

Autogenous jugular vein was used as a mesocaval shunt in dogs with ligated portal vein. Nine out of fifteen animals survived the operation and could be used for further studies one month postoperatively. Immediately after the shunt procedure an increased portosystemic pressure gradient was observed. However, this returned to normal at one month after the operation. At this time the graft was patient in seven out of nine dogs. Histological studies of the graft showed a smooth neointima and an increased number of elastin fibers in the media. The collagen concentration of the vein wall was significantly reduced and the glucosaminoglycans were significantly increased. It was however, not possible to assess the relative role of the operative trauma and the new haemodynamic and anatomical environment.

Animals↗
PubMed1981

The effect of methylprednisolone and vitamin A on wound healing. I.

The effect of methylprednisolone and vitamin A on wound healing was studied by analysing various relevant granulation tissue components in rats. The granulation tissue development was induced by viscose cellulose sponges implanted subcutaneously. Methylprednisolone and vitamin A were applied either locally into the sponge at the time of operation or systemically and daily throughout the observation period of 3 weeks. Methylprednisolone alone, both systematically and locally, retarded the development of granulation tissue, as shown by reduced amounts of collagen and delayed development of vascularity. This effect was partially reversed with simultaneous administration of vitamin A at one week. Local application of vitamin A resulted in increased hemoglobin and DNA values but did not significantly affect the amount of hydroxyproline in methylprednisolone-treated granulation tissue. Systemic administration of vitamin A resulted in methylprednisolone-treated granulation tissue at one week. Vitamin A alone did not have any effect on collagen accumulation but resulted in higher amount of cells in the granulation tissue.

Administration, Topical↗
PubMed1981

Influence of zinc on synthesis and the accumulation of collagen in early granulation tissue.

Chronic zinc deficiency causes a delay of reparative processes. The rate of repair is normalized by the administration of zinc. An acute lowering of the serum zinc level follows trauma. In a previous experimental study, it was demonstrated that the intramuscular administration of zinc beginning before trauma results in an increased collagen accumulation in early granulation tissue. In this study, the rate of collagen synthesis was determined to see if the higher amount of collagen found in early granulation tissue could be explained by increased collagen synthesis. The rate of collagen synthesis was studied by the determination of the incorporation of 14C-L-proline into collagen in vivo and in vitro. No difference was found regarding collagen synthesis in the granulation tissue of rats in the control and zinc treated groups. Specific activity of collagen, a measure of newly synthesized collagen in relation to the total amount of collagen, was found to increase markedly during the observation time. Further, the specific activity was found to be lower in the rats of the zinc treated groups than in the rats of the control groups on days 4 and 5, an indication that, after the administration of zinc there is more earlier synthesized, not labeled, collagen present. A possible explanation is that there is a concomitant synthesis and breakdown of collagen in granulation tissue and that the rate of breakdown is decreased by the administration of zinc.

Animals↗
PubMed1980

The effect of local methylprednisolone on granulation tissue formation. II. Mechanisms of action.

The mechanism of action of a locally applied depot preparation of methylprednisolone on the granulation tissue was studied. Various connective tissue components were analysed in the developing granulation tissue induced by subcutaneously implanted viscose cellulose sponges in rats. Methylprednisolone treatment at the time of sponge implantation reduced the content of both hydroxyproline and hemoglobin and caused a clearly reduced RNA/DNA ratio in the new connective tissue. The total number of cells infiltrating the sponge was not affected by the treatment, but there were significantly fewer lymphocytes, monocytes and macrophages 4 and 7 days post-implantation. In the non-treated sponges there were significantly more fibroblastoid cells, which sticky cells usually died during the releasing procedure. When the corticosteroid was given after the third postoperative day it did not affect the developing granulation tissue. These results indicate that methylprednisolone mainly affects the initial inflammatory phase of granulation tissue formation and wound healing.

Animals↗
PubMed1980

Cell composition of granulation tissue in defibrinogenated rabbits.

The influence of systemic defibrinogenation on cell composition and capillary formation in sponge-induced early granulation tissue was studied in rabbits. The tissue was studied histologically and the content of RNA, DNA and Hb was determined. Inflammatory cells were identified and quantified using histochemical and biochemical techniques. An accumulation of PMN-leucocytes was found after defibrinogenation whereas the amount of fibroblasts and capillaries was reduced.

Afibrinogenemia↗
PubMed1980

Kidney transplantation in patients over 60 years of age.

Between 1972 and the end of 1978 kidney transplantation was performed on 39 patients over 60 years of age. In one case a kidney from a live donor was used. The other patients received cadaver kidneys. Patient and graft survival in this group of patients did not differ from the results obtained with younger age groups. 14 patients have died. The chief reasons for death were cardiac infarction and infection. The mortality rate was no higher among patients over 60 years than among younger groups. The results show that kidney transplantation can be performed successfully on patients of relatively advanced age.

Aged↗
PubMed1980

Diagnostic evaluation of the in situ inflammatory response of renal allograft rejection.

Transplant aspiration cytology (TAC) may be performed daily from human renal allografts without risk to the graft or to the graft recipient. With TAC it is possible to accurately quantitate the onset, type, degree and duration of the inflammatory response of rejection, predict the course of rejection, and on certain occasions also visualise the rejection prior to the appearance of clinical signs. The method also provides a quantitative tool for the assessment of the effects of immunosuppressive and anti-inflammatory drugs on the composition of the in situ inflammatory infiltrate.

Biopsy, Needle↗
PubMed1980

Collagen metabolism in syngeneic aortal vein grafts in the rat.

The sequential changes in hydroxyproline concentration and in vivo 3H-proline incorporation in arterialized grafts of the supradiaphragmatic inferior vena cava have been studied. These grafts were transplanted from one rat to the abdominal aorta of another rat of the same inbred strain, i.e., syngeneic grafts. The hydroxyproline (collagen) concentration decreased to half of its pregraft value one week after the transplantation and thereafter increased again, reaching its peak value 4 weeks after transplantation. The pregraft level of collagen concentration was not reached within the observation period of 12 weeks., The incorporation of 3H-proline increased and reached its peak value one week after transplantation. The values then levelled off and one month after the transplantation were slightly elevated. These results indicate that the reduction of collagen concentration after grafting was due to an increased breakdown, which was compensated by increased collagen synthesis. This probably signifies that the collagen in the vein wall is remodelled as a response to the altered hemodynamic milieu following its insertion to the arterial circulation. The collagen concentration did not reach pregraft level. This is most likely due to a relative increase of ground substance, smooth muscle cells and elastin in the vein wall.

Animals↗
PubMed1980

The effect of local methylprednisolone on granulation tissue formation. 1. Effect on the various granulation tissue components.

The effect of locally administered depot preparation of methylprednisolone on granulation tissue formation in the rat was studied. Various connective tissue components were analysed at different times in implanted viscose cellulose sponges. When the corticosteroid was administered at the time of operation, both the accumulation of collagen and development of vascularity was retarded. Methylprednisolone did not affect the number of white cells infiltrating the sponge nor the sponge content of DNA. This mode of drug administration was shown to have mostly local effects.

Animals↗