Search PubMed⌕ Search

Biomedical subjects

W Brendel

Publications and source records attributed to W Brendel.

At least 91 records · Page 5Linked to original sources
PubMed1985

[Animal experiment studies on hemodynamics following partial and total blood exchange with a pyridoxalated polyhemoglobin solution].

The effects of a pyridoxalated polyhaemoglobin (SFH-PLP)n-solution on haemodynamics were investigated in a model of partial (hct = 12%) and total blood exchange (hct less than 1%) in 7 dogs. Partial blood exchange resulted in a slight increase in right atrial pressure (RAP) and pulmonary capillary wedge pressure (PCWP) and in a marked decrease in heart rate (HR). Cardiac output (CO) did not increase as would be expected from haemodilution. After total blood exchange, arterial pressure, HR, RAP, PCWP and CO were unchanged compared to the pre-exchange values during the 90 minutes of observation. However, pronounced pulmonary vasoconstriction was observed in 4 dogs. The beneficial effects on haemodynamics are due to the long intravascular persistance of the polymerized haemoglobin molecules (plasma half-disappearance time = 36 hours) and the addition of albumin supplying a sufficient colloid-osmotic pressure of the solution. These characteristics and the good oxygen unloading capacity of the pyridoxalated polyhaemoglobin resulted in longterm survival of three dogs. These results demonstrate a better haemodynamic efficacy of the (SFH-PLP)n-solution compared to previous investigations with unmodified haemoglobin solutions. However, there are still many problems, which have to be clarified prior to its clinical application.

Animals↗
PubMed1985

[Allogeneic lymph vessel transplantations in the early phase].

Syngeneic and allogeneic grafts of segments of the thoracic duct from rats were investigated in the first fifteen days after transplantation. The patency rate--evaluated by the passage of blue dye--of the allogeneic transplants was almost equal to that seen in the syngeneic grafting. By direct exploration there were no changes to be seen in the syngeneic and allogeneic transplants. Investigations by electron microscopy showed no major reactions to the syngeneic grafts during the observation time: The endothelium always was completely detectable and the subendothelial layer of collagen fibrils was not dislocated. By contrast, the allogeneic transplants showed considerable alterations as disintegration of the collagen fibrils and a partial loss of endothelium occurred after eight to ten days. After fifteen days, however, the formation of a neointima could be demonstrated. Despite the observed alterations there was no loss of function in the allogeneic transplants.

Animals↗
PubMed1985

[Cellular mechanisms in graft rejection of peripheral nerve transplants].

Allogeneic nerve specimens (sciatic nerve) were transplanted in rats. Cyclosporin A was used as an immunosuppressive agent. Under this treatment reinnervation occurred. Without treatment, nerve grafts were rejected. In order to monitor the acute cellular rejection, the nerve grafts were surrounded by a silicon tube. The perineural exudate and the mononuclear cells contained in it were aspirated at three day intervals by fine needle aspiration. Exact analysis of the mononuclear cells involved in the rejection mechanism and their degree of activation could in future provide a tool that allows control of nerve graft rejection and estimation of the effect of immunosuppressive treatment.

Animals↗
PubMed1985

[Experimental studies on the regeneration capability and prognosis of hydronephrosis].

There are conflicting opinions regarding the ability of kidneys to return to normal functioning following removal of an obstruction. Opinions also differ on the precision of radioactive iodine for the measurement of functional ability in obstructed kidneys. We tried to assess the value of nuclear medical methods in comparison to the classical physiological clearance methods. Furthermore, we tried to answer the following questions: how long can an obstruction be present before total recovery becomes impossible and when is it no longer worthwhile to perform conservative surgery?

Animals↗
PubMed1984

Fine needle aspiration cytology of the spleen of tumor bearing mice.

Fine needle aspiration cytology (FNAC) of the spleen was performed in 10 tumor bearing mice. The vascularized spleens were mobilized and re-located under the skin in order to facilitate fine needle biopsy (FNB). Samples of spleen cells thus obtained were studied and the lymphoid cells characterized and counted according to morphology. Owing to a relative decrease in numbers of lymphocytes during tumor growth a very marked intrasplenic increase in numbers of granulocytes was observed. The splenograms of a mouse rejecting the tumor were different from those of tumor bearing mice. FNAC of the spleen is a reliable method for monitoring immunocompetence in individual tumor bearing animals.

Animals↗
PubMed1984

Spleen transplantation in the dog as a model for studying immunological feedback reactions.

Modification of the immune response towards the generation of suppressor T cells can be attained using experimental designs promoting immunological feedback mechanisms. Those studies have been carried out in defined inbred animal systems. With respect to the great importance for organ transplantation, an in vivo model using larger outbred animals was developed in order to study such feedback reactions. The following experimental design was used: (1) allogeneic spleen transplantation in the dog; (2) autologous retransplantation of this spleen together with an allogeneic kidney transplantation to the former donor of the spleen after a period of 2-4 days. Although full immunological activity of the transplanted as well as the retransplanted spleen was demonstrated, rejection of the kidney occurred in a fashion identical to that observed in control animals.

Animals↗
PubMed1984

Infrared contact coagulation: a new approach for local hyperthermic therapy of solid animal tumors.

Infrared contact coagulation (ICC) was evaluated in 3 different tumor models. 56-94% of all tumor-bearing rats, hamsters or mice were cured by ICC, whereas 100% of the controls died. The possibility that long-lasting immunological resistance might develop against the tumor after ICC was investigated by repeated tumor challenge. Cytotoxicity against tumor cells of host thymocytes and splenocytes following ICC was demonstrated in a Winn assay. The production of a mainly T-cell-dependent immune response could be due to ICC-induced antigenic changes in the tumor cells.

Animals↗
PubMed1984

Hypoxic pulmonary vasoconstriction and endogenous prostaglandin (PG) and thromboxane (TX) release in anesthetized pigs.

Products of the arachidonate cascade are known to be released from pulmonary tissue in normal and abnormal states, contributing to the regulation of pulmonary vascular resistance. To what extent hypoxic pulmonary vasoconstriction is affected by prostaglandin imbalances is still controversial. To evaluate PG and TX release, we measured plasma levels of TXA2, PGI2, PGF2a, and 13,14-dihydro-15-keto-PGF2a in healthy pigs undergoing normobaric hypoxic ventilation. Plasma levels of TXA2, PGI2, and PGF2a did not change during 10 minutes of hypoxia, whereas 13,14-dihydro-15-keto-PGF2a, the stable metabolite of PGF2a, was significantly elevated after 2, 5 and 10 minutes. Hemodynamic parameters showed an increase in heart rate and pulmonary vascular resistance. Our results suggest that alveolar hypoxia releases PGF2a from lung tissue, being rapidly metabolized to 13,14-dihydro-15-keto-PGF2a and that prostaglandins, at least in part, contribute to hypoxic pulmonary vasoconstriction.

Anesthesia, General↗
PubMed1983

[Immunologic reactions following heart transplantation and their detection].

Transplantation antigens of the major histocompatibility complex are able to stimulate the rejection of the graft. Class I and class II antigens presented by dendritic cells to the host macrophages are found on parenchymal cells (class I) or combined on all passenger leucocytes. Humoral factors like interleukin 1 produced by the macrophages activate the helper-lymphocyte subpopulation. The cytotoxic effector cells but also antibody producing B-cells receive their signal (interleukin 2) from the helper cells. Cellular and humoral mechanisms attack the vascular endothelium and the endocard first. Typical perivascular infiltrates or antibodies on the sarcolemm of myocard fibres and the intima herald the two types of rejection. The activated lymphocytes and their blast forms recirculate in various amounts in the peripheral blood, reflecting the severity of the event. Hematological evaluation including differentiation of lymphocyte subsets by monoclonal antibodies according to their phenotype seem to be a tool to recognize these mechanisms at an early stage. It is suggested that the optimal therapy and the necessary biopsy can be adjusted even more precisely using this immunological monitoring.

Antibody Formation↗
PubMed1983

[A new statistical approach in the search of essential pharmacophoric structures].

The first step of the method consists of a statistical test by which are found those fragments which are represented with higher frequency in a series of active compounds compared to the entirety of all organic compounds. By means of the same procedure it is established in the second step which of these fragments correlate to each other. The third step is the establishment and stepwise generalization of the essential pharmacophoric structures by intellectual combination of the fragments above average and the correlated ones. The method is outlined with a series of 353 antiphlogistically effective compounds. Thus, five essential pharmacophoric structures had been determined. 278 out of these 353 compounds had been correlated to these structures.

Anti-Inflammatory Agents, Non-Steroidal↗