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P Althaus

Publications and source records attributed to P Althaus.

At least 37 records · Page 2Linked to original sources
PubMed1984

[Hemodynamic effects of an alpha-adrenergic blockade following experimental kidney transplantation].

The experiments were made to determine whether alpha-adrenergic blockade would reverse the vascular spasm in kidney grafts exposed to a warm ischaemia time of 30 min and 24 hr cold storage. Total vascular resistance per unit kidney mass, hematocrit, urinary flow, plasma and urine concentrations of creatinine, [Na+] and [K+], blood gases, renal O2 consumption and acid-base balance were studied in 21 anaesthetized dogs before and after kidney transplantation and administration of the blocking agent. Seven dogs were used to evaluate the effects of warm and cold ischemic stress on graft circulation and function without blockade (group 1). In the remaining dogs the blockade was induced by infusion of phentolamine (100 micrograms/kg/min) over 20 min. Controlled normal level of blood pressure was maintained throughout the experiments by infusion of 10% dextran 40 in saline (group 2) or by blood transfusion (group 3). Despite of interruption of neural pathways phentolamine induced a marked decrease in graft vascular resistance ranging from 89.2% +/- 5.9 (group 2) to 78.5% +/- 6.7 (group 3) in relation to the difference between the resistances before and after transplantation. In contrast, the decrease in vascular resistance of untreated grafts amounted only to 10.7% +/- 7.8 within a recirculation period of 4 1/2 hours. The increased renal blood flow following the blockade was associated with a considerable rise in urine flow and urinary excretion of creatinine, [Na+] and [K+] and a significant decrease in their plasma levels. The reduced O2 utilization by the grafts and the metabolic acidosis remained unchanged. These results indicate that phentolamine caused an effective suppression of vasoconstriction in kidney grafts exposed to warm ischemia and cold storage reflecting the intensive sympathetic activity under these conditions. Although the recovery of ischemic damaged tubular cells in this way was not acutely effected, the pharmacological enhancement of the cortical and medullary blood supply in the early posttransplant period may be helpful for overcoming the acute tubular necrosis and for preventing the development of hypertension due to the augmented release of vasodepressive medullary hormones.

Animals↗
PubMed1984

[A model of chronic percutaneous blood sampling during subcutaneous transposition of the renal vein in heterotopic kidney transplants in the dog].

The operative techniques of subcutaneous transposition of the renal vein in the heterotopic canine kidney transplant model and of the carotid artery are described in detail. Following this procedure a chronic percutaneous access of the renal vein and carotid artery for investigations of the kidney transplant metabolism and blood pressure measurement respectively is possible.

Animals↗
PubMed1983

Microvascular surgery in experimental and clinical kidney transplantation.

An improved microsurgical technique for orthotopic rat kidney transplantation is described in detail. (1) End-to-end anastomosis of renal arteries with 7-8 interrupted 10-0 sutures. (2) End-to-end anastomosis of renal veins with 2 continuous semicircular 10-0 sutures. (3) Non-splinted end-to-end ureteric anastomosis with 4 interrupted full-thickness 11-0 sutures. (4) Simultaneous bilateral nephrectomy. Seventy transplantations were analysed. No failure due to complications of the vascular anastomoses occurred. The ureteric anastomoses were complicated by stenosis in only 5 animals (7%). The operation times for vascular anastomoses were 20 (15-24) minutes and for complete transplantation 50 (45-60) minutes. This technique seems to be less time consuming than other methods. Our method has produced a success rate of 93% with well standardized and reproducible organ quality. Preliminary clinical experiences with extracorporeal microvascular reconstruction in 4 cases of injured small polar kidney allograft arteries support the continued application in appropriate situations to increase the number of suitable donor kidneys.

Animals↗
PubMed1983

[Kidney transplantation in the rat--heterotopic or orthotopic?].

Kidney transplantation in the rat is a model frequently used in transplantation research. The advantages and disadvantages of both the heterotopic and orthotopic approach were compared. The orthotopic model with end-to-end anastomoses of the renal vessels and nonsplinted end-to-end ureteric anastomosis was found to be superior to the heterotopic technique in respect of lower frequency of complications and short operation times. Orthotopic rat kidney transplantation is an optimum approach and further use is possible and necessary.

Animals↗
PubMed1983

[Modification of the development of infant kidneys by homotransplantation to adult recipients. Hemodynamic and morphologic study on the minipig].

To study the development or absence of a compensatory hypertrophy and early maturity of suckling kidneys after allotransplantation into adult recipients, MLC histocompatible piglet kidneys of the minipig were transplanted en bloc into the binephrectomized mother. As a result, the significant higher renal perfusion pressure in the circulation of the sow in comparison with the lower arterial pressure in the piglet organism caused a autoregulatoric increase in the blood flow of the infantile kidneys following the transplantation. After 1-2 weeks, the transplants showed an abnormal weight increase attributable to the prematurity associated with glomerular and tubular hypertrophy as well as to rejection-induced or unspecific inflammatory infiltrations. The functional effectiveness of the pediatric grafts were limited especially by the body weight of the recipients and by the rapidly occurring deficit of nephrons in consequence of infection and/or rejection. As a survival period of 45 days was reached in one case, the recipient shows approximately physiological creatinine concentrations in serum.

Animals↗
PubMed1983

[The rat as a training model for microvascular surgery. Methods and results].

Before the clinical application of microvascular surgery the experimental training is necessary. The techniques of end-to-end anastomosis of femoral artery and vein and groin flap autotransplantation are described in detail on the rat model and results are presented. These techniques seems to be suitable for persons still learning without much experience.

Animals↗
PubMed1983

[The laser in urology].

The clinical application of laser in urology has become possible after intensive experimental work. Because of necessary facilities and high costs connected with, the use of laser can be recommended for high specialised medical institutions. At the present time only Neodym-YAG- and Argon-laser meet all the urologic requirements. The CO2-laser is restricted for broad application. Actually tumours of the bladder, urethra, and penis are the fields for laser-application. Treatment of urethral strictures with laser-irradiation seems to be successful too. The photosensitization could being break-through in treatment of superficial tumours.

Female↗
PubMed1983

[Problems of photo-documentation in microsurgery].

Photomicrography through the operating microscope requires considerable attention to detail. All the details which are essential for obtaining good photomicrographs for documentation and publication are described.

Animals↗
PubMed1982

Orthotopic kidney transplantation in the rat with non-splinted end-to-end ureteric anastomosis: details of a technique.

A detailed description is presented of an improved technique of orthotopic rat kidney transplantation with end-to-end anastomoses of the renal vessels, non-splinted end-to-end ureteric anastomosis and simultaneous bilateral nephrectomy. Forty-four consecutive transplantations are analysed. No failure due to complications of the vascular anastomoses occurred. The ureteric anastomoses were followed by stenosis in only two cases (5%), one of which was reconstructed. The operation times for the vascular anastomoses were 16-24 min, with an average of 20 min, and for complete transplantation 50 min. Therefore, our method seems to be less time consuming than other common techniques of renal transplantation. The technique described has produced a success rate of 95% and guarantees a standardised and reproducible organ quality.

Animals↗
PubMed1982

[Transplantation of the kidneys from newborn donors, using the Mini-Lewe minipig as a model].

The importance of kidneys from newborn donors in transplantation has not been clearly defined. The purpose of this study was to investigate the degree of morphological and functional adaptation of the newborn kidney in an adult recipient. 7 MLS-matched kidneys from Lewe minipig puppies (age: 3-4 weeks) had been transplanted en bloc to their mothers with immediately bilateral nephrectomy. Preliminary results suggested that arterial vasculature and blood supply are the limiting factors in adaptation of newborn donor kidneys in adult recipients.

Animals↗
PubMed1981

[Experimental and clinical use of microsurgery in urology].

Application of microsurgery in experimental and clinical urology is reviewed. A summary of the literature and own preliminary results are presented, especially the model of kidney transplantation in the rat and the treatment of male infertility due to obstructive azoospermia. The extended use of microsurgery in urology is possible and necessary.

Animals↗
PubMed1981

[Possibilities and problems in the transplantation of kidneys from newborn donors using the minipig as a model].

The importance of kidneys from newborn donors in transplantation has not been clearly defined. The purpose of this study was to investigate the degree of morphological and functional adaptation of the newborn kidney in an adult recipient. 7 MLS-matched kidneys from LEWE minipig puppies (age 3-4 weeks) had been transplanted en bloc to their mothers with immediately bilateral nephrectomy. Preliminary results suggested that arterial vasculature and blood supply are limiting factors in adaption of newborn donor kidneys in adult recipient.

Animals↗
PubMed1980

[Arteriovenous access for hemodialysis by vascular transplants].

Indications, surgical technic, late results and complications after creation of vascular accesses for chronic hemodialysis with vascular grafts are described. A fistula in the upper arm between the end of the relocated basilic vein and brachial artery most closely satisfied criteria for an vascular access. The autogenous saphenous vein was found to be an unsuitable arterio-venous fistula for chronic dialysis. Exposed polytetrafluroethylene (PTFE) can be used as a subcutaneous arteriovenous conduit if suitable vessels have been exhausted.

Arteriovenous Shunt, Surgical↗
PubMed1979

Gas exchange, pulmonary mechanics and haemodynamics in adult respiratory distress syndrome: experimental results in Lewe miniature pigs.

Adult respiratory distress syndrome (ARDS) is a common medical emergency in respiratory care complicating a great variety of traumas and diseases. An animal model from Lewe miniature pigs has been developed to study the ARDS under standardized conditions; it is based on aspiration pneumonitis, a disorder often observed in ARDS, injuring the lung alveolar surfactant system. The experimental study was conducted under neuroleptanalgesia. ARDS was produced by intratracheal application of hydrochloric acid (0.2 mol/l) in an amount of 1.0 ml/kg body wt. The animals were ventilated automatically by a standardized ventilatory pattern in IPP mode. In all animals the time course of oxygenation ratio (Pa,O2/F1O2), arterial CO2 tension (Pa,CO2), ratio of alveolo--arterial oxygen tension difference to inspired oxygen fraction (Aa,DO2/F1O2), oxygen exchange ratio ((AaDO2/Pa,O2), lung compliance (CL), inspiratory airway resistance (RrsI), dead space ratio VD/VT), pulmonary artery pressure (PAP) and systemic blood pressure were studied. Changes in quasi-static volume--pressure curves, percentage change in lung water content and gross pathological finding were used to integrate the findings into a system of pathophysiological changes in ARDS. The animal group to which hydrochloric acid was administered shows severe pulmonary distress leading to death within 3.5--7.5 h. No significant changes in the measured parameters could be observed in the control group over a 14 h period. The results suggest that aspiration pneumonitis in Lewe miniature pigs is very suitable to investigate various problems in pathogenesis of ARDS. The model provides reproducible results which correlate very well with findings in different ARDS states. The models serves both to compare clinical states and to search for newer therapeutic manoeuvres.

Animals↗
PubMed1979

Effect of high-dose prednisone on renal hemodynamics of normal and transplanted dog kidneys.

The effect of prednisone therapy on renal hemodynamics was studied in normal, autotransplanted as well as homotransplanted dog kidneys. After intravenous administration of prednisone (8 and 16 mg/kg/min) the total blood flow decreased and vascular resistance increased significantly. This effect was more pronounced if the drug was directly injected into the arteria renalis. The same changes were observed in autotransplanted and homotransplanted kidneys and in kidneys in rejection. Our results suggest that high dosage of prednisone decreases the renal blood flow and this adverse effect has to be considered in the therapy. The administration of the drug directly into the arteria renalis may have to be avoided.

Animals↗