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Biomedical subjects

W Zingg

Publications and source records attributed to W Zingg.

105 records · Page 6Linked to original sources
PubMed1965

The effect of methandrostenolone on nitrogen excretion following open-heart surgery.

An attempt was made to assess the effect of an anabolic hormone in the postoperative phase. Methandrostenolone (Danabol) was given to groups of adults and children undergoing open-heart surgery, and the results were compared with those obtained in control groups. No difference in the clinical picture could be found between the treated and the untreated groups, or in the total amount of nitrogen excreted during six days following the operation. In both treated groups the urinary volume was increased, resulting in a decreased urinary nitrogen concentration.

Adult↗
PubMedDate not supplied

Determination of the surface tension of biological cells using the freezing front technique.

The freezing front technique for solid surface tension measurements was used to obtain the surface tensions of glutaraldehyde-fixed human erythrocytes, and fresh human lymphocytes and granulocytes in aqueous media. The results agree well with the values obtained by other methods and indicate that the freezing front technique is sufficiently sensitive to detect small differences (of the order of 0.1 ergs/cm2) in surface tension. This property, along with a number of applications for which it is uniquely suited, makes the freezing front technique an important new approach to the measurement of the surface tensions of biological cells and of small particles in general.

Cell Membrane↗
PubMedDate not supplied

Computer diagnosis of skin disease: system design and preliminary results.

A system for computer-assisted diagnosis of dermatological disease is described. This is an 'expert system' whose knowledge base has been prepared with the aid of a dermatological specialist. The user enters the key elements of the patient's disease history and physical examination into the computer. The computer then returns a summary of the patient's medical record, and a differential diagnosis. The rules of operation by which a given diagnosis was included or rejected is accessible to the user. The system is currently being evaluated in a large dermatology clinic. Preliminary evaluation of the accuracy of diagnosis by the computer indicates that while it nearly always includes the correct diagnosis in its differential diagnosis (94% of cases), it frequently also includes diseases thought to be inappropriate (34% of diseases listed).

Diagnosis, Computer-Assisted↗
PubMedDate not supplied

Maintenance of normoglycemia in pancreatectomized dogs with a controlled release micropump.

A diffusion-based insulin micropump was capable of sustaining normoglycemia in diabetic, pancreatectomized dogs for as long as 10 months. Basal insulin delivery was provided by diffusion into the peritoneal cavity from the insulin reservoir across a silicone rubber porous outlet, while the delivery of insulin was augmented for 35 minutes at mealtimes by repeated squeezing of a polyurethane foam disk; the latter was initiated 15 minutes prior to the start of the meal. In the best implant, which functioned for more than 10 months before it was deliberately terminated, the mean glucose level was 126 +/- 24.7 mg/dl (+/- SD) and the mean Schlichtkrull M value was 2.8. In the other three implants, the mean and standard deviations were a little higher. The basal insulin supply was sufficient to restore normoglycemia each morning, while the augmented supply substantially reduced the size of the postprandial period of hyperglycemia. Over the 10 month period studied, the maximum concentration was 150 mg/dl approximately 6 hours after the beginning of the meal, based on the mean of the approximately 200 glucose profiles determined for this implant. Despite this ability to maintain reasonable normoglycemic profiles for long periods, the pump performance deteriorated over this time period, presumably from a tissue reaction to the porous outlet of the implant. This deterioration was evident in the higher levels of glycemia associated with an insulin delivery program that was maintained for too long or in the need to readjust the program to achieve similar levels of glycemia. Nevertheless, the biocompatibility and efficacy of the controlled release micropump demonstrates the feasibility of this approach.

Animals↗
PubMedDate not supplied

Protein and platelet interactions with polymer surfaces.

An attempt is made to develop an understanding of the basic mechanism governing the interaction of the major blood proteins and cells with polymer surfaces with a focus on thermodynamic approach. It is believed that such investigations may be helpful to provide a rational for the design of suitable cardiovascular prosthetic materials and to choose materials in such a way that adsorption of certain proteins eg. 'fibrinogen' is thermodynamically unfavourable compared to adsorption of other proteins eg. 'albumin'.

Adsorption↗
PubMedDate not supplied

An all-plastic double-lumen catheter for continuous blood sampling.

The all-plastic double-lumen catheter described in this paper represents a significant improvement over previously reported catheters. It is used routinely for continuous blood withdrawal in two clinical investigation units and one experimental laboratory in Toronto. No experiments have been terminated due to catheter failure or clot formation and no maximum time limit of its use has been established. In clinical use with adult patients (4), the outer cannula has been kept open overnight with a slow saline drip after 18 hours of use. The same cannula has then been reused the next day for another 16 hours with a new adapter precut to size. Its design enzures that: (1) heparin is mixed with the blood at the site of blood sampling. (2) Blood is never brought into contact with glass or metal. (3) The blood channel is a uniform polyethylene tube with no discontinuities and no junctions, except where it is introduced into the peristaltic pump tube. The overall manufacturing process is simple, and percutaneous insertion is straightforward. Through its use, clotting in the blood withdrawal line and thrombus formations in the blood analyzer are no longer problems to limit the use of techniques requiring continuous blood withdrawal.

Blood Specimen Collection↗
PubMedDate not supplied

The force of detachment of endothelial cells from different solid surfaces.

With the use of a technique based on the detachment of single cells by suctioning of the cells with a glass micropipette, the authors studied human endothelial cell adhesion on 4 different surfaces (Fluorocarbon FC 721, polyester, nylon, glass) versus time of contact in phosphate buffered solution and a complete culture medium. It was observed that the force of detachment from solid surfaces of endothelial cells increases significantly with time and with increasing substrate surface tension in PBS and decreasing substrate surface tension in complete culture medium. This dependence of cell-fiber interactions with surface tension of the fibers demonstrates that cell adhesion in the authors' experimental conditions in primarily controlled by surface tension.

Biomechanical Phenomena↗
PubMedDate not supplied

A chronic arteriovenous shunt for the testing of biomaterials and devices in dogs.

A technique is described for an extracorporeal arteriovenous shunt in dogs which allows the testing of biomaterials in the shunt for several months in the same animal. The details of the preparation of the tubes and of the surgical technique are given. In contrast to other techniques, encircling ligatures are not placed around the cannulated blood vessels.

Animals↗
PubMedDate not supplied

The effect of oxygen tension and mechanical stress on the outcome of fresh autogenous tissue implants in the canine blood stream.

Fresh autogenous collagenous tissue grafts were implanted in the lumen of the aorta, vena cava, pulmonary artery and vein of thirty dogs. Grafts were studied at varying periods postimplantation. Grafts in the latter three situations were vascularized and absorbed early and were replaced by host fibrous tissue; whereas grafts in the aorta remained unabsorbed because of lack of vascularization. We conclude that fresh autogenous fibrous tissue is not a good material for the reconstruction of the right ventricular outflow tract with a competent valve.

Animals↗