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Biomedical subjects

D Kistler

Publications and source records attributed to D Kistler.

31 records · Page 2Linked to original sources
PubMed1989

Temporal resolution in children.

The auditory temporal resolving power of young children was measured using an adaptive forced-choice psychophysical paradigm that was disguised as a video game. 20 children between 3 and 7 years of age and 5 adults were asked to detect the presence of a temporal gap in a burst of half-octave-band noise at band center frequencies of 400 and 2,000 Hz. The minimum detectable gap (gap threshold) was estimated adaptively in 20-trial runs. The mean gap thresholds in the 400-Hz condition were higher for the younger children than for the adults, with the 3-year-old children producing the highest thresholds. Gap thresholds in the 2,000-Hz condition were generally lower than in the 400-Hz condition and showed a similar age effect. All the individual adaptive runs were "adult-like," suggesting that the children were generally attentive to the task during each run. However, the variability of threshold estimates from run to run was substantial, especially in the 3-5-year-old children. Computer simulations suggested that this large within-subjects variability could have resulted from frequent, momentary lapses of attention, which would lead to "guessing" on a substantial portion of the trials.

Attention↗
PubMed1988

A model to reproduce predictable full-thickness burns in an experimental animal.

A standardized, reproducible animal model is a prerequisite to study concepts in the therapy of extensive burn injuries. The development of a new model makes it possible to produce predetermined burn injuries with a set temperature, time, contact pressure, and standard extent of tissue damage. For our studies we chose rats and exposed them to a temperature of 250 degrees C for 20 s and a contact pressure of 500 g/cm2 over various percentages of TBSA (total body surface area). The animals received shock prophylaxis for 3 days postburn and were kept under standardized conditions in a laminar airflow compartment. The temperature was kept at 32 degrees C and the relative humidity at 75 per cent. To reduce bacterial contamination, air was filtered through special bacteria-proof filters. Under these conditions we found burns of approximately 35 per cent TBSA to be sublethal resulting in 80 per cent mortality between days 5 and 7. This model permits the investigator to vary the burned skin area to any required extent for a reproducible study of different concepts of burn therapy.

Animals↗
PubMed1988

Morphological changes of intermingled skin transplants on rats.

Experiments with rats demonstrate that free skin transplants between genetically distinct strains become totally rejected after no longer than 3 weeks. In intermingled skin transplants, however, the autogenic epidermis directly covers the allodermis, which results in a definitively covered wound with a mostly normal skin texture. It seems that during the first phase after the burn the allodermis is accepted as donor skin. In the second phase it becomes covered by the epidermis and surrounded by the connective tissue of the recipient. During this process all structures of ectodermal origin like skin adnexa are rejected. Since for the most part the elastic fibres in the allograft remain unchanged after a successful intermingled skin transplantation, the transplant shows elasticity similar to a mesh autograft, but it is incapable of regenerating skin adnexa. After complete healing cellular and humoral infiltrates, as in the case of immunological rejections, could no longer be detected.

Animals↗
PubMed1984

[Secondary immunodeficiencies following severe skin burns].

Despite of modern fluid resuscitation, electrolyte management and respiratory care techniques 70% of severely burned patients often survive the early posttraumatic phase only to later succumb to septic complications. Acquired deficiencies in host defense mechanisms are largely held responsible for this increase in susceptibility to sepsis. The thermal insult affects the complex interactions of cells of the immune system by generation and release of suppressive mediators which, in turn, either cause defective cellular functions or overstimulation of regulatory pathways of host defense.

Burns↗
PubMed1983

Phagocytic activity of granulocytes and alveolar macrophages after burn injury measured by chemiluminescence.

Despite substantial progress in handling the acute phase, about 50 per cent of all severely burned patients are still subject to lethal infections during the later stages of the burn disease. Such patients frequently succumb to infections by opportunistic bacteria and viruses of normally low virulence indicating that the antiinfectious host defences are severely compromised. The present study was conducted in order to evaluate the effects of severe thermal injury on the two major categories of phagocytic cells, the circulating phagocytes of the blood and the alveolar macrophages as one population of the fixed phagocytes of the reticulo-endothelial system. The cells were isolated from burned and unburned rats. For quantitative assessment of the phagocytic function the chemiluminescence associated with the phagocytosis of opsonized zymosan particles was measured, using luminol as a chemiluminigenic probe. It turned out that as a consequence of the thermal trauma the phagocytic activity as measured by chemiluminescence is reduced in granulocytes as well as in alveolar macrophages.

Animals↗
PubMedDate not supplied

Follow-up results after stent placement in failing arteriovenous shunts: a three-year experience.

Self-expandable endoprostheses were used in 18 failing arteriovenous shunts after unsuccessful balloon dilatation. Technical success was satisfactory with an early patency in 17 of 18 shunts. Thrombosis right after stenting occurred in three shunts but was successfully treated in two. Follow-up history revealed recurrent events of reobstruction due either to stent or shunt stenoses or thrombosis. Restenosis within the stented segment was responsible for reobstruction in about half the cases. Although patency was low with 27% at 18-month follow-up, repeated intervention established a shunt survival rate of 77% at 18-month follow-up. Stent placement in AV shunts is useful for overcoming acute problems of balloon dilatation but does not prevent restenosis.

Angioplasty, Balloon↗
PubMedDate not supplied

Technical aspects and results of percutaneous transluminal angioplasty in Brescia-Cimino dialysis fistulas.

Our experience with percutaneous transluminal angioplasty for treatment of stenoses and occlusions in surgically created arteriovenous fistulas (Brescia-Cimino) is reported. Methodological aspects are emphasized. Forty-nine PTAs were performed in 36 patients, in 3 combined with the use of a vascular metallic endoprosthesis (Wallstent). The initial success rates for stenoses and occlusions were 91% and 77%, respectively. Long stenoses and occlusions (greater than 4 cm) showed significantly worse initial results (55%) as compared to short ones (95%). Of the primarily successfully treated shunts, 90% are still functioning after a mean follow-up time of 8 months. The results indicate that PTA may replace surgical intervention as the primary method for treatment of insufficient flow for internal arteriovenous shunts, provided fresh thrombi are not the cause of the occlusion. Metallic endoprostheses and the use of atherectomy catheters were shown to be a valuable adjunct to classical PTA in selected cases.

Adult↗
PubMedDate not supplied

A computerised machine for the facilitated production of intermingled skin grafts.

The introduction of intermingled allograft/autograft skin grafting in western countries has long been hampered by high costs, due to the personnel requirements to produce this special form of graft. We have solved this problem by designing and constructing a computer-controlled machine, which in one operation punches holes out of strips of allogeneic donor skin and in another cuts fitting islets out of autogenous skin and transfers them into these holes. In comparison to manual preparation, this machine not only accelerates the production of intermingled skin grafts, but it also inserts the islets with superior accuracy, which is very important for the final functional and cosmetic result.

Adult↗
PubMedDate not supplied

Use of Pseudomonas hyperimmunoglobulin to treat septic shock in burn cases.

The progress of 18 episodes of septic shock in nine patients with burn injuries after administration of a Pseudomonas immunoglobulin is presented. In nine instances the septic shock was treated successfully. The mean burn index of these nine patients was 96. In six of the nine patients the septic shock was accompanied by simultaneous inhalation trauma and in six by acute kidney failure. In four cases the sepsis was caused by P. aeruginosa and in five by staphylococci. Despite the different causative agents, successful treatment was possible in these cases. The mean burn index for the four patients who eventually died was 119; all patients in this group were suffering from an inhalation trauma and acute kidney failure requiring dialysis. In these cases even the use of Pseudomonas immunoglobulin had no decisive effect.

Adult↗