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D Kunz

Publications and source records attributed to D Kunz.

100 records · Page 6Linked to original sources
PubMed1983

On the analysis of the cat's pattern recognition system.

The objective of the paper is to determine in abstract terms the algorithms used by the cat detecting simple patterns and to quantify the contributions of the visual areas 17, 18, 19 for this task. The data incorporated in the algorithm are collected from behavioral experiments where the animals had to distinguish between two patterns. The patterns were superimposed with gaussian noise and the detection probability was measured. The resulting model describes pattern recognition in two steps: first extraction of features and second classification. The test of the validity of the model system was to predict the outcome of similar experiments but with different patterns. With the help of the model it is possible to describe the effect of a lesion in parametric form. This in turn gives some hints about the functions of the visual areas 17, 18, 19 for the specific fask, tested in the experiments.

Animals↗
PubMedDate not supplied

Sleep-wake cycle, sleep-related disturbances, and sleep disorders: a chronobiological approach.

There is convincing evidence that the functions of sleep include restoration of brain energy storage and memory consolidation. The circadian timing system (CTS) is involved in the daily variation of almost any physiological and psychological variable evaluated thus far. Disturbances of the CTS can be clinically observed by their influence on the sleep-wake cycle, hormones, body temperature, and locomotor activity. This article reviews the basic mechanisms of circadian rhythm sleep disturbances, names the applicable diagnostic tools and specific therapeutic strategies, and thereby hints at the impact of circadian rhythm sleep disturbance on psychiatric disorders, especially disorders of affect and cognition. In light of the preventive, diagnostic, and therapeutic tools now available, a new round of chronobiological studies in psychiatry seems justified, promising, and necessary.

Brain↗
PubMedDate not supplied

Peritoneal release of TNFalpha and IL-6 after elective colorectal surgery and anastomotic leakage.

The evaluation of postoperative peritoneal drainage fluid tumor necrosis factor (TNF)alpha and interleukin (IL)-6 was studied prospectively over a 7-day period in 25 patients operated on for neoplastic colorectal diseases. In 22 cases, colon or rectum carcinoma was the reason for surgery, and in 3 patients resection was performed because of colonic adenoma. All patients received either an end-to-end colo-colonic or colorectal anastomosis. Of this group, 22 patients were free of complications defined as uneventful postoperative course without any signs of anastomotic leakage until the 14th postoperative day. All of these patients showed a significant rise in peritoneal TNFalpha with maximum on the 7th day during the study period (p <.05). In contrast, peritoneal IL-6 levels remained constant without significant change in time (p >.05). Three patients underwent relaparotomy because of anastomotic leakage. In these patients, peritoneal TNFalpha concentrations showed a rise until the day of operative confirmation of anastomotic leakage. This rise preceded the day of operative confirmation by at least 1 day but did not change significantly in time (p =.59). Peritoneal IL-6 concentrations in patients with anastomotic leakage remained constant and also did not change significantly in time (p =.21). After elective colorectal surgery, neither postoperative abdominal drainage fluid TNFalpha nor IL-6 monitoring is helpful to decide on the need for revision in patients with anastomotic leakage.

Adult↗
PubMedDate not supplied

Expression and functional role of dipeptidyl peptidase IV (CD26) on human natural killer cells.

The expression and functional role of dipeptidyl peptidase IV (DP IV, CD26, EC 3.4.14.5) was studied on human natural killer (NK) cells. Here we show that freshly isolated NK cells do express only low amounts of DP IV. However, after IL-2 stimulation of NK cells (70% purity) surface DP IV expression was significantly increased in a subpopulation (30%) of these cells. Specific DP IV inhibitors (Lys-[Z-(NO2)]-piperidide, Lys-[Z(NO2)]-thiazolidide) and polyclonal antibodies directed against the ectopeptidase suppressed DNA synthesis and cell cycle progression of NK cells. The natural cytotoxic activity of DP IV+ CD56+ cells was found unchanged in comparison to those of DP IV- CD56+ cells. DP IV inhibitors had no effect on the natural cytotoxicity of mononuclear cells. From these data we conclude that DP IV is involved in the regulation of proliferation of NK cells, whereas natural cytotoxicity seems to be regulated independently.

Cell Cycle↗