Biomedical subjects

K Götz

Publications and source records attributed to K Götz.

16 recordsLinked to original sources

PubMed2006

Radiological findings in individuals at high risk of psychosis.

OBJECTIVE: To assess the prevalence of radiological magnetic resonance imaging (MRI) findings in individuals at high risk of schizophrenia. METHODS: MRI scans from individuals at high risk of schizophrenia (HR; n = 37) were assessed by a radiologist blind to group status and compared with scans from patients with first episode psychosis (FE; n = 30), depressive controls (DC; n = 17), and healthy controls (HC; n = 26). RESULTS: There was a significantly higher proportion of radiological findings in individuals at high risk of schizophrenia (35%) and patients with first-episode psychosis (40%) than in patients with depression (18%) or healthy controls (12%). These differences were specific to findings regarded as potentially clinically significant as opposed to normal variants; however, there was no indication for medical treatment. CONCLUSIONS: The results suggest that a large proportion of those at high risk of psychosis have radiological findings on MRI scanning, and that the prevalence of radiological findings in this group is similar to that in patients with first episode psychosis.

Adolescent↗

PubMed2002

Estimation of x ray overexposure in a childhood leukaemia cluster by means of chromosome aberration analysis.

Only multiple X ray diagnostics could be identified as a common risk factor in a leukaemia cluster that appeared between 1985-1989 in the municipality of Sittensen in northern Germany. In order to judge if the effect could be explained by irradiation dose, estimates were done in two of the leukaemia cases and seven former patients of a practice where some of the leukaemia cases had been treated for orthopaedic reasons. The methods used for the reconstruction of doses were physical simulation and biological dosimetry by dicentric chromosomes in peripheral lymphocytes. Compared to the Bremen laboratory control the mean frequency of dicentric chromosomes in the lymphocytes of the seven volunteers was significantly elevated. An overexposure of about 12-fold could be derived compared to state of the art X raying. At least two cases of the leukaemia cluster in Sittensen can therefore be correlated to an overexposure by diagnostic X rays.

Acute Disease↗

PubMed2001

Task-specific association of photoreceptor systems and steering parameters in Drosophila.

Visual motion processing enables moving fruit flies to stabilize their course and altitude and to approach selected objects. Earlier attempts to identify task-specific pathways between two photoreceptor systems (peripheral retinula cells 1-6, and central retinula cells 7 + 8) and three steering parameters (wingstroke asymmetry, abdomen deflection, hindleg deflection) attributed course control and object fixation to peripheral retinula cells 1-6-mediated simultaneous reactions of these parameters. The present investigation includes first results from fixed flying or freely walking ninaE17 mutants which cannot synthesize the peripheral retinula cells 1-6 photoreceptor-specific opsin. Retention of about 12% of the normal course control and about 58% of the object fixation in these flies suggests partial input sharing for both responses and, possibly, a specialization for large-field (peripheral retinula cells 1-6) and small-field (central retinula cells 7 + 8) motion. Such signals must be combined to perceive relative motion between an object and its background. The combining links found in larger species might explain a previously neglected interdependence of course control and object fixation in Drosophila. -Output decomposition revealed an unexpected orchestration of steering. Wingstroke asymmetry and abdomen deflection do not contribute in fixed proportions to the yaw torque of the flight system. Different steering modes seem to be selected according to their actual efficiency under closed-loop conditions and to the degree of intended turning. An easy experimental access to abdominal steering is introduced.

Animals↗

PubMed2000

Role of potassium channels in the control of renin secretion from isolated perfused rat kidneys.

This study aimed to assess the relevance of specific potassium channels, such as inwardly or outwardly rectifying and calcium-regulated potassium channels, to the control of renin secretion. For this purpose we examined the effects of the K+ channel blockers 4-aminopyridine (1 mmol/l), barium (100 micromol/l), tetraethylammonium (2 mmol/l) and apamin (200 nmol/l) on basal renin secretion, on renin secretion stimulated by isoproterenol (10 nmol/l) and on the inhibition of renin secretion by angiotensin II (100-300 pmol/l) in the isolated rat kidney perfused at constant pressure. Whilst all four K+ channel blockers increased renal vascular resistance, only 4-aminopyridine and barium attenuated isoproterenol-stimulated renin secretion in an additive fashion and augmented the inhibitory effect of angiotensin II. These effects of K+ channel blockers were not changed by the L-type calcium channel blocker amlodipine (5 pmol/l), indicating that their effects on renin secretion are not due to voltage-operated calcium influx. Our data, moreover, suggest that potassium efflux from renal juxtaglomerular cells is not important for the inhibitory action of angiotensin II on renin secretion. As a consequence it appears that the membrane potential of renal juxtaglomerular cells per se is relevant to renin secretion such that membrane depolarization inhibits the exocytosis of renin whilst hyperpolarization favors renin secretion. By their activity, potassium channels can contribute to membrane hyperpolarization and thus facilitate renin secretion.

4-Aminopyridine↗

PubMed1993

Which factor mediates reno-renal control of renin gene expression?

OBJECTIVE: To obtain information about possible pathways mediating the suppression of renin gene expression in the contralateral kidneys of stenosed kidneys. DESIGN: The effects of unilateral renal denervation and of treatment with an angiotensin II antagonist (losartan) on renal renin gene expression were examined in a two-kidney, one-clip model. METHODS: Renal renin messenger RNA levels, plasma renin activity, blood pressure and kidney weights were monitored over 10 days in adult male Sprague-Dawley rats with various unilateral reductions of renal blood flow achieved with silver clips of 0.2, 0.3 and 0.4 mm inner diameter. RESULTS: With all the clip sizes used, renin messenger RNA levels increased transiently in the clipped kidneys, the time course and the magnitude of the increase being dependent on the degree of flow reduction. In the contralateral kidneys clipping caused sustained decreases in renin messenger RNA to levels proportional to the clip size. The suppression of renin gene expression in the contralateral kidneys was not related to compensatory growth of the organs nor to changes in plasma renin activity or arterial pressure. Unilateral denervation of the kidney before clipping had no influence on the characteristic increase and decrease in renin messenger RNA in the stenosed and contralateral kidneys, respectively. Treatment of the rats with losartan led to fourfold increases in renal renin messenger RNA levels and to sixfold increases in plasma renin activity in control rats. A 0.3-mm clip did not further increase renin messenger RNA or plasma renin activity in losartan-treated rats but again led to suppression of renin messenger RNA in the contralateral kidney to 50% of the levels found in the clipped kidneys. CONCLUSIONS: The results suggest that the suppression of renin gene expression in the contralateral kidneys of stenosed kidneys is not due to compensatory renal growth nor mediated by systemic blood pressure, angiotensin II AT1 receptors or renal nerves. We therefore hypothesize that kidneys with reduced perfusion release a humoral factor that acts as a potent inhibitor of renin gene expression.

Angiotensin Receptor Antagonists↗

PubMed1991

Direct correlation of parvalbumin levels with myosin isoforms and succinate dehydrogenase activity on frozen sections of rodent muscle.

Parvalbumin (PV) is a soluble Ca++ binding protein which is particularly concentrated in fast muscles of rodents. We have developed a new protocol to fix frozen sections of muscle by formaldehyde vapor, which enabled us to immunochemically stain serial frozen sections for PV. Fiber types were defined on the basis of myosin ATPase stability, and of isomyosins identified by a variety of antibodies because ATPase stability alone yielded ambiguous results in the mouse. Slow Type I fibers in mouse and rat were devoid of PV and had intermediate to high SDH levels. Fast fiber subtypes IIA, IIB, and IIX-like were defined in the mouse on the basis of the similarity of their myosin heavy chain immunoreactivity to these types in the rat. The soleus muscle was usually PV negative, but a small population of strongly PV-positive IIX-like fibers was present in the mouse. In mouse fast muscle, small diameter IIA fibers were PV negative with high SDH activity. In both mouse and rat, PV reactivities of IIB and IIX fibers were higher than those of IIA and I, whereas SDH levels of IIA, IIX, and I fibers were higher than those of IIB. Thus, PV content correlated with the type of myosin ATPase but not with SDH levels. The method described for immunocytochemistry of PV may be applicable to other highly soluble proteins.

Animals↗

PubMed1975

Color preferences of art students: surface colors: II.

In a previous study (Götz & Götz, 1974b) the preferences of 14 surface colors were analyzed. While this set contained only one red, one blue, one yellow, etc., the color set of the present investigation was extended, and the preferences of 5 different reds, blues, yellow, etc. were analyzed. Between the five variations of red and yellow, respectively, the greatest affective differences were found, while the opposite was true for the 5 oranges, pinks, and grays. The most preferred colors are 2 reds, 2 blues, and 2 yellows; least preferred are a greenish yellow, a penetrating red-violet, and all 5 pinks. Significant sex differences were found for 8 colors.

Adult↗

PubMed1975

Color preferences, extraversion, and neuroticism of art students.

Color preferences of 190 art students (Götz & Götz, 1974, 1975) were compared with the corresponding scores on extraversion (E) and neuroticism (N). It was found that the preferences of a group of 27 highly gifted young artists were different from preferences of average and less gifted Ss who had little or no artistic practice. In the latter group extraverts and ambiverts mainly preferred primary and secondary colors (light clear and dark clear tones included), while introverts preferred tertiary colors (earth colors) and achromatics. However, in the group of highly gifted Ss no significant differences between positive and negative rankings in both color categories were found. Neuroticism had no effect on color preferences; this holds for introverts and extraverts and for each single color.

Adult↗

PubMed1974