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Biomedical subjects

H Stumpf

Publications and source records attributed to H Stumpf.

At least 19 recordsLinked to original sources
PubMed1995

The DNA binding activity of the liver transcription factors LFB1 (HNF1) and HNF4 varies coordinately in rat hepatocellular carcinoma.

As renal cell carcinomas are characterized by the disappearance of the transcription factor LFB1, which is known to be primarily involved in gene regulation in the liver, we have measured the presence of LFB1 in rat hepatocellular carcinomas induced by diethylnitrosamine. The level of LFB1 binding activity in adenoid-cystic as well as trabecular tumours shows some variation and may either be lower or higher than in the non-tumorous tissue. The amount of LFB1 binding activity correlates with the binding activity of HNF4, a transcription factor reported to stimulate LFB1 expression. As the levels of LFB1 and HNF4 binding activity differ extensively in various hepatocellular carcinomas, it is unlikely that these transcription factors play a general role in hepatocarcinogenesis. This is in contrast to renal carcinogenesis where a dramatic loss of LFB1 is a consistent feature.

Albumins↗
PubMed1995

Responses of single neurons in amygdala to interoceptive and exteroceptive stimuli in conscious cats.

The amygdala is critical for behavioral arousal and must therefore integrate a wide variety of inputs. We examined sensory inputs and the degree of convergence to single neurons in the amygdala in conscious freely moving cats. A pressor stimulus elicited responses, predominantly inhibitory, in one-half of the amygdalar neurons tested. Most neurons in the central and basal nuclei responded to carotid chemoreceptor activation typically with an excitation. Almost one-half of all amygdalar neurons tested, particularly in the central nucleus, received orthodromic input from the locus ceruleus, the substantia nigra, and/or the contralateral central nucleus of the amygdala. Exteroceptive sensory stimulation with optic, acoustic, tactile, and olfactory stimuli elicited responses in 33, 55, 39, and 59% of amygdalar neurons, respectively. Two-thirds of the neurons tested with more than one external stimulus modality responded in the same manner to the various stimuli (usually excitation), demonstrating a convergence of exteroceptive stimuli on single amygdalar neurons, particularly in the basal nucleus. Spontaneous and induced behavioral arousal elicited responses in 92 and 86% of neurons, respectively. Most neurons responded to multimodal exteroceptive stimuli and behavioral arousal in the same manner. We suggest that amygdalar inputs are highly varied and, in many cases, relatively nonspecific and that the amygdala integrates a large number of external and internal sensory modalities to regulate autonomic and behavioral responsiveness to various stimuli.

Amygdala↗
PubMed1993

Performance factors and gender-related differences in spatial ability: another assessment.

To explore whether test-taking styles (performance factors) can contribute to explaining gender-related differences on tests of spatial ability, 15 spatial tests were administered to three samples of subjects. On each test, number-correct scores and ratio scores (number of items solved divided by the number of items attempted) were computed. In accordance with previous research findings, the use of ratio scores significantly reduced the magnitude of the gender-related differences on the Mental Rotations Test. For most of the remaining tests, however, the reduction of the gender-related score difference was small. It was concluded that the difference reduction for the Mental Rotations Test was specific to the format of this test. In common spatial tests, performance factors may account for a small portion of gender-related variance, but the bulk of this variance must be attributed to other factors.

Adolescent↗
PubMed1992

Altered transferrin gene expression in preneoplastic and neoplastic liver lesions induced in rats with N-nitrosomorpholine.

The expression of the gene for the iron transport protein transferrin was found to be altered in preneoplastic and neoplastic lesions induced in the rat liver by N-nitrosomorpholine. The total RNA of ten hepatocellular carcinomas (HCC) was investigated by Northern blot analysis using a cDNA-probe comprising 150 bp of the 3' region and compared with the total hepatic RNA in untreated rats. Seven hepatocellular carcinomas showed slight or pronounced reduction in transferrin expression. In situ hybridization of two additional hepatocellular carcinomas revealed marked reduction in the mRNA level for the transferrin gene compared with the surrounding tissue. In contrast, the majority of early preneoplastic lesions storing excess glycogen and tigroid cell foci expressed increased levels of transferrin mRNA. The loss of glycogen in mixed cell foci, which represent a later stage of hepatocarcinogenesis, was usually accompanied by a decrease in transferrin mRNA suggesting a close relationship between this change in gene expression and cellular dedifferentiation emerging during hepatocarcinogenesis.

Animals↗
PubMed1992

Cellular and molecular mechanisms of renal carcinogenesis induced by avian erythroblastosis virus.

Besides erythroleukemias and sarcomas, avian erythroblastosis virus strain ES4 (AEV-ES4) induces renal adenocarcinomas (RCas) in chickens. To search for the cells of origin and the mechanism of the development of RCas, we investigated the RCas produced by td359AEV, a mutant of AEV-ES4 which lacks a leukemogenic effect, but which is sarcomagenic. Spindle cell sarcomas in various organs and RCas developed in a high number of chickens inoculated with td359AEV. RCas were tubulo-cystopapillary structures of basophilic cells and originated only from differentiated principal cells (PCs) of the renal collecting duct system. The origin of tumors from PCs was indicated by connections of tumor epithelium to segments of the collecting duct system, including connecting tubules and cortical and medullary collecting ducts. Tumor cells showed typical mucopolysaccharide-containing vacuoles which are characteristic of chicken PCs. Viral particles were observed throughout the kidney. Moreover, the highest numbers of particles as well as budding-images of them were seen (apart from tumor cells) in podocytes and distal tubule cells which did not undergo neoplastic change. The susceptibility of PCs to undergo neoplastic transformation could not be related to a particular activation state of the erbB gene, in view of the fact that cerbB expression was detected by in situ hybridization in the epithelium lining the Bowmann's capsule and the entire renal tubule system. From data of Northern blot and in situ hybridization techniques, it was suggested that the neoplastic transformation of PCs was elicited by overexpression of the v-erbB oncogene, a feature of tumor cells already detected in renal tubules lined by basophilic proliferating cells, the first stages of renal carcinogenesis induced by td359AEV. According to Southern blot analysis, td359AEV proviruses were randomly inserted in tumor DNAs and the RCas were polyclonal in nature.

Alpharetrovirus↗
PubMed1990

Afferent connections of the nucleus centralis amygdalae. A horseradish peroxidase study and literature survey.

The central nucleus of the amygdala has been shown to be involved in cardiovascular regulation and the integration of arousal. In this study, the afferent input was investigated in cat by microinjecting horseradish peroxidase (HRP) into the central nucleus and examining retrogradely-labelled cells in the brain. Retrograde labelling was found in the cortex next to the sulcus ectosylvius anterior, fissura lateralis Sylvii, sulcus rhinicus anterior and posterior, sulcus suprasylvius, and pyriform and entorhinal cortices as well as in the insula and claustrum. Each of the sub-nuclei of the amygdaloid complex exhibited retrogradely-labelled perikarya. Labelled cells were also found in the diagonal band of Broca, nucl. lateralis septi, and nucl. proprius striae terminalis (bed nucl. of stria terminalis). In the hypothalamus the area preoptica medialis and lateralis, nucl. dorsomedialis, paraventricularis, periventricularis, arcuatus and mammilaris medialis were labelled. The nucl. subthalamicus, zona incerta, peripeduncular system, substantia nigra, and nucl. interpeduncularis contained HRP-marked cells. In the thalamus labelled cells were observed in the nucl. reuniens, nucl. centroposterior lateralis, nucl. latero-posterior, nucl. posterior, nucl. centro-anterior, antero-dorsalis, antero-medialis, antero-lateralis, centrum mdianum, nucl. reticularis, nucl. rhomboideus, nucl. parafascicularis and subfascicularis. The area tegmentalis Tsai and the corpora geniculata also contained labelled cells. In the brain stem, HRP-marked cells could be detected in the brachium colliculi inferioris, aqueductal grey matter, locus coeruleus, nucl. parabrachialis, in various nuclei of the formatio reticularis, in the nucl. retrofascialis, nucl. solitarius, nucl. commissuralis, nucl. ambiguus and nucl. dorsalis n. vagi. The results were compared to other neuroanatomical studies and to functional studies of the amygdala.

Afferent Pathways↗
PubMed1990

Dietary fructose enhances the development of atypical acinar cell nodules in the pancreas of rats pretreated with N-nitrosomorpholine.

Dietary influences on carcinogenesis have been shown in various tissues on the basis of epidemiological and experimental approaches. The present paper demonstrates that the oral application of fructose over long periods to rats previously treated with N-nitrosomorpholine increases the incidence of atypical acinar cell nodules (AACN) in the pancreas. Whereas an increase in AACN was statistically significant (P less than 0.005), no effect on ductule-like structures was detectable. AACN have been regarded as precursor lesions of the acinar cell carcinoma. Although the AACN observed frequently exhibited severe atypia and numerous mitotic figures, no clearcut evidence for malignancy could be detected under our experimental conditions.

Animals↗
PubMed1989

Sex-related differences in spatial ability: more evidence for convergence.

Sex-related differences in spatial ability, favoring males, have frequently been reported in the literature. Recent analyses, however, have found indications of a convergence in the scores of men and women on spatial tests over the years. This research examined the evidence for such a secular trend in a German population using data of 18 samples that had completed the Cube Perspectives Test, a measure of spatial visualization ability. The largest effect size (d = .77) was found for a sample tested in 1978, the smallest difference (d = .38) was observed for a sample tested in 1987. There was a clear trend narrowing the sex-related differences; the correlation between the recency of the data and the respective d-value was -.926. The convergence of the scores of men and women proved to be stronger than in the previous studies.

Adolescent↗
PubMed1987

Sensory input to single neurons in the amygdala of the cat.

We determined functionally the afferent projections from exteroceptors and enteroceptors (visceral receptors) to single cells of the amygdala. Recordings were made in chloralosed cats from 249 cells in four subnuclei of the amygdala. Forty-six percent of cells tested responded to carotid sinus nerve stimulation and more than one-half of them responded to selective baroreceptor or chemoreceptor activation or to electrical stimulation of the locus ceruleus. Of 11 cells responding similarly (inhibition) to carotid sinus nerve stimulation and to selective baroreceptor activation, all were inhibited by locus ceruleus stimulation, also. Approximately 17% of cells tested responded to at least one exteroceptive stimulus (acoustic, optic, or tactile) whereas 14% responded to more than one exteroceptive stimulus in a similar manner. Amygdalar cells were also identified that responded to visceral (renal nerve) and somatic (iliac nerve) stimulation. Many cells received input both from enteroreceptors and from exteroceptors. These results suggest that baroreceptor input to single neurons in the amygdala is often convergent with input from the locus ceruleus. In addition, the convergence of both internal and external sensory inputs to single neurons is further evidence that the amygdala is a site for the integration of responses to arousal.

Acoustic Stimulation↗
PubMed1986

Baroreceptor sensitivity during desynchronized sleep.

Sleep is characterized by periods of cortical and subcortical desynchronization similar to that observed during arousal. Because baroreflex control of heart rate is suppressed in the aroused state, the present study compared the cardiac index of baroreflex sensitivity in awake cats with that during desynchronized sleep to determine the level of arousal and its affect on autonomic regulation. Cats were prepared for long-term arterial pressure, cortical, and subcortical EEG and EMG recording. After acclimatization to the laboratory, cats engaged in spontaneous periods of desynchronized sleep. During this period, a bolus of angiotensin II was injected i.v. and the subsequent change in the R-R interval of the cardiac cycle was recorded during the rising phase of the pressor response. These values were compared with values obtained from the same cats during quiet and active wakefulness and those obtained during drug-induced desynchronized sleep with gamma-hydroxybutyrate. The values obtained during naturally occurring desynchronized sleep were comparable to those observed during drug-induced desynchronized sleep. In contrast, the increase in the R-R interval in awake cats, particularly quiet ones, was greater than that seen during desynchronized sleep or during active periods in the awake animal. These data suggest that there is a correlation between the level of arousal, as measured by EEG activity, and the cardiomotor component of baroreflexes.

Animals↗
PubMed1984

Baroreceptor reflex during arousal induced by electrical stimulation of the amygdala or by natural stimuli.

Baroreceptor control of heart rate was studied in 14 unanaesthetized cats during rest and arousal induced by either electrical stimulation of the central nucleus of the amygdala or by natural stimuli. The baroreceptor reflex was elicited by i.v. injections of angiotensin II and the sensitivity of the vagal component of the reflex expressed as the regression coefficient of the relationship between the systolic blood pressures of successive arterial pulses and their pulse intervals. Baroreceptor reflex sensitivity was reduced by all types of arousing procedure studied; an effect assumed to be a part of integrated cardiovascular adjustments accompanying arousal. Further studies in slightly anaesthetized cats were performed in order to investigate the time-course of such changes in reflex sensitivity. Th inhibition of the vagal component of the reflex did not last for the entire period of the electrically elicited arousal and it is suggested, therefore, that this might reflect the activation of mechanisms which limit orienting behaviour. Overall, these results indicate that the central nucleus of the amygdala may be involved in a transient integration of cardiovascular and behavioural responses during arousal.

Amygdala↗
PubMed1983

Involvement of dopamine in amygdaloid kindling.

The concentrations of dopamine, noradrenaline, and dihydroxyphenylacetic acid were determined in the amygdala, neostriatum, neocortex, hippocampus, brain stem, and hypothalamus of cats, which had had 9 to 14 tonic-clonic kindled seizures. No significant biochemical changes were observed compared to control cats. Pharmacological manipulations of dopamine receptors (haloperidol, apomorphine) did not modify the kindling procedure. According to the data it seems unlikely that dopamine plays a major role in amygdaloid kindling.

Amygdala↗
PubMed1981

Cardiovascular changes during arousal elicited by stimulation of amygdala, hypothalamus and locus coeruleus.

Experiments were performed in chronically operated cats first awake and thereafter anesthetized with pentobarbitone, 16-20 mg/kg i.v. Stimulation of the central amygdala in awake cats elicited an arousal reaction seen in cortical and hippocampal EEG, and in muscle activity of dorsal neck muscles. Concomitantly therewith were autonomic system reactions resulting in a decrease in aortic blood flow distal to the renal arteries, an increase in arterial blood pressure, a tachycardia during, and a short-lasting bradycardia at the end of stimulation. In slightly anesthetized cats the cardiovascular reactions were found to be qualitatively similar. If the postero-lateral hypothalamus or the locus coeruleus complex were stimulated in cats first awake and thereafter anesthetized, similar arousal reactions and similar cardiovascular changes were obtained as with amygdaloid stimulations. However, the onset and magnitude of the response were more abrupt and more marked than those obtained by amygdaloid stimulations. Recordings of single unit activity within the central amygdala during spontaneously occurring changes in the level of arousal showed that amygdaloid units (n = 10) discharged at a rate of 7-14 impulses/sec during wakefulness whereas during slow wave sleep (n = 5) the discharge was only 2-9 impulses/sec. The hypothesis is put forward that the amygdala integrates behavioral and cardiovascular changes during arousal.

Amygdala↗