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B Putz

Publications and source records attributed to B Putz.

16 recordsLinked to original sources
PubMed1998

Attention-regulated activity in human primary visual cortex.

Effects of attention to a local contour of a moving object on the activation of human primary visual cortex (area V1) were examined. Local cerebral oxygenation changes (an index of neuronal activity) in human area V1 were measured with functional magnetic resonance imaging (fMRI) in conditions including the following two: 1) when attention was selectively directed toward one side of a moving wedge (the attention condition) and 2) when the wedges were viewed passively (the passive condition). Activation in area V1 was found to be higher in the attention condition than in the passive condition. To our knowledge, this is the first finding that attention to motion activates as early as area V1. We suggest that attentional activation of area V1 is task dependent.

Attention↗
PubMed1991

Control of cell death (apoptosis) by diethylstilbestrol in an estrogen-dependent kidney tumor.

The role of cell death as a determinant for tumor growth and regression was studied using an estrogen-dependent, transplantable kidney tumor designated H301. H301 cells were injected s.c. into diethylstilbestrol(DES)-treated male Syrian hamsters and developed solid tumors of 1-2 g within 2-3 weeks. Upon withdrawal of estrogen the tumors regressed by 80-90% within 4 days. Mitoses, necrotic areas and single-cell death indicated by small, condensed cell residues, were counted in hematoxylin and eosin stained histological sections of the tumors. Coincident with tumor regression after DES withdrawal, mitotic activity decreased by approximately 90%; the rate of single-cell death increased (by approximately 2-fold at its maximum). The incidence of necrotic areas was not affected by DES withdrawal. DES re-treatment resulted in reduction of single-cell death by 80% within 8 h. Mitotic activity increased within 24 h to the level observed before DES withdrawal. Again, the incidence of necrotic areas did not change. As a result, tumors re-grew to their previous size within 2 days after resumption of DES treatment. These results led to the following conclusions: (i) DES treatment inhibits and DES withdrawal enhances single-cell death of H301 tumor cells. (ii) Both this functional property and its morphology characterize single-cell death in the tumors as apoptosis. (iii) Estrogen-dependent cell death determines, in addition to mitosis and necrosis, the growth rate of H301 tumors. (iv) This experimental model may provide a useful tool to study the interaction of potential anti-tumor drugs with apoptosis in neoplasia.

Animals↗
PubMed1990

Tumor promotion by the peroxisome proliferator nafenopin involving a specific subtype of altered foci in rat liver.

The involvement of tumor promotion in the hepatocarcinogenic action of peroxisome proliferators has not been generally accepted. We studied the effect of nafenopin (NAF) as a model compound in a two-stage initiation-promotion protocol. Carcinogenesis was initiated by a single dose of aflatoxin B1 (AFB1) in female (AFB1, 5 mg/kg) and male (AFB1, 2 mg/kg) Wistar rats. After recovery NAF was fed via the diet, providing a daily dose of 100 mg/kg body weight. Phenobarbital (PB) (50 mg/kg body weight) was fed to female rats as a positive control. The following results were obtained. (a) At weeks 40, 55, 59, and 70, significantly more and larger liver tumors were present in AFB1-NAF-treated rats than in rats receiving either compound alone, and the effect of the combined treatment was clearly more than additive, in three independent experiments including both sexes. This suggests tumor promotion by NAF. Male rats responded more strongly than females. Similarly, PB enhanced the yield of liver tumors. Histologically, tumors were hepatocellular adenoma or carcinoma. In group AFB1-PB the majority consisted of eosinophilic and glycogenstoring cells. However, adenoma and carcinoma of groups AFB1-NAF and O-NAF consisted of weakly basophilic cells. (b) Phenotypically altered foci were evaluated in hematoxylin- and eosin-stained liver sections from the female rats. NAF treatment after AFB1 had little effect on number and size of eosinophilic-clear cell foci and decreased the number of trigroid foci. However, it led to a dramatic increase (20-fold after 70 weeks of NAF treatment) in number and size of foci of a special phenotype that was extremely rare after AFB1 alone and virtually absent in group AFB1-PB. Hepatocytes in these foci are characterized by weak diffuse basophilia and some eosinophilia, similar to the phenotype in adenoma and carcinoma, and by absence of gamma-glutamyltranspeptidase (GGT) expression. Based on these findings, we propose the hypothesis that NAF promotes the development of liver tumors via a mechanism involving amplification of a specific subtype of altered hepatic foci.

Aflatoxin B1↗
PubMed1990

Effects of hypolipidemic drugs nafenopin and clofibrate on phenotypic expression and cell death (apoptosis) in altered foci of rat liver.

Phenotypically altered liver foci were produced in female Wistar rats by a single dose of N-nitrosomorpholine followed by promotion with phenobarbital (PB) for 20 or 28 weeks. Then treatment was changed to either hexachlorocyclohexane (HCH), or cyproterone acetate (CPA), or nafenopin (Naf) or clofibrate (Clof), two hypolipidemic drugs. Foci were identified by a positive reaction for gamma-glutamyl-transpeptidase (GGT) and other cytological markers. HCH and CPA could substitute for PB as foci promoters; in contrast, Naf and Clof decreased expression of GGT in foci resulting in a decline of number and area of detectable foci, effects particularly pronounced with Naf. Immunohistochemical investigations of serial sections revealed that Naf also reduced expression of the altered phenotype when cytochrome P450-PB and pyruvate kinase (type L) were used as foci markers, but not when glutathione-S-transferase B (GST-B) was used. Thus, the number of foci with enhanced GST-B did not decline significantly after the change from PB to Naf treatment. Furthermore, the reduction of GGT and the decrease of foci number during Naf treatment were not associated with increased evidence of cell death by apoptosis in foci, in contrast to the situation after PB withdrawal. These findings strongly suggest that the disappearance of GGT-positive foci after Naf is due to a phenotypic change resulting in a suppression of GGT expression rather than to physical elimination of foci.

Animals↗
PubMed1990

Determination of the length of the histological stages of apoptosis in normal liver and in altered hepatic foci of rats.

Apoptosis is a form of cell death involved in the regulation of cell number in various organs and tumors. Quantitative determination of cell loss through apoptosis in histological sections requires, in addition to counts of apoptotic cells, information on the duration of the histologically visible stages of apoptosis. Here we describe a method to determine the duration of apoptosis in (i) normal and (ii) putative preneoplastic tissue of the liver. (i) Female rats were treated with high doses of the hepatomitogen cyproterone acetate (CPA) to induce liver hyperplasia. After stopping CPA treatment, the hyperplasia partially regressed and excessive hepatocytes were eliminated by apoptosis. CPA was given to block the initiation of apoptosis, and thereafter the time course of elimination of apoptotic cell residues (apoptotic bodies, ABs) from the liver was studied. The mean duration of the histological stages of apoptosis was found to be approximately 3 h. (ii) Phenotypically altered cell foci in rat liver were produced by a single dose of N-nitrosomorpholine and subsequent promotion for 39 weeks with phenobarbital (PB). PB was withdrawn to stop foci growth and to stimulate apoptosis. Then rats were retreated with PB to block initiation of apoptosis in foci. The results indicate that the majority of apoptotic bodies in foci disappeared within 4 h after PB, suggesting that the stages of apoptosis are as short in foci as in normal liver. Finally a simple formula is given to calculate the cell loss rate by apoptosis. The method presented may provide data for quantitative cancer risk assessment from mathematical models of carcinogenesis.

Animals↗
PubMed1989

Histochemical and biochemical studies on the effect of the prostacyclin derivative iloprost on CCl4-induced lipid peroxidation in rat liver and its significance for hepatoprotection.

In the present study, it was investigated whether the prostacyclin derivative Iloprost would protect hepatocytes against CCl4-induced liver injury and which mechanism(s) of hepatocellular pathogenesis might be affected by it. Rats were treated with a single oral dose of CCl4 (2 ml per kg); Iloprost was infused continuously from 2 to 4 hr before intoxication until killing. The following results were obtained. The CCl4-induced release of AST, lactate dehydrogenase and alkaline phosphatase into the serum was reduced by 50 to 70% in rats treated with doses of 0.1 and 0.5 micrograms Iloprost per kg per min. Infusion of 0.02 and 0.004 micrograms Iloprost per kg per min did not affect the CCl4-induced enzyme release into the blood. CCl4 induced the occurrence of aldehydes (products of lipid peroxidation), which were detected by histochemical and biochemical means. At 12, 48 and 72 hr after CCl4, the aldehyde-positive liver section area was about 58, 69 and 16% in rats treated with CCl4 alone, but only about 18, 13 and less than 1% in rats treated additionally with Iloprost. The aldehyde-positive hepatocytes were located predominantly in the centrilobular zone of the liver. At 24 hr the extent of the aldehyde-positive section area was the same in rats with or without Iloprost treatment (about 90%). Biochemical determination, however, revealed that at this time point the malondialdehyde content after Iloprost in rats was about 70% lower than without Iloprost treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1989

Pharmacokinetic interpretation of toxicity tests in rats treated with oestradiol valerate in the diet.

Oestrogen concentrations (oestradiol = E2 and oestriol = E3) were determined in plasma and liver tissue of female rats before, during and after treatment with two different doses (1.2 and 12.0 mg/kg/d) of oestradiol valerate (E2-val) given in the feed over 27 days. The oral bioavailability of E2 was determined in a pharmacokinetic study in which rats received a single intramuscular administration of E2-val. The aim of the present investigation was to support the evaluation of the results of a previous 90 weeks chronic toxicity and tumorigenicity study in rats where the same dosages were administered. The bioavailability was approximately 0.5%; the systemic body burden of exogenous E2 was 1.6 fold, the endogenous E2 burden at the low, and 9 fold at the high dose. Despite these low values, distinct systemic effects were noted. At 1.2 mg/kg/d a marked decrease in food consumption and body weight gain occurred in the 27 day study as well as in the chronic study. In addition, in the latter study mortality increased from the low dose onwards and was complete at the high dose after 72 weeks. The incidence of pituitary adenoma increased. The results indicate that theoretically rats are far more sensitive towards exogenous oestradiol treatment than humans.

Animals↗
PubMed1986

Abnormal neural fold development in mouse trisomy 12 and trisomy 14. II. LM and TEM.

LM and TEM observations of embryonic tissue during the period of cranial neurulation are described in trisomic mouse embryos known to develop exencephaly, and are compared with tissue from normal mouse embryos. The earliest regularly observed differences were visible from the late presomite stage onwards, in the extracellular matrix of the cranial region. These were local defects of the basement membrane of the neural epithelium and enlarged areas of mesenchymal extracellular matrix, with associated abnormalities of mesenchymal cell distribution, cell number and cell contacts, and deficiency of alcian blue staining. Apical neuroepithelial microfilament bundles were observed at later somite-stages in trisomic embryos c.f. = compared with controls, and development of the concave neuroepithelial curvature was correspondingly retarded. Apposition of the neural folds at the forebrain/midbrain junction was never made, even though late neural fold fusion occurred in the hindbrain and ventral forebrain. At later stages (9-20 somites) the neuroepithelial cells showed pyknotic nuclei and dense intracellular inclusions. These are interpreted as secondary effects.

Animals↗
PubMed1985

Anencephaly in one monoamniotic-monochorionic twin and encephalocele in the other.

This is a report of monoamniotic-monochorionic (ie, probably MZ) twins, one of which had anencephaly, whereas the co-twin died of complications of prematurity. Autopsy in this seemingly nonmalformed twin showed a small encephalocele. The literature on MZ twins with discordant anencephaly is often contradictory. It is suggested that this might be due to the difficulty of determining zygosity on the one hand and identifying discordance or concordance on the other. This case is presented as an example of this difficulty; it is discordant with respect to anencephaly, but concordant in the sense of "dysraphic" disturbances.

Anencephaly↗
PubMed1983

Analysis of two-dimensional protein patterns from mouse embryos with different trisomies.

Two-dimensional protein patterns from whole mouse embryos with different trisomies (Ts) (Ts1, -12, -14, -19) and from different organs (normal or malformed) and developmental stages of Ts12 embryos were analyzed by comparison with control patterns. Quantitatively altered proteins were found, and a portion of these (21/approximately equal to 1,000, average) was attributable to the Ts conditions. Most of these variants were found always (regularly) in Ts embryos. They could be divided into two groups: group I shows characteristics (chromosome specific, density increased by a factor close to 1.5 +/- 0.12) compatible with proteins directly affected by the Ts; and group II (chromosome nonspecific, density decreased, seldom increased) results most likely from indirect effects. The incidence of group II variants (about 13/approximately equal to 1,000, average) was considerably greater than that of the group I variants (about 3/approximately equal to 1,000). The frequency of both types of variants, however, was far lower than was expected by a rough estimation. Apparently, a relatively small number of changes, rather than a complex, escalating effect, was induced at the protein level by the Ts. Some observations suggest that this is due to a stable regulation of protein concentrations. The proportion in which quantitative changes of different types occurred in the protein patterns did not correlate with the degree of developmental impairments (malformation, retardation, early death) of the embryos. The generalized occurrence of protein changes on the cellular level might explain the restricted viability of Ts mouse embryos.

Animals↗
PubMed1980

Severe fetal manifestation of hemifacial microsomia.

Hemifacial microsomia is a heterogenous complex lesion including predominantly unilateral face and head malformations mainly in the region of the first and second branchial arch, vertebral anomalies and varying accompanying malformations. A severe manifestation of this condition is demonstrated in a fetus by means of 5 mm thick sections of the whole head. Abortion had been induced because extreme microcephaly simulated fetal anencephaly in prenatal ultrasound examination. Alpha-Fetoprotein values were normal.

Abortion, Induced↗