Search PubMed⌕ Search

Biomedical subjects

E Fuchs

Publications and source records attributed to E Fuchs.

At least 271 records · Page 15Linked to original sources
PubMed1988

Binding sites of atrial natriuretic peptide in human renal tissue-quantification by in vitro receptor autoradiography.

Specific binding sites for atrial natriuretic peptide (99-126) in different areas of normal human renal tissue were quantified by in vitro autoradiography. Our data represent the first characterization of ANP binding sites in different structures of the human kidney. Characterization of ANP binding revealed by Scatchard plot analysis a single class of high affinity binding sites in the glomeruli (Kd 0.53 +/- 0.11 nM; BMax 74.4 +/- 17.86 fmol/mg protein), the vasculature (Kd 0.18 +/- 0.014 nM; BMax 91.6 +/- 25.02 fmol/mg protein), and the medulla (Kd 0.34 +/- 0.13 nM; BMax 106.0 +/- 30.61 fmol/mg protein). These sites may play a key role in the actions of the cardiac hormone in human kidney and in the ameliorating effects of ANP in the recovery from acute renal failure.

Aged↗
PubMed1988

The corticosterone receptive system in the brain of Tupaia belangeri visualized by in vivo autoradiography.

The present investigation deals with in vivo binding of 3H-corticosterone in the brains of tree shrews as visualized by autoradiography. Tree shrews were injected with 3H-corticosterone and brain sections were mounted on slides which were subsequently exposed on tritium sensitive film. The relative labeling of 20 different brain structures was determined densitometrically. The indusium griseum, which demonstrated the highest binding for corticosterone of all brain regions in the autoradiograms, was taken as reference and defined as 100% relative labeling (RL). As in other species, the hippocampal subdivisions of the tree shrew retained high amounts of the steroid (60 to 80% RL). In other parts of the limbic system, medium labeling intensities were observed with approximately 40% RL in the lateral septum. The amygdala was less intensely labeled revealing around 30% RL in the basal accessory, the cortical, central, and the lateral nuclei. Autoradiographic grey values in the ventral striatum and pallidum were comparable to those in the amygdala, but in the islands of Callejae they were approximately as high as in the lateral septum (44% RL). In contrast to previous reports dealing with other species, the tree shrew cerebellum also demonstrated a high binding capacity for corticosterone. The RL was nearly 60% in the cerebellar granular layer. This finding may indicate that the cerebellum also plays a role in mediating the effects of corticosterone in the central nervous system.

Animals↗
PubMed1988

Locomotor activity registration by passive infrared detection in saddle back tamarins and tree shrews.

Locomotor activities of tamarins and tree shrews were monitored using a passive infrared detector (PID) and a small hand-held computer as a recording unit. It is a low-cost system, easy to install and to handle without any disturbing effects on the animals investigated. Recording activity is not limited to specific sites in the cage. A temporal resolution of about two seconds for activity detection will meet most experimental requirements. The method was validated by a comparison of PID-recorded signals with simultaneous behavioral observations using a video-recorder. PID is highly specific, detecting only those movements which involve a change in location. The recording system can be adapted to various experimental conditions or other mammalian species.

Animals↗
PubMed1988

Binding sites for atrial natriuretic peptide in the kidney and aorta of the hagfish (Myxine glutinosa).

1. In the atlantic hagfish (Myxine glutinosa) binding sites for atrial natriuretic peptide (ANP) were visualized by autoradiography in contractile structures of the renal system (glomeruli, neck segment, and archinephric duct) and in the aorta. 2. Since the location of binding sites is comparable to that in higher vertebrates including man, these results suggest that ANP may act as a hormone already in cylcostomata.

Animals↗
PubMed1988

Human papillomavirus type 16 alters human epithelial cell differentiation in vitro.

Human papillomavirus (HPV) types 16, 18, 31, and 33 have been implicated as etiologic agents of cervical and penile cancer. Using a cell culture system for keratinocytes which allows stratification and production of differentiation-specific keratins, we have examined the effects of one of these viruses, HPV-16, on the differentiation capabilities of human epithelial cells. A plasmid containing the HPV-16 genome and a neomycin-selectable marker was transfected into primary human epidermal cells and SCC-13 cells, an immortalized squamous cell carcinoma cell line. Cloned neomycin-resistant cell lines were isolated and examined by cell culture on raised collagen rafts. Cell lines containing HPV-16 DNA retained the ability to stratify and express differentiation-specific keratins in the raft system but otherwise failed to differentiate normally. The histological abnormalities induced by HPV-16 closely resembled those seen in genital intraepithelial neoplasia in vivo. Hence, our results support the role of HPV-16 as an etiologic agent in the development of genital neoplasias and suggest a specific system for the study of HPV-16-induced epithelial cancers.

Blotting, Southern↗
PubMed1988

Use of monospecific antisera and cRNA probes to localize the major changes in keratin expression during normal and abnormal epidermal differentiation.

We report here the isolation and characterization of three antisera, each of which is specific for a single keratin from one of the three different pairs (K1/K10, K14/K5, K16/K6) that are differentially expressed in normal human epidermis and in epidermal diseases of hyperproliferation. We have used these antisera in conjunction with monospecific cRNA probes for epidermal keratin mRNAs to investigate pathways of differentiation in human epidermis and epidermal diseases in vivo and in epidermal cells cultured from normal skin and from squamous cell carcinomas in vitro. Specifically, our results suggest that: (a) the basal-specific keratin mRNAs are down-regulated upon commitment to terminal differentiation, but their encoded proteins are stable, and can be detected throughout the spinous layers; (b) the hyperproliferation-associated keratin mRNAs are expressed at a low level throughout normal epidermis when their encoded proteins are not expressed, but are synthesized at high levels in the suprabasal layers of hyperproliferating epidermis, coincident with the induced expression of the hyperproliferation-associated keratins in these cells; and (c) concomitantly with the induction of the hyperproliferation-associated keratins in the suprabasal layers of the epidermis is the down-regulation of the expression of the terminal differentiation-specific keratins. These data have important implications for our understanding of normal epidermal differentiation and the deviations from this process in the course of epidermal diseases of hyperproliferation.

Amino Acid Sequence↗
PubMed1988

Isolation, sequence, and differential expression of a human K7 gene in simple epithelial cells.

Simple epithelial cells synthesize a different set of keratins than epidermal cells. In experiments reported in this manuscript, we show that the base level of keratin expression in simple epithelial cells is variable for different cell types, and that, in some simple epithelia, this level can be upregulated by increasing the exposure of cells to retinoids, but not glucocorticoids or estradiol. To elucidate the molecular mechanisms underlying simple epithelial keratin gene regulation, we have isolated and characterized a human gene encoding the simple epithelial keratin K7. By examining the possible regulatory elements of this gene and by investigating the behavior of this gene introduced transiently into simple epithelial cells, we have uncovered a possible basis for the differential expression of epidermal and simple epithelial keratin genes.

Amino Acid Sequence↗
PubMed1988

Sequence and expression of a type II keratin, K5, in human epidermal cells.

We report here the cDNA and amino acid sequences of a human 58-kilodalton type II keratin, K5, which is coexpressed with a 50-kilodalton type I keratin partner, K14, in stratified squamous epithelia. Using a probe specific for the 3'-noncoding portion of this K5 cDNA, we demonstrated the existence of a single human gene encoding this sequence. Using Northern (RNA) blot analysis and in situ hybridization with cRNA probes for both K5 and K14, we examined the expression of these mRNAs in the epidermis and in cultured epidermal cells. Our results indicate that the mRNAs for K5 and K14 are coordinately expressed and abundant in the basal layer of the epidermis. As cells undergo a commitment to terminally differentiate, the expression of both mRNAs seems to be downregulated.

Amino Acid Sequence↗
PubMed1988

A group of type I keratin genes on human chromosome 17: characterization and expression.

The human type I keratins K16 and K14 are coexpressed in a number of epithelial tissues, including esophagus, tongue, and hair follicles. We determined that two genes encoding K16 and three genes encoding K14 were clustered in two distinct segments of chromosome 17. The genes within each cluster were tightly linked, and large parts of the genome containing these genes have been recently duplicated. The sequences of the two K16 genes showed striking homology not only within the coding sequences, but also within the intron positions and sequences and extending at least 400 base pairs 5' upstream and 850 base pairs 3' downstream from these genes. Despite the strong homologies between these two genes, only one of the genes encoded a protein which assembled into keratin filaments when introduced into simple epithelial cells. While there were no obvious abnormalities in the sequence of the other gene, its promoter seemed to be significantly weaker, and even a hybrid gene with the other gene's promoter gave rise to a much reduced mRNA level after gene transfection. To demonstrate that the functional K16 gene that we identified was in fact responsible for the K16 expressed in human tissues, we made a polyclonal antiserum which recognized our functional K16 gene product in both denatured and filamentous form and which was specific for bona fide human K16.

Amino Acid Sequence↗
PubMed1988

Localization of keratin mRNA in human tracheobronchial epithelium and bronchogenic carcinomas by in situ hybridization.

An in situ hybridization technique was applied to detect expression of keratin mRNAs in xenotransplanted human tracheobronchial epithelium and lung carcinomas. Tissues from eight tracheas repopulated with cells from five different noncancerous donors and 15 squamous cell carcinomas were used. Using a K6 (56 kd) human keratin cDNA (KA-1) and a K14 (50 kd) cDNA (KB-2) as probes, radiolabeled by nick-translation with 3H-dATP/TTP, the specificity and significant differences in the levels of silver grains on various epithelial lesions in formalin-fixed, paraffin-embedded tissue sections were demonstrated. In situ hybridization with either KA-1 or KB-2 probe showed similar localization of silver grains in all histologic types in consecutive tissue sections. In xenotransplanted tracheobronchial epithelia, very few grains were seen over cells of simple, pseudostratified, or stratified epithelia two to three cell layers thick. Nonkeratinizing stratified hyperplastic epithelia of more than three cell layers showed uniform localization of numerous grains throughout the lesions. In contrast, epidermoid metaplasias exhibited a dense and localized pattern of grains on the basal and parabasal cell layers with a decrease in grain density toward the surface layers. Carcinoma cells from bronchogenic squamous cell carcinomas showed a higher density and more uniform localization of grains. Well-differentiated carcinoma cells contained more keratin mRNAs than moderately to poorly differentiated carcinoma cells. This evidence obtained with the KA-1 and KB-2 probes demonstrates the different localization patterns of keratin mRNAs in different epithelial lesions. In addition, the levels of mRNA expressed show a positive correlation with the degree of squamous differentiation. It was of particular interest that an ordered program of keratin mRNA expression proportional to the level of cellular differentiation was observed in epidermoid metaplasias. Both of these probes serve as keratinization markers of human tracheobronchial epithelial lesions.

Animals↗
PubMed1987

More than 150 nucleotides flanking the initiation codon contribute to the efficiency of the ribosomal binding site from bacteriophage T7 gene 1.

The ribosomal binding site (RBS) from gene 1 of bacteriophage T7 was isolated on fragments of differing length and cloned upstream of the mouse dihydrofolate reductase gene to control the translation of its sequence. A 29 base pair sequence containing all elements generally believed to be essential for the RBS's showed extremely low activity. Additional upstream and downstream sequences were required to obtain a several orders of magnitude higher efficiency. By contrast, areas further downstream than +112 nucleotides from the initiator proved to be inhibitory, whereas the presence of an upstream RNaseIII cleavage site showed a strong stimulatory effect. This suggests that tertiary structures are involved in the function of the RBS studied. The efficient RBS's were complexed by ribosomes at much lower concentrations of the mRNA than the weak ones.

Base Sequence↗
PubMed1987

The transfection of epidermal keratin genes into fibroblasts and simple epithelial cells: evidence for inducing a type I keratin by a type II gene.

Through gene transfection studies, we have discovered that the forced expression of a foreign type II epidermal keratin in fibroblasts can trigger the expression of an endogenous type I epidermal keratin. Both the transfected and the induced proteins participate in the formation of filamentous structures. Interestingly, this regulation appears to be unidirectional: the expression of a transfected type I keratin does not induce type II expression. Rather, nonfilamentous aggregates of type I protein accumulate in the cytoplasm. In contrast, simple epithelial cells transfected with either a type I or a type II epidermal keratin gene do not respond by inducing the expression of a host epidermal keratin. In this case, the foreign protein is incorporated into the endogenous keratin network. These results suggest the possibility that type I keratin expression may be dependent on the accumulation of unpolymerized type II keratin.

Animals↗
PubMed1987

Atrial natriuretic peptide detected by immunocytochemistry in peripheral organs of Tupaia belangeri.

ANP (atrial natriuretic peptide), a peptide found in granules of mammalian atrial cardiac myocytes, has been shown to be active in regulation of blood pressure and body water homeostasis. The existence of ANP in atrium, pituitary, adrenal gland, and kidney of the rat had been immunocytochemically demonstrated with an antibody against rat ANP (102-126). We used the same antibody in immunocytochemical studies for the detection of ANP in peripheral organs of the tree shrew (Tupaia belangeri). The antibody stained granules in myocytes of cardiac atria which indicated that it reacted with tree shrew ANP. In contrast to the rat, no immunoreactive cells were found in pituitaries and adrenal glands. However, in the kidneys distal tubules in outer medulla and cortex were labeled. Ascending limbs of distal tubules were intensely stained when either the peroxidase-antiperoxidase (PAP) or the indirect immunofluorescence method were used. Collecting ducts and convoluted distal tubules in the outer cortex showed a granular type of staining when the immunofluorescence method was used. These data indicate that ANP is present in epithelial cells of distal tubules and collecting ducts, where it may be involved in the regulation of renal salt excretion.

Adrenal Medulla↗
PubMed1987

Response of rats to the presence of stressed conspecifics as a function of time of day.

The physiological response of nonrestrained rats to the presence of immobilized conspecifics during the beginning of the active period and the inactive period was studied. In immobilized animals concentrations of serum corticosterone (SCS), serum glucose, and liver glycogen, and the activity of liver tyrosine aminotransferase (TAT) during both the active and the inactive periods, were consistent with earlier studies. In nonrestrained rats the presence of immobilized conspecifics induced a significant increase in SCS during the active period, whereas it had no effect during the inactive period. The level of TAT was significantly elevated in the nonrestrained rats only during the inactive period and remained unchanged during the active period. The results demonstrate a physiological influence of stressed rats on unstressed conspecifics and provide evidence for regulation of TAT activity that is dependent on the situation and the time of day.

Activity Cycles↗