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Biomedical subjects

H Hering

Publications and source records attributed to H Hering.

At least 19 recordsLinked to original sources
PubMed2000

Distribution of the integrin beta 1 subunit on radial cells in the embryonic and adult avian retina.

The distribution of the beta1 integrin subunit was investigated in the developing and adult chick retina at the light and electron microscopic levels, using two different monoclonal antibodies. Western blotting revealed a single band with a molecular weight of approximately 130 kDa in the retina and in a number of other tissues, indicating the specificity of the antibodies. In the retina, immunoreactivity was detected on radial cells spanning the entire width between the pigment epithelium and the vitreal border. These cells were undifferentiated neuroepithelial cells at early stages and radial Müller glial cells at later stages of development. At all stages, the beta1 subunit was concentrated at the vitreal border of the retina around the inner limiting membrane. Mechanical isolation of the inner limiting membrane, as well as immunoelectron microscopy, demonstrated that this immunoreactivity was due to a concentration of the beta1 subunit in the endfeet of neuroepithelial and Müller glial cells. Injection of collagenase into the vitreous of live embryos, a procedure that selectively removes the inner limiting membrane, but does not proteolytically degrade the integrin protein, resulted in a redistribution of the integrin immunoreactivity, demonstrating that the integrity of the basal lamina is required for the maintenance of the concentration of the beta1 subunit in the endfeet. These results suggest a role for the beta1 subunit-containing integrin heterodimers in the adhesion of neuroepithelial and Müller glial cells to extracellular matrix components of the inner limiting membrane, possibly stabilizing the radial morphology of these cells.

Aging↗
PubMed1999

Synapse formation and agrin expression in stratospheroid cultures from embryonic chick retina.

Stratospheroids are three-dimensional cellular spheres which develop in vitro through the proliferation and differentiation of retinal neuroepithelial precursor cells. We investigated synapse formation in stratospheroids by analyzing the development of aggregates of synapse-associated molecules and of electron microscopically identifiable synaptic specializations. Our results show that the first aggregates of the GABA(A) receptor, the glycine receptor, and gephyrin appear in the inner plexiform layer after 8 days in culture simultaneously with the development of the first active zones and postsynaptic densities. In contrast, presynaptic molecules including synaptophysin could be detected in the inner plexiform layer before synaptogenesis, suggesting functions for these molecules in addition to neurotransmitter exocytosis at mature synapses. Similar to the retina in vivo, synapses were not found in the nuclear layers of stratospheroids. We also analyzed the isoform pattern, expression, and distribution of the extracellular matrix molecule agrin, a key regulator during formation, maintenance, and regeneration of the neuromuscular junction. In stratospheroids, several agrin isoforms were expressed as highly glycosylated proteins with an apparent molecular weight of approximately 400 kDa, similar to the molecular weight of agrin in the retina in vivo. The expression specifically of the neuronal isoforms of agrin was concurrent with the onset of synaptogenesis. Moreover, the neuronal agrin isoforms were exclusively found in the synapse-containing inner plexiform layer, whereas other agrin isoforms were associated also with the inner limiting membrane and with Müller glial cells. These results show that synapse formation is very similar in stratospheroids and in the retina in vivo, and they suggest an important role for agrin during CNS development.

Agrin↗
PubMed1997

Pigmented epithelium sustains cell proliferation and decreases expression of opsins and acetylcholinesterase in reaggregated chicken retinospheroids.

We investigated the effect of the retinal pigmented epithelium on cell proliferation and differentiation in rosetted retinospheroids, which are retina-like spheres reaggregated in the complete absence of retinal pigmented epithelium from dissociated retinal cells of 6-day-old chick embryos in a rotation culture system. In spheroids raised in the absence of retinal pigmented epithelium (controls), acetylcholinesterase was expressed in cells of an inner nuclear-like layer and their neuropil matrices. Moreover, the ratio between rods and cones was found to be approximately normal throughout the spheroid. When spheroids were cultured in the presence of retinal pigmented epithelium monolayers, cell proliferation in spheroids as determined by BrdU labelling was significantly increased and extended for 1 week, while acetylcholinesterase protein levels and specific activities in homogenates were decreased to approximately 30%. At the same time, opsin immunoreactivity was completely suppressed within the spheroid and appeared slowly in cells around its periphery; i.e. the proportion of rhodopsin-positive cells decreased from 14 to 3%. This study reveals that the retinal pigmented epithelium in vitro sustains cell proliferation but inhibits the differentiation of acetylcholinesterase-positive cells and of photoreceptors.

Acetylcholinesterase↗
PubMed1996

Formation of synaptic specializations in the inner plexiform layer of the developing chick retina.

The development of synapse-like specializations was investigated in the inner plexiform layer of the developing chick retina by using light and electron microscopy. Six monoclonal antibodies, directed against glycine and gamma-aminobutyric acid (GABA)A receptor subunits, the intracellular receptor-associated protein gephyrin, synaptotagmin, and synaptophysin were used to determine the initial appearance and distribution of their antigens. Synaptophysin and synaptotagmin immunoreactivity was detected in the retina concurrent with the formation of the inner plexiform layer at embryonic day 7. This early appearance before synaptic differentiation, together with the transient expression of synaptotagmin immunoreactivity in the synapse-free optic fiber layer, suggests that in the developing central nervous system (CNS) these proteins are not confined to synapses. The first immunofluorescence signal detected with specific antibodies against the beta 2 and beta 3-subunits of the GABAA receptor, the glycine receptor, and gephyrin appeared at embryonic day 12. In contrast, the alpha 1-subunit of the adult-type glycine receptor heteromeric complex was detectable only at later stages of development, after embryonic day 16, suggesting a change in the subunit composition of some glycine receptor complexes. The staining was clearly punctate, indicating the clustering of the alpha 1-subunit at synapses. Electron microscopic investigation revealed the first postsynaptic densities and active zones in the inner plexiform layer of the retina at embryonic day 12. These results reveal different patterns of development for the investigated pre- and postsynaptic proteins and indicate a parallel appearance of gephyrin, glycine receptor, and the beta 2 and beta 3-subunits of the GABAA receptor with the first synaptic specializations in the inner plexiform layer of the developing chick retina.

Animals↗
PubMed1976

[Plasma and urinary CEA-assay in patients with urological tumours (author's transl)].

Plasma and urinary carcino-embryonic antigen (CEA) assays were performed in 151 patients with urological tumours. CEA measurement is unreliable in renal cell carcinoma and carcinoma of the prostate. However, CEA-assays permit the diagnosis of bladder tumours. The test is particularly useful in the followup and therapeutic control of patients with carcinoma of the bladder.

Adenocarcinoma↗
PubMed1975

[Age-dependent biochemical studies on the extrarenal effect of furosemid (author's transl)].

The present study investigated the activities of lysosomal enzymes of the liver after administration of Furosemid. 10 weeks and 1-year old male albino rats were treated with 40 mg Furosemid for 4 subsequent days. According to the method devised by de Duve a sediment rich in lysosomes was produced by fractionated centrifugation and subsequently the enzyme activity of beta-glucuronidase, beta-acetylglucosaminidase, cathepsin D and a collagenolytic enzyme was measured in the sediment as well as in the corresponding lysosomal supernatant. The protein content served as a reference for the enzyme activities. In addition, we investigated the activities of cytoplasmic enzymes such as GOT, GPT, gamma-GT and the alkaline phosphatase. The enzyme activity changes were age-dependent. With Furosemid treatment the activities of beta-glucuronidase and cathepsin D increased in the lysosomal supernatant and the lysosomal sediment of the 1-year old rats, whereas the activities of the collagenolytic enzyme increased in the lysosomal sediment of the same group. In the lysosomal sediment of the 10-weeks old rats a decrease of beta-glucuronidase, beta-acetylglucosaminidase and cathepsin D was observed. These results are discussed in the light of reports from the literature.

Age Factors↗