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Biomedical subjects

H J Thiel

Publications and source records attributed to H J Thiel.

At least 19 recordsLinked to original sources
PubMed1992

Specific transcellular staining of microglia in the adult rat after traumatic degeneration of carbocyanine-filled retinal ganglion cells.

The present work was undertaken to assess the fate of ganglion cell debris in the axotomized retina of adult rats and employed a new technique to label phagocytosing microglia via the internalized material. In the main experiment, transection axotomy was performed on the intraorbital segment of the optic nerve, and a fast-transported, vital fluorescent styryl dye (4Di-10ASP) was deposited at the ocular stump of the nerve in order to pre-label retrogradely the ganglion cells destined to die because of the axotomy. Optic nerve transection resulted in progressive degradation of ganglion cell axons, perikarya, and dendrites within the retina and in release of fluorescent material, which was then incorporated into cells identified as microglia. No other retinal cells stained, although astrocytes and Müller's cells also responded to neuron degeneration by accumulating glial fibrillary acidic protein. Incorporation of labelled material into microglia topo-chronologically paralleled the ganglion cell degeneration starting within the optic fibre layer (OFL) and proceeding towards the ganglion cell layer (GCL) and the inner plexiform layer (IPL) of the affected retina. Long-term labelling of microglia monitored up to 3 months after optic nerve transection indicated that labelled microglial cells persisted within the retina. Microglia displayed a strong territorial arrangement within the GCL and IPL, and staggered, bilaminated distribution in both layers. These studies directly prove that microglia in the retina can be transcellularly labelled during traumatic degeneration of ganglion cells. The findings suggest that microglial cells play an important role in axotomy-induced wound healing and removal of cell debris.

Animals↗
PubMed1992

Rearrangement of viral sequences in cytopathogenic pestiviruses.

Two cytopathogenic isolates of bovine viral diarrhea virus (cpBVDV) have been analyzed. For both viruses two regions of their genomic RNAs were found to be duplicated and rearranged. The viral genomes contain a small duplicated element (SD) derived from the genomic 5' end far downstream of its original context. This sequence is followed by a larger duplication which encompasses the region coding for the protein p80(LD), a molecular marker for cpBVDV. The SD element codes for the viral protease p20. In the case of the viruses analyzed here the aminoterminus of p80 is generated by autoproteolytic removal of the preceding SD-encoded protease. For one of the cpBVDV isolates a specific fusion protein (p28) could be identified which is composed of p20 and part of p10, another viral protein. Molecular characterization of the respective noncytopathogenic counterpart revealed that duplication and rearrangement of sequences as well as the expression of p28 and p80 are specific for the cytopathogenic virus.

Amino Acid Sequence↗
PubMed1992

Proteins encoded in the 5' region of the pestivirus genome--considerations concerning taxonomy.

The first protein encoded within the pestivirus open reading frame is a nonstructural protein which removes itself from the polyprotein by autoproteolytic cleavage. The following nucleocapsid protein ends just before a putative signal sequence preceding three glycosylated proteins. All three glycoproteins are part of the viral envelope and exist in the form of disulfide-linked dimers. Pestiviruses have recently been reclassified as members of the family Flaviviridae which now comprises three genera, namely flavivirus, hepatitis C virus group and pestivirus. All members of the family have certain characteristics in common like the overall genome organization and the strategy of gene expression. Major differences exist, however, between the genera; the most obvious ones concern proteins encoded in the 5' region of the respective genomes.

Animals↗
PubMed1992

Haemorrhagic disease of lagomorphs: evidence for a calicivirus.

Studies on the aetiological agents of rabbit haemorrhagic disease (RHD) and European brown hare syndrome show that the viruses responsible for these infections can be placed in the family Caliciviridae. Established members of this group are vesicular exanthema virus (prototype), San Miguel sea lion virus and feline calcivirus. The human hepatitis E virus and the Norwalk agent may soon be included. The RHD virus genome consists of a positive stranded RNA molecule composed of 7437 nucleotides. A major subgenomic RNA of 2.2 kb, colinear with the 3' end of the genomic RNA, can also be recovered from infected liver tissue, and both RNAs are enclosed within viral capsids formed by a single major protein of approximately 60 kDa. Electron microscopic examination of organ suspensions from diseased animals shows two types of particle; 35-40 nm complete virions have the regularly arranged cup-shaped depressions typical of calcivirus morphology, and 23-25 nm smooth particles resulting from degradation of the outer surface structures of the complete virions.

Animals↗
PubMed1992

[Metastatic eyelid tumors--description of clinical aspects and histology based on three cases].

Clinical findings and histology of secondary lid tumors are described by example of three cases. The rare lid metastases appear mainly in three different patterns. Except cytology, which depends on the primary tumor, their morphology is quite uniform. Lid metastases of a cutaneous melanoma, a contralateral uveal melanoma and, probably reported for the second time, a leiomyosarcoma are presented.

Adult↗
PubMed1992

[125 years ophthalmopathology in Tübingen. Change in the times and spectrum of findings].

The beginning of ophthalmopathological activities at the University Eye Clinic Tübingen, Germany, can be dated back to the year 1868, as at this time the continuous counting of investigated, ophthalmological specimens was started. So the ophthalmopathological department in Tübingen will be 125 years old in 1993. In a review its history is described with particular regard to the first period and the change in the kind and frequence of diagnoses.

Eye Diseases↗
PubMed1992

Pathogenesis of classical swine fever: B-lymphocyte deficiency caused by hog cholera virus.

Hog cholera, also known as classical or European swine fever, is caused by hog cholera virus, a member of the genus Pestivirus. It is shown here that the end stage of lethal infection in the natural host is associated with a dramatic depletion preferentially of B lymphocytes in the circulatory system as well as in lymphoid tissues. Already at the onset of disease, viral replication in lymphoid tissues demarcates the germinal centers, and the viral genome remains localized to that site as the disease progresses even after morphologic disintegration of the follicular structure. A block in B-lymphocyte maturation by infection and destruction of germinal centers is discussed as a key event in the pathogenesis of acute, lethal hog cholera.

Animals↗
PubMed1992

A second envelope glycoprotein mediates neutralization of a pestivirus, hog cholera virus.

Several monoclonal antibodies (MAbs) raised against hog cholera virus (HCV) reacted with the HCV structural glycoprotein gp44/48 and neutralized the virus. The presence of HCV gp44/48 on the viral surface was directly demonstrated by immunogold electron microscopy. Eight anti-HCV gp44/48 MAbs were tested by immunoperoxidase assay against a panel of pestivirus strains. Each MAb showed a distinct pattern of reactivity with HCV strains. It is suggested that the MAbs are well suited for epidemiological investigations of HCV outbreaks.

Animals↗
PubMed1992

[Clinical aspects, follow-up and results of cataract extraction in uveitis].

Over a 5-year period, a consecutive series of 52 eyes in 46 patients with uveitis underwent extracapsular cataract extraction. Twenty-eight of these cases received a posterior chamber intraocular lens (IOL). During an average follow-up of 25 months (range 7 to 58 months) 71% of eyes receiving an IOL achieved postoperatively a visual acuity of 0.5 or better; 54% of aphakic eyes reached this level. Persistent cystoid macular edema limited the visual improvement to 20/200 in 6 patients; none of the patients developed cystoid macular edema postoperatively on clinical observation. Intraocular hypertension occurred postoperatively in 12 eyes, but was limited to a 4-week postoperative period in 9 cases. YAG laser capsulotomy was performed in 2 eyes with opacification of the posterior lens capsule without any further complications. The results suggest that uveitis patients benefit from cataract extraction and in selected cases can tolerate IOL implantation without major complications.

Adolescent↗
PubMed1992

[Ascorbic acid. Cytotoxic effect on cultivated bovine lens epithelium cells].

Ascorbic acid is one of the main components (1.16 mM/l) of the aqueous humor. The molarity of this molecule is 25 times higher than in the plasma of the cow, man or horse. Now the question arises as to which function ascorbic acid has in this extremely high concentration referring to the proliferation of the lens epithelial cells. Thus, the effect of ascorbic acid was investigated upon bovine lens epithelial cells (BLEC) in the range of 0-3 mM/l. These cells were cultivated under various culture conditions (serum-free, serum-containing, aqueous-humor-containing medium) and also incubated with such mitogens as retinal extract (RE), crude endothelial cell growth factor (cECGF), basic fibroblast growth factor (bFGF) or with calcium. In each culture condition 1 mM/l ascorbic acid caused remarkable inhibition of the proliferation of BLEC. Higher concentrations (> 1.5 mM/l) revealed cytotoxic effects. These effects were independent of small variations in the pH value caused by ascorbic acid. In addition, the effect of 2 mM/l ascorbic acid in combination with catalase in a concentration of 500 Um/ml and 1000 Um/ml, respectively, was investigated. It could be shown that catalase is capable of preventing the cytotoxic effect of ascorbic acid. These results show the inhibitory effect of ascorbic acid in its physiological concentration in the proliferation of BLEC.

Animals↗
PubMed1992

[Effect of heparin on proliferation of cultivated bovine lens epithelial cells].

The treatments proposed to date for the prevention of secondary cataract have shown limited efficacy or have not been satisfactory due to ocular toxicity. Since it has been demonstrated that heparin can inhibit the proliferative activity of smooth muscle cells and fibroblasts in vitro and in vivo, we examined the effect of heparin at concentrations ranging from 20 to 200 micrograms/ml on the proliferation of cultured bovine lens epithelial cells (BLEC) under various culture conditions: (1) serum-free medium (SFM); (2) SFM + aqueous humor 1:1; (3) SFM +1 and 10% fetal calf serum; (4) SFM +1% retinal extract; (5) SFM +50 micrograms/ml endothelial cell growth factor; (6) SFM +10 ng/ml epidermal growth factor; (7) SFM +10 ng/ml basic fibroblast growth factor. Heparin caused no cytotoxic effects in any of the experiments. With medium 2 and 3, heparin caused dose-dependent inhibition of cell proliferation at concentrations ranging from 10 to 50 micrograms/ml. Cells cultivated in medium 4-7 with the addition of 50 micrograms/ml heparin revealed increased proliferative activity when compared with the corresponding controls. The antiproliferative activity on BLEC in medium containing aqueous humor suggests that heparin is a valuable tool for the prevention of secondary cataract in vivo.

Animals↗
PubMed1992

[Changes in the invasion front of uveal melanomas].

Central and peripheral cells of 12 uveal melanomas were compared by electron microscopy to determine whether infiltrating melanoma cells have special characteristics (e.g., loss of cell adherence, changes in the cytoskeleton, increase of cell organelles). No significant differences were found. The two theories of tumor invasion ("mechanical" and "locomotive" theory) and the light microscopical findings that occur in the invasion zone of uveal melanomas are discussed.

Choroid↗
PubMed1992

[EGF in therapy of corneal diseases. Principles and possible uses].

Numerous recent research results stress the importance of the epidermal growth factor (EGF) for the growth and differentiation of corneal tissues. EGF, a physiological ingredient in the tears, plays a predominant role in the regeneration of corneal epithelium. Furthermore, EGF has been shown to increase the proliferation and differentiation of corneal keratocytes and endothelial cells. Topically applied EGF significantly enhances both the re-epithelialization of denuded areas and the tear strength of stromal cicatrices. These results may lead to interesting pharmacological management procedures for numerous corneal disorders. Thus, the clinical feasibility of EGF therapy is currently the subject of intensive evaluation. A better understanding of its mode of action, both on the molecular and cellular level, and increasing knowledge of the pharmacokinetics, together with the development of suitable application media, may all make EGF an integral part of the next generation of ophthalmic drugs. This survey reviews basic molecular-pharmacological and biochemical findings on EGF and evaluates its possible value for therapeutical use.

Animals↗
PubMed1992

[The pathologically changed Descemet membrane. Cultivation of human corneal endothelium on transformed membrane].

Corneal endothelial diseases are connected with structural and biochemical changes of Descemet's membrane (DM). Little is known about the possible effects of these changed basement membranes. In the present study we investigated the influence of changed DM on endothelium. Human corneal endothelial cells were cultured on DM of healthy corneas as well as corneas with Fuchs' endothelial dystrophy or bullous keratopathy, and cell growth and morphology were compared. On healthy DM, cells formed a confluent monolayer within 4 days. Cells cultured on Fuchs' DM showed a similar pattern. The polygonal cell pattern was interrupted merely in the area of the guttae, which were covered by cell processes alone. Culturing cells proved to be difficult on DM from corneas with bullous keratopathy. Even though the cells attached to the DM, they did not spread but became spindle shaped and rarely formed intercellular contacts. Even after 7 days no confluent monolayer was established. These results indicate that some though not all pathological DM changes interfere with cell growth.

Adult↗
PubMed1991

Paraproteinemic corneal deposits in plasma cell myeloma.

We treated two patients who had IgG-kappa-light chain monoclonal gammopathy with partially crystalline and partially amorphic corneal deposits. Impairment of vision made keratoplasty necessary for each patient. Histologic examination of the corneal specimens showed deposits that stained positively for Masson's trichrome in all corneal cells. Immunohistochemical tests identified these deposits as IgG-kappa-light chain immunoglobulin fragments. Electron microscopy showed intracellular, rhomboid-shaped deposits enveloped by a membrane. The same deposits appeared in the conjunctival epithelium, within subconjunctival fibrocytes, and in the plasma cells of the bone marrow. Immunoelectrophoresis showed IgG-kappa-light chain fragments in the blood serum, the lacrimal film, and the aqueous humor. This suggests that the intracellular immunoglobulin fragments may have entered the corneal and conjunctival epithelium by way of the lacrimal film, the keratocytes by way of the corneo-scleral limbus vasculature, and the endothelial cells from the aqueous humor.

Aged↗
PubMed1991

Elevated prolactin levels in human aqueous humor of patients with anterior uveitis.

Evidence is accumulating that prolactin (PRL) may play a physiological role in the regulation of humoral and cell-mediated immune responses. On the basis of these observations, we measured levels in the serum and aqueous humor of 28 patients with cataract or anterior uveitis with concomitant cataract. Intraocular concentrations were measured in a range from 0.1 to 3.4 ng/ml. Whereas serum PRL levels failed to show significant differences between the two groups (P = 0.39), intraocular concentrations were significantly higher in uveitis patients (P less than 0.001). The level in aqueous humor did not reflect the serum concentration in either group. To the best of our knowledge, this is the first study measuring PRL concentrations in human aqueous humor.

Adolescent↗