Tick-borne encephalitis in Austrian dogs.
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Animals↗
Biomedical subjects
H Holzmann
Publications and source records attributed to H Holzmann.
Correlation between ELISA, hemagglutination inhibition, and neutralization tests after vaccination against tick-borne encephalitis.
The significance of IgG antibody levels determined by a binding assay (ELISA) was investigated as a surrogate marker for the presence of neutralizing and hemagglutination inhibiting antibodies in sera from individuals vaccinated against tick-borne encephalitis (TBE). To assess the extent of interference by flavivirus cross-reactive antibodies, sera from persons with a proven or suspected history of other flavivirus infections and/or vaccinations were also examined. An excellent and highly significant correlation was found between ELISA IgG units and the antibody titers obtained by the hemagglutination inhibition (HI) as well as by the neutralization test (NT), provided that there was no other exposure to flavivirus antigens except TBE vaccination. Yellow fever vaccination and/or dengue virus infections induced significant levels of antibodies reactive in the TBE ELISA and HI test, which did not exhibit, however, neutralizing activity against TBE virus. The phenomenon and problem of "original antigenic sin" was demonstrated in a TBE vaccinee with a history of previous flavivirus infections. TBE vaccination first induced a booster reaction resulting in a rise in the level of cross-reactive antibodies only, whereas TBE virus-neutralizing antibodies became detectable only after the third vaccination. It is concluded that the level of IgG antibodies determined by ELISA is a good marker for predicting the presence of neutralizing antibodies after TBE vaccination, but only in the absence of flavivirus cross-reactive antibodies. Otherwise, a neutralization assay is necessary for assessing immunity.
Animals↗
[Psoriatic osteoarthropathy and bone scintigraphy].
Psoriasis is a generalized disease that affects bone as well as skin. Three patterns of bone involvement can be differentiated in psoriatic arthritis distal, central, and distal combined with central. Distal involvement is more specific for psoriatic arthritis, with radial and/or transverse involvement of the distal interphalangeal joints. The progression dynamic and the pattern of distribution are different from those pattern of rheumatoid arthritis: psoriatic arthritis originates in the periarticular bone and extends towards the synovia, whereas in rheumatoid arthritis it extends in the opposite direction. In psoriatic arthritis anterior chest wall syndrome, insertion tendinopathies, and localized or diffuse bone disease are often observed. Bone scintigraphy is more sensitive in the diagnosis of psoriatic bone involvement than clinical examination or conventional radiological imaging, allowing earlier diagnosis through the visualization and documentation of specific patterns and presence of disease in multiple sites. It also allows more discriminating selection of subsequent X-ray examinations to limit radiation exposure. Thus, bone scintigraphy is now the most important diagnostic tool in the assessment of psoriatic arthritis.
Arthritis, Psoriatic↗
Characterization and complete genome sequences of high- and low- virulence variants of tick-borne encephalitis virus.
The entire genomic sequences of two strains (Hypr and 263) of the flavivirus tick-borne encephalitis (TBE) virus differing in virulence from the prototypic strain Neudoerfl were determined. Strain Hypr is a human isolate of TBE virus with a high laboratory passage history which exhibits a significantly higher neuro-invasiveness in mice compared to the prototype strain. Strain 263 is a low-passage tick-isolate with a temperature-sensitive and attenuated phenotype. Except for the heterogeneous 3' non-coding regions strains Hypr and 263 share, respectively, 97.2% and 97.6% nucleotide sequence identity with strain Neudoerfl, and differ by a total of 42 and 36 amino acids from the prototypic strain. Of these, only 12 amino acids for each of the two strains represent non-conservative differences unique to an individual strain and some of these are located at positions highly conserved among flaviviruses. Based on these observations, the potential biological significance of particular sequence differences is discussed in the context of the current knowledge about molecular determinants of flavivirus virulence.
Animals↗
Transcription of melanogenesis enzymes in melanocytes: dependence upon culture conditions and co-cultivation with keratinocytes.
Eumelanogenesis of human skin melanocytes requires at least three enzymes: tyrosinase, TRP 1, and TRP 2. The regulation of these enzymes on transcriptional level was detected in a semiquantitative attempt. The total RNA of melanocytes was reverse-transcripted and followed by a PCR with degenerated primers for all three enzymes. The amplification products were related to each other densitometrically. We examined five different culture conditions: 1) melanocytes in a popular phorbolester containing F-10-medium, 2) melanocytes in a co-culture medium with EGF, 3) melanocytes in a co-culture medium with high calcium, 4) melanocytes co-cultured with keratinocytes in EGF containing co-culture medium, and 5) melanocytes co-cultured with keratinocytes in co-culture medium with high calcium. Melanocytes cultured in phorbolester containing F-10-medium featured transcripts of tyrosinase, TRP 1, and TRP 2 in the ratio 45:45:10. The same results were obtained for melanocytes co-cultured with keratinocytes under the two different culture conditions. In melanocytes cultured alone in co-culture media only TRP 1-transcripts were present. It is likely that under co-culture conditions a keratinocyte-derived factor supports the transcription of all three enzymes. For melanocytes in the phorbolester-containing melanocyte medium a proteinkinase C dependent regulation of transcription seems possible.
Coculture Techniques↗
[The hereditary form of pincer nail syndrome].
Over a period of six months a 41-year-old woman had recurrent acute paronychia of both large toes. On inspection all toes had pincer nails. She had no metabolic abnormalities and no history of trauma. Onychomykosis was excluded. Under conduction anaesthesia an Emmert plasty (Haneke's modification) was performed: it revealed osteocartilaginous exostoses in the area of nail gryposis. Subsequent radiological examination showed distally directed exostoses on the tibial side of all toe phalanges, which is an obligatory criterion for the hereditary form of the pincer nail syndrome.
Acute Disease↗
Tick-borne encephalitis virus envelope protein E-specific monoclonal antibodies for the study of low pH-induced conformational changes and immature virions.
A set of ten monoconal antibodies (mabs) specific for the tick-borne encephalitis (TBE) virus envelope protein E were prepared and characterized with respect to their functional activities, the location of their binding sites on protein E and the involvement of their epitopes in acid pH-induced conformational changes and interactions with the precursor to the membrane protein (prM) in immature virions. The majority of these mabs mapped to the previously defined antigenic domain A. All of the mabs recognize parts of the E protein which undergo low pH-induced structural rearrangements believed to be necessary for the fusion activity of the virus, and six of the mabs define epitopes which are affected by the prM-E interaction in immature virions. They are therefore of potential value as specific reagents for studying the structure and function of protein E, as well as the function of the prM-E association. Five of the mabs exhibited neutralizing activity, and can therefore be used for the selection of escape mutants.
Animals↗
Recombinant and virion-derived soluble and particulate immunogens for vaccination against tick-borne encephalitis.
Using different forms of the envelope glycoprotein E from tick-borne encephalitis virus we investigated the influence of physical and antigenic structure on the efficacy of vaccination. Different protein E-containing preparations were either derived from purified virions or were produced as recombinant proteins in COS cells. These included soluble dimeric forms (virion-derived protein E dimers with and without membrane anchor; recombinant protein E dimers without membrane anchor), micellar aggregates of protein E (rosettes), and recombinant subviral particles (RSPs). The structural differences between these immunogens were verified by sedimentation analysis, immunoblotting and epitope mapping with a panel of monoclonal antibodies. Specific immunogenicities were determined in mice in comparison to formalin-inactivated whole virus. Rosettes and RSPs were excellent immunogens and exhibited similar efficacies as inactivated virus in terms of antibody induction and protection against challenge, whereas all of the soluble forms were much less immunogenic. These data emphasize the importance of the immunogen's antigenic and physical structure for an effective stimulation of the immune system and indicate that RSPs represent an excellent candidate for a recombinant vaccine against tick-borne encephalitis.
Animals↗
In vitro studies on the immunomodulating effects of polypodium leucotomos extract on human leukocyte fractions.
The in vitro effect of Anapsos, a water based extract of the naturally occurring fern Polypodium leucotomos (calagualine), on human leukocyte fractions was investigated. Calagualine inhibited interleukin-2 secretion and concanavalin A (Con A) stimulated proliferation of T-lymphocytes in a concentration dependent manner. In contrast, a greatly enhanced secretion of IL-1 alpha, IL-1 beta and tumor necrosis factor alpha was induced suggesting a stimulation of monocytes and dendritic cells also present in this system. Endotoxin induced stimulation was excluded. Also in the absence of Con A, calagualine stimulated cytokine production. The presented data show for the first time that calagualine exerts an immunomodulating effect on leukocyte fractions, paving the way for further detailed studies related to possible clinical efficacy.
Adjuvants, Immunologic↗
[Incidence of hepatitis E in Austria].
Sera from 1274 patients were tested for IgG antibodies to hepatitis E using the newly developed Abbott Enzyme immunoassay (EIA). All tested patients had previously proved to be negative for hepatitis A, B, and C. 180 suffered from hepatitis, in the remaining 1094 the hepatitis tests were done for other reasons (presurgical, pregnancy etc.). No clear-cut distinction was found between positive and negative sera in the Abbott ELISA: Therefore the cut-off value was set somewhat higher than as stated by the producer. Thus, 15 (8.3%) of the hepatitis patients and 25 (2.3%) of the remaining patients were positive. Epidemiological data were available from 12 positive patients. Seven had been in countries endemic for hepatitis E, however 5-all Austrian citizens-had never visited such an area. These data can be explained either by unspecific (false) positive tests or by endemic occurrence of hepatitis E in Austria, which, however, seems unlikely.
Austria↗
Structural changes and functional control of the tick-borne encephalitis virus glycoprotein E by the heterodimeric association with protein prM.
We have used tick-borne encephalitis virus to study the involvement of acidic compartments during the entry and release phases of flavivirus infection and to elucidate the role of protein prM in immature virions. Elevation of the pH in acidic intracellular compartments by either bafilyomycin A1, a specific inhibitor of the vacuolar type H(+)-ATPase or by NH4Cl had a strong inhibitory effect during virus penetration and also prevented the cleavage of prM when added in the late phase of the viral life cycle. In the latter case the release of virus particles was not impaired. These immature (prM-containing) virions exhibited a 20- to 50-fold lower specific infectivity and HA activity than mature virions and in contrast to these did not undergo low pH-triggered aggregation. The presence of prM also affected the binding of monoclonal antibodies to protein E, especially at sites which have been shown to undergo acid pH-induced conformational changes in mature virions. Crosslinking, solubilization, and sedimentation analyses revealed the existence of prM-E heterooligomeric complexes, suggesting that the function of prM is to protect protein E from undergoing the irreversible conformational changes in acidic compartments of the secretory pathway that are necessary for triggering fusion activity in the endosome during virus entry.
Ammonium Chloride↗
The interactions of the flavivirus envelope proteins: implications for virus entry and release.
Viral membrane proteins play an important role in the assembly and disassembly of enveloped viruses. Oligomerization and proteolytic cleavage events are involved in controlling the functions of these proteins during virus entry and release. Using tick-borne encephalitis virus as a model we have studied the role of the flavivirus envelope proteins E and prM/M in these processes. Experiments with acidotropic agents provide evidence that the virus is taken up by receptor-mediated endocytosis and that the acidic pH in endosomes plays an important role for virus entry. The envelope glycoprotein E undergoes irreversible conformational changes at acidic pH, as indicated by the loss of several monoclonal antibody-defined epitopes, which coincide with the viral fusion activity in vitro. Sedimentation analysis reveals that these conformational changes lead to aggregation of virus particles, apparently by the exposure of hydrophobic sequence elements. None of these features are exhibited by immature virions containing E and prM rather than E and M. Detergent solubilization, sedimentation, and crosslinking experiments provide evidence that prM forms a complex with protein E which prevents the conformational changes necessary for fusion activity. The functional role of prM before its endoproteolytic cleavage by a cellular protease thus seems to be the protection of protein E from acid-inactivation during its passage through acidic trans Golgi vesicles in the course of virus release.
Acids↗
[Cell and tissue culture models in dermatology. The Frankfurt Center of Dermatology establishes models].
In the course of the Third Frankfurt Talks, for the first time a congress in dermatology was dedicated exclusively to cell and tissue culture models. The complexity of a whole organ, in this case the skin, could be reduced to single aspects without losing the holistic context. Ways of managing this were discussed on an interdisciplinary level by dermatologists, physiologists, pharmacologists and biologists. The results are also expected to be useful to the clinician. Focus points of in vitro investigations for dermatology are wound closure models and the use of in vitro skin for transplantation in the therapy of non-healing ulcers and vitiligo. As an alternative to animal experiments, cultures of human cells are gaining increasing influence in drug testing. The effect of glucocorticosteroids on normal skin fibroblasts, keratinocytes and permanent cell lines is discussed as an example, and in vitro models of diseases such as psoriasis are established. Additionally, basic events such as differentiation and ageing have been modelled in cell cultures of melanocytes and keratinocytes. Mechanical stress, UV radiation and nicotine are discussed as inductors.
Cell Differentiation↗
[Lung manifestation of progressive systemic scleroderma. Computerized tomographic findings].
Progressive systemic scleroderma (PSS) is caused by generalized connective tissue disorder. The most frequent visceral manifestations are pulmonary and oesophageal involvement. Early detection of such visceral manifestations, which are sometimes life-limiting, is of paramount importance in any diagnostic procedures. The sensitivity of the methods differs and depends on the stage of the disease. Modified high-resolution computed tomographic scans (HRCT) were obtained in 28 patients with early forms of PSS and showed pulmonary involvement in 79% and signs of oesophageal involvement in 54%. HRCT is much more sensitive than chest radiography, lung scintigraphy and lung function tests even at an early stage of the disease. Classification of PSS should take account of the clinical type of sclerosis and of immunological and other parameters of prognostic importance.
Adult↗
Levels of dopachrome tautomerase in human melanocytes cultured in vitro.
Several reports have been published about the level of activity and possible functions of dopachrome tautomerase (DCT) in mouse melanoma cells. Data about the levels of this activity in human melanocytes in culture are still scarce, and, as far as we know, a comparison between mouse and human melanocytes, or between normal and malignant melanocytes, has never been published. We have measured the tyrosinase and DCT activities, as well as the melanin content, in mouse Cloudman melanoma cells, two lines of human melanoma, and three lines of normal human melanocytes obtained from fetal skin. Although more cell lines should be tested to draw a general conclusion, our results suggest that normal melanocytes contained much higher tyrosinase activity and melanin content but lower DCT activity than malignant melanocytes. The two lines of human melanoma cells tested had lower levels of DCT activity than Cloudman melanoma cells. Finally, the low level of DCT activity found in normal human melanocytes cultured in vitro cannot be explained by any of the necessary stimulatory factors added to the cell culture media.
Animals↗
Osteoarthropathia psoriatica of one leg: a manifestation of somatic mosaicism?
A psoriatic osteoarthropathy localized in the left quadrant of a male patient is described. Diagnosis was made on the basis of bone scintigraphy (specific distribution pattern) and histological evaluation of a bone biopsy. There is no indication of psoriasis in the patient's family. Nor is there an association to psoriasis-typical HLA markers. Psoriasis of the skin has not been found. Environmental factors, including a Köbner phenomenon on the skeleton resulting from a trauma 13 years ago (hallux rigidus operation), are discussed in connection with this manifestation. The genetic aspects of this unusual localization are considered.
Arthritis, Psoriatic↗
Reactions of human keratinocytes in vitro after application of nicotine.
Nicotine is rapidly taken up by human keratinocytes (HaCaT cells) and after 3 h the uptake is approximately 50% of maximum. Cotinine, a metabolite of nicotine, was detected, thus demonstrating the metabolism of nicotine in HaCaT cells. Low nicotine concentrations (0.1-200 micrograms/ml) did not influence the incorporation rate of thymidine into DNA or amino acids into proteins. Inhibition of DNA and protein synthesis was only observed at concentrations > 200 micrograms/ml. After application of 400 micrograms/ml nicotine, the cells were vacuolated. This process was reversed after nicotine withdrawal. At low nicotine concentrations, no changes in microtubules and actin filaments could be detected. However, in the presence of nicotine (1-10 micrograms/ml), keratin filaments showed a more orderly pattern that controls, and the expression of the suprabasal keratins 1 and 10/11 was induced and increased according to the concentration of nicotine. The number of cornified envelopes also increased markedly. Nicotine concentrations > 100 micrograms/ml led to a disarrangement of keratin filaments and to a decrease in keratin expression and cornified envelope formation. Our results suggest that nicotine at concentrations up to 100 micrograms/ml is not an irritant but may induce cornification of the skin.
Cell Differentiation↗
Coexistence of morphea and systemic sclerosis.
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Female↗