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Biomedical subjects

M Frese

Publications and source records attributed to M Frese.

At least 19 recordsLinked to original sources
PubMed2005

Effects of a combinations of emodepside and praziquantel on parasites of reptiles and rodents.

A new combination of two anthelmintic compounds containing emodepside and praziquantel (Profender, Bayer AG, Levekusen, Germany) was tested in pet rodents and reptiles. Topical application of the two compounds led to the quick disappearance of nematodes and cestodes from a broad spectrum of hosts including mice, jirds, snakes, anole lizards, turtles, monitor lizards, etc. In reptiles the dosage had to be increased, since the thick outer layer of the epidermis hinders the penetration of the compounds. In animals with an extremely thick epidermis (e.g. monitor lizards, leguans) the new product was applied under the armpits.

Administration, Topical↗
PubMed2001

Interferon-induced rat Mx proteins confer resistance to Rift Valley fever virus and other arthropod-borne viruses.

Mx proteins belong to the interferon (IFN)-induced antiviral defense. The rat genome contains three Mx genes, ratMx1, ratMx2, and ratMx3. The Mx gene products differ in their subcellular localization and antiviral specificity. The nuclear ratMx1 protein confers resistance to influenza A virus, and the cytoplasmic ratMx2 is active against vesicular stomatitis virus (VSV), whereas the cytoplasmic ratMx3 protein is antivirally inactive. To investigate the antiviral potential of the rat Mx proteins against arboviruses, a phylogenetically diverse group of viruses that frequently infect rodents, we studied the replication of LaCrosse virus (LACV). Rift Valley fever virus (RVFV) (both family Bunyaviridae), and Thogoto virus (THOV) (family Orthomyxoviridae). To that end, we used transfected Vero cells constitutively expressing one of the rat Mx proteins. We observed that the antiviral activity of rat Mx proteins against these arboviruses correlates with their intracellular localization: ratMx1 is active against THOV, which replicates in the nucleus, whereas ratMx2 inhibits bunyaviruses that replicate in the cytoplasm. The results indicate that rats have evolved two Mx proteins to efficiently control viruses with different replication strategies.

Animals↗
PubMed2000

Constitutive expression of interferon-induced human MxA protein in transgenic tobacco plants does not confer resistance to a variety of RNA viruses.

MxA is a key component in the interferon-induced antiviral defense in humans. After viral infections, MxA is rapidly induced and accumulates in the cytoplasm. The multiplication of many RNA viruses, including all bunyaviruses tested so far, is inhibited by MxA. These findings prompted us to express MxA in plants in an attempt to create resistance to tospoviruses. Here, we report the generation of transgenic tobacco plants that constitutively express MxA under the control of the 35 S cauliflower mosaic virus promotor. Northern and western blot analysis confirmed the expression of MxA in several transgenic plant lines. MxA expression had no obvious detrimental effects on plant growth and fertility. However, challenge experiments with tomato spotted wilt virus, tomato chlorotic spot virus, and groundnut ringspot virus revealed no increased resistance of MxA-transgenic tobacco plants to tospovirus infections. Neither was the multiplication of tobacco mosaic virus, cucumber mosaic virus and potato virus Y inhibited in MxA-transgenic plants. The results indicate that the expression of human MxA alone does not enhance virus resistance in planta.

GTP-Binding Proteins↗
PubMed2000

The temporal factor of change in stressor-strain relationships: a growth curve model on a longitudinal study in east Germany.

Several theoretical models describing how stressor-strain relationships unfold in time (e.g., M. Frese & D. Zapf, 1988) were tested with a longitudinal study, with 6 measurement waves, using multivariate latent growth curve models. The latent growth curve model made it possible to decompose trait and state components of strains and to show that both trait and state components are affected by work stressors. Because East Germany constitutes a high-change environment, it is an appropriate setting in which to study the relationship between work stressors and strains. The results showed that both the state and trait components of strains were affected by stressors. For example, individual trends in uncertainty (stressor) and worrying (strain) were related, whereas worrying also showed a short-term relationship with time pressure (another stressor). In particular, the decomposition into trait and state components was only possible with the growth curve method that was used.

Adolescent↗
PubMed1999

Social support as a moderator of the relationship between work stressors and psychological dysfunctioning: a longitudinal study with objective measures.

The match hypothesis proposed by S. Cohen and T. A. Wills (1985) is extended, and the buffer effect of social support is tested within a longitudinal study with objective measures (N = 90 male blue-collar workers in the German metal industry). Stressors at work were ascertained by observers and a variant of a peer rating. Psychological, physical, and social stressors at work and leisure time stressors were ascertained. The dependent variables of dysfunctioning were psychosomatic complaints, depression, irritation/strain, and (social) anxiety. There were moderator effects of social support on the relationship between stressors and psychological dysfunctioning. Results are in line with the match hypothesis as social stressors and socially oriented aspects of psychological dysfunctioning were affected most strongly.

Adaptation, Psychological↗
PubMed1999

Human MxA protein protects mice lacking a functional alpha/beta interferon system against La crosse virus and other lethal viral infections.

The human MxA protein is part of the antiviral state induced by alpha/beta interferon (IFN-alpha/beta). MxA inhibits the multiplication of several RNA viruses in cell culture. However, its antiviral potential in vivo has not yet been fully explored. We have generated MxA-transgenic mice that lack a functional IFN system by crossing MxA-transgenic mice constitutively expressing MxA with genetically targeted (knockout) mice lacking the beta subunit of the IFN-alpha/beta receptor (IFNAR-1(-/-) mice). These mice are an ideal animal model to investigate the unique antiviral activity of human MxA in vivo, because they are unable to express other IFN-induced proteins. Here, we show that MxA confers resistance to Thogoto virus, La Crosse virus, and Semliki Forest virus. No Thogoto virus progeny was detectable in MxA-transgenic mice, indicating an efficient block of virus replication at the primary site of infection. In the case of La Crosse virus, MxA restricted invasion of the central nervous system. In contrast, Semliki Forest virus multiplication in the brain was detectable in both MxA-expressing and nonexpressing IFNAR-1(-/-) mice. However, viral titers were clearly reduced in MxA-transgenic mice. Our results demonstrate that MxA does not need the help of other IFN-induced proteins for activity but is a powerful antiviral agent on its own. Moreover, the results suggest that MxA may protect humans from potential fatal infections by La Crosse virus and other viral pathogens.

Alphavirus Infections↗
PubMed1998

Mx proteins: mediators of innate resistance to RNA viruses.

Mx proteins are interferon-induced members of the dynamin superfamily of large guanosine triphosphatases. These proteins have attracted attention because some display antiviral activity against pathogenic RNA viruses, for example against members of the orthomyxovirus (influenzavirus) family or the bunyavirus family. Transfected cells and transgenic mice expressing Mx proteins are highly resistant to Mx-sensitive viruses, demonstrating that Mx proteins are powerful antiviral agents. In humans, synthesis of MxA is observed during self-limiting viral infections and may thus promote recovery from disease.

Animals↗
PubMed1997

Mx1 sensitivity: Batken virus is an orthomyxovirus closely related to Dhori virus.

Batken virus, isolated from mosquitoes and ticks, was tentatively classified as a member of the family Bunyaviridae. Here we show that Batken virus is inhibited by the interferon-induced Mx1 protein of mice which selectively blocks the growth of orthomyxoviruses, including Thogoto and Dhori viruses. Furthermore, we show that Batken virus multiplication is characterized by accumulation of viral proteins in the nucleus and by budding of viral particles from the cell surface. Serological cross-reactions between Batken and Dhori viruses revealed a phylogenetic relationship of these viruses, as previously also proposed by D. K. Lvov. Fragments of the Batken virus glycoprotein and nucleoprotein genes were amplified by RT-PCR. The deduced amino acid sequences were similar to the corresponding Dhori virus sequences. Therefore, Batken virus should be classified into the newly established genus Thogotovirus of the family Orthomyxoviridae. Finally, our results demonstrate that Mx1 susceptibility of orthomyxoviruses is a reliable marker in the hunt for new family members.

Amino Acid Sequence↗
PubMed1996

Longitudinal studies in organizational stress research: a review of the literature with reference to methodological issues.

Demonstrating causal relationships has been of particular importance in organizational stress research. Longitudinal studies are typically suggested to overcome problems of reversed causation and third variables (e.g., social desirability and negative affectivity). This article reviews the empirical longitudinal literature and discusses designs and statistical methods used in these studies. Forty-three longitudinal field reports on organizational stress were identified. Most of the investigations used a 2-wave panel design and a hierarchical multiple regression approach. Six studies with 3 and more waves were found. About 50% of the studies analyzed potential strain-stressor (reversed causation) relationships. In about 33% of the studies there was some evidence of reverse causation. The power of longitudinal studies to rule out third variable explanations was not realized in many studies. Procedures of how to analyze longitudinal data are suggested.

Humans↗
PubMed1996

Inhibition of bunyaviruses, phleboviruses, and hantaviruses by human MxA protein.

Viruses of the Bunyaviridae family cause a variety of diseases ranging from uncomplicated fever to potentially lethal encephalitis and hemorrhagic fever. Little is known about the factors determining pathogenicity in the vertebrate host. Interferons have been reported to be inhibitory, but their mode of action against members of the Bunyaviridae has not yet been elucidated. The interferon-induced MxA protein encoded on human chromosome 21 is a large GTPase with antiviral activity against distinct negative-strand RNA viruses, notably influenza viruses. Here we show that MxA inhibits representative members of the Bunyaviridae family by interacting with an early step of virus replication. When constitutively expressed in stably transfected Vero cells, MxA prevented the accumulation of viral transcripts and proteins of Hantaan virus (genus Hantavirus). Other members of the family such as La Crosse virus (genus Bunyavirus) and Rift Valley fever virus and sandfly fever virus (both genus Phlebovirus) were likewise inhibited, and virus titers were reduced up to 10(4)-fold. Our data indicate that humans have evolved a mechanism of controlling these viruses irrespective of differences in viral coding strategies.

3T3 Cells↗
PubMed1995

Mx1 but not MxA confers resistance against tick-borne Dhori virus in mice.

The interferon-induced nuclear Mx1 protein is responsible for innate resistance of mice to influenza virus. It has been unclear why mice are equipped with a powerful and specific defense mechanism against influenza viruses for which they are not natural hosts. Here, we show that Dhori virus, an influenza-like virus transmitted by ticks and known to infect small mammals, is sensitive to the Mx1 resistance mechanism. Influenza virus-susceptible BALB/c and C57BL/6 mice (lacking a functional Mx1 gene) developed severe disease symptoms and died within a few days after intraperitoneal infection with a lethal dose of Dhori virus. In contrast, Mx1(+)-congenic, influenza virus-resistant BALB.A2G-Mx1 and B6.A2G-Mx1 mice remained healthy and survived. The Mx1 resistance phenotype was expressed in cultured peritoneal macrophages and interferon-treated embryonic cells obtained from these mice. Moreover, stable lines of transfected mouse 3T3 cells constitutively expressing Mx1 protein were protected from Dhori virus infection. The MxA protein of human cells shows a high degree of sequence similarity to Mx1 but, unlike Mx1, inhibits a broad range of RNA viruses. Transgenic mice that permanently express the human MxA protein in various organs became resistant to infection with Thogoto virus but remained fully susceptible to Dhori virus. These in vivo results show that DHO virus is unique in being resistant to human MxA but susceptible to mouse Mx1 protein. They further indicate that the Mx1 system functions as a potent defense mechanism against tick-borne influenza-like viruses in mice.

3T3 Cells↗
PubMed1995

Tick-borne thogoto virus infection in mice is inhibited by the orthomyxovirus resistance gene product Mx1.

We show that tick-transmitted Thogoto virus is sensitive to interferon-induced nuclear Mx1 protein, which is known for its specific antiviral action against orthomyxoviruses. Influenza virus-susceptible BALB/c mice (lacking a functional Mx1 gene) developed severe disease symptoms and died within days after intracerebral or intraperitoneal infection with a lethal challenge dose of Thogoto virus. In contrast, Mx1-positive congenic, influenza virus-resistant BALB.A2G-Mx1 mice remained healthy and survived. Likewise, A2G, congenic B6.A2G-Mx1 and CBA.T9-Mx1 mice (derived from influenza virus-resistant wild mice) as well as Mx1-transgenic 979 mice proved to be resistant. Peritoneal macrophages and interferon-treated embryo cells from resistant mice exhibited the same resistance phenotype in vitro. Moreover, stable lines of transfected mouse 3T3 cells that constitutively express Mx1 protein showed increased resistance to Thogoto virus infection. We conclude that an Mx1-sensitive step has been conserved during evolution of orthomyxoviruses and suggest that the Mx1 gene in rodents may serve to combat infections by influenza virus-like arboviruses.

Animals↗
PubMed1995

Human MxA protein inhibits tick-borne Thogoto virus but not Dhori virus.

Thogoto and Dhori viruses are tick-borne orthomyxoviruses infecting humans and livestock in Africa, Asia, and Europe. Here, we show that human MxA protein is an efficient inhibitor of Thogoto virus but is inactive against Dhori virus. When expressed in the cytoplasm of stably transfected cell lines, MxA protein interfered with the accumulation of Thogoto viral RNA and proteins. Likewise, MxA(R645), a mutant MxA protein known to be active against influenza virus but inactive against vesicular stomatitis virus, was equally efficient in blocking Thogoto virus growth. Hence, a common antiviral mechanism that is distinct from the antiviral action against vesicular stomatitis virus may operate against both influenza virus and Thogoto virus. When moved to the nucleus with the help of a foreign nuclear transport signal, MxA(R645) remained active against Thogoto virus, indicating that a nuclear step of virus replication was inhibited. In contrast, Dhori virus was not affected by wild-type or mutant MxA protein, indicating substantial differences between these two tick-transmitted orthomyxoviruses. Human MxB protein had no antiviral activity against either virus.

Animals↗
PubMed1995

Enhanced virus resistance of transgenic mice expressing the human MxA protein.

MxA is a GTPase that accumulates to high levels in the cytoplasm of interferon-treated human cells. Expression of MxA cDNA confers to transfected cell lines a high degree of resistance against several RNA viruses, including influenza, measles, vesicular stomatitis, and Thogoto viruses. We have now generated transgenic mice that express MxA cDNA in the brain and other organs under the control of a constitutive promoter. Embryonic fibroblasts derived from the transgenic mice were nonpermissive for Thogoto virus and showed reduced susceptibility for influenza A and vesicular stomatitis viruses. The transgenic animals survived challenges with high doses of Thogoto virus by the intracerebral or intraperitoneal route. Furthermore, the transgenic mice were more resistant than their nontransgenic littermates to intracerebral infections with influenza A and vesicular stomatitis viruses. These results demonstrate that MxA is a powerful antiviral agent in vivo, indicating that it may protect humans from the deleterious effects of infections with certain viral pathogens.

Animals↗
PubMed1992

Neuronal and glial gamma-aminobutyric acid+ transporters are distinct proteins.

In the central nervous system, two subtypes of sodium- and chloride-coupled GABA transporter exist. One is sensitive to ACHC, the other to beta-alanine. They are thought to be of neuronal and glial origin, respectively. GABA transport in membrane vesicles derived from astroglial cells was found to be sodium- and chloride-dependent, electrogenic and much more sensitive to beta-alanine than to ACHC. Immunoblotting with antibodies directed against a variety of sequences of the ACHC-sensitive transporter indicated that none of these epitopes was shared by the glial transporter.

Amino Acids↗
PubMed1990

[Modifying factors of the relationship between stress at work and state of health].

Resources, particularly social support and control have been shown to moderate the stress process in various studies. Low social support or low control lead to a higher impact of stressors on psychological and psychosomatic dysfunctioning. Various mechanisms are suggested how resources may have an impact on the stress process.

Adaptation, Psychological↗
PubMed1987

Prolonged unemployment and depression in older workers: a longitudinal study of intervening variables.

In this study, unemployed blue-collar workers over the age of 45 (N = 51) filled out a questionnaire in 1975 and in 1977. It was shown that prolonged unemployment or re-unemployment leads to depression, reduced hope, and financial problems, although none of these factors leads to prolonged unemployment. Being employed or retired leads to a reduction of depression and financial problems. Problems associated with the daily hassles of unemployment, such as financial problems and disappointed hope play a role in the development of depression with prolonged unemployment. Potential third variables that could cause both unemployment and depression--such as internal/external control, passivity, sickness, and age--do not affect the effect of unemployment on depression.

Depression↗