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Biomedical subjects

M Marschall

Publications and source records attributed to M Marschall.

34 records · Page 2Linked to original sources
PubMed1995

The persistent variant of influenza C virus carries one characteristic point mutation in RNA segment 1.

Influenza C/ Ann Arbor/1/50-pi(C/AA-pi) virus causes persistent infections in MDCK and Wi38 cells, but sets limited, wild-type like infections in other cells. Concluding that persistence itself it dependent on the host environment, we determined the nucleotide sequence of the C/AA-pi analogous gene to the basic polymerase 2 (PB2) of influenza A virus, which is known to be a determinant for the host range. C/AA-pi and the parental wild-type virus (C/AA-wt) have 16 nucleotides in common that are different to a previously published PB2 sequence (C/JJ/50). These variations, which are probably due to divergent passages histories, are scattered along the sequence and are partially found in another published isolate (C/Berlin/1/85). One single mutation, however, is unique to the persistent variant. Nucleotide 28 mutated from T to C which leads to a change of amino acid 3 from Leu to Phe. This substitution is stably associated with the persistent phenotype throughout multiple passages in different cells lines and eggs and cannot be found in any other influenza C viruses.

Base Sequence↗
PubMed1995

Effect of work station design on sitting posture in young children.

The purpose of the study was to compare muscular activity levels and sitting posture displayed by 10 children (mean age = 4.7 years) when performing tracing tasks while seated at a traditional work station (level desk top, 5 degrees backward sloping seat) and at an ergonomically designed work station (15 degrees sloping desk top, 15 degrees forward sloping seat). EMG profiles of latissimus dorsi (LD), erector spine (ES), and superior trapezius (ST) were sampled using Medi-trace disposable surface electrodes for 10 min on the non-dominant side. Muscle activity was sampled (1000 Hz) every 2 min for 5000 ms while the subjects performed the tracing tasks at each station. Raw EMG signals of the five trials for each muscle were processed by removing signal offset, full-wave rectification, and integration. The subjects' posture was monitored from a lateral view using a Panasonic VHS video camera while the children were seated at each work station. Neck flexion angle and the angle between the torso and thigh (hip angle) were manually sampled from the video images each 1 min as an indication of the posture adopted by the subjects during the tracing tasks. Use of t-tests for dependent means indicated that there was no significant difference in either mean ES or ST muscle activity as a function of work station design. However, subjects demonstrated significantly less LD activity when seated at the ergonomic work station (mean = 20.9 V ms) compared with the traditional work station (mean = 24.4 V ms, t = -2.88, p = 0.018).(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗
PubMed1995

Lower limb salvage by microvascular free-tissue transfer in patients with homozygous sickle cell disease.

Chronic, excruciatingly painful ulcerations of the lower extremities in patients with homozygous sickle cell anemia (HbSS) present a frustrating clinical problem for the reconstructive surgeon. Despite adequate wound care and skin grafting, there is a dismally high incidence of recurrence. Furthermore, there is a paucity of reliable locoregional fasciocutaneous, muscle, and myocutaneous flaps in the ankle region. Free-tissue transfer has become the procedure of choice for reconstruction of the lower third of the leg. However, in sickle cell anemia, does the obligate period of flap ischemia inherent in free-tissue transfer inevitably doom a flap to failure? We present our multidisciplinary experience over 55 months with five free flaps in four homozygous sickle cell anemia patients 21 to 38 years old who had chronic nonhealing leg ulcerations. Special perioperative measures included exchange transfusion to lower hemoglobin S to below 30 percent, maintaining the hematocrit at 31 to 35 percent, intraoperative flap washout and perfusion with warm heparinized saline-dextran solution, administration of dextran and aspirin intraoperatively and postoperatively, prophylactic topical and systemic anti-Pseudomonas antibiotics, supplemental oxygen, and warm ambient room temperature. Flaps included the latissimus dorsi muscle (two patients), the temporoparietal fascia (one patient), and "split" omentum for bilateral lower limb salvage (one patient). Successful free-tissue transfer was accomplished in all patients. One patient suffered gradual partial occlusion of the microcirculation by sickled erythrocytes following a transient hypothermic, hypotensive episode. Sufficient flap tissue survived to permit skin grafting with an excellent result. Pseudomonas infection occurred in two patients (three flaps).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Negatively cis-acting elements in the distal part of the promoter of Epstein-Barr virus trans-activator gene BZLF1.

Epstein-Barr virus (EBV) replicates in a latent or a lytic way in the infected organism, depending on the type and level of differentiation of the host cell. The switch between latency and lytic replication was previously shown, for Burkitt's lymphoma cell lines, to depend on the viral BZLF1 gene product. Protein-DNA assays were used to identify the cis-acting elements that represent the link between regulating signal transduction pathways and the viral cascade of gene expression. Specific binding of proteins to several sites of the BZLF1 promoter during latency was shown. Induction of the lytic cycle by stimulation with 12-O-tetradecanoyl-phorbol 13-acetate abolished the binding of these proteins to the distal promoter (positions -227 to -551), suggesting a functional role for the down-regulation of promoter activity during latency. Computer analysis identified a multiply repeated sequence motif, HI, in this region and exonuclease III footprints confirmed that these sites act as specific protein recognition sites. Using a set of reporter plasmids we were able to demonstrate a negative regulatory effect of the HI motif in some B lymphoid cell lines, in contrast to epithelial HeLa cells. The HI silencer elements are different from other silencer elements described so far in respect of their sequence and protein-binding pattern during the activation of BZLF1.

Base Sequence↗
PubMed1994

Persistent influenza C virus possesses distinct functional properties due to a modified HEF glycoprotein.

A model of long term viral persistence has been established by selecting a spontaneous mutant strain of influenza C/Ann Arbor/1/50 virus in a permanent carrier culture of MDCK cells. Infectivity and cell tropism are mainly determined by the multifunctional viral membrane glycoprotein (HEF). HEF analysis was aimed at identifying a putative correlation between sequence and function, i.e. receptor binding, enzymatic activity, antigenicity and rate of infection. The current experimental picture is summarized by the following findings: (i) C/Ann Arbor/1/50 persistent virus carries a modified receptor-binding sequence, (ii) receptor-binding activity is altered, as indicated by a higher efficiency in recognizing low amounts of the receptor determinant N-acetyl-9-O-acetylneuraminic acid, (iii) direct attachment to cell surfaces differs from that of wild-type virus, as measured by slower kinetics of viral elution, (iv) receptor-destroying enzymatic activity is diminished, (v) characteristic features of virion surface morphology are altered or unstable, (vi) persistent-type HEF epitopes are distinguishable by monoclonal antibodies from wild-type and (vii) viral infectivity is intensified for cells bearing a low number of receptors. The sum of these changes highlights a structurally and functionally modified HEF glycoprotein that allows long term viral persistence. In order to clarify which of the described points are required for the persistent viral phenotype, a working concept is presented.

Animals↗
PubMed1994

Different activation of Epstein-Barr virus immediate-early and early genes in Burkitt lymphoma cells and lymphoblastoid cell lines.

Specific expression of the Epstein-Barr virus (EBV) immediate-early and early gene products Zta, Rta, I'ta, and MSta by a recombinant vaccinia virus system allowed us to analyze the first steps in the induction of the lytic cycle in EBV-infected Burkitt lymphoma (BL) cells and lymphoblastoid cell lines (LCLs). Significant differences in the induction of early genes were found between these cell types: whereas in BL cells the trans activator Zta was found to induce key steps of the early lytic cycle, only minor activities of Zta were noted in LCLs. Contrary to Zta, the trans activator Rta was found to be highly effective in LCLs. These observations suggest that Rta may play an important role in the activation of the early lytic cycle in LCLs, although it cannot be activated by Zta. The latter may be a reason for the lower tendency of LCLs to switch into the lytic cycle compared with BL cells or differentiated epithelial cells.

B-Lymphocytes↗
PubMed1993

The lytic transition of Epstein-Barr virus is imitated by recombinant B-cells.

Lytic transition of Epstein-Barr virus (EBV) is initiated by distinct immediate early regulators of the viral cycle, in synchronization to temporary, permissive conditions during host cell differentiation. We developed eukaryotic vectors suitable to imitate the processes involved in lytic transition in cell culture systems. Two stable B cell lines were established: R59Z activator cells were used to induce lytic EBV expression in a constitutive manner by the production of the BZLF 1 trans-activator (Zta). R7-57 reporter cells, on the other hand, signaled induced activity of the lytic origin of EBV replication (ori Lyt). Different modes, like chemical induction, lytic superinfection with EBV and single gene trans-activation converted the recombinant ori Lyt element in R7-57 reporter cells. BZLF 1, transiently expressed in R7-57 reporter cells, was the only EBV trans-activator found, sufficient in inducing the viral lytic cycle. Basing on these experiments, trans-cellular activation of EBV was tested by cocultivation of BZLF 1-expressing R59Z activator cells with the R7-57 reporter line. No lytic effect on the reporter cells could be measured, neither by cocultivation of activator cells nor by coincubation of BZLF 1-containing cell lysates. Latency breaking activity, however, was transferred from activator to reporter cells when active, exogenous virus was added. The cell system described in these experiments provides a tool for the detection of EBV reactivation and demonstrates the potential of the lytic regulatory gene BZLF 1.

Animals↗
PubMed1993

Productive and non-productive phases during long-term persistence of influenza C virus.

Persistent infection with a variant of influenza C/Ann Arbor/1/50 virus in MDCK cells has been previously reported. However, the precise molecular mechanism of persistence is still unknown. We show that the release of active progeny virus, as tested for by haemagglutination and acetylesterase profiles, does not take place in freshly seeded MDCK cells. Productive virus replication occurs simultaneously with massive production of structural proteins as shown by immunoprecipitation and immunofluorescence. PCR for the HEF structural protein-encoding segment 4 revealed that positive-sense RNA is present only during virus multiplication whereas negative-sense RNA appears to be constantly detectable. In this study we give initial evidence that influenza C virus can persist in the form of its genomic minus strand RNA, and plus strand transcription, protein synthesis and virus replication remain restricted to productive phases.

Animals↗
PubMed1991

Expression of proteins encoded by Epstein-Barr virus trans-activator genes depends on the differentiation of epithelial cells in oral hairy leukoplakia.

The Epstein-Barr virus (EBV) immediate early gene product BZLF1 was localized by indirect immunofluorescence to the cytoplasm of the basal epithelial layer at the lateral border and dorsum of tongue in human immunodeficiency virus-infected and -seronegative patients. Two biopsies of oral hairy leukoplakia revealed a sporadic cytoplasmic staining of the BHRF1 and BRLF1 gene products in the basal epithelial layer. The widespread presence of BZLF1 in the basal epithelial layer indicated that this cell layer contained EBV DNA and was probably directly infected by EBV. Nuclear localization of the immediate early and early gene products BZLF1, BHRF1, BRLF1, and BMLF1 was limited to oral hairy leukoplakia in human immunodeficiency virus-seropositive patients and revealed a codistribution with the virus capsid antigen. Our results indicate that the epithelium of the tongue is a potential reservoir for EBV and that in heavily immunocompromised patients EBV may move from the cytoplasm to the nucleus with increasing differentiation and be coactivated there during the terminal differentiation of epithelial cells at the lateral border and dorsum of tongue.

Cell Differentiation↗
PubMed1991

The BI'LF4 trans-activator of Epstein-Barr virus is modulated by type and differentiation of the host cell.

We have analyzed the activity and regulated expression of a new Epstein-Barr virus (EBV) trans-activator (I'ta) encoded by left reading frame 4 (BI'LF4) of the BamHI I'fragment. The gene was detected in all genomes of established EBV strains and individual isolates, with the exception of B95-8, where the type-specific deletion of this open reading frame is tolerated in vitro. Specific trans-activation of two EBV promoters (early MS and I'ta promoter) could be shown in cotransfection assays. The I'ta product affected autoactivation but had no influence on heterologous target promoters. The I'ta promoter segment was shown to be costimulated in the process of host cell differentiation in the absence of other EBV gene products. Expression of the reading frame in bacteria identified a 48-kDa protein as a stable gene product. I'ta-specific antibodies were detected in sera from EBV-positive persons (nasopharyngeal carcinoma). When expressed with suitable eucaryotic vectors, a nuclear protein could be immunostained in transfected cells. Our experiments suggest a cell type-specific requirement for I'ta in the lytic cycle of EBV at a determined differentiation stage of the host cell.

Animals↗
PubMed1989

Hepatitis B virus surface antigen as a reporter of promoter activity.

The coding sequence for the hepatitis B virus surface antigen (HBsAg) was used as a new reporter gene for studies on eukaryotic promoter activity and upstream regulatory sequences. The data observed in transfection assays were comparable to results obtained with conventional chloramphenicol acetyltransferase (CAT) assays, as was demonstrated using various transcriptional regulation sequences. The expression of HBsAg as a reporter protein offered some advantages: (i) In transient expression assays, a time course of promoter activity depending on variable culture conditions could be monitored over a period of time, since the HBsAg was secreted into the culture supernatant. (ii) Evaluation of HBsAg from supernatant aliquots and quantification of the corresponding promoter activities could be performed easily, using the very sensitive and readily available diagnostic HBsAg kits. (iii) In contrast to the conventional CAT assay, the cells remained available for further tests, e.g., Western blot, immunofluorescence or transcript analysis. Characteristics of several Epstein-Barr virus (EBV) promoters, depending on the virus state of EBV-positive B-cells (latency, chemical induction, lytic superinfection, trans-activation), were assayed using the HBsAg reporter system.

Animals↗
PubMed1989

Identification of proteins encoded by Epstein-Barr virus trans-activator genes.

Specific antisera were generated to characterize Epstein-Barr virus proteins reported to have trans-activating properties. Open reading frame BRLF1 was found to be expressed in two modifications in vivo, with molecular sizes ranging from 94 to 98 kilodaltons (kDa) depending on the cell line, whereas only one protein (Raji cells, 96 kDa) was detected by in vitro translation. Open reading frame BZLF1 encoded polypeptides of 38 and 35 kDa and additional smaller forms. A BZLF1-encoded 30-kDa protein could be detected under conditions in which expression was restricted to immediate early genes. Nuclear localization could be detected under conditions in which expression was restricted to immediate early genes. Nuclear localization could be shown for the proteins derived from reading frames BZLF1 and BMLF1. BMLF1 expression gave a heterogeneous protein pattern, with molecular sizes between 45 and 70 kDa, including a predominant 60-kDa protein detected in different B-cell lines.

Antibodies, Viral↗
PubMed1982

[Tension pneumocephalus: a possible complication of posterior fossa craniotomy in the sitting position].

The authors describe a case of subdural tension pneumocephalus complicating the early postoperative course after posterior fossa craniotomy in the sitting position. This complication was promptly recognized and was treated successfully by allowing the compressed air to escape through frontal burr holes. A brief review of the recent literature is presented and the possible pathological mechanism is discussed. Emphasis is given to means of early detection and measures of prevention.

Child↗