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C Wolff

Publications and source records attributed to C Wolff.

At least 19 recordsLinked to original sources
PubMed1998

A novel EspA-associated surface organelle of enteropathogenic Escherichia coli involved in protein translocation into epithelial cells.

Enteropathogenic Escherichia coli (EPEC), like many bacterial pathogens, employ a type III secretion system to deliver effector proteins across the bacterial cell. In EPEC, four proteins are known to be exported by a type III secretion system_EspA, EspB and EspD required for subversion of host cell signal transduction pathways and a translocated intimin receptor (Tir) protein (formerly Hp90) which is tyrosine-phosphorylated following transfer to the host cell to become a receptor for intimin-mediated intimate attachment and 'attaching and effacing' (A/E) lesion formation. The structural basis for protein translocation has yet to be fully elucidated for any type III secretion system. Here, we describe a novel EspA-containing filamentous organelle that is present on the bacterial surface during the early stage of A/E lesion formation, forms a physical bridge between the bacterium and the infected eukaryotic cell surface and is required for the translocation of EspB into infected epithelial cells.

Adenylate Cyclase Toxin↗
PubMed1998

Preattentive processing of auditory spatial information in humans.

Auditory event-related potentials were recorded from reading subjects to frequent and infrequent tones. Frequent tones presented by a loudspeaker in front of the subject were interspersed with infrequent tones delivered either by one of the symmetrically-placed lateral loudspeakers, or by both lateral loudspeakers simultaneously. This latter sound was perceived as originating from a spacious source in the direction of the central loudspeaker. A sizable mismatch negativity (MMN) and P3a were elicited by all three infrequent stimuli, suggesting that infrequent changes in the direction or perceived spaciousness of the sound source were preattentively detected. In addition, a dissociation between the MMN and P3a amplitudes was found: whereas lateral deviants elicited a larger P3a than the simultaneous left + right deviant, the MMN amplitude was approximately equal for all three deviants.

Acoustic Stimulation↗
PubMed1998

Interaction of enteropathogenic Escherichia coli with host epithelial cells.

Enteropathogenic Escherichia coli (EPEC) causes severe diarrhea in young children. Upon infection, EPEC induces the assembly of highly organized pedestal-like actin structures in host epithelial cells. All the EPEC genes that are involved in inducing formation of actin pedestals are located in a unique 35 kbp chromosomal pathogenicity island, termed LEE. These genes include the sep genes that encode components of type III protein secretion system, and genes that encode proteins secreted by this system, the esp genes. This protein secretion system is activated upon contact with the host cell, resulting in increased secretion of Esp proteins. Some of these Esp proteins from the translocation apparatus while others are translocated into the cytoplasm of the host cell. Concerted activity of the LEE genes including the eae, esp and the sep genes is needed to trigger signal transduction in the host cell which results in formation of an actin pedestal.

Diarrhea↗
PubMed1998

A caudal homologue in the short germ band beetle Tribolium shows similarities to both, the Drosophila and the vertebrate caudal expression patterns.

We have isolated a homologue to the Drosophila caudal (cad) gene from the flour beetle Tribolium castaneum and have studied its expression pattern. The Tribolium caudal (Tc-cad) gene arrangement is unusual in that there is a partial duplication of the gene resulting in alternative transcripts with identical 5'-exons, but different 3'-exons encoding two different homeoboxes. Expression analysis was done by whole-mount in situ hybridization and by staining with an antibody raised against the N-terminal part of the protein that is common to both transcripts. At early stages we observe a homogeneously distributed maternal mRNA which is initially also translated throughout the embryo. A little later, a posterior to anterior CAD protein gradient is formed, very similar to that in Drosophila. However, because of the differences in the fate map between Drosophila and Tribolium, the CAD protein expression at blastoderm stage covers the prospective head and thoracic region and not the abdomen as in Drosophila. Expression of Tc-cad in the prospective abdomen is only seen during further germband growth where it becomes restricted to the growth zone in which the segments are formed. This expression is very similar to the growth zone expression in the somitogenic region seen for cad homologues in vertebrates. After the completion of the segmentation process Tc-cad expression becomes confined to a terminal stripe which resembles a similar stripe at late blastoderm stages in Drosophila.

Alternative Splicing↗
PubMed1998

Behavioral and electrophysiological effects of task-irrelevant sound change: a new distraction paradigm.

A distraction paradigm was utilized that is suited to yield reliable auditory distraction on an individual level even with rather small frequency deviances (7%). Distraction to these tiny deviants was achieved by embedding task-relevant aspects and task-irrelevant, distracting aspects of stimulation into the same perceptual object. Event-related potential (ERP) and behavioral effects of this newly developed paradigm were determined. Subjects received tones that could be of short or long duration equiprobably. They were instructed to press a response button to long-duration tones (targets). In oddball blocks, tones could be of standard frequency or of low-probability (p=0.1), deviant frequency. The task-irrelevant frequency deviants elicited MMN, N2b, and P3a components, and caused impoverished behavioral performance to targets. The usage of tiny distractors permits an interpretation of auditory distraction in terms of attention switching due to a particular memory-related change-detection process. On the basis of the results from an additional condition in which tones were of 10 different frequencies (involving those frequencies which served as standard and deviant in oddball blocks), it is argued that one important prerequisite for linking the neural mechanisms reflected in change-related brain waves to behavioral distraction effects may be regarded as fulfilled. The robustness of the distraction effects to tiny deviations was confirmed in two control experiments.

Acoustic Stimulation↗
PubMed1998

Protein translocation into host epithelial cells by infecting enteropathogenic Escherichia coli.

Enteropathogenic Escherichia coli (EPEC) causes diarrhoea in young children. EPEC induces the formation of actin pedestal in infected epithelial cells. A type III protein secretion system and several proteins that are secreted by this system, including EspB, are involved in inducing the formation of the actin pedestals. We have demonstrated that contact of EPEC with HeLa cells is associated with the induction of production and secretion of EspB. Shortly after infection, EPEC initiates translocation of EspB, and EspB fused to the CyaA reporter protein (EspB-CyaA), into the host cell. The translocated EspB was distributed between the membrane and the cytoplasm of the host cell. Translocation was strongly promoted by attachment of EPEC to the host cell, and both attachment factors of EPEC, intimin and the bundle-forming pili, were needed for full translocation efficiency. Translocation and secretion of EspB and EspB-CyaA were abolished in mutants deficient in components of the type III protein secretion system, including sepA and sepB mutants. EspB-CyaA was secreted but not translocated by an espB mutant. These results indicate that EspB is both translocated and required for protein translocation by EPEC.

Adenylate Cyclase Toxin↗
PubMed1998

Regulation of the Tribolium homologues of caudal and hunchback in Drosophila: evidence for maternal gradient systems in a short germ embryo.

In short germ embryos, the germ rudiment forms at the posterior ventral side of the egg, while the anterior-dorsal region becomes the extra-embryonic serosa. It is difficult to see how an anterior gradient like that of bicoid in Drosophila could in these embryos be directly involved in patterning of the germ rudiment. Moreover, since it has not yet been possible to recover a bicoid homologue from any species outside the diptera, it has been speculated that the anterior bicoid gradient could be a late addition during insect evolution. We addressed this question by analysing the regulation of potential target genes of bicoid in the short germ embryo of Tribolium castaneum. We demonstrate that homologues of caudal and hunchback from Tribolium are regulated by Drosophila bicoid. In Drosophila, maternal caudal RNA is translationally repressed by bicoid. We find that Tribolium caudal RNA is also translationally repressed by bicoid, when it is transferred into Drosophila embryos under a maternal promoter. This strongly suggests that a functional bicoid homologue must exist in Tribolium. The second target gene, hunchback, is transcriptionally activated by bicoid in Drosophila. Transfer of the regulatory region of Tribolium hunchback into Drosophila also results in regulation by early maternal factors, including bicoid, but in a pattern that is more reminiscent of Tribolium hunchback expression, namely in two early blastoderm domains. Using enhancer mapping constructs and footprinting, we show that caudal activates the posterior of these domains via a specific promoter. Our experiments suggest that a major event in the evolutionary transition from short to long germ embryogenesis was the switch from activation of the hunchback gap domain by caudal to direct activation by bicoid. This regulatory switch can explain how this domain shifted from a posterior location in short germ embryos to its anterior position in long germ insects, and it also suggest how an anterior gradient can pattern the germ rudiment in short germ embryos, i.e. by regulating the expression of caudal.

Animals↗
PubMed1998

[Acquired characteristics of porphyria cutanea tarda in patients infected with hepatitis C virus].

BACKGROUND: Porphyria cutanea tarda (PCT) is due to a partial defect of hepatic uroporphyrinogen decarboxylase (URO-D). In the hereditary form, both hepatic and erythrocytic enzymes are altered, whereas in the acquired form, only the hepatic enzyme fails. There is a high prevalence of hepatitis C virus infection in patients with PCT, specially in those without family history of the disease. AIM: To study erythrocytic URO-D activity in order to find out whether hepatitis C virus infection is associated to the acquired form of PCT or unveils an inactive hereditary form. PATIENTS AND METHODS: URO-D activity was measured in red blood cells of normal controls, hepatitis C virus carriers without symptoms of PCT and patients with PCT, with and without family history of the disease, with and without anti hepatitis C virus antibodies. RESULTS: URO-D activity was similar in normal controls, patients with chronic liver disease associated to hepatitis C virus, and in patients with PCT without family history of the disease with and without hepatitis C virus antibodies. URO-D activity was lower in patients with PCT and family history of the disease, with and without hepatitis C virus antibodies. CONCLUSIONS: PCT in patients with hepatitis C virus infection is due to an acquired alteration of hepatic URO-D. Hepatitis C virus does not modify erythrocytic URO-D.

Adult↗
PubMed1997

Fast preattentive processing of location: a functional basis for selective listening in humans.

Spatial separation of sound sources provides a primary cue for selecting relevant from irrelevant acoustic input. This competence for selective listening is important in every-day life, when several concurrent sound sources are simultaneously active. The present study demonstrated a temporal advantage in the preattentive processing of location information relative to frequency information. This was indicated by shorter latency of the mismatch negativity (MMN), generated by the brain's automatic detection of a sound change, to a location change than to a frequency change. Results suggest that the superior role of spatial location for selective listening may be due to faster automatic encoding of spatial information into the neural representations underlying attentional selection.

Adult↗
PubMed1997

Anti-arthritic activity of hydroxamic acid-based pseudopeptide inhibitors of matrix metalloproteinases and TNF alpha processing.

OBJECTIVE AND DESIGN: The effects of two hydroxamate inhibitors of metalloproteinase and tumor necrosis factor alpha (TNF alpha) processing on endotoxin-induced plasma TNF alpha and arthritic lesions in adjuvant-induced arthritic (AA) rats were determined. MATERIAL AND TREATMENT: BB-1101 and BB-1433 were administered orally twice daily to AA Lewis rats with an established disease (days 13 to 22). AA rats (day 16) or normal rats were injected with bacterial endotoxin and plasma levels of TNF alpha were also determined. METHODS: Hindpaw swelling was measured plethysmographically. Bone degradation was determined by radiography and bone mineral densitometry. TNF alpha was quantified using a sandwich ELISA. RESULTS: The hydroxamic-acid pseudopeptides inhibited plasma. TNF alpha levels in vivo and significantly reduced swelling and bone degradation of the tibiotarsal joints of AA rats in the range of 10-50 mg/kg given orally (p < 0.01 by Student's t-test). CONCLUSIONS: Thus, these novel compounds offer a new disease modifying therapy for arthritis and the results also suggest that inhibition of TNF alpha production may contribute, at least in part, to their anti-arthritic activity.

Animals↗
PubMed1997

[Results of elastic plate osteosynthesis of simple femoral shaft fractures in polytraumatized patients. An alternative procedure].

Primary medullary nailing of femoral fractures is burdened by the risk of central and pulmonary complications in patients with polytrauma, especially in conjunction with craniocerebral or thoracic trauma. This also applies to unreamed medullary nailing. Primary treatment with external fixation necessitates secondary surgery with an altered procedure, the timing of which is not predictable. Plate osteosynthesis with anatomical repositioning of the fragments and rigid fixation is a technically demanding procedure, but can lead to fragment necrosis due to fragment denudation. In a prospective study conducted from 1 September 1994 to 30 June 1996 on 17 polytraumatized patients (average ISS:30 points), simple femoral stem fractures (A-1 to B-3 of the AO-classification) were stabilized by elastic plate osteosynthesis using biological technique. While cautiously preserving the periosteal and muscle connections to the bone, a plate is inserted as a bridge without any interfragmentary compression. At least two to four holes are left free in the center of the plate. This allows micro-movements in the fracture gap without the risk of material fatigue. All of the fractures were immediately stabilized on the day of the accident. In four patients with severe craniocerebral trauma or manifest shock, the procedure was changed to plate osteosynthesis after application of primary external fixation. Secondary injuries (joint and pelvic fractures or craniocerebral trauma) delayed early loading in 12 cases. Four patients were mobilized postoperatively under partial loading. A fixation callus was radiologically detectable on average 6 weeks after surgery. This often allowed additional loading, depending on the secondary injuries. Full loading was possible after 14 weeks. Complications included one case of surgery-related malpositioning, one soft-tissue infection, one case of plate detachment after a fall and one case of periosseous calcification. There were no cases of bone infections or pseudoarthroses. Elastic plate osteosynthesis is thus a conservative osteosynthesis procedure with a low complication rate in polytraumatized patients, even in those with simple femoral fractures.

Adolescent↗
PubMed1997

Interaction with a lipid membrane: a key step in bacterial toxins virulence.

Bacterial toxins are secreted as soluble proteins. However, they have to interact with a cell lipid membrane either to permeabilize the cells (pore forming toxins) or to enter into the cytosol to express their enzymatic activity (translocation toxins). The aim of this review is to suggest that the strategies developed by toxins to insert in a lipid membrane is mediated by their structure. Two categories, which contains both pore forming and translocation toxins, are emerging: alpha helical proteins containing hydrophobic domains and beta sheets proteins in which no hydrophobicity can be clearly detected. The first category would rather interact with the membrane through multi-spanning helical domains whereas the second category would form a beta barrel in the membrane.

Amino Acid Sequence↗
PubMed1997

Association of Ureaplasma urealyticum biovars with clinical outcome for neonates, obstetric patients, and gynecological patients with pelvic inflammatory disease.

In this prospective study, the prevalence of the two Ureaplasma urealyticum biovars, parvo and T960, was determined in pregnant women and in gynecological patients colonized by ureaplasmas. Furthermore, we investigated the association of these biovars with gynecological complications and adverse pregnancy outcome. Isolates of U. urealyticum from 254 women were biotyped by a PCR method recently developed. The parvo biovar was found in 81% (206 of 254) of the patients, and the T960 biovar was found in 30% (76 of 254) of the patients; 6% (14 of 254) of the women were coinfected. Identical biovars were detected in mothers and their infants. Serial isolations or cultures from different sampling sites of the same individual revealed the same biovar. T960 was dominant in patients with pelvic inflammatory disease (57%) and patients who had had a miscarriage (42%), showed a higher rate of tetracycline resistance than did parvo isolates (55 versus 18%), and seemed to have more adverse effects on pregnancy outcome with regard to birth weight (2,500 versus 1,720 g), gestational age (35 versus 30 weeks), and preterm delivery (35 versus 77%).

Female↗
PubMed1997

[Porphyrin excretion in patients with chronic hepatitis C virus infection].

BACKGROUND: The high prevalence of chronic hepatitis C virus infection in patients with porphyria cutanea tarda, specially in those without family history of the disease, suggests that this could be an acquired disease and one of the most frequent extra hepatic manifestations of hepatitis C virus infection. AIM: To study the excretion of porphyrins and its precursors in cirrhotic patients with and without hepatitis C virus infection. PATIENTS AND METHODS: Eighteen patients with cirrhosis Child-Pough A, eight infected with hepatitis C virus, were studied. Urinary excretion of [symbol see text] aminolevulinic acid, porphobilinogen, coproporphyrins, uroporphyrins and fecal excretion of coproporphyrins and protoporphyrins were measured. Red blood cell protoporphyrin was also measured. RESULTS: There were no differences in the measured parameters between patients with or without hepatitis C virus infection. No patient had uroporphyrin excretion values over the normal range. Some patients had slight elevations in some parameters, but always below the values observed in porphyrias. CONCLUSIONS: In these group of patients, hepatitis C virus infection of its associated liver disease, do not cause detectable alterations in porphyrin metabolism.

Adult↗
PubMed1996

Mismatch response of the human brain to changes in sound location.

WE investigated whether the enhanced negativity of the human event-related brain potential elicited by changes in auditory lateralization is due to a higher-order change-detection process or whether it can be explained exclusively in terms of selective sensory adaptation. Infrequent changes in lateralization of a repetitive standard tone, generated by changes in interaural time differences, elicited a frontocentrally distributed negative brain wave in the 100-250 ms range relative to stimulus onset. This brain wave was also elicited when possible sensory adaptation was prevented by controlling for the state of refractoriness of location-specific neurones. The results demonstrate that changes in lateralization elicit a genuine mismatch negativity (MMN), indicating the activity of an automatic higher-order change-detection process.

Adult↗
PubMed1996

Significance of human cytomegalovirus DNA detection in immunocompromised heart transplant patients.

Peripheral blood samples (n= 1240), obtained at variable intervals from 483 heart transplantation (HTx patients under immunosuppressive therapy, and blood samples (n=1013) obtained upon blood donation from 1013 healthy anti-human cytomegalovirus (HCMV) positive blood donors, were tested for HCMV DNA by nested polymerase chain reaction (PCR). The detection limit of the nested PCR was determined to be less than 10 copies of the plasmid pRR 47, containing the HCMV immediate early gene. HCMV DNA was detected in 79 of 483 HTx patient (17%). To the contrary' HCMV DNA was only detected in 1 of 1013 anti-HCMV positive, healthy blood donors (0.1%). This PCR positive donor had recently contracted a primary HCMV infection. The rate of HCMV PCR positive immunosuppressed HTx patients in our study was lower than the rate of HCMV PCR positive healthy blood donors in previous reports in the literature. Blood samples (269 from 117 HTx patients) were assayed for HCMV DNA in peripheral blood leukocytes, HCMV DNA in plasma, and HCMV tegument protein 65 kDa (pp 65 antigen). Three laboratory diagnostic patterns were observed and related to clinical findings: (1) HCMV DNA only in leukocytes was observed in 26 patients, 7 of whom had HCMV disease, 5 of whom had graft rejection, and 14 of whom had no specific symptoms; (2) HCMV DNA both in leukocytes and in plasma (viremia) was observed in 3 patients, who were all symptomatic with HCMV disease; (3) HCMV DNA in leukocytes and in plasma (viremia) and pp 65 antigen were observed in 13 patients, all of whom were symptomatic (10 patients had HCMV disease, and 3 patients had graft rejection). A similar sequence of diagnostic patterns was observed in all symptomatic HCMV infections and reactivations in this study: HCMV DNA appeared first in peripheral blood leukocytes, then also in plasma, followed by pp 65 antigen detectable in peripheral blood leukocytes. Upon clinical recovery, these findings disappeared in reverse order. However, HCMV DNA remained detectable in peripheral blood leukocytes for several weeks. The detection of HCMV DNA in the peripheral blood is an exception, not the rule, even in severely immunosuppressed HTx patients. It indicates a pathological condition, albeit without clinical symptoms in some patients, and it is the earliest signal of HCMV replication. Of 42 patients in whom HCMV DNA was initially detected only in peripheral blood leukocytes, 16 patients progressed into viremia. Thus, HCMV-specific PCR performed on nucleic acid extracts from lysed peripheral blood is an appropriate method for the monitoring of HCMV infections in immunosuppressed HTx patients.

Antibodies, Viral↗