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J Brunner

Publications and source records attributed to J Brunner.

At least 55 records · Page 3Linked to original sources
PubMed1998

Staff attitudes that impede the implementation of behavioral treatment programs.

Staff who have negative attitudes about behavioral treatments are less likely to implement them. Previous research suggests that negative attitudes are associated with staff burnout and perceived collegial support. A path analysis is conducted in this study to determine the direction of these effects. Ninety staff members who work in treatment programs for severely mentally ill adults completed measures of attitudes about behavior therapy, experience with behavior therapy, burnout, and collegial support. Results of the path analysis yielded a model with good fit that confirmed our hypotheses; namely, burnout leads to negative attitudes and experience with behavior therapy yields positive attitudes. Insufficient collegial support leads to negative attitudes through burnout. Implications of these findings for improving the use of behavior treatments in real-world programs are discussed.

Adult↗
PubMed1997

Molecular mechanism of membrane protein integration into the endoplasmic reticulum.

As proteins are integrated into the membrane of the endoplasmic reticulum, some hydrophilic polypeptide segments are transported through the translocation channel, others remain in the cytosol, and hydrophobic transmembrane sequences are released into the lipid phase. We have addressed the molecular mechanism by which these events occur. We demonstrate that both the lumenal and the cytosolic domains of a membrane protein are synthesized while the ribosome is membrane bound, so that even cytosolic domains come in contact with the translocation channel. We also find that, before translation of the protein is terminated, transmembrane sequences can laterally exit the translocation channel and enter the lipid environment. These results have significant implications for the folding and assembly of membrane proteins.

Animals↗
PubMed1997

The active site of ICP47, a herpes simplex virus-encoded inhibitor of the major histocompatibility complex (MHC)-encoded peptide transporter associated with antigen processing (TAP), maps to the NH2-terminal 35 residues.

The herpes simplex virus (HSV) immediate early protein ICP47 inhibits the transporter associated with antigen processing (TAP)-dependent peptide translocation. As a consequence, empty major histocompatibility complex (MHC) class I molecules are retained in the endoplasmic reticulum and recognition of HSV-infected cells by cytotoxic T lymphocytes is abolished. We chemically synthesized full-length ICP47 (sICP47) and show that sICP47 inhibits TAP-dependent peptide translocation in human cells. Its biological activity is indistinguishable from that of recombinant ICP47 (rICP47). By using synthetic peptides, we mapped the core sequence of ICP47 minimally required for TAP inhibition to residues 2-35. This segment is located within the region of the molecule conserved between ICP47 from HSV-1 and HSV-2. Through alanine scanning substitution we identified three segments within this region that are critical for the ability to inhibit TAP function. The interaction of ICP47 with TAP is unlikely to mimic precisely that of the transported peptides, as deduced from differential labeling of the TAP1 and TAP2 subunits using sICP47 fragments with chemical cross-linkers.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

The protease-protected 30 kDa domain of SecA is largely inaccessible to the membrane lipid phase.

SecA binds to the inner membrane of Escherichia coli through low affinity lipid interactions or with high affinity at SecYEG, the integral domain of preprotein translocase. Upon addition of preprotein and nucleotide, a 30 kDa domain of SecYEG-bound SecA is protected from proteolysis via membrane insertion. Such protection could result from some combination of insertion into the lipid phase, into a proteinaceous environment or across the membrane. To assess the exposure of SecYEG-bound SecA to membrane lipids, a radiolabeled, photoactivatable and lipid-partitioning crosslinker, 3-trifluoromethyl-3-(m[125I]iodophenyl) diazirine benzoic acid ester, was incorporated into inner membrane vesicles. The 30 kDa domain of SecYEG-bound SecA, inserted into the membrane in response to translocation ligands, is 18-fold less labeled than SecY, which is labeled effectively. In contrast, incorporation of the purified 30 kDa SecA fragment into crosslinker-containing detergent micelles or addition of detergent to crosslinker-containing membranes bearing the protease-protected SecA domain readily allows for labeling of this domain. We propose that the protease-inaccessible 30 kDa SecA domain is shielded from the fatty acyl membrane phase by membrane-spanning SecYEG helices and/or is largely exposed to the periplasm.

Adenosine Triphosphatases↗
PubMed1997

Direct and GTP-dependent interaction of ADP ribosylation factor 1 with coatomer subunit beta.

A site-directed photocrosslink approach was used to elucidate components that interact directly with ADP- ribosylation factor (ARF)-GTP during coat assembly. Two ARF mutants were generated that contain a photolabile amino acid at positions distant to each other within the ARF molecule. Here we show that one of the two positions specifically interacts with coatomer subunit beta both on Golgi membranes and in isolated coat protein complex type I (COPI)-coated vesicles. Thus, a direct and GTP-dependent interaction of coatomer via beta-coat protein complex (COP) with ARF is involved in the coating of COPI-coated vesicles. These data implicate a bivalent interaction of the complex with the donor membrane during vesicle formation.

ADP-Ribosylation Factors↗
PubMed1997

The endoplasmic reticulum-resident stress protein gp96 binds peptides translocated by TAP.

The endoplasmic reticulum (ER)-resident stress protein gp96 induces a major histocompatibility complex class I-restricted cytotoxic T lymphocyte (CTL) response against antigens present in the cells from which it has been prepared. In this study, photoreactive peptides were translocated into the ER by the transporter associated with antigen processing (TAP). These peptides can be cross-linked specifically to gp96. Thus, we provide the first evidence that gp96 binds TAP-translocated peptides which have been implicated in the induction of specific CTL responses after immunization with gp96 (Srivastava, P. K. et al., Immunogenetics 1994. 39: 93).

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Protein disulfide isomerase is the dominant acceptor for peptides translocated into the endoplasmic reticulum.

Peptides derived from cytosolic protein degradation are translocated into the lumen of the endoplasmic reticulum (ER) by the transporter associated with antigen processing (TAP). In the ER, class I molecules bind the peptides fitting to their respective motifs and present them on the cell surface to CD8+ T lymphocytes. However, most TAP-translocated peptides are not expected to bind to the class I molecules present in a particular cell. Recently, we have demonstrated that TAP-translocated peptides containing a photoreactive phenylalanine analogue can be cross-linked to two luminal ER-resident proteins: with low efficiency to the stress protein gp96 and with high efficiency to a 60-kDa protein (Lammert, E. et al., Eur. J. Immunol. 1997. 27: 923). Both proteins have also been labeled specifically by TAP-translocated peptides conjugated to a different photoreactive group (Marusina, K. et al., Biochemistry 1997. 36: 856). Here, we show that the 60-kDa peptide-binding protein is identical to the multifunctional protein disulfide isomerase (PDI). Since PDI is the only luminal ER-resident protein that is labeled by the photoreactive peptides with high efficiency, it might represent the dominant acceptor for TAP-translocated peptides.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Collegial support and barriers to behavioral programs for severe mental illness.

Previous investigations have identified staff beliefs about barriers to implementing behavioral interventions in programs for persons with severe mental illness. One of these barriers, institutional constraints, was found to be associated with collegial support; i.e., staff who report more collegial support were less likely to endorse institutional constraints. The purpose of this study was to determine how the components of collegial support were associated with beliefs about institutional constraints. Fifty-six staff members completed measures of staff opinions about barriers to implementing behavior therapy, satisfaction with collegial support, source of support, and functions of support. Results suggested that collegial support is significantly associated with co-worker and supervisor support, but not the support of family and friends. Endorsing institutional constraints was inversely associated with the support of co-workers and supervisors; institutional constraints were positively associated with the support of family and friends. Endorsing institutional constraints was also inversely associated with the sense that others rely upon the individual for their well-being. Implications of these findings for diminishing barriers to behavioral interventions are discussed.

Behavior Therapy↗
PubMed1997

Fear and envy: sexual difference and the economies of feminist critique in psychoanalytic discourse.

This essay examines Freud's construction of a mythical moment during early childhood, in which differences between male and female sexual identities are said to originate. It focuses on the way in which Freud divides fear and envy between the sexes, allocating the emotion of (castration) fear to men, and that of (penis) envy to women. On the one hand, the problems of this construction are pointed out, but on the other hand, it is shown that even a much-maligned myth may still provide food for thought. Then, four critiques of Freud which have been articulated by prominent feminist psychoanalysts -- Karen Horney, Nancy Chodorow, Luce Irigaray, and Jessica Benjamin -- are presented, as well as the alternative visions of sexual identities which these thinkers have developed. The basic metaphors or economies guiding these visions of sexual difference are appraised in terms of their breadth and depth, with particular reference to their ability to acknowledge and integrate the presence of fear and envy as passions which are evoked but also repressed in the face of sexual difference. ...

Feminism↗
PubMed1997

Evaluation of a PCR assay for identification and differentiation of Campylobacter fetus subspecies.

OBJECTIVE: To evaluate a polymerase chain reaction assay for identification of Campylobacter fetus and differentiation of the defined subspecies. DESIGN: Characterisation of bacterial strains by traditional phenotyping, polymerase chain reaction, a probabilistic identification scheme and macrorestriction profiling using pulsed field gel electrophoresis. PROCEDURE: The results of identification of 99 bacterial strains as determined by conventional phenotyping or by polymerase chain reaction were compared. Two of these were type strains of C fetus subsp fetus and C fetus subsp venerealis; the remaining strains were field isolates putatively identified as C fetus. In cases where the subspecies identity was disputed, isolates were identified by means of a probabilistic identification scheme and by macrorestriction profiling. RESULTS: The agreement between strain identities initially suggested by traditional phenotypic methods and the PCR assay was found to be 80.8%. The polymerase chain reaction proved to be a reliable technique for the species and subspecies identification of C fetus; equivocal results were obtained in only two instances. Initial misidentifications by conventional phenotyping methods were attributed to methodological differences used in various laboratories. CONCLUSION: Our results indicate that misidentification of C fetus in routine diagnostic laboratories may be relatively common. The PCR assay evaluated gave rapid and reproducible results and is thus a valuable adjunctive method for the identification of C fetus and subsequent subspecies differentiation.

Animals↗
PubMed1996

Ceramide-binding and activation defines protein kinase c-Raf as a ceramide-activated protein kinase.

Interleukin 1 is the prototype of an inflammatory cytokine, and evidence suggests that it uses the sphingomyelin pathway and ceramide production to trigger mitogen-activated protein kinase (MAPK) activation and subsequent gene expression required for acute inflammatory processes. To identify downstream signaling targets of ceramide, a radioiodinated photoaffinity labeling analog of ceramide ([125I] 3-trifluoromethyl-3-(m-iodophenyl)diazirine-ceramide) was employed. It is observed that ceramide specifically binds to and activates protein kinase c-Raf, leading to a subsequent activation of the MAPK cascade. Ceramide does not bind to any other member of the MAPK module nor does it bind to protein kinase C-zeta. These data identify protein kinase c-Raf as a specific molecular target for interleukin 1 beta-stimulated ceramide formation and demonstrate that ceramide is a lipid cofactor participating in regulation of c-Raf activity.

Affinity Labels↗
PubMed1996

H+-induced membrane insertion of influenza virus hemagglutinin involves the HA2 amino-terminal fusion peptide but not the coiled coil region.

Fusion of influenza virus with target membranes is induced by acid and involves complex changes in the viral envelope protein hemagglutinin (HA). In a first, kinetically distinct step, the HA polypeptide chain 2 (HA2) is inserted into the target membrane bilayer. Using hydrophobic photolabeling with the phospholipid analogue 1-O-hexadecanoyl-2-O-[9-[[[2-[125I]iodo-4(trifluoromethyl-3H-diazirin -3-yl)benzyl]oxy]carbonyl]nonanoyl]-sn-glycero-3-phosphocholine, we identified the segment within HA2 that interacts with the membrane. The sole part of the HA2 ectodomain that was labeled with the membrane-restricted reagent is the NH2-terminal fusion peptide (residues 1-22). No labeling occurred within the long coiled coil region generated during the acid-induced conformational transition (Bullough, P. A., Hughson, F. M., Skehel, J. J., and Wiley, D. C. (1994) Nature 371, 37-43). These data strongly suggest that the coiled coil region of HA2 does not insert into the lipid bilayer. This conclusion is at variance with the recent suggestion (Yu, Y. G., King, D. S., and Shin, Y.-K.(1994) Science 266, 274-276) that the coiled coil of HA may splay apart and insert into the target membrane, providing a mechanism by which the viral and the target membrane may come in close apposition.

Animals↗
PubMed1996

Identification of a contact region for peptide on the TAP1 chain of the transporter associated with antigen processing.

The transporter associated with Ag processing (TAP) translocates cytosolic peptides into the endoplasmic reticulum for presentation by MHC class 1 molecules. Recently, the actual peptide translocation step has been suggested to be preceded by binding of the peptide to TAP. In this study, we investigated the peptide binding site of TAP and its relevance for peptide selection by cross-linking of translocatable peptides. Our data demonstrate, first, that for a TAP heterodimer containing the rat TAPu allelic product, which selects peptides on basis of their C terminus, the translocation efficiency correlates with the peptide binding efficiency. Second, peptides having the cross-linker at different positions all label both the TAP1 and the TAP2 subunit after binding to the heterodimer, indicating that both TAP subunits contribute directly to the peptide binding site and contact most or all amino acids of a bound peptide. Third, by enzymatic digestion and the use specific antisera, we identified a domain of human TAP1 that contributes to the peptide binding site. This domain contains the two hydrophobic and thus putative transmembrane regions closest to the ATP binding sites. We conclude that the peptide binding site controls the selectivity of TAP and is composed of domains of both TAP1 and TAP2, which each contact the bound peptide over all or most of its length. Moreover, the major contact site(s) for peptide on TAP1 are located within or close to the two putative transmembrane regions adjacent to the ATP binding site.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

Phospholipase A2 and the hypofrontality hypothesis of schizophrenia.

Phospholipase A2 (PLA2) catalyzes the hydrolysis of membrane phospholipids to release cytotoxic products such as lysophosphatidylcholine. In schizophrenia increased PLA2 activity and an accelerated breakdown of membrane phospholipids have been reported. In neuronal do membranes PLA2 modulates dopamine (DA) release and DA receptor sensitivity. Using two different animal models we show inhibition of dopaminergic activity in vivo by intracerebral PLA2 application. (1) Unilateral stereotaxic injection of PLA2 into the substantia nigra pars compacta causes an apomorphine-induced ipsilateral rotational asymmetry. (2) Intracerebroventricular PLA2 application reduces apomorphine-induced locomotion. NMR spectroscopy studies show a disordered phospholipid metabolism in the prefrontal cortex (PFC) of schizophrenics. The hypofrontality hypothesis of schizophrenia postulates hypodopaminergic activity in the prefrontal cortex. We speculate that increased PLA2 activity in the PFC of schizophrenics might be related to both abnormalities and could thus contribute to hypofrontality in schizophrenia.

Animals↗
PubMed1995

Intracerebroventricular injection of phospholipase A2 inhibits apomorphine-induced locomotion in rats.

Phospholipase A2 (PLA2) is a key enzyme in phospholipid metabolism. In neurons, membrane-bound PLA2 plays an essential role in signal transduction by affecting neurotransmitter release and receptor sensitivity. There are some reports of increased PLA2 activity in schizophrenia. We investigated the effects of intracerebroventricular (i.c.v.) injections of PLA2 on dopamine-mediated behavior in rats. Ten days after i.c.v. injection, PLA2 significantly inhibited apomorphine-induced locomotion as compared with i.c.v. saline injections. The inhibition of apomorphine-induced locomotion by PLA2 was reversible within 4 weeks after stereotaxic surgery. These findings suggest a functional inhibition of dopaminergic postsynaptic receptors by PLA2. Accelerated phospholipid metabolism and reduced dopaminergic activity in the prefrontal cortex have been postulated to play a role in schizophrenia. Increased PLA2 activity may be related to both abnormalities and could thus play a role in the pathophysiology of schizophrenia.

Animals↗