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M Kress

Publications and source records attributed to M Kress.

At least 55 records · Page 3Linked to original sources
PubMed1996

Low pH facilitates capsaicin responses in isolated sensory neurons of the rat.

The effects of capsaicin (CAPS; 30 nM, 300 nM, 3 microM) and acidic solutions (pH 6.6, 6.1, 5.6, 5.1) were studied in dorsal root ganglion (DRG) neurons from adult rats in short term culture using the whole cell patch-clamp technique and a system for fast drug application. At -60 mV holding potential, both CAPS 30 nM and 300 nM for 10 s did not induce a significant membrane current in pH 7.3. The first response to 3 microM CAPS at pH 7.3 yielded an inward current of 898 +/- 517 pA and with pH 6.1 the sustained proton-induced current was 365 +/- 153 pA. A more than additive current increase was observed when both agents were applied together even at subthreshold concentrations of CAPS or protons. Similar results were obtained at positive holding potential. Facilitation was also observed when extracellular pH 6.1 solution was applied immediately after discontinuation of 3 microM CAPS application but not when CAPS followed the application of pH 6.1 solution (n = 8). The proton-induced current as well as the CAPS-pH response both increased with proton concentration and showed the same short relaxation time relative to the CAPS response. The facilitation saturated near pH 5.6, and was present in repeated trials when responses to CAPS were markedly decreased due to tachyphylaxis. It is suggested that protonation of CAPS gated ion channels increases their open probability or conductance and modulates their kinetics.

Animals↗
PubMed1996

An apparent autocrine mechanism amplifies the dexamethasone- and retinoic acid-induced expression of mouse lipocalin-encoding gene 24p3.

We have isolated, sequenced and characterized the mouse 24p3 gene. The 24p3 protein is a member of the lipocalin family comprising secreted transporters of hydrophobic ligands. The 24p3 cDNA had been initially isolated during a search for genes overexpressed during a SV40-induced mitotic reaction [Hraba-Renevey et al., Oncogene 4 (1989) 601-608]. 24p3 comprises six exons, five introns and 793 bp of 5' regulatory region. The transcription start point (tsp) was identified by primer extension. Putative regulatory elements, including a TATA-like box and two glucocorticoid responsive core elements (GRE), have been mapped in the 5'-flanking region. Based on this observation, we examined the effect of a glucocorticoid (dexamethasone, Dex) on 24p3 expression. Dex induced the expression of 24p3 dramatically in the absence of de novo protein synthesis. This activation was further amplified by an apparent autocrine mechanism. Similar results were obtained with retinoic acid. Using the cat reporter gene system, we have shown that the 5'-flanking region of 24p3 confers Dex inducibility. Furthermore, we have identified a 43-bp region of the 24p3 promoter required for the Dex responsiveness. The biological implications are discussed in light of these results.

Acute-Phase Proteins↗
PubMed1996

Stable analogues of cyclic AMP but not cyclic GMP sensitize unmyelinated primary afferents in rat skin to heat stimulation but not to inflammatory mediators, in vitro.

The aim of this investigation was to evaluate the role played by cyclic nucleotides in the transduction of inflammatory pain and hyperalgesia. Unmyelinated afferents (n = 79) were exposed to stable analogues of cyclic AMP and cyclic GMP, to inflammatory mediators and to Methylene Blue, an inhibitor of guanylyl cyclase. Analogues of cyclic AMP at a concentration of 1 mM (n = 9) but not 10 microM (n = 16) sensitized nociceptor responses to noxious heat and enhanced interstimulus activity. In addition. mechanical thresholds were moderately, but significantly lowered after superfusion of the cyclic AMP analogue (1 mM). Addition of 10 microM cyclic AMP analogue to a mixture of excitatory inflammatory mediators (serotonin, histamine, bradykinin and prostaglandin E2, 10 microM each) did not further increase nociceptor activity (n = 15), in contrast to a previous report that cAMP sensitized bradykinin responses. Cyclic GMP analogues (10 microM, 1 mM) did not alter heat sensitivity or mechanical thresholds of polymodal C-fibres, nor did they enhance the ongoing activity that resulted from repeated heat stimulation. After inhibition of guanylyl cyclase with Methylene Blue, cyclic GMP analogues (1-10 microM) did not alter nociceptor responses evoked by application of the mixture of inflammatory mediators. The findings indicate that polymodal nociceptor sensitization and excitation is independent of cyclic GMP. Cyclic AMP can obviously contribute to the increased heat sensitivity of inflamed tissue, whereas cyclic GMP might be of importance in the recruitment of "silent" nociceptors.

Afferent Pathways↗
PubMed1996

Ca2+ permeability of the sustained proton-induced cation current in adult rat dorsal root ganglion neurons.

1. Microfluorometric Ca2+ measurements using FURA-2 and whole cell patch-clamp recordings were performed to investigate the Ca2+ permeability of ion channels underlying the proton-induced sustained cation current in adult rat dorsal root ganglion neurons. 2. In a subpopulation of these neurons, extracellular application of acidic solutions (pH 5.1) elicited a sustained cation current and a concomitant reversible rise in the intracellular free Ca2+ concentration ([Ca2+]i), which depended on the presence of external Ca2+. Ruthenium red (10 microM) reduced both the current and the rise in [Ca2+]i to about the same extent. 3. In the presence of 2 mM external Ca2+, sustained proton-induced currents reversed sign at -4.6 +/- 1.2 (SE) mV, with external Na+ and internal Cs+ as the major charge carriers. Increasing the external Ca2+ concentration to 30 mM shifted the reversal potential (Erev) by 3.0 +/- 0.9 mV toward more positive values, suggesting a permeability ratio of Ca2+/Cs+ of 0.41. A similar value (0.35) could be obtained from Erev (-21 mV) under bi-ionic conditions with 100 mM external Ca2+ and 154 mM internal Cs+. 4. These results demonstrate that the proton-activated cation channels investigated here are moderately permeable to Ca2+. This may lead to pathophysiologically relevant increases in [Ca2+]i on prolonged exposure of the cells to an acidic environment in inflamed or ischemic tissue.

Animals↗
PubMed1995

Phosphorylation by p34cdc2 regulates spindle association of human Eg5, a kinesin-related motor essential for bipolar spindle formation in vivo.

We have isolated a human homolog of Xenopus Eg5, a kinesin-related motor protein implicated in the assembly and dynamics of the mitotic spindle. We report that microinjection of antibodies against human Eg5 (HsEg5) blocks centrosome migration and causes HeLa cells to arrest in mitosis with monoastral microtubule arrays. Furthermore, an evolutionarily conserved cdc2 phosphorylation site (Thr-927) in HsEg5 is phosphorylated specifically during mitosis in HeLa cells and by p34cdc2/cyclin B in vitro. Mutation of Thr-927 to nonphosphorylatable residues prevents HsEg5 from binding to centrosomes, indicating that phosphorylation controls the association of this motor with the spindle apparatus. These results indicate that HsEg5 is required for establishing a bipolar spindle and that p34cdc2 protein kinase directly regulates its localization.

Amino Acid Sequence↗
PubMed1995

Human and mouse Krüppel-like (MOK2) orthologue genes encode two different zinc finger proteins.

We have isolated the human homologue of Mok2 gene encoding a Krüppel-like protein. The identification of three cDNAs and genomic clones reveals that the human protein shows substantial structural differences with the mouse MOK2 protein. The mouse MOK2 protein is composed of seven tandem zinc-finger motifs with five additional amino acids at the COOH-terminal. This structural feature is also present at the end of the human MOK2 protein. The seven zinc-finger motifs show 94% identity between the two proteins. In addition, the human protein contains three additional zinc-finger motifs in tandem with the others and a nonfinger acidic domain of 173 amino acids at the NH2-terminal. The Southern analysis indicates that a single copy of these two genes is present in the genome. The human gene has been localized on chromosome 19 on band q13.2-q13.3. The comparison of human and mouse cDNA sequences reveals a strong identity in the sequences localized outside the seven highly conserved zinc-finger motifs. The divergence from their common ancestor results in the loss of a potential transcription activator domain in mouse MOK2 protein.

Amino Acid Sequence↗
PubMed1995

Effects of oxygen radicals on nociceptive afferents in the rat skin in vitro.

On the premises of clinical studies, a possible contribution of oxygen radicals has been considered to the development of inflammatory pain and hyperalgesia. In a rat skin-saphenous nerve preparation using standard teased-fiber techniques (n = 57) hydrogen peroxide (1 mM, 10 mM and 50 mM) was applied in aqueous solution to cutaneous nerve endings of unmyelinated nociceptive afferents. Superoxide anion and hydroxyl radical were secondarily generated as reaction products from pyrogallol (1 and 10 mM) and from Fe-EDTA (1 mM) in hydrogen peroxide, respectively. None of these substances, except exceptionally, induced ongoing activity nor nociceptor sensitization to heat and mechanical stimuli. If occasionally there was a weak excitatory effect, the fibers were left with a profound desensitization to adequate stimulation. The addition of hydrogen peroxide did not enhance sustained responses to solutions of high proton concentration (pH 6.1). Responses to combined inflammatory mediators (bradykinin, serotonin, histamine and prostaglandin E2, 10 microM) were increased, on average, when hydrogen peroxide was added but this effect did just not reach significance. These findings suggest that oxygen radicals do not play a major and specific role in nociceptor sensitization.

Animals↗
PubMed1994

A highly conserved eukaryotic protein family possessing properties of polypeptide chain release factor.

The termination of protein synthesis in ribosomes is governed by termination (stop) codons in messenger RNAs and by polypeptide chain release factors (RFs). Although the primary structure of prokaryotic RFs and yeast mitochrondrial RF is established, that of the only known eukaryotic RF (eRF) remains obscure. Here we report the assignment of a family of tightly related proteins (designated eRF1) from lower and higher eukaryotes which are structurally and functionally similar to rabbit eRF. Two of these proteins, one from human and the other from Xenopus laevis, have been expressed in yeast and Escherichia coli, respectively, purified and shown to be active in the in vitro RF assay. The other protein of this family, sup45 (sup1) of Saccharomyces cerevisiae, is involved in omnipotent suppression during translation. The amino-acid sequence of the eRF1 family is highly conserved. We conclude that the eRF1 proteins are directly implicated in the termination of translation in eukaryotes.

Amino Acid Sequence↗
PubMed1994

The gene encoding the MOK-2 zinc-finger protein: characterization of its promoter and negative regulation by mouse Alu type-2 repetitive elements.

The mouse gene MOK-2 encodes a protein with seven highly similar zinc fingers. The MOK-2 transcripts are preferentially detected in transformed cell lines, brain and testis tissues. The characterized 5'-flanking sequence differs from those of tissue-specific genes previously described. DNA sequence analysis shows that the promoter region lacks TATA and CCAAT boxes. Two short interspersed mouse genomic repeats (B2 sequences) found in this region exert a negative cis-acting effect on MOK-2 promoter activity.

Amino Acid Sequence↗
PubMed1994

Activated human platelets in plasma excite nociceptors in rat skin, in vitro.

Extravascular activation of thrombocytes may contribute to nociceptor excitation and pain, since platelets store and, upon stimulation, release potential algogenic substances such as serotonin, histamine and precursor molecules of bradykinin. To test this hypothesis, a skin-nerve preparation of rat hairy skin, in vitro, was used that allows to record and characterize single afferent nerve fibers. In a first protocol, receptive fields of nociceptive C-fibers, at the corium side of the skin patch, were exposed to adenosine diphosphate (ADP), to heparinized human platelet-rich plasma (PRP) and to PRP activated by ADP. Such activated platelets excited 9/11 units characterized as mechano-heat responsive C-nociceptors (CMH); peak discharges of more than 10 spikes/s were observed. After application of activated PRP, 4/5 high threshold mechanosensitive C-units and 4/5 mechano-cold sensitive C-units became responsive to heat stimulation but only few of these fibers were excited (1/5 in each group). In a second series of experiments the exposure to native PRP was prolonged to test for the effect of spontaneous platelet activation resulting from cutaneous collagen. Prolonged exposure did, but not significantly, enhance fiber discharge. During subsequent exposure to activated PRP, the discharge commenced, on average, after a significant delay of about three minutes. With this protocol 5/7 CMH units were driven by activated platelets. Following both protocols, mechanical (v.Frey) and thermal thresholds of the CMH units were not significantly altered. The findings demonstrate that nociceptors can indeed be driven and sensitized by activated platelets. This pain inducing mechanism may be relevant to certain clinical conditions, and it appears promising to scrutinize the chemical factors involved.

Adenosine Diphosphate↗
PubMed1994

The kinesin-related protein Eg5 associates with both interphase and spindle microtubules during Xenopus early development.

We have examined the changing abundance and distribution of the kinesin-related protein Eg5 during oogenesis and early development in Xenopus laevis. Antibodies raised against proteins synthesized from parts of a novel Eg5 gene expressed in eggs were used for Western blotting and immunofluorescence. Eg5 protein was highly enriched in oocytes and eggs compared with other adult tissues. It accumulated during the latter stages of oogenesis and increased a further threefold during oocyte maturation. Its level then gradually declined during early development. In oocytes, eggs, and early embryos, Eg5 protein could be detected throughout the cytoplasm and in subcortical aggregates. Eg5 staining was found concentrated in meiotic and mitotic spindles, mainly toward the poles. Some Eg5 staining colocalized with microtubules in interphase cells, including the aligned subcortical microtubules in fertilized eggs implicated in the cortical rotation that specifies the dorsoventral axis. Interphase association of Eg5 with microtubules during early development was confirmed by copelleting the protein with microtubules from egg homogenates. In tadpoles and tissue culture cells, Eg5 colocalized with spindle microtubules throughout mitosis but not with interphase microtubules. These results suggest that the Eg5 microtubule motor may function in meiosis, mitosis, and interphase during early development.

Amino Acid Sequence↗
PubMed1993

[Hypersalivation as a leading symptom of neoplastic meningiosis in highly malignant non-Hodgkin's lymphoma].

Partial remission of a centroblastic non-Hodgkin's lymphoma, clinical stage IV A, in a 79-year-old man was achieved by six courses of chemotherapy with epirubicin, cyclophosphamide and vincristine. The only residual finding was a palpable small cervical lymphoma. After a treatment pause of about 6 weeks increasing hypersalivation set in which ultimately made food intake impossible and led to a breakdown in the patient's general state. Findings in the region of the head, neck, throat and the base of the skull were unremarkable, but cerebrospinal fluid contained 1300/3 cells, almost all of them lymphoblasts. After five intrathecal injections of at first 15 mg methotrexate and 4 mg dexamethasone each, followed by five more with 40 mg cytarabine added to them, the CSF cell count became normal. At the same time salivation clearly decreased and food intake became once again possible. The patient died 5 months later from hypercalcaemia due to osseous infiltrations. Until his death there was no recurrence of the hypersalivation as the cardinal sign of meningeal carcinomatosis.

Aged↗
PubMed1993

Biochemical and functional characteristics of soluble MHC molecules derived from H-2Ld/Q10d chimeric gene.

We have constructed a chimeric class I gene in which the 5' half of the H-2Ld gene is linked to the 3' half of Q10d. The resulting H-2Ld/Q10d protein is homologous to the native H-2Ld heavy chain for the three external domains except for an Arg to His substitution at position 260. The transmembrane and intracytoplasmic domains of the H-2Ld chain are replaced by the short low hydrophobic transmembrane-like domain of the Q10d chain. Following DNA-mediated gene transfer into mouse L cells, transformants were selected for the presence of specific mRNA. Radiolabelling and immunoprecipitation analysis revealed secretion of a 48-46 kd chain weakly associated with beta 2-microglobulin. This molecule reacts with H-2Ld-specific mAb that identify determinants on the first and second domains as well as with an anti-Q10 carboxyl-terminal peptide antiserum, but is not recognized by a mAb specific for a determinant of H-2Ld third domain. The integrity of antibody reactivity of the first and second domains together with beta 2-microglobulin association suggest that our molecule may be considered a good soluble counterpart of the native membrane H-2Ld molecule with which to perform functional studies. In order to analyze the immunogenic capacities and T-cell recognition of the soluble H-2Ld molecules, T-cell lines were produced from mice of various inbred strains immunized with supernatant from H-2Ld/Q10d-transfected fibroblasts. Characterization of these T cells revealed that they expressed a CD4+CD8- phenotype, and recognized H-2Ld/Q10d products in a class II-restricted manner.

Animals↗
PubMed1993

In Xenopus laevis, the product of a developmentally regulated mRNA is structurally and functionally homologous to a Saccharomyces cerevisiae protein involved in translation fidelity.

We have performed a differential screen of a Xenopus egg cDNA library and selected two clones (Cl1 and Cl2) corresponding to mRNA which are specifically adenylated and recruited into polysomes after fertilization. Sequence analysis of Cl1 reveals that the corresponding protein is 67.5% identical (83% similar) to the product of the Saccharomyces cerevisiae SUP45 (also called SUP1 or SAL4) gene. This gene, when mutated, is an omnipotent suppressor of nonsense codons. When expressed in a sup45 mutant, the Xenopus Cl1 cDNA was able to suppress sup45-related phenotypes, showing that the structural homology reflects a functional homology. Our discovery of a structural and functional homolog in Xenopus cells implies that the function of SUP45 is not restricted to lower eukaryotes and that the SUP45 protein may perform a crucial cellular function in higher eukaryotes.

Amino Acid Sequence↗
PubMed1992

The nociceptor sensitization by bradykinin does not depend on sympathetic neurons.

Nociceptive primary afferents develop an increased responsiveness in inflamed tissue. The aim of this neurophysiological investigation was to study the sensitivity changes of cutaneous nociceptors following application of the algesic inflammatory mediator bradykinin and to examine a possible contribution of the sympathetic nervous system. Single unit recordings were obtained in a skin-nerve in vitro preparation from unmyelinated nociceptive afferents supplying the hairy skin of intact or of chronically sympathectomized rats. In preparations from intact skin, mechano-heat-sensitive C-fibres responding to superfusion of the receptive fields with 10 microM bradykinin for 1 min were sensitized to heat stimulation 2 min later. On average, the threshold dropped by 5.0 degrees C, the maximal discharge frequency increased by 34% and the temperature eliciting this peak discharge dropped by 5.6 degrees C. This resulted in a leftward shift and an increased slope of the stimulus-response function indicating sensitization. In surgically sympathectomized animals, 52% of the nociceptive afferents were activated by bradykinin which is not different from normal controls. In sympathectomized animals neither the reduction of the mean threshold (4.6 degrees C) nor the increase of the peak discharge frequency (48%) differed significantly from intact controls. The change of the stimulation-response function following bradykinin application was virtually identical in intact and sympathectomized preparations. Moreover, bradykinin increased the heat discharge of individual fibres by a factor of 2.1 in intact and 1.9 in sympathectomized animals, respectively. In both preparations the increased responsiveness of the nociceptors was short-lived and had resolved 7 min after chemical stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Responsiveness and functional attributes of electrically localized terminals of cutaneous C-fibers in vivo and in vitro.

1. The purpose of the present study was to compare the responsiveness unmyelinated cutaneous units in vivo and in vitro and to determine the proportion of primary afferents innervating the rat hairy skin that do not respond to transient mechanical or thermal stimuli. We have adopted electrical search strategies to locate the terminal arborization of unmyelinated fibers before testing the sensitivity to adequate stimuli. 2. A total of 144 unmyelinated units were studied, of which 31 were obtained from in vivo and 113 from in vitro experiments. 55 afferents were investigated after chronic surgical sympathectomy. Units recorded from sympathectomized rats did not differ in their conduction velocity, electrical thresholds, or receptive properties from units in intact animals. 3. There were only minor differences between the properties of units recorded in vivo and in vitro. This probably reflects technical differences of the setups rather than biological changes introduced by the in vitro conditions. Except for a higher prevalence of mechano-cold sensitive units in vitro, there was no significant difference between the distributions of receptor types. 4. Eight of 31 units (26%) recorded in vivo and 17 of 113 units (15%) obtained from in vitro experiments failed to respond to transient mechanical or thermal stimuli. In vivo, one of eight initially unresponsive units was activated by repeated mechanical and thermal stimulation. Two further units became responsive after topical application of mustard oil. In vitro, 2 of 17 unresponsive units were activated by repeated stimulation. Ten of the remaining unresponsive units were treated with a combination of inflammatory mediators. Four of these units were activated: three developed ongoing activity, and two of them also became responsive to mechanical and/or heat stimuli. The fourth unit responded to probing but was not spontaneously active. 5. We conclude that transient mechanical or thermal stimuli can excite the majority of unmyelinated cutaneous units. However, in vivo and in vitro, part of unmyelinated units are initially unresponsive even to noxious forms of stimulation. Because those unresponsive units were also encountered in sympathectomized preparations, and because some units can be recruited with repeated noxious stimuli or inflammatory agents, it is unlikely that all of them are sympathetic efferents. The same substances that cause sensitization of "normal" nociceptors are capable of recruiting initially unresponsive unmyelinated afferents.

Animals↗