Search PubMed⌕ Search

Biomedical subjects

C Bergmann

Publications and source records attributed to C Bergmann.

At least 55 records · Page 3Linked to original sources
PubMed1993

Effects of mouse hepatitis virus infection on host cell metabolism.

A time dependent decrease in cell surface expression of major histocompatibility complex (MHC) class 1 proteins was found during JHMV infection of the mouse macrophage J774.1 cells line by radioimmunoassay. MHC class I, actin and CSF-1 receptor mRNA levels were also found to decrease during infection. Surprisingly, not all host cell mRNA were similarly affected, suggesting that the apparent MHV-induced translational shut off of host cell protein synthesis during infection was specific for only some host cell mRNAs. Interestingly, two mRNAs found to be refractory to JHMV infection encode monokines, suggesting a role in pathogenesis. To understand the mechanism(s) of this preferential mRNA stability and the apparent shut off of host cell mRNA, translation lysates were prepared from infected and uninfected cells. Translation of host mRNAs in these extracts showed no apparent loss of translational ability in the infected cells vs. the uninfected cells; however, viral mRNAs were preferentially translated in the lysates from the infected cells. Chimeric mRNAs containing the MHV leader upstream of a globin reporter gene showed that preferential translation was a property of the MHV leader RNA. Deletional analysis showed that the sequences responsible for this cis translational augmentation are in a 12 nucleotide (nt) tract at the 3' end of the leader. The previously reported interaction of the nucleocapsid protein with these nts suggest that it may play a role in translational augmentation of MHV mRNAs.

Animals↗
PubMed1993

JHM virus-specific cytotoxic T cells derived from the central nervous system.

Spleen cells cultured from Balb/c mice immunized with the JHM strain of mouse hepatitis virus (JHMV) have CD8+ cytotoxic T cells (CTL) specific for both the S and N proteins, but not the M or HE proteins. T cell lines were established from the brains of Balb/c mice infected with JHMV. The majority of the lines (20 of 22) were specific for JHMV. Analysis of the viral structural proteins which served as target structures indicate that most (15 of 20) were specific for the N protein. One line was specific for the S protein and four lines were specific for JHMV but the protein recognized could not be determined. These data suggest that early during infection there is a preferential recruitment of N protein specific CTL into the CNS of infected mice.

Animals↗
PubMed1993

[Overuse syndrome in ballet: study of the effect of a tape bandage of the upper ankle joint with motion analysis].

In six ballet dancers with overuse syndromes of the foot a study on the effect of taping on stabilisation, proprioception and muscular activity was performed. By using synchronous surface electromyography and 3-dimensional motion analysis three standard ballet positions without and with applied tape were performed. Muscular activities of pronator muscles (peroneus longus) and supinator muscles (tibialis posterior) were recorded. EMG measurements showed significant differences between patients with stable or unstable ankles and painful or pain-free feet. Applying tape led to significant changes of muscle activities in height and antagonist reflex patterns. These changes were highest in dancers with unstable ankle joints and metatarsalgia.

Adult↗
PubMed1993

Effects of ATP on cultured smooth muscle cells from rat aorta.

1. Membrane ionic currents provoked by externally applied ATP were studied by patch-clamp techniques in cultured aortic smooth muscle cells of the rat. 2. Using standard bath and pipette solutions and whole-cell voltage-clamp, ATP evoked an inward current when the cell membrane potential was held at -50 mV and an outward current when the potential was held at 30 mV, with a reversal potential near -10 mV. 3. Application of ATP gamma S gave results similar to those obtained with ATP, while adenosine, AMP and alpha,beta-methylene ATP were ineffective. The ATP-activated current was inhibited by suramin, 100 microM. 4. ATP also induced a biphasic rise in internal free Ca levels as shown directly by Fura-2 measurements and by the increase in Ca-dependent K single-channel activity in cell-attached patches. 5. With outward current through K channels blocked by internal Cs and TEA, modification of the ionic composition of bath and pipette solutions revealed that the reversal potential for the ATP-induced whole-cell current closely followed ECl, the chloride equilibrium potential, and was insensitive to manipulations of the monovalent cation gradient. 6. These results indicate that in rat cultured aortic smooth muscle cells, ATP binding to P2-purinoceptors produces increases of internal free Ca levels and subsequent activation of both Ca-dependent K and Cl currents.

Adenosine Triphosphate↗
PubMed1993

Characterization of the Ld-restricted cytotoxic T-lymphocyte epitope in the mouse hepatitis virus nucleocapsid protein.

The mouse hepatitis virus (MHV) JHM strain (JHMV) produces primary demyelination in the central nervous system associated with acute encephalomyelitis. Humoral and cellular immune responses both participate in controlling the development of chronic MHV-induced demyelination. A subset of the CD8+ cytotoxic T lymphocytes (CTL) induced by immunization of BALB/c (H-2d) mice with JHMV is specific for the viral nucleocapsid protein. This CTL population recognizes an epitope located within the carboxy-terminal 149 amino acids in association with the Ld class I molecule (S. A. Stohlman, S. Kyuwa, M. Cohen, C. Bergmann, J. P. Polo, J. Yeh, R. Anthony, and J. G. Keck, Virology 189:217-224, 1992). Using a panel of vaccinia virus recombinants expressing truncated forms of the nucleocapsid protein and a series of overlapping synthetic peptides, we mapped the response to 15 amino acids. This sequence, encompassing the MHV epitope, contains the Ld-specific binding motif. The predicted 9-mer peptide (residues 318 to 326: APTAGAFFF) was sufficient and highly active in sensitizing target cells for CTL recognition when either added exogenously or synthesized intracellularly. Cross-reactivity of JHMV nucleocapsid protein-specific CTL with six other MHV strains indicated that natural sequence variations within the 9-mer epitope are tolerated in positions 4 and 5, whereas all other amino acids are conserved. These data define a novel 9-mer Ld-restricted CTL epitope which represents the first MHV CTL epitope. Characterization of this epitope provides a molecular basis to study the role of nucleocapsid protein-specific CTL in the clearance of JHMV from the central nervous system.

Amino Acid Sequence↗
PubMed1992

Mouse hepatitis virus nucleocapsid protein-specific cytotoxic T lymphocytes are Ld restricted and specific for the carboxy terminus.

Infection of mice with the JHM strain of mouse hepatitis virus (MHV) results in an acute encephalomyelitis associated with primary demyelination of the central nervous system. Efforts at understanding the components of the immune response in the development of chronic MHV-induced demyelination have implicated the antibody response and both the CD4+ and CD8+ T cell responses. In this report, we demonstrate that Balb/c (H-2d) mice immunized with the JHM (JHMV) strain of MHV develop a CD8+ cytotoxic T lymphocyte (CTL) response. One population of these virus-specific CTL recognize the nucleocapsid (N) protein. Recombinant vaccinia viruses expressing either the entire N protein or carboxy-terminal deletions were used to determine the number and location of the epitope(s) recognized. The CTLs were found to recognize a peptide contained within the carboxy-terminal 149 amino acids of the N protein. Analysis of infected cell lines expressing transfected major histocompatibility genes demonstrated that the anti-N protein CTLs were restricted exclusively to the Ld molecule. These data provide the first definition of a MHV-specific CTL response directed to a viral protein and suggest that the anti-N protein CTL response is one potential mechanism used by the host to clear JHMV from the central nervous system.

Animals↗
PubMed1990

Dietary calcium, vascular reactivity, and genetic hypertension in the Lyon rat strain.

In order to examine the relationship existing between dietary calcium and the development of hypertension, we developed a long-term study in the Lyon hypertensive rat strain (LH) and two control strains, the Lyon normotensive (LN) and low blood pressure rats (LL) given enriched (HCa, 2.5%), deprived (LCa, 0.03%) and normal (NCa, 0.6%) calcium diets. Evolution of body weight, systolic blood pressure (BP), plasma calcium and magnesium was monitored from 4 to 23 weeks of age. Total cardiovascular reactivity and contractile response of isolated aorta to norepinephrine were measured at 23 weeks of age. LH rats on HCa diet failed to develop hypertension (BP less than 150 mm Hg) whereas LH rats on LCa diet exhibited higher blood pressure levels than their controls fed the NCa diet. Moreover, in LN rats HCa diet slightly decreased BP whereas LCa had no effect. In the LL rats, on the contrary, only LCa diet slightly increased BP. In vivo responsiveness to NE was significantly higher in LH compared to LL and LN rats fed a NCa diet. HCa and LCa diets both induced a significant decrease in this response in LH rats. HCa diet increased the response in LN rats but decreased it in LL. In contrast, at the same age, the in vitro contractile response of isolated aorta to NE was significantly decreased in LH compared to LN and LL rats receiving NCa diet. Moreover in LH and LN rats on HCa diet the contractile response was markedly increased but no significant difference was observed with LCa diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Cloning and expression of human salivary-gland kallikrein in Escherichia coli.

CDNA clones for human kallikrein have been identified in a cDNA library constructed from mRNA of human salivary gland. The entire coding sequence for preprokallikrein and for the 5'- and 3'-untranslated regions were isolated by using a mixture of oligonucleotides corresponding to amino acids 51-56 of human urinary kallikrein and one oligonucleotide corresponding to amino acids 233-238 of human pancreatic kallikrein. The DNA sequence proved that, with the exception of two amino acid exchanges, kallikrein of the human salivary gland is identical with pancreatic kallikrein. Salivary gland and renal kallikrein was expressed in Escherichia coli from plasmid pKK223-3 under the control of the tac promoter. The protein was identified by Western-blot analysis and by demonstration of its specific proteolytic activity.

Amino Acid Sequence↗
PubMed1989

Parathyroid hormone acute vascular effect is mediated by decreased Ca2+ uptake and enhanced cAMP level.

Cardiovascular effects of parathyroid hormone (PTH) have been recently described. Pharmacological doses of PTH both reduce arterial pressure and increase blood flow of vascular beds. Two possible cellular mechanisms were investigated: (a) transmembrane Ca2+ fluxes and (b) cyclic AMP response in vascular smooth muscle. In vivo, results in the rat show that injection of synthetic bovine 1-34 fragment of PTH (bPTH-(1-34] produced a rapid (1-2 min) but transient (5-16 min) hypotensive effect which was dose-related (0.4-4 nmol.kg-1). In the in vitro studies on isolated rat aorta, bPTH-(1-34) partially inhibited noradrenaline (NA)-induced contractions by decreasing the sustained tonic component dependent on extracellular Ca2+. bPTH-(1-34) also produced relaxation of aorta preconstricted with NA or prostaglandin F2 alpha. Measurements of the lanthanum-resistant Ca2+ pool using 45Ca2+ showed that bPTH-(1-34) decreased basal Ca2+ uptake and partially inhibited Ca2+ uptake stimulated by NA or K+-depolarizing solution in a concentration-dependent fashion. In addition, bPTH-(1-34) caused a concentration-related increase in cyclic AMP in rat isolated aortic tissues. Hypotensive and vasorelaxing effects of bPTH-(1-34) thus appear to be mediated by a decrease in the amount of Ca2+ available for contraction and by an increase in cyclic AMP response in vascular smooth muscle cells.

Adenylyl Cyclases↗
PubMed1989

Intracellular Ca2+ and force determined simultaneously in isolated resistance arteries.

A method is described for the simultaneous measurement of intracellular Ca2+ ([Ca2+]i) and force generation in isolated resistance arteries using the fluorescent Ca2+ indicator fura-2. Branch II mesenteric resistance arteries were isolated from 12-wk-old Wistar-Kyoto rats and mounted in a wire myograph. The myograph was placed on the stage of a compound microscope interfaced with a dual excitation wavelength fluorometer, and the tissue was loaded with fura-2 by incubation over a 30-min period with the cell-permeable form of the dye. When stimulated with physiological salt solution containing 100 mM KCl and 10 microM norepinephrine, a rapid and transient increase in [Ca2+], was observed to precede active force development and plateau at approximately 60% of the maximal level after 50 s. Washout of the agonists induced relaxation of these small arteries, consisting of an 85% decline in active tension over 100 s and a fall in [Ca2+]i to 50% of prerelaxation level over the same time period. Forskolin (1 microM), which increases intracellular adenosine 3',5'-cyclic monophosphate, induced a 50% relaxation over a 150-s period that was preceded by a fall in [Ca2+]i. Nearly identical results were obtained with 100 microM sodium nitroprusside, which stimulates intracellular guanosine 3',5'-cyclic monophosphate production. These findings indicate that the initiating event of forskolin- and sodium nitroprusside-induced relaxation may be a reduction of [Ca2+]i. The method described is useful for examining basic physiological events and Ca2+-related mechanisms of action of vasoactive compounds in isolated resistance arteries.

Animals↗
PubMed1987

Effect of parathyroid hormone and antagonist on aortic cAMP levels.

Experiments were designed to further investigate the vasoactive mechanisms of parathyroid hormone (PTH) on vascular smooth muscle cells. Time courses of the cAMP responses to the fragment (1-34) of bovine PTH (bPTH(1-34)) on cAMP levels have been studied in rat isolated aorta and in aortic myocytes in primary culture. In both aorta and myocytes bPTH (1-34) induced an increase in cAMP levels that was maximal and reached, respectively, 1.6- and 1.9-fold the basal level after 2 min of contact with bPTH (1-34). The effect of bPTH (1-34) on aortic cAMP content was concentration dependent in the range of 30-300 nM. (Nle8,18, Tyr34)-bPTH (3-34)amide, an antagonist of bPTH (1-34) with a stimulant effect on renal and vascular adenylate cyclase activity, inhibited the cAMP-increasing effect of bPTH (1-34). These results are in favour of a role for cAMP in the vasodilating effect of PTH.

Animals↗
PubMed1986

Expression, secretion and processing of hirudin in E. coli using the alkaline phosphatase signal sequence.

A DNA fragment coding for the E. coli phoA signal peptide was synthesized and inserted into the expression vector pKK223-3. A single HindIII restriction site is located just at the end of the signal sequence. A gene coding for the proteinase inhibitor hirudin, which has previously been synthesized, was inserted into this HindIII site. The hybrid protein was expressed under control of the tac-promoter and secreted into the periplasm of E. coli. From the periplasmic fraction two processed proteins were isolated. One of these was identical with desulfatohirudin and also had similar biological properties.

Alkaline Phosphatase↗
PubMed1986

Chemical synthesis and expression of a gene coding for hirudin, the thrombin-specific inhibitor from the leech Hirudo medicinalis.

A DNA containing the coding sequence for the proteinase inhibitor protein hirudin from the leech Hirudo medicinalis has been obtained by enzymic ligation of chemically synthesized deoxyoligonucleotides. The 226 bp synthetic gene carries signals for the translation initiation and termination. Fragment synthesis was performed by the Khorana ligation method as well as by the fill-in method. Efficiencies of these two methods are compared. The synthetic gene was expressed in E. coli as a fusion protein with beta-galactosidase under the control of the lac-promoter as well as a non-hybrid protein under the control of the lambda PL-promoter. The non-hybrid expression product was shown to have similar biological properties as the authentic protein isolated from the leech.

Amino Acid Sequence↗