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Biomedical subjects

C Lange

Publications and source records attributed to C Lange.

At least 91 records · Page 5Linked to original sources
PubMed1997

A secreted/shed product of Helicobacter pylori activates transcription factor nuclear factor-kappa B.

Helicobacter pylori is an etiologic agent in the development of chronic gastritis, duodenal ulceration, and gastric adenocarcinoma. Exposure of gastric epithelial cells to H. pylori induces secretion of the cytokine IL-8, which plays a pivotal role in the immunopathogenesis of H. pylori infections. Isolated Helicobacter strains differ in their virulence and in their ability to induce cytokine production. High degrees of virulence correlate with enhanced IL-8 production. However, the molecular mechanism of this variance in Helicobacter pathogenicity remains poorly understood. Here we show that H. pylori-mediated IL-8 secretion requires activation of the transcription factor nuclear factor-kappaB (NF-kappaB) in a gastric epithelial cell line. Several H. pylori strains which fail to induce IL-8 secretion do not activate NF-kappaB, while all IL-8-inducing strains activate the transcription factor. Moreover, the antioxidant curcumin, which inhibits NF-kappaB activation, also completely suppresses IL-8 induction by H. pylori. NF-kappaB activation is not mediated by LPSs, since purified H. pylori LPS had no effect on gastric epithelial cells. In contrast, both IL-8 secretion and NF-kappaB activation require a secreted H. pylori product, which is not secreted by strains mutated in picB/cagE, a recently identified putative transport protein.

Antioxidants↗
PubMed1997

Calcium-dependent binding of recoverin to membranes monitored by surface plasmon resonance spectroscopy in real time.

Recoverin is an N-myristoylated Ca2+-binding protein that serves as a Ca2+-sensor in visual transduction. We studied the dynamics of its Ca2+-dependent membrane association which depends on the myristoyl modification (Ca2+-myristoyl switch) by surface plasmon resonance spectroscopy. Either recoverin or phospholipid vesicles were immobilized on a sensor chip surface, and the respective binding partner was supplied in the mobile phase. Binding of recoverin to artificial liposomes or rod outer segment membranes was strictly dependent on Ca2+ and the myristoyl group. The Ca2+-myristoyl switch was half-maximal between 4.0 and 7.7 microM Ca2+, depending on whether recoverin or liposomes were in the mobile phase. At saturating [Ca2+], the dissociation constant (KD) of recoverin for phospholipid liposomes was approximately 150 microM. The association and dissociation of recoverin to membranes was fast and biphasic (fast and slow components) with time constants on the order of 0.1 s-1 and 0.01 s-1, respectively. Dissociation of the recoverin-membrane complex was 3-fold faster at low than at high free [Ca2+]. We discuss the analogy between the liposome-sensor chip and the disk surface and conclude that a minor fraction of the total recoverin in a rod outer segment is associated with membranes at resting dark levels of free [Ca2+].

Animals↗
PubMed1997

Induction of host signal transduction pathways by Helicobacter pylori.

Adherence of Helicobacter pylori to cultured gastric epithelial cells is associated with several cellular events, including the tyrosine phosphorylation of a 145-kDa host protein; the reorganization of the host cell actin and associated cellular proteins, like vasodilator-stimulated phosphoprotein, adjacent to the attached bacterial cell; and the subsequent release of the cytokine, interleukin 8 (IL-8). H. pylori isolated from patients with ulcer disease and gastric cancer contain a DNA insertion, the cag pathogenicity island (PAI), that is not present in bacteria isolated from individuals with asymptomatic infection. Mutations in a number of PAI genes abolish tyrosine phosphorylation and IL-8 synthesis but not the cytoskeletal rearrangements. Kinase inhibition studies suggest there are two distinct pathways operative in stimulating IL-8 release from host cells and one of these H. pylori pathways is independent of the tyrosine phosphorylation step.

Cell Line↗
PubMed1997

Health impacts of large releases of radionuclides. The fate and impact of radiocontaminants in urban areas.

The Chernobyl accident made it clear that the contaminants released after a severe nuclear accident may spread over large areas, and thereby form a significant external radiation hazard in areas of high population density. Since then, the weathering effects on the deposited radiocontaminants (essentially radiocaesium) have been followed on different types of surface in urban, suburban and industrial areas in order to enable an estimation of the long-term impact of such events. Analytical expressions have been derived for the typical behaviour of radiocaesium on the different surfaces, and dose measurements and calculations for different urban environments have pinpointed which surfaces generally contribute most to the dose and consequently are most important to clean. At this point, after nearly a decade, the dose rate from horizontal pavements has decreased by at least a factor of 10, whereas the dose rate from an area of soil or a roof has generally only been halved. The contamination on walls is the most persistent: it has only decreased by 10-20%.

Cesium Radioisotopes↗
PubMed1997

Loss of retroviral gene expression in bone marrow reconstituted mice correlates with down-regulation of gene expression in long-term culture initiating cells.

The question of whether a retroviral vector is expressed in vivo after infection of hematopoietic stem cells remains unpredictable. In this study, we show that a switch off of retroviral sequences can be tested in vitro using the long-term bone marrow culture system. The time kinetics of the down-regulation of retroviral expression in vitro and in vivo have been demonstrated to be similar. The correlation of switch off events in both systems allows for evaluation of retroviral expression in vitro provided the silencing is caused by viral sequences. This approach could be useful for testing vectors for gene therapeutical applications of the hematopoietic system.

Animals↗
PubMed1996

cag, a pathogenicity island of Helicobacter pylori, encodes type I-specific and disease-associated virulence factors.

cagA, a gene that codes for an immunodominant antigen, is present only in Helicobacter pylori strains that are associated with severe forms of gastroduodenal disease (type I strains). We found that the genetic locus that contains cagA (cag) is part of a 40-kb DNA insertion that likely was acquired horizontally and integrated into the chromosomal glutamate racemase gene. This pathogenicity island is flanked by direct repeats of 31 bp. In some strains, cag is split into a right segment (cagI) and a left segment (cagII) by a novel insertion sequence (IS605). In a minority of H. pylori strains, cagI and cagII are separated by an intervening chromosomal sequence. Nucleotide sequencing of the 23,508 base pairs that form the cagI region and the extreme 3' end of the cagII region reveals the presence of 19 ORFs that code for proteins predicted to be mostly membrane associated with one gene (cagE), which is similar to the toxin-secretion gene of Bordetella pertussis, ptlC, and the transport systems required for plasmid transfer, including the virB4 gene of Agrobacterium tumefaciens. Transposon inactivation of several of the cagI genes abolishes induction of IL-8 expression in gastric epithelial cell lines. Thus, we believe the cag region may encode a novel H. pylori secretion system for the export of virulence determinants.

Antigens, Bacterial↗
PubMed1996

Identification of a subdomain within DNA-(cytosine-C5)-methyltransferases responsible for the recognition of the 5' part of their DNA target.

In previous work on DNA-(cytosine-C5)-methyltransferases (C5-MTases), domains had been identified which are responsible for the sequence specificity of the different enzymes (target-recognizing domains, TRDs). Here we have analyzed the DNA methylation patterns of two C5-MTases containing reciprocal chimeric TRDs, consisting of the N- and C-terminal parts derived from two different parental TRDs specifying the recognition of 5'-CC(A/T)GG-3' and 5'-GCNGC-3'. Sequences recognized by these engineered MTases were non-symmetrical and degenerate, but contained at their 5' part a consensus sequence which was very similar to the 5' part of the target recognized by the parental TRD which contributed the N-terminal moiety of the chimeric TRD. The results are discussed in connection with the present understanding of the mechanism of DNA target recognition by C5-MTases. They demonstrate the possibility of designing C5-MTases with novel DNA methylation specificities.

Amino Acid Sequence↗
PubMed1996

Localization of 17beta-hydroxysteroid dehydrogenase and characterization of testosterone in the brain of the male frog.

Several enzymes involved in the formation of steroids of the pregnene and pregnane series have been identified in the brain, but the biosynthesis of testosterone has never been reported in the central nervous system. In the present study, we have investigated the distribution and bioactivity of 17beta-hydroxysteroid dehydrogenase (17beta-HSD) (EC 1.1.1.62; a key enzyme that is required for the formation of testosterone and estradiol) in the brain of the male frog Rana ridibunda. By using an antiserum against human type I placental 17beta-HSD, immunoreactivity was localized in a discrete group of ependymal glial cells bordering the telencephalic ventricles. HPLC analysis of telencephalon and hypothalamus extracts combined with testosterone radioimmunoassay revealed the existence of two peaks coeluting with testosterone and 5alpha-dihydrotestosterone. After HPLC purification, testosterone was identified by gas chromatography/mass spectrometry. Incubation of telencephalon slices with [3H]pregnenolone resulted in the formation of metabolites which coeluted with progesterone, 17alpha-hydroxyprogesterone, dehydroepiandrosterone, androstenedione, testosterone, and 5alpha-dihydrotestosterone. The newly synthesized steroid comigrating with testosterone was selectively immunodetected by using testosterone antibodies. These data indicate that 17beta-HSD is expressed in a subpopulation of gliocytes in the frog telencephalon and that telencephalic cells are capable of synthesizing various androgens, including dehydroepiandrosterone, androstenedione, testosterone, and 5alpha-dihydrotestosterone.

17-Hydroxysteroid Dehydrogenases↗
PubMed1996

[Infrared temperature measurement in the ear canal with the DIATEK 9000 Instatemp and the DIATEK 9000 Thermoguide. Comparison with methods of temperature measurement in other body parts].

UNLABELLED: Temperature of the tympanic membrane is recommended as a "gold standard" of core-temperature recording. However, use of temperature probes in the auditory canal may lead to damage of tympanic membrane. Temperature measurement in the auditory canal with infrared thermometry does not pose this risk. Furthermore it is easy to perform and not very time-consuming. For this reason infrared thermometry of the auditory canal is becoming increasingly popular in clinical practice. We evaluated two infrared thermometers-the Diatek 9000 Thermoguide and the Diatek 9000 Instatemp-regarding factors influencing agreement with conventional tympanic temperature measurement and other core-temperature recording sites. In addition, we systematically evaluated user dependent factors that influence the agreement with the tympanic temperature. MATERIALS AND METHODS: In 20 volunteers we evaluated the influence of three factors: duration of the devices in the auditory canal before taking temperature (0 or 5 s), interval between two following recordings (30, 60, 90, 120, 180 s) and positioning of the grip relative to the auditory-canal axis (0, 60, 180 and 270 degrees). Agreement with tympanic contact probes (Mon-a-therm tympanic) in the contralateral ear was investigated in 100 postoperative patients. Comparative readings with rectal (YSI series 400) and esophageal (Mon-a-therm esophageal stethoscope with temperature sensor) probes were done in 100 patients in the ICU. The method of Bland and Altman was taken for comparison. RESULTS: Shortening of the interval between two consecutive readings led to increasing differences between the two measurements with the second reading decreasing. A similar effect was seen when positioning the infrared thermometers in the auditory canal before taking temperatures: after 5 s the recorded temperatures were significantly lower than temperature recordings taken immediately. Rotation of the devices out of the telephone handle position led to increasing lack of agreement between infrared thermometry and contact probes. Mean differences between infrared thermometry (Instatemp and Thermoguide, CAL-Mode) and tympanic probes were -0.41 +/- 0.67 degree C (2 SD) and -0.43 +/- 0.70 degree C, respectively. Mean differences between the Thermoquide (Rectal-Mode) and rectal probe were -0.19 +/- 0.72 degree C, and between the Thermoguide (Core Mode) and esophageal probe -0.13 +/- 0.74 degree C. DISCUSSION: Although easy to use, infrared thermometry requires careful handling. To obtain optimal recordings, the time between two consecutive readings should not be less than two min. Recordings should be taken immediately after positioning the devices in the auditory canal. Best results are obtained in the 60 degrees position with the grip of the devices following the ramus mandibulae (telephone handle position). The lower readings of infrared thermometry compared with tympanic contact probes indicate that the readings obtained represent the temperature of the auditory canal rather than of the tympanic membrane itself. To compensate for underestimation of core temperature by infrared thermometry, the results obtained are corrected and transferred into core-equivalent temperatures. This data correction reduces mean differences between infrared recordings and traditional core-temperature monitoring, but leaves limits of agreement between the two methods uninfluenced.

Body Temperature↗
PubMed1996

Pharmacokinetics and safety of glimepiride at clinically effective doses in diabetic patients with renal impairment.

The pharmacokinetics, efficacy and safety of glimepiride were investigated in a single- and a multiple-dose open study in patients with non-insulin-dependent diabetes mellitus and renal impairment and an initial creatinine clearance above 10 ml/ min. Patients were divided into three groups with creatinine clearance above 50 ml/min, 20-50 ml/min and under 20 ml/min. Fifteen fasting patients received a single dose of 3 mg glimepiride and serial blood and urine samples were taken over 24 h for pharmacokinetic and efficacy analyses. A further 16 patients received glimepiride over a 3-month period, an initial dose of 1 mg glimepiride being adjusted within the range 1 to 8 mg to achieve good glucose control. Pharmacokinetic evaluation was done on day 1 and after 3 months. Mean relative total clearance and mean volume of distribution of both single (41.6 ml/ min and 8.47 litres, respectively, when creatinine clearance was above 50 ml/min) and multiple doses of glimepiride increased in proportion to the degree of renal impairment (to 91.1 ml/min and 14.98 litres, respectively, when creatinine clearance was below 20 ml/min, single dose), whereas the terminal halflife and mean time remained unchanged. Lower relative total clearance and renal clearance of both glimepiride metabolites correlated significantly with lower creatinine clearance values. Of the 16 patients 12 required between 1 and 4 mg glimepiride to stabilize their fasting blood glucose. Glimepiride was well-tolerated and there were no drug-related adverse events. In conclusion glimepiride is safe, effective and has clearly-definable pharmacokinetics in diabetic patients with renal impairment. The increased plasma elimination of glimepiride with decreasing kidney function is explainable on the basis of altered protein binding with an increase in unbound drug.

Administration, Oral↗
PubMed1996

In vivo and in vitro evidence for the biosynthesis of testosterone in the telencephalon of the female frog.

Neurons and glial cells are capable of synthesizing various steroid hormones, but biosynthesis of testosterone in the CNS has never been reported. The aim of the present study was to demonstrate the synthesis of testosterone in the frog brain. The presence of 17beta-hydroxysteroid dehydrogenase (17beta-HSD)-like immunoreactivity was detected in a population of glial cells located in the telencephalon. Reversed-phase HPLC analysis of brain tissue extracts combined with radioimmunoassay detection revealed the presence of substantial amounts of testosterone and 5alpha-dihydrotestosterone (5alpha-DHT) in the telencephalon where 17beta-HSD-positive cells were visualized. In male frogs, castration totally suppressed testosterone and 5alpha-DHT in the blood and in the rhombencephalon but did not affect the concentration of these two steroids in the telencephalon. Chemical characterization of testosterone in female frog telencephalon extracts was performed by coupling HPLC analysis with gas chromatography-mass spectrometry. Using the pulse-chase technique with [3H]pregnenolone as a precursor, the formation of a series of metabolites was observed, including dehydroepiandrosterone, androstenedione, testosterone, 5alpha-DHT, and estradiol. These data demonstrate the existence of an active form of 17beta-HSD in the frog telencephalon, which is likely involved in testosterone biosynthesis within the brain.

17-Hydroxysteroid Dehydrogenases↗
PubMed1996

Mobilisation kinetics of primitive haemopoietic cells following G-CSF with or without chemotherapy for advanced breast cancer.

BACKGROUND: The objective of this study was to determine the optimal conditions for blood progenitor cell harvest for transplantation, with main emphasis on the mobilisation kinetics of primitive, marrow repopulating cells. PATIENTS AND METHODS: Sixteen patients with advanced breast cancer were treated with 4 cycles of dose escalating FAC chemotherapy (5-fluorouracil, adriamycin, cyclophosphamide) each followed by 10 micrograms/kg/d G-CSF for 13 days. We assessed the number of colony-forming cells (CFC), and estimated the long-term culture initiating cells (LTC-IC) and CD34+ cells during the recovery phase of cycle 1 and 4 of chemotherapy, and during additional periods of G-CSF administration either preceding or following the full course of chemotherapy. RESULTS: The highest peak numbers of CFC per ml of blood (median 10489, range 860-39282) were mobilised after the first cycle of chemotherapy. The lowest peak numbers of CFC were obtained during the recovery phase from cycle 4 (median 4739, range 40-26789). In contrast, the numbers of CD34+ cells per ml of blood were significantly higher in cycle 4 (median 650, range 30-2600 x 10(2)) compared to those of cycle 1 (median 240, range 20-770 x 10(2)). The peak numbers of CFC mobilised by G-CSF before commencement and after the cessation of chemotherapy were equivalent, with a median of 5470 (range 1056-25669) and 5948 (range 2710-38975) per ml of blood, respectively. However, while mononuclear cells (MNC) collected at the days of maximal CFC mobilization following G-CSF administration before or after cycle 1 were similar to normal bone marrow MNCs in their ability to generate haemopoiesis when seeded onto performed irradiated stroma, those collected after cycle 4 or during G-CSF administration after the cessation of chemotherapy were markedly compromised in this respect. CONCLUSIONS: Our results indicate that repeated cycles of FAC chemotherapy followed by G-CSF result in a far lower number of LTC-IC than of CFC mobilised into the circulation. Furthermore although the combination of chemotherapy and G-CSF mobilised the highest numbers if CFC, G-CSF alone pre-chemotherapy was more effective at mobilising LTC-IC. These data indicate that neither the numbers of CFC mobilised nor the numbers of CD34+ cells are necessarily a reliable indicator for the putative marrow repopulating capability of the blood cells mobilised with chemotherapy plus G-CSF.

Adult↗
PubMed1996

Anticoagulant effects and tissue factor pathway inhibitor after intrapulmonary low-molecular-weight heparin.

The present study was designed to investigate the anticoagulant action of inhaled low-molecular-weight (LMW) heparin on the release of tissue factor pathway inhibitor (TFPI) and on antifactor Xa activity, Heptest, activated partial thromboplastin time (APTT) and thrombin clotting time (TCT) in healthy volunteers. 3000 IU (group 1), 9000 IU (group 2), 27,000 IU (group 3) or 54,000 IU (group 4) LMW-heparin were given to 20 healthy volunteers each at 4 weeks intervals by inhalation. For safety reasons a dose escalating design was chosen. APTT and TCT did not change after inhalation of any dose of LMW-heparin as well as all parameters in group 1. In group 2, Heptest coagulation times were prolonged from 18.7 +/- 2.0 s before to 26.1 +/- 5.2 s 6 h and 20.5 +/- 1.9 s 24 h after inhalation and the other parameters remained uneffected. In group 3, S2222 method and the protamine assay increased from 0.01 to about 0.1 IU/ml 6 h after inhalation and returned to normal values after 24 h. TFPI antigen increased from 74.1 +/- 13.9 to 80.5 +/- 14.2 ng/ml 3 h after inhalation. TFPI activity remained unchanged. Heptest coagulation values were prolonged to 42 +/- 7.6 s after 6 h and returned to normal within 72 h after inhalation. In group 4, the following changes were observed: antifactor Xa activity increased to 0.343 +/- 0.196 U/ml after 6 h and normalized after 72 h. The protamine assay detected 0.2 +/- 0.18 U LMWH/ml after 6 h, TFPI antigen increased to 103 +/- 17.9 ng/ml and TFPI activity to 1.14 +/- 0.23 U 3 h after inhalation. All tests were normal after 24 h. Heptest coagulation values increased to 77.5 +/- 11.8 s 6 h after inhalation and normalized after 144 h. The area under the activity time curve of the S2222 method and of the Heptest assay increased with increasing doses (r = 0.677 and r = 0.571), respectively. The calculated elimination half-life of the aXa-effect was 7.5 h using S2222-, Heptest- and protamine assays. The data demonstrate a resorption of LMW-heparin by intrapulmonary route in man. The dose to produce antifactor Xa levels, prolongations of Heptest coagulation values and in releasing TFPI is about ten-fold higher than after subcutaneous administration.

Administration, Inhalation↗
PubMed1995

Desorption of ions from locust tissues. III. Study of a metabolite of A-destruxin using fast-atom bombardment linked-scan mass spectrometry.

The process of the detoxification of A-destruxin into a polar linear peptide in vivo in Locusta migratoria has been demonstrated using both high performance liquid chromatography and negative-ion fast-atom bombardment mass spectrometry. The final structure of the metabolite, after synthesis and comparison of retention time with the component in the crude biological mixture, was elucidated by positive-ion fast-atom bombardment linked-scan mass spectrometry. Diagnostic fragment ions produced by collision-induced dissociation are discussed.

Animals↗
PubMed1995

Intracellular routing of wild-type and mutated polymeric immunoglobulin receptor in hippocampal neurons in culture.

Certain epithelial cells synthesize the polymeric immunoglobulin receptor (pIgR) to transport immunoglobulins (Igs) A and M into external secretions. In polarized epithelia, newly synthesized receptor is first delivered to the basolateral plasma membrane and is then, after binding the Ig, transcytosed to the apical plasma membrane, where the receptor-ligand complex is released by proteolytic cleavage. In a previous work (Ikonen et al., 1993), we implied the existence of a dendro-axonal transcytotic pathway for the rabbit pIgR expressed in hippocampal neurons via the Semliki Forest Virus (SFV) expression system. By labeling surface-exposed pIgR in live neuronal cells, we now show (a) internalization of the receptor from the dendritic plasma membrane to the dendritic early endosomes, (b) redistribution of the receptor from the dendritic to the axonal domain, (c) inhibition of this movement by brefeldin A (BFA) and (d) stimulation by the activation of protein kinase C (PKC) via phorbol myristate acetate (PMA). In addition, we show that a mutant form of the receptor lacking the epithelial basolateral sorting signal is directly delivered to the axonal domain of hippocampal neurons. Although this mutant is internalized into early endosomes, no transcytosis to the dendrites could be observed. In epithelial Madin-Darby Canine Kidney (MDCK) cells, the mutant receptor could also be internalized into basolaterally derived early endosomes. These results suggest the existence of a dendro-axonal transcytotic pathway in neuronal cells which shares similarities with the basolateral to apical transcytosis in epithelial cells and constitute the basis for the future analysis of its physiological role.

Animals↗