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H J Dieterich

Publications and source records attributed to H J Dieterich.

At least 19 recordsLinked to original sources
PubMed2005

[Effects of reduced shear stress on inflammatory reactions in vitro. Effects of pathological flow conditions on leukocyte-endothelial interactions and monocyte tissue factor expression in human cell cultures].

BACKGROUND: During malperfusion and inflammation leukocyte adhesion is common. The purpose of this study was to examine the effects of reduced shear stress on leukocyte-endothelial interactions and subsequent inflammatory reactions such as up-regulation of tissue factor. METHODS: Isolated neutrophils and monocytes were co-incubated with human umbilical venous endothelium at 0-3 dynes/cm(2) in a flow chamber. Adhesion and tissue factor expression on adherent leukocytes were examined at various flow conditions. RESULTS: At 2-3 dynes/cm(2) adhesion occurred only on TNFalpha-activated endothelium. Below 1 dyne/cm(2) similarly increased adhesion was also observed on non-activated endothelium. As was observed for leukocyte adhesion, these shear stress-dependent cell interactions also resulted in an up-regulation of tissue factor on adherent monocytes from non-activated co-cultures. CONCLUSION: Apart from additional activators of inflammation, reduced shear forces may directly contribute to inflammation.

Cell Adhesion↗
PubMed2004

Release of S(+) enantiomers in breath samples after anaesthesia with isoflurane racemate.

BACKGROUND AND OBJECTIVE: Isoflurane is a chiral volatile anaesthetic, routinely administered as racemate. It has a low metabolic rate and is mostly eliminated via respiration. In blood samples, S(+) enantiomers are found in greater proportion in the days immediately after administration of isoflurane racemate whereas the ratio in breath samples is unknown. METHODS: Breath and blood samples were drawn immediately after recovery and daily up to 19 days after operation from patients undergoing anaesthesia with isoflurane racemate. The percentage of isoflurane enantiomer was determined by gas chromatography mass spectrometry in blood and thermodesorption gas chromatography mass spectrometry in breath samples. RESULTS: In breath samples, there were significant differences in S(+) enantiomers at all time points compared to the racemate. During the early postoperative phase, the percentage of S(+) enantiomers were significantly enhanced whereas 5 days after surgery predominantly R(-) enantiomers (50.41%) were detected in the breath samples. Also in blood samples a statistical significant accumulation of the S(+) enantiomer was noted between days 1 and 5 compared to isoflurane racemate blood control. S(+) enantiomers were significantly higher in blood compared to breath samples and was most evident on the third day after surgery (51.43%). CONCLUSIONS: During the first days after application of isoflurane racemate, the percentage of S(+) enantiomers are higher in breath and blood samples of patients. We suggest that resorption and/or redistribution of enantiomers are responsible for the different kinetics of isoflurane enantiomers.

Anesthetics, Inhalation↗
PubMed2003

[Aortocaval compression syndrome].

Aortocaval compression syndrome (supine hypotensive syndrome) represents a common complication mainly of late pregnancy, although the syndrome has been described to occur as early as 16 weeks of gestation. The nature and severity of symptoms range from unspecific complaints to severe maternal hypotension, loss of consciousness, cardiovascular collapse, and consecutive fetal depression. Predominantly, the syndrome is provoked by placing the parturient supine. Since supine positioning is required for diverse diagnostic and therapeutic procedures in obstetrics, these involve increased risk of aortocaval compression. For the anesthetist, cesarean section is most relevant, because of the coincidence of several risk factors. The following article begins by reviewing the pathophysiology of the syndrome, known risk factors and anesthesiological procedures that predispose to the syndrome. The second part is concerned with prophylactic measures and therapeutic options, together with the discussion of a clinically practicable algorithm.

Adult↗
PubMed2002

Accumulation of S(+) enantiomer in human beings after general anaesthesia with isoflurane racemate.

BACKGROUND AND OBJECTIVE: Isoflurane is a chiral, volatile anaesthetic with low metabolic rate (0.17%) that is routinely administered in its racemic form. Knowledge about the distribution of the enantiomers in human beings may give some important information about the understanding of the mechanisms of volatile anaesthetics. METHODS: Blood samples were drawn immediately after tracheal extubation and daily up to 8 days postoperatively from patients undergoing general anaesthesia with isoflurane racemate. The enantiomer enrichment of isoflurane was determined by headspace gas chromatography-mass spectrometry. RESULTS: At all time points, there was a statistically significant accumulation of the S(+) enantiomer in blood, especially at days 2 (52.01%) and 7 (52.1%). Separate analysis of obese patients or in a small group of patients with co-existing lung disease did not show any difference to the total population. In addition, duration of anaesthesia did not influence the enantiomer concentrations. CONCLUSIONS: We suggest that a slower association and dissociation rate is responsible for the S(+) enrichment.

Aged↗
PubMed2001

Inducible expression of inflammatory chemokines in respiratory syncytial virus-infected mice: role of MIP-1alpha in lung pathology.

Lower respiratory tract disease caused by respiratory syncytial virus (RSV) is characterized by profound airway mucosa inflammation, both in infants with naturally acquired infection and in experimentally inoculated animal models. Chemokines are central regulatory molecules in inflammatory, immune, and infectious processes of the lung. In this study, we demonstrate that intranasal infection of BALB/c mice with RSV A results in inducible expression of lung chemokines belonging to the CXC (MIP-2 and IP-10), CC (RANTES, eotaxin, MIP-1beta, MIP-1alpha, MCP-1, TCA-3) and C (lymphotactin) families. Chemokine mRNA expression occurred as early as 24 h following inoculation and persisted for at least 5 days in mice inoculated with the highest dose of virus (10(7) PFU). In general, levels of chemokine mRNA and protein were dependent on the dose of RSV inoculum and paralleled the intensity of lung cellular inflammation. Immunohisthochemical studies indicated that RSV-induced expression of MIP-1alpha, one of the most abundantly expressed chemokines, was primarily localized in epithelial cells of the alveoli and bronchioles, as well as in adjoining capillary endothelium. Genetically altered mice with a selective deletion of the MIP-1alpha gene (-/- mice) demonstrated a significant reduction in lung inflammation following RSV infection, compared to control littermates (+/+ mice). Despite the paucity of infiltrating cells, the peak RSV titer in the lung of -/- mice was not significantly different from that observed in +/+ mice. These results provide the first direct evidence that RSV infection may induce lung inflammation via the early production of inflammatory chemokines.

Animals↗
PubMed1999

Headspace gas chromatography-mass spectrometry analysis of isoflurane enantiomers in blood samples after anesthesia with the racemic mixture.

Several in vivo and in vitro studies on the stereoselective potency of isoflurane enantiomers suggest beneficial effects of the (+)-(S)-enantiomer. In order to detect possible differences in the pharmacokinetics of isoflurane enantiomers, a clinical study of 41 patients undergoing general anesthesia maintained with racemic isoflurane was performed. The isoflurane enantiomers were analyzed in blood samples drawn before induction, at cessation (day 0), and up to eight days after isoflurane anesthesia (day 1-8). A multipurpose sampler (Gerstel MPS) was used for the headspace gas chromatography-mass spectrometry (GC/MS) analysis, and it was combined with a cold injection system (Gerstel CIS 3) for coldtrapping, enrichment, and focusing of the analyte. The enantiomer separation was achieved by using a capillary column coated with octakis(3-O-butanoyl-2,6-di-O-pentyl)-gamma-cyclodextrin (Lipodex E) dissolved in the polysiloxane PS 255. Detection was done in the selected ion monitoring mode with ions m/z 117 and m/z 149. An enrichment of (+)-(S)-isoflurane in all blood samples drawn after anesthesia was found. The highest enantiomer bias, up to 52-54% (+)-(S)-isoflurane as compared to 50% for the racemate, was observed on day 2 for most of the patients. Furthermore, quantification of isoflurane in blood samples of five patients was done by enantiomer labeling, employing enantiomerically pure (+)-(S)-isoflurane as internal standard. The isoflurane concentration decreased rapidly from 383 nmol/ml to 0.6 nmol/ml (mean values) eight days after anesthesia. The present study shows differences in the pharmacokinetics of isoflurane enantiomers in man. However, it is not possible to distinguish between enantioselective distribution and enantioselective metabolism, if any.

Anesthesia, Inhalation↗
PubMed1999

Certain batches of albumin solutions influence the expression of endothelial cell adhesion molecules.

OBJECTIVE: Increased levels of soluble adhesion molecules, a decreased PO2/FIO2 ratio and a tendency to worsened outcome have been reported following the use of human albumin in critical illness. The reasons are not yet understood. Since albumin solutions have previously been shown to contain proinflammatory mediators, a direct upregulation of adhesion molecules by contaminated batches may explain these findings. To examine this, we studied the effects of different albumin preparations on endothelial cell adhesion molecules in vitro. DESIGN: Experimental study. SETTING: Laboratory for cell biology. METHODS: Human umbilical venous endothelial cell cultures (n = 4) were incubated for 6 h at 5 mg/ml with four different human albumin solutions (HA1-4) from different manufacturers. Medium served as the control. Using flow cytometry, the effects on E-selectin, ICAM-1 and VCAM-1 expression were determined on unstimulated cells and on cells stimulated with tumour necrosis factor alpha at 0.5 ng/ml for 4 h. MEASUREMENTS AND RESULTS: On unstimulated cells, HA1 and HA4, two different batches from the same manufacturer, increased ICAM-1 by 22% and 15%, respectively. After stimulation, both solutions resulted in a 19% increased expression of E-Selectin. In addition, HA4 decreased VCAM-1 on stimulated cells (p < or = 0.05). Two albumin preparations from other manufacturers did not produce significant effects. CONCLUSIONS: Some albumin solutions directly modulate adhesion molecule expression on endothelial cells. This may, at least in part, explain the previous finding of increased soluble adhesion molecules and a decreased PO2/FIO2 ratio in critically ill patients undergoing volume replacement with human albumin.

Albumins↗
PubMed1999

Methemoglobinemia after axillary block with bupivacaine and additional injection of lidocaine in the operative field.

Methemoglobinemia may occur after the administration of various drugs, including some local anesthetics. We report a patient with chronic renal failure and ischemic heart disease who developed clinically significant methemoglobinemia after an axillary block with bupivacaine and additional injection of lidocaine in the operative field. Although the two local anesthetics usually do not cause methemoglobinemia, we suspect that the displacement of lidocaine from protein binding by bupivacaine, in combination with metabolic acidosis and treatment with other oxidants, was the reason for the development of methemoglobinemia.

Acidosis↗
PubMed1999

Elimination of meropenem by continuous hemo(dia) filtration: an in vitro one-compartment model.

Meropenem is a carbapenem antibiotic with a wide spectrum of activity against most gram positive and gram negative bacteria including anaerobes. Dose adjustments are necessary during continuous renal replacement therapies of acute renal failure. This in vitro study was conducted to investigate the influence of different filter materials, surface areas (AN-69 0.6 m2 and 0.9 m2, polysulfone 0.75 m2, polyamide 0.6 m2), and increasing flow rates (from 3.3 - 26.7 ml/min) on the elimination of meropenem in an in vitro continuous hemo(dia)filtration model. Meropenem was measured using HPLC with UV-detection. While the clearance increased proportionally to increasing dialysate flow rates in filters with a surface area of 0.9 m2, a peak clearance was reached in the small filters at flow rates of 10.0 ml/min (polyamide 0.6 m2) and 18.3 ml/min (AN-69 0.6 m2), when tested under the same conditions. This indicated incomplete dialysate saturation due to the diminished time available for meropenem to equilibrate with the dialysate solution. No adsorption to either of the tested membranes was detected. Dosage recommendations derived from clinical studies might be appropriate when different filter materials, but similar operational settings of the continuous replacement therapy, are applied. Reduction of the recommended dose might be necessary, when renal replacement therapies with lower flow rates and/or filters with smaller surface areas are carried out.

Anti-Bacterial Agents↗